[Effect of Fuzheng Tongluo Granules on macrophage pyroptosis in rat model with pulmonary fibrosis based on NLRP3/caspase-1/GSDMD pathway].

Abstract

To investigate the therapeutic effect of Fuzheng Tongluo Granules on idiopathic pulmonary fibrosis(IPF) and its mechanism. Seventy-two SD rats were randomly divided into the control group, model group, pirfenidone group(162 mg·kg~(-1)), and low-, medium-and high-dose of Fuzheng Tongluo Granules groups(2.63, 5.25, 10.5 g·kg~(-1)). Rat model of IPF was induced by a single non-invasive tracheal intubation drip of bleomycin(BLM). The corresponding drugs were given daily by gavage after the 2nd day of modeling, and body mass was recorded. On the 28th day, the samples were collected and weighed, and the lung coefficients were calculated. The pathological changes in the lung tissue were observed by HE and Masson staining, and the hydroxyproline(HYP) content of the lung tissue was detected by alkaline hydrolysis. The contents of tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), and interleukin-18(IL-18) of the lung tissue were determined by ELISA. The expression of collagen type Ⅰ(collagen Ⅰ) and α-smooth muscle actin(α-SMA) was observed by immunohistochemistry. The expression levels of NOD-, LRR-and pyrin domain-containing 3(NLRP3), cysteine-requiring aspartate protease type 1(caspase-1), gasdermin D-N(GSDMD-N), and apoptosis-associated speck-like protein containing a CARD(ASC) in the lung tissue were detected by Western blot. Immunofluorescence co-localization was used to observe the expression of GSDMD and CD68. The results show that compared with the control group, the model group showed increased lung coefficient, Ashcroft score, Szapiel score, HYP, TNF-α, IL-1β, and IL-18 content in the lung tissue and elevated protein expression levels of NLRP3, caspase-1, GSDMD-N, and ASC. The expression levels of GSDMD and CD68 were increased, and there was a high degree of co-localization between GSDMD and CD68. Compared with those in the model group, the lung coefficient, Ashcroft score, and Szapiel score decreased in all drug administration groups, and the content of HYP, TNF-α, IL-1β, and IL-18 decreased. The protein expression levels of NLRP3, caspase-1, GSDMD-N, and ASC decreased, and the expression levels of GSDMD and CD68 were reduced. There was a high degree of co-localization between GSDMD and CD68. In summary, Fuzheng Tongluo Granules can effectively reduce pulmonary fibrosis and inflammation levels in rats with IPF, and the mechanism may be related to the down-regulation of the NLRP3/caspase-1/GSDMD pathway to inhibit macrophage pyroptosis.