Glomerular Basement Membrane Thickening Research Articles

Donor-related diabetic nephropathy: a comprehensive clinicopathological study

Knowledge on renal involvement in kidney donors with diabetes, that is, diabetic nephropathy (DN), is limited. During the 7 years (2010-2017), 921 postperfusion biopsies were performed for living donors (14%) or deceased donors (86%). The Renal Pathology Society classification schema for DN (class 0-IV) was used. Biopsies with light microscopic changes of DN (at least class IIa) were selected for study. Eleven biopsies (1.2%) showed DN, all from deceased donors (class IIa in 8, class IIb in 2, and class III in 1 biopsy). The glomerular basement membrane thickness ranged from 439 ± 52 to 725 ± 82 nm. These biopsies also displayed arterionephrosclerosis. They were from 9 deceased donors (fulfilling clinical criteria for acceptance in all, diabetes ;[>6 years] in 8, hypertension in 6, and proteinuria [1+] in all). Follow-up biopsies (5-342 weeks after transplant) showed DN of the same class (7 biopsies), probably progression (1), or progression (3). At follow-up (15-416 weeks), all recipients were alive. One graft was lost at 76 weeks because of progressive DN. The other 10 grafts were functioning, but the serum creatinine reached 2.0 to 2.7 mg/dL in 5 of them. Although diabetes is frequent in kidney donors, donor-related DN is unusual. It is observed only in deceased donors, but the risk factors for its development are not known. Donor-related DN may be stable or progress. Whether it resolves, especially for DN in early phase, remains unknown. It may adversely impact the graft outcome with a magnitude proportional to the severity of the tissue injury in the postperfusion biopsies.

Codonopsis tangshen Oliv. Amelioration Effect on Diabetic Kidney Disease Rats Induced by High Fat Diet Feeding Combined with Streptozotocin

Diabetic kidney disease (DKD) is the most serious microvascular complication during the development of diabetes with the characterizations of glomerular basement membrane thickening, mesangial expansion, and glomerular sclerosis, eventually leading to end-stage renal disease. This study aimed to investigate the melioration effect of Codonopisis tangshen Oliv. (COD) on the DKD model, which was established by unilateral nephrectomy (UN)-high fat diet feeding (HFD) combined with streptozotocin (STZ). After the DKD rats were oral treated with COD at a dose of 2.7 mg/kg for 4 consecutive weeks, the blood glucose, lipid metabolism, renal function, inflammatory mediators, and fibrosis-associated proteins were examined. In vivo, the COD administration obviously relieved the weight loss, water intake, and blood glucose; decreased the total cholesterol, triglyceride, and low-density lipoprotein cholesterol levels; and improved the renal function by reducing the expression of serum creatinine, uric acid, and urinary protein compared with the model group. The levels of pro-inflammatory cytokines of tumor necrosis factor-α, interleukin-1β, and IL-6 were significantly inhibited by COD. Meanwhile, the deposition of collagen fiber was markedly increased, and the protein and mRNA expressions of transforming growth factor-β1 and α-smooth muscle actin were markedly elevated in DKD rats, but they were decreased to some extent after the COD treatment. In conclusion, COD exhibited a protective effect on the UN-HFD feeding combined with STZ-induced DKD model by improving the blood glucose and lipid metabolism, relieving the inflammatory response, and mitigating the renal fibrosis, which provided scientific evidence for its applications in clinic.Graphical

ERp44 depletion exacerbates ER stress and aggravates diabetic nephropathy in db/db mice

Diabetic nephropathy (DN) is a major complication of diabetes, and the dysfunction of endoplasmic reticulum (ER) plays an important role in its pathogenesis. ERp44, an ER resident chaperone protein, has been implicated in the modulation of ER stress, however, its role and mechanism in DN are not determined. Here, we show that ERp44 expression is upregulated in the glomeruli of db/db mice, a rodent model of type 2 diabetes. When ERp44 is depleted by in vivo shRNA-mediated knockdown, the features associated with DN including albuminuria level and glomerular basement membrane (GBM) thickness are aggravated, therefore suggesting a detrimental role of ERp44 depletion in DN progression. We further show that ERp44 depletion exacerbates ER stress in DN in db/db mice, and that attenuating ER stress with the chemical chaperone TUDCA remarkably diminishes the aggravated DN features caused by ERp44 depletion. These results suggest that the exacerbated ER stress is a critical factor for the detrimental effect of ERp44 depletion on DN progression in db/db mice. Thus, our study links the role of ERp44 in DN with ER stress regulation and may offer a potential therapeutic strategy to interfere DN progression.

Amelioration of Diabetic Nephropathy Using a Retinoic Acid Receptorβ2 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.

In glomerular cells of puromycin aminonucleoside nephrosis rats both phosphorylated and total STAT3 levels increased during proteinuria

Recent studies showed that JAK/STAT pathway plays role in glomerular damages. The fact that STAT3 could be activated also by oxidative stress make Puromycin Aminonucleoside (PAN) Nephrosis model very appropriate for examination of STAT3 expression changes in glomerular pathology. Along with a control group, three PAN groups sacrificed on different days were formed by the i.p. injection of PAN for 5 consecutive days. Throughout the experiment, 24-hour-urines were collected on specific days and proteinuria levels were monitored. At the end of the experiments, tissue specimens were stained immunohistochemically for both total and phosphorylated STAT3 and evaluated subjectively. They were also examined ultrastructurally in transmission electron microscope. The proteinuria levels did not increase significantly on 5th day but showed a dramatic increase on 10th and 15th days. On 20th and 25th days, urinary protein levels gradually decreased. Ultrastructural examinations showed glomerular damages such as significant decrease in slit pore number, a significant gradual increase in glomerular basement membrane thickness and podocyte hypertrophy on 5th and 15th days; besides significant increase in mesangial matrix. The first significant increases in phosphorylated and total STAT3 levels occurred in 5th day and 15th day groups respectively. These increases diminished in 25th day group. Regarding all the findings, it was deduced that STAT3 is one of the active factors in glomerular pathologies.

Combining SGLT2 Inhibition With a Thiazolidinedione Additively Attenuate the Very Early Phase of Diabetic Nephropathy Progression in Type 2 Diabetes Mellitus.

Although both sodium glucose co-transporter 2 inhibition by dapagliflozin and thiazolidinedione, pioglitazone have glucose-lowering and anti-inflammatory effects, the therapeutic efficacy of their combination on diabetic nephropathy has not been investigated. 9-week-old male db/db mice were randomly assigned to 4 groups and administrated with (1) vehicle, (2) dapagliflozin, (3) pioglitazone, or (4) dapagliflozin and pioglitazone combination. Human proximal tubule (HK-2) cells were treated with glucose or palmitate acid in the presence of medium, dapagliflozin, pioglitazone, or both. Glomerular tuft area and mesangial expansion of the kidney more reduced in the combination group compared to control and single therapy groups. Podocyte foot process width and glomerular basement membrane thickness decreased regardless of treatment, while the combination group showed the slowest renal hypertrophy progression (P < 0.05). The combination treatment decreased MCP-1, type I and IV collagen expression in the renal cortex. Only the combination treatment decreased the expression of angiotensinogen, IL-6, and TGF-β while it enhanced HK-2 cell survival (all P < 0.05). In conclusion, dapagliflozin and pioglitazone preserved renal function, and combination therapy showed the greatest benefit. These findings suggest that the combination therapy of dapagliflozin with pioglitazone is more effective than the single therapy for preventing the progression of nephropathy in patients with type 2 diabetes.

Luseogliflozin Inhibits HIF-1α Expression in Renal Proximal Tubular Epithelial Cells

Recent clinical trials have demonstrated the renoprotective effects of SGLT2 inhibitors in diabetic nephropathy (DN). However, the mechanisms of SGLT2 inhibitors on prevention of DN have not been fully elucidated. Hypoxia-induced tubulointerstitial fibrosis is considered to be a common pathway for various progressive kidney diseases including DN. Hypoxia inducible factor (HIF)-1α plays an important role in these pathological processes. In this study, we assessed the effects of luseogliflozin, an SGLT2 inhibitor, on HIF-1α expression in both cultured human renal proximal tubular epithelial cells (HRPTECs) and kidney of diabetic mice. Hypoxia (1%O2 for 24h) markedly increased HIF-1α protein in HRPTEC, whereas luseogliflozin inhibited expression of hypoxia-induced HIF-1α protein. In addition, luseogliflozin inhibited mRNA expression for HIF-1α-targeted genes, PAI-1, VEGF and GLUT-1 under hypoxia. The inhibitors of mitochondrial respiratory complex I, rotenone or complex III, antimycin A equally suppressed hypoxia-induced HIF-1α expression. We next treated db/db mice with 15 mg/kg/day luseogliflozin for 8 weeks. Luseogliflozin administration lowered plasma glucose levels and decreased glomerular mesangial matrix expansion as well as glomerular and interstitial fibronectin accumulation in db/db mice. Electron microscopic study revealed that luseogliflozin attenuated the thickening of glomerular basement membrane in db/db mice. Intriguingly, luseogliflozin decreased the length of mitochondria in the renal proximal tubules of the S1 segment. Furthermore, luseogliflozin attenuated diabetes-induced HIF-1α accumulation in the kidney of db/db mice. These results suggest that luseogliflozin inhibits hypoxia-induced HIF-1α accumulation at least partly by suppressing mitochondrial respiration. SGLT2 inhibitors may protect diabetic kidney from hypoxia-induced renal fibrosis by attenuating the expression of HIF-1α and profibrotic molecules. Disclosure R. Bessho: None. Y. Takiyama: None. T. Ota: None.

A Low-Protein Calorie-Restricted Diet Attenuates Renal Injury and Facilitates Podocyte Autophagy in Type 2 Diabetic Rats

Purpose: Caloric restrictionhas been shown to exert a renoprotective effect in diabetic rats. Dietary protein restriction slows the progression of nephropathy in diabetic patients.We explored whether a low-protein calorie-restricted (LPCR) diet reduces renal injury and whether the renoprotective effect of LPCR diet isrelated to the activation of podocyte autophagy. Methods: The type 2 diabeticrat model was induced by a combination of high fat diet and low dose streptozotocin injection. The diabetic rats were randomly divided into 3 groups, normal protein (NP, 20% protein) group, low protein(LP, 8% protein) group and LPCR (8% protein, 30% restriction)group. Nondiabetic rats were used as normal control (NC). After 4 weeks of dietary intervention, urine albumin-to-creatinine ratio,creatinine clearance, serum creatinine, and kidney-to-body weight ratio, renal histologies, podocyte density, autophagy activity in glomeruli as well as glomerular basement membrane thickness and autophagic vacuoles in podocytesunder electron microscopy were estimated. Results: TheLPCR-diettreated diabetic ratsexhibited reduced body weight, serum triglycerides, and fasting blood glucose levels, as well as improved insulin resistance comparedwith NP-diettreated diabetic rats. LPCR diet attenuated renal injury, includingpodocyte injury, in type 2 diabetic rats. The reduced number of autophagic vacuolesin podocytesand insufficient podocyte autophagyin type 2 diabetic rats were reversed by LPCR diet. Conclusions: The findings suggest that a LPCR diet can ameliorate renal injury in type 2 diabetic rats, which maybe linked to the activation of podocyte autophagy. Disclosure G. Chen: None. Y. Geng: None. C. Liu: None.

Aliskiren inhibits renin-mediated complement activation

Certain kidney diseases are associated with complement activation although a renal triggering factor has not been identified. Here we demonstrated that renin, a kidney-specific enzyme, cleaves C3 into C3b and C3a, in a manner identical to the C3 convertase. Cleavage was specifically blocked by the renin inhibitor aliskiren. Renin-mediated C3 cleavage and its inhibition by aliskiren also occurred in serum. Generation of C3 cleavage products was demonstrated by immunoblotting, detecting the cleavage product C3b, by N-terminal sequencing of the cleavage product, and by ELISA for C3a release. Functional assays showed mast cell chemotaxis towards the cleavage product C3a and release of factor Ba when the cleavage product C3b was combined with factor B and factor D. The renin-mediated C3 cleavage product bound to factor B. In the presence of aliskiren this did not occur, and less C3 deposited on renin-producing cells. The effect of aliskiren was studied in three patients with dense deposit disease and this demonstrated decreased systemic and renal complement activation (increased C3, decreased C3a and C5a, decreased renal C3 and C5b-9 deposition and/or decreased glomerular basement membrane thickness) over a follow-up period of four to seven years. Thus, renin can trigger complement activation, an effect inhibited by aliskiren. Since renin concentrations are higher in renal tissue than systemically, this may explain the renal propensity of complement-mediated disease in the presence of complement mutations or auto-antibodies.

Inhibition of Akt/mTOR/p70S6K Signaling Activity With Huangkui Capsule Alleviates the Early Glomerular Pathological Changes in Diabetic Nephropathy.

Huangkui capsule (HKC), a Chinese modern patent medicine extracted from Abelmoschus manihot (L.) medic, has been widely applied to clinical therapy in the early diabetic nephropathy (DN) patients. However, it remains elusive whether HKC can ameliorate the inchoate glomerular injuries in hyperglycemia. Recently the activation of phosphatidylinositol-3-kinase (PI3K)/serine-threonine kinase (Akt)/mammalian target of rapamycin (mTOR) signaling and its downstream regulator, 70-kDa ribosomal protein S6 kinase (p70S6K), play important roles in the early glomerular pathological changes of DN including glomerular hypertrophy, glomerular basement membrane (GBM) thickening and mild mesangial expansion. This study thereby aimed to clarify therapeutic effects of HKC during the initial phase of DN and its underlying mechanisms. Fifteen rats were randomly divided into 3 groups: the normal group, the model group and the HKC group. The early DN model rats were induced by unilateral nephrectomy combined with intraperitoneal injection of streptozotocin, and administered with either HKC suspension or vehicle after modeling and for a period of 4 weeks. Changes in the incipient glomerular lesions-related parameters in urine and blood were analyzed. Kidneys were isolated for histomorphometry, immunohistochemistry, immunofluorescence and Western blotting (WB) at sacrifice. In vitro, murine mesangial cells (MCs) were used to investigate inhibitory actions of hyperoside (HYP), a bioactive component of HKC, on cellular hypertrophy-associated signaling pathway by WB, compared with rapamycin (RAP). For the early DN model rats, HKC ameliorated micro-urinary albumin, body weight and serum albumin, but had no significant effects on renal function and liver enzymes; HKC improved renal shape, kidney weight and kidney hypertrophy index; HKC attenuated glomerular hypertrophy, GBM thickening and mild mesangial expansion; HKC inhibited the phosphorylation of Akt, mTOR and p70S6K, and the protein over-expression of transforming growth factor-β1 in kidneys. In vitro, the phosphorylation of PI3K, Akt, mTOR and p70S6K in MCs induced by high-glucose was abrogated by treatment of HYP or RAP. On the whole, this study further demonstrated HKC safely and efficiently alleviates the early glomerular pathological changes of DN, likely by inhibiting Akt/mTOR/p70S6K signaling activity in vivo and in vitro, and provided the first evidence that HKC directly contributes to the prevention of the early DN.

Coumarins improved type 2 diabetes induced by high-fat diet and streptozotocin in mice via antioxidation.

Coumarins extensively exist in plants and are utilized against diabetes in some folk medicines. Recent studies have demonstrated that oxidative stress plays a crucial role in the etiology and pathogenesis of diabetes mellitus. We investigated the antioxidant ability of 3 coumarins (osthole, esculin, and fraxetin) in type 2 diabetes. After being fed a high-fat diet, ICR mice were exposed to low doses of streptozotocin and then treated with experimental coumarins for 5 weeks. We found osthole, esculin, and metformin significantly lowered fasting blood glucose, HOMA-IR, and 3 blood lipids (total cholesterol, total triglyceride, free fatty acids), and increased insulin levels, while fraxetin only enhanced insulin levels and lessened free fatty acids. Both osthole and esculin had antioxidative effects in pancreas through elevating the activities of glutathione peroxidase, catalase, and superoxide dismutase; fraxetin, however, merely heightened catalase activity. By contrast, 3 coumarins significantly increased those antioxidase activities in liver. Hematoxylin and eosin staining revealed 3 coumarins, especially osthole, attenuated cellular derangement, blurry fringes of hepatic sinusoid and extensive vacuolization due to hepatocellular lipid accumulation, and lessened inflammatory infiltration in pancreas. The glomerular and islet structure of diabetic mice were improved, with reduced mesangial matrix and glomerular basement membrane thickening. Therefore, our study supports that coumarins could be promising candidates against type 2 diabetes through antioxidative mechanisms.

Effect of Pinocembrin Isolated from Mexican Brown Propolis on Diabetic Nephropathy.

Propolis is a resinous beehive product that has been used worldwide in traditional medicine to prevent and treat colds, wounds, rheumatism, heart disease and diabetes. Diabetic nephropathy is the final stage of renal complications caused by diabetes and for its treatment there are few alternatives. The present study aimed to determine the chemical composition of three propolis samples collected in Chihuahua, Durango and Zacatecas and to evaluate the effect of pinocembrin in a model of diabetic nephropathy in vivo. Previous research demonstrated that propolis of Chihuahua possesses hypoglycemic and antioxidant activities. Two different schemes were assessed, preventive (before renal damage) and corrective (once renal damage is established). In the preventive scheme, pinocembrin treatment avoids death of the rats, improves lipid profile, glomerular filtration rate, urinary protein, avoid increases in urinary biomarkers, oxidative stress and glomerular basement membrane thickness. Whereas, in the corrective scheme, pinocembrin only improves lipid profile without showing improvement in any other parameters, even pinocembrin exacerbated the damage. In conclusion, pinocembrin ameliorates diabetic nephropathy when there is no kidney damage but when it is already present, pinocembrin accelerates kidney damage.

The relationship between the thickness of glomerular basement membrane and renal outcomes in patients with diabetic nephropathy

Glomerular basement membrane (GBM) thickening is considered as one of the earliest detectable pathological features of diabetic nephropathy (DN). However, whether the thickness of GBM will impact the prognosis of DN remains largely unknown. Our aim was to explore the relationship between thickness of GBM and DN progression in patients with type 2 diabetes mellitus (T2DM). A total of 118 patients with T2DM and biopsy-proven DN who received follow-up for at least 1year were recruited. The patients were divided into two groups according to the median (787nm) of the GBM thickness: Group 1: GBM thickness < 787nm (n = 59), and Group 2: GBM thickness ≥ 787nm (n = 59). The GBM width was estimated by the direct GBM measurements as recently modified by Haas. Renal outcomes were defined by progression to ESRD and/or doubling of serum creatinine (D-Cr). The influence of GBM thickness on renal outcomes was assessed using Cox regression. Compared with the Group 1, patients in Group 2 had more serious renal insufficiency and glomerular lesions. During the follow-up, ESRD occurred in 39.8% of patients, and 8.5% of patients progressed to D-Cr. The univariate analysis indicated the greater width of GBM the higher risk of renal outcomes in T2DM patients with DN (HR [95% CI] = 2.180 [1.246-3.814], p = 0.006). However, the multivariate COX analysis demonstrated that the GBM thickness was not an independent risk factor for progression to ESRD or D-Cr (HR [95% CI] = 0.825 [0.404-1.685], p = 0.597) when adjusting for important clinical variables and pathological findings. In conclusion, the DN patients with greater width of GBM had relatively poorer renal prognosis, although it did not emerge as an independent indicator of disease progression.

Silencing of CXCL12 performs a protective effect on C5b-9-induced injury in podocytes.

Podocytes, terminal differentiation cell in glomerulu, are crucial to kidney-related diseases such as membranous nephropathy (MN). MN is characterized by podocyte injury and glomerular basement membrane thickening. This paper focused to investigate the expression of chemokine (C-X-C motif) ligand 12 (CXCL12) in MN patients and its possible role in podocyte injury. Through the enzyme-linked immunosorbent assay, CXCL12 level in the serum and urine of MN patients was examined. Further, several assays of cell viability, apoptosis, quantitative real-time PCR and western blot were applied to explore the effects of CXCL12 in the model of podocyte injury. We found a significant increase of CXCL12 in serum and urine of MN patients, which indicated that CXCL12 may be involved in the progression of MN. And in vitro C5b-9-induced podocyte injury model, the proliferation of podocytes was inhibited whereas CXCL12/CXCR4 and phosphorylated STAT3 (p-STAT3) were increased. Silencing of CXCL12 remarkably promoted cell proliferation, inhibited cell apoptosis and suppressed CXCL12/CXCR4, p-STAT3 and caspase 3. Consistently, STAT3 inhibitor and berberine (a CXCL12 antagonist) also reduced CXCL12 treatment-induced apoptosis. All data suggested that silencing of CXCL12 had a protective effect on podocyte injury, which may be through inhibiting CXCL12/STAT3 signaling pathway.

New Glucose-Lowering Agents for Diabetic Kidney Disease.

The prevalence of diabetes mellitus is increasing and is associated with a range of complications including nephropathy. New antidiabetic agents are sought which also have positive effects to diminish diabetic complications. Examples of promising new classes of such agents are glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, and sodium-glucose cotransporter 2 inhibitors. In addition to cardiovascular protective effects such as weight loss and decreased blood pressure of some of these agents, there is evidence for renoprotective effects with these agents. This review elaborates on the main results of renoprotective effects of these 3 treatment classes. In conclusion, currently available trials have demonstrated renoprotective effects for certain glucagon-like peptide-1 receptor agonists, liraglutide and semaglutide, and the sodium-glucose cotransporter 2 inhibitors, empagliflozin and canagliflozin. Dipeptidyl peptidase-4 inhibitors did not show a significant renoprotective effect. Nevertheless, larger studies with respect to renoprotective effects of these 3 drug classes are currently being performed, and thus, no conclusions for all of these agents can yet be made.

Acute Kidney Injury and Progression of Diabetic Kidney Disease.

Diabetic kidney disease, commonly termed diabetic nephropathy (DN), is the most common cause of end-stage kidney disease (ESKD) worldwide. The characteristic histopathology of DN includes glomerular basement membrane thickening, mesangial expansion, nodular glomerular sclerosis, and tubulointerstitial fibrosis. Diabetes is associated with a number of metabolic derangements, such as reactive oxygen species overproduction, hypoxic state, mitochondrial dysfunction, and inflammation. In the past few decades, our knowledge of DN has advanced considerably although much needs to be learned. The traditional paradigm of glomerulus-centered pathophysiology has expanded to the tubule-interstitium, the immune response and inflammation. Biomarkers of proximal tubule injury have been shown to correlate with DN progression, independent of traditional glomerular injury biomarkers such as albuminuria. In this review, we summarize mechanisms of increased susceptibility to acute kidney injury in diabetes mellitus and the roles played by many kidney cell types to facilitate maladaptive responses leading to chronic and end-stage kidney disease.

A new model of diabetic nephropathy in C57BL/6 mice challenged with advanced oxidation protein products.

There remains a lack of robust mouse models with key features of advanced human diabetic nephropathy (DN). Few options of murine models of DN require mutations to be superimposed to obtain desired phenotypic characteristics. Most genetically modified mice are on the C57BL/6 background; however, they are notorious for resistance to develop DN. To overcome these conundrums, this study reports a novel DN model by challenging with advanced oxidation protein products (AOPPs) in streptozotocin-induced diabetic C57BL/6 mice. AOPPs-challenged diabetic C57BL/6 mice were more sensitive to develop progressive proteinuria, causing a 5.59-fold increase in urine albumin to creatinine ratio as compared to diabetic controls by 24 weeks. Typical lesions were present as demonstrated by significant diffuse mesangial expansion, diffuse podocyte foot process effacement, increased glomerular basement membrane thickness, focal arteriolar hyalinosis, mesangiolysis, and mild interstitial fibrosis. These changes were alleviated by losartan treatment. Collectively, these results suggest that AOPPs can accelerate the progression of DN in the resistant C57BL/6 mouse strain. Our studies offer a novel model for studying the pathogenesis of DN that resembles human diabetic kidney disease. It also makes it possible to interrogate the role of specific genetic modifications and to evaluate novel therapeutics to treat DN in preclinical setting.

Taxus chinensis ameliorates diabetic nephropathy through down-regulating TGF-β1/Smad pathway

Diabetic nephropathy (DN) is one of the common microvascular complications of diabetes mellitus. Renal fibrosis is closely related to the deterioration of renal function. The present study aimed to investigate protective effect of Taxus chinensis on high-fat diet/streptozotocin-induced DN in rats and explore the underlying mechanism of action. The rat DN model was established via feeding high fat diet for 4 weeks and subsequently injecting streptozotocin (30 mg·kg−1 body weight) intraperitoneally. The rats with blood glucose levels higher than 16.8 mmol·L−1 were selected for experiments. The DN rats were treated with Taxus chinensis orally (0.32, 0.64, and 1.28 g·kg−1) once a day for 8 weeks. Taxus chinensis significantly improved the renal damage, which was indicated by the decreases in 24-h urinary albumin excretion rate, blood serum creatinine, and blood urea nitrogen. Histopathological examination confirmed the protective effect of Taxus chinensis. The thickness of glomerular basement membrane was reduced, and proliferation of mesangial cells and podocytes cells and increase in mesangial matrix were attenuated. Further experiments showed that Taxus chinensis treatment down-regulated the expression of TGF-β1 and α-SMA, inhibited phosphorylation of Smad2 and Smad3. These results demonstrated that Taxus chinensis alleviated renal injuries in DN rats, which may be associated with suppressing TGF-β1/Smad signaling pathway.

Liraglutide ameliorates early renal injury by the activation of renal FoxO1 in a type 2 diabetic kidney disease rat model

AimsThe aim of this study was to investigate the effects of liraglutide on renal injury and the renal expression of FoxO1 in type 2 diabetic rats. MethodsType 2 diabetic rats model was induced by a high-sugar and high-fat diet and intraperitoneal injection of low-dose Streptozotocin (STZ) (30 mg/kg). Five weeks after STZ injection, diabetic rats were randomly treated with or without subcutaneous injection of liraglutide (0.2 mg/kg/12 h) for eight weeks. Diabetes-related physical and biochemical indicators, renal histopathological and ultrastructural changes, the expression of renal transforming growth factor beta-1 (TGF-β1), fibronectin (FN), type IV collagen (Col IV), protein kinase B (Akt), forkhead box protein O1 (FoxO1) and manganese superoxide dismutase (MnSOD) were measured. ResultsRats in DN group showed a significant increase in fasting blood glucose, HbA1c, kidney to body weight index, serum creatinine (Scr), blood urea nitrogen (BUN), urinary albumin excretion, mesangial matrix index, glomerular basement membrane (GBM) thickening, podocyte foot process fusion, the mRNA and protein levels of renal TGF-β1, FN and Col IV and a dramatic decrease in the mRNA and protein levels of renal MnSOD, all of which were significantly ameliorated by liraglutide. In addition, liraglutide also increased the expression of FoxO1 mRNA and reduced renal phosphorylation levels of Akt and FoxO1 protein. ConclusionsThese results suggest that liraglutide may exert a renoprotective effect by a FoxO1-mediated upregulation of renal MnSOD expression in the early DKD.

Quercetin ameliorates podocyte injury via inhibition of oxidative stress and the TGF-β1/Smad pathway in DN rats.

An increasing number of investigations have revealed that podocytes play a crucial role in the development and progression of diabetic nephropathy (DN). Quercetin (2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-4H-chromen-4-one) is the most common flavonol in the diet and is one of the most prominent dietary antioxidants, which might have a protective effect on DN. The present study was designed to investigate the protective effect of quercetin on podocyte impairment in a rat model of DN, as well as underlying molecular mechanisms. All diabetic rats were induced by a single intraperitoneal injection of streptozotocin, and quercetin was administered daily at a dose of 50 mg kg−1 or 100 mg kg−1 for 12 weeks. In the present study, quercetin markedly decreased blood glucose levels, kidney-to-body weight ratio, albuminuria, creatinine clearance rate, blood urea nitrogen, and triglycerides and significantly attenuated oxidative stress. Moreover, quercetin was observed to inhibit podocyte effacement and decrease the thickness of glomerular basement membranes. Mechanistically, quercetin significantly increased the expression of podocyte-specific markers nephrin and podocin and decreased expression of the podocyte injury marker desmin in DN rats. Quercetin also inhibited activation of the TGF-β1/Smad signaling pathway in DN rats by decreasing expression of TGF-β1, p-Smad2, and p-Smad3, and increasing Smad7 expression. These findings suggest that quercetin administration ameliorated podocyte injury in DN rats, possibly by inhibiting oxidative stress and the TGF-β1/Smad signaling pathway. Thus, quercetin may be manipulated to act as a potential drug for prevention of early diabetic nephropathy.