PPARD and COVID-19: In other words, previous studies have reported that the decrease in the expression of PPARs including PPARγ, PPARα, and PPARβ/δ during SARS-CoV-2 infection is associated with the increased secretion of proinflammatory cytokines such as IL6, IL1β, and TNF-α, as well as cytokine storm; thus, it has a positive correlation with ARDS and ALI in COVID-19 patients (150, 151).