Department of Respiratory and Critical Care Medicine, Key Cite of National Clinical Research Center for Respiratory Disease, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410008, China.
Department of Nephrology, Xiangya Hospital, Central South University, 87 Xiangya Road, Changsha, 410008, China.
J Nephrol. 2020 Oct;33(5):1027-1036. doi: 10.1007/s40620-020-00708-1. Epub 2020 Feb 8.
CD4 T cells are involved in the pathogenesis of immunoglobulin A nephropathy (IgAN); T helper (Th) 1, Th17 and Th22 cells promote the occurrence and amplification of inflammatory reactions, while regulatory T (Treg) cells produce the opposite effects. However, whether Th9 cells, a subset of CD4 T cells, participate in IgAN development is still unknown.
Human peripheral blood mononuclear cells (PBMCs) were isolated from IgAN patients for Th9 cells detection by flow cytometry. Wild-type (WT) mouse was used to establish an IgAN mouse model while C3aR and C5aR inhibitor treated IgAN mouse. Kidney disease and function was assessed by histology and albumin-to-creatinine ratio. C3aR and C5aR expression was examined by immunohistochemical (IHC) assay. Th9 cell proportions in the blood of IgAN mouse was detected. C3a, C5a and interleukin (IL)-9 levels were tested by ELISA. Moreover, co-culture system between human mesangial cells (HMCs) and CD4 T cells were constructed with or without C3a, C5a and anti-CCL20 mAb stimulation for transwell assay to examine Th9 cell chemotaxis.
We observed the numbers of Th9 cell and the levels of IL-9 were increased in IgAN patients and IgAN mice. Furthermore, C3a and C5a level in serum and kidney, C3aR and C5aR expression was increased in IgAN mice compared to WT mice. Most interestingly, C3aR and C5aR inhibitor could reduce kidney damage, Th9 cell numbers and IL-9 levels. We also observed that C3a and C5a enhanced CCL20 production in HMCs. Notably, C3a and C5a also increased the recruitment of Th9 cells and IL-9 levels by HMCs through enhancing the CCL20-CCR6 pathway.
Our results support that C3a and C5a increase the production of CCL20 by HMCs and consequently augment Th9 cell recruitment and IL-9 levels, resulting in IgAN exacerbation.
CD4 T 细胞参与免疫球蛋白 A 肾病（IgAN）的发病机制；辅助性 T（Th）1、Th17 和 Th22 细胞促进炎症反应的发生和放大，而调节性 T（Treg）细胞则产生相反的效果。然而，CD4 T 细胞亚群 Th9 细胞是否参与 IgAN 的发生尚不清楚。
通过流式细胞术从 IgAN 患者中分离外周血单核细胞（PBMC）以检测 Th9 细胞。使用野生型（WT）小鼠建立 IgAN 小鼠模型，并使用 C3aR 和 C5aR 抑制剂处理 IgAN 小鼠。通过组织学和白蛋白/肌酐比评估肾脏疾病和功能。通过免疫组化（IHC）检测 C3aR 和 C5aR 的表达。检测 IgAN 小鼠血液中 Th9 细胞的比例。通过 ELISA 检测 C3a、C5a 和白细胞介素（IL）-9 水平。此外，构建了人肾小球系膜细胞（HMC）与 CD4 T 细胞的共培养体系，并在 C3a、C5a 和抗 CCL20 mAb 刺激下进行 Transwell 实验，以检测 Th9 细胞趋化性。
我们观察到 IgAN 患者和 IgAN 小鼠中 Th9 细胞数量和 IL-9 水平增加。此外，与 WT 小鼠相比，IgAN 小鼠血清和肾脏中的 C3a 和 C5a 水平以及 C3aR 和 C5aR 的表达增加。最有趣的是，C3aR 和 C5aR 抑制剂可减少肾脏损伤、Th9 细胞数量和 IL-9 水平。我们还观察到 C3a 和 C5a 增强了 HMCs 中 CCL20 的产生。值得注意的是，C3a 和 C5a 还通过增强 CCL20-CCR6 途径增加了 HMCs 募集 Th9 细胞和产生 IL-9 的水平，导致 IgAN 加重。
我们的研究结果支持 C3a 和 C5a 通过增加 HMCs 中 CCL20 的产生，进而增加 Th9 细胞的募集和 IL-9 水平，导致 IgAN 恶化。
