IL17A and middle ear disorder: Pai-1 knockout mice showed significant pathological changes of tympanosclerosis (Shin et al., 2014); mice deficient in the C5a gene have been shown to have reduced levels of IL-6, mKC, and MCP-1, in association with decrease in inflammatory cell recruitment, mucosal inflammation, and bacterial clearance (Tong et al., 2014); mice lacking the IL-17A gene, encoding interleukin 17A (IL-17A), a neutrophil inducing factor, were associated with abnormal recruitment and apoptosis of neutrophils (Wang et al., 2014).