Interleukin-10 inhibition of nitric oxide biosynthesis involves suppression of CAT-2 transcription.
Interleukin-10 (IL-10) has been shown to attenuate lipopolysaccharide (LPS) stimulation of inducible nitric oxide synthase (iNOS) in various cell types. Guanosine triphosphate cyclohydrolase I (GTPCH) and type-2 cationic amino acid transporter (CAT-2) are enzymes that regulate iNOS activity. We therefore sought to assess the effects of IL-10 on the expression of these regulatory enzymes in LPS-stimulated macrophages that are known to express iNOS. Five minutes after adding LPS to these macrophage cultures, various doses of recombinant human IL-10 were also added. The samples were harvested for analysis 18 h after exposure to both LPS and IL-10. In LPS-stimulated macrophages, IL-10 attenuated the upregulation of nitric oxide and iNOS protein but not iNOS mRNA. IL-10 also attenuated the LPS-induced upregulation of CAT-2 mRNA. However, IL-10 and LPS had no effect on GTPCH mRNA expression. We therefore conclude that IL-10 inhibits nitric oxide formation in LPS-stimulated macrophages partly by decreasing iNOS protein expression. Moreover, our data suggests that transcriptional control of CAT-2 plays a role in IL-10 mediated influences upon nitric oxide biosynthesis.
Huang
Chun-Jen
CJ
Department of Anesthesiology, Mackay Memorial Hospital
Stevens
Bruce R
BR
Nielsen
R Barton
RB
Slovin
Paul N
PN
Fang
Xiaoying
X
Nelson
David R
DR
Skimming
Jeffrey W
JW
D000818:Animals; D027202:Cationic Amino Acid Transporter 2 / Q000235:genetics* / Q000378:metabolism / Q000502:physiology; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D006136:GTP Cyclohydrolase / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016753:Interleukin-10 / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000494:pharmacology; D008264:Macrophages / Q000378:metabolism; D051379:Mice; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000187:drug effects / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D012333:RNA, Messenger / Q000378:metabolism; D014158:Transcription, Genetic / Q000187:drug effects*
D027202:Cationic Amino Acid Transporter 2; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D016753:Interleukin-10; D009569:Nitric Oxide; C496319:NOS2 protein, human; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse; D006136:GTP Cyclohydrolase