The Autoimmune Gastritis Puzzle: Emerging Cellular Crosstalk and Molecular Pathways Driving Parietal Cell Loss and ECL Cell Hyperplasia

T-cells, epithelial stress pathways, and microbial factors. Parietal cell loss results in achlorhydria, intrinsic factor deficiency, and vitamin B12 malabsorption, ultimately leading to pernicious anemia. Compensatory hypergastrinemia promotes enterochromaffin-like (ECL) cell hyperplasia and contributes to the development of type 1 gastric neuroendocrine neoplasms (gNENs). These clinical consequences are well recognized, yet the cellular and molecular mechanisms driving mucosal atrophy and neoplastic transformation remain incompletely defined. Recent advances highlight the role of endoplasmic reticulum stress, impaired autophagy, innate immune effectors, and dysbiosis in perpetuating inflammation and epithelial injury. The frequent coexistence of AIG with other autoimmune disorders further adds to its clinical complexity. Therapeutic options remain limited, spanning vitamin B12 replacement and endoscopic management to emerging targeted approaches. Netazepide, a gastrin/CCK2 receptor antagonist, is the only agent tested in clinical trials, whereas interventions targeting ER stress, autophagy, immune tolerance, or microbiome composition are still in the preclinical stage. Clarifying these mechanisms is crucial to improve biomarker development, optimize surveillance, and identify targeted therapies to prevent neoplastic transformation.