ABSTRACT
BACKGROUND: Pharmacologic doses of glutamine (GLN) can improve clinical outcome following acute illness and injury. Recent studies indicate enhanced heat shock protein (HSP) expression is a key mechanism underlying GLN's protection. However, such a link has not yet been tested in chronic inflammatory states, such as experimental inflammatory bowel disease (IBD). METHODS: Experimental colitis was induced in Sprague-Dawley rats via oral 5% dextran sulfate sodium (DSS) for 7 days. GLN (0.75 g/kg/d) or sham was administered to rats by oral gavage during 7-day DSS treatment. In vitro inflammatory injury was studied using YAMC colonic epithelial cells treated with varying concentrations of GLN and cytokines (tumor necrosis factor-α/interferon-γ). RESULTS: Pharmacologic dose, bolus GLN attenuated DSS-induced colitis in vivo with decreased area under curve for bleeding (8.06 ± 0.87 vs 10.38 ± 0.79, P < .05) and diarrhea (6.97 ± 0.46 vs 8.53 ± 0.39, P < .05). This was associated with enhanced HSP25 and HSP70 in colonic mucosa. In vitro, GLN enhanced cell survival and reduced proapoptotic caspase3 and poly(ADP-ribose) polymerase cleavage postcytokine injury. Cytokine-induced inducible nitric oxide synthase expression and nuclear translocation of nuclear factor-κB p65 subunit were markedly attenuated at GLN concentrations above 0.5 mmol/L. GLN increased cellular HSP25 and HSP70 in a dose-dependent manner. CONCLUSIONS: These data demonstrate the therapeutic potential of GLN as a "pharmacologically acting nutrient" in the setting of experimental IBD. GLN sufficiency is crucial for the colonic epithelium to mount a cell-protective, antiapoptotic, and anti-inflammatory response against inflammatory injury. The enhanced HSP expression observed following GLN treatment may be responsible for this protective effect.
Subject(s)
Colitis/drug therapy , Colon/drug effects , Glutamine/therapeutic use , Heat-Shock Proteins/metabolism , Inflammatory Bowel Diseases/drug therapy , Intestinal Mucosa/drug effects , Animals , Area Under Curve , Caspase 3/metabolism , Cell Survival/drug effects , Colitis/complications , Colitis/metabolism , Colon/metabolism , Cytokines/metabolism , Dextran Sulfate , Diarrhea/drug therapy , Diarrhea/etiology , Diarrhea/metabolism , Disease Models, Animal , Dose-Response Relationship, Drug , Epithelial Cells/drug effects , Epithelial Cells/metabolism , Glutamine/pharmacology , HSP70 Heat-Shock Proteins/metabolism , Hemorrhage/drug therapy , Hemorrhage/etiology , Hemorrhage/metabolism , Inflammatory Bowel Diseases/complications , Inflammatory Bowel Diseases/metabolism , Intestinal Mucosa/cytology , Intestinal Mucosa/metabolism , Male , Mice , NF-kappa B/metabolism , Nitric Oxide Synthase Type II/metabolism , Poly(ADP-ribose) Polymerases/metabolism , Rats , Rats, Sprague-DawleyABSTRACT
BACKGROUND: Generalized vitiligo is an autoimmune disease characterized by melanocyte loss, which results in patchy depigmentation of skin and hair, and is associated with an elevated risk of other autoimmune diseases. METHODS: To identify generalized vitiligo susceptibility loci, we conducted a genomewide association study. We genotyped 579,146 single-nucleotide polymorphisms (SNPs) in 1514 patients with generalized vitiligo who were of European-derived white (CEU) ancestry and compared the genotypes with publicly available control genotypes from 2813 CEU persons. We then tested 50 SNPs in two replication sets, one comprising 677 independent CEU patients and 1106 CEU controls and the other comprising 183 CEU simplex trios with generalized vitiligo and 332 CEU multiplex families. RESULTS: We detected significant associations between generalized vitiligo and SNPs at several loci previously associated with other autoimmune diseases. These included genes encoding major-histocompatibility-complex class I molecules (P=9.05x10(-23)) and class II molecules (P=4.50x10(-34)), PTPN22 (P=1.31x10(-7)), LPP (P=1.01x10(-11)), IL2RA (P=2.78x10(-9)), UBASH3A (P=1.26x10(-9)), and C1QTNF6 (P=2.21x10(-16)). We also detected associations between generalized vitiligo and SNPs in two additional immune-related loci, RERE (P=7.07x10(-15)) and GZMB (P=3.44x10(-8)), and in a locus containing TYR (P=1.60x10(-18)), encoding tyrosinase. CONCLUSIONS: We observed associations between generalized vitiligo and markers implicating multiple genes, some associated with other autoimmune diseases and one (TYR) that may mediate target-cell specificity and indicate a mutually exclusive relationship between susceptibility to vitiligo and susceptibility to melanoma.