IL33 and obesity due to melanocortin 4 receptor deficiency: IL-33 contributed to obesity-related increases in the response to O3: BAL IL-33 was greater in obese than lean O3 exposed mice (Figures 1A and 5C) and anti-ST2 reduced O3-induced increases in baseline mechanics, in airway responsiveness, and in BAL neutrophils in obese but not lean mice (Figure 1C,D).