目的·筛选新型冠状病毒感染（coronavirus disease-2019，COVID-19）患者合并肾损伤（kidney injury，KI）的相关标志物，探讨新型冠状病毒蛋白通过影响肾脏细胞与巨噬细胞间相互作用参与肾损伤的相关机制。方法·回顾性分析2022年12月—2023年2月上海交通大学医学院第九人民医院收治的COVID-19合并KI患者的临床特征，采用酶联免疫吸附试验（enzyme linked immunosorbent assay，ELISA）检测血清中的炎症因子和趋化因子水平。体外用严重急性呼吸综合征冠状病毒2（severe acute respiratory syndrome coronavirus-2，SARS-CoV-2）重组刺突蛋白S1亚基刺激人巨噬细胞系THP-1后，收集细胞和培养上清，通过实时荧光定量PCR（quantitative real-time PCR，qRT-PCR）和ELISA检测炎症因子和趋化因子的水平。利用S1蛋白刺激THP-1的细胞培养上清制备条件培养基，体外刺激人肾上皮细胞系HK-2，并检测HK-2细胞分泌细胞因子的能力。采用抗体阻断实验分析条件培养基对HK-2细胞产生细胞因子的影响。结果·在39例COVID-19患者中，有8例（20.50%）血清肌酐水平高于正常参考范围，提示这些患者可能合并KI。ELISA结果显示COVID-19合并KI组患者外周肿瘤坏死因子-α（tumor necrosis factor-α，TNF-α）水平［（18.33±8.20）pg/mL］显著高于未合并KI组［（11.88±6.50）pg/mL］（P=0.015）。体外实验结果显示S1蛋白可以刺激THP-1胞内TNF-α、白细胞介素-1β（interleukin-1β，IL-1β）和C-X-C基序趋化因子配体10（chemokine C-X-C motif ligand 10，CXCL10）基因转录水平上升，同时刺激THP-1高表达TNF-α、IL-1β和CXCL10（P<0.001）。进一步研究发现，利用S1蛋白刺激THP-1的细胞培养上清制备的条件培养基能促进HK-2细胞表达TNF-α（P=0.005）。而采用抗TNF-α抗体（英夫利昔单抗，infliximab）阻断条件培养基中的TNF-α后，HK-2细胞表达TNF-α的水平显著降低（P<0.001）。结论·TNF-α在COVID-19合并KI患者中明显增高，提示TNF-α是COVID-19合并KI的重要炎症因子。细胞学实验证实新冠病毒S1蛋白可以诱导巨噬细胞分泌TNF-α，进而促进肾脏细胞炎症水平的增加，可能是COVID-19合并KI发生的主要原因。因此，靶向TNF-α有望成为降低COVID-19合并KI发生率的潜在新策略。

Objective ·To identify relevant biomarkers for patients with coronavirus disease 2019-associated kidney injury (COVID-19-associated KI) and explore the mechanisms underlying the involvement of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) proteins in infection-related KI by affecting the interactions between renal cells and macrophages. Methods ·A retrospective analysis was conducted on the clinical characteristics of COVID-19 patients with KI treated in Shanghai Ninth, People′s, hospital from December 2022 to February 2023. Serum levels of inflammatory factors and chemokines were measured by using enzyme- linked immunosorbent assay (ELISA). In vitro, human macrophage cell line THP-1 cells were stimulated with recombinant S1 subunit protein derived from SARS-CoV-2 spike protein. The cells and culture supernatants were collected to detect the levels of inflammatory factors and chemokines by using quantitative real-time PCR (qRT-PCR) and ELISA. Conditioned medium was prepared from the cell culture supernatants of S1-stimulated THP-1 cells and used to stimulate human renal epithelial cells (HK-2) in vitro to assess cytokine secretion. Antibody blocking experiments were performed to analyze the effects of the conditioned medium on the production of cytokines in HK-2 cells. Results ·Among 39 patients with COVID-19, 8 (20.50%) had creatinine levels above the reference interval, which indicated the occurrence of KI. The levels of peripheral tumor necrosis factor-α (TNF-α) in the COVID-19 patient with KI group [(18.33±8.20) pg/mL] were significantly higher than those in the non-KI group [(11.88±6.50) pg/mL] (P=0.015). In vitro assay has shown that S1-spike protein stimulation promoted the level of gene transcription and production of TNF-α, interleukin-1β (IL-1β) and chemokine C-X-C motif ligand 10 (CXCL10) in THP-1 macrophage cells (P<0.001). Furthermore, the conditioned medium from S1-stimulated THP-1 cells promoted the secretion of TNF-α, IL-1β and CXCL10 by HK-2 cells (P=0.005). When anti-TNF-α antibody (Infliximab) was used to block TNF-α in the culture supernatants from S1-stimulated THP-1 cells, the secretion level of TNF-α by HK-2 cells decreased dramatically (P<0.001). Conclusion ·TNF-α levels increase significantly in COVID-19 patients with KI, implying the significance of TNF-α in the occurrence of COVID-19-associated KI. In vitro experiments confirm that the S1 protein induces TNF-α secretion from THP-1 cells, leading to increased inflammatory responses in renal cells, which may contribute to the development of COVID-19-associated KI. Therefore, targeting TNF-α may become an alternative strategy to reduce the occurrence of COVID-19-associated KI.