Table1_PGF2α induces a pro-labour phenotypical switch in human myometrial cells that can be inhibited with PGF2α receptor antagonists.DOCX

Preterm birth is the leading cause of infant morbidity and mortality. There has been an interest in developing prostaglandin F2α (PGF2α) antagonists as a new treatment for preterm birth, although much of the rationale for their use is based on studies in rodents where PGF2α initiates labour by regressing the corpus luteum and reducing systemic progesterone concentrations. How PGF2α antagonism would act in humans who do not have a fall in systemic progesterone remains unclear. One possibility, in addition to an acute stimulation of contractions, is a direct alteration of the myometrial smooth muscle cell state towards a pro-labour phenotype. In this study, we developed an immortalised myometrial cell line, MYLA, derived from myometrial tissue obtained from a pregnant, non-labouring patient, as well as a novel class of PGF2α receptor (FP) antagonist. We verified the functionality of the cell line by stimulation with PGF2α, resulting in Gαq-specific coupling and Ca2+ release, which were inhibited by FP antagonism. Compared to four published FP receptor antagonists, the novel FP antagonist N582707 was the most potent compound [Fmax 7.67 ± 0.63 (IC50 21.26 nM), AUC 7.30 ± 0.32 (IC50 50.43 nM), and frequency of Ca2+ oscillations 7.66 ± 0.41 (IC50 22.15 nM)]. RNA-sequencing of the MYLA cell line at 1, 3, 6, 12, 24, and 48 h post PGF2α treatment revealed a transforming phenotype from a fibroblastic to smooth muscle mRNA profile. PGF2α treatment increased the expression of MYLK, CALD1, and CNN1 as well as the pro-labour genes OXTR, IL6, and IL11, which were inhibited by FP antagonism. Concomitant with the inhibition of a smooth muscle, pro-labour transition, FP antagonism increased the expression of the fibroblast marker genes DCN, FBLN1, and PDGFRA. Our findings suggest that in addition to the well-described acute contractile effect, PGF2α transforms myometrial smooth muscle cells from a myofibroblast to a smooth muscle, pro-labour–like state and that the novel compound N582707 has the potential for prophylactic use in preterm labour management beyond its use as an acute tocolytic drug.

早产是导致婴儿发病与死亡的首要原因。学界长期致力于研发前列腺素F2α（Prostaglandin F2α）拮抗剂作为早产治疗的新方案，不过此类药物的应用依据大多源于啮齿类动物研究：在这些研究中，PGF2α通过使黄体退化、降低全身孕酮浓度触发分娩。而对于全身孕酮浓度未出现下降的人类群体，PGF2α拮抗剂的作用机制仍未明确。除了可急性刺激宫缩外，一种潜在的作用途径是直接改变子宫平滑肌细胞的状态，使其向促分娩表型转化。
本研究中，我们从一名未进入产程的妊娠患者的子宫肌层组织中构建了永生化子宫平滑肌细胞系MYLA，同时研发了一类新型前列腺素F2α受体（FP）拮抗剂。我们通过PGF2α刺激验证了该细胞系的功能：刺激后可引发Gαq蛋白特异性偶联与钙离子释放，且此类效应可被FP拮抗剂抑制。相较于已发表的4种FP受体拮抗剂，新型FP拮抗剂N582707的活性最强[最大效应值Fmax为7.67±0.63，半数抑制浓度IC50为21.26 nM；曲线下面积AUC为7.30±0.32，IC50为50.43 nM；钙离子振荡频率为7.66±0.41，IC50为22.15 nM]。
对经PGF2α处理后1、3、6、12、24及48小时的MYLA细胞系进行RNA测序，结果显示其mRNA表达谱从成纤维细胞样向平滑肌细胞样表型转化。PGF2α处理可上调MYLK、CALD1、CNN1以及促分娩基因OXTR、IL6、IL11的表达，此类效应可被FP拮抗剂阻断。在抑制平滑肌细胞向促分娩表型转化的同时，FP拮抗剂可上调成纤维细胞标志物基因DCN、FBLN1及PDGFRA的表达。
本研究结果表明，除了已被广泛证实的急性宫缩效应外，PGF2α还可将子宫平滑肌细胞从肌成纤维细胞状态转化为平滑肌样促分娩表型；同时，新型化合物N582707除可作为急性宫缩抑制剂外，还有望用于早产的预防性管理。