Pathology Of Diabetic Nephropathy Research Articles

A translational model of chronic diabetic nephropathy in the Nile grass rat.

Diabetic nephropathy (DN) is a major healthcare challenge for individuals with diabetes and associated with increased cardiovascular morbidity and mortality. The existing rodent models do not fully represent the complex course of the human disease. Hence, developing a translational model of diabetes that reproduces both the early and the advanced characteristics of DN and faithfully recapitulates the overall human pathology is an unmet need. Here, we introduce the Nile grass rat (NGR) as a novel model of DN and characterize key pathologies underlying DN. NGRs spontaneously developed insulin resistance, reactive hyperinsulinemia, and hyperglycemia. Diabetic NGRs evolved DN and the key histopathological aspects of the human advanced DN, including glomerular hypertrophy, infiltration of mononuclear cells, tubular dilatation, and atrophy. Enlargement of the glomerular tufts and the Bowman's capsule areas accompanied the expansion of the Bowman's space. Glomerular sclerosis, renal arteriolar hyalinosis, Kimmelsteil-Wilson nodular lesions, and protein cast formations in the kidneys of diabetic NGR occurred with DN. Diabetic kidneys displayed interstitial and glomerular fibrosis, key characteristics of late human pathology as well as thickening of the glomerular basement membrane and podocyte effacement. Signs of injury included glomerular lipid accumulation, significantly more apoptotic cells, and expression of KIM-1. Diabetic NGRs became hypertensive, a known risk factor for kidney dysfunction, and showed decreased glomerular filtration rate. Diabetic NGRs recapitulate the breadth of human DN pathology and reproduce the consequences of chronic kidney disease, including injury and loss of function of the kidney. Hence, NGR represents a robust model for studying DN-related complications and provides a new foundation for more detailed mechanistic studies of the genesis of nephropathy, and the development of new therapeutic approaches.

Whole transcriptome mapping reveals the lncRNA regulatory network of TFP5 treatment in diabetic nephropathy.

TFP5 is a Cdk5 inhibitor peptide, which could restore insulin production. However, the role of TFP5 in diabetic nephropathy (DN) is still unclear. This study aims to characterize the transcriptome profiles of mRNA and lncRNA in TFP5-treated DN mice to mine key lncRNAs associated with TFP5 efficacy. We evaluated the role of TFP5 in DN pathology and performed RNA sequencing in C57BL/6Jcontrol mice, C57BL/6J db/db model mice, and TFP5 treatment C57BL/6J db/db model mice. The differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) were analyzed. WGCNA was used to screen hub-gene of TFP5 in treatment of DN. Our results showed that TFP5 therapy ameliorated renal tubular injury in DN mice. In addition, compared with the control group, the expression profile of lncRNAs in the model group was significantly disordered, while TFP5 alleviated the abnormal expression of lncRNAs. A total of 67 DElncRNAs shared among the three groups, 39 DElncRNAs showed a trend of increasing in the DN group and decreasing after TFP treatment, while the remaining 28 showed the opposite trend. DElncRNAs were enriched in glycosphingolipid biosynthesis signaling pathways, NF-κB signaling pathways, and complement activation signaling pathways. There were 1028 up-regulated and 1117 down-regulated DEmRNAs inthe model group compared to control group, and 123 up-regulated and 153 down-regulated DEmRNAs in theTFP5 group compared to themodel group. The DEmRNAs were involved in PPAR and MAPK signaling pathway. We confirmed that MSTRG.28304.1 is a key DElncRNA for TFP5 treatment of DN. TFP5 ameliorated DN maybe by inhibiting MSTRG.28304.1 through regulating the insulin resistance and PPAR signaling pathway. The qRT-PCR results confirmed the reliability of the sequencing data through verifying the expression of ENSMUST00000211209, MSTRG.31814.5, MSTRG.28304.1, and MSTRG.45642.14. Overall, the present study provides novel insights into molecular mechanisms of TFP5 treatment in DN.

Expression profiles and potential roles of serum tRNA‑derived fragments in diabetic nephropathy.

Diabetic nephropathy (DN) is one of the most important causes of end-stage renal disease and current treatments are ineffective in preventing its progression. Transfer RNA (tRNA)-derived fragments (tRFs), which are small non-coding fragments derived from tRNA precursors or mature tRNAs, have a critical role in various human diseases. The present study aimed to investigate the expression profile and potential functions of tRFs in DN. High-throughput sequencing technology was employed to detect the differential serum levels of tRFs between DN and diabetes mellitus and to validate the reliability of the sequencing results using reverse transcription-quantitative PCR. Ultimately, six differentially expressed (DE) tRFs were identified (P<0.05; |log2fold change| ≥1), including three upregulated (tRF5-GluCTC, tRF5-AlaCGC and tRF5-ValCAC) and three downregulated tRFs (tRF5-GlyCCC, tRF3-GlyGCC and tRF3-IleAAT). Potential functions and regulatory mechanisms of these DE tRFs were further evaluated using an applied bioinformatics-based analysis. Gene ontology analysis revealed that the DE tRFs are mainly enriched in biological processes, including axon guidance, Rad51 paralog (Rad51)B-Rad51C-Rad51D-X-Ray repair cross-complementing 2 complex, nuclear factor of activated T-cells protein binding and fibroblast growth factor-activated receptor activity. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that they are associated with axon guidance, neurotrophin signaling, mTOR signaling, AMPK signaling and epidermal growth factor receptor family signaling pathways. In conclusion, the present findings indicated that tRFs were DE in DN and may be involved in the regulation of DN pathology through multiple pathways, thereby providing a new perspective for the study of DN therapeutic targets.

Knockdown of GPRC5B alleviates the high glucose-induced inflammation and extracellular matrix deposition of podocyte through inhibiting NF-κB pathway.

Diabetes is a serious disease that could greatly increase the risk of cardiovascular complications, whereas the underlying pathology of DN is still unknown. GPRC5B is a member of the RAIG subfamily of type 3 (family C) GPCR, and its role in DN is still unclear. To unveil the role of GPRC5B in diabetic nephropathy (DN) progression and investigate the potential signaling pathway. Podocytes were stimulated with high glucose and expression of GPRC5B was analyzed by qPCR and western blot. Then the level of GPRC5B was depleted by siRNA transfection and inflammatory cytokine level was monitored by ELISA assay. The ECM depostion and the activation of NF-κB pathway were detected by Immunoblot. We investigated the possible role of GPRC5B in the pathology of diabetic nephropathy. We found GPRC5B was highly expressed in high glocuse (HG) induced podocytes. The depletion of GPRC5B inhibited HG induced cell inflammation. In addition, the ablation of GPRC5B suppressed the HG induced ECM deposition. We further found GPRC5B could alleviate the inflammation and extracellular matrix deposition of HG-induced podocytes through NF-κB pathway. We therefore thought GPRC5B could serve as a promising target for the treatment of diabetic nephropathy. G-protein-coupled receptors.

POS-187 PROGNOSTIC ROLES OF URINARY TUBULAR INJURY MARKERS IN DIABETIC NEPHROPATHY

Tubular damage is common in the pathology of diabetic nephropathy (DN) and the severity of interstitial fibrosis and tubular atrophy associates with DN progression. Diabetic patients could have decreased kidney function without overt proteinuria, which highlighted the importance of tubular injury markers in DN management. However, the prognostic roles of urinary tubular injury markers are not well established. This retrospective study sought to correlate current clinically used urinary tubular injury markers with DN pathological features and renal outcomes.

In vitro anti-oxidant property and reduction of hyperglycemia-induced oxidation by hydroalcoholic extract of Phyllanthus emblica in cultured mesangial cell lines

The pathology of diabetic nephropathy (DN) is due to long-term poor blood sugar control leading to changes in the filtration unit of the kidneys. However, drugs used to offer renal protection cause many side effects. Therefore, it is necessary to develop a new drug or food supplement that acts on multiple factors of DN. Studies have confirmed that Phyllanthus emblica (PE) has anti-diabetic, free radical scavenging, anti-inflammatory, immune regulation, antipyretic, analgesic, wound healing, anti-atherosclerosis, liver protection, kidney protection, and neuroprotection properties. In this study, we explored the antioxidant activity and ability to maintain redox balance in MES-13 cell line. We performed DPPH and FRAP assay to detect the antioxidant property of PE. SDS-PAGE was performed to understand the changes in the types of protein of the glomerular cells treated (24 hr) with high sugar (25 mM) with/without PE extract (10 & 100 μg/ml). Oxidative stress in cells was detected by RedCC-1 staining. Significant antioxidant activity was shown by the extract (IC50 – 108.9 μg/ml) compared to Trolox (IC50 – 60.9 μg/ml). The protein pattern of high glucose (25 mM) treated cells significantly reduced compared to normal and PE treated cells. Mitochondrial dysfunction and cellular oxidative stress produced by high glucose (intensity - 222.04 units) supplementation was significantly reduced by PE (intensity - 38.67 units). In conclusion, PE extract possesses an antioxidant property that can reduce the glomerular damage and oxidative stress in the cells caused by high glucose exposure

Adipose mesenchymal stem cell-derived extracellular vesicles containing microRNA-26a-5p target TLR4 and protect against diabetic nephropathy

Diabetic nephropathy (DN) is a complication of diabetes that is increasing in prevalence in China. Extracellular vesicles (EVs) carrying microRNAs (miRs) may represent a useful tool in the development of therapies for DN. Here, we report that EVs released by adipose-derived mesenchymal stem cells (ADSCs) during DN contain a microRNA, miR-26a-5p, that suppresses DN. Using bioinformatic analyses, we identified differentially expressed miRs in EVs from ADSCs and in DN and predicted downstream regulatory target genes. We isolated mesenchymal stem cells (MSCs) from adipose tissues and collected EVs from the ADSCs. We exposed mouse glomerular podocytes and MP5 cells to high glucose (HG), ADSC-derived EVs, miR-26a-5p inhibitor/antagomir, Toll-like receptor 4 (TLR4) plasmids, or the NF-κB pathway activator (phorbol-12-myristate-13-acetate, or PMA). We used the cell counting kit-8 (CCK-8) assay and flow cytometry to investigate the impact of miR-26a-5p on cell viability and apoptosis and validated the results of these assays with in vivo experiments in nude mice. We found that in DN, miR-26a-5p is expressed at very low levels, whereas TLR4 is highly expressed. Of note, EVs from ADSCs ameliorated the pathological symptoms of DN in diabetic mice and transferred miR-26a-5p to HG-induced MP5 cells, improving viability while suppressing the apoptosis of MP5 cells. We also found that miR-26a-5p protects HG-induced MP5 cells from injury by targeting TLR4, inactivating the NF-κB pathway, and downregulating vascular endothelial growth factor A (VEGFA). Moreover, ADSC-derived EVs transferred miR-26a-5p to mouse glomerular podocytes, which ameliorated DN pathology. These findings suggest that miR-26a-5p from ADSC-derived EVs protects against DN.

Impact of sex on diabetic nephropathy and the renal transcriptome in UNx db/db C57BLKS mice.

Diabetic nephropathy (DN) is associated with albuminuria and loss of kidney function and is the leading cause of end‐stage renal disease. Despite evidence of sex‐associated differences in the progression of DN in human patients, male mice are predominantly being used in preclinical DN research and drug development. Here, we compared renal changes in male and female uninephrectomized (UNx) db/db C57BLKS mice using immunohistochemistry and RNA sequencing. Male and female UNx db/db mice showed similar progression of type 2 diabetes, as assessed by obesity, hyperglycemia, and HbA1c. Progression of DN was also similar between sexes as assessed by kidney and glomerular hypertrophy as well as urine albumin‐to‐creatinine ratio being increased in UNx db/db compared with control mice. In contrast, kidney collagen III and glomerular collagen IV were increased only in female UNx db/db as compared with respective control mice but showed a similar tendency in male UNx db/db mice. Comparison of renal cortex transcriptomes by RNA sequencing revealed 66 genes differentially expressed (p < .01) in male versus female UNx db/db mice, of which 9 genes were located on the sex chromosomes. In conclusion, male and female UNx db/db mice developed similar hallmarks of DN pathology, suggesting no or weak sex differences in the functional and structural changes during DN progression.

MiR-218 regulates diabetic nephropathy via targeting IKK-β and modulating NK-κB-mediated inflammation.

Diabetic nephropathy (DN) is a common clinically relevant complication of diabetes that is associated with damage to the capillaries, yet the etiology of this condition remains unclear. Nuclear factor-kappa B (NF-κB) activation is known to be associated with DN-related inflammation and disease progression. Recent work indicated that microRNAs are diagnostic biomarkers of DN progression associated with inflammation in the progression of DN. miR-218 is known to play key regulatory roles in certain cancers in humans, while its influence on DN pathology remains uncertain. The present study, therefore, sought to assess how miR-218 influences the progression of disease in both a rat streptozotocin-induced model of DN and as well as an in vitro model system in which mouse podocytes were stimulated with high glucose levels. We found miR-218 to be markedly downregulated in both model systems relative to appropriate controls, and this downregulation was associated with IKK-β upregulation. In DN rat model, overexpressing miR-218 was sufficient to reduce renal injury. We further determined that podocyte proliferation was markedly impaired by glucose treatment, leading to the apoptotic death of these cells, and miR-218 mimics were able to reduce these phenotypes. Overexpressing miR-218 also significantly dampened inflammatory responses in this model system, as evidenced by reduced tumor necrosis factor-α, interleukin-6 (IL-6), IL-1β, and MCP-1 levels. We then confirmed that miR-218 targeting the messenger RNA encoding IKK-β using a dual-luciferase reporter assay. Together, our results provide clear evidence that miR-218 regulate NF-κB-mediated inflammation, which is central to DN progression.

494-P: Whole-Kidney 3D Imaging and Image Analysis Enables Detailed Quantification of Diabetic Nephropathy Features in the Uninephrectomized db/db Mouse Model

Diabetic nephropathy (DN) is a serious complication of diabetes and the leading cause of end-stage renal disease. To reproducibly test novel therapies, there is a need for precise quantification of DN pathology in rodent models. We compared the accelerated development of DN in male and female uninephrectomized db/db mice using advanced imaging techniques. Unilateral nephrectomy (UNx) was performed in 7-8 weeks old male and female db/db mice. Sham-operated db/+ mice served as controls. Kidneys were preserved for histology and stereology. In a separate study, UNx was performed in 18 weeks old male db/db mice. These mice and control db/+ mice were injected with lectin-594 prior to termination to visualize glomerular morphology by 3D light sheet microscopy. All mice were terminated at 24 weeks of age. Male and female db/db UNx mice showed comparable increases in albuminuria. Total glomerular volume was markedly higher in male and female db/db UNx mice compared to db/+ controls (mean males; 4.42 vs. 2.71 mm3; p&amp;lt;0.001; females; 5.04 vs. 2.69 mm3; p&amp;lt;0.001). Tubulointerstitial collagen III immuno-staining was significantly increased only in female db/db UNx mice compared to db/+ mice. In contrast, total glomerular collagen IV levels were increased in male db/db UNx mice compared to db/+ controls (mean 1.30 vs. 0.80 mm3; p&amp;lt;0.01), and female db/db UNx mice displayed increased glomerular collagen IV compared to male db/db UNx mice (mean 1.80 vs. 1.30 mm3; p&amp;lt;0.05). 3D imaging at 24 weeks following UNx at 18 weeks of age confirmed expansion in glomerular volume (median db/+ 96.000 vs. db/db 145.000 µm3). Moreover, a marked increase was seen in cortical lectin-594 staining, indicating glomerular leakage in db/db UNx mice. In conclusion, male and female db/db UNx mice displayed comparable features of DN and both constitute valid models for DN. The use of whole-kidney 3D imaging provides a novel avenue for assessment of individual glomerular volume and permeability. Disclosure L.N. Fink: Employee; Self; Gubra. Stock/Shareholder; Self; Novo Nordisk A/S. F.E. Sembach: Consultant; Self; Novo Nordisk A/S. Employee; Self; Gubra. U. Roostalu: Employee; Self; Gubra. T. Johansen: Employee; Self; Gubra. J.L. Skytte: Employee; Self; Gubra. T. Secher: Employee; Self; Gubra. Employee; Spouse/Partner; Novo Nordisk A/S. Stock/Shareholder; Self; Gubra. Stock/Shareholder; Spouse/Partner; Novo Nordisk A/S. K. Fosgerau: Stock/Shareholder; Self; Gubra. N. Vrang: Board Member; Self; Gubra. Stock/Shareholder; Self; Gubra. J. Jelsing: Stock/Shareholder; Self; Gubra. J. Hecksher-Sørensen: Employee; Self; Gubra. Stock/Shareholder; Self; Novo Nordisk A/S. T.X. Pedersen: Employee; Self; Gubra.

Supplementation of Abelmoschus manihot Ameliorates Diabetic Nephropathy and Hepatic Steatosis by Activating Autophagy in Mice.

Diabetic nephropathy (DN) is a diabetic complication marked by albuminuria and a decline of the glomerular filtration rate. Diabetic kidneys are defective in the autophagy process and mitochondrial function and their enhancement of activity alleviates the pathology. In this paper, we developed a mouse model of DN by a combined treatment of a high-fat diet and streptozotocin after unilateral nephrectomy and supplementation with flower or leaf extracts of Abelmoschus manihot (AM) were tested. The preventive effects of the extracts on DN pathology and changes on autophagy and mitochondrial proteins were investigated. DN mice showed a significant increase in fasting blood glucose, plasma creatinine, blood urea nitrogen, and urinary albumin levels. Periodic acid–Schiff and Sirius red staining of the diabetic kidney presented a significant change in glomerular and tubular structures that was associated with podocyte loss and fibrotic protein accumulation. These changes were attenuated by AM extract treatment in DN mice. In addition, hepatic injury, proinflammatory cytokines, and lipid accumulation were decreased by AM extracts in DN mice. As a protective mechanism, AM extracts significantly increased the expression of proteins by regulating autophagy and mitochondrial dynamics, which potentially prevented the kidney and liver from accumulating pathogenic proteins and dysfunctional mitochondria, which alleviated the progression of DN.

Urinary Proteome Analysis Identified Neprilysin and VCAM as Proteins Involved in Diabetic Nephropathy.

Urinary proteome was analyzed and quantified by tandem mass tag (TMT) labeling followed by bioinformatics analysis to study diabetic nephropathy (DN) pathophysiology and to identify biomarkers of a clinical outcome. We included type 2 diabetic normotensive non-obese males with (n = 9) and without (n = 11) incipient DN (microalbuminuria). Sample collection included blood and urine at baseline (control and DN basal) and, in DN patients, after 3 months of losartan treatment (DN treated). Urinary proteome analysis identified 166 differentially abundant proteins between controls and DN patients, 27 comparing DN-treated and DN-basal patients, and 182 between DN-treated patients and controls. The mathematical modeling analysis predicted 80 key proteins involved in DN pathophysiology and 15 in losartan effect, a total of 95 proteins. Out of these 95, 7 are involved in both processes. VCAM-1 and neprilysin stand out of these 7 for being differentially expressed in the urinary proteome. We observed an increase of VCAM-1 urine levels in DN-basal patients compared to diabetic controls and an increase of urinary neprilysin in DN-treated patients with persistent albuminuria; the latter was confirmed by ELISA. Our results point to neprilysin and VCAM-1 as potential candidates in DN pathology and treatment.

Advanced glycation end products mediated cellular and molecular events in the pathology of diabetic nephropathy.

Diabetic nephropathy (DN) is a major cause of morbidity and mortality in diabetic patients and a leading cause of end-stage renal disease (ESRD). Degenerative changes such as glomerular hypertrophy, hyperfiltration, widening of basement membranes, tubulointerstitial fibrosis, glomerulosclerosis and podocytopathy manifest in various degrees of proteinuria in DN. One of the key mechanisms implicated in the pathogenesis of DN is non-enzymatic glycation (NEG). NEG is the irreversible attachment of reducing sugars onto free amino groups of proteins by a series of events, which include the formation of Schiff's base and an Amadori product to yield advanced glycation end products (AGEs). AGE modification of client proteins from the extracellular matrix induces crosslinking, which is often associated with thickening of the basement membrane. AGEs activate several intracellular signaling cascades upon interaction with receptor for AGEs (RAGE), which manifest in aberrant cellular responses such as inflammation, apoptosis and autophagy, whereas other receptors such as AGE-R1, AGE-R3 and scavenger receptors also bind to AGEs and ensue endocytosis and degradation of AGEs. Elevated levels of both serum and tissue AGEs are associated with adverse renal outcome. Increased evidence supports that attenuation of AGE formation and/or inhibition of RAGE activation manifest(s) in improving renal function. This review provides insights of NEG, discusses the cellular and molecular events triggered by AGEs, which manifest in the pathogenesis of DN including renal fibrosis, podocyte epithelial-mesenchymal transition and activation of renin-angiotensin system. Therapies designed to target AGEs, such as inhibitors of AGEs formation and crosslink breakers, are discussed.

MicroRNAs in Diabetic Nephropathy: From Biomarkers to Therapy.

Recent estimates suggest that 1 in 12 of the global population suffers from diabetes mellitus. Approximately 40 % of those affected will go on to develop diabetes-related chronic kidney disease or diabetic nephropathy (DN). DN is a major cause of disability and premature death. Existing tests for prognostic purposes are limited and can be invasive, and interventions to delay progression are challenging. MicroRNAs (miRNAs) are a recently described class of molecular regulators found ubiquitously in human tissues and bodily fluids, where they are highly stable. Alterations in miRNA expression profiles have been observed in numerous diseases. Blood and tissue miRNAs are already established cancer biomarkers, and cardiovascular, metabolic and immune disease miRNA biomarkers are under development. Urinary miRNAs represent a potential novel source of non-invasive biomarkers for kidney diseases, including DN. In addition, recent data suggest that miRNAs may have therapeutic applications. Here, we review the utility of miRNAs as biomarkers for the early detection and progression of DN, assess emerging data on miRNAs implicated in DN pathology and discuss how the data from both fields may contribute to the development of novel therapeutic agents.

Therapeutic potential of digitoflavone on diabetic nephropathy: nuclear factor erythroid 2-related factor 2-dependent anti-oxidant and anti-inflammatory effect.

Nuclear factor erythroid 2-related factor 2 (Nrf2) has emerged as a therapeutic target in many diseases, because it can induce antioxidant enzymes and other cytoprotective enzymes. Moreover, some Nrf2 activators have strong anti-inflammatory activities. Oxidative stress and inflammation are major components involved in the pathology of diabetic nephropathy. In the present study, we evaluated the Nrf2-dependent anti-oxidative and anti-inflammatory effects of digitoflavone in streptozotocin-induced diabetic nephropathy. The molecular mechanisms of digitoflavone were investigated in vitro using SV40-transformed mouse mesangial cells (SV40-Mes13). For the in vivo experiment, diabetes was induced in Nrf2+/+ and Nrf2−/− mice by STZ injection, and digitoflavone was administered 2 weeks after the STZ injection. Digitoflavone induced Nrf2 activation and decreased oxidative damage, inflammation, TGF-β1 expression, extracellular matrix protein expression, and mesangial cell hyperplasia in SV40-Mes13 cells. Digitoflavone-treated Nrf2+/+ mice, but not Nrf2−/− mice, showed attenuated common metabolic disorder symptoms, improved renal performance, minimized pathological alterations, and decreased oxidative damage, inflammatory gene expression, inflammatory cell infiltration, TGF-β1 expression, and extracellular matrix protein expression. Our results show that the anti-oxidative and anti-inflammatory effects of digitoflavone are mediated by Nrf2 activation and that digitoflavone can be used therapeutically to improve metabolic disorders and relieve renal damage induced by diabetes.

Type 2 Diabetes Mellitus and Hepatitis C are Unlikely Contributors in a Case of Progression of Diabetic Nephropathy to End Stage Renal Disease

Progression of diabetic nephropathy to end stage renal disease can occur in the presence of minimal evidence for type 2 diabetes mellitus, and the recent literature indicates the pathology of diabetic nephropathy arises even in the absence of diabetes, suggesting other contributors like over expression of glucose transporter 1 (GLUT1) may have a similar pathogenesis. Although hepatitis C has been implicated in accelerating declines of renal function in diabetic nephropathy in some cases, evidence of hepatitis C activity cannot be assumed to contribute to the worsening renal function in this case. Here we report a case in a 61 year- old female with minimal elevation of Hemoglobin A1C (HbA1C), seropositivity for hepatitis C and anapparent rapid decline of renal function. The patient presented with a previous elevation of serum creatinine concentration from 1.4 to 4.7 mg/dl over the last 23 months. The patient had been treated with insulin and a recent HbA1C was 6.2%, correlating with an average blood glucose concentration of 130-150 mg/dl. There was no history of diabetic retinopathy or neuropathy. The patient was also taking anangiotensin converting enzyme inhibitor (ACEI) and had controlled hypertension over the 2 years prior to the current hospitalization for hematochezia. The serum creatinine then increased to nearly 6 mg/ dl after admission. Acute kidney injury work-up (super imposed on chronic kidney disease and proteinuria) beyond hematochezia, revealed hepatitis C seropositivity without liver failure. The renal biopsy was typical for established diabetic glomerulosclerosis, without evidence of another disease process. A plot of the reciprocal serum creatinine concentration versus time waned linearly as expected for progression of a single, chronic disease process, despite the appearance of promptly falling renal function on the plot of serum creatinine concentration versus time. We suggest that 1) The appearance of rapid decline ofrenal function was actually the natural progression of chronic diabetic nephropathy; 2) Other contributors rather than mild level of hyperglycemia might associated with development of substantial diabetic nephropathy despite clinical absence of other diabetic tissue complications; 3) A role for hepatitis C -persuaded acceleration of renal disease was not supported in this case.

Animal Models of Diabetes and Its Associated Complications

Diabetes is a major threat to global public health. According to the latest data from the International Diabetes Federation (IDF), at least 366 million people are living with diabetes and this number is projected to be 552 million by 2030. At least 50% of people with diabetes suffer from one or two major diabetic complications such as diabetic cardiomyopathy, nephropathy, neuropathy, retinopathy, and diabetic foot diseases. Development of an authentic model of each type of diabetes and their associated complications, which exactly mimic the human pathogenesis, is very crucial not only for a better understanding of the core causes of the diseases but also for the development and routine pharmacological screening of novel anti-diabetic drugs. A number of genetic and nongenetic animal models of the different types of diabetes and their associated complications have been developed in last three decades but none of them are without limitations. This special issue of the Journal of Diabetes Research has been designed to publish original and review articles with novel approaches of the development of animal model of diabetes and its associated complications. Almost all areas of the animal models of diabetes and its associated complications have been covered by this issue. Among the reviews: the animal models of diabetic retinopathy by A. K. W. Lai and A. Lo, animal models of diabetic neuropathy by M. S. Islam, murine models of diabetic neuropathy by L. L. Kong et al., methods and models for metabolic assessment by G. Pacini et al., and porcine models of accelerated coronary atherosclerosis by D. Hamamdzic et al. contributed significantly by summarizing the advantages, disadvantages, and suitability of animal models developed to study the above-mentioned diabetic complications. Many other original papers such as role of adrenomedulin in the renal NADPH oxidase and (pro)renin in diabetic mice by M. Hayashi et al., development of glomerulopathy in the KK.Cg-Ay/J mouse with the pathology of diabetic nephropathy by P. Stephen et al., and the role of ERK/MAPK and TGF-beta/Smad signaling pathways in the kidney fibrosis of diabetic mice by X. Cheng et al. contributed novel information in the pathogenesis of diabetic nephropathy, a major and common complications of diabetes mellitus. Finally, an exceptional paper has been contributed by E. Hillhouse et al. on the effect of nearby construction on the progress to overt autoimmune diabetes in NOD mice. As a whole, papers from almost every aspects of the animals models of diabetes and its associated complications have been published in this special issue so it can be a special interest of diabetes researchers particularly those who are working in the different areas of diabetic complications. Md. Shahidul Islam Daisuke Koya Bernard Portha

Pathogenic Role of TGF- β in Diabetic Nephropathy

About one-third of diabetic patients develop diabetic kidney disease. In renal cells, transforming growth factor- β (TGF-β) is a key regulator of extracellular matrix protein synthesis and is secreted as latent complexes. Chronic hyperglycemia in diabetic patients seems to stimulate the glomerular mesangial cells to secrete TGF- β, which is stored in the mesangial matrix and then localized to the podocyte surface. Glomerular hypertension in the diabetic kidney may upregulate angiotensin II (Ang II) in podocytes, which may activate the latent TGF- β. Activated TGF- β /Smad signaling may stimulate the podocytes to overproduce α3(IV) collagen, leading to glomerular basement membrane (GBM) thickening. Furthermore, TGF-β-induced connective tissue growth factor (CTGF) and vascular endothelial growth factor (VEGF) may stimulate mesangial cells to overproduce matrix, culminating in diabetic glomerulo sclerosis. TGF-β- induced podocyte loss may also contribute to the development of glomerulosclerosis. Together, this review provides new mechanistic insights into the renal activation of TGF-s signaling and TGF-s-induced glomerular pathology in diabetic nephropathy.

Combined Effects of PPARγAgonists and Epidermal Growth Factor Receptor Inhibitors in Human Proximal Tubule Cells

We aimed to determine whether epidermal growth factor receptor (EGFR) inhibition, in addition to a peroxisome proliferator-activated receptor gamma (PPARγ) agonist, prevents high-glucose-induced proximal tubular fibrosis, inflammation, and sodium and water retention in human proximal tubule cells exposed to normal glucose; high glucose; high glucose with the PPARγ agonist pioglitazone or with the P-EGFR inhibitor, gefitinib; or high glucose with both pioglitazone and gefitinib. We have shown that high glucose increases AP-1 and NFκB binding activity, downstream phosphorylation of EGFR and Erk1/2, and fibronectin and collagen IV expression. Pioglitazone reversed these effects but upregulated NHE3 and AQP1 expression. Gefitinib inhibited high glucose induced fibronectin and collagen IV, and EGFR and Erk1/2 phosphorylation and reversed pioglitazone-induced increases in NHE3 and AQP1 expression. Our data suggests that combination of an EGFR inhibitor and a PPARγ agonist mitigates high-glucose-induced fibrosis and inflammation and reverses the upregulation of transporters and channels involved in sodium and water retention in human proximal tubule cells. Hence EGFR blockade may hold promise, not only in limiting tubulointerstitial pathology in diabetic nephropathy, but also in limiting the sodium and water retention observed in patients with diabetes and exacerbated by PPARγ agonists.

Meprins cleave the catalytic subunit of protein kinase A in a meprin isoform‐specific manner

Meprins are metalloproteases that are abundantly expressed in the brush border membrane of proximal kidney tubules and small intestines. Meprins are also expressed in podocytes, skin, and leukocytes. Meprins are redistributed to the cytosol after kidney ischemia/reperfusion, and have been implicated in the pathology of diabetic nephropathy (DN). There is increasing knowledge of in vivo kidney meprin substrates, and recently villin and actin were found to be cleaved by meprins. The objective of this study was to determine whether meprins cleave the catalytic subunit of protein kinase A (PKAcat), and whether the levels of PKAcat are changed in DN. Kidney proteins from meprin αβ double knockout (KO) mice, and purified recombinant human PKAcat were incubated with activated forms of either homomeric meprin A (α‐α) or meprin B (β‐β). The proteins were resolved by SDS‐PAGE and probed by Western blot analysis using PKAcat specific antibodies. Only the meprin B isoform cleaved PKAcat. Cytosolic levels of PKAcat were elevated in kidneys from both WT and meprin KO mice with streptozotocin‐induced type 1 diabetes. Cytosolic PKAcat leveles were higher in WT diabetic kidneys than in meprin double KO diabetic kidneys. The PKA signaling pathway plays a role in glomerular extracellular matrix (ECM) metabolism. Accumulation of ECM proteins is a hallmark of DN, and meprins could modulate the pathology of DN via cleavage of PKAcat.