Interleukin-10 Gene-deficient Mice Research Articles

Interferon-γ and Interleukin-10 Reciprocally Regulate Endothelial Junction Integrity and Barrier Function

Inflammatory bowel disease (IBD) is associated with Th1/Th2 cytokine dysregulation, leukocyte extravasation, and tissue edema, but the mechanisms for cytokine-mediated vascular dysfunction are not understood. To investigate how cytokines might control edema in IBD, we determined vascular permeability and IFN-γ expression in two models of murine colitis: SCID mice reconstituted with CD45RBhigh T-lymphocytes (CD45RBhigh/SCID mice), and interleukin-10 gene deficient (IL-10−/−) mice. We also investigated the in vitro effects of IFN-γ and IL-10 on human endothelial solute barrier and junction protein expression. Vascular permeability in CD45RBhigh/SCID and IL-10−/− mice was quantified using tissue 131I-IgG accumulation. The IFN-γ message was quantified using the ribonuclease protection assay. Endothelial barrier integrity in vitro was measured by transmonolayer electrical resistance, and junctional proteins were examined by immunoblotting and fluorescence microscopy. Both CD45RBhigh/SCID and IL-10−/− mice exhibit enhanced colonic microvascular leakage and IFN-γ message levels compared to their respective controls. In vitro, IFN-γ also reduced endothelial barrier (monolayer electrical resistance, increased albumin permeability) and reduced tight junction (occludin) expression and staining. These effects were reversed by pretreatment of monolayers with IL-10. Therefore, in vivo IFN-γ and IL-10 may modulate microvascular leakage in IBD partly by controlling the expression of intestinal endothelial tight junctional proteins.

Studies on the Interleukin-10 Gene in Animal Models of Colitis

Cytokines play a role in the inflammatory process in colitis and may have therapeutic potential. Interleukin-10 (IL-10) has both immunomodulatory and anti-inflammatory properties. IL-10-deficient mice develop intestinal inflammation with increased tissue levels of other cytokines, including tumour necrosis factor-alpha. In patients with inflammatory bowel disease, impaired IL-10 production by lamina propria T cells occurs and human recombinant IL-10 improves clinical parameters in inflammatory bowel disease (eg, Crohn's disease). There seem to be conflicting results in differing animal models, and the timing of administration of IL-10 relative to onset of colitis may be critical, possibly due to rapid clearance of IL-10. Interestingly, in IL-10 gene-deficient mice raised in germ-free conditions, the intestinal inflammatory changes normally observed in conventional nongerm-free conditions are not detected, suggesting a role for luminal bacteria in the pathogenesis of the inflammatory process.