Kidney fibrosis is considered the essential pathophysiological process for the progression of chronic kidney disease (CKD) toward renal failure. 20-Hydroxyeicosatetraenoic acid (20-HETE) has crucial roles in modulating the vascular response in the kidney and the progression of albuminuria. However, the roles of 20-HETE in kidney fibrosis are largely unexplored. In the current research, we hypothesized that if 20-HETE has important roles in the progression of kidney fibrosis, 20-HETE synthesis inhibitors might be effective against kidney fibrosis. To verify our hypothesis, this study investigated the effect of a novel and selective 20-HETE synthesis inhibitor, TP0472993, on the development of kidney fibrosis after folic acid- and obstructive-induced nephropathy in mice. Chronic treatment with TP0472993 at doses of 0.3 and 3 mg/kg twice a day attenuated the degree of kidney fibrosis in the folic acid nephropathy and the unilateral ureteral obstruction (UUO) mice, as demonstrated by reductions in Masson's trichrome staining and the renal collagen content. In addition, TP0472993 reduced renal inflammation, as demonstrated by markedly reducing interleukin-1β (IL-1β) and tumor necrosis factor alpha (TNF-α) levels in the renal tissue. Chronic treatment with TP0472993 also reduced the activity of extracellular signal-regulated kinase 1/2 (ERK1/2) and signal transducer and activator of transcription 3 (STAT3) in the kidney of UUO mice. Our observations indicate that inhibition of 20-HETE production with TP0472993 suppresses the kidney fibrosis progression via a reduction in the ERK1/2 and STAT3 signaling pathway, suggesting that 20-HETE synthesis inhibitors might be a novel treatment option against CKD. SIGNIFICANCE STATEMENT: In this study, we demonstrate that the pharmacological blockade of 20-hydroxyeicosatetraenoic acid (20-HETE) synthesis using TP0472993 suppresses the progression of kidney fibrosis after folic acid- and obstructive-induced nephropathy in mice, indicating that 20-HETE might have key roles in the pathogenesis of kidney fibrosis. TP0472993 has the potential to be a novel therapeutic approach against chronic kidney disease.

BackgroundThe endocannabinoid CB1 receptor is known to have protective effects in kidney disease. The aim of the present study is to evaluate the potential agonistic and antagonistic actions and to determine the renoprotective potential of CB1 receptors in diabetic nephropathy. The present work investigates the possible role of CB1 receptors in the pathogenesis of diabetes-induced nephropathy. Streptozotocin (STZ) (55 mg/kg, i.p., once) is administered to uninephrectomised rats for induction of experimental diabetes mellitus. The CB1 agonist (oleamide) and CB1 antagonist (AM6545) treatment were initiated in diabetic rats after 1 week of STZ administration and were given for 24 weeks.ResultsThe progress in diabetic nephropathy is estimated biochemically by measuring serum creatinine (1.28±0.03) (p < 0.005), blood urea nitrogen (67.6± 2.10) (p < 0.001), urinary microprotein (74.62± 3.47) (p < 0.005) and urinary albuminuria (28.31±1.17) (p < 0.0001). Renal inflammation was assessed by estimating serum levels of tumor necrosis factor alpha (75.69±1.51) (p < 0.001) and transforming growth factor beta (8.73±0.31) (p < 0.001). Renal morphological changes were assessed by estimating renal hypertrophy (7.38± 0.26) (p < 0.005) and renal collagen content (10.42± 0.48) (p < 0.001).ConclusionsFrom the above findings, it can be said that diabetes-induced nephropathy may be associated with overexpression of CB1 receptors and blockade of CB1 receptors might be beneficial in ameliorating the diabetes-induced nephropathy.Graphical abstract

Mesenchymal stromal cell (MSC) therapy may improve renal function after ischemia-reperfusion injury in transplantation. Ex vivo renal intraarterial administration is a targeted delivery method, avoiding the lung vasculature, a known barrier for cellular therapies. In a randomized and blinded study, we tested the feasibility and effectiveness of MSC therapy in a donation after circulatory death autotransplantation model to improve posttransplant kidney function, using an ex vivo MSC delivery method similar to the clinical standard procedure of pretransplant cold graft flush. Kidneys exposed to 75 minutes of warm ischemia and 16 hours of static cold storage were intraarterially infused ex vivo with 10 million male porcine MSCs (Tx-MSC, n = 8) or vehicle (Tx-control, n = 8). Afterwards, the kidneys were autotransplanted after contralateral nephrectomy. Biopsies an hour after reperfusion confirmed the presence of MSCs in the renal cortex. Animals were observed for 14 days. Postoperatively, peak plasma creatinine was 1230 and 1274 µmol/L (Tx-controls versus Tx-MSC, P = 0.69). During follow-up, no significant differences over time were detected between groups regarding plasma creatinine, plasma neutrophil gelatinase-associated lipocalin, or urine neutrophil gelatinase-associated lipocalin/creatinine ratio. At day 14, measured glomerular filtration rates were 40 and 44 mL/min, P = 0.66. Renal collagen content and fibrosis-related mRNA expression were increased in both groups but without significant differences between the groups. We demonstrated intraarterial MSC infusion to transplant kidneys as a safe and effective method to deliver MSCs to the graft. However, we could not detect any positive effects of this cell treatment within 14 days of observation.

Diabetes is the leading cause of chronic kidney disease and end stage renal disease which is most common reason for mortality and morbidity such as cardiovascular disease and renal dysfunction, a major reason for mortality The uncontrolled diabetes mellitus often leads to renal complications. Nephropathy is chief cause of death among people having chronic diabetes mellitus Elevated serum creatinine, blood urea nitrogen, renal collagen content and reduced level of serum nitrite/ nitrate are markers of diabetic nephropathy In addition, diabetic nephropathy characterized by glomerular hypertrophy, accumulation of extracellular matrix protein, increased basement membrane thickness, mesangial expansion, podocyte loss and vascular endothelial dysfunction p r o g r e s s i v e l y l e a d i n g t o g l o m e r u l o s c l e r o s i s , tubulointerstitial fibrosis, proteinuria and dyslipidaemia The progression of diabetic nephropathy can be controlled by optimal glucose control. Recent studies have demonstrated involvement of dyslipidaemia and mitochondrial dysfunction in the development of diabetic nephropathy Dyslipidaemic condition includes hypertriglyceridemia (TG), reduced high density lipoprotein (HDL) and elevated low density lipoprotein (LDL). Dyslipidaemia plays critical role in the pathogenesis of nephropathy.

Abstract Background Diabetes is a downregulator of atrial natriuretic peptide (ANP), resulting in reduced nitric oxide level and low expression of endothelial nitric oxide synthase by which nitric oxide level get reduced. In the present study, we examined the role of ANP in reduced nitric oxide level, which may be responsible in controlling diabetic nephropathy in rats. Methods Serum nitrite/nitrate ratio, blood urea nitrogen, protein in urine, urinary output, serum creatinine, serum cholesterol, kidney weight, kidney hypertrophy, renal cortical collagen content, thiobarbituric acid level, and antioxidant enzymatic activities were assessed. Results Treatment with lisinopril (1 mg/kg) significantly attenuated diabetes-induced elevated glucose level, cholesterol level, and protein in urine concentration. Whereas ANP at low dose (5 μg/kg) has no effect on elevated markers of diabetic nephropathy, treatment with intermediate (10 μg/kg) and high-dose ANP (20 μg/kg) significantly attenuated the diabetes-induced increased blood urea nitrogen, protein in urine, urinary output, creatinine, cholesterol, kidney weight, kidney hypertrophy, renal collagen content, and thiobarbituric acid level and reduced endogenous antioxidant enzymatic activities. High dose of ANP was more effective in attenuating the diabetes-induced nephropathy, renal oxidative stress, and antioxidant enzyme activity as compared with the treatment with low-dose ANP (5 μg/kg), intermediate-dose ANP (10 μg/kg), or lisinopril (1 mg/kg, employed as standard agent). Administration of erythro-9-(2-hydroxy-3-nonyl)adenine, a phosphodiesterase-2 inhibitor (3 mg/kg), in combination with high-dose ANP significantly attenuated high-dose ANP induced ameliorative effects in diabetic nephropathy. Conclusions Taken together, these results indicate that diabetes-induced oxidative stress and lipid alterations may be responsible for the induction of nephropathy in diabetic rats. ANP at intermediate and high doses have prevented the development of diabetes-induced nephropathy by reducing the cholesterol level, protein in urine concentration, and renal oxidative stress and by increasing the nitrite/nitrate ratio, certainly providing the direct nephroprotective action.

Introduction: Obesity increases the risk of salt sensitive hypertension and kidney damage. AcSDKP is a natural tetrapeptide with anti-inflammatory and antifibrotic properties but its effect on obesity-related salt sensitive hypertension and renal damage is unknown. Hypothesis: AcSDKP prevents high-sodium diet (HSD) induced hypertension and kidney damage in obese rats. Methods: Eight-week-old Zucker obese rats (ZOR) and Zucker lean rats (ZLR) were treated with AcSDKP (1.6 mg/kg/day infused via osmotic minipumps) while maintained on either normal-sodium diet (NSD; 0.4%) or high-sodium diet (HSD; 4%) for 8 wk. Rats were divided into following six groups: ZOR+vehicle, ZOR+HSD, ZOR+HSD+AcSDKP, ZLR+vehicle, ZLR+ HSD, and ZLR+HSD+AcSDKP. Systolic blood pressure (SBP) was measured by tail cuff method. 24-hour urine collection was done to measure albuminuria as a marker of renal damage. Renal fibrosis (collagen content in the kidney) was measured by hydroxyproline assay. Medullary and cortical interstitial fibrosis was measured by picrosirius red staining. Results: are summarized in Table 1. HSD increased SBP in ZOR but not in ZLR. AcSDKP treatment prevented HSD induced increase in BP in ZOR. HSD increased renal collagen content both in ZOR and ZLR and AcSDKP treatment decreased it. Increased interstitial fibrosis induced by high salt diet was confirmed by PSR staining in both cortical and medullary region and AcSDKP prevented this increase. Albuminuria in ZOR was significantly higher than ZLR, however neither high salt nor AcSDKP treatment was unable to normalize it. Conclusion: Chronic treatment with AcSDKP prevents high salt-induced hypertension and renal fibrosis in ZOR.

Anakinra reduces blood pressure and renal fibrosis in one kidney/DOCA/salt-induced hypertension

ObjectiveThe aim of this study was to investigate the effects of chronic treatment with atrial natriuretic peptide (ANP) on renal function, nitric oxide (NO) system, oxidative stress, collagen content and apoptosis in kidneys of spontaneously hypertensive rats (SHR), as well as sex-related differences in the response to the treatment.Methods10 week-old male and female SHR were infused with ANP (100 ng/h/rat) or saline (NaCl 0.9%) for 14 days (subcutaneous osmotic pumps). Systolic blood pressure (SBP) was recorded and diuresis and natriuresis were determined. After treatment, renal NO synthase (NOS) activity and eNOS expression were evaluated. Thiobarbituric acid-reactive substances (TBARS), glutathione concentration and glutathione peroxidase (GPx) and superoxide dismutase (SOD) activities were determined in the kidney. Collagen was identified in renal slices by Sirius red staining and apoptosis by Tunel assay.ResultsFemale SHR showed lower SBP, oxidative stress, collagen content and apoptosis in kidney, and higher renal NOS activity and eNOS protein content, than males. ANP lowered SBP, increased diuresis, natriuresis, renal NOS activity and eNOS expression in both sexes. Renal response to ANP was more marked in females than in males. In kidney, ANP reduced TBARS, renal collagen content and apoptosis, and increased glutathione concentration and activity of GPx and SOD enzymes in both sexes.ConclusionsFemale SHR exhibited less organ damage than males. Chronic ANP treatment would ameliorate hypertension and end-organ damage in the kidney by reducing oxidative stress, increasing NO-system activity, and diminishing collagen content and apoptosis, in both sexes.

Hypertension-induced renal injury is characterized by inflammation, fibrosis and proteinuria. Previous studies have demonstrated that N-acetyl-Ser-Asp-Lys-Pro (Ac-SDKP) inhibits renal damage following diabetes mellitus and antiglomerular basement membrane nephritis. However, its effects on low-renin hypertensive nephropathy are not known. Thus, we hypothesized that Ac-SDKP has renal protective effects on deoxycorticosterone acetate (DOCA)-salt hypertensive mice, decreasing inflammatory cell infiltration, matrix deposition and albuminuria. We uninephrectomized 16-week-old C57BL/6J mice and treated them with either placebo, DCOA (10 mg/10 g body weight subcutaneous) and 1% sodium chloride with 0.2% potassium chloride in drinking water (DOCA-salt) or DOCA-salt with Ac-SDKP (800 μg/kg per day) for 12 weeks. We measured blood pressure, urine albumin, glomerular matrix, renal collagen content, monocyte/macrophage infiltration and glomerular nephrin expression. Treatment with DOCA-salt significantly increased blood pressure (P < 0.01), which remained unaltered by Ac-SDKP. Ac-SDKP decreased DOCA-salt-induced renal collagen deposition, glomerular matrix expansion and monocyte/macrophage infiltration. Moreover, DOCA-salt-induced increase in albuminuria was normalized by Ac-SDKP (controls, 10.8 ± 1.7; DOCA-salt, 41 ± 5; DOCA-salt + Ac-SDKP, 13 ± 3 μg/10 g body weight per 24 h; P < 0.001, DOCA-salt vs. DOCA-salt + Ac-SDKP). Loss of nephrin reportedly causes excess urinary protein excretion; therefore, we determined whether Ac-SDKP inhibits proteinuria by restoring nephrin expression in the glomerulus of hypertensive mice. DOCA-salt significantly downregulated glomerular nephrin expression (controls, 37 ± 8; DOCA-salt, 10 ± 1.5% of glomerular area; P < 0.01), which was partially reversed by Ac-SDKP (23 ± 4.0% of glomerular area; P = 0.065, DOCA-salt vs. DOCA-salt + Ac-SDKP). We concluded that Ac-SDKP prevents hypertension-induced inflammatory cell infiltration, collagen deposition, nephrin downregulation and albuminuria, which could lead to renoprotection in hypertensive mice.

The present study was designed to investigate the effects of angiotensin(1-7) (Ang(1-7)) a Mas receptor agonist, and A-779, a Mas receptor antagonist, in streptozotocin-induced diabetic nephropathy (DN). A single administration of streptozotocin (STZ) (50 mg/kg i.p.) to rats produced diabetes, and diabetic nephropathy developed after 8 weeks of STZ administration. The extent of DN was assessed biochemically and morphologically by measuring serum creatinine, creatinine clearance, blood urea nitrogen (BUN), proteinuria, urinary N-acetyl-beta-D glucosaminadase activity, renal collagen contents, lipid profile, serum nitrite/nitrate concentration and kidney weight/body weight (%). Treatments with Ang(1-7) (576 microg/kg/day i.p. for 4 weeks) and Ang(1-7) plus A-779 (744 microg/kg/day i.p. for 4 weeks) were started after 4 weeks of STZ administration. The treatment with Ang(1-7) attenuated STZ-induced nephropathy in rats by decreasing proteinuria, renal collagen content and by improving endothelial functions without preventing tubular damage. It has been shown for the first time that treatment with Ang(1-7) decreases dyslipidemia and BUN in diabetic rats, implying a renoprotective effect of the peptide. However, serum creatinine, creatinine clearance and kidney weight/body weight (%) remained unaffected with Ang(1-7) treatment. It may be concluded that activation by specific agonists of the Mas receptor may be useful in combating glomerular damage in DN.

N-acetyl-seryl-aspartyl-lysyl-proline (Ac-SDKP) is a naturally occurring peptide of which the plasma concentration is increased 4- to 5-fold by angiotensin-converting enzyme inhibitors. We reported previously that, in models of both hypertension and postmyocardial infarction, Ac-SDKP reduces cardiac inflammation and fibrosis. However, it is unknown whether Ac-SDKP can prevent or reverse renal injury and dysfunction in hypertension. In the present study, we tested the hypothesis that, in rats with 5/6 nephrectomy (5/6Nx)-induced hypertension, Ac-SDKP reduces renal damage, albuminuria, and dysfunction by decreasing inflammatory cell infiltration and renal fibrosis and by increasing nephrin protein. Ac-SDKP (800 microg/kg per day, SC via osmotic minipump) or vehicle was either started 7 days before 5/6Nx (prevention) and continued for 3 weeks or started 3 weeks after 5/6Nx (reversal) and continued for another 3 weeks. Rats with 5/6Nx developed high blood pressure, left ventricular hypertrophy, albuminuria, decreased glomerular filtration rate, and increased macrophage infiltration (inflammation) and renal collagen content (fibrosis). Ac-SDKP did not affect blood pressure or left ventricular hypertrophy in either group; however, it significantly reduced albuminuria, renal inflammation, and fibrosis and improved glomerular filtration rate in both prevention and reversal groups. Moreover, slit diaphragm nephrin protein expression in the glomerular filtration barrier was significantly decreased in hypertensive rats. This effect was partially prevented or reversed by Ac-SDKP. We concluded that Ac-SDKP greatly attenuates albuminuria and renal fibrosis and improves renal function in rats with 5/6Nx. These effects may be related to decreased inflammation (macrophages) and increased nephrin protein.

The objective of the present study was to evaluate the effect of Npr1 (coding for Guanylyl Cyclase‐A/Natriuretic Peptide Receptor‐A; GC‐A/NPRA) gene‐disruption in the development of renal hypertrophy and fibrosis. Blood pressure measurement and plasma cytokine assays were performed in 16‐weeks old mice having different copies of Npr1 gene (0‐copy, 1‐copy and 2‐copy). The 0‐copy mice showed 35‐45 mmHg higher systolic blood pressure (SBP) as compared with 2‐copy mice. A significant increase in plasma levels of tumor necrosis factor (TNF‐α; 5‐fold) and interleukin‐6 (IL‐6; 2.5‐fold) were observed in 0‐copy mice as compared with 2‐copy mice. Moreover, protein analysis also showed a significant increased expression levels of transforming growth factor (TGF‐β) and reduced expression of matrix metalloproteinases (MMP's) by Western blot analysis in 0‐copy mice as compared with 2‐copy wild‐type mice. Renal collagen content was significantly increased by 2‐fold in 0‐copy mice and was confirmed by histological study with masson's trichrome staining of kidney tissues. The increased levels of TNF‐α, IL‐6, and TGF‐β as well as a reduced levels of MMP's in 0‐copy mice indicated the ensuing process of renal fibrosis in these animals. Thus, the present results suggest that the absence of ANP/NPRA signaling exerts a stimulatory effect to cause significant increase in pro‐inflammatory cytokines to produce hypertrophy and fibrosis in the kidney.

There is a correlation between renal graft rejection and blood glucose (BG) levels. Furthermore, diabetic patients may develop non-diabetic renal diseases, which in some circumstances progress rapidly. Since transforming growth factor-beta1 (TGF-beta) levels are elevated in many renal diseases, the accelerated progression may be due to interactions between glucose and locally produced TGF-beta1. Therefore, we investigated the effect of mild hyperglycaemia on glomerular morphology and collagen production in TGF-beta1 transgenic mice. To achieve BG concentrations of approximately 15 mmol/l in TGF-beta1 transgenic and non-transgenic mice, we used multiple streptozotocin (STZ) injections, and after 8 weeks, we measured the changes in glomerular morphology and total collagen content. We also analysed extracellular matrix (ECM) and protease mRNA levels using real-time polymerase chain reaction (PCR) and phosphorylated extracellular signal-regulated kinase 1/2 (pERK) expression by immunohistochemistry. Mild hyperglycaemia alone had no effect on glomerular structure or ECM deposition. Over-expression of TGF-beta1 increased basement membrane thickness (BMT) and the mesangial volume fraction. Furthermore, it augmented ECM, Matrix metalloproteinase-2 (MMP), MMP-9, plasminogen activator inhibitor-1 (PAI) and tissue inhibitor of metalloproteinase-1 (TIMP) gene expression and pERK1/2 immunostaining. Elevated BG in combination with TGF-beta1 resulted in enlargement of glomerular volume, total mesangial volume and renal collagen content. Moreover, high BG exaggerated TGF-beta1-induced changes in the BMT, MMP-2 and TIMP-1 expression and pERK1/2 staining. Even moderate elevations in BG accelerate the progression of those kidney diseases in which TGF-beta1 is involved. This emphasizes the importance of strict BG control in renal transplant patients and diabetic patients with renal malfunctions unrelated to diabetes.

Plasminogen activator inhibitor-1 deficiency protects against aldosterone-induced glomerular injury

Regression of sclerosis in aging by an angiotensin inhibition-induced decrease in PAI-1

Experimental vesicoureteral reflux in the fetus depends on bladder function and causes renal fibrosis.

EXPERIMENTAL VESICOURETERAL REFLUX IN THE FETUS DEPENDS ON BLADDER FUNCTION AND CAUSES RENAL FIBROSIS