Interleukin-10 gene-deficient mice develop a primary intestinal permeability defect in response to enteric microflora

Area of Science:

• Immunology
• Gastroenterology
• Molecular Biology

Background:

• The intestinal epithelium acts as a barrier, but inflammatory bowel disease (IBD) is linked to increased intestinal permeability.
• It remains unclear if heightened permeability precedes or results from IBD-related mucosal injury.

Purpose of the Study:

• To investigate whether increased intestinal permeability is a primary defect preceding mucosal inflammation in Interleukin-10 (IL-10) gene-deficient mice.
• To determine the role of the enteric microflora in this permeability defect.

Main Methods:

• Studied IL-10 gene-deficient mice at various ages (2 and 6 weeks).
• Assessed ileal and colonic permeability using histological and functional assays.
• Measured mucosal cytokine levels (interferon-gamma, tumor necrosis factor-alpha) and nitric oxide synthase activity.
• Compared conventional and germ-free IL-10 gene-deficient mice.

Main Results:

• At 2 weeks, IL-10 gene-deficient mice showed increased ileal and colonic permeability without histological injury.
• This defect correlated with elevated interferon-gamma and tumor necrosis factor-alpha, but not nitric oxide synthase.
• Colonic permeability remained high, while ileal permeability normalized by 6 weeks.
• Germ-free IL-10 gene-deficient mice had normal permeability, cytokine levels, and no inflammation.

Conclusions:

• Increased intestinal permeability in IL-10 gene-deficient mice is a primary defect preceding inflammation.
• This defect arises from a dysregulated immune response to the normal enteric microflora.
• The findings highlight the critical role of IL-10 in maintaining intestinal barrier function and immune homeostasis.