Cytokine storm and COVID-19 severity

Cytokine storm in case of COVID-19 is considered to be one of the major causes of acute respiratory distress syndrome (ARDS) and multiple organ failure. It plays an important role in the process of disease aggravation. Aim of the study was to characterize the effect of SARS-CoV-2 on the production of cytokines in patients with severe clinical symptoms and selected sets of samples from patients with mild or no clinical symptoms. Based on the analysis of the topical scientific literature on the peculiarities of the clinical course of COVID-19, a cytokine panel (GM-CSF, IFN-γ, IL-1β, IL-6, IL-8, IL-17A, IL-18, IP-10, MCP-1, MIP-1α, MIP-1β, PDGF-AB/BB, TNF-α, VEGF-A) was created to determine the differences in cytokine levels in both hospitalized and non-hospitalized patients using the Luminex200 system. To date, we have analysed 104 plasma samples of which 61 [24 (39%) male, median age 40 years; 37 (61%) female, median age 44.5 years] were from outpatients and 43 [17 (40%) male, median age 61 years; 26 (60%) female, median age 71 years] from hospitalized COVID-19 patients. The obtained results were analysed using GraphPad Prism 9.0. Comparing hospitalized patients against outpatients results clearly shows that most patients with severe COVID-19 exhibit markedly increased plasma levels of pro-inflammatory cytokines and the statistically significant correlation between hospitalized patients and outpatient for multiple cytokines: IFN-γ, IL-6, IL-8, IL-18, IP-10, MCP-1, TNF-α and VEGF-A. Our results confirm the previously published that a sudden increase in cytokine levels provoked by systemic stimuli, like a generalized viral disease may easily escape the regulation and trigger systemic responses within the definition of ‘cytokine storm’, systemic inflammatory response syndrome or ARDS.