The immune response plays a critical role in the pathophysiology of SARS-CoV-2 infection ranging from protection to tissue damage. This is observed in the development of acute respiratory distress syndrome when elevated levels of inflammatory cytokines are detected. Several cells of the immune response are implied in this dysregulated immune response including innate immune cells and T and B cell lymphocytes. Mast cells are abundant resident cells of the respiratory tract, able to rapidly release different inflammatory mediators following stimulation. Recently, mast cells have been associated with tissue damage during viral infections, but little is known about their role in SARS-CoV-2 infection. In this study we examined the profile of mast cell activation markers in the serum of COVID-19 patients. We noticed that SARS-CoV-2 infected patients showed increased carboxypeptidase A3 (CPA3), and decreased serotonin levels in their serum. CPA3 levels correlated with C-reactive protein, the number of circulating neutrophils and quick SOFA. CPA3 in serum was a good biomarker for identifying severe COVID-19 patients, while serotonin was a good predictor of SARS-CoV-2 infection. In summary, our results show that serum CPA3 and serotonin levels are relevant biomarkers during SARS-CoV-2 infection, suggesting that mast cells are relevant players in the inflammatory response in COVID-19, might represent targets for therapeutic intervention.
SEVERE COVID-19 IS MARKED BY DYSREGULATED SERUM LEVELS OF CARBOXYPEPTIDASE A3 AND SEROTONIN