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.

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.