IL17A and keratoconus: IL-6 induces IL-17 to produce an inflammatory response, promotes KC hyperproliferation, and increases T-cell aggregation in the epidermis. IL-17 and TNF-α promote the expression of CCL20 in KCs and further attract dendritic cells as well as Th17 cells, thereby promoting the formation of chemotaxis rings and exacerbating the inflammatory response in psoriasis (Wang et al., 2015; Yang et al., 2020).