Upregulation of PD-L1 by SARS-CoV-2 promotes immune evasion.

Patients with severe COVID-19 often suffer from lymphopenia, which is linked to T-cell sequestration, cytokine storm, and mortality. However, it remains largely unknown how severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) induces lymphopenia. Here, we studied the transcriptomic profile and epigenomic alterations involved in cytokine production by SARS-CoV-2-infected cells. We adopted a reverse time-order gene coexpression network approach to analyze time-series RNA-sequencing data, revealing epigenetic modifications at the late stage of viral egress. Furthermore, we identified SARS-CoV-2-activated nuclear factor-κB (NF-κB) and interferon regulatory factor 1 (IRF1) pathways contributing to viral infection and COVID-19 severity through epigenetic analysis of H3K4me3 chromatin immunoprecipitation sequencing. Cross-referencing our transcriptomic and epigenomic data sets revealed that coupling NF-κB and IRF1 pathways mediate programmed death ligand-1 (PD-L1) immunosuppressive programs. Interestingly, we observed higher PD-L1 expression in Omicron-infected cells than SARS-CoV-2 infected cells. Blocking PD-L1 at an early stage of virally-infected AAV-hACE2 mice significantly recovered lymphocyte counts and lowered inflammatory cytokine levels. Our findings indicate that targeting the SARS-CoV-2-mediated NF-κB and IRF1-PD-L1 axis may represent an alternative strategy to reduce COVID-19 severity.

Inhibition of angiogenesis of LCI-D20 hepatocellular carcinoma by metronomic chemotherapy of S-1 / 中华肝脏病杂志

<p><b>OBJECTIVE</b>To investigate the role of metronomic chemotherapy of S-1 on angiogenesis of hepatocellular carcinoma in animal model.</p><p><b>METHOD</b>S-1 was dissolved in a 0.5% (w/v) HPMC solution. 30 LCI-D20 were randomly devided into five groups: control group(O), 10 mg * kg(-1) * d(-1) S-1 group (A), 1 mg * kg(-1) * d(-1) S-1 group (B), 0.5 mg * kg(-1) * d(-1) S-1 group (C) and 0.25 mg * kg(-1) * d S-1 group (D). 28 days after the treatment with 0.5% (w/v) HPMC solution, tumors in LCI-D20 mice were moved out. Tumor mass was measured and microvessel density (MVD) was used to evaluate angiogenesis in tumor. The cellular apoptosis was determined using flow cytometry. The expression of VEGF, bFGF and TSP-1 was measured by RT-PCR.</p><p><b>RESULTS</b>The mean tumor mass was 2.01, 0.38, 1.12, 1.38, 2.27 g in O, A, B, C, D group, respectively. The mean MVD was 39.57, 19.90, 5.93, 17.10, 29.53 in O, A, B, C, D respectively. The mean tumor cellular apoptosis rate was 4.08%, 44.37%, 31.73%, 19.83%, and 8.25% in O, A, B, C, D respectively. The expression of VEGF and bFGF in O group was highest, and A was slightly low, and C and D taked the third place, and B was the lowst; The expression of TSP-1 in B was highest, and C and D were slightly low, and A taked the third place, and O was the lowst.</p><p><b>CONCLUSION</b>Metronomic chemotherapy of S-1 destabilizes pre-existing tumor vasculature and inhibits ongoing angiogenesis.</p>