Potential Role of Epigenetic Modulation in Prevention or Therapy for Diabetic Kidney Disease-Still a Dream or a Reality –A Systematic Review

Kulvinder Kochar Kaur1*, Gautam Allahbadia1 and Mandeep Singh2

1Centre for Human Reproduction, India

2Obstetrics and Gynaecology, DNB, Rotunda-A Centre for Human reproduction, India

3Swami Satyanand Hospital, India

Correspondence: Kulvinder Kochar Kaur, Scientific Director, Dr Kulvinder Kaur Centre for Human Reproduction, 721, G.T.B. Nagar, Jalandhar, Punjab, India. E-mail: kulvinder.dr@gmail.com

Citation: Kaur KK, Allahbadia G and Singh M. Potential Role of Epigenetic Modulation in Prevention or Therapy for Diabetic Kidney Disease-Still a Dream or a Reality –A Systematic Review. Journal of Diabetic Nephropathy and Diabetes Management. 2021;1(1):1-6.

Copyright: © 2021 Kaur KK, et. al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Received On: 9th March,2021   Accepted On: 30th April,2021   Published On: 10th May,2021

Abstract

One of the diseases growing at a very rapid pace is the Diabetic Kidney Disease (DKD) all over the world. Earlier we reviewed the pathophysiology of type1 and 2 DM, we have concentrated on avoiding the complications related to DM like how to treat diabetic neuropathy (DN), All complications utilizing ECV’S, then emphasis of Sodium–glucose cotransporter 2 (SGLT2) inhibitors on cardiovascular outcome trials (CVOT) trials, role of Vitamin D in avoidance of DN. Here we further reviewed the role of epigenetics influence on DKD generation. Epigenetics controllers regulate gene expression and recently a hype of them might be therapeutic targets. Thus, here we conducted a systematic review utilizing search engine PubMed, google scholar and others utilizing the MeSH terms like DKD; Epigenetics; DNA methylation; Histone post-translational modifications; Histone acetylation; Histone crotonylation; Histone β-hydroxybutyrylation; Apelin; curcumin analogs; Apabetalone from 1950 to 2021 till date. We found a total of 300 articles out of which we selected 150 articles for this review. No meta-analysis was done. Further readers of epigenetic marks like BET proteins were therapeutic targets. Hence BD2 selective BET inhibitor and Apabetalone was the first Epigenetics controllers that have gone via phase-3 Clinical trial in DKD) with the endpoint of Kidney function. Directly one can manipulate the Epigenetics prop by pharmacological manipulation of particular enzymes implicated along with therapeutic utilization of needed substrates. Moreover, indirect nephroprotective actions on Epigenetics control. Here HDAC inhibitors like Valproic acid (VPA), trichostatin A (TSA), with Na butyrate manipulating Histone-β-hydroxy butyrylation, curcumin analogues like C66 and C646. Further significance of SGLTi is detailed.

Keywords: DKD; Epigenetics, Histoneacetylation; Histone crotonylation; Apabetalone; BET Proteins; BRD’s

Introduction- Diabetic Kidney Disease Outcomes

As per the Global burden of Disease (GBD) study, the total weight of Non-Communicable Diseases (NCD) is escalating, and explaining 73% of Global deaths [1]. Actually 50% of total deaths Globally (28.8 million), were secondary to 4 risk factors namely; hypertension, Diabetes mellitus (DM); Smoking as well as escalated body mass index (BMI) [2]. The Total prevalence of DM is also escalating by resulting in Diabetic Kidney Disease (DKD), that represents the greatest stimulator of Chronic Kidney Disease (CKD) [1]. Those patients presenting with DKD- CKD or end stage renal Disease (ESRD), possess greater mortality rates in contrast to non-DKD patients [3]. CKD due to type1 as well as type2 DM led to 2.9m (2.4-3.5) disability adjusted life years (DALYs) as well as 8.1m (7.1-9.2) DALYs [1]. Deaths throughout world secondary to DKD were calculated to be 219, 451 in 2017 [1]. While mortality secondary to DKD is escalating, the other etiologies of CKD continue to persist relatively at a stable stage, that points to an escalation of prevalence in DKD- CKD, that has been out increasing rest types of CKD [1]. By 2040 it is anticipated that CKD would be the 5th commonest etiology of death world over, out of which DKD is the 1st global etiology of CKD [4]. This DKD amount is escalating at a much rapid pace in low as well as middle income countries act high income countries [1]. Thus, enhancing the clinical DM as well as DKD might translate into the manipulation of present global mortality rates.

DKD gets initiated by enhanced glomerular filtration rate (GFR) which probably occurs secondary to hyperglycaemia–i) stimulated proximal tubular impairment as well as ii) absence of tubulo glomerular feedback [5]. iii) Subsequent to that escalating, proteinuria that gradually propagates to overt proteinuria along with deletion of kidney function that ends in ESRD after approximately 10yrs. Hence primarily DKD was believed to be the proteinuric form of CKD as well as despite the description of non-proteinuric CKD recently, proteinuric patients possess much poorer results [6], which makes podocyte damage as well as deletion [7, reviewed in ref 8] as the crucial factor in aiding to propagation of DKD (Figure 1). High glucose amounts as well as haemodynamic alterations secondary to proximal tubular cells glucose overload are the critical initiators of podocyte damage vascular as well as   tubular cells, albuminuria also injure tubular cells, reducing the nephroprotective along with anti-aging protein Klotho, along with induction of pro inflammatory as well as profibrotic events [9-11]. Fibrosis occurs early, with earlier properties of thickening of basement membrane (BM) but finally developing into glomerulosclerosis as well as interstitial fibrosis. Fibrinogenic factors like transforming growth factorβ1 (TGF-β1) as well as processes like incomplete epithelial–mesenchymal transformation (EMT) aid in escalated extracellular matrix (ECM) generation.

Figure 1: Courtesy ref no-8-Key pathophysiological features of Diabetic Kidney Disease (DKD), emphasizing key processes and cell types as well as some of the multiple molecules involved. ECM: increase extracellular matrix. EMT: epithelial-to-mesenchymal transition.

Sodium–glucose cotransporter 2 (SGLT2) inhibitors, that is the oral hypoglycaemic agents that regulate glucose by reduction of glucose reabsorption in proximal tubules along with escalating glycosuria were illustrated to escalate kidney along with C cardiovascular outcomes (CVOT) [reviewed by us in type1 diabetes type2 diabetes, as well as heart failure (HF) [5, 12]. Specifically, Canagliflozin enhanced kidney results in patients presenting with DKD [13]. Consequently, most of the clinical guidelines advocate the use of SGLT2 inhibitors as a preferred oral antidiabetic in DM patients who have been at high CVS or renal risk [5, 14]. The present posit is that generalized utilization might enhance the poor outcome of DKD patients. Still residual of cardiovascular system (CVS) demise or CKD propagation [5]. Earlier after reviewing the pathophysiology of type1 as well as type2 DM, we have concentrated on avoiding the complications related to DM [15-23]. Further we had reviewed role of epigenetics in preeclampsia and IUGR [24]. After having reviewed the role of Vitamin D in alleviation of DKD [25], here we reviewed the role of epigenetics in trying to avoid the generation of complications like DKD.

Methods

Here we conducted a systematic review utilizing search engine utilizing the PRISMA Guidelines PubMed, google scholar; web of science; embase; Cochrane review library utilizing the MeSH terms like DKD; Epigenetics; DNA methylation; Histone post-translational modifications; Histone acetylation; Histone crotonylation; Histone -β-hydroxy butyrylation; Apelin;curcumin analogs; Apabetalone; BET Proteins; BRD’s; TET; BMP’s; sodium butyrate from 2010 to 2021 till date.

Results

We found a total of 300 articles out of which we selected 139 articles for this review. No meta-analysis was done (Figure 2).

        Figure 2: Selection Criteria

Epigenetic Control of Gene Expression

The heritable alterations in Gene expression patterns which are not secondary to a particular DNA nucleotide sequence itself is what Epigenetics by definition implies. Information regards to Epigenetics is both heritable along with self-perpetuating along with is dynamic as well as reversible with alteration in environment. The major along with controllers are DNA methylation, histone post-translational modifications [26]. The best kind of histone post-translational modifications with reference to kidney disease are lysine DNA acetylation, along with crotonylation (Figure 2). Further when trying to talk in context of DKD, histone-β-hydroxy butyrylation might be Intriguing. In addition, >100 histone modifications have been detailed, of which 67 had been in a single article as well as newer modifications keep getting detailed like acetylation [27, 28]. Certain authors further add miRNAs, although they are not getting reviewed here. Further Epigenetic readers which isolate as well as interpret the Epigenetic signals are crucial constituents of this system.

DNA methylation

DNA methylation refers to an enzymatic event which implicates the covalent transfer of methyl (CH3) group from S-adenosylL methionine (SAM)to the 5-carbon of cytosine residues on CpG sites [29] mainly, the ones present on CpG islands (80-1000 nucleotides) existing on the gene promoter or in the 1st exons [30]. CpG methylation in gene promoters is correlated with transcriptional inhibition secondary to recruiting co-repressors along with interfering with the transcription factor binding through packaging of chromatin [31]. Nevertheless, DNA methylation in the gene body facilitates expression of gene via manipulation of transcription elongation along with RNA splicing [32].

The profiles of methylation are tissue particular along with decide the fate of the cell, that explains the separate cell identities along with their expression patterns in spite of the same genome. DNA methyltransferases (DNMT) are the ones that catalyze these events. DNMT1 regulates the sustainance of methylation marks that work on hypermethylated DNA at the time of DNA replicating itself or its repairing somatic cells, whereas DNMT3a is present more abundantly in view of its correlation with normal cell differentiation, whereas DNMT3b is usually missing in adult tissue as well as  is necessary for early generation [30].This way the methylation patterns at the time of embryonic generation gets proven by the DNMT3 subfamily along with get further sustained via somatic divisions through DNMT1 in differentiated cells [33].

Initially Epigenetic prints were thought to be relatively stable marls till Ten–eleven translocation (TET) family proteins that are implicated in DNA demethylation. Oxidation of 5methyl cytosine (5mc) to generate 5-hydroxy methyl cytosine (5hmc) gets catalyzed by these enzymes as well as other following oxidized products. Enzymes responsible for DNA repair excise these oxidized products as well as incorporate the unmethylated cytosines. DNA demethylation can further take place passively by avoidance of DNMT1 binding at the time of DNA replication [26, 34].

Histone Methylation

 Methylation implicates the covalent methyl groups getting added to lysine (Lys) a as well as arginine (Arg) residues of Histones. This event is controlled by a lot of enzymes acting in a coordinated fashion for regulation of gene expression, along with stability of the genome [35]. For Histone Methylation, Histone Methyltransferases (HMTs), that are categorized as lysine particular (KMTs) as well as arginine particular (PRMTs) Methyltransferases. Lys might be mono, di-ortri methylated, while Arg might be symmetrically or a symmetrically mono or de methylated [36]. KMTs get grouped in 2 classes depending on their catalytic domain structure, the SET domain possessing enzymes, as well as the DOT1L/KMT4 family [36].

Separate potential influence occurs on transcription occur secondary to Histone Methylation. Arg Methylation facilitates activation of transcription, whereas Lys Methylation might stimulate or suppress transcription based on the Methylation area [37]. Like mono Methylation, dimethylation, trimethylation of H3 at Lys4 (H3K4m1/2/3) have a correlation with transcriptionally active genome areas, whereas trimethylation of H3 at Lys9 or at Lys27 (H3 K9m3/ K27m3) as well as trimethylation of H3 at Lys20 (H3 K20m3) are enhanced in suppressed areas,

Initially Histone Methylation was believed to be stable till the documentation of Lys particular demethylase (KDM1A) in 2004. Hence Histone Lys demethylase (KDM) along with arginine demethylase are the enzymes that delete methyl manipulations from Lys/Arg respectively.

Histone Acetylation

Histone acetylases (HAT’s), like CREB –binding protein (CBP), as well as p300, shift an acetyl group (COCH3) from acetyl-Coenzyme A (acetyl –CoA) to Lys residues in in histones, neutralizing their positive charge along with conferring relaxation to the chromatin [39]. With the knowledge of requirement of acetyl-CoA, Histone Acetylation mainly might be controlled metabolically by the amount of acetyl-CoA that is available [39]. Histone Acetylation mainly takes place in promoter as well as enhancer of the target genes, facilitating their expression. There are 4 classes of histone deacetylales (HDACs) which delete the acetyl groups. Class 1HDAC exist ubiquitously as nuclear enzymes which control cell survival along with proliferation. Class I1HDAC are existent in nuclei as well as cytoplasm, possessing roles that are tissue particular. Class II1HDAC’s are Sirtuins, which control a lot of physiological as well as pathological parts. Just 1 Class IV HDAC’s, namely HDAC 11.

Histone Crotonylation

Histone lysine crotonylation ((Kcr) has been a post transcription manipulation of Histone that has been detailed recently in which a crotonyl group gets added from crotonyl- CoA, to Lys residues, that possesses a key significance regards to global control of transcription in mammalian cells [28, 39]. Kcr has the significance of having been evolutionally preserved as well as points to active promoters or potential enhancers, possessing a separate genomic pattern as compared to Histone lysine acetylation (Kac), though the influence on gene expression remains ill understood, since it can either stimulate or suppress transcription of genes [28, 40]. Despite having common enzyme controllers with Kac, Kcr although both possess separate mode of action along with function [28, 41]. Hence acetytransferases like CBP, or the evolutionally preserved Males absent on the first. (MOF) possess cronoyl transferases action, nevertheless, catalysis stimulated by CBP causing Histone crotonylation possesses direct stimulatory effect on transcription at a larger degree as compared to Histone acetylation [41]. Further HDACs, particularly Class 1HDAC, also possess de cronoylase action, despite Kcr possessing greater resistance to deacetylation as compared to Kac, that validates the idea of marked transcription [42-46]. Kcr is further controlled by metabolic pathways which regulate the availability of crotonate [43]. Crotonate represents the short chain fatty acids (SCFA) precursor of cronoyl-CoA, a chemical event that gets catalyzed via Acyl CoA Synthetase SC Family Member2(ACSS2) [41]. Crotonylate availability in cultured kidney cells was correlated with escalated or reduced gene expression of the genes implicated in pathogenesis of kidney disease [43].

Histone-β-hydroxybutyrylation

β-hydroxy butyrate (BHB) represents the most enriched ketone body, accounting for 70-80% of the total as well as gets generated mainly in liver through fatty acid (FA) metabolism in conditions where glucose amount is considerably less along with body requires energy, like at the time of dietary restriction, fasting periods or continued extensive exercise. Further more BHB supplementation confers protection against oxidative stress (OS), besides influencing anti-inflammatory along with anti-oxidative characteristics [44, 45]. Large amounts of BHB, in cells promote lysine β-hydroxy butyrylation (Kbhb) that is a recently detailed as histone post-translational modification [46] as well as other proteins like p53 [47]. In p53 Kbhb reduces p53 action in view of it replacing an acetyl mark [47]. The implication of BHB along with Kbhb on various molecular events in separate cells along with tissues have been evaluated in minimal studies. In livers from either mouse who have been fasted for long time or with streptozocin stimulated diabetic ketoacidosis, along with human cells that got cultured with BHB, Histone Kbhb marks are associated with active gene promoters of the metabolic pathways stimulated by ketone acids. This was the 1st instance when Histone Kbhb was isolated as a new method of Epigenetics control which controls physiology of cells [46]. Ketogenesis is further a metabolic pathway needed for the generation of CD8+TCells, when BHB facilitates β-hydroxy butyrylation of Lys 9 in H3 (H3K9bhb) as well as this gets correlated with upregulation of gene expression of Foxo1 as well as Ppargc1a, that in cooperation upregulate Pck1 expression [48]. Moreover, BHB stimulates the inflassome as well as the β-hydroxy butyrylation in Histone H3 expression of correlated inflammatory genes via Histone Kbhb decreasing inflammatory responses as well as blood pressure (BP) [49]. Lastly BHB stimulates β-hydroxy butyrylation in Histone H3(H3K9bhb) of the adiponectin gene along with adiponectin expression in adipocytes [50]. Since adiponectin possesses anti- inflammatory along with anti-atherogenic characteristics [51]. BHB might confer protection via manipulation of Epigenetic control [50].

β-hydroxy butyrylation of the Lysine residues gets catalyzed through CBP along with p300 [47, 52]. Conversely, SIRT3 along with HDAC3 display robust action in deletion of β-hydroxy butyryl groups from Lysines in Histones. Nevertheless, SIRT3 does not possess the capacity of deletion of β-hydroxy butyryl groups marks that is bordered by glycine in contrast to HDAC3, that deletes β-hydroxy butyryl groups marks, irrespective of the nearby glycines. SIRT 1 along with SIRT22 might further catalyze β-hydroxy butyryl grouphydrolysis from lysines in Histones [53] (Figure 3and 4).

Figure 3. Courtesy ref no-8-Enzymatic regulation of epigenetic histone modifications most relevant in diabetic nephropathy. (A) Lysine mono-, di- or tri- methylation is mediated by lysine methyl-transferases (KMT) and demethylation by lysine demethylases (KDM). (B) Histone acetylation, crotonylation and β-hydroxybutyrylation share some enzymes such as the histone acyl transferase CBP and combinations of p300 and MOF, and some histone deacetylases (HDACs) that may also remove other acyl groups. CBP: CREB-binding protein; MOF: Males absent on the first.

Figure 4: Overview of epigenetic modifications and mediators in DKD.

Courtesy ref no-149-Chromatins are subjected to epigenetic regulations, including DNA methylation, posttranslational histone modifications, and microRNA (miRNA) and long noncoding RNAs (lncRNAs)-mediated gene regulation. miRNAs typically affect mRNA expression at post-transcriptional level by targeting the 3’-untranslated regions of mRNA in the cytoplasm. DNA methylation and histone modification influence gene regulation in the nucleus. These molecular processes are intricately regulated by various epigenetic enzymes as depicted. LncRNAs can regulate gene expression through either nuclear or cytoplasmic mechanism. DNMT, DNA methyltransferases; HMT, histone methyltransferases; HDM, histone demethylase; HAT, histone acetyltransferases; and histone deacetylases (HDACs).

Epigenetic Readers

Readers isolate Epigenetic modifications as well as impact gene expression in a markedly particular way for the residues as well as the extent of Histone Methylation (chromodomains as well as bromodomain proteins) or acetylation [35, 54, 55]. Bromodomains represent a markedly preserved motif of 110 amino acids with proteins crosstalk function. They are implicated in Chromatin remodeling as well as transcriptional control [55]. The bromodomain as well as extra terminal (BET) protein family (BRD2, BRD3, BRD4 along with BRDT) are Epigenetic Readers, which through bromodomain (BD) 1 as well as 2 control gene transcription by binding to acetylated lysine residues.

Diabetic Kidney Disease as well as DNA Methylation

Various methylation pattern in critical controlling genes is believed to aid in the generation of DKD along with particular enzymes involved in the histone methylation, might participate in Diabetic Nephropathy (Figure 4) [56]. This is further observed in rest of the CKD’s. Tubules from human CKD kidneys (50% with DKD) display maximum of the differentially methylated areas were existing in enhancers as well as associated with the escalated expression of critical fibrotic genes [57]. Additionally, methylation in the cytosine phospho-guanine (CpG) dinucleotide islands of various genes implicated in pathways that facilitate epithelial-mesenchymal transition (EMT), were correlated with kidney function deletion in CKD patients (50% in DKD also) [58].

Changes in DNA methylation both in intrinsic kidney cells as well as in leukocytes might aid in DKD propagation. In case of proximal tubules from db/db mice, a mouse model of leptin deficiency that has been utilized in the form of a type2 Diabetes (T2D), genes implicated in glucose metabolism had aberrant DNA methylation [59]. Kin to this cultured proximal tubular cell that got exposure to large amounts of glucose amount, as well as kidneys from mice with type1 streptozotocin induced Diabetes displayed DNA hypomethylation of MIOX, that was correlated with escalated, binding of the transcription factor SP1 at the promoter of genes implicated in oxidative stress, hypoxia as well as fibrosis [60]. Anormal DNA methylation patterns were further seen in cultured podocytes that got exposed to High glucose amounts [61]. Matrix metalloproteinase 9 (MMP9) promoter area in podocytes possessed demethylated CpG areas, along with this escalated glucose decreased MMP9 promoter methylation, hence escalating its promoter action, aiding in podocytes EMT [62]. Transcriptional suppression of the transcription factor Kruppel-like factor4 (KLF4) in podocytes was correlated with escalated DNA methylation at the nephrin (Nphs1) promoter, resulting in podocytes apoptosis as well as proteinurea in db/db mice, while KLF4 over expression possesses renal protection actions [63]. Kat5 modulated DNA repair is necessary for podocyte sustainance as well as associated with alterations in DNA methylation status [64]. Intriguingly interaction among proximal tubules along with podocyte might be based on Epigenetic modes. Tubules particular over expression of SIRT1- stimulated hypermethylation of the Cldn1 gene (since SIRT deacetylases along with activates DNMT1) resulting in downregulation of the tight junction proteins Claudin 1 in podocytes, that conferred protection against albuminuria [65]. High glucose-stimulated cytoplasmic translocation of DNMT3a in human mesangial cells, that resulted in decrease in nuclear amounts, hence promoting CTGF hypomethylation [66]. Actually, escalated Trim 13 promoter methylation aided in downregulation of the expression of the E3 ubiqitin ligase TRIM13 in DKD glomeruli, that got correlated with escalation of mesangial collagen generation [67]. DNA Methylation might further aid in manipulating the expression of transforming growth factorβ 1 (TGF-β1)-controlled genes that are implicated in the etiopathogenesis of DKD [56, 68]. Actually, Reactive oxygen species (ROS) manipulate DNA methylation [69], as well as via ROS-based DNA methylation of the Tgfb1 locus aid in mesangial fibrosis in DKD [70]. In case of db/db mice as well as in mesangial cells cultured along withescalated glucose, expression of TET2 demethylase results in demethylation of transforming growth factorβ 1 (TGF-β1) promoter along with escalated TGF-β1 expression [76].

DNA Methyltransferase (DNMT) inhibitors, like 5azacytidine (5-aza) as well as 5-aza 20-deoxy cytidine (5-aza-2de, decitabine) stimulate DNA hypomethylation which actually might be of advantage in kidney diseases [26, 71]. They decreased albuminuria in db/db mice [72] as well as 5-aza brought back the erythropoietin generation in fibrotic murine Kidneys, though this was not evaluated in DKD in particular [73]. In that context, Kidney’s fibrosis has been a crucial in learning about DKD propagation as well as TGF-β1 stimulated Kruppel-like factor4 promoter hypermethylation as well as downregulation of KLF4 in cultured human tubular cells was ameliorated with decitabine [74], that further avoided escalated glucose stimulated repression of regulator of calcineurin1 (RCAN 1) expression in cultured podocytes [75]. RCAN 1 confers protection on podocyte. Suppression of RCAN 1 mRNA expression in humans along with experimental glomeruli as well as knockout of Rcan 1 exaggerated albuminuria along with podocyte injury in proteinuric mice [27]. Aberrant DNA methylation observed in the peripheral immune cells could be implicated in Diabetic propagation. Upregulation of DNMT1 was observed in the peripheral immune cells belonging to Diabetic patients along with associated with inflammatory response [76]. Expression of DNMT1 was further escalated in immune cells from db/db mice as well as 5-aza therapy decreased the hypermethylation of negative controllers of mTOR activation, resulting in inactivationof mTOR pathway in addition to decreasing renal inflammation [76].

More substances might implicate alterations in DNA methylation indirectly or via manipulation of the expression as well as /or action of DNMT’s .Hence minimally the nephro protection action of bone morphogenetic protein-7 (BMP7) supplementation in variety of models of Kidney fibrosis, that includes streptozotocin induced Diabetes kidney disease, got mediated by restoration of TET-3 –mRNA expression as well as protein amounts repressed by TGF-β, leading to TET-3 modulated restoring of the antifibrotic gene Rasal1. In this context, abnormal Rasal1 methylation as well as hydroxy methylation got rectified by BMP7 [78], that is a substance that confers protection to various models of CKD, that includes Diabetic Nephropathy(DN) [79].Probable mode of this protection might be the restoration of Klotho expression by decreasing the typical Klotho promoter hypermethylation, that is visualised in CKD [80].This was associated with a reduction in expression of DNMT1/ DNMT3a. Klotho represents a protein obtained from Kidney possessing antiaging as well as nephroprotection actions [81].

Epigenetic alterations can further aid in differentiating among rapid propagators from those who will continue to be stable or evaluating separate responses to therapy [58, 82]. Like 5 DNA methylation (DNAm) areas discriminated Diabetics who received statin therapy or not in evaluation of cohort studies involving 8270 patients in an epigenome wide association study in blood.2 areas were correlated with a glycaemic trait or T2D [83].

DNMT’s can further be controlled by miRNAs.In the proximal tubular cells that had received escalated glucose, miR 29b downregulation stimulated the expression of DNMT’s, leading to upregulation of fibrotic genes, which got ameliorated by miR 29b mimics [84], whereas TGF-β1 escalated miR152 as well as miR30a in the renal cells as well as fibrotic (here in non-diabetic) kidney [72].

Diabetic Kidney Disease as well as Histone post-translational modifications

Alterations in Histone post-translational modifications have been visualized to be present along with aid in the generation of Diabetic Kidney Disease or Kidney Disease of different aetiologies.

Histone Methylation

Abnormal Histone Methylation has been seen in experimental as well as human DKD (85, 86). The initial correlation among Diabetes along with changed Histone Methylation was visualized in monocytes as well as lymphocytes from T1D patients along within THP1 monocytes that had been cultured with escalated glucose, where differences of Histone methylation was association with mRNA amounts in the target genes [87].

The total profile of Histone methylation in DKD has not got totally worked up, nevertheless, knowledge regards to individual modulation of genes. In the Kidneys of db/db mice, H3K4m2(the activating mark) are less as compared to non diabetic mice, as well as following unineprectomy that exacerbates the propagation of renal damage in db/db mice., H3K4 Methylation was escalated [88]. Furthermore, a CCL2 inhibitor which avoids disease propagation, also avoided the escalated H3K4 Methylation, pointing that this Epigenetic mark was associated with propagation of disease [89]. Nevertheless, the action of H3K4m2 on Kidney gene expression is not clear.

In case of 2 rodent models of T1D, OVE26 mice as well as streptozotocin rats, the amounts of H3K27m3, that is a repressive Histone Methylation mark, are decreased in critical genes like Mcp1, vimentin as well as the abnormal Histone Methylation may be behind the differential Kidney gene expression in DKD [89]. KDM6A (alias UTX), the histone demethylase gets overexpressed in OVE26 mice as well as might aid in these findings [89]. The harmful actions of histone demethylation on repressive marks have further been visualized in case of cultured podocyte, as GSK-J4, that is a double inhibitor of H3K27m3/2- demethylases, limits the Notch pathway as well as preferred the podocyte differentiation (Figure 6) [90]. Moreover GSK-J4 ameliorated renal damage. In addition, TGF β1, that is a critical promoter of fibrosis in DKD, escalated the expression of histone demethylase JMJD3 as well as UTX besides downregulating EZH2 methyltransferase in mesangial cells [91]. Kidneys from streptozotocin rats as well as OVE26 mice, upregulation of demethylase, whereas abundant enhancer of Zeme Homolog 2 (EZH2) methylase as well as repressive methylation in the profibrotic genes is diminished. In case of human DKD, the repressive histone mark H3K27m3 is further diminished, whereas the expression of histone demethylase UTX is escalated, that points to the part of histone demethylation of repressive areas in DKD [91]. Furthermore the inhibition of EZH2 in podocyte that were cultured in enhanced glucose surroundings as well as in streptozotocin induced Diabetes rats diminished H3K27me marks at the Pax 6 promoter, stimulating the expression of PAX6 as well as facilitating podocyte damage, oxidative stress as well as proteinuria [92] SUV39H (Figure 4), that represents another methyltransferase of the repressive mark H3K9m3, is further downregulated in Kidneys from streptozotocin mice as well as in mesangial cells that had got exposure to high glucose. Actually, SUV39H1 overexpression reduced ECM generation by mesangial cells [93].

SET7/9, that is a H3K4 mono methyltransferase, modulates the TGF β1-stimulated expression of profibrotic genes as it was recruited with their promoters along with SET7/9 siRNA targeting reduced the ECM generation stimulated BY TGF β1-in mesangial cells [94] (Figure 5). Moreover SET7/9 facilitates the expression of the inflammatory genes via histone methylation along with transcription factor NF-κB getting recruited in peripheral blood monocytes obtained from streptozotocin induced Diabetes mice as well as from T2D patients along with human aortic endothelial cells that had received exposure to escalated glucose [95].

Intriguingly, losartan, that is AT1R blocker utilized for the treatment of clinical DKD, partly decreased the permissive Epigenetic histone methylation visualized in db/db mice, along with this can reason out the decreased PAI-1, MCP1 along with RAGE under losartan therapy [96]. Nevertheless, the action of losartan over histone methylation of these particular genes was markedly weak, hence in total how much it aids in enhancement of DKD is still ill understood [96].

In total these results point that histone methylation might have a critical part in changed gene expression at the time of DKD, although functional in vivo studies particularly targeting separate enzymes are essential for clarification of their therapeutic target utility.

Histone Acetylation

Proof exists that Histone acetylation aids in DKD propagation. Factors, like escalated glucose amounts along with Diabetes complications can stimulate alterations in total Histone acetylation patterns that gets modulated by HATs along with HDACs [97, 98]. Moreover, Histone acetylation was involved in EMT [99] along with escalated Kidney extracellular matrix (ECM) getting deposited [100].

TGF β1- that has been considered a critical modulator of DKD, facilitates Histone acetylation. In case of cultured rat, mesangial cells TGF β1 as well as escalated glucose situation stimulated p300/CBP-, hence escalating H3K9/14ac at the fibronectin-1 (Fn1) promoter [101], along with close to the Sp1 as well as Smad binding areas at the Pai, Fn1 along with Ctgf gene expression were further escalated by stimulation of HAT p300/CBP along with the existence of acetylated histones in their promoters of type1 Diabetic mice [102]. Moreover, TGF β1 further escalated acetylation of H3 (K9, 14, 27) along with ETS in glomeruli from Diabetic db/db mice aiding in DKD via miR192 expression [103]. H3K9/14ac also exists in Ccl2 Rage as well as Pai promoters under escalated glucose situation, pointing to a controlling function of H3K9/14ac in the DKD associated genes getting expressed [99]. Further p300/CBP controls the expression of collagen type1 alpha 2 chain (COLIA2), that is a significant ECM molecule via manipulation of Histone acetylation at its promoter in dermal fibroblast as well as skin biopsies [104] along with getting induced by TGF β1 via p300/CBP getting recruited in mouse mesangial cells [105] (Figure 6).

Figure 5: Courtesy ref no-150-Schematic representation of histone modifications in diabetic-induced fibrotic and inflammatory gene expression. High-glucose conditions cause the expression of ECM-associated genes Col1a1, CTGF, PAI-1, FN-1, Lacm1, and P21 as well as inflammatory genes TNF-α, COX-2, and MCP-1, leading to fibrosis and glomerulosclerosis in the pathogenesis of DKD. The gene expression is based on the increased active chromatin markers (H3K4me, H3K9/14ac, and H3K79me) and decreased repressive markers (H3K9me3 and H3K27me3) on the promoters of fibrotic and inflammatory genes. Under diabetic conditions (high glucose), TGF-β antibodies, some specific HDACs, TSA, and antioxidants could have renoprotective effects.

Figure 6: Courtesy ref no-8-Summary of therapeutic intervention on epigenetic modifications with evidence of renal benefit in preclinical diabetic nephropathy. Different approaches targeting epigenetic modifications attenuate renal injury in experimental models DN. me, methylation; Ac, acetylation; TSA, trichostatin A; VPA, valproic acid; NaB, sodium butyrate. Inhibition of DNA methylases or activation of DNA demethylases, inhibition of specific histone demethylases, and inhibition of certain histone deacetylases (HDAC) (e.g., HDAC2 by TSA and VPA and NaB unknown), activation of other HDACs (e.g., HDAC1 by apelin-13) or activation of histone acetylases such as p300/CBP were all protective in preclinical DN.

Kidney Histone acetylation stimulated by Diabetes, promotes pro inflammatory gene expression in rats [106] as well as, in human blood monocytes via escalated NFκB activity along with hyper acetylation of pro inflammatory gene promoters [107]. In case of human along with murine mesangial cells that got cultured in escalated glucose situation as well as in Kidneys from Diabetic mice H3K9 acetylation caused escalated expression of thioredoxin –interacting protein (TXNIP), that is a critical pathogenic factor in DKD [108].

Akita mice that are Diabetic as well as possessing to point mutation in the Ins2 gene which causes misfolding of insulin along with type1 Diabetes, had escalated H3K9 as well as H3K18 acetylation in renal cortex as well as this was reduced by Apelin13 therapy, reducing the expression of NFκB inflammatory associated gene along with this being correlated with an escalated HDAC1 expression [107]. Blood monocytes from Diabetic subjects, an escalation of H3K9Ac promoters along with H3K9Ac got correlated with glycaemic regulation. Furthermore, the top hyperacetylated promoters in Diabetic subjects had an enrichment of genes that were associated with the NFκB pathway along with Diabetic complications [92].

By utilizing HAT HDAC inhibitors, Histone acetylation represent a potential target for treatment of DKD (Figure 4). HDAC1 gets downregulated in the renal cortex of Akita mice, along with in rat glomerular mesangial cells that had got cultured in escalated glucose situation, causing Histone hyperacetylation, that promotes inflammatory gene expression. HDAC inhibition results in escalated H3K9 acetylation along with TGF β1- stimulated gene expression [102]. Akin to that escalated action of SIRT1, that is a significant nephroprotective HDAC, by podocyte particular SIRT1 overexpression or by the SIRT1 agonist BF175 therapy, reduced podocyte damage along with albuminuria in OVE26 mice [108]. BF175 in cultured podocytes, escalated SIRT1-modulated activation of PGC1-α as well as conferred protection against escalated glucose modulated mitochondrial damage. In rat DKD, the HDAC inhibitors trichostatin A (TSA) along with Valproic acid (VPA) conferred protection. TGF β1- stimulated ECM collection was blocked by TSA, besides escalating the expression of E-cadherin in streptozotocin induced Diabetes rats [109]. TSA is believed to escalate the expression of E-cadherin via HDAC inhibition leading to escalated acetylation of the promoter, nevertheless, it is not clarified if ate action over TGF β1 expression is based on the manipulation of acetylation in non-histone proteins. VPA abrogates renal damage in streptozotocin induced Diabetes rats via the control of endoplasmic reticulum stress (ER)- correlated proteins. VPA stimulates acetylation in the Grp78 promoter aacetylation de along with in the C/EBP-homologous protein (Chop) promoter, causing an escalated expression of GPR78 along with downregulation of CHOP [102]. The deacetylation of Chop promoter, appears to get modulated by ATF4 downregulation, which is essential for HAT binding its promoter [102].

Curcumin avoids the generation of renal injury in the streptozotocin induced type 1 Diabetic rats which got correlated with decreased amounts of renal H3 acetylation [103]. Subsequently, it got demonstrated that the Curcumin analog C66 inhibits HAT p300/CBP action as well as subsequent histone acetylation in streptozotocin induced Diabetic mice avoiding the expression of renal fibrotic genes [108]. Another p300/CBP inhibitor C646 inhibited TGF β1 stimulated epithelial-mesenchymal-transition (EMT) of human peritoneal mesothelial cells getting exposed to escalated glucose situation via manipulation of H3 acetylation [110].

Rest of Histonemodifications

Crotonylation

In variety of healthy tissues, that includes the kidney [28], constitutive along with escalated histone Crotonylation has been detailed at the time of experimental Nephrotoxic Akin pointing to a part of histone Crotonylation in kidney damage, despite no studies in DKD [47]. In this context, manipulation of histone Crotonylation modulates the results of kidney damage.

Stimulation of murine tubular cells via the cytokine TWEAK, that is a modulator of kidney damage [112], along withAKI, histone crotonylation was escalated, which was correlated with reduced SIRT3 along with PGC1-α expression as well as escalated expression of the chemokine-that encodes Ccl2 gene. In this context, crotonate delivery, that by escalating the substrate facilitated histone crotonylation, escalated kidney SIRT3 as well as PGC1-α expression in vivo as well as in cultured cells, whereas reducing CCL2 expression besides conferring protection. Nevertheless, studies evaluating its part in the form of therapy in DKD are needed.

β-hydroxy butyrylation

Despite few studies have assessed the association among histone β-hydroxy butyrylation along with DKD, proof exists pointing to a potential advantageous action. Inspite the finding that escalated serum BHB amounts are correlated with greater chances of mortality in haemodialysis patients irrespective of the existence or absence of Diabetic Nephropathy [113]. BHB represses oxidative stress as well as might be advantageous in DKD. In this context correlation imply causality. Hence a ketogenic diet relieved DKD as well as decreased oxidative stress genes in murine type1(Akita) as well as type 2(db/db) Diabetes [114]. It is believed that this action gets modulated by BHB , that confers protection against oxidative stress stimulated by glucose in neuronal cells , but this was not evaluated in renal cells [114]In case of human embryonic Kidney cells , histone Kbhb gets controlled by BHB amounts , whereas histone acetylation didn’t get controlled that way. This might possess a physiological significance in DKD, as serum BHB amounts are escalated in case of both fasted as well as streptozotocin Diabetic mice [43]. Actually, greater serum BHB amounts get correlated with escalated histone Kbhb amounts in both liver of streptozotocin Diabetic mice along within in Kidney of fasted mice, as well as histone Kbhb had a part in reprogramming gene expression for getting the cells adjust to the alteration in energy sources [46]. Inhibition of HDACs by BHB might enhance the metabolic profile along with redox state by stimulation of oxidative stress resistance via the expression of FOXO3A as well as, MT2 in murine Kidney [44]. Regarding DN, post therapy with sodium butyrate (NaB) in streptozotocin rats was nephroprotective as well as decreased HDACs action pointing that this protection was modulated by manipulation of histone acetylation [115]. However more studies are required to get an insight in the global as well as local involvement of histone Kbhb on DKD , besides its treatment potential.

Modulators of Epigenetic Readers

BET Inhibitors (iBET) that are selective are the ones that block the Bromodomains on BET proteins as well as acetylated proteins [116]. BRD4 Inhibition in cell cultures by small interfering RNA or by pharmacological iBET’s downregulate the proinflammatory as well as profibrotic gene expression [117-119]. Transcription factors also possess acetylated residues. The RelA subunit of the proinflammatory Transcription factors NFκB can get acetylated by Lys 310, resulting in activation. Cancer studies have detailed that BRD binding to acetylated Lys310 of RelA is necessary to activate particular NFκB Transcriptional activation as well as downregulating various NFκB regulated genes, that are Ccl2 as well as Il17a [120]. Intriguingly, all the above factors, TNFα, NF κB, CCL2 as well as IL-17A, aid in the pathogenesis of DKD [121] (Figure 5).

iBET’s have been observed to be advantageous in variety of experimental diseases, that are malignancies, infections, autoimmune diseases, inflammation as well as fibrotic conditions [116, 117]. In particular BET Inhibition further conferred protection from DM as well as enhanced renal function, besides possessing nephro protective properties in experimental Kidney diseases [115, 120].

iBET762 avoided Diabetes mellitus in NOD mice that is a model of T1D. BET InhibitIon, in this context, in pancreatic β cells escalated insulin liberation [122], pointing that these drugs might be of use for treatment of insulin resistant / Diabetic subjects. BRD4 as well as modulates the activation of senescence-associated secretory phenotype in case of islet cells. Furthermore, BET proteins control pancreatic generation [123], as well as Diabetic intervertebral disc degeneration [125]. BET Inhibition by JQI ameliorates streptozotocin induced Diabetic cardiomyopathy in streptozotocin induced Diabetes by repressing cardiac fibrosis as well as enhancing cardiac function by manipulation of caveolin/TGF β1-signalling in cardio-fibroblasts in addition to inhibiting cardiomyocyte apoptosis [126]. Further BRD4 is implicated by escalated glucose-stimulated cardiomyocyte hypertrophy via AKT pathway [126]. Lesser knowledge exists in relation to Kidney. Nevertheless, the outcomes do help in validation of nephroprotection through BET Inhibition. Hence in case of cultured podocytes, silencing of BRD4 gene or JQI inhibited escalated glucose-stimulated podocytes damage, while overexpression of BRD4 stimulated apoptosis, nevertheless, it is not clear if this gets manifested by manipulation of histone binding [127].

Association of Epigenetic Modulation with Crucial pathogenic events in DKD

The knowledge existing on Epigenetic modifications as well as DKD can be described as probable aid in particular pathogenic events, like podocyte damage, inflammation as well as fibrosis via Modulation of gene transcription in Kidney cells as well as/or leukocytes. In spite these studies it is tough to point the action of some histone post translational modifications or DNA methylation to a particular cell type or a particular molecule or a group of molecules knowing that unworked out actions in other cell kinds or other genes might aid in the phenotype visualized. Due to this only, it is tough to be sure if the Association of Epigenetic modifications with DKD characteristics suggest correlations versus causality. Once no interventional studies got conducted, it becomes practically impossible to discriminate correlations versus causality. Nevertheless, even if these studies had been conducted, it might not have clarified if the alterations visualized in gene expression in cultured cells secondary to promotion or inhibition of a particular Epigenetic characteristics are the critical drivers of any potential in vivo therapeutic action or if they might depict epiphenomena as well as the in vivo action is stimulated by a well-tuned response, where the gene evaluated possessed a little part or none .Or on the other hand , the critical cells mediating the in vivo action might not be the a renal cell also. Hence in spite of watching an involvement of Epigenetic modifications on the cultured podocytes, the critical cells for protection of Kidney cell in vivo, might be a leukocytes subtype. This is present even when well established mediators of DKD like TGFβ1 are demonstrated to get Modulated in culture along with in vivo. This problem probably would only be solved once single cell Epigenetic methods get generated along with combined with the present single cell transcriptomics data gets available.

Utilization of Agents that Modify Epigenetics for Therapy or Targets in Clinical DKD

An escalation into Epigenetics along with Agents that Modify Epigenetics is there. According to the Clinical trials .com, there are a minimal of 290 Clinical studies on this topic (http:// Clinical trials.gov/ct2/results? cond=epigenetic &term=&cntry=&state=&city=&dist =&search = search;accessed on apr 17, 2020). Maximum studies concentrate on Epigenetics in haematological diseases, cancer, autoimmune diseases as well as inflammatory disease, cardiovascular risk factors , in the form of DM, obesity as well as atherosclerosis along with include evaluation of iBETs, mainly in cancers [116]. Actually 55 studies are continuing in the DM field, maximum of which are not evaluating the Epigenetic modifiers directly.

The BD2 selective inhibitor Apabetalone (RVX -208/RVX000222) got analyzed in patients with type 2Diabetes possessing high risk of cardiovascular diseases (http:// Clinical trials.gov/NCT 02586155). This represents an Epigenetic modifier possessing maximum clinical generation that is advanced in DM, cardiovascular (CVS) as well as Kidney diseases, since phase 3 outcomes got documented recently. Apabetalone manipulates the expression of a lot of different genes, that included complement along with coagulation factors, cardiovascular disease (CVD) markers, C-reactive protein (CRP) as well as of particular significance for nephrologists, alkaline phosphatase as well as cholesterol transport genes.

The phase IIb SUSTAIN as well as ASSURE trials evaluated the action of Apabetalone on cardiovascular processes in patients that were in high category risk of Diabetics with coronary artery disease. A post hoc sub- evaluation [128] of patients with eGFR <60 mL/min 1, 73m2 documented that Apabetalone patients had a significant diminution (p=0.02) of alkaline phosphatase amounts of-14% in contrast to 6% in the placebo group. alkaline phosphatase amounts are considered to be risk factors for mortality in patients having CKD as well as are associated as well as believed to aid in vascular calcification, along with to cardiovascular processes [129]. Another multicenter trial (NCT 03160430) will contrast, in a sequential cross-over study with 4 weeks washout in between, the influence of 6 wks of Apabetalone (100mg/12h) or placebo on the plasma alkaline phosphatase in end-stage renal disease (ESRD) patients getting haemo dialysis.

A phase 3 clinical trial, BET on MACE , got finished recently [130].2425 patients got recruited with recent acute coronary syndrome, type2 Diabetes, along with low HDL cholesterol on statins to Apabetalone (100mg/12h) or placebox120wks.The trial could not meet the primary endpoint of CVS death , myocardial infarction (MI), stroke [130].At the time of a median follow up of 26.5 mths, 274 primary endpoints took place; 125(10.3%) in Apabetalone receivers as well as 149(12.4%) in placebo receivers(hazard ratio, 0.82b [95%CI, 0.65-1.04;P=0.06). Despite there being an earlier defined secondary endpoint of alteration in Kidney function in patients with eGFR <60 mL/min 1, 73m2, formal statistical evaluation of the crucial secondary endpoint as well as pre marked evaluation plan on not meeting the primary endpoints. Anyways , an exploratory evaluation of secondary endpoints pointed to a decreased risk of congestive heart failure hospitalized patients. Nevertheless, no influence on inflammation, as evaluated by CRP amounts was seen. Greater number of patients got marked for receiving Apabetalone in contrast to placebo discontinued study group (114[9.4%] vs 69[5.7%]), due to escalation of liver enzyme amounts (35[2.9%] vs 11[0.9%), that caused safety issues[130].The incidence of alanine aminotransferase escalation was greater than 5 fold the upper limit of normal was 4.7 times greater in the Apabetalone in contrast to placebo groups although this was totally reversible as well as Hy‘s law thresholds for liver toxicity were not seen in any patient. Nausea was observed greater with Apabetalone in contrast to placebo groups (26[2.1%] vs 7[0.6%]), that highlighted this concern of tolerability of the drug.

 At present 6 Apabetalone clinical trials are trying to assess its safety, pharmacokinetics as well as pharmacodynamics, where 2 are concentrating on CKD.A phase 1 as well as 2 trial (NCT03228940) would assess the safety, as well as actions on crucial Biomarkers (like markers of inflammation, CKD-MBD as well as glycolipid storage) of Apabetalone (100mg/12h) for 16wks in Fabry disease patients. Fabry disease represents a genetic X-linked disorder of lysosomal storage secondary to mutations in the GLA gene resulting in collection of glycolipids along with Kidney as well as heart disease, that has common pathways with DKD [131]. This trial was anticipated to be finished by 2020.

There are 2 separate interventional clinical studies (NCT03817749, NCT4194450) in pre-Diabetic patients are evaluation as a secondary endpoint, if monocytes H3 acetylation at Lys9 as well as Lys4 alterations in response to oral ketone supplements (a ketone ester as well as (R)-3-hydroxy butyl (R)-3 hydroxy butyrate respectively) for14 days. The SCFA butyrate a product that gets formed by the gut microbiota (GM) can get converted to β hydroxy properties [132]. Butyrate reduces proteinuria in Diabetic rats [115]. As a changed microbiota possessing the properties of butyrate generating bacteria has been detailed in DM, an ongoing randomized clinical trial (NCT04073927) in type1 Diabetes patients with DKD is evaluating the influence of 3.6g/day oral Sodium butyrate or placebo x12wks as well as has albuminuria as well as GFR in the form of secondary endpoints.

As far as safety as well as particular populations which might be benefitted via epigenetic interventions, still knowledge is not enough, since interventions targeting Epigenetics Modifications in DKD are at the early clinical trial stage.

Epigenetics and SGLT2 Inhibitors

With the unanticipated advantageous effect of SGLT2 inhibitors on Kidney as well as heart results in Diabetes, DKD as well as heart failure, a lot of debate goes on regarding the molecular modes implicated [12]. This might be associated to a tubular modulated haemodynamic action, to conferring protection to tubular cells from escalated glucose or to other metabolic actions, like escalated ketone amounts [12, 133, 134]. Knowing the escalated knowledge on the part of Epigenetic controlling in DKD, a probability that SGLT2 inhibitors might indirectly control DNA methylation, as well as /or histone post translational modifications. Nevertheless, a Pubmed search done recently for (methylation, or acetylation or Crotonylation or histone) as well as (SGLT2 or Dapagliflozin, or Canagliflozin or empagliflozin) did not yield anything that was relevant to this topic. It was posited by Martinez-Moreno group [8], that here exists a lucrative field needing evaluation as well as exploration to get insight on the molecular modes of SGLT2 inhibitors advantages besides to know part of Epigenetics control of DKD. In this context of SGLT2 inhibitors escalate plasma along with tissue amounts of ketone-3 hydroxy butyric acid that stimulated β hydroxy butyrylation of H3 at Lys 9 of the adiponectin gene in adipocytes independent of their methylation, or acetylation that isolates a new histone post translational modifications significant to the therapeutic action of SGLT2 inhibitors [50].Although little information on DNA methylation as well as /or histone epigenetics , already some knowledge on miRNAs.40 Diabetic patients contrasting therapy with Dapagliflozin, or thiazides in an open label study circulating miR30e-5p was upregulated whereas miR199 a-3p downregulated in Dapagliflozin treatment patients [135]. This study points that actually SGLT2 inhibitors might manipulate Epigenetic controllers.

Conclusions as well as Future Directions

This idea of Epigenetic controlling of gene expression got generated from a fixed at birth p-or-early generation characteristics to a dynamic property that might get altered in response to the environment or therapeutic manipulation. Hence tools, are present for activation or inhibition of enzymes implicated in attaching or detaching the Epigenetic marks, along with for interference with readers of Epigenetic information. Interfering with the BET reader proteins is already going through clinical trials in the DKD field. Moreover, the substrate availability controls histone post translational modifications, as illustrated for histone Crotonylation or β hydroxy butyrylation. These tools got utilized to illustrate nephroprotective actions of therapeutically Epigenetic control in variety of nephropathies that include DKD. Nevertheless, certain fields continue not having been explored in the DKD field, like the nephroprotective part of a total escalation in kidney histone Crotonylation as seen in non-Diabetic Kidney damage. Lastly, commonly utilized drugs might indirectly control Epigenetic modes. Of the least explored are the Epigenetic effects of giving SGLT2 inhibitors. An urgent requirement for the same exists, knowing that cardio as well as nephroprotective property is much greater than anticipation as well as currently no reasoning is there depending on our insight of their modes of action. A part for an indirect manipulation of Epigenetic definitely requires more studies knowing the influence of SGLT2 inhibitors on 3 hydroxy butyric acid, which is a driver of histone β hydroxy butyrylation. Intriguingly, a low caloric intake is the only method that escalates lifespan continuously in all species evaluated as well as it is believed that fasting is a crucial aiding factor in this action. Fasting further escalates 3 hydroxy butyric acid amounts escalating the β histone hydroxy butyrylation, like Ppaar gc1a gene that encodes PGC-1α [48], that is a crucial nephroprotective molecule [136, 137]. Ultimately in spite the detailing of certain Epigenetic manipulations of particular characteristics as well as particular Molecular involvement in DKD, insight is not enough on the cause as well as action association among these particular Molecular alterations as well as total influence of targeting Epigenetic manipulations in vivo. In this context, with the knowledge that Epigenetic manipulations in DKD are at the clinical trial stage till now, it is uncertain if early intervention in these pathways can avoid disease or later intervention might aid in reversal of disease already developed in human beings. Further Xu et al. [138] and Lu et al. [139] reviewed how miRNA’s Long noncoding RNAs might impact and till now Figure 5 and Figure 6 summarize how epigenetic manipulation might aid in helping in DKD’S despite more research required.

REFERENCES

1. Bikbov B, Purcell CA, Levey AS, Smith M, Abdoli A, Abebe M, Adebayo OM, Afarideh M, Agarwal SK, Agudelo-Botero M, Ahmadian E. Global, regional, and national burden of chronic kidney disease, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017. The Lancet. 2020 Feb 29;395(10225):709-33.
2. Lancet T. GBD 2017: a fragile world. 
3. Thomas B. The global burden of diabetic kidney disease: time trends and gender gaps. Current diabetes reports. 2019 Apr;19(4):1-7.
4. Foreman KJ, Marquez N, Dolgert A, Fukutaki K, Fullman N, McGaughey M, Pletcher MA, Smith AE, Tang K, Yuan CW, Brown JC. Forecasting life expectancy, years of life lost, and all-cause and cause-specific mortality for 250 causes of death: reference and alternative scenarios for 2016–40 for 195 countries and territories. The Lancet. 2018 Nov 10;392(10159):2052-90. 
5. Fernandez-Fernandez B, Fernandez-Prado R, Górriz JL, Martinez-Castelao A, Navarro-González JF, Porrini E, Soler MJ, Ortiz A. Canagliflozin and renal events in diabetes with established nephropathy clinical evaluation and study of diabetic nephropathy with atrasentan: what was learned about the treatment of diabetic kidney disease with canagliflozin and atrasentan? Clinical kidney journal. 2019 Jun;12(3):313-21.
6. Perez-Gomez MV, Sanchez-Niño MD, Sanz AB, Martín-Cleary C, Ruiz-Ortega M, Egido J, Navarro-González JF, Ortiz A, Fernandez-Fernandez B. Horizon 2020 in diabetic kidney disease: the clinical trial pipeline for add-on therapies on top of renin angiotensin system blockade. Journal of clinical medicine. 2015 Jun;4(6):1325-47. 
7. Martinez-Moreno JM, Fontecha-Barriuso M, Martin-Sanchez D, Guerrero-Mauvecin J, Goma-Garces E, Fernandez-Fernandez B, Carriazo S, Sanchez-Niño MD, Ramos AM, Ruiz-Ortega M, Ortiz A. Epigenetic Modifiers as Potential Therapeutic Targets in Diabetic Kidney Disease. International Journal of Molecular Sciences. 2020 Jan;21(11):4113. 
8. Sanchez-Nino MD, Sanz AB, Sanchez-Lopez E, Ruiz-Ortega M, Benito-Martin A, Saleem MA, Mathieson PW, Mezzano S, Egido J, Ortiz A. HSP27/HSPB1 as an adaptive podocyte antiapoptotic protein activated by high glucose and angiotensin II. Laboratory Investigation. 2012 Jan;92(1):32-45. 
9. Navarro-González JF, Sánchez-Niño MD, Donate-Correa J, Martín-Núñez E, Ferri C, Pérez-Delgado N, Górriz JL, Martínez-Castelao A, Ortiz A, Mora-Fernández C. Effects of pentoxifylline on soluble klotho concentrations and renal tubular cell expression in diabetic kidney disease. Diabetes Care. 2018 Aug 1;41(8):1817-20. 
10. Fernandez-Fernandez B, Izquierdo MC, Valiño-Rivas L, Nastou D, Sanz AB, Ortiz A, Sanchez-Niño MD. Albumin downregulates Klotho in tubular cells. Nephrology Dialysis Transplantation. 2018 Oct 1;33(10):1712-22. 
11. Sanchez-Niño MD, Bozic M, Córdoba-Lanús E, Valcheva P, Gracia O, Ibarz M, Fernandez E, Navarro-Gonzalez JF, Ortiz A, Valdivielso JM. Beyond proteinuria: VDR activation reduces renal inflammation in experimental diabetic nephropathy. American Journal of Physiology-Renal Physiology. 2012 Mar 15;302(6): F647-57.        
12. Sarafidis P, Ferro CJ, Morales E, Ortiz A, Malyszko J, Hojs R, Khazim K, Ekart R, Valdivielso J, Fouque D, London GM. SGLT-2 inhibitors and GLP-1 receptor agonists for nephroprotection and cardioprotection in patients with diabetes mellitus and chronic kidney disease. A consensus statement by the EURECA-m and the DIABESITY working groups of the ERA-EDTA. Nephrology Dialysis Transplantation. 2019 Feb 1;34(2):208-30. 
13. Perkovic V, Jardine MJ, Neal B, Bompoint S, Heerspink HJ, Charytan DM, Edwards R, Agarwal R, Bakris G, Bull S, Cannon CP. Canagliflozin and renal outcomes in type 2 diabetes and nephropathy. New England Journal of Medicine. 2019 Jun 13;380(24):2295-306. 
14. American Diabetes Association. 11. Microvascular complications and foot care: standards of medical care in diabetes—2019. Diabetes Care. 2019 Jan 1;42(Supplement 1): S124-38.
15. Kaur KK, Gautam A, Singh M. An update on etiopathogenesis and management of type 1 diabetes Mellitus. Journal of Endocrinology. 2016;1(2):1-23.
16. Kaur KK, Allahbadia GN, Singh M. An update on the Immunotherapy Strategies for the treatment of Type 1 Diabetes (TID)-How far have we reached in reaching insulin independency in TID therapy-A Systematic Review. J Endocrinol. 2020;4(1):000149.
17. Kaur KK, Allahbadia GN, Singh M. Path Directed towards a Stage when we almost Cure Type1 Diabetes Mellitus (T1dm) after a Century of Insulin Advent”. EC Diabetes and Metabolic Research. 2020;4(6):37-46.
18. Kaur KK, Allahbadia GN, Singh M. How to classify type 2 diabetes mellitus and approach its treatment in view of associated diabetes and complications-a short communication. Series Endo Diab Met. 2019;1(2):29-34.
19. Kaur KK, Allahbadia GN, Singh M. An Update on Management of Diabetic Neuropathy with Diabetic Foot Syndrome-Optimization of Therapy Cost Effectively with Avoidance of Gangrene and Amputation-A Systematic Review. Open Access Journal of Endocrinology. 2020; 4(1): 000145.
20. Kaur KK, Allahbadia G, Singh M. Advantage of Cardiovascular Outcome Trials (CVOT’s) for SGLT2 (Sodium Glucose Transporter 2) Inhibitors in Type 2 Diabetes Mellitus (T2 DM). EC Endocrinology and Metabolic Research. 2019;4(9):38-44.
21. Kaur KK. How can we Use Empagliflozin as an Adjuvant in Reducing Required Need of Insulin in Type 1 Diabetes along with Lowered HbA1c, Weight without Fear of DKA-A Mini Review? J Clin Cases Rep.;4(2):30-8. 
22. Kaur KK, Allahbadia GN, Singh M. Utilization of Extracellular Vesicles for Treatment of Type 1 Diabetes Mellitus (T1DM) Along with Type 2 Diabetes Mellitus (T2DM) besides Complications Associated with Diabetes- A Systematic Review. J Clin Diabetes Obes.2020; 1:001-013.
23. Kaur KK, Allahbadia G, Singh M. Are we Any Close to Unraveling the Mechanism of Interactions Among Susceptibility Genes Towards Type 1 Diabetes, Gut Microbiota Along with Environmental Factors, Specifically Early Diet Patterns–A Systematic Review.’’? Endocrinology and Surgical Endocrinology, 2 (1); DOI: http. doi. org/03.2021/1.1005. 2021 Feb 24.
24. Kaur KK, Allahbadia GN, Singh M. How does Epigenetics Regulate Development of Placenta and Placental Pathologies like PreEclampsia (PE), Intrauterine growth Restriction (IUGR)-With Main emphasis on PE’’.Advances in Bioengineering and Biomed Res. 2020.
25. Kaur KK, Allahbadia GN, Singh M. Can Vitamin D Supplementation prevent / delay/ halt the progression of Diabetic nephropathy;A Systematic Review on mechanism of Vitamin D Crosstalk with Vitamin D Receptor, with others like Megalin-Cubilin and Amnioless Complex along with FGF23-Klotho Complex. 2021-under review.
26. Fontecha-Barriuso M, Martin-Sanchez D, Ruiz-Andres O, Poveda J, Sanchez-Niño MD, Valino-Rivas L, Ruiz-Ortega M, Ortiz A, Sanz AB. Targeting epigenetic DNA and histone modifications to treat kidney disease. Nephrology dialysis transplantation. 2018 Nov 1;33(11):1875-86.
27. Susztak K. Understanding the epigenetic syntax for the genetic alphabet in the kidney. Journal of the American Society of Nephrology. 2014 Jan 1;25(1):10-7. 
28. Tan M, Luo H, Lee S, Jin F, Yang JS, Montellier E, Buchou T, Cheng Z, Rousseaux S, Rajagopal N, Lu Z. Identification of 67 histone marks and histone lysine crotonylation as a new type of histone modification. Cell. 2011 Sep 16;146(6):1016-28. 
29. Jin SG, Wu X, Li AX, Pfeifer GP. Genomic mapping of 5-hydroxymethylcytosine in the human brain. Nucleic acids research. 2011 Jul 1;39(12):5015-24. 
30. Li LX, Agborbesong E, Zhang L, Li X. Investigation of epigenetics in kidney cell biology. Methods in cell biology. 2019 Jan 1; 153:255-78. 
31. Beckerman P, Ko YA, Susztak K. Epigenetics: a new way to look at kidney diseases. Nephrology Dialysis Transplantation. 2014 Oct 1;29(10):1821-7. 
32. Bomsztyk K, Denisenko O, Wang Y. DNA methylation yields epigenetic clues into the diabetic nephropathy of Pima Indians. Kidney international. 2018 Jun 1;93(6):1272-5. 
33. Liao J, Karnik R, Gu H, Ziller MJ, Clement K, Tsankov AM, Akopian V, Gifford CA, Donaghey J, Galonska C, Pop R. Targeted disruption of DNMT1, DNMT3A and DNMT3B in human embryonic stem cells. Nature genetics. 2015 May;47(5):469-78.
34. Ko M, An J, Pastor WA, Koralov SB, Rajewsky K, Rao A. TET proteins and 5‐methylcytosine oxidation in hematological cancers. Immunological reviews. 2015 Jan;263(1):6-21. 
35. Audia JE, Campbell RM. Histone modifications and cancer. Cold Spring Harbor perspectives in biology. 2016 Apr 1;8(4): a019521. 
36. Black JC, Whetstine JR. Tipping the lysine methylation balance in disease. Biopolymers. 2013 Feb;99(2):127-35. 
37. Greer EL, Shi Y. Histone methylation: a dynamic mark in health, disease and inheritance. Nature Reviews Genetics. 2012 May;13(5):343-57. 
38. Ramakrishnan S, Pili R. Histone deacetylase inhibitors and epigenetic modifications as a novel strategy in renal cell carcinoma. Cancer journal (Sudbury, Mass.). 2013 Jul;19(4):333. 
39. Wei W, Mao A, Tang B, Zeng Q, Gao S, Liu X, Lu L, Li W, Du JX, Li J, Wong J. Large-scale identification of protein crotonylation reveals its role in multiple cellular functions. Journal of proteome research. 2017 Apr 7;16(4):1743-52. 
40. Fellows R, Denizot J, Stellato C, Cuomo A, Jain P, Stoyanova E, Balázsi S, Hajnády Z, Liebert A, Kazakevych J, Blackburn H. Microbiota derived short chain fatty acids promote histone crotonylation in the colon through histone deacetylases. Nature Communications. 2018 Jan 9;9(1):1-5.
41. Sabari BR, Tang Z, Huang H, Yong-Gonzalez V, Molina H, Kong HE, Dai L, Shimada M, Cross JR, Zhao Y, Roeder RG. Intracellular crotonyl-CoA stimulates transcription through p300-catalyzed histone crotonylation. Molecular cell. 2015 Apr 16;58(2):203-15. 
42. Wei W, Liu X, Chen J, Gao S, Lu L, Zhang H, Ding G, Wang Z, Chen Z, Shi T, Li J. Class I histone deacetylases are major histone decrotonylases: evidence for critical and broad function of histone crotonylation in transcription. Cell research. 2017 Jul;27(7):898-915. 
43. Martinez-Moreno JM, Fontecha-Barriuso M, Martin-Sanchez D, Sánchez-Niño MD, Ruiz-Ortega M, Sanz AB, Ortiz A. The Contribution of Histone Crotonylation to Tissue Health and Disease: Focus on Kidney Health. Frontiers in pharmacology. 2020 Apr 3; 11:393. 
44. Shimazu T, Hirschey MD, Newman J, He W, Shirakawa K, Le Moan N, Grueter CA, Lim H, Saunders LR, Stevens RD, Newgard CB. Suppression of oxidative stress by β-hydroxybutyrate, an endogenous histone deacetylase inhibitor. Science. 2013 Jan 11;339(6116):211-4.
45. Bae HR, Kim DH, Park MH, Lee B, Kim MJ, Lee EK, Chung KW, Kim SM, Im DS, Chung HY. β-Hydroxybutyrate suppresses inflammasome formation by ameliorating endoplasmic reticulum stress via AMPK activation. Oncotarget. 2016 Oct 11;7(41):66444. 
46. Xie Z, Zhang D, Chung D, Tang Z, Huang H, Dai L, Qi S, Li J, Colak G, Chen Y, Xia C. Metabolic regulation of gene expression by histone lysine β-hydroxybutyrylation. Molecular cell. 2016 Apr 21;62(2):194-206. 
47. Liu K, Li F, Sun Q, Lin N, Han H, You K, Tian F, Mao Z, Li T, Tong T, Geng M. p53 β-hydroxybutyrylation attenuates p53 activity. Cell death & disease. 2019 Mar 11;10(3):1-3. 
48. Zhang H, Tang K, Ma J, Zhou L, Liu J, Zeng L, Zhu L, Xu P, Chen J, Wei K, Liang X. Ketogenesis-generated β-hydroxybutyrate is an epigenetic regulator of CD8+ T-cell memory development. Nature cell biology. 2020 Jan;22(1):18-25.
49. Dąbek A, Wojtala M, Pirola L, Balcerczyk A. Modulation of cellular biochemistry, epigenetics and metabolomics by ketone bodies. Implications of the ketogenic diet in the physiology of the organism and pathological states. Nutrients. 2020 Mar;12(3):788. 
50. Nishitani S, Fukuhara A, Shin J, Okuno Y, Otsuki M, Shimomura I. Metabolomic and microarray analyses of adipose tissue of dapagliflozin-treated mice, and effects of 3-hydroxybutyrate on induction of adiponectin in adipocytes. Scientific reports. 2018 Jun 11;8(1):1-1. 
51. Ohashi K, Ouchi N, Matsuzawa Y. Anti-inflammatory and anti-atherogenic properties of adiponectin. Biochimie. 2012 Oct 1;94(10):2137-42. 
52. Zhao S, Zhang X, Li H. Beyond histone acetylation—writing and erasing histone acylations. Current opinion in structural biology. 2018 Dec 1; 53:169-77. 
53. Chen XF, Chen X, Tang X. Short-chain fatty acid, acylation and cardiovascular diseases. Clinical Science. 2020 Mar;134(6):657-76. 
54. Hyun K, Jeon J, Park K, Kim J. Writing, erasing and reading histone lysine methylations. Experimental & molecular medicine. 2017 Apr;49(4): e324-. 
55. Filippakopoulos P, Knapp S. Targeting bromodomains: epigenetic readers of lysine acetylation. Nature reviews Drug discovery. 2014 May;13(5):337-56. 
56. Wang YZ, Xu WW, Zhu DY, Zhang N, Wang YL, Ding M, Xie XM, Sun LL, Wang XX. Specific expression network analysis of diabetic nephropathy kidney tissue revealed key methylated sites. Journal of cellular physiology. 2018 Oct;233(10):7139-47. 
57. Ko YA, Mohtat D, Suzuki M, Park AS, Izquierdo MC, Han SY, Kang HM, Si H, Hostetter T, Pullman JM, Fazzari M. Cytosine methylation changes in enhancer regions of core pro-fibrotic genes characterize kidney fibrosis development. Genome biology. 2013 Oct;14(10):1-4. 
58. Wing MR, Devaney JM, Joffe MM, Xie D, Feldman HI, Dominic EA, Guzman NJ, Ramezani A, Susztak K, Herman JG, Cope L. DNA methylation profile associated with rapid decline in kidney function: findings from the CRIC study. Nephrology Dialysis Transplantation. 2014 Apr 1;29(4):864-72.
59. Marumo T, Yagi S, Kawarazaki W, Nishimoto M, Ayuzawa N, Watanabe A, Ueda K, Hirahashi J, Hishikawa K, Sakurai H, Shiota K. Diabetes induces aberrant DNA methylation in the proximal tubules of the kidney. Journal of the American Society of Nephrology. 2015 Oct 1;26(10):2388-97. 
60. Sharma I, Dutta RK, Singh NK, Kanwar YS. High glucose–induced hypomethylation promotes binding of Sp-1 to myo-inositol oxygenase: Implication in the pathobiology of diabetic tubulopathy. The American journal of pathology. 2017 Apr 1;187(4):724-39. 
61. Li Z, Chen H, Zhong F, Zhang W, Lee K, He JC. Expression of glutamate receptor subtype 3 is epigenetically regulated in podocytes under diabetic conditions. Kidney Diseases. 2019;5(1):34-42.
62.  Xiaowen C, Xiaoyan D, Wenting L. High glucose induces podocyte epithelial-mesenchymal transition and cell migration through NF-κB pathway. Chinese Journal of Nephrology, Dialysis & Transplantation. 2016 Apr 28;25(2):140. 
63. Hayashi K, Sasamura H, Nakamura M, Azegami T, Oguchi H, Sakamaki Y, Itoh H. KLF4-dependent epigenetic remodeling modulates podocyte phenotypes and attenuates proteinuria. The Journal of clinical investigation. 2014 Jun 2;124(6):2523-37. 
64. Hishikawa A, Hayashi K, Abe T, Kaneko M, Yokoi H, Azegami T, Nakamura M, Yoshimoto N, Kanda T, Sakamaki Y, Itoh H. Decreased KAT5 expression impairs DNA repair and induces altered DNA methylation in kidney podocytes. Cell reports. 2019 Jan 29;26(5):1318-32. 
65. Hasegawa K, Wakino S, Simic P, Sakamaki Y, Minakuchi H, Fujimura K, Hosoya K, Komatsu M, Kaneko Y, Kanda T, Kubota E. Renal tubular Sirt1 attenuates diabetic albuminuria by epigenetically suppressing Claudin-1 overexpression in podocytes. Nature medicine. 2013 Nov;19(11):1496-504. 
66. Zhang H, Li A, Zhang W, Huang Z, Wang J, Yi B. High glucose-induced cytoplasmic translocation of Dnmt3a contributes to CTGF hypo-methylation in mesangial cells. Bioscience reports. 2016 Aug 1;36(4). 
67. Li Y, Ren D, Shen Y, Zheng X, Xu G. Altered DNA methylation of TRIM13 in diabetic nephropathy suppresses mesangial collagen synthesis by promoting ubiquitination of CHOP. EBioMedicine. 2020 Jan 1; 51:102582.
68. Gondaliya P, Dasare A, Srivastava A, Kalia K. Correction: miR29b regulates aberrant methylation in In-Vitro diabetic nephropathy model of renal proximal tubular cells. Plos one. 2019 Jan 25;14(1): e0211591. 
69. Richter K, Konzack A, Pihlajaniemi T, Heljasvaara R, Kietzmann T. Redox-fibrosis: Impact of TGFβ1 on ROS generators, mediators and functional consequences. Redox biology. 2015 Dec 1; 6:344-52. 
70. Oba S, Ayuzawa N, Nishimoto M, Kawarazaki W, Ueda K, Hirohama D, Kawakami-Mori F, Shimosawa T, Marumo T, Fujita T. Aberrant DNA methylation of Tgfb1 in diabetic kidney mesangial cells. Scientific reports. 2018 Nov 5;8(1):1-6. 
71. Zhang Q, Wu Q, Wei Y, Yu J, Mu J, Zhang J, Zeng W, Feng B. Effect of TET2 on the pathogenesis of diabetic nephropathy through activation of transforming growth factor β1 expression via DNA demethylation. Life sciences. 2018 Aug 15; 207:127-37. 
72. Yin S, Zhang Q, Yang J, Lin W, Li Y, Chen F, Cao W. TGFβ-incurred epigenetic aberrations of miRNA and DNA methyltransferase suppress Klotho and potentiate renal fibrosis. Biochimica et Biophysica Acta (BBA)-Molecular Cell Research. 2017 Jul 1;1864(7):1207-16.
73. Zhang L, Zhang Q, Liu S, Chen Y, Li R, Lin T, Yu C, Zhang H, Huang Z, Zhao X, Tan X. DNA methyltransferase 1 may be a therapy target for attenuating diabetic nephropathy and podocyte injury. Kidney International. 2017 Jul 1;92(1):140-53. 
74. Chang YT, Yang CC, Pan SY, Chou YH, Chang FC, Lai CF, Tsai MH, Hsu HL, Lin CH, Chiang WC, Wu MS. DNA methyltransferase inhibition restores erythropoietin production in fibrotic murine kidneys. The Journal of clinical investigation. 2016 Feb 1;126(2):721-31.
75.  Xiao X, Tang W, Yuan Q, Peng L, Yu P. Epigenetic repression of Krüppel-like factor 4 through Dnmt1 contributes to EMT in renal fibrosis. International journal of molecular medicine. 2015 Jun 1;35(6):1596-602. 
76. Li H, Zhang W, Zhong F, Das GC, Xie Y, Li Z, Cai W, Jiang G, Choi J, Sidani M, Hyink DP. Epigenetic regulation of RCAN1 expression in kidney disease and its role in podocyte injury. Kidney international. 2018 Dec 1;94(6):1160-76. 
77. Chen G, Chen H, Ren S, Xia M, Zhu J, Liu Y, Zhang L, Tang L, Sun L, Liu H, Dong Z. Aberrant DNA methylation of mTOR pathway genes promotes inflammatory activation of immune cells in diabetic kidney disease. Kidney international. 2019 Aug 1;96(2):409-20. 
78. Tampe B, Tampe D, Müller CA, Sugimoto H, LeBleu V, Xu X, Müller GA, Zeisberg EM, Kalluri R, Zeisberg M. Tet3-mediated hydroxymethylation of epigenetically silenced genes contributes to bone morphogenic protein 7-induced reversal of kidney fibrosis. Journal of the American Society of Nephrology. 2014 May 1;25(5):905-12. 
79. Lin YJ, Zhen YZ, Wei JB, Wei J, Dai J, Gao JL, Li KJ, Hu G. Rhein lysinate protects renal function in diabetic nephropathy of KK/HlJ mice. Experimental and therapeutic medicine. 2017 Nov 30;14(6):5801-8. 
80. Zhang Q, Liu L, Lin W, Yin S, Duan A, Liu Z, Cao W. Rhein reverses Klotho repression via promoter demethylation and protects against kidney and bone injuries in mice with chronic kidney disease. Kidney international. 2017 Jan 1;91(1):144-56. 
81. Sanchez-Niño MD, Fernandez-Fernandez B, Ortiz A. Klotho, the elusive kidney-derived anti-ageing factor. 
82. Barrera‐Chimal J, Jaisser F. Pathophysiologic mechanisms in diabetic kidney disease: A focus on current and future therapeutic targets. Diabetes, Obesity and Metabolism. 2020 Apr; 22:16-31. 
83. Ochoa-Rosales C, Portilla-Fernandez E, Nano J, Wilson R, Lehne B, Mishra PP, Gao X, Ghanbari M, Rueda-Ochoa OL, Juvinao-Quintero D, Loh M. Epigenetic link between statin therapy and type 2 diabetes. Diabetes care. 2020 Apr 1;43(4):875-84. 
84. Gondaliya P, Dasare A, Srivastava A, Kalia K. Correction: miR29b regulates aberrant methylation in In-Vitro diabetic nephropathy model of renal proximal tubular cells. Plos one. 2019 Jan 25;14(1): e0211591. 
85. Kato M, Natarajan R. Epigenetics and epigenomics in diabetic kidney disease and metabolic memory. Nature Reviews Nephrology. 2019 Jun;15(6):327-45. 
86. Yu C, Zhuang S. Histone methyltransferases as therapeutic targets for kidney diseases. Frontiers in pharmacology. 2019 Dec 6; 10:1393. 
87. Miao F, Chen Z, Genuth S, Paterson A, Zhang L, Wu X, Li SM, Cleary P, Riggs A, Harlan DM, Lorenzi G. Evaluating the role of epigenetic histone modifications in the metabolic memory of type 1 diabetes. Diabetes. 2014 May 1;63(5):1748-62. 
88. Sayyed SG, Gaikwad AB, Lichtnekert J, Kulkarni O, Eulberg D, Klussmann S, Tikoo K, Anders HJ. Progressive glomerulosclerosis in type 2 diabetes is associated with renal histone H3K9 and H3K23 acetylation, H3K4 dimethylation and phosphorylation at serine 10. Nephrology dialysis transplantation. 2010 Jun 1;25(6):1811-7.
89. Komers R, Mar D, Denisenko O, Xu B, Oyama TT, Bomsztyk K. Epigenetic changes in renal genes dysregulated in mouse and rat models of type 1 diabetes. Laboratory investigation. 2013 May;93(5):543-52. 
90. Majumder S, Thieme K, Batchu SN, Alghamdi TA, Bowskill BB, Kabir MG, Liu Y, Advani SL, White KE, Geldenhuys L, Tennankore KK. Shifts in podocyte histone H3K27me3 regulate mouse and human glomerular disease. The Journal of clinical investigation. 2018 Jan 2;128(1):483-99. 
91. Jia Y, Reddy MA, Das S, Oh HJ, Abdollahi M, Yuan H, Zhang E, Lanting L, Wang M, Natarajan R. Dysregulation of histone H3 lysine 27 trimethylation in transforming growth factor-β1–induced gene expression in mesangial cells and diabetic kidney. Journal of Biological Chemistry. 2019 Aug 23;294(34):12695-707. 
92. Siddiqi FS, Majumder S, Thai K, Abdalla M, Hu P, Advani SL, White KE, Bowskill BB, Guarna G, Dos Santos CC, Connelly KA. The histone methyltransferase enzyme enhancer of zeste homolog 2 protects against podocyte oxidative stress and renal injury in diabetes. Journal of the American Society of Nephrology. 2016 Jul 1;27(7):2021-34. 
93. Goru SK, Kadakol A, Pandey A, Malek V, Sharma N, Gaikwad AB. Histone H2AK119 and H2BK120 mono-ubiquitination modulate SET7/9 and SUV39H1 in type 1 diabetes-induced renal fibrosis. Biochemical Journal. 2016 Nov 1;473(21):3937-49. 
94. Sun G, Reddy MA, Yuan H, Lanting L, Kato M, Natarajan R. Epigenetic histone methylation modulates fibrotic gene expression. Journal of the American Society of Nephrology. 2010 Dec 1;21(12):2069-80. 
95. Paneni F, Costantino S, Battista R, Castello L, Capretti G, Chiandotto S, Scavone G, Villano A, Pitocco D, Lanza G, Volpe M. Adverse epigenetic signatures by histone methyltransferase Set7 contribute to vascular dysfunction in patients with type 2 diabetes mellitus. Circulation: Cardiovascular Genetics. 2015 Feb;8(1):150-8. 
96. Reddy MA, Sumanth P, Lanting L, Yuan H, Wang M, Mar D, Alpers CE, Bomsztyk K, Natarajan R. Losartan reverses permissive epigenetic changes in renal glomeruli of diabetic db/db mice. Kidney international. 2014 Jan 1;85(2):362-73.
97. Villeneuve LM, Natarajan R. Epigenetic mechanisms. Diabetes and the Kidney. 2011; 170:57-65. 
98. Villeneuve LM, Natarajan R. The role of epigenetics in the pathology of diabetic complications. American Journal of Physiology-Renal Physiology. 2010 Jul;299(1): F14-25. 
99. Loeffler I, Wolf G. Epithelial-to-mesenchymal transition in diabetic nephropathy: fact or fiction? Cells. 2015 Dec;4(4):631-52. 
100. Kolset SO, Reinholt FP, Jenssen T. Diabetic nephropathy and extracellular matrix. Journal of Histochemistry & Cytochemistry. 2012 Dec;60(12):976-86. 
101. Wang Y, Wang Y, Luo M, Wu H, Kong L, Xin Y, Cui W, Zhao Y, Wang J, Liang G, Miao L. Novel curcumin analog C66 prevents diabetic nephropathy via JNK pathway with the involvement of p300/CBP-mediated histone acetylation. Biochimica et Biophysica Acta (BBA)-Molecular Basis of Disease. 2015 Jan 1;1852(1):34-46. 
102. Yuan H, Reddy MA, Sun G, Lanting L, Wang M, Kato M, Natarajan R. Involvement of p300/CBP and epigenetic histone acetylation in TGF-β1-mediated gene transcription in mesangial cells. American Journal of Physiology-Renal Physiology. 2013 Mar 1;304(5): F601-13. 
103. Kato M, Dang V, Wang M, Park JT, Deshpande S, Kadam S, Mardiros A, Zhan Y, Oettgen P, Putta S, Yuan H. TGF-β induces acetylation of chromatin and of Ets-1 to alleviate repression of miR-192 in diabetic nephropathy. Science signaling. 2013 Jun 4;6(278):ra43-. 
104. Ghosh AK, Bhattacharyya S, Lafyatis R, Farina G, Yu J, Thimmapaya B, Wei J, Varga J. p300 is elevated in systemic sclerosis and its expression is positively regulated by TGF-β: epigenetic feed-forward amplification of fibrosis. Journal of Investigative Dermatology. 2013 May 1;133(5):1302-10. 
105. Malek V, Sharma N, Gaikwad AB. Histone acetylation regulates natriuretic peptides and neprilysin gene expressions in diabetic cardiomyopathy and nephropathy. Current molecular pharmacology. 2019 Feb 1;12(1):61-71. 
106. De Marinis Y, Cai M, Bompada P, Atac D, Kotova O, Johansson ME, Garcia-Vaz E, Gomez MF, Laakso M, Groop L. Epigenetic regulation of the thioredoxin-interacting protein (TXNIP) gene by hyperglycemia in kidney. Kidney international. 2016 Feb 1;89(2):342-53.
107. Chen H, Li J, Jiao L, Petersen RB, Li J, Peng A, Zheng L, Huang K. Apelin inhibits the development of diabetic nephropathy by regulating histone acetylation in Akita mouse. The Journal of physiology. 2014 Feb 1;592(3):505-21. 
108. Hong Q, Zhang L, Das B, Li Z, Liu B, Cai G, Chen X, Chuang PY, He JC, Lee K. Increased podocyte Sirtuin-1 function attenuates diabetic kidney injury. Kidney international. 2018 Jun 1;93(6):1330-43. 
109. Sun XY, Qin HJ, Zhang Z, Xu Y, Yang XC, Zhao DM, Li XN, Sun LK. Valproate attenuates diabetic nephropathy through inhibition of endoplasmic reticulum stress-induced apoptosis. Molecular Medicine Reports. 2016 Jan 1;13(1):661-8.
110. Yang Y, Liu K, Liang Y, Chen Y, Chen Y, Gong Y. Histone acetyltransferase inhibitor C646 reverses epithelial to mesenchymal transition of human peritoneal mesothelial cells via blocking TGF-β1/Smad3 signaling pathway in vitro. International journal of clinical and experimental pathology. 2015;8(3):2746. 
111. Ruiz-Andres O, Sanchez-Niño MD, Cannata-Ortiz P, Ruiz-Ortega M, Egido J, Ortiz A, Sanz AB. Histone lysine crotonylation during acute kidney injury in mice. Disease models & mechanisms. 2016 Jun 1;9(6):633-45.
112. , Sanz AB, Ruiz-Andres O, Sanchez-Niño MD, Ruiz-Ortega M, Ramos AM, Ortiz A. Out of the TWEAKlight: elucidating the role of Fn14 and TWEAK in acute kidney injury. InSeminars in nephrology 2016 May 1 (Vol. 36, No. 3, pp. 189-198). WB Saunders.
113. Obokata M, Negishi K, Sunaga H, Ishida H, Ito K, Ogawa T, Iso T, Ando Y, Kurabayashi M. Association between circulating ketone bodies and worse outcomes in hemodialysis patients. Journal of the American Heart Association. 2017 Oct 3;6(10): e006885. 
114. Poplawski MM, Mastaitis JW, Isoda F, Grosjean F, Zheng F, Mobbs CV. Reversal of diabetic nephropathy by a ketogenic diet. PloS one. 2011 Apr 20;6(4): e18604. 
115. Khan S, Jena G. Sodium butyrate, a HDAC inhibitor ameliorates eNOS, iNOS and TGF-β1-induced fibrogenesis, apoptosis and DNA damage in the kidney of juvenile diabetic rats. Food and chemical toxicology. 2014 Nov 1; 73:127-39. 
116. Morgado-Pascual JL, Rayego-Mateos S, Tejedor L, Suarez-Alvarez B, Ruiz-Ortega M. Bromodomain and extraterminal proteins as novel epigenetic targets for renal diseases. Frontiers in pharmacology. 2019 Nov 8; 10:1315. 
117. Suarez‐Alvarez B, Rodriguez RM, Ruiz‐Ortega M, Lopez‐Larrea C. BET proteins: an approach to future therapies in transplantation. American Journal of Transplantation. 2017 Sep;17(9):2254-62. 
118. Zou Z, Huang B, Wu X, Zhang H, Qi J, Bradner J, Nair S, Chen LF. Brd4 maintains constitutively active nf-κ b in cancer cells by binding to acetylated rela. Oncogene. 2014 May;33(18):2395-404. 
119. Suarez-Alvarez B, Morgado-Pascual JL, Rayego-Mateos S, Rodriguez RM, Rodrigues-Diez R, Cannata-Ortiz P, Sanz AB, Egido J, Tharaux PL, Ortiz A, Lopez-Larrea C. Inhibition of bromodomain and extraterminal domain family proteins ameliorates experimental renal damage. Journal of the American Society of Nephrology. 2017 Feb 1;28(2):504-19. 
120. Sanchez-Niño MD, Benito-Martin A, Ortiz A. New paradigms in cell death in human diabetic nephropathy. Kidney international. 2010 Oct 2;78(8):737-44. 
121. Thompson PJ, Shah A, Apostolopolou H, Bhushan A. BET Proteins Are Required for Transcriptional Activation of the Senescent Islet Cell Secretome in Type 1 Diabetes. International journal of molecular sciences. 2019 Jan;20(19):4776. 
122. Deeney JT, Belkina AC, Shirihai OS, Corkey BE, Denis GV. BET bromodomain proteins Brd2, Brd3 and Brd4 selectively regulate metabolic pathways in the pancreatic β-cell. PloS one. 2016 Mar 23;11(3): e0151329. 
123. Huijbregts L, Petersen MB, Berthault C, Hansson M, Aiello V, Rachdi L, Grapin-Botton A, Honore C, Scharfmann R. Bromodomain and extra terminal protein inhibitors promote pancreatic endocrine cell fate. Diabetes. 2019 Apr 1;68(4):761-73. 
124. Wang J, Hu J, Chen X, Huang C, Lin J, Shao Z, Gu M, Wu Y, Tian N, Gao W, Zhou Y. BRD4 inhibition regulates MAPK, NF‐κB signals, and autophagy to suppress MMP‐13 expression in diabetic intervertebral disc degeneration. The FASEB Journal. 2019 Oct;33(10):11555-66. 
125. Guo M, Wang HX, Chen WJ. BET-inhibition by JQ1 alleviates streptozotocin-induced diabetic cardiomyopathy. Toxicology and applied pharmacology. 2018 Aug 1; 352:9-18. 
126. Wang Q, Sun Y, Li T, Liu L, Zhao Y, Li L, Zhang L, Meng Y. Function of BRD4 in the pathogenesis of high glucose-induced cardiac hypertrophy. Molecular medicine reports. 2019 Jan 1;19(1):499-507. 
127. Zuo H, Wang S, Feng J, Liu X. BRD4 contributes to high-glucose-induced podocyte injury by modulating Keap1/Nrf2/ARE signaling. Biochimie. 2019 Oct 1; 165:100-7. 
128. Kulikowski E, Halliday C, Johansson J, Sweeney M, Lebioda K, Wong N, Haarhaus M, Brandenburg V, Beddhu S, Tonelli M, Zoccali C. Apabetalone mediated epigenetic modulation is associated with favorable kidney function and alkaline phosphatase profile in patients with chronic kidney disease. Kidney and Blood Pressure Research. 2018;43(2):449-57.
129.  Sumida K, Molnar MZ, Potukuchi PK, Thomas F, Lu JL, Obi Y, Rhee CM, Streja E, Yamagata K, Kalantar-Zadeh K, Kovesdy CP. Prognostic significance of pre-end-stage renal disease serum alkaline phosphatase for post-end-stage renal disease mortality in late-stage chronic kidney disease patients transitioning to dialysis. Nephrology Dialysis Transplantation. 2018 Feb 1;33(2):264-73.
130. Ray KK, Nicholls SJ, Buhr KA, Ginsberg HN, Johansson JO, Kalantar-Zadeh K, Kulikowski E, Toth PP, Wong N, Sweeney M, Schwartz GG. Effect of apabetalone added to standard therapy on major adverse cardiovascular events in patients with recent acute coronary syndrome and type 2 diabetes: a randomized clinical trial. Jama. 2020 Apr 28;323(16):1565-73. 
131. Sanchez-Niño MD, Sanz AB, Carrasco S, Saleem MA, Mathieson PW, Valdivielso JM, Ruiz-Ortega M, Egido J, Ortiz A. Globotriaosylsphingosine actions on human glomerular podocytes: implications for Fabry nephropathy. Nephrology Dialysis Transplantation. 2011 Jun 1;26(6):1797-802.
132. Aguilera-Correa JJ, Madrazo-Clemente P, del Carmen Martínez-Cuesta M, Peláez C, Ortiz A, Sánchez-Niño MD, Esteban J, Requena T. Lyso-Gb3 modulates the gut microbiota and decreases butyrate production. Scientific reports. 2019 Aug 19;9(1):1-0. 
133. van Bommel EJ, Lytvyn Y, Perkins BA, Soleymanlou N, Fagan NM, Koitka-Weber A, Joles JA, Cherney DZ, van Raalte DH. Renal hemodynamic effects of sodium-glucose cotransporter 2 inhibitors in hyperfiltering people with type 1 diabetes and people with type 2 diabetes and normal kidney function. Kidney international. 2020 Apr 1;97(4):631-5. 
134. Soler MJ, Porrini E, Fernandez-Fernandez B, Ortiz A. SGLT2i and postglomerular vasodilation. Kidney international. 2020 Apr 1;97(4):805-6. 
135. Solini A, Seghieri M, Giannini L, Biancalana E, Parolini F, Rossi C, Dardano A, Taddei S, Ghiadoni L, Bruno RM. The effects of dapagliflozin on systemic and renal vascular function display an epigenetic signature. The Journal of Clinical Endocrinology & Metabolism. 2019 Oct;104(10):4253-63. 
136. Fontecha‐Barriuso M, Martín‐Sánchez D, Martinez‐Moreno JM, Carrasco S, Ruiz‐Andrés O, Monsalve M, Sanchez‐Ramos C, Gómez MJ, Ruiz‐Ortega M, Sánchez‐Niño MD, Cannata‐Ortiz P. PGC‐1α deficiency causes spontaneous kidney inflammation and increases the severity of nephrotoxic AKI. The Journal of pathology. 2019 Sep;249(1):65-78. 
137. Fontecha-Barriuso M, Martin-Sanchez D, Martinez-Moreno JM, Monsalve M, Ramos AM, Sanchez-Niño MD, Ruiz-Ortega M, Ortiz A, Sanz AB. The role of PGC-1α and mitochondrial biogenesis in kidney diseases. Biomolecules. 2020 Feb;10(2):347. 
138. Xu L, Natarajan R, Chen Z. Epigenetic risk profile of diabetic kidney disease in high-risk populations. Current diabetes reports. 2019 Mar 1;19(3):9. 
139. Lu HC, Dai WN, He LY. Epigenetic Histone Modifications in the Pathogenesis of Diabetic Kidney Disease. Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy. 2021; 14:329.