Obesity induces phenotypic switching of gastric smooth muscle cells through the activation of the PPARD/PDK4/ANGPTL4 pathway

Abstract

ObjectiveClinical research has identified stomach dysmotility as a common feature of obesity. However, the specific mechanisms driving gastric emptying dysfunction in patients with obesity remain largely unknown. In this study, we investigated potential mechanisms by focusing on the homeostasis of gastric smooth muscle, using tissue samples from both patient and mice, as well as human cell culture system. DesignTissue samples were collected from patients who underwent sleeve gastrectomy for obesity, as well as from control subjects with standard weight who were undergoing treatment for gastric or esophageal carcinoma. Stomach tissues were harvested from mice after 12 weeks on a High-Fat Diet (HFD). Differentiated human gastric smooth muscle cells (SMCs) were treated with lipids, siRNA-peptide-based nanoparticles and/or pharmaceutical compounds. All experimental conditions were analyzed for their effects on SMC differentiation using stage-specific smooth muscle markers. Additionally, lipidomic and RNA sequencing analyses were performed on human gastric SMC cultures. The findings were assessed in patients with obesity to evaluate their clinical relevance. ResultsThe smooth muscle layers in gastric tissue from both patients with obesity and mice fed on a HFD exhibited altered differentiation status. Treatment of differentiated human gastric SMCs with lipids phenocopies these alterations and is associated with increased expression of PDK4 and ANGPTL4. Inhibition of PDK4 or ANGPTL4 upregulation prevents these lipid-induced modifications. Mechanistically, lipid treatment activates PPARD, which regulates PDK4 and ANGPTL4 upregulation, leading to SMC dedifferentiation. Notably, PDK4 and ANGPTL4 levels correlate with immaturity and alteration of gastric smooth muscle in patients with obesity. ConclusionObesity triggers a phenotypic change in gastric SMCs, driven by the activation of the PPARD/PDK4/ANGPTL4 pathway. These mechanistic insights offer potential biomarkers for diagnosing stomach dysmotility in patients with obesity.