Meng Qian, Yang Xiaowei, Liu Zhongcheng, You Guoxing, Chen Wanyi, Zhao Bing, Zhu Huizi, Xu Liang, Zhou Yan, Liu Xiang, Zhai Chunjuan, Wang Rong, Zhao Lian, Sun Jing
Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, Shandong, 250021, People's Republic of China.
Department of Cardiovascular, The North City Hospital of Jinan, Jinan, Shandong, 250031, People's Republic of China.
J Inflamm Res. 2024 Oct 9;17:7111-7121. doi: 10.2147/JIR.S467136. eCollection 2024.
Chronic kidney disease (CKD) is associated with persistent systemic inflammation. Reduced red blood cell (RBC) survival in patients with CKD has been identified for several decades. The purpose of this study is to explore whether excessive erythrophagocytosis exists and contributes to systemic inflammation in CKD.
A CKD rat model was induced by 5/6 nephrectomy. Erythrocyte osmotic fragility was determined with hypotonic NaCl solutions. Erythrocyte deformability was evaluated by filterability. RBC cell death was quantified using fluorescence-activated cell sorting analyses of fluorescent annexin V-bound surface phosphatidylserine (PS). Erythrophagocytosis was evaluated in vivo and in vitro. RT-qPCR and immunohistochemistry were used to determine the inflammatory effects after erythrophagocytosis.
Erythrocyte osmotic fragility and deformability progressively declined, and the percentage of PS-exposing RBCs progressively increased in CKD rats. Levels of erythrophagocytosis in vivo were evaluated by autologous injection of CFSE-labeled erythrocytes. In comparison with the control group, higher fluorescence intensity of CFSE was detected in the spleen homogenates of rats with CKD. In vitro, more of erythrocytes from 5/6Nx rats were phagocytosed by peritoneal macrophages in comparison to those from control rats. Compared with macrophages phagocytosed control erythrocytes, macrophages phagocytosed CKD erythrocytes exhibited higher mRNA levels of IL-6, CXCL-10, CXCL-11, iNOS, IL-1β, ICAM-1 and MCP-1. Compared with the control group, the red pulp of rats with CKD exhibited higher levels of p-NFκB, IL-6, iNOS and CXCL-10. ELISA results showed significantly increased plasma levels of both IL-6 and CXCL-10 in patients with long-term hemodialysis compared with those in healthy controls (2.30 ± 1.38 pg/mL vs 1.33 ± 0.65 pg/mL, =0.01; 78.11 ± 27.34 pg/mL vs 37.45 ± 7.08 pg/mL, =0.001).
Our results indicated that excessive erythrophagocytosis may contribute to systemic inflammation in CKD.
慢性肾脏病（CKD）与持续性全身炎症相关。几十年来，人们已认识到CKD患者红细胞（RBC）存活时间缩短。本研究的目的是探讨CKD中是否存在过度红细胞吞噬作用并导致全身炎症。
通过5/6肾切除术建立CKD大鼠模型。用低渗氯化钠溶液测定红细胞渗透脆性。通过滤过性评估红细胞变形性。使用荧光激活细胞分选分析结合荧光膜联蛋白V的表面磷脂酰丝氨酸（PS）对RBC细胞死亡进行定量。在体内和体外评估红细胞吞噬作用。采用RT-qPCR和免疫组化法测定红细胞吞噬后的炎症效应。
CKD大鼠的红细胞渗透脆性和变形性逐渐下降，暴露PS的RBC百分比逐渐增加。通过自体注射CFSE标记的红细胞评估体内红细胞吞噬水平。与对照组相比，CKD大鼠脾脏匀浆中检测到更高的CFSE荧光强度。在体外，与对照组大鼠的红细胞相比，5/6肾切除大鼠的更多红细胞被腹腔巨噬细胞吞噬。与吞噬对照红细胞的巨噬细胞相比，吞噬CKD红细胞的巨噬细胞表现出更高的IL-6、CXCL-10、CXCL-11、iNOS、IL-1β、ICAM-1和MCP-1 mRNA水平。与对照组相比，CKD大鼠的脾髓中p-NFκB、IL-6、iNOS和CXCL-10水平更高。ELISA结果显示，与健康对照组相比，长期血液透析患者血浆中IL-6和CXCL-10水平显著升高（2.30±1.38 pg/mL对1.33±0.65 pg/mL，P = 0.01；78.11±27.34 pg/mL对37.45±7.08 pg/mL，P = 0.001）。
我们的结果表明，过度红细胞吞噬作用可能导致CKD中的全身炎症。
