[Effect of Gualou Xiebai Decoction on pulmonary fibrosis in rats based on pyroptosis pathway]

This study investigated the effect of Gualou Xiebai Decoction on rats with bleomycin-induced pulmonary fibrosis. The rats were randomly divided into a control group, a model group, a low-dose Gualou Xiebai Decoction group(2.4 g·kg~(-1)), a high-dose Gualou Xiebai Decoction group(4.8 g·kg~(-1)), and pirfenidone group(150 mg·kg~(-1)). The model of pulmonary fibrosis was established by intratracheal instillation of bleomycin in all groups, except the control group. Since the second day of modeling, the corresponding drugs were given to rats by intragastric administration, once a day for 14 d and 28 d. The hematoxylin-eosin(HE) staining was used to evaluate the degree of inflammatory injury in lung tissues. The immunofluorescence staining was used to detect the expression of CD68 and CD163 in lung tissues of rats. The levels of tumor necrosis factor-α(TNF-α) and interleukin-10(IL-10) in serum and brochoalveolar lavage fluid(BALF) were detected by enzyme-linked immunosorbent assay(ELISA). The expression of pyroptosis-related genes in lung tissues of rats was detected by qRT-PCR. The results of HE staining and immunofluorescence staining showed that the lung tissue structure was normal in the control group. In addition, there were alveolar collapse or even closure in lung tissues of rats in the model group, with obvious inflammatory cell infiltration, and the expression of CD68 and CD163 was significantly up-regulated. As compared with the model group, the lung tissue structure of rats in the Gualou Xiebai Decoction groups was significantly improved, with alleviated inflammation, and the expression of CD68 and CD163 was decreased. As compared with the control group, the level of TNF-α in serum and BALF of rats in the model group was significantly increased(P<0.01), the mRNA expression levels of alpha smooth muscle actin(α-SMA), collagen type Ⅰ alpha 1 chain(Col1a1), caspase-1, IL-1β, IL-18, gasdermin D(Gsdmd), and NOD-like receptor thermal protein domain associated protein 3(NLRP3) in lung tissues were significantly increased(P<0.05, P<0.01), and the mRNA expression level of E-cadherin was significantly decreased(P<0.01). As compared with the model group, the level of TNF-α in serum and BALF was significantly down-regulated in the high-dose Gualou Xiebai Decoction group(P<0.05, P<0.01), and that of IL-10 was up-regulated(P<0.05, P<0.01). The mRNA expression levels of α-SMA, Col1a1, caspase-1, IL-18, Gsdmd, NLRP3 and IL-1β in lung tissues were significantly decreased(P<0.05, P<0.01) in the high-dose Gualou Xiebai Decoction group, and the mRNA expression level of E-cadherin was significantly increased(P<0.05, P<0.01). In conclusion, Gualou Xiebai Decoction can down-regulate the levels of inflammatory factors and related genes and effectively mitigate pulmonary fibrosis by regulating the pyroptosis pathways.