Kazuyuki Kasahara

The clinical impact of late gadolinium enhancement in Takotsubo cardiomyopathy: serial analysis of cardiovascular magnetic resonance images

BackgroundOur study aimed to investigate both the clinical implications of late gadolinium enhancement (LGE) by cardiovascular magnetic resonance (CMR) and the relation of LGE to clinical findings in patients with Takotsubo cardiomyopathy (TTC).MethodsWe evaluated 20 consecutive patients (2 men, 18 women; median age, 77 years; interquartile range [IQR] 67-82 years) who were admitted to our hospital with the diagnosis of TTC. CMR was performed within 1 week after admission, and follow-up studies were conducted 1.5 and 6 months later.ResultsIn 8 patients, CMR imaging during the sub-acute phase revealed LGE in the area matched with wall motion impairment. Cardiogenic shock was more frequently observed in patients with LGE than in those without LGE (38% vs 0%, p = 0.049). The patients with LGE needed a longer duration for ECG normalization and recovery of wall motion than did those without LGE (median 205 days, IQR [152-363] vs 68 days, [43-145], p = 0.005; 15 days, [10-185] vs 7 days, [4-13], p = 0.030, respectively). In 5 of these 8 patients, LGE disappeared within 45-180 days (170, IQR [56-180]) of onset. The patients with LGE remaining in the chronic phase had higher peak creatine kinase levels than did those without LGE (median 307 IU/L, IQR [264-460] vs 202 IU/L, [120-218], p = 0.017).ConclusionLGE by CMR in the sub-acute phase may be associated with the severity and prolonged recovery to normal of clinical findings in TTC.

Anti-inflammatory and immune-modulatory therapies for preventing atherosclerotic cardiovascular disease

Atherosclerosis is believed to be a chronic inflammation of the arterial wall and various immune cells of innate and adaptive immunity involves in the pathogenesis of atherosclerosis. Based on this notion, several anti-inflammatory strategies for prevention of atherosclerosis have been examined mainly using animal models. Vaccination or mucosal immunization with athero-antigens comes under candidate therapeutic methods for antigen-specific prevention of atherosclerosis. Immune suppression mediated by regulatory T cells (Tregs) could be another method to regulate pathogenic chronic inflammation in atherogenesis. Inducible Tregs are reported to differentiate peripherally in the intestine and we have been interested in the oral tolerance, in which not only Tregs but also tolerogenic dendritic cells play crucial roles. We demonstrated that modulation of the intestinal immunity including oral tolerance could be a novel therapy against atherosclerosis. Further, downregulation of effector T cell response and/or Treg predominant condition was shown to induce atherosclerosis regression and inhibit the progression of aneurysm. In clinical situations, none of the approaches to specifically and directly treat inflammation to prevent cardiovascular events or reduce atherosclerosis in human individuals were successful, although high-sensitive C-reactive protein is shown to have a strong relationship with recurrent events of cardiovascular diseases in several randomized clinical trials. Now two randomized placebo-controlled clinical trials evaluating anti-inflammatory agents are being conducted in the USA and Canada to clarify whether targeting the inflammation itself will reduce cardiovascular events and risks. In this review, we present the current understanding of anti-inflammatory and immune-modulation therapies against atherosclerosis and discuss the future perspectives.

Regression of atherosclerosis with anti-CD3 antibody via augmenting a regulatory T-cell response in mice

AIMS Although recent animal studies have investigated the cellular and molecular mechanisms underlying the process of atherosclerosis regression, it remains unknown whether adaptive immune responses including T cells are involved in this process. We investigated the role of T cells in atherosclerosis regression. METHODS AND RESULTS LDL receptor-deficient mice were fed a high-cholesterol diet for 8 weeks to form atherosclerotic lesions and were then changed to a standard diet, and atherosclerosis was assessed 4 weeks later. Just before changing the diet, the mice received an iv injection of anti-CD3 antibody (CD3-Ab) or control immunoglobulin G for 5 consecutive days. CD3-Ab treatment regressed atherosclerosis and decreased the accumulation of macrophages and CD4(+) T cells in the plaques. CD3-Ab treatment also dramatically reduced CD4(+) T cells and increased the proportion of regulatory T cells (Tregs). Depletion of Tregs by anti-CD25 antibody injection abolished the regression of atherosclerosis seen in CD3-Ab-treated mice, indicating the essential role for Tregs in this process. CONCLUSION CD3-Ab treatment induced rapid regression of established atherosclerosis via reducing CD4(+) T cells and increasing the proportion of Tregs. These findings suggest that therapeutic intervention for T-cell-mediated immune responses may represent a novel strategy to induce atherosclerosis regression in combination with lipid-lowering therapy.

Foxp3+ Regulatory T Cells Play a Protective Role in Angiotensin II–Induced Aortic Aneurysm Formation in Mice

Although regulatory T cells (Tregs) have been shown to play a protective role in abdominal aortic aneurysm (AAA) formation, it remains unclear whether expansion of endogenous Foxp3+ Tregs prevents AAA. In the current study, we determined the effects of endogenous Foxp3+ Treg expansion or depletion in an experimental model of AAA. We continuously infused 12-week-old apolipoprotein E–deficient mice fed a high-cholesterol diet with angiotensin II (n=60) or normal saline (n=12) by implanting osmotic mini-pumps and evaluated AAA formation at 16 weeks. The angiotensin II–infused mice received interleukin-2/anti–interleukin-2 monoclonal antibody complex (interleukin-2 complex; n=31) or PBS (n=29). Eighty-one percent of angiotensin II–infused mice developed AAA, with 42% mortality possibly because of aneurysm rupture. Interleukin-2 complex treatment systemically increased the number of Foxp3+ Tregs and significantly decreased the incidence (52%) and mortality (17%) of AAA. Immunohistochemical analysis showed reduced accumulation of macrophages and increased numbers of Foxp3+ Tregs in aneurysmal tissues, suggesting that expansion of Tregs may suppress local inflammation in the vessel wall and provide protection against AAA formation. Furthermore, genetic depletion of Foxp3+ Tregs led to a significant increase in the mortality of AAA, suggesting the protective role of Foxp3+ Tregs against AAA. Our findings suggest that Foxp3+ Tregs may play a protective role in AAA formation and that promotion of an endogenous regulatory immune response may be a potentially valuable therapeutic approach for preventing AAA.

Intestinal Immunity and Gut Microbiota as Therapeutic Targets for Preventing Atherosclerotic Cardiovascular Diseases

Atherosclerosis is considered a chronic inflammatory disease and an intervention targeting the inflammatory process could be a new therapeutic strategy for preventing atherosclerotic cardiovascular diseases (CVD). We hypothesized that the intestine, which is considered the biggest immune organ in the human body, could be a therapeutic target for preventing CVD. We demonstrated that oral administration of anti-CD3 antibody or an active form of vitamin D3 reduced atherosclerosis in mice via induction of regulatory T cells and tolerogenic dendritic cells in the gut-associated lymphoid tissues. Similar to regulatory immune responses achieved by oral tolerance, our method had systemic effects that ultimately contributed towards atherosclerosis reduction. Recently, we have been interested in the gut microbiota, which have been reported as highly associated with intestinal immunity and systemic metabolic disorders, including obesity and diabetes. Notably, the guts of obese individuals are predominantly colonized by Firmicutes over Bacteroidetes. The association between atherosclerosis and microbiota has been attracting increased attention, and gut microbiota have been shown to participate in the metabolism of a proatherogenic compound called trimethylamine-N-oxide (TMAO) and aggravate CVD. Our investigation of the relationship between susceptibility to CVD and the gut microbiota revealed a characteristic flora type. Here, we discuss the evidence for the relationship between the gut microbiota and cardiometabolic diseases, and consider the gut microbiota as new potential therapeutic targets for treating CVD. (Circ J 2015; 79: 1882-1890).

CD3 Antibody and IL-2 Complex Combination Therapy Inhibits Atherosclerosis by Augmenting a Regulatory Immune Response

Background Accumulating evidence suggests that the balance between pathogenic effector T cells (Teffs) and regulatory T cells (Tregs) may be important for controlling atherosclerotic disease. We hypothesized that a combination therapy with anti‐CD3 antibody (CD3‐Ab) and IL‐2/anti‐IL‐2 monoclonal antibody complex (IL‐2 complex) aimed at increasing the ratio of Tregs to Teffs would effectively inhibit atherosclerosis in mice. Methods and Results We treated apolipoprotein E‐deficient mice fed a high‐cholesterol diet with vehicle, CD3‐Ab, IL‐2 complex, or their combination. Mice receiving the combination therapy had markedly reduced atherosclerotic lesions than mice treated with CD3‐Ab or IL‐2 complex alone. In addition, a striking increase in the Treg/Teff ratio of lymphoid organs and atherosclerotic lesions, along with plaque stabilization characterized by decreased macrophage content and increased collagen content was observed. The combination treatment also markedly reduced splenic Ly6Chigh inflammatory monocytes and might induce a favorable macrophage phenotype change in atherosclerotic lesions. Conclusions Our results indicate that in addition to suppressing Teff responses, enhancing Treg‐mediated immune responses is more efficacious in preventing atherosclerosis, suggesting a novel therapeutic approach for atherosclerosis.

Overexpression of Cytotoxic T-Lymphocyte–Associated Antigen-4 Prevents Atherosclerosis in Mice

Objective— Although T-cell–mediated chronic inflammation contributes to atherosclerosis development, the role of a negative regulatory molecule cytotoxic T-lymphocyte–associated antigen-4 (CTLA-4) in atherosclerosis is poorly understood. We investigated the effects of CTLA-4 overexpression on atherosclerosis in apolipoprotein E–deficient (Apoe −/−) mice. Approach and Results— We generated CTLA-4 transgenic (CTLA-4-Tg)/Apoe −/− mice that display constitutive cell surface and intracellular expression of CTLA-4 in T cells and assessed atherosclerosis at age 16 weeks. CTLA-4 overexpression significantly reduced atherosclerotic lesion formation and intraplaque accumulation of macrophage and CD4+ T cells in the aortic root compared with controls. CTLA-4-Tg/Apoe −/− mice showed decreased numbers of effector CD4+ T cells and decreased expression of costimulatory molecules CD80 and CD86, ligands for CTLA-4, and a costimulatory molecule CD28, on CD11c+ dendritic cells compared with controls. Consistent with in vivo findings, in vitro experiments revealed that CD4+ T cells from CTLA-4-Tg/Apoe −/− mice showed decreased proliferative capacity and proinflammatory cytokine production, downregulated CD80 expression on CD11c+ dendritic cells, and suppressed the proliferation of other T cells by limiting the costimulatory pathway. Moreover, CD11c+ dendritic cells from CTLA-4-Tg/Apoe −/− mice showed reduced proliferative activity of T cells in vitro, suggesting the suppression of dendritic cell maturation in vivo. Conclusions— CTLA-4 regulates atherosclerosis by suppressing proatherogenic immune responses and could be an attractive therapeutic target for atherosclerosis.

UVB Exposure Prevents Atherosclerosis by Regulating Immunoinflammatory Responses

Objective— UVB irradiation is an established treatment for immunoinflammatory cutaneous disorders and has been shown to suppress cutaneous and systemic inflammatory diseases through modulation of the adaptive immune response. However, it remains unknown whether UVB irradiation prevents an immunoinflammatory disease of arteries such as atherosclerosis. Approach and Results— Here, we show that UVB exposure inhibits the development and progression of atherosclerosis in atherosclerosis-prone mice by expanding and enhancing the functional capacity of CD4+ forkhead box P3+ regulatory T cells and regulating proatherogenic T-cell responses. Experimental studies in Langerhans cell–depleted mice revealed that epidermal Langerhans cells play a critical role in UVB-dependent induction of CD4+ forkhead box P3+ regulatory T cells, suppression of proatherogenic T-cell responses, and prevention of atherosclerotic plaque development. Conclusions— Our findings suggest the skin immune system as a novel therapeutic target for atherosclerosis and provide a novel strategy for the treatment and prevention of atherosclerosis.

Oral administration of the lactic acid bacterium Pediococcus acidilactici attenuates atherosclerosis in mice by inducing tolerogenic dendritic cells

The intestinal microbiota appears to play an important role in the development of atherosclerosis. We investigated the effect of the probiotic lactic acid bacterium Pediococcus acidilactici R037 on atherosclerosis using apolipoprotein E-deficient (ApoE−/−) mice. Six-week-old ApoE−/− mice were orally administered R037 six times a week. Mice treated with R037 for 12 weeks exhibited markedly attenuated atherosclerotic lesions in the aortic root (2.3 ± 0.15 × 105 µm2 vs. 3.3 ± 0.29 × 105 µm2, respectively; P < 0.01; n = 15–17 each group). The expression of Ki-67 in CD4+ T cells, the population of interferon γ-producing CD4+ T cells in the spleen, and pro-inflammatory cytokine production from splenic lymphocytes were significantly decreased in R037-treated mice. Interestingly, splenic dendritic cells (DCs) isolated from R037-treated mice suppressed CD4+ T-cell proliferation and pro-inflammatory cytokine production ex vivo, suggesting that R037 treatment induced tolerogenic DCs. Programmed cell death ligand 1 expression in DCs was significantly enhanced in R037-treated mice, which might explain the immunosuppressive effect of DCs at least in part. These results indicate that R037 attenuates atherosclerosis by inducing tolerogenic DCs, which suppress Th1-driven inflammation and the proliferative activity of CD4+ T cells. Our findings may provide a novel therapeutic approach for the prevention of atherosclerosis based on dietary supplementation with probiotics.

Regulatory T Cells and Tolerogenic Dendritic Cells as Critical Immune Modulators in Atherogenesis

Innate and adaptive immunity has been shown to be critically involved in the pathogenesis of atherosclerosis. In particular, immune suppression mediated by regulatory T cells (Tregs) or tolerogenic dendritic cells (DCs) serves as a vital mechanism for regulating pathogenic chronic inflammation in atherogensis, suggesting that promotion of endogenous regulatory immune responses could be a possible therapeutic approach to suppress atherosclerotic disease. In this review, we discuss the possible role of Tregs and tolerogenic DCs in the prevention of atherosclerosis and the promising strategies to prevent or cure atherosclerotic disease by modulating regulatory immune responses mediated by these suppressor cells.