-
[show abstract]
[hide abstract]
ABSTRACT: Atherosclerosis has been recognized as an inflammatory disease of the arterial wall, involving innate and adaptive immunity. Effector T cells are differentiated from naïve T cells stimulated by antigen-presenting cells such as macrophages and dendritic cells (DCs) and play critical roles in atherogenesis. Accumulating evidence revealed that several subsets of regulatory T cells (Tregs) inhibit atherosclerotic lesion formation via inhibiting the inflammatory response of effector T cells. In addition, the contribution of DCs to atherogenesis has been demonstrated. DCs have different functions for either stimulating or inhibiting T cell function depending on their origin and maturation stage. In particular, immature DCs, which have potential for inducing Tregs and inhibiting effector T cells, are sometimes called 'tolerogenic DCs' and suppress immune responses. Epidemiological studies have highlighted the increasing prevalence of vitamin D(3) deficiency and its association with increased risks of cardiovascular diseases. Some studies have raised interest in the immunomodulatory properties of vitamin D(3) beyond its well-established role in bone and calcium metabolism. The active form of vitamin D(3) (calcitriol) induces Tregs and tolerogenic DCs, which are both involved in maintaining immunologic tolerance to self and harmless antigens. Interestingly, recent evidence suggested that DCs in the intestinal immune system are involved in inducing Tregs; modulating the function of DCs and Tregs in the intestinal immune system might have beneficial effects on atherosclerosis. In this review, we focus on the function of DCs in vascular diseases and discuss vitamin D(3) therapy for the prevention of atherosclerosis.
Journal of atherosclerosis and thrombosis 08/2012; · 2.69 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Atherosclerosis is believed to be an inflammatory condition of the arterial wall. It has become apparent that various types of cells of innate and adaptive immunity participate in atherogenesis. T cells are of particular interest because they mediate pathogenic immune responses involved in the acceleration of atherosclerosis. Recent studies from several independent groups indicated that subsets of regulatory T cells (Tregs) actively mediate immunologic tolerance and inhibit atherosclerosis development or progression through the down-regulation of effector T-cell responses. It is likely that there is an imbalance between pathogenic effector T cells and Tregs under atherosclerotic conditions. Recent evidence suggests that in addition to the thymus, gut-associated lymphoid tissues are the main sites for the generation of several subsets of peripherally inducible Tregs. This indicates that intervention in the gut environment to promote an endogenous regulatory immune response may serve as a possible therapeutic approach to suppress atherosclerotic diseases. In this review, we discuss not only the possible role of Tregs in the prevention of atherosclerosis, but also promising strategies to prevent or cure atherosclerotic diseases by promoting an endogenous regulatory immune response, particularly by oral immune modulation.
Journal of atherosclerosis and thrombosis 04/2012; 19(6):503-15. · 2.69 Impact Factor
-
Kenji Nakajima,
Tomoya Yamashita,
Tomoyuki Kita, Masafumi Takeda,
Naoto Sasaki,
Kazuyuki Kasahara,
Masakazu Shinohara,
Yoshiyuki Rikitake,
Tatsuro Ishida,
Mitsuhiro Yokoyama,
Ken-ichi Hirata
[show abstract]
[hide abstract]
ABSTRACT: Eicosapentaenoic acid (EPA) has been shown to have beneficial effects on cardiovascular diseases, although the precise mechanism is unknown. We investigated the effect of EPA on the regression of atherosclerosis.
LDL-receptor-deficient mice were fed a high-cholesterol diet for 8 weeks to build up aortic sinus atherosclerotic lesions and then were fed a normal diet with or without 5% EPA for 4 weeks. Atherosclerotic lesions were histologically assessed, and immunologic assays were performed. EPA treatment significantly regressed atherosclerosis (-22.7%, P<0.05) and decreased the content of macrophages, CD4(+) T cells, and dendritic cells (DCs) in atherosclerotic lesions, though only changing the chow never induced the regression. Flow cytometric analysis revealed that EPA increased immature DCs (CD11c(+) CD80(-) CD86(-)), increased the indoleamine 2,3-dioxygenase (IDO) in DCs, and decreased the number of CD4(+) T cells. In the presence of the IDO inhibitor, the beneficial effects of EPA on regression were inhibited, suggesting that the effect of EPA was mainly mediated through IDO.
In addition to lowering plasma cholesterol, EPA regressed atherosclerosis probably due to modulation of DC phenotype and reduction in T cell numbers. The present findings might partly explain the beneficial effects of EPA in clinics and support clinical evidence.
Arteriosclerosis Thrombosis and Vascular Biology 09/2011; 31(9):1963-72. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: We have applied an imaging system of phase-contrast X-ray CT to the detection of atherosclerotic plaque components by means of the differences of tissue mass densities. In this study, we investigated the effect of the anti-platelet therapies, widely used for secondly prevention of cardiovascular events, on plaque stability and examined whether this novel technique could detect the changes of plaque components under the therapy. Apolipoprotein E-deficient mice were fed on high-cholesterol diet alone and either with 0.1% cilostazol or clopidogrel for 10 weeks. We assessed atherosclerotic lesion volumes and components at brachiocephalic artery by the phase-contrast X-ray CT imaging and histochemistry. The phase-contrast X-ray CT imaging could reveal that cilostazol and clopidogrel significantly decreased atherosclerotic lesion volumes at brachiocephalic artery (31.2% reduction in cilostazol group and 37.4% reduction in clopidogrel group), compared with control group. In addition, the mass densities calculated by this method revealed the anti-platelet treatment increased stable plaque areas including high collagen content, but decreased unstable plaque areas including lipid and macrophage content. These findings were confirmed by histological analyses. Real-time PCR analyses indicated that anti-platelets inhibited gene expressions of cytokines and adhesion molecules, such as IFNγ and ICAM-1. Anti-platelet therapies had a beneficial effect on plaque stability maybe due to anti-inflammatory actions. Phase-contrast X-ray CT imaging could quantify the plaque volume and qualify the plaque components affected by anti-platelet therapies. This novel phase-contrast X-ray CT imaging system could be a plausible method to detect the unstable plaque non-invasively in the future.
The international journal of cardiovascular imaging 06/2011; 28(5):1181-91. · 2.15 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: A prospective, randomized laboratory investigation.
To investigate whether administration of minocycline attenuates hind-limb motor dysfunction and gray and white matter injury after spinal cord ischemia.
Minocycline, a semisynthetic tetracycline antibiotic, has been shown to have neuroprotective effects in models of focal and global cerebral ischemia. However, there have been no data available regarding the effects of minocycline in a model of spinal cord ischemia.
Thirty-six rats were randomly allocated to one of three groups; control (C) group (n = 11), minocycline (M) group (n = 13), or sham group (n = 12). Minocycline or saline was intraperitoneally administered for 3 days beginning at 12 hours before 10 minutes of spinal cord ischemia or sham operation. Spinal cord ischemia was induced with intraaortic balloon catheter and blood withdrawal. Seventy-two hours after reperfusion, hind-limb motor functions were assessed using Basso, Beattie, Bresnahan (BBB) Scale (0 = paraplegia, 21 = normal). For histologic assessments, the gray and white matter injury was evaluated using the number of normal neurons and the extents of vacuolations in the white matter, respectively. Activated microglia was also evaluated using Iba-1 immunohistochemistry.
BBB scores and the numbers of normal neurons in the M group were significantly higher than those in the C group. The percentage areas of vacuolations in the white matter and the number of Iba-1 positive cells were significantly lower in the M group compared with those in the C group.
The results indicated that minocycline administration improved hind-limb motor function and attenuated gray and white matter injury and microglial activation after spinal cord ischemia in rats.
Spine 02/2011; 36(23):1919-24. · 2.08 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: To determine whether the administration of an active form of vitamin D(3) (calcitriol) could prevent atherosclerosis through anti-inflammatory actions.
Recent clinical studies have shown that lack of vitamin D(3) is a risk factor for cardiovascular events. Oral calcitriol administration decreased atherosclerotic lesions, macrophage accumulation, and CD4(+) T-cell infiltration at the aortic sinus, when compared with the corresponding observations in control mice. We observed a significant increase in Foxp3(+) regulatory T cells and a decrease in CD80(+)CD86(+) dendritic cells (DCs) in the mesenteric lymph nodes, spleen, and atherosclerotic lesions in oral calcitriol-treated mice in association with increased interleukin 10 and decreased interleukin 12 mRNA expression. CD11c(+) DCs from the calcitriol group showed reduced proliferative activity of T lymphocytes, suggesting the suppression of DC maturation. Neutralization of CD25 in vivo revealed that calcitriol inhibited atherosclerosis mainly in a regulatory T cell-dependent manner but also partly because of a decrease in DC maturation.
Oral calcitriol treatment could prevent the development of atherosclerosis by changing the function or differentiation of DCs and regulatory T cells. These findings suggest that intestinal and systemic immune modulation by calcitriol may be a potentially valuable therapeutic approach against atherosclerosis.
Arteriosclerosis Thrombosis and Vascular Biology 10/2010; 30(12):2495-503. · 6.37 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Accumulating evidence suggests that several subsets of regulatory T cells that actively mediate immunologic tolerance play crucial roles in atherogenesis. Recently, orally administered anti-CD3 monoclonal antibody has been shown as an inducer of novel regulatory T cells expressing latency-associated peptide (LAP) on their surface, which potently prevents systemic autoimmunity. In the present study, we hypothesized that oral anti-CD3 antibody treatment may inhibit atherosclerosis in mice.
Six-week-old apolipoprotein E-deficient mice on a standard diet were orally given anti-CD3 antibody or control immunoglobulin G on 5 consecutive days, and atherosclerosis was assessed at age 16 weeks. Oral administration of anti-CD3 antibody significantly reduced atherosclerotic lesion formation and accumulations of macrophages and CD4(+) T cells in the plaques compared with controls. We observed a significant increase in LAP(+) cells and CD25(+)Foxp3(+) cells in the CD4(+) T-cell population in anti-CD3-treated mice, in association with increased production of the antiinflammatory cytokine transforming growth factor-beta and suppressed T-helper type 1 and type 2 immune responses. Neutralization of transforming growth factor-beta in vivo abrogated the preventive effect of oral anti-CD3 antibody.
Our findings indicate the atheroprotective role of oral anti-CD3 antibody treatment in mice via induction of a regulatory T-cell response. These findings suggest that oral immune modulation may represent an attractive therapeutic approach to atherosclerosis.
Circulation 11/2009; 120(20):1996-2005. · 14.74 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Thioredoxin, a redox-regulating protein that scavenges reactive oxygen species, appears to show an excellent antiinflammatory effect in treating animal models of various human inflammatory diseases. The aim of this study was to clarify whether thioredoxin is useful for treating inflammatory skin diseases, such as contact dermatitis, caused by epicutaneous exposure to environmental and occupational antigens. The allergic contact hypersensitivity response was suppressed in thioredoxin-transgenic mice. This suppressive effect of thioredoxin appeared to be via the inhibition of the efferent limb of contact hypersensitivity because administration of recombinant thioredoxin suppressed the inflammatory response in the elicitation phase but not in the induction phase. Adoptive-transfer studies revealed that the host environment, but not donor leukocytes, is critical in this suppressive effect. In thioredoxin-transgenic mice, the infiltration of neutrophils in the elicitation site was diminished, whereas the migratory function of cutaneous dendritic cells and hapten-specific cell proliferation were not disturbed. Thioredoxin-transgenic mice had also an attenuated inflammatory response to croton oil. These findings suggest that thioredoxin prevents skin inflammatory responses and could be a suitable candidate for the treatment of contact dermatitis.
Antioxidants & Redox Signaling 03/2009; 11(6):1227-35. · 8.20 Impact Factor
-
Masafumi Takeda,
Tomoya Yamashita,
Masakazu Shinohara,
Naoto Sasaki,
Tomofumi Takaya,
Kenji Nakajima,
Nobutaka Inoue,
Tomoya Masano,
Hideto Tawa,
Seimi Satomi-Kobayashi,
Ryuji Toh,
Daisuke Sugiyama,
Kunihiro Nishimura,
Mitsuhiro Yokoyama,
Ken-ichi Hirata,
Seinosuke Kawashima
[show abstract]
[hide abstract]
ABSTRACT: Although endothelium-dependent vasodilatation has been used as a marker of endothelial dysfunction (ED), there have been no reliable plasma markers for ED. Oxidative stress, which is a major determinant of ED, oxidizes tetrahydrobiopterin (BH4), an essential cofactor of endothelial type nitric oxide synthase (eNOS), and resulted in the relative deficiency of BH4.
In 163 patients with cardiovascular disorders, the plasma levels of BH4 and 7, 8-dihydrobiopterin (BH2) by high performance liquid chromatography were measured and compared with the flow-mediated (FMD) vasodilatory response of the brachial artery, which was measured by ultrasonography. The effects of atorvastatin on plasma pteridine levels and FMD were examined in patients with multiple coronary risk factors. There was a positive relationship between FMD and plasma BH4 levels and a negative relationship between FMD and plasma BH2 levels. Subsequently, a strong positive relationship between FMD and the BH4/BH2 ratio (r=0.585, P<0.0001) was found. Although we did not find any significant relationship between pteridine levels and individual traditional risk factors, the BH4/BH2 ratio in patients with more than 2 risk factors showed significant reductions compared with that in those without risk factors. Statin treatment improved FMD in association with an increase in the plasma BH4/BH2 ratio.
Plasma pteridine levels were associated with endothelial dysfunction in cardiovascular disorders.
Circulation Journal 03/2009; 73(5):955-62. · 3.77 Impact Factor
-
Tomoya Masano,
Seinosuke Kawashima,
Ryuji Toh,
Seimi Satomi-Kobayashi,
Masakazu Shinohara,
Tomofumi Takaya,
Naoto Sasaki, Masafumi Takeda,
Hideto Tawa,
Tomoya Yamashita,
Mitsuhiro Yokoyama,
Ken-ichi Hirata
[show abstract]
[hide abstract]
ABSTRACT: Reactive oxygen species (ROS) is deeply involved in the process of ventricular remodeling after myocardial infarction (MI). Under oxidative stress, endothelial nitric oxide synthase (eNOS) can be converted to a ROS generator, because a relative lack of tetrahydrobiopterin (BH4), an essential cofactor for NO synthesis, leads to eNOS uncoupling. The uncoupled eNOS generates superoxide rather than NO. The possible role of ROS generated by eNOS in ventricular remodeling after MI was investigated.
Rats were treated with oral BH4 supplementation starting at 3 days before coronary artery ligation. At 4 weeks after MI, there was augmented superoxide production in association with reduced BH4/dihydrobiopterin (BH2) ratio and eNOS dimer/monomer protein ratio in the heart. Treatment with BH4 increased BH4/BH2 ratio and eNOS dimer/monomer ratio, and decreased superoxide production. In BH4-treated MI rats, left ventricular size was smaller, thickness of the non-infarcted posterior wall was thinner, and cardiac function was preserved compared with the control MI rats.
The present study suggested that ventricular remodeling process after MI leads to BH4 oxidation and resulted in uncoupled eNOS-derived superoxide generation, which further augmented the remodeling process and deteriorated cardiac function.
Circulation Journal 10/2008; 72(9):1512-9. · 3.77 Impact Factor
-
Naoto Sasaki,
Tomoya Yamashita,
Tomofumi Takaya,
Masakazu Shinohara,
Rio Shiraki, Masafumi Takeda,
Noriaki Emoto,
Akiko Fukatsu,
Toshio Hayashi,
Kazuhisa Ikemoto,
Takahide Nomura,
Mitsuhiro Yokoyama,
Ken-Ichi Hirata,
Seinosuke Kawashima
[show abstract]
[hide abstract]
ABSTRACT: Diabetes mellitus is associated with increased oxidative stress, which induces oxidation of tetrahydrobiopterin (BH4) in vessel wall. Without enough BH4, eNOS is uncoupled to L-arginine and produces superoxide rather than NO. We examined the role of uncoupled eNOS in vascular remodeling in diabetes.
Diabetes mellitus was produced by streptozotocin in C57BL/6J mice. Under stable hyperglycemia, the common carotid artery was ligated, and neointimal formation was examined 4 weeks later. In diabetic mice, the neointimal area was dramatically augmented. This augmentation was associated with increased aortic superoxide formation, reduced aortic BH4/dihydrobiopterin (BH2) ratio, and decreased plasma nitrite and nitrate (NOx) levels compared with nondiabetic mice. Chronic BH4 treatment (10 mg/kg/d) reduced the neointimal area in association with suppressed superoxide production and inflammatory changes in vessels. BH4/BH2 ratio in vessel wall was preserved, and plasma NOx levels increased. Furthermore, in the presence of diabetes, overexpression of bovine eNOS resulted in augmentation of neointimal area, accompanied by increased superoxide production in the endothelium.
In diabetes, increased oxidative stress by uncoupled NOSs, particularly eNOS, causes augmentation of vascular remodeling. These findings indicate restoration of eNOS coupling has an atheroprotective benefit in diabetes.
Arteriosclerosis Thrombosis and Vascular Biology 07/2008; 28(6):1068-76. · 6.37 Impact Factor
-
Masakazu Shinohara,
Tomoya Yamashita,
Hideto Tawa, Masafumi Takeda,
Naoto Sasaki,
Tomofumi Takaya,
Ryuji Toh,
Akihisa Takeuchi,
Takuji Ohigashi,
Kunio Shinohara,
Seinosuke Kawashima,
Mitsuhiro Yokoyama,
Ken-ichi Hirata,
Atsushi Momose
[show abstract]
[hide abstract]
ABSTRACT: Reliable, noninvasive imaging modalities to characterize plaque components are clinically desirable for detecting unstable coronary plaques, which cause acute coronary syndrome. Although recent clinical developments in computed tomography (CT) have enabled the visualization of luminal narrowing and calcified plaques in coronary arteries, the identification of noncalcified plaque components remains difficult. Phase-contrast X-ray CT imaging has great potentials to reveal the structures inside biological soft tissues, because its sensitivity to light elements is almost 1,000 times greater than that of absorption-contrast X-ray imaging. Moreover, a specific mass density of tissue can be estimated using phase-contrast X-ray CT. Ex vivo phase-contrast X-ray CT was performed using a synchrotron radiation source (SPring-8, Japan) to investigate atherosclerotic plaque components of apolipoprotein E-deficient mice. Samples were also histologically analyzed. Phase-contrast X-ray CT at a spatial resolution of 10-20 mum revealed atherosclerotic plaque components easily, and thin fibrous caps were detected. The specific mass densities of these plaque components were quantitatively estimated. The mass density of lipid area was significantly lower (1.011 +/- 0.001766 g/ml) than that of smooth muscle area or collagen area (1.057 +/- 0.001407 and 1.080 +/- 0.001794 g/ml, respectively). Moreover, the three-dimensional assessment of plaques could provide their anatomical information. Phase-contrast X-ray CT can estimate the tissue mass density of atherosclerotic plaques and detect lipid-rich areas. It can be a promising noninvasive technique for the investigation of plaque components and detection of unstable coronary plaques.
AJP Heart and Circulatory Physiology 03/2008; 294(2):H1094-100. · 3.71 Impact Factor
-
Tomoya Yamashita,
Seinosuke Kawashima,
Tetsuaki Hirase,
Masakazu Shinohara,
Tomofumi Takaya,
Naoto Sasaki, Masafumi Takeda,
Hideto Tawa,
Nobutaka Inoue,
Ken-Ichi Hirata,
Mitsuhiro Yokoyama
[show abstract]
[hide abstract]
ABSTRACT: Atherosclerosis is a complex chronic inflammatory disease in which macrophages play a critical role, and the intervention of the inflammatory process in atherogenesis could be a therapeutic strategy. In this study, we investigated the efficacy of xenogenic macrophage immunization on the atherosclerotic lesion formation in a model of murine atherosclerosis. Apolipoprotein E knockout (apoE-KO) mice were repeatedly immunized with formaldehyde-fixed cultured human macrophages (phorbol ester-stimulated THP-1 cells), using human serum albumin as a control protein or HepG2 cells as human control cells, once a week for four consecutive weeks. The vehicle phosphate-buffered saline was injected in the nonimmunized controls. THP-1 immunization induced antibodies that are immunoreactive with mouse macrophages. Although the plasma lipid levels were unchanged by the immunization, the atherosclerotic lesion area in the aortic root was significantly reduced by >50% in 16-wk-old THP-1-immunized apoE-KO mice compared with that in control mice. THP-1 immunization reduced in vivo macrophage infiltration, reduced in vitro macrophage adhesion, and changed cytokine production by macrophages to the antiatherogenic phenotype. Xenogenic macrophage immunization protects against the development of atherosclerosis in apoE-KO mice by modulating macrophage function in which antibodies induced by the immunization are likely to be involved. This method is a novel and potentially useful cell-mediated immune therapeutic technique against atherosclerosis.
AJP Cell Physiology 09/2007; 293(3):C865-73. · 3.54 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: c-Ski is a transcriptional corepressor that interacts strongly with Smad2, Smad3, and Smad4 but only weakly with Smad1 and Smad5. Through binding to Smad proteins, c-Ski suppresses signaling of transforming growth factor-beta (TGF-beta) as well as bone morphogenetic proteins (BMPs). In the present study, we found that a mutant of c-Ski, termed c-Ski (ARPG) inhibited TGF-beta/activin signaling but not BMP signaling. Selectivity was confirmed in luciferase reporter assays and by determination of cellular responses in mammalian cells (BMP-induced osteoblastic differentiation of C2C12 cells and TGF-beta-induced epithelial-to-mesenchymal transdifferentiation of NMuMG cells) and Xenopus embryos. The ARPG mutant recruited histone deacetylases 1 (HDAC1) to the Smad3-Smad4 complex but not to the Smad1/5-Smad4 complex. c-Ski (ARPG) was unable to interact with Smad4, and the selective loss of suppression of BMP signaling by c-Ski (ARPG) was attributed to the lack of Smad4 binding. We also found that c-Ski interacted with Smad3 or Smad4 without disrupting Smad3-Smad4 heteromer formation. c-Ski (ARPG) would be useful for selectively suppressing TGF-beta/activin signaling.
Molecular Biology of the Cell 04/2004; 15(3):963-72. · 4.94 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: c-Ski and SnoN are transcriptional co-repressors that inhibit transforming growth factor-beta signaling through interaction with Smad proteins. Among receptor-regulated Smads, c-Ski and SnoN bind more strongly to Smad2 and Smad3 than to Smad1. Here, we show that c-Ski and SnoN bind to the "SE" sequence in the C-terminal MH2 domain of Smad3, which is exposed on the N-terminal upper side of the toroidal structure of the MH2 oligomer. The "QPSMT" sequence, located in the vicinity of SE, supports the interaction with c-Ski and SnoN. Sequences similar to SE and QPSMT are found in Smad2, but not in Smad1. The N-terminal MH1 domain and linker region of Smad3 protrude from the N-terminal upper side of the MH2 oligomer toroid. Smurf2 induces ubiquitin-dependent degradation of SnoN, since it appears to be located close to SnoN through binding to the linker region of Smad2. In contrast, transcription factors Mixer and FoxH3 (FAST1) bind to the bottom side of the Smad3 MH2 toroid; therefore, c-Ski does not affect the interaction of Smads with these transcription factors. Our findings thus demonstrate the stoichiometry of how multiple molecules can associate with the Smad oligomers and how the Smad-interacting proteins functionally interact with each other.
Journal of Biological Chemistry 02/2003; 278(1):531-6. · 4.77 Impact Factor
