Helicobacter pylori infection and immune thrombocytopenic purpura: an update

Discussion on the common controversies of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori ( H. pylori ) can persistently colonize on the gastric mucosa after infection and cause gastritis, atrophy, metaplasia, and even gastric cancer (GC).

METHODS

Therefore, the detection and eradication of H. pylori are the prerequisite.

RESULTS

Clinically, there are some controversial issues, such as why H. pylori infection is persistent, why it translocases along with the lesser curvature of the stomach, why there is oxyntic antralization, what the immunological characteristic of gastric chronic inflammation caused by H. pylori is, whether H. pylori infection is associated with extra-gastric diseases, whether chronic atrophic gastritis (CAG) is reversible, and what the potential problems are after H. pylori eradication. What are the possible answers?

CONCLUSION

In the review, we will discuss these issues from the attachment to eradication in detail.

Helicobacter pylori in Human Stomach: The Inconsistencies in Clinical Outcomes and the Probable Causes

Pathogenic potentials of the gastric pathogen, Helicobacter pylori, have been proposed, evaluated, and confirmed by many laboratories for nearly 4 decades since its serendipitous discovery in 1983 by Barry James Marshall and John Robin Warren. Helicobacter pylori is the first bacterium to be categorized as a definite carcinogen by the International Agency for Research on Cancer (IARC) of the World Health Organization (WHO). Half of the world’s population carries H. pylori, which may be responsible for severe gastric diseases like peptic ulcer and gastric cancer. These two gastric diseases take more than a million lives every year. However, the role of H. pylori as sole pathogen in gastric diseases is heavily debated and remained controversial. It is still not convincingly understood, why most (80–90%) H. pylori infected individuals remain asymptomatic, while some (10–20%) develop such severe gastric diseases. Moreover, several reports indicated that colonization of H. pylori has positive and negative associations with several other gastrointestinal (GI) and non-GI diseases. In this review, we have discussed the state of the art knowledge on “H. pylori factors” and several “other factors,” which have been claimed to have links with severe gastric and duodenal diseases. We conclude that H. pylori infection alone does not satisfy the “necessary and sufficient” condition for developing aggressive clinical outcomes. Rather, the cumulative effect of a number of factors like the virulence proteins of H. pylori, local geography and climate, genetic background and immunity of the host, gastric and intestinal microbiota, and dietary habit and history of medicine usage together determine whether the H. pylori infected person will remain asymptomatic or will develop one of the severe gastric diseases.

Expression of Lewis (b) blood group antigen interferes with oral dienogest therapy among women with adenomyosis

Adenomyosis is frequently observed in premenopausal women, and oral dienogest is the recommended treatment to target the underlying pathology and improve the symptoms. This retrospective study investigated the association of Lewis (b) antigen expression with outcomes of dienogest therapy among women with adenomyosis. Records from a total of 342 adenomyosis patients were analysed, who were prescribed with oral dienogest for a maximum of 16 weeks. Expression levels of Lewis (b) antigen were measured to categorize all patients into either Le (b)- and Le(b)+ groups. Treatment outcomes, in terms of uterine volume, menstrual flow, pain symptoms and quality of life, were compared between the two groups. While oral dienogest therapy showed considerable clinical efficacy in both groups of patients, the extent of improvements in treatment outcomes was significantly more pronounced in Le (b)- group than Le (b)+ group, with respect to treatment time, uterine symptoms, menstrual flow, pain symptoms and quality of life. No difference in adverse effects was observed between the two groups. Expression of Lewis (b) blood group antigen interferes with oral dialogist therapy among women with adenomyosis.

Clinical features of Helicobacter pylori antibody-positive junior high school students in Nagano Prefecture, Japan

BACKGROUND

Previously, we conducted an epidemiological study screening for Helicobacter pylori antibody positivity among Japanese junior high school students. In this study, we updated the epidemiological data and assessed the clinical features of H pylori antibody-positive junior high school students.

MATERIALS AND METHODS

We assessed H pylori antibody-positive subjects who were identified between 2012 and 2015 at four junior high schools in Nagano Prefecture, Japan. H pylori infection was confirmed by urea breath test (UBT) or endoscopic examination. Endoscopy was performed after obtaining consent from the subject and their guardians. Eradication therapy consisted of triple therapy with proton pump inhibitor (PPI), amoxicillin (AMPC), and clarithromycin (CAM) or metronidazole (MNZ) for seven days. Eradication of H pylori was confirmed by UBT. We reviewed subjects' characteristics, endoscopic findings, histological findings, eradication regimes, outcomes, and adverse effects.

RESULTS

The overall prevalence of H pylori antibody positivity was 3.2% (42/1298). We assessed thirteen H pylori antibody-positive subjects. Eight subjects had a family history of H pylori infection. Six subjects had abdominal pain, and two subjects had iron deficiency anemia (IDA). Twelve subjects underwent endoscopy; one subject had duodenal ulcer, eleven subjects had antral nodular gastritis, and six subjects showed grade 2 closed type atrophic border according to the Kimura-Takemoto classification. All subjects received eradication therapy; CAM was used in five subjects with CAM susceptibility as well as in three subjects with unknown information on CAM susceptibility, and MNZ was used in five subjects with CAM resistance. Eradication was successful in twelve subjects (one unconfirmed). There were three mild adverse effects (abdominal pain or diarrhea).

CONCLUSIONS

Helicobacter pylori test for junior high school students represents an opportunity to diagnose the peptic ulcer, iron deficiency anemia, and gastric atrophy.

Increase in antibiotic resistant Helicobacter pylori in a University Hospital in Japan

Background

Eradication effectively prevents Helicobacter pylori-associated diseases; however, H. pylori antibiotic resistance has increased throughout Japan and worldwide. This study aimed to assess rates of resistance to antibiotics; amoxicillin, clarithromycin and metronidazole in a University Hospital in Japan.

Materials and methods

H. pylori (208 strains) were isolated from patients at the Okayama University Hospital in Japan. The minimum inhibitory concentrations (MIC) were determined using the mean values of the E-test to determine the antimicrobial susceptibilities of the strains. Sequencing and gene analysis were performed to analyze resistance genes to clarithromycin and amoxicillin.

Results

Rates of amoxicillin, clarithromycin, and metronidazole resistance were 13%, 48%, and 49%, respectively. Genetic analysis indicated that the A2143G point mutation in 23S rDNA is closely associated with the MIC of clarithromycin. The MIC in amoxicillin-resistant strains increased with an increase in the number of PBP1A amino acids mutations.

Conclusion

Genetic analysis for resistant strains is not clinically effective in cases of amoxicillin resistance. Numerous bacteria with already high antibiotic resistance rates have been isolated in large hospitals such as a University Hospital. For effective eradication therapy, MIC measurement should be considered via several methods.

Narrow band imaging and serology in the assessment of premalignant gastric pathology

BACKGROUND

Patient outcomes in gastric adenocarcinoma are poor due to late diagnosis. Detecting and treating at the premalignant stage has the potential to improve this. Helicobacter pylori is also a strong risk factor for this disease.

AIMS

Primary aims were to assess the diagnostic accuracy of magnified narrow band imaging (NBI-Z) endoscopy and serology in detecting normal mucosa, H. pylori gastritis and gastric atrophy. Secondary aims were to compare the diagnostic accuracies of two classification systems using both NBI-Z and white light endoscopy with magnification (WLE-Z) and evaluate the inter-observer agreement.

METHODS

Patients were prospectively recruited. Images of gastric mucosa were stored with histology and serum for IgG H. pylori and Pepsinogen (PG) I/II ELISAs. Blinded expert endoscopists agreed on mucosal pattern. Mucosal images and serological markers were compared with histology. Kappa statistics determined inter-observer variability for randomly allocated images among four experts and four non-experts.

RESULTS

116 patients were prospectively recruited. Diagnostic accuracy of NBI-Z for determining normal gastric mucosa was 0.87(95%CI 0.82-0.92), H. pylori gastritis 0.65(95%CI 0.55-0.75) and gastric atrophy 0.88(95%CI 0.81-0.94). NBI-Z was superior to serology at detecting gastric atrophy: NBI-Z gastric atrophy 0.88(95%CI 0.81-0.94) vs PGI/II ratio < 3 0.74(95%CI 0.62-0.85) p<.0001. Overall NBI-Z was superior to WLE-Z in detecting disease using two validated classifications. Inter-observer agreement was 0.63(95%CI 0.51-0.73).

CONCLUSIONS

NBI-Z accurately detects changes in the GI mucosa which currently depend on histology. NBI-Z is useful in the detection of precancerous conditions, potentially improving patient outcomes with early intervention to prevent gastric cancer.

Helicobacter pylori Eradication in Idiopathic Thrombocytopenic Purpura: A Meta-Analysis of Randomized Trials

Objective

Several recent reviews of published studies have shown that the eradication of H. pylori infection in patients with ITP improved thrombocytopenia in about half of the cases. However, most included studies were observational case series. We performed the first meta-analysis of randomized trials to gain a better insight into the effect of H. pylori eradication in ITP patients.

Methods

A systematic computerized search of the electronic databases including PubMed, EMBASE, Google Scholar, and Cochrane Library (up to December 2017) was conducted.

Results

From six studies, a total of 241 patients (125 in eradication group and 116 in control group) were included in the meta-analysis. Patients in the eradication group showed significantly higher overall platelet response rate than those in the control group (odds ratio = 1.93, 95% confidence interval: 1.01–3.71, P = 0.05). In the subgroup analysis, however, children in the eradication group failed to show statistically better response rate than those in the noneradication group (odds ratio = 1.80, 95% confidence interval: 0.88–3.65, P = 0.11).

Conclusions

This meta-analysis indicates that H. pylori eradication has a significant therapeutic effect in patients with ITP. Considering the intrinsic limits in the design and sample size of the included studies, however, large randomized controlled trials are warranted to validate the therapeutic impact of H. pylori eradication in adults as well as children with ITP.

DEC205 mediates local and systemic immune responses to Helicobacter pylori infection in humans

Helicobacter pylori infections cause gastritis and affect systemic immune responses; however, no direct association between immune cells and stomach bacteria has yet been reported. The present study investigated DEC205-mediated phagocytosis of H. pylori and the role of DEC205-positive macrophages in the human gastric mucosa. DEC205 mediated phagocytosis of H. pylori was detected immunocytochemically in PMA-stimulated macrophages differentiated from NOMO1 cells. Expression of DEC205 mRNA in peripheral blood mononuclear cells (PBMCs) from H. pylori-infected patients was analyzed following stimulation with H. pylori cell lysate. We found that anti-DEC205 antibodies inhibited phagocytosis of H. pylori. The number of cells double-positive for DEC205 and CD14 in human gastric mucosa was higher in H. pylori-infected patients. DEC205-positive macrophages invaded the extracellular space between epithelial cells within gastric pits. In addition, DEC205 mRNA expression was upregulated in human PBMCs stimulated with H. pylori lysate. These findings suggest DEC205-expressing macrophages are important for recognition of H. pylori in human gastric mucosa, which affects systemic immunity.

Does Helicobacter pylori eradication play a role in immune thrombocytopenia?

Helicobacter pylori infection has been implicated as trigger or disease modifier in immune thrombocytopenia (ITP). So, eradication treatment for this agent could have clinical benefits. Searching in Epistemonikos database, which is maintained by screening 30 databases, we identified four systematic reviews comprising 40 studies addressing the question of this article overall, including one randomized controlled trial. We combined the evidence using meta-analysis and generated a summary of findings following the GRADE approach. We concluded Helicobacter eradication might decrease risk of bleeding in patients with immune thrombocytopenia but the certainty of the evidence is low.

Helicobacter pylori Eradication in Patients with Immune Thrombocytopenic Purpura: A Review and the Role of Biogeography

Idiopathic thrombocytopenic purpura (ITP) is typically a diagnosis of exclusion, assigned by clinicians after ruling out other identifiable etiologies. Since a report by Gasbarrini et al. in 1998, an accumulating body of evidence has proposed a pathophysiological link between ITP and chronic Helicobacter pylori (H. pylori) infection. Clinical reports have described a spontaneous resolution of ITP symptoms in about 50% of chronic ITP patients following empirical treatment of H. pylori infection, but response appears to be geography dependent. Studies have also documented that ITP patients in East Asian countries are more likely to express positive antibody titers against H. pylori-specific cytotoxic-associated gene A (CagA), a virulence factor that is associated with an increased risk for gastric diseases including carcinoma. While a definitive mechanism by which H. pylori may induce thrombocytopenia remains elusive, proposed pathways include molecular mimicry of CagA by host autoantibodies against platelet surface glycoproteins, as well as perturbations in the phagocytic activity of monocytes. Traditional treatments of ITP have been largely empirical, involving the use of immunosuppressive agents and immunoglobulin therapy. However, based on the findings of clinical reports emerging over the past 20 years, health organizations around the world increasingly suggest the detection and eradication of H. pylori as a treatment for ITP. Elucidating the exact molecular mechanisms of platelet activation in H. pylori-positive ITP patients, while considering biogeographical differences in response rates, could offer insight into how best to use clinical H. pylori eradication to treat ITP, but will require well-designed studies to confirm the suggested causative relationship between bacterial infection and an autoimmune disease state.

Human platelets efficiently kill IgG-opsonized E. coli

Platelets are known contributors of hemostasis but have recently been shown to be important in inflammation and infectious diseases. Moreover, thrombocytopenia is often observed in patients with sepsis. We previously reported that platelets actively phagocytosed IgG-coated latex beads. In this study, the capacity of human platelets to participate in host defense against bacterial infections was determined by assessing their ability to kill Escherichia coli. Washed human platelets were incubated with unopsonized or IgG-opsonized E. coli and evaluated for binding and killing of E. coli. We found that although both unopsonized and IgG-opsonized E. coli were associated with platelets, only IgG-opsonized E. coli were efficiently killed unless platelets were activated by a potent agonist. The bactericidal activity was dependent on FcγRIIA, was sensitive to cytochalasin D, but was not due to reactive oxygen metabolites. These data suggest that platelets may play an important role in protection against infection.

14C-urea breath test is safe for pediatric patients

Helicobacter pylori (H. pylori) infection, quite prevalent in the developing countries, is considered to be one of the causative factors for various gastric pathologies and other nongastric diseases. It is believed that H. pylori infection is almost always acquired in early childhood and persists throughout life unless specific treatment is given. The (13/14)C-urea breath test (UBT) is now considered to be a 'gold standard' technique for the detection of H. pylori infection. However, because of the lack of facilities and high cost, the preferred nonradioactive ¹³C-UBT cannot be performed on pediatric patients in developing countries, whereas the radioactive ¹⁴C-UBT is not used on children because of the fear of radiation exposure. When using 37 kBq (1 μCi) of ¹⁴C-urea for the ¹⁴C-UBT, the patient is not exposed to more radiation than is acquired from the natural environment in one day, as almost all the ingested radioactivity is excreted from the body (urine and breath) within 72-120 h. This article reviews the importance of the ¹⁴C-UBT for the detection of H. pylori and justifies the radiation safety aspects of its use in children without any fear of 'radiation phobia' where the facility for ¹³C-UBT is lacking.

Internalization of IgG-coated targets results in activation and secretion of soluble CD40 ligand and RANTES by human platelets

Platelets are crucial elements for maintenance of hemostasis. Other functions attributable to platelets are now being appreciated, such as their role in inflammatory reactions and host defense. Platelets have been reported to bind immunological stimuli like IgG complexes, and for nearly 50 years it has been speculated that platelets may participate in immunological reactions. Platelets have been reported to bind and internalize various substances, similar to other leukocytes, such as macrophages and dendritic cells. In the present study, we tested the hypothesis that human platelets can bind and internalize IgG-coated particles, similar to leukocytes. To this end, we observed that interaction with IgG-coated beads resulted in platelet activation (as measured by CD62P expression), internalization of targets, and significant soluble CD40 ligand (sCD40L) and RANTES (regulated upon activation, normal T cell expresses and secreted) secretion. Blocking FcγRIIA with monoclonal antibody (MAb) IV.3 or inhibiting actin remodeling with cytochalasin D inhibited platelet activation, internalization, and cytokine production. These data suggest that platelets are capable of mediating internalization of IgG-coated particles, resulting in platelet activation and release of both sCD40L and RANTES.

Consequences of Helicobacter pylori infection in children

Although evidence is emerging that the prevalence of Helicobacter pylori (H. pylori) is declining in all age groups, the understanding of its disease spectrum continues to evolve. If untreated, H. pylori infection is lifelong. Although H. pylori typically colonizes the human stomach for many decades without adverse consequences, children infected with H. pylori can manifest gastrointestinal diseases. Controversy persists regarding testing (and treating) for H. pylori infection in children with recurrent abdominal pain, chronic idiopathic thrombocytopenia, and poor growth. There is evidence of the role of H. pylori in childhood iron deficiency anemia, but the results are not conclusive. The possibility of an inverse relationship between H. pylori and gastroesophageal reflux disease, as well as childhood asthma, remains a controversial question. A better understanding of the H. pylori disease spectrum in childhood should lead to clearer recommendations about testing for and treating H. pylori infection in children who are more likely to develop clinical sequelae.

Lipoteichoic acid may affect the pathogenesis of bile duct damage in primary biliary cirrhosis

AIM

Intrahepatic bile ducts are the targets for inflammation in primary biliary cirrhosis (PBC), but their pathogenesis is not known. Gram-positive bacterial DNA was detected recently in gallbladder bile of PBC patients. In the present study, we assessed the possible pathological role of lipoteichoic acid (LTA), the gram-positive bacterial cell wall component, in PBC.

METHODS

Liver samples, obtained from 20 patients with PBC (stage 1-2 with CNSDC: stage 3-4 with loss of bile ducts = 10:10) and from 13 patients with chronic hepatitis due to hepatitis C virus (CH-C) with lymphocytic cholangitis, were subjected to immunohistochemical staining with polyclonal rabbit anti-LTA as the primary antibody. Serum reactivities to LTA were studied by ELISA. After 1 microg of purified LTA was placed in a 96-well microplate as an antigen, an antibody capture assay was carried out using serum samples from PBC (n = 20), CH-C (n = 13) and healthy subjects (n = 11).

RESULTS

LTA was localized around the sites of chronic non-suppurative destructive cholangitis (CNSDC) in the portal area in stage 1-2 PBC but was not detected in the portal area in CH-C. In stage 3-4 PBC, LTA was localized around sites of ductular proliferation at the periphery of portal tracts. IgM class anti-LTA serum titers were significantly higher in PBC than in CH-C. IgA class anti-LTA serum titers were significantly higher in PBC than in healthy subjects.

CONCLUSIONS

In the PBC livers, the profile of immunoreactivity to LTA changed markedly as the disease progressed. Sera from PBC showed higher levels of anti-LTA titers than CH-C (IgM) or from healthy subjects (IgA). The LTA-mediated immune system might affect the initiation and/or progression of PBC.

Absence of platelet recovery following Helicobacter pylori eradication in childhood chronic idiopathic thrombocytopenic purpura: a multi-center randomized controlled trial

OBJECTIVE

To investigate the effect of Helicobacter pylori eradication on platelet recovery in childhood chronic idiopathic thrombocytopenic purpura (ITP).

PATIENTS AND METHODS

A multi-center randomized controlled trial was conducted. Patients aged 4-18 years, diagnosed with chronic ITP, defined by platelet count below 100 x 10(9)/L lasting more than 6 months without identified causes, were enrolled and underwent (13)C-urea breath test for diagnosis of H. pylori infection. Patients who received prednisolone more than 0.5 mg/kg per day or received other platelet-enhancing therapy were excluded. Patients with H. pylori infection were randomized into two groups: treatment and control groups. Treatment group received a standard protocol for H. pylori eradication and repeated (13)C-UBT at 4-6 weeks to confirm successful therapy while the control group received no specific treatment. Monthly platelet count was monitored for 6 months in both groups. Primary outcome was platelet recovery, defined by platelet count over 100 x 10(9)/L for at least 3 months.

RESULTS

Of the 55 ITP children, 16 (29.1%) had H. pylori infection. There were no differences in age, sex, duration of disease, platelet count, and the dose of prednisolone between the treatment group (n = 7) and control group (n = 9). One patient in control group was withdrawn due to massive gastrointestinal bleeding requiring a high dose prednisolone. At 6 months, platelet recovery was demonstrated in one patient in the treatment group as well as one in the control group.

CONCLUSION

No beneficial effect of H. pylori eradication on platelet recovery in childhood chronic ITP was identified.

Long term platelet responses to Helicobacter pylori eradication in Canadian patients with immune thrombocytopenic purpura

This prospective Canadian pilot study assesses the platelet response rate in H. pylori positive and negative patients and evaluates potential mechanisms to explain response. Patients with ITP received H. pylori eradication therapy and platelet counts at day 56 were used to assess response. Gastric permeability, stool H. pylori antigen and serum CagA anti-body were done at baseline and at day 60. Twenty-two patients were enrolled with an overall response rate of 27% (6/22). The prevalence of H. pylori was 18% (4/22). Seventy-five percent of the H. pylori positive patients (3/4) achieved a response compared to 17% (3/18) of the H. pylori negative patients (P < 0.05). Seventy-five percent of complete responders have demonstrated long-term ongoing responses at 48 months of follow-up. A trend towards lower post-eradication gastric permeability in responders was seen. Although the prevalence of H. pylori is low, H. pylori positive Canadian patients with ITP may benefit from a trial of H. pylori eradication therapy as a safe and effective means to achieve long term platelet response.

What is new in the management of Helicobacter pylori?

Since the discovery of Helicobacter pylori in the early 1980s several treatment regimens have been developed to effectively treat this infection. International guidelines have allowed consensus on the best management and improved eradication rates. In recent years increasing antimicrobial resistance and falling eradication rates highlight the need for updated guidelines. In this article we review the most recent European management guidelines and in view of the unavailability of some drugs consider new treatment regimens for the management of H. pylori in Ireland.

A possible role of histone-like DNA-binding protein of Streptococcus intermedius in the pathogenesis of bile duct damage in primary biliary cirrhosis

Bacterial infection has become a focus of attention in the pathogenesis of primary biliary cirrhosis (PBC). It was reported that anti-histone autoantibody was detected in PBC, suggesting that bacterial histone-like DNA-binding protein (HLP) may be involved in the pathogenesis of PBC. To identify bacterial species in PBC to confirm this possibility, serum reactivity to bacterial cells was studied by ELISA. The IgM class Streptococcus intermedius titers were significantly higher in PBC than chronic hepatitis due to hepatitis C virus (CH-C) and healthy subjects. Among the streptococci, S. intermedius was selected for further study. The antigenic peptide of S. intermedius of HLP was synthesized to examine the serum reactivity to Si-HLP. IgM class anti-Si-HLP peptide titers were significantly higher in PBC. Immunoreactivity to anti-Si-HLP was detected in the cytoplasm of biliary epithelial cells and inflammatory cells in the portal area in PBC patients' livers. Streptococci, especially S. intermedius, might play a key role in the pathogenesis of PBC, possibly involving HLP.

Diagnosis, pathophysiology and management of children with refractory immune thrombocytopenic purpura

PURPOSE OF REVIEW

Refractory immune thrombocytopenic purpura is infrequent in children, but carries substantial morbidity and even mortality. Management of these children is controversial despite the availability of several treatment options as these strategies have not been directly compared and there are many definitions for refractory immune thrombocytopenic purpura. This review will provide an update on the pathogenesis, diagnosis and treatment options for children with severe, acute and chronic refractory immune thrombocytopenic purpura.

RECENT FINDINGS

Recent studies have demonstrated a number of immunologic alterations (dominant proinflammatory state, inadequate thrombopoiesis, and various B and T lymphocyte disturbances) in the pathogenesis of chronic immune thrombocytopenic purpura. New agents that target certain of these mechanisms (e.g. anti-CD20 monoclonal antibody, thrombopoietic agents) have shown promising results in recent clinical trials, primarily but not solely in adults.

SUMMARY

Management of refractory immune thrombocytopenic purpura often requires multiple agents that may provide only short-term benefit. Lack of clear views about the use of these medications, their unwanted side effects and an inability to specifically target a particular patient's disease all lead to frustration among patients, family and the physicians. Better understanding of pathogenesis with the availability of newer therapies with different mechanisms of effect should, however, allow improved management of these patients.

The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases

Helicobacter pylori is the main cause of peptic ulceration, distal gastric adenocarcinoma, and gastric lymphoma. Only 15% of those colonized develop disease, and pathogenesis depends upon strain virulence, host genetic susceptibility, and environmental cofactors. Virulence factors include the cag pathogenicity island, which induces proinflammatory, pro-proliferative epithelial cell signaling; the cytotoxin VacA, which causes epithelial damage; and an adhesin, BabA. Host genetic polymorphisms that lead to high-level pro-inflammatory cytokine release in response to infection increase cancer risk. Pathogenesis is dependent upon inflammation, a Th-1 acquired immune response and hormonal changes including hypergastrinaemia. Antral-predominant inflammation leads to increased acid production from the uninflamed corpus and predisposes to duodenal ulceration; corpus-predominant gastritis leads to hypochlorhydria and predisposes to gastric ulceration and adenocarcinoma. Falling prevalence of H. pylori in developed countries has led to a falling incidence of associated diseases. However, whether there are disadvantages of an H. pylori-free stomach, for example increased risk of esosphageal adenocarcinoma, remains unclear.

Helicobacter pylori infection and chronic immune thrombocytopenic purpura: long-term results of bacterium eradication and association with bacterium virulence profiles

Eradication of Helicobacter pylori may lead to improvement of chronic immune thrombocytopenic purpura (ITP), although its efficacy over time is uncertain. We report the results of H pylori screening and eradication in 75 consecutive adult patients with ITP. We also used molecular methods to investigate lymphocyte clonality and H pylori genotypes in the gastric biopsies from 10 H pylori-positive patients with ITP and 19 H pylori-positive patients without ITP with chronic gastritis. Active H pylori infection was documented in 38 (51%) patients and successfully eradicated in 34 (89%) patients. After a median follow-up of 60 months, a persistent platelet response in 23 (68%) of patients with eradicated infection was observed; 1 relapse occurred. No differences in mucosal B- or T-cell clonalities were observed between patients with ITP and control participants. Of note, the frequency of the H pylori cagA gene (P = .02) and the frequency of concomitant H pylori cagA, vacAs1, and iceA genes (triple-positive strains; P = .015) resulted statistically higher in patients with ITP than in control participants. All asymptomatic H pylori-positive patients with ITP were suffering from chronic gastritis. Our data suggest a sustained platelet recovery in a proportion of patients with ITP by H pylori eradication alone. Overrepresentation of specific H pylori genotypes in ITP suggests a possible role for bacterium-related factors in the disease pathogenesis.

Effect of Helicobacter pylori eradication on platelet count in idiopathic thrombocytopenic purpura: a systematic review and meta-analysis

BACKGROUND

There is a debate in the recent literature about the effect of Helicobacter pylori eradication on platelet count in patients with idiopathic thrombocytopenic purpura (ITP). In order to clarify this controversial issue, we performed a systematic review with meta-analysis of the available literature.

METHODS

The meta-analytic comparison was focused on the difference in the platelet count increase between the experimental arm (H. pylori-infected patients who responded to eradication therapy) and each control arm (H. pylori-infected patients who failed to respond to eradication therapy; H. pylori-infected patients who did not receive eradication therapy and H. pylori-negative patients) and was expressed as weighted mean difference (WMD). Moreover, in order to explain the heterogeneity, a meta-regression model was fitted with arm-level covariates.

RESULTS

Data involving 788 ITP patients were collected from 17 articles (16 studies with a prospective cohort design and 1 randomized trial). There was a statistically significant difference in the increase in platelet count in patients in whom eradication was successful compared with control groups [WMD, 40.77x10(9)/L (95% CI, 20.92-60.63) compared with untreated patients; 52.16 (95% CI, 34.26-70.05) compared with patients who failed eradication and 46.35 (95% CI, 27.79-64.91) compared with H. pylori-negative patients]. Moreover, in the meta-regression model, the success of H. pylori eradication was highly significant as an explanatory variable for platelet count increase.

CONCLUSIONS

Our analysis shows a strict correlation between H. pylori eradication and increase in platelet count. However, due to intrinsic limits in the design of the studies analysed, further evidence from randomized clinical trials is required to confirm the effect of eradication treatment on platelet count.

Helicobacter pylori infection in epileptic patients

It is well known that there might be an epidemiological association between Helicobacter pylori infection and extraintestinal diseases. This study aimed at determining H. pylori infection in epileptic patients. Forty-seven cryptogenic epileptic patients (Group 1) and 35 healthy people (Group 2) participated in this study. Presence of H. pylori infection was examined by H. pylori stool antigen (HpSA), H. pylori IgG, and IgM. HpSA was detected in 21 participants (44.6%) in Group 1 and in 3 participants (8.5%) in Group 2. H. pylori IgM was positive in 27 participants (57.4%) in Group 1 and in 8 participants (22.8%) in Group 2. H. pylori IgG was positive in 37 participants (78.7%) in Group 1 and in 13 participants (38%) in Group 2. The difference of rates of HpSA, H. pylori IgM and IgG in Groups 1 and 2 were found statistically significant (chi2=4.18, p=0.04; chi2=9.18, p=0.0017; chi2=14.58, p<0.001, respectively). We also compared presence of H. pylori infection between the epileptic patients with poor and good prognosis; HpSA positivity was detected in 15 (62.5%) of 24 and 6 (26%) of 23, respectively, and the differences were statistically significant (chi2=6.30, p=0.012). H. pylori IgM positivity was detected in 16 (66%) of 24 patients with poor prognosis and 11 (47.8%) of 23 patients with good prognosis (p>0.05). H. pylori IgG positivity was detected in 18 (75%) of 24 patients with poor prognosis and 19 (82.6%) of 23 patients with good prognosis. The differences of H. pylori IgM and IgG positivity rates in epileptic patients with poor and good prognosis were not found statistically significant (p>0.05). These results suggest a probable association between the acute H. pylori infection and epilepsy, especially with poor prognosis.

The co-evolved Helicobacter pylori and gastric cancer: trinity of bacterial virulence, host susceptibility and lifestyle

Helicobacter pylori is an important yet unproven etiological agent of gastric cancer. H. pylori infection is more prevalent in developing Asian countries like India and it is usually acquired at an early age. It has been two decades since Marshall and Warren (1984) first described curved bacilli in the stomach of ulcer and gastritis patients. This discovery has won them the Nobel Prize recently, but the debate whether H. pylori is a pathogen or a commensal organism is still hot. Associations with disease-specific factors remain illusive years after the genome sequences were made available. Cytotoxin-associated antigen A (CagA) and the so-called plasticity region cluster genes are implicated in pathogenesis of the carcinoma of stomach. Another virulence factor VacA whose role is still debatable, has recently been projected in pathology of gastric cancer. Studies of the evolution through genetic variation in H. pylori populations have provided a window into the history of human population migrations and a possible co-evolution of this pathogen with its human host. Possible symbiotic relationships were seriously debated since the discovery of this pathogen. The debate has been further intensified as some studies proposed H. pylori infection to be beneficial in some humans. In this commentary, we attempt to briefly discuss about H. pylori as a human pathogen, and some of the important issues linked to its pathophysiology in different hosts.

'We dance around in a ring and suppose, the secret sits in the middle and knows' – Robert Frost

Anti-Helicobacter pylori seropositivity: influence on severity and treatment response in patients with chronic hepatitis C

We sought to clarify the incidence and role of Helicobacter pylori (H. pylori) seropositivity in patients with hepatitis C virus (HCV) infection and the effect of coinfection on interferon-alpha and ribavirin therapy. The presence of H. pylori was tested using a commercially available enzyme immunoassay in serum samples from 93 patients with chronic hepatitis C. Clinical features, HCV markers and response of HCV to interferon-alpha and ribavirin were compared between H. pylori-positive and H. pylori-negative patients. Anti-H. pylori antibody was detected in 45 (48%) of the 93 patients, whose median HCV-RNA level (495 vs 760 kIU/mL; P = 0.013) and platelet count (128 vs 158 x 10(3)/microL; P = 0.009) were significantly lower than in patients with HCV infection alone. Anti-H. pylori antibody levels were found to be significantly correlated with fibrosis score (P = 0.0083, r = 0.33) but inversely related to platelet count (P = 0.0037, r = -0.34). The sustained response rate for HCV clearance following interferon-alpha and ribavirin treatment did not differ between patients with and without anti-H. pylori seropositivity. The presence of H. pylori [odds ratio (OR) 8.61; 95% confidence interval (CI) 1.59-46.70] and fibrosis score (OR 30.13; 95% CI 5.44-166.78) were found by multivariate analysis to be associated with the decrease of platelet count during therapy. Coexistent H. pylori infection does not demonstrably influence the clinical course of chronic hepatitis C. A possible connection between H. pylori coinfection and thrombocytopenia was found during the treatment course, suggesting that preemptive eradication of H. pylori may facilitate completion of treatment and increased sustained virological response.

The interaction of bacterial pathogens with platelets

In recent years, the frequency of serious cardiovascular infections such as endocarditis has increased, particularly in association with nosocomially acquired antibiotic-resistant pathogens. Growing evidence suggests a crucial role for the interaction of bacteria with human platelets in the pathogenesis of cardiovascular infections. Here, we review the nature of the interactions between platelets and bacteria, and the role of these interactions in the pathogenesis of endocarditis and other cardiovascular diseases.

The pathogenesis of immune thrombocytopaenic purpura

Immune thrombocytopaenic purpura (ITP) is an autoimmune bleeding disease that is rarely fatal. However, in many adults treatment is unsatisfactory, with as much morbidity from the immunosuppressive effects of treatment as from bleeding. Identifying the underlying disease process should help us to identify more targeted therapies and improve not only the treatment but also the quality of life of patients with this disorder.

Helicobacter pylori-associated immune thrombocytopenia

Idiopatic thrombocytopenic purpura (ITP), a disorder characterized by autoantibody-mediated platelet destruction, may be primary or secondary to various illnesses including lymphoproliferative, autoimmune, or infectious diseases. There are increasing data on the association between Helicobacter pylori infection and idiopathic thrombocytopenic purpura and the significant increase in platelet count after bacterial eradication. The aim of this review is to consider the studies so far published on Helicobacter pylori infection and idiopathic thrombocytopenic purpura in order to evaluate a possible pathogenic correlation between these two conditions. A review of the literature data show that Helicobacter pylori eradication in patients with idiopathic thrombocytopenic purpura is effective in increasing platelet count in approximately half of the cases. However, since the studies so far published are few, sometimes controversial and involve small series of patients, further controlled studies on larger numbers of patients with longer follow-up are needed to confirm these preliminary findings.

Rifaximin-based regimens for eradication of Helicobacter pylori: a pilot study

BACKGROUND

Triple therapy is the treatment of choice for Helicobacter pylori-infected patients with an eradication rate ranging from 70 to 85%. Poor compliance and antibiotic resistance are the main causes of treatment failure. The aim of the present study was to assess the efficacy of rifaximin, a poorly absorbed antibiotic, for H. pylori eradication.

METHODS

We enrolled 48 consecutive H. pylori-positive patients affected. They were randomized to receive two 7-day rifaximin-based triple therapies: rifaximin tablets 400 mg t.i.d., esomeprazole 40 mg o.d. and clarithromycin 500 mg b.i.d. (CRE) or levofloxacin 500 mg o.d. (LRE). H. pylori eradication was assessed using a (13)C-urea breath test 4 weeks after the end of therapy. Treatment compliance and the incidence of side effects were also evaluated.

RESULTS

No dropouts were observed. The eradication rate both on intention-to-treat and per-protocol analysis did not show significant differences between groups: 58% (14/24 patients) in group 1 and 42% (10/24 patients) in group 2 (p = 0.24, OR 1.96, 95% CI 0.62-6.18). No significant differences in patients' compliance and incidence of side effects were found between groups.

CONCLUSIONS

Rifaximin-based therapy showed optimal compliance but a limited eradication rate compared to standard first-line treatment. Further investigations are needed to evaluate different dosages and combinations.

Thrombocytopenic conditions-autoimmunity and hypercoagulability: commonalities and differences in ITP, TTP, HIT, and APS

Immune thrombocytopenia purpura (ITP), thrombotic thrombocytopenia purpura (TTP), heparin-induced thrombocytopenia (HIT), and antiphospholipid syndrome (APS) are clinical conditions associated with significant morbidity and mortality. These well-defined clinical syndromes have in common several properties: (1) their pathogenesis is immune mediated, specifically by autoantibodies; (2) thrombocytopenia is a hallmark in these four conditions; (3) except for the case of ITP, platelet and endothelial cell activation occurs in TTP, HIT, and APS, resulting in a prothrombotic state and an increased risk of thrombosis. Although these four immune-mediated syndromes are well-defined diseases, several case reports and studies have documented the association of two diseases in the same patient, illustrating the concept of the kaleidoscope of autoimmunity.

Immunity markers in patients with Helicobacter pylori infection: effect of eradication

BACKGROUND

Helicobacter pylori is a microorganism able to stimulate a robust inflammatory and systemic immune response.

AIM

The aim of our study was to evaluate autoimmune markers in dyspeptic patients positive for H. pylori infection compared to a control group of non-H. pylori-infected subjects. The kinetics of cryoglobulins and autoantibodies was evaluated after treatment of the infection.

PATIENTS AND METHODS

Dyspeptic patients with active H. pylori infection and age- and sex-matched healthy H. pylori-negative controls were studied. Markers of immunity were compared, in H. pylori-infected patients before, 6 months and 1 year after the end of therapy. Results were also compared between those with and without successful eradication therapy.

RESULTS

Eighty-six individual were entered (43 H. pylori-infected). H. pylori-infected patients had higher levels of IgG and/or IgA and/or IgM (22/43 versus 2/43). Circulating immune complexes and cryoglobulins were detected in patients more often than controls (p < .05 for both). Autoantibodies were observed in 13 patients (30% versus 5% in controls) and antithyroid antibodies in 12 (p < .04 versus controls). Lower levels of C3 and/or C4 complement fractions were observed in infected patients with respect to controls (7/43 versus 1/43; p = .014). After 1 year of follow-up, the markers of autoimmunity dramatically improved in patients eradicated for H. pylori infection compared to those in whom therapy failed. No patient developed a clinical autoimmune disorder.

CONCLUSIONS

Additional studies are necessary to ascertain the clinical significance of the modifications of autoimmune markers in patients with H. pylori infection.

Thrombotic thrombocytopenic purpura: proposal of a new pathogenic mechanism involving Helicobacter pylori infection

Thrombotic thrombocytopenic purpura (TTP) is a severe, occlusive, thrombotic microangiopathy characterized by a systemic platelet aggregation, organ ischemia, profound thrombocytopenia and erythrocyte fragmentation. Recent observations have documented that a deficiency of a von Willebrand factor (VWF)-cleaving protease, termed ADAMTS13, that normally cleaves hyper-reactive unusually large VWF multimers into smaller and less adhesive VWF forms, may be responsible for many cases of TTP. Multiple mutations of the ADAMTS13 gene can result in ADAMTS13 deficiency and cause congenital TTP, while autoantibodies neutralizing ADAMTS13 protease activity have been associated with acquired TTP. However, in spite of the recent progresses in the pathophysiology of TTP, many aspects of this disease remain still controversial. In this study, basing on the laboratory results of a group of eight patients with an acquired form of TTP, an alternative pathogenic mechanism for TTP involving Helicobacter pylori infection is proposed. In fact, Helicobacter pylori, which has been recently implied in the pathogenesis of idiopathic thrombocytopenic purpura (ITP), could function as a triggering factor in TTP by inducing platelet aggregation through an interaction with VWF.

Important bacterial gastrointestinal pathogens in children: a pathogenesis perspective

This article focuses on the five most common bacterial enteropathogens of the developed world--Helicobacter pylori, Escherichia coli, Shigella, Salmonella, and Campylobacter--from the perspective of how they cause disease and how they relate to each other. Basic and recurring themes of bacterial pathogenesis, including mechanisms of entry, methods of adherence, sites of cellular injury, role of toxins, and how pathogens acquire particular virulence traits (and antimicrobial resistance), are discussed.

The Role of Autoreactive T-Cells in the Pathogenesis of Idiopathic Thrombocytopenic Purpura

Idiopathic thrombocytopenic purpura (ITP) is an autoimmune disease mediated by antiplatelet autoantibodies. The major target of these autoantibodies is a platelet membrane glycoprotein, GPIIb-IIIa, which is a receptor for fibrinogen and other ligands. We recently identified CD4+ T-cells autoreactive to GPIIb-IIIa in ITP patients. These T-cells are considered pathogenic because they help B-cells produce antibodies that bind to normal platelet surfaces. GPIIb-IIIa-reactive T-cells respond to chemically reduced and tryptic peptides of GPIIb-IIIa but not to native GPIIb-IIIa, indicating that the epitopes they recognize are "cryptic" determinants generated at a subthreshold level by the processing of native GPIIb-IIIa under normal circumstances. Although GPIIb-IIIa-reactive T-cells are also detected in healthy individuals, they are activated in vivo only in ITP patients. Activation of GPIIb-IIIa-specific T-cells and the subsequent production of pathogenic anti-GPIIb-IIIa antibodies can be induced by functional antigen-presenting cells in the spleen that present cryptic GPIIb-IIIa peptides to these T-cells. The pathogenic process of ITP can be explained as a continuous loop in which B-cells produce antiplatelet autoantibodies, splenic macrophages phagocytose antibody-coated platelets and present GPIIb-IIIa-derived cryptic peptides, and GPIIb-IIIa-reactive CD4+ T-cells exert their helper activity. Further studies examining the mechanisms that induce the processing and presentation of cryptic peptides derived from the platelet antigen at disease onset will clarify how the pathogenic autoantibody response in ITP is initiated.

Helicobacter pylori Infection and Idiopathic Thrombocytopenic Purpura

A treatment strategy for idiopathic thrombocytopenic purpura (ITP) is considered with the aim of cure or management of the bleeding tendency. In 1998, Gasbarrini et al reported a high prevalence of Helicobacter pylori infection in patients with ITP and showed that platelet recovery occurred after eradication therapy in most cases. Since then, many studies were performed to evaluate eradication therapy. This article discusses the incidence of H pylori infection in ITP, characteristic clinical features in H pylori-positive ITP, the effectiveness of eradication on platelet count increase, and the mechanisms of development of ITP by H pylori infection. Overall, there was a positive association between H pylori infection and ITP, and eradication of bacterium was accompanied by a significant increase in platelet counts in more than 50% of H pylori-positive ITP cases. These findings suggest that H pylori infection is involved in the mechanisms of thrombocytopenia in most cases of ITP in middle-aged and older patients. This approach could be beneficial to some ITP patients, but there were some uncertainties raised. To confirm the effectiveness of eradication therapy in H pylori-positive ITP, prospective studies conducted in several countries with a new treatment protocol are required, with a large number of ITP cases and longer follow-up.