[Huangqi Glycoprotein improves myocardial injury in rats with adjuvant arthritis by interfering with lncRNA GAS5/miR-21/TLR4 signaling axis to inhibit pyroptosis].

Objective To investigate the effect and mechanism of Huangqi glycoprotein (HQGP) on myocardial injury in rats with adjuvant arthritis (AA) based on the long non-coding RNA growth arrest-specific transcript 5/microRNA-21/Toll-like receptor 4 (lncRNA GAS5/miR-21/TLR4) signal axis. Methods SD rats were randomized into normal control, model, methotrexate (MTX) and HQGP groups, with 6 rats in each group. The AA rat model was established, and the drug was administered on the 19th day after the model was established, for 4 consecutive weeks. The degree of toe swelling and the arthritis index (AI) of AA rats in each group were measured. The pathological changes of rat myocardial tissue were observed by HE staining, and the changes in the ultrastructure of the myocardial tissue and the situation of pyroptotic vesicles were observed by transmission electron microscope. The levels of serum interleukin 6 (IL-6), IL-18, IL-1β and tumor necrosis factor α (TNF-α) were detected by ELISA. The release of lactate dehydrogenase (LDH) in myocardial tissue was detected by kit. Real-time quantitative PCR was used to detect the mRNA expression of nuclear factor-kappa B p65 (NF-κB p65), cysteine aspartate specific proteinase 1 (caspase-1), nucleotide binding oligomerization domain like receptor family pyrin domain containing 3 (NLRP3), gasdermin D (GSDMD), and molecules in the lncRNA GAS5/miR-21/TLR4 signaling axis in the myocardial tissue. The protein levels of TLR4, NF-κB p65, caspase-1, NLRP3 and GSDMD in myocardial tissue were detected by Western blot. Results Compared with the normal control group, the toe swelling and AI of the model group rats were significantly increased. The myocardial fibers of rats dissolved and broken, the structure of sarcomere was blurred, the arrangement of myocardial fibers was disordered, there was inflammatory cell infiltration between tissues, the mitochondrial cristae were significantly broken and sparse, and the number of pyroptotic vesicles increased. The expression of serum pro-inflammatory cytokines IL-6, IL-18, IL-1β and TNF-α increased significantly. In myocardial tissue, the expression of GAS5 reduced significantly, the expression of miR-21 increased significantly, the release of LDH, and the mRNA and protein levels of TLR4, NF-κB p65, caspase-1, NLRP3 and GSDMD increased significantly. Compared with the model group, the toe swelling, AI, and the pathological status of myocardial tissue in the HQGP group rats were improved significantly. The expressions of serum IL-6, IL-18, IL-1β and TNF-α reduced significantly. In myocardial tissue, the expression of GAS5 increased significantly, the expression of miR-21 decreased significantly, the release of LDH, the mRNA and protein levels of TLR4, NF-κB p65, caspase-1 and NLRP3 decreased significantly, and the mRNA expression of GSDMD reduced while the protein level significantly reduced. Conclusion HQGP improves myocardial injury in AA rats by inhibiting miR-21/TLR4 signalling through up-regulation of lncRNA GAS5, inhibiting pyroptosis, and reducing pro-inflammatory cytokine expression.