Intestinal epithelial cells are a crucial cell type in the maintenance of the health of colonic tissue, providing a barrier between the contents of the colon, such as bacteria and foreign food antigens, and the immune system. IBD is characterized by a breakdown of the intestinal epithelial barrier leading to increased exposure of the immune system to these contents. This exposure leads to inflammation and increased breakdown of the epithelial barrier. It is now appreciated that inflammatory responses in IBD are accompanied by striking shifts in tissue metabolism, including key metabolites involved in cellular methylation. Methylation reactions are a critical component of the control of gene expression, as well as protein function. Additionally, studies have shown that changes in cellular methylation reactions play an important role in inflammatory processes and immune system modulation. These studies have revealed that epigenetic changes in DNA methylation patterns can have important consequences for these processes. Since the epithelium functions as the critical interface between the intestinal lumen and the sub-epithelial mucosa, they are thereby anatomically positioned as a central coordinator of mucosal inflammatory response and have been found to be important for control of immune system and inflammatory responses. Ongoing studies have focused on defining molecular pathways and functional targets of cellular methylation during mucosal inflammation. The initial analysis of the metabolic signature induced during inflammation in epithelial models and in colonic tissue isolated from mouse colitis models demonstrated that levels of specific metabolites associated with cellular methylation reactions are altered during epithelial inflammation in both model systems. Furthermore, expression of an enzymes central to all cellular methylation, SAM synthetase and SAH hydrolase, is increased in cells in response to inflammation. Importantly, we demonstrate that genome-wide DNA methylation is increased during hypoxia and that at least one IFN-?- regulated gene, IL-10R1, is impacted by these processes. Furthermore, we demonstrate that epithelial IL- 10R1 and IL-10 signaling play a critical role in epithelial homeostasis and inflammation resolution. These results indicate that epigenetic mechanisms play a role in the epithelial responses during inflammation. We have demonstrated that inhibition of cellular methylation exacerbates disease in mouse models of colitis indicating that these processes are protective of the epithelium. As guided by these studies, we hypothesize that IFN-?-induced epigenetic alterations modify gene expression as an integral aspect of epithelial inflammatory pathways and that alteration of DNA methylation represents a protective mechanism for the epithelium during intestinal inflammation. In this application, we will define the molecular endpoints of IFN-? regulation of cellular methylation. More importantly, we propose that these IFN-?-mediated methylation pathways could serve as templates for the development, testing and implementation as promising IBD therapies.

Public Health Relevance

Ongoing experiments have revealed that cellular methylation represents an important and underappreciated modulator of the inflammatory response. This project will elucidate the mechanisms of IFN-? regulation of cellular methylation reactions and epigenetic modifications induced during inflammation in both human epithelial cell and mouse colitis models. Based on preliminary studies, we hypothesize that methylation- dependent pathways regulate the expression of genes such as IL-10R1 that are protective of the mucosal epithelium. The studies proposed here will more fully examine IFN-?-dependent mechanisms and epigenetic targets induced under conditions of ongoing inflammation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
1R01DK099452-01A1
Application #
8761974
Study Section
Gastrointestinal Mucosal Pathobiology Study Section (GMPB)
Program Officer
Hamilton, Frank A
Project Start
2014-08-01
Project End
2018-04-30
Budget Start
2014-08-01
Budget End
2015-04-30
Support Year
1
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Colorado Denver
Department
Anesthesiology
Type
Schools of Medicine
DUNS #
City
Aurora
State
CO
Country
United States
Zip Code
80045
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Lanis, J M; Alexeev, E E; Curtis, V F et al. (2017) Tryptophan metabolite activation of the aryl hydrocarbon receptor regulates IL-10 receptor expression on intestinal epithelia. Mucosal Immunol 10:1133-1144
Kao, Daniel J; Lanis, Jordi M; Alexeev, Erica et al. (2016) NMR-Based Metabolomic Analysis of Normal and Inflamed Gut. Methods Mol Biol 1422:77-87
Kao, Daniel J; Lanis, Jordi M; Alexeev, Erica et al. (2016) HPLC-Based Metabolomic Analysis of Normal and Inflamed Gut. Methods Mol Biol 1422:63-75
Frasch, S Courtney; McNamee, Eóin N; Kominsky, Douglas et al. (2016) G2A Signaling Dampens Colitic Inflammation via Production of IFN-?. J Immunol 197:1425-34
Colgan, Sean P; Campbell, Eric L; Kominsky, Douglas J (2016) Hypoxia and Mucosal Inflammation. Annu Rev Pathol 11:77-100
Kelly, Caleb J; Zheng, Leon; Campbell, Eric L et al. (2015) Crosstalk between Microbiota-Derived Short-Chain Fatty Acids and Intestinal Epithelial HIF Augments Tissue Barrier Function. Cell Host Microbe 17:662-71
Kominsky, Douglas J; Campbell, Eric L; Ehrentraut, Stefan F et al. (2014) IFN-?-mediated induction of an apical IL-10 receptor on polarized intestinal epithelia. J Immunol 192:1267-76
Campbell, Eric L; Bruyninckx, Walter J; Kelly, Caleb J et al. (2014) Transmigrating neutrophils shape the mucosal microenvironment through localized oxygen depletion to influence resolution of inflammation. Immunity 40:66-77
Keely, S; Campbell, E L; Baird, A W et al. (2014) Contribution of epithelial innate immunity to systemic protection afforded by prolyl hydroxylase inhibition in murine colitis. Mucosal Immunol 7:114-23

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