In addition, repeated injections of ␣-GalCer or the related glycolipid OCH to apolipoprotein E knockout (apoE ؊/؊ ) mice during the early phase of atherosclerosis significantly enlarged the lesion areas compared with mice injected with vehicle control. However, administering ␣-GalCer to apoE ؊/؊ mice with established lesions did not significantly increase the lesion area but considerably decreased the collagen content. Atherosclerosis development in either AD-fed WT or apoE ؊/؊ mice was associated with the presence of V␣14J␣18 transcripts in the atherosclerotic arterial walls, indicating that NKT cells were recruited to these lesions. Thioglycolate-elicited macrophages pulsed with oxidized low-density lipoproteins expressed enhanced CD1d levels and induced NKT cells to produce interferon-␥, a potentially proatherogenic T-helper 1 (T H 1) cytokine. Collectively, we conclude that NKT cells are proatherogenic in mice. IntroductionAtherosclerosis is an inflammatory vascular disease that involves components of the innate and acquired immune systems. [1][2][3] Several studies have suggested that lymphocytes, which are detected in atherosclerotic lesions in humans and mice, 4,5 play a proatherogenic role. [6][7][8] Recently, the role of distinct lymphocyte subsets in the development of atherosclerosis has been evaluated. For example, emerging evidence indicates that T-helper 1 (T H 1) cells are proatherogenic, 9 whereas T H 2 cells are antiatherogenic. 10,11 These observations are further supported by the finding that T H 1 cytokines (eg,) are important in the progression of atherosclerosis [12][13][14][15] and that, among T H 2 cytokines, IL-10 is antiatherogenic. 16 On the other hand, recent studies have suggested that B cells play a protective role in atherogenesis. 17,18 Natural killer T (NKT) cells are a unique subset of lymphocytes that have surface markers and functions of T cells and NK cells. [19][20][21][22][23] Several characteristics of NKT cells suggest that they may play a role in the atherogenic process. Most NKT cells express an invariant V␣14J␣18 T-cell receptor (TCR)-V␣ chain paired with a restricted set of TCR-V␤ chains. These classical NKT cells recognize lipid antigens presented by the major histocompatibility complex (MHC) class 1-like molecule CD1d, produce copious amounts of IFN-␥ and IL-4 on activation, 22 and constitutively express Fas-ligand. 23 Moreover, NKT cells play a protective role in several autoimmune diseases, infections, and tumor progression/ metastasis. 20 Protective effects of NKT cells and their ligands in autoimmunity are largely attributed to their capacity to promote T H 2 immune responses. 24,25 However, in some situations, NKT cells can contribute to the development of T H 1 immune responses as well. 26 Therefore, it was difficult to predict whether NKT cells would play a proatherogenic or an antiatherogenic role. 2 To date, few studies have investigated the role of CD1d and CD1d-dependent T cells in atherogenesis. CD1d-expressing cells are present in human atherosclerotic...

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Abstract. Allograft inflammatory factor (AIF)-1, originally cloned from a rat heart allograft under chronic rejection, is induced in various inflammatory conditions including atherosclerosis. Using mouse AIF-1 transfected macrophages and AIF-1 transgenic (AIF-1 Tg ) mice, we analyzed the influence of AIF-1 overexpression on macrophage phagocytosis and the development of atherosclerosis. The AIF-1 transfectants showed significantly increased phagocytosis of latex beads and E. coli BioParticles as well as incorporation of acetylated low-density lipoprotein (LDL) compared to those of vector controls. Concordant results were obtained with elicited peritoneal exudate cells from AIF-1 Tg mice. When AIF-1 Tg mice were crossbred with apolipoprotein E knockout mice (ApoE -/-), these AIF-1 Tg ApoE -/-mice developed significantly increased atherosclerotic lesions compared to ApoE -/-mice. These results suggest that enhanced AIF-1 expression leads to augmented incorporation of degenerated LDL by macrophages and promotes development of atherosclerotic vasculopathy.

Hypertension is an important risk factor for coronary atherosclerosis, which is accelerated by inflammation and diminished fibrinolysis. We have previously shown that levels of plasminogen activator inhibitor-1 (PAI-1), the major physiologic inhibitor of fibrinolysis, are increased with atherogenic metabolic derangement.Because the liver is one of the major sources of circulating PAI-1, we here examined the effects of two proin- major physiologic inhibitor of fibrinolysis, may play a pivotal role in the deposition of fibrin in the affected vessels. We have previously reported that circulating PAI-1 levels were increased in an animal model of atherogenic metabolic derangement (3). Liver is one of the major sources of circulating PAI-1 (4) and insulin stimulates PAI-1 synthesis in liver cells (5), suggesting that the insulin resistance and subsequent hyperinsulinemia typically seen in hypertensives may contribute to a prothrombotic risk state.

SUMMARYThe expression of allograft in¯ammatory factor-1 (AIF-1) in 2,4,6-trinitrobenzene sulphonic acid (TNBS)-induced colitis, a model for T helper 1 (Th1) type disease, was investigated in BALB/c mice. The AIF-1 expression was signi®cantly increased in the colitis lesion compared to that in the normal colon. We then prepared AIF-1 transgenic mice (Tgm) with the BALB/c background that express high levels of AIF-1 in lymphoid tissues and the colon. When AIF-1 Tgm were administrated TNBS, the TNBS-induced colitis was ameliorated compared with that in non-transgenic littermates. The amelioration of colitis was associated with the low expression of interleukin-1b in the colon. The present ®ndings suggest that AIF-1 regulates Th1-type in¯ammatory responses.