Kayoko Sato

Pathogen-Sensing Plasmacytoid Dendritic Cells Stimulate Cytotoxic T-Cell Function in the Atherosclerotic Plaque Through Interferon-α

Background— Unstable atherosclerotic plaque is characterized by an infiltrate of inflammatory cells. Both macrophages and T cells have been implicated in mediating the tissue injury leading to plaque rupture; however, signals regulating their activation remain unidentified. Infectious episodes have been suspected to render plaques vulnerable to rupture. We therefore explored whether plasmacytoid dendritic cells (pDCs) that specialize in sensing bacterial and viral products can regulate effector functions of plaque-residing T cells and thus connect host infection and plaque instability. Methods and Results— pDCs were identified in 53% of carotid atheromas (n=30) in which they localized to the shoulder region and produced the potent immunoregulatory cytokine interferon (INF)-&agr;. IFN-&agr; transcript concentrations in atheroma tissues correlated strongly with plaque instability (P<0.0001). Plaque-residing pDCs responded to pathogen-derived motifs, CpG-containing oligodeoxynucleotides binding to toll-like receptor 9, with enhanced IFN-&agr; transcription (P=0.03) and secretion (P=0.007). IFN-&agr; emerged as a potent regulator of T-cell function, even in the absence of antigen recognition. Specifically, IFN-&agr; induced a 10-fold increase of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) on the surface of CD4 T cells (P<0.0001) and enabled them to effectively kill vascular smooth muscle cells (P=0.0003). Conclusions— pDCs in atherosclerotic plaque sense microbial motifs and amplify cytolytic T-cell functions, thus providing a link between host-infectious episodes and acute immune-mediated complications of atherosclerosis.

TRAIL-expressing T cells induce apoptosis of vascular smooth muscle cells in the atherosclerotic plaque

Acute coronary syndromes (ACS) are precipitated by a rupture of the atherosclerotic plaque, often at the site of T cell and macrophage infiltration. Here, we show that plaque-infiltrating CD4 T cells effectively kill vascular smooth muscle cells (VSMC). VSMCs sensitive to T cell–mediated killing express the death receptor DR5 (TNF-related apoptosis-inducing ligand [TRAIL] receptor 2), and anti-TRAIL and anti-DR5 antibodies block T cell–mediated apoptosis. CD4 T cells that express TRAIL upon stimulation are expanded in patients with ACS and more effectively induce VSMC apoptosis. Adoptive transfer of plaque-derived CD4 T cells into immunodeficient mice that are engrafted with human atherosclerotic plaque results in apoptosis of VSMCs, which was prevented by coadministration of anti-TRAIL antibody. These data identify that the death pathway is triggered by TRAIL-producing CD4 T cells as a direct mechanism of VSMC apoptosis, a process which may lead to plaque destabilization.

Functional profile of activated dendriticcells in unstable atherosclerotic plaque

AbstractBackgroundUnstable atherosclerotic plaque typically contains an infiltrate of activated macrophages and activated T cells. This study established a functional profile of plaque-residing dendritic cells (DC) to examine whether they can function as Ag-presenting cells to facilitate in situ T-cell activation.MethodsCarotid artery plaque tissues were collected from 19 asymptomatic and 38 symptomatic patients undergoing endarterectomy. Matched samples of normal coronary artery wall, stable nonruptured plaque, and eroded unstable plaque were harvested from patients with fatal myocardial infarction. Quantitative PCR and immunohistochemistry were used to analyze the tissues for markers of DC activation (CD83, CD86, CCL19,CCL21) and correlate them with T-cell activation (IFN-γ,TNF-α).ResultsCarotid artery plaques from patients with ischemic symptoms compared to asymptomatic patients were characterized by the presence of high amount of T-cells (P < 0.01) and tissue production of high levels of the T-cell cytokines IFN-γ (P = 0.001) and TNF-α (P = 0.006). Plaque tissues from patients with ischemic complications contained elevated levels of CD83 (P < 0.001), a marker of DC activation, and the DC chemokines CCL19 (P = 0.001) and CCL21 (P < 0.02).Unstable coronary artery plaques were similarly correlated compared to carotid plaques from symptomatic patients with the accumulation of T cells (P = 0.001) and the production of T cell chemokines IFN-γ (P = 0.001) and TNF-α (P = 0.002).Immunohistochemistry confirmed the presence of CD83+ DC in the shoulder region of unstable plaques, where they produced the T cell-attracting chemokines CCL19 and CCL21. Mapping of activated DC demonstrated close contact between mature DC and T cells expressing the activation marker CD40 ligand (CD40L).ConclusionActivated and fully mature DC are represented in the inflammatory infiltrate characteristic for unstable carotid and coronary atheroma. Such DC produce chemokines, and thus can regulate the cell traffic into the lesion. Through the expression of the costimulatory ligand CD86, plaque-residing DC can augment T-cell stimulation and provide optimal stimulation conditions for T lymphocytes, resembling the microenvironment in organized lymphoid tissues.

T Cell Recognition and Killing of Vascular Smooth Muscle Cells in Acute Coronary Syndrome

Loss of vascular smooth muscle cells (VSMCs) has been proposed to destabilize the atherosclerotic plaque and contribute to plaque rupture, superimposed thrombosis, and acute coronary syndromes (ACSs). We examined whether VSMCs are susceptible to T cell–induced apoptosis and found that CD4 T cells are highly effective in establishing cell–cell contact with VSMCs and triggering apoptotic death. Visualization of the T cell–VSMC contact zone on the single-cell level revealed that both patient-derived and control CD4 T cells reorganized their cell membrane to assemble an immunologic synapse with the VSMCs. Within 4 to 10 minutes, the membrane proximal signaling molecule ZAP-70 was recruited and phosphorylated. However, only patient-derived CD4 T cells sustained an intact immunologic synapse beyond 10 minutes and generated intracellular calcium signals. CD4 T cells that maintained a synaptic contact and appeared to be responsible for VSMC apoptosis accounted for approximately 20% of the circulating memory T cell population in ACS patients and were rare in the blood of age-matched controls. CD4 T cells from ACS patients were also hyperresponsive to T cell receptor–mediated stimulation when triggered by a superantigen and non-VSMC target cells. Lowered setting of the T cell activation threshold, attributable to excessive amplification of proximal CD3-mediated signals, may contribute to CD4 T cell-mediated killing of VSMCs and promote plaque instability.

Statins reduce endothelial cell apoptosis via inhibition of TRAIL expression on activated CD4 T cells in acute coronary syndrome

OBJECTIVE Statins reduce cardiovascular-related morbidity and mortality, but their effects on inflammation in atherosclerosis are not fully understood. We investigated whether statins can modulate cytotoxic functions of CD4 T cells in acute coronary syndrome (ACS). METHODS AND RESULTS Fresh CD4 T cells were isolated from 55 patients with ACS without statin treatment on admission and from 34 age-matched controls. CD4 T cells collected from ACS patients induced endothelial cell apoptosis significantly more than control T cells. The TNF-related apoptosis-inducing ligand (TRAIL) receptor DR5 was strongly upregulated on endothelial cells, and TRAIL-specific antibodies effectively blocked CD4 T cell-mediated apoptosis, indicating that T cell-mediated endothelial death was dependent on the TRAIL pathway. Expression of both the activating antigen CD69 and TRAIL was enhanced on ACS T cells. In in-vitro assays rosuvastatin, fluvastatin, and pitavastatin directly blocked CD4 T cell-mediated endothelial cell apoptosis and reduced T cell-expression of CD69 and TRAIL through TCR-induced Extracellar signal-Regulated Kinases (ERK) activation. CONCLUSIONS Activated CD4 T cells expressing TRAIL are enriched in the blood of ACS patients and induce endothelial injury, which may contribute to the destabilization of the plaque. Early statin therapy may suppress T cell-mediated endothelial cell damage in atherosclerotic plaques and thus prevent cardiovascular events.

Sudden cardiac arrest secondary to cardiac amyloidosis in a young woman with cryopyrin-associated periodic syndrome.

Cryopyrin-associated periodic syndrome (CAPS) is caused by NLRP3 mutations, which result in dysregulated interleukin 1β (IL-1β) production and inflammation. Some patients with CAPS develop systemic amyloidosis via an inflammatory reaction. We describe a case of a 39-year-old woman who experienced cardiopulmonary arrest secondary to ventricular fibrillation complicated by cardiac amyloidosis as well as by CAPS. She was diagnosed with renal amyloidosis at 32 years of age. At 34 years of age, genetic sequencing of the NLRP3 gene demonstrated that she was heterozygous for the p.E304 K mutation, and she was subsequently diagnosed with CAPS. After treatment with canakinumab (human anti-IL-1β monoclonal antibody) for CAPS, the inflammatory reaction was improved. However, she eventually developed cardiac arrest with ventricular fibrillation and was successfully resuscitated. Echocardiography demonstrated mildly reduced left ventricular systolic function (left ventricular ejection fraction of 48%). Coronary angiography revealed no stenosis, but a cardiac biopsy demonstrated cardiac amyloidosis. She received an implantable cardioverter defibrillator.

Statement for Appropriate Clinical Use of PCSK9 Inhibitors

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a protein that promotes the degradation of LDL receptors. Evolocumab (Repatha®), a recombinant human IgG2 antibody, and alirocumab (Praluent ®), a recombinant human IgG1 antibody, are new types of drug that lower blood LDL cholesterol (LDL-C) by inhibiting PCSK9 and increasing the number of LDL receptors on the surface of hepatocytes. In combination with statins, PCSK9 inhibitors achieve a very strong LDL-C lowering effect making them a powerful option for patients with insufficient LDL-C management with existing drugs. However, the drugs are expensive. Therefore, from the viewpoints of medical and medical economics, it is an urgent issue to identify the types of patients who really need them and would be benefitted greatly from their use. In this regard, the Japan Atherosclerosis Society would like to express its views in accordance with the JAS Guidelines for the Diagnosis and Prevention of Atherosclerotic Cardiovascular Diseases 20171).

P-Selectin Glycoprotein Ligand-1 (PSGL-1) Expressing CD4 T Cells Contribute Plaque Instability in Acute Coronary Syndrome

BACKGROUND Adhesion molecules have essential roles in the development of atherosclerosis. We investigated whether P-selectin glycoprotein ligand-1 (PSGL-1)-expressing CD4 T cells contribute to plaque instability in acute coronary syndrome (ACS).Methods and Results:We studied the adhesion molecules on CD4 T cells from consecutive patients with ACS treated with thrombus-aspirating device and compared them with healthy controls (n=48 each). Blood, thrombi, and plaque samples from the culprit coronary arteries were collected by thrombus aspiration performed during emergency coronary artery angiography. According to flow cytometry results, peripheral CD4 T cells from ACS patients strongly expressed PSGL-1 and integrin β2 (P<0.05 for both) more than those from controls; culprit coronary arteries contained an abundance of PSGL-1+(P<0.001) but not integrin β2+CD4 T cells. In addition, immunohistochemical analysis of the thrombus-aspirating device samples revealed numerous PSGL-1+CD4 T cells in plaques from the culprit lesions. Results from the selectin-binding assay demonstrated that activated PSGL-1+CD4 T cells from ACS patients bound to P- or E-selectin after triggering the T-cell receptor, and adhered to endothelial cells under laminar flow conditions (P<0.05 and P<0.05, respectively), inducing their apoptosis (P<0.01) via activated caspase-3, which correlated with PSGL-1 expression (R=0.788, P=0.021) and was suppressed by application of a PSGL-1-specific antibody (P<0.05). CONCLUSIONS PSGL-1 contributed to cytotoxic CD4 T cell homing to the culprit coronary artery and promoted plaque instability in ACS.