Il-17+Cells Immunoexpression in Systemic Sclerosis Pulmonary Fibrosis

Background: Investigators have documented an increased number of IL-17+ cells in peripheral blood, in bronchoalveolar lavage and in skin of patients with systemic sclerosis (SSc). IL-17+ cells have been associated to collagen overexpression in SSc fibroblast. Objectives: To evaluate the expression of IL-17+ cells in the pulmonary fibrosis process of the SSc patients. Patients and methods: Lung biopsies were obtained from 14 female patients with SSc (age 26–56 y): 9 patients had limited SSc, and 5 patients had diffuse according to the American College of Rheumatology criteria. Control samples were collected from necropsies of 6 individuals without pulmonary pathology (CAPPesq 0960/08). The collagen I, III and V deposit in pulmonary interstitium was evaluated by immunofluorescence and quantified by image analysis using the software Image-Pro Plus 6.0. IL17+ cells were immunostained by immunohistochemistry and evaluated by the point counting method. Results: Alveolar septa was 4.7-fold greater in SSc when compared to controls. There was no difference in thickened alveolar septa and collagen content between limited and diffuse SSc. However, in both SSc forms, collagen I was higher expressed than collagen III (p=0.011) and V (p=0.002). The amount of IL-17+ cells in the pulmonary interstitium was higher in SSc patients when compared to controls (p=0.01). Limited and diffuse SSc presented the same amounts of IL-17+ cells. Conclusions: Distorted lung framework found in SSc is associated to IL-17+ cells immunoexpression, thus suggesting that this cytokine is involved in altered pathway of SSc pulmonary fibrosis and may represent a promissory immune therapeutic target. Financial support: FAPESP, Federico Foundation.