Multiplex array analysis of circulating cytokines and chemokines in COVID-19 patients during the first wave of the SARS-CoV-2 pandemic in Milan, Italy

Background: The systemic inflammatory syndrome called "cytokine storm" has been described in COVID-19 pathogenesis, contributing to disease severity. The analysis of cytokine and chemokine levels in the blood of 21 SARS-CoV-2 positive patients throughout the phases of the pandemic has been studied to understand immune response dysregulation and identify potential disease biomarkers for new treatments. The present work reports the cytokine and chemokine levels in sera from a small cohort of individuals primarily infected with SARS-CoV-2 during the first wave of the COVID-19 pandemic in Milan (Italy). Results: Among the 27 cytokines and chemokines investigated, a significant higher expression of Interleukin-9 (IL-9), IP-10 (CXCL10), MCP-1 (CCL2) and RANTES (CCL-5) in infected patients compared to uninfected subjects was observed. When the change in cytokine/chemokine levels was monitored over time, from the hospitalization day to discharge, only IL-6 and IP-10 showed a significant decrease. Consistent with these findings, a significant negative correlation was observed between IP-10 and anti-Spike IgG antibodies in infected individuals. In contrast, IL-17 was positively correlated with the production of IgG against SARS-CoV-2. Conclusions: The cytokine storm and the modulation of cytokine levels by SARS-CoV-2 infection are hallmarks of COVID-19. The current global immunity profile largely stems from widespread vaccination campaigns and previous infection exposures. Consequently, the immunological features and dynamic cytokine profiles of non-vaccinated and primarily-infected subjects reported here provide novel insights into the inflammatory immune landscape in the context of SARS-CoV-2 infection, and offer valuable knowledge for addressing future viral infections and the development of novel treatments.