Mucosal production of antigastric autoantibodies in Helicobacter pylori gastritis

Clinical characteristics and outcomes of pediatric patients with autoimmune gastritis

OBJECTIVES

Autoimmune gastritis (AIG) is a rare chronic inflammatory disorder with potential long-term sequelae including gastric neoplasia. There is limited data on the natural history of pediatric AIG. We aimed to characterize the clinical course and outcomes of children with AIG.

METHODS

This was a multicenter retrospective study that included pediatric patients diagnosed with AIG between January 1, 2000 and December 31, 2021. Diagnosis of AIG was based on the demonstration of histological corpus-predominant atrophic gastritis, with or without positive antiparietal cell (APCA) or anti-intrinsic factor (IF) antibodies. Demographic, clinical, laboratory, endoscopic, and histologic data were retrieved, along with follow-up data.

RESULTS

Thirty-three patients, (23 females, [69.7%], median age 12.0 [interquartile range 7.0-15.0] years at diagnosis) were identified. Twenty-two patients (66.7%) had positive APCA and/or anti-IF serology. The most common presenting manifestation was iron deficiency anemia (75%), and accompanying autoimmune disorders were significantly more common in patients with positive serology (62% vs. 18%, p < 0.05). Pseudo-pyloric or intestinal-type metaplasia was present at diagnosis in eight patients (24%), and 11 additional patients (33%) developed metaplasia during a median follow-up time of 27 (17.5-48.3) months. One patient developed a type 1 gastric neuroendocrine tumor. Helicobacter pylori was identified in only one patient, while two patients had prior eradication. Endoscopic and histologic improvements weren't identified in any patients.

CONCLUSIONS

AIG should be considered in patients with autoimmunity and resistant iron-deficiency anemia. H. pylori infection may not be associated with pediatric AIG. The development of neuroendocrine tumor in one patient, and the high rates of metaplasia, highlight the importance of surveillance.

Helicobacter pylori seropositivity is associated with antinuclear antibodies in US adults, NHANES 1999-2000

Infectious diseases, such as Helicobacter pylori, which produce systemic inflammation may be one key factor in the onset of autoimmunity. The association between H. pylori and antinuclear antibodies (ANA), a marker of autoimmunity, has been understudied. Data from the 1999–2000 National Health and Nutrition Examination Survey were used to evaluate the cross-sectional association between H. pylori seroprevalence and ANA positivity in US adults aged ≥20 years. ANA was measured in a 1:80 dilution of sera by indirect immunofluorescence using HEp-2 cells (positive ⩾3). H. pylori immunoglobulin G enzyme-linked immunosorbent assays were used to categorise individuals as seropositive or seronegative. H. pylori seropositivity and ANA positivity were common in the adult US population, with estimated prevalences of 33.3% and 9.9%, respectively. Both were associated with increasing age. H. pylori seropositivity was associated with higher odds of ANA (prevalence odds ratio = 1.89, 95% confidence interval = 1.08–3.33), adjusted for age, sex, race/ethnicity, educational attainment and body mass index. H. pylori infection may be one key factor in the loss of self-tolerance, contributing to immune dysfunction.

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.

Immune evasion strategies used by Helicobacter pylori

Helicobacter pylori (H. pylori) is perhaps the most ubiquitous and successful human pathogen, since it colonizes the stomach of more than half of humankind. Infection with this bacterium is commonly acquired during childhood. Once infected, people carry the bacteria for decades or even for life, if not treated. Persistent infection with this pathogen causes gastritis, peptic ulcer disease and is also strongly associated with the development of gastric cancer. Despite induction of innate and adaptive immune responses in the infected individual, the host is unable to clear the bacteria. One widely accepted hallmark of H. pylori is that it successfully and stealthily evades host defense mechanisms. Though the gastric mucosa is well protected against infection, H. pylori is able to reside under the mucus, attach to gastric epithelial cells and cause persistent infection by evading immune responses mediated by host. In this review, we discuss how H. pylori avoids innate and acquired immune response elements, uses gastric epithelial cells as mediators to manipulate host T cell responses and uses virulence factors to avoid adaptive immune responses by T cells to establish a persistent infection. We also discuss in this review how the genetic diversity of this pathogen helps for its survival.

Role of Helicobacter pylori and autoimmunity in serological atrophic corpus gastritis in a Dutch primary care community

BACKGROUND

Atrophic corpus gastritis predisposes to vitamin B12 deficiency and gastric cancer. Little is known about the seroprevalence of atrophic corpus gastritis in the general population of Western Europe.

AIM

To investigate the seroprevalence of atrophic corpus gastritis in a West-European primary care community in relation to Helicobacter pylori infection and autoimmunity.

METHODS

Nine hundred and ninety-seven consecutive persons attending one general practice were asked to participate in the study by completing a questionnaire and donating fasting blood. Gastrin, pepsinogen A and C, and antibodies to H. pylori and parietal cells were measured by well-validated immunological methods. Criteria for serological atrophic corpus gastritis were pepsinogen A < 17 microg/l, pepsinogen A/C ratio <1.6, and gastrin >100 ng/l.

RESULTS

Thirty-four participants (3.4%) fulfilled the serological criteria of atrophic corpus gastritis. Twenty-one of them (62%) and 17 of 34 (50%) age-matched and sex-matched nested controls were H. pylori positive [NS; odds ratio, 1.62 (0.62-4.24)], while 15 of them (44%) and one of 34 controls had antibodies to parietal cells [P < 0.005; odds ratio, 24.0 (3.00-201)].

CONCLUSIONS

The seroprevalence of atrophic corpus gastritis in this primary care community is 3.4%. When compared with controls, the approximate relative risk of having atrophic corpus gastritis was significantly higher (P < 0.025) for antibodies to parietal cells (24.0) than to H. pylori (1.62). In view of the decreasing risk of H. pylori infection in the western world, it is likely that the impact of H. pylori on the development of atrophic corpus gastritis will further diminish.

CD4+ CD25+ regulatory T cells modulate the T-cell and antibody responses in helicobacter-infected BALB/c mice

Gastric Helicobacter spp. induce chronic gastritis that may lead to ulceration and dysplasia. The host elicits a T helper 1 (Th1) response that is fundamental to the pathogenesis of these bacteria. We analyzed immune responses in Helicobacter-infected, normal mice depleted of CD4+ CD25+ T cells to investigate the in vivo role of regulatory T cells (Tregs) in the modulation of Helicobacter immunopathology. BALB/c and transgenic mice were depleted of CD4+ CD25+ T cells by administration of an anti-CD25 antibody either at the time of infection with Helicobacter or during chronic infection and gastritis. Depletion of CD25+ Tregs prior to and during infection of mice with Helicobacter spp. did not affect either bacterial colonization or severity of gastritis. Depletion of CD25+ Tregs was associated with increased Helicobacter-specific antibody levels and an altered isotype distribution. Paragastric lymph node cells from CD25+ Treg-depleted and control infected mice showed similar proliferation to Helicobacter antigens, but only cells from anti-CD25-treated animals secreted Th2 cytokines. CD25+ Tregs do not control the level of gastritis induced by gastric Helicobacter spp. in normal, thymus-intact BALB/c mice. However, CD25+ Tregs influence the cytokine and antibody responses induced by infection. Autoimmune gastritis is not induced in Helicobacter-infected mice depleted of CD25+ Tregs but is induced in CD25+ Treg-depleted mice, which have a higher frequency of autoreactive T cells.

Long-term infection of Mongolian gerbils with Helicobacter pylori: microbiological, histopathological, and serological analyses

The effects of long-term infection with Helicobacter pylori on the gastric mucosa of Mongolian gerbils were examined. Colonization by H. pylori was evaluated by both microaerobic cultivation and real-time reverse transcriptase PCR (RT-PCR). Persistent infection with H. pylori in gastric mucosa was detected by real-time RT-PCR during 6 months after infection, but no H. pylori was isolated 4 months after infection by cultivation. Infiltration with neutrophils and mononuclear cells was observed from 2 months after infection. Both intestinal metaplasia and gastric atrophy were also detected from 2 months after infection. The results by enzyme-linked immunosorbent assay indicated that antibody titers against whole H. pylori antigens, H. pylori heat shock protein 60 (HSP60), and Escherichia coli GroEL were significantly higher in the infected gerbils than in noninfected gerbils. After long-term infection with H. pylori for 18 months, marked atrophy of gastric mucosa and multiple cysts in the submucosa were observed in the glandular stomach of the infected gerbils. In addition, squamous cell papilloma with hyperkeratosis was observed in cardia of all the infected gerbils. These results indicate that evaluation of bacterial colonization during long-term infection can be done by real-time RT-PCR and that mucosal damage might be induced by host immune response against whole H. pylori antigen.

Helicobacter pylori infection and gastric autoimmune diseases: is there a link?

BACKGROUND

Helicobacter pylori is thought to be involved in atrophic body gastritis. We explored the prevalence of H. pylori infection in asymptomatic subjects with gastric parietal cell antibodies, as well as in patients with pernicious anemia, to evaluate a possible role of H. pylori gastric infection in gastric autoimmunity.

PATIENTS AND METHODS

We studied 79 consecutive asymptomatic subjects with parietal cell antibodies, 24 patients with pernicious anemia, and 66 parietal cell antibody-negative controls. All patients underwent gastric biopsies for histology and detection of H. pylori. Red blood cell count and volume, serum levels of gastrin, pepsinogen I, iron, folic acid, vitamin B12, and circulating antibodies to H. pylori and to intrinsic factor were also determined.

RESULTS

We found an atrophic body gastritis in 14 of the 79 asymptomatic subjects with parietal cell antibodies (18%) and in 2 of the 66 controls (3%) (p =.01). Mean levels of gastrin were increased (p <.0001), while those of pepsinogen were reduced (p <.001) compared with controls. H. pylori was identified at the gastric level and/or circulating anti-H. pylori antibodies were detected in 46 parietal cell antibody-positive subjects (58%) compared with 26 controls (39%) (p =.03). In patients with pernicious anemia we found an atrophic body gastritis in 18 of 24 cases (75%) (p <.001 vs. controls). Mean levels of gastrin were markedly increased (p <.0001) and those of pepsinogen I decreased (p <.0001) relative to controls. Only five of these patients (21%) had evidence of H. pylori infection compared with 46 of the parietal cell antibody-positive subjects (58%) (p =.003) and 26 of the controls (39%). Considering all patients with gastric autoimmunity (i.e. with parietal cell antibodies and/or with pernicious anemia), H. pylori was found in 44 of 72 of those without atrophy (61%) but in 6 of 31 with gastric body atrophy (19%) (p <.001), indicating that H. pylori infection is greatly reduced when gastric acid secretion decreases.

CONCLUSIONS

The frequent detection of H. pylori infection in subjects with early gastric autoimmunity, indicated by the presence of parietal cell antibodies, suggests that H. pylori could have a crucial role in the induction and/or the maintenance of autoimmunity at the gastric level.

Better survival of Helicobacter pylori infected patients with early gastric cancer is related to a higher level of Thomsen-Friedenreich antigen-specific antibodies

The survival of patients with histologically verified gastric carcinoma at stage I (n = 44) and stage II (n = 43) was analysed by the Kaplan-Meier method depending on H. pylori serological status and a level of IgG and IgM antibody to tumor-associated Thomson-Friedenreich antigen (T Ag). In cancer patients at stage I, significantly better survival for H. pylori seropositive patients was observed compared to H. pylori seronegative patients (median SE survival time: 60.0 +/- 3.8 mths and 37.0 +/- 7.8 mths, respectively; P < 0.0004, log-rank test). Patients with higher level of T Ag-specific IgG antibody (strong responders) showed significantly and dramatically better (P < 0.00001) survival rate than weak responders. However, an association of better survival with a higher level of anti-T antibody level was limited to the H. pylori seropositive patients exclusively (P < 0.00001) with no difference for H. pylori seronegative group of patients. The level of IgM anti-T Ag antibody was not significantly related to the survival of patients at both stages of the disease, though better survival was noted in H. pylori seropositive IgM strong responders at approximately 40-60 months of observation. Statistically insignificant associations between survival and H. pylori status or anti-T antibody levels were also observed in a group of gastric cancer patients at stage II. In summary, the survival of patients with early gastric cancer (stage I) is significantly better in H. pylori seropositive patients, and this phenomenon may be in part explained by up-regulation of T Ag-specific IgG immune response in H. pylori infected individuals.