Pressure and endothelial coculture upregulate myocytic Fas-FasL pathway and induce apoptosis by way of direct and paracrine mechanisms.
BACKGROUND
Pressurized endothelial cell (EC)-smooth muscle cell (SMCs) coculture significantly increases the apoptosis of SMCs. Our current hypothesis was that in EC-SMC coculture, pressure upregulates SMC apoptosis SMCs through EC-derived paracrine factors and that SMC apoptosis is induced through Fas-Fas ligand (FasL) activation.


METHODS
Conditioned media (CM) from ECs and SMCs exposed to ambient or high pressure was transferred to recipient SMCs. SMCs were stained with terminal deoxynucleotide transferase-mediated deoxy uridine triphosphate nick-end labeling. Fas and FasL expression was assessed in SMC grown in monoculture, coculture with EC, pressurized monoculture, and pressurized coculture with EC.


RESULTS
CM from pressurized ECs caused a 30% increase in SMC apoptosis compared with CM from control ECs (P < .05). Pressure increased Fas and FasL expression in monocultured and cocultured SMCs (1.6-fold and 2.3-fold for Fas [P < .05] and 1.65-fold and 1.7-fold for FasL [P < or = .05]). Coculture had synergistic effect on Fas expression and no effect on FasL expression.


CONCLUSIONS
Pressure plays significant role in EC-SMC interaction, SMC apoptosis, and vascular remodeling.
Vouyouka
Agelikie G
AG
Department of Surgery, John D. Dingell Veterans Administration Medical Center, 4646 John R St., Detroit MI 48201-1932, USA. angela.vouyouka@med.va.gov
Lin
Lifeng
L
Basson
Marc D
MD
D000818:Animals; D001011:Aorta / Q000166:cytology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D017077:Culture Media, Conditioned; D004247:DNA / Q000235:genetics*; D004730:Endothelium, Vascular / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D053222:Fas Ligand Protein; D020287:In Situ Nick-End Labeling; D008562:Membrane Glycoproteins / Q000096:biosynthesis / Q000235:genetics*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D011312:Pressure; D051381:Rats; D018124:Receptors, Tumor Necrosis Factor / Q000096:biosynthesis / Q000235:genetics*; D015854:Up-Regulation / Q000502:physiology*; D019014:fas Receptor
D017077:Culture Media, Conditioned; D053222:Fas Ligand Protein; C491898:Fas protein, rat; C505662:Faslg protein, rat; D008562:Membrane Glycoproteins; D018124:Receptors, Tumor Necrosis Factor; D019014:fas Receptor; D004247:DNA