Abstract
Background: Studies have suggested a possible contribution for IL-17 in the development and progression of pulmonary fibrosis. Besides, IL-17 induced type V collagen (COLV) overexpression in obliterative bronchiolitis. COLV is a quantitatively minor collagen that regulates the fibrillogenesis. Recently COLV overexpression was described in the early fibrosis processes. Objectives: To correlate COLV expression with IL-17+ cells in the pulmonary tissues of C57BL/6 mice immunized with COLV. Methods: C57BL/6 female mice (n=6) were subcutaneously immunized with 150µg/200µl of COLV in complete Freund´s adjuvant (FA). Control mice (n=6) were immunized with FA. Total collagen and COLV deposit in pulmonary interstitium were evaluated by picrossirius and immunostaining and quantified by image analysis. IL-17+ cells were evaluated by immunohistochemistry and point counting method. Results: Immunized mice presented prominent thickness of the septal and bronchovascular interstitium with thick collagen fibers, characteristic of the fibrotic process. Also, these mice showed high expression of COLV thick fibers along the bronchovascular and septal interstitium, differing from its normal fibrilar pattern of thin fibers found in control mice (18.11±0.65 vs. 4.61±0.66, p=0.002). The amount of IL-17+ cells in the pulmonary interstitium was higher in immunized mice when compared to controls (47.05±5.17 vs. 12.21±5.17, p=0.001). Conclusions: COLV high expression was correlated with more IL-17+ cells expression, suggesting that this cytokine can play a role in inducing COLV overexpression in pulmonary remodeling. Strategies to block IL-17+ cells may represent a promissory therapeutic target to fibrosis process.
- © 2014 ERS