PD-1highCXCR5-CD4+ peripheral helper T cells promote CXCR3+ plasmablasts in human acute viral infection.

T cell-B cell interaction is the key immune response to protect the host from severe viral infection. However, how T cells support B cells to exert protective humoral immunity in humans is not well understood. Here, we use COVID-19 as a model of acute viral infections and analyze CD4+ T cell subsets associated with plasmablast expansion and clinical outcome. Peripheral helper T cells (Tph cells; denoted as PD-1highCXCR5-CD4+ T cells) are significantly increased, as are plasmablasts. Tph cells exhibit "B cell help" signatures and induce plasmablast differentiation in vitro. Interestingly, expanded plasmablasts show increased CXCR3 expression, which is positively correlated with higher frequency of activated Tph cells and better clinical outcome. Mechanistically, Tph cells help B cell differentiation and produce more interferon γ (IFNγ), which induces CXCR3 expression on plasmablasts. These results elucidate a role for Tph cells in regulating protective B cell response during acute viral infection.

Single-cell multi-omics reveals dyssynchrony of the innate and adaptive immune system in progressive COVID-19.

Dysregulated immune responses against the SARS-CoV-2 virus are instrumental in severe COVID-19. However, the immune signatures associated with immunopathology are poorly understood. Here we use multi-omics single-cell analysis to probe the dynamic immune responses in hospitalized patients with stable or progressive course of COVID-19, explore V(D)J repertoires, and assess the cellular effects of tocilizumab. Coordinated profiling of gene expression and cell lineage protein markers shows that S100Ahi/HLA-DRlo classical monocytes and activated LAG-3hi T cells are hallmarks of progressive disease and highlights the abnormal MHC-II/LAG-3 interaction on myeloid and T cells, respectively. We also find skewed T cell receptor repertories in expanded effector CD8+ clones, unmutated IGHG+ B cell clones, and mutated B cell clones with stable somatic hypermutation frequency over time. In conclusion, our in-depth immune profiling reveals dyssynchrony of the innate and adaptive immune interaction in progressive COVID-19.

Worsening physical functioning in patients with neuroinflammatory disease during the COVID-19 pandemic.

OBJECTIVE: To quantify changes in psychological wellbeing and physical function as reported by people with neurological inflammatory disease (PwNID) during the COVID-19 pandemic. METHODS: 1134 PwNID and 868 control participants were recruited through five major academic medical centers in the Northeast/Mid-Atlantic U.S. beginning in April 2020. Participants completed serial surveys throughout the COVID-19 pandemic that aimed to quantify mood symptoms and physical function, analyzed cross-sectionally with a smaller cohort analyzed longitudinally. RESULTS: Throughout the pandemic, depression scores were not significantly different between PwNID and controls, although a higher proportion of PwNID reported clinically significant depression at study entry. Depression scores did not worsen over time for either group. Loneliness was the strongest predictor of worse depression, along with older age, male gender in both PwNID and controls, as well as lack of disease modifying therapy use, and disease duration in PwNID only. In contrast, physical disability worsened significantly over time for both PwNID and controls. Age, DMT status and comorbid health conditions emerged as significant predictors of physical function. CONCLUSIONS: Depressive symptoms remained consistent for both PwNID and controls throughout the COVID-19 pandemic, but physical function worsened significantly over time for both groups. This is particularly impactful for PwNID, who have higher baseline levels of physical disability, and underscores the importance of reinstituting services and interventions that facilitate exercise and reconditioning for this population.