Lack of association between infectious burden and carotid atherosclerosis in Japanese patients

Causal association between helicobacter pylori and atherosclerosis: a two-sample Mendelian randomization

BACKGROUND

Helicobacter pylori (H. pylori), according to a number of recent observational studies, is connected to atherosclerosis (AS). However, the link between H. pylori and AS is debatable.

METHODS

In order to calculate the causal relationship between H. pylori and AS, we employed a two-sample Mendelian randomization (MR) analysis. The data for H. pylori were obtained from the IEU GWAS database ( https://gwas.mrcieu.ac.uk/datasets/ ) and the data for AS were obtained from the Finngen GWAS database ( https://r5.finngen.fi/ ). We selected single nucleotide polymorphisms with a threshold of 5 × 10-6 from earlier genome-wide association studies. MR was performed mainly using the inverse variance weighted (IVW) method. To ensure the reliability of the findings, We performed a leave-one-out sensitivity analysis to test for sensitivity. F-value was used to test weak instrument.

RESULTS

A positive causal relationship between H. pylori OMP antibody levels and peripheral atherosclerosis was shown by our two-sample MR analysis (odds ratio (OR) = 1.33, 95% confidence interval (CI) = 1.14-1.54, P = 0.26E-03) using IVW. Additionally, there was a causative link between coronary atherosclerosis and H. pylori VacA antibody levels (IVW OR = 1.06, 95% CI = 1.01-1.10, P = 0.016). All the F-values were above 10.

CONCLUSIONS

This MR study discovered a causal link between H. pylori and AS. Different antibodies have different effects, so future researches are needed to figure out the exact mechanisms behind this link.

Prevalence of Microorganisms in Atherosclerotic Plaques of Coronary Arteries: A Systematic Review and Meta-Analysis

Background

In this systematic review and meta-analysis, the existence of pathogens in atherosclerotic plaques of coronary arteries was investigated in coronary arteries diseases (CAD) patients.

Methods

This study was designed and implemented up to 31 August 2020. The findings present according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analysis) checklist. Two independent reviewers (I.RJ and S.H) performed a comprehensive search on four different English databases including PubMed, ISI, Scopus, and Embase. In order to assess the quality of the articles, a checklist prepared by The Joanna Briggs Institute (JBI) was used.

Results

Finally, 44 studies were selected. The prevalence of different microorganisms in coronary arteries were as follows: Aggregatibacter actinomycetemcomitans (46.2%), Campylobacter rectus (43.0%), Chlamydia pneumonia (42.8%), Cytomegalovirus (29.1%), Helicobacter pylori (18.9%), Herpes simplex virus type 1 (5.9%), Porphyromonas gingivalis (42.6%), Prevotella intermedia (47.6%), Tannerella forsythia (43.7%), and Treponema denticola (32.9%).

Conclusion

Based on the result of this meta-analysis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans are the most common microorganisms in atherosclerotic plaques of coronary arteries and may have an important role in the development of atherosclerosis.

Infection and atherosclerosis: TLR-dependent pathways

Atherosclerotic vascular disease (ASVD) is a chronic process, with a progressive course over many years, but it can cause acute clinical events, including acute coronary syndromes (ACS), myocardial infarction (MI) and stroke. In addition to a series of typical risk factors for atherosclerosis, like hyperlipidemia, hypertension, smoking and obesity, emerging evidence suggests that atherosclerosis is a chronic inflammatory disease, suggesting that chronic infection plays an important role in the development of atherosclerosis. Toll-like receptors (TLRs) are the most characteristic members of pattern recognition receptors (PRRs), which play an important role in innate immune mechanism. TLRs play different roles in different stages of infection of atherosclerosis-related pathogens such as Chlamydia pneumoniae (C. pneumoniae), periodontal pathogens including Porphyromonas gingivalis (P. gingivalis), Helicobacter pylori (H. pylori) and human immunodeficiency virus (HIV). Overall, activation of TLR2 and 4 seems to have a profound impact on infection-related atherosclerosis. This article reviews the role of TLRs in the process of atherosclerosis after C. pneumoniae and other infections and the current status of treatment, with a view to providing a new direction and potential therapeutic targets for the study of ASVD.

Cytomegalovirus Infection in Cardiovascular Diseases

Atherosclerosis underlies the development of many cardiovascular diseases that continue to hold a leading place among the causes of death in developed countries. The role of activated immune cells in atherosclerosis progression has been convincingly demonstrated, but the mechanism of their action remains poorly investigated. Since atherosclerosis is associated with chronic inflammatory response, involvement of viral and bacterial infections in atherogenesis has been examined. A special place among the infectious agents is held by human herpesviruses as the most common persistent viruses in human population coupled to chronic inflammation during atherosclerosis. We found that activation of cytomegalovirus (CMV, human herpesvirus 5) infection is associated with the emergence of acute coronary syndrome, which is in a good agreement with the data on productive CMV infection published elsewhere. In this review, we discuss the data obtained by us and other researchers regarding the role of cytomegalovirus infection and related potential mechanisms resulting in the expansion of atherosclerotic plaques during ischemic heart disease and stroke, including virus transfer to immune and endothelial cells via extracellular vesicles. In particular, the data presented in the review demonstrate that virus spreading in the vascular wall triggers immune system activation in atherosclerotic plaques and causes endothelial dysfunction. Moreover, productive CMV infection in patients with acute myocardial infarction correlates with the extent of endothelial dysfunction. The mechanisms described by us and other researchers may explain the role of CMV infection in atherosclerosis and development of ischemic heart disease.

Anti-cytomegalovirus IgG antibody titer is positively associated with advanced T cell differentiation and coronary artery disease in end-stage renal disease

Background

Accumulating evidence indicates that persistent human cytomegalovirus (HCMV) infection is associated with several health-related adverse outcomes including atherosclerosis and premature mortality in individuals with normal renal function. Patients with end-stage renal disease (ESRD) exhibit impaired immune function and thus may face higher risk of HCMV-related adverse outcomes. Whether the level of anti-HCMV immune response may be associated with the prognosis of hemodialysis patients is unknown.

Results

Among 412 of the immunity in ESRD study (iESRD study) participants, 408 were HCMV seropositive and were analyzed. Compared to 57 healthy individuals, ESRD patients had higher levels of anti-HCMV IgG. In a multivariate-adjusted logistic regression model, the log level of anti-HCMV IgG was independently associated with prevalent coronary artery disease (OR = 1.93, 95% CI = 1.2~ 3.2, p = 0.01) after adjusting for age, sex, hemoglobin, diabetes, calcium phosphate product and high sensitivity C-reactive protein. Levels of anti-HCMV IgG also positively correlated with both the percentage and absolute number of terminally differentiated CD8+ and CD4+ CD45RA+ CCR7- T_EMRA cells, indicating that immunosenescence may participate in the development of coronary artery disease.

Conclusion

This is the first study showing that the magnitude of anti-HCMV humoral immune response positively correlates with T cell immunosenescence and coronary artery disease in ESRD patients. The impact of persistent HCMV infection should be further investigated in this special patient population.

Electronic supplementary material

The online version of this article (10.1186/s12979-018-0120-0) contains supplementary material, which is available to authorized users.

Evidence for a vascular microbiome and its role in vessel health and disease

PURPOSE OF REVIEW

We have summarized available evidence for and against the presence of a vascular microbiome. Studies that have attempted to detect bacteria and viruses in blood vessels in both health and disease are critiqued in an attempt to explain contrary results that may be due to variations in methodology.

RECENT FINDINGS

Many studies have demonstrated the presence of both bacteria and viruses within diseased blood vessels. Evidence is most compelling in atherosclerosis; however, recent reports have raised questions about the potential role of microbes in nonatherosclerotic aortic aneurysms and vasculitis. Preliminary evidence also suggests that apparently normal vessels may harbor microbes. With the exception of certain viral infections (e.g. hepatitis C virus, HIV, Epstein-Barr virus, and cytomegalovirus) and infectious endocarditis, systemic vasculitides have not been convincingly associated with infectious agents. However, emerging data suggest that different communities of microbes may be present in noninflammatory and inflammatory large-vessel diseases. Whether variations in vascular microbial communities are the cause or a secondary result (epiphenomena) of vessel injury remains to be determined.

SUMMARY

Blood vessels may not be sterile. Future studies of microbes in vessel health and disease may provide important insights into disease pathogenesis and suggest new therapies for diseases now considered to be idiopathic and refractory.

Infection and Stroke: an Update on Recent Progress

The role of infection in cerebrovascular disease is complex and remains incompletely understood. Over the last 5 years, investigators have made notable inroads in untangling this thorny topic. In this review, we examine these recent developments, concentrating on four aspects of the relationship between infection and stroke. We first discuss specific infectious agents as direct causes of stroke, focusing on recent work implicating herpesviruses and HIV in cerebral vasculopathy. We then discuss systemic infection of any type as a stroke trigger, focusing on the relationship of infection to timing of acute stroke, both in children and adults, as well as the role of vaccination in stroke prevention. We examine the evidence for chronic infection or "infectious burden" as a stroke risk factor. Finally, we discuss recent work on infection as a risk factor for increased morbidity after stroke, possible mechanisms mediating this effect, and the evidence for prophylactic antibiotics.

Infection and Atherosclerosis Development

Atherosclerosis is a chronic disease hallmarked by chronic inflammation, endothelial dysfunction and lipid accumulation in the vasculature. Although lipid modification and deposition are thought to be a major source of the continuous inflammatory stimulus, a large body of evidence suggests that infectious agents may contribute to atherosclerotic processes. This could occur by either direct effects through infection of vascular cells and/or through indirect effects by induction of cytokine and acute phase reactant proteins by infection at other sites. Multiple bacterial and viral pathogens have been associated with atherosclerosis by seroepidemiological studies, identification of the infectious agent in human atherosclerotic tissue, and experimental studies demonstrating an acceleration of atherosclerosis following infection in animal models of atherosclerosis. This review will focus on those infectious agents for which biological plausibility has been demonstrated in animal models and on the challenges of proving a role of infection in human atherosclerotic disease.

Does non-central nervous system tuberculosis increase the risk of ischemic stroke? A population-based propensity score-matched follow-up study

Background

Previous studies on the association between tuberculosis and the risk of developing ischemic stroke have generated inconsistent results. We therefore performed a population-based, propensity score-matched longitudinal follow-up study to investigate whether contracting non-central nervous system (CNS) tuberculosis leads to an increased risk of ischemic stroke.

Methods

We used a logistic regression model that includes age, sex, pre-existing comorbidities and socioeconomic status as covariates to compute the propensity score. A total of 5804 persons with at least three ambulatory visits in 2001 with the principal diagnosis of non-CNS tuberculosis were enrolled in the tuberculosis group. The non-tuberculosis group consisted of 5804, propensity score-matched subjects without tuberculosis. The three-year ischemic stroke-free survival rates for these 2 groups were estimated using the Kaplan-Meier method. The stratified Cox proportional hazards regression was used to estimate the effect of tuberculosis on the occurrence of ischemic stroke.

Results

During three-year follow-up, 176 subjects in the tuberculosis group (3.0%) and 207 in the non-tuberculosis group (3.6%) had ischemic stroke. The hazard ratio for developing ischemic stroke in the tuberculosis group was 0.92 compared to the non-tuberculosis group (95% confidence interval: 0.73–1.14, P = 0.4299).

Conclusions

Non-CNS tuberculosis does not increase the risk of subsequent ischemic stroke.

High prevalence of human cytomegalovirus in carotid atherosclerotic plaques obtained from Russian patients undergoing carotid endarterectomy

Background

Human cytomegalovirus (HCMV) infection is associated with cardiovascular disease (CVD) but the role of this virus in CVD progression remains unclear. We aimed to examine the HCMV serostatus in Russian patients (n = 90) who had undergone carotid endarterectomy (CEA) and controls (n = 82) as well as to determine the prevalence of HCMV immediate early (IE) and late (LA) antigens in carotid atherosclerotic plaques obtained from 89 patients. In addition, we sought to determine whether HCMV infection was associated with inflammatory activity in the plaque by quantifying infiltrating CD3 and CD68 positive cells and 5-LO immunoreactivity.

Methods

HCMV serology was assessed with ELISA and immunohistochemistry staining was performed to detect HCMV antigens, CD3, CD68 and 5-LO reactivity. The Fisher’s exact test was used to compare i) seroprevalence of HCMV IgG between patients and controls and ii) HCMV-positive or –negative to that of CD3, CD68 and 5-LO immunoreactive cells in plaque samples. The student-t test was performed to connote the significance level of mean optical density between patients and controls.

Results

The seroprevalence for HCMV IgG was high in both patients and controls (99% and 98%, respectively). Controls had significantly higher IgG titers for HCMV compared with patients (p = 0.0148). Strikingly, we found a high prevalence of HCMV antigens in atherosclerotic plaques; 57/89 (64%) and 47/87 (54%) were HCMV IE and LA positive, respectively. Most plaques had rather low HCMV reactivity with distinct areas of HCMV-positive cells mainly detected in shoulder regions of the plaques, but also in the area adjacent to the necrotic core and fibrous cap. In plaques, the cellular targets for HCMV infection appeared to be mainly macrophages/foam cells and smooth muscle cells. HCMV-positive plaques trended to be associated with increased numbers of CD68 positive macrophages and CD3 positive T cells, while 5-LO reactivity was high in both HCMV-positive and HCMV-negative plaques.

Conclusions

In Russian patients undergoing CEA, HCMV proteins are abundantly expressed in carotid plaques and may contribute to the inflammatory response in plaques via enhanced infiltration of CD68 and CD3 cells.

Association of cytomegalovirus and other pathogens with frailty and diabetes mellitus, but not with cardiovascular disease and mortality in psycho-geriatric patients; a prospective cohort study

Background

Studies about associations of infections with herpes viruses and other pathogens, such as Chlamydia pneumoniae (CP) and Helicobacter pylori (HP) with cardiovascular disease (CVD), diabetes mellitus (DM), frailty and/or mortality are conflicting. Since high levels of antibodies against these pathogens occur in the elderly, the role of these pathogens in morbidity and mortality of vulnerable elderly was explored.

Results

Blood samples of 295 community dwelling psycho-geriatric patients were tested for IgG antibodies to herpes simplex virus type 1 and 2, varicella zoster virus, Epstein Barr virus (EBV), cytomegalovirus (CMV), human herpes virus type 6 (HHV6), CP and HP. Frailty was defined with an easy-to-use previously described frailty risk score. Relative risks (RR) with 95% confidence intervals were calculated to evaluate associations between CVD, DM, frailty and pathogens. Pathogens as a predictor for subsequent mortality were tested using Kaplan Meier analyses and Cox proportional hazard models. The mean age was 78 (SD: 6.7) years, 20% died, 44% were defined as frail, 20% had DM and 49% had CVD. Presence of CMV antibody titers was associated with frailty, as shown by using both qualitative and quantitative tests, RR ratio 1.4 (95% CI: 1.003-2.16) and RR ratio 1.5 (95% CI: 1.06-2.30), respectively. High IgG antibody titers of HHV6 and EBV were associated with DM, RR ratio 3.3 (95% CI: 1.57-6.49). None of the single or combined pathogens were significantly associated with mortality and/or CVD.

Conclusions

Prior CMV infection is associated with frailty, which could be in line with the concept that CMV might have an important role in immunosenescence, while high IgG titers of HHV6 and EBV are associated with DM. No association between a high pathogen burden and morbidity and/or mortality could be demonstrated.

Cytomegalovirus localization in atherosclerotic plaques is associated with acute coronary syndromes: report of 105 patients

It has been shown that cytomegalovirus (CMV) is present in coronary atherosclerotic plaques, but the clinical relevance of this presence remains to be elucidated. In this study we sought to examine CMV infection in atherosclerosis patients defined by different methods and to identify the clinical significance of CMV replication in the atherosclerotic plaques. The study included 105 consecutive patients who were admitted to our department and underwent coronary artery bypass grafting (CABG) surgical interventions. Coronary atherosclerotic specimens as well as 53 specimens from the mamillary artery of these same patients were analyzed. Enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) methods were used for evaluations. The CMV PCR test result was positive for 28 (26.7%) of patients with coronary artery atherosclerosis. After adjusting for other risk factors, coronary artery disease patients with a history of acute coronary syndrome were more likely to be positive for CMV PCR test (P=0.027; odds ratio: 4.2; 95% CI: 1.18-15.0). They were also more likely to have a positive family history for cardiovascular diseases (CVD). This study confirms previous evidence about the replication of CMV virus in the atherosclerotic plaques of coronary arteries and brings clinical significance to this observation by showing a higher prevalence of acute coronary syndromes in those patients with CMV-infected plaques. Our study also suggests a familial vulnerability to CMV replication in the coronary artery walls.

Cytomegalovirus-induced effector T cells cause endothelial cell damage

Human cytomegalovirus (CMV) infection has been linked to inflammatory diseases that involve vascular endothelial cell damage, but definitive proof for a direct cytopathic effect of CMV in these diseases is lacking. CMV infection is associated with a strong increase in both CD4(+) and CD8(+) T cells with constitutive effector functions that can perpetuate systemic inflammation. We investigated whether CMV-induced immune responses could lead to endothelial damage in humans. We found that terminally differentiated effector CD4(+) and CD8(+) T cells, formed during primary CMV infection and maintained throughout latency, express high levels of CX3CR1 and CXCR3. The ligands of these receptors, fractalkine and IP-10, respectively, are expressed by activated endothelial cells. Peripheral blood mononuclear cells (PBMC) stimulated with CMV antigen produced soluble factors that stimulated endothelial cells to produce both chemokines. Finally, effector cells migrated in a fractalkine- and IP-10-dependent fashion to activated endothelial cells and induced apoptosis in endothelial cells that were stimulated by supernatant from CMV-activated PBMC. Our findings offer an explanation for the accumulation of highly differentiated T cells near to the endothelium in CMV-infected individuals that may result in endothelial damage.

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.

Individual pathogens, pathogen burden and markers of subclinical atherosclerosis: the Multi-Ethnic Study of Atherosclerosis

METHODS

We examined the cross-sectional relationships of subclinical atherosclerosis - expressed by carotid intimal-medial thickness and coronary calcification - with antibodies to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, herpes simplex virus, hepatitis A virus, and pathogen burden (number of positive pathogens). A random sample of 1056 individuals chosen from 5030 Multi-Ethnic Study of Atherosclerosis cohort participants were included.

RESULTS

After multiple adjustment, no associations were found between atherosclerosis measures and either individual pathogens or pathogen burden. Interactions with inflammatory and endothelial function markers, demographic factors, BMI, high-density lipoprotein, diabetes, and smoking were also explored. The only interaction that was large, qualitative, statistically significant (P < 0.05) and in the expected direction was that between hepatitis A virus and soluble intercellular adhesion molecule-1 with regard to Agatston calcium score: the difference between hepatitis A virus-positive and hepatitis A virus-negative participants was -186 units in participants with soluble intercellular adhesion molecule-1 below the median, and +162 units in those with soluble intercellular adhesion molecule-1 equal or above the median. However, given the number of interactions that were explored, these results must be interpreted cautiously.

CONCLUSION

Findings from the present analyses do not provide support for an infectious etiology for subclinical atherosclerosis. However, the study's limitations, which include its cross-sectional design and insufficient statistical power, suggest that inferences from its findings should be made cautiously.

Cardiovascular disease and periodontitis: an update on the associations and risk

BACKGROUND

Associations between periodontitis and cardiovascular diseases have been recognized.

MATERIAL AND METHODS

New literature since the last European Workshop on Periodontology has been reviewed.

RESULTS

The lack of reliable epidemiological data on disease prevalence makes an assessment of the associations and risks between periodontitis and cardiovascular diseases difficult. Two recent meta-analysis reports have identified associations between periodontitis and cardiovascular diseases (odds ratios: 1.1-2.2). Different surrogate markers for both disease entities, including serum biomarkers, have been investigated. Brachial artery flow-mediated dilatation, and carotid intima media thickness have in some studies been linked to periodontitis. Studies are needed to confirm early results of improvements of such surrogate markers following periodontal therapy. While intensive periodontal therapy may enhance inflammatory responses and impair vascular functions, studies are needed to assess the outcome of periodontal therapies in subjects with confirmed cardiovascular conditions. Tooth eradication may also reduce the systemic inflammatory burden of individuals with severe periodontitis. The role of confounders remain unclear.

CONCLUSIONS

Periodontitis may contribute to cardiovascular disease and stroke in susceptible subjects. Properly powered longitudinal case-control and intervention trials are needed to identify how periodontitis and periodontal interventions may have an impact on cardiovascular diseases.

Extragastric manifestations of Helicobacter pylori infection: other Helicobacters

The finding that Helicobacter pylori is the main cause of gastritis and peptic ulcer disease has opened a new era in the gastrointestinal world. Today there is evidence that H. pylori may also play a role in different nongastric diseases, opening the new "extragastric manifestations of H. pylori infection" field. Concerning this, several studies have been published in the last year. The most convincing data arise from those investigating idiopathic thrombocytopenic purpura and sideropenic anemia, while there is also an increasing evidence for a possible association with atherosclerotic disease. Furthermore, the discovery of a number of other novel Helicobacter species has stimulated the research in different extragastric diseases, in which an infectious hypothesis is plausible. In particular, several species have been studied for a potential role in different liver and intestinal diseases with interesting findings.

Detection of Cytomegalovirus in Atherosclerotic Plaques and Nonatherosclerotic Arteries

Several studies have reported an association between infectious agents and atherosclerosis. Cytomegalovirus (CMV) is the most commonly implicated viral pathogen. However, the role of CMV in atherosclerosis remains obscure. The present study evaluated the presence of CMV DNA in atherosclerotic plaques and normal vessel walls. A total of 40 arterial specimens from coronary plaques and 27 samples from normal vessels were obtained from 26 patients who underwent aortocoronary bypass surgery. The specimens were analyzed by polymerase chain reaction for the presence of the CMV immediate early genomic region. CMV DNA was detected in 9 out of 26 patients (34.6%). Viral DNA was detected in both nonatherosclerotic tissues and atherosclerotic plaques. No statistically significant differences were observed between normal and diseased vessels. Our findings, in accordance with previous studies, do not support a direct causative role of CMV in the development of atherosclerotic plaques.

Helicobacter pylori-induced inhibition of vascular endothelial cell functions: a role for VacA-dependent nitric oxide reduction

Epidemiological and clinical studies provide compelling support for a causal relationship between Helicobacter pylori infection and endothelial dysfunction, leading to vascular diseases. However, clear biochemical evidence for this association is limited. In the present study, we have conducted a comprehensive investigation of endothelial injury in bovine aortic endothelial cells (BAECs) induced by H. pylori-conditioned medium (HPCM) prepared from H. pylori 60190 [vacuolating cytotoxin A (Vac(+))]. BAECs were treated with either unconditioned media, HPCM (0-25% vol/vol), or Escherichia coli-conditioned media for 24 h, and cell functions were monitored. Vac(+) HPCM significantly decreased BAEC proliferation, tube formation, and migration (by up to 44%, 65%, and 28%, respectively). Posttreatment, we also observed sporadic zonnula occludens-1 immunolocalization along the cell-cell border, and increased BAEC permeability to FD40 Dextran, indicating barrier reduction. These effects were blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (VacA inhibitor) and were not observed with conditioned media prepared from either VacA-deleted H. pylori or E. coli. The cellular mechanism mediating these events was also considered. Vac(+) HPCM (but not Vac(-)) reduced nitric oxide (NO) by >50%, whereas S-nitroso-N-acetylpenicillamine, an NO donor, recovered all Vac(+) HPCM-dependent effects on cell functions. We further demonstrated that laminar shear stress, an endothelial NO synthase/NO stimulus in vivo, could also recover the Vac(+) HPCM-induced decreases in BAEC functions. This study shows, for the first time, a significant proatherogenic effect of H. pylori-secreted factors on a range of vascular endothelial dysfunction markers. Specifically, the VacA-dependent reduction in endothelial NO is indicated in these events. The atheroprotective impact of laminar shear stress in this context is also evident.