Role of antigastric autoantibodies in chronic Helicobacter pylori infection

Identification of Autoantigens in Pediatric Gastric Juices

Purpose

This study aimed to investigate the presence of autoantigens in the gastric juices of children.

Methods

Gastric juice and serum samples were obtained from 53 children <15 years of age who underwent gastric endoscopy. Among these, 8, 22, and 23 participants were in the age groups 0-5, 6-10, and 11-15 years, respectively. These samples were analyzed using two-dimensional electrophoresis (2-DE), immunoblot analysis, and matrix-assisted laser desorption ionization-time of-flight mass spectrometry. Furthermore, we reviewed the histopathological findings and urease test results and compared them with the results of 2-DE and immunoblot analysis.

Results

There were no statistically significant differences in urease test positivity, grades of chronic gastritis, active gastritis, or Helicobacter pylori infiltration of the antrum and body among the three age groups. Three distinct patterns of gastric juice were observed on 2-DE. Pattern I was the most common, and pattern III was not observed below the age of 5 years. Histopathological findings were significantly different among active gastritis (p=0.037) and H. pylori infiltration (p=0.060) in the gastric body. The immunoblots showed large spots at an approximate pH of 3-4 and molecular weights of 31-45 kDa. These distinct, large positive spots were identified as gastric lipase and pepsin A and C.

Conclusion

Three enzymes, which are normally secreted under acidic conditions were identified as autoantigens. Further investigation of the pathophysiology and function of autoantigens in the stomach is required.

Gastritis: The clinico-pathological spectrum

The inflammatory spectrum of gastric diseases includes different clinico-pathological entities, the etiology of which was recently established in the international Kyoto classification. A diagnosis of gastritis combines the information resulting form the gross examination (endoscopy) and histology (microscopy). It is important to consider the anatomical/functional heterogeneity of the gastric mucosa when obtaining representative mucosal biopsy samples. Gastritis includes self-limiting and non-self-limiting (long-standing) inflammatory diseases, and the latter are epidemiologically, biologically and clinically linked to the onset of gastric cancer (i.e. "inflammation-associated cancer"). Different biological models of inflammation-associated gastric oncogenesis have been proposed. Helicobacter pylori (H. pylori) gastritis is the most prevalent worldwide, and H. pylori is classified as a first-class carcinogen. On these bases, eradicating H. pylori is mandatory for the primary prevention of gastric cancer. Non-self-limiting gastritis may also be triggered by the immune-mediated destruction of gastric parietal cells, resulting in autoimmune gastritis. In both H. pylori-related and autoimmune gastritis, the non-self-limiting inflammation results in atrophy of the gastric mucosa, which is the main factor promoting gastric cancer. Long-term follow-up studies consistently demonstrate the prognostic impact of the histological staging of gastritis in gastric cancer secondary prevention strategies.

Autoimmune atrophic gastritis: The role of Helicobacter pylori infection in children

BACKGROUND

Autoimmune atrophic gastritis (AIG) is very rare in children. Despite a better understanding of histopathologic changes and serological markers in this disease, underlying etiopathogenic mechanisms and the effect of Helicobacter pylori (H pylori) infection are not well known. We aimed to investigate the relation between AIG and H pylori infection in children.

MATERIALS AND METHODS

We evaluated the presence of AIG and H pylori infection in fifty-three patients with positive antiparietal cell antibody (APCA). Demographic data, clinical symptoms, laboratory and endoscopic findings, histopathology, and presence of H pylori were recorded.

RESULTS

The children were aged between 5 and 18 years, and 28 (52.8%) of them were male. Mean age was 14.7 ± 2.6 years (median: 15.3; min-max: 5.2-18), and 10 (18.8%) of them had AIG confirmed by histopathology. In the AIG group, the duration of vitamin B12 deficiency was longer (P = .022), hemoglobin levels were lower (P = .018), and APCA (P = .039) and gastrin (P = .002) levels were higher than those in the non-AIG group. Endoscopic findings were similar between the two groups. Intestinal metaplasia was higher (P = .018) in the AIG group. None of the patients in the AIG group had H pylori infection (P = .004). One patient in the AIG group had enterochromaffin-like cell hyperplasia.

CONCLUSIONS

Our results show that, in children, H pylori infection may not play a role in AIG. AIG could be associated with vitamin B12 deficiency, iron deficiency, and APCA positivity in children. APCA and gastrin levels should be investigated for the early diagnosis of AIG and intestinal metaplasia.

Insights Into Pediatric Autoimmune Gastritis: Is There a Role for Helicobacter pylori Infection?

OBJECTIVES

Autoimmune gastritis (AIG) is a chronic inflammatory condition of the gastric mucosa, mainly described in adults presenting with pernicious anemia. It results from antibody-mediated destruction of parietal cells, but the precise initiating event is unknown. The pathogenicity of Helicobacter pylori (H pylori) has been suggested but not established. This study aimed to better characterize AIG in pediatric patients and to address the possible role of H pylori infection.

METHODS

Descriptive single-center study, retrospectively describing 20 patients with a diagnosis of AIG based on positivity for anti-parietal cell autoantibodies, in addition to analytical and/or histological findings of oxyntic mucosa atrophy.

RESULTS

In the majority (18/20), AIG diagnosis was suggested during investigation of refractory iron-deficient anemia. One patient had dyspepsia and none of the others had gastrointestinal symptoms. Fifty-five percent (11/20) were H pylori positive, but there were no significant differences regarding mean hemoglobin values at presentation (10.6 ± 2.5 vs 9.5 ± 1.0 g/dL, P > 0.05), analytical indicators of gastric atrophy (gastrin, 564.4 ± 184 vs 721.2 ± 220.6 pg/mL, P > 0.05), or in the presence or the grade of oxyntic mucosa atrophy.

CONCLUSIONS

Our findings highlight that AIG may have an age-dependent presentation; thus, we can consider a pediatric phenotype that in contrast to adults, is manifested by refractory iron-deficient anemia and associated with parietal cell autoantibody positivity, but not intrinsic factor autoantibodies. A correlation between H pylori and AIG was not evident in the current study and it is still unclear whether H pylori is a trigger for AIG.

Thyro-gastric autoimmunity in patients with differentiated thyroid cancer: a prospective study

Thyro-gastric autoimmunity has not been previously evaluated in patients with differentiated thyroid cancer (DTC), although its long-term complications may be relevant for the management of DTC patients. We assessed the prevalence of gastric autoimmunity and autoimmune gastritis (AG) in patients with Hashimoto's thyroiditis (HT) and concomitant DTC. Prevalence of parietal cell antibody (PCA) positivity, iron deficiency anemia (IDA), and pernicious anemia (PA) were prospectively assessed in 150 DTC patients referred for radioiodine ablation after total thyroidectomy. Patients were classified as HT (n = 31) and non-HT (n = 119) based on a combination of serological, ultrasonographic, and histological findings. Patients with PCA positivity were subsequently addressed to endoscopy for confirmation of atrophy body gastritis, required for the diagnosis of AG. For all the variables under study, a comparison between groups was made using Fisher's exact test and appropriate parametric and non-parametric tests. PCA positivity was significantly more prevalent in HT than in non-HT patients (12.9 vs 1.6 %, p = 0.017). After Hp eradication, a reversal of PCA positivity was observed in 3/4 patients in the HT group. IDA and PA did not differ significantly between groups. In the HT group, only one patient had endoscopical confirmation of mild gastric corporal atrophy. Gastric autoimmunity shows higher prevalence in patients with DTC and concomitant HT than in patients with DTC alone; however, in most cases, PCA positivity was associated with Hp infection. Furthermore, although previous reports found up to one-third of patients with HT to have associated AG, in our cohort AG was extremely rare.

Gastric autoantigenic proteins in Helicobacter pylori infection

PURPOSE

This study tried to identify novel gastric autoimmune antigens that might be involved in aggravating the atrophic gastritis among patients with Helicobacter pylori infection using two-dimensional immunoblotting analysis.

MATERIALS AND METHODS

Proteins from gastric mucosal antrectomy specimens and AGS cells (gastric adenocarcinoma cell lines derived from a Caucasian patient who had received no prior therapy) were 2-dimensionally immunoblotted separately with a pool of 300 sera from H. pylroi-infected patients at Gyeongsang National University Hospital.

RESULTS

Thirty-eight autoantigenic proteins including alcohol dehydrogenase [NADP+], alpha enolase, gastrokine-1, gastric triacylglycerol lipase, heat shock 70 kDa protein 1, and peroxiredoxin-2 were identified in the gastric mucosal tissue. Fourteen autoantigenic proteins including programmed cell death 6-interacting protein, serum albumin and T-complex protein 1 subunit gamma were identified in the AGS cells. Albumin, alpha-enolase, annexin A3, cytoplasmic actin 1, heat shock cognate 71 kDa protein and leukocyte elastase inhibitor were commonly observed autoantigenic proteins in both gastric mucosal tissue and AGS cells. Alpha-enolase, glutathione S-transferase P, heat shock cognate 71 kDa protein, heat shock 70 kDa protein 1, human mitochondrial adenosine triphosphate synthase (ATP) subunit beta, mitochondrial 60 kDa heat shock protein, peroxiredoxin-2, 78 kDa glucose-regulated protein precursor, tyrosine-protein phosphatase non-receptor type 11 and Tryptophan-Aspartic acid (WD) repeat-containing protein 1 showed 60% or higher amino acid positivity.

CONCLUSION

These newly identified gastric autoimmune antigens might be useful in the control and prevention of gastroduodenal disorders, and might be valuable in breaking the vicious circle that exists in gastroduodenal disorders if their pathophysiological roles could be understood in the progress of chronic atrophic gastritis, gastroduodenal ulcers, intestinal metaplasia, and gastric carcinogenesis.

The Story So Far:Helicobacter Pyloriand Gastric Autoimmunity

The gastric mucosal pathogen Helicobacter pylori induces autoantibodies directed against the gastric proton pump H+,K+-ATPase in 20-30% of infected patients. The presence of these autoantibodies is associated with severity of gastritis, increased atrophy, and apoptosis in the corpus mucosa, and patients with these autoantibodies infected with H. pylori display histopathological and clinical features that are similar to those of autoimmune gastritis (AIG). This review will focus on the T helper cell responses, cytokines, and adhesion molecules involved in corpus mucosal atrophy in chronic H. pylori gastritis and in AIG, and the role of H. pylori in the onset of AIG.

Natural history of Helicobacter pylori infection

This report describes the modalities of chronic gastritis induced by Helicobacter pylori infection in different populations. The full gamut of lesions representing the precancerous cascade is very prevalent in populations of low socioeconomic background experiencing very high gastric cancer risk, as seen in the Latin American Andes Mountains. In populations of high socioeconomic standards and high cancer risk, such as Japan and Korea, the precancerous cascade predominates and "early" cancers are also diagnosed frequently. Some reports describe frequent corpus atrophy, not prominent in the former group. The so-called African enigma is seen in populations of low socioeconomic standards, usually living at low altitudes, with high prevalence of infection but low frequency of cancer and precancerous lesions. In populations in transition from high to low cancer risk, duodenal ulcer and antral non-atrophic gastritis are frequently seen. In affluent societies at low risk of cancer, such as Western Europe, Australia and North America, mild non-atrophic gastritis associated with low virulence Helicobacter pylori genotypes predominate. The varied phenotypes of gastritis may reflect secular changes in the ecology of our species.

Helicobacter felis-induced gastritis was suppressed in mice overexpressing thioredoxin-1

Thioredoxin-1 (TRX-1) is a redox-active protein involved in scavenging reactive oxygen species and regulating redox-sensitive transcription factors. TRX-1 is induced in various inflammatory conditions and shows cytoprotective action. We investigated the roles of TRX-1 in the host defense mechanism against Helicobacter felis (H. felis) infection. Transgenic (TG) mice overexpressing human TRX-1 and wild-type (WT) mice were orally inoculated with H. felis. After 2 months, histology, oxidative damage, and gene expression of several cytokines, including macrophage inflammatory protein-2 (MIP-2), a murine equivalent to interleukin (IL)-8, in the gastric mucosa were investigated. Furthermore, the effects of TRX-1 on oxidative stress and neutrophil migration were studied both in vivo and in vitro. The gastric mucosa was thickened in H. felis-infected WT mice, but not in infected TRX-1-TG mice. Histologically, all H. felis-infected WT mice developed moderate-to-severe gastritis, whereas the development of gastritis was significantly suppressed in infected TRX-1-TG mice. Oxidative damage markers, 8-hydroxy-2'-deoxyguanosine and malondialdehyde, increased in the stomach of infected WT mice, but not TRX-1-TG mice. Upregulation of IL-1beta and tumor necrosis factor-alpha gene expression in H. felis-infected TRX-1-TG mice was significantly lower than in WT mice. However, upregulation of MIP-2 and IL-7 was not different between the two groups. TRX-1 suppressed oxidative cytotoxicity and DNA damage, and inhibited neutrophil migration both in vivo and in vitro. The present study suggests that overexpression of TRX-1 suppresses H. felis-induced gastritis by inhibiting chemotaxis of neutrophils and reducing oxidative stress.

Apoptosis and autoimmunity as proposed pathogenetic links between Helicobacter pylori infection and idiopathic achalasia

Achalasia is a disorder of the oesophagus characterised by increased lower oesophageal sphincter (LOS) tone, lack of LOS relaxation with swallowing and aperistalsis of the body of the oesophagus. The aetiology and pathogenesis of idiopathic achalasia are still unclear, although a viral cause, genetic influences (associations with HLA loci) and autoimmune processes have been postulated. Degeneration and significant loss of nerve fibres, associated with an inflammatory infiltrate of the myenteric plexus in idiopathic achalasia, provide evidence of an immune mediated destruction of the myenteric plexus, possibly through apoptotic process. This concept is reinforced by the concomitant appearance of achalasia and Guillain-Barré syndrome (GBS) and/or Parkinson's disease, where inappropriate initiation of apoptosis has been proposed to underlie the neuronal attrition. In the same respect, Helicobacter pylori (H. pylori) infection has been associated with gastric autoimmunity, and patients infected with H. pylori have been shown to possess autoantibodies that cross-react with antigens expressed on the gastric mucosa. Furthermore, H. pylori is thought to be associated with the development of autoimmune sequelae observed in peripheral neuropathies and GBS, where autoantibodies to specific neural targets have been found to impair native neural function by inducing nerve tissue damage, possibly by apoptosis. Taken together, we assume that H. pylori infection might be a pathogenetic factor of achalasia through induction of autoimmunity and apoptosis. Whether eradication of H. pylori infection may indirectly offer benefit to the pathophysiology of idiopathic achalasia by ameliorating the apoptotic loss of ganglion cells and their axons in the oesophageal wall remains to be elucidated.

Detection of Helicobacter ganmani-like 16S rDNA in pediatric liver tissue

BACKGROUND

To determine the presence of Helicobacter species in the liver biopsy specimens from children with various chronic liver diseases as data in adult literature suggests a possible role of these bacteria in their pathogenesis.

MATERIALS AND METHODS

Paraffin sections of 61 liver biopsies of pediatric patients with miscellaneous diseases and autopsy liver tissue from 10 control subjects with no evidence of preexisting liver disease were examined for the presence of Helicobacter species by a genus-specific seminested polymerase chain reaction (PCR) assay. PCR-products of positive samples were further characterized by denaturing gradient gel electrophoresis (DGGE) and DNA-sequence analysis. Based on those results, a seminested PCR assay for H. ganmani was developed and applied to the samples.

RESULTS

On analysis, 40/61 patient samples were positive in the genus-specific Helicobacter PCR and 4/10 from the control group. The nucleotide sequences of 16S rDNA fragments were 99-100% similar to mainly Helicobacter sp. 'liver' and H. ganmani. PCR-products similar to H. canis and H. bilis were also found. The 16S rDNAs of control specimens showed similarity to Helicobacter sp. 'liver'. In the H. ganmani-specific PCR analysis 19 patients, but none of the controls, were positive.

CONCLUSIONS

Amplified Helicobacter 16S rDNAs were related to Helicobacter sp. 'liver' or H. ganmani in liver biopsy specimens of pediatric patients. The possible significance of Helicobacter species in pediatric liver diseases needs to be evaluated further in prospective studies.

Hepatitis E, Helicobacter pylori, and gastrointestinal symptoms in workers exposed to waste water

BACKGROUND

Workers exposed to sewage may have an increased risk of infection by Helicobacter pylori and hepatitis E virus (HEV).

AIMS

To assess the prevalence of clinical hepatitis E (HE) and peptic ulcer disease as well as the seroprevalence of antibodies to H pylori and HEV in workers with and without sewage exposure and to look for symptoms due to exposure to endotoxin.

METHODS

In the first year of a prospective cohort study 349 sewage exposed workers and 429 municipal manual workers (participation: 61%) underwent a complete medical examination. Travelling to endemic areas, socioeconomic level, age, country in which childhood was spent, and number of siblings were considered as the main confounding factors.

RESULTS

Peptic ulcer disease and clinical HE did not occur more often in workers exposed to sewage. Prevalence of antibodies to HEV was 3.3% and overall prevalence of IgG antibodies to H pylori was 42% with large differences between subgroups. Logistic regression did not show an increased risk of seropositivity or antibodies to parietal cells in sewage exposed workers, but disentangling the effect of exposure from that of confounders was extremely difficult. No increase of symptoms due to exposure to endotoxin was found in sewage workers, with the exception of diarrhoea.

CONCLUSIONS

No clear increased risk of infection by H pylori or by HEV in workers exposed to sewage was found in this cross-sectional study, but these results need to be confirmed by follow up.

Gastritis and carditis

Dyspepsia is a common clinical problem. Its causes include peptic ulcer disease, gastroesophageal reflux, and functional (nonulcer) dyspepsia. A detailed clinical description of pain does not reliably differentiate the cause. Approximately 80% of gastroscopies are performed for the investigation of dyspepsia. "Gastritis" is diagnosed endoscopically in 59% of all stomachs, although in only 3% are the changes severe. Pathologic examination of unselected gastric biopsy specimens reveals that abnormalities are present in 62-73%, but there is only a weak correlation between endoscopic and histologic findings. For these reasons, it is recommended that endoscopic examination should always be accompanied by biopsy. Ideally, biopsies should be taken in a systematic fashion to include sampling of antrum and corpus. Recent evidence suggests that gastric infection by Helicobacter pylori initially presents as a superficial gastritis. Later it may become atrophic with development of intestinal metaplasia. The onset of atrophic changes may be related to the duration of infection, the strain of the infecting organism, associated dietary factors, or as-yet undefined host factors related to immunity. Persistent superficial gastritis predisposes to duodenal ulcer and gastric mucosa-associated lymphoid tissue lymphoma. Atrophic gastritis predisposes to gastric ulcer and adenocarcinoma. Evidence is accumulating that in some patients, pernicious anemia may be an end result of H. pylori-induced atrophic gastritis. Reactive gastropathy is a relatively common finding in gastric biopsies; in most instances it is associated with either reflux of duodenal contents or therapy with nonsteroidal anti-inflammatory drugs. Lymphocytic gastritis, eosinophilic gastritis, and the gastritis associated with Crohn's disease are distinct morphologic entities. Lymphocytic gastritis and eosinophilic gastritis have a variety of clinical associations. Carditis is a controversial topic: currently opinions are divided as to whether it is the result of gastroesophageal reflux or a proximal extension of H. pylori infection from the remainder of the stomach.

Helicobacter pylori infection in skin diseases: a critical appraisal

More than 50% of the human population have long-term Helicobacter pylori infection, causing, in some cases, severe diseases such as peptic ulcers and stomach cancer. In the last few years several extra-gastrointestinal disorders have been associated with H. pylori infection. This review summarized the current medical literature, identified through hand searching and MEDLINE research, including our own studies, with regard to H. pylori and skin diseases. From the literature it can be seen that the role of H. pylori in skin diseases is still a controversial subject. Randomized controlled trials with adequate masking and sample sizes are still lacking. The best evidence comes from studies investigating chronic urticaria in which chronic urticaria disappeared in many patients with H. pylori infection after careful eradication of the H. pylori. Moreover, there are promising recent reports of beneficial H. pylori eradication in Behçet's disease, pruritus cutaneus, prurigo chronica, prurigo nodularis and in some patients with lichen planus, but not in rosacea or psoriasis. Before any conclusions with respect to other skin diseases such as atopic dermatitis, Schoenlein-Henoch Purpura, Sweet's syndrome, Sjögren syndrome or systemic sclerosis may be drawn, additional randomized, double-blinded and placebo-controlled studies including adequate diagnostic schedules, sufficient eradication treatment protocols, confirmation of eradication and adequate control groups are needed. The cutaneous pathology of H. pylori is far from being clear, but it is speculated that the systemic effects may involve increased mucosal permeability to alimentary antigens, immunomodulation, an autoimmune mechanism or the impairment of vascular integrity.

Generation and characterization of human monoclonal scFv antibodies against Helicobacter pylori antigens

Infection with Helicobacter pylori is chronic despite a vigorous cellular and humoral immune response and causes severe pathology in some patients. In this study, phage display was used as a new approach in order to investigate the role of the host's humoral immune response in the pathogenesis of H. pylori gastritis. Human monoclonal single-chain Fv (scFv) antibody fragments against H. pylori cell lysate and the H. pylori urease were isolated from an immune phage display library, constructed from peripheral blood lymphocytes of an H. pylori-infected patient. After affinity selection, 23% of the clones tested showed binding activity against a lysate of the H. pylori Sydney strain in enzyme-linked immunosorbent assay (ELISA) and 9% bound the H. pylori urease. Further characterization by PCR-fingerprint analysis and sequencing revealed that two closely related H. pylori binders and one antiurease scFv could be isolated. The selected scFvs were highly specific as analyzed by ELISA and immunoblots using various bacterial lysates and recombinant proteins. Analysis of the humoral immune response following H. pylori infection using human monoclonal antibodies might contribute to a better understanding of the pathogenesis of the disease. Moreover, using immune phage display libraries, it might be possible for relevant epitopes of H. pylori antigens to be determined, which might be of use for vaccine development.

Are lymphocytic monoclonality and immunoglobulin heavy chain (IgH) rearrangement premalignant conditions in chronic gastritis?

Normal gastric mucosa is devoid of lymphoid cells. Any increase of lymphocytes suggests chronic inflammation. Infection with Helicobacter pylori (Hp) is the major cause for nonautoimmune chronic gastritis and induces a mixed cellular response resulting in an acquired lymphoid tissue, or MALT (mucosa-associated lymphoid tissue). Hp has also been implicated in the genesis of gastric MALT-lymphoma. Polymerase chain reaction-based assays to detect the expansion of monoclonal B-cells have also been used to corroborate the diagnosis. In a considerable number of cases monoclonal B-cells remain detectable in follow-up biopsies, with the lymphoma being in complete histological remission. The clinical relevance of this finding is not clear yet. However, there also exist different reports that monoclonal B-cells can be found in gastric biopsies of patients with neither a histological sign nor a present or past history of lymphoma. In the light of these findings we address the question whether B-cell monoclonality can be seen as a premalignant condition in chronic gastritis and conclude that as of now the relevance of the finding of B-cell monoclonality remains unclear. As of now the only and gold standard for the diagnosis of gastric MALT-lymphoma is histopathology.

Gastric mucosal morphological consequences of acid suppression: a balanced view

In the chapter, an analysis of the literature on the relationship between Helicobacter pylori, the use of proton pump inhibitors and the development of atrophic gastritis is presented, and the difficulties of classifying gastritis and the new possibilities of quantifying chronic inflammation by morphometric analysis are discussed. The issue surrounding the necessity of eradicating H. pylori in H. pylori-positive patients has still not been solved. Most studies have now accepted that proton pump inhibitors indeed accelerate the onset of atrophic gastritis in H. pylori-positive patients, but evidence against such an association was published in one recent (Scandinavian) study; conclusions from this study have, however, been challenged by several groups. Some data are available on the efficacy of H. pylori eradication with regard to the prevention of atrophy. The limited significance of the development of parietal cell protrusions and fundic gland cysts is better understood, but much less is known of the development and long-term consequence of H. pylori-induced autoimmune gastritis. Finally, recent studies in H. pylori-positive patients indicate that treatment with proton pump inhibitors may promote bacterial N-nitrosation formation. These data taken together suggest that the eradication of H. pylori may be based not only on morphological arguments, but also on bacterial alterations in the gastric milieu.