Inflammatory bowel disease: An archetype disorder of outer environment sensor systems

Area of Science:

• Immunology
• Genetics
• Gastroenterology

Background:

• The exact causes of inflammatory bowel diseases (IBDs), including ulcerative colitis (UC) and Crohn's disease (CD), remain unclear, hindering cure development.
• IBDs involve complex inflammation with extra-intestinal manifestations and links to autoimmune disorders, with genetics suggesting multi-organ involvement.
• Previously, mutations in the nucleotide-oligomerization domain (NOD) gene in CD were an exception, revealing it as an immune deficiency.

Purpose of the Study:

• To re-evaluate the understanding of Crohn's disease (CD) and its relationship with other inflammatory conditions.
• To introduce a new classification of "barrier organ disease" encompassing CD, psoriasis, and chronic pulmonary disease.
• To highlight the implications of this new classification for future research and personalized medicine.

Main Methods:

• Review of genetic studies, particularly focusing on NOD gene mutations in Crohn's disease.
• Analysis of the association between NOD mutations and other inflammatory conditions like Blau syndrome, psoriasis, and COPD.
• Conceptual framework development for "barrier organ disease" based on shared characteristics.

Main Results:

• NOD gene mutations in CD suggest an immune deficiency state, particularly in Caucasian patients.
• Similarities in disease mechanisms are observed between CD, Blau syndrome, psoriasis, and chronic obstructive pulmonary disease.
• A new category, "barrier organ disease," is proposed for conditions affecting mucosal/epithelial surfaces with microbial interactions.

Conclusions:

• Crohn's disease can be viewed as a "barrier organ disease" due to its immune deficiency and interaction with microbial environments.
• This novel classification revolutionizes the understanding of IBD and related disorders.
• The "barrier organ disease" concept facilitates personalized treatments and cross-phenotype research.