Valsartan slows the progression of diabetic nephropathy in db/db mice via a reduction in podocyte injury, and renal oxidative stress and inflammation

RNA-binding protein HuR regulates the transition of septic AKI to CKD by modulating CD147

Septic acute kidney injury (AKI) is an important risk factor for developing chronic kidney disease (CKD). Hu antigen R (HuR) is recognized as a crucial modulator in inflammation. We hypothesized that elevated HuR contributes to the transition from septic AKI to CKD by promoting persistent inflammation and fibrosis, and inhibition of HuR may reverse septic kidney injury. Mice subjected to lipopolysaccharide (LPS) injections every other day were concurrently treated without or with either KH39 or niclosamide (NCS) for 7 days. Control mice received saline injections. Repeated LPS injections led to a significant increase in HuR expression in the kidneys, which was effectively suppressed by KH39 or NCS treatment. LPS-induced kidney injury was characterized by elevated plasma blood urea nitrogen levels and urinary albuminuria, along with histological signs of inflammatory cell infiltration and fibrosis, as determined by periodic acid-Schiff and Masson's trichrome staining, and immunofluorescent staining for markers such as α-smooth muscle actin, fibronectin, collagen III, and F4/80. Treatment with either KH39 or NCS mitigated these changes observed in LPS-injured kidneys. Additionally, increased expression of CD147, a molecule implicated in inflammatory cell recruitment and tubular injury, was inhibited by KH39 or NCS treatment. These effects on HuR and CD147 expression were further validated in vitro in cultured macrophages and tubular cells. This study suggests that HuR elevation in LPS-stimulated macrophages and kidney cells contributes to the progression of septic kidney injury, possibly through HuR-CD147 interactions, underscoring the therapeutic potential of HuR inhibitors for this condition.

Repurposing Niclosamide to Modulate Renal RNA-Binding Protein HuR for the Treatment of Diabetic Nephropathy in db/db Mice

Hu antigen R (HuR) plays a key role in regulating genes critical to the pathogenesis of diabetic nephropathy (DN). This study investigates the therapeutic potential of niclosamide (NCS) as an HuR inhibitor in DN. Uninephrectomized mice were assigned to four groups: normal control; untreated db/db mice terminated at 14 and 22 weeks, respectively; and db/db mice treated with NCS (20 mg/kg daily via i.p.) from weeks 18 to 22. Increased HuR expression was observed in diabetic kidneys from db/db mice, which was mitigated by NCS treatment. Untreated db/db mice exhibited obesity, progressive hyperglycemia, albuminuria, kidney hypertrophy and glomerular mesangial matrix expansion, increased renal production of fibronectin and a-smooth muscle actin, and decreased glomerular WT-1+-podocytes and nephrin expression. NCS treatment did not affect mouse body weight, but reduced blood glucose and HbA1c levels and halted the DN progression observed in untreated db/db mice. Renal production of inflammatory and oxidative stress markers (NF-κBp65, TNF-a, MCP-1) and urine MDA levels increased during disease progression in db/db mice but were halted by NCS treatment. Additionally, the Wnt1-signaling-pathway downstream factor, Wisp1, was identified as a key downstream mediator of HuR-dependent action and found to be markedly increased in db/db mouse kidneys, which was normalized by NCS treatment. These findings suggest that inhibition of HuR with NCS is therapeutic for DN by improving hyperglycemia, renal inflammation, and oxidative stress. The reduction in renal Wisp1 expression also contributes to its renoprotective effects. This study supports the potential of repurposing HuR inhibitors as a novel therapy for DN.

Unveiling Wide Spectrum Therapeutic Implications and Signaling Mechanisms of Valsartan in Diverse Disorders: A Comprehensive Review

Valsartan is an orally active non-peptide angiotensin receptor antagonist, an effective and well-tolerated anti-hypertensive drug. Besides its antihypertensive action, it has clinical implications in many other disorders, like heart failure (HF), arrhythmia, chronic kidney disease (CKD), diabetic complications (DM), atherosclerosis, etc. Besides angiotensin receptor blocking activity, valsartan reduces circulating levels of biochemical markers, such as hs-CRP, which is responsible for its anti-inflammatory and anti-oxidant activity. Moreover, valsartan also acts by inhibiting or inducing various signalling pathways, such as inducing autophagy via the AKT/mTOR/S6K pathway or inhibiting the TLR/NF-kB pathway. The current review exhaustively discusses the therapeutic implications of valsartan with specific emphasis on the mechanism of action in various disorders. The article provides a detailed spectrum of the therapeutic profile of valsartan and will likely be very useful to researchers working in the relevant research areas.

Targeting RNA-binding protein HuR to inhibit the progression of renal tubular fibrosis

BACKGROUND

Upregulation of an RNA-binding protein HuR has been implicated in glomerular diseases. Herein, we evaluated whether it is involved in renal tubular fibrosis.

METHODS

HuR was firstly examined in human kidney biopsy tissue with tubular disease. Second, its expression and the effect of HuR inhibition with KH3 on tubular injury were further assessed in a mouse model induced by a unilateral renal ischemia/reperfusion (IR). KH3 (50 mg kg-1) was given daily via intraperitoneal injection from day 3 to 14 after IR. Last, one of HuR-targeted pathways was examined in cultured proximal tubular cells.

RESULTS

HuR significantly increases at the site of tubular injury both in progressive CKD in patients and in IR-injured kidneys in mice, accompanied by upregulation of HuR targets that are involved in inflammation, profibrotic cytokines, oxidative stress, proliferation, apoptosis, tubular EMT process, matrix remodeling and fibrosis in renal tubulointerstitial fibrosis. KH3 treatment reduces the IR-induced tubular injury and fibrosis, accompanied by the remarkable amelioration in those involved pathways. A panel of mRNA array further revealed that 519 molecules in mouse kidney following IR injury changed their expression and 71.3% of them that are involved in 50 profibrotic pathways, were ameliorated when treated with KH3. In vitro, TGFβ1 induced tubular HuR cytoplasmic translocation and subsequent tubular EMT, which were abrogated by KH3 administration in cultured HK-2 cells.

CONCLUSIONS

These results suggest that excessive upregulation of HuR contributes to renal tubulointerstitial fibrosis by dysregulating genes involved in multiple profibrotic pathways and activating the TGFß1/HuR feedback circuit in tubular cells. Inhibition of HuR may have therapeutic potential for renal tubular fibrosis.

Macrophage inflammatory protein-1β as a novel therapeutic target for renal protection in diabetic kidney disease

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease worldwide and the prevalence of DKD has increased over recent decades. Inflammation is involved in the development and progression of DKD. In this study, we explored the potential role of macrophage inflammatory protein-1β (MIP-1β) in DKD. Clinical non-diabetic subjects and DKD patients with different levels of urine albumin-to-creatinine ratio (ACR) were enrolled in the study. Lepr^db/^db mice and MIP-1β knockout mice were also used as mouse models for DKD. We found that serum MIP-1β levels were elevated in the DKD patients, especially those with ACRs that were less than or equal to 300, suggesting that MIP-1β is activated in clinical DKD. The administration of anti-MIP-1β antibodies attenuated DKD severity in the Lepr^db/^db mice, which also showed reduced glomerular hypertrophy and podocyte injury, as well as decreased inflammation and fibrosis, suggesting that MIP-1β plays a role in the development of DKD. The MIP-1β knockout mice showed improved renal function and decreased renal glomerulosclerosis and fibrosis in DKD. Furthermore, podocytes from the MIP-1β knockout mice showed less high glucose-induced inflammation and fibrosis compared to those from wild-type mice. In conclusion, the inhibition or deletion of MIP-1β protected podocytes, modulated renal inflammation, and ameliorated experimental DKD, suggesting that novel anti-MIP-1β strategies could potentially be used to treat DKD.

Engineered Bone Marrow Stem Cell-Sheets Alleviate Renal Damage in a Rat Chronic Glomerulonephritis Model

Although mesenchymal stem cell (MSC)-based regenerative therapy is being developed for the treatment of kidney diseases, cell delivery and engraftment still need to be improved. Cell sheet technology has been developed as a new cell delivery method, to recover cells as a sheet form retaining intrinsic cell adhesion proteins, which promotes its transplantation efficiency to the target tissue. We thus hypothesized that MSC sheets would therapeutically reduce kidney disease with high transplantation efficiency. When the chronic glomerulonephritis was induced by two injections of the anti-Thy 1.1 antibody (OX-7) in rats, the therapeutic efficacy of rat bone marrow stem cell (rBMSC) sheet transplantation was evaluated. The rBMSC-sheets were prepared using the temperature-responsive cell-culture surfaces and transplanted as patches onto the surface of two kidneys of each rat at 24 h after the first injection of OX-7. At 4 weeks, retention of the transplanted MSC-sheets was confirmed, and the animals with MSC-sheets showed significant reductions in proteinuria, glomerular staining for extracellular matrix protein, and renal production of TGFß1, PAI-1, collagen I, and fibronectin. The treatment also ameliorated podocyte and renal tubular injury, as evidenced by a reversal in the reductions of WT-1, podocin, and nephrin and by renal overexpression of KIM-1 and NGAL. Furthermore, the treatment enhanced gene expression of regenerative factors, and IL-10, Bcl-2, and HO-1 mRNA levels, but reduced TSP-1 levels, NF-kB, and NAPDH oxidase production in the kidney. These results strongly support our hypothesis that MSC-sheets facilitated MSC transplantation and function, and effectively retarded progressive renal fibrosis via paracrine actions on anti-cellular inflammation, oxidative stress, and apoptosis and promoted regeneration.

Angiopoietin-like protein 3 deficiency combined with valsartan administration protects better against podocyte damage in streptozotocin-induced diabetic nephropathy mice

Diabetic nephropathy (DN) is a common leading cause of end-stage renal disease (ESRD). Podocyte injury is a major pathogenesis of DN. Pharmacological inhibition of the renin-angiotensin-aldosterone system (RAAS) is insufficient to fully prevent the development of ESRD. The present investigation aims to evaluate the protective function of valsartan, an angiotensin receptor blocker, alone and in combination with angiopoietin-like protein 3 (Angptl3) knockout against renal damage and podocyte injury in streptozotocin (STZ)-induced diabetic mice. The mice were divided into four groups: normal control group, STZ-induced DN group, valsartan + DN group (val, 100 mg/kg, po), and Angptl3-/- + valsartan + DN group. Tests on kidney function, renal pathology, podocyte ultrastructure, podocyte apoptosis, reactive oxygen species (ROS) production, and autophagy were performed. The combined Angptl3 knockout/valsartan treatment significantly attenuated diabetes-induced renal pathological damage and improved podocyte ultrastructure compared with valsartan alone. The combined administration ameliorated glomerular injury by increasing nephrin, podocin, and CD2-associated protein (CD2AP) expression levels and inhibiting podocyte loss by apoptosis. Compared with valsartan alone, Angptl3-/- and valsartan combination therapy significantly improved the renal function, as demonstrated by decreasing levels of serum urea nitrogen, creatinine, and urinary albumin. Additionally, the combination treatment significantly activated autophagy and reduced the ROS production than valsartan alone. These findings highlight the role of valsartan to Angptl3 knockout could have much better outcome that opens the future for drugs that could inhibit Angptl3.

Combination of tolvaptan and valsartan improves cardiac and renal functions in doxorubicin-induced heart failure in mice

Heart failure (HF) is often complicated by renal dysfunction. Tolvaptan and valsartan are two well-known agents for the treatment of HF. However, the role of tolvaptan/valsartan combination on HF with renal dysfunction remains unclear. To establish a mice model with HF with renal dysfunction, mice were intraperitoneally injected with doxorubicin (Dox). Echocardiogram was applied to assess the left ventricular function. Additionally, serum aldosterone (ALD) and angiotensin II (Ang II) level in mice were determined by ELISA. Meanwhile, western blot assay was used to evaluate the expressions of B cell lymphoma-2 (Bcl-2), Bcl-2 associated X (Bax) and cleaved caspase 3 in the heart and kidney tissues of mice. In this study, we found that compared to tolvaptan or valsartan alone treatment group, tolvaptan/valsartan combination obviously improved the left ventricular ejection fraction (LVEF) and the left ventricular fractional shortening (LVFS), and reduced serum ALD and Ang II level in Dox-treated mice. Additionally, tolvaptan/valsartan combination significantly prevented the inflammation and fibrosis of heart and kidney tissues in Dox-treated mice. Meanwhile, tolvaptan/valsartan combination notably inhibited the myocardial and renal cell apoptosis in Dox-treated mice via upregulation of Bcl-2 and downregulation of Bax and cleaved caspase 3, compared to the single drug treatment. Collectively, tolvaptan/valsartan combination could improve cardiac and renal functions, as well as prevent the fibrosis, inflammation and apoptosis of heart and kidney tissues in Dox-treated mice. Taken together, combining tolvaptan with valsartan might be a promising approach to achieve enhanced therapeutic effect for treatment of HF with renal dysfunction.

Stimulation of Angiotensin Converting Enzyme 2: A Novel Treatment Strategy for Diabetic Nephropathy

Despite current therapies for diabetic nephropathy, many patients continue to progress to end-stage renal disease requiring renal replacement therapy. While the precise mechanisms underlying diabetic nephropathy remain to be determined, it is well established that chronic activation of the renin angiotensin aldosterone system (RAAS) plays a substantial role in the pathogenesis of diabetic nephropathy. Angiotensin converting enzyme 2 (ACE2), the enzyme responsible for activating the reno-protective arm of the RAAS converts angiotensin (Ang) II into Ang 1-7 which exerts reno-protective effects. Chronic RAAS activation leads to kidney inflammation and fibrosis, and ultimately lead to end-stage kidney disease. Currently, angiotensin converting enzyme inhibitors and Ang II receptor blockers are approved for renal fibrosis and inflammation. Targeting the reno-protective arm of the RAAS should therefore, provide further treatment options for kidney fibrosis and inflammation. In this review, we examine how targeting the reno-protective arm of the RAAS can ameliorate kidney inflammation and fibrosis and rescue kidney function in diabetic nephropathy. We argue tissue ACE2 stimulation provides a unique and promising therapeutic approach for diabetic nephropathy.

Therapeutic potential of resveratrol in diabetic nephropathy according to molecular signaling

BACKGROUND

Diabetic nephropathy (DN) as a severe complication of diabetes mellitus (DM), is a crucial menace for human health and survival and remarkably elevates the healthcare systems' costs. Therefore, it is worth noting to identify novel preventive and therapeutic strategies to alleviate the disease conditions. Resveratrol, as a well-defined anti-diabetic/ antioxidant agent has capabilities to counteract diabetic complications. It has been predicted that resveratrol will be a fantastic natural polyphenol for diabetes therapy in the next few years.

OBJECTIVE

Accordingly, the current review aims to depict the role of resveratrol in the regulation of different signaling pathways that are involved in the reactive oxygen species (ROS) production, inflammatory processes, autophagy, and mitochondrial dysfunction, as critical contributors to DN pathophysiology.

RESULTS

The pathogenesis of DN can be multifactorial; hyperglycemia is one of the prominent risk factors of DN development that is closely related to oxidative stress. Resveratrol, as a well-defined polyphenol, has various biological and medicinal properties, including anti-diabetic, anti-inflammatory, and anti-oxidative effects.

CONCLUSION

Resveratrol prevents kidney damages that are caused by oxidative stress, enhances antioxidant capacity, and attenuates the inflammatory and fibrotic responses. For this reason, resveratrol is considered an interesting target in DN research due to its therapeutic possibilities during diabetic disorders and renal protection.

Effect of the Renin-Angiotensin-Aldosterone System Reactivity on Endothelial Function and Modulative Role of Valsartan in Male Subjects with Essential Hypertension

BACKGROUND

The aim of the study was to evaluate the relationship between renin-angiotensin-aldosterone (RAA) system activity and reactivity, and the endothelial function profile in normotensive subjects (N), and in essential hypertensives (H), followed by analysis of the modulatory role of an angiotensin receptor blocker (ARB): valsartan, administered in the management of hypertension.

METHODS

A total of 101 male subjects were enrolled to the study: 31H and 70N. The nitric-oxide (NO) bioavailability (l-Arginine, asymmetric dimethylarginine (ADMA)), symmetric dimethylarginine (SDMA), endothelial vasodilative function (flow mediated dilation (FMD)), oxidative-stress markers (malonyldialdehyde (MDA), thiol index (GSH/GSSG), nitrotyrozine (N-Tyr)), and pro-inflammatory/angiogenic parameters (sICAM-1, sVCAM-1, PAI-1, sE-selectin, PAI-1, thromboxane -B2) were assessed at baseline, then after intravenous -l-arginine administration, which was repeated after the 4-day acetylsalicylic acid (ASA) administration (75 mg/24 h). In hypertensives, this whole protocol was repeated following 2 weeks of valsartan therapy.

RESULTS

No effect of valsartan and ASA on the flow-mediated vasodilation (FMD) and the NO bioavailability in hypertensives was observed. Administration of valsartan increased plasma renin activity (PRA), but without a decrease in the aldosterone levels. ASA treatment minimized the pre-existing differences between the groups, and increased the PRA in the N-subgroup with the highest ARR values. The blood concentrations of proinflammatory sICAM-1, sE-selectin, sVCAM-1, and PAI-1 were higher, whereas the anti-inflammatory 6-keto-PGF1 alpha level was lower in hypertensive subjects. The levels of angiogenic VEGF did not differ between groups.

CONCLUSIONS

Our study does not confirm the modulative effect of valsartan on endothelial function. Normotensive men showed an increase in FMD after l-arginine administration, possibly indicating baseline impairment of the NO synthesis.

Pleiotropic Properties of Valsartan: Do They Result from the Antiglycooxidant Activity? Literature Review and In Vitro Study

Valsartan belongs to angiotensin II type 1 (AT1) receptor blockers (ARB) used in cardiovascular diseases like heart failure and hypertension. Except for its AT1-antagonism, another mechanism of drug action has been suggested in recent research. One of the supposed actions refers to the positive impact on redox balance and reducing protein glycation. Our study is aimed at assessing the antiglycooxidant properties of valsartan in an in vitro model of oxidized bovine serum albumin (BSA). Glucose, fructose, ribose, glyoxal (GO), methylglyoxal (MGO), and chloramine T were used as glycation or oxidation agents. Protein oxidation products (total thiols, protein carbonyls (PC), and advanced oxidation protein products (AOPP)), glycooxidation products (tryptophan, kynurenine, N-formylkynurenine, and dityrosine), glycation products (amyloid-β structure, fructosamine, and advanced glycation end products (AGE)), and albumin antioxidant activity (total antioxidant capacity (TAC), DPPH assay, and ferric reducing antioxidant power (FRAP)) were measured in each sample. In the presence of valsartan, concentrations of protein oxidation and glycation products were significantly lower comparing to control. Moreover, albumin antioxidant activity was significantly higher in those samples. The drug's action was comparable to renowned antiglycation agents and antioxidants, e.g., aminoguanidine, metformin, Trolox, N-acetylcysteine, or alpha-lipoic acid. The conducted experiment proves that valsartan can ameliorate protein glycation and oxidation in vitro in various conditions. Available animal and clinical studies uphold this statement, but further research is needed to confirm it, as reduction of protein oxidation and glycation may prevent cardiovascular disease development.

Mechanism of Albuminuria Reduction by Chymase Inhibition in Diabetic Mice

Chymase has several functions, such as angiotensin II formation, which can promote diabetic kidney disease (DKD). In this study, we evaluated the effect of the chymase inhibitor TY-51469 on DKD in diabetic db/db mice. Diabetic mice were administered TY-51469 (10 mg/kg/day) or placebo for 4 weeks. No significant difference was observed in body weight and fasting blood glucose between TY-51469- and placebo-treated groups. However, a significant reduction in urinary albumin/creatinine ratio was observed in the TY-51469-treated group compared with the placebo-treated group. In the renal extract, chymase activity was significantly higher in placebo-treated mice than in non-diabetic db/m mice, but it was reduced by treatment with TY-51469. Both NADPH oxidase 4 expression and the oxidative stress marker malondialdehyde were significantly augmented in the placebo-treated group, but they were attenuated in the TY-51469-treated group. Significant increases of tumor necrosis factor-α and transforming growth factor-β mRNA levels in the placebo-treated group were significantly reduced by treatment with TY-51469. Furthermore, the expression of nephrin, which is a podocyte-specific protein, was significantly reduced in the placebo-treated group, but it was restored in the TY-51469-treated group. These findings demonstrated that chymase inhibition reduced albuminuria via attenuation of podocyte injury by oxidative stress.

Inhibition of RNA-binding protein HuR reduces glomerulosclerosis in experimental nephritis

Recent identification of an RNA-binding protein (HuR) that regulates mRNA turnover and translation of numerous transcripts via binding to an ARE in their 3′-UTR involved in inflammation and is abnormally elevated in varied kidney diseases offers a novel target for the treatment of renal inflammation and subsequent fibrosis. Thus, we hypothesized that treatment with a selective inhibition of HuR function with a small molecule, KH-3, would down-regulate HuR-targeted proinflammatory transcripts thereby improving glomerulosclerosis in experimental nephritis, where glomerular cellular HuR is elevated. Three experimental groups included normal and diseased rats treated with or without KH-3. Disease was induced by the monoclonal anti-Thy 1.1 antibody. KH-3 was given via daily intraperitoneal injection from day 1 after disease induction to day 5 at the dose of 50 mg/kg BW/day. At day 6, diseased animals treated with KH-3 showed significant reduction in glomerular HuR levels, proteinuria, podocyte injury determined by ameliorated podocyte loss and podocin expression, glomerular staining for periodic acid-Schiff positive extracellular matrix proteins, fibronectin and collagen IV and mRNA and protein levels of profibrotic markers, compared with untreated disease rats. KH-3 treatment also reduced disease-induced increases in renal TGFβ1 and PAI-1 transcripts. Additionally, a marked increase in renal NF-κB-p65, Nox4, and glomerular macrophage cell infiltration observed in disease control group was largely reversed by KH-3 treatment. These results strongly support our hypothesis that down-regulation of HuR function with KH-3 has therapeutic potential for reversing glomerulosclerosis by reducing abundance of pro-inflammatory transcripts and related inflammation.

Systemic AAV10.COMP-Ang1 rescues renal glomeruli and pancreatic islets in type 2 diabetic mice

INTRODUCTION

Diabetic hyperglycemia causes progressive and generalized damage to the microvasculature. In renal glomeruli, this results in the loss of podocytes with consequent loss of constitutive angiopoietin-1 (Ang1) signaling, which is required for stability of the glomerular endothelium. Repeated tail vein injection of adenovirus expressing COMP-Ang1 (a stable bioengineered form of Ang1) was previously reported to improve diabetic glomerular damage despite the liver and lungs being primary targets of adenoviral infection. We thus hypothesized that localizing delivery of sustained COMP-Ang1 to the kidney could increase its therapeutic efficacy and safety for the treatment of diabetes.

RESEARCH DESIGN AND METHODS

Using AAVrh10 adeno-associated viral capsid with enhanced kidney tropism, we treated 10-week-old uninephrectomized db/db mice (a model of type 2 diabetes) with a single dose of AAVrh10.COMP-Ang1 delivered via the intracarotid artery, compared with untreated diabetic db/db control and non-diabetic db/m mice.

RESULTS

Surprisingly, both glomerular and pancreatic capillaries expressed COMP-Ang1, compensating for diabetes-induced loss of tissue Ang1. Importantly, treatment with AAVrh10.COMP-Ang1 yielded a significant reduction of glycemia (blood glucose, 241±193 mg/dL vs 576±31 mg/dL; glycosylated hemoglobin, 7.2±1.5% vs 11.3±1.3%) and slowed the progression of albuminuria and glomerulosclerosis in db/db mice by 70% and 61%, respectively, compared with untreated diabetic db/db mice. Furthermore, COMP-Ang1 ameliorated diabetes-induced increases of NF-kBp65, nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase-2 (Nox2), p47phox and productions of myeloperoxidase, the inflammatory markers in both renal and pancreatic tissues, and improved beta-cell density in pancreatic islets.

CONCLUSIONS

These results highlight the potential of localized Ang1 therapy for treatment of diabetic visceropathies and provide a mechanistic explanation for reported improvements in glucose control via Ang1/Tie2 signaling in the pancreas.

Resveratrol ameliorates renal damage by inhibiting oxidative stress-mediated apoptosis of podocytes in diabetic nephropathy

Diabetic nephropathy (DN) is the major cause of end-stage renal disease. Resveratrol (RSV) has been shown to exert a renoprotective effect against DN, but despite research progress, the protective mechanisms of RSV have not been fully elucidated. Here, we demonstrated that RSV relieved a series of pathological characteristics of DN and attenuated oxidative stress and apoptosis in the renal tissues of diabetic (db/db) mice. In addition, RSV inhibited oxidative stress production and apoptosis in human podocytes exposed to high glucose. Furthermore, inhibition of reactive oxygen species generation by reactive oxygen species scavengers N-acetylcysteine and 2,2,6,6-tetramethyl-1-piperidinyloxy had the same anti-apoptosis effects on podocytes as did RSV. Finally, we found that 5' adenosine monophosphate-activated protein kinase (AMPK) was activated by RSV in db/db mice and podocytes exposed to high glucose. The protective effects of RSV on podocytes were suppressed by Compound C, a pharmacological inhibitor of AMPK. Together, our results indicate that RSV effectively attenuated renal damage by suppressing oxidative stress-mediated apoptosis of podocytes, which was dependent on AMPK activation. This study revealed a possible mechanism to protect podocytes against apoptosis in DN.

LCZ696 mitigates diabetic-induced nephropathy through inhibiting oxidative stress, NF-κB mediated inflammation and glomerulosclerosis in rats

Background

Diabetic nephropathy (DN) is among the most common microvascular complications of diabetes resulting in end-stage renal disease and therefore search for candidates which can ameliorate the kidney function is needed simultaneously with standard diabetic pharmacotherapy. The current study was aimed to investigate the effect of long term sacubitril/valsartan therapy (LCZ696) in diabetic rats to assess its ameliorative impact against various pathological parameters such as oxidative stress, inflammation and glomerulosclerosis associated with chronic DN.

Methods

A single dose (60 mg/kg/day) of STZ was used to induce type 1 diabetes in adult male wistar rats. 2 weeks after diabetes induction, these rats were treated orally with valsartan (31 mg/kg) or LCZ696 (68 mg/kg) for 6 weeks. At end of the treatment period, serum and kidney samples were collected and analyzed. The serum levels of glucose, insulin, urea, creatinine, TNF-α, IL-1β, IL-6 and IL-10 levels were estimated. In renal tissue homogenate, the levels of inflammatory markers such as TNF-α, IL-1β, IL-6, NF-kB along with oxidative stress biomarkers including thiobarbituric acid-reacting substances (TBARs), glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST) were assessed. Histological changes were observed in kidney.

Results

Time course therapy withLCZ696 and valsartan in diabetic rats resulted in significant reduction of serum glucose, urea and creatinine levels (P < 0.05). Additionally, serum of treated diabetic rats showed a diminution in inflammatory (TNF-α, IL-1β, IL-6) and increment in anti-inflammatory (IL-10) cytokines levels (P < 0.05). Tissue homogenate of the kidney extracted from LCZ696 and valsartan treated diabetic rats revealed a substantial reduction in the levels of inflammatory markers such as TNF-α, IL-1β, IL-6, NF-kB and sufficient restoration of anti-oxidant enzyme levels (P < 0.05). Finally, in the histological sections of the kidney, prevention of renal injury was observed with limited necrosis and inflammatory cells infiltration.

Conclusion

Present data suggest that LCZ696 has sufficient therapeutic potential to restrict DN progression through inhibiting inflammation, oxidative stress and glomerulosclerosis.

Tetrandrine Suppresses Transient Receptor Potential Cation Channel Protein 6 Overexpression- Induced Podocyte Damage via Blockage of RhoA/ROCK1 Signaling

Objective

Podocyte damage is common in many renal diseases characterized by proteinuria. Transient receptor potential cation channel protein 6 (TRPC6) plays an important role in renal function through its regulation of intracellular Ca²⁺ influx and RhoA/ROCK pathways. Chinese herb Stephania tetrandra, with the main active component being tetrandrine, has been used for the treatment of various kidney diseases for several years and has shown a positive effect. This study aimed at investigating the effect and mechanism of tetrandrine in podocyte damage induced by high expression of TRPC6.

Methods

Immortalized, differentiated murine podocytes, MPC5 were treated with valsartan (0–800 μM) and tetrandrine (0–40 μM) for 48 h. The maximum safe concentrations of valsartan and tetrandrine were selected using a cell viability assay. MPC5 podocytes stably expressing TRPC6 were constructed using a lentivirus packaging system, followed by treatment with valsartan, tetrandrine, and Y-27632 for 48 h and U73122 (10 μM) for 10 min. The RhoA/ROCK pathway and podocyte-specific proteins (nephrin and synaptopodin) levels were quantified. Podocyte apoptosis and intracellular Ca²⁺ concentration were measured.

Results

Maximum safe concentrations of 100 μM valsartan and 10 μM tetrandrine showed no observable toxicity in podocytes. MPC5 podocytes stably expressing TRPC6 had higher intracellular Ca²⁺ influx, apoptotic percentages, and expression of RhoA/ROCK proteins, but lower expression of nephrin and synaptopodin proteins. U73122 treatment for 10 min did not inhibit TRPC6, but suppressed RhoA/ROCK protein. Y-27632 decreased ROCK1 expression, but did not influence the expression of TRPC6 protein. Both 100 μM valsartan and 10 μM tetrandrine for 48 h significantly inhibited intracellular Ca²⁺ influx, apoptosis, and RhoA/ROCK pathway, and increased nephrin and synaptopodin proteins in podocytes stably expressing TRPC6.

Conclusion

Elevated TRPC6 expression can lead to podocyte injury by inducing intracellular Ca²⁺ influx and apoptosis of podocytes, and this effect may be mediated by activation of the RhoA/ROCK1 pathway. Tetrandrine can alleviate podocyte injury induced by TRPC6 expression through inhibition of the RhoA/ROCK pathway, suggesting a protective role in podocyte damage.

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.

The diabetes pandemic suggests unmet needs for 'CKD with diabetes' in addition to 'diabetic nephropathy'-implications for pre-clinical research and drug testing

Curing 'diabetic nephropathy' is considered an unmet medical need of high priority. We propose to question the concept of 'diabetic nephropathy' that implies diabetes as the predominant cause of kidney disease, which may not apply to the majority of type 2 diabetics approaching end-stage kidney disease. With the onset of diabetes, hyperglycaemia/sodium-glucose co-transporter-2-driven glomerular hyperfiltration promotes nephron hypertrophy, which, however, on its own, causes proteinuria not before a decade later, probably because podocyte hypertrophy can usually accommodate an increase in the filtration surface. In contrast, precedent chronic kidney disease (CKD), that is, few nephrons per body mass, e.g. due to poor nephron endowment from birth, obesity, pregnancy, or renal ageing or injury-related nephron loss, usually precedes the onset of type 2 diabetes. This applies in particular in older adults, and each on its own, but especially in combination, further aggravates single nephron hyperfiltration and glomerular hypertrophy. Whenever this additional hyperglycaemia-driven enlargement of the glomerular filtration surface exceeds the capacity of podocytes for hypertrophy, podocytes detachment leads to glomerulosclerosis and nephron loss, i.e. CKD progression. Animal models of 'diabetic nephropathy' based only on hyperglycaemia do not mimic this aspect and therefore poorly predict outcomes of clinical trials usually performed on elderly CKD patients with type 2 diabetes. Thus, we advocate the use of renal mass (nephron) ablation in type 2 diabetic animals to better mimic the pathophysiology of 'CKD with diabetes' in the target patient population and the use of the glomerular filtration rate as a primary endpoint to more reliably predict trial outcomes.

Prorenin independently causes hypertension and renal and cardiac fibrosis in cyp1a1-prorenin transgenic rats

Plasma prorenin is commonly elevated in diabetic patients and appears to predict the development of diabetic nephropathy. However, the pathological role of prorenin is unclear. In the present study, a transgenic, inducible, hepatic prorenin-overexpressing rat model was generated and the effect of prorenin in organ injury was examined. Four groups of rats (cyp1a1 prorenin transgenic male and female rats and non-transgenic littermates) were assigned to receive a diet containing 0.3% of the transgene inducer indole-3-carbinol (I3C) for 4 weeks. Plasma prorenin concentration was increased and mean arterial pressure (MAP) increased from 80 ± 18 to 138 ± 17 (mmHg), whereas renal prorenin/renin protein expression was unchanged, in transgenic rats fed with I3C diet. The intact prorenin, not renin, in plasma and urine samples was further observed by Western blot analysis. Importantly, transgenic rats with high levels of prorenin developed albuminuria, glomerular and tubulointerstitial fibrosis associated with increased expression of transforming growth factor β (TGFβ) 1 (TGFβ1), plasminogen activator inhibitor-1 (PAI-1), collagen, and fibronectin (FN). These rats also exhibited cardiac hypertrophy determined by echocardiography, with elevated ratio of heart weight to body weight (HW/BW). Cardiac collagen in interstitial and perivascular regions was prominent, accompanied by the increase in mRNA contents of atrial natriuretic peptide (ANP), brain natriuretic peptide (BNP), β-myosin heavy chain (β-MHC), TGFβ1, PAI-1, and collagen in the heart tissue. Furthermore, renal protein levels of p-NF-κB-p65 and monocyte chemoattractant protein-1 (MCP-1), NAPDH oxidases, malondialdehyde (MDA) and 8-isoprostane (8-IP), p-ERK, p-β-catenin, and p-Akt were dramatically increased in prorenin overexpressing rats. These results indicate that prorenin, without being converted into renin, causes hypertension, renal and cardiac fibrosis via the induction of inflammation, oxidative stress and the ERK, β-catenin, and Akt-mediated signals.

Adiponectin attenuates kidney injury and fibrosis in deoxycorticosterone acetate-salt and angiotensin II-induced CKD mice

Adiponectin (ApN) is a multifunctional adipokine. However, high, rather than low, concentrations of ApN are unexpectedly found in patients with chronic kidney disease (CKD) via an as yet unknown mechanism, and the role of ApN in CKD is unclear. Herein, we investigated the effect of ApN overexpression on progressive renal injury resulting from deoxycorticosterone acetate-salt (DOCA) and angiotensin II (ANG II) infusion using a transgenic, inducible ApN-overexpressing mouse model. Three groups of mice [wild type receiving no infusion (WT) and WT and cytochrome P450 1a1 (cyp1a1)-ApN transgenic mice (ApN-Tg) receiving DOCA+ANG II infusion (WT/DOCA+ANG II and ApN-Tg/DOCA+ANG II)] were assigned to receive normal food containing 0.15% of the transgene inducer indole-3-carbinol (I3C) for 3 wk. In the I3C-induced ApN-Tg/DOCA+ANG II mice, not the WT or WT/DOCA+ANG II mice, overexpression of ApN in liver resulted in 3.15-fold increases in circulating ApN compared with nontransgenic controls. Of note, the transgenic mice receiving DOCA+ANG II infusion were still hypertensive but had much less albuminuria and glomerular and tubulointerstitial fibrosis, which were associated with ameliorated podocyte injury determined by ameliorated podocyte loss and foot process effacement, and alleviated tubular injury determined by ameliorated mRNA overexpression of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin and mRNA decreases of cubilin and megalin in tubular cells, compared with WT/DOCA+ANG II mice. In addition, renal production of NF-κB-p65, NAPDH oxidase 2, and p47 ^phox and MAPK-related cellular proliferation, which were induced in WT/DOCA+ANG II mice, were markedly reduced in ApN-Tg/DOCA+ANG II mice. These results indicate that elevated ApN in the CKD mouse model is renal protective. Enhancing ApN production or signaling may have therapeutic potential for CKD.

Translational science in albuminuria: a new view of de novo albuminuria under chronic RAS suppression

The development of de novo albuminuria during chronic renin–angiotensin system (RAS) suppression is a clinical entity that remains poorly recognized in the biomedical literature. It represents a clear increment in global cardiovascular (CV) and renal risk that cannot be counteracted by RAS suppression. Although not specifically considered, it is clear that this entity is present in most published and ongoing trials dealing with the different forms of CV and renal disease. In this review, we focus on the mechanisms promoting albuminuria, and the predictors and new markers of de novo albuminuria, as well as the potential treatment options to counteract the excretion of albumin. The increase in risk that accompanies de novo albuminuria supports the search for early markers and predictors that will allow practising physicians to assess and prevent the development of de novo albuminuria in their patients.

Dapagliflozin slows the progression of the renal and liver fibrosis associated with type 2 diabetes

Sodium-glucose cotransporter 2 (SGLT2) inhibitors are a new class of antidiabetic oral agents indicating promising effects on cardiovascular and renal end points. However, the renoprotective effects of SGLT2 inhibitors are not fully understood. Also, metabolic effects of SGLT2 inhibition on other organ systems, such as effects on hepatic steatosis, are not fully understood. This study sought to address these questions by treating 18-wk-old uninephrectomized db/db mice with the selective SGLT2 inhibitor dapagliflozin. Untreated db/db mice developed progressive albuminuria, glomerular mesangial matrix expansion, and fatty liver associated with increased renal expression of TGFβ1, PAI-1, type IV collagen and fibronectin, and liver deposition of fibronectin, type I and III collagen, and laminin. Treatment with dapagliflozin (1 mg·kg^-1·day^-1) via gel diet from 18 to 22 wk of age not only reduced blood glucose (371.14 ± 55.02 mg/dl in treated db/db vs. 573.53 ± 21.73 mg/dl in untreated db/db, P < 0.05) and Hb A_1c levels (9.47 ± 0.79% in treated db/db vs. 12.1 ± 0.73% in untreated db/db, P < 0.05) but also ameliorated the increases in albuminuria and markers of glomerulosclerosis and liver injury seen in untreated db/db mice. Furthermore, both renal expressions of NF-kB p65, MCP-1, Nox4, Nox2, and p47phox and urine TBARS levels and liver productions of myeloperoxidase and reactive oxygen species, the markers of tissue inflammation and oxidative stress, were increased in untreated db/db mice, which were reduced by dapagliflozin administration. These results demonstrate that dapagliflozin not only improves hyperglycemia but also slows the progression of diabetes-associated glomerulosclerosis and liver fibrosis by improving hyperglycemia-induced tissue inflammation and oxidative stress.

High levels of circulating TNFR1 increase the risk of all-cause mortality and progression of renal disease in type 2 diabetic nephropathy

BACKGROUND

Several studies have demonstrated that levels of circulating inflammatory markers such as tumour necrosis factorα (TNFα), are associated with early progression of diabetic nephropathy (DN). The aim of this study was to investigate whether there is an association between circulating TNFα receptor and disease progression in patients with advanced type 2 DN and severe proteinuria.

METHODS

Between 2006 and 2011, we measured levels of circulating soluble TNFα receptor 1 (TNFR1) and soluble TNFα receptor 2 (TNFR2) at baseline and 4 and 12 months in 101 patients included in a multicenter randomized controlled trial to compare the effect of optimal doses of renin-angiotensin system blockers in monotherapy or in combination (dual blockade) to slow progression of established type 2 DN. The primary composite endpoint was a >50% increase in baseline serum creatinine, end-stage renal disease, or death.

RESULTS

The median follow-up was 32 months (IQR, 18-48), during which time 28 patients (22.7%) achieved the primary endpoint. The TNFR1 level, but not the TNFR2 level, was correlated with other inflammatory markers. Cox regression analysis showed that the highest TNFR1 levels (HR, 2.60; 95%CI, 1.11-86.34) and baseline proteinuria (HR 1.32; 95%CI 1.15-1.52) were associated with the primary endpoint. The mixed model analysis revealed that TNFR1 and the TNFR2 levels did not change after starting treatment with renin-angiotensin system blockers.

CONCLUSIONS

Our results show that the highest levels of TNFR1 are independently associated with progression of renal disease and death in type 2 DN. The renin angiotensin blockers have no effect on these inflammatory markers.

Renoprotective Effect of the Shen-Yan-Fang-Shuai Formula by Inhibiting TNF-α/NF-κB Signaling Pathway in Diabetic Rats

Diabetic kidney disease (DKD) is the leading cause of end-stage kidney disease, and satisfactory therapeutic strategies have not yet been established. The Shen-Yan-Fang-Shuai Formula (SYFSF) is a traditional Chinese formula composed of Astragali radix, Radixangelicae sinensis, Rheum officinale Baill, and four other herbs. It has been widely used as an effective treatment for DKD patients in China. However, little is known about the molecular mechanisms underlying SYFSF's renoprotection. In this study, we compared the protective effect of SYFSF to irbesartan on the histology and renal cells in type 2 DKD rat model and high-glucose (HG) cultured mesangial cells, respectively. We found that SYFSF could significantly decrease urinary albumin, cholesterol, and triglyceride. And a decrease in serum creatinine was also found in SYFSF-treated group compared with irbesartan-treated rats. In addition, SYFSF inhibited the interstitial expansion and glomerulosclerosis in diabetic rats. Notably, SYFSF markedly downregulated the expression of MCP-1, TGF-β1, collagen IV, and fibronectin in diabetic rat models and HG-induced mesangial cell models. The renoprotection was closely associated with a reduced expression of TNF-α and phosphorylated NF-κBp65. Our study suggests that SYFSF may ameliorate diabetic kidney injury. The observed renoprotection is probably attributable to an inhibition of inflammatory response and extracellular matrix (ECM) accumulation mediated by TNF-α/NF-κBp65 signaling pathway.

A novel pan-Nox inhibitor, APX-115, protects kidney injury in streptozotocin-induced diabetic mice: possible role of peroxisomal and mitochondrial biogenesis

NADPH oxidase (Nox)-derived reactive oxygen species (ROS) are increasingly recognized as a key factor in inflammation and extracellular matrix accumulation in diabetic kidney disease. APX-115 (3-phenyl-1-(pyridin-2-yl)-4-propyl-1-5-hydroxypyrazol HCl) is a novel orally active pan-Nox inhibitor. The objective of this study was to compare the protective effect of APX-115 with a renin-angiotensin system inhibitor (losartan), the standard treatment against kidney injury in diabetic patients, on streptozotocin (STZ)-induced diabetic kidney injury. Diabetes was induced by intraperitoneal injection of STZ at 50 mg/kg/day for 5 days in C57BL/6J mice. APX-115 (60 mg/kg/day) or losartan (1.5 mg/kg/day) was administered orally to diabetic mice for 12 weeks. APX-115 effectively prevented kidney injury such as albuminuria, glomerular hypertrophy, tubular injury, podocyte injury, fibrosis, and inflammation as well as oxidative stress in diabetic mice, similar to losartan. In addition, both APX-115 and losartan treatment effectively inhibited mitochondrial and peroxisomal dysfunction associated with lipid accumulation. Our data suggest that APX-115, a pan-Nox inhibitor, may become a novel therapeutic agent against diabetic kidney disease by maintaining peroxisomal and mitochondrial fitness.

Role of TGF-alpha in the progression of diabetic kidney disease

Transforming growth factor-alpha (TGFA) has been shown to play a role in experimental chronic kidney disease associated with nephron reduction, while its role in diabetic kidney disease (DKD) is unknown. We show here that intrarenal TGFA mRNA expression, as well as urine and serum TGFA, are increased in human DKD. We used a TGFA neutralizing antibody to determine the role of TGFA in two models of renal disease, the remnant surgical reduction model and the uninephrectomized (uniNx) db/db DKD model. In addition, the contribution of TGFA to DKD progression was examined using an adeno-associated virus approach to increase circulating TGFA in experimental DKD. In vivo blockade of TGFA attenuated kidney disease progression in both nondiabetic 129S6 nephron reduction and Type 2 diabetic uniNx db/db models, whereas overexpression of TGFA in uniNx db/db model accelerated renal disease. Therapeutic activity of the TGFA antibody was enhanced with renin angiotensin system inhibition with further improvement in renal parameters. These findings suggest a pathologic contribution of TGFA in DKD and support the possibility that therapeutic administration of neutralizing antibodies could provide a novel treatment for the disease.

RAGE-Aptamer Blocks the Development and Progression of Experimental Diabetic Nephropathy

The interaction of advanced glycation end products (AGEs) and their receptor (RAGE) plays a central role in diabetic nephropathy. We screened DNA aptamers directed against RAGE (RAGE-aptamers) in vitro and examined the effects on the development and progression of diabetic nephropathy in streptozotocin-induced diabetic rats. RAGE-aptamer bound to RAGE with a K_d of 5.68 nmol/L and resultantly blocked the binding of AGEs to RAGE. When diabetic rats received continuous intraperitoneal injection of RAGE-aptamer from week 7 to 11 of diabetes, the increases in renal NADPH oxidase activity, oxidative stress generation, AGE, RAGE, inflammatory and fibrotic gene and protein levels, macrophage and extracellular matrix accumulation, and albuminuria were significantly suppressed, which were associated with improvement of podocyte damage. Two-week infusion of RAGE-aptamer just after the induction of diabetes also inhibited the AGE-RAGE-oxidative stress system and MCP-1 levels in the kidneys of 8-week-old diabetic rats and simultaneously ameliorated podocyte injury and albuminuria. Moreover, RAGE-aptamer significantly suppressed the AGE-induced oxidative stress generation and inflammatory and fibrotic reactions in human cultured mesangial cells. The findings suggest that continuous infusion of RAGE-aptamer could attenuate the development and progression of experimental diabetic nephropathy by blocking the AGE-RAGE axis.

Effects of valsartan and amlodipine on oxidative stress in type 2 diabetic patients with hypertension: a randomized, multicenter study

BACKGROUND/AIMS

Oxidative stress plays an important role in the pathogenesis and progression of diabetic complications and antagonists of renin-angiotensin system and amlodipine have been reported previously to reduce oxidative stress. In this study, we compared the changes in oxidative stress markers after valsartan and amlodipine treatment in type 2 diabetic patients with hypertension and compared the changes in metabolic parameters.

METHODS

Type 2 diabetic subjects with hypertension 30 to 80 years of age who were not taking antihypertensive drugs were randomized into either valsartan (n = 33) or amlodipine (n = 35) groups and treated for 24 weeks. We measured serum nitrotyrosine levels as an oxidative stress marker. Metabolic parameters including serum glucose, insulin, lipid profile, and urine albumin and creatinine were also measured.

RESULTS

After 24 weeks of valsartan or amlodipine treatment, systolic and diastolic blood pressure decreased, with no significant difference between the groups. Both groups showed a decrease in serum nitrotyrosine (7.74 ± 7.30 nmol/L vs. 3.95 ± 4.07 nmol/L in the valsartan group and 8.37 ± 8.75 nmol/L vs. 2.68 ± 2.23 nmol/L in the amlodipine group) with no significant difference between the groups. Other parameters including glucose, lipid profile, albumin-to-creatinine ratio, and homeostasis model assessment of insulin resistance showed no significant differences before and after treatment in either group.

CONCLUSIONS

Valsartan and amlodipine reduced the oxidative stress marker in type 2 diabetic patients with hypertension.

APX-115, a first-in-class pan-NADPH oxidase (Nox) inhibitor, protects db/db mice from renal injury

Recent studies have suggested that renal Nox is important in the progression of diabetic nephropathy. Therefore, we investigated the effect of a novel pan-NOX-inhibitor, APX-115, on diabetic nephropathy in type 2 diabetic mice. Eight- week-old db/m and db/db mice were treated with APX-115 for 12 weeks. APX-115 was administered by oral gavage at a dose of 60 mg/kg per day. To compare the effects of APX-115 with a dual Nox1/Nox4 inhibitor, db/db mice were treated with GKT137831 according to the same protocol. APX-115 significantly improved insulin resistance in diabetic mice, similar to GKT137831. Oxidative stress as measured by plasma 8-isoprostane level was decreased in the APX-115 group compared with diabetic controls. All lipid profiles, both in plasma and tissues improved with Nox inhibition. APX-115 treatment decreased Nox1, Nox2, and Nox4 protein expression in the kidney. APX-115 decreased urinary albumin excretion and preserved creatinine level. In diabetic kidneys, APX-115 significantly improved mesangial expansion, but GKT137831 did not. In addition, F4/80 infiltration in the adipose tissue and kidney decreased with APX-115 treatment. We also found that TGF-β stimulated ROS generation in primary mouse mesangial cells (pMMCs) from wild-type, Nox1 KO, and Duox1 KO mice, but did not induce Nox activity in pMMCs from Nox2 knockout (KO), Nox4 KO, or Duox2 KO mice. These results indicate that activating Nox2, Nox4, or Duox2 in pMMCs is essential for TGF-β-mediated ROS generation. Our findings suggest that APX-115 may be as effective or may provide better protection than the dual Nox1/Nox4 inhibitor, and pan-Nox inhibition with APX-115 might be a promising therapy for diabetic nephropathy.

Differential renal effects of candesartan at high and ultra-high doses in diabetic mice-potential role of the ACE2/AT2R/Mas axis

High doses of Ang II receptor (AT1R) blockers (ARBs) are renoprotective in diabetes. Underlying mechanisms remain unclear. We evaluated whether high/ultra-high doses of candesartan (ARB) up-regulate angiotensin-converting enzyme 2 (ACE2)/Ang II type 2 receptor (AT2R)/Mas receptor [protective axis of the of the renin–angiotensin system (RAS)] in diabetic mice. Systolic blood pressure (SBP), albuminuria and expression/activity of RAS components were assessed in diabetic db/db and control db/+ mice treated with increasing candesartan doses (intermediate, 1 mg/kg/d; high, 5 mg/kg/d; ultra-high, 25 and 75 mg/kg/d; 4 weeks). Lower doses candesartan did not influence SBP, but ultra-high doses reduced SBP in both groups. Plasma glucose and albuminuria were increased in db/db compared with db/+ mice. In diabetic mice treated with intermediate dose candesartan, renal tubular damage and albuminuria were ameliorated and expression of ACE2, AT2R and Mas and activity of ACE2 were increased, effects associated with reduced ERK1/2 phosphorylation, decreased fibrosis and renal protection. Ultra-high doses did not influence the ACE2/AT2R/Mas axis and promoted renal injury with increased renal ERK1/2 activation and exaggerated fibronectin expression in db/db mice. Our study demonstrates dose-related effects of candesartan in diabetic nephropathy: intermediate–high dose candesartan is renoprotective, whereas ultra-high dose candesartan induces renal damage. Molecular processes associated with these effects involve differential modulation of the ACE2/AT2R/Mas axis: intermediate–high dose candesartan up-regulating RAS protective components and attenuating pro-fibrotic processes, and ultra-high doses having opposite effects. These findings suggest novel mechanisms through the protective RAS axis, whereby candesartan may ameliorate diabetic nephropathy. Our findings also highlight potential injurious renal effects of ultra-high dose candesartan in diabetes.

An additive effect of anti-PAI-1 antibody to ACE inhibitor on slowing the progression of diabetic kidney disease

While angiotensin II blockade slows the progression of diabetic nephropathy, current data suggest that it alone cannot stop the disease process. New therapies or drug combinations will be required to further slow or halt disease progression. Inhibition of plasminogen activator inhibitor type 1 (PAI-1) aimed at enhancing ECM degradation has shown therapeutic potential in diabetic nephropathy. Here, using a mouse model of type diabetes, the maximally therapeutic dose of the PAI-1-neutralizing mouse monoclonal antibody (MEDI-579) was determined and compared with the maximally effective dose of enalapril. We then examined whether addition of MEDI-579 to enalapril would enhance the efficacy in slowing the progression of diabetic nephropathy. Untreated uninephrectomized diabetic db/db mice developed progressive albuminuria and glomerulosclerosis associated with increased expression of transforming growth factor (TGF)-β1, PAI-1, type IV collagen, and fibronectin from weeks 18 to 22, which were reduced by MEDI-579 at 3 mg/kg body wt, similar to enalapril given alone from weeks 12 to 22 Adding MEDI-579 to enalapril from weeks 18 to 22 resulted in further reduction in albuminuria and markers of renal fibrosis. Renal plasmin generation was dramatically reduced by 57% in diabetic mice, a decrease that was partially reversed by MEDI-579 or enalapril given alone but was further restored by these two treatments given in combination. Our results suggest that MEDI-579 is effective in slowing the progression of diabetic nephropathy in db/db mice and that the effect is additive to ACEI. While enalapril is renal protective, the add-on PAI-1 antibody may offer additional renoprotection in progressive diabetic nephropathy via enhancing ECM turnover.

RAS and sex differences in diabetic nephropathy

The incidence and progression of kidney diseases are influenced by sex. The renin-angiotensin system (RAS) is an important regulator of cardiovascular and renal function. Sex differences in the renal response to RAS blockade have been demonstrated. Circulating and renal RAS has been shown to be altered in type 1 and type 2 diabetes; this enzymatic cascade plays a critical role in the development of diabetic nephropathy (DN). Angiotensin converting enzyme (ACE) and ACE2 are differentially regulated depending on its localization within the diabetic kidney. Furthermore, clinical and experimental studies have shown that circulating levels of sex hormones are clearly modulated in the context of diabetes, suggesting that sex-dependent RAS regulation may be also be affected in these individuals. The effect of sex hormones on circulating and renal RAS may be involved in the sex differences observed in DN progression. In this paper we will review the influence of sex hormones on RAS expression and its relation to diabetic kidney disease. A better understanding of the sex dimorphism on RAS might provide a new approach for diabetic kidney disease treatment.

Melatonin nephroprotective action in Zucker diabetic fatty rats involves its inhibitory effect on NADPH oxidase

Excessive activity of NADPH oxidase (Nox) is considered to be of importance for the progress of diabetic nephropathy. The aim of the study was to elucidate the effect of melatonin, known for its nephroprotective properties, on Nox activity under diabetic conditions. The experiments were performed on three groups of animals: (i) untreated lean (?/+) Zucker diabetic fatty (ZDF) rats; (ii) untreated obese diabetic (fa/fa) ZDF rats; and (iii) ZDF fa/fa rats treated with melatonin (20 mg/L) in drinking water. Urinary albumin excretion was measured weekly. After 4 wk of the treatment, the following parameters were determined in kidney cortex: Nox activity, expression of subunits of the enzyme, their phosphorylation and subcellular distribution. Histological studies were also performed. Compared to ?/+ controls, ZDF fa/fa rats exhibited increased renal Nox activity, augmented expression of Nox4 and p47(phox) subunits, elevated level of p47(phox) phosphorylation, and enlarged phospho-p47(phox) and p67(phox) content in membrane. Melatonin administration to ZDF fa/fa rats resulted in the improvement of renal functions, as manifested by considerable attenuation of albuminuria and some amelioration of structural abnormalities. The treatment turned out to nearly normalize Nox activity, which was accompanied by considerably lowered expression and diminished membrane distribution of regulatory subunits, that is, phospho-p47(phox) and p67(phox) . Thus, it is concluded that: (i) melatonin beneficial action against diabetic nephropathy involves attenuation of the excessive activity of Nox; and (ii) the mechanism of melatonin inhibitory effect on Nox is based on the mitigation of expression and membrane translocation of its regulatory subunits.

Angiotensin II induces reorganization of the actin cytoskeleton and myosin light-chain phosphorylation in podocytes through rho/ROCK-signaling pathway

AIMS

In the present study, we have evaluated the effect of angiotensin II (Ang II) on actin cytoskeleton reorganization and myosin light-chain (MLC) phosphorylation in podocytes to demonstrate whether the Rho/Rho-associated coiled kinase (ROCK) pathway is involved podocyte injury.

METHODS

Eighteen male Sprague-Dawley rats were divided into three groups and treated with Ang II, saline or telmisartan. Morphological changes were studied at 28 days after treatment. Immunohistochemistry and Western blotting were used to determine the renal expression of p-MLC and ROCK2. Cultured podocytes were treated with Ang II (10(-7 )M) with or without Rho-kinase inhibitor (Y27632, 10(-6 )M) for variable time periods. F-actin was visualized with fluorescein isothiocyanate (FITC)-conjugated phalloidin or tetraethyl rhodamine isothiocyanate (TRITC)-conjugated phalloidin. p-MLC expression was evaluated by immunofluorescence and Western blot. The activation of Rho/ROCK was evaluated by Western blot.

RESULTS

The expression of p-MLC in glomeruli increased significantly in rats treated with Ang II when compared to the control rats as shown by Western blot (p < 0.05). In cultured podocytes, Rho A and ROCK2 increased after incubation with Ang II. Ang II increased the expression of ROCK2, which was accompanied with altered morphology, redistribution of actin and increased phosphorylation of MLC. The distribution of actin changed to a large extent, although overall quantitative differences were not observed. Addition of Y-27632 to podocytes treated with Ang II could ameliorate F-actin cytoskeleton remodeling and the increment in p-MLC expression.

CONCLUSION

Ang II-induced podocyte cytoskeleton protein expression changing through the RhoA/ROCK2 p-MLC/F-actin pathway.

You-gui Pill ameliorates renal tubulointerstitial fibrosis via inhibition of TGF-β/Smad signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

You-gui Pill (YGP), a traditional Chinese medicinal prescription, was widely used to warm and recuperate "kidney-yang" clinically for hundreds of years in China. Recent studies found that YGP had a potential benefit for renoprotection.

AIM OF THE STUDY

The present study aimed to elucidate the in vivo and in vitro efficacy of YGP on renal tubulointerstitial fibrosis, and the molecular mechanism is also investigated.

MATERIALS AND METHODS

Rat renal tubulointerstitial fibrosis model was elicited by unilateral ureteral obstruction (UUO). Sprague-Dawley rats underwent UUO and were studied after 14 days. Animals were randomly subjected to six groups: sham, UUO, UUO/YGP (0.14, 0.42, 1.26g/kg/d), and UUO/enalapril (10mg/kg/d). HE, Masson and ELISA were used for evaluate renal injury and function. Immunohistochemical analysis and western blot were used to detect the expressions of α-SMA, fibronectin, collagen matrix and Smads. In vitro studies were investigated in TGF-β1-stiumlated NRK-49F cell line.

RESULTS

Oral administration of YGP significantly decreased UUO-induced inflammatory cell infiltration, tubular atrophy and interstitial fibrosis, and there was no significant difference between YGP at 1.26g/kg and enalapril at 10mg/kg treatment (P>0.05). Meanwhile, serum creatinine and blood urea nitrogen levels were reduced dramatically (P<0.01). In coincide with the decreased of TGF-β1, α-SMA, fibronectin and collagen matrix expressions were also declined with YGP treatment in both UUO kidneys and TGF-β1-stimulated NRK-49F cell line. Additionally, nuclear translocation of p-Smad2/3 was markedly down-regulated by YGP (P<0.001), with a relative mild up-regulated expression of Smad7 (P<0.05).

CONCLUSIONS

Our findings demonstrate that YGP had a renoprotective effect in ameliorating renal tubulointerstitial fibrosis, and this activity possibly via suppression of the TGF-β and its downstream regulatory signaling pathway, including Smad2/3.

Renoprotective effects of berberine as adjuvant therapy for hypertensive patients with type 2 diabetes mellitus: Evaluation via biochemical markers and color Doppler ultrasonography

Diabetes and hypertension are complex and serious diseases that may ultimately lead to renal complications. Adequate control of blood glucose and blood pressure contributes to decreased renal risks, but may not be sufficient for certain patients. The current study was undertaken to investigate the renoprotective effects of berberine as an adjuvant therapy to standard hypotensive and hypoglycemic treatment in hypertensive patients with type 2 diabetes mellitus (T2DM). In this 2-year clinical study, 69 hypertensive patients with T2DM, whose blood pressure and fasting plasma glucose (FPG) were adequately controlled by hypotensive and oral hypoglycemic agents prior to the study, were enrolled and randomly assigned into control (33 cases) and add-on (36 cases) groups. Berberine was orally administrated to the patients in the add-on group concomitantly with standard hypotensive and hypoglycemic treatment. Baseline characteristics, including the levels of FPG, glycated hemoglobin, systolic blood pressure, diastolic blood pressure, serum creatinine, urinary albumin-to-creatine ratio (UACR), urinary osteopontin and kidney injury molecule-1 (KIM-1) were determined. Furthermore, the oxidative stress markers malondialdehyde, urinary 8-hydroxy-2'-deoxyguanosine, superoxide dismutase, glutathione peroxidase and total-antioxidant capacity, and the inflammatory parameters vascular adhesion molecule-1, C-reactive protein and high molecular weight-adiponectin were evaluated. In addition, ultrasonographic parameters, including peak systolic velocity, end diastolic velocity and renal arterial resistance index were determined. After treatment, it was observed that the control and add-on treatments were able to adequately control blood pressure and blood glucose. Patients in the add-on group exhibited significant reductions in renal damage biochemical markers (UACR, urinary osteopontin and KIM-1) and improved renal hemodynamics, in addition to reduced inflammation and oxidative stress. The present results suggest that berberine is beneficial for hypertensive patients with T2DM as add-on therapy to standard hypotensive and hypoglycemic agents.