Immune Dysregulation in the Oral Cavity during Early SARS-CoV-2 Infection

Tissue-specific immune responses are critical determinants of health-maintaining homeostasis and disease-related dysbiosis. In the context of COVID-19, oral immune responses reflect local host-pathogen dynamics near the site of infection and serve as important "windows to the body," reflecting systemic responses to the invading SARS-CoV-2 virus. This study leveraged multiplex technology to characterize the salivary SARS-CoV-2-specific immunological landscape (37 cytokines/chemokines and 11 antibodies) during early infection. Cytokine/immune profiling was performed on unstimulated cleared whole saliva collected from 227 adult SARS-CoV-2+ participants and 37 controls. Statistical analysis and modeling revealed significant differential abundance of 25 cytokines (16 downregulated, 9 upregulated). Pathway analysis demonstrated early SARS-CoV-2 infection is associated with local suppression of oral type I/III interferon and blunted natural killer-/T-cell responses, reflecting a potential novel immune-evasion strategy enabling infection. This virus-associated immune suppression occurred concomitantly with significant upregulation of proinflammatory pathways including marked increases in the acute phase proteins pentraxin-3 and chitinase-3-like-1. Irrespective of SARS-CoV-2 infection, prior vaccination was associated with increased total α-SARS-CoV-2-spike (trimer), -S1 protein, -RBD, and -nucleocapsid salivary antibodies, highlighting the importance of COVID-19 vaccination in eliciting mucosal responses. Altogether, our findings highlight saliva as a stable and accessible biofluid for monitoring host responses to SARS-CoV-2 over time and suggest that oral-mucosal immune dysregulation is a hallmark of early SARS-CoV-2 infection, with possible implications for viral evasion mechanisms.