IL4 and inflammation: We found that BMDM pretreated with PepN induced protection against HDM-induced airway inflammation, as determined by reduced numbers of eosinophils in BALF (Fig. 6i), attenuated infiltration of inflammatory cells and mucus secretion in peribronchial and perivascular (Fig. 6j) and decreased levels of inflammatory cytokines IL-4 and TNF-α in lungs (Fig. 6k).