Inhibition of the mitogen activated protein kinase, p38 alpha, prevents proinflammatory cytokine induction by human adherent mononuclear leukocytes in response to lipid loading.
Macrophage infiltration, inflammatory processes and oxidatively modified low density lipoprotein (LDL) are known contributing factors in the formation of the atherosclerotic plaque. To determine whether a direct link might exist between these factors, we examined the effect of oxidized LDL upon proinflammatory cytokine production in adherent human peripheral blood mononuclear leukocytes. Oxidized LDL, as well as a combination of cholesterol and 25-hydroxycholesterol, induced tumor necrosis factor-alpha (TNFalpha) and interleukin-1 beta (IL-1 beta) mRNA as measured by quantitative real time PCR, by a maximum of two- to fourfold following a 24-h incubation. Analysis of cell culture supernatants revealed a concomitant stimulation of TNFalpha and IL-1 beta secreted protein as determined by ELISA. Treatment of human peripheral blood mononuclear leukocytes with oxidized LDL or the combination of cholesterol and 25-hydroxycholesterol caused activation of p38 alpha as determined by the ability of immunoprecipitated p38 to phosphorylate an ATF-2 fusion protein, a surrogate substrate of p38 alpha. VK-19911 (Pyridine, 4-[4-(4-fluorophenyl)-1-(4-piperidinyl)-1H-imidazol-5-yl]-dihydrochloride), a specific inhibitor of p38 alpha, prevented the induction of TNFalpha and IL-1 beta by oxidized LDL in a dose-dependent manner. Activated p38 alpha is known to be involved in the stabilization of cyclooxygenase-2 mRNA in response to stimuli such as lipopolysaccharide; however, in the setting of oxidized LDL-induced p38 alpha activation, COX-2 mRNA levels were not affected. Taken together, the data imply a potential role for p38 alpha activation in lipid-associated inflammatory processes.
Feng
Y
Y
Scios Inc., 820 West Maude Ave., Sunnyvale, CA 94086, USA.
Schreiner
G F
GF
Chakravarty
S
S
Liu
D Y
DY
Joly
A H
AH
D051698:Activating Transcription Factor 2; D002448:Cell Adhesion; D002784:Cholesterol / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D051546:Cyclooxygenase 2; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D006888:Hydroxycholesterols / Q000494:pharmacology; D007093:Imidazoles / Q000494:pharmacology; D007375:Interleukin-1 / Q000096:biosynthesis*; D007527:Isoenzymes; D007963:Leukocytes, Mononuclear / Q000378:metabolism*; D008055:Lipids / Q000494:pharmacology*; D008077:Lipoproteins, LDL / Q000494:pharmacology; D008565:Membrane Proteins; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010084:Oxidation-Reduction; D010766:Phosphorylation; D011451:Prostaglandin-Endoperoxide Synthases; D011725:Pyridines / Q000494:pharmacology; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis*; D048051:p38 Mitogen-Activated Protein Kinases
C107383:4-(4-fluorophenyl)-1-(4-piperidinyl)-5-(4-pyridyl)-imidazole; C497105:ATF2 protein, human; D051698:Activating Transcription Factor 2; D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D006888:Hydroxycholesterols; D007093:Imidazoles; D007375:Interleukin-1; D007527:Isoenzymes; D008055:Lipids; D008077:Lipoproteins, LDL; D008565:Membrane Proteins; D011725:Pyridines; D012333:RNA, Messenger; D014157:Transcription Factors; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; C007997:25-hydroxycholesterol; D002784:Cholesterol; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011451:Prostaglandin-Endoperoxide Synthases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases