Metabolomic Analysis Identifies Inflammatory and Noninflammatory Metabolic Effects of Genetic Modification in a Mouse Model of Crohn’s Disease

Abstract

Interleukin-10 is an immunosuppressive cytokine involved in the regulation of gastrointestinal mucosal immunity toward intestinal microbiota. Interleukin-10-deficient (IL10(-/-)) mice develop Crohn's disease-like colitis unless raised in germ-free conditions. Previous gas chromatography-mass spectrometry (GC-MS) metabolomic analysis revealed urinary metabolite differences between IL10(-/-) and wildtype C57BL/6 mice. To determine which of these differences were specifically associated with intestinal inflammation arising from IL10-deficiency, urine samples from IL10(-/-) and wildtype mice, housed in either conventional or specific pathogen-free conditions, were subjected to GC-MS metabolomic analysis. Fifteen metabolite differences, including fucose, xanthurenic acid, and 5-aminovaleric acid, were associated with intestinal inflammation. Elevated urinary levels of xanthurenic acid in IL10(-/-) mice were attributed to increased production of kynurenine metabolites that may induce T-cell tolerance toward intestinal microbiota. Liquid chromatography-mass spectrometry analysis confirmed that plasma levels of kynurenine and 3-hydroxykynurenine were elevated in IL10(-/-) mice. Eleven metabolite differences, including glutaric acid, 2-hydroxyglutaric acid, and 2-hydroxyadipic acid, were unaffected by the severity of inflammation. These metabolite differences may be associated with residual genes from the embryonic stem cells of the 129P2 mouse strain that were used to create the IL10(-/-) mouse, or may indicate novel functions of IL10 unrelated to inflammation.

Urinary metabolites as noninvasive biomarkers of gastrointestinal diseases: A clinical review

“…In another study on IL-10 gene deficient mice, Lin et al [17] showed an association between 15 metabolites including fucose, xanthurenic acid, and 5-aminovaleric acid with intestinal inflammation. Elevated urinary xanthu renic acid in gene deficient mice was linked to increased plasma levels of kynurenine [17] .…”

“…Elevated urinary xanthu renic acid in gene deficient mice was linked to increased plasma levels of kynurenine [17] . In a further study, the same group validated these findings by showing that feeding IL-10 gene-deficient and wild-type mice with Kiwifruit increases Kiwifruit-derived urinary metabolites more significantly in IL-10 genedeficient mice compared to wild-type mice without affecting urinary metabolites levels previously associated with inflammation [18] .…”

“…Bacterial lipopolysaccharides and proinflammatory cytokines are the activators of this pathway and its metabolites act as the moderators of T-cell tolerance to intestinal microbiota. As colitis does not usually develop in germ-free IL-10 gene deficient mice, the role of intestinal microbiota looks considerable in the induction of urinary metabolomics alterations during colitis [17,[19][20][21] . Although, overall studies indicated that IL-10 gene deficient mice have different urinary metabolomics profile compared to wild-type mice, Tso et al [22] showed that these differences are gender and age specific.…”

Animal Models of Colitis: Lessons Learned, and Their Relevance to the Clinic

“…Eleven metabolites, including glutaric acid, 2-hydroxyglutaric acid and 2-hydroxyadipic acid, were significantly different in Il10 -/-compared with C57 mice, but these differences were not related to the severity of inflammation, and were possibly associated with the genetic manipulation that produced these animals, rather than any inflammatory-related function of IL-10. In contrast, fucose, xanthurenic acid and 5-aminovaleric acid were among fifteen metabolite differences associated with intestinal inflammation (Lin et al, 2010). The presence of defined metabolites associated with inflammation may be of benefit in enabling a non-invasive measurement of the severity of inflammation in human IBD.…”

“…We have shown that food components such as polyunsaturated fatty acids (Knoch et al, 2009;Knoch et al, 2010) can prevent or ameliorate the level of intestinal inflammation, and have characterized changes in gene expression in association with this change in inflammation to better understand the mechanisms through which such food components might be acting. We have also used metabolomic analysis to measure urinary metabolite differences between Il10 -/-and wildtype C57BL/6 mice, and to determine which of these differences were associated with intestinal inflammation (Lin et al, 2010). Eleven metabolites, including glutaric acid, 2-hydroxyglutaric acid and 2-hydroxyadipic acid, were significantly different in Il10 -/-compared with C57 mice, but these differences were not related to the severity of inflammation, and were possibly associated with the genetic manipulation that produced these animals, rather than any inflammatory-related function of IL-10.…”