C3a-C3a受体在常染色体显性多囊肾病进展中的作用及机制

目的旨在探讨C3a-C3a受体(C3aR)在常染色体显性多囊肾病(ADPKD)进展中的作用及机制。方法收集ADPKD患者切除肾组织和PKD1敲除小鼠多囊肾组织,观察C3a、C3aR及F4/80在肾组织中的表达;利用脂多糖(LPS)和白细胞介素4(IL-4)分别刺激巨噬细胞,检测各组细胞C3aR、TNF-α、分型标志物和相关信号通路的表达及机制;使用C3aR抑制剂SB290157(1 mg/kg)处理PKD1敲除小鼠,观察肾脏病理、囊肿相关指标和肾功能变化。结果C3a及C3aR在ADPKD患者和PKD1敲除小鼠肾组织中表达显著上调(均P<0.05),C3aR与F4/80共定位于小鼠多囊肾组织中的巨噬细胞上。体外培养M1型巨噬细胞C3aR表达显著上调(P<0.05),C3a刺激后M1型巨噬细胞表达iNOS、TNF-α和IL-6 mRNA显著上调(均P<0.05),分泌TNF-α增多,说明C3a不仅影响M1型巨噬细胞自身炎性因子表达,还影响其周围炎症微环境;此外,C3a激活M1型巨噬细胞Akt信号通路显著上调(P<0.05)。与模型对照组比较,SB290157治疗组小鼠血Scr、BUN水平、囊肿指数、双肾重/体重(2KW/BW)均显著降低(均P<0.05),小鼠肾组织中C3a、C3aR水平及p-ERK、p-P65通路蛋白表达显著下调(均P<0.05)。结论多囊肾组织中增多的C3a通过C3aR引起巨噬细胞浸润和活化,进而促进ADPKD进展,其机制可能通过Akt活化、TNF-α产生增多所致。C3aR拮抗剂是治疗ADPKD的一个潜在研究方向。

Role and mechanism of C3a-C3a receptor in autosomal dominant polycystic kidney disease

Objective To explore the role and mechanism of C3a-C3a receptor (C3aR) in the progression of autosomal dominant polycystic kidney disease (ADPKD). Methods Renal tissues of ADPKD patients and PKD1 knockout mice were collected. Then the expression of C3a-C3aR, Ki67 and F4/80 in renal tissues was observed. Macrophages were stimulated with lipopolysaccharide (LPS) and interleukin 4 respectively. The expression of C3aR, TNF-α, typing markers and related signal pathway proteins was detected in each group. PKD1 knockout mice were treated with C3aR inhibitor SB290157 (1 mg/kg). Renal pathology, cyst-related indicators and renal function were observed. Results The expression of C3a and C3aR in ADPKD was up-regulated (both P＜0.05); C3aR and F4/80 were co-located in the kidney of polycystic kidney disease (PKD) mice, indicating that C3aR was mainly expressed on membrane of macrophages. In vitro, the expression of C3aR was up-regulated in M1 macrophages (P＜0.05). After the stimulation of C3a, the expression of iNOS, TNF-α and IL-6 mRNA in M1 macrophages were up-regulated (all P＜0.05), as well as the secretion of TNF-α, indicating that C3a not only affected the expression of inflammatory factors of M1 macrophages, but also affected the inflammatory microenvironment. In addition, C3a significantly activated Akt in M1 macrophages (P＜0.05). Compared with the control group, the treatment group showed a decrease in C3a-C3aR as well as serum BUN, Scr, cyst index, and two kidneys weight/body weight (2KW/BW) (all P＜0.05), and ADPKD related pathway protein expression such as p-ERK and p-P65 was significantly down-regulated (all P＜0.05). Conclusions The increased C3a in polycystic kidney tissue causes infiltration and activation of macrophages through C3aR, and then promotes ADPKD progression. The mechanism may be mediated by Akt activation and increased TNF-α production. C3aR antagonist is a potential research direction in the treatment of ADPKD.