Immunological aspects of gastritis and pernicious anaemia

Autoimmune gastritis in type 1 diabetes: a clinically oriented review

CONTEXT

Autoimmune gastritis and pernicious anemia are common autoimmune disorders, being present in up to 2% of the general population. In patients with type 1 diabetes or autoimmune thyroid disease, the prevalence is 3- to 5-fold increased. This review addresses the epidemiology, pathogenesis, diagnosis, clinical consequences, and management of autoimmune gastritis in type 1 diabetic patients.

SYNTHESIS

Autoimmune gastritis is characterized by: 1) atrophy of the corpus and fundus; 2) autoantibodies to the parietal cell and to intrinsic factor; 3) achlorhydria; 4) iron deficiency anemia; 5) hypergastrinemia; 6) pernicious anemia may result from vitamin B12 deficiency; and 7) in up to 10% of patients, autoimmune gastritis may predispose to gastric carcinoid tumors or adenocarcinomas. This provides a strong rationale for screening, early diagnosis, and treatment. The management of patients with autoimmune gastritis implies yearly determination of gastrin, iron, vitamin B12 levels, and a complete blood count. Iron or vitamin B12 should be supplemented in patients with iron deficiency or pernicious anemia. Whether regular gastroscopic surveillance, including biopsies, is needed in patients with autoimmune gastritis/pernicious anemia is controversial. The gastric carcinoids that occur in these patients generally do not pose a great threat to life, whereas the danger of developing carcinoma is controversial. Nevertheless, awaiting a consensus statement, we suggest performing gastroscopy and biopsy at least once in patients with autoantibodies to the parietal cell, iron-, or vitamin B12-deficiency anemia, or high gastrin levels.

CONCLUSION

The high prevalence of autoimmune gastritis in type 1 diabetic patients and its possible adverse impact on the health of the patient provide a strong rationale for screening, early diagnosis, periodic surveillance by gastroscopy, and treatment.

Animal models of human disease: experimental autoimmune gastritis--a model for autoimmune gastritis and pernicious anemia

Human autoimmune gastritis is an organ-specific autoimmune disease of the stomach. It is characterized by the development of disease-specific autoantibodies and a pathology that specifically targets specialized cells within the gastric environment. The autoantigens associated with this disease have been defined as the gastric H+/K+ ATPase and intrinsic factor. The development of experimental disease models has been pivotal in our contemporary understanding of autoimmunity. Here we review mouse models of autoimmune gastritis and their relevance to human autoimmune gastritis associated with pernicious anemia. We appraise some historical as well as recent studies of experimental autoimmune gastritis (EAG), highlighting key findings that have formed the basis of our current understanding of the etiology and mechanism(s) associated with autoimmune gastritis. A precise understanding of the pathogenesis of autoimmune gastritis will permit the design of innovative and rational therapeutic strategies to prevent, arrest, ameliorate or reverse the disease.

A female with asymptomatic primary biliary cirrhosis associated with pernicious anemia

We experienced a female case with asymptomatic primary biliary cirrhosis that was associated with pernicious anemia after 16 years from the onset. She was 52 years old when she first visited a clinic in 1981 for liver dysfunction treatment. Antimitochondrial antibody was negative and antipyruvate dehydrogenase complex antibody was positive in a low titer in its immunoglobulin (Ig)M type. Histological examination of her liver revealed a presence of definite chronic non-suppurative destructive cholangitis with numerous epithelioid cell granuloma. She had been given 600 mg of the oral daily dose of ursodeoxycholic acid since 1992. Macrocytic anemia incidiously appeared in September 1999. An immunological examination detected negative antiparietal cell antibodies and positive anti-intrinsic factor antibodies. Her bone marrow smear showed numerous megaloblasts and serum vitamin B12 in her blood was low at 99 pg/mL. Severe reversed atrophic-type gastritis (type A gastritis) was demonstrated by the use of dye-endoscopy with Congo red. Her macrocytic anemia dramatically improved after intramuscular administration of vitamin B12. In conclusion, attention should be given to the association of pernicious anemia during the follow up of primary biliary cirrhosis.

Pemphigoid gestationis: a review

Pemphigoid gestationis is a rare autoimmune vesiculobullous skin disease closely related to the pemphigoid group of blistering disorders. It is unique in that it is most frequently associated with pregnancy. Diagnosis is made on the basis of the presence of a subepidermal vesicle on routine histologic examination and of linear deposition of the third component of complement along the basement membrane zone of perilesional skin. Abnormal expression of major histocompatibility complex class II molecules in the placenta may trigger the initiating immunologic event in this organ, which is followed by cross-reactivity with an antigen present in the skin and the characteristic cutaneous signs of the disease. The immunogenetics of this disorder are interesting. A role for the involvement of major histocompatibility complex class II antigens seems likely because of the association with human leukocyte antigens DR3 and DR4. Major histocompatibility complex class III associations have also been observed, as has a high frequency of anti-human leukocyte antigen antibodies. We review the current understanding of the molecular biologic and immunogenetic properties of this disease and discuss treatment and potential impact on the fetus.

Coincidental occurrence of pernicious anemia and mycosis fungoides in two elderly males

We experienced two rare cases of pernicious anemia that presented in the course of mycosis fungoides in elderly males. Pernicious anemia has recently been reported to be caused by autoimmune gastritis that produces autoantibodies to gastric parietal cells and intrinsic factor. Immunological abnormalities in mycosis fungoides are reported to induce autoimmune diseases (i.e., autoimmune hemolytic anemia, anti-phospholipid antibody syndrome, arthritis, myasthenia gravis, necrotizing vasculitis, and vitiligo); the pernicious anemia in our two patients may have been closely related to the mycosis fungoides.

Vitiligo, rheumatoid arthritis and pernicious anemia

A patient with a 46-year history of vitiligo who also presented rheumatoid arthritis and pernicious anemia is described. Meticulous physical examination excluded further systemic or cutaneous involvement. The immunological workup revealed a low CD4 cell percentage with T cells mostly composed of CD8 cells, a discrepancy between the high percentage of cumulative CD4 + CD8 cells and the measured CD3 proportions, very low NK cytotoxicity toward K562 cells, and almost negligible responses to PHA, Con A and PWM mitogens. The results point to severe T and NK cell functional defects. The pathogenetic significance of these data is discussed.

A study of autoimmune gastritis in the postpartum period and at a 5-year follow-up

The presence of autoimmune gastritis was investigated in 54 women with postpartum thyroiditis. Parietal cell antibodies (PCA) specific against H+, K(+)-adenosine triphosphatase (EC 3.6.1.36) were found in 18 women during pregnancy; in 10 of them, a 2-9-fold increase in the PCA level was observed in the postpartum period. At a 5-year follow-up, the initially PCA-positive women still had elevated antibody levels. Hypergastrinemia and low pepsinogen levels were noted in 4 women. In 2 of these women low serum vitamin B12 levels had developed. In 6 of 9 PCA-positive women examined by gastroscopy, biopsy specimens from the gastric body mucosa contained mononuclear cells, mainly T lymphocytes (CD3+) and macrophages (Leu-M3+) combined with an aberrant epithelial expression of HLA-DR. In four patients with chronic gastritis, all parietal cells, as defined by a specific monoclonal antibody, were found to have immunoglobulin G (IgG) deposits by a double-immunostaining method. Three of them had microscopic evidence of atrophy, whereas in 1 patient the body mucosa was intact. In 1 further patient with intact glands at histological examination, the basolateral membrane of some oxyntic glands was coated with IgG. The selective in situ deposition of antibodies associated with histologically intact parietal cells may support the concept that specific autoantibodies participate in the early pathogenesis of parietal cell destruction.

Secondary autoimmune diseases in herpes gestationis (pemphigoid gestationis)

BACKGROUND

Herpes gestationis (HG) is an autoimmune disease of the skin that occurs exclusively in association with pregnancy (or trophoblastic disease). It is associated with the HLA-DR3 and -DR4 antigens that are also associated with several other autoimmune diseases. HG has previously been reported in association with Graves' disease.

OBJECTIVE

Our purpose was to determine the frequency of other autoimmune disease(s) in patients with a history of HG.

METHODS

Seventy-five patients with a history of HG were studied for the frequency of other autoimmune diseases.

RESULTS

We found an increased frequency of Graves' disease in patients with a history of HG. Those with HG have an increased risk for the development of other autoantibodies. There is an increased frequency of autoimmune diseases in the family members of patients with HG.

CONCLUSION

Secondary autoimmune disease in HG is unusual, but does occur. The most frequent is Graves' disease.

Parietal cell antibodies in pernicious anemia inhibit H+, K+-adenosine triphosphatase, the proton pump of the stomach

Antibodies to a membrane-bound antigen, localized to the canalicular structures of the parietal cell, are found in most sera of patients with chronic atrophic gastritis and pernicious anemia. In the present study immunoglobulins containing parietal cell antibodies were found to inhibit the activity of H+,K+-adenosine triphosphatase (EC 3.6.1.36) in a tubulovesicular membrane preparation from porcine gastric mucosa. The degree of inhibition correlated to the titer of parietal cell antibodies as assessed by an enzyme-linked immunosorbent assay. The specificity of the enzymatic inhibition was confirmed by the lack of effect of parietal cell antibodies on membrane-bound esterase. A possible interaction of parietal cell antibodies with gastrin binding at the receptor level was investigated in a radioreceptor assay employing 125I-gastrin 1 and gastric mucosal cell suspension from the guinea pig. No blocking capacity was found with immunoglobulins from patients with pernicious anemia as compared with immunoglobulins from healthy controls. The results thus demonstrate a direct inhibitory effect of parietal cell antibodies on the acid producing H+,K+-adenosine triphosphatase of the parietal cell, but also a lack of interaction with the gastrin receptor, and indicate that in the development of hypo/achylia H+,K+-adenosine triphosphatase autoantibodies could have a major pathogenic role.