RESUMO
OBJECTIVE: The aim of this study was to unravel mechanisms whereby deficiency of the transcription factor Id3 (inhibitor of differentiation 3) leads to metabolic dysfunction in visceral obesity. We investigated the impact of loss of Id3 on hyaluronic acid (HA) production by the 3 HAS isoenzymes (HA synthases; -1, -2, and -3) and on obesity-induced adipose tissue (AT) accumulation of proinflammatory B cells. Approach and Results: Male Id3-/- mice and respective wild-type littermate controls were fed a 60% high-fat diet for 4 weeks. An increase in inflammatory B2 cells was detected in Id3-/- epididymal AT. HA accumulated in epididymal AT of high-fat diet-fed Id3-/- mice and circulating levels of HA were elevated. Has2 mRNA expression was increased in epididymal AT of Id3-/- mice. Luciferase promoter assays showed that Id3 suppressed Has2 promoter activity, while loss of Id3 stimulated Has2 promoter activity. Functionally, HA strongly promoted B2 cell adhesion in the AT and on cultured vascular smooth muscle cells of Id3-/- mice, an effect sensitive to hyaluronidase. CONCLUSIONS: Our data demonstrate that loss of Id3 increases Has2 expression in the epididymal AT, thereby promoting HA accumulation. In turn, elevated HA content promotes HA-dependent binding of B2 cells and an increase in the B2 cells in the AT, which contributes to AT inflammation.
Assuntos
Tecido Adiposo/metabolismo , Linfócitos B/metabolismo , Hialuronan Sintases/metabolismo , Ácido Hialurônico/biossíntese , Proteínas Inibidoras de Diferenciação/metabolismo , Paniculite/metabolismo , Tecido Adiposo/imunologia , Animais , Linfócitos B/imunologia , Adesão Celular , Células Cultivadas , Técnicas de Cocultura , Dieta Hiperlipídica , Modelos Animais de Doenças , Hialuronan Sintases/genética , Proteínas Inibidoras de Diferenciação/genética , Macrófagos/imunologia , Macrófagos/metabolismo , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Músculo Liso Vascular/imunologia , Músculo Liso Vascular/metabolismo , Miócitos de Músculo Liso/imunologia , Miócitos de Músculo Liso/metabolismo , Paniculite/genética , Paniculite/imunologia , Fenótipo , Transdução de Sinais , Regulação para CimaRESUMO
Cardiovascular diseases (CVDs) contribute to a large part of worldwide mortality. Similarly, two of the major risk factors for these diseases, aging and obesity, are also global problems. Aging, the gradual decline of body functions, is non-modifiable. Obesity, a modifiable risk factor for CVDs, also predisposes to type 2 diabetes mellitus (T2DM). Moreover, it affects not only the vasculature and the heart but also specific fat depots, which themselves have a major impact on the development and progression of CVDs. Common denominators of aging, obesity, and T2DM include oxidative stress, mitochondrial dysfunction, metabolic abnormalities such as altered lipid profiles and glucose metabolism, and inflammation. Several plant substances such as curcumin, the major active compound in turmeric root, have been used for a long time in traditional medicine and for the treatment of CVDs. Newer mechanistic, animal, and human studies provide evidence that curcumin has pleiotropic effects and attenuates numerous parameters which contribute to an increased risk for CVDs in aging as well as in obesity. Thus, curcumin as a nutraceutical could hold promise in the prevention of CVDs, but more standardized clinical trials are required to fully unravel its potential.