Mast cell activation signature as a potential biomarker in COVID-19

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, represented a public health challenge due to the absence of effective treatments to combat the disease. Lethality associated with SARS-CoV-2 infection results from an exacerbated immune response that mediates clinical disease progression and compromises respiratory capacity and organ function. In the lungs, one of the cell lineages increased during COVID-19 are mast cells (MC), cells of innate immune response known for their ability to promote inflammation through the release of their pre-formed mediators or de novo synthesis. The role of MC-derived mediators during SARS-CoV-2 infection and their association with the development of severe COVID-19 have been poorly described. In a previous report, we demonstrated the predictive ability of carboxypeptidase A3 (CPA3) to determine COVID-19 severity. However, it is currently unclear whether the use of other mast cell-derived mediators could improve this predictive ability. To address this gap, we evaluated levels of total tryptase, CPA3, chymase, and prostaglandin D2 (PGD2) in serum from patients with non-severe and severe COVID-19 to develop a predictive model of severe COVID-19 outcomes. We demonstrate that the combined use of these mediators enhances their predictive ability for MC activation during SARS-CoV-2 infection and their involvement in severe forms of COVID-19. Based on these findings, a serum MC activation profile can be proposed as a promising biomarker for SARS-CoV-2 infection and may contribute to the development of targeted therapeutic strategies to improve patient outcomes.