Immuno-proteomic profiling reveals aberrant immune cell regulation in the airways of individuals with ongoing post-COVID-19 respiratory disease

Some patients hospitalized with acute COVID-19 suffer respiratory symptoms
that persist for many months. We delineated the immune-proteomic landscape
in the airway and peripheral blood of healthy controls and post-COVID-19
patients 3 to 6 months after hospital discharge. Post-COVID-19 patients
showed abnormal airway (but not plasma) proteomes, with elevated
concentration of proteins associated with apoptosis, tissue repair and
epithelial injury versus healthy individuals. Increased numbers of
cytotoxic lymphocytes were observed in individuals with
greater airway dysfunction, while increased B cell numbers and altered
monocyte subsets were associated with more widespread lung abnormalities.
1 year follow-up of some post-COVID-19 patients indicated that these
abnormalities resolved over time. In summary, COVID-19 causes a prolonged
change to the airway immune landscape in those with persistent lung
disease, with evidence of cell death and tissue repair linked to ongoing
activation of cytotoxic T cells.