Mouse macrophage paraoxonase 2 activity is increased whereas cellular paraoxonase 3 activity is decreased under oxidative stress.
OBJECTIVE
To determine whether paraoxonases (PONs) are expressed in macrophages and to analyze the oxidative stress effect on their expression and activities.


RESULTS
We demonstrated the presence (mRNA, protein, activity) of PON2 and PON3 but not PON1 in murine macrophages, whereas in human macrophages, only PON2 was expressed. Under oxidative stress as present in mouse peritoneal macrophages (MPMs) from apoE-deficient (E0) mice as well as in C57BL6 mice, MPMs that were incubated with buthionine sulfoximine, with angiotensin II, with 7-ketocholesterol, or with oxidized phosphatidylcholine, PON2 mRNA levels and lactonase activity toward dihydrocoumarin significantly increased (by 50% to 130%). In contrast, PON3 lactonase activity toward lovastatin was markedly reduced (by 29% to 57%) compared with control cells. The supplementation of E0 mice with dietary antioxidants (vitamin E, pomegranate juice) significantly increased macrophage PON3 activity (by 23% to 40%), suggesting that oxidative stress was the cause for the reduced macrophage PON3 activity. Incubation of purified PON2 or PON3 with E0 mice MPMs resulted in reduced cellular lipid peroxides content by 14% to 19% and inhibition of cell-mediated LDL oxidation by 32% to 39%.


CONCLUSIONS
Increased macrophage PON2 expression under oxidative stress could represent a selective cellular response to reduce oxidative burden, which may lead to attenuation of macrophage foam cell formation.
Rosenblat
Mira
M
The Lipid Research Laboratory, Technion Faculty of Medicine, The Rappaport Family Institute for Research in the Medical Sciences and Rambam Medical Center, Haifa, Israel.
Draganov
Dragomir
D
Watson
Catherine E
CE
Bisgaier
Charles L
CL
La Du
Bert N
BN
Aviram
Michael
M
D000818:Animals; D001057:Apolipoproteins E / Q000172:deficiency; D001161:Arteriosclerosis / Q000201:enzymology*; D043303:Aryldialkylphosphatase; D002478:Cells, Cultured; D008078:Cholesterol, LDL / Q000378:metabolism*; D004950:Esterases / Q000235:genetics / Q000378:metabolism*; D005487:Foam Cells / Q000378:metabolism; D008264:Macrophages / Q000201:enzymology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis
D001057:Apolipoproteins E; D008078:Cholesterol, LDL; D012333:RNA, Messenger; D004950:Esterases; D043303:Aryldialkylphosphatase; C468406:PON1 protein, human; C113656:PON3 protein, human