Low–Molecular Weight Fucoidan Polysaccharide Inhibits Pulmonary Fibrosis by Regulating M1/M2 Macrophages Polarization

Abstract In this study, sulfated polysaccharides extracted from Laminaria japonica were degraded by free radicals to obtain low–molecular weight fucoidan (LMWF). The effects of LMWF on bleomycin-treated pulmonary fibrosis (PF) mice were evaluated in precious research. In this study, the expression of M2 macrophage polarization biomarker arginase was detected by immunohistochemistry, and the expression of M1/M2 markers was detected by Western blot and qPCR. It was found that the expression of M1/M2 macrophage markers were significantly increased in the lung tissue of pulmonary fibrosis mice, and LMWF could effectively reduce its expression. Subsequently, in order to verify the mechanism of LMWF inhibiting pulmonary fibrosis by regulating macrophage polarization, MH-S cells were induced by LPS combined with IFN-γ and IL-4 to construct the in vitro macrophage polarization models, and the expression of biomarkers were analyzed by Western blot and qPCR. The results showed that LMWF could regulate M1 macrophage polarization through early anti-inflammatory effect and inhibit the development of pulmonary fibrosis by inhibiting M2 macrophage polarization in the later stage.