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The kidney tropism of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) has been well‐validated clinically and often leads to various forms of renal damage in coronavirus disease‐2019 (COVID‐19) patients. However, the underlying mechanisms and diagnostic approaches remain to be determined. We interrogated the expression of virus‐related host factors in single‐cell RNA sequencing (scRNA‐seq) datasets of normal human kidneys and kidneys with pre‐existing diseases and validated the results with urinary proteomics of COVID‐19 patients and healthy individuals. We also assessed the effects of genetic variants on kidney susceptibility using expression quantitative trait loci (eQTLs) databases. We identified a subtype of tubular cells, which we named PT‐3 cells, as being vulnerable to SARS‐CoV‐2 infections in the kidneys. PT‐3 cells were enriched in viral entry factors and replication and assembly machinery but lacked antiviral restriction factors. Immunohistochemistry confirmed positive staining of PT‐3 cell marker SCL36A2 on kidney sections from COVID‐19 patients. Urinary proteomic analyses of COVID‐19 patients revealed that markers of PT‐3 cells were significantly increased, along with elevated viral receptor angiotensin‐converting enzyme 2. We further found that the proportion of PT‐3 cells increased in diabetic nephropathy but decreased in kidney allografts and lupus nephropathy, suggesting that kidney susceptibility varied among these diseases. We finally identified several eQTLs that regulate the expression of host factors in kidney cells. PT‐3 cells may represent a key determinant for the kidney tropism of SARS‐CoV‐2, and detection of PT‐3 cells may be used to assess the risk of renal infection during COVID‐19., Through single‐cell analysis, we identified PT‐3 cells, a proximal tubule epithelial cell subtype in human kidney, that are highly susceptible to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection. We validated these results using immunostaining and urinary proteomics in coronavirus disease‐2019 (COVID‐19) patients. Our findings provide not only new insights into the mechanism involving SARS‐CoV‐2 infection of the kidney cells, but also a potential strategy for risk assessment of kidney infection among COVID‐19 patients.

Clear cell sarcoma of the kidney (CCSK) is a rare paediatric renal malignant tumour. The majority of CCSKs have internal tandem duplications (ITDs) of the BCOR gene, whereas a minority have the YWHAE-NUTM2 gene fusion. A third 'double-negative' (DN) category comprises CCSKs with neither BCOR ITDs nor YWHAE-NUTM2 fusion. The aim of this study was to characterise 11 histologically diagnosed CCSKs immunohistochemically (with CCND1, BCOR and CCNB3 stains) and genetically.By next-generation sequencing, 10 cases (90.9%) had BCOR exon 15 ITDs, with positive BCOR immunoreactivity being found in four (36%) or eight (72%) cases, depending on the antibody clone. By reverse transcription polymerase chain reaction, none had the YWHAE-NUTM2 fusion. The DN case had a BCOR-CCNB3 fusion and strong nuclear CCNB3 and BCOR immunoreactivity. Quantitative polymerase chain reaction showed markedly elevated BCOR expression in this case, whereas BCOR ITD cases had lower levels of elevated BCOR expression.The majority of the CCSKs in our cohort had BCOR ITDs, and none had the YWHAE-NUTM2 fusion. We verified the strong, diffuse cyclin D1 (CCND1) immunoreactivity in CCSKs described in recent reports. BCOR immunoreactivity was not consistently positive in all CCSKs with BCOR ITDs, and therefore cannot be used as a diagnostic immunohistochemical stain to identify BCOR ITD cases. The DN case was a BCOR-CCNB3 fusion sarcoma. BCOR-CCNB3 sarcoma is typically a primary bone sarcoma affecting male adolescents, and this is the first report of it presenting in a kidney of a young child as a CCSK. The full spectrum of DN CCSKs awaits more comprehensive characterisation.

Traditional Chinese medicine has been used for the treatment of many diseases including acute infections often associated with public health emergencies for thousands of years. However, clinical evidence supporting the use of these treatments is insufficient, and the mechanism for using Chinese medicine therapy in the public health setting has not been fully established. In this report, the Evidence-based Traditional and Integrative Chinese medicine Responding to Public Health Emergencies Working Group proposed five recommendations to facilitate the inclusion of Chinese medicine as part of our responses to public health emergencies. It is expected that the Working Group’s proposals may promote the investigation and practice of Chinese Medicine in public health settings.