krn-7000 and Obesity

Although natural killer T cells (NKT cells) are altered in obese asthmatic mice, their function remains completely unclear. To further explore the potential mechanism of NKT cells in airway inflammation of obesity-associated asthma, we examined the effects of α-galactosylceramide (KRN7000) on airway inflammation in obese asthmatic mice. Male C57BL/6J mice were divided into five groups: (1) control; (2) asthma; (3) A + KRN, asthma with KRN7000; (4) obese asthma; and (5) OA + KRN, obese asthma with KRN7000. Cytometric bead array (CBA) was used to detect interleukin-4 (IL-4), IL-10, tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ) in the serum. Flow cytometry was used to detect NKT cells and CD69

Topics: Adjuvants, Immunologic; Animals; Asthma; Diet, High-Fat; Galactosylceramides; Inflammation Mediators; Killer Cells, Natural; Male; Mice; Mice, Inbred C57BL; Obesity; Ovalbumin

The role of iNKT cells was investigated in chronic adipose tissue inflammation in obese mice after administration of α-GalCer in different pathways.. C57BL/6J mice were fed high-fat diet (HFD) for 12 weeks to establish the obese mouse model. The pathology of adipose tissue was observed by H&E staining. The rates of iNKT cells, macrophages and cell subsets in adipose tissue were detected by FCM. Cytokine levels in serum and adipose tissue lymphocyte-stimulated supernatants were assessed with the CBA kit. The expression levels of related transcription factor in adipose tissue were detected by Western blot.. The proportions of iNKT cells, iNKT10 cells and M2 macrophages were decreased, while those of iNKT1 and M1 macrophages were increased in adipose tissue of HFD-fed mice. The expression levels of the related transcriptional proteins E4BP4 and Arg-1 were decreased while iNOS expression was increased in adipose tissue. Administration of α-GalCer by subcutaneous injection resulted in increased rates of iNKT10 cells and M2 macrophages, and decreased amounts of M1 macrophages in adipose tissue of HFD-fed mice. The expression of E4BP4 and Arg-1 were up-regulated, but iNOS was down-regulated. Meanwhile, infiltration of inflammatory cells into adipose tissue was further reduced.. The imbalance between the proportions of iNKT1 and iNKT10 cells may be involved in the development of chronic inflammation in obese adipose tissue. Administration of α-GalCer by subcutaneous injection in HFD-fed mice activates adipose tissue iNKT10 cells, which promote M2 macrophage polarization and improve chronic inflammation in obese adipose tissue.

Topics: Adipocytes; Adipose Tissue; Animals; Basic-Leucine Zipper Transcription Factors; Diet, High-Fat; Disease Models, Animal; Galactosylceramides; Inflammation; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Obese; Nitric Oxide Synthase Type II; Obesity

It has been shown that CD1d expression and glycolipid-reactive, CD1d-restricted NKT cells exacerbate the development of obesity and insulin resistance in mice. However, the relevant CD1d-expressing cells that influence the effects of NKT cells on the progression of obesity remain incompletely defined. In this study, we have demonstrated that 3T3-L1 adipocytes can present endogenous ligands to NKT cells, leading to IFN-γ production, which in turn, stimulated 3T3-L1 adipocytes to enhance expression of CD1d and CCL2, and decrease expression of adiponectin. Furthermore, adipocyte-specific CD1d deletion decreased the size of the visceral adipose tissue mass and enhanced insulin sensitivity in mice fed a high-fat diet (HFD). Accordingly, NKT cells were less activated, IFN-γ production was significantly reduced, and levels of adiponectin were increased in these animals as compared with control mice on HFD. Importantly, macrophage recruitment into the adipose tissue of adipocyte-specific CD1d-deficient mice was significantly blunted. These findings indicate that interactions between NKT cells and CD1d-expressing adipocytes producing endogenous NKT cell ligands play a critical role in the induction of inflammation and functional modulation of adipose tissue that leads to obesity.

Topics: 3T3-L1 Cells; Adipocytes; Adiponectin; Animals; Antigen Presentation; Antigens, CD1d; B7-1 Antigen; Diet, High-Fat; Disease Models, Animal; Disease Progression; Galactosylceramides; Insulin Resistance; Interferon-gamma; Lymphocyte Activation; Macrophage Activation; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Transgenic; Natural Killer T-Cells; Obesity

Obesity triggers a low-grade systemic inflammation, which plays an important role in the development of obesity-associated metabolic diseases. In searching for links between lipid accumulation and chronic inflammation, we examined invariant natural killer T (iNKT) cells, a subset of T lymphocytes that react with lipids and regulate inflammatory responses. We show that iNKT cells respond to dietary lipid excess and become activated before or at the time of tissue recruitment of inflammatory leukocytes, and that these cells progressively increase proinflammatory cytokine production in obese mice. Such iNKT cells skew other leukocytes toward proinflammatory cytokine production and induce an imbalanced proinflammatory cytokine environment in multiple tissues. Further, iNKT cell deficiency ameliorates tissue inflammation and provides protection against obesity-induced insulin resistance and hepatic steatosis. Conversely, chronic iNKT cell stimulation using a canonical iNKT cell agonist exacerbates tissue inflammation and obesity-associated metabolic disease. These findings place iNKT cells into the complex network linking lipid excess to inflammation in obesity and suggest new therapeutic avenues for obesity-associated metabolic disorders.

Topics: Adipose Tissue, White; Animals; Antigens, CD1d; CD8-Positive T-Lymphocytes; Cells, Cultured; Cytokines; Dietary Fats; Fatty Liver; Female; Flow Cytometry; Galactosylceramides; Inflammation; Inflammation Mediators; Insulin Resistance; Lipids; Lymphocyte Activation; Macrophages; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Natural Killer T-Cells; Obesity

CD1d-restricted natural killer T (NKT) cells and CD4+CD25+ regulatory T (Treg) cells are two thymus-derived subsets of regulatory T cells that play an important role in the maintenance of self-tolerance. Yet the functional changes of the two subsets of regulatory T cells in the development of diabetes in non-obese diabetic (NOD) mice remain unclear, and how NKT cells and CD4+CD25+ Treg cells cooperate functionally in the regulation of autoimmune diabetes is also uncertain. We provide evidence that in NOD mice, an animal model of human type 1 diabetes, the functions of both NKT cells and CD4+CD25+ Treg cells decrease in an age-dependent manner. We show that treatment with alpha-galactosylceramide increases the size of the CD4+CD25+ Treg cell compartment in NOD mice, and augments the expression of forkhead/winged helix transcription factor and the potency of CD4+CD25+ Treg cells to inhibit proliferation of CD4+CD25- T cells. Our data indicate that NKT cells and CD4+CD25+ Treg cells might cooperate in the prevention of autoimmune diabetes in NOD mice treated with alpha-galactosylceramide. Induced cooperation of NKT cells and CD4+CD25+ Treg cells could serve as a strategy to treat human autoimmune disease, such as type 1 diabetes.

Topics: Aging; Animals; Cell Communication; Cells, Cultured; Diabetes Mellitus, Type 1; Female; Galactosylceramides; Killer Cells, Natural; Mice; Mice, Inbred NOD; Obesity; T-Lymphocytes, Regulatory

The liver regulates lipid homeostasis and is enriched with natural killer T (NKT) cells that respond to lipid antigens. Optimal maturation and activation of NKT cells requires their interaction with lipid antigens that are presented by cluster of differentiation-1 (CD-1) molecules on antigen-presenting cells. Hepatocytes express CD1d and present lipid antigens to NKT cells. Depletion and dysregulation of hepatic NKT cells occurs in mice with fatty livers. Herein, we assess whether reduced CD1d content on steatotic hepatocytes contributes to fatty liver-associated NKT cell abnormalities. We show that despite expressing normal levels of CD1d mRNA, fatty hepatocytes from ob/ob mice have significantly less CD1d on their plasma membranes than normal hepatocytes. This has functional significance because ob/ob hepatocytes are less able to activate CD1d-restricted T-cell responses in vitro, and CD1d-reactive NKT cells are reduced in ob/ob livers. Events in the endoplasmic reticulum (ER) normally regulate CD1d trafficking to plasma membranes. Hepatic steatosis has been associated with ER stress. To determine if ER stress reduces CD-1 accumulation on hepatocytes, we evaluated hepatic ER stress in ob/ob mice and treated cultured hepatocytes and lean mice with tunicamycin to induce ER stress. Lipid accumulation and ER stress occurred in the livers of both ob/ob and tunicamycin-treated mice. Tunicamycin caused dose-dependent decreases in hepatocyte CD1d, inhibited hepatocyte activation of CD1d-restricted T-cell responses, depleted liver populations of CD1d-reactive NKT cells and promoted Th-1 polarization of hepatic cytokine production. In conclusion, ER stress-related decreases in hepatocyte CD1d contribute to NKT cell dysregulation in fatty livers.

Topics: Animals; Antigens, CD1; Antigens, CD1d; Cells, Cultured; Disease Models, Animal; Endoplasmic Reticulum; Fatty Liver; Galactosylceramides; Hepatocytes; Immunity, Innate; Killer Cells, Natural; Male; Mice; Obesity