PTN and COVID-19: Conforming with previous reports which were mostly conducted using the peripheral blood of COVID-19 patients [3], our study shows a significant increase in the following markers, CA12, CAPG, CDPC1, CD40, CXCL9, IL-6, IL-8, OSM, PD-L1, PTN, STX8, and VEGF, thus, pinpointing their relevance to be applied for the treatment of critically ill COVID-19 patients (Figure 2).