Lack of specific association between gastric autoimmunity hallmarks and clinical presentations of atrophic body gastritis

Increased Prevalence of Autoimmune Gastritis in Patients with a Gastric Precancerous Lesion

Background: Autoimmune gastritis (AIG), characterized with the presence of anti-parietal-cell antibodies (APCA), is a risk factor for gastric cancer. However, AIG may go underdiagnosed, especially in the case of H. pylori infection and the presence of gastric precancerous lesions (GPL), due to the ambiguous pathology and delayed symptom onset. Aim: Investigate the prevalence and characteristics of AIG in GPL patients. Methods: Prevalence of AIG was determined with the presence of APCA in patients with GPL (n = 256) and the control group (n = 70). Pathological characteristics and levels of gastrin 17 (G17), pepsinogen (PG) I and II and anti-Helicobacter pylori IgG were assessed in GPL cases, and the severity of intestinal metaplasia and gastric atrophy was scored by expert pathologists. Results: APCA positivity was observed in 18% of cases vs. 7% of controls (p = 0.033). Only 3/256 patients were previously diagnosed with AIG. The presence of APCA was associated with corpus-limited and extended GPL. A receiver operating curve analysis demonstrated that the G17 and PGI/II ratio could identify APCA-positive patients within GPL cases (AUC: 0.884). Conclusions: The prevalence of AIG is higher in patients with GPL but goes undiagnosed. Using G17 and PG I/II as diagnostic markers can help to identify patients with AIG and improve surveillance programs for patients with GPL.

A current clinical overview of atrophic gastritis

Introduction: Atrophic gastritis (AG) is a complex syndrome which arises as a consequence of H. pylori infection or in the context of gastric autoimmunity. It often deserves a benign course but may lead to potentially life-threatening complications: cancer and anemia. This review aims to address traditional and innovative knowledge on this often under-diagnosed disorder.Areas covered: This review covers clinical presentation, risk factors, diagnosis, and management of AG and provides an updated resource for clinicians to get insight into this challenging disorder. Updated literature was searched in PubMed. Manual search from reference lists of publications was performed.Expert opinion: A case-finding strategy may be beneficial in individuals with anemia, dyspepsia, autoimmune thyropaties and type 1 diabetes, and family history of gastric cancer. AG is linked to gastric cancer risk and endoscopic surveillance is indicated according to topography of gastric atrophy and risk factors. The direction for future research in AG is summarized.

Chronic atrophic gastritis: Natural history, diagnosis and therapeutic management. A position paper by the Italian Society of Hospital Gastroenterologists and Digestive Endoscopists [AIGO], the Italian Society of Digestive Endoscopy [SIED], the Italian Society of Gastroenterology [SIGE], and the Italian Society of Internal Medicine [SIMI]

Chronic atrophic gastritis (CAG) is an underdiagnosed condition characterised by translational features going beyond the strict field of gastroenterology as it may manifest itself by a variable spectrum of gastric and extra-gastric symptoms and signs. It is relatively common among older adults in different parts of the world, but large variations exist. Helicobacter pylori-related CAG [multifocal] and autoimmune CAG (corpus-restricted) are apparently two different diseases, but they display overlapping features. Patients with cobalamin and/or iron deficiency anaemia or autoimmune disorders, including autoimmune thyroiditis and type 1 diabetes mellitus, should be offered screening for CAG. Pepsinogens, gastrin-17, and anti-H. pylori antibodies serum assays seem to be reliable non-invasive screening tools for the presence of CAG, helpful to identify individuals to refer to gastroscopy with five standard gastric biopsies in order to obtain histological confirmation of diagnosis. Patients with CAG are at increased risk of developing gastric cancer, and they should be estimated with histological staging systems (OLGA or OLGIM). H. pylori eradication may be beneficial by modifying the natural history of atrophy, but not that of intestinal metaplasia. Patients with advanced stages of CAG (Stage III/IV OLGA or OLGIM) should undergo endoscopic surveillance every three years, those with autoimmune CAG every three-five years. In patients with CAG, a screening for autoimmune thyroid disease and micronutrient deficiencies, including iron and vitamin B₁₂, should be performed. The optimal treatment for dyspeptic symptoms in patients with CAG remains to be defined. Proton pump inhibitors are not indicated in hypochlorhydric CAG patients.

Differential Helicobacter pylori Plasticity in the Gastric Niche of Subjects at Increased Gastric Cancer Risk

Helicobacter pylori (H. pylori) represents an independent risk factor for Gastric Cancer (GC). First Degree Relatives (FDR) of GC subjects and Autoimmune Gastritis (AG) patients are both at increased risk for GC. H. pylori genetic heterogeneity within the gastric niche of FDR and AG individuals has been little explored. To understand whether they exploit an increased H. pylori stability and virulence, 14 AG, 25 FDR, 39 GC and 13 dyspeptic patients (D) were investigated by a cultural PCR-based approach characterizing single colonies-forming-units. We chose three loci within the Cytotoxin-associated gene-A Pathogenicity Island (CagPAI) (cagA,cagE,virB11), vacA, homA and homB as markers of virulence with reported association to GC. Inflammatory/precancerous lesions were staged according to Sydney System. When compared to D, FDR, similarly to GC patients, were associated to higher atrophy (OR = 6.29; 95% CI:1.23-31.96 in FDR; OR = 7.50; 95% CI:1.67-33.72 in GC) and a lower frequency of mixed infections (OR = 0.16; 95% CI:0.03-0.81 in FDR; OR = 0.10; 95% CI:0.02-0.48 in GC). FDR presented also an increased neutrophil infiltration (OR = 7.19; 95% CI:1.16-44.65). Both FDR and GC carried a higher proportion of CagPAI⁺vacAs1i1mx⁺homB⁺ profiles (OR = 2.71; 95% CI: 1.66-4.41 and OR = 3.43; 95% CI: 2.16-5.44, respectively). Conversely, AG patients presented a lower frequency of subtypes carrying a stable CagPAI and vacAs1i1mx. These results underline different H. pylori plasticity in FDR and AG individuals, and thus, a different host-bacterium interaction capacity that should be considered in the context of eradication therapies.

[The investigation of the positive rate of intrinsic factor antibody and deficiency rate of vitamin B(12) in normal physical examination population]

Objective: To explore the positive rate of intrinsic factor antibody (IFAb) and level of vitamin B(12) (VitB(12)) in normal physical examination population and the possible relation between IFAb, VitB12 and sex, age, number of RBC, HGB and MCV. Methods: A total of 1 427 people who came to Peking Union Medical Colleague Hospital (PUMCH) for physical examination were enrolled. There were 758 males with average age of (52.5±14.5) years-old and 669 females with average age of (50.3±14.3) year-old. Beckman DxI800 automatic biochemical-immune analyzer and corollary reagents were used to analyze the level of serum IFAb and VitB(12). The results in different sex, age were documented and their correlation with the value of whole blood cell count was tested later on. Results: Among the 1 427 normal subjects, 66 (4.63%) were positive for IFAb. The positive rate for IFAb in the population≥40 years-old was higher than those<40 years-old (5.66% vs 1.48%, χ(2)=7.46, P=0.006). The deficiency rate of VitB(12) in the population<40 years-old, 40-59 years-old and ≥60 years-old was 2.22%, 2.51% and 5.50%, respectively (χ(2)=8.55, P=0.014). There were no difference between people with different sex in the positive rate of IFAb (5.15% for males and 4.04% for females, χ(2)=0.99, P=0.320) or in the deficiency rate of VitB(1)2 (3.83% for males and 2.69% for females, χ(2)=1.44, P=0.230). The results of multiple linear regression showed that HGB level of IFAb positive subjects was 3.05 g/L lower on average than those of IFAb negative, but IFAb had no effect on both RBC and MCV. There was no correlation between VitB(1)2 deficiency and HGB, RBC and MCV. Conclusion: The positive rate of IFAb and deficiency rate of VitB(1)2 increase as age increases. But the presence of VitB(12) deficiency is later than the positive findings of IFAb. IFAb showed some effects on the level of HGB, which may compensate the limitations of VitB(12) detection to some extent. It is necessary to check the IFAb and level of VitB(12) in people with middle or old ages.

Micronutrient deficiencies in patients with chronic atrophic autoimmune gastritis: A review

Chronic atrophic autoimmune gastritis (CAAG) is an organ-specific autoimmune disease characterized by an immune response, which is directed towards the parietal cells and intrinsic factor of the gastric body and fundus and leads to hypochlorhydria, hypergastrinemia and inadequate production of the intrinsic factor. As a result, the stomach’s secretion of essential substances, such as hydrochloric acid and intrinsic factor, is reduced, leading to digestive impairments. The most common is vitamin B12 deficiency, which results in a megaloblastic anemia and iron malabsorption, leading to iron deficiency anemia. However, in the last years the deficiency of several other vitamins and micronutrients, such as vitamin C, vitamin D, folic acid and calcium, has been increasingly described in patients with CAAG. In addition the occurrence of multiple vitamin deficiencies may lead to severe hematological, neurological and skeletal manifestations in CAAG patients and highlights the importance of an integrated evaluation of these patients. Nevertheless, the nutritional deficiencies in CAAG are largely understudied. We have investigated the frequency and associated features of nutritional deficiencies in CAAG in order to focus on any deficit that may be clinically significant, but relatively easy to correct. This descriptive review updates and summarizes the literature on different nutrient deficiencies in CAAG in order to optimize the treatment and the follow-up of patients affected with CAAG.

Chronic gastritis - an update

Helicobacter pylori is the main aetiologic factor for chronic gastritis worldwide. The degree of inflammation and the evolution of this form of chronic gastritis can vary largely depending on bacterial virulence factors, host susceptibility factors and environmental conditions. Autoimmune gastritis is another cause of chronic inflammation in the stomach, which can occur in all age groups. This disease presents typically with vitamin B12 deficiency and pernicious anaemia. The presence of anti-parietal cell antibodies is highly specific for the diagnosis. The role of H. pylori as a trigger for autoimmune gastritis remains uncertain. Other rare conditions for chronic gastritis are chronic inflammatory conditions such as Crohn's disease or on the background of lymphocytic or collagenous gastroenteropathies.

Gastric neuroendocrine tumours

BACKGROUND

Gastric neuroendocrine tumours (NETs) are increasingly recognised, and management decisions may be difficult due to an incomplete understanding of aetiology, natural history and optimum therapy. This article presents a current understanding based on recent advances in epidemiology, classification, molecular profiling, and treatment.

METHODS

Relevant medical literature was identified from searches of PubMed and references cited in appropriate articles identified. Selection of articles was based on peer review, journal and relevance.

RESULTS

Gastric NETs may be divided into three clinical prognostic groups: type I is associated with autoimmune atrophic gastritis and hypergastrinaemia, type II is associated with Zollinger-Ellison syndrome, and type III lesions are gastrin-independent, have the greatest metastatic potential and poorest prognosis. There has been an increased frequency of gastric NETs reported. Management approaches have evolved in parallel with advances in endoscopic staging and surgery, as well as improved understanding of the biology and natural history of NETs.

CONCLUSIONS

Gastric NETs present a spectrum of activity from indolent tumours to metastatic malignancy. Treatment decisions for patients must be individualised and are best managed by a multidisciplinary team approach. The current evidence base is limited to small series and efforts to treat patients within clinical networks of expertise are warranted.

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.

Diagnosis and management of pernicious anemia

Pernicious anemia is a macrocytic anemia due to cobalamin deficiency, which is the result of intrinsic factor deficiency. Pernicious anemia is associated with atrophic body gastritis, whose diagnostic criteria are based on the histologic evidence of gastric body atrophy associated with hypochlorhydria. Serological markers suggesting the presence of oxyntic mucosa damage are increased levels of fasting gastrin and decreased levels of Pepsinogen I. Without the now obsolete Schilling's test, intrinsic factor deficiency may not be proven, and gastric intrinsic factor output after pentagastric stimulation has been proposed. Intrinsic factor autoantibodies are useful surrogate markers of pernicious anemia. The management of patients with pernicious anemia should focus on the life-long replacement treatment with cobalamin and the monitoring to early diagnose an eventual onset of iron deficiency. Moreover, these patients should be advised about possible gastrointestinal long-term consequences, such as gastric cancer and carcinoids.

Pernicious anemia: What are the actual diagnosis criteria?

A gastric intrinsic factor output under 200 U/h after pentagastrin stimulation (N > 2000 U/h) is specific for pernicious anemia. The other findings are either variable or non specific. Serum intrinsic factor antibodies, considered as specific in general practice, are present only in half of the patients with pernicious anemia. In their absence, since the disappearance of the Schilling tests, the gastric tubage currently used for the study of gastric acid secretion, is obligatory for the simultaneous study of intrinsic factor output. This study is important to eliminate another disease much more frequent than pernicious anemia, the protein bound to cobalamin malabsorption was observed in achlorhydric simple atrophic gastritis in the presence of intrinsic factor secretion.

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.

Pernicious anemia: New insights from a gastroenterological point of view

Pernicious anemia (PA) is a macrocytic anemia that is caused by vitamin B₁₂ deficiency, as a result of intrinsic factor deficiency. PA is associated with atrophic body gastritis (ABG), whose diagnosis is based on histological confirmation of gastric body atrophy. Serological markers that suggest oxyntic mucosa damage are increased fasting gastrin and decreased pepsinogen I. Without performing Schilling’s test, intrinsic factor deficiency may not be proven, and intrinsic factor and parietal cell antibodies are useful surrogate markers of PA, with 73% sensitivity and 100% specificity. PA is mainly considered a disease of the elderly, but younger patients represent about 15% of patients. PA patients may seek medical advice due to symptoms related to anemia, such as weakness and asthenia. Less commonly, the disease is suspected to be caused by dyspepsia. PA is frequently associated with autoimmune thyroid disease (40%) and other autoimmune disorders, such as diabetes mellitus (10%), as part of the autoimmune polyendocrine syndrome. PA is the end-stage of ABG. Long-standing Helicobacter pylori infection probably plays a role in many patients with PA, in whom the active infectious process has been gradually replaced by an autoimmune disease that terminates in a burned-out infection and the irreversible destruction of the gastric body mucosa. Human leucocyte antigen-DR genotypes suggest a role for genetic susceptibility in PA. PA patients should be managed by cobalamin replacement treatment and monitoring for onset of iron deficiency. Moreover, they should be advised about possible gastrointestinal long-term consequences, such as gastric cancer and carcinoids.

Limited value of testing for intrinsic factor antibodies with negative gastric parietal cell antibodies in pernicious anaemia

BACKGROUND

The appropriate testing strategy for diagnosing pernicious anaemia using gastric parietal cell (GPC) and/or intrinsic factor antibodies (IFA) is controversial. Intrinsic factor antibodies are found in only about 70% of cases. Indirect immunofluorescence screening for gastric parietal cell antibodies is more sensitive, labour intensive, and less specific.

METHODS

The frequency of antibody positivity (IFA and/or GPC) was retrospectively examined in patients tested for both autoantibodies over a three-year period. It was investigated whether B12 levels were related to antibody status. These findings were validated in a prospective study of IFA in 91 GPC negative patients with low B12 levels.

RESULTS

Of 847 samples identified in the retrospective study, 4 (0.47%) were positive for only intrinsic factor antibodies, 731 (86.3%) positive for GPC alone, and 112 (13.2%) for both. Student t test on log-transformed data showed B12 levels had no bearing on autoantibody status. 91 consecutive patients with low B12 levels were tested for both autoantibodies; all were negative for gastric parietal cell antibodies. Only one sample was positive for intrinsic factor antibody using the porcine intrinsic factor assay, but was negative by a human recombinant intrinsic factor-based ELISA.

CONCLUSIONS

This study provides evidence that testing for gastric parietal cell antibodies is an appropriate screening test for pernicious anaemia, with intrinsic factor antibodies reserved for confirmatory testing or in patients with other autoantibodies that mask the GPC pattern; B12 levels are not related to autoantibody status.

Do intrinsic factor antibodies assays provide univocal answers in Biermer's disease?

The objective of the study is to evaluate the concordance of four assays for antibodies against intrinsic factor (IF-Ab). Sixty-two sera were tested with one competitive automated and three manual noncompetitive assays. Thirty-five percent patients had discordant results with at least one of the four assays. However, any method uncovered patients with proven Biermer's disease missed by the others assays. The observed discordance partly explains the poor sensitivity of IF-Ab in studies using a single assay.

Pernicious anaemia in triplets. A case report and literature review

Pernicious anemia is the most common cause of vitamin B12 deficiency in adults. This entity is associated with chronic atrophic gastritis. We report a case of pernicious anaemia in triplets. We also report a fourth case of cobalamin deficiency with antibodies against intrinsic factor and anti parietal cell antigen negative antibodies in a sibling. The present article reviews the pediatric presentation of pernicious anemia and highlights the possible existence of familial aggregation. Furthermore, the need for systematic familial screening and the usefulness of an endoscopic follow-up program in patients with pernicious anemia are evaluated.

[Pernicious anemia: a teenager with an unusual cause of iron-deficiency anemia]

A teenager was admitted with an iron-deficiency anemia. The gastroscopy found an atrophic body gastritis, which revealed a pernicious anemia. This diagnosis is rare in paediatric patients, the frequency of pernicious anemia increasing with age. Iron-deficiency anemia is mainly described in young people.

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.

Artificial neural networks in the recognition of the presence of thyroid disease in patients with atrophic body gastritis

AIM: To investigate the role of artificial neural networks in predicting the presence of thyroid disease in atrophic body gastritis patients.

METHODS: A dataset of 29 input variables of 253 atrophic body gastritis patients was applied to artificial neural networks (ANNs) using a data optimisation procedure (standard ANNs, T&T-IS protocol, TWIST protocol). The target variable was the presence of thyroid disease.

RESULTS: Standard ANNs obtained a mean accuracy of 64.4% with a sensitivity of 69% and a specificity of 59.8% in recognizing atrophic body gastritis patients with thyroid disease. The optimization procedures (T&T-IS and TWIST protocol) improved the performance of the recognition task yielding a mean accuracy, sensitivity and specificity of 74.7% and 75.8%, 78.8% and 81.8%, and 70.5% and 69.9%, respectively. The increase of sensitivity of the TWIST protocol was statistically significant compared to T&T-IS.

CONCLUSION: This study suggests that artificial neural networks may be taken into consideration as a potential clinical decision-support tool for identifying ABG patients at risk for harbouring an unknown thyroid disease and thus requiring diagnostic work-up of their thyroid status.

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.

My approach to reporting a gastric biopsy

The protracted inflammation of the gastric mucosa induces profound changes in the microenvironment of the gastric cells. These changes modify the molecular signals that orchestrate morphogenesis and cell differentiation in the stem cells of the crypts. The expression of this adjustment to the new microenvironment is evidenced by the appearance of differentiated metaplastic cells (intestinal, bronchial-ciliated, pancreatic or (pseudo) pyloric, all deriving from the same embryological origin). The inability of stem cells to readapt to the new microenvironment may lead to genomic aberrations such as the retention of cellular products (glassy cells) or to neoplastic transformation. In this report, parameters such as gastric mucosal inflammation, Helicobacter pylori, atrophy, intestinal metaplasia and/or pseudopyloric metaplasia found in gastric biopsy specimens were individually classified according to their extension in sections as grade 1 (focal distribution in sections from individual biopsy specimens) and grade 2 (present in the entire width-distance across-in sections from individual biopsy specimen). The rationale is that a biopsy grade 2 was harvested from a larger mucosal area having that particular change. Each individual parameter gives a score, and the sum of all individual scores gives the total score. The proposed system might allow monitoring the results of treatment in follow-up biopsies. Divergent clinical results in the frequency/incidence of gastritis (including body-autoimmune gastritis), of H pylori strains, of various metaplasias and neoplasias, in disparate geographical regions substantiate the conviction that these parameters are much influenced by the environment. This knowledge is crucial, considering that environmental diseases are theoretically preventable.

Review article: Pathogenesis and management of gastric carcinoid tumours

BACKGROUND

Gastric carcinoid tumours are rare, but are increasing in incidence.

AIM

To discuss tumour pathogenesis and outline current approaches to patient management.

METHODS

Review of published articles following a Pubmed search.

RESULTS

Although interest in gastric carcinoids has increased since it was recognized that they are associated with achlorhydria, to date there is no definite evidence that humans taking long-term acid suppressing medication are at increased risk. Type I tumours are associated with autoimmune atrophic gastritis and hypergastrinaemia, type II are associated with Zollinger-Ellison syndrome, multiple endocrine neoplasia-1 and hypergastrinaemia and sporadic type III carcinoids are gastrin-independent and carry the worst prognosis. Careful investigation of these patients is required, particularly to identify the tumour type, the source of hypergastrinaemia and the presence of metastases. Treatment can be directed at the source of hypergastrinaemia if type I or II tumours are still gastrin responsive and not growing autonomously. Type III tumours should be treated surgically.

CONCLUSIONS

Advances in our understanding of the pathogenesis of gastric carcinoids have led to recent improvements in investigation and management. Challenges remain in identifying the genetic and environmental factors, in addition to hypergastrinaemia, that are responsible for tumour development in susceptible patients.

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.