The Story So Far:Helicobacter Pyloriand Gastric Autoimmunity

Autoimmune Gastritis with a Long-term Course of Type B Gastritis: A Report of Two Cases

Autoimmune gastritis (AIG) typically exhibits the characteristics of type A gastritis and has been classified as a separate disease from type B gastritis that corresponds to Helicobacter pylori gastritis. However, many reports have suggested the involvement of H. pylori infection in the pathogenesis of AIG. In our two cases, the patients' previous gastritis exhibited a clear pattern in which H. pylori gastritis had progressed over many years, but ultimately transitioned to AIG with its spontaneous disappearance. These findings suggest that some cases of AIG might originate from long-standing H. pylori gastritis.

Rapid Progression of Autoimmune Gastritis after Helicobacter pylori Eradication Therapy: A Case Report

We herein report a case of autoimmune gastritis (AIG) with rapid progression after Helicobacter pylori eradication therapy. The patient's previous gastritis had followed the course of type B gastritis before eradication therapy for many years. Immediately after eradication, we diagnosed her with AIG and carefully followed changes in the endoscopic and histopathological findings and serum markers. All of these clinical findings showed significant atrophic progression in the corporal area for approximately three years. We concluded that H. pylori eradication therapy exacerbated AIG in this case.

Five Autoimmune Gastritis Patients with Positive Findings of Serum Anti-parietal Cell Antibodies

Autoimmune gastritis is a corpus-dominant type of gastritis with positive serum anti-parietal cell antibodies (APCA) and/or anti-intrinsic factor antibodies. Serum APCA and pepsinogen (PG) assays were performed in subjects with corpus-dominant gastritis detected by endoscopy. Serum APCA was positive in five patients. All these patients were postmenopausal women (four Koreans and one Caucasian from the Russian Federation) with a mean age of 59.0±3.2 years. They displayed low PG I levels ranging from 8.1 to 18.8 ng/mL (mean, 11.4±4.8 ng/mL) and low PG I/II ratios ranging from 0.7 to 2.4 (mean, 1.2±0.7). Three of the patients were being treated for autoimmune thyroiditis. Multiple gastric neuroendocrine tumors were observed in two Helicobacter pylori (H. pylori)-naive patients with high serum gastrin levels exceeding 700 pg/mL and serum chromogranin A levels exceeding 1,000 ng/mL. In the remaining three patients, intestinal metaplasia was observed in the biopsied specimens from the antrum, suggesting a history of H. pylori infection. Our findings indicate the value of positive serum APCA findings, low serum PG I levels, and low serum PG I/II ratios in confirming autoimmune gastritis in patients showing corpus-dominant atrophy, regardless of their H. pylori infection status.

Proteomics signature of autoimmune atrophic gastritis: towards a link with gastric cancer

BACKGROUND

Autoimmune atrophic gastritis (AAG) is a chronic disease that can progress to gastric cancer (GC). To better understand AAG pathology, this proteomics study investigated gastric proteins whose expression levels are altered in this disease and also in GC.

METHODS

Using two-dimensional difference gel electrophoresis (2D-DIGE), we compared protein maps of gastric corpus biopsies from AAG patients and controls. Differentially abundant spots (|fold change|≥ 1.5, P < 0.01) were selected and identified by LC-MS/MS. The spots were further assessed in gastric antrum biopsies from AAG patients (without and with Helicobacter pylori infection) and from GC patients and unaffected first-degree relatives of GC patients.

RESULTS

2D-DIGE identified 67 differentially abundant spots, with 28 more and 39 less abundant in AAG-corpus than controls. LC-MS/MS identified these as 53 distinct proteins. The most significant (adjusted P < 0.01) biological process associated with the less abundant proteins was "tricarboxylic acid cycle". Of the 67 spots, 57 were similarly differentially abundant in AAG-antrum biopsies irrespective of H. pylori infection status. The differential abundance was also observed in GC biopsies for 14 of 28 more abundant and 35 of 39 less abundant spots, and in normal gastric biopsies of relatives of GC patients for 6 and 25 spots, respectively. Immunoblotting confirmed the different expression levels of two more abundant proteins (PDIA3, GSTP gene products) and four less abundant proteins (ATP5F1A, PGA3, SDHB, PGC).

CONCLUSION

This study identified a proteomics signature of AAG. Many differential proteins were shared by GC and may be involved in the progression of AAG to GC.

Vitamin B12 status in health and disease: a critical review. Diagnosis of deficiency and insufficiency - clinical and laboratory pitfalls

Vitamin B₁₂ (cobalamin) is an essential cofactor for two metabolic pathways. It is obtained principally from food of animal origin. Cobalamin becomes bioavailable through a series of steps pertaining to its release from dietary protein, intrinsic factor-mediated absorption, haptocorrin or transcobalamin-mediated transport, cellular uptake, and two enzymatic conversions (via methionine synthase and methylmalonyl-CoA-mutase) into cofactor forms: methylcobalamin and adenosylcobalamin. Vitamin B₁₂ deficiency can masquerade as a multitude of illnesses, presenting different perspectives from the point of view of the hematologist, neurologist, gastroenterologist, general physician, or dietician. Increased physician vigilance and heightened patient awareness often account for its early presentation, and testing sometimes occurs during a phase of vitamin B₁₂ insufficiency before the main onset of the disease. The chosen test often depends on its availability rather than on the diagnostic performance and sensitivity to irrelevant factors interfering with vitamin B₁₂ markers. Although serum B₁₂ is still the most commonly used and widely available test, diagnostics by holotranscobalamin, serum methylmalonic acid, and plasma homocysteine measurements have grown in the last several years in routine practice. The lack of a robust absorption test, coupled with compromised sensitivity and specificity of other tests (intrinsic factor and gastric parietal cell antibodies), hinders determination of the cause for depleted B₁₂ status. This can lead to incorrect supplementation regimes and uncertainty regarding later treatment. This review discusses currently available knowledge on vitamin B₁₂, informs the reader about the pitfalls of tests for assessing its deficiency, reviews B₁₂ status in various populations at different disease stages, and provides recommendations for interpretation, treatment, and associated risks. Future directions for diagnostics of B₁₂ status and health interventions are also discussed.

Features That Aid Identification of Autoimmune Gastritis in a Background of Active Helicobacter pylori Infection

CONTEXT.—

Helicobacter pylori-associated and autoimmune gastritis may coexist in a subset of patients who require treatment for both disorders.

OBJECTIVE.—

To delineate findings that identify autoimmune gastritis in the background of H pylori infection.

DESIGN.—

We examined cases of (1) patients with H pylori-associated gastritis who had successful eradication therapy and subsequent biopsies diagnostic of autoimmune gastritis and (2) H pylori-associated gastritis wherein pathologists noted features of autoimmune gastritis during original interpretation. Control patients underwent H pylori eradication but lacked evidence of autoimmune gastritis or H pylori infection after 10 years of follow-up.

RESULTS.—

Eight subjects had H pylori-associated gastritis followed by H pylori-negative sampling that showed autoimmune gastritis. Review of original samples showed full-thickness inflammation of oxyntic mucosa in 8 of 8 and oxyntic gland loss in 7 of 8 cases. Enterochromaffin-like (ECL) cell hyperplasia, pyloric metaplasia, and intestinal metaplasia were present in 4 of 8 (80% of 5 tested cases), 4 of 8, and 3 of 8 cases, respectively. Features of autoimmune gastritis were noted at the time of their original H pylori diagnosis in 11 study subjects. Ten of 11 samples displayed full-thickness inflammation of oxyntic mucosa and/or partial loss of oxyntic glands, 8 of 11 had ECL cell hyperplasia (all tested cases), 6 of 11 showed pyloric metaplasia, and 4 of 11 harbored intestinal metaplasia. Except for full-thickness oxyntic mucosa inflammation, these features were absent in control cases.

CONCLUSIONS.—

Full-thickness inflammation combined with oxyntic gland loss and ECL cell hyperplasia may help to identify autoimmune gastritis in patients with concomitant H pylori infection.

Thyro-entero-gastric autoimmunity: Pathophysiology and implications for patient management

The association between autoimmune atrophic gastritis and thyroid disorders has been observed since the early 1960s and the expression "thyrogastric syndrome" was coined to indicate the presence of thyroid autoantibodies or autoimmune thyroid disease in patients with pernicious anemia, a late clinical stage of autoimmune atrophic gastritis. More recently, it was confirmed that autoimmune thyroid disorders, in particular Hashimoto's thyroiditis, may be frequently associated with other organ-specific, immune-mediated disorders, such as autoimmune atrophic gastritis or celiac disease. The association of Hashimoto's thyroiditis with autoimmune atrophic gastritis or celiac disease in adult patients is currently considered part of the polyglandular autoimmune syndromes which include several autoimmune disorders associated with an autoaggressive impairment of endocrine glands. From a clinical point of view, the thyro-entero-gastric autoimmunity may lead to potentially serious consequences like anemia, micronutrients deficiencies, and drugs malabsorption, as well as to an increased risk for malignancies. These alterations may frequently present in an underhand manner, with consequent diagnostic and treatment delays. Many aspects of the association between thyroid, gastric and intestinal autoimmune diseases still await clarification. The present review focuses on the embryological, genetic and pathophysiological aspects of thyro-entero-gastric autoimmunity. In particular, the current diagnostic criteria of autoimmune thyroid disease, autoimmune atrophic gastritis, and celiac disease are reviewed, along with the evidences for their association in poly-autoimmunity syndromes. The benefits of proactive screening of autoimmune thyroid disorders in patients with autoimmune gastritis or enteropathy and viceversa are also discussed.

Measurement of Autoantibodies to Gastric H+,K+-ATPase (ATP4A/B) Using a Luciferase Immunoprecipitation System (LIPS)

The Luciferase Immuno Precipitation System (LIPS) enables the detection of specific serum antibodies by immunoprecipitation of recombinant antigens tagged with a luciferase reporter. Here we describe LIPS assays for the quantification of autoantibodies to the H+, K+-ATPase A (ATP4A) and B (ATP4B) subunits, two serological markers of autoimmune atrophic gastritis and pernicious anemia. In particular, we will describe the expression of luciferase-tagged recombinant ATP4A and ATP4B, their immunoprecipitation with test sera, the recovery and washing of immune-complexes with a protein-A coated resin, and the quantification of autoantibodies by addition of a luciferase substrate and the measurement of the light output from captured luciferase-tagged antigens.

High incidence of autoimmune gastritis in patients misdiagnosed with two or more failures of H. pylori eradication

BACKGROUND

Although autoimmune gastritis (AIG) is generally considered relatively rare, we frequently encounter AIG among patients at to our hospital who have experienced at least two episodes of Helicobacter pylori eradication failure.

AIMS

We investigated the incidence of AIG in consecutive patients who consulted our department for H. pylori eradication with reference to eradication history.

METHODS

A total of 404 consecutive patients who visited the H. pylori-specific out-patient unit of our hospital from June 2015 to June 2017 were enrolled. Of these, 137 were treatment-naive, 47 had failed treatment once (single failure), and 220 had failed treatment twice or more (multiple failures) by ¹³ C-UBT. Gastroscopy was performed in all patients. Culture tests of gastric mucosal samples were performed for H. pylori and other bacteria positive for urease activity. Anti-parietal cell antibody (APCA) was measured. Patients with severe atrophy in the gastric corpus and positivity for APCA were diagnosed as having AIG.

RESULTS

A total of 43 patients were diagnosed as having AIG, of whom two were treatment-naive (1.5%, 2/137), 1 failed eradication once (2.1% 1/47), and 40 failed treatment at least twice (18.2%, 40/220). The incidence of AIG was significantly higher in the multiple failure group than in the single failure or treatment-naive groups. Urease-positive bacteria, such as Klebsiella pneumoniae and alpha-streptococcus, were identified in 33 of the 35 AIG patients who underwent culture testing.

CONCLUSION

AIG patients were often misdiagnosed as refractory to eradication therapy, probably because achlorhydria in AIG might allow urease-positive bacteria other than H. pylori to colonise the stomach, causing positive ¹³ C-UBT results.

Acid and the basis for cellular plasticity and reprogramming in gastric repair and cancer

Subjected to countless daily injuries, the stomach still functions as a remarkably efficient digestive organ and microbial filter. In this Review, we follow the lead of the earliest gastroenterologists who were fascinated by the antiseptic and digestive powers of gastric secretions. We propose that it is easiest to understand how the stomach responds to injury by stressing the central role of the most important gastric secretion, acid. The stomach follows two basic patterns of adaptation. The superficial response is a pattern whereby the surface epithelial cells migrate and rapidly proliferate to repair erosions induced by acid or other irritants. The stomach can also adapt through a glandular response when the source of acid is lost or compromised (that is, the process of oxyntic atrophy). We primarily review the mechanisms governing the glandular response, which is characterized by a metaplastic change in cellular differentiation known as spasmolytic polypeptide-expressing metaplasia (SPEM). We propose that the stomach, like other organs, exhibits marked cellular plasticity: the glandular response involves reprogramming mature cells to serve as auxiliary stem cells that replace lost cells. Unfortunately, such plasticity might mean that the gastric epithelium undergoes cycles of differentiation and de-differentiation that increase the risk of accumulating cancer-predisposing mutations.

Microbes and Viruses Are Bugging the Gut in Celiac Disease. Are They Friends or Foes?

The links between microorganisms/viruses and autoimmunity are complex and multidirectional. A huge number of studies demonstrated the triggering impact of microbes and viruses as the major environmental factors on the autoimmune and inflammatory diseases. However, growing evidences suggest that infectious agents can also play a protective role or even abrogate these processes. This protective crosstalk between microbes/viruses and us might represent a mutual beneficial equilibrium relationship between two cohabiting ecosystems. The protective pathways might involve post-translational modification of proteins, decreased intestinal permeability, Th1 to Th2 immune shift, induction of apoptosis, auto-aggressive cells relocation from the target organ, immunosuppressive extracellular vesicles and down regulation of auto-reactive cells by the microbial derived proteins. Our analysis demonstrates that the interaction of the microorganisms/viruses and celiac disease (CD) is always a set of multidirectional processes. A deeper inquiry into the CD interplay with Herpes viruses and Helicobacter pylori demonstrates that the role of these infections, suggested to be potential CD protectors, is not as controversial as for the other infectious agents. The outcome of these interactions might be due to a balance between these multidirectional processes.

Increased endogenous antigen presentation in the periphery enhances susceptibility to inflammation-induced gastric autoimmunity in mice

How the immune system maintains peripheral tolerance under inflammatory conditions is poorly understood. Here we assessed the fate of gastritogenic T cells following inflammatory activation in vivo. Self-reactive T cells (A23 T cells) specific for the gastric H⁺ /K⁺ ATPase α subunit (HKα) were transferred into immunosufficient recipient mice and immunised at a site distant to the stomach with adjuvant containing the cognate HKα peptide antigen. Activation of A23 T cells by immunisation did not impact on either immune tolerance or protection from gastric autoimmunity in wild-type BALB/c mice. However, increased presentation of endogenously derived HKα epitopes by dendritic cells (DCs) in the gastric lymph node of IE-H⁺ /K⁺ β transgenic mice (IEβ) reduces A23 T-cell tolerance to gastric antigens after inflammatory activation, with subsequent development of gastritis. While HKα-specific A23 T cells from immunised wild-type mice were poorly responsive to in vitro antigen specific activation, A23 T cells from immunised IEβ transgenic mice were readily re-activated, indicating loss of T-cell anergy. These findings show that DCs of gastric lymph nodes can maintain tolerance of pathogenic T cells following inflammatory stimulation and that the density of endogenous antigen presented to self-reactive T cells is critical in the balance between tolerance and autoimmunity.

Autoimmune Metaplastic Atrophic Gastritis: Recognizing Precursor Lesions for Appropriate Patient Evaluation

Autoimmune metaplastic atrophic gastritis (AMAG) is a significant risk factor for pernicious anemia and gastric neoplasia. Still, the histologic features of AMAG are frequently overlooked, especially in the early stages of the disease. The purpose of our study, therefore, was to catalogue the progression of histologic changes that precede the development of AMAG in affected individuals. Over a 2-year period (2012 to 2014), the diagnosis of AMAG was rendered on material from 113 patients seen at Johns Hopkins Hospital (∼1.8% of "in house" gastric biopsies). Prior gastric body biopsies had been performed on 54 (48%) patients in the cohort, and the majority of these specimens had also shown AMAG. Eighteen of the previous biopsies, however, carried a diagnosis other than AMAG: 13 inactive chronic gastritis, 2 acute Helicobacter pylori gastritis, and 1 each of eosinophilic gastritis, iron pill gastritis, and proton-pump inhibitor-like effect. Upon review of these 18 biopsies, the most common histologic findings were heavy full-thickness or deep lamina propria chronic inflammation (12), inflammatory destruction of oxyntic glands (12), metaplasia (intestinal, pyloric, or pancreatic acinar) (10), prominent lamina propria eosinophils (8), and parietal cell pseudohypertrophy (4). At least 2 of these features were present in the majority (13, 72%) of the biopsies. In addition, 7 (58%) of these patients were also found to have another autoimmune or inflammatory disorder before the diagnosis of AMAG. Although subtle, histologic features of developing AMAG are identifiable in routine gastric body biopsies. When metaplasia, full-thickness chronic inflammation, and/or oxyntic destruction are seen, a note suggesting laboratory testing and/or close clinical follow-up in this subset of patients may be warranted.

Activation of Helicobacter Pylori Causes Either Autoimmune Thyroid Diseases or Carcinogenesis in the Digestive Tract

Helicobacter pylori has been implicated in stimulation of immune system, development of autoimmune endocrinopathies as autoimmune thyroiditis (AT) and on other hand induction of immunosupresion activates gastric and extra-gastric diseases such as gastric ulcer or cancer. It causes persistent lifelong infection despite local and systemic immune response. Our results indicate that Helicobacter pylori might cause inhibition of the specific cellular immune response in Helicobacter pylori-infected patients with or without autoimmune diseases such as AT. We cannot also declare the carcinogenic effect in oropharynx. However the association of any infection agents and cancerogenesis exists. The adherence of Helicobacter pylori expression and enlargement of benign lymphatic tissue and the high incidence of the DNA of Helicobacter pylori in laryngopharyngeal and oropharyngeal cancer is reality. LTT appears to be a good tool for detection of immune memory cellular response in patients with Helicobacter pylori infection and AT. All these complications of Helicobacter pylori infection can be abrogated by successful eradication of Helicobacter pylori.

Type 1 Diabetic Populations Have an Increased Prevalence of Parietal Cell Antibody: A Systematic Review and Meta-Analysis

The presence of parietal cell antibody (PCA) in serum is a biomarker of autoimmune gastritis. PCA directly recognizes the H/K ATPase expressed in parietal cells, which is responsible for the active transport of hydrogen ions in exchange for potassium ions to increase the acidity of gastric secretions. Type 1 diabetes mellitus (T1DM) mainly results from pancreatic β-cell destruction due to cell-type specific autoimmunity. Considering autoimmune factors may be the common characteristics of both PCA positivity and T1DM, it is likely that both disorders may coexist within the same patient. The main objective of this meta-analysis is to provide a reliable evaluation to clarify the association between PCA positivity and T1DM by combining the raw data from all of the relevant studies.Literature databases, including the Medline, Embase, and Web of Science, were systematically queried for studies investigating the association between PCA positivity and T1DM and were published from January 1980 to December 2014. A total of 3,584 T1DM cases and 2,650 non-T1DM controls were included in this meta-analysis, which showed that PCA positivity was more prevalent in patients with T1DM than healthy controls. Publication bias testing found no significant biases and sensitivity analysis demonstrated that our statistics were relatively stable and credible.Our findings suggested that T1DM was associated with an increased risk of PCA positivity compared to control populations.

Autoimmune mechanisms in pernicious anaemia & thyroid disease

Pernicious anaemia (PA) and some types of thyroid disease result from autoimmune processes. The autoimmune mechanisms in these conditions have not been fully elucidated. This review discusses the autoimmune mechanisms involved in PA and how these affect diagnosis and disease progression. In addition to gastric antibodies, antibodies to the vitamin B12 binding protein transcobalamin which can result in high serum B12 levels are also addressed with regard to how they affect clinical practice. The role of autoimmune susceptibility is investigated by comparing PA to one of its most common comorbidities, autoimmune thyroid disease (AITD). Thyroid disease (although not exclusively AITD) and B12 deficiency are both also implicated in the pathology of hyperhomocysteinemia, an elevated homocysteine in plasma. Since hyperhomocysteinemia is a risk factor for cardiovascular occlusive disease, this review also addresses how thyroid disease in particular leads to changes in homocysteine levels.

Single nucleotide polymorphisms related to vitamin B12 serum levels in autoimmune gastritis patients with or without pernicious anaemia

BACKGROUND

Autoimmune gastritis may present as pernicious anaemia arising from vitamin B12 malabsorption, but also with iron deficiency anaemia due to iron malabsorption. These different clinical presentations might have a genetic basis. Single nucleotide polymorphisms associated with vitamin B12 levels have not been investigated in autoimmune gastritis.

AIMS

To determine the frequency of single nucleotide polymorphisms related to vitamin B12 levels in autoimmune gastritis patients, with or without pernicious anaemia, compared to healthy controls.

METHODS

14 single nucleotide polymorphisms associated with vitamin B12 levels were selected from literature. 83 autoimmune gastritis patients (43 with and 40 without pernicious anaemia) and 173 controls were enrolled. Genomic DNA was extracted from peripheral blood leukocytes. Genotyping was performed using Sequenom MALDI-TOF mass spectrometry iPLEX platform.

RESULTS

TCN2 (rs9606756) GG genotype, related with lower vitamin B12 levels, was found in 3 (3.6%) autoimmune gastritis patients (2 with pernicious anaemia), but in none of controls (p = 0.02). FUT6 (rs3760776) AA genotype was present in four (4.8%) autoimmune gastritis patients (all pernicious anaemia) and three (1.7%) controls (p = 0.007).

CONCLUSION

A genetic variant of TCN2 (rs9606756) related to lower vitamin B12 levels was more frequent in pernicious anaemia patients compared to controls, showing the plausibility of genetic factors determining the possible clinical manifestation of autoimmune gastritis.

Relationship between Helicobacter pylori infection and vitiligo: a prospective study

BACKGROUND

Helicobacter pylori is a worldwide bacteria that may affect several extra-gastric systems, including the endocrine, hematologic, vascular, respiratory, immune, and skin. Several skin diseases, including chronic urticaria, alopecia areata, psoriasis, and systemic lupus erythematosis have been found to be associated with H. pylori infection.

AIM

To our knowledge, there are no data showing an association between H. pylori and vitiligo. Therefore, in this study, we wanted to evaluate the relationship between H. pylori and vitiligo.

METHODS

This study is a prospective study carried out in our Gastroenterology and Dermatology and Venereology departments of the Ankara Education and Research Hospital (Ankara, Turkey) between July 2013 and December 2013. Seventy-nine consecutive patients with vitiligo and 72 patients with telogen effluvium (TE) were recruited from the dermatology outpatient clinic. A total of 133 patients with vitiligo (n=68) and TE (n=65) [excluding 18 patients who had suspicious urea breath test (UBT) results] were included in the study. All individuals were tested for H. pylori IgG and CagA. Also, a UBT was performed to detect the presence of H. pylori infection.

RESULTS

There were significantly higher rates of H. pylori positivity, H. pylori CagA, and IgG in serum in the vitiligo group than in the TE group (p<0.05). The number of patients with dyspepsia was significantly higher in the vitiligo group than in the TE group. No statistically significant relationship was seen between H. pylori positivity, CagA, H. pylori IgG, dyspepsia, and the Vitiligo Disease Activity score (p>0.05). Also, when patients with vitiligo were divided into localized and generalized types of vitiligo, there was no association between vitiligo involvement pattern and H. pylori positivity, CagA, H. pylori IgG, and dyspepsia (p>0.05).

CONCLUSION

Additional studies are necessary to evaluate the effect of H. pylori eradication on the clinical course of vitiligo. Further studies are also needed to explain the relationship between H. pylori and the pathogenesis of vitiligo.

[Gastritis and gastropathy]

Alterations of the stomach mucosa in response to different adverse effects result in various morphological and clinical symptoms. Gastric mucosa alterations can be classified on the bases of diverse viewpoints. It makes this overview difficult, that identical toxic effects may cause different mucosal changes and different toxic agents may produce similar mucosal appearance. The more accurate understanding of the pathological processes which develop in the stomach mucosa needs reconsideration. The authors make an attempt to define gastritis and gastropathy in order to classify and present their features. Gastritis is a histological definition indicating mucosal inflammation. Acute gastritis is caused by infections. The two most important forms of chronic gastritis are metaplastic atrophic gastritis with an autoimmune origin and Helicobacter pylori inflammation. Gastropathy is the name of different structural alterations of the mucosa. Its most important feature is the paucity of inflammatory signs. Gastropathies can be divided into 4 categories based on the nature of the underlying pathological effect, on its morphological appearance and the way of the development. Differential diagnosis is an important pathological and clinical task because different treatment methods and prognosis.

Differential proteomics of Helicobacter pylori associated with autoimmune atrophic gastritis

Atrophic autoimmune gastritis (AAG) is a condition of chronic inflammation and atrophy of stomach mucosa, for which development can be partially triggered by the bacterial pathogen Helicobacter pylori (HP). HP can cause a variety of gastric diseases, such as duodenal ulcer (DU) or gastric cancer (GC). In this study, a comparative proteomic approach was used by two-dimensional fluorescence difference gel electrophoresis (DIGE) to identify differentially expressed proteins of HP strains isolated from patients with AAG, to identify markers of HP strain associated with AAG. Proteome profiles of HP isolated from GC or DU were used as a reference to compare proteomic levels. Proteomics analyses revealed 27 differentially expressed spots in AAG-associated HP in comparison with GC, whereas only 9 differential spots were found in AAG-associated HP profiles compared with DU. Proteins were identified after matrix-assisted laser desorption ionization (MALDI)-TOF and peptide mass fingerprinting. Some AAG-HP differential proteins were common between DU- and GC-HP (peroxiredoxin, heat shock protein 70 [HSP70], adenosine 5'-triphosphate [ATP] synthase subunit α, flagellin A). Our results presented here may suggest that comparative proteomes of HP isolated from AAG and DU share more common protein expression than GC and provide subsets of putative AAG-specific upregulated or downregulated proteins that could be proposed as putative markers of AAG-associated HP. Other comparative studies by two-dimensional maps integrated with functional genomics of candidate proteins will undoubtedly contribute to better decipher the biology of AAG-associated HP strains.

How I treat unexplained refractory iron deficiency anemia

Endoscopic gastrointestinal workup fails to establish the cause of iron deficiency anemia (IDA) in a substantial proportion of patients. In patients referred for hematologic evaluation with unexplained or refractory IDA, screening for celiac disease, autoimmune gastritis, Helicobacter pylori, and hereditary forms of IDA is recommended. About 4% to 6% of patients with obscure refractory IDA have celiac disease, and autoimmune gastritis is encountered in 20% to 27% of patients. Stratification by age cohorts in autoimmune gastritis implies a disease presenting as IDA many years before the establishment of clinical cobalamin deficiency. Over 50% of patients with unexplained refractory IDA have active H pylori infection and, after excluding all other causes of IDA, 64% to 75% of such patients are permanently cured by H pylori eradication. In young patients with a history suggestive of hereditary iron deficiency with serum ferritin higher than expected for IDA, mutations involving iron trafficking and regulation should be considered. Recognition of the respective roles of H pylori, autoimmune gastritis, celiac disease, and genetic defects in the pathogenesis of iron deficiency should have a strong impact on the current diagnostic workup and management of unexplained, or refractory, IDA.

CagA-positive Helicobacter pylori infection and reduced sperm motility, vitality, and normal morphology

Helicobacter pylori (HP) infection, particularly when caused by strains expressing CagA, may be considered a concomitant cause of male and female reduced fertility. This study explored, in 87 HP-infected males, the relationship between infection by CagA-positive HP strains and sperm parameters. HP infection and CagA status were determined by ELISA and Western blotting; semen analysis was performed following WHO guidelines. The amino acid sequence of human enzymes involved in glycolysis and oxidative metabolism were “blasted” with peptides expressed by HP J99. Thirty-seven patients (42.5%) were seropositive for CagA. Sperm motility (18% versus 32%; P < 0.01), sperm vitality (35% versus 48%; P < 0.01) and the percentage of sperm with normal forms (18% versus 22%; P < 0.05) in the CagA-positive group were significantly reduced versus those in the CagA-negative group. All the considered enzymes showed partial linear homology with HP peptides, but four enzymes aligned with four different segments of the same cag island protein. We hypothesize a relationship between infection by strains expressing CagA and decreased sperm quality. Potentially increased systemic levels of inflammatory cytokines that occur in infection by CagA-positive strains and autoimmune phenomena that involve molecular mimicry could explain the pathogenetic mechanism of alterations observed.

Autoimmune atrophic gastritis--pathogenesis, pathology and management

Autoimmune gastritis is a chronic progressive inflammatory condition that results in the replacement of the parietal cell mass by atrophic and metaplastic mucosa. A complex interaction of autoantibodies against the parietal cell proton pump and sensitized T cells progressively destroy the parietal cells, inducing hypochlorhydria and then achlorhydria, while autoantibodies against the intrinsic factor impair the absorption of vitamin B₁₂. The resulting cobalamin deficiency manifests with megaloblastic anaemia and neurological and systemic signs and symptoms collectively known as pernicious anaemia. Previously believed to be predominantly a disease of elderly women of Northern European ancestry, autoimmune gastritis has now been recognized in all populations and ethnic groups, but because of the complexity of the diagnosis no reliable prevalence data are available. For similar reasons, as well as the frequent and often unknown overlap with Helicobacter pylori infection, the risk of gastric cancer has not been adequately assessed in these patients. This Review summarizes the epidemiology, pathogenesis and pathological aspects of autoimmune metaplastic atrophic gastritis. We also provide practical advice for the diagnosis and management of patients with this disease.

Gastric parietal cell antibodies, Helicobacter pylori infection, and chronic atrophic gastritis: evidence from a large population-based study in Germany

BACKGROUND

Striking similarities between autoimmune gastritis and Helicobacter Pylori (H. pylori)-associated gastritis have suggested a potential link between these two pathologic conditions in the progression of chronic atrophic gastritis (CAG); however, evidence has remained conflicting.

METHODS

Serum pepsinogen I and II, and antibodies against H. pylori in general, the cytotoxin-associated gene A protein (CagA) and parietal cells were measured by ELISA in 9,684 subjects aged 50 to 74 years. Antigastric parietal cell antibody (APCA) prevalence was examined in the overall population and according to sex, age, and H. pylori serostatus. The association between APCA prevalence and CAG was assessed by logistic regression, overall and according to H. pylori status, controlling for potential confounding factors.

RESULTS

Overall APCA prevalence was 19.5%. APCA prevalence was strongly associated with CAG, and the association was increasing with increasing severity of CAG. Furthermore, the association between APCA and CAG was even stronger among H. pylori-negative subjects [odds ratio (OR) = 11.3; 95% confidence interval (CI): 7.5-17.1)] than among H. pylori-positive subjects (OR = 2.6; 95% CI: 2.1-3.3).

CONCLUSIONS

APCA may play a role on the development of gastric atrophy, irrespective of H. pylori infection.

IMPACT

Assessment of APCA might be a useful complement to established markers (such as pepsinogens and H. pylori antibodies) in screening for CAG.

Cutting edge issues in autoimmune gastritis

Autoimmune gastritis is the outcome of a pathological CD4 T cell-mediated autoimmune response directed against the gastric H/K-ATPase. Silent initially, the gastric lesion becomes manifest in humans by the development of megaloblastic pernicious anemia arising from vitamin B12 deficiency. Cutting edge issues in this disease relate to its epidemiology, immunogenetics, a role for Helicobacter pylori as an infective trigger through molecular mimicry, its immunopathogenesis, associated organ-specific autoimmune diseases, laboratory diagnosis, and approaches to curative therapy.

Helicobacter pylori and autoimmune diseases

It is now widely accepted that Helicobacter pylori may play a role in several extra-gastric diseases. In particular, H. pylori infection seems to be implicated in various autoimmune diseases. Many recent studies have shown a healing or an improvement in different autoimmune disorders after H. pylori eradication therapy in infected patients. The exact mechanisms behind this relationship remain under discussion, but molecular mimicry is a consistent hypothesis. This subject is particularly relevant taking into consideration the high prevalence of H. pylori infection, the existence of inexpensive and noninvasive diagnostic methods, as the urea breath test or the stool antigen test, and the low cost and toxicity of eradication treatment. If this connection becomes confirmed, it can change the diagnostic and therapeutic approach of some autoimmune diseases.

The intriguing relationship of Helicobacter pylori infection and acid secretion in peptic ulcer disease and gastric cancer

Helicobacter pylori infection induces chronic inflammation of the gastric mucosa and thus profoundly affects gastric physiology. In the acute phase of infection, gastric acid secretion is transiently impaired. The morphological damage of the gastric mucosa, changes in gastric hormone release, and disruption of neural pathways all contribute to influence gastric acid secretion in a distinct manner. Changes in gastric acid secretion, whether impaired or increased, are intimately related with the topographic phenotypes of gastritis and the presence of atrophy or absence of corpus atrophy. The interplay of gastritis phenotype and acid secretion are key determinants in disease outcomes. Corpus-predominant gastritis and corpus atrophy are accompanied by hypochlorhydria and carry the highest risk for gastric cancer, whereas antrum-predominant gastritis with little involvement of the corpus-fundic mucosa is associated with hyperchlorhydria and predisposes to duodenal ulcer disease.

Polymorphisms in chemokine and receptor genes and gastric cancer risk and survival in a high risk Polish population

OBJECTIVE

To examine if genetic variations in chemokine receptor and ligand genes are associated with gastric cancer risk and survival.

METHODS

The study included 298 cases and 417 controls from a population-based study of gastric cancer conducted in Warsaw, Poland in 1994-1996. We investigated seven single nucleotide polymorphisms in a chemokine ligand (CXCL12) and chemokine receptor (CCR2, CCR5, CX3CR1) genes and one frameshift deletion (CCR5) in blood leukocyte DNA in relation to gastric cancer risk and survival. Genotyping was conducted at the NCI Core Genotyping Facility. Odds ratios and 95% confidence intervals were computed using univariate and multivariate logistic regression models. Survival analysis was performed using Cox proportional hazards models.

RESULTS

Gastric cancer risk was not associated with single chemokine polymorphisms. A CCR5 haplotype that contained the common alleles of IVS1+151 G>T (rs2734648), IVS2+80 C>T (rs1800024) and minor allele of IVS1+246 A>G (rs1799987) was associated with a borderline significantly increased risk (OR = 1.5, 95% CI: 1.0?2.2). For gastric cancer cases, there was a greater risk of death for carriers of the minor alleles of CCR2 Ex2+241 G>A (rs1799864) (HR = 1.5, 95% CI: 1.1-2.1) and CCR5 IVS2+80 C>T (rs1800024) (HR = 1.5, 95% CI: 1.1-2.1). Carriers of the CCR5 minor allele of IVS1+151 G>T (rs2734648) had a decreased risk of death compared to homozygote carriers of the common allele (HR = 0.8, 95% CI: 0.6-1.0).

CONCLUSIONS

Our findings do not support an association between gastric cancer risk and single chemokine genetic variation. The observed associations between cancer risk and a CCR5 haplotype and between survival and polymorphisms in CCR2 and CCR5 need replication in future studies.

Pernicious anemia - genetic insights

Pernicious anemia (PA) is a complex, autoimmune, multi-factorial disease. Rapid progress has been made in the understanding of susceptibility to a spectrum of other autoimmune diseases through genome wide association studies (GWAS). However, PA has been conspicuous by its absence from this work. Here, we examine the evidence that PA has a significant heritable component through epidemiological evidence and its co-occurrence with other autoimmune diseases. Further, we consider how knowledge of the genetic susceptibility to other autoimmune diseases may provide insight into the etiology of PA.

HLA-DRB1*03 and DRB1*04 are associated with atrophic gastritis in an Italian population

BACKGROUND

Atrophic gastritis (AG) is often considered an autoimmune disorder and is associated with other autoimmune diseases. HLA-DRB1 alleles are often associated with autoimmune diseases, however HLA-DRB1 genotyping data in AG patients are lacking. The objective of the study was to evaluate the prevalence of HLA-DRB1 in AG patients.

METHODS

The occurrence of HLA-DRB1 alleles was assessed in 89 Italian AG patients (69.1% female) and 313 controls (47.3% females). Genomic DNA was extracted from peripheral venous blood, PCR-coamplified for HLA-DRB1 and typed using a reverse line-blot assay.

RESULTS

Compared to controls, prevalence of HLA-DRB1*03 (28.1% vs. 15.9%, p=0.01) and HLA-DRB1*04 (25.8% vs. 14.4%, p=0.01) was greater in AG patients, conferring an OR of 2.05 and 2.07, respectively. HLA-DRB1*01 occurred more frequently in controls than in AG patients (11.5% vs. 3.4%, p=0.01) conferring an OR of 0.27. AG patients carrying the HLA-DRB1*03 or *04 alleles were characterised by having more frequently autoimmune thyroid disease (70.4% vs. 42.2%, p=0.01) and intestinal metaplasia (86.4% vs. 62.2%, p=0.01).

CONCLUSIONS

In our population, over 50% of AG patients carry the HLA-DRB1*03 or *04 alleles associated with autoimmune diseases, suggesting that this subset of AG patients has a genetic predisposition to autoimmunity.

Cytotoxic T cells in H. pylori-related gastric autoimmunity and gastric lymphoma

Helicobacter pylori infection is the major cause of gastroduodenal pathologies, but only a minority of infected patients develop gastric B-cell lymphoma, gastric autoimmunity, or other life threatening diseases, as gastric cancer or peptic ulcer. The type of host immune response against H. pylori, particularly the cytolytic effector functions of T cells, is crucial for the outcome of the infection. T cells are potentially able to kill a target via different mechanisms, such as perforins or Fas-Fas ligand interaction. In H. pylori-infected patients with gastric autoimmunity cytolytic T cells, that cross-recognize different epitopes of H. pylori proteins and H(+)K(+)-ATPase autoantigen, infiltrate the gastric mucosa and lead to gastric atrophy via long-lasting activation of Fas ligand-mediated appotosis and perforin-induced cytotoxicity. On the other hand, gastric T cells from MALT lymphoma exhibit defective perforin- and Fas-Fas ligand-mediated killing of B cells, with consequent abnormal help for B-cell proliferation, suggesting that deregulated and exhaustive H. pylori-induced T cell-dependent B-cell activation can support both the onset and the promotion of low-grade B-cell lymphoma.

Immunogenetic characteristics of patients with autoimmune gastritis

AIM: To explore whether predisposition to autoimmune gastritis (AIG) is found in human leukocyte antigen (HLA), cytokine or killer cell immunoglobulin-like receptor (KIR) gene variations.

METHODS: Twelve Finnish patients with autoimmune-type severe atrophy of the gastric corpus were included. The patients’ serum was analyzed for pepsinogen I and Helicobacter pylori (H. pylori) antibodies. DNA was separated and the patients were genotyped for HLA-A, B, Cw, DRB1 and DQB1 antigens, and studied for single nucleotide polymorphisms for the following cytokines: interleukin (IL)-1 gene cluster, IL-2, IL-4, IL-6, IL-10, IL-12, interferon γ, transforming growth factor β, and tumor necrosis factor α. Variation in KIR genes was also explored. The results were compared with prevalence of the polymorphisms in Finnish or European populations.

RESULTS: All patients had pepsinogen I levels below normal (mean: 11 μg/L, range: < 5 to 25 μg/L). Three patients had elevated H. pylori IgG antibodies, while H. pylori serology was negative in the rest of the patients. AIG patients carried significantly more often HLA-DRB1*04 (58%) and DQB1*03 (83%) than the general Finnish population did (28% and 51%, respectively; P = 0.045 and 0.034 by the Fisher’s exact test). No patient was positive for HLA-B8-DRB1*03, a well-established autoimmune marker. Neither cytokine polymorphisms nor KIR gene variation showed association with AIG.

CONCLUSION: As explored with modern DNA-based methods, HLA-DRB1*04 and DQB1*03 alleles, but not HLA-B8-DRB1*03, may predispose to AIG.

Association of autoimmune type atrophic corpus gastritis with Helicobacter pylori infection

AIM: To study the association between Helicobacter pylori (H. pylori) infection and autoimmune type atrophic gastritis.

METHODS: Twenty-three patients with different grades of atrophic gastritis were analysed using enzyme immunoassay-based serology, immunoblot-based serology, and histology to reveal a past or a present H. pylori infection. In addition, serum markers for gastric atrophy (pepsinogen I, pepsinogen I/II and gastrin) and autoimmunity [parietal cell antibodies (PCA), and intrinsic factor (IF), antibodies] were determined.

RESULTS: Of the 14 patients with severe gastric atrophy, as demonstrated by histology and serum markers, and no evidence for an ongoing H. pylori infection, eight showed H. pylori antibodies by immunoblotting. All eight had elevated PCA and 4/8 also had IF antibodies. Of the six immunoblot-negative patients with severe corpus atrophy, PCA and IF antibodies were detected in four. Among the patients with low to moderate grade atrophic gastritis (all except one with an ongoing H. pylori infection), serum markers for gastric atrophy and autoimmunity were seldom detected. However, one H. pylori negative patient with mild atrophic gastritis had PCA and IF antibodies suggestive of a pre-atrophic autoimmune gastritis.

CONCLUSION: Signs of H. pylori infection in autoimmune gastritis, and positive autoimmune serum markers in H. pylori gastritis suggest an etiological role for H. pylori in autoimmune gastritis.

Occurrence and risk factors for autoimmune thyroid disease in patients with atrophic body gastritis

PURPOSE

To investigate the occurrence of and risk factors for autoimmune thyroid disease in atrophic body gastritis patients.

METHODS

Cross-sectional study on 401 consecutive outpatients with atrophic body gastritis. Diagnostic work-up of thyroid disease was completed in 319 atrophic body gastritis patients (225 women, median age 55.5 years [range 17-95 years]). Data on anagraphics, lifestyle, family history, and biochemical and histological items were obtained at baseline, and associations between atrophic body gastritis and autoimmune and nonautoimmune thyroid diseases were explored through descriptive statistics and logistic regression analyses.

RESULTS

Of the 319 atrophic body gastritis patients, 169 (53%) had an associated thyroid disorder, and 89 (52.7%) of these were unaware of it. The thyroid disease was autoimmune in 128 patients (75.7%) and nonautoimmune in 41 patients. Logistic regression showed that risk factors for having autoimmune thyroid disease in atrophic body gastritis patients were female sex (odds ratio [OR] 5.6, 95% confidence interval [CI], 2.6-12.1), presence of parietal cell antibodies (OR 2.5, 95% CI, 1.1-5.5), and presence of metaplastic atrophy (OR 2.2, 95% CI, 1.0-5.0).

CONCLUSIONS

Autoimmune thyroid disease and atrophic body gastritis occur in a closely linked fashion, suggesting that atrophic body gastritis patients should be investigated for an occult autoimmune thyroid disease, in particular women and those with positive parietal cell antibodies.

Is there a link between atrial fibrillation and certain bacterial infections?

The pathogenesis of atrial fibrillation (AF), the most common cardiac dysrhythmia, remains unknown. However, many recent studies point to an association between AF and inflammation because of a demonstrable significant correlation between the dysrhythmia and various biomarkers of inflammation. For example, C-reactive protein (CRP), a sensitive biomarker of systemic inflammation, has been reported to be significantly higher in patients with AF compared with a control group with no history of atrial dysrhythmias. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if the structural changes within the atria of patients with AF are a cause or consequence of the dysrhythmia. Given the suggested involvement of inflammation with this dysrhythmia, an initiating factor for inflammation has been sought. Chronic bacterial infection is the most likely event to initiate and maintain an inflammatory process. Recently, bacteria infections have been hypothesized to be involved in the pathogenesis of AF, and Helicobacter pylori and Chlamydia pneumoniae are two bacteria that have aroused interest. Here, we give a brief overview of AF and then specifically explore the recent evidence that suggests that AF may be caused by bacterial infection(s) in certain patients.

CagA and VacA are immunoblot markers of past Helicobacter pylori infection in atrophic body gastritis

BACKGROUND AND AIM

Atrophic body gastritis (ABG) may be induced by H. pylori infection. It is difficult to diagnose H. pylori infection in this condition, since during progression of body atrophy the bacterium disappears. In 30% of patients with ABG no sign of H. pylori infection is detectable. We aimed to investigate whether patients with ABG, classified as H. pylori-negative by conventional methods (ELISA serology and Giemsa stain histology), have been previously exposed to the infection.

METHODS

Case series consisted of 138 outpatients with ABG, of whom 31 are H. pylori negative (histology and ELISA serology), and 107 are H. pylori related (histology and ELISA serology positive: active infection, n = 29; only serology positive: past infection, n = 78). Thirty control subjects who were H. pylori negative at histology and ELISA serology were investigated. Immunoblotting of sera against H. pylori whole-cell protein lysate was performed.

RESULTS

None of the control sera recognized CagA, VacA, heat-shock protein B, and urease B, yielding a specificity of 100%. All H. pylori-negative patients with ABG showed immunoblotting seroreactivity, including in each case either CagA or VacA. The concomitant seroreactivity against CagA and VacA was highly prevalent in the H. pylori-negative patients with ABG, comparable to those with active infection (77.4% vs. 86.2%) and with past infection (vs. 61.5%).

CONCLUSIONS

Immunoblotting against CagA and VacA is able to prove past exposure to H. pylori infection in all patients with ABG defined as H. pylori-negative by conventional methods, suggesting a hidden role of H. pylori infection in gastric atrophy also in these patients.

Characterization of TccP-mediated N-WASP activation during enterohaemorrhagic Escherichia coli infection

Subversion of the host cell cytoskeleton is the hallmark of enterohaemorrhagic Escherichia coli (EHEC) infection. EHEC translocates the trans-membrane receptor protein Tir (translocated intimin receptor), which links the extracellular bacterium to the eukaryotic cell actin cytoskeleton, triggering formation of actin-rich pedestals beneath adherent bacteria. Tir-mediated actin accretion by EHEC requires TccP (Tir cytoskeleton coupling protein), a recently discovered type III secretion system effector protein which, following translocation, binds and activates Wiskott-Aldrich syndrome protein (N-WASP), which in turn activates the actin-related protein 2/3 complex leading to localized polymerization of actin. In this study, truncated N-WASP and TccP derivatives were generated and tested in in vitro actin polymerization and epithelial cell infection assays. The C-terminal amino acids 253-276 of the GTPase binding domain (GBD) of N-WASP were identified as essential, although not sufficient, for TccP:N-WASP protein:protein interaction, TccP-mediated N-WASP activation and induction of actin polymerization. TccP from EHEC O157:H7 strain EDL933 consists of a unique N-terminal domain and six proline-rich repeats. Progressive deletions within the N-terminus of TccP revealed that residues 1-21 are necessary and sufficient for its translocation, while amino acids 1-181, encompassing the N-terminal translocation signal and two proline-rich repeats, are sufficient for triggering actin polymerization in EHEC-infected epithelial cells and in in vitro actin polymerization assays. This study defines the modular domain structure of TccP and the molecular basis of TccP-mediated N-WASP activation and EHEC-induced remodelling of the host actin cytoskeleton.

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Is Helicobacter pylori a cause of atrial fibrillation?

Inflammation has been implicated in the pathogenesis of cardiovascular diseases. C-reactive protein, a sensitive marker of systemic inflammation, has recently been reported to be significantly higher in patients with atrial fibrillation (AF) compared with a control group with no history of atrial arrhythmia. Elevated C-reactive protein levels in patients with AF reflects an underlying inflammatory process. Histological anomalies in the atria of patients with AF have also been observed. These anomalies may have an inflammatory basis, although it is not known if any structural changes within the atria are a cause or a consequence of the arrhythmia. Ongoing chronic infection(s) has been suggested as a possible cause of the inflammatory process demonstrated in patients with AF. Helicobacter pylori, a Gram-negative bacterium more commonly known for infecting the gastric mucosa and causing peptic ulcers, is a noncardiac factor that has been controversially reported to be associated with cardiovascular diseases. This article gives a brief overview of AF and specifically explores the recent evidence that suggests that Helicobacter pylori infection causes AF.

Pathogenesis of Helicobacter pylori Infection

SUMMARY

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori .

Pathogenesis of Helicobacter pylori infection

Helicobacter pylori is the first formally recognized bacterial carcinogen and is one of the most successful human pathogens, as over half of the world's population is colonized with this gram-negative bacterium. Unless treated, colonization usually persists lifelong. H. pylori infection represents a key factor in the etiology of various gastrointestinal diseases, ranging from chronic active gastritis without clinical symptoms to peptic ulceration, gastric adenocarcinoma, and gastric mucosa-associated lymphoid tissue lymphoma. Disease outcome is the result of the complex interplay between the host and the bacterium. Host immune gene polymorphisms and gastric acid secretion largely determine the bacterium's ability to colonize a specific gastric niche. Bacterial virulence factors such as the cytotoxin-associated gene pathogenicity island-encoded protein CagA and the vacuolating cytotoxin VacA aid in this colonization of the gastric mucosa and subsequently seem to modulate the host's immune system. This review focuses on the microbiological, clinical, immunological, and biochemical aspects of the pathogenesis of H. pylori.

Helicobacter pylori phase variation, immune modulation and gastric autoimmunity

Helicobacter pylori can be regarded as a model pathogen for studying persistent colonization of humans. Phase-variable expression of Lewis blood-group antigens by H. pylori allows this microorganism to modulate the host T-helper-1-cell versus T-helper-2-cell response. We describe a model in which interactions between host lectins and pathogen carbohydrates facilitate asymptomatic persistence of H. pylori. This delicate balance, favourable for both the pathogen and the host, could lead to gastric autoimmunity in genetically susceptible individuals.

Long-term acid suppression by omeprazole in gastro-oesophageal reflux disease patients does not lead to anti-gastric autoantibody production

BACKGROUND

Helicobacter pylori-associated atrophy of the gastric corpus is associated with the presence of anti-canalicular autoantibodies. Also, long-term profound acid suppression in H. pylori-infected subjects may cause atrophic corpus gastritis.

AIM

To investigate whether long-term acid suppression by omeprazole leads to antigastric autoantibodies.

METHODS

Fifty patients, of which 34 H. pylori-positive on entry of the study, were treated with omeprazole (20-40 mg once daily) for reflux oesophagitis, and were evaluated for anti-gastric autoantibody responses by immunohistochemistry before and after treatment. H. pylori was not eradicated and patients were followed for an average of 6.6 years (range 3-14.1 years). In addition to immunohistochemistry, anti-H(+), K(+)-ATPase reactivity was assessed by Western blot in paired sera of 41 patients (26 H. pylori-positive and 15 uninfected) and results are critically evaluated.

RESULTS

In immunohistochemistry, all patients were negative for anti-canalicular autoantibodies when omeprazole therapy started, except for two patients with corpus-predominant gastritis in the presence of H. pylori. One patient, who was H. pylori-negative, newly developed an anti-canalicular antibody response during therapy.

CONCLUSIONS

Our results indicate that, as compared with non-infected patients, long-term profound acid suppression therapy in H. pylori-infected gastro-oesophageal reflux disease patients does not increase or accelerate gastric autoimmunity.