Altered serum concentrations of IL-8, IL-32 and IL-10 in patients with lung impairment 6 months after COVID-19

Post-COVID symptoms are reported in 10-35 % of patients not requiring hospitalization, and in up to 80 % of hospitalized patients and patients with severe disease. The pathogenesis of post-COVID syndrome remains largely unknown. Some evidence suggests that prolonged inflammation has a key role in the pathogenesis of most post-COVID manifestations. We evaluated a panel of inflammatory and immune-mediated cytokines in individuals with altered HRCT features and in patients without any long-term COVID symptoms. Blood samples of 89 adult patients previously hospitalized with COVID-19 were collected and stratified as patients with and without HRCT evidence of fibrotic lung alterations. Serum analyte concentrations of IL-4, IL-2, CXCL10 (IP-10), IL-1β, TNF-α, CCL2 (MCP-1), IL-17A, IL-6, IL-10, IFN-γ, IL-12p70 and TGF-β1 (free active form) were quantified by bead-based multiplex assay. Clinical and functional data were recorded in a database. With the use of machine learning approach, IL-32, IL-8, and IL-10 proved to be associated with the development of HRCT evidence of lung sequelae at follow-up. Direct comparison of cytokine levels in the two groups showed increased levels of IL-32 and decreased levels of IL-8 in patients with lung impairment. After further stratification of patients by severity (severe versus mild/moderate) during hospitalization, IL-10 emerged as the only cytokine showing decreased levels in severe patients. These findings contribute to a better understanding of the immune response and potential prognostic markers in patients with lung sequelae after COVID-19.