Aminoethyl-isothiourea inhibits leukocyte production of reactive oxygen species and proinflammatory cytokines induced by streptococcal cell wall components in human whole blood.
The incidence of severe invasive disease caused by serogroup A streptococci (GAS) is increasing, and to elucidate the role of streptococcal cell wall components in the inflammatory response, human whole blood was stimulated with lipoteichoic acid (LTA, 0.005-50 microg/mL) and peptidoglycan (10 and 100 microg/ml) from Streptococcus pyogenes. Both stimulants increased dose dependently the leukocyte release of cytokines many thousand fold: tumor necrosis factor alpha (0 to 158,000+/-4,900 pg/mL), interleukin (IL)-1beta (85+/-56 to 31,000+/-4,600 pg/mL), IL-6 (30+/-11 to 34,800+/-15,000 pg/mL), and IL-8 (300+/-150 to 29,000+/-14,000 pg/mL). Intracellular leukocyte levels of reactive oxygen species (ROS) as measured by flow cytometry increased 15-20 fold, from 25 to 400-500 mean fluorescence intensity. Aminoethyl-isothiourea (AE-ITU), a relatively selective inhibitor of the inducible nitric oxide synthase (iNOS) and a ROS scavenger, reduced the cytokine production by 70-100%, and intracellular leukocyte ROS levels by 50-70% (all P < 0.05). The non-selective NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) did not affect intracellular ROS levels, but it caused a moderate selective inhibition of IL-8 production. Leukocyte NO production (measured up to 36 h) was not enhanced by LTA, peptidoglycan, inactivated streptococci, or cytokine combinations. The mechanisms for the anti-inflammatory effects of AE-ITU may be through a reduction of intracellular ROS levels, or through a direct effect on signal transduction, whereas NO modulation is an unlikely mechanism.
Saetre
T
T
Research Forum, Ullevaal University Hospital, Oslo, Norway.
Kähler
H
H
Foster
S J
SJ
Lyberg
T
T
D002470:Cell Survival / Q000187:drug effects; D002473:Cell Wall / Q000276:immunology; D016207:Cytokines / Q000097:blood*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D066298:In Vitro Techniques; D007249:Inflammation; D007375:Interleukin-1 / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D016209:Interleukin-8 / Q000097:blood; D007962:Leukocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D008070:Lipopolysaccharides / Q000494:pharmacology; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009566:Nitrates / Q000097:blood; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052247:Nitric Oxide Synthase Type II; D009573:Nitrites / Q000097:blood; D010457:Peptidoglycan / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013297:Streptococcus pyogenes / Q000276:immunology*; D013682:Teichoic Acids / Q000494:pharmacology; D013890:Thiourea / Q000031:analogs & derivatives* / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
D016207:Cytokines; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D015850:Interleukin-6; D016209:Interleukin-8; D008070:Lipopolysaccharides; D009566:Nitrates; D009573:Nitrites; D010457:Peptidoglycan; D017382:Reactive Oxygen Species; D013682:Teichoic Acids; D014409:Tumor Necrosis Factor-alpha; C413842:aminoethyl-isothiourea; C009900:lipoteichoic acid; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; D013890:Thiourea; D019331:NG-Nitroarginine Methyl Ester