AHR and asthma: Similarly, a very recent study demonstrated that PM2.5 disturbs the balance of Th17/Treg cells by impairing differentiation of Treg cells and promoting differentiation of Th17 cells through the molecular pathways AhR–HIF-1α (hypoxia-inducible factor-1alpha) and AhR–Got1 (glutamate oxaloacetate transaminase 1) in a cockroach allergen-induced mouse model of asthma (31).