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A novel function of adipocytes in lipid antigen presentation to iNKT cells.

ABSTRACT: Systemic low-grade chronic inflammation has been intensively investigated in obese subjects. Recently, various immune cell types, such as macrophages, granulocytes, helper T cells, cytotoxic T cells, and B cells, have been implicated in the pathogenesis of adipose tissue inflammation. However, the roles of invariant natural killer T cells (iNKT cells) and the regulation of iNKT cell activity in adipose tissue are not thoroughly understood. Here, we demonstrated that iNKT cells were decreased in number in the adipose tissue of obese subjects. Interestingly, CD1d, a molecule involved in lipid antigen presentation to iNKT cells, was highly expressed in adipocytes, and CD1d-expressing adipocytes stimulated iNKT cell activity through physical interaction. iNKT cell population and CD1d expression were reduced in the adipose tissue of obese mice and humans compared to those of lean subjects. Moreover, iNKT cell-deficient J?18 knockout mice became more obese and exhibited increased adipose tissue inflammation at the early stage of obesity. These data suggest that adipocytes regulate iNKT cell activity via CD1d and that the interaction between adipocytes and iNKT cells may modulate adipose tissue inflammation in obesity.

SUBMITTER: Huh JY

PROVIDER: S-EPMC3554106 | biostudies-literature | 2013 Jan

REPOSITORIES: biostudies-literature

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A novel function of adipocytes in lipid antigen presentation to iNKT cells.

Huh Jin Young JY Kim Jong In JI Park Yoon Jeong YJ Hwang In Jae IJ Lee Yun Sok YS Sohn Jee Hyung JH Lee Sung Kyu SK Alfadda Assim A AA Kim Su Sung SS Choi Sung Hee SH Lee Dong-Sup DS Park Se-Ho SH Seong Rho Hyun RH Choi Cheol Soo CS Kim Jae Bum JB

Molecular and cellular biology 20121112 2

Systemic low-grade chronic inflammation has been intensively investigated in obese subjects. Recently, various immune cell types, such as macrophages, granulocytes, helper T cells, cytotoxic T cells, and B cells, have been implicated in the pathogenesis of adipose tissue inflammation. However, the roles of invariant natural killer T cells (iNKT cells) and the regulation of iNKT cell activity in adipose tissue are not thoroughly understood. Here, we demonstrated that iNKT cells were decreased in ...[more]

PMID: 23149942

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Project description:Background/objectivesAlthough obesity is associated with low-grade inflammation and metabolic disorders, clinical studies suggested some obese people were metabolically healthy with smaller adipocyte size compared with metabolically abnormal obese (MAO). This indicated adipocyte size may be an important predictor underlay the distinction between MAO and metabolically healthy obese. As recent study has shown that adipocytes expressed class II major histocompatibility complex (MHCII), which functioned as APCs during obesity. However, the relationship between adipocyte hypertrophy and MHCII expression was not involved. Here we hypothesize that hypertrophic adipocytes could be associated with upregulating MHCII to influence adipose tissue metabolism.MethodsAdipocytes were sorted by fluorescence-activated cell sorting (FACS) according to the cell size from MAO mice. The activation of MHCII, T cells and related signaling molecules were examined by FACS, ELISA and western blotting. 3T3-L1 cell line and primary adipocytes were used to examine the effect of free fatty acids (FFA) on adipocytes enlargement and MHCII expression.ResultsMAO mice had a significant increase in adipocytes size and FFA concentration. The large adipocytes from both obese and non-obese mice expressed higher levels of MHCII than small adipocytes. Importantly, large adipocytes from obese mice stimulated CD4(+) T cells to secrete more interferon (IFN)-?. Furthermore, the activation of the JNK-STAT1 pathway was involved in upregulation of MHCII in large adipocytes. In vitro FFA treatment promoted adipocyte hypertrophy and expression of MHCII-associated genes.ConclusionsThis study demonstrates that large adipocytes highly express MHCII and function as APC to stimulate IFN-?-expressing CD4(+) T cells, in which FFA may have important roles before IFN-? elevated. These findings suggest that adipocyte hypertrophy, rather than overall obesity, is the major contributor to adipose tissue inflammation and insulin resistance.

Dataset Information

A novel function of adipocytes in lipid antigen presentation to iNKT cells.

Publications

A novel function of adipocytes in lipid antigen presentation to iNKT cells.

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