Identification of a protein expression signature distinguishing early from organising diffuse alveolar damage in COVID-19 patients.

Diffuse alveolar damage (DAD) is a histopathological finding associated with severe viral infections, including SARS-CoV-2. However, the mechanisms mediating progression of DAD are poorly understood. Applying protein digital spatial profiling to lung tissue obtained from a cohort of 27 COVID-19 autopsy cases from the UK, we identified a protein signature (ARG1, CD127, GZMB, IDO1, Ki67, phospho-PRAS40 (T246), and VISTA that distinguishes early / exudative DAD from late / organising DAD with good predictive accuracy. These proteins warrant further investigation as potential immunotherapeutic targets to modulate DAD progression and improve patient outcome.

Integrated miRNA/cytokine/chemokine profiling reveals immunopathological step changes associated with COVID-19 severity

Circulating microRNAs (miRNAs) are exceptional mechanism-based correlates of disease, yet their potential remains largely untapped in COVID-19. Here, we determined circulating miRNA and cytokine and chemokine (CC) profiles in 171 blood plasma samples from 58 hospitalised COVID-19 patients. Thirty-two miRNAs were differentially expressed in severe cases when compared to moderate and mild cases. These miRNAs and their predicted targets reflected key COVID-19 features including cell death and hypoxia. Compared to mild cases, moderate and severe cases were characterised by a global decrease in circulating miRNA levels. Partial least squares regression using miRNA and CC measurements allowed for discrimination of severe cases with greater accuracy (87%) than using miRNA or CC levels alone. Correlation analysis revealed severity group-specific associations between CC and miRNA levels. Importantly, the miRNAs that correlated with IL6 and CXCL10, two cardinal COVID-19-associated cytokines, were distinct between severity groups, providing a novel qualitative way to stratify patients with similar levels of proinflammatory cytokines but different disease severity. Integration of miRNA and CC levels with clinical parameters revealed severity-specific signatures associated with clinical hallmarks of COVID-19. Our study highlights the existence of severity-specific circulating CC/miRNA networks, providing insight into COVID-19 pathogenesis and a novel approach for monitoring COVID-19 progression.