抄録
Sterodid hormones raise the serum cholesterol level and promote the process of atherosclerosis. The progression of atherosclerosis was suppressed when steroid hormones were administrated to cholesterol-fed rabbits.
Platelet-derived growth factor (PDGF) is a smooth muscle cell proliferating factor and it also participates in wound healing due to the proliferation of fibroblasts. It is also known that in patients treated with steroid hormones, the wound healing is delayed and the number of macrophages in wounds is reduced.
From these findings, the following hypotheses are proposed:
(1) Sterod hormones suppress the differentiation of macrophages.
(2) Steroid hormones inhibit the expression of PDGF in macrophages.
To confirm these hypotheses, we examined the effect of dexamethasone (DEX) on the differentiation and the PDGF expression in a monocytic leukemia cell line, THP-1. DEX inhibited the cell adhesion and NBT reducing activity of THP-1 cells treated with phorbol myristate acetate (PMA). EDX exerted a morphological effect on PMA-stimulated THP-1 cells by suppresing the development of the characteristic spreading shapes in differentiated macrophages. The levels of the PDGF-A and -B mRNA were determined by reverse transcription (RT)-PCR methods. DEX inhibited the expression of PDGF-A during PMA stimulation in a dose dependent manner. PDGF-A expressions were suppressed within 6 hrs to 24 hrs following administration of DEX. Little PDGF-B mRNA was detected in PMA treated THP-1 cells and the effect of DEX could not be detected, suggested that DEX may partially inhibit the differentiation and the PDGF-A expression in monocytes and prevent the progression of atherosclerosis.
