Macrophage activation induces formation of the anti-inflammatory lipid cholesteryl-nitrolinoleate.
Nitroalkene derivatives of fatty acids act as adaptive, anti-inflammatory signalling mediators, based on their high-affinity PPARgamma (peroxisome-proliferator-activated receptor gamma) ligand activity and electrophilic reactivity with proteins, including transcription factors. Although free or esterified lipid nitroalkene derivatives have been detected in human plasma and urine, their generation by inflammatory stimuli has not been reported. In the present study, we show increased nitration of cholesteryl-linoleate by activated murine J774.1 macrophages, yielding the mononitrated nitroalkene CLNO2 (cholesteryl-nitrolinoleate). CLNO2 levels were found to increase approximately 20-fold 24 h after macrophage activation with Escherichia coli lipopolysaccharide plus interferon-gamma; this response was concurrent with an increase in the expression of NOS2 (inducible nitric oxide synthase) and was inhibited by the (*)NO (nitric oxide) inhibitor L-NAME (N(G)-nitro-L-arginine methyl ester). Macrophage (J774.1 and bone-marrow-derived cells) inflammatory responses were suppressed when activated in the presence of CLNO2 or LNO2 (nitrolinoleate). This included: (i) inhibition of NOS2 expression and cytokine secretion through PPARgamma and *NO-independent mechanisms; (ii) induction of haem oxygenase-1 expression; and (iii) inhibition of NF-kappaB (nuclear factor kappaB) activation. Overall, these results suggest that lipid nitration occurs as part of the response of macrophages to inflammatory stimuli involving NOS2 induction and that these by-products of nitro-oxidative reactions may act as novel adaptive down-regulators of inflammatory responses.
Ferreira
Ana M
AM
Department of Immunology, Faculty of Sciences, University of the Republic, Montevideo 11400, Uruguay.
Ferrari
Mariana I
MI
Trostchansky
Andrés
A
Batthyany
Carlos
C
Souza
José M
JM
Alvarez
María N
MN
López
Gloria V
GV
Baker
Paul R S
PR
Schopfer
Francisco J
FJ
O'Donnell
Valerie
V
Freeman
Bruce A
BA
Rubbo
Homero
H
D000818:Animals; D018955:CD36 Antigens / Q000378:metabolism; D002460:Cell Line; D002788:Cholesterol Esters / Q000138:chemical synthesis / Q000378:metabolism* / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D051547:Heme Oxygenase-1 / Q000378:metabolism; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism; D007371:Interferon-gamma / Q000494:pharmacology; D053583:Interleukin-1beta / Q000378:metabolism; D008070:Lipopolysaccharides / Q000494:pharmacology; D008262:Macrophage Activation; D008264:Macrophages / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052247:Nitric Oxide Synthase Type II / Q000378:metabolism; D048069:Tumor Necrosis Factors / Q000378:metabolism
D018955:CD36 Antigens; D002788:Cholesterol Esters; D053583:Interleukin-1beta; D008070:Lipopolysaccharides; D048069:Tumor Necrosis Factors; C487539:cholesteryl nitrolinoleate; C021976:cholesteryl linoleate; D007371:Interferon-gamma; D052247:Nitric Oxide Synthase Type II; D051547:Heme Oxygenase-1; D019331:NG-Nitroarginine Methyl Ester