Production of angiogenic activity by human monocytes requires an L-arginine/nitric oxide-synthase-dependent effector mechanism.
Human monocytes (M phi) require stimulation with substances such as bacterial endotoxin [LPS (lipopolysaccharide)] to produce angiogenic activity. In this study, we report that stimulation of M phi with LPS (5 micrograms/ml) in the absence of L-arginine greatly reduced their production of angiogenic activity, as assessed in vivo in rat corneas and in vitro by chemotaxis of human umbilical vein endothelial cells (HU-VECs). D-Arginine did not substitute for L-arginine in the production of angiogenic activity. The nitric oxide synthase (NO synthase, EC 1.14-13.39) inhibitors NG-monomethyl-L-arginine (L-NMMA) and NG-nitro-L-arginine methyl ester (L-NAME) both inhibited the production of angiogenic activity by LPS-stimulated M phi in the presence of L-arginine, suggesting the involvement of this enzyme in the pathway that generates angiogenic activity. Neither of these substances directly inhibited the M phi-derived angiogenic activity. LPS-induced production of the cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin 8 (IL-8) was not significantly reduced when M phi were incubated in the absence of L-arginine. Similarly, L-NMMA and L-NAME did not significantly reduce the LPS-induced production of these cytokines by M phi in the presence of L-arginine. These results suggest that the LPS-stimulation-dependent generation of angiogenic activity by M phi requires an L-arginine-dependent NO-synthase effector mechanism that may be independent of the generation of TNF-alpha and IL-8.
Leibovich
S J
SJ
Department of Basic Sciences, Northwestern University Dental School, Chicago, IL 60611.
Polverini
P J
PJ
Fong
T W
TW
Harlow
L A
LA
Koch
A E
AE
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors / Q000097:blood / Q000378:metabolism*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects; D003315:Cornea / Q000502:physiology*; D017077:Culture Media, Conditioned; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004731:Endotoxins / Q000494:pharmacology; D006801:Humans; D016209:Interleukin-8 / Q000032:analysis / Q000096:biosynthesis; D008070:Lipopolysaccharides / Q000494:pharmacology; D009000:Monocytes / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester; D009389:Neovascularization, Pathologic; D019001:Nitric Oxide Synthase; D051381:Rats; D013237:Stereoisomerism; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis / Q000096:biosynthesis; D014471:Umbilical Veins; D019323:omega-N-Methylarginine
D017077:Culture Media, Conditioned; D004731:Endotoxins; D016209:Interleukin-8; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D019323:omega-N-Methylarginine; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester