Second, severe asthma animal model and the BECs cellular model were established to evaluate the expression, influence, and role of MBD2 on Th17 cells, comparison of male and female sex hormone therapeutic efficacy in severe asthma, and sex hormones affecting the expression of Th17 cells via regulating MBD2 in BECs as a cellular level working mechanism of sex hormone in severe asthma. Here, MBD2 is linked to asthma.