RESUMO
The activation of Kupffer cells (KCs) and monocyte-derived recruited macrophages (McMΦs) in the liver contributes to obesity-induced insulin resistance and type 2 diabetes. Mice with diet-induced obesity (DIO mice) treated with chromogranin A peptide catestatin (CST) showed several positive results. These included decreased hepatic/plasma lipids and plasma insulin, diminished expression of gluconeogenic genes, attenuated expression of proinflammatory genes, increased expression of anti-inflammatory genes in McMΦs, and inhibition of the infiltration of McMΦs resulting in improvement of insulin sensitivity. Systemic CST knockout (CST-KO) mice on normal chow diet (NCD) ate more food, gained weight, and displayed elevated blood glucose and insulin levels. Supplementation of CST normalized glucose and insulin levels. To verify that the CST deficiency caused macrophages to be very proinflammatory in CST-KO NCD mice and produced glucose intolerance, we tested the effects of (sorted with FACS) F4/80+Ly6C- cells (representing KCs) and F4/80-Ly6C+ cells (representing McMΦs) on hepatic glucose production (HGP). Both basal HGP and glucagon-induced HGP were markedly increased in hepatocytes cocultured with KCs and McMΦs from NCD-fed CST-KO mice, and the effect was abrogated upon pretreatment of CST-KO macrophages with CST. Thus, we provide a novel mechanism of HGP suppression through CST-mediated inhibition of macrophage infiltration and function.
Assuntos
Cromogranina A/farmacologia , Glucose/metabolismo , Resistência à Insulina , Células de Kupffer/efeitos dos fármacos , Fígado/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Obesidade/metabolismo , Fragmentos de Peptídeos/farmacologia , Animais , Cromogranina A/genética , Regulação da Expressão Gênica/efeitos dos fármacos , Regulação da Expressão Gênica/imunologia , Glucagon/farmacologia , Gluconeogênese/efeitos dos fármacos , Gluconeogênese/genética , Hormônios/farmacologia , Inflamação/imunologia , Insulina/metabolismo , Células de Kupffer/imunologia , Metabolismo dos Lipídeos/efeitos dos fármacos , Fígado/imunologia , Fígado/metabolismo , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Knockout , Obesidade/imunologia , Fragmentos de Peptídeos/genéticaRESUMO
The obesity epidemic is the underlying driver of the type 2 diabetes mellitus epidemic. A remarkable accumulation of various pro-inflammatory immune cells in adipose tissues is a hallmark of obesity and leads to pathogenesis of tissue inflammation and insulin resistance. Here, we describe a detailed protocol to isolate adipose tissue stromal vascular cells (SVCs), which enrich various immune cells of adipose tissues. These SVCs can be used to examine the population and activation status of immune cells by tracking their cell surface antigens, gene expression, and activation of specific signaling pathways.
