Heat shock protein 60/65, beta 2-glycoprotein I and oxidized LDL as players in murine atherosclerosis

Soluble Vascular Biomarkers in Rheumatoid Arthritis and Ankylosing Spondylitis: Effects of 1-year Antitumor Necrosis Factor-α Therapy

OBJECTIVE

Rheumatoid arthritis (RA) and ankylosing spondylitis (AS) have been associated with cardiovascular disease. The treatment of arthritis by tumor necrosis factor-α (TNF-α) inhibitors may decrease the serum concentrations of vascular biomarkers. We determined circulating levels of oxidized low-density lipoprotein (oxLDL)/β₂ glycoprotein I (β₂-GPI) complexes, antibodies to 60 kDa heat shock protein (anti-Hsp60), soluble urokinase plasminogen activator receptor (suPAR), and B-type natriuretic peptide (BNP) fragment in sera of RA and AS patients undergoing anti-TNF treatment.

METHODS

Fifty-three patients with RA/AS were treated with etanercept or certolizumab pegol for 1 year. Circulating oxLDL/β₂-GPI complex (AtherOx), anti-Hsp60 IgG, and BNP8-29 fragment levels were assessed by ELISA. suPAR levels were determined by suPARnostic Quick Triage test. Flow-mediated vasodilation (FMD), carotid intima-media thickness (CIMT), and arterial pulse wave velocity (PWV) were determined by ultrasound.

RESULTS

One-year anti-TNF treatment significantly decreased oxLDL/β₂-GPI levels, as well as suPAR levels in patients with critically high suPAR levels at baseline. In RA, BNP levels were higher in seropositive vs seronegative patients. Serum levels of these vascular biomarkers variably correlated with lipids, anticitrullinated protein antibodies, rheumatoid factor, and C-reactive protein. CIMT positively correlated with BNP, and PWV with suPAR and anti-Hsp60, whereas FMD inversely associated with anti-Hsp60. In repeated measures ANOVA analysis, disease activity supported the effects of anti-TNF treatment on 12-month changes in oxLDL/β₂-GPI. CIMT supported the effects of therapy on changes in anti-Hsp60 and suPAR.

CONCLUSION

These biomarkers may be involved in the pathogenesis of atherosclerosis underlying RA/AS. TNF inhibition variably affects the serum levels of oxLDL/β₂-GPI, suPAR, and BNP.

CD40 Ligand-Dependent Maturation of Human Monocyte-Derived Dendritic Cells by Activated Platelets

Atherosclerosis is defined as an inflammatory immunological disease that is triggered by platelet activation, endothelial injury and consequent innate and adaptive immune processes. Dendritic cells are critical for the cell-mediated arm of the immune response as they activate naïve T cells after maturation. Platelets play a crucial role in thrombus formation in the injured vessel walls. We investigated the role of resting and thrombin-activated platelets in dendritic cell maturation in vitro using platelets and monocyte-derived dendritic cells from healthy donors. Resting platelet supernatants did not affect maturation, whereas supernatants from thrombin-activated platelets induced dendritic cell maturation as demonstrated by FACS analysis of HLA-DR expression. This effect was inhibited by anti CD40 ligand antibody, but not by aspirin pretreatment of platelets. Supernatants of platelet-dendritic cell co-cultures induced augmented monocyte migration when platelets were activated by thrombin, again reversible by blocking CD40 ligand. These data show that activated platelets trigger dendritic cell maturation independent of cyclooxygenase-derived arachidonic acid metabolites by mechanisms involving CD40 ligand, which is also involved in monocyte chemotactic mediator release from platelets and dendritic cells. The results of this study suggest a role of CD40 ligand from activated platelets in connecting innate and adaptive immunity.

Tolerization against atherosclerosis using heat shock protein 60

Atherosclerosis is a chronic inflammatory disease of the artery wall, and both innate and adaptive immunity play important roles in the pathogenesis of this disease. In several experimental and human experiments of early atherosclerotic lesions, it has been shown that the first pathogenic event in atherogenesis is intimal infiltration of T cells at predilection sites. These T cells react to heat shock protein 60 (HSP60), which is a ubiquitous self-antigen expressed on the surface of endothelial cells (ECs) together with adhesion molecules in response to classical risk factors for atherosclerosis. When HSP60 is expressed on the EC surface, it can act as a "danger-signal" for both cellular and humoral immune reactions. Acquired by infection or vaccination, beneficial protective immunity to microbial HSP60 and bona fide autoimmunity to biochemically altered autologous HSP60 is present in all humans. Thus, the development of atherosclerosis during aging is paid by the price for lifelong protective preexisting anti-HSP60 immunity by harmful (auto)immune cross-reactive attack on arterial ECs maltreated by atherosclerosis risk factors. This is supported by experiments, which shows that bacterial HSP60 immunization can lead and accelerate experimental atherosclerosis. This review article presents accumulating proof that supports the idea that tolerization with antigenic HSP60 protein or its peptides may arrest or even prevent atherosclerosis by increased production of regulatory T cells and/or anti-inflammatory cytokines. Recent data indicates that HSP60, or more likely some of its derivative peptides, has immunoregulatory functions. Therefore, these peptides may have important potential for being used as diagnostic agents or therapeutic targets.

Promotion of atherosclerosis in high cholesterol diet-fed rabbits by immunization with the P277 peptide

Previous evidence has proved the ability of immunization with heat shock protein (HSP) 60/65 to induce atherosclerosis. P277, a 24-residue peptide of human HSP60, is a promising peptide vaccine against autoimmune diabetes. But as a fragment of HSP60, its potential ability of promoting atherosclerosis has never been investigated yet. In the present study, the rabbits fed with normal standard diet or high cholesterol diet were immunized with P277 or PBS emulsified in incomplete Freund's adjuvant 4 times at 4-week intervals. Atherosclerotic lesions of the rabbits receiving P277 treatment and fed with high cholesterol diet increased significantly compared with those of the rabbits receiving PBS treatment and the same diet. However, no obvious lesions were found in the two groups of rabbits fed with the normal standard diet. Significant expression of P277 was detected in the high cholesterol diet-induced atherosclerotic lesions and heat-stressed endothelial cells. Surface exposure of P277 was also observed in the stressed cells. In the subsequent assay of endothelial cells in vitro, the purified anti-P277 antibodies mediated a noticeable cytotoxicity to the stressed cells with the participation of complement. In conclusion, subcutaneous immunization with P277 emulsified in IFA can aggravate the atherosclerosis in high cholesterol diet-fed rabbits. Surface expression of P277 was observed on stressed endothelial cells, and were suggested to mediate the autoimmune attack and promote the disease.

The virus-induced HSPs regulate the apoptosis of operatus APCs that result in autoimmunity, not in homeostasis

The viruses stand salient as environmental factors that trigger autoimmunity. The virus realizes its effects through induction of heat-shock proteins (HSPs) as well as by the viral IE-axis-mediated conversion of organ epithelial cells into virgin de novo professional antigen-presenting cells (APCs). The HSP is the accomplished operator in homeostasis by the logic of it being the regulator of apoptosis. By virtue of its regulation of apoptosis, the HSP is also involved in autoimmunity: (1) adornment of viral IE-axis-generated virgin de novo professional APCs with HSP-induced co-stimulatory molecules which transform these otherwise epithelial cells to competent antigen presenters, the operatus APCs, liable to apoptosis that becomes the initiator of organ damages; (2) molecular mimicry mechanism: epitopes on the HSP may be mistaken for viral peptides and be presented by operatus APCs to autoreactive TCRs resulting in the apoptosis of the operatus APCs; (3) regulation of MHC class II DR-mediated apoptosis of operatus APCS which can result in organ-specific autoimmune syndromes. We should remember, however, that Nature's intended purpose for apoptosis of the professional APCs is benevolence: as a principal regulator of immune homeostasis. But the apoptosis of our postulated operatus APCs can result in autoimmunity. The transformation of virgin de novo professional APCs to operatus APCs mirrors the maturation of DCs through their acquisition of HSP-induced costimulatory molecules. What happens to mature DCs as antigen presenters that end in homeostasis is replicated by what happens to operatus APCs that ends instead in autoimmunity.

Humoral response against small heat shock proteins in Parkinson's disease

Introduction

In the light of evidence for the increased heat shock proteins (HSP) expression in neurodegenerative disorders, the presence of the adaptive humoral response of the immune system can be expected. The aim of the study was to check whether Parkinson’s disease (PD) has the ability to elicit immune response against small heat shock proteins.

Methods

IgG and IgM autoantibodies against alpha B-crystallin were assessed in 26 PD patients 26 healthy subjects. For the assessment of anti-HSP IgG autoantibodies serum samples from 31 parkinsonian patients and 31 healthy control subjects were collected. Serum samples from PD patients and healthy control subjects were collected twice, at baseline and after mean of 13 months follow up.

Results

Both IgM and IgG autoantibodies against alpha ß-crystallin in PD patients were significantly higher compared to healthy controls (p<0.05). We also found statistically significant increase in antibodies titers against alpha ß-crystallin over the time of 13 months, both for IgG (p = 0.021) and for IgM (p<0.0001). Additionally, PD patients presented higher levels of anti-HSP IgG autoantibodies than healthy controls (p = 0.02).

Conclusions

Increase of IgG and IgM autoantibodies against alpha B-crystallin in PD patients over time may suggest their involvement in the disease pathogenesis and progression. Further studies are required to confirm the role of this antibody as a biomarker of the disease progression.

The virus-induced HSPs regulate the apoptosis of operatus APCs that results in autoimmunity, not in homeostasis

The viruses are salient in the roles of environmental factors that trigger autoimmunity. The virus realizes its effects by the power of its induction of heat shock proteins (HSPs) as well as by the viral IE-axis-mediated conversion of organ epithelial cells into virgin de novo professional antigen-presenting cells (APCs). The HSP is the accomplished operator in homeostasis by the logic of it being the regulator of apoptosis. That HSP which regulates and controls different points in the pathways of apoptosis is rationally propitious as both HSP and apoptosis are highly conserved in multicellular organisms. By virtue of its regulation of apoptosis, the HSP is also involved in human autoimmunity and this involvement is tripartite: (i) adornment of viral IE-axis-generated virgin de novo professional APCs with HSP-induced co-stimulatory molecules which transform these otherwise epithelial cells to achieve the status of fledged competent antigen-presenters, the operatus APCs, which are liable to apoptosis that becomes the initiator of organ damages that can culminate in the autoimmune syndrome(s); apoptosis is a routine fate that befalls all APCs following their antigen presentation; (ii) molecular mimicry mechanism: epitopes on the HSP may be mistaken for viral peptides and be presented by operatus APCs to autoreactive TCRs resulting in the apoptosis of the operatus APCs; and (iii) regulation of MHC class II-DR-mediated apoptosis of operatus APCs which can ultimately consequent in organ-specific autoimmune syndromes. We should remember, however, that Nature's intended purpose for the apoptosis of the professional APCs is benevolence: as a principal regulator of homeostasis. It is only from the apoptosis of our postulated operatus APCs that the apoptotic consequence can be deleterious, an autoimmune syndrome(s). The transformation of virgin de novo professional APCs to operatus APCs mirrors the maturation of DCs, through their acquisition of HSP-induced co-stimulatory molecules; and what happens to mature DCs as antigen-presenters that ends in homeostasis is replicated by what happens to operatus APCs that ends instead in autoimmune syndromes (Fig. 1).

Oxidative risk for atherothrombotic cardiovascular disease

In the vasculature, reactive oxidant species, including reactive oxygen, nitrogen, or halogenating species, and thiyl, tyrosyl, or protein radicals may oxidatively modify lipids and proteins with deleterious consequences for vascular function. These biologically active free radical and nonradical species may be produced by increased activation of oxidant-generating sources and/or decreased cellular antioxidant capacity. Once formed, these species may engage in reactions to yield more potent oxidants that promote transition of the homeostatic vascular phenotype to a pathobiological state that is permissive for atherothrombogenesis. This dysfunctional vasculature is characterized by lipid peroxidation and aberrant lipid deposition, inflammation, immune cell activation, platelet activation, thrombus formation, and disturbed hemodynamic flow. Each of these pathobiological states is associated with an increase in the vascular burden of free radical species-derived oxidation products and, thereby, implicates increased oxidant stress in the pathogenesis of atherothrombotic vascular disease.

Heat-shock protein 60 and cardiovascular disease: a paradoxical role

Heat-shock proteins (HSPs) are members of a highly conserved group of proteins that are induced in response to stress and injury. These proteins have protective properties, and can protect the heart from injury. HSP60 is found in the mitochondria and cytosol, and has essential intracellular functions including folding key proteins after their import into the mitochondria. In the cytosol, HSP60 binds to proapoptotic proteins, sequestering them. HSPs are highly conserved and, thus, are similar to bacterial proteins. Many individuals have antibodies to HSP60, possibly from prior infections. HSP60 can be found in the plasma membrane and in the serum in disease states. Serum HSP60 may be a marker for coronary artery disease. Once extracellular, HSP60 can cause cell injury. Thus, this protein has dichotomous functions for which the role in disease remains to be fully elucidated.

Antibodies against heat shock protein 60 derived from Helicobacter pylori: diagnostic implications in cardiovascular disease

Immune responses against heat shock protein 60 (HSP60) of pathogen-origin are thought to be defensive events which, due to molecular mimicry, misdirect to a human counterpart. Therefore, atherosclerosis may be serologically predicted by anti-HSP60 antibodies (Abs). In the present study, we analyzed the clinical prevalence of the serum IgG Abs against Helicobacter pylori (Hp)-derived HSP60 (Hp-HSP60) or its peptide fragments in patients with cardiovascular disease (CVD; n=250), as compared to those in age- and gender-matched non-CVD patients (n=293). Anti-Hp cell lysate Abs frequently appeared in Hp-infected patients who were not associated with CVD. In contrast, Abs against the particular amino acid sequence Hp-HSP60(II3) (II3 region, Glu(141)-Leu(160), in Hp-HSP60) predominantly appeared in CVD patients, as well as IgG anti-human HSP60 (Hu-HSP60(w)). Furthermore, neither titer of anti-Hp-HSP60(II3) nor anti-Hu-HSP60(w) Abs was correlated with the levels of high sensitivity C-reactive protein (hsCRP). This data strongly suggested that IgG anti-Hp-HSP60(II3) Abs cross-reacted with Hu-HSP60(w) were independent diagnostic markers relevant to CVD. Further, the 20 amino acid residues (Glu(141)-Leu(160)) might be predominant CVD-associated epitopes that induce anti-Hu-HSP60 auto-Abs, whose location was predicted in the tertiary structure of Hu-HSP60.

Autoreactive antibodies are present in sheep with Johne's disease and cross-react with Mycobacterium avium subsp. paratuberculosis antigens

Mycobacterial infection has been linked to the generation of autoantibodies, including anti-neutrophil cytoplasmic autoantibodies (ANCA), in clinical studies and small animal models. In an attempt to identify antibodies that react with both self and mycobacterial antigens in naturally infected ruminants, we generated a phage display library comprising single chain antibody fragments (scFv) from sheep with Johne's disease (JD). The library was screened simultaneously against ovine small intestinal tissue and Mycobacterium avium subsp. paratuberculosis (MAP). A clone (termed AutoH1) reacted strongly with host tissue and MAP, recognizing a proteinase-susceptible 32 kDa determinant in ovine gut tissues and lymphatics, and in blood granulocytes but not mononuclear cells. In granulocytes, binding was to cytoplasmic granules and cell membranes; in MAP, AutoH1 bound bacterial cell wall determinants. We further identified a synthetic peptide sequence recognized by AutoH1, using this to generate a carrier:peptide fusion protein (paH1). Sera of normal and JD sheep were screened for AutoH1-like autoantibody activity; 7/11 JD animals showed autoreactivity that could be blocked by paH1, while 0/21 normal animals showed no such serological reactivity. It is possible that the severe pathology observed in ruminant JD may have an autoimmune component, possibly due to ANCA-type binding; this remains to be further investigated.

The role of innate and adaptive immunity to oxidized low-density lipoprotein in the development of atherosclerosis

Atherosclerosis is a chronic inflammatory process of the arterial wall associated with systemic and local immune responses to various antigens, oxidized low-density lipoprotein (oxLDL) being the most significant. Both IgM and IgG antibodies to oxLDL are produced during atherosclerosis. Some studies have shown that elevated levels of antibody to oxLDL correlate with the degree of atherosclerosis. Other studies reported that immunization of experimental animals with oxLDL induces high levels of antibodies to oxLDL, with decreased atherosclerosis, suggesting that the immune response to oxLDL may be antiatherogenic. The accelerated development of atherosclerosis has been observed in patients with systemic autoimmune diseases. In patients with antiphospholipid syndrome (APS), beta2-glycoprotein I (beta2GPI) is a major antigenic target for anticardiolipin antibodies (aCLs). We recently reported that oxLDL interacts with beta2GPI via oxLDL-derived specific ligands, such as 7-ketocholesteryl-9-carboxynonanoate (oxLig-1) to form complexes. In vitro, anti-beta2GPI autoantibodies bind to oxLDL/beta2GPI complexes that are actively taken up by macrophages via Fcgamma receptors. Circulating oxLDL/beta2GPI complexes were detected in patients with systemic lupus erythematosus (SLE) and APS, at higher levels than in healthy individuals. Autoantibodies against these complexes were also present; however, IgG anti-oxLig-1/beta2GPI antibody levels in SLE patients with APS were significantly higher than those in SLE patients without APS and those in healthy individuals.

Accelerated atherosclerosis in patients with systemic autoimmune diseases

Systemic autoimmune diseases such as systemic lupus erythematosus and Wegener's granulomatosis are associated with a significantly increased prevalence of cardiovascular disease (CVD) compared with age- and sex-matched controls. Many risk factors are involved in the pathogenesis of atherosclerosis, the major underlying cause of CVD. In patients with systemic autoimmune diseases, it has been shown that traditional risk factors for CVD cannot completely explain the prevalence of atherosclerosis. Therefore, in addition to these traditional factors, nontraditional risk factors are suggested to contribute to atherogenesis. All risk factors, traditional and nontraditional, contribute to endothelial activation that, followed by endothelial dysfunction, is seen as one of the first steps in this process. This review updates information on the factors that contribute to accelerated atherosclerosis in patients with systemic autoimmune diseases, such as disease-related factors, inflammatory mediators, and advanced glycation end products.

Oxidized Low-Density Lipoprotein Autoantibodies, Chronic Infections, and Carotid Atherosclerosis in a Population-Based Study

OBJECTIVES

We investigated whether associations exist between immune reactions to oxidized low-density lipoproteins (OxLDLs), chronic infections, and carotid atherosclerosis as quantified by ultrasound.

BACKGROUND

Atherosclerosis is a chronic immuno-inflammatory disease wherein both oxidized lipids and infectious agents are incriminated as possible contributors.

METHODS

We measured immunoglobulin (Ig)G and IgM autoantibody titers to copper-oxidized-LDL and malondialdehyde-LDL (OxLDL-AB), IgG and IgM apolipoprotein B-100-immune complexes (ApoB-IC), and titers of antibodies to Escherichia coli and chlamydial lipopolysaccharide (LPS), mycobacterial heat shock protein 65 (mHSP65), Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus and evaluated their relationship to cardiovascular risk factors, chronic infections, and incident/progressive carotid atherosclerosis in the Bruneck study.

RESULTS

The OxLDL-AB and ApoB-IC levels remained stable over time as indicated by strong correlations between 1995 and 2000 measurements (p < 0.001 each). Significant associations existed between all OxLDL markers and antibody titers to pathogens, especially to E. coli-LPS and mHSP65. Both OxLDL-AB and ApoB-IC levels showed a rise with increasing pathogen burden. Notably, OxLDL-ABs were also elevated in subjects with chronic infection as defined by clinical criteria. Titers of IgG, but not IgM, OxLDL-AB, or ApoB-IC inversely correlated with total cholesterol, LDL cholesterol, and apoB concentrations. The IgG OxLDL markers were positively and IgM markers were inversely associated with incident and progressive carotid atherosclerosis in univariate analyses but were not independent predictors in multivariate analyses.

CONCLUSIONS

Our study provides evidence for an association between human oxLDL markers and chronic infections. Moreover, in this population-based study, neither IgG nor IgM OxLDL autoantibodies were independently predictive of atherosclerosis progression in the carotid arteries.

Intravenous immunoglobulin and atherosclerosis

Several inflammatory and immunological factors have been established as important contributors to atherogenesis. Among these, oxidized low-density lipoprotein (oxLDL) play a central role in the initiation and progression of atherosclerotic lesions. In atherosclerotic lesions, oxLDL was also found to co-localize with beta2-glycoprotein I (beta2-GPI). Immunoglobulin (Ig)G autoantibodies against beta2-GPI complexed with oxLDL are pro-atherogenic because they increase uptake of the complexes by macrophages. In contrast, IgM natural anti-oxLDL antibodies derived from atherosclerosis-prone apolipoprotein E (ApoE) deficient mice reduced incidence of atherosclerosis. Such anti-oxLDL antibodies have been found in humans, and the accumulating evidences seem to support the idea that anti-oxLDL antibodies have a protective role for atherogenesis. Intravenous immunoglobulins (IVIgs) contain natural anti-oxLDL antibodies and infusion of IVIg into ApoE-deficient mice has been reported to decrease atherosclerosis. The anti-atherogenic property of IVIg may be derived from non-antigen-specific antibody binding to FCgamma receptors, which blocks foam cell formation of macrophages. Several other possible mechanisms are also discussed.

Defects in regulation of local immune responses resulting in atherosclerosis

Atherosclerosis is nowadays generally accepted as an inflammatory disease but the mechanism of its origin and development have not yet been fully clarified. The present review focuses on the role of the local immune system as one of the key players in the pathogenesis of the complex process. Its part represented by vascular-associated lymphoid tissue (VALT) within the arterial wall participates directly in the vascular wall's homeostatis. Its inordinate activation during ontogenic development of an individual, this formerly defensive and physiologic mechanism transform into a pathological process resulting in an impairing inflammation. Hsp60, CRP and oxidized or otherwise modified LDL are serious candidates for triggering these pathological changes. The principal role is played by anti-Hsp60 antibodies and by shear stress originating on the surface of endothelium due to blood flow. The experimental and clinical data supporting this immunological hypothesis of atherosclerosis are discussed.

Mouse cytomegalovirus antigenic immune stimulation is sufficient to aggravate atherosclerosis in hypercholesterolemic mice

We have previously demonstrated that mouse cytomegalovirus (MCMV) infection aggravates atherosclerosis by stimulating the ongoing inflammatory process in the vascular wall. Here we investigated whether MCMV antigenic immune stimulation by UV-MCMV injection is sufficient to aggravate atherosclerosis. In addition we analyzed whether low viral doses are sufficient to stimulate atherosclerosis. Therefore, apoE(-/-) mice received a low dose injection with infectious virus (MCMV) or replication-deficient virus (UV-inactivated MCMV, UV-MCMV). Atherosclerosis progression, influx of inflammatory cells in atherosclerotic lesions and internal organs and the number of MCMV DNA copies in various organs were determined at 2 weeks after injection. After injection with infectious virus, MCMV DNA was present in internal organs, while no MCMV DNA could be detected after UV-MCMV injection. Interestingly, both MCMV and UV-MCMV significantly increased mean atherosclerotic lesion area and T cell number in the atherosclerotic lesions, while only MCMV infection increased T cell numbers in the internal organs. These data indicate that in apoE(-/-) mice both low dose infectious MCMV as well as MCMV antigenic injections are sufficient for atherosclerosis aggravation.

Heat shock protein 60 autoimmunity and early lipid lesions in cholesterol-fed C57BL/6JBom mice during Chlamydia pneumoniae infection

Chronic Chlamydia pneumoniae infection and autoimmunity to heat shock protein 60 (Hsp60) have both been documented to be associated with atherosclerosis. Herein, we studied the effects of C. pneumoniae infection and a diet with a low-cholesterol supplement on the development of autoantibodies to mouse Hsp60 and early lipid lesions in the aortic valve of C57BL/6JBom mice. In addition, pulmonary infection was investigated. C57BL/6JBom mice were given one to three C. pneumoniae inoculations and fed either a regular diet or a diet enriched with 0.2% cholesterol. Autoantibody responses against mouse Hsp60 developed in both diet groups when the mice were infected with C. pneumoniae and in uninfected mice fed a cholesterol-enriched diet. C. pneumoniae infections increased subendothelial foam cell accumulation in mice on a 0.2% cholesterol-enriched diet (p = 0.022), without apparent hypercholesterolemia. These in vivo data suggest that autoantibodies against mouse Hsp60 develop as a consequence of cholesterol feeding and repeated C. pneumoniae infections. Further, infectious burden increased early lipid lesions in C57BL/6JBom mice fed a cholesterol-enriched diet.

Role of beta2-glycoprotein I, LDL-, and antioxidant levels in hypercholesterolemic elderly subjects

The levels of electronegative low-density lipoprotein (LDL-), LDL cholesterol oxidability, and plasma levels of molecular antioxidants and of beta(2)-glycoprotein I (beta(2) GPI) were studied in a group of 10 hypercholesterolemic (HC) and 10 normocholesterolemic (NC) elderly subjects. HC subjects showed significantly higher levels of cholesterol, LDL cholesterol, LDL-, and beta(2)GPI than NC, whereas high-density lipoprotein cholesterol and alpha-tocopherol levels were lower in HC as compared with NC subjects. Correlations among LDL- levels, LDL oxidation lag time, beta(2)GPI, and antioxidant plasma levels were studied in 100 HC elderly subjects. Lag time for in vitro LDL oxidation positively correlated with ubiquinol-10 levels (p = 0.008), but not with other antioxidants studied or beta(2)GPI. LDL- and alpha-tocopherol levels showed an inverse and significant correlation (p = 0.018). beta(2)GPI and LDL cholesterol levels were correlated (p = 0.001), whereas no significance was found between LDL- and beta(2)GPI levels (p = 0.057). The physiological significance of alpha-tocopherol and ubiquinol-10 levels on LDL- levels, and the presence of high levels of beta(2)-GPI, are discussed in terms of protective mechanisms operating during the overall atherosclerosis process.

Cardiovascular complications and increased levels of circulating modified low density lipoprotein in HIV patients and patients with lipodystrophy

The introduction of highly active antiretroviral therapy (HAART) for patients infected with HIV has significantly prolonged the life expectancy and to some extent has restored a functional immune response. However, the premature introduction of HAART has led to a significant and alarming increase in cardiovascular complications, including myocardial infarction and the appearance of abnormal distribution of body fat seen as lipodystrophy. One key element in the development of ischemic coronary artery disease is the presence of circulating and tissue-fixed modified low density lipoprotein (mLDL) that contributes to the initiation and progression of arterial lesions and to the formation of foam cells. Even though not completely elucidated, the most likely mechanism involves mLDL in the inflammatory response and the induction of a specific immune response against mLDL. Circulating antibodies against mLDL can serve as an indirect marker of the presence of circulating and vessel-fixed mLDL. In the present study, we measured antibodies to mLDL and correlated them with immune status (i.e., number of CD4+ T cells) in 59 HIV patients and with the clinical manifestation of lipodystrophy in 10 patients. We observed a significant reduction in anti-mLDL antibody levels related both to lipodystrophy and to an immunocompromised state in HIV patients. We speculate that these antibodies may explain in part the rapid development of ischemic coronary artery disease in some patients.

Nicotine strongly activates dendritic cell-mediated adaptive immunity: potential role for progression of atherosclerotic lesions

BACKGROUND

Antigen-presenting cells (APCs) such as monocytes and dendritic cells (DCs) stimulate T-cell proliferation and activation in the course of adaptive immunity. This cellular interaction plays a role in the growth of atherosclerotic plaques. Nicotine has been shown to increase the growth of atherosclerotic lesions. Therefore, we investigated whether nicotine can stimulate APCs and their T cell-stimulatory capacity using human monocyte-derived DCs and murine bone marrow-derived DCs as APCs.

METHODS AND RESULTS

Nicotine dose-dependently (10(-8) to 10(-4) mol/L) induced DC expression of costimulatory molecules (ie, CD86, CD40), MHC class II, and adhesion molecules (ie, LFA-1, CD54). Moreover, nicotine induced a 7.0-fold increase in secretion of the proinflammatory T(H)1 cytokine interleukin-12 by human DCs. These effects were abrogated by the nicotinic receptor antagonist alpha-bungarotoxin and mecamylamine, respectively. The effects of nicotine were mediated in part by the phosphorylation of the PI3 kinase downstream target Akt and the mitogen-activated kinases ERK and p38 MAPK. Nicotine-stimulated APCs had a greater capacity to stimulate T-cell proliferation and cytokine secretion, as documented by mixed lymphocyte reactions and ovalbumin-specific assays with ovalbumin-transgenic DO10.11 mice. In a murine model of atherosclerosis, nicotine significantly enhanced the recruitment of DCs to atherosclerotic lesions in vivo.

CONCLUSIONS

Nicotine activates DCs and augments their capacity to stimulate T-cell proliferation and cytokine secretion. These effects of nicotine may contribute to its influence on the progression of atherosclerotic lesions.

Identification of negative regulator of interleukin-3 (NIL-3) in bone marrow

We have reported that an inhibitor of interleukin-3 (NIL-3) is produced from murine bone marrow cells in response to excess stimulation of interleukin-3. In this report, we attempted the purification of the NIL-3 activity from bone marrow culture supernatant in the presence of interleukin-3. The purified NIL-3 activity was a protein with relative molecular weight of 54.5 kDa (SDS-PAGE), which inhibited the growth of IL-3 dependent DA-1 cell growth in a dose dependent manner. The N-terminal amino acid sequence of purified NIL-3 activity was determined to be homologous to beta-2 glycoprotein I (apolipoprotein H: APO-H). The gene expression of APO-H was detected by nested-PCR in STIL-3 C5-CM stimulated total bone marrow cells and STIL-3 C5-CM stimulated bone marrow fraction 2 (Fr. 2) which has been reported as a hematopoietic stem cell rich fraction. These observations indicate the possibility that the APO-H is the NIL-3 which was produced from bone marrow cells in response to excess IL-3 stimuli.

Statins prevent endothelial cell activation induced by antiphospholipid (anti-beta2-glycoprotein I) antibodies: effect on the proadhesive and proinflammatory phenotype

OBJECTIVE

To investigate the ability of statins, the inhibitors of the hydroxymethylglutaryl-coenzyme A reductase enzyme, to affect endothelial cell activation induced by anti-beta2-glycoprotein I (anti-beta2GPI) antibodies in vitro.

METHODS

Human umbilical vein endothelial cell (HUVEC) activation was evaluated as U937 monocyte adhesion, E-selectin, and intercellular adhesion molecule I (ICAM-1) expression by cell enzyme-linked immunosorbent assay and as interleukin-6 (IL-6) messenger RNA (mRNA) expression by RNA protection assay. E-selectin-specific nuclear factor kappaB (NF-kappaB) DNA-binding activity was evaluated by the gel-shift assay. HUVECs were activated by polyclonal affinity-purified IgG, human monoclonal IgM anti-beta2GPI antibodies, human recombinant IL-1beta, tumor necrosis factor alpha, or lipopolysaccharide (LPS).

RESULTS

Fluvastatin reduced, in a concentration-dependent manner (1-10 microM), the adhesion of U937 to HUVECs and the expression of E-selectin and ICAM-1 induced by anti-beta2GPI antibodies as well as by cytokines or LPS. Another lipophilic statin, simvastatin, displayed similar effects but to a lesser extent than fluvastatin. The inhibition of E-selectin expression exerted by fluvastatin was related to the impairment of NF-kappaB binding to DNA. Moreover, the drug attenuated the expression of IL-6 mRNA in HUVEC exposed to anti-beta2GPI antibodies or cytokines. Incubation of HUVECs with mevalonate (100 microM), concomitantly with fluvastatin, greatly prevented the inhibitory effect of statin.

CONCLUSION

Endothelial activation mediated by anti-beta2GPI antibody can be inhibited by statins. Because of the suggested role of endothelial cell activation in the pathogenesis of antiphospholipid syndrome (APS), our data provide, for the first time, a rationale for using statins as an additional therapeutic tool in APS.

Antibodies to human heat-shock protein 60 are associated with the presence and severity of coronary artery disease: evidence for an autoimmune component of atherogenesis

BACKGROUND

Antibodies to mycobacterial heat-shock protein (HSP) 65 have been reported to be associated with carotid artery thickening. We examined whether antibodies to human HSP60 are associated with the risk of coronary artery disease (CAD).

METHODS AND RESULTS

Blood samples from 391 patients (62% men, mean age 57 years) being evaluated for CAD by coronary angiography were tested for IgG antibodies to human HSP60 by ELISA. We found that 75% of the study subjects had anti-HSP60 antibodies. The prevalence of CAD was increased in seropositive compared with seronegative patients (68% versus 49%, P:=0.0009). Mean titers of HSP60 antibodies were higher in CAD patients than in non-CAD patients (P:=0.008). No association between HSP60 antibodies and infection or inflammation was found. Importantly, HSP60 antibodies were related to disease severity. The prevalence of HSP60 antibodies was 76%, 80%, and 85% in patients with 1-, 2-, and 3-vessel disease, compared with 64% in patients without CAD (P: for trend=0.003). A similar association between increasing antibody titers and number of diseased vessels was also found (P:=0.03). Significant associations between antibodies to HSP60 and CAD severity persisted after adjustment for traditional risk factors by age, race, sex, smoking, diabetes, hypercholesterolemia, hypertension, and C-reactive protein levels. Adjusted OR for number of vessels diseased was 1.86 (95% CI 1.13 to 3.04).

CONCLUSIONS

This is the first study demonstrating a significant association between human HSP60 antibodies and both the presence and severity of CAD.