Hyperhomocysteinaemia, Helicobacter pylori, and coronary heart disease

Helicobacter pylori infection and the progression of atherosclerosis: A systematic review and meta-analysis

OBJECTIVE

In recent years, many studies have tried to prove whether Helicobacter pylori (H. pylori) can promote the progression of atherosclerosis (AS), but the reported results are conflicting. Carotid intima-media thickness (CIMT), flow-mediated dilation (FMD), or pulse wave velocity (PWV) are the most commonly used indicators to evaluate the progress of AS. So, we collected and evaluated these three indicators to provide evidence-based medicine for the clinic.

MATERIALS AND METHODS

We included and evaluated studies on H. pylori infection and CIMT, FMD, or PWV from PubMed, Cochrane trials, and Embase databases before September 1, 2021, and language restrictions: English. Research types include cross-sectional studies, cohort studies, and case-control studies. The MINORS scale was used to evaluate the quality of these studies. For all studies, we choose a random-effects model and calculate the weighted mean difference (WMD) for analysis, and all our analyses use STATA software.

RESULTS

Meta-analysis shows that H. pylori infection can significantly increase CIMT (WMD = 0.059, 95% CI: 0.039, 0.079, p < 0.001). Based on subgroup analysis, we found that the relationship between the two is more significant in the young and middle-aged people younger than 60 years old and people without cardiovascular disease. In addition, we also found an association between H. pylori infection and FMD (WMD = -3.873, 95% CI: -5.684, -2.062, p < 0.001), but it is a pity that there are few literatures that meet the standards. Finally, We concluded that H. pylori infection can significantly increase PWV (WMD = 88.033, 95%CI: 67.297,108.768. I²  = 99.63%, p < 0.001). In the subgroup analysis, we also found that this correlation is similar to CIMT, and it is more significant in the young and middle-aged population under 60 and those without cardiovascular disease. We also found in the sub-analysis that there was a significant increase in CIMT in CagA-positive individuals in H. pylori-infected patients (WMD = 0.16, 95%CI: 0.02, 0.29. p = 0.03).

CONCLUSION

Helicobacter pylori infection can promote the process of AS, especially in people under the age of 60 and people without cardiovascular risk factors, and we hope that our meta-analysis can provide ideas for the early prevention of AS.

Helicobacter pylori Infection Acts as an Independent Risk Factor for Intracranial Atherosclerosis in Women Less Than 60 Years Old

Background: Studies show inconsistent results regarding the relationship between Helicobacter pylori (H. pylori) infection and stroke. The present study assessed a potential association between H. pylori infection and an important risk factor for stroke, intracranial atherosclerosis.

Methods: In total, 15,798 subjects with transcranial Doppler (TCD) and 13C-urea breath test (13C-UBT) were enrolled from March 2012 to March 2017. Intracranial atherosclerosis was further measured using intracranial carotid artery calcification (ICAC) on past or recent head CT, and 14,084 subjects were ultimately included in the study. Baseline demographics, atherosclerosis risk factors, and laboratory results were investigated. Since endothelial dysfunction is critical to the development of atherosclerosis, the role of H. pylori in migration, tube formation, and proliferation of human brain microvascular endothelial cells (HBMECs) was assessed in vitro.

Results: The intracranial atherosclerosis group had a higher proportion of women and a greater rate of H. pylori infection than those without intracranial atherosclerosis. H. pylori infection was significantly more common in women with intracranial atherosclerosis than males. In addition, the incidence of intracranial atherosclerosis was significantly higher in women with H. pylori infection than uninfected women (53.8 vs. 46.4%, p &lt; 0.001). In an adjusted model, H. pylori was shown to be an independent risk factor for intracranial atherosclerosis in women ≤ 60 years of age [odds ratio (OR) = 2.261, 95% CI = 1.839–2.780, p &lt; 0.001]. Serum exosomes from patients with H. pylori infection had significantly reduced brain endothelial cell migration, tube formation, and proliferation in vitro.

Conclusion:Helicobacter pylori infection may be an important independent risk factor for intracranial atherosclerosis in women ≤ 60 years of age.

The evidence for a role of bacteria and viruses in cardiovascular disease

Inflammation plays a critical role in atherosclerosis and cardiovascular disease. Bacteria and viruses are major causative agents of inflammation in the body which normally develops as a response to infection. It is a logical extention, therefore, to believe bacterial and viral infections may be involved in a variety of presentations of cardiovascular diseases. The purpose of this review is to describe the data and conclusions to date on the involvement of these infectious agents in the induction of cardiovascular disease. The review also discusses the various specific bacteria and viruses that have been implicated in cardiovascular disease and the mechanisms, if known, that these agents induce cardiovascular disease.

40 Years of Helicobacter pylori: A Revolution in Biomedical Thought

Background: Various microorganisms such as bacteria, virus, and fungi can infect humans and cause not just a simple infection but septic conditions, organ dysfunction, and precancerous conditions or cancer involving various organ systems. After the discovery of the microscope, it was easier to discover and study such microorganisms, as in the case of Helicobacter pylori, a pathogen that was seen in the distant era of the nineteenth century but without being recognized as such. It took 100 years to later discover the pathogenesis and the cancer that this bacterium can cause. Since it was discovered, until today, there has been a continuous search for the understanding of its pathogenetic mechanisms, and the therapeutic approach is continuously updated. Methods: We investigated how diagnosis and therapy were dealt with in the past and how researchers sought to understand, exactly, the pathogenetic biomolecular mechanisms of H. pylori, from the genesis of the infection to the current knowledge, with an analysis of carcinogenic mechanisms in the stomach. We have examined the scientific evolution of the knowledge of the disease over these 40 years in the gastroenterological and pharmacological fields. This was possible through a search in the databases of Medline, the WHO website, the Centers for Disease Control and Prevention (CDC) website, PubMed, and Web of Science to analyze the earlier and the latest data regarding H. pylori. Results: With the scientific discoveries over time, thanks to an increasing number of progressions in scientific research in the analysis of the gastric mucosa, the role of Helicobacter pylori in peptic ulcer, carcinogenesis, and in some forms of gastric lymphoma was revealed. Furthermore, over the years, the biomolecular mechanism involvement in some diseases has also been noted (such as cardiovascular ones), which could affect patients positive for H. pylori. Conclusions: Thanks to scientific and technological advances, the role of the bacterium H. pylori in carcinogenesis has been discovered and demonstrated, and new prospective research is currently attempting to investigate the role of other factors in the stomach and other organs. Cancer from H. pylori infection had a high incidence rate compared to various types of cancer, but in recent years, it is improving thanks to the techniques developed in the detection of the bacterium and the evolution of therapies. Thus, although it has become an increasingly treatable disease, there is still continuous ongoing research in the field of treatment for resistance and pharma compliance. Furthermore, in this field, probiotic therapy is considered a valid adjuvant.

Serum and Mucosal Cytokine Profiles in Patients with Active Helicobacter Pylori and Ischemic Heart Disease: Is There a Relationship?

This study is designed to investigate, for the first time, circulating and gastric mucosal levels of IL1-α, IL-6, IL-8 and TNF-α in patients with ischemic heart disease (IHD) and matched controls, according to the presence or absence of active Helicobacter pylori infection. Furthermore, in order to evaluate whether modified lipid profile was associated to an increased cardiovascular risk, this was determined in the same groups. Cytokine levels were measured using ELISA in 58 patients with IHD and 52 controls. Active H. pylori infection was assessed if either culture of H. pylori or rapid urease test gave a positive result. Our findings indicate increasing cytokine mucosal levels in H. pylori-positive patients compared to H. pylori-negative subjects. However, the increase was statistically significant only for IL-6 and TNF-α in the gastric mucosa of IHD patients. In H. pylori-positive controls, IL-8 mucosal levels positively correlated with both IL-1α (r = 0.98; P = 0.0003) and IL-6 (r = 0.83; P = 0.03) levels. Circulating cytokine levels were comparable in IHD and healthy subjects, regardless of H. pylori status. There were no correlations between mucosal and circulating cytokine levels. Active H. pylori infection was not associated with a modified lipid profile in either controls or IHD patients, although ApoAI levels were significantly higher in H. fly/ort'-positive controls compared to those H. pylori-negative. Taken together, the results of the present study provide evidence that active H. pylori infection may play a role as a trigger factor in the pathophysiology of IHD by inducing an inflammatory cascade concentrated on gastric mucosa.

Helicobacter pylori gastritis, a presequeale to coronary plaque

Helicobacter pylori are considered the most common human pathogen colonizing gastric mucosa. Gastritis with or without H. pylori infection is associated with increase in levels of homocysteine and high-sensitivity C-reactive protein (hs-CRP) but a more pronounced increase is noted in gastritis with H. pylori infection. Increasing level of homocysteine, due to decreased absorption of vitamin B₁₂ and folic acid, together with increased CRP levels in gastritis with H. pylori infection may be the earliest event in the process of atherosclerosis and plaque formation. Retrospective study conducted at tertiary care hospital in Mumbai by Department of Biochemistry in association with Department of Surgery. Eighty patients who underwent gastroscopy in view of gastritis were subjected to rapid urease test for diagnosis of H. pylori infection. Vitamin B₁₂, folic acid, homocysteine and hs-CRP were analyzed using chemiluminescence immuno assay. Student’s t-test, Pearson’s correlation and linear regression used for statistical analysis.

Patients with H. pylori gastritis had significantly lower levels of vitamin B₁₂ (271.6±101.3 vs 390.6±176.7 pg/mL; P=0.0005), as well as higher levels of homocysteine (17.4±7.4 vs 13.8±7.8 µmol/L; P=0.037) and hs-CRP (2.5±2.9 vs 1.2±1.1 mg/L; P=0.017), than in patients without H. pylori gastritis. However, folic acid showed (8.9±3.2 vs 10.0±3.6 ng/mL; P=0.171) no significant difference.

Elevated homocysteine and hs-CRP in H. pylori gastritis may independently induce endothelial dysfunction, leading to cardiovascular pathology.

Helicobacter pylori-an infectious risk factor for atherosclerosis?

Accumulating evidence implicates Helicobacter pylori (H. pylori) infection in the pathogenesis of certain diseases localized outside the stomach, particularly those characterized by persistent and low-grade systematic inflammation. Recently, the role of H. pylori infection in the development of atherosclerosis and its clinical complications has received attention. Atherosclerosis is a high-cost disease, and acute events resulting from this condition rank first among morbidity and mortality statistics in most industrialized countries. Atherosclerosis is a multifactorial disorder, and traditional risk factors explain only 50% of its etiology. Therefore, identifying new risk factors for atherosclerosis is necessary. Serological studies indicate that chronic H. pylori infection, especially that with more virulent strains, may predispose patients to the onset of atherosclerosis and related adverse clinical events, and PCR studies have detected H. pylori DNA in atherosclerotic plaques, although this finding remains controversial. If this association were to be confirmed, its importance to public health would be substantial, as the eradication of H. pylori is more straightforward and less costly than the long-term treatment of other risk factors. This review investigates the potential relationship between H. pylori infection and atherosclerosis from both epidemiological and pathogenic perspectives and characterizes the potential mechanisms underlying this correlation.

Association between helicobacter pylori infection and body mass index, before and after eradication of infection in hemodialysis batients

BACKGROUND

In dialysis patients, chronic infections have been associated with cachexia and anorexia.

OBJECTIVES

This study was carried out to determine the association between Helicobacter pylori (HP) infection and body mass index (BMI) in hemodialysis (HD) patients.

PATIENTS AND METHODS

Ninety eight patients were divided into two groups of negative (group 1) and positive (group 2), for HP. BMI of all patients was measured at the beginning and in group2 after six months following eradication of HP. Before dialysis, various paraclinical parameters were checked at the same intervals.

RESULTS

Fifty-nine patients were enrolled in group 1 and 39 patients in group 2. The means of BMI in groups 1 and 2 were 23.4±3.7 and 25.8±4.4kg/m², respectively. Prior to the study, there was no significant difference for BMI, duration of HD and paraclinic data between two groups. Group 2 took anti HP therapy and eradication occurred in 30 of them. In this group six months after eradication of HP, the BMI was significantly decreased from 25.02±4.4 to 24.4±4.0 kg/m² (P = 0.001). Also six months following the eradication of HP, the mean of serum albumin level was significantly declined from 4.2 to 3.7 g/L (P<0.001). There was also significant decrease in cholesterol (P=0.001), blood urea nitrogen (P=0.005) and calcium (P=0.02). However, significant increase in hemoglobin level was also seen (P=0.03).

CONCLUSIONS

The results of this study show that eradication of HP has an impact on BMI. The results need to be investigated with larger cases.

Extragastrointestinal manifestations of Helicobacter pylori infection: facts or myth? A critical review

Helicobacter pylori (H. pylori) infection is reported to be associated with many extragastrointestinal manifestations, such as hematological diseases [idiopathic thrombocytopenic purpura (ITP) and unexplained iron deficiency anemia (IDA)], cardiovascular diseases (ischemic heart diseases), neurological disorders (stroke, Parkinson's disease, Alzheimer's disease), obesity and skin disorders. Among these, the best evidence so far is in ITP and unexplained IDA, with high-quality studies showing the improvement of IDA and ITP after H. pylori eradication. The evidence of its association with coronary artery disease is weak and many of the results may be erroneous. The role of H. pylori infection in affecting serum leptin and ghrelin levels has attracted a lot of attention recently and available data to date have been conflicting. There have also been many uncontrolled, small sample studies suggesting an association between H. pylori infection and neurological disorders or chronic urticaria. However, more studies are required to clarify such proposed causal links.

Comparison of azithromycin and clarithromycin triple therapy regimens for helicobacter pylori eradication in hemodialysis patients

Background

Helicobacter pylori eradication with clarithromycin is more expensive than with azithromycin.

Objectives

This study aimed to compare the effectiveness of these two antibiotics in eradicating H. pylori in hemodialysis (HD) patients.

Patients and Methods

This is a prospective, randomized, double-blinded clinical trial analysis of HD patients. Patients who had dyspepsia and showed positive results for two of three tests, anti-H. pylori serology, H. pylori stool antigen (HpSAg), or Urease Breath Test (UBT), were included in the study. The subjects consisted of 39 dialysis patients who were randomly divided into two groups that received medication twice daily. Group OAC received 20 mg omeprazol, 500 mg amoxycilin, and 250 mg clarithromycin, and Group OAAz received 20 mg omeprazol, 500 mg amoxicillin, and 250 mg azithromycin. Both regimens were administered for 14 days. Eradication was investigated by performing the UBT and the HpSAg test eight weeks later.

Results

This study began with 39 patients, 37 of which completed the treatment schedule (20 males and 17 females, mean age 59 years). Two patients died due to MI before beginning treatment. In the OAC group, negative results on the UBT and HpSAg tests were found in 82.4% and 88.2% of the participants, respectively. In the OAAz group, these values were 80% and 85%, respectively. The data showed that the difference between the two regimens was not significant (P = 1.0).

Conclusions

According to the data, no differences in eradication rates were apparent between the azitromycin and the claritromycin regimens. However, lower cost and fewer complaints could be considered as an advantage of the triple therapy with azithromycin.

Helicobacter pylori serum antibody titers in patients with cerebral non-cardioembolic ischemic stroke

BACKGROUND

Helicobacter pylori (H. pylori) infection has been associated with atherosclerosis of coronary arteries but there is lack of data regarding possible association between chronic H. Pylori infection and cerebral non-cardioembolic ischemia. We evaluated H. pylori serum antibody titers in patients with cerebral non-cardioembolic ischemic stroke.

METHODS

This was a cross-sectional study carried out in Alzahra hospital, Isfahan, Iran. 96 patients with ischemic stroke were enrolled in this study. Control group were selected from healthy blood donors. IgG and IgA antibodies to H. pylori were detected using a rapid enzyme linked immunosorbent assay. Quantitative variables and categorical variables were compared using t student and chi-square tests.

RESULTS

There were 21 cases of hypertension and 5 cases of diabetes mellitus among patients. Patients and controls were similar regarding serum IgA and IgG titers as well as positivity. There were 13 and 15 cases of positive IgA and 44 and 39 cases of positive IgG among patients and controls, respectively. Also, there were 7 and 9 cases of both positive IgA and IgG in patients and controls, respectively. No differences were found between the two groups in IgA or IgG titers or positivity (p > 0.05).

CONCLUSIONS

Patients with stroke were not different regarding either H. Pylori IgA or IgG positivity or the antibody titers. Comparing genetic typing of H. pylori in patients with or without stroke and diagnosis of H. pylori with more specific and sensitive tests such as stool antigen test are recommended.

Helicobacter pylori seropositivity in patients with acute coronary syndromes

The aim of this study was to investigate the seroprevalence of Helicobacter pylori (HP) in patients with coronary atherosclerosis and acute coronary syndromes. We enrolled 152 patients (group I, 73 patients with acute coronary syndrome; group II, 79 patients with chronic stable angina) and 22 control subjects. An enzyme-linked immunosorbent assay for immunoglobulin (Ig) G test for HP diagnosis was used on all enrolled subjects. C-reactive protein (CRP) was also measured in all patients as an inflammatory marker. Seropositivity rates for HP were significantly higher in patients with coronary artery disease than in controls (80.2% versus 54.5%; P < 0.05). Although CRP level was significantly higher in group I than in group II (1.72 +/- 2.89 mg/dl versus 0.53 +/- 0.63 mg/dl, P < 0.0001), HP infection rates were similar between groups (86.3% versus 74.6%, P > 0.05). Infection with HP may influence atherogenesis through low-grade, persistent inflammatory stimulation. However, our data show evidence of increased systemic inflammation in patients with acute coronary syndrome, which was unrelated to an increased HP seropositivity.

Helicobacter pylori infection and arterial stiffness in patients with type 2 diabetes mellitus

Epidemiologic studies have suggested possible atherogenic roles for such pathogens as Chlamydia pneumoniae, Helicobacter pylori (Hp), cytomegalovirus, and herpes simplex virus. The aim of the present study was to examine the relationship between seropositivity of antibodies to Hp (Hp infection) and arterial stiffness determined by pulse wave velocity (PWV) in 130 patients (73 men and 57 women) with type 2 diabetes mellitus without a history of cardiovascular disease. The prevalence of Hp infection in patients with type 2 diabetes mellitus was 53.8%. Age (66.7 +/- 11.3 vs 60.0 +/- 12.2 years, P = .0014) and systolic blood pressure (138 +/- 19 vs 131 +/- 22 mm Hg, P = .0420) were significantly higher in patients with Hp infection than in those without. Serum C-reactive protein was higher in patients with Hp infection than in those without, although it did not reach statistical significance (0.23 +/- 0.27 vs 0.18 +/- 0.20 mg/dL, P = .2205). Pulse wave velocity was significantly higher in patients with Hp infection than in those without (1877 +/- 550 vs 1585 +/- 331 cm/s, P = .0005). Multiple regression analysis demonstrated that age (beta = .388, P < .0001), mean arterial pressure (beta = .289, P = .0006), hypertensive treatment (beta = .185, P = .0282), and presence of Hp infection (beta = .169, P = .0220) were independent determinants of PWV. In conclusion, Hp infection is associated with arterial stiffness determined by PWV in patients with type 2 diabetes mellitus.

Significant association between Helicobacter pylori infection and serum C-reactive protein

BACKGROUND

Helicobacter pylori (H. pylori) infection in gastric mucosa may cause systemic inflammatory reaction. This study aimed to examine the association between the infection and serum high sensitivity C-reactive protein (hsCRP).

METHODS

Subjects were comprised of three groups; 453 health checkup examinees from Yakumo town inhabitants in Hokkaido, Japan (YTI, 153 males and 300 females), 449 health checkup examinees (ENUH, 273 males and 176 females), and 255 female patients of an infertility clinic (PIC), Nagoya University Hospital. Twenty participants with hsCRP more than 1 mg/dl were excluded from the analysis. Those with hsCRP more than 0.1mg/dl were defined as high hsCRP individuals. H. pylori infection status was examined with a serum IgG antibody test.

RESULTS

When the three groups were combined, the geometric mean of hsCRP concentration was significantly higher among the seropositives (0.047 mg/dl) than among the seronegatives (0.035 mg/dl); p<0.0001 by a t-test. The percentage of high hsCRP individuals was also higher in the seropositives than in the seronegatives among any group; 23.3% and 20.1% in YTI, 22.0% and 16.0% in ENUH, and 32.7% and 18.7% in PIC, respectively, although the difference was significant only in ENUH. The summary odds ratio of the high hsCRP for the seropositives relative to the seronegatives was 1.38 (95% confidence interval, 1.01-1.89), when age, sex, body mass index, smoking, and subject group were adjusted by a logistic model.

CONCLUSIONS

In three groups, hsCRP was higher among the infected individuals. The summary odd ratio indicated that H. pylori infection could influence the serum hsCRP level.

Association between Helicobacter pylori-infection, C-reactive protein and status of B vitamins

PURPOSE

Some investigations, but not all, found that a chronic infection with Helicobacter pylori (Hp) is associated with deficiencies in B vitamins, elevated plasma total homocysteine concentrations (tHcy) and increased plasma levels of proinflammatory acute-phase proteins. It has been suggested that these factors promote atherogenesis and therefore could mechanistically explain why people infected with Hp might have an increased risk for cardiovascular diseases (CVD). Therefore we evaluated the association between Hp-infection, concentration of C-reactive protein (CRP), and status of various B vitamins in apparently healthy subjects.

MATERIAL AND METHODS

In 69 subjects with proved Hp-infection and 21 healthy control subjects identified in a cross sectional study, blood samples were collected to determine serum folate, serum vitamin B12, serum methylmalonic acid (MMA), serum CRP and plasma vitamin B6 and plasma total homocysteine (tHcy).

RESULTS

The mean concentration of CRP was significantly higher in the Hp-positive collective than in controls. Although mean concentrations of vitamin B12, B6, and MMA differed between the groups, statistical significance was missed. However, the mean concentrations of homocysteine and folic acid were nearly the same in both groups. In univariate analysis a significant impact of Hp-status was shown on cobalamin (p=0.028; eta square: 0.055), and in multivariate analysis of variance the Hp-status had an impact on vitamin B12-values (p=0.028; eta square 0.057).

CONCLUSIONS

In this study Hp-infection shows no significant impact on status of B vitamins, but has a significant influence on CRP concentration. However, this study does not support the hypothesis that Hp-infection is related to CVD via elevated levels of tHcy.

Elevated homocysteine levels in patients with slow coronary flow: relationship with Helicobacter pylori infection

BACKGROUND AND OBJECTIVE

Elevation of plasma homocysteine (Hcy) level has been implicated in the pathogenesis of slow coronary flow (SCF) as it can severely disturb vascular endothelial function. Helicobacter pylori chronically infect the human stomach and causes malabsorption of vitamin B(12) and folate in food, leading ultimately to an increase in circulating Hcy levels.

METHODS

Forty-three patients with angiographically proven SCF (group I) were enrolled in this study; 43 cases with normal coronary flow pattern (group II) served as controls. Fasting plasma levels of Hcy, vitamin B(12), and folate were measured in all subjects. Presence of H. pylori infection was defined as positive 14 C urea breath test. Coronary flow patterns for each major epicardial coronary artery were determined with the Thrombolysis in Myocardial Infarction (TIMI) frame count method.

RESULTS

Mean TIMI frame count was 46.3 +/- 8.7 in group I and 24.3 +/- 2.9 in Group II (p = .0001). Vitamin B(12) levels were similar, whereas folate levels were dramatically reduced in group I compared to group II (13.2 +/- 4.3 vs. 17.1 +/- 5.2, p = .0001). Plasma Hcy levels were significantly higher in group I compared to group II (13.4 +/- 5.6 vs. 7.9 +/- 2.5, p = .0001) as was the prevalence of H. pylori infection (90.7% in group I vs. 58.1% in group II, p = .001). Hcy levels were elevated (11.7 +/- 5.3 vs. 7.5 +/- 2.7, p = .0001) and folate levels were reduced (13.9 +/- 4.7 vs. 18.6 +/- 4.9, p = .0001) in patients with H. pylori infection, while vitamin B(12) levels were similar in patients with and without H. pylori infection. Correlation analysis revealed a significant negative correlation between plasma folate and Hcy levels and also between folate levels and mean TIMI frame counts (r = -.33, p = .002 vs. r = -.33, p = .003). Moreover, there was a significant positive correlation between plasma Hcy levels and mean TIMI frame counts (r = .66, p = .0001). In addition, the folate level was the only significant determinant of the variance of Hcy in multiple regression analysis (r = -.21, p = .03).

CONCLUSION

Our data showed that plasma folate levels were decreased and plasma Hcy levels were increased in patients with SCF compared to controls. Also, the prevalence of H. pylori infection was increased in patients with SCF. These findings suggest that elevated levels of plasma Hcy, possibly caused by H. pylori infection, and/or a possible disturbance in its metabolism may play a role in the pathogenesis of SCF.

A review of the postulated mechanisms concerning the association of Helicobacter pylori with ischemic heart disease

Since its discovery, Helicobacter pylori has been implicated in the pathogenesis of several diseases, both digestive and extradigestive. Interestingly, the majority of the extradigestive-related literature is focused on two vascular manifestations: stroke and ischemic heart disease. Potential mechanisms for the establishment of a H. pylori-induced ischemic heart disease have been proposed with regard to chronic inflammation, molecular mimicry, oxidative modifications, endothelial dysfunction, direct effect of the microorganism on atherosclerotic plaques as well as changes regarding traditional or novel risk factors for ischemic heart disease or even platelet-H. pylori interactions. A positive link between H. pylori infection and ischemic heart disease has been suggested by a series of studies focusing on epidemiologic evidence, dyslipidemic alterations, upregulation of inflammatory markers or homocysteine levels, induction of hypercoagulability, oxidation of low-density lipoprotein, causation of impaired endothelial function, detection of H. pylori DNA in atherosclerotic plaques, and participation of certain antigens and antibodies in a cross-reactivity model. There are studies, however, which investigated the relationship between H. pylori and ischemic heart disease with regard to the same parameters and failed to confirm the suggested positive association. Further studies in the direction of interaction between H. pylori and the host's genotype as well as a quest for evidence towards novel risk factors for ischemic heart disease such as oxidative stress, vascular remodeling, vascular calcification, or vasomotor activity, may reveal a field of great interest, thus contributing to the determination of new potential mechanisms.

No associations of Helicobacter pylori infection and gastric atrophy with plasma total homocysteine in Japanese

Recent studies have suggested that Helicobacter pylori (H. pylori) infection might be a risk factor for atherosclerosis. Since the bacterium has not been isolated from atherosclerotic lesions, a direct role in atherogenesis is not plausible. We examined associations of plasma total homocysteine (tHcy) and serum folate, independent risk factors for atherosclerosis, with H. pylori infection and subsequent gastric atrophy among 174 patients (78 males and 96 females) aged 20 to 73 years, who visited an H. pylori eradication clinic of Nagoya University from July 2004 to October 2005. Polymorphism genotyping was conducted for methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) 28-bp tandem repeats by PCR with confronting two-pair primers and PCR, respectively. H. pylori infection and gastric atrophy were not significantly associated with hyperhomocysteinemia (tHcy > or = 12 nmol/ml), when adjusted by sex, age, smoking, alcohol, and genotypes of MTHFR and TS. The adjusted odds ratio of gastric atrophy for low folate level (< or = 4 mg/ml) was 0.21 (95% confidence interval = 0.05-0.78). The associations of tHcy with serum folate and MTHFR genotype were clearly observed in this dataset. The present study demonstrated that folate and MTHFR genotype were the deterministic factors of plasma tHcy, but not H. pylori infection and subsequent gastric atrophy, indicating that even if H. pylori infection influences the risk of atherosclerosis, the influence may not be through the elevation of homocysteine.

Helicobacter pylori eradication lowers serum homocysteine level in patients without gastric atrophy

AIM

To determine whether Helicobacter pylori (H pylori)infection caused hyperhomocysteinemia by altering serum vitamin B(12), serum folate and erythrocyte folate levels and whether eradication of this organism decreased serum homocysteine level.

METHODS

The study involved 73 dyspeptic H pylori-positive patients, none of them had gastric mucosal atrophy based on rapid urease test and histology. Out of 73 patients, 41 (56.2%) showed a successful eradication of H pylori 4 wk after the end of treatment. In these 41 patients, fasting serum vitamin B(12), folate and homocysteine levels, and erythrocyte folate levels before and 4 wk after H pylori eradication therapy were compared.

RESULTS

The group with a successful eradication of H pylori had significantly higher serum vitamin B(12) and erythrocyte folate levels in the post-treatment period compared to those in pre-treatment period (210+/-97 pg/mL vs 237+/-94 pg/mL, P<0.001 and 442+/-212 ng/mL vs 539+/-304 ng/mL, P = 0.024, respectively), but showed no significant change in serum folate levels (5.6+/-2.6 ng/mL vs 6.0+/-2.4 ng/mL, P = 0.341). Also, the serum homocysteine levels in this group were significantly lower after therapy (13.1+/-5.2 micromol/L vs 11.9+/-6.2 micromol /L, P = 0.002). Regression analysis showed that serum homocysteine level was positively correlated with age (P = 0.01) and negatively with serum folate level before therapy (P = 0.003).

CONCLUSION

Eradication of H pylori decreases serum homocysteine even in patients who do not exhibit gastric mucosal atrophy. It appears that the level of homocysteine in serum is related to a complex interaction among serum vitamin B(12), serum folate and erythrocyte folate levels.

Association of Helicobacter pylori infection with systemic inflammation and endothelial dysfunction in healthy male subjects

OBJECTIVES

The goal of the present study was to determine whether seropositivity to Helicobacter pylori (HP), Chlamydia pneumoniae (CP), and cytomegalovirus (CMV) is associated with systemic inflammation and endothelial dysfunction in healthy male subjects.

BACKGROUND

Chronic infection with certain bacteria and viruses may play an important role in inflammation as the pathogenesis of atherosclerosis.

METHODS

The serum levels of immunoglobulin G antibodies to HP, CP, CMV, high-sensitivity C-reactive protein, soluble intercellular adhesion molecule-1, and soluble vascular cell adhesion molecule-1 were determined in 81 healthy Japanese men (40 +/- 10 years of age). High-frequency ultrasonographic imaging of the brachial artery was used to study endothelium-dependent (flow-mediated vasodilation) and endothelium-independent (nitroglycerin-induced) vasodilation.

RESULTS

Prevalences of seropositive antibodies to HP, CP, and CMV were 67.9%, 61.7%, and 56.8%, respectively. Infection with HP, CP, or CMV had no relationship with age, blood pressure, or level of serum glucose, lipid, or soluble vascular cell adhesion molecule-1. The levels of C-reactive protein and soluble intercellular adhesion molecule-1 were significantly higher, and flow-mediated vasodilation was significantly lower in subjects with seropositive antibodies to HP than in subjects with seronegative antibodies to HP. Endothelium-independent vasodilation was similar in both groups.

CONCLUSIONS

Chronic infection with HP may be involved in the development of the atherosclerosis via endothelial dysfunction and systemic and vascular inflammation.

Persistent infection and vascular disease: a systematic review

More than 150 epidemiological or clinical studies have reported on associations between vascular disease and the presence of certain persistent bacterial and viral agents, or of clinical conditions (e.g., periodontal disease) that are associated with persistent infection. This article provides a review of such studies, particularly in relation to Helicobacter pylori, Chlamydia pneumoniae, dental disease and cytomegalovirus (CMV), as well as references to possible mechanisms. The association between coronary heart disease and H. pylori or between heart disease and dental disease may be accounted for by residual confounding. Although markers of C. pneumoniae infection are around twenty times more common in atherosclerotic plaques than in disease-free blood vessels, the sequence of infection and disease is uncertain. For CMV, a limited number of patients with classic atherosclerotic coronary heart disease have been investigated in seroepidemiological studies. For all such agents, better and larger seroepidemiological and pathology-based studies are needed to resolve these uncertainties, as well as - at some stage - large-scale, randomised intervention studies.

Review article: is there a link between micronutrient malnutrition and Helicobacter pylori infection?

Helicobacter pylori causes a chronic gastric infection, which is usually life-long. Many epidemiological studies have shown that this is probably one of the most common bacterial infections throughout the world involving 30% of the population living in developed countries and up to 80-90% of the population in developing regions. Concomitantly, developing regions also have high prevalence of micronutrient malnutrition. In the last few years, some studies have suggested that H. pylori infection may affect the homeostasis of different micronutrients including iron, vitamin B12, folic acid, alpha-tocopherol, vitamin C and beta-carotene. In this article, we discuss the current scientific information of the effect that H. pylori infection may produce on micronutrient malnutrition.

Helicobacter pylori and Alzheimer's disease: a possible link

BACKGROUND: Although serological findings indicate the presence of a relationship between Helicobacter pylori (HP) and vascular disease, no data have been reported about a possible association of HP with dementia. The aim of the present study was to determine whether chronic HP infection might play a role in Alzheimer's disease (AD). METHODS: Plasma homocysteine level, serum folate and vitamin B(12) concentrations, plasma pyridoxal phosphate level, IgG and IgA antibodies to HP, and C-reactive protein (CRP) were determined in 30 AD patients, 30 patients affected by vascular dementia (VaD), and 30 control subjects. All patients and control subjects were matched for age, educational level, and nutritional and socioeconomic status. None of the subjects had a history of chronic gastritis, peptic ulcer, gastric cancer, or major abdominal surgery. RESULTS: HP-IgG level was significantly increased in VaD patients as compared to controls and AD patients, while AD patients had HP-IgG levels higher than those of normal controls. HP-IgA levels were equally increased in both VaD and AD patients. CRP was higher in AD patients than in VaD patients and controls, although CRP levels in VaD patients were also significantly increased. CONCLUSIONS: The present study found an association between HP infection and AD. The question remains as to whether this association is due to the ubiquity of HP, or whether it contributes to the neuroinflammatory process in AD. The relationship between HP and AD, if confirmed by additional studies with a greater number of patients, may have important clinical and therapeutic implications.

Increased thrombin generation and circulating levels of tumour necrosis factor-alpha in patients with chronic Helicobacter pylori-positive gastritis

BACKGROUND

Conflicting data have been reported concerning the relationship between Helicobacter pylori infection and coronary heart disease.

AIM

To evaluate clotting system activation and plasma levels of tumour necrosis factor-alpha, a procoagulant cytokine, in patients with H. pylori-positive and -negative gastritis.

METHODS

Three groups of patients were identified: 38 with H. pylori-positive gastritis, 18 with H. pylori-negative gastritis, and 40 H. pylori-negative controls with normal gastric mucosa. Plasma levels of prothrombin fragment 1 + 2 (F1 + 2) and tumour necrosis factor-alpha were assayed. Patients were also controlled after 2 and 6 months following standard H. pylori eradication treatment.

RESULTS

At baseline, fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients were significantly higher than those in H. pylori-negative patients with gastritis (P < 0.05 and P < 0.01, respectively). After H. pylori eradication, fragment 1 + 2 and tumour necrosis factor-alpha levels showed a significant decrease at 2 months (P = 0.03 and P = 0.02, respectively) and a further reduction at 6 months, reaching levels observed in H. pylori-negative patients and controls.

CONCLUSIONS

The increase thrombin generation rate and the correlation of plasma fragment 1 + 2 and tumour necrosis factor-alpha levels in H. pylori-positive patients suggest a role for inflammation in mediating the relationship between H. pylori infection and activation of the clotting system.

Atrophic gastritis as a cause of hyperhomocysteinaemia

BACKGROUND

Hyperhomocysteinaemia is an independent risk factor for atherosclerosis. It is often related to low levels of vitamin B12 and/or folate, enzymatic co-factors of methionine metabolism. Atrophic gastritis, often caused by Helicobacter pylori infection, may impair vitamin absorption.

AIM

To assess whether the presence of atrophic gastritis is associated with hyperhomocysteinaemia via deficiency of its vitamin co-factors.

METHODS

Thirty-one patients with atrophic gastritis were recruited. The control group consisted of 28 patients with non-atrophic gastritis, matched with patients for sex, age and body mass index. The presence and degree of gastric atrophy were assessed by histology. H. pylori infection was assessed by histology/serology. Blood samples were collected for the measurement of homocysteine, vitamin B12 and folates.

RESULTS

Multiple logistic regression analysis showed that atrophic gastritis (odds ratio, 5.3; 95% confidence interval, 1.23-25.26; chi2=5.2; P=0.01) and low vitamin B12 (odds ratio, 3.7; 95% confidence interval, 1.03-22.08; chi2=3.6; P<0.05) were both predictors of hyperhomocysteinaemia. None of the other variables considered in the analysis, including H. pylori status, showed a significant association with hyperhomocysteinaemia.

CONCLUSIONS

The present study suggests that atrophic gastritis, rather than H. pylori infection per se, may be a contributing factor to hyperhomocysteinaemia, possibly via vitamin B12 malabsorption.

Hepatitis A IgG seropositivity and coronary atherosclerosis assessed by angiography

BACKGROUND

Infectious agents, in particular intracellular pathogens that can establish long-term, persistent infection, may play an important role in atherogenesis. We tested the hypothesis that hepatitis A virus (HAV) could be associated with significant coronary artery disease.

METHODS

The possible association between HAV infection and angiographically proven coronary artery disease (CAD) was studied. Blood from 218 patients undergoing coronary angiography was tested for serum IgG antibodies to HAV.

RESULTS

Of the 218 patients, 178 (81.7%) had anti-HAV IgG antibodies. CAD prevalence was 66.3% in HAV seropositive and 57.5% in HAV seronegative patients (P=0.385). In contrast, the number of infectious pathogens to which an individual has been exposed correlates with CAD. Four or more of the six seromarkers tested for particular infections (HAV, Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, influenza type A and type B) were positive in 48.8% of patients with CAD and in 31.2% of patients in patients without CAD (P=0.02).

CONCLUSIONS

This analysis demonstrated that HAV seropositivity is not a predictor of risk for CAD. HAV infection, therefore, seems not to be associated with CAD. The number of infectious agents to which an individual has been exposed ('infectious burden') correlates with CAD.

Is periodontitis associated with an increased risk of coronary heart disease and preterm and/or low birth weight births?

The objective of this systematic review was to determine whether periodontal disease is associated with an increased risk for coronary heart disease (CHD) and preterm and/or low birth weight deliveries (PLBW). A literature search was performed to identify cross-sectional, case-control, and cohort studies as well as clinical trials addressing different aspects of periodontal disease (clinical, microbial, immunological) and clinical outcomes of CHD or PLBW. The periodontitis-CHD association was evaluated in eight cohort, four case-control- and four cross-sectional studies. Meta-analysis was not performed due to the extensive heterogeneity of the studies, particularly with regard to periodontitis measures, which varied from full mouth probing assessments to questionnaires. Percentage-wise, 50% of the cohort studies (4/8), 75% of the case-control studies (3/4) and 50% of the cross-sectional studies (2/4) reported a significant association between clinical measures of periodontitis and CHD (excess risk ranged from 0 to 3.3-fold). The periodontitis-PLBW association was evaluated in one cohort and two case-control studies. The cohort study as well as one of the two case-control studies reported a significant association between periodontitis and PLBW (odds ratios 4.4-7.9). From two additional case-control studies microbiological data could be extracted. Bacteroides forsythus was found to be associated with PLBW in both studies. In conclusion, the evidence linking periodontitis with an increased risk for CHD and PLBW is limited. There is a clear need for new, well designed observational and intervention studies to confirm the thus far observed associations, explore the validity of the associations in diverse populations, establish whether they are causal in nature and determine potential benefits of periodontal intervention in reducing the risk for these conditions.

Influenza A and B IgG seropositivity and coronary atherosclerosis assessed by angiography

Infectious agents, in particular intracellular pathogens that can establish long-term, persistent seropositivity, may play an important role in atherogenesis. The possible association between influenza type A and B infection and angiographically proven coronary artery disease (CAD) and the effect of the aggregate pathogen burden on CAD was studied by testing blood from 218 patients undergoing coronary angiography for serum IgG antibodies to influenza A and B, and for antibodies to four other pathogens (hepatitis A, Chlamydia pneumoniae, Helicobacter pylori, and cytomegalovirus). This analysis demonstrates that although influenza (A and B) seropositivity represents no predictor of risk for CAD, infectious burden is independently associated with coronary atherosclerosis.

The association of seropositivity to Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus with risk of cardiovascular disease: a prospective study

OBJECTIVES

We sought to determine whether seropositivity to Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV) is an independent predictor of incident cardiovascular disease.

BACKGROUND

Recent reports have suggested that infections may contribute to risk of cardiovascular disease. However, prospective studies of these associations in a free-living population are lacking.

METHODS

We measured serum H. pylori IgG, C. pneumoniae IgG and IgA, and CMV IgG levels in Framingham Heart Study cohort participants. Blood samples were drawn during the 16th biennial examination cycle (1979 to 1982) from 1,187 participants free of cardiovascular disease (mean age 69 years) and stored at -20 degrees C. A pooled primary end point of myocardial infarction, atherothrombotic stroke, and coronary heart disease deaths was studied in relation to serology. Using a Cox model, hazard ratios (HR) and 95% confidence intervals (CI) were calculated, adjusting for age, gender, and established risk factors.

RESULTS

Seropositivity to H. pylori IgG, C. pneumoniae IgG, C. pneumoniae IgA, and CMV IgG was 60%, 45%, 11%, and 69%, respectively. During 10 years of follow-up, incident cardiovascular disease occurred in 199 participants (16.8%). In age- and gender-adjusted models, H. pylori IgG (HR 1.09, 95% CI 0.81 to 1.46), C. pneumoniae IgG (HR 0.91, 95% CI 0.68 to 1.20), C. pneumoniae IgA (HR 0.65, 95% CI 0.39 to 1.07), and CMV IgG (HR 0.84, 95% CI 0.62 to 1.12) were not associated with incident cardiovascular disease. These associations were further attenuated after adjustment for risk factors including body mass index, total and high-density lipoprotein cholesterol, diabetes mellitus, smoking, and hypertension. These estimates did not change for the individual components of cardiovascular disease, and seropositivity to more than one organism did not alter these risk estimates substantially.

CONCLUSIONS

In this elderly cohort, chronic H. pylori, C. pneumoniae, and CMV infections, as evidenced by seropositivity, were not associated with increased risk for cardiovascular disease. Additional studies are needed to determine the relations of chronic infections to cardiovascular disease risk in younger persons.

Greater pathogen burden but not elevated C-reactive protein increases the risk of clinical restenosis after percutaneous coronary intervention

BACKGROUND

Restenosis after percutaneous coronary intervention (PCI) constitutes a serious complication in the treatment of cardiovascular disease, but known risk factors do not fully account for the observed restenosis risk. Preliminary studies of infection or inflammation in restenosis report varied results. We tested whether C-reactive protein (CRP) or pathogen burden (seropositivity to 0, 1, 2, or 3 pathogens, of Chlamydia pneumoniae [Cpn], cytomegalovirus [CMV], or Helicobacter pylori [Hpy]) predict clinical restenosis after percutaneous coronary intervention (PCI).

METHODS

Blood samples were collected from 415 patients undergoing PCI, and levels of plasma CRP and antibodies to Cpn, CMV, and Hpy were measured. The patient's medical history, demographics, and procedural data were recorded. Patient end points were determined for as long as 6 months as a means of evaluating the incidence of clinical restenosis and major adverse cardiac events.

RESULTS

The average patient age was 62 years, and 80% of patients were male. Fifty-eight patients (14%) experienced clinical restenosis, whereas 17 patients (4%) died or had an acute myocardial infarction. After adjusting for 19 possible predictors, we found the pathogen burden (P-trend =.04, adjusted odds ratio [OR] 1.5 per number of pathogens) and minimum luminal diameter (P =.003, OR 1.8 per mm decrease) to be significant predictors of clinical restenosis. Male sex was a nonsignificant predictor of restenosis (P =.06, OR 2.2), but CRP was not significant after adjustment (P-trend =.10, OR 0.73 per tertile).

CONCLUSION

Pathogen burden was associated with clinical coronary restenosis, an association that deserves further exploration and evaluation. CRP, a marker of inflammation, was not associated with an increased risk of restenosis.

The relation between Helicobacter pylori and atherosclerosis cannot be explained by a high homocysteine concentration

BACKGROUND

Recent studies have suggested that a chronic infection with Helicobacter pylori might be an independent risk factor for atherosclerosis. However, a direct role in atherogenesis is not plausible, since the bacterium has not been isolated from atherosclerotic lesions. An indirect mechanism that could link H. pylori with atherosclerosis might be through an increase in plasma homocysteine concentration caused by deficiencies of vitamin B12 and folate in plasma.

MATERIALS AND METHODS

In 150 female patients with peripheral arterial disease (PAD) and in 412 healthy control women from a nation-wide population-based case-control study, blood samples were collected to determine the antibody titre against H. pylori and to measure plasma homocysteine, folate and vitamin B12 levels. First, the odds ratio for PAD in women with a positive antibody titre against H. pylori was calculated and adjusted for homocysteine level. Secondly, mean concentrations of vitamin B12, folate and homocysteine were compared in healthy controls with a positive or negative antibody titre against H. pylori. Thirdly, the relation between H. pylori and PAD in individuals with a normal or high homocysteine level was investigated.

RESULTS

A positive immunoglobulin G antibody titre against H. pylori was found in 42% of the PAD patients and in 27% of the controls. The age- and socio-economic-status (SES) adjusted odds ratio for PAD was 1.5 (95%CI; 1.0-2.2). Additional adjustment for homocysteine plasma concentration did not essentially change the odds ratio. Secondly, among the healthy controls, the homocysteine plasma concentration did not depend on the immunoglobulin G titre, neither did the folate plasma concentration. The concentration of vitamin B12 was slightly higher in women with a positive titre. Thirdly, H. pylori infection was a risk factor for PAD in subjects with a normal homocysteine concentration [OR 2.0 (95%CI 1.3-3.1)].

CONCLUSIONS

This study shows a relationship between a positive immunoglobulin G antibody titre against H. pylori and PAD in young women. Moreover, this study does not support the hypothesis that H. pylori infection is related to atherosclerosis via an increase in plasma homocysteine concentration.

Homocysteine and methylenetetrahydrofolate reductase genotype: association with risk of coronary heart disease and relation to inflammatory, hemostatic, and lipid parameters

AIM

It has been suggested that homocysteine (tHcy) levels and methylenetetrahydrofolate reductase (MTHFR) genotype are primary risk factors for coronary heart disease (CHD). We performed a case-control study to investigate whether tHcy levels and MTHFR genotype (677 C-->T mutation and 1298 A-->C mutation) are associated with CHD under special consideration of the possibility for confounding.

METHODS

German speaking patients aged 40-68 years who underwent coronary angiography at the University of Ulm between April 1996 and November 1997 and who had at least one coronary stenosis greater than 50% were included in the study. Controls were sampled from voluntary blood donors and were matched for sex and age. tHcy levels were measured by high performance liquid chromatography and MTHFR genotype by means of polymerase chain reaction. In addition, C-reactive protein, fibrinogen, plasma viscosity, leukocytes, HDL-cholesterol and Lp(a) were determined.

RESULTS

Overall, 312 patients and 479 controls were enrolled in the study (response in patients 78%, in controls 84%). Mean tHcy value was 9.43 micromol/l in CHD patients and 8.91 micromol/l in controls (P=0.145). Prevalence of 677TT-polymorphism was 9.9% in patients and 10.4% in controls (P=0.295). Prevalence of 1298CC-polymorphism was 9.7% in patients and 13.8% in controls (P=0.346). There was a clear association of tHcy-values, but not of 677TT- or 1298CC-genotype with conventional CHD risk factors. After adjustment for these risk factors no increased risk for CHD could be associated with increased tHcy-values, with 677TT or 1298CC-genotype, or with their combination. Also no statistically significant relationships of these parameters to inflammatory, rheologic or hemostatic parameters or lipids were detectable.

CONCLUSION

These results do not confirm an independent relationship of tHcy values and MTHFR genotype with risk of CHD in the population studied.

Relation of Helicobacter pylori infection to plasma vitamin B12, folic acid, and homocysteine levels in patients who underwent diagnostic coronary arteriography

OBJECTIVE

The aim of this study was to test the hypothesis that chronic atrophic gastritis induced by Helicobacter pylori (H. pylori) causes malabsorption of vitamin B12 and folate in food, leading ultimately to an increase in circulating homocysteine levels.

METHODS

We performed endoscopy with stomach biopsy and measured fasting plasma homocysteine, vitamin B12, and folate levels in 93 patients who underwent diagnostic coronary arteriography. The patients were divided into two groups according to the presence (n = 57) or absence (n = 36) of H. pylori infection. Positive H. pylori infection was defined as positive H. pylori histology of biopsy specimens from the stomach. The extent of atrophic gastritis was endoscopically graded from 0 to 6.

RESULTS

There were no differences in age, sex, or traditional coronary risk factors between the two groups. Atrophy scores of the stomach were greater in patients with H. pylori infection than in patients without (3.9 +/- 1.4 vs 2.2 +/- 1.8, p < 0.0001). Patients with H. pylori infection had lower levels of vitamin B12 (630 +/- 222 vs 747 +/- 259 pg/ml, p = 0.02) and folate (6.2 +/- 2.1 vs 7.4 +/- 2.8, p = 0.046), as well as higher levels of homocysteine (11 +/- 4.9 vs 8.3 +/- 2.1 nmol/ml, p = 0.01), than did patients without H. pylori infection. Plasma homocysteine levels correlated inversely with plasma vitamin B12 and folate levels and positively with atrophic scores.

CONCLUSIONS

This study suggests that H. pylori-induced chronic atrophic gastritis decreases plasma vitamin B12 and folic acid levels, thereby increasing homocysteine levels. However, this effect does not seem to be strong.

Correlation between Helicobacter pylori infection, gastric inflammation and serum homocysteine concentration

BACKGROUND

Epidemiological studies have suggested a link between chronic Helicobacter pylori infection and ischemic heart disease but the underlying mechanism remains elusive. We hypothesized that H. pylori-associated chronic gastritis causes impairment of absorption of vitamin cofactors that are essential in the metabolism of homocysteine and results in hyperhomocysteinemia.

MATERIALS AND METHODS

Forty-nine dyspeptic patients were studied. H. pylori infection was defined by rapid urease test and histology. Fasting serum homocysteine level, which was measured by a validated commercial fluorescence polarization immunoassay, was correlated with H. pylori infection statuses and gastric histology. H. pylori-infected patients were followed up for 24 weeks post eradication for changes in serum homocysteine concentration.

RESULTS

Univariate analyses showed that serum homocysteine level correlated with increasing age (p <.001), male sex (p =.003) and smoking habit (p =.025). There was no significant difference in serum homocysteine levels between H. pylori infected and uninfected subjects (median 10.5 vs. 10.2 micromol/l). After successful eradication of the bacterium, there was no significant reduction in homocysteine level. Moreover, there was no correlation between homocysteine level and gastric histology including H. pylori density, activity and inflammation scores, presence of atrophy or intestinal metaplasia.

CONCLUSIONS

The postulated link between H. pylori infection and ischemic heart disease, if it actually exists, is unlikely to be mediated through hyperhomocysteinemia.

Successful eradication of Helicobacter pylori as determined by ((13))C-urea breath test does not alter fibrinogen and acute phase response markers

In this study we examined in 100 patients testing positive for Helicobacter pylori infection whether successful eradication therapy with pantoprazole, clarithromycin, and metronidazole alters fibrinogen and other acute phase response markers. Of 100 patients, only 11 showed a fibrinogen level above 300 mg/dL. Successful eradication proven by the 13C-urea breath test does not alter acute phase response markers. These findings indicate that Helicobacter pylori infection is unlikely to affect atherosclerosis unfavourably via acute phase response.

Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus: chronic infections and coronary heart disease

We conducted a MEDLINE search of the English-language literature from 1966-1999 on the association of chronic infections with Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV) with coronary heart disease (CHD); additional literature was retrieved from references of selected articles. All human studies were included. Abstracts were excluded because of limited data. Chronic infections in CHD are speculated to be due to serum antibody concentrations of one or more of the three organisms. Data for H. pylori and CMV are difficult to interpret due to the confounding factor of childhood poverty and studies conducted in transplant recipients, respectively. Chlamydia pneumoniae data appear stronger with elevated IgG antibody titers (> or = 64) as a risk factor. Larger prospective studies are warranted to determine an association with CHD before universal prophylaxis or treatment of these chronic infections.

Treatment of Helicobacter pylori and Chlamydia pneumoniae infections decreases fibrinogen plasma level in patients with ischemic heart disease

BACKGROUND

Chronic Chlamydia pneumoniae and Helicobacter pylori infections could be a risk factor for ischemic heart disease (IHD), possibly by increasing fibrinogen levels. The aim of our study was to evaluate changes in fibrinogen level in patients with IHD and H pylori and/or C pneumoniae positivity randomly assigned to antibiotic treatment.

METHODS AND RESULTS

Eighty-four patients with chronic IHD, H pylori and/or C pneumoniae antibodies, and normal acute-phase reactants were randomly assigned to treatment or no treatment. Treatment consisted of omeprazole, clarithromycin, and tinidazole in H pylori-positive patients and clarithromycin alone in C pneumoniae-positive patients. The effect of treatment and other baseline variables on fibrinogen levels, determined at 6 months, was evaluated by multivariate analysis. Treatment significantly reduced fibrinogen level at 6 months in the overall study population and in the groups of patients divided according to H pylori or C pneumoniae positivity. In the 43 treated patients, mean (+/-SD) basal fibrinogen was 3.65+/-0.58 g/L, and mean final fibrinogen was 3. 09+/-0.52 g/dL (P<0.001), whereas in the 41 untreated patients, mean basal and final fibrinogen levels were 3.45+/-0.70 and 3.61+/-0.71 g/L, respectively. The largest decrease was observed in patients with both infections. Fibrinogen changes were also significantly and negatively correlated with age.

CONCLUSIONS

Our data suggest that a short, safe, and effective course of antibiotic therapy might be suggested as a means of interacting with an "emerging" risk factor.

Relation of Helicobacter pylori infection to 13-year mortality and incident ischemic heart disease in the caerphilly prospective heart disease study

BACKGROUND

Associations have been suggested between Helicobacter pylori seropositivity, cardiovascular risk factors, and ischemic heart disease (IHD). The effect of this common infection on mortality is uncertain.

METHODS AND RESULTS

Plasma specimens collected during 1979 to 1983 from 1796 men in Caerphilly, South Wales, were analyzed for IgG antibodies to H pylori. Cause of death and occurrence of incident IHD events were ascertained over an average of 13.7 years from death certificates, hospital records, and ECG changes at 5-yearly follow-up examinations. Seventy percent of men were seropositive. The prevalence of IHD at entry was similar in men with and without H pylori antibodies (odds ratio [OR], 1.10; 95% CI, 0.87 to 1.40). Seropositivity was significantly (P<0.05) associated with poorer socioeconomic status currently and in childhood, shorter stature, and poorer ventilatory function at entry but not with age, smoking, body mass index, blood pressure, total cholesterol, HDL cholesterol, LDL cholesterol, fibrinogen, plasma viscosity, or heat shock protein antibodies. Thirteen-year incidence of IHD was not significantly associated with H pylori (OR, 1.05; 95% CI, 0.80 to 1.39), but there was a stronger relationship with all-cause mortality (OR, 1.46; 95% CI, 1.12 to 1.92) and fatal IHD (OR, 1.54; 95% CI, 1.03 to 2.30). After adjustment for cardiovascular risk factors and both adult and childhood socioeconomic status, ORs were slightly reduced and lost statistical significance (OR=1.32 [95% CI, 0.99 to 1.78] for all-cause mortality and OR=1.52 [95% CI, 0.99 to 2.34] for fatal IHD).

CONCLUSIONS

H pylori infection is unlikely to be as strong a risk factor for IHD as some previous studies have suggested, but its relationship to mortality, including fatal IHD, deserves further investigation. The mechanism underlying these associations is unlikely to involve hypertension, circulating lipid profile, fibrinogen, or cross-reacting antibodies to bacterial heat shock proteins.

Helicobacter pylori seropositivity and coronary heart disease incidence. Atherosclerosis Risk In Communities (ARIC) Study Investigators

BACKGROUND

Several epidemiological and clinical reports have suggested seropositivity for Helicobacter pylori may be a risk factor for coronary heart disease. However, there has been no prospective study of this association involving an ethnically diverse sample of middle-aged men and women.

METHODS AND RESULTS

Using a prospective, case-cohort design, we determined H pylori seropositivity in relation to coronary heart disease incidence over a median follow-up period of 3.3 years among middle-aged men and women. There were 217 incident coronary heart disease cases and a cohort sample of 498. We determined H pylori antibody status by measuring IgG antibody to the high-molecular-weight cell-associated proteins of H pylori using a sensitive and specific ELISA. The prevalence of H pylori seropositivity was higher in blacks than whites, in those with less than high school education, in those with lower plasma pyridoxal 5'-phosphate and higher homocyst(e)ine concentrations, in those who did not use vitamin supplements, in those with higher fibrinogen levels, and in those seropositive for cytomegalovirus and herpes simplex type I (all P<0.05). The age-, sex-, race-, and field center-adjusted hazard ratio of coronary heart disease for H pylori seropositivity was 1.03 (95% CI=0.68 to 1.57). After adjustment for other risk factors, including fibrinogen, cytomegalovirus seropositivity, and herpes simplex type I seropositivity, the hazard ratio was 0.85 (95% CI=0.43 to 1.69). H pylori seropositivity also was not associated with increased mean intima-media thickness of the carotid artery, a measure of subclinical atherosclerosis.

CONCLUSIONS

H pylori infection is probably not an important contributor to clinical coronary heart disease events.

Helicobacter pylori infection: a risk factor for ischaemic cerebrovascular disease and carotid atheroma

OBJECTIVES

Chronic Helicobacter pylori infection has been associated with ischaemic heart disease although the mechanism by which it mediates this effect remains unclear. The objective was to determine whether it is also a risk factor for ischaemic cerebrovascular disease

METHODS

A total of 238 patients and 119 controls were studied. Patients were characterised into stroke subtypes based on pathogenic mechanisms and carotid atheroma load was estimated using duplex ultrasound. H pylori seropositivity was determined on serum samples.

RESULTS

H pylori seropositivity was more common in cases (58.8% v 44.5%, p=0.01). The odds ratio for cerebrovascular disease associated with seropositivity was 1.78 (95% confidence interval (95% CI) 1.14-2.77), and this remained significant after controlling for other risk factors including socioeconomic status (1.63 (95% CI 1.02-2.60). H pylori seropositivity was associated with large vessel disease (odds ratio 2.58 (95% CI 1.44-4.63), p=0.001) and lacunar stroke (odds ratio 2.21 (95% CI 1.12-4.38), p=0.02) but not stroke due to cardioembolism or unknown aetiology (odds ratio 1.16 (95% CI 0.66-2.02), p=0.5). Mean (SD) carotid stenosis was greater in patients seropositive for H pylori (37.3 (29.7) v 27.9 (26.2)%, p=0.01). There was no difference in the prevalence of seropositivity between patients with stroke and transient ischaemic attack (59.6% v 58.6%, p=0.9)

CONCLUSION

Chronic H pylori infection is an independent risk factor for ischaemic cerebrovascular disease and may act, at least in part, by increasing atherosclerosis.

Coronary artery disease associated with Helicobacter pylori infection is at least partially due to inadequate folate status

The numerous effects of Helicobacter pylori have attracted significant attention. The most consistent and well appreciated effect is peptic ulcer. However, gastric cancer, growth retardation and coronary artery disease are among other sequelae of this chronic infection. This discussion describes a potential relationship among risk of coronary artery disease, the changes caused in gastric juice by H. pylori-induced gastritis, and the bioavailability of folates. Reduced folate absorption can occur in an environment of increased gastric juice pH and/or decreased ascorbic acid. This can, relatively rapidly, result in inadequate folate status which inhibits the methionine synthase reaction. Reduced methionine synthase activity increases the blood concentration of homocyst(e)ine which is known to be toxic to endothelial cells, and an independent risk factor for atherosclerosis. Decreased folate bioavailability may help explain the increased risk of coronary artery disease which has been observed in populations infected with H. pylori. It would also be consistent with the increased occurrence of this association in lower socioeconomic groups, and may also help explain the low incidence of gastric cancer in Africa, despite the high prevalence of H. pylori infection.

Chronic infections and coronary heart disease: is there a link?

A large number of studies have reported on associations of human coronary heart disease (CHD) and certain persistent bacterial and viral infections. We review the epidemiological and clinical evidence on CHD and Helicobacter pylori, Chlamydia pneumoniae, and cytomegalovirus (CMV), as well as possible mechanisms. The association between CHD and H pylori may be accounted for by residual confounding from risk factors. Although the association between C pneumoniae and CHD is stronger, the sequence of infection and disease is uncertain. As regards CMV, a limited number of patients with classic atherosclerotic coronary artery disease have been studied. Further studies are needed to resolve these uncertainties.