Department of Nephrology, The First Affiliated Hospital, Anhui Medical University, No. 218, Jixi Road, Hefei, Anhui, 230032, People's Republic of China.
Int Urol Nephrol. 2021 Jul;53(7):1399-1415. doi: 10.1007/s11255-020-02733-2. Epub 2021 Jan 3.
Bruton's tyrosine kinase (BTK) is a vital biological molecule that contributes to immune regulation. Previous studies have showed that BTK can be detected in patients with lupus nephritis and rheumatoid arthritis. However, the role of BTK in IgA nephropathy (IgAN) has not yet been elucidated. The purpose of this research was to investigate the role of BTK activation in macrophages in IgAN.
Peripheral blood and renal tissue samples were collected from 63 patients with IgAN, and peritumoral normal tissues were collected from 20 patients after surgical resection of renal tumor for use as control. Additionally, 20 healthy volunteers were recruited as control. The levels of BTK, CD68, phosphorylated BTK (pBTK), phosphorylated NF-κB (p-NF-κB p65), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and monocyte chemotactic protein (MCP)-1 were measured by immunohistochemistry (IHC), real-time polymerase chain reaction (RT-PCR), western blotting, and enzyme-linked immunosorbent assay (ELISA).
Compared to peritumoral normal tissues, the expression levels of CD68 and BTK were significantly increased in IgAN group (p < 0.001) and the differences between M0 and M1, E0 and E1, S0 and S1, T0 and T1-2, C0 and C1-2 were statistically significant in the updated Oxford Classification (p < 0.05). Also, CD68 and BTK were positively correlated with Katafuchi semi-quantitative glomerular and tubulointerstitial scores (r = 0.580, 0.637 and 0.442, 0.489, respectively, p < 0.05). The expression of BTK was significantly higher in C3b- and C4d-positive renal tissues of patients with IgAN (p < 0.05). In addition, BTK was positively correlated with 24-h urine protein, serum creatinine levels (r = 0.456 and 0.453, respectively, p < 0.001), and negatively correlated with serum albumin (r = 0.357, p < 0.05). The intensity of expression of pBTK and p-NF-κB p65 was observably increased in renal tissues and monocytes of patients with IgAN compared to the control group. The results of IHC, RT-PCR, and ELISA indicated that the levels of TNF-ɑ, IL-1β, and MCP-1 were markedly increased in the IgAN group (p < 0.05).
The results of this study indicate that activation of BTK in macrophages may play an important role in promoting the progression of renal inflammation in IgAN.
布鲁顿酪氨酸激酶（BTK）是一种重要的生物分子，参与免疫调节。先前的研究表明，BTK 可在狼疮肾炎和类风湿关节炎患者中检测到。然而，BTK 在 IgA 肾病（IgAN）中的作用尚未阐明。本研究旨在探讨 BTK 在 IgAN 中巨噬细胞中的激活作用。
收集 63 例 IgAN 患者的外周血和肾组织样本，收集 20 例肾肿瘤切除术后肿瘤旁正常组织作为对照。此外，招募 20 名健康志愿者作为对照。采用免疫组化（IHC）、实时聚合酶链反应（RT-PCR）、Western blot 和酶联免疫吸附试验（ELISA）检测 BTK、CD68、磷酸化 BTK（pBTK）、磷酸化核因子-κB（p-NF-κB p65）、肿瘤坏死因子（TNF）-α、白细胞介素（IL）-1β和单核细胞趋化蛋白（MCP）-1的水平。
与肿瘤旁正常组织相比，IgAN 组 CD68 和 BTK 的表达水平显著升高（p<0.001），在更新的牛津分类中，M0 与 M1、E0 与 E1、S0 与 S1、T0 与 T1-2、C0 与 C1-2 之间的差异具有统计学意义（p<0.05）。此外，CD68 和 BTK 与 Katafuchi 半定量肾小球和肾小管间质评分呈正相关（r=0.580、0.637 和 0.442、0.489，p<0.05）。BTK 在 IgAN 患者 C3b 和 C4d 阳性肾组织中的表达明显升高（p<0.05）。此外，BTK 与 24 小时尿蛋白、血清肌酐水平呈正相关（r=0.456 和 0.453，p<0.001），与血清白蛋白呈负相关（r=0.357，p<0.05）。与对照组相比，IgAN 患者肾组织和单核细胞中 pBTK 和 p-NF-κB p65 的表达强度明显增加。IHC、RT-PCR 和 ELISA 的结果表明，IgAN 组 TNF-ɑ、IL-1β 和 MCP-1 的水平明显升高（p<0.05）。
本研究结果表明，BTK 在巨噬细胞中的激活可能在促进 IgAN 肾炎症进展中发挥重要作用。
