Regulation Of Immune Microenvironments Attenuates And Reverses Pulmonary Fibrosis In Murine Models Of Pulmonary Fibrosis

Pulmonary inflammation and pulmonary fibrosis are the common pathological features ofinterstitial lung diseases that result from a variety of reasons. Dependenting on initiatingpathogens, the time and properties of lung injury, different molecular and cellular mechanisms areresponsible for the regulation of pulmonary injury and wound healing, resulting either in theresolution of inflammation or in the progressive pulmonary fibrosis. Immune system plays animportant role in generating, maintaining, developing, or inhibiting pulmonary fibrosis. Theactivation of innate immunity determines the polarization direction of adaptive immunity throughtoll-like receptors or non-TLR dependent pathways, while the adaptive immune responses,especially the Th1 and Th2 responses, are critical for both resolution and development ofpulmonary fibrosis. The polarization of the adaptive immunity to the lung injury toward a favorableThl response leads to the resolution of inflammation and regeneration of the injury tissue. Incontrast, a Th2 response is associated with progressive fibrosis. In this study we investigated themechanism of innate immunity activating Th1/Th2 balance of adaptive immunity after lung injury,and the relationship of Th1/Th2 polarization with development of pulmonary fibrosis in cells andanimal models, including DG-based screening system, murine models of bleomycin-inducedpulmonary fibrosis and silica-induced pulmonary fibrosis. Moreover, we studied the mechanism ofthe HO-1 inducer in regulation of ROS systems and pulmonary immune microenvironment insilica-induced pulmonary fibrosis. We explored the potential therapeutic effects of CFX, afermentative polysaccharides of medicinal mushroom, CF78, a nature HO-1 inducer, andanti-TLR2 antibody on pulmonary fibrosis. Additionally, we determined protein expression profilesduring the development of bleomycin-induced pulmonary fibrosis. In partⅠ, polysaccharides ofmushroom CFX prevented and reversed pulmonary fibrosis by integrative activation of TLR2,Dectin-1, and to a less content, TLR4 signaling pathways to shift the balance of Th1/Th2 immuneresponses toward Th1- dominant response in the lungs. CFX also decreased bleomycin-inducedanimal death, ameliorated pulmonary function of silica-induced pulmonary fibrosis rats. In partⅡ,HO-1 inducer CF78 significantly retarded the development of silica-induced pulmonary fibrosis byinhibiting pro-fibrotic factors including PAI-1, TGFβ1. These antifbtoic effects of CF78 might berelated with regulating pulmonary microenvironments, inhibiting expression of pulmonary toll-likereceptor 9, and decreasing profibrotic factor IL-10. In partⅢ, bleomycin was found to inducesignificantly maturation of DCs by enhancing expressions of MHC classⅡmolecules,co-stimulatory molecules and cytokines and these effects were specifically blocked by anti-TLR2antibody. Bleomycin-activated DCs promoted polarization of T helper(TH) 1- and TH2-cells viaactivation of TLR2. Moreover, inhibition of TLR2 by anti-TLR2 antibody significantly attenuatedbleomycin-induced pulmonary injury, decreased bleomycin-induced animal death, and attenuatedbleomycin-induced pulmonary fibrosis. In partⅣ, we found that bleomycin-induced fibrosis wasaggravated by anti-TLR4 antibody, and the anti-fibrosis effect of pro-inflammtion cytokine IFNγwas better than that of glucocorticoid. We also tried to dig out the specific different proteins duringbleomycin-induced pulmonary fibrosis by two-dimensional electrophoresis. The results of thisstudy will contribute to understanding the pathogenesis of pulmonary fibrotic diseases, finding andidentifing the molecular targets of pulmonary fibrosis, and providing the research clues for thedevelopment of new anti-pulmonary fibrosis drugs.