FOXO1 and allergic asthma: For example, FOXO1 overexpression in mice has been shown to promote allergic asthma through macrophage polarization, Th9 (T-helper 9 cell) differentiation, and regulation of IRF4 expression, though inhibition of FOXO1 led to attenuation of immune response and asthmatic inflammation through regulation of IRF4 (60, 61).