Colitis in HLA-B27/beta 2 microglobulin transgenic rats

Area of Science:

• Immunology
• Gastroenterology
• Genetics

Background:

• Transgenic rats expressing HLA-B27 and human beta-2 microglobulin develop chronic colitis and adenocarcinoma.
• This model exhibits extraintestinal manifestations similar to human spondyloarthropathy, including joint, skin, and genital inflammation.

Purpose of the Study:

• To investigate the mechanisms underlying gastrointestinal and systemic inflammation in HLA-B27 transgenic rats.
• To explore the role of antigen-presenting cells (APCs), T lymphocytes, and gut microbiota in disease pathogenesis.

Main Methods:

• Generation of HLA-B27 and human beta-2 microglobulin transgenic rats.
• Analysis of inflammatory cell populations (CD4+, CD8+ T cells) and APC function.
• Assessment of the role of specific gut bacteria (e.g., B. vulgatus, E. coli) in disease induction.
• Evaluation of bone marrow transplant and genetic modulation effects.

Main Results:

• Inflammation is T cell-mediated, with CD4+ cells playing a significant role.
• Disease development requires normal gut bacteria, with B. vulgatus being a potent inducer.
• Defective in vitro function of transgenic dendritic cells was observed, impacting peptide binding.
• Bone marrow transplantation from normal donors ameliorated inflammation and complications.

Conclusions:

• Gastrointestinal and systemic inflammation in B27 transgenic rats result from a loss of tolerance to enteric bacteria, linked to impaired APC function.
• Further research is needed to elucidate the precise mechanisms, including MHC binding, T cell responses, and cytokine secretion.