Methane-Rich Saline Suppresses ER-Mitochondria Contact and Activation of the NLRP3 Inflammasome by Regulating the PERK Signaling Pathway to Ameliorate Intestinal Ischemia‒Reperfusion Injury

Intestinal ischemia‒reperfusion (I/R) injury is a common pathological process in patients undergoing gastrointestinal surgery, leading to local intestinal damage and increased microvascular permeability, eventually causing extraintestinal multiple organ dysfunction or sepsis. The NLRP3-mediated inflammatory response is associated with I/R injury. Methane saline (MS) has anti-pyroptosis properties. This study aims to explore the protective effect of MS on intestinal I/R injury and its potential mechanisms. After MS pretreatment, the in vivo model was established by temporarily clipping the mouse superior mesentery artery with a noninvasive vascular clamp, and the in vitro model was established by OGD/R on Caco-2 cells. The results of HE and TUNEL staining showed intestinal barrier damage after I/R injury, which was consistent with the IHC staining results of tight junction proteins. Moreover, the expression of the NLRP3 signaling pathway was increased after I/R injury, and inhibition of NLRP3 activation reduced Caco-2 cell injury, indicating that NLRP3-mediated pyroptosis was one of the main forms of cell death after I/R injury. Subsequently, we found that MS treatment ameliorated intestinal barrier function after I/R injury by suppressing NLRP3-mediated pyroptosis. MS treatment also reduced mitochondria-associated membrane (MAM) formation, which was considered to be a platform for activation of the NLRP3 inflammasome. Importantly, MS reduced ER stress, which was related to the PERK signaling pathway. Knocking down PERK, a key protein involved in ER stress and MAM formation, reversed the protective effect of MS, indicating that MS suppressed NLRP3 by reducing ER stress and MAM formation. In conclusion, we believe that MS suppresses MAMs and activation of the NLRP3 inflammasome by regulating the PERK signaling pathway to ameliorate intestinal I/R injury.