Effect of Liangxue Huoxue decoction on intestinal flora and NLRP3/caspase-1/GSDMD signaling pathway in mice model of sepsis-induced acute kidney injury

Abstract

To investigate the effect of Liangxue Huoxue decoction on intestinal flora, intestinal barrier and NOD-like receptor protein 3 (NLRP3)/caspase-1/gasdermin D (GSDMD) pyroptosis signaling pathway in mice model of sepsis-induced acute kidney injury (AKI). The model of AKI was established by cecal ligation and perforation (CLP). Thirty male C57BL/6 mice were randomly divided into sham operation group (Sham group), sepsis group (CLP group) and sepsis+Liangxue Huoxue decoction (CLP+LXHX group), with 10 mice in each group. Mice in Sham group only underwent laparotomy. Two hours before model establishment, mice in CLP+LXHX group were treated with Liangxue Huoxue decoction (6 g/kg) by gavage; mice in Sham group and CLP group were given equal volume of normal saline by gavages. After 24 hours of modeling, all mice were sacrificed under anesthesia, and the colon and kidney tissues and fresh feces in the colon were taken. The pathological changes of kidney and colon were observed by hematoxylin-eosin (HE) staining under light microscope. Real-time polymerase chain reaction (RT-PCR) was used to detect inflammatory factors (interleukins, IL-1β and IL-18) in renal tissue. The expressions of NLRP3, caspase-1 and GSDMD were detected by Western blotting. The changes of intestinal flora in mice were detected by 16S rDNA high-throughput sequencing. Compared with the Sham group, the inflammatory cell infiltration of the kidney tissue was increased and the kidney became vacuolated in CLP group, the mRNA expressions of IL-1β, IL-18, and the protein expressions of NLRP3, caspase-1 and GSDMD were significantly increased in CLP group, the species richness of intestinal microflora decreased significantly, the relative abundance of Enterococcus and Escherichia-Shigella increased significantly, and the relative abundance of Ileibacterium, Alloprevotella, Lachnospiraceae, Klebsiella and Parasutterella increased significantly in CLP group. Compared with CLP group, Liangxue Huoxue decoction can significantly reduce the pathological changes of kidney and colon tissue, reduce the pathological score (1.75±0.43 vs. 3.50±0.50 for kidney tissue, 1.25±0.43 vs. 4.50±0.50 for colon tissue, both P < 0.05), improve the composition of intestinal flora, reduce the relative abundance of Enterococcus and Escherichia-Shigella, and significantly increase the relative abundance of Lactobacillus and Akkermansia. In addition, Liangxue Huoxue decoction can significantly reduce mRNA expressions of IL-1β and IL-18 in kidney tissue [IL-1β mRNA (2-ΔΔCt): 1.59±0.05 vs. 4.61±0.88, IL-18 mRNA (2-ΔΔCt): 1.69±0.17 vs. 2.86±0.63, both P < 0.05] and the protein expressions of NLRP3, caspase-1 and GSDMD (NLRP3/GAPDH: 0.71±0.04 vs. 0.89±0.01, caspase-1/GAPDH: 1.04±0.04 vs. 1.48±0.04, GSDMD/GAPDH: 0.90±0.01 vs. 1.41±0.02, all P < 0.05). Liangxue Huoxue decoction has obvious protective effect on AKI induced by sepsis. It can improve intestinal barrier by regulating intestinal flora, thereby inhibiting the activation of NLRP3/caspase-1/GSDMD signaling pathway in kidney tissue and reducing the expression of proptosis-related inflammatory factors.