J Immunol. 2014 Oct 1;193(7):3683-92. doi: 10.4049/jimmunol.1400347. Epub 2014 Sep 3.

Crucial role of macrophage selenoproteins in experimental colitis.

Kaushal N1, Kudva AK1, Patterson AD1, Chiaro C1, Kennett MJ1, Desai D2, Amin S2, Carlson BA3, Cantorna MT1, Prabhu KS4.

• 1Center for Molecular Immunology and Infectious Disease and Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802;
• 2Department of Pharmacology, Penn State College of Medicine, Hershey, PA 17033; and.
• 3Molecular Biology of Selenium Section, Mouse Cancer Genetics Program, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892.
• 4Center for Molecular Immunology and Infectious Disease and Center for Molecular Toxicology and Carcinogenesis, Department of Veterinary and Biomedical Sciences, The Pennsylvania State University, University Park, PA 16802; ksprabhu@psu.edu.

Abstract

Inflammation is a hallmark of inflammatory bowel disease (IBD) that involves macrophages. Given the inverse link between selenium (Se) status and IBD-induced inflammation, our objective was to demonstrate that selenoproteins in macrophages were essential to suppress proinflammatory mediators, in part, by the modulation of arachidonic acid metabolism.

Acute colitis was induced using 4% dextran sodium sulfate in wild-type mice maintained on

• Se-deficient (<0.01 ppm Se),
• Se-adequate (0.08 ppm; sodium selenite), and two supraphysiological levels in the form of
• Se-supplemented (0.4 ppm; sodium selenite) and high Se (1.0 ppm; sodium selenite) diets.

Selenocysteinyl transfer RNA knockout mice (Trsp(fl/fl)LysM(Cre)) were used to examine the role of selenoproteins in macrophages on disease progression and severity using histopathological evaluation, expression of proinflammatory and anti-inflammatory genes, and modulation of PG metabolites in urine and plasma.

Whereas Se-deficient and Se-adequate mice showed increased colitis and exhibited poor survival, Se supplementation at 0.4 and 1.0 ppm increased survival of mice and decreased colitis-associated inflammation with an upregulation of expression of proinflammatory and anti-inflammatory genes.

Metabolomic profiling of urine suggested increased oxidation of PGE2 at supraphysiological levels of Se that also correlated well with Se-dependent upregulation of 15-hydroxy-PG dehydrogenase (15-PGDH) in macrophages. Pharmacological inhibition of 15-PGDH, lack of selenoprotein expression in macrophages, and depletion of infiltrating macrophages indicated that macrophage-specific selenoproteins and upregulation of 15-PGDH expression were key for Se-dependent anti-inflammatory and proresolving effects. Selenoproteins in macrophages protect mice from dextran sodium sulfate-colitis by enhancing 15-PGDH-dependent oxidation of PGE2 to alleviate inflammation, suggesting a therapeutic role for Se in IBD.

Copyright © 2014 by The American Association of Immunologists, Inc.

PMID:  25187657