Autoantibodies against ATP4A are a feature of the abundant autoimmunity that develops in first-degree relatives of patients with type 1 diabetes.

OBJECTIVE: Type 1 diabetes is associated with autoantibodies to different organs that include the gut. The objective of the study was to determine the risk of developing gastric parietal cell autoimmunity in relation to other autoimmunity in individuals with a family history of type 1 diabetes. METHODS: Autoantibodies to the parietal cell autoantigen, H+ /K+ ATPase subunit A (ATP4A) was measured in 2218 first-degree relatives of patients with type 1 diabetes, who were prospectively followed from birth for a median of 14.5 years. All were also tested regularly for the development of islet autoantibodies, transglutaminase autoantibodies, and thyroid peroxidase autoantibodies. RESULTS: The cumulative risk to develop ATP4A autoantibodies was 8.1% (95% CI, 6.6-9.6) by age 20 years with a maximum incidence observed at age 2 years. Risk was increased in females (HR, 1.9; 95% CI, 1.3-2.8; p = 0.0004), relatives with the HLA DR4-DQ8/DR4-DQ8 genotype (HR, 3.4; 95% CI, 1.9-5.9; p < 0.0001) and in participants who also had thyroid peroxidase autoantibodies (HR, 3.7; 95% CI, 2.5-5.5; p < 0.0001). Risk for at least one of ATP4A-, islet-, transglutaminase-, or thyroid peroxidase-autoantibodies was 24.7% (95% CI, 22.6-26.7) by age 20 years and was 47.3% (95% CI, 41.3-53.3) in relatives who had an HLA DR3/DR4-DQ8, DR4-DQ8/DR4-DQ8, or DR3/DR3 genotype (p < 0.0001 vs. other genotypes). CONCLUSIONS: Relatives of patients with type 1 diabetes who have risk genotypes are at very high risk for the development of autoimmunity against gastric and other organs.

Autoantibodies Toward ATP4A and ATP4B Subunits of Gastric Proton Pump H+,K+-ATPase Are Reliable Serological Pre-endoscopic Markers of Corpus Atrophic Gastritis.

INTRODUCTION: Noninvasive assessment of corpus atrophic gastritis (CAG), a condition at increased risk of gastric cancer, is based on the measurement of pepsinogens, gastrin, and Helicobacter pylori antibodies. Parietal cell autoantibodies (PCAs) against the gastric proton pump (ATP4) are potential serological biomarkers of CAG. The purpose of this study was to compare the diagnostic performance of PCA and pepsinogen I tests in patients with clinical suspicion of CAG with the histopathological evaluation of gastric biopsies as reference standard. METHODS: A prospective case-finding study was performed on 218 naive adult patients (131 women, median age 65 years) who underwent gastric biopsies to confirm/exclude CAG. Patients with histopathological CAG were defined as cases, conversely as controls. Autoantibodies against the individual alpha (ATP4A) and beta (ATP4B) subunits of ATP4 were measured by luciferase immunoprecipitation, and global PCA and pepsinogen I by enzyme-linked immunosorbent assay. RESULTS: Histopathology classified 107 subjects (49%) as cases (CAG+, autoimmune 81.2%, and multifocal extensive 18.8%) and 111 subjects (51%) as controls (CAG-). In cases, ATP4A, ATP4B, and PCA titers were increased compared with controls, whereas pepsinogen I was reduced (P < 0.0001 for all). ATP4B, ATP4A, and pepsinogen I tests showed sensitivities of 77%, 75%, and 73% and specificities of 88%, 88%, and 80%, respectively. The receiver operating characteristic (ROC) area under the ROC curve (AUC) of these serological biomarkers confirmed their ability to discriminate cases from controls (ATP4B = 0.838, ATP4A = 0.826, pepsinogen I = 0.775, and PCA = 0.805), whereas the partial ROC-pAUC90 analysis showed that the ATP4B test had the best diagnostic performance (P = 0.008 vs ATP4; P = 0.0002 vs pepsinogen I). The presence of autoimmune or extensive gastritis was not significantly different between ATP4B positive or negative cases (P = 0.217). DISCUSSION: PCAs are promising serological biomarkers for the identification of CAG in high-risk individuals, particularly in an autoimmune pattern but also in an extensive-multifocal atrophy pattern.

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.

A quarter of patients with type 1 diabetes have co-existing non-islet autoimmunity: the findings of a UK population-based family study.

Individuals with type 1 diabetes (T1D) are at increased risk of coeliac disease (CD), autoimmune thyroiditis and autoimmune gastritis, but the absolute risks are unclear. The aim of this study was to investigate the prevalence of autoantibodies to tissue transglutaminase (TGA), thyroid peroxidase (TPOA) and gastric H+ /K+ -ATPase (ATPA) and their genetic associations in a well-characterized population-based cohort of individuals with T1D from the Bart's-Oxford family study for whom islet autoantibody prevalence data were already available. Autoantibodies in sera from 1072 patients (males/females 604/468; median age 11·8 years, median T1D duration 2·7 months) were measured by radioimmunoassays; HLA class II risk genotype was analysed in 973 (91%) using polymerase chain reaction with sequence specific primers (PCR-SSP). The prevalence of TGA (and/or history of CD), TPOA and ATPA in patients was 9·0, 9·6 and 8·2%, respectively; 3·1% had two or more autoantibodies. Females were at higher risk of multiple autoimmunity; TGA/CD were associated with younger age and TPOA with older age. ATPA were uncommon in patients under 5 years, and more common in older patients. Anti-glutamate decarboxylase autoantibodies were predictive of co-existing TPOA/ATPA. TGA/CD were associated with human leucocyte antigen (HLA) DR3-DQ2, with the DR3-DQ2/DR3-DQ2 genotype conferring the highest risk, followed by DR4-DQ8/DR4-DQ8. ATPA were associated with DR3-DQ2, DRB1*0404 (in males) and the DR3-DQ2/DR4-DQ8 genotype. TPOA were associated with the DR3-DQ2/DR3-DQ2 genotype. Almost one-quarter of patients diagnosed with T1D aged under 21 years have at least one other organ-specific autoantibody. HLA class II genetic profiling may be useful in identifying those at risk of multiple autoimmunity.

ATP4A autoimmunity in pediatric patients with type 1 diabetes and its relationship to blood count, iron metabolism, and vitamin B12.

OBJECTIVE: We aimed to assess the prevalence of autoantibodies against the 4A subunit of the gastric proton pump (ATP4A) in pediatric type 1 diabetes (T1D) patients and explore the relationship between ATP4A positivity and blood cell count, iron turnover, and vitamin B12 concentration. SUBJECTS: The study included 94 (59% female) T1D children (aged 12.5 ± 4.1 years, T1D duration 4.2 ± 3.6 years, HbA1c 7.3 ± 1.5% (57 ± 12.6 mmol/mol) with no other autoimmune diseases. METHODS: ATP4A antibodies were measured in T1D patients using a radioimmunoprecipitation assay. Blood cell count, iron concentration, total iron binding capacity, ferritin, transferrin, hepcidin, and vitamin B12 concentration were measured in all the study participants. RESULTS: A total of 16 (17%) children were ATP4A positive. Serum concentrations of ferritin were significantly lower in ATP4A positive than in antibody negative subjects (P = .034). Overall the levels of ATP4A antibodies (ATP4A Index) correlated positively with the age at T1D diagnosis (r = 0.228, P = .026) and negatively with ferritin levels (r = -0.215, P = .037). In ATP4A positive patients, the ATP4A Index correlated positively with age at diagnosis (r = 0.544, P = .032) and negatively with vitamin B12 levels (r = -0.685, P = .004). CONCLUSIONS: ATP4A antibodies were present in a significant proportion of children with T1D. Higher ATP4A levels in T1D children are associated with lower, yet still fitting within the normal range, levels of vitamin B12, and ferritin. Routine screening of T1D children for gastric autoimmunity (ATP4A) should be considered with follow-up of those positive for vitamin B12 and iron deficiency.

Revisiting autoimmune gastritis in children and adolescents with type 1 diabetes.

OBJECTIVE: Assess the frequency of anti-H+ /K+ adenosine triphosphatase (ATPase) autoantibodies (AAB) and symptoms of autoimmune gastritis in children and adolescents with type 1 diabetes (T1D). RESEARCH DESIGN AND METHODS: Anti-H+ /K+ ATPase AAB were measured in 402 children and adolescents (210 boys and 192 girls, 11.1 ± 4.5 years) treated for T1D (screened positive for ß-cell AAB), along with search of symptoms of anemia (hemoglobin, serum iron, and ferritin levels) and gastric pain. The AAB specific for thyroperoxydase, thyroglobulin, and transglutaminase were also measured. RESULTS: Anti-H+ /K+ ATPase AAB were present in 6.5% of children. Their frequency increased with age: 4% at 10 years, 10% at 15 years, and 20% at 20 years. Iron deficiency (45% vs 3.8%), iron deficiency anemia (36% vs 3.8%), antithyroid AAB (24% vs 9.7%), and family history of Graves' disease (25% vs 5.6%) were more frequent in patients with anti-H+ /K+ ATPase AAB. Two patients, a 13-year-old girl and a 11-year-old boy, experienced symptoms (iron deficiency anemia and epigastric pain) which led to diagnosis of autoimmune gastritis confirmed upon fibroscopy. Both showed high levels of anti-H+ /K+ ATPase AAB and atrophic gastritis. CONCLUSIONS: Autoimmune gastritis presents an age-dependent frequency in children and adolescents with T1D but is rarely symptomatic. Screening for anti-H+ /K+ ATPase AAB should thus target patients with iron deficiency, anemia, epigastralgia, autoimmune thyroiditis, or age over 15 years.

Proton pump inhibitors decrease eotaxin-3/CCL26 expression in patients with chronic rhinosinusitis with nasal polyps: Possible role of the nongastric H,K-ATPase.

BACKGROUND: Chronic rhinosinusitis with nasal polyps (CRSwNP) is often characterized by tissue eosinophilia that is associated with poor prognosis. Recent findings that proton pump inhibitors (PPIs) directly modulate the expression of eotaxin-3, an eosinophil chemoattractant, in patients with eosinophilic diseases suggest therapeutic potential for PPIs in those with CRSwNP. OBJECTIVE: We assessed the effect of type 2 mediators, particularly IL-13 and eotaxin-3, on tissue eosinophilia and disease severity in patients with chronic rhinosinusitis (CRS). Further investigation focused on PPI suppression of eotaxin-3 expression in vivo and in vitro, with exploration of underlying mechanisms. METHODS: Type 2 mediator levels in nasal tissues and secretions were measured by using a multiplex immunoassay. Eotaxin-3 and other chemokines expressed in IL-13-stimulated human sinonasal epithelial cells (HNECs) and BEAS-2B cells with or without PPIs were assessed by using ELISA, Western blotting, real-time PCR, and intracellular pH imaging. RESULTS: Nasal tissues and secretions from patients with CRSwNP had increased IL-13, eotaxin-2, and eotaxin-3 levels, and these were positively correlated with tissue eosinophil cationic protein levels and radiographic scores in patients with CRS (P < .05). IL-13 stimulation of HNECs and BEAS-2B cells dominantly induced eotaxin-3 expression, which was significantly inhibited by PPIs (P < .05). Patients with CRS taking PPIs also showed lower in vivo eotaxin-3 levels compared with those without PPIs (P < .05). Using intracellular pH imaging and altering extracellular K+, we found that IL-13 enhanced H+,K+-exchange, which was blocked by PPIs and the mechanistically unrelated H,K-ATPase inhibitor, SCH-28080. Furthermore, knockdown of ATP12A (gene for the nongastric H,K-ATPase) significantly attenuated IL-13-induced eotaxin-3 expression in HNECs. PPIs also had effects on accelerating IL-13-induced eotaxin-3 mRNA decay. CONCLUSION: Our results demonstrated that PPIs reduce IL-13-induced eotaxin-3 expression by airway epithelial cells. Furthermore, mechanistic studies suggest that the nongastric H,K-ATPase is necessary for IL-13-mediated epithelial responses, and its inhibitors, including PPIs, might be of therapeutic value in patients with CRSwNP by reducing epithelial production of eotaxin-3.

Expression of ODC Antizyme Inhibitor 2 (AZIN2) in Human Secretory Cells and Tissues.

Ornithine decarboxylase (ODC) antizyme inhibitor 2 (AZIN2), originally called ODCp, is a regulator of polyamine synthesis that we originally identified and cloned. High expression of ODCp mRNA was found in brain and testis. We reported that AZIN2 is involved in regulation of cellular vesicle transport and / or secretion, but the ultimate physiological role(s) of AZIN2 is still poorly understood. In this study we used a peptide antibody (K3) to human AZIN2 and by immunohistochemistry mapped its expression in various normal tissues. We found high expression in the nervous system, in type 2 pneumocytes in the lung, in megakaryocytes, in gastric parietal cells co-localized with H,K-ATPase beta subunit, in selected enteroendocrine cells, in acinar cells of sweat glands, in podocytes, in macula densa cells and epithelium of collecting ducts in the kidney. The high expression of AZIN2 in various cells with secretory or vesicle transport activity indicates that the polyamine metabolism regulated by AZIN2 is more significantly involved in these events than previously appreciated.

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 ß-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.

ATPase4A Autoreactivity and Its Association With Autoimmune Phenotypes in the Type 1 Diabetes Genetics Consortium Study.

Autoantibodies targeting the H+/K+-ATPase proton pump of the gastric parietal cell (parietal cell antibodies [PCA]) are diagnostic of atrophic body gastritis (ABG) leading to pernicious anemia (PA). PCA, ABG, and PA occur in increased frequency in patients with type 1 diabetes and their relatives and are considered "minor" components of forms of autoimmune polyglandular syndrome (APS). A customized radioimmunoprecipitation assay was applied to 6,749 samples from the Type 1 Diabetes Genetics Consortium to measure ATP4A autoreactivity. Autoantibody prevalence was correlated with variants in HLA class II, PTPN22, and CTLA4 genes. With an ATP4A radioimmunoprecipitation assay, PCA were detected in sera from 20.9% of affected individuals. PCA prevalence increased with age and was greater in females (25.3%) than males (16.5%) and among Hispanics (36.3%) and blacks (26.2%) compared with non-Hispanic whites (20.8%) and Asians (16.7%). PCA and other organ-specific autoantibodies GAD65, IA-2, thyroid peroxidase (TPO), 21-hydroxylase (21-OH), and transglutaminase (TG) clustered within families with heritability estimates from 71 to 95%. PCA clustered with TPO, 21-OH, and persistent GAD65 autoantibodies but not with celiac (TG) or IA-2 autoantibodies. PCA-positive subjects showed an increased frequency of DRB1*0404, DPB1*0201, and PTPN22 R620W (rs2476601-T) and a decreased frequency of DRB1*0101, DPB1*0301, and CTLA4 CT60 (rs3087243-T). Genetic variants accounted for 4-5% of the heritable risk for PCA. The same alleles were associated with other autoantibody phenotypes in a consistent pattern. Whereas most of the heritable risk for PCA and other antibodies reflects genetic effects that are tissue specific, parietal cell autoimmunity is a major pathogenetic contributor in APS2.

ATP4A autoimmunity and Helicobacter pylori infection in children with type 1 diabetes.

Persistent presence of ATP4A autoantibodies (ATP4AA) directed towards parietal cells is typical for atrophic body gastritis (ABG), an autoimmune disease associated with type 1 diabetes. We assessed whether Helicobacter pylori (Hp) infection might be associated with positivity for ATP4AA in children with type 1 diabetes. Sera were collected from 70 (38♀) type 1 diabetes children [aged 13·2 ± 4·5 years, age at diagnosis 8·8 ± 4·3 years, diabetes duration 4·5 ± 3·8 years, mean HbA1c 7·8 ± 1·6% (62 ± 17·5 mmol/mol)] seen at the regional diabetes clinic in Katowice, Poland. Patients were tested concurrently for Hp infection by means of a 13C urea breath test. ATP4AA were measured using a novel radioimmunoprecipitation assay developed at the Barbara Davies Center for Childhood Diabetes, University of Colorado. ATP4AA were present in 21 [30%, 95% confidence interval (CI) = 19-41%] and Hp infection was detected in 23 (33%, 95% CI = 22-44%) children. There was no statistically significant association between ATP4AA presence and Hp status. ATP4AA presence was not associated with current age, age at type 1 diabetes diagnosis, diabetes duration or current HbA1c. ATP4AA were more prevalent in females [42% (26-58%)] than males [16% (3-28%)], P = 0·016. ATP4A are found in nearly one-third of children with type 1 diabetes and more common among females. In this cross-sectional analysis, Hp infection was not associated with autoimmunity against parietal cells.

Autoimmune gastritis mediated by CD4+ T cells promotes the development of gastric cancer.

Chronic inflammation is a major risk factor for cancer, including gastric cancers and other gastrointestinal cancers. For example, chronic inflammation caused by autoimmune gastritis (AIG) is associated with an increased risk of gastric polyps, gastric carcinoid tumors, and possibly adenocarcinomas. In this study, we characterized the progression of gastric cancer in a novel mouse model of AIG. In this model, disease was caused by CD4(+) T cells expressing a transgenic T-cell receptor specific for a peptide from the H(+)/K(+) ATPase proton pump, a protein expressed by parietal cells in the stomach. AIG caused epithelial cell aberrations that mimicked most of those seen in progression of human gastric cancers, including chronic gastritis followed by oxyntic atrophy, mucous neck cell hyperplasia, spasmolytic polypeptide-expressing metaplasia, dysplasia, and ultimately gastric intraepithelial neoplasias. Our work provides the first direct evidence that AIG supports the development of gastric neoplasia and provides a useful model to study how inflammation drives gastric cancer.

Parietal cell antibody identified by ELISA is superior to immunofluorescence, rises with age and is associated with intrinsic factor antibody.

Parietal cell antibody is a marker for autoimmune gastritis. With identification of gastric H/K ATPase as its molecular target, ELISAs have been introduced. We compared performance of ELISA with immunofluorescence in a retrospective and prospective sera set and correlated the results with intrinsic factor antibody. In 138 retrospective sera selected for positivity or negativity for intrinsic factor antibody, 87 reacted with gastric H/K ATPase by Euroimm ELISA but only 62 reacted by immunofluorescencence.. Similar results were obtained with Inova ELISA with 78 positives that were also positive by Euroimm ELISA. In 161 prospective sera, 29 sera tested positive by ELISA compared to 24 by immunofluorescence. ELISA positive but immunofluoresnce negative sera are bona fide positives because a representative set of 16 sera reacted with both 95kD α and 60-90kDß subunits of gastric H/K ATPase. ELISA values rose with age regardless of whether immunofluorescence tests were positive or negative. Of 53 sera containing antibody to intrinsic factor, 46/53 (87%) reacted to gastric H/K ATPase by ELISA. Taken together, the data indicates an enhanced detection rate by ELISA over immunofluorescence and validates it as a robust diagnostic assay for parietal cell antibody. As parietal cell antibody marks asymptomatic autoimmune gastritis that may progress to end stage gastric atrophy and haematological complications, and as autoimmune gastritis is associated with autoimmune thyroiditic and type 1 diabetes mellitus, early detection of parietal cell antibody by a sensitive ELISA will enable early follow-up of at risk subjects.

Development of a novel autoantibody assay for autoimmune gastritis in type 1 diabetic individuals.

BACKGROUND: Autoimmune atrophic body gastritis (ABG) and pernicious anaemia are prototypical, organ-specific autoimmune diseases whose prevalence in the general population is 2.0 vs 2 and 0.15-1%, respectively. The incidence of disease increases with age and is frequently associated with other autoimmune disorders such as type 1 diabetes mellitus (T1DM). Early diagnosis of ABG/pernicious anaemia is essential for the prevention and/or treatment before manifestations of chronic disease become irreversible. Parietal cell autoantibody detection via enzyme-linked immunosorbent assay is currently the most widely used biomarker of disease with diagnosis confirmed by subsequent immunohistochemistry via biopsy. METHODS: To improve the assay we designed a specific, molecularly defined radioimmunoprecipitation assay for early detection of ABG, targeting its major antigen, the gastric H+/K+ ATPase 4A subunit ATP4A. RESULTS: The major antigenic domain in ATP4A was tested against a panel of sera from new onset patients with T1DM which tested positive for the gold standard T1DM autoantibodies (IAA, IA2A, GAD65A, and ZnT8A). Significant immunoreactivity to ATP4A was measured (25%) while 6% of first-degree relatives of subjects with T1DM who were sero-negative for T1DM autoantigens were positive for ATP4A autoantibodies. ATP4A antibody prevalence increased with age of onset of T1DM, which is atypical of other T1DM autoantibodies. Immunoreactivity to ATP4A, unlike that of T1DM antigens, demonstrates a significant gender bias in newly diagnosed individuals with T1DM. CONCLUSION: Although the utility of the assay as a biomarker for T1DM is likely limited, it may serve as an improved indicator of ABG.

[Pernicious anaemia--diagnostic benefit of the detection of autoantibodies against intrinsic factor and gastric parietal cells antigen H+/K+ ATPase]. / Perniciózní anémie--diagnostický prínos detekce autoprotilátek proti vnitrnímu faktoru a tercovému antigenu parietálních bunek zaludku H+/K+ ATPáze.

BACKGROUND: Pernicious anaemia is an autoimmune disease that causes acquired vitamin B12 deficiency. The diagnostic process includes the detection of typical changes in the blood count, low serum levels of vitamin B12, endoscopic and histological signs of gastritis and autoantibodies against the gastric parietal cells antigen H+/K+ ATPase and intrinsic factor. OBJECTIVE: Our aims were to establish immunological tests for the detection of autoantibodies against intrinsic factor and target gastric parietal cell antigen H+/K+ ATPase and to evaluate their diagnostic benefits in patients with pernicious anaemia. MATERIAL AND METHODS: Sera from 95 patients were tested for autoantibodies against H+/K+ ATPase and intrinsic factor by multiplex Luminex assay. The results were compared with those of the immunofluorescence assay for the detection of autoantibodies against gastric parietal cells and with the diagnostic criteria. RESULTS: The autoantibodies against gastric parietal cell H+/K+ ATPase had a sensitivity of 68.2% with a specificity of 91.7% for the diagnosis of pernicious anaemia. The respective rates for the autoantibodies against intrinsic factor were 40.9% and 98.6%. The combined sensitivity and specificity rates for both autoantibodies were 86.36% and 90.28%, respectively, the combined positive predictive value was 73.08% and the combined negative predictive value was 95.59%. CONCLUSION: The detection of both autoantibodies is helpful in diagnosing pernicious anaemia and the combination of the two assays increases diagnostic sensitivity.

[Association of the morphological features of gastric parietal cells with the concentration of H+/K+/ATPase autoantibodies in chronic gastrititis].

Chronic gastritis was morphologically verified in 119 patients. The count of parietal cells per 100 epitheliocytes of fundic glands was estimated. The sizes of parietal cells were measured by the morphometric computer program Videotest. For the diagnosis of autoimmune chronic gastritis (ACG), the level of antibodies to H+K+ATPase of gastric parietal cells in the patients' serum was determined by enzyme immunoassay. Childhood ACG has been found to be characterized by hyperplasia and structural changes of parietal cells with their preserved total count. The specific features of adult ACG include a significant reduction in the number of parietal cells, their sizes depending on the level of antiparietal autoantibodies, and marked ultrastructural changes as impairments in the differentiation and destruction of cytoplasm, organelles, and cell membrane.

Expression of H(+),K(+)-ATPase and glycopattern analysis in the gastric glands of Rana esculenta.

A multidisciplinary study involving lectin histochemistry, IHC, immuno-lectin blotting, and immunogold was carried out to determine the distribution of sugar residues in the glycoproteins of Rana esculenta oxynticopeptic cells. We considered animals in two experimental conditions, fasting and fed. It is known that, in mammals, the tubulovesicular membranes are rich in proteins with several functions. The proton pump H(+),K(+)-ATPase, a heterodimeric complex with a catalytic alpha-subunit and a heavily glycosylated beta-subunit, responsible for acid secretion, is the most abundant. No data have been published regarding the localization and the structures of H(+),K(+)-ATPase in amphibians. In the water frog, the luminal membrane and tubulovesicular system of oxynticopeptic cells, which differ in morphology according to their functional stage, reacted with the primary gold-conjugated antibody against the H(+),K(+)-ATPase alpha-subunit. By lectin histochemistry and immunoblotting, in the oxynticopeptic cells of R. esculenta we detected the presence of N-linked glycans having fucosylated (poly)lactosamine chains, which could correspond to the oligosaccharide chains of the beta subunit. The latter are somewhat different from those described in mammals, and this is probably because of an adaptation to the different microenvironmental conditions in which the oxynticopeptic cells find themselves, in terms of their different habits and phylogeny.

Prevention of autoimmune gastritis in mice requires extra-thymic T-cell deletion and suppression by regulatory T cells.

BACKGROUND AND AIMS: Autoimmune gastritis is one of the most common autoimmune diseases and is caused by a CD4(+) T-cell response to the gastric H(+)/K(+) ATPase encoded by Atp4a and Atp4b (H(+)/K(+) ATPase). Here, we have elucidated events that result in immunological tolerance to the H(+)/K(+) ATPase and thus the prevention of autoimmune gastritis. METHODS: T cells from H(+)/K(+) ATPase-deficient mice and H(+)/K(+) ATPase-specific T-cell receptor transgenic mice were purified and transferred to wild-type (WT) or H(+)/K(+) ATPase-deficient recipients to assess the impact of exposure to antigen on pathogenicity. RESULTS: The CD4(+) T-cell population from H(+)/K(+) ATPase-deficient mice was highly effective at inducing gastritis when compared with T cells from WT mice and, as a population, was comparatively resistant to the suppressive activity of regulatory T cells. Exposing T cells from H(+)/K(+) ATPase-deficient mice to H(+)/K(+) ATPase in WT mice decreased their ability to induce gastritis and resulted in a population that could be more easily suppressed by T(reg) cells. Transfer of clonotypic antigen-inexperienced H(+)/K(+) ATPase-specific T cells into WT mice resulted in extra-thymic clonal deletion. CONCLUSIONS: Prevention of autoimmune gastritis requires the extra-thymic purging of highly autoaggressive H(+)/K(+) ATPase-specific T cells to produce a T-cell repertoire that is more susceptible to the suppressive activity of regulatory T cells. Taken together with recent published data describing the role of T-cell receptor signalling in the maintenance of regulatory T-cell populations, we propose that exposure of T cells to antigen in the periphery is able to both delete autoaggressive specificities and maintain regulatory T-cell activity, establishing a balance between pathogenicity and regulation.

Murine experimental autoimmune gastritis models refractive to development of intrinsic factor autoantibodies, cobalamin deficiency and pernicious anemia.

Researchers have developed murine lymphopenic, non-lymphopenic, transgenic, spontaneous and infectious agent based models to induce an experimental autoimmune gastritis (EAG) for the study of human organ-specific autoimmune disease. These models result in a chronic inflammatory mononuclear cell infiltrate in the gastric mucosa, destruction of parietal and zymogenic cells with autoantibodies reactive to the gastric parietal cells and the gastric H+/K+ ATPase (ATP4), arguably hallmarks of a human autoimmune gastritis (AIG). In the case of AIG, it is well documented that, in addition to parietal cell antibodies being detected in up to 90% of patients, up to 70% have intrinsic factor antibodies with the later antibodies considered highly specific to patients with pernicious anemia. This is the first report specifically investigating the occurrence of intrinsic factor antibodies, cobalamin deficiency and pernicious anemia in EAG models. We conclude, in contrast to AIG, that, in the three EAG models examined, intrinsic factor is not selected as a critical autoantigen.

Spontaneous large-scale lymphoid neogenesis and balanced autoimmunity versus tolerance in the stomach of H+/K+-ATPase-reactive TCR transgenic mouse.

Autoimmunity is often accompanied by the development of ectopic lymphoid tissues in the target organ, and these tissues have been believed to have close relevance to the severity of the disease. However, the true relationship between the extent of such lymphoid structures and the intensity or type of immune responses mediated by self-reactive T cells has remained unclear. In the present study, we generated transgenic mice expressing TCR from an autoimmune gastritis (AIG)-inducing Th1 cell clone specific for one of the major stomach self-Ags, H(+)/K(+)-ATPase alpha subunit. The transgenic mice spontaneously develop massive lymphoid neogenesis with a highly organized tissue structure in the gastric mucosa, demonstrating Ag-specific, T cell-mediated induction of the lymphoid tissues. Nevertheless, the damage of surrounding tissue and autoantibody production were considerably limited compared with those in typical AIG induced by neonatal thymectomy. Such a moderate pathology is likely due to the locally restricted activation and Th2 skewing of self-reactive T cells, as well as the accumulation of naturally occurring regulatory T cells in the target organ. Altogether, the findings suggest that lymphoid neogenesis in chronic autoimmunity does not simply correlate with the destructive response; rather, the overall activation status of the T cell network, i.e., the balance of self-reactivity and tolerance, in the local environment has an impact.