The Modulation Of Prostaglandins On Cytokines Outputs And Uterine Activation Proteins Expressions In Pregnant Myometrial Cells

Numerous physiological processes, like implantation, pregnancy maintaince and thetrigger of parturtiton, have close relationship with maternal immune system. Evidenceindicated that the establishment of inflammatory environment in intrauterine organscontributes to the initiation of parturition. The cytokines and chemokines activate themyometrium contractile ability changes via modulating contraction-related fators, andfurther more initate the parturition of labor. However there is no definite conclusion aboutthe regulation mechanism of inflammation factors during pregnancy and parturition.Considering as the most powerful contractile agonist of myometrium, PGs was reported todelay the stimulatory effect in clinical application as the drug induced labor. Thus thisfinding indicated that the regulatory mechanism of PGs on myometrium contractility mightgo through the uterus activation process in the early stage of parturition initiation and latersitmulates the regular contration in uterus. Reports demonstrated that the level of PGsdetected in amion fluid before parturition arised significantly which possibly contribute tothe uterine activation process during the early parturition. Without clarified explainationabout the hypothesis, we studied whether PGF2α and PGE2modulate the inflammation-related factors expression during normal pregnancy based on the cultured myometrialsmooth muscle cells.The contractility of uterus is influenced by changes of hormones level, expression ofcontractile proteins and other factors. The alteration of contractile protein family onexpression and function represents the contract ability of uterus. PGs have been discoveredinvolved in the regulation of some contractile proteins. However more studies are requiredfor the possible activated signal pathway mechanism triggered by PGF2α and PGE2inmyometrial cells. Here in our study, PTGS-2, CX43, OTR and PTGFR are taken as fourproxies for the uterine activation protein family (UAPs).In the third part, the role of transcriptional factor，Zinc E box binding homeobox,(ZEB) was taken into consideration that particicpated in the effect of PGs on uterineactivation process. Evidences indicated that ZEBs could directly bind to the promoters ofOTR and CX43and futher regulated their protein abundance. Therefore, we focused onwhether ZEBs medicatd partially the regulation of PGs on uterine activation proteinsexpression. Main results:1. Regulation of inflammatory cytokines expression mediated by prostaglandinsvia different receptors1) In the uterine activation process, PGF2α stimulated the outputs of pro-inflammatory cytokines, such as IL-6, IL-1β, the outputs of chemokines, like IL-8, MCP-1,and growth factor VEGF output, while decreased the output of cytokine TNFα.2) PGF2α receptor, PTGFR, trigger the intracellular multiple signal pathways toregulate the outputs of cytokines and chemokines. The outputs of IL-6，IL-1β, IL-8,MCP-1，VEGF and TNFα were modulated by PLC-β-PKC pathway. While the activationof Calcineurin-NFAT pathway involved in the regulation on MCP-1and TNFα outputs.The output of MCP-1was also mediated by P38-STATs pathway, while the PI3K activationparticipated in the regulation of MCP-1and VEGF outputs.3) PGE2via EP1/3up-regulated the outputs of IL-6, VEGF, TNFα, while decreasedIL-1β output. EP2agonist stimulated the outputs of IL-6, IL-8, IL-1β, and VEGF dose-dependently. But there exist the dual effect of EP2mediating the output of TNFα, i.e itshowed the stimulatory effect at the low concentration while decreased TNFα output at thehigh concenctration. And EP4agonist mainly down-regulated VEGF output and increasedIL-1β and TNFα outputs. Compared withhere is no significant effect on chemokine MCP-1output by PGE2.2. Regulation of uterine activation proteins expression mediated byprostaglandins via different receptors1) PGF2α via its Gq protein-coupled receptor PTGFR, activated intracellular PLCβ-PKC pathway and other signal factors to up-regulate the expression of uterine activationproteins, such as CX43, PTGS-2, OTR. Meanwhile PGF2α showed the negative feedbackmodulation on its own receptor expression.2) The contractile receptors EP1/3of PGE2mediated the stimulatory effect on UAPsexpression. While the relaxant receptor EP2and EP4mainly reduced the sensitivity ofmyometrial cells on oxytocin and PGs by down-regulating their receptor expression.Therefore PGE2achieved the subtle regulation on the uterine activation proteinsabundance by the balanced coordination among receptors.3. Regulation of transcript factor--ZEBs expression mediated by prostaglandinsvia different receptors1) PGF2α downregulated ZEB1and ZEB2protein abundances in pregnant myomtrial cells.2) PGE2mainly decreased ZEB1expression while ZEB2abundance remained at thesimilar level. However the contractile receptor EP1/3specific agonist increased ZEBsexpression while EP2and EP4agonists downregulated their abundances.ConclusionIn concluation, our study demonstrated that the arising level of PGF2α and PGE2inamnion fluid of pregnant women, took act on myometrium via autocrine or paracrine mean.On one hand, PGs contributed the micro inflammatory environment in intrauterine organsby promoting inflammation-related cytokines and chemokines expression. Meanwhile theupregulated VEGF level may contribute to the permeability of myometrial cells allowingmigration of leukocytes to uterus. On the other hand, the up-regulation of uterus contractileproteins can activate myometrium and prepare for the parturition.