Soluble epoxide hydrolase gene deficiency or inhibition attenuates chronic active inflammatory bowel disease in IL-10(-/-) mice

BACKGROUND

Soluble epoxide hydrolase (sEH) metabolizes anti-inflammatory epoxyeicosatrienoic acids (EETs) into their much less active dihydroxy derivatives dihydroxyeicosatrienoic acids. Thus, targeting sEH would be important for inflammation.

AIMS

To determine whether knockout or inhibition of sEH would attenuate the development of inflammatory bowel disease (IBD) in a mouse model of IBD in IL-10(-/-) mice.

METHODS

Either the small molecule sEH inhibitor trans/-4-[4-(3-adamantan-1-yl-ureido)-cyclohexyloxy]-benzoic acid (t-AUCB) or sEH knockout mice were used in combination with IL-10(-/-) mice. t-AUCB was administered to mice in drinking fluid. Extensive histopathologic, immunochemical, and biochemical analyses were performed to evaluate effect of sEH inhibition or deficiency on chronic active inflammation and related mechanism in the bowel.

RESULTS

Compared to IL-10 (-/-) mice, sEH inhibition or sEH deficiency in IL-10(-/-) mice resulted in significantly lower incidence of active ulcer formation and transmural inflammation, along with a significant decrease in myeloperoxidase-labeled neutrophil infiltration in the inflamed bowel. The levels of IFN-γ, TNF-α, and MCP-1, as well VCAM-1 and NF-kB/IKK-α signals were significantly decreased as compared to control animals. Moreover, an eicosanoid profile analysis revealed a significant increase in the ratio of EETs/DHET and EpOME/DiOME, and a slightly down-regulation of inflammatory mediators LTB(4) and 5-HETE.

CONCLUSION

These results indicate that sEH gene deficiency or inhibition reduces inflammatory activities in the IL-10 (-/-) mouse model of IBD, and that sEH inhibitor could be a highly potential in the treatment of IBD.

Bifidobacterium animalis causes extensive duodenitis and mild colonic inflammation in monoassociated interleukin-10-deficient mice

BACKGROUND

We recently showed that Bifidobacterium animalis is more prevalent within the colons of interleukin (IL)-10-deficient (-/-) mice than in wildtype (WT) animals colonized with the same specific pathogen-free (SPF) fecal contents. Here we tested the ability of this organism to cause T-cell-mediated intestinal inflammation by introducing it into germ-free (GF) IL-10-/- mice.

METHODS

GF IL-10-/- or WT mice were monoassociated with Bifidobacterium animalis subsp. animalis ATCC (American Type Culture Collection, Manassas, VA) 25527(T) or with B. infantis ATCC 15697(T). Inflammation was measured by blinded histologic scores of the duodenum, cecum, and colon and by spontaneous secretion of IL-12/IL-23 p40 from colonic explants. Bacterial antigen-specific CD4(+) mesenteric lymph node (MLN) T-cell recall responses were measured in response to antigen-presenting cells (APC) pulsed with bacterial lysates.

RESULTS

B. animalis caused marked duodenal inflammation and mild colitis in monoassociated IL-10-/- mice, whereas the intestinal tracts of WT animals remained free of inflammation. B. infantis colonization resulted in mild inflammation in the duodena of IL-10-/- mice. CD4(+) MLN T cells from B. animalis monoassociated IL-10-/- mice secreted high levels of IFN-gamma and IL-17 in response to B. animalis lysate. B. animalis equally colonized the different intestinal regions of WT and IL-10-/- mice.

CONCLUSIONS

B. animalis, a traditional probiotic species that is expanded in experimental colitis in this model, induces marked duodenal and mild colonic inflammation and TH1/TH17 immune responses when introduced alone into GF IL-10-/- mice. This suggests a potential pathogenic role for this commensal bacterial species in a susceptible host.