The clinical manifestations of SARS-CoV-2 infection, which is the cause of the coronavirus disease 2019 (COVID-19) pandemic, are highly variable and range from asymptomatic carriage or mild symptoms to severe disease involving different organ systems. However, the specific factors influencing individual clinical outcomes remain unclear. Thus, to characterize the versatile interplay of mucosal and systemic immune responses with the local microbiome and the viral load, as well as its impact on the course of the disease, Smith et al. performed integrated analyses of nasopharyngeal swabs and plasma samples from COVID-19 patients with varying degrees of illness severity. They observed that spike-specific neutralizing antibodies were heterogeneous between paired plasma samples and nasopharyngeal swabs from individual SARS-CoV-2 patients, suggesting a tissue-dependent regulation of humoral immune responses. Their study also confirmed that systemic inflammatory responses were associated with viral load. Interestingly, dysbiosis of the local microbiota and an accumulation of (facultative) pathogenic bacteria in the nasopharynx, frequently reported in secondary respiratory infections, were linked to mucosal inflammation and severe COVID-19. Conversely, the levels of cytokines, including IL-33 and different interferons that might be important for viral control, were reduced. Thus, Smith et al. revealed the nasopharyngeal microbiome as a novel player influencing local and systemic immune responses to SARS-CoV-2 and subsequently the clinical outcome of COVID-19…

Fuente: Cellular & Molecular Immunology

Published: 07 January 2022