The changing immunological paradigm in coeliac disease

Area of Science:

• Immunology
• Gastroenterology
• Pathology

Background:

• Coeliac disease is often mischaracterized as a classical inflammatory disorder.
• The tissue reaction in coeliac disease differs significantly from inflammatory bowel diseases like ulcerative colitis and Crohn's disease.
• Understanding the precise immunological mechanisms is crucial for accurate diagnosis and treatment.

Purpose of the Study:

• To elucidate the true nature of the mucosal lesion in coeliac disease.
• To differentiate the pathogenetic mechanisms of coeliac disease from typical inflammatory bowel disorders.
• To propose a refined model for coeliac disease pathogenesis.

Main Methods:

• Analysis of the immunological and tissue reaction within the mucosal lesion.
• Comparison of coeliac disease pathology with inflammatory bowel diseases.
• Investigation of innate and adaptive immune system involvement, including cytokine roles and cellular responses.

Main Results:

• Coeliac lesions are primarily characterized by immune-driven remodelling of mucosal architecture, with a minor inflammatory component.
• Early innate immune signals, potentially involving complement split products and interleukin-15, activate immune cells.
• Persistent signaling leads to adaptive immunopathology, yet mucosal homeostasis is maintained, evidenced by dominant secretory IgA production.

Conclusions:

• Coeliac disease pathogenesis involves a two-signal model: innate immunity (signal 1) and adaptive immunity (signal 2).
• Immune activation in the epithelial compartment is key, contrasting with microvascular changes in inflammatory bowel disease.
• The findings necessitate a shift in focus from classical inflammation to immune-driven remodelling in understanding coeliac disease.