Paracoccidioides spp. EXOANTIGENS INDUCE PROLIFERATION AND MODULATION OF PULMONARY FIBROSIS

Paracoccidioidomycosis (PCM) is a systemic and granulomatous mycosis caused by thermally dimorphic fungi of the genus Paracoccidioides. Endemic in Latin America, PCM presents high incidence in Brazil, Colombia and Venezuela, especially among men and rural workers. The main clinical forms are acute/subacute (AF), and chronic (CF) form. Patients with CF (CF-p) have long-term disease and sequelaes, such as pulmonary fibrosis, are observed even after an effective antifungal treatment. Several studies have shown that CF-p present elevated production of inflammatory mediators, as IL-1β, cytokine involved in the exacerbation of the inflammatory response and also induces the production of TGF-β1. This growth factor is essential for the fibrogenesis, responsible for the transformation of fibroblasts into a myofibroblasts, collagen-producing cells and although the fibrogenesis is recognized as an early process in PCM, its mechanisms are unknown. It is possible that pulmonary involvement occurs in the early stage of the disease and there is no recovery of lung function. Recently, studies have observed the presence of reticular fiber deposition in the alveolar septum in areas distant from the granulomatous lesion, suggesting the possibility of components of the fungus itself acting in the fibrogenesis process. Thus, we investigated the influence of Paracoccidioides ssp components of PCM patients in the proliferation and responsiveness of pulmonary fibroblasts. For this, human pulmonary fibroblasts (MRC-5 strain) and ex-vivo pulmonary fibroblasts isolated from BALB/c mice were cultivated with P. brasiliensis (Pb18 and Pb326) and P. lutzii (Pb01, Pb8334 and Pb66) exoantigens at concentrations of 2.5, 5, 10, 100 and 250 µg/mL. Purified gp43, the immunodominant protein in P. brasiliensis exoantigens, was also evaluated at concentrations of 5 and 10 µg/mL. After 24 hours, cellular proliferation and production of cytokines and grow factors by murine and human pulmonary fibroblasts were evaluated. Our results showed that the fungal components of the two species induced fibroblasts proliferation (p < 0.05), increased levels of TGF-β1 (p < 0.05) and pro-collagen I, and decreased IL-6 (p < 0.05), VEGF (p < 0.05) and bFGF (p < 0.05) by both murine and human pulmonary fibroblasts. Gp43 induced increased levels of TGF-β1 (p = 0.02) by human pulmonary fibroblast. Therefore, our results showed, at first time, that P. brasiliensis and P. lutzii components interfere in the fibrogenesis by directly act in the biology of pulmonary fibroblast.