Study On The Protective Effect Of PMID On Pulmonary Fibrosis

Pulmonary fibrosis,especially idiopathic pulmonary fibrosis?IPF?,is a chronic and irreversible histopathological process with complicated pathogenesis and poor cure clinically.Only two drugs,Nintedanib and Pirfenidone,have been used to treat IPF.However,the therapeutic effects are still limited and both of them have certain side effects.Therefore,it is of great significance to develop a novel effective drug for the treatment of pulmonary fibrosis.PMID is a small molecular antioxidant compound screened by the screening technology platform based on Keap1/Nrf2 protein interaction.Our previous studies found that PMID can enhance the phosphorylation and stability of Nrf2 and then activate Nrf2/ARE antioxidant signaling pathway,and upregulate the expression of antioxidant genes such as SOD and NQO1.In addition,according to preclinical pharmacokinetic guidelines,our study found that PMID showed certain rules of absorption,elimination and distribution in the body with good metabolism.Furthermore,PMID was found to show potential protective effects against low-dose radiation injury and bleomycin-induced pulmonary fibrosis in mice.The synthesis of PMID and its application in the treatment of pulmonary fibrosis have been patented?Application number:201610794652.6?.In this study,we used BLM-induced rat pulmonary fibrosis model and silica-induced mouse pulmonary fibrosis model to evaluate the protective effect of PMID in pulmonary fibrosis systematically,and explore the mechanism.The experimental animals were administered via pulmonary spray to establish the best spray dosage of BLM and SiO₂,followed by two modes of administration,prevention and treatment.The experiment animals was divided into normal control?NC?,model control?MC?,three PMID administration groups?low,middle and high dose?and positive drug groups?BF and PFD?.After 28 days of modeling,the lung respiratory function was detected in the experimental animals.Then the animals were sacrificed.The pathological damage of lung tissue was observed by H&E staining,Masson staining and Sirius red staining.The formation of collagen in lung tissue was quantitatively analyzed.The expression levels of TGF-?,Col1A2,?-SMA and different markers of inflammatory cells including CD11b,F4/80 and CD3 were analyzed by immunohistochemistry.RT-PCR was used to detect the mRNA levels of inflammatory cytokines and pulmonary fibrosis-related cytokines in lung tissue.In BLM-induced rat pulmonary fibrosis,we evaluated the protective effect of PMID prevention and treatment on pulmonary fibrosis.PMID can effectively alleviate the lung injury,reduce the production of collagen,and decrease the expression of inflammatory-releated molecules in a dose-dependent manner.When PMID was given immediately after the model,PMID could effectively inhibit the inflammatory stage and the pulmonary fibrosis transformation induced by BLM.During the period of acute injuries,PMID can effectively alleviate the acute inflammation of the lungs,reduce the invasion of neutrophils and macrophages in the process of pulmonary fibrosis and significantly decrease the number of inflammatory cytokines,such as tumor necrosis factor alpha?TNF-??,Interleukin 1 beta?IL-1??and Interleukin 6?IL-6?.At the same time,the PMID can effectively reduce the production of collagen and the expression of TGF-?to alleviate the disease process of pulmonary fibrosis.Finally in the stage of fibrotic formation,PMID can effectively alleviate the pathological damage of pulmonary fibrosis in rats and reduce the content of collagen and the expression of?-SMA and Collagen1,suggesting that PMID can effectively alleviate BLM-induced pulmonary fibrosis at various stages,then slowing down the progress of the disease.In silica-induced mouse pulmonary fibrosis,no matter the preventive administration or the therapeutic administration,PMID can effectively alleviate the lung injury,reduce the production of collagen,and decrease the expression of inflammatory-releated molecules in a dose-dependent manner.PMID high dose group showed dramatic protective effect on pulmonary fibrosis,which is obviously better than the positive drug group.Analyzing the types of inflammatory cells and the expression of inflammatory-related factors at a cellular and molecular level suggest that the number of macrophages and neutrophils and the expression of IL-6 in PMID administration group were significantly decreased.These data suggest that PMID can inhibit the SiO2-induced pulmonary fibrosis by inhibiting the inflammatory stage of pulmonary fibrosis.