Macrophage-Specific Progranulin Deficiency Prevents Diet-Induced Obesity through the Inhibition of Hypothalamic and Adipose Tissue Inflammation

Le résumé fourni par la source

BACKGRUOUND: Chronic low-grade inflammation in multiple metabolic organs contributes to the development of insulin resistance induced by obesity. Progranulin (PGRN) is an evolutionarily-conserved secretory protein implicated in immune modulation. The generalized deletion of the PGRN-encoded Grn gene improves insulin resistance and glucose intolerance in obese mice fed a high-fat diet (HFD). However, it remains unclear which cells or organs are responsible for the beneficial metabolic effect of Grn depletion. METHODS: Considering the critical role of macrophages in HFD-induced obesity and inflammation, we generated mice with a macrophage-specific Grn depletion (Grn-MΦKO mice) by mating lysozyme M (LysM)-Cre and Grn-floxed mice. Body weight, food intake, energy expenditure, and glucose and insulin tolerance were compared between Grn-MΦKO mice and their wildtype (WT) controls under normal chow diet (NCD)- or HFD-fed conditions. We also examined macrophage activation and inflammation- related gene expression in the visceral adipose tissue and hypothalamus along with insulin and leptin signaling. RESULTS: Grn-MΦKO mice showed no alteration in metabolic phenotypes under NCD-fed conditions. However, upon HFD feeding, these mice exhibited less weight gain and improved glucose and insulin tolerance compared to WT mice. Moreover, HFD-induced macrophage activation and proinflammatory cytokine expression were significantly reduced in both the adipose tissue and hypothalamus of Grn-MΦKO mice, while HFD-induced impairments in leptin and insulin signaling showed improvement. CONCLUSION: Macrophage-derived PGRN and possibly other Grn products play a critical role in the development of HFD-induced obesity, tissue inflammation, and impaired hormonal signaling in both central and peripheral metabolic organs.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.