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The effect of hypercholesterolemia induced immune response and inflammation on progression of atherosclerosis in ApoB tm25gy LDLr tm1Her mice, expressing only ApoB100 and deficient in the low density lipoprotein (LDL) receptor, thus closely resembling human cholesterol transport is not well defined. Atherosclerosis was induced by a high cholesterol diet and its progression was studied at 8, 14 and 20 weeks. Antibody response was determined by ELISA. Lymphocytes in spleen and aortic expression of inflammatory markers were studied by flow cytometry, and immunohistochemistry respectively. A rapid increase in plasma LDL levels in the first 8 weeks was followed by the exponential development of atherosclerosis between 8 and 14 weeks. Progression of the disease was accompanied by an accumulation of macrophages and increased expression of IL17 and IFN-γ in the aorta. Hypercholesterolemia resulted in increased immune response to modified lipids and aortic inflammation, with an expansion of Th17 cells in the spleen. Progression of atherosclerosis showed a positive correlation (r = 0.84, P

Objective Atherosclerosis is an autoimmune condition and the underlying cause of coronary artery disease (CAD). Circulating antibodies to self-antigens can have a pathogenic or protective function in atherosclerosis. The objective of the study was to understand the association of autoantibody levels with CAD and its correlation with circulating immune cells. Methods We assessed antigen concentration and antibodies to apolipoprotein B (ApoB) and heat shock protein (HSP)60 by ELISA in 252 acute coronary syndromes (ACS), 112 patients with stable angina (SA) and 203 healthy controls from Indian population. T cells in peripheral blood mononuclear cells (PBMC) were enumerated by flow cytometry. Cytokine concentrations were measured by multiplex assay. Results IgG and IgM antibodies to ApoB and HSP60 proteins were significantly lower in patients with ACS while only IgG levels to ApoB were lower in patients with SA, compared with control. Subjects in the highest tertile of antibodies showed significantly lower OR for ACS (IgG 0.52, 95% CI 0.31 to 0.88, p=0.02 and IgM 0.58, 95% CI 0.34 to 0.98, p=0.04), ApoB100 (IgG 0.52, 95% CI 0.31 to 0.88, p=0.02 and IgM 0.58, 95% CI 0.34 to 0.99, p=0.04) and HSP60, respectively. Interestingly, T helper 17 (TH17) cells showed an inverse relationship with ApoB and HSP60 IgG antibodies (r 2 =−0.17, p 2 =−0.20, p Conclusion This study shows that higher antibodies to ApoB and HSP60 proteins are less often associated with ACS and that these antibodies are inversely associated with inflammatory Th17 cells.

Cardiovascular diseases remain the most significant cause of global mortality despite advances in medicine and new drug development. Atherosclerotic lesions start developing in childhood, progress over decades and manifest as coronary artery disease, stroke or peripheral arterial disease later in life. Chronic inflammation in the arterial wall mediated by altered immune response is vital during the development of atherosclerosis. Antigen specific immune therapy is an elegant approach to target disease related antigens. Immune tolerance to atherogenic self antigens has gained importance as an efficient therapy to control atherosclerosis in recent years. This review discusses the recent development and our understanding of immune tolerance in atherosclerosis and the role of regulatory immune response in protection against the disease.

Background: Activated inflammatory cells are found in coronary plaques as well as peripheral circulation in patients with acute coronary syndrome. We explored the circulating T cell profile, their reactivity to self-antigens and plasma cytokine levels in Indian patients with Myocardial Infarction. Methods and Results: Intracellular expression of interferon-γ Interleukin (IL)-4, IL-17, IL-10 and Foxp3 were determined in CD4+ and CD8+ T cells using flow cytometry in patients with ST elevated myocardial infarction (STEMI) (N = 79) and controls (N = 80). Cytokines were measured using Milliplex kit and T cell reactivity was studied by CFSE dilution. Statistical analysis was performed using SPSS software. Patients with myocardial infarction showed higher proportion of IL-17 expressing CD4+ and CD8+ T cells (Th17 and Tc17) and elevated levels of IL-6 and IL-17 in plasma with significant reduction in circulating Tregs. Th1, Th2 and CD4+CD28null cells were not significantly different in patients compared to healthy individuals. The ratio of Th17 and Tc17 to Tregs showed an independent association with STEMI with an adjusted odds ratio of 2.92 (95% CI: 1.73 - 4.92), P < 0.001 and 2.22 (95% CI: 1.42 - 3.44), P < 0.001 respectively. Reactivity to HSP60 and oxidized LDL with expansion of IL-17 expression was higher in patients compared with control. Young patients (

Atherosclerosis is the leading cause for cardiovascular mortality. We determined the effect of multi-antigenic construct expressing three peptides AHC (ApoB100, HSP60 and outer membrane protein of chlamydia pneumonia) in stabilizing advanced atherosclerosis in Apobtm2Sgy/Ldlrtm1Her/J mice. Atherosclerosis was induced by feeding high fat diet (HFD) to mice for 10 weeks, followed by five oral dosing with purified AHC or ovalbumin on alternate days and continued on HFD for another 10 weeks. Tolerance was associated with significantly higher numbers of regulatory T cells both in aortic sinus and spleen with higher mRNA expression of CTLA4 (3 fold), Foxp3 (1.4 folds) and TGF-β (1.62) in aorta. Tregs cells were found to induce alternate activation of macrophages to M2 phenotype, with a reduction in plaque inflammation. AHC treatment showed evidence of plaque stabilization as observed by reduction in plaque necrosis in aortic sinus (35.8%) and in brachiocephalic artery (26%), with reduced expression of Tissue factor and MMP9. Macrophage apoptosis was reduced and collagen content was enhanced by treatment. Our results suggest that tolerance to atherogenic peptides increases regulatory T cells which activate M2 macrophages, prevent T cell proliferation and reduce plaque destabilization and inflammatory markers thus providing evidences for plaque stabilization in mice with advanced atherosclerosis.

Antigen-specific immune modulation is emerging as an attractive therapeutic option to prevent atherosclerosis. We compared the efficacy of oral administration of peptides derived from apolipoprotein B (ApoB; 661–680) and heat shock protein 60 (HSP60; 153–163), in the prevention of atherosclerotic lesion formation hyperlipidemic low density lipoprotein receptordeficient (LDLr−/−), apolipoprotein B-100 only (apoB100/100) mice model. Oral administration of peptides induced tolerance as seen by an increase in regulatory T cells in the peripheral immune system. Tolerance to ApoB peptide reduced plaque development by 28.7% (P<0.001) while HSP60 was effective in reducing lesion development by 26.8% in ApoB48/LDLr−/− mice. While tolerance to HSP60 resulted in increase in anti-inflammatory cytokines (IL10 and TGF-β), ApoB tolerance was effective in reducing the lipid deposition in the lesion. Our results suggest that the two peptides have distinct mechanisms of controlling the development of atherosclerosis in mice.

Introduction: Immunotherapy by inducing oral tolerance to atherogenic self-antigens is gaining importance as an alternative treatment modality for atherosclerosis. The use of live bacterial vectors to express the recombinant antigen in vivo will obviate the need for large-scale purification of recombinant protein and may also augment the efficacy of oral tolerance induction. Aim: The objective of the study was to explore the use of recombinant Mycobacterium smegmatis as a live vector for oral delivery of antigens to induce immune tolerance. Method and Results: We developed a M. smegmatis vector to secrete a recombinant tripeptide construct (AHC; peptides from Apolipoprotein B, Heat-shock protein 60 and Chlamydia pneumoniae outer membrane protein) expressed in a dendroaspin protein scaffold in pJH154 background. Immune response and oral tolerance to the cloned peptides were studied in C57/BL6 mice. The efficacy of this live vaccine to control atherosclerosis was studied in ApoE−/− knockout mice in C57/BL6 background. Oral administration of M. smegmatis secreting the cloned AHC antigen was found to induce tolerance to cloned protein and reduce the development of atherosclerosis by 24.0% compared to control. Protection against atherosclerosis was associated with increase in expression of regulatory T cell-associated markers including CTLA4 (1.8-fold), Foxp3 (2.6-fold), TGF-β (2.8-fold), IL10 (2.9-fold), and reduction in lipids, macrophage infiltration, and expression of inflammatory mediators in aorta. Conclusions: Our results suggest that M. smegmatis can be developed as an oral carrier of recombinant proteins to treat inflammatory autoimmune diseases. © 2016 John Wiley & Sons Ltd

Objective— The goal of this study was to assess whether immunization of Ldlr tm1Her Apob tm2Sgy J mice with 2 peptides located at the N-terminus of the C5a receptor (C5aR), either alone or in combination, is effective in reducing atherosclerotic lesions. Methods and Results— Five- to 6-week-old female Ldlr tm1Her Apob tm2Sgy J mice were immunized using a repetitive immunization multiple sites strategy with keyhole limpet hemocyanin-conjugated peptides derived from the C5aR, either alone (designated as C5aR-P1 [aa 1–21] and C5aR-P2 [aa 19–31]) or in combination (designated as C5aR-P1+C5aR-P2). Mice were fed a high-fat diet for 10 weeks. Lesions were evaluated histologically; local and systemic immune responses were analyzed by immunohistochemistry of aorta samples and cytokine measurements in plasma samples and splenocyte supernatants. Immunization of Ldlr tm1Her Apob tm2Sgy J mice with these peptides elicited high concentrations of antibodies against each peptide. Immunization with the single peptide inhibited plaque development. Combined inoculation with C5aR-P1+C5aR-P2 had an additive effect on reducing the lesion in the aorta sinus and descending aortas when compared with controls. This effect correlated with cellular infiltration and cytokine/chemokine secretion in the serum or in stimulated spleen cells as well as specific cellular immune responses when compared with controls. Conclusion— Immunization of mice with C5aR-P1 and C5aR-P2, either alone or in combination, was effective in reducing early atherosclerotic lesion development. The combined peptide is more potential than either epitope alone to reduce atherosclerotic lesion formation through the induction of a specific Treg cell response as well as blockage of monocyte differentiation into macrophages.

Background Several studies have reported a conflicting association between cytomegalovirus (CMV) infection and coronary artery disease (CAD) based on the levels of total anti-CMV antibodies. However, none have estimated the levels of specific neutralising antibodies (NA) to CMV, which may be clinically more relevant. Objective To determine whether CMV–NA titres show a better association with CAD compared with total anti-CMV antibody levels. Design CMV–NA titres were measured by micro-neutralisation assay and anti-CMV IgG antibodies using ELISA in 391 consecutive CAD patients compared with the same number of controls (N=782), and 91 patients reporting recurrent cardiac events during a 4-year follow-up compared with those without a recurrent event (N=182). Levels of inflammatory markers, interleukin 6, high-sensitivity C reactive protein, fibrinogen and secretory phospholipase A2 (sPLA2), were measured by ELISA. Analysis of variance and logistic regression were used for statistical analyses. Results High CMV–NA titres showed a positive association with CAD occurrence (OR 2.24, 95% CI 1.31 to 3.85, p=0.003) and recurrent cardiac events in CAD patients (OR 4.65, 95% CI 1.21 to 17.86, p=0.025) compared with total CMV antibodies (OR 1.67, 95% CI 1.04 to 2.69, p=0.034, and 2.70, 1.04 to 7.02, p=0.040, respectively). Patients with higher quartile of CMV–NA titres and sPLA2 levels had an adjusted OR of 7.82 (95% CI 1.87 to 32.65, 0.005) for recurrent cardiac events compared with those with the lowest quartiles for both markers. Conclusion These findings suggest that high CMV–NA titres in combination with inflammatory markers improve prediction of cardiac events in the Asian Indian population.

Inflammatory immune response to atherogenic self-antigens plays an important role in the development of atherosclerosis. We evaluated the role of oral tolerance to three peptides in controlling atherosclerosis in New Zealand white rabbits.Peptides derived from apolipoprotein B (ApoB), heat shock protein 60, and outer membrane protein from Chlamydia pneumoniae were expressed as part of the dendroaspin protein scaffold (AHC). Groups of 3-month-old rabbits were dosed orally with purified AHC protein either before the onset of disease or 2 months after inducing atherosclerosis; they were euthanized at the age of 7 months to study disease development and progression.Oral treatment with AHC resulted in a marked increase in regulatory T cells in the lymphoid organs and reduced the development and progression of atherosclerosis by 48.6% and 28.4%, respectively (P0.05). Oral tolerance decreased plaque inflammation, enhanced expression of anti-inflammatory and regulatory markers in the aorta, and attenuated the adaptive immune response to self-antigens. AHC treatment in rabbits with established disease significantly decreased vascular cell adhesion molecule 1 (VCAM-1) (6.2 fold) and monocyte chemoattractant protein-1(MCP-1) (3 fold) expression and reduced the infiltration of macrophages into the aorta. Collagen content and the smooth muscle cell-to-macrophage ratio were higher in treated animals, whereas markers of plaque vulnerability, including matrix metalloproteinase expression, were reduced.Our results suggest that oral tolerance to multiantigenic AHC molecule restores the immune balance and induces markers of plaque stability in rabbits.

Oral tolerance to auto antigens reduces the development of atherosclerosis in mouse models. However, the effect of immune tolerance to multiple self antigenic peptides in plaque progression and stabilization is not known. We studied the protective effect of mucosal tolerance to peptides from apolipoprotein B (ApoB; 661-680) and heat shock protein 60 (HSP60; 153-163), in combination with diet, in the prevention of atherosclerotic lesion progression and plaque stabilization in ApoB(tm25gy)LDLr(tm1Her) mice. We found that oral administration of five doses of a combination of ApoB and HSP60 peptides (20 µg/mice/dose) induced tolerance to both the peptides and reduced early plaque development by 39.9% better than the individual peptides (ApoB = 28.7%;HSP60 = 26.8%)(P

Antigen-specific immune modulation is an attractive approach to atherosclerosis treatment. The aim of this study was to develop an in-vitro assay to screen peptide molecules for their inflammatory propensity.Human dendritic cells derived from CD14(+) monocytes were activated using peptides derived from apolipoprotein B100 (ApoB), heat shock protein 60 (HSP60) and complement cascade (peptide A) in vitro, and used for priming autologous T cells. Proliferation of T cells, their differentiation to regulatory cells (Treg) and their cytokine profile were studied. The efficacy of the peptides in preventing atherosclerosis was studied in ApoB(tm2Sgy)/Ldlr(tm1Her/J) knockout mice.ApoB and HSP60 peptides induced T-cell proliferation and expansion of regulatory T cells with interleukin-10 and transforming growth factor-β secretion. In comparison, peptide A was a poor stimulator of T cells and was found to induce tumor necrosis factor-α secretion by activated T cells. ApoB and HSP60 peptides were found to reduce early atherosclerotic lesion formation in mice by 32.1 and 33.5 %, respectively, while the reduction with peptide A was 5.7 %. Thus the in-vitro assay shows an apparent correlation with in-vivo activity and can be developed as a screening assay to prioritize the candidate molecules for animal efficacy testing.

Atherosclerosis, the underlying cause of cardiovascular disease, is characterized by chronic inflammation and altered immune response. Cholesterol is a well-known risk factor associated with the development of cardiovascular diseases. Elevated serum cholesterol is unique because it can lead to development of atherosclerosis in animals and humans even in the absence of other risk factors. Modifications of low-density lipoproteins mediated by oxidation, enzymatic degradation, and aggregation result in changes in their function and activate both innate and adaptive immune system. Oxidized low-density lipoprotein (LDL) has been identified as one of the most important autoantigens in atherosclerosis. This escape from self-tolerance is dependent on the formation of oxidized phospholipids. The emerging understanding of the importance of immune responses against oxidized LDL in atherosclerosis has focused attention on the possibility of development of novel therapy for atherosclerosis. This review provides an overview of immune response to lipoproteins and the fascinating possibility of developing an immunomodulatory therapy for atherosclerosis.