Uterine RGS2 expression is regulated by exogenous estrogen and progesterone in ovariectomized mice, and downregulation of RGS2 expression in artificial decidualized ESCs inhibits trophoblast spreading in vitro

The role of sex hormones in aldosterone biosynthesis and their potential impact on its mineralocorticoid receptor

Blood pressure (BP) regulation is a complex process involving various hormones, including aldosterone and its mineralocorticoid receptor. Mineralocorticoid receptor is expressed in several tissues, including the kidney, and plays a crucial role in regulating BP by controlling the sodium and water balance. During different stages of life, hormonal changes can affect mineralocorticoid receptor activity and aldosterone levels, leading to changes in BP. Increasing evidence suggests that sex steroids modulate aldosterone levels. Estrogens, particularly estradiol, mediate aldosterone biosynthesis by activating classical estrogen receptors and the G protein-coupled receptor. Progesterone acts as an anti-mineralocorticoid by inhibiting the binding of aldosterone to the mineralocorticoid receptor. Moreover, progesterone inhibits aldosterone synthase enzymes. The effect of testosterone on aldosterone synthesis is still a subject of debate. However, certain studies show that testosterone downregulates the mRNA levels of aldosterone synthase, leading to decreased plasma aldosterone levels.

Estrogen-sensitive activation of SGK1 induces M2 macrophages with anti-inflammatory properties and a Th2 response at the maternal-fetal interface

BACKGROUND

Decidual macrophages participate in immune regulation at the maternal-fetal interface. Abnormal M1/M2 polarization of decidual macrophages might predispose immune maladaptation in recurrent pregnancy loss (RPL). However, the mechanism of decidual macrophage polarization is unclear. We explored the role of Estradiol (E₂)-sensitive serum-glucocorticoid regulated kinase (SGK) 1 in promoting macrophage polarization and suppressing inflammation at the maternal-fetal interface.

METHODS

We assessed serum levels of E₂ and progesterone during first trimester of pregnancy in women with or without threatened miscarriages (ended in live birth, n = 448; or early miscarriages, n = 68). For detection of SGK1 in decidual macrophages, we performed immunofluorescence labeling and western blot analysis applying decidual samples from RPL (n = 93) and early normal pregnancy (n = 66). Human monocytic THP-1 cells were differentiated into macrophages and treated with Toll-like receptor (TLR) 4 ligand lipopolysaccharide (LPS), E₂, inhibitors or siRNA for in vitro analysis. Flow cytometry analysis were conducted to detect macrophages polarization. We also applied ovariectomized (OVX) mice with hormones exploring the mechanisms underlying the regulation of SGK1 activation by E₂ in the decidual macrophages in vivo.

RESULTS

SGK1 expression down regulation in the decidual macrophages of RPL was consistent with the lower concentration and slower increment of serum E₂ from 4 to 12 weeks of gestation seen in these compromised pregnancies. LPS reduced SGK1 activities, but induced the pro-inflammatory M1 phenotype of THP-1 monocyte-derived macrophages and T helper (Th) 1 cytokines that favored pregnancy loss. E₂ pretreatment promoted SGK1 activation in the decidual macrophages of OVX mice in vivo. E₂ pretreatment amplified SGK1 activation in TLR4-stimulated THP-1 macrophages in vitro through the estrogen receptor beta (ERβ) and PI3K pathway. E₂-sensitive activation of SGK1 increased M2 macrophages and Th2 immune responses, which were beneficial to successful pregnancy, by inducing ARG1 and IRF4 transcription, which are implicated in normal pregnancy. The experiments on OVX mice have shown that pharmacological inhibition of E₂ promoted nuclear translocation of NF-κB in the decidual macrophages. Further more, pharmacological inhibition or knockdown of SGK1 in TLR4-stimulated THP-1 macrophages activated NF-κB by promoting its nuclear translocation, leading to increased secretion of pro-inflammatory cytokines involved in pregnancy loss.

CONCLUSION

Our findings highlighted the immunomodulatory roles of E₂-activated SGK1 in Th2 immune responses by priming anti-inflammatory M2 macrophages at the maternal-fetal interface, resulting in a balanced immune microenvironment during pregnancy. Our results suggest new perspectives on future preventative strategies for RPL.

Uterine extracellular vesicles as multi-signal messengers during maternal recognition of pregnancy in the mare

In contrast to other domestic mammals, the embryo-derived signal(s) leading to maternal recognition of pregnancy (MRP) are still unknow in the mare. We hypothesize that these embryonic signals could be packed into uterine extracellular vesicles (uEVs), acting as multi-signal messengers between the conceptus and the maternal tract, and contributing to MRP. To unveil these signals, the RNA and protein cargos of uEVs isolated from uterine lavages collected from pregnant mares (P; day 10, 11, 12 and 13 after ovulation) and cyclic control mares (C; day 10 and 13 after ovulation) were analyzed. Our results showed a fine-tuned regulation of the uEV cargo (RNAs and proteins), by the day of pregnancy, the estrous cycle, and even the size of the embryo. A particular RNA pattern was identified with specific increase on P12 related to immune system and hormonal response. Besides, a set of proteins as well as RNAs was highly enriched in EVs on P12 and P13. Differential abundance of miRNAs was also identified in P13-derived uEVs. Their target genes were linked to down- or upregulated genes in the embryo and the endometrium, exposing their potential origin. Our study identified for first time specific molecules packed in uEVs, which were previously associated to MRP in the mare, and thus bringing added value to the current knowledge. Further integrative and functional analyses will help to confirm the role of these molecules in uEVs during MRP in the mare.

Spatiotemporal endometrial transcriptome analysis revealed the luminal epithelium as key player during initial maternal recognition of pregnancy in the mare

During the period of maternal recognition of pregnancy (MRP) in the mare, the embryo needs to signal its presence to the endometrium to prevent regression of the corpus luteum and prepare for establishment of pregnancy. This is achieved by mechanical stimuli and release of various signaling molecules by the equine embryo while migrating through the uterus. We hypothesized that embryo's signals induce changes in the endometrial gene expression in a highly cell type-specific manner. A spatiotemporal transcriptomics approach was applied combining laser capture microdissection and low-input-RNA sequencing of luminal and glandular epithelium (LE, GE), and stroma of biopsy samples collected from days 10-13 of pregnancy and the estrous cycle. Two comparisons were performed, samples derived from pregnancies with conceptuses ≥ 8 mm in diameter (comparison 1) and conceptuses ≤ 8 mm (comparison 2) versus samples from cyclic controls. The majority of gene expression changes was identified in LE and much lower numbers of differentially expressed genes (DEGs) in GE and stroma. While 1253 DEGs were found for LE in comparison 1, only 248 were found in comparison 2. Data mining mainly focused on DEGs in LE and revealed regulation of genes related to prostaglandin transport, metabolism, and signaling, as well as transcription factor families that could be involved in MRP. In comparison to other mammalian species, differences in regulation of genes involved in epithelial barrier formation and conceptus attachment and implantation reflected the unique features of equine reproduction at the time of MRP at the molecular level.

Silencing of RGS2 enhances hippocampal neuron regeneration and rescues depression-like behavioral impairments through activation of cAMP pathway

Depression is one of the most common mental disorders with an increasing incidence. However, factors involved in depression are so complex, thus it is difficult to find effective strategies to reverse the impairments. This study aims to verify the role of regulator of G protein signaling 2 (RGS2) in the mouse mode of unpredictable mild stress-induced depression-like behaviors. Knockdown of RGS2 was achieved by transfection of siRNA-RGS2 in mouse hippocampal (HT-22) cells in vitro and injection of recombinant adenovirus expressing siRNA-RGS2 in mice in vivo. An aberrant high expression of RGS2 was found in mice with depression-like behaviors through immunohistochemical analysis. Silencing of RGS2 or Forskolin (activator of cAMP pathway) developed sweet water consumption, reduced inflammation and oxidative stress injury, and attenuated cognitive impairment and neuronal damage in mice with depression-like behaviors. Furthermore, regeneration was enhanced and apoptosis was repressed in mouse hippocampal neurons in the presence of RGS2 knockdown and Forskolin. Mechanistic studies indicated that silencing of RGS2 promoted the activation of cAMP pathway, thus rescuing depression-like behaviors of mice. Collectively, our study uncovered the role of RGS2-dependent cAMP pathway in regulation of cognitive impairment and hippocampal neuron regeneration in depression-like behaviors of mice, which may be a potential therapeutic target for impairments and symptoms associated with depression.