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

The Pathophysiological Role of Heat Shock Response in Autoimmunity: A Literature Review

Within the last two decades, there has been increasing evidence that heat-shock proteins can have a differential influence on the immune system. They can either provoke or ameliorate immune responses. This review focuses on outlining the stimulatory as well as the inhibitory effects of heat-shock proteins 27, 40, 70, 65, 60, and 90 in experimental and clinical autoimmune settings.

Chlamydia pneumoniae Infection Exacerbates Atherosclerosis in ApoB100only/LDLR-/- Mouse Strain

Aims

Hyperlipidaemia model animals have been used to elucidate the role of Chlamydia pneumoniae (Cpn) infection in atherosclerosis. The aims of this study were to investigate the proatherogenic effect of multiple Cpn infections in ApoB100only/LDLR^−/− mice which based on lipid profile can be regarded as the most suitable mouse model of human hypercholesterolemia and to compare the lesion development to that in a major atherosclerosis model ApoE^−/− mice.

Methods and Results

Aorta samples of ApoB100only/LDLR^−/− mice infected three times with Cpn were subjected to morphometric analyses. Morphometric evaluation disclosed that Cpn infections exacerbated atherosclerosis development in the aortic root and descending aorta of the mice fed with normal diet. Viable Cpn was detected in the ascending aorta by RT-PCR. Chlamydial 16SrRNA expression showed the presence of viable Cpn in the aorta of infected animals. A similar rate of acceleration of atherosclerosis was observed when the infection protocol was applied in ApoB100only/LDLR^−/− and in ApoE^−/− mice.

Conclusion

Similar to ApoE^−/− mice, ApoB100only/LDLR^−/− mice with more human-relevant serum lipoprotein composition develop increased atherosclerosis after Cpn infections; thus this mouse strain can be used as a model of infection-related atherosclerosis enhancement and can provide further evidence for the proatherogenic influence of Cpn in mice.

Inhibitors of Apoptosis Protein Antagonists (Smac Mimetic Compounds) Control Polarization of Macrophages during Microbial Challenge and Sterile Inflammatory Responses

Apoptosis is a physiological cell death process essential for development, tissue homeostasis, and for immune defense of multicellular animals. Inhibitors of apoptosis proteins (IAPs) regulate apoptosis in response to various cellular assaults. Using both genetic and pharmacological approaches we demonstrate here that the IAPs not only support opportunistic survival of intracellular human pathogens like Chlamydia pneumoniae but also control plasticity of iNOS+ M1 macrophage during the course of infection and render them refractory for immune stimulation. Treatment of Th1 primed macrophages with birinapant (IAP-specific antagonist) inhibited NO generation and relevant proteins involved in innate immune signaling. Accordingly, birinapant promoted hypoxia, angiogenesis, and tumor-induced M2 polarization of iNOS+ M1 macrophages. Interestingly, birinapant-driven changes in immune signaling were accompanied with changes in the expression of various proteins involved in the metabolism, and thus revealing the new role of IAPs in immune metabolic reprogramming in committed macrophages. Taken together, our study reveals the significance of IAP targeting approaches (Smac mimetic compounds) for the management of infectious and inflammatory diseases relying on macrophage plasticity.

Dendritic Cell KLF2 Expression Regulates T Cell Activation and Proatherogenic Immune Responses

Dendritic cells (DCs) have been implicated as important regulators of innate and adaptive inflammation in many diseases, including atherosclerosis. However, the molecular mechanisms by which DCs mitigate or promote inflammatory pathogenesis are only partially understood. Previous studies have shown an important anti-inflammatory role for the transcription factor Krüppel-like factor 2 (KLF2) in regulating activation of various cell types that participate in atherosclerotic lesion development, including endothelial cells, macrophages, and T cells. We used a pan-DC, CD11c-specific cre-lox gene knockout mouse model to assess the role of KLF2 in DC activation, function, and control of inflammation in the context of hypercholesterolemia and atherosclerosis. We found that KLF2 deficiency enhanced surface expression of costimulatory molecules CD40 and CD86 in DCs and promoted increased T cell proliferation and apoptosis. Transplant of bone marrow from mice with KLF2-deficient DCs into Ldlr-/- mice aggravated atherosclerosis compared with control mice, most likely due to heightened vascular inflammation evidenced by increased DC presence within lesions, enhanced T cell activation and cytokine production, and increased cell death in atherosclerotic lesions. Taken together, these data indicate that KLF2 governs the degree of DC activation and hence the intensity of proatherogenic T cell responses.

Putative consequences of exposure to Helicobacter pylori infection in patients with coronary heart disease in terms of humoral immune response and inflammation

INTRODUCTION

Pathogens, including Helicobacter pylori (Hp), have been suggested to contribute to the development of coronary heart disease (CHD), although the evidence still remains insufficient. The study was focused on the exposure of CHD patients to Hp and resulting anti-Hp heat shock protein B HspB antibody production in relation to the level of serum lipopolysaccharide binding protein (LBP) as a marker of inflammation.

MATERIAL AND METHODS

One hundred seventy CHD patients and 58 non-CHD individuals participated in this study. Coronary angiography confirmed the atheromatic background of CHD. The panel of classical risk factors included: arterial hypertension, diabetes, total cholesterol, low-density lipoprotein (LDL)/high-density lipoprotein (HDL) cholesterol, triglycerides, obesity and nicotinism. The Hp status was estimated by (13)C urea breath test and serology. Immunoblot and ELISA were used for screening the sera samples for anti-Hp HspB immunoglobulins (Igs) and LBP.

RESULTS

Coronary heart disease patients were exposed to Hp more frequently than non-CHD individuals. This was associated with increased levels of specific anti-Hp IgG2 and IgA as well as total IgA. Hp infected CHD and non-CHD donors produced anti-Hp HspB IgG cross-reacting with human Hsp 60. In CHD patients the LBP level was significantly higher in comparison to non-CHD donors. This was related to the severity of the disease. Type I Hp strains stimulated higher LBP levels than less pathogenic type II isolates.

CONCLUSIONS

Lipopolysaccharide binding protein secreted in excess together with anti-Hp HspB, cross-reacting with human Hsp60, may increase the risk of vascular pathologies in Hp-exposed CHD patients.

Chlamydia pneumoniae acute liver infection affects hepatic cholesterol and triglyceride metabolism in mice

OBJECTIVE

Chlamydia pneumoniae has been linked to atherosclerosis, strictly associated with hyperlipidemia. The liver plays a central role in the regulation of lipid metabolism. Since in animal models C. pneumoniae can be found at hepatic level, this study aims to elucidate whether C. pneumoniae infection accelerates atherosclerosis by affecting lipid metabolism.

METHODS

Thirty Balb/c mice were challenged intra-peritoneally with C. pneumoniae elementary bodies and thirty with Chlamydia trachomatis, serovar D. Thirty mice were injected with sucrose-phosphate-glutamate buffer, as negative controls. Seven days after infection, liver samples were examined both for presence of chlamydia and expression of genes involved in inflammation and lipid metabolism.

RESULTS

C. pneumoniae was isolated from 26 liver homogenates, whereas C. trachomatis was never re-cultivated (P < 0.001). C. pneumoniae infected mice showed significantly increased serum cholesterol and triglycerides levels compared both with negative controls (P < 0.001 and P = 0.0197, respectively) and C. trachomatis infected mice (P < 0.001). Liver bile acids were significantly reduced in C. pneumoniae compared to controls and C. trachomatis infected mice. In C. pneumoniae infected livers, cholesterol 7α-hydroxylase (Cyp7a1) and low-density lipoprotein receptor (Ldlr) mRNA levels were reduced, while inducible degrader of the low-density lipoprotein receptor (Idol) expression was increased. Hypertriglyceridemia was associated to reduced expression of hepatic carnitine palmitoyltransferase-1a (Cpt1a) and medium chain acyl-Coenzyme A dehydrogenase (Acadm). Pro-inflammatory cytokines gene expression was increased compared to negative controls. Conversely, in C. trachomatis infected animals, normal serum lipid levels were associated with elevated pro-inflammatory cytokines gene expression, linked to only a mild disturbance of lipid regulatory genes.

CONCLUSION

Our results indicate that C. pneumoniae mouse liver infection induces dyslipidemic effects with significant modifications of genes involved in lipid metabolism.

Heat shock proteins and cardiovascular disease

Atherosclerosis is the leading global cause of mortality, morbidity, and disability. Heat shock proteins (HSPs) are a highly conserved family of proteins with diverse functions expressed by all cells exposed to environmental stress. Studies have reported that several HSPs may be potential risk markers of atherosclerosis and related cardiovascular diseases, or may be directly involved in the atherogenic process itself. HSPs are expressed by cells in atherosclerotic plaque and anti-HSP has been reported to be increased in patients with vascular disease. Autoimmune responses may be generated against antigens present within the atherosclerotic plaque, including HSP and may lead to a cycle of ongoing vascular injury. It has been suggested that by inducing a state of tolerance to these antigens, the atherogenic process may be limited and thus provide a potential therapeutic approach. It has been suggested that anti-HSPs are independent predictors of risk of vascular disease. In this review, we summarize the current understanding of HSP in cardiovascular disease and highlight their potential role as diagnostic agents and therapeutic targets.

Chlamydophila pneumoniae infection and cardiovascular disease

Atherosclerosis is a multifactorial vascular inflammatory process; however, the inciting cause for inflammation remains unclear. Two decades ago, Chlamydophila pneumoniae (formerly Chlamydia pneumoniae) infection was proposed as a putative etiologic agent. We performed a PubMed search using the keywords Chlamydia and atherosclerosis in a Boolean query to identify published studies on C. pneumoniae and its role in atherogenesis, and to understand research interest in this topic. We found 1,652 published articles on this topic between 1991 and 2011. We analyzed relevant published studies and found various serological, molecular, and animal modeling studies in the early period. Encouraged by positive results from these studies, more than a dozen antibiotic clinical-trials were subsequently conducted, which did not find clinical benefits of anti-Chlamydophila drug therapy. While many researchers believe that the organism is still important, negative clinical trials had a similar impact on overall research interest. With many novel mechanisms identified for atherogenesis, there is a need for newer paradigms in Chlamydophila-atherosclerosis research.

The role of the vascular dendritic cell network in atherosclerosis

A complex role has been described for dendritic cells (DCs) in the potentiation and control of vascular inflammation and atherosclerosis. Resident vascular DCs are found in the intima of atherosclerosis-prone vascular regions exposed to disturbed blood flow patterns. Several phenotypically and functionally distinct vascular DC subsets have been described. The functional heterogeneity of these cells and their contributions to vascular homeostasis, inflammation, and atherosclerosis are only recently beginning to emerge. Here, we review the available literature, characterizing the origin and function of known vascular DC subsets and their important role contributing to the balance of immune activation and immune tolerance governing vascular homeostasis under healthy conditions. We then discuss how homeostatic DC functions are disrupted during atherogenesis, leading to atherosclerosis. The effectiveness of DC-based "atherosclerosis vaccine" therapies in the treatment of atherosclerosis is also reviewed. We further provide suggestions for distinguishing DCs from macrophages and discuss important future directions for the field.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Pathogens and atherosclerosis: update on the potential contribution of multiple infectious organisms to the pathogenesis of atherosclerosis

It is currently unclear what causes the chronic inflammation within atherosclerotic plaques. One emerging paradigm suggests that infection with bacteria and/or viruses can contribute to the pathogenesis of atherosclerosis either via direct infection of vascular cells or via the indirect effects of cytokines or acute phase proteins induced by infection at non-vascular sites. This paradigm has been supported by multiple epidemiological studies that have established positive associations between the risk of cardiovascular disease morbidity and mortality and markers of infection. It has also been supported by experimental studies showing an acceleration of the development of atherosclerosis following infection of hyperlipidaemic animal models. There are now a large number of different infectious agents that have been linked with an increased risk of cardiovascular disease. These include: Chlamydia pneumoniae, Porphyromonas gingivalis, Helicobacter pylori , influenza A virus, hepatitis C virus, cytomegalovirus, and human immunodeficiency virus. However, there are significant differences in the strength of the data supporting their association with cardiovascular disease pathogenesis. In some cases, the infectious agents are found within the plaques and viable organisms can be isolated suggesting a direct effect. In other cases, the association is entirely based on biomarkers. In the following review, we evaluate the strength of the data for individual or groups of pathogens with regard to atherosclerosis pathogenesis and their potential contribution by direct or indirect mechanisms and discuss whether the established associations are supportive of the infectious disease paradigm. We also discuss the failure of antibiotic trials and the question of persistent infection.

Heat-shock proteins in cardiovascular disease

Heat-shock proteins (HSPs) belong to a group of highly conserved families of proteins expressed by all cells and organisms and their expression may be constitutive or inducible. They are generally considered as protective molecules against different types of stress and have numerous intracellular functions. Secretion or release of HSPs has also been described, and potential roles for extracellular HSPs reported. HSP expression is modulated by different stimuli involved in all steps of atherogenesis including oxidative stress, proteolytic aggression, or inflammation. Also, antibodies to HSPs may be used to monitor the response to different types of stress able to induce changes in HSP levels. In the present review, we will focus on the potential implication of HSPs in atherogenesis and discuss the limitations to the use of HSPs and anti-HSPs as biomarkers of atherothrombosis. HSPs could also be considered as potential therapeutic targets to reinforce vascular defenses and delay or avoid clinical complications associated with atherothrombosis.

Autoimmunity, infectious immunity, and atherosclerosis

INTRODUCTION

Vascular inflammation is common in certain systemic autoimmune diseases and contributes to the oxidation of low-density lipoprotein (oxLDL) and oxLDL/beta2-glycoprotein I (beta2GPI) complex formation. These complexes have been implicated as proatherogenic autoantigens that participate in the development of atherosclerotic disease.

DISCUSSION

We have demonstrated that the in vitro macrophage uptake of oxLDL/beta2GPI complexes increases in the presence of IgG anti-beta2GPI antibodies and that IgG immune complexes containing oxLDL/beta2GPI upregulate the expression of both scavenger and Fcgamma receptors to activate beta2GPI specific T cells. Some persistent infections may cause immune responses that promote atherogenesis. Cellular immunity (Th1) against Helicobacter pylori (H. pylori) derived heat shock protein 60 (Hp-HSP60) cross-reacts with endogenous HSP60 to cause cardiovascular disease likely by molecular mimicry.

CONCLUSION

Infectious cellular response may be proatherogenic,while the humoral response (antibody production) maybe protective. We review the recent progress in our understanding of autoimmunity and infectious immunity that promote atherosclerosis.

Regulation of cellular immunity prevents Helicobacter pylori-induced atherosclerosis

Helicobacter pylori (H. pylori) is a predominant pathogen that causes not only gastroduodenal diseases but also extra-alimentary tract diseases. In this study, we demonstrated that H. pylori infection promoted atherogenesis in heterozygous apoe(+/ --) ldlr(+/--) mice. The male mice were fed with high fat diet from the age of 6 weeks. At the age of 16 weeks, development of atherosclerotic lesions was observed in the H. pylori-infected mice, and it seemed to be associated with an elevation of Th1-immune response against H. pylori origin-heat shock protein 60 (Hp-HSP60) and an increment of transendothelial migration of T cells. Subcutaneous immunisation with Hp-HSP60 or H. pylori eradication with antibiotics significantly reduced the progression of atherosclerosis, accompanied by a decline of Th1 differentiation and reduction of their chemotaxis beyond the endothelium. Thus, oral infection with H. pylori accelerates atherosclerosis in mice and the active immunisation with Hp-HSP60 or the eradication of H. pylori with antibiotics can moderate/prevent cellular immunity, resulting in a reduction of atherosclerosis.

Chronic infections and atherosclerosis

The immune response against heat shock protein 60 (HSP60) derived from pathogens causing chronic infections is thought to be an important pro-atherogenic mechanism because high serum levels of antibodies against HSP60 have been associated with atherosclerotic diseases, such as coronary artery diseases, or cerebro-vascular events. Furthermore, the presence of HSP60-specific T lymphocytes in circulation may increase the risk of atherosclerosis. Our recent in vitro and in vivo studies have also shown an association of Helicobacter pylori-HSP60 (Hp-HSP60) specific Th1 immune responses elicited by H. pylori infection with the progression of atherosclerosis in a hyperlipidemic mouse model. These Th1 dominant immune responses may cross-react with endogenous HSP60 expressed on stressed cells of the vascular endothelium, likely due to molecular mimicry. However, the exact mechanisms by which endothelial cells display their HSP60 molecule or present HSP60 antigenic epitopes on the surface are still unclear.

The autoimmune origin of atherosclerosis

Atherosclerosis is a chronic inflammatory disease. Many studies and observations suggest that it could be caused by an immune reaction against autoantigens at the endothelial level, the most relevant of which are oxidized LDL and heat shock proteins (HSP) 60/65. Endothelial dysfunction plays a fundamental role. The first antigen is related to the increased leakage and oxidation of LDL; the second to cellular reaction to stress. Experimental and clinical observations confirm the pathogenetic role of these antigens. Both innate and adaptive immunity and impaired regulatory mechanisms of the autoimmune reaction are involved. Different triggering factors are examined: infectious agents, smoking, air pollution, diabetes and hypercholesterolemia. Analogies and differences between systemic atherosclerosis and transplant-related coronary atherosclerosis help to understand their respective nature. Immune mechanisms might be responsible for the passage from stable plaque to unstable and rupture-prone plaque. Finally, prospects of treatment and prevention are linked to the induction of tolerance to responsible antigens, activation of immune regulatory response and the use of immunomodulatory drugs.

Implications of antibodies to heat-shock proteins in ischemic heart disease

OBJECTIVE

Experimental studies illustrate that priming with infectious agents, like Chlamydia pneumoniae, is involved in plaque formation and progression based on molecular mimicry with host heat-shock proteins (HSP). We have here evaluated the hypothesis that C. pneumoniae contributes to atherosclerotic disease progression via anti-HSP antibodies.

METHODS

The blood circulation of 151 consecutive patients with ischemic heart disease was screened for antibodies against human and Chlamydia HSP60 and C. pneumoniae IgG. Antibody levels were associated with the angiographic extent of coronary atherosclerosis, with clinical symptoms of ischemic heart disease and with biochemical and functional endothelial dysfunction markers.

RESULTS

Positive serology to human (11%) or Chlamydia HSP60 (22%) was not associated with the presence and extent of atherosclerosis, neither was it related with endothelial dysfunction. Patients with acute myocardial infarction had significantly lower Chlamydia HSP60 antibody levels (median OD 0.12, range: 0.02-0.75) than patients with stable (median OD 0.22, range: 0.02-2.67) or unstable angina pectoris (median OD 0.24, range: 0-2.48) (p=0.032). Subjects with positive C. pneumoniae IgG serology (if measured at a titre of 1:128) showed reduced flow-mediated vasodilation (p=0.024), but vasodilation responses did not differ in single-, two- or three-vessel disease.

CONCLUSION

Overall, antibody responses to C. pneumoniae IgG, human or Chlamydia HSP60 are not associated with endothelial dysfunction and presence and severity of coronary artery disease, arguing against the suggestion that infection contributes to disease progression and supplying additional proof that C. pneumoniae is an unlikely major risk factor of coronary atherosclerosis.

Chronic infections and atherosclerosis

Immunoinflammatory processes due to chronic infection are thought to be one of the definitive atherogenetic processes. Especially, anti-heat shock protein antibodies have been related to the prevalence of disease such as coronary artery disease or cerebral infarction, etc., resulted from atherosclerosis. Furthermore, the presence of HSP60-specific T lymphocytes in circulation may increase the risk of atherosclerosis. We have recently demonstrated the evidences that Helicobacter pylori infection induced atherosclerosis in apoe+/- ldlr+/- mice and that Hp-anti-heat-shock protein specific Th1-dominant immune responses had a major involvement in the progression of atherosclerosis. These cellular immune responses caused autoimmunity against endogenous HSP60 (expressed on the stressed cells of vascular endothelium), due to the molecular mimicry. Therefore, an appropriate treatment with antibiotics or with anti-HSP60 antibodies, which regulates the Th1 induction, could sufficiently reduce the progression of atherosclerosis.

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.

Pathogen proteins eliciting antibodies do not share epitopes with host proteins: a bioinformatics approach

The best way to prevent diseases caused by pathogens is by the use of vaccines. The advent of genomics enables genome-wide searches of new vaccine candidates, called reverse vaccinology. The most common strategy to apply reverse vaccinology is by designing subunit recombinant vaccines, which usually generate an humoral immune response due to B-cell epitopes in proteins. A major problem for this strategy is the identification of protective immunogenic proteins from the surfome of the pathogen. Epitope mimicry may lead to auto-immune phenomena related to several human diseases. A sequence-based computational analysis has been carried out applying the BLASTP algorithm. Therefore, two huge databases have been created, one with the most complete and current linear B-cell epitopes, and the other one with the surface-protein sequences of the main human respiratory bacterial pathogens. We found that none of the 7353 linear B-cell epitopes analysed shares any sequence identity region with human proteins capable of generating antibodies, and that only 1% of the 2175 exposed proteins analysed contain a stretch of shared sequence with the human proteome. These findings suggest the existence of a mechanism to avoid autoimmunity. We also propose a strategy for corroborating or warning about the viability of a protein linear B-cell epitope as a putative vaccine candidate in a reverse vaccinology study; so, epitopes without any sequence identity with human proteins should be very good vaccine candidates, and the other way around.

Protective effect of human heat shock protein 60 suggested by its association with decreased seropositivity to pathogens

The presence of heat shock protein 60 (Hsp60) in human plasma has been linked with cardiovascular disease (CVD). In this study, the examination of the relationship between Hsp60 in plasma and seropositivity for three microbial agents, which are thought to be risk factors for CVD, surprisingly revealed a negative association between Hsp60 and seropositivity, suggesting a protective effect of this circulating stress protein.

Increased prostanoid dependency of arterial relaxation in Chlamydia pneumoniae-infected mice

Endothelial dysfunction plays an important role in the development of atherosclerosis. Previous studies have shown that inoculation with Chlamydia pneumoniae contributes to atherosclerotic development in rabbits and hypercholesterolaemic mice and causes endothelial dysfunction in apolipoprotein E-deficient mice. The effect of acute C. pneumoniae infection on endothelial function in normocholesterolaemic C57BL/6J mice was studied by measuring the force of contraction of the descending aorta after noradrenaline stimulation and in response to methacholine-induced relaxation. In addition, the effects of the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester (L-NAME) and the cyclooxygenase inhibitor diclofenac on relaxation were assessed. Pre-treatment of the aortas with L-NAME decreased the relaxation response in both the infected and uninfected groups and no significant difference was detected between these groups, whereas diclofenac significantly attenuated the relaxation response only in the infected animals. In conclusion, infection shifted the balance of endothelium-derived relaxing factors from nitric oxide towards vasorelaxing prostanoids in C57BL/6J mice.

Chemokines in Children With Heterozygous Familiar Hypercholesterolemia

OBJECTIVE

Increasing data support the involvement of chemokines in atherogenesis. However, although several studies have shown increased chemokine levels in adult patients, the literature is virtually devoid of data on chemokines in children with hypercholesterolemia.

METHODS AND RESULTS

We examined the gene expression of chemokines in peripheral blood mononuclear cells (PBMCs) from clinically healthy children with and without heterozygous familial hypercholesterolemia (FH). Our main findings were: (1) compared with healthy controls, PBMCs from FH children showed significantly higher mRNA levels of RANTES, but not of the other examined chemokines; (2) an opposite pattern was seen in adult FH subjects, with markedly enhanced expression of macrophage inflammatory peptide-1alpha, but not of RANTES; (3) this increased gene expression of RANTES in PBMCs from FH children seemed to reflect enhanced RANTES expression in monocytes but not in T cells; (4) FH children also had raised serum levels of neopterin, additionally suggesting monocyte/macrophage activation in these children; and (5) PBMCs from both FH children and controls showed enhanced release of interleukin 8 on RANTES stimulation in vitro.

CONCLUSIONS

Our findings support a role of inflammation also in the early stages of atherogenesis possibly involving monocyte-derived RANTES as an important mediator.

Effects of repeated Chlamydia pneumoniae inoculations on aortic lipid accumulation and inflammatory response in C57BL/6J mice

Chlamydia pneumoniae is a common respiratory tract pathogen, and persistent infections have been associated with atherosclerosis. We studied the effects of repeated chlamydial inoculations on the inflammatory response and on aortic lipid accumulation in C57BL/6J mice. Mice fed a diet supplemented with 0.2% cholesterol were infected three or six times with C. pneumoniae every fourth week. Sera and lungs were analyzed for inflammatory responses, lung tissues were tested for the presence of C. pneumoniae DNA and RNA, and intimal lipid accumulation in the aortic sinus was quantified. High levels of chlamydial heat shock protein 60 (Hsp60) immunoglobulin G2c subclass antibodies were detected in all of the infected mice, and a positive and statistically significant correlation was found between these antibodies and autoantibodies against mouse Hsp60. Both Hsp60 antibody levels correlated with the severity of lung tissue inflammation. The cholesterol supplement in the diet had no effect on serum cholesterol levels. Significantly larger intimal lipid lesions were seen in the mouse group infected six times (6,542 mum(2)) than in the control group (1,376 mum(2); P = 0.034). In conclusion, repeated inoculations increased aortic sinus lipid accumulation in normocholesterolemic mice. The correlation between the antibodies to mouse and chlamydial Hsp60 proteins and their association with lung inflammation further support the theory of the development of an autoimmune response against heat shock proteins after repeated chlamydial infections.

Proteomic approach to identify changes in protein expression modified by 17β-oestradiol in bovine vascular smooth muscle cells

The aim of the present study was to use proteomics to analyse modifications in the level of expression of different proteins in BVSMCs (bovine vascular smooth muscle cells) incubated in the absence and presence of 17β-oestradiol. By using two-dimensional electrophoresis with a pH range of 4–7, we identified several areas on the gels in which the level of expression of proteins were different between control BVSMCs and cells incubated for 24 h with 17β-oestradiol. Changes in several isoforms of α-enolase, HSP60 (heat-shock protein 60), vimentin and PDI (protein disulphide-isomerase) were observed in BVSMCs. The expression of α-enolase isoform 1 was enhanced after 17β-oestradiol treatment. The expression of HSP60 isoform 3, vimentin isoforms 2 and 3 and caldesmon was reduced by 17β-oestradiol. Finally, the expression of PDI isoforms was reduced by 17β-oestradiol. In summary, 17β-oestradiol modified the expression of isoforms of proteins associated with smooth muscle cell proliferation (α-enolase, vimentin and HSP-60), cell contraction (vimentin and caldesmon) and cell redox modulation (PDI). These findings confirm that 17β-oestradiol may modulate a wide range of signalling pathways in vascular smooth muscle cells.