Background-Macrophage and lymphocyte infiltration in adipose tissue may contribute to the pathogenesis of obesity-mediated metabolic disorders. Natural killer T (NKT) cells, which integrate proinflammatory cytokines, have been demonstrated in the atherosclerotic lesions and in visceral adipose tissue. Objective-To determine whether NKT cells are involved in glucose intolerance and adipose tissue inflammation in diet-induced obese mice. Methods and Results-To determine whether NKT cells are involved in the development of glucose intolerance, male ␤ 2 -microglobulin knockout (KO) mice lacking NKT cells and C57BL/6J (wild-type) mice were fed with a high-fat diet (HFD) for 13 weeks. Body weight and visceral obesity were comparable between wild-type and KO mice. However, macrophage infiltration was reduced in adipose tissue and glucose intolerance was significantly ameliorated in KO mice.To further confirm that NKT cells are involved in these abnormalities, ␣-galactosylceramide, 0.1 g/g body weight, which specifically activates NKT cells, was administered after 13 weeks of HFD feeding. ␣-Galactosylceramide significantly exacerbated glucose intolerance and macrophage infiltration as well as cytokine gene expression in adipose tissue. O besity, specifically visceral obesity, increases the risk for metabolic disorders, such as type 2 diabetes mellitus, dyslipidemia, and hypertension as well as atherosclerotic cardiovascular diseases. Previous studies have demonstrated that the accumulation of macrophages within adipose tissue is well documented in obese individuals and that adipose tissue inflammation plays an important role in the pathogenesis of these metabolic disorders. 1,2 Macrophages are attracted by chemokines, such as monocyte chemoattractant protein 1 (MCP-1), and contribute to local inflammation through the release of other inflammatory cytokines, such as tumor necrosis factor (TNF) ␣. In high-fat diet (HFD)-fed obese mice, it has been shown that infiltration of macrophages into adipose tissue coincides with the occurrence of obesitymediated metabolic disorders. 2 The important role of adipose tissue macrophages in the pathogenesis of metabolic disorders has further been supported by recent data in C-C motif chemokine receptor 2 (CCR2)-deficient mice. 3 The CCR2 Ϫ/Ϫ mice exhibited a reduction in adipose tissue macrophages in association with an improvement of glucose homeostasis and insulin sensitivity. However, the abolished monocyte and macrophage recruitment into peripheral tissue via interaction with MCP-1 could not completely inhibit HFD-mediated metabolic disorders, suggesting that other inflammatory cells may play a role in this context. Wu et al 4 and Rocha et al 5 demonstrated that CD3-positive T lymphocytes are present in human adipose tissue; and regulated upon activation, normal T cell expressed secreted (RANTES), a T-cell-specific chemokine, and its respective receptor CCR5 are expressed in adipose tissue from obese patients. However, the role of other types of lymphocytes in adipose tissue inflam...

Aim: Cardiovascular events associated with hypertension often involve thrombosis. Increased platelet activity is one of the risk factors of cardiovascular diseases. Antithrombotic properties of antihypertensive agents are not fully characterized. Angiotensin type 1 receptor blockers (ARBs) are widely used for the treatment of hypertension. Some ARBs can provoke antiaggregatory effects on platelets in vitro. Whether ARBs can inhibit platelet aggregation was tested in hypertensive patients in vivo. Methods: Platelet aggregation was assessed by the highly sensitive particle counting method using laser-light scattering.

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Introduction: Natural killer T (NKT) cells are a unique subset of T lymphocytes, which recognize glycolipids and integrate inflammation producing pro-inflammatory cytokines on activation. We have demonstrated that NKT cells are present in atherosclerotic lesions and play a pivotal role in atherogenesis. NKT cells also reside in visceral adipose tissues, however, their pathogenic role has not been studied in metabolic derangements. Methods and Results: To determine whether NKT cells are involved in the development of metabolic phenotypes, male β 2 microglobulin knockout (KO) mice, which lack T cells and NKT cells, and C57BL/6J (WT) mice were fed an western diet (WD) containing 21% fat and 0.15% cholesterol or a chow diet for 13 weeks. In both KO (n=14) and WT (n=10) mice fed WD, visceral adipose-tissue weight, adipose cell size, and plasma leptin and non-HDL cholesterol levels were significantly increased compared to those fed a chow ( p< 0.05) but did not differ between KO and WT mice. However, in KO mice fed WD, impaired glucose tolerance (plasma glucose 15 minutes after intraperitoneal glucose injection, 228±7 vs 343±31 mg/dl, p< 0.001) and microalbuminuria (urine albumin/creatinin ratio, 10±1 vs 24±2 μg/mg, p< 0.0001) were significantly ameliorated, but not in WT mice. Plasma TNF-α was significantly lower in KO mice than in WT mice (29±6 vs 85±40 pg/ml, p< 0.05). Immunohistochemical staining of visceral adipose tissues revealed that F4/80 (+) macrophages in KO mice were markedly reduced to 34% of those in WT mice ( p< 0.0001). To further confirm that NKT cells can aggravate metabolic derangements, WT mice received α-galactosylceramide (0.1μg/g), which specifically activates NKT cells, (αgC, n=5) or saline (PBS, n=5) injection after 13 weeks of feeding WD. In αgC mice, impaired glucose tolerance (347±9 vs 308±13 mg/dl, p< 0.05) and microalbuminuria (35±8 vs 17±1 μg/mg, p< 0.05) were significantly exacerbated as compared to PBS mice. Conclusions: NKT cells enhance chronic inflammation in visceral adipose tissues and contribute to the development of metabolic derangements in diet-induced obese mice. NKT cells may be novel therapeutic targets in the prevention of metabolic syndrome.