The effects of phosphoinositide/calcium- or cyclic AMP-mediated signal transduction pathway inhibitors on the activation of rat peritoneal macrophages by acetylated low-density lipoprotein.
BACKGROUND
Macrophages that uptake modified lipoproteins are activated and may initially behave as endotoxin-stimulated macrophages. This study was undertaken in order to determine whether signal transduction pathways controlling endotoxin-mediated activation may also influence the lipoprotein-mediated activation of macrophages.


METHODS
Rat peritoneal macrophages were incubated for 16 hours with acetylated low-density lipoprotein and certain agents that modify the phosphoinositide/calcium- and cyclic AMP-mediated pathways, such as 2-[4-morpholinyl]-8-phenyl-1[4H]-benzopyran-4-one (LY-294002), autocamtide 2-related inhibitory peptide (AIP), N-(2-[p-bromocinnamylamino]-ethyl)-5-isoquinolinesulfonamide hydrochloride (H-89) and actinomycin D. The production of nitric oxide and the intracellular and extracellular activities of acid phosphatase were assayed.


RESULTS
Macrophages incubated with acetylated low-density lipoprotein showed an increased production of nitric oxide and intracellular acid phosphatase activity as compared to their controls. LY-294002, AIP and H-89 caused a significant decrease in nitric oxide production and intracellular acid phosphatase activity. Actinomycin D had similar effects. AIP and actinomycin also significantly increased extracellular acid phosphatase activity.


CONCLUSIONS
The activation of peritoneal macrophages by acetylated low-density lipoprotein was similar to the activation by endotoxin, as expressed by the nitric oxide production and acid phosphatase intracellular activity; agents controlling the phosphoinositide/calcium- and cyclic AMP-mediated pathways in endotoxin-activated macrophages also influence the acetylated low-density lipoprotein-activated macrophages.
Kondomerkos
Dimitrios J
DJ
Department of Anatomy, Histology and Embryology, Medical School, University of Ioannina, 45110 Ioannina, Greece. kondomerkos@hotmail.com
Kalamidas
Stefanos A
SA
Michalis
Lampros K
LK
Kanavaros
Panagiotis
P
D000135:Acid Phosphatase / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000494:pharmacology; D053453:Caspase 9; D020169:Caspases / Q000494:pharmacology; D002478:Cells, Cultured; D002867:Chromones / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D003609:Dactinomycin / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D007546:Isoquinolines / Q000494:pharmacology; D008077:Lipoproteins, LDL / Q000494:pharmacology*; D008262:Macrophage Activation / Q000187:drug effects*; D017737:Macrophages, Peritoneal / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009025:Morpholines / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013047:Specific Pathogen-Free Organisms; D013449:Sulfonamides / Q000494:pharmacology
D000135:Acid Phosphatase; D002352:Carrier Proteins; D053453:Caspase 9; D020169:Caspases; D002867:Chromones; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D003609:Dactinomycin; D004791:Enzyme Inhibitors; D007546:Isoquinolines; D008077:Lipoproteins, LDL; D009025:Morpholines; D009569:Nitric Oxide; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D013449:Sulfonamides; C032629:acetyl-LDL; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C506435:Casp9 protein, rat; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide