Glutamine decreases lipopolysaccharide-induced IL-8 production in Caco-2 cells through a non-NF-kappaB p50 mechanism.
Glutamine (Gln) supplementation has been shown to decrease production of pro-inflammatory cytokines by the human intestinal mucosa. The mechanism of this is poorly understood. We hypothesize that Gln down-regulates lipopolysaccharide (LPS)-stimulated pro-inflammatory cytokine production in Caco-2 cells by nuclear factor-kappa B (NF-kappaB). Caco-2 cells were incubated with different concentrations of Gln with or without methionine sulfoximine (MS, an inhibitor of glutamine synthetase) before stimulation with LPS. IL-6, IL-8, IL-10 and TNF-alpha protein and mRNA level were determined. NF-kappaB translocation was determined using an ELISA-based kit. IL-8 was the only detectable cytokine/chemokine. The largest amount of IL-8 was secreted by cells in the presence of MS with no Gln in the medium after exposure to LPS. LPS increased IL-8 production, peaking 10h after LPS administration. The addition of Gln (0.5 or 5.0mM) decreased IL-8 peptide and mRNA expression. LPS increased NF-kappaB nuclear translocation in the presence or absence of MS. Neither Gln nor MS altered NF-kappaB nuclear translocation. These results indicate that the lack of glutamine increases IL-8 production by Caco-2 cells after LPS stimulation. However, the glutamine-mediated decrease in LPS-stimulated IL-8 production is not associated with NF-kappaB p50 nuclear binding.
Huang
Ying
Y
Children's Hospital of Fudan University, 183 Fenglin Road, Shanghai 200032, People's Republic of China.
Li
Nan
N
Liboni
Kellym
K
Neu
Josef
J
D018938:Caco-2 Cells; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004797:Enzyme-Linked Immunosorbent Assay; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis* / Q000235:genetics; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism
D016209:Interleukin-8; D008070:Lipopolysaccharides; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D012333:RNA, Messenger; D005973:Glutamine; D004247:DNA