Dipeptidyl peptidase (DPP) IV inhibitors are probably beneficial for preventing diabetic complication and modulating glucagonlike peptide-1 receptor (GLP-1R) expression. The aim of this study was to determine whether the DPP IV inhibitor LAF237 (vildagliptin) has renoprotective qualities in streptozotocin-induced diabetic rats. Diabetic and nondiabetic rats were treated with an oral dose of 4 or 8 mg/kg/day LAF237 or placebo for 24 weeks, and renal injury was observed by light and electron microscopy. We also assessed DPP IV activity, active GLP-1 level, cAMP and 8-hydroxy-deoxyguanosine excretion, and GLP-1R, cleaved caspase 3, and transforming growth factor-␤1 (TGF-␤1) expression. LAF237 significantly decreased proteinuria, albuminuria, and urinary albumin/creatinine ratio, improved creatinine clearance, and dose-dependently inhibited interstitial expansion, glomerulosclerosis, and the thickening of the glomerular basement membrane in diabetic rats. It is noteworthy that LAF237 markedly down-regulated DPP IV activity and increased active GLP-1 levels, which probably prevented oxidative DNA damage and renal cell apoptosis by activating the GLP-1R and modulating cAMP. Renoprotection was also associated with a reduction in TGF-␤1 overexpression. Our study suggests that DPP IV inhibitors may ameliorate diabetic nephropathy as well as reduce the overproduction of TGF-␤1. The observed renoprotection is probably attributable to inhibition of DPP IV activity, mimicking of incretin action, and activation of the GLP-1R.

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Background Chronic kidney disease (CKD) is an increasing public health issue. Anemia, which is a complication of CKD, is associated with reduced quality of life and increased morbidity and mortality. Currently quite a few clinical studies have been conducted to compare roxadustat with epoetin alfa [all for dialysis-dependent (DD) patients] or placebo [all for nondialysis-dependent (NDD) patients]. Our meta-analysis aimed to investigate the efficacy and safety of roxadustat for anemia in patients with CKD. Methods We thoroughly searched eight electronic resource databases for randomized controlled trials (RCTs) comparing the efficacy and safety between roxadustat versus epoetin alfa or placebo for the treatment of anemia in patients with CKD. Results Four Phase 2 and two Phase 3 studies with 1010 participants were included. Hemoglobin (Hb) and transferrin levels were increased significantly in the roxadustat group versus those in the placebo {standard mean difference [SMD] 1.57 [95% confidence interval (CI) 1.17–1.98]; SMD 1.81 [95% CI 1.53–2.08]; respectively, both low-quality evidence} or epoetin alfa group [SMD 0.47 (95% CI 0.02–0.93), very low-quality evidence; SMD 1.05 (95% CI 0.81–1.29), low-quality evidence; respectively]. Hepcidin levels were reduced significantly in the roxadustat group versus those in the placebo [SMD −1.72 (95% CI −3.03 to −0.41), very low-quality evidence] or epoetin alfa group [SMD −0.23 (95% CI −0.43 to −0.02), low-quality evidence]. Ferritin and serum transferrin saturation (TSAT) levels were reduced significantly in the roxadustat group versus those in the placebo group [SMD −0.82 (95% CI −1.31 to −0.33); SMD −0.54 (95% CI −0.76 to −0.32), respectively; both low-quality evidence] and ferritin and TSAT levels in the roxadustat group were comparable to those in the epoetin alfa group [SMD 0.02 (95% CI −0.18–0.21); SMD 0.15 (95% CI −0.04–0.35), respectively, both low-quality evidence]. As for safety, the incidence of adverse events (AEs) in the roxadustat group was insignificantly different from that of the placebo group [risk ratio (RR) 0.99 (95% CI 0.83–1.18); P = 0.89, very low-quality evidence]. But the incidence of AEs in the roxadustat group was significantly higher than that in the epoetin alfa group [RR 1.25 (95% CI 1.01–1.54); P = 0.04, low-quality evidence]. There was no significant association between roxadustat and the incidence of serious AEs (SAEs) for both NDD and DD patients [RR 1.08 (95% CI 0.51–2.28) and RR 1.43 (95% CI 0.85–2.40), respectively, both very low-quality evidence]. Conclusion In this meta-analysis of RCTs, we found evidence that after the oral administration of roxadustat, NDD patients’ Hb levels were increased effectively and DD patients’ Hb levels were maintained effectively. The risk of SAEs was not observed with the short-term use of roxadustat. These findings support roxadustat for the treatment of anemia in patients with CKD.

Hypertensive renal injury is a primary etiology of end-stage renal disease, and satisfactory therapeutic strategies are urgently required. Cordyceps cicadae, a traditional Chinese herb, has potential renoprotective benefits and is widely used in the treatment of many kidney diseases. To investigate the mechanisms underlying the renoprotective effect of C. cicadae on hypertensive renal injury, we studied the effect of C. cicadae on tubular epithelial cells (TECs) in a spontaneously hypertensive rat (SHR) model and angiotensin II- (AngII-) cultured primary TECs. Our study showed that C. cicadae treatment could decrease 24-hour urine albumin, albumin-to-creatinine ratio (ACR), β2-MG level, and kidney injury molecule-1 (kim-1) level in SHR urine, alleviate interstitial fibrosis, and reduce α-smooth muscle actin (α-SMA) expression in SHR kidney. In primary TECs, medicated serum containing C. cicadae (CSM) might significantly reduce the AngII-induced production of kim-1 and neutrophil gelatinase-associated lipocalin (NGAL). Furthermore, C. cicadae treatment could decrease TEC apoptosis in SHRs as assessed by the terminal transferase-mediated biotin dUTP nick-end labeling (TUNEL) assay. CSM could inhibit caspase-3 activity and enhance cellular viability as measured by methyl thiazolyl tetrazolium in AngII-cultured TECs, suggesting that CSM might reduce the apoptosis level in TECs induced by AngII. We found that the SIRT1 expression level was markedly lowered, while the protein level of acetylated-p53 was elevated in the TECs of patients with hypertensive renal injury and SHRs. C. cicadae presented the effect of regulating the SIRT1/p53 pathway. Further SIRT1 inhibition with EX527 reversed the effect of C. cicadae on AngII-induced apoptosis. Taken together, our results indicate that C. cicadae offers a protective effect on TECs under hypertensive conditions, which may be related to its antiapoptotic effect through regulation of the SIRT1/p53 pathway.

The hypoalbuminuric effect of sulodexide (SDX) on diabetic kidney disease (DKD) was suggested by some clinical trials but was denied by the Collaborative Study Group. In this study, the diabetic rats were treated with SDX either from week 0 to 24 or from week 13 to 24. We found that 24-week treatment significantly decreased the urinary protein and HAVCR1 excretion, inhibited the interstitial expansion, and downregulated the renal cell apoptosis and interstitial fibrosis. Renoprotection was also associated with a reduction in renocortical/urinary oxidative activity and the normalization of renal klotho expression. However, all of these actions were not observed when SDX was administered only at the late stage of diabetic nephropathy (from week 13 to 24). In vitro, advanced glycation end products (AGEs) dose-dependently enhanced the oxidative activity but lowered the klotho expression in cultured proximal tubule epithelial cells (PTECs). Also, H2O2 could downregulate the expression of klotho in a dose-dependent manner. However, overexpression of klotho reduced the HAVCR1 production and the cellular apoptosis level induced by AGEs or H2O2. Our study suggests that SDX may prevent the progression of DKD at the early stage by upregulating renal klotho expression, which inhibits the tubulointerstitial injury induced by oxidative stress.

Hypertensive renal injury is a complication of hypertension. Cordyceps cicadae (C. cicadae) is a traditional Chinese medicine used to treat chronic kidney diseases especially renal fibrosis. Autophagy is described as a cell self-renewal process that requires lysosomal degradation and is utilized for the maintenance of cellular energy homeostasis. The present study explores the mechanism underlying C. cicadae’s renoprotection on hypertensive nephropathy (HN). First, HN rat models were established on spontaneously hypertensive rats (SHRs). The expression of fibrosis-related protein and autophagy-associated protein was detected in vivo. NRK-52E cells exposed to AngII were chosen to observe the potential health benefits of C. cicadae on renal damage. The level of extracellular matrix accumulation was detected using capillary electrophoresis immunoquantification and immunohistochemistry. After treatment with lysosomal inhibitors (chloroquine) or an autophagy activator (rapamycin), the expression of Beclin-1, LC3II, and SQSTM1/p62 was further investigated. The study also investigated the change in sirtuin1 (SIRT1), fork head box O3a (FOXO3a), and peroxidation (superoxide dismutase (SOD) and malondialdehyde (MDA)) expression when intervened by resveratrol. The changes in SIRT1 and FOXO3a were measured in patients and the SHRs. Here, we observed that C. cicadae significantly decreased damage to renal tubular epithelial cells and TGFβ1, α-smooth muscle actin (α-SMA), collagen I (Col-1), and fibronectin expression. Meanwhile, autophagy defects were observed both in vivo and in vitro. C. cicadae intervention significantly downregulated Beclin-1 and LC3II and decreased SQSTM1/p62, showing an inhibition of autophagic vesicles and the alleviation of autophagy stress. These functions were suppressed by rapamycin, and the results were just as effective as the resveratrol treatment. HN patients and the SHRs exhibited decreased levels of SIRT1 and FOXO3a. We also observed a positive correlation between SIRT1/FOXO3a and antifibrotic effects. Similar to the resveratrol group, the expression of SIRT1/FOXO3a and oxidative stress were elevated by C. cicadae in vivo. Taken together, our findings show that C. cicadae ameliorates tubulointerstitial fibrosis and delays HN progression. Renoprotection was likely attributable to the regulation of autophagic stress mediated by the SIRT1 pathway and achieved by regulating FOXO3a and oxidative stress.

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