Electronegative LDL from normolipemic subjects induces IL-8 and monocyte chemotactic protein secretion by human endothelial cells.
The presence in plasma of an electronegative LDL subfraction [LDL(-)] cytotoxic for endothelial cells (ECs) has been reported. We studied the effect of LDL(-) on the release by ECs of molecules implicated in leukocyte recruitment [interleukin-8 (IL-8) and monocyte chemotactic protein-1 (MCP-1)] and in the plasminogen activator inhibitor-1 (PAI-1). LDL(-), isolated by anion-exchange chromatography, differed from nonelectronegative LDL [LDL(+)] in its higher triglyceride, nonesterified fatty acid, apoprotein E and apoprotein C-III, and sialic acid contents. No evidence of extensive oxidation was found in LDL(-); its antioxidant and thiobarbituric acid-reactive substances contents were similar to those of LDL(+). However, conjugated dienes were increased in LDL(-), which suggests that mild oxidation might affect these particles. LDL(-) increased, in a concentration-dependent manner, the release of IL-8 and MCP-1 by ECs and was a stronger inductor of both chemokines than oxidized LDL (oxLDL) or LDL(+). PAI-1 release increased slightly in ECs incubated with both LDL(-) and oxLDL but not with LDL(+). However, no cytotoxic effects of LDL(-) were observed on ECs. Actinomycin D inhibited the release of IL-8 and MCP-1 induced by LDL(-) and oxLDL by up to 80%, indicating that their production is mediated by protein synthesis. Incubation of ECs with N:-acetyl cysteine inhibited production of IL-8 and MCP-1 induced by LDL(-) and oxLDL by >50%. The free radical scavenger butylated hydroxytoluene slightly inhibited the effect of oxLDL but did not modify the effect of LDL(-). An antagonist (BN-50730) of the platelet-activating factor receptor inhibited production of both chemokines by LDL(-) and oxLDL in a concentration-dependent manner. Our results indicate that LDL(-) shows proinflammatory activity on ECs and may contribute to early atherosclerotic events.
De Castellarnau
C
C
Institut de Recerca, Servei de Bioquímica, Hospital de la Santa Creui Sant Pau, Barcelona, Spain. ccastellarnauc@medynet.com
Sánchez-Quesada
J L
JL
Benítez
S
S
Rosa
R
R
Caveda
L
L
Vila
L
L
Ordóñez-Llanos
J
J
D000111:Acetylcysteine / Q000494:pharmacology; D000328:Adult; D000975:Antioxidants; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000096:biosynthesis*; D002852:Chromatography, Ion Exchange; D003609:Dactinomycin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D005260:Female; D016166:Free Radical Scavengers / Q000494:pharmacology; D006801:Humans; D016209:Interleukin-8 / Q000096:biosynthesis*; D008077:Lipoproteins, LDL / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000096:biosynthesis; D013858:Thiobarbiturates; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000975:Antioxidants; D018932:Chemokine CCL2; D016166:Free Radical Scavengers; D016209:Interleukin-8; D008077:Lipoproteins, LDL; D017395:Plasminogen Activator Inhibitor 1; D013858:Thiobarbiturates; D014409:Tumor Necrosis Factor-alpha; C099252:oxidized low density lipoprotein; D003609:Dactinomycin; C029684:thiobarbituric acid; D000111:Acetylcysteine