C3a Receptor Antagonist Ameliorates Inflammatory and Fibrotic Signals in Type 2 Diabetic Nephropathy by Suppressing the Activation of TGF-β/smad3 and IKBα Pathway

Abstract

ObjectiveDiabetic nephropathy (DN) is a serious complication for patients with diabetes mellitus (DM). Emerging evidence suggests that complement C3a is involved in the progression of DN. The aim of this study was to investigate the effect of C3a Receptor Agonist (C3aRA) on DN and its potential mechanism of action in rats with type 2 diabetes mellitus (T2DM).MethodsT2DM was induced in SD rats by a high fat diet (HFD) plus repeated low dose streptozocin (STZ) injections. T2DM rats were treated with vehicle or C3aRA for 8 weeks. Biochemical analysis, HE and PAS stains were performed to evaluate the renal function and pathological changes. Human renal glomerular endothelial cells (HRGECs) were cultured and treated with normal glucose (NG), high glucose (HG), HG+C3a, HG+C3a+C3aRA and HG+C3a+BAY-11-7082 (p-IKBα Inhibitor) or SIS3 (Smad3 Inhibitor), respectively. Real-time PCR, immunofluorescent staining and western blot were performed to detect the mRNA and protein levels, respectively.ResultsT2DM rats showed worse renal morphology and impaired renal function compared with control rats, including elevated levels of serum creatinine (CREA), blood urea nitrogen (BUN) and urine albumin excretion (UACR), as well as increased levels of C3a, C3aR, IL-6, p-IKBα, collagen I, TGF-β and p-Smad3 in the kidney of T2DM rats and C3a-treated HRGECs. In contrast, C3aRA treatment improved renal function and morphology, reduced CREA, UACR and the intensity of PAS and collagen I staining in the kidney of T2DM rats, and decreased C3a, p-IKBα, IL-6, TGF-β, p-Smad3 and collagen I expressions in HRGECs and T2DM rats.ConclusionC3a mediated pro-inflammatory and pro-fibrotic responses and aggravated renal injury in T2DM rats. C3aRA ameliorated T2DN by inhibiting IKBα phosphorylation and cytokine release, and also TGF-β/Smad3 signaling and ECM deposition. Therefore, complement C3a receptor is a potential therapeutic target for DN.

Protective effect ofL-glutamine against diabetes-induced nephropathy in experimental animal: Role of KIM-1, NGAL, TGF-β1, and collagen-1

“…66 Moreover, extracellular membrane (ECM) protein activation and matrix degradation subdue is correlated with TGF-b-induced fibrogenesis. 67,68 Interestingly, TGF-b signal transduction is greatly connected with the Smads. 67,68 TGF-b on binding with two specific type I and type II serine/threonine kinase receptor convey its signal across the plasma membrane.…”

“…67,68 Interestingly, TGF-b signal transduction is greatly connected with the Smads. 67,68 TGF-b on binding with two specific type I and type II serine/threonine kinase receptor convey its signal across the plasma membrane. Clinical study also showed elevated serum and urinary TGF-b1 level in DN patients.…”

Exendin-4 Ameliorates Lipotoxicity-induced Glomerular Endothelial Cell Injury by Improving ABC Transporter A1-mediated Cholesterol Efflux in Diabetic apoE Knockout Mice

“…The tissue sections were analyzed with a Nikon A1Si confocal laser scanning microscope and NIS-Elements Advanced Research software, version 4.0 (Nikon, Tokyo), and S Plan Fluor ELWD 40ϫ DIC. The subsequent steps were carried out as described previously (64).…”

“…After confirming the RNA quality by agar gel electrophoresis, cDNA was synthesized. Real-time PCR was performed with the CFX96 TM real-time PCR detection system (Bio-Rad) using SYBR Premix Ex Taq TM (Tli RNase H Plus, Takara) as described previously (64). The gene encoding ␤-actin was used as an internal standard.…”

Protective effects of leflunomide on renal lesions in a rat model if diabetic nephropathy

“…TGFb1 is considered one of the most potent factors inducing glomerulosclerosis in the DN. 23,24 Clinical study showed that serum and urinary TGF-b1 was an important biochemical markers in DN patients. 25 It plays important role in the development of renal interstitial fibrosis mainly through the classical TGF-b1/Smads pathway-mediated renal tubular epithelial cell transdifferentiation.…”