Mitigation of lipopolysaccharide-induced intestinal injury in rats by Chimonanthus nitens Oliv. essential oil via suppression of mitochondrial fusion protein mitofusin 2 (MFN2)-mediated mitochondrial-associated endoplasmic reticulum membranes (MAMs) formation

Abstract

Ethnopharmacological relevanceChimonanthus nitens Oliv. is a traditional Chinese medicine with anti-inflammatory and antioxidant properties that has commonly been used for colds, fevers, and other diseases. However, its role and specific mechanism in sepsis-associated intestinal injury have not been reported. Aim of the studyC. nitens Oliv. essential oil (CEO), an organic active compound extracted from the traditional Chinese medicine C. nitens Oliv. exhibits notable anti-inflammatory and antioxidant properties. Nevertheless, the therapeutic potential of CEO for septic intestinal injury remains undocumented. This study thus aims to elucidate the anti-inflammatory and antioxidant effects of CEO in the context of acute intestinal injury and to investigate its mechanisms of action in septic rats. Materials and methodsCell and animal models were established using LPS to investigate the impact of CEO on LPS-induced intestinal pathological injury and the secretion of inflammatory factor IL-1β. The effects of CEO on the expression of NLRP3, caspase-1, and MFN2, p-p65 protein were also examined, as well as its influence on oxidative stress injury and mitochondrial-associated endoplasmic reticulum membrane (MAM) formation. Generation of an MFN2 knockout IEC-6 cell line allowed comprehensive investigation of the protective mechanism of CEO. ResultsIn rat models, CEO reduced IL-1β secretion, inhibited caspase-1, ZO-1 expression and NF-κB p65 phosphorylation, while also decreasing malondialdehyde levels and enhancing superoxide dismutase activity in intestinal tissues. Cellular experiments demonstrated its ability to decrease IL-1β secretion; NLRP3, caspase-1, and MFN2 expression; NF-κB p65 phosphorylation; reactive oxygen species (ROS) production, and mitochondrial dysfunction. MFN2 knockdown enhanced these effects synergistically with CEO, indicating potential therapeutic synergy. Further, MFN2 knockdown significantly mitigated LPS-induced NLRP3 and caspase-1 expression, IL-1β secretion, ROS production, NF-κB p65 phosphorylation and MMP reduction in IEC-6 cells, while inhibiting MAM formation and NLRP3 localization on MAMs. Importantly, MFN2 downregulation and CEO synergistically reduced LPS-induced IL-1β secretion and ROS production while inhibiting MAM formation in IEC-6 cells, thus inhibiting NLRP3 inflammasome activation. ConclusionCEO mitigates inflammation and oxidative stress by inhibiting MAM formation and is thus a promising intervention for septic intestinal injury.