IL17A and pulmonary fibrosis: 1, 25-dihydroxycholecalciferol calcitriol, [1,25(OH)2D3] is activate form of vitamin D, and calcitriol inhibited IL-23/IL-17 in the airway of cystic fibrosis patients.(51) Furthermore, calcitriol prevented experimental lung fibrosis model in mice via inhibiting inflammation and accumulation of activated fibroblasts.(52) Thus, IL-23/IL-17 pathway possibly is involved in IP development, however our preliminary examination of the serum IL-17 concentration did not show apparent elevation of IL-17A in Ro52 positive patients.