Inhibition of TREM-1 attenuates inflammation and lipid accumulation in diet-induced nonalcoholic fatty liver disease.

Abstract

In the liver tissues of obese diabetic or nondiabetic patients, triggering receptor expressed on myeloid cells‐1 (TREM‐1) is usually found to be upregulated, thus leading to upregulation of various inflammatory cytokines and lipid accumulation. On the other hand, nonalcoholic fatty liver disease (NAFLD), characterized by excess lipid accumulation, and inflammatory injury in liver, is becoming an epidemic disease, globally. In the present study, we aimed to investigate the biological role and the underlying mechanisms of TREM‐1 in NAFLD. upregulation of TREM‐1 occurred in high‐fat diet (HFD)‐induced mice NAFLD model and oleic acid‐treated HepG2 and primary mouse hepatocytes cell model at messenger RNA and protein levels. Functional studies established that overexpression of TREM‐1 displayed hyperlipidemia, and increased in inflammatory indicators and lipid accumulation‐related genes, which was ameliorated by knockdown of TREM‐1. Our results also showed that obvious lipid accumulation and inflammatory injury occurred in the liver tissue of HFD‐fed mice, while treatment with lentiviral vector short hairpin TREM showed marked improvement in tissue morphology and architecture and less lipid accumulation, thus deciphering the mechanism through which knockdown of TREM‐1 ameliorated the inflammatory response and lipid accumulation of NAFLD mice through inactivation of the nuclear factor‐κB (NF‐κB) and PI3K/AKT signal pathways, respectively. In conclusion, TREM‐1/NF‐κB and TREM‐1/PI3K/AKT axis could be an important mechanism in ameliorating the inflammatory response and lipid accumulation, respectively, thus shedding light on the development of novel therapeutics to the treatment of NAFLD.