Human kidney spheroids and monolayers provide insights into sars-cov-2 renal interactions

Abstract

Background Although coronavirus disease 2019 (COVID-19) causes significan t morbidity, mainly from pulmonary involvement, extrapulmonary symptoms are alsomajor componen ts of the disease. Kidney disease, usually presenting as AKI, is particularly severe among patients with COVID-19. It is unknown, however, whether such injury results from direct kidney infection with COVID-19's causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or from indirect mechanisms. Methods Using ex vivo cellmodels,we sought to analyze SARS-CoV-2 interactionswith kidney tubular cells and assessdirect tubular injury.Thesemodels comprisedprimaryhumankidneyepithelial cells (derivedfromnephrectomies) and grown as either proliferating monolayers or quiescent three-dimensional kidney spheroids. Results We demonstrated that viral entrymolecules and high baseline levels of type 1 IFN-relatedmolecules were present inmonolayers and kidney spheroids. Although bothmodels support viral infection and replication, they did not exhibit a cytopathic effect and cell death, outcomes that were strongly present in SARSCoV- 2-infected controls (African green monkey kidney clone E6 [Vero E6] cultures). A comparison of monolayer and spheroid cultures demonstrated higher infectivity and replication of SARS-CoV-2 in actively proliferatingmonolayers, although the spheroid cultures exhibited high er levels ofACE2.Monolayers exhibited elevation of some tubular injurymolecules-includingmolecules related to fibrosis (COL1A1 and STAT6) and dedifferentiation (SNAI2)-and a loss of cell identity, evident by reduction in megalin (LRP2). The threedimensional spheroids were less prone to such injury. Conclusions SARS-CoV-2 can infect kidney cells without a cytopathic effect. AKI-induced cellular proliferation may potentially intensify infectivity and tubular damage by SARS-CoV-2, suggesting that early intervention in AKI is warranted to help minimize kidney infection.