It is possible that differences in the ability of ST2 deficiency to reduce responses to O3 in db/db mice [12] but not mice with DIO (Figs.6, 7) is due to differences in the sex of the mice: sex impacts responses to O3 [17] and the db/db mice were female [12] but we used male mice in this study because female mice are resistant to the induction of obesity by HFD feeding [24]. Here, IL1RL1 is linked to obesity due to melanocortin 4 receptor deficiency.