Treatment with a human recombinant monoclonal IgG antibody against oxidized LDL in atherosclerosis-prone pigs reduces cathepsin S in coronary lesions.

Background: Immunization with oxidized LDL (oxLDL) reduces atherosclerosis in rodents. We tested the hypothesis that treatment with a human recombinant monoclonal antibody against oxLDL will reduce the burden or composition of atherosclerotic lesions in hypercholesterolemic minipigs.

Methods And Results: Thirty-eight hypercholesterolemic minipigs with defective LDL receptors were injected with an oxLDL antibody or placebo weekly for 12weeks.

Transforming growth factor-β signaling in T cells promotes stabilization of atherosclerotic plaques through an interleukin-17-dependent pathway.

Adaptive immunity has a major impact on atherosclerosis, with pro- and anti-atherosclerotic effects exerted by different subpopulations of T cells. Transforming growth factor-β (TGF-β) may promote development either of anti-atherosclerotic regulatory T cells or of T helper 17 (TH17) cells, depending on factors in the local milieu. We have addressed the effect on atherosclerosis of enhanced TGF-β signaling in T cells.

T-cell activation leads to reduced collagen maturation in atherosclerotic plaques of Apoe(-/-) mice.

Rupture of the collagenous, fibrous cap of an atherosclerotic plaque commonly causes thrombosis. Activated immune cells can secrete mediators that jeopardize the integrity of the fibrous cap. This study aimed to determine the relationship between T-cell-mediated inflammation and collagen turnover in a mouse model of experimental atherosclerosis.

Inflammation and atherosclerosis.

Atherosclerosis, the cause of myocardial infarction, stroke, and ischemic gangrene, is an inflammatory disease. The atherosclerotic process is initiated when cholesterol-containing low-density lipoproteins accumulate in the intima and activate the endothelium. Leukocyte adhesion molecules and chemokines promote recruitment of monocytes and T cells.

Enhanced expression of the homeostatic chemokines CCL19 and CCL21 in clinical and experimental atherosclerosis: possible pathogenic role in plaque destabilization.

Objective: Based on their role in T-cell homing into nonlymphoid tissue, we examined the role of the homeostatic chemokines CCL19 and CCL21 and their common receptor CCR7 in coronary artery disease (CAD).

Methods And Results: We performed studies in patients with stable (n=40) and unstable (n=40) angina and healthy controls (n=20), in vitro studies in T-cells and macrophages, and studies in apolipoprotein-E-deficient (ApoE-/-) mice and human atherosclerotic carotid plaques. We found increased levels of CCL19 and CCL21 within the atherosclerotic lesions of the ApoE-/- mice, in human atherosclerotic carotid plaques, and in plasma of CAD patients.

T cells in atherogenesis: for better or for worse?

The idea that atherosclerosis is an inflammatory disease is no longer controversial. Instead, much of the current research is now focused on understanding what drives this inflammation and how it is regulated. Adaptive immunity, in particular T cells, is highly involved in atherogenesis.

Transforming growth factor-beta regulation of immune responses.

Transforming growth factor-beta (TGF-beta) is a potent regulatory cytokine with diverse effects on hemopoietic cells. The pivotal function of TGF-beta in the immune system is to maintain tolerance via the regulation of lymphocyte proliferation, differentiation, and survival. In addition, TGF-beta controls the initiation and resolution of inflammatory responses through the regulation of chemotaxis, activation, and survival of lymphocytes, natural killer cells, dendritic cells, macrophages, mast cells, and granulocytes.

Natural regulatory T cells control the development of atherosclerosis in mice.

Atherosclerosis is an immunoinflammatory disease elicited by accumulation of lipids in the artery wall and leads to myocardial infarction and stroke. Here, we show that naturally arising CD4(+)CD25(+) regulatory T cells, which actively maintain immunological tolerance to self and nonself antigens, are powerful inhibitors of atherosclerosis in several mouse models. These results provide new insights into the immunopathogenesis of atherosclerosis and could lead to new therapeutic approaches that involve immune modulation using regulatory T cells.

Adoptive transfer of CD4+ T cells reactive to modified low-density lipoprotein aggravates atherosclerosis.

Objective: Atherosclerosis is associated with immune responses to oxidized low-density lipoprotein (oxLDL). The presence of activated macrophages and T cells in lesions suggests that cell-mediated immune reactions are taking place during the disease process. However, the role of specific immune responses has remained unclear.

Enhanced T-cell expression of RANK ligand in acute coronary syndrome: possible role in plaque destabilization.

Objective: Based on its role in inflammation and matrix degradation, we hypothesized a role for osteoprotegerin (OPG), RANK, and RANK ligand (RANKL) in coronary artery disease.

Methods And Results: We examined the expression of various members of the OPG/RANKL/RANK axis in patients with stable and unstable angina and in the atherosclerotic lesions of apolipoprotein E-deficient (apoE(-/-)) mice. Our findings were: (1) Serum levels of OPG were raised in patients with unstable angina (n=40), but not in those with stable angina (n=40), comparing controls (n=20); (2) mRNA levels of RANKL were increased in T-cells in unstable angina patients accompanied by increased expression of RANK in monocytes; (3) strong immunostaining of OPG/RANKL/RANK was seen within thrombus material obtained at the site of plaque rupture during acute myocardial infarction; (4) OPG/RANKL/RANK was expressed in the atherosclerotic plaques of apoE(-/-) mice, with RANKL located specifically to the plaques; and (5) RANKL enhanced the release of monocyte chemoattractant peptide-1 in mononuclear cells from unstable angina patients, and promoted matrix metalloproteinase (MMP) activity in vascular smooth muscle cells.

Lesion development and response to immunization reveal a complex role for CD4 in atherosclerosis.

Atherosclerosis is a complex disease, bearing many of the characteristics of a chronic inflammatory process. Both cellular and humoral immune responses may be involved in the disease development. Oxidized low-density lipoprotein (oxLDL) is suggested to be an autoantigen in atherosclerosis.

Lack of complement factor C3, but not factor B, increases hyperlipidemia and atherosclerosis in apolipoprotein E-/- low-density lipoprotein receptor-/- mice.

Objective: To investigate the effect of complement deficiency on atherogenesis and lipidemia, we used mice deficient in the third complement component (C3-/-) or factor B (FB-/-).

Methods And Results: Complement-deficient mice were crossed with mice deficient in both apolipoprotein E and the low-density lipoprotein receptor (Apoe-/- LDLR-/-). The percent lesion area in the aorta at 16 weeks, determined by en face analysis, was 84% higher in C3-/- mice than in controls (11.

Disruption of TGF-beta signaling in T cells accelerates atherosclerosis.

Increasing evidence suggests that atherosclerosis is an inflammatory disease promoted by hypercholesterolemia. The role of adaptive immunity has been controversial, however. We hypothesized that proatherogenic T cells are controlled by immunoregulatory cytokines.