Expression and control mechanisms of prostaglandin H2 synthase in endometrium and decidua

为了阐明两种环氧合酶(COX)在蜕膜PG产生中的作用，采用蜕膜基质细胞体外培养系统进行了研究，用特异性抗体进行免疫细胞化学研究，发现在治疗流产6~8周时获得的蜕膜基质细胞中存在COX-2和COX-1。与COX-1明显组成性表达不同，COX-2是在无血清的情况下加入白介素1(IL-1)诱导的。COX-2的基础染色水平明显低于COX-1。加入地塞米松的孕酮在酶染色和PGE2产生方面均减弱了COX-2的诱导，提示孕酮可能参与了早孕蜕膜抑制前列腺素合成的机制。此外，COX-2的特异性抑制剂NS-398剂量依赖性地抑制IL-1刺激的蜕膜细胞PGE2的产生，并在10℃时完全阻断PG的产生。这些结果表明，在这种体外培养条件下，早期妊娠的外周基质细胞PG的产生完全依赖于COX-2途径，COX-1的活性可能受到不同机制的控制，如花生四烯酸的可获得性或先前报道的酶抑制蛋白。

In order to clarify the involvement of two types of cyclooxygenase (COX) in decidual PG production, subsequent study was undertaken by using in vitro decidual stromal cells culture system.Immunocytochemical study with specific antibody revealed the presence of COX-2 as well as COX-1 in decidual stromal cells obtained at the time of therapeutic abortion between 6 to 8 weeks. In contrast to COX-1 which was apparently expressed constitutively, COX-2 was induced by the addition of interleukin-1 (IL-1) in the absence of serum in culture medium. The basal staining level of COX-2 was significantly lower than that of COX-1. The addition of dexamethasone of progesterone attenuated the induction of COX-2 in terms of both enzyme staining and PGE2 production, which implied the possible involvement of progesterone in the inhibitory mechanism of prostaglandin synthesis by decidua in early pregnancy. In addition, a specific inhibitor of COX-2, NS-398, dose dependently inhibited the PGE2 production by decidual cells stimulated with IL-1 and completely blocked PG production at the dose of 10^<-6>M.These results suggest that PG production by dedidual stromal cells from early pregnancy wholely depend upon COX-2 pathway in this in vitro culture condition and it seems likely that COX-1 activity may be under control of different mechanism such as arachidonic acid availability or previously reported enzyme inhibitory protein.