Cytotoxin-associated gene-A-seropositive virulent strains of Helicobacter pylori and atherosclerotic diseases: a systematic review:

Preventive effect of Helicobacter pylori eradication on the coronary heart diseases depending on age and sex with a median follow-up of 51 months

BACKGROUND

The association between Helicobacter pylori (HP) infection and coronary heart disease (CHD) is controversial. This study aimed to investigate the effect of H. pylori eradication on CHD, especially in terms of age and sex.

MATERIALS AND METHODS

From May 2003 to March 2022, 4765 subjects with H. pylori infection and without CHD (median follow-up: 51 months) were prospectively enrolled. The participants were categorized into two groups: H. pylori eradication and H. pylori non-eradication. After propensity-score matching (PSM), the effect of H. pylori eradication on CHD was analyzed using Cox proportional hazards.

RESULTS

There were no significant differences in age, sex, alcohol consumption, smoking habits, history of diabetes, hypertension, and dyslipidemia, and aspirin intake between the eradication and non-eradication groups (3783 vs. 982) before and after PSM. Multivariate analysis after PSM showed that H. pylori eradication (HR: 0.489, CI: 0.314-0.761, p = .002), age (HR: 1.027, CI: 1.007-1.047, p = .007), hypertension (HR: 2.133, CI: 1.337-3.404, p = 001), dyslipidemia (HR: 1.758, CI: 1.086-2.848, p = .022), and aspirin intake (HR: 2.508, CI: 1.566-4.017, p < .001) were associated with CHD development. H. pylori eradication prevented CHD in males ≤65 years (HR: 0.133, CI: 0.039-0.455, p = .001), but not in those aged >65 years (p = .078) (p for interaction = .022). In contrast, females aged >65 years (HR: 0.260, CI: 0.110-0.615, p = .002) were protected by H. pylori eradication and not those ≤65 years (p = .485) (p for interaction = .003). This preventive effect increased more after PSM, particularly in males ≤65 years and females >65 years.

CONCLUSIONS

H. pylori eradication prevented CHD and this effect was different depending on age and sex.

Associations of genetic and infectious risk factors with coronary heart disease

Coronary heart disease (CHD) is one of the most pressing health problems of our time and a major cause of preventable death. CHD results from complex interactions between genetic and environmental factors. Using multiplex serological testing for persistent or frequently recurring infections and genome-wide analysis in a prospective population study, we delineate the respective and combined influences of genetic variation, infections, and low-grade inflammation on the risk of incident CHD. Study participants are enrolled in the CoLaus|PsyCoLaus study, a longitudinal, population-based cohort with baseline assessments from 2003 through 2008 and follow-up visits every 5 years. We analyzed a subgroup of 3459 individuals with available genome-wide genotyping data and immunoglobulin G levels for 22 persistent or frequently recurring pathogens. All reported CHD events were evaluated by a panel of specialists. We identified independent associations with incident CHD using univariable and multivariable stepwise Cox proportional hazards regression analyses. Of the 3459 study participants, 210 (6.07%) had at least one CHD event during the 12 years of follow-up. Multivariable stepwise Cox regression analysis, adjusted for known cardiovascular risk factors, socioeconomic status, and statin intake, revealed that high polygenic risk (hazard ratio [HR] 1.31, 95% CI 1.10-1.56, p=2.64 × 10^-3) and infection with Fusobacterium nucleatum (HR 1.63, 95% CI 1.08-2.45, p=1.99 × 10^-2) were independently associated with incident CHD. In a prospective, population-based cohort, high polygenic risk and infection with F. nucleatum have a small, yet independent impact on CHD risk.

Transgenically expressed Helicobacter pylori CagA in vascular endothelial cells accelerates arteriosclerosis in mice

Arteriosclerosis is intimately associated with cardiovascular diseases. Recently, evidence accumulated that infection with Helicobacter pylori cagA-positive strains, which causes gastritis, peptic ulceration, and gastric cancer, is also involved in the development of arteriosclerosis. The cagA-encoded CagA protein is injected into the attached gastric epithelial cells via the type IV secretion system. We previously showed that CagA-containing exosomes are secreted from CagA-injected gastric epithelial cells and enter the systemic blood circulation, delivering CagA into endothelial cells. In the present study, transgenic mice were established in which CagA was selectively expressed in endothelial cells by Cre-loxP system. Treatment of the mice with a high-fat diet revealed that atherogenic lesions were induced in mice expressing CagA in vascular endothelial cells but not in CagA-nonexpressing mice. To investigate the effects of CagA on endothelial cells, we also established conditional CagA-expressing human vascular endothelial cells using the Tet-on system. Upon induction of CagA, a dramatic change in cell morphology was observed that was concomitantly associated with the loss of the endothelial cells to form tube-like structures. Induction of CagA also activated the pro-inflammatory transcription factor STAT3. Thus, exosome-delivered CagA deregulates signals that activates STAT3 in endothelial cells, which accelerates inflammation that promotes arteriosclerosis/atherosclerosis.

Emerging Roles of Extracellular Vesicle-Delivered Circular RNAs in Atherosclerosis

Atherosclerosis (AS) is universally defined as chronic vascular inflammation induced by dyslipidaemia, obesity, hypertension, diabetes and other risk factors. Extracellular vesicles as information transmitters regulate intracellular interactions and their important cargo circular RNAs are involved in the pathological process of AS. In this review, we summarize the current data to elucidate the emerging roles of extracellular vesicle-derived circular RNAs (EV-circRNAs) in AS and the mechanism by which EV-circRNAs affect the development of AS. Additionally, we discuss their vital role in the progression from risk factors to AS and highlight their great potential for use as diagnostic biomarkers of and novel therapeutic strategies for AS.

Cytotoxin-associated gene A (CagA) promotes aortic endothelial inflammation and accelerates atherosclerosis through the NLRP3/caspase-1/IL-1β axis

Atherosclerosis is a chronic inflammatory disease. Pathophysiological similarities between chronic infections and atherosclerosis triggered interests between these conditions. The seroepidemiological study showed that Helicobacter pylori strains that express cytotoxin-associated gene A (CagA), an oncoprotein and a major virulence factor, was positively correlated with atherosclerosis and related clinical events. Nevertheless, the underlying mechanism is poorly understood. In this study, the seroprevalence of infection by H. pylori and by strains express CagA assessed by enzyme-linked immunosorbent assay (ELISA) showed that the prevalence of CagA strains rather than H. pylori in patients was positively correlated with atherogenesis. Correspondingly, we found that CagA augmented the growth of plaque of ApoE^-/- mice in the early stage of atherosclerosis and promoted the expression of adhesion molecules and inflammatory cytokines in mouse aortic endothelial cells (MAECs). Mechanistically, both si-NLRP3 and si-IL-1β mitigated the promoting effect of CagA on the inflammatory activation of HAECs. In vivo, the inhibition of NLRP3 by MCC950 significantly attenuated the promoting effect of CagA on plaque growth of ApoE^-/- mice. We also propose NLRP3 as a potential therapeutic target for CagA-positive H. pylori infection-related atherosclerosis and emphasize the importance of inflammation in atherosclerosis pathology.

Relationship Between Helicobacter pylori Infection and Arteriosclerosis

It is reported that Helicobacter pylori (H. pylori) infection may be linked to non-digestive tract diseases, such as arteriosclerosis including dyslipidemia, diabetes, obesity, hypertension, and cardiovascular disease. Therefore, we reviewed recent studies available in PubMed dealing with the mechanisms of arteriosclerosis due to H. pylori infection and the effects of H. pylori eradication. Conventional studies suggested that H. pylori infection may increase the risk of arteriosclerosis. A large interventional study is required to clarify the causal relationships and the effects of bacterial eradication.

Association between Helicobacter Pylori infection and stroke: a meta-analysis of 273,135 patients

BACKGROUND

Stroke stands among the most leading causes of mortality worldwide. Although modifiable risk factors for stroke have been identified, current risk factors do not sufficiently explain the risk in young patients. Previous studies have postulated an association between infection by Helicobacter pylori (HP) and stroke.

OBJECTIVE

To investigate the association between HP infection and stroke by using a systematic review and meta-analysis approach.

METHODS

Four electronic search engines/libraries were systematically searched for relevant observational studies. Studies were screened for eligibility and data were extracted. The odds ratio (OR) and 95% confidence interval (95% CI) were combined under the random-effect model. The protocol was registered in PROSPERO (CRD42019123689).

RESULTS

Among the included studies, 25 studies were analyzed for anti-HP IgG, 9 studies were for anti-Cag A, and 6 studies were for the C-urea breath test. The results showed that positive anti-HP IgG was significantly associated with an increased risk of stroke [OR (95% CI) = 1.43 (1.25-1.46)]. Similarly, both antiCag A and C-urea breath test were significantly associated with an increased risk of stroke with [OR (95% CI) = 1.77 (1.25-2.49)], and [OR (95% CI) = 2.21 (1.33-3.66)], respectively. Furthermore, our results indicated that positive anti-HP IgG was associated with stroke caused by atherothrombosis and small artery disease.

CONCLUSIONS

This study suggests that HP infection is significantly associated with increased risk of stroke. However, more well-designed studies are required to investigate if early HP eradication might decrease the incidence of stroke.

Exosomal CagA derived from Helicobacter pylori-infected gastric epithelial cells induces macrophage foam cell formation and promotes atherosclerosis

BACKGROUND

Seroepidemiological studies have highlighted a positive relation between CagA-positive Helicobacter pylori (H. pylori), atherosclerosis and related clinic events. However, this link has not been well validated. The present study was designed to explore the role of H. pylori PMSS1 (a CagA-positive strain that can translocate CagA into host cells) and exosomal CagA in the progression of atherosclerosis.

METHODS

To evaluate whether H. pylori accelerates or even induces atherosclerosis, H. pylori-infected C57/BL6 mice and ApoE^-/- mice were maintained under different dietary conditions. To identify the role of H. pylori-infected gastric epithelial cells-derived exosomes (Hp-GES-EVs) and exosomal CagA in atherosclerosis, ApoE^-/- mice were given intravenous or intraperitoneal injections of saline, GES-EVs, Hp-GES-EVs, and recombinant CagA protein (rCagA).

FINDINGS

CagA-positive H. pylori PMSS1 infection does not induce but promotes macrophage-derived foam cell formation and augments atherosclerotic plaque growth and instability in two animal models. Meanwhile, circulating Hp-GES-EVs are taken up in aortic plaque, and CagA is secreted in Hp-GES-EVs. Furthermore, the CagA-containing EVs and rCagA exacerbates macrophage-derived foam cell formation and lesion development in vitro and in vivo, recapitulating the pro-atherogenic effects of CagA-positive H. pylori. Mechanistically, CagA suppresses the transcription of cholesterol efflux transporters by downregulating the expression of transcriptional factors PPARγ and LXRα and thus enhances foam cell formation.

INTERPRETATION

These results may provide new insights into the role of exosomal CagA in the pathogenesis of CagA-positive H. pylori infection-related atherosclerosis. It is suggested that preventing and eradicating CagA-positive H. pylori infection could reduce the incidence of atherosclerosis and related events.

Application of proteomics to the study of Helicobacter pylori and implications for the clinic

INTRODUCTION

Helicobacter pylori (H. pylori) is a gram-negative bacterium that colonizes the gastric epithelium and mucous layer of more than half the world's population. H. pylori is a primary human pathogen, responsible for the development of chronic gastritis, peptic ulceration and gastric cancer. Proteomics is impacting several aspects of medical research: understanding the molecular basis of infection and disease manifestation, identification of therapeutic targets and discovery of clinically relevant biomarkers. Areas covered: The main aim of the present review is to provide a comprehensive overview of the contribution of proteomics to the study of H. pylori infection pathophysiology. In particular, we focused on the role of the bacterium and its most important virulence factor, CagA, in the progression of gastric cells transformation and cancer progression. We also discussed the proteomic approaches aimed at the investigation of the host response to bacterial infection. Expert commentary: In the field of proteomics of H. pylori, comprehensive analysis of clinically relevant proteins (functional proteomics) rather than entire proteomes will result in important medical outcomes. Finally, we provided an outlook on the potential development of proteomics in H. pylori research.

The association between cardiac and gastrointestinal disorders: causal or casual link?

Cardiovascular diseases are the leading cause of death worldwide: among them, coronary artery disease and arrhythmias represent the most frequent pathological conditions. Similarly, the gastrointestinal disorders, that is, gastroesophageal reflux and inflammatory bowel diseases, have a high incidence in the general population. Several pieces of evidence have documented a link between cardiac and gastrointestinal disorders as they often share similar risk factors and symptoms. Furthermore, both can simultaneously occur in the same patient, thus creating problems in the correct clinical diagnosis. It is well known that gastrointestinal disorders may present with chest pain and mimic angina pectoris. In contrast, they can also unmask heart disease, such as in the case of the angina-linked ischemia. The aim of this review was to elucidate the mechanisms underlying the relationship between cardiac and gastrointestinal diseases to better understand the causal or casual character of such a linkage.

Helicobacter pylori and cardiovascular complications: a mechanism based review on role of Helicobacter pylori in cardiovascular diseases

Heart disease comprises a wide class of cardiovascular abnormalities, including ischemic heart disease, myocardial infarction, atherosclerosis, and coronary artery disease. It is the leading cause of death all over the world. Several traditional and novel risk factors, such as infectious and noninfectious agents, have been associated with heart disease. Out of these, Helicobacter pylori has been recently introduced as an important etiological factor for heart disease. Numerous seroepidemiological findings observed H. pylori antibodies in the blood of a patient with cardiovascular complications. The bacteria survive in the epithelial cells of gastric organs and cause digestive complications. Excess inflammatory pathogenesis and prognosis stimulate an immune response that further causes significant disturbances in various factors like cytokines, fibrinogen, triglycerides, high density lipoprotein, C-reactive protein, heat shock protein, and white blood cell count, and provoke a number of problems such as atherosclerosis and prothrombic state, and cross-reactivity which eventually leads to heart diseases. H. pylori releases toxigenic nutrients, chiefly vacuolating cytotoxin gen A (Vac A) and cytotoxin associated gene A (Cag A), of which Cag A is more virulent and involved in the formation of cholesterol patches in arteries, induction of autoimmune disorder, and release of immune mediated response. Although numerous mechanisms have been correlated with H. pylori and heart disease, the exact role of bacteria is still ambiguous.

Association between Helicobacter pylori infection and stroke: a meta-analysis of prospective observational studies

BACKGROUND

Some studies have suggested an association between Helicobacter pylori infection and the risk of stroke, but the relationship remains controversial. The aim of this study was to obtain a more comprehensive estimate of H. pylori on the risk of stroke by performing a meta-analysis.

METHODS

A computerized search of PubMed, EMBASE, and the Cochrane library (including CENTRAL) up to February 2014 was performed to identify eligible studies. Prospective studies reported that a multivariate-adjusted estimate for the association between H. pylori and stroke were included. A random-effects model was used to calculate the overall combined risk.

RESULTS

Ten prospective observational studies (6 cohort studies, 4 nested case-control, or case-cohort studies within cohort studies) were included in the meta-analysis. The overall combined odds ratio for H. infection and stroke was .96 (95% confidence interval, .78-1.14). Similar results were yielded in patients with cytotoxin-associated gene-A seropositive strains. The combined estimates were robust across sensitivity analyses and had no observed publication bias.

CONCLUSIONS

In conclusion, our formal meta-analysis indicated no strong association between H. pylori infection and stroke, neither in those with cytotoxin-associated gene-A-positive infection. We believe that future epidemiologic studies of H. pylori and stroke are unlikely to be fruitful.

The relationship between Helicobacter pylori and beta-2 microglobulin in humans

H. pylori is related to various gastrointestinal diseases. β₂ Microglobulin (β₂M) is an intrinsic element of major histocompatibility complex (MHC I). Serum β₂M level may increase in inflammatory states. The aim of current study is to evaluate the relationship between β₂M and H. pylori bearing CagA strains. Methods. H. pylori status was determined by histopathology of samples taken from stomach. CagA status and β₂M level were measured from blood samples of patients. Eradication therapy was administered to the patients with H. pylori infection. β₂ Microglobulin levels were measured before and after treatment. Results. 35 (29.2%) H. pylori(−) patients and 85 (70.8%) H. pylori (+) patients were included in the study. There were 52 (43.3%) patients with CagA negative and 33 (27.5%) patients with CagA positive H. pylori infection. The mean serum β₂M level was 1.83 mg/L in H. pylori (−) group, 1.76 mg/L in H. pylori (+) CagA (−) group, and 1.93 mg/L in H. pylori and CagA (+) group (P > 0.05). Serum β₂M levels (1.82 versus 1.64 mg/L P < 0.05) were decreased after eradication. Conclusion. H. pylori and CagA status did not affect β₂M level. Relationship between low grade systematic inflammation and H. pylori should be investigated to find out new predictors for diseases associated with inflammation.

Clinical significance of Helicobacter pylori infection in patients with acute coronary syndromes: an overview of current evidence

Although Helicobacter pylori (Hp) primarily colonizes gastric mucosa, it can occasionally inhabit in atherosclerotic plaques. Both forms of Hp infection may be involved in the pathogenesis of atherosclerosis via activation of a systemic or local inflammatory host reaction and induction of plaque progression and/or instability, possibly leading to coronary syndromes. The association between Hp infection and cardiovascular endpoint prevalence remains uncertain; however, it has been reported in many epidemiological investigations and may be reasonably explained by pathophysiological mechanisms. Besides the inflammatory pathway, Hp infection may trigger acute coronary syndromes by enhanced platelet reactivity and increased risk of gastrointestinal bleeding (type 2 myocardial infarction). The former seems to be predominantly related to the stimulatory effect of Hp infection on von Willebrand factor-binding and P-selectin activation, and the latter results from cytotoxic bacteria properties and aggravation of digestive tract injury related to aspirin or dual antiplatelet therapy. Despite these premises, the role of Hp infection in cardiovascular syndromes should still be recognized as controversial and requiring randomized, controlled trials to evaluate the outcome of Hp eradication in both cardiac and gastroenterological endpoints. Such need is also justified by potential bias of previous studies resulting from (1) using different diagnostic methods for identification of Hp infection, since only a small number of studies required confirmation of active Hp infection; and from (2) common lack of adjustment for important confounders such as socioeconomic status, smoking and effectiveness of eradication therapy, as well as the genetic characteristics of both the host and the bacterium.

Association of Helicobacter pylori infection with coronary artery disease: is Helicobacter pylori a risk factor?

BACKGROUND

Helicobacter pylori (HP) infection is the most common infection in the world and coronary artery disease (CAD) is probably associated with it. The aim of this prospective study was to evaluate the association between HP infection and CAD in suspected patients referred for coronary angiography. The coronary angiography was performed using Judkins method and patients were assigned to participate in CAD positive (>50% luminal diameter stenosis) and negative groups. The serum HP IgG antibody was checked.

RESULTS

Positive and negative CAD groups consisted of 62 and 58 patients, respectively. HP was more prevalent among CAD+ patients, and with increasing the number of coronary arteries with stenosis, the HP seropositivity increased so that 76.3% of patients with multiple vessel diseases (MVD) and 70% of patients with single vessel diseases (SVD) were HP seropositive versus 50% in control group (P = 0.006). Positive CAD was significantly associated with HDL level (P = 0.01) and ESR level (P = 0.006). Also, CAD+ patients had higher CRP levels than controls and it was statistically different between SVD group and controls (P < 0.05).

CONCLUSION

HP infection is more prevalent in CAD positive patients and, in case of proving causal relationship, it can be considered as a reversible risk factor for CAD.

Association of Helicobacter pylori infection with acute myocardial infarction

OBJECTIVES

Helicobacter pylori infection has been linked to cardiovascular diseases (CVD) and several studies have reported its positive association with inflammatory response after acute myocardial infarction (AMI). On account of the importance of the inflammatory process in the development of CVD, we decided to examine the seroprevalence of H. pylori, the prevalence of CVD risk in the more virulent strains bearing the cytotoxin-associated protein (CagA), and the changes in C-reactive protein (CRP) as an inflammatory marker in Iranian patients with AMI.

METHODS

A case-control study was designed to determine the seropositivity status of H. pylori and CagA in blood samples obtained from 500 patients with AMI and 500 control individuals without any evidence of clinical CVD. Serum and peripheral blood mononuclear cells were analyzed using the enzyme-linked immunosorbent assay and western blotting methods, respectively. CRP levels were also measured in all individuals.

RESULTS

The prevalence of H. pylori infection and CagA status were significantly higher among the patients with AMI than the controls (66 vs. 20% and 75.7 vs. 30%, respectively); the odds ratio was 2.57 (95% confidence interval 1.89-3.49). CRP levels were significantly different in the patients compared with the controls (5.02±1.04 mg/l vs. 2.41±0.9 mg/l, respectively).

CONCLUSION

Our results confirmed that the patients with AMI had a significantly higher prevalence of H. pylori infection and CagA seropositivity than the control population. Infection with H. pylori may influence AMI, which in our findings shows an association between H. pylori seropositivity and AMI through an inflammatory process.

CagA-positive Helicobacter pylori strains enhanced coronary atherosclerosis by increasing serum OxLDL and HsCRP in patients with coronary heart disease

BACKGROUND

The role of infection in the pathogenesis of atherosclerosis is still a matter of debate.

AIMS

This study aimed to investigate the effect of CagA-positive Helicobacter pylori (H. pylori) strains infection on coronary atherosclerosis in patients with coronary heart disease and to elucidate how cytotoxin-associated gene A (CagA)-positive H. pylori strains infections were involved in coronary heart disease by examining the levels of serum lipid, high-sensitivity C-reactive protein (hsCRP) and oxidized low-density protein (oxLDL).

METHODS

Recruited for this study were 159 patients with coronary heart disease. The severity of coronary heart disease was estimated by calculating the Gensini score. Serum oxLDL and hsCRP were examined in all subjects. Current H. pylori infection was determined in all participants by means of a modified (13C) urea breath test (>200 dpm classified as positive). IgG antibodies against CagA protein were analyzed by enzyme immunoassays. Antibody titers against CagA (≥8 U/ml) were classified as positive. All subjects were divided into three groups, including an uninfected group (n=30), an H. pylori +CagA- group (n=69), and an H. pylori +CagA+ group (n=60).

RESULTS

Significant differences were found among the three groups in levels of total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, serum hsCRP, oxLDL, and severity of coronary atherosclerosis (p<0.05). The levels of total cholesterol, LDL, apolipoprotein B, serum hsCRP, oxLDL were significantly elevated and the severity of coronary atherosclerosis was significantly increased in H. pylori +CagA+ group (p<0.05).

CONCLUSIONS

More serious coronary atherosclerosis was observed in CHD patients with H. pylori +CagA+ infection. H. pylori +CagA+ infection might be involved in coronary atherosclerosis by modifying serum lipids, enhancing LDL oxidation, and activating the inflammatory responses.

Helicobacter pylori cytotoxin-associated gene-A antibodies do not predict complications or death in type 2 diabetes: the Fremantle Diabetes Study

OBJECTIVES

There is cross-sectional evidence that CagA antigen produced by Helicobacter pylori is associated with coronary heart disease, stroke, atrial fibrillation (AF) and microalbuminuria, but no large-scale longitudinal studies have been conducted in diabetic patients. We aimed to determine whether cytotoxin-associated gene-A (CagA) seropositivity is independently associated with important vascular outcomes in type 2 diabetes.

METHODS

We studied 1179 type 2 patients from a well characterized community-based cohort who had available sera from baseline assessment between 1993 and 1996, and follow-up for incident events to end-June 2007. H. pylori IgG and CagA antibodies at baseline were measured by validated ELISA. Multiple logistic/linear regression analysis and Cox proportional hazards modelling were used to determine independent baseline associates of prevalent and incident complications, respectively, including H. pylori/CagA serostatus.

RESULTS

At baseline, 62.0% of patients were H. pylori seropositive and 37.7% were both H. pylori and CagA seropositive. CagA seropositivity was not independently associated with prevalent coronary heart disease (CHD), cerebrovascular disease (CVD), peripheral arterial disease or AF at baseline (P > 0.41), but there was a significant inverse association with ln(urinary albumin:creatinine) (P = 0.033). There were no independent associations between CagA seropositivity and incident CHD/CVD or progression to microalbuminuria (P > 0.20). During follow-up, 480 patients (40.7%) died, 246 (50.2%) from cardiovascular causes. After adjustment for other variables,CagA seropositivity was weakly protective against cardiovascular death (P = 0.024).

CONCLUSION

CagA seropositivity is not a risk factor for chronic vascular complications of type 2 diabetes. Assay of CagA antibodies does not contribute significantly to clinical management outside gastroenterological indications.

Common infections and the risk of stroke

The occurrence of stroke in populations is incompletely explained by traditional vascular risk factors. Data from several case-control studies and one large study using case series methodology indicate that recent infection is a temporarily acting, independent trigger factor for ischemic stroke. Both bacterial and viral infections, particularly respiratory tract infections, contribute to this association. A causal role for infection in stroke is supported by a graded temporal relationship between these conditions, and by multiple pathophysiological pathways linking infection and inflammation, thrombosis, and stroke. Furthermore, observational studies suggest that influenza vaccination confers a preventive effect against stroke. Case-control and prospective studies indicate that chronic infections, such as periodontitis, chronic bronchitis and infection with Helicobacter pylori, Chlamydia pneumoniae or Cytomegalovirus, might increase stroke risk, although considerable variation exists in the results of these studies, and methodological issues regarding serological results remain unresolved. Increasing evidence indicates that the aggregate burden of chronic and/or past infections rather than any one single infectious disease is associated with the risk of stroke. Furthermore, genetic predispositions relating to infection susceptibility and the strength of the inflammatory response seem to co-determine this risk. Here, we summarize and analyze the evidence for common acute and chronic infectious diseases as stroke risk factors.

Helicobacter pylori infection is associated with decreased serum levels of high density lipoprotein, but not with the severity of coronary atherosclerosis

OBJECTIVE

The objective of this survey was to study the association between Helicobacter pylori infection and the severity of coronary atherosclerosis.

METHODS

The study population consisted of 961 consecutive patients (711 males and 250 females) who underwent coronary angiography for suspected or known coronary atherosclerosis. The patients' body mass index, blood pressure, the blood lipid, blood glucose, leukocyte count (10(9)/L), neutrophil count (10(9)/L), and Helicobacter pylori-specific IgG antibodies were performed. Coronary angiograms were scored according to vessel score and Gensini's score.

RESULTS

A significant association between H. pylori infection and coronary atherosclerosis as well as its severity was not find in this cross section study (p = 0.858). And, the level distribution of vessel score (p = 0.906) and Gensini's score (p = 0.905) were similar in the seropositivity group and seronegativity group of Helicobacter pylori infection. However, the level of fasting high-density lipoprotein cholesterol (mmol/L) (p = 0.013) was significantly lower in the seropositivity group than that in the seronegativity group of Helicobacter pylori infection.

CONCLUSIONS

In conclusion, in the present study, a significantly correlation between Helicobacter pylori seropositivity and angiographically evaluated severity of atherosclerosis was not find. And, the present study showed a good correlation between Helicobacter pylori infection and decreased HDL cholesterol. However, the exact mechanisms need further study.

Helicobacters and extragastric diseases

For two decades, Helicobacter pylori has been considered as the culprit in many extragastric manifestations. However, for several of these supposed associations the hypothesis of an etiological role has not yet been fully investigated. This may be due to a series of factors linked to the epidemiological features of the studies and to the diseases investigated. This review attempts to highlight the main reported associations of H. pylori with extragastric manifestations during the last year. The most convincing data arise in the field of idiopathic thrombocytopenic purpura (ITP) and sideropenic anemia. Long-term follow-up studies have shown that 50% of subjects with ITP maintain a hematological response after H. pylori eradication. There is also growing evidence of the role of H. pylori in other diseases, including ischemic heart disease even though results are not conclusive.