CD40L induces inflammation and adipogenesis in adipose cells--a potential link between metabolic and cardiovascular disease.

CD40L figures prominently in atherogenesis. Recent data demonstrate elevated levels of sCD40L in the serum of patients with the metabolic syndrome (MS). This study investigated the role of CD40L in pro-inflammatory gene expression and cellular differentiation in adipose tissue to obtain insight into mechanisms linking the MS with atherosclerosis.

Interleukin-18, the metabolic syndrome, and subclinical atherosclerosis: results from the Dallas Heart Study.

Objective: Although IL-18 promotes atherogenesis in animal studies and predicts cardiovascular risk in humans, it is unknown whether elevated IL-18 levels are associated with coronary atherosclerosis in the general population.

Methods And Results: IL-18 plasma levels were determined by ELISA in 2231 subjects from the Dallas Heart Study. In univariable analysis, IL-18 levels associated with traditional cardiovascular risk factors and particularly with components of the metabolic syndrome (MS, P<0.

CD40 ligand mediates inflammation independently of CD40 by interaction with Mac-1.

Background: Strong evidence supports a role for CD40 ligand (CD40L) as marker and mediator of inflammatory diseases such as atherosclerosis. Despite extensive characterization of CD40, the classic receptor of CD40L, its role in immune defense against inflammatory diseases remains uncertain. The present study aimed to characterize the contribution of CD40 signaling to atherogenesis.

TRAF-1, -2, -3, -5, and -6 are induced in atherosclerotic plaques and differentially mediate proinflammatory functions of CD40L in endothelial cells.

Objective: Several lines of evidence implicate CD40 ligand (CD40L, CD154) as a mediator and marker of atherosclerosis. This study investigated the involvement of tumor necrosis factor receptor-associated factors (TRAFs) in CD40 signaling in endothelial cells (ECs) and their expression in atheromata and cells involved in atherogenesis.

Methods And Results: CD40L enhanced the basal expression of TRAF-1, -2, -3, and 6, but not TRAF-5 in ECs.

Influence of pre-analytical and analytical factors on soluble CD40L measurements.

The soluble form of CD40L (CD40 ligand), a pro-atherogenic mediator, has emerged as a diagnostic and prognostic marker for cardiovascular events. However, as platelets can shed CD40L upon activation, accurate measurement has proved challenging. The present study addresses the controversy regarding the appropriate specimen and preparation for laboratory evaluation of blood sCD40L (soluble CD40L).

Family history of diabetes is a major determinant of endothelial function.

Objectives: We evaluated whether endothelial dysfunction was present in nondiabetic persons with a family history (FH) of diabetes and assessed its relationship with insulin resistance and atherosclerosis risk factors.

Background: Atherosclerosis is frequently present when type 2 diabetes (T2D) is first diagnosed. Endothelial dysfunction contributes to atherogenesis.

Metformin inhibits proinflammatory responses and nuclear factor-kappaB in human vascular wall cells.

Objective: Metformin may benefit the macrovascular complications of diabetes independently of its conventional hypoglycemic effects. Accumulating evidence suggests that inflammatory processes participate in type 2 diabetes and its atherothrombotic manifestations. Therefore, this study examined the potential action of metformin as an inhibitor of pro-inflammatory responses in human vascular smooth muscle cells (SMCs), macrophages (Mphis), and endothelial cells (ECs).

Elevated release of sCD40L from platelets of diabetic patients by thrombin, glucose and advanced glycation end products.

The pro-inflammatory CD40/CD40L dyad participates in atherogenesis. Plasma levels of the soluble ligand (sCD40L) predict cardiovascular events and are elevated in diabetic patients. This study compared CD40/CD40L surface expression on platelets and T lymphocytes of diabetic and control subjects, and tested whether glucose and advanced glycation end products (AGEs) stimulate sCD40L release.

Associations between soluble CD40 ligand, atherosclerosis risk factors, and subclinical atherosclerosis: results from the Dallas Heart Study.

Objective: The purpose of this study was to evaluate the associations between plasma levels of soluble CD40 ligand (sCD40L), atherosclerosis risk factors, and evidence of subclinical atherosclerosis.

Methods And Results: Plasma levels of sCD40L were measured in 2811 subjects from the Dallas Heart Study, a multiethnic population-based cross-sectional study. Electron Beam Computed Tomography measurements of coronary artery calcium (CAC) and MRI measurements of aortic plaque were performed in 2198 and 1965 subjects, respectively.

Atherogenesis in mice does not require CD40 ligand from bone marrow-derived cells.

Objective: Recent research suggests a central role for CD40 ligand (CD40L) in atherogenesis. However, the relevant cellular source of this proinflammatory cytokine remains unknown. To test the hypothesis that CD40L expressed on hematopoietic cell types (eg, macrophages, lymphocytes, platelets) is crucial to atherogenesis, we performed bone marrow reconstitution experiments using low-density receptor-deficient (ldlr-/-) and ldlr-/-/cd40l-/- compound-mutant mice.

Enhanced expression of CD44 variants in human atheroma and abdominal aortic aneurysm: possible role for a feedback loop in endothelial cells.

CD44, a polymorphic hyaluronate receptor, may participate in chronic inflammation. We hypothesized that CD44 variants contribute to the development of arterial diseases. CD44 levels vary in normal and diseased arterial tissues in the following order: unaffected arteries < fibrous plaques < or = abdominal aortic aneurysm < atheromatous plaques; and correlate with macrophage content.

Inflammation, immunity, and HMG-CoA reductase inhibitors: statins as antiinflammatory agents?

According to traditional thinking, atherosclerosis results from passive lipid deposition in the vascular wall. Thus, therapies predominantly targeted lipid metabolism. The contemporary view of atherosclerosis, however, has broadened to include an active and complex role for inflammation, orchestrated in part by mediators of the immune system.

Diseased vein grafts express elevated inflammatory cytokine levels compared with atherosclerotic coronary arteries.

Background: The pathologic modifications characterizing vein graft disease resemble those observed in native arteriosclerosis, but in accelerated form. Although both disorders are considered to be inflammatory diseases, it remains to be determined whether diseased vein grafts and atherosclerotic coronary arteries differentially express inflammatory mediators. Therefore, we examined whether differences in the expression of proinflammatory cytokines by these two distinct vascular pathologies favor the accelerated inflammation within diseased vein grafts.

Soluble CD40L: risk prediction after acute coronary syndromes.

Background: Elevated plasma concentrations of soluble CD40 ligand (sCD40L) indicate increased risk for future cardiovascular events in apparently healthy women. This study tested the hypothesis that plasma sCD40L, alone or in combination with troponin (cTnI) or C-reactive protein (CRP), may identify patients with acute coronary syndromes at heightened risk for recurrent cardiac events.

Methods And Results: In a nested case-control study (cases, n=195; controls, n=195) within the OPUS-TIMI16 trial, patients with the prespecified study end points death, myocardial infarction (MI), or congestive heart failure (CHF) within 10 months had significantly higher median (25th, 75th percentiles) sCD40L plasma levels than did controls (0.

Elevated plasma levels of the atherogenic mediator soluble CD40 ligand in diabetic patients: a novel target of thiazolidinediones.

Background: Considerable evidence implicates the proinflammatory cytokine CD40 ligand (CD40L) in atherosclerosis and accumulating data link type 1 and 2 diabetes, conditions associated with accelerated atherosclerosis, to inflammation. This study therefore evaluated the hypothesis that diabetic patients have elevated plasma levels of soluble CD40L (sCD40L) and that treatment with the insulin-sensitizing thiazolidinediones lowers this index of inflammation.

Methods And Results: Subjects with type 1 (n=49) or type 2 diabetes (n=48) had higher (P<0.

Soluble CD40 ligand levels indicate lipid accumulation in carotid atheroma: an in vivo study with high-resolution MRI.

Objective: The CD40/CD40 ligand pathway mediates inflammatory processes important in atherogenesis and the formation of the intraplaque lipid pool. We tested the hypothesis that plasma levels of soluble CD40 ligand are elevated in patients with evidence of a lipid pool on high-resolution magnetic resonance imaging (MRI) of carotid stenoses.

Methods And Results: We recruited 49 patients with evidence of carotid atherosclerosis on ultrasonography; 3 patients could not undergo carotid MRI because of claustrophobia.

Oxidized low-density lipoprotein augments and 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors limit CD40 and CD40L expression in human vascular cells.

Background: Although CD40 signaling participates in atherosclerosis, links between lipid risk factors and this inflammatory pathway remain obscure. Cardiovascular risk reduction by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) may involve actions beyond lipid lowering, including reduced inflammation. Therefore, this study analyzed whether oxidized low-density lipoprotein (oxLDL) induces CD40/CD40L expression on cells implicated in atherogenesis and whether statins affect their expression in vitro as well as the expression of soluble CD40L (sCD40L) in vivo.

Cytokines in the pathogenesis of atherosclerosis.

Research during the last two decades established atheromatous lesions as active sites of inflammation and immune responses, contrasting to the traditional view of atherosclerosis as an acellular lesion composed of lipid deposits. In particular, cytokines appear to orchestrate the chronic development of atherosclerosis, eventually leading to the formation of complex atherosclerotic plaques, which can trigger acute thromboembolic complications, such as myocardial infarction or stroke. Indeed the rupture-prone plaque, characterized by a thin fibrous cap overlaying a voluminous lipid core, exhibits accumulation of various pro-inflammatory cytokines.

Innate and adaptive immunity in the pathogenesis of atherosclerosis.

This review considers critically the evidence for the involvement of mediators of innate and acquired immunity in various stages of atherosclerosis. Rapidly mobilized arms of innate immunity, including phagocytic leukocytes, complement, and proinflammatory cytokines, contribute to atherogenesis. In addition, adaptive immunity, with its T cells, antibodies, and immunoregulatory cytokines, powerfully modulates disease activity and progression.

T(H)2 predominant immune responses prevail in human abdominal aortic aneurysm.

T lymphocytes localize within lesions of two diametrically opposed expressions of atherosclerosis: stenosis-producing plaques and ectasia-producing abdominal aortic aneurysm (AAA). T(H)1 immune responses appear to predominate in human stenotic lesions. However, little information exists regarding the nature of the T-cell infiltrate in AAAs.

Induction of tissue factor expression in human endothelial cells by CD40 ligand is mediated via activator protein 1, nuclear factor kappa B, and Egr-1.

Induction of tissue factor expression in endothelial cells via ligation of CD40 probably figures prominently in the pathogenesis of prevalent inflammatory diseases, including atherosclerosis. However, the molecular mechanisms of tissue factor gene expression triggered by CD40 ligand (CD40L) in this cell type remain unknown. We demonstrate here that the tissue factor promoter region -278 bp to +121 bp contains the CD40L-responsive elements, consisting of activator protein 1 (AP-1)+/-, nuclear factor (NF) kappaB-, and Egr-1-binding sites.

Expression of interleukin (IL)-18 and functional IL-18 receptor on human vascular endothelial cells, smooth muscle cells, and macrophages: implications for atherogenesis.

Although considerable evidence implicates the cytokine interferon (IFN)-gamma in atherogenesis, the proximal inducers and the range of sources of its expression remain unknown. This study tested the hypothesis that interleukin (IL)-18 regulates IFN-gamma expression during atherogenesis. Indeed, human atheroma in situ expressed IL-18 and elevated levels of its receptor subunits, IL-18Ralpha/beta, compared with nondiseased arterial tissue.