Nigella sativa Linn. seed extract modulates the activity of ASC complex of NLRP3 inflammasome in rats subjected to experimental pancreatitis

NLRP3 inflammasome, a multi-protein complex containing ASC as a linker protein influences the process of inflammation and tissue injury in pancreas. In this study, the effect of methanolic seed extract of Nigella sativa (MENS) on the expression of ASC protein of NLRP3 inflammasome was investigated in rats subjected to experimental pancreatitis. Male albino Wistar rats were divided into 4 groups. Group 1 and 2 rats were fed with normal diet; group 3 and 4 rats were administered with ethanol (EtOH) and fed high fat diet (HFD) for 90 days. In addition, group 2 and 4 rats were administered orally with 200 mg/kg body weight of MENS for the last 60 days. We measured serum lipase and amylase activities, oxidative stress markers and inflammatory markers. The mRNA expression of caspase-1, ASC, pro-inflammatory cytokines, IL-1β, IL-18, TNF-α and protein expression of caspase-1 and ASC were determined in pancreas. Our study indicated that MENS co-administration significantly decreased the level of serum lipase and amylase activities, oxidative stress markers and inflammatory markers in EtOH and HFD fed rats. mRNA and protein level expression of caspase-1 and ASC were found to be downregulated in MENS co-administered rats. Spearman's rank correlation test showed that ASC mRNA expression has significant positive correlation with the serum levels of caspase-1 (r_s = 0.885, P < 0.01), IL-1β (r_s = 0.828, P < 0.05) and IL-18 (r_s = 0.943, P = 0.01) in MENS co-administered rats. The present study showed that MENS exhibits anti-inflammatory activity probably by downregulating the expression of ASC protein of NLRP3 inflammasome in pancreas to minimize the activation of caspase-1.