Cell type-specific mechanisms coupling protease-activated receptor-1 to infectious colitis pathogenesis

Area of Science:

• Immunology
• Gastroenterology
• Molecular Biology

Background:

• Protease-activated receptor-1 (PAR-1) is implicated in various diseases, including colitis.
• PAR-1's broad expression across cell types complicates understanding its specific roles in disease pathogenesis.

Purpose of the Study:

• To elucidate the distinct contributions of PAR-1 in macrophages and colonic enterocytes to infectious colitis.
• To investigate the impact of cell type-specific PAR-1 deletion on Citrobacter rodentium colitis models.

Main Methods:

• Generated mice with conditional PAR-1 alleles, specifically deleting PAR-1 in myeloid (PAR-1ΔM) or enterocyte (PAR-1ΔEPI) lineages.
• Analyzed Citrobacter rodentium colitis pathogenesis in global PAR-1 knockout (PAR-1-/-) and cell type-specific knockout mice.

Main Results:

• Global PAR-1 deletion showed no impact on weight loss or inflammation but blunted colonic shortening and reduced IL-1β, IL-22, IL-6, and IL-17A.
• PAR-1ΔM mice exhibited reduced weight loss and crypt abscesses, with diminished CD3+ T cell infiltration and lower IL-1β levels.
• PAR-1ΔEPI mice showed increased crypt hypertrophy and abscess formation, with unaltered local cytokine levels compared to controls.

Conclusions:

• PAR-1 plays intricate, cell-specific roles in the immune response to Citrobacter colitis.
• Cell type-specific analyses are crucial for uncovering functions of broadly expressed receptors like PAR-1, which are masked in global knockout studies.