内源性硫化氢抑制子宫激活的机制及其意义

。Preterm birth occurs in 8-10% of all pregnancies and current therapeutic approaches are unsuccessful. This failure is largely due to our ignorance of the fundamental mechanisms that control the length of human pregnancy and the process of human labour. Uterus is a dynamic organ that undergoes distinct molecular changes during pregnancy. At the term, uterus activated by increasing expression of uterine activation proteins (UAPs, e.g. the gap junction protein, connexin43, receptors for agonists and ion channels) that control myometrial excitability and increased production of uterine agonists. There are a number of endogenous factors which modulate uterus activation. Hydrogen sulfide (H2S) is endogenously produced from L-cysteins by cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE). We have found that CBS and CSE expressed in human uterus by IHC and western blotting. The results showed that CSE and CBS in uterus in labor were decreased compared with term not in labor, and the expression of CSE and CBS was negatively correlated with the expression of UAPs. Moreover, H2S inhibited the expression of UAPs in cultured myometrial cells. H2S postponed against LPS-induced preterm delivery. It suggested that H2S inhibited uterus activation. As we known, uterus activation for labour would be induced by inflammation. And we found that H2S inhibited the production of inflammatory cytokines in cultured myometrial cells. On the basis of preliminary experiment, we are going to explore the mechanism of inhibition of uterus activation by endogenous H2S. We will investigate whether the effects of H2S on the regulation of UAPs in uterus were through inhibiting cytokine production. We will employ a set of molecular biological techniques to investigate the mechanism of regulation of inflammation by H2S in myometrium. The study will help to furtherly clarity the mechanism of human parturition.

早产发病率高达9-11%，但早产的发生率并未得到有效的控制，原因在于人类妊娠末期子宫激活的机理尚未明晰，发现新的抑制子宫激活的内源性因子为研制有效且安全的治疗早产的新药提供新思路。硫化氢（H2S）是一种新型气体信号分子，我们前期在整体动物和离体细胞实验的研究表明，内源性H2S能够抑制子宫激活。人类的分娩是一个炎症过程，分娩前夕炎性因子参与激活子宫，我们前期实验观察到H2S能够抑制子宫肌炎性因子的生成。在此基础上，本项目系统深入地研究妊娠末期H2S抑制子宫激活的机制，明确H2S是否通过抗炎进而抑制子宫激活，并对其分子机制进行深入研究，观察H2S通过激活KATP通道，p38 MAPK，PI3K/AKT,NF-κB等信号通路中的哪些信号通路发挥抗炎作用，并进一步明确H2S作用的靶分子。本研究结果将有助于阐明妊娠末期子宫激活的机制，为研制有效且安全的治疗早产的新药提供新的思路。

硫化氢是继NO和CO之后发现的第三种具有生物活性的气体信号分子，研究发现H2S可舒张多种平滑肌，但是H2S是否可调节子宫平滑肌收缩性及其可能机制目前尚未见研究报道。为观察H2S对不同状态子宫肌的作用是否不同，我们将子宫肌分为足月未临产(TNL)和足月临产（TL）子宫肌进行研究。结果发现给予H2S供体NaHS及前体L-cysteine都能抑制离体子宫肌组织的收缩，而且L-cysteine对TNL组收缩的抑制作用明显强于TL组，结果还表明TNL组CSE和CBS表达以及H2S生成速率明显高于TL组，提示CSE和CBS在临产前后表达的变化可能在子宫肌由静息态转化为收缩态中发挥一定的作用。.有研究表明H2S可激活KATP通道，我们的研究表明给予KATP通道阻断剂预处理可阻断NaHS和L-cysteine舒张子宫肌的作用，提示H2S是通过激活KATP通道发挥舒张离体子宫肌的作用。由此我们进一步研究KATP通道蛋白在人类子宫肌上的表达，发现TNL组上段和下段的KATP通道各组成亚基蛋白表达量都高于TL组；用KATP通道激动剂diazoxide处理离体子宫肌组织，能抑制其自发性收缩，且diazoxide对TNL组的抑制效应明显强于TL组，提示临产前后KATP通道蛋白表达变化可能也与子宫由静息态向收缩态的转变有关。