[Adhesion between monocytes and vascular smooth muscle cells induced by integrin beta1-mediated platelet-derived growth factor].
OBJECTIVE
To investigate the effects of platelet-derived growth factor (PDGF)-BB on the vascular smooth muscle cell (VSMC)-monocyte interaction and the mechanism thereof.


METHODS
Rat aortic VSMC were pretreated with PDGF-BB of the concentrations of 0, 2.5, 5, 10, and 20 ng/ml for 8 hours and then co-incubated with human monocytes of the line THP-1 labeled with PKH26, a cellular membrane fluorescent marker, i.e., to be subjected to binding assay to observe the dose-effect relationship. Other VSMC were co-cultured with PDGF of the concentration of 10 ng/ml for 1, 2, 4, 12, and 24 hours respectively and then interacted with PKH26-abeled THP-1 cells so as to observe the time-response relationship. Monoclonal antibody against integrin beta1 was co-cultured with VSMC for 30 min, and then PKH26-labeled THP-1 cells were added to block the effect of PDGF. After the incubation of THP-1 cells and VSMC, the amount of bound cells was counted using fluorescent phase-contrast microscopy. The effect of PDGF on the expression of integrin beta1 was detected by Western blotting.


RESULTS
The amounts of THP-1 cells bound to VSMC pretreated with PDGF of the concentrations of 2.5, 5, 10, and 20 ng/ml respectively were 1.1, 2.1, 3.1, and 4.4 times that of the untreated cells. Incubated with 10 ng/ml PDGF for 0-18 h, the adhesion rate between the VSMC and THP-1 cells increased time-1dependently. After the blocking by the antibody against integrin beta1, the adhesion rate between the VSMC and THP-1 cells decreased from (25.4+/-11.4)% to (9.2+/-4.1)% (P<0.01). Western blotting showed that the level of integrin beta1 of the VSMC treated by 10 ng/ml PDGF increased since 4 h after the treatment, peaked 8 h later, and then decreased gradually.


CONCLUSIONS
PDGF-BB can induce the binding of monocytes to VSMC via the integrin-beta1 signaling pathway. The effect may therefore facilitate the progression of atherosclerosis by augmenting the VSMC-monocyte adhesive interaction.
Guo
Yan-hong
YH
Department of Cardiology, Peking University Third Hospital, Key Laboratory of the Ministry of Education on Molecular Cardiology, Beijing 100083, China.
Yu
Hai-yi
HY
Zu
Ling-yun
LY
Wang
Yan
Y
Gao
Wei
W
D000818:Animals; D001011:Aorta / Q000166:cytology; D000077214:Becaplermin; D015153:Blotting, Western; D002448:Cell Adhesion / Q000187:drug effects; D002460:Cell Line; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism*; D009000:Monocytes / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D032389:Myocytes, Smooth Muscle / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects
D019012:Integrin beta1; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin