title: Glutamine and alanine-induced differential expression of intracellular IL-6, IL-8, and TNF-α in LPS-stimulated monocytes in human whole-blood.
abstract: To investigate the effects of the commonly-used immunomodulators l-glutamine, l-alanine, and the combination of both l-alanyl-l-glutamine (Dipeptamin(®)) on intracellular expression of IL-6, IL-8, and TNF-α during endotoxemia, lipopolysaccharide (LPS)-stimulated human monocytes in a whole blood system were investigated by flow cytometry. Whole blood of twenty-seven healthy volunteers was stimulated with LPS and incubated with three different amino acid solutions (1. l-glutamine, 2. l-alanine, 3. l-alanyl-l-glutamine, each concentration 2 mM, 5 mM, incubation time 3 h). CD14(+) monocytes were phenotyped in whole-blood and intracellular expression of cytokines was assessed by flow cytometry. Our investigations showed for the first time in whole blood probes, imitating best physiologically present cellular interactions, that l-glutamine caused a dose-independent inhibitory effect on IL-6 and TNF-α production in human monocytes stimulated with LPS. However, l-alanine had contrary effects on IL-6 expression, significantly upregulating expression of IL-6 in LPS-treated monocytes. The impact of l-alanine on the expression of TNF-α was comparable with glutamine. Neither amino acid was able to affect IL-8 production in LPS-stimulated monocytes. The combination of both did not influence significantly IL-6 and IL-8 expression in monocytes during endotoxemia, however strongly reduced TNF-α production. For the regulation of TNF-α, l-glutamine, l-alanine and the combination of both show a congruent and exponentiated downregulating effect during endotoxemia, for the modulation of IL-6, l-glutamine and l-alanine featured opposite regulation leading to a canceling impact of each other when recombining both amino acids.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Halle-Wittenberg University, Germany. christoph.raspe@uk-halle.de
authors.forename: C
authors.initials: C
authors.lastname: Raspé
authors.forename: E
authors.initials: E
authors.lastname: Czeslick
authors.forename: A
authors.initials: A
authors.lastname: Weimann
authors.forename: C
authors.initials: C
authors.lastname: Schinke
authors.forename: A
authors.initials: A
authors.lastname: Leimert
authors.forename: P
authors.initials: P
authors.lastname: Kellner
authors.forename: A
authors.initials: A
authors.lastname: Simm
authors.forename: M
authors.initials: M
authors.lastname: Bucher
authors.forename: A
authors.initials: A
authors.lastname: Sablotzki
mesh_terms: D000328:Adult; D000409:Alanine / Q000494:pharmacology*; D004151:Dipeptides / Q000494:pharmacology; D019446:Endotoxemia / Q000097:blood; D005434:Flow Cytometry; D005973:Glutamine / Q000494:pharmacology*; D006801:Humans; D015850:Interleukin-6 / Q000097:blood / Q000378:metabolism*; D016209:Interleukin-8 / Q000097:blood / Q000378:metabolism*; D042541:Intracellular Space / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology*; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism*
chemical_list: C508606:CXCL8 protein, human; D004151:Dipeptides; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D005973:Glutamine; D000409:Alanine