Efeitos do treinamento físico aeróbico na fibrose pulmonar

Abstract

Background: Idiopathic pulmonary fibrosis (IPF) is characterized by decline of lung function, increased inflammation and fibrosis mainly in the pulmonary interstitium, with serotonin (5-HT) and Akt signaling presenting a role. Aerobic training (AT) reduces lung injury in different models of pulmonary diseases. However, the mechanisms underlying the effects of AT in a model of bleomycin-induced lung fibrosis is unknown. Thus, this study investigated the effects of AT in a model of bleomycin-induced pulmonary fibrosis, as well as the participation of 5HT/Akt signaling. Methods: Seventy-two C57Bl/6 male mice were distributed in Control (Co), Exercise (Ex), Fibrosis (Fi) and Fibrosis+Exercise (Fi+Ex) groups. Bleomycin (1.5UI/Kg) was administered on day 1 and treadmill AT began on day 14 during 4 weeks. Total and differential cells count in bronchoalveolar lavage (BAL), IL-1beta, IL-6, CXCL1/KC, IL-10, TNF-alpha and TGF-beta levels in BAL fluid, collagen content in the lung parenchyma, 5-HT levels in BAL fluid and in serum, and the expression of 5-HT2b receptor and Aktphosphorylation were evaluated. Results: AT reduced bleomycin-increased number of total cells (p<0.001), neutrophils (p<0.01), macrophages (p<0.01) and lymphocytes (p<0.05) in BAL. AT also reduced the levels of IL-1beta (p<0.01), IL-6 (p<0.05), CXCL1/KC (p<0.001), TNF-alpha (p<0.001) and TGF-beta (p<0.001), while increased the levels of IL-10 (p<0.001). Collagen fibers deposition was also reduced by AT (p<0.01). These findings were followed by AT-reduced bleomycin-increased 5-HT levels in BAL fluid (p<0.001) and in serum (p<0.05), as well as the expression of 5-HT2b receptor (p<0.01) and the Aktphosphorylation in lung tissue. Conclusions: We conclude that AT reduces lung inflammation and fibrosis in a model of bleomycin-induced lung fibrosis involving 5-HT/Akt signaling.