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Background: Classification of nephrotic syndrome relies on clinical presentation and descriptive patterns of injury on kidney biopsies. This approach does not reflect underlying disease biology, limiting the ability to predict progression or treatment response. Methods: Systems biology approaches were used to categorize patients with minimal change disease (MCD) and focal segmental glomerulosclerosis (FSGS) based on kidney biopsy tissue transcriptomics across three cohorts and assessed association with clinical outcomes. Patient- level tissue pathway activation scores were generated using differential gene expression. Then, functional enrichment and non-invasive urine biomarker candidates were identified. Biomarkers were validated in kidney organoid models and single nucleus RNA-seq (snRNAseq) from kidney biopsies. Results: Transcriptome-based categorization identified three subgroups of patients with shared molecular signatures across independent North American, European and African cohorts. One subgroup demonstrated worse longterm outcomes (HR 5.2, p = 0.001) which persisted after adjusting for diagnosis and clinical measures (HR 3.8, p = 0.035) at time of biopsy. The molecular profile of this subgroup was largely (48%) driven by tissue necrosis factor (TNF) activation and could be predicted based on levels of TNF pathway urinary biomarkers TIMP-1 and MCP-1 and clinical features (correlation 0.63, p <0.001 for predicted vs observed score). Kidney organoids confirmed TNF-dependent increase in transcript and protein levels of these markers in kidney cells, as did snRNAseq from NEPTUNE biopsy samples. Conclusions: Molecular profiling identified a patient subgroup within nephrotic syndrome with poor outcome and kidney TNF pathway activation. Clinical trials using non-invasive biomarkers of pathway activation to target therapies are currently being evaluated.

SARS-CoV-2 is a newly emerged beta-coronavirus that enter cells via two routes, direct fusion at the plasma membrane or endocytosis followed by fusion with the late endosome/lysosome. While the viral receptor, ACE2, multiple entry factors, and the mechanism of fusion of the virus at the plasma membrane have been extensively investigated, viral entry via the endocytic pathway is less understood. By using a human hepatocarcinoma cell line, Huh-7, which is resistant to the antiviral action of the TMPRSS2 inhibitor camostat, we discovered that SARS-CoV-2 entry is not dependent on dynasore but dependent on cholesterol. ADP-ribosylation factor 6 (ARF6) has been described as a host factor for SARS-CoV2 replication and it is involved in the entry and infection of several pathogenic viruses. By CRISPR-Cas9 genetic deletion, we found that ARF6 is important for SARS-CoV-2 uptake and infection in Huh-7. In addition, the ARF6 inhibitor NAV-2729, and the ARF6 agonist AA147, showed a dose-responsive inhibition or enhancement of viral infection, respectively. Importantly, ARF6 inhibition reduced SARS-CoV-2 viral loads also in more physiologic models of infection: Calu-3 and kidney organoids, suggesting a role also in post-entry steps. Together, these experiments points to a ARF6 as a putative target to develop antiviral strategies against SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged beta-coronavirus that enter cells via two routes, direct fusion at the plasma membrane or endocytosis followed by fusion with the late endosome/lysosome. While the viral receptor, ACE2, multiple entry factors and the mechanism of fusion of the virus at the plasma membrane have been investigated extensively, viral entry via the endocytic pathway is less understood. By using a human hepatocarcinoma cell line, Huh-7, which is resistant to the antiviral action of the TMPRSS2 inhibitor camostat, we discovered that SARS-CoV-2 entry is not dependent on dynamin but on cholesterol. ADP-ribosylation factor 6 (ARF6) has been described as a host factor for SARS-CoV-2 replication and is involved in the entry and infection of several pathogenic viruses. Using CRISPR/Cas9 genetic deletion, a modest reduction in SARS-CoV-2 uptake and infection in Huh-7 was observed. In addition, pharmacological inhibition of ARF6 with the small molecule NAV-2729 showed a dose-dependent reduction of viral infection. Importantly, NAV-2729 also reduced SARS-CoV-2 viral loads in more physiological models of infection: Calu-3 cells and kidney organoids. This highlighted a role for ARF6 in multiple cell contexts. Together, these experiments point to ARF6 as a putative target to develop antiviral strategies against SARS-CoV-2.

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