Vaccinating Rabbits with a Cholesteryl Ester Transfer Protein (CETP) B-Cell Epitope Carried by Heat Shock Protein-65 (HSP65) for Inducing Anti-CETP Antibodies and Reducing Aortic Lesions In Vivo

Two decades of vaccine development against atherosclerosis

Atherosclerosis is an immune-mediated chronic inflammatory disease that leads to the development of fatty plaques in the arterial walls, ultimately increasing the risk of thrombosis, stroke, and myocardial infarction. The immune response in this complex disease is both atheroprotective and pro-atherogenic, involving both innate and adaptive immunity. Current treatments include the adjustment of lifestyle factors, cholesterol-lowering drugs such as statins, and immunotherapy, whereas vaccine development has received comparatively little attention. In this review, we discuss the potential of antigen-specific vaccination as a preventative approach based on more than 20 years of research and innovation. Vaccination targets include proteins that are more abundant in atherosclerotic patients, such as oxidized low-density lipoprotein (LDL), apolipoprotein B-100, proprotein convertase subtilisin/kexin type-9 serine protease (PCSK9), cholesteryl ester transfer protein (CETP), and heat shock proteins HSP60 and HSP65. Immunization with such proteins or their peptide epitopes has been shown to induce T-cell activation, produce antigen-specific antibodies, reduce the size of atherosclerotic lesions, and/or reduce serum cholesterol levels. Vaccination against atherosclerosis therefore offers a new strategy to address the burden on healthcare systems caused by cardiovascular disease, the leading cause of death worldwide.

Modulating Autoimmunity against LDL: Development of a Vaccine against Atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the arterial wall that leads to the build-up of occluding atherosclerotic plaques. Its clinical sequelae, myocardial infarction and stroke, represent the most frequent causes of death worldwide. Atherosclerosis is a multifactorial pathology that involves traditional risk factors and chronic low-grade inflammation in the atherosclerotic plaque and systemically. This process is accompanied by a strong autoimmune response that involves autoreactive T cells in lymph nodes and atherosclerotic plaques, as well as autoantibodies that recognize low-density lipoprotein (LDL) and its main protein component apolipoprotein B (ApoB). In the past 60 years, numerous preclinical observations have suggested that immunomodulatory vaccination with LDL, ApoB, or its peptides has the potential to specifically dampen autoimmunity, enhance tolerance to atherosclerosis-specific antigens, and protect from experimental atherosclerosis in mouse models. Here, we summarize and discuss mechanisms, challenges, and therapeutic opportunities of immunomodulatory vaccination and other strategies to enhance protective immunity in atherosclerosis.

Cholesteryl ester transfer protein and its inhibitors

Most of the cholesterol in plasma is in an esterified form that is generated in potentially cardioprotective HDLs. Cholesteryl ester transfer protein (CETP) mediates bidirectional transfers of cholesteryl esters (CEs) and triglycerides (TGs) between plasma lipoproteins. Because CE originates in HDLs and TG enters the plasma as a component of VLDLs, activity of CETP results in a net mass transfer of CE from HDLs to VLDLs and LDLs, and of TG from VLDLs to LDLs and HDLs. As inhibition of CETP activity increases the concentration of HDL-cholesterol and decreases the concentration of VLDL- and LDL-cholesterol, it has the potential to reduce atherosclerotic CVD. This has led to the development of anti-CETP neutralizing monoclonal antibodies, vaccines, and antisense oligonucleotides. Small molecule inhibitors of CETP have also been developed and four of them have been studied in large scale cardiovascular clinical outcome trials. This review describes the structure of CETP and its mechanism of action. Details of its regulation and nonlipid transporting functions are discussed, and the results of the large scale clinical outcome trials of small molecule CETP inhibitors are summarized.

Assessment of Carrot Callus as Biofactories of an Atherosclerosis Oral Vaccine Prototype

Atherosclerosis is a pathology leading to cardiovascular diseases with high epidemiologic impact; thus, new therapies are required to fight this global health issue. Immunotherapy is a feasible approach to treat atherosclerosis and given that genetically engineered plants are attractive hosts for vaccine development; we previously proved that the plant cell is able to synthesize a chimeric protein called CTB:p210:CETPe, which is composed of the cholera toxin B subunit (CTB) as immunogenic carrier and target epitopes from the cholesteryl ester transfer protein (CETP461-476) and apolipoprotein B100 (p210). Since CTB:p210:CETPe was expressed in tobacco at sufficient levels to evoke humoral responses in mice, its expression in carrot was explored in the present study looking to develop a vaccine in a safe host amenable for oral delivery; avoiding the purification requirement. Carrot cell lines expressing CTB:p210:CETPe were developed, showing accumulation levels up to 6.1 µg/g dry weight. An immunoblot analysis revealed that the carrot-made protein is antigenic and an oral mice immunization scheme led to evidence on the immunogenic activity of this protein; revealing its capability of inducing serum IgG responses against p210 and CETP epitopes. This study represents a step forward in the development of an attractive oral low-cost vaccine to treat atherosclerosis.

Vaccine against arteriosclerosis: an update

Substantial data from experimental and clinical investigation support the role of immune-mediated mechanisms in atherogenesis, with immune systems responding to many endogenous and exogenous antigens that play either proatherogenic or atheroprotective roles. An active immunization strategy against many of these antigens could potentially alter the natural history of atherosclerosis. This review mainly focuses on the important studies on the search for antigens that have been tested in vaccine formulations to reduce atherosclerosis in preclinical models. It will also address the opportunities and challenges associated with potential clinical application of this novel therapeutic paradigm.

A novel atheroprotective role of MF59-like adjuvant when co-administered with CETP vaccine in rabbit model of atherosclerosis

OBJECTIVES

In this study, for the first time, MF59 adjuvant was used to develop a cholesteryl ester transfer protein (CETP) vaccine. The efficacy of the vaccine was compared with the efficacy of CETP vaccine formulated with Alum/CpG, the formulation that its immunogenicity has been already demonstrated in rabbit and mice.

MATERIALS AND METHODS

Tetanus toxoid- CETP peptide (TT-CETP) was mixed with Alum/CpG or MF59-like and administered subcutaneously for total five times in rabbit model of atherosclerosis. Anti-TT-CETP specific antibody, CETP activity in sera and mRNA level of cytokine IL-4 and IFN-γ in peripheral mononuclear cells were determined. Therapeutic response was also examined by tracking serum lipoprotein levels and pathologic observation of atherosclerotic lesions at aortic site.

RESULTS

More anti-TT-CETP antibody was found in Alum/CpG vaccinated rabbits compared to buffer (P<0.001). Antibody induced by MF59-like formulation was not significantly higher than buffer. CETP activity and lipoprotein levels were not significantly different between vaccinated and control rabbits. The mRNA level of IL-4 was significantly lower than buffer while, IFN-γ gene expression was significantly higher in both vaccinated groups. Atherosclerosis thickness grade of aorta was dramatically lower than buffer (P<0.01) in both vaccinated groups.

CONCLUSION

It is concluded that MF59-adjuvanted CETP vaccine showed anti-atherosclerosis properties, but the protective effect could not be directly attributed to the immune response induced by anti TT-CETP antibody and CETP inhibition. Further studies are needed to explain the anti-atherosclerosis properties of MF59 in the presence of TT-CETP peptide.

Anti-atherosclerosis effect of different doses of CETP vaccine in rabbit model of atherosclerosis

AIM

To evaluate atheroprotective effects of different doses of cholesteryl ester transfer protein (CETP) vaccine, three doses of Tetanus toxoid-CETP (TT-CETP) peptide including 10, 50 and 100/rabbit, termed FA10, FA50, FA100, respectively, were administered in rabbit model of atherosclerosis.

METHODS

Animals were vaccinated subcutaneously (S.C.) with 100μl of vaccine in presence of complete Freund's adjuvant (CFA) for the first administration. Rabbits were boosted 4 times at 3 weeks intervals with the same peptide dose formulated in incomplete Freund's adjuvant (IFA). Animals were fed with diet supplemented with 2% cholesterol from week 11 to week 19. Anti-TT-CETP specific antibody and CETP activity in sera were determined. Therapeutic response was examined by tracking plasma lipoprotein levels (HDL-C, LDL-C and total cholesterol), and pathologic observation of intima/media thickness at the site of aortic lesions.

RESULTS

All TT-CETP vaccine doses generated strong anti TT-CETP antibody response. CETP activity reduced in rabbits vaccinated with FA100 (P=0.031). FA100 showed significant increase in level of HDL-C rather than control group (P=0.006). However, no significant reduction were found in atherosclerotic lesion when compared to control.

CONCLUSION

Inhibition of CETP activity and increased HDL-C were found with FA100, but the vaccine failed to prevent aortic lesion development in immunized rabbits when compared to control. Our result supports the hypothesis stated that CETP may not be an attractive therapeutic target for the prevention of cardiovascular disease.

The role of inflammatory biomarkers in developing targeted cardiovascular therapies: lessons from the cardiovascular inflammation reduction trials

Anti-inflammatory add-on therapy to conventional cardiovascular prophylaxis has been proposed as a novel therapeutic approach to potentially reduce residual cardiovascular risk. This hypothesis has been challenged by a series of unsuccessful Phase III studies testing the impact on clinical outcomes of novel agents with immunomodulatory actions. Specifically, the apparent ability of phospholipase A2 (PLA2) inhibitors and of antioxidants to ameliorate inflammation and to reduce coronary disease in Phase II trials did not translate into improved secondary cardiovascular prevention in larger population-based studies. Other anti-inflammatory agents are still under scrutiny. However, studies to date have lacked information on the inflammatory profile of the participants, both at baseline and at follow-up, thereby limiting the possibility of identifying subgroups of patients in whom 'residual inflammation' can be detected despite optimal conventional therapy, and who could therefore benefit from a cardiovascular prevention strategy specifically targeting inflammation. This has also rendered it difficult to interpret the results as a conclusive demonstration of inefficacy of the tested anti-inflammatory strategies in the treatment of atherosclerosis. We here discuss the importance of better patient characterization to minimize heterogeneity of the study population, so that effectiveness of different anti-inflammatory strategies can be evaluated in targeted subgroups of patients. We also illustrate how specific inflammatory biomarkers could assist in this process, with particular emphasis on the roles of high-sensitivity C-reactive protein and circulating monocyte phenotype.

Reality of a Vaccine in the Prevention and Treatment of Atherosclerosis

Atherosclerosis together with multiple sclerosis, psoriasis and rheumatoid arthritis can be used as examples of chronic inflammatory diseases associated with multifactorial components that evolve over the years. Nevertheless, an important difference between these diseases relies on the fact that atherosclerosis develops from early ages where inflammation dominates the very beginning of the disease. This review highlights the inflammatory nature of atherosclerosis and the role the immune system plays in the process of atherogenesis. Although treatment of atherosclerosis has been for years based on lipid-lowering therapies reducing a series of risk factors, the degree of success has been only limited because cardiovascular complications related to the evolution of atherosclerotic lesions continue to appear in the population worldwide. In this sense, alternative treatments for atherosclerosis have come into play where both innate and adaptive immunity have been proposed to modulate atherosclerosis-associated inflammatory phenomena. When tested for their atheroprotective properties, several immunogens have been studied through passive and active immunization with good results and, therefore, the strategy through vaccination to control the disease has been made possible. Many experimental pre-clinical studies demonstrating proof of concept that vaccination using DNA and protein with an effective use of adjuvants and the optimal route of administration now provide a tangible new therapeutic approach that sets the stage for several of these vaccines to be tested in large, randomized, long-term clinical studies. A vaccine ready for human use will only be accomplished through the close association between academia, regulatory government organizations and private industry, allowing the reality of a simple and successful therapy to reduce atherosclerosis and its severe clinical complications.

Immunomodulation therapy of diabetes by oral administration of a surfactin lipopeptide in NOD mice

Type 1 diabetes mellitus (T1DM) is considered an autoimmune disease, which can be attenuated by modulation of immune pathway from Th1- to Th2-type through vaccination. WH1fungin surfactin is a Bacillus-produced natural immunomodulator. NOD mice were orally treated with 5mg/kg or 25mg/kg WH1fungin once a week for total 4 weeks. After the final administration, the diabetes incidence and the anti-inflammatory roles of WH1fungin were investigated by immunohistochemistry, FACS and ELISA. The results showed oral WH1fungin obviously resulted in a WH1fungin-unspecific suppression of T1DM. Diabetes incidence was significantly reduced when compared to phosphate buffered saline (PBS) control. Mice in the control group began to be onset of diabetes at week 15, following with an increased mortality from week 16 to 28. At the end of observation, the diabetes incidence reached to 81% at week 30, while only 25% in WH1fungin groups. The splenocytes assay showed oral WH1fungin could suppress T cells proliferation, down-regulate amounts of activated CD8(+) T cells with the production of tumor necrosis factor (TNF)-α and interferon (IFN)-γ, and increase CD4(+)CD25(+)FOXP3(+) regulator T cells (Tregs). The serum assay revealed oral WH1fungin down-regulated TNF-α and IgG2a but increased interleukin (IL)-10 and IgG1 in mice. All of these data showed oral WH1fungin tended to switch the immune response from Th1- to Th2-type. The further surveys revealed that less IFN-γ but more transfer growth factor (TGF)-β were found in the islets of mice with oral WH1fungin when compared to that in the control group. As a result, the normal islet architecture and slight inflammatory cells infiltration was observed with a slight insulitis in the oral WH1fungin groups. These results demonstrate that oral WH1fungin might be a novel therapeutic approach for the prevention of T1DM.

Advances in immune-modulating therapies to treat atherosclerotic cardiovascular diseases

In addition to hypercholesterolemia, innate and adaptive immune mechanisms play a critical role in atherogenesis, thus making immune-modulation therapy a potentially attractive way of managing atherosclerotic cardiovascular disease. These immune-modulation strategies include both active and passive immunization and confer beneficial reduction in atherosclerosis. Preclinical studies have demonstrated promising results and we review current knowledge on the complex role of the immune system and the potential for immunization as an immune-modulation therapy for atherosclerosis.

Can we vaccinate against atherosclerosis?

A large body of evidence implicates the immune system in the pathogenesis of atherosclerosis. Both active and passive immunizations have been tested as immunomodulation strategies to confer protective effect against atherogenesis. This review focuses on the current knowledge of the complex role and the potential for immune modulation therapy via active immunization for atherosclerosis.

Activation of inflammatory cells and cytokines by peptide epitopes in vitro: a simple in-vitro screening assay for prioritizing them for in-vivo studies

OBJECTIVE

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.

MATERIALS

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.

RESULTS AND CONCLUSION

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.

A perspective for atherosclerosis vaccination: is there a place for plant-based vaccines?

Alternatives to pharmacological treatments for atherosclerosis are highly desirable in terms of cost and compliance. During the last two decades several vaccination strategies have been reported as an effort to develop immunotherapeutic treatments. This approach consists on eliciting immune responses able to modulate either the atherosclerosis-associated inflammatory processes or the activity of some physiological mechanisms that are up-regulated under this pathologic condition. In particular, the apolipoprotein B100 (ApoB100) and the cholesterilester transferase protein (CETP) have been targeted in these strategies. It is considered that recent progress in the development of experimental models of oral vaccines against atherosclerosis has opened a new avenue in the field: as plant-based vaccines are considered a viable platform for vaccine production and delivery at low costs, they could serve as an oral-delivered therapeutic approach for atherosclerosis in an economical and patient-friendly manner. The rationale of the design, development and evaluation of possible plant-based vaccines against atherosclerosis is discussed in this review. We identify within this approach a significant trend that will positively impact the field of atherosclerosis vaccination.

Nasal immunization with different forms of heat shock protein-65 reduced high-cholesterol-diet-driven rabbit atherosclerosis

Heat shock protein-65 (Hsp65) is an important pro-atherogenic factor, but nasal immunization of Hsp65 can induce immune tolerance and reduce atherosclerotic inflammation. Here, we describe the effects of different forms of Hsp65 antigen inoculated, i.e. Hsp65 DNA, Hsp65 protein, Hsp65 DNA prime combined with Hsp65 protein boost, on high-cholesterol-diet-driven rabbit atherosclerosis lesions. The results showed that sera anti-Hsp65 IgG antibodies were lower induced and protective anti-Hsp65 IgA in nasal cavity and lung were induced after rabbits were immunized with different forms of Hsp65. However, the avidity between Hsp65 IgG antibody and antigen is different. Hsp65 DNA prime-protein boost could further improve the avidity compared with Hsp65 DNA immunization alone, but only immunization with Hsp65 protein alone obtain the best avidity. In addition, more protective IL-10 and less adverse IFN-γ were produced and sera TC and LDL-C were decreased obviously at different extents in immunized groups. As a result, atherosclerosis lesions were significantly attenuated, but only nasal immunization with Hsp65 protein alone may be the best effective form of Hsp65 antigen to control atherosclerotic lesions. The results demonstrated that different forms of Hsp65 antigen could produce different effects in the treatment of atherosclerosis. Immunization mucosally with Hsp65 protein could be a promising therapeutic method for atherosclerosis.

Effects of nasal immunization of multi-target preventive vaccines on atherosclerosis

Previous investigations have demonstrated that anti-inflammatory or lipid-lowering treatments could be useful for alleviating morbidity and mortality of atherosclerotic cardiovascular diseases. However, whether a vaccine designed to target inflammation and lipid simultaneously is more powerful to control the process of atherosclerosis remain to be unknown. Here, a vaccine was designed to target heat shock protein-65(Hsp65) and cholesteryl ester transfer protein (CETP) simultaneously and the effects of nasal immunization of multi-target vaccine on high-cholesterol-diet-driven rabbit atherosclerosis lesions were evaluated. Sera, nasal lavages and lung washes were used to ELISA assay for the analysis of IgG and IgA against Hsp65 and CETP. Sera were also used to the analysis of the avidity of combination of anti-Hsp65 and anti-CETP IgG antibodies with corresponding antigen, cytokines IL-10 and IFN-γ, and lipoproteins. In addition, aortas were harvested for analysis of atherosclerotic lesions. The results showed that lower and lasting specific anti-Hsp65 IgG and high anti-CETP IgG in sera and protective anti-Hsp65 and anti-CETP IgA in nasal cavity and lung were induced, the avidity of combination of anti-Hsp65 and anti-CETP IgG with antigen were higher, and more protective IL-10 and less adverse IFN-γ were produced. In addition, sera TC, and LDL-C were decreased. As a result, the size of aorta atherosclerotic plaques was significantly reduced. We conclude that multifaceted vaccine combining lipid-regulating with anti-inflammation was a potential remedy, especially for atherosclerosis with complicated etiology.

Vaccination strategies in atherosclerosis

The treatment of atherosclerosis is currently based on lipid lowering in combination with anti-inflammatory therapies that slow the progression of atherosclerosis. Still, we are not able to fully inhibit the formation or progression of atherosclerotic lesions. A very effective strategy in other disease pathologies is vaccination, in which the body is challenged with the culprit protein or micro-organism in order to create a highly specific humoral immune-response. Immunisation can typically be divided into active or passive immunisation. Active immunisation occurs naturally when the body is exposed to certain microbes or antigens, but also artificially in the case of vaccination. Exposure to a microbe or antigen will result in the production of (antigen specific) antibodies. Passive immunisation is defined as the transfer of humoral immunity (as a result of antibody transfer). Another mechanism to ensure immune-protection is tolerance induction. Immune tolerance occurs naturally to prevent immune responses to 'self-antigens', but can also be induced to non-self antigens. Acquired tolerance to foreign antigens is accompanied by suppression of cellular and/or humoral immune response to the introduced antigen. In its most effective way, vaccination can result in a lifelong protection against the targeted pathology, and therefore the development of an atherosclerosis-specific vaccination is of high importance in the future prevention of atherosclerosis. One of the difficulties in developing effective vaccination strategies for atherosclerosis is the selection of a specific antigen to target. So far vaccination strategies have been based on targeting of lipid-antigens, inflammation-derived antigens, and recently cell-based vaccination strategies have been employed; but also the cardiovascular 'side-effects' of infection-based vaccines are worthy of our attention. This review describes the current status-quo on classical antibody associated vaccination strategies but also includes promising immune-modulation approaches that may lead to a clinical application.

Novel HDL-directed pharmacotherapeutic strategies

The burden of atherothrombotic cardiovascular disease remains high despite currently available optimum medical therapy. To address this substantial residual risk, the development of novel therapies that attempt to harness the atheroprotective functions of HDL is a major goal. These functions include the critical role of HDL in reverse cholesterol transport, and its anti-inflammatory, antithrombotic, and antioxidant activities. Discoveries in the past decade have shed light on the complex metabolic and antiatherosclerotic pathways of HDL. These insights have fueled the development of HDL-targeted drugs, which can be classified among four different therapeutic approaches: directly augmenting apolipoprotein A-I (apo A-I) levels, such as with apo A-I infusions and upregulators of endogenous apo A-I production; indirectly augmenting apo A-I and HDL-cholesterol levels, such as through inhibition of cholesteryl ester transfer protein or endothelial lipase, or through activation of the high-affinity niacin receptor GPR109A; mimicking the functionality of apo A-I with apo A-I mimetic peptides; and enhancing steps in the reverse cholesterol transport pathway, such as via activation of the liver X receptor or of lecithin-cholesterol acyltransferase.

Vaccination for atherosclerosis

Atherosclerosis is an inflammatory disease, and several antigens have been shown to activate the immune response and affect the development of atherogenesis. This suggests that modulation of the immune system could represent a useful approach to prevent and/or treat this disorder. A vaccination approach might be a useful, effective tool in the modern arsenal of cardiovascular therapy and could possibly be used on a large scale at a low cost. Several modalities of vaccines have been tested against lipoproteins, cholesterol, molecules involved in cholesterol metabolism, atherosclerosis-associated microorganisms, and other molecules (heat shock protein, CD99, vascular endothelial growth factor-receptor, interleukin-2), with promising results. Nevertheless, a deeper understanding of the role of immunization in atherosclerosis will be essential to the use of vaccines in clinical medicine.

Safety and efficacy trial of adipose-tissue derived oral preparation V-6 Immunitor (V-6): results of open-label, two-month, follow-up study

Background

Chronic inflammations, atherosclerosis and obesity, are major risk factors for cardiovascular diseases. Immune modulation of the inflammatory response has shown promise in animal models of atherogenesis and metabolic disease. Tableted dietary supplement, V-6, containing pooled antigens derived from pig adipose tissue has been administered daily to 12 volunteers for 2 months.

Results

No significant changes were observed in liver ALT and AST enzymes, i.e., 28 vs 23.8 IU and 22.6 vs 24.8 IU, with p = 0.07 and p = 0.49, respectively. Creatinine decreased; 0.88 vs 0.84 mg/dL (p = 0.05) while BUN moved upward; 14.5 vs 17.5 mg/dL (p = 0.01), but both values remained within normal range. Blood glucose remained within normal range; 96.1 vs 101.1 mg/dL (p = 0.04). Complete blood cell analysis has not revealed any change except slight increase in hemoglobin; 13.13 to 13.96 g/dL (p = 0.0002); hematocrit and red blood cells count 40.3 to 42.3% (p = 0.02) and 5.15 to 5.35 × 10⁶ cells/mm³ (p = 0.03) respectively. Blood pressure systolic and diastolic values were not affected, i.e., 116.1 vs 116.3 (p = 0.12) and 76.8 vs 76.6 (p = 0.99). Body weight and body mass index (BMI) remained same; 66.4 vs 66.3 kg (p = 0.47) and 25.7 vs 25.6 kg/m² (p = 0.2). Body fat deposit indices, such as abdomen; mid-arm; and thigh circumferences declined by 3.5 cm (p = 0.008); 1.2 cm (p = 0.004); and 3.0 cm (p = 0.0007) respectively. The total cholesterol and LDL levels did not change; 195.5 vs 195.1 (-0.2%; p = 0.8) and 113.4 vs 120.3 (6.1%; p = 0.08) respectively. Triglycerides have been reduced but not statistically significant; 168.1 vs 118 mg/dL (-29.8%; p = 0.2). In contrast, HDL content had risen by 29.7% from 39.4 to 51.1 mg/dL in all 12 patients (p = 0.000003). TG/HDL ratio - a marker of insulin resistance - was reduced from 4.78 to 2.56 (-46.5%; p = 0.04).

Conclusions

These results demonstrate that V-6 is safe and has a potential as an anti-atherogenic and overweight/obesity immune intervention.

Intranasal immunization with chitosan/pCETP nanoparticles inhibits atherosclerosis in a rabbit model of atherosclerosis

In search of a convenient and pain-free route of administration of DNA vaccine against atherosclerosis, the plasmid pCR-X8-HBc-CETP (pCETP) encoding B-cell epitope of cholesteryl ester transfer protein C-terminal fragment displayed by Hepatitis B virus core particle was condensed with chitosan to form chitosan/pCETP nanoparticles. Cholesterol-fed rabbits were then intranasally immunized with the chitosan/pCETP nanoparticles to evaluate antiatherogenic effects. The results showed that significant serum antibodies against CETP were detected by enzyme-linked immunosorbent analysis and verified by Western blot analysis. The significant anti-CETP IgG lasted for 21 weeks in the rabbits immunized intranasally. Moreover, the atherogenic index was significantly lower compared with the saline control (5.95 versus 2.39, p<0.05). In addition, the average percentage of aortic lesions in the entire aorta area in the rabbits intranasally vaccinated with nanoparticles was 59.2% less than those treated with saline (29.0+/-10.9% versus 71.0+/-14.4%, p<0.01) and was similar to those intramuscularly injected with pCETP solution (29.0+/-10.9% versus 21.2+/-14.2%, p>0.05). Thus, chitosan/pCETP nanoparticles could significantly attenuate the progression of atherosclerosis by intranasal immunization. The results suggested that intranasal administration could be potentially developed as a vaccination route against atherosclerosis.

A vaccine against atherosclerosis: myth or reality?

Atherosclerosis is a chronic inflammatory disease that develops in the context of enhanced serum lipid levels. Nowadays, many studies focus on the modulation of inflammatory responses to reduce atherosclerosis. The most powerful strategy to achieve this is vaccination. In several immune diseases vaccination is shown to be very effective, resulting in a drastic decline in the incidence of the disease. But is vaccination also realistic in atherosclerosis? In this article, several approaches to vaccinate against atherosclerosis are described. Vaccination (based on protein or DNA) against bioactive molecules and disease-related proteins successfully reduces experimental atherosclerosis. In addition, passive immunization with antibodies against atherosclerosis-specific antigens and tolerance induction, in which antigen-specific regulatory T cells are elicited, are described. In the near future, we expect an increased interest in vaccination against atherosclerosis and, maybe, the myth may become reality when the first clinical trials are performed.

Is raising HDL a futile strategy for atheroprotection?

The dramatic failure of clinical trials evaluating the cholesterol ester transfer protein inhibitor torcetrapib has led to considerable doubt about the value of raising high-density lipoprotein cholesterol (HDL-C) as a treatment for cardiovascular disease. These results have underscored the intricacy of HDL metabolism, with functional quality perhaps being a more important consideration than the circulating quantity of HDL. As a result, HDL-based therapeutics that maintain or enhance HDL functionality warrant closer investigation. In this article, we review the complexity of HDL metabolism, discuss clinical-trial data for HDL-raising agents, including possible reasons for the failure of torcetrapib, and consider the potential for future HDL-based therapies.

Immunization for atherosclerosis

This review summarizes experimental findings that highlight the complex roles of the immune system in atherogenesis. Immune activation can have either proatherogenic or atheroprotective effects. Immune-modulation therapy via an active or passive immunization strategy aims to exploit the atheroprotective aspects of the immune system to modulate atherosclerosis. Several experimental studies have demonstrated that such an approach is feasible and effective, raising the tantalizing possibility that an atheroprotective vaccine can be developed for clinical testing. Several potential immunogens have been identified and tested for their atheroprotective efficacy with variable results. Although several questions such as choice of optimal antigens, choice of most effective adjuvants, the optimal route of administration, durability of effects, and safety remain to be answered, we believe that a vaccine-based approach to manage atherosclerotic cardiovascular disease is a potentially viable paradigm.

Immunomodulation of the inflammatory response in atherosclerosis

PURPOSE OF REVIEW

Cardiovascular disease, as manifested in the formation of atherosclerotic lesions, can be described as a chronic inflammatory autoimmune-like disease that proceeds in the context of enhanced plasma lipid levels. Modulation of the immune response may therefore form a valuable therapy in addition to standardized cholesterol and blood pressure-lowering therapies. The purpose of this review is to describe a number of recent approaches to immunomodulate atherosclerosis: immunization against mediators involved in atherosclerosis, such as cytokines and modified low-density lipoprotein; intervention in cytokine pathways; intervention in co-stimulatory pathways; activation of regulatory T cells; and modulation of natural killer T cells.

RECENT FINDINGS

The most recent findings point to an important role for regulatory T cells in atherosclerotic lesion formation. The function of the regulatory T cells is modulated by chemokines and by co-stimulatory pathways, whereas the function of these cells can be strongly upregulated by anti-CD3 treatment and tolerance induction.

SUMMARY

In the near future the first exponents of this approach, such as immunization and enhancement of the function of regulatory T cells, may enter the first phase of clinical trials, and may ultimately add to the current therapies in atherosclerosis.

Vaccines for cholesterol management

Over the last 50 years, several attempts have been made to harness the power and economy of vaccines in the fight against cardiovascular disease. Vaccines directed to lipoproteins, cholesterol itself, and molecules involved in cholesterol metabolism have all demonstrated success in modifying progression of disease in animal models of atherosclerosis. One vaccine that elicits antibodies to cholesteryl ester transfer protein has also progressed into the realm of human clinical testing. This review summarizes the published scientific work describing the various approaches that have been tried, their strengths and weaknesses, and where this field may go in the future.

Heat-Shock Protein 65 Autoantibodies Are Differently Associated with Early Atherosclerosis in Rheumatoid Arthritis and in Healthy Subjects

The aim of this study was to examine whether heat-shock protein (HSP)-65 autoantibodies are associated with early atherosclerosis in rheumatoid arthritis (RA). Intima-media thickness (IMT) was measured in the carotid arteries of 100 RA patients and 69 control subjects. The IMT was evaluated on both carotid arteries in the common carotid, bifurcation, and internal arteries. Every patient underwent anti-HSP-65 antibody evaluation. Anti-HSP-65 antibodies were not more prevalent among patients compared with controls. Among controls, patients having "positive" anti-HSP-65 tended to have increased carotid artery IMT compared with "negative" patients, whereas among RA patients the opposite association was noted, and positive patients had significantly decreased carotid bifurcation IMT than negative patients without elevated levels of anti-HSP-65. As opposed to the association with cardiovascular diseases and atherosclerosis of anti-HSPs in the general population, among RA patients anti-HSP-65 cannot be regarded as associated with early atherosclerosis.

High-density lipoproteins: a therapeutic target for atherosclerotic cardiovascular disease

Despite great progress being made during the last two decades in cardiovascular disease prevention, especially by lowering low-density lipoprotein-cholesterol with statins, cardiovascular events continue to occur. Plasma high-density lipoprotein (HDL) exerts multiple protective effects on the arterial wall, through promotion of reverse cholesterol transport, prevention of endothelial dysfunction and inhibition of lipid oxidation. Therapeutic interventions raising plasma HDL levels or directly mimicking its beneficial effects represent the next frontier in the prevention and treatment of cardiovascular disease.

Vaccines for the prevention of cardiovascular disease

Atherosclerosis, especially coronary heart disease (CHD), remains a most significant global public health problem. Highly effective LDL-lowering therapies have gained widespread adoption in the United States and throughout the developed world, but therapeutic options for raising low HDL, a key independent risk factor for CHD, remain limited. We are developing a vaccine approach to raising HDL, by inducing an immune response to endogenous cholesteryl ester transfer protein (CETP), and have demonstrated proof of principle in preclinical and clinical models. This vaccine approach may offer the opportunity to address low HDL with a cost-effective semi-annual injection.

Intramuscular immunization with a DNA vaccine encoding a 26-amino acid CETP epitope displayed by HBc protein and containing CpG DNA inhibits atherosclerosis in a rabbit model of atherosclerosis

Rabbits were intramuscularly immunized with the plasmid pCR-X8-HBc-CETP encoding a B-cell epitope of cholesteryl ester transfer protein (CETP) C-terminal fragment (CETPC) displayed by Hepatitis B virus core (HBc) particle. This plasmid also contained immunostimulatory sequences (ISS) which included eight CpG motifs 5'-GACGTT-3', functioning as immunomodulators. After anti-CETP antibodies were successfully produced, rabbits were fed with a high-cholesterol diet for 15 weeks, and then the antiatherogenic effects of this DNA immunization were evaluated. The results showed that the fraction of plasma cholesterol in HDL significantly increased and the fraction of plasma cholesterol in LDL decreased in the pCR-X8-HBc-CETP immunized rabbits compared with those in the saline control group and one group treated with the plasmid pCR-X8-HBc containing ISS but lacking CETP epitope. More importantly, DNA immunization with pCR-X8-HBc-CETP markedly reduced the average percentage of aortic lesions in the entire aorta area by 80.60% compared with the saline control (3.78% versus 19.48%) and the average thickness of hyperplastic coronary artery in this group was also significantly less than in the saline control group (146+/-11 microm versus 248+/-18 microm). Our data also showed that CpG DNA alone could be antiatherogenic in this model because the average percentage of aortic lesions in pCR-X8-HBc immunized rabbits was 16.53% lower than that of the saline control group and the average thickness of hyperplastic coronary artery was also substantially lower than saline control group (155+/-13 microm versus 248+/-18 microm). Thus, plasmid pCR-X8-HBc-CETP could significantly inhibit the progression of atherosclerosis and be potentially developed as a suitable DNA vaccine against atherosclerosis.

Cholesteryl ester transfer protein (CETP) inhibition beyond raising high-density lipoprotein cholesterol levels: pathways by which modulation of CETP activity may alter atherogenesis

Raising high-density lipoprotein cholesterol (HDL-C) is a promising strategy in the struggle to prevent cardiovascular disease, and cholesteryl ester transfer protein (CETP) inhibitors have been developed to accomplish this. The first results are encouraging, and, in fact, in rabbits, inhibition of CETP reduces atherosclerosis. Because human data regarding the reduction of atheroma burden require more time, the biochemical mechanisms underlying the putative atheroprotection of CETP inhibitors are currently dissected, and several pathways have emerged. First, CETP inhibition increases HDL-C and reduces low-density lipoprotein cholesterol (LDL-C) levels consistent with CETP lipid transfer activity and its role in reverse cholesterol transport (RCT). This coincides with putative beneficial increases in both HDL and LDL size. However, many aspects regarding the impact of CETP inhibition on the RCT pathway remain elusive, in particular whether the first step concerning cholesterol efflux from peripheral tissues to HDL is influenced. Moreover, the relevance of scavenger receptor BI and consequently the central role of HDL in human RCT is still unclear. Second, CETP inhibition was shown recently to increase antioxidant enzymes associated with HDL, in turn associated with decreased oxidation of LDL. Atheroprotection in man is currently anticipated based on the improvement of these biochemical parameters known to influence atherosclerosis, but final confirmation regarding the impact of CETP inhibition on cardiovascular outcome will have to come from trials evaluating clinical end points.

Inhibitors of cholesteryl ester transfer protein – a new approach to coronary artery disease

Despite the use of the statins to lower low-density lipoprotein-cholesterol, leading to major reductions in the mortality and morbidity that is associated with coronary artery disease, considerable mortality and morbidity remains. Increasing high-density lipoprotein (HDL)-cholesterol levels has been associated with reduced coronary artery disease mortality and morbidity in several studies. Inhibition of cholesteryl ester transfer protein (CETP) activity leads to increased HDL-cholesterol. In cholesterol-fed rabbits, antibodies against CETP increased HDL-cholesterol and decreased atherosclerotic lesions. In healthy subjects with mild dyslipidaemia, the CETP inhibitors JTT-705 and torcetrapib increased HDL-cholesterol and decreased low-density lipoprotein-cholesterol. Increasing HDL-cholesterol with CETP inhibitors is a new approach to dyslipidaemia that requires further investigation, especially in patients who have coronary artery disease.