Human Endometrial Stromal Cell Differentiation is Stimulated by PPARβ/δ Activation: New Targets for Infertility?

Interleukin-1β induces and accelerates human endometrial stromal cell senescence and impairs decidualization via the c-Jun N-terminal kinase pathway

As the mean age of first-time mothers increases in the industrialized world, inquiries into causes of human reproductive senescence have followed. Rates of ovulatory dysfunction and oocyte aneuploidy parallel chronological age, but poor reproductive outcomes in women older than 35 years are also attributed to endometrial senescence. The current studies, using primary human endometrial stromal cell (ESC) cultures as an in vitro model for endometrial aging, characterize the proinflammatory cytokine, IL-1β-mediated and passage number-dependent effects on ESC phenotype. ESC senescence was accelerated by incubation with IL-1β, which was monitored by RNA sequencing, ELISA, immunocytochemistry and Western blotting. Senescence associated secreted phenotype (SASP) proteins, IL-1β, IL-6, IL-8, TNF-α, MMP3, CCL2, CCL5, and other senescence-associated biomarkers of DNA damage (p16, p21, HMGB1, phospho-γ-histone 2 A.X) were noted to increase directly in response to 0.1 nM IL-1β stimulation. Production of the corresponding SASP proteins increased further following extended cell passage. Using enzyme inhibitors and siRNA interference, these effects of IL-1β were found to be mediated via the c-Jun N-terminal kinase (JNK) signaling pathway. Hormone-induced ESC decidualization, classical morphological and biochemical endocrine responses to estradiol, progesterone and cAMP stimulation (prolactin, IGFBP-1, IL-11 and VEGF), were attenuated pari passu with prolonged ESC passaging. The kinetics of differentiation responses varied in a biomarker-specific manner, with IGFBP-1 and VEGF secretion showing the largest and smallest reductions, with respect to cell passage number. ESC hormone responsiveness was most robust when limited to the first six cell passages. Hence, investigation of ESC cultures as a decidualization model should respect this limitation of cell aging. The results support the hypotheses that "inflammaging" contributes to endometrial senescence, disruption of decidualization and impairment of fecundity. IL-1β and the JNK signaling pathway are pathogenetic targets amenable to pharmacological correction or mitigation with the potential to reduce endometrial stromal senescence and enhance uterine receptivity.

Differential gene expression in decidualized human endometrial stromal cells induced by different stimuli

Decidualization can be induced by culturing human endometrial stromal cells (ESCs) with several decidualization stimuli, such as cAMP, medroxyprogesterone acetate (MPA) or Estradiol (E2). However, it has been unclear how decidualized cells induced by different stimuli are different. We compared transcriptomes and cellular functions of decidualized ESCs induced by different stimuli (MPA, E2 + MPA, cAMP, and cAMP + MPA). We also investigated which decidualization stimulus induces a closer in vivo decidualization. Differentially expressed genes (DEGs) and altered cellular functions by each decidualization stimuli were identified by RNA-sequence and gene-ontology analysis. DEGs was about two times higher for stimuli that use cAMP (cAMP and cAMP + MPA) than for stimuli that did not use cAMP (MPA and E2 + MPA). cAMP-using stimuli altered the cellular functions including angiogenesis, inflammation, immune system, and embryo implantation whereas MPA-using stimuli (MPA, E2 + MPA, and cAMP + MPA) altered the cellular functions associated with insulin signaling. A public single-cell RNA-sequence data of the human endometrium was utilized to analyze in vivo decidualization. The altered cellular functions by in vivo decidualization were close to those observed by cAMP + MPA-induced decidualization. In conclusion, decidualized cells induced by different stimuli have different transcriptome and cellular functions. cAMP + MPA may induce a decidualization most closely to in vivo decidualization.

RhoB Promotes Endometrial Stromal Cells Decidualization Via Semaphorin3A/PlexinA4 Signaling in Early Pregnancy

Endometrial decidualization refers to a series of morphological changes and functional remodeling of the uterine endometrium to accept the embryo under the effect of estrogen and progesterone secreted by ovaries after ovulation. During decidualization, endometrial stromal cells (ESCs) proliferate and differentiate into decidual stromal cells, undergoing cytoskeletal rearrangement-mediated morphological changes and expressing decidualization markers, such as insulin-like growth factor-binding protein-1 and prolactin. Ras homology (Rho) proteins, a family of small G proteins, are well known as regulators of cellular morphology and involved in multiple other cellular processes. In this study, we found ras homolog family member B (RHOB) was the most significantly upregulated gene in the Rho protein family after the in vitro decidualization of human primary ESCs. RhoB expression was induced mainly by 3',5'-cyclic adenosine 5'-monophosphate (cAMP) / protein kinase A (PKA) / cyclic adenosine monophosphate-response element binding protein signaling and partly by progesterone signaling. Knockdown of RhoB in ESCs greatly inhibited actin cytoskeletal rearrangement, cell morphological transformation, and upregulation of insulin-like growth factor-binding protein-1, suggesting an indispensable role of RhoB in decidualization. Mechanistically, the downstream target of RhoB was semaphorin3A (Sema3A), which mediated its signaling via interacting with the receptor, plexinA4. More importantly, decreased expression of RhoB, Sema3A, and plexinA4 were detected in deciduas from patients with unexplained spontaneous miscarriage. Collectively, our results indicate that RhoB/Sema3A/plexinA4 signaling plays a positive role in endometrial decidualization and relates to unexplained spontaneous miscarriage, which is worthy of further exploration so as to provide new insights into therapeutic strategies for pregnancy diseases associated with poor decidualization.

Cabergoline Stimulates Human Endometrial Stromal Cell Decidualization and Reverses Effects of Interleukin-1β In Vitro

CONTEXT

Human embryonic implantation is regulated by neuroendocrine hormones, ovarian steroids, growth factors, and cytokines. Sympathetic innervation of the uterus also may play a role.

OBJECTIVE

We tested the hypothesis that cabergoline (Cb), an agonist of type 2 dopamine receptors (DRD2), could influence endometrial decidualization in vitro.

METHODS

Immunohistochemistry confirmed the presence of catecholaminergic neurons in human uterine tissue. DRD2 mRNA and protein expression in endometrial tissue and cells were validated by quantitative RT-PCR, cDNA microarrays, RNA sequencing, and Western blotting. Isolated human endometrial stromal cells (ESC) were subjected to dose-response and time-course experiments in the absence or presence of decidualizing hormones (10 nM estradiol, 100 nM progesterone, and 0.5 mM dibutyryl cAMP). In some cases, interleukin (IL)-1β (0.1 nM) was used as an inflammatory stimulus. Well-characterized in vitro biomarkers were quantified.

RESULTS

DRD2 were maximally expressed in vivo in the mid-secretory phase of the cycle and upregulated in ESC in response to decidualizing hormones, as were classical (eg, prolactin) and emerging (eg, VEGF and connexin 43) differentiation biomarkers. Cabergoline treatment more than doubled decidual biomarker expression, whereas risperidone, a dopamine receptor antagonist, inhibited ESC differentiation by >50%. Cabergoline induced characteristic decidual morphology changes and blocked detrimental effects of IL-1β on decidual cytology.

CONCLUSION

Our results support the hypothesis that dopaminergic neurons modulate decidualization in situ. We postulate that dopamine agonists, like Cb, could be developed as therapeutic agents to enhance implantation in couples with inflammation-associated infertility.

Role of Peroxisome Proliferator-Activated Receptors (PPARs) in Trophoblast Functions

Peroxisome proliferator-activated receptors (PPARα, PPARβ/δ, and PPARγ) belong to the transcription factor family, and they are highly expressed in all types of trophoblast during pregnancy. The present review discusses currently published papers that are related to the regulation of PPARs via lipid metabolism, glucose metabolism, and amino acid metabolism to affect trophoblast physiological conditions, including differentiation, maturation, secretion, fusion, proliferation, migration, and invasion. Recent pieces of evidence have proven that the dysfunctions of PPARs in trophoblast lead to several related pregnancy diseases such as recurrent miscarriage, preeclampsia, intrauterine growth restriction, and gestational diabetes mellitus. Moreover, the underlying mechanisms of PPARs in the control of these processes have been discussed as well. Finally, this review's purposes are to provide more knowledge about the role of PPARs in normal and disturbed pregnancy with trophoblast, so as to find PPAR ligands as a potential therapeutic target in the treatment and prevention of adverse pregnancy outcomes.