Mechanism of Rhubarb Tangluo Pills Regulating NLRP3/Caspase-1/GSDMD Pathway to Ameliorate Inflammatory Injury in Large Vessels of Diabetic Rats

OBJECTIVE To clarify the interventional effects of Rhubarb Tangluo pills on macrovascular injury in diabetic rats and to explore the specific mechanisms based on the NLRP3/Caspase-1/GSDMD pathway mediating inflammatory injury.

METHODS  Forty SPF-grade 9-week-old ZDF(purebred fa/fa) rats were selected for the experiment, and the diabetic rats model was induced by Purina#5008 chow for 3 weeks after 1 week of acclimatization feeding, and then randomly divided into model control group, metformin group(0.18 g·kg⁻¹), and high-, medium-, low-dose group of Rhubarb Tangluo pills(2.16, 1.08, 0.54 g·kg⁻¹) after the model was formed. Another 8 ZDF(heterozygous fa/+) rats of the same age were selected as blank control group, and the body mass and fasting blood glucose of the rats were measured after 12 weeks of intervention. The plasma levels of TC, TG, LDL-c and HDL-c were detected using an automatic biochemical analyzer; the pathomorphological changes of rat vascular tissues were observed using HE staining; the serum levels of IL-1β and IL-18 were detected using ELISA; and the expression levels of NLRP3, ASC, Caspase-1 and GSDMD protein and mRNA expression level were detected by Western blotting and RT-qPCR techniques.

RESULTS  Compared with the blank control group, rats in the model control group showed significantly higher body mass and fasting glucose content(P<0.05), significantly higher TC, TG, LDL-c content(P<0.05), significantly lower HDL-c content(P<0.05), irregular cell arrangement and cell vacuoles in the vasculature, thickening of vascular endothelium, and significant increase in the content of IL-1β, IL-18(P<0.05), increased expression of NLRP3, ASC, Caspase-1, GSDMD protein and mRNA(P<0.05). Compared with the model control group, body mass and fasting blood glucose of rats in the high- and medium-dose group of Rhubarb Tangluo pills and the metformin group were significantly reduced(P<0.05), TC, TG, LDL-c content was significantly increased(P<0.05), HDL-c content was significantly reduced(P<0.05), vascular pathological injury was improved to different degrees, and the content of serum inflammatory factors(IL-1β, IL-18) was significantly reduced(P<0.05), protein and mRNA expression of NLRP3, ASC, Caspase-1, GSDMD were significantly reduced(P<0.05). Compared with the low-dose group, the high-dose group of Rhubarb Tangluo pills showed more significant improvement(P<0.05).

CONCLUSION  Rhubarb Tangluo pills can significantly improve vascular injury in diabetic rats in a dose-dependent manner, and the specific mechanism is related to the inhibition of NLRP3/Caspase-1/GSDMD pathway by Rhubarb Tangluo pills to improve vascular inflammatory injury.