IL33 and asthma: Insufficient clearance of impaired apoptotic epithelial cells has previously been documented to lead to the overproduction of IL-33 (Penberthy et al. 2014), which is a crucial substrate for caspases (caspase-3 and -7) activated during apoptosis (Luthi et al. 2009).Another study showed that IL-25 expression was positively associated with the number of apoptotic cells in HDM-induced asthma (Yuan et al. 2017).