LEP and asthma: High leptin level was reported to inhibit neutrophil death by activating MEK1/2 and NF-κB pathways, produce neutrophil chemotaxis by activating ERK1/2 and p38-MAPK pathways; stimulate natural killer cells and macrophages to release inflammatory factors, and promote epithelial cells and smooth muscle cells in the airway to proliferate in asthma [112,113].