Autoimmune atrophic gastritis

Clinic

• Atrophic gastritis is a process of chronic inflammation of the gastric mucosa of the stomach, leading to a loss of gastric glandular cells and their eventual replacement by intestinal and fibrous tissues.
• As a result, the stomach's secretion of essential substances such as hydrochloric acid, pepsin, and intrinsic factor is impaired, leading to digestive problems. The most common are vitamin B₁₂ deficiency possibly leading to pernicious anemia and iron deficiency anemia.
• It can be caused by persistent infection with Helicobacter pylori, or can be autoimmune in origin.
• Atrophic gastritis is characterised by stomach atrophy and the presence of antibodies to parietal cells and intrinsic factor.

• The exact role of Helicobacter pylori infection in PA remains controversial, evidence indicates
• Less commonly, H. pylori and Zollinger-Ellison syndrome may cause a form of nonautoimmune gastritis that can lead to pernicious anemia.

Types

• Autoimmune atrophic gastritis (Type A gastritis) is statistically more likely to develop gastric carcinoma, Hashimoto's thyroiditis, and achlorhydria.
• Type A gastritis primarily affects the fundus (body) of the stomach and is more common with pernicious anemia.
• Type B gastritis primarily affects the antrum, and is more common with H. pylori infection.

Signs / Symptoms

• Some people with atrophic gastritis may be asymptomatic.
• That said, symptomatic patients are mostly females and signs of atrophic gastritis are those associated with iron deficiency: fatigue, restless legs syndrome, brittle nails, hair loss, impaired immune function, and impaired wound healing.
• Other symptoms, such as delayed gastric emptying (80%), reflux symptoms (25%), peripheral neuropathy (25% cases), autonomic abnormalities, and memory loss, are less common and occur in 1%–2% of cases.
• Other psychiatric disorders are also reported, such as mania, depression, obsessive compulsive disorder, psychosis and cognitive impairment.
• Although, autoimmune atrophic gastritis impairs iron and vitamin B₁₂ absorption, iron deficiency will be found at a younger age and many years before the development of pernicious anemia.

Related disease

• They have increased risk for the development of gastric adenocarcinoma.
• Pernicious anemia

Causes

• Autoimmune metaplastic atrophic gastritis (AMAG) is a result of the immune system attacking the parietal cells.
• Environmental metaplastic atrophic gastritis (EMAG) is due to environmental factors, such as diet and H. pylori infection. It is typically confined to the body of the stomach. Patients with EMAG are also at increased risk of gastric carcinoma.

Pathophysiology

• AMAG is an inherited form of atrophic gastritis characterized by an immune response directed toward parietal cells and intrinsic factor.
• The presence of serum antibodies to parietal cells and to intrinsic factor are characteristic findings.
• The autoimmune response subsequently leads to the destruction of parietal cells, which leads to profound Achlorhydria (and elevated gastrin levels).
• The inadequate production of intrinsic factor also leads to vitamin B₁₂ malabsorption and pernicious anemia.
• AMAG is typically confined to the gastric body and fundus.

Miasms

• EBV: EBV was detected in 12% of the cases with gastritis without H. pylori infection. Endoscopic follow-up may be appropriate for patients with gastritis, who have atrophy without intestinal metaplasia and are H. pylori negative but EBV positive.

• HCV: A close association has been reported between autoimmune thyroiditis and autoimmune (i.e. type A) gastritis.