Expression profiles of podocytes exposed to high glucose reveal new insights into early diabetic glomerulopathy

Genome-wide association study suggests genetic candidate loci of insulin dysregulation in Finnhorses

Equine metabolic syndrome (EMS) is a common welfare problem in horses worldwide. It is characterized by insulin dysregulation (ID), predisposition to laminitis and often obesity. EMS is multifactorial by nature, with both the environment and genetics contributing to the phenotype. Environmental factors, such as feeding and exercise, can be controlled, thus forming the basis for treatment and prevention. Genetic factors, by contrast, are less well-known and not easily controllable. The aim of this study was to identify potential genetic loci influencing ID/EMS in Finnhorses. A single-breed (Finnhorse) case-control genome-wide association study (GWAS) of ID was conducted with controls that included age-appropriate non-ID horses. ID status was determined with an oral sugar test (OST) for fasted horses. Seventy-one Finnhorses participated (n = 34 ID, n = 37 control). DNA samples (hair roots) were genotyped for 65 157 single-nucleotide polymorphisms (SNPs) with the Illumina Equine SNP70 BeadChip, and these data were analysed for association and FST outliers with genomic tools. P-values that exceeded the suggestive threshold (P = 1.00 ×10-5) were found in SNP BIEC2_383954 (P = 3.45 ×10-6) in chromosome 17 and SNP BIEC2_312374 (P = 1.89 ×10-5) in chromosome 15. Hierarchical and Bayesian FST outlier tests also detected these SNPs. Potential candidate genes associated with the ID close to SNP BIEC2_383954, with functions in carbohydrate metabolism, were Arginine and Glutamate Rich 1 (ARGLU1) and Ephrin-B2 (EFNB2).

Expression profiling of cultured podocytes exposed to nephrotic plasma reveals intrinsic molecular signatures of nephrotic syndrome

BACKGROUND

Nephrotic syndrome (NS) is a common renal disorder in children attributed to podocyte injury. However, children with the same diagnosis have markedly variable treatment responses, clinical courses, and outcomes, suggesting molecular heterogeneity.

PURPOSE

This study aimed to explore the molecular responses of podocytes to nephrotic plasma to identify specific genes and signaling pathways differentiating various clinical NS groups as well as biological processes that drive injury in normal podocytes.

METHODS

Transcriptome profiles from immortalized human podocyte cell line exposed to the plasma of 8 subjects (steroidsensitive nephrotic syndrome [SSNS], n=4; steroid-resistant nephrotic syndrome [SRNS], n=2; and healthy adult individuals [control], n=2) were generated using microarray analysis.

RESULTS

Unsupervised hierarchical clustering of global gene expression data was broadly correlated with the clinical classification of NS. Differential gene expression (DGE) analysis of diseased groups (SSNS or SRNS) versus healthy controls identified 105 genes (58 up-regulated, 47 down-regulated) in SSNS and 139 genes (78 up-regulated, 61 down-regulated) in SRNS with 55 common to SSNS and SRNS, while the rest were unique (50 in SSNS, 84 genes in SRNS). Pathway analysis of the significant (P≤0.05, -1≤ log2 FC ≥1) differentially expressed genes identified the transforming growth factor-β and Janus kinase-signal transducer and activator of transcription pathways to be involved in both SSNS and SRNS. DGE analysis of SSNS versus SRNS identified 2,350 genes with values of P≤0.05, and a heatmap of corresponding expression values of these genes in each subject showed clear differences in SSNS and SRNS.

CONCLUSION

Our study observations indicate that, although podocyte injury follows similar pathways in different clinical subgroups, the pathways are modulated differently as evidenced by the heatmap. Such transcriptome profiling with a larger cohort can stratify patients into intrinsic subtypes and provide insight into the molecular mechanisms of podocyte injury.

Tacrolimus Protects Podocytes from Apoptosis via Downregulation of TRPC6 in Diabetic Nephropathy

Podocyte injury plays an important role in diabetic nephropathy (DN), and apoptosis is one of its mechanisms. The transient receptor potential channel 6 (TRPC6) is expressed in podocytes and mediates podocyte injury induced by high glucose levels. Tacrolimus is a novel immunosuppressive agent that is reported to play an important role in podocyte protection. The purpose of this study was to investigate the potential mechanism of podocyte protection by tacrolimus in a type 2 diabetic mellitus (T2DM) rat model and in immortalized mouse podocytes (MPC5). Transmission electron microcopy was used to evaluate renal injury morphology. After treatment with FK506, we measured 24-hour urinary albumin-to-creatinine ratios and creatinine clearance rates as well as major biochemical parameters such as glucose, insulin, serum creatinine, urea nitrogen, total cholesterol, triglycerides, alanine transaminase, and aspartate aminotransferase. Nephrin and TRPC6 protein expression and podocyte apoptotic rates in vivo and in vitro were measured using immunohistochemical staining, TUNEL assays, and flow cytometry, respectively. Western blot was used to measure expression of cleaved-caspase-3 and bax/bcl-2. Exposed to high glucose (HG), DM rats exhibited disrupted biochemical conditions and impaired podocyte structure. Decreased expression of nephrin and increased expression of TRPC6, cleaved-caspase-3, and bax/bcl-2 ratios were found in podocytes, along with higher apoptotic percentage, while tacrolimus intervention counteracted the effect of HG on podocytes. Our results suggest that tacrolimus protects podocytes during the progression of type 2 diabetic nephropathy, possibly ameliorating podocyte apoptosis by downregulating the expression of TRPC6.

Down-regulation of SETD6 protects podocyte against high glucose and palmitic acid-induced apoptosis, and mitochondrial dysfunction via activating Nrf2-Keap1 signaling pathway in diabetic nephropathy

Diabetic nephropathy (DN), a serious complication of hyperglycemia, is one of the most common causes of end-stage renal disease (ESRD). Glomerular podocyte injury is a major mechanism that leads to DN. However, the mechanisms underlying podocyte injury are ambiguous. In this study, we sought to investigate the contribution of SET domain-containing protein 6 (SETD6) to the pathogenesis of podocyte injury induced by glucose (GLU) and palmitic acid (PA), as well as the underlying mechanisms. Our results showed that GLU and PA treatment significantly decreased SETD6 expression in mouse podocytes. Besides, Cell Counting Kit-8 (CCK-8) and flow cytometry assay demonstrated that silencing of SETD6 silence obviously enhanced cell viability, and suppressed apoptosis in GLU and PA-induced podocytes. We also discovered that downregulation of SETD6 suppressed GLU and PA-induced ROS generation and podocyte mitochondrial dysfunction. Nrf2-Keap1 signaling pathway was involved in the effect of SETD6 on mitochondrial dysfunction. Taken together, silencing of SETD6 protected mouse podocyte against apoptosis and mitochondrial dysfunction through activating Nrf2-Keap1 signaling pathway. Therefore these data provide new insights into new potential therapeutic targets for DN treatment.

Amelioration of Diabetic Nephropathy Using a Retinoic Acid Receptor β2 Agonist

Vitamin A (VA) and its derivatives, known as retinoids, play critical roles in renal development through retinoic acid receptor β2 (RARβ2). Disruptions in VA signaling pathways are associated with the onset of diabetic nephropathy (DN). Despite the known role of RARβ2 in renal development, the effects of selective agonists for RARβ2 in a high-fat diet (HFD) model of DN are unknown. Here we examined whether AC261066 (AC261), a highly selective agonist for RARβ2, exhibited therapeutic effects in a HFD model of DN in C57BL/6 mice. Twelve weeks of AC261 administration to HFD-fed mice was well tolerated with no observable side effects. Compared with HFD-fed mice, HFD + AC261-treated mice had improved glycemic control and reductions in proteinuria and urine albumin-to-creatinine ratio. Several cellular hallmarks of DN were mitigated in HFD + AC261-treated mice, including reductions in tubule lipid droplets, podocyte (POD) effacement, endothelial cell collapse, mesangial expansion, and glomerular basement membrane thickening. Mesangial and tubule interstitial expression of the myofibroblast markers α-smooth muscle actin (α-SMA) and type IV collagen (Col-IV) was lower in HFD + AC261-treated mice compared with HFD alone. Ultrastructural and immunohistochemistry analyses showed that, compared with HFD-fed mice, HFD + AC261-treated mice showed preservation of POD foot process and slit-diaphragm morphology, an increase in the levels of slit-diagram protein podocin, and the transcription factor Wilms tumor-suppressor gene 1 in PODs. Given the need for novel DN therapies, our results warrant further studies of the therapeutic properties of AC261 in DN.

Glomerular Endothelial Cell Stress and Cross-Talk With Podocytes in Early [corrected] Diabetic Kidney Disease

Diabetic kidney disease (DKD) is one of the major causes of morbidity and mortality in diabetic patients and also the leading single cause of end-stage renal disease in the United States. A large proportion of diabetic patients develop DKD and others don't, even with comparable blood glucose levels, indicating a significant genetic component of disease susceptibility. The glomerulus is the primary site of diabetic injury in the kidney, glomerular hypertrophy and podocyte depletion are glomerular hallmarks of progressive DKD, and the degree of podocyte loss correlates with severity of the disease. We know that chronic hyperglycemia contributes to both microvascular and macrovascular complications, as well as podocyte injury. We are beginning to understand the role of glomerular endothelial injury, as well as the involvement of reactive oxygen species and mitochondrial stress, which play a direct role in DKD and in other diabetic complications. There is, however, a gap in our knowledge that links genetic susceptibility to early molecular mechanisms and proteinuria in DKD. Emerging research that explores glomerular cell's specific responses to diabetes and cell cross-talk will provide mechanistic clues that underlie DKD and provide novel avenues for therapeutic intervention.

Substrate reduction therapy for Krabbe's disease

Krabbe's disease (KD) is a lysosomal storage disorder in which galactosylceramide, a major glycosphingolipid of myelin, and psychosine (galactose-sphingosine) cannot be adequately metabolized because of a deficiency in galactosylceramidase. Substrate reduction therapy (SRT) has been tested in preclinical studies. The premise of SRT is to reduce the synthesis of substrates that are not adequately digested so that the substrate burden is lowered, resulting in less accumulation of unmetabolized material. SRT is used for Gaucher's disease, in which inhibitors of the terminal biosynthetic step are used. Unfortunately, an inhibitor for the final step of galactosylceramide biosynthesis, i.e., UDP glycosyltransferase 8 (a.k.a. UDP-galactose ceramide galactosyltransferase), has not been found. Approaches that inhibit an earlier biosynthetic step or that lessen the substrate burden by other means, such as genetic manipulations, have been tested in the twitcher mouse model of KD. Either as a stand-alone therapy or in combination with other approaches, SRT slowed the disease course, indicating that this approach has potential therapeutic value. For instance, in individuals with adult-onset disease, SRT theoretically could lessen the production of substrates so that residual enzymatic activity could adequately manage the lower substrate burden. In more severe forms of disease, SRT theoretically could be part of a combination therapy. However, SRT has the potential to impair normal function by reducing the synthesis of galactosylceramide to levels that impede myelin function, or SRT could have other deleterious effects. Thus, multiple issues need to be resolved before this approach is ready for testing in humans. © 2016 Wiley Periodicals, Inc.

Upregulation of α3β1-Integrin in Podocytes in Early-Stage Diabetic Nephropathy

Background. Podocyte injury plays an important role in the onset and progression of diabetic nephropathy (DN). Downregulation of α3β1-integrin expression in podocytes is thought to be associated with podocyte detachment from the glomerular basement membrane, although the mechanisms remain obscure. To determine the mechanism of podocyte detachment, we analyzed the expression levels of α3β1-integrin in podocytes in early and advanced stages of DN. Methods. Surgical specimens from DN patients were examined by in situ hybridization, and the expression levels of α3- and β1-integrin subunits in glomeruli of early (n = 6) and advanced (n = 8) stages were compared with those of normal glomeruli (n = 5). Heat-sensitive mouse podocytes (HSMP) were cultured with TGF-β1 to reproduce the microenvironment of glomeruli of DN, and the expression levels of integrin subunits and the properties of migration and attachment were examined. Results. Podocytes of early-stage DN showed upregulation of α3- and β1-integrin expression while those of advanced stage showed downregulation. Real-time PCR indicated a tendency for upregulation of α3- and β1-integrin in HSMP cultured with TGF-β1. TGF-β1-stimulated HSMP also showed enhanced in vitro migration and attachment on collagen substrate. Conclusions. The results suggested that podocyte detachment during early stage of DN is mediated through upregulation of α3β1-integrin.

Effects of ROS-relative NF-κB signaling on high glucose-induced TLR4 and MCP-1 expression in podocyte injury

High glucose (HG) induced inflammation is central to progression in diabetic nephropathy (DN). Recent studies have suggested that nuclear factor-kappa B (NF-κB) signaling activation is associated with DN, and podocyte damage may be involved in orchestrating these effects. Therefore, the aim of this study was to investigate the effects of NF-κB signaling on podocytes under HG conditions. The effects of HG and NF-κB signaling on podocytes were assessed by CCK-8 assay, cellular NF-κB translocation assay, measurement of reactive oxygen species (ROS) and Western blot analysis. We found that HG reduced cell viability, activated NF-κB signaling and up-regulated toll-like receptor 4 (TLR4) and monocyte chemoattractant protein-1 (MCP-1). In these cells, NF-κB inhibition with ammonium pyrrolidinethiocarbamate (PDTC) resulted in effectively constraining TLR4 and MCP-1 up-regulation, indicating that protective effects associated with the inhibition of NF-κB were linked to TLR4 and MCP-1 down-regulation in podocytes. Furthermore, HG significantly increased the production of intracellular ROS. Pretreatment with N-acetyl-l-cysteine (NAC) significantly inhibited intracellular ROS generation and increased cell viability, accompanied by a significant NF-κB inhibition and suppression of TLR4 and inflammatory cytokine MCP-1 expression. Collectively, our novel data suggest that HG induces the over-experssion of TLR-4 and MCP-1 through a NF-κB-dependent signaling. NF-κB-mediated increased inflammation is possibly via ROS and contributes to the cell injury. These results may provide potential therapeutic target for diabetic nephropathy in the future.

Role of podocyte B7-1 in diabetic nephropathy

Podocyte injury and resulting albuminuria are hallmarks of diabetic nephropathy, but targeted therapies to halt or prevent these complications are currently not available. Here, we show that the immune-related molecule B7-1/CD80 is a critical mediator of podocyte injury in type 2 diabetic nephropathy. We report the induction of podocyte B7-1 in kidney biopsy specimens from patients with type 2 diabetes. Genetic and epidemiologic studies revealed the association of two single nucleotide polymorphisms at the B7-1 gene with diabetic nephropathy. Furthermore, increased levels of the soluble isoform of the B7-1 ligand CD28 correlated with the progression to ESRD in individuals with type 2 diabetes. In vitro, high glucose conditions prompted the phosphatidylinositol 3 kinase-dependent upregulation of B7-1 in podocytes, and the ectopic expression of B7-1 in podocytes increased apoptosis and induced disruption of the cytoskeleton that were reversed by the B7-1 inhibitor CTLA4-Ig. Podocyte expression of B7-1 was also induced in vivo in two murine models of diabetic nephropathy, and treatment with CTLA4-Ig prevented increased urinary albumin excretion and improved kidney pathology in these animals. Taken together, these results identify B7-1 inhibition as a potential therapeutic strategy for the prevention or treatment of diabetic nephropathy.

Urine biomarkers for monitoring juvenile lupus nephritis: a prospective longitudinal study

BACKGROUND

In juvenile-onset systemic lupus erythematosus (JSLE), renal involvement (lupus nephritis) is frequently seen and can result in long-term morbidity. This prospective longitudinal study aimed to identify the utility of standard and/or novel biomarkers for monitoring and predicting lupus nephritis in a real world setting.

METHODS

Using an unselected JSLE cohort, urine samples were collected during routine clinical review. Protein concentrations of urinary monocyte chemo-attractant protein 1 (uMCP1) and neutrophil gelatinase-associated lipocalin (uNGAL) were analysed along with standard disease activity markers, and were compared with current and subsequent disease activity.

RESULTS

JSLE patients (n = 64; median age 14.1 years) were seen at 3 (interquartile range: 2-5) clinical reviews over 364 (182-532) days. Multivariate analysis demonstrated uMCP1 and serum C3 as independent variables (p < 0.001) for active renal disease at the time of the current review. uMCP1 was an excellent predictor of improved renal disease over time (AUC: 0.81; p = 0.013). uNGAL was a good predictor of worsened renal disease activity (AUC 0.76; p = 0.04) over time.

CONCLUSION

Biomarkers (uMCP1, serum C3) can indicate current renal involvement in JSLE, whilst uMCP1 and uNGAL are able to predict subsequent renal disease activity changes. Moving towards biomarker-led monitoring may improve the renal outcome for our patients.

New insights into the pathology of podocyte loss: mitotic catastrophe

Podocytes represent an essential component of the kidney's glomerular filtration barrier. They stay attached to the glomerular basement membrane via integrin interactions that support the capillary wall to withstand the pulsating filtration pressure. Podocyte structure is maintained by a dynamic actin cytoskeleton. Terminal differentiation is coupled with permanent exit from the cell cycle and arrest in a postmitotic state. Postmitotic podocytes do not have an infinite life span; in fact, physiologic loss in the urine is documented. Proteinuria and other injuries accelerate podocyte loss or induce death. Mature podocytes are unable to replicate and maintain their actin cytoskeleton simultaneously. By the end of mitosis, cytoskeletal actin forms part of the contractile ring, rendering a round shape to podocytes. Therefore, when podocyte mitosis is attempted, it may lead to aberrant mitosis (ie, mitotic catastrophe). Mitotic catastrophe implies that mitotic podocytes eventually detach or die; this is a previously unrecognized form of podocyte loss and a compensatory mechanism for podocyte hypertrophy that relies on post-G1-phase cell cycle arrest. In contrast, local podocyte progenitors (parietal epithelial cells) exhibit a simple actin cytoskeleton structure and can easily undergo mitosis, supporting podocyte regeneration. In this review we provide an appraisal of the in situ pathology of mitotic catastrophe compared with other proposed types of podocyte death and put experimental and renal biopsy data in a unified perspective.

Defining cell-type specificity at the transcriptional level in human disease

Cell-lineage–specific transcripts are essential for differentiated tissue function, implicated in hereditary organ failure, and mediate acquired chronic diseases. However, experimental identification of cell-lineage–specific genes in a genome-scale manner is infeasible for most solid human tissues. We developed the first genome-scale method to identify genes with cell-lineage–specific expression, even in lineages not separable by experimental microdissection. Our machine-learning–based approach leverages high-throughput data from tissue homogenates in a novel iterative statistical framework. We applied this method to chronic kidney disease and identified transcripts specific to podocytes, key cells in the glomerular filter responsible for hereditary and most acquired glomerular kidney disease. In a systematic evaluation of our predictions by immunohistochemistry, our in silico approach was significantly more accurate (65% accuracy in human) than predictions based on direct measurement of in vivo fluorescence-tagged murine podocytes (23%). Our method identified genes implicated as causal in hereditary glomerular disease and involved in molecular pathways of acquired and chronic renal diseases. Furthermore, based on expression analysis of human kidney disease biopsies, we demonstrated that expression of the podocyte genes identified by our approach is significantly related to the degree of renal impairment in patients. Our approach is broadly applicable to define lineage specificity in both cell physiology and human disease contexts. We provide a user-friendly website that enables researchers to apply this method to any cell-lineage or tissue of interest. Identified cell-lineage–specific transcripts are expected to play essential tissue-specific roles in organogenesis and disease and can provide starting points for the development of organ-specific diagnostics and therapies.

Wnt/β-catenin signalling pathway mediates high glucose induced cell injury through activation of TRPC6 in podocytes

OBJECTIVES

Diabetic nephropathy is a major complication of diabetes and a frequent cause of end-stage renal disease and recent studies suggest that podocyte damage may play a role in the pathogenesis of this. At early onset of diabetic nephropathy there is podocyte drop-out, which is thought to provoke glomerular albuminuria and subsequent glomerular injury; however, the underlying molecular mechanisms of this remain poorly understood. Here we report that we tested the hypothesis that early diabetic podocyte injury is caused, at least in part, by up-regulation of transient receptor potential cation channel 6 (TRPC6), which is regulated by the canonical Wnt signalling pathway, in mouse podocytes.

MATERIALS AND METHODS

Mechanism of injury initiation in mouse podocytes, by high concentration of D-glucose (HG, 30 mM), was investigated by MTT, flow cytometry, real-time quantitative PCR, and western blot analysis.

RESULTS

HG induced apoptosis and reduced viability of differentiated podocytes. It caused time-dependent up-regulation of TRPC6 and activation of the canonical Wnt signalling pathway, in mouse podocytes. In these cells, blockade of the Wnt signalling pathway by dickkopf related protein 1 (Dkk1) resulted in effective reduction of TRPC6 up-regulation and amelioration of podocyte apoptosis. Furthermore, reduction of cell viability induced by HG was attenuated by treatment with Dkk1.

CONCLUSION

These findings indicate that the Wnt/β-catenin signalling pathway may potentially be active in pathogenesis of TRPC6-mediated diabetic podocyte injury.

Redox proteomics in study of kidney-associated hypertension: new insights to old diseases

SIGNIFICANCE

The kidney helps to maintain low blood pressure in the human body, and impaired kidney function is a common attribute of aging that is often associated with high blood pressure (hypertension). Kidney-related pathologies are important contributors (either directly or indirectly) to overall human mortality. In comparison with other organs, kidney has an unusually wide range of oxidative status, ranging from the well-perfused cortex to near-anoxic medulla.

RECENT ADVANCES

Oxidative stress has been implicated in many kidney pathologies, especially chronic kidney disease, and there is considerable research interest in oxidative stress biomarkers for earlier prediction of disease onset. Proteomics approaches have been taken to study of human kidney tissue, serum/plasma, urine, and animal models of hypertension.

CRITICAL ISSUES

Redox proteomics, in which oxidative post-translational modifications can be identified in protein targets of oxidative or nitrosative stress, has not been very extensively pursued in this set of pathologies.

FUTURE DIRECTIONS

Proteomics studies of kidney and related tissues have relevance to chronic kidney disease, and redox proteomics, in particular, represents an under-exploited toolkit for identification of novel biomarkers in this commonly occurring pathology.

Endothelial lipase is localized to follicular epithelial cells in the thyroid gland and is moderately expressed in adipocytes

Endothelial lipase (EL), a member of the triglyceride lipase gene family, has been shown to be a key player in HDL metabolism. Northern blots revealed that EL was highly expressed in endothelium, thyroid, lung, placenta, liver, and testis. In liver and adrenal gland, EL protein was localized with vascular endothelial cells but not parenchymal cells. EL was shown to be upregulated in tissues such as atherosclerotic plaque where it was located in macrophages, endothelial cells, and medial smooth muscle cells. The purpose of this study was to investigate the cellular localization of EL in thyroid and other tissues where EL is known to be expressed. Besides its presence in vascular endothelial and smooth muscle cells, EL protein was detected in the epithelial cells that line the follicles within the thyroid gland. EL-specific immunostaining was also found near the cell surface as well as in the cytoplasm of adipocytes. Using immunoblots, EL expression was confirmed in cultured human omental and subcutaneous adipocytes. EL expression, however, was not found in preadipocytes. These findings suggest that EL plays a role in thyroid and adipocyte biology in addition to its well-known role in endothelial function and HDL metabolism.

Effects of Epigallocatechin-3-Gallate on the Expression of TGF-β1, PKC α/βII, and NF-κB in High-Glucose-Stimulated Glomerular Epithelial Cells

Epigallocatechin-3-gallate (EGCG) is the most potent antioxidant polyphenol in green tea. In the present study, we investigated whether EGCG plays a role in the expression of transforming growth factor-beta1 (TGF-β1), protein kinase C (PKC) α/βII, and nuclear factor-kappaB (NF-κB) in glomerular epithelial cells (GECs) against high-glucose injury. Treatment with high glucose (30 mM) increased reactive oxygen species (ROS)/lipid peroxidation (LPO) and decreased glutathione (GSH) in GECs. Pretreatment with 100 µM EGCG attenuated the increase in ROS/LPO and restored the levels of GSH, whereas ROS, LPO, and GSH levels were not affected by treatment with 30 mM mannitol as an osmotic control. Interestingly, high-glucose treatment affected 3 separate signal transduction pathways in GECs. It increased the expression of TGF-β1, PKC α/βII, and NF-κB in GECs, respectively. EGCG (1, 10, 100 µM) pretreatment significantly decreased the expression of TGF-β1 induced by high glucose in a dose-dependent manner. In addition, EGCG (100 µM) inhibited the phosphorylation of PKC α/βII caused by glucose at 30 mM. Moreover, EGCG (1, 10, 100 µM) pretreatment significantly decreased the transcriptional activity of NF-κB induced by high glucose in a dose-dependent manner. These data suggest that EGCG could be a useful factor in modulating the injury to GECs caused by high glucose.