Metformin attenuates susceptibility to inflammation-induced preterm birth in mice with higher endocannabinoid levels

Differences in microRNA within plasma extracellular vesicles at various time points during early pregnancy in sheep revealed by high-throughput sequencing data

Exosome microRNAs are vital for gene transcription and expression, influencing target genes. They may play direct and indirect roles in pregnancy across animal models and humans. The objective of this research was to comprehensively explore the expression profiles of plasma exosomal miRNAs during the early pregnancy stage in sheep. This study specifically delved into the differences in the expression of plasma exosomal miRNAs between Chinese Merino and Suffolk sheep. The primary focus was on clearly elucidating the changes in plasma exosomal miRNAs, pinpointing potential biomarkers that might exert an impact on early pregnancy, and thoroughly exploring their biological functions as well as the possible underlying molecular mechanisms. Chinese Merino and Suffolk sheep were divided into two groups of 20 for artificial insemination. Blood samples were collected at various pregnancy stages (day 0, day 14, and day 30), Ultrasound diagnosis was carried out five weeks following artificial insemination. Three pregnant sheep from each group were selected for isolating extracellular vesicle-derived miRNAs from plasma. High-throughput sequencing identified differentially expressed miRNAs, and their target genes were analyzed using bioinformatics methods. In plasma exosomal samples derived from all sheep of both breeds at various time points during the early pregnancy stage, a cumulative total of 80 known miRNAs and 182 novel miRNAs were successfully identified. Compared to day 0 gestation controls, both sheep breeds showed differential expression of six known miRNAs: four were up- regulated and two down- regulated. Pathway analysis linked these miRNAs to biological processes such as ECM receptor interactions, growth hormone synthesis, carbohydrate digestion, adrenergic signaling in cardiomyocytes, and MAPK signaling regulation. Notably, Oar-mir-27a differed between the two groups at various time points. In summary, this research meticulously carried out a profiling analysis of the expression of plasma exosomal miRNAs in Chinese Merino and Suffolk sheep. Through this analysis, several exosomal miRNAs were identified, which display distinct abundance levels during the early pregnancy period. These findings strongly imply that these miRNAs have the potential to serve as biomarkers for precisely assessing the reproductive status of sheep.

TNFSF14+ natural killer cells prevent spontaneous abortion by restricting leucine-mediated decidual stromal cell senescence

In preparation for a potential pregnancy, the endometrium of the uterus changes into a temporary structure called the decidua. Senescent decidual stromal cells (DSCs) are enriched in the decidua during decidualization, but the underlying mechanisms of this process remain unclear. Here, we performed single-cell RNA transcriptomics on ESCs and DSCs and found that cell senescence during decidualization is accompanied by increased levels of the branched-chain amino acid (BCAA) transporter SLC3A2. Depletion of leucine, one of the branched-chain amino acids, from cultured media decreased senescence, while high leucine diet resulted in increased senescence and high rates of embryo loss in mice. BCAAs induced senescence in DSCs via the p38 MAPK pathway. In contrast, TNFSF14+ decidual natural killer (dNK) cells were found to inhibit DSC senescence by interacting with its ligand TNFRSF14. As in mice fed high-leucine diets, both mice with NK cell depletion and Tnfrsf14-deficient mice with excessive uterine senescence experienced adverse pregnancy outcomes. Further, we found excessive uterine senescence, SLC3A2-mediated BCAA intake, and insufficient TNFRSF14 expression in the decidua of patients with recurrent spontaneous abortion. In summary, this study suggests that dNK cells maintain senescence homeostasis of DSCs via TNFSF14/TNFRSF14, providing a potential therapeutic strategy to prevent DSC senescence-associated spontaneous abortion.

The Role and Mechanism of Metformin in Inflammatory Diseases

Metformin is a classical drug used to treat type 2 diabetes. With the development of research on metformin, it has been found that metformin also has several advantages aside from its hypoglycemic effect, such as anti-inflammatory, anti-aging, anti-cancer, improving intestinal flora, and other effects. The prevention of inflammation is critical because chronic inflammation is associated with numerous diseases of considerable public health. Therefore, there has been growing interest in the role of metformin in treating various inflammatory conditions. However, the precise anti-inflammatory mechanisms of metformin were inconsistent in the reported studies. Thus, this review aims to summarize various currently known possible mechanisms of metformin involved in inflammatory diseases and provide references for the clinical application of metformin.

Metformin beyond an anti-diabetic agent: A comprehensive and mechanistic review on its effects against natural and chemical toxins

In addition to the anti-diabetic effect of metformin, a growing number of studies have shown that metformin has some exciting properties, such as anti-oxidative capabilities, anticancer, genomic stability, anti-inflammation, and anti-fibrosis, which have potent, that can treat other disorders other than diabetes mellitus. We aimed to describe and review the protective and antidotal efficacy of metformin against biologicals, chemicals, natural, medications, pesticides, and radiation-induced toxicities. A comprehensive search has been performed from Scopus, Web of Science, PubMed, and Google Scholar databases from inception to March 8, 2023. All in vitro, in vivo, and clinical studies were considered. Many studies suggest that metformin affects diseases other than diabetes. It is a radioprotective and chemoprotective drug that also affects viral and bacterial diseases. It can be used against inflammation-related and apoptosis-related abnormalities and against toxins to lower their effects. Besides lowering blood sugar, metformin can attenuate the effects of toxins on body weight, inflammation, apoptosis, necrosis, caspase-3 activation, cell viability and survival rate, reactive oxygen species (ROS), NF-κB, TNF-α, many interleukins, lipid profile, and many enzymes activity such as catalase and superoxide dismutase. It also can reduce the histopathological damages induced by many toxins on the kidneys, liver, and colon. However, clinical trials and human studies are needed before using metformin as a therapeutic agent against other diseases.

Measuring the Content of Endocannabinoid-Like Compounds in Biological Fluids: A Critical Overview of Sample Preparation Methodologies

Different mass spectrometric techniques have been used over the past decade to quantify endocannabinoids (eCBs) and related lipids. Even with the level of molecular fingerprinting accuracy of an instrument like the most advanced triple quadrupole mass spectrometer, if one is not getting the most optimized sample to the detector in a way that this improved technology can be of use, then advancements can be stymied. Here, our focus is on review and discussion of sample preparation methodologies used to isolate the eCB anandamide and its close congeners N-acyl ethanolamines and structural congeners (i.e., lipo amino acids, lipoamines, N-acyl amides) in biological fluids. Most of our focus will be on the analysis of these lipids in plasma/serum, but we will also discuss how the same techniques can be used for the analysis of saliva and breast milk.

A Review on the Use of Metformin in Pregnancy and Its Associated Fetal Outcomes

A commonly used first-line anti-diabetic medication, metformin, has been used in pregnancy. The drug is known to have specific effects on different organs around the body. One of these organs includes the ovaries. Therefore, for more than 40 years, it has often been prescribed for maternal obesity along with gestational diabetes mellitus. Untreated pregnancies like these frequently result in complications for both the mother and the fetus, like macrosomia, pregnancy-induced hypertension, obstructed labor, stillbirths, and perinatal deaths. In addition, there is also evidence that these mothers tend to develop type II diabetes mellitus during their pregnancy and even a few years post-delivery. These complications can be controlled or even reduced with the help of metformin, sometimes combining it with insulin or clomiphene citrate if required. There is still a need to cautiously prescribe the drug by outweighing its benefits against the risk associated with it. The current research on the subject leans more towards the benefits offered to the mother during pregnancy. Only a few randomized, controlled trials have been conducted on the fetal condition after the mother has been administered metformin.

Furthermore, these studies lack the appropriate sample size and long-term follow-up on these metformin-exposed offspring. As a result, there are no reliable data available to clinicians and physicians about the drug. Owing to its benefits in certain pregnancies, it is less likely that the drug will cease to be prescribed. Therefore, it becomes increasingly imperative to conduct more research on this topic to ensure the drug is safe for the mother and the offspring.

Metformin inhibits testosterone-induced endoplasmic reticulum stress in ovarian granulosa cells via inactivation of p38 MAPK

STUDY QUESTION

Does metformin inhibit excessive androgen-induced endoplasmic reticulum (ER) stress in mouse granulosa cells (GCs) in vivo and in vitro?

SUMMARY ANSWER

Metformin inhibits testosterone-induced ER stress and unfolded protein response (UPR) activation by suppressing p38 MAPK phosphorylation in ovarian GCs.

WHAT IS KNOWN ALREADY

Polycystic ovary syndrome (PCOS) is associated with hyperandrogenism. Excessive testosterone induces ER stress and UPR activation in human cumulus cells, leading to cell apoptosis. Metformin has potential inhibitory effects on ER stress and UPR activation, as demonstrated in human pancreatic beta cells and obese mice.

STUDY DESIGN, SIZE, DURATION

Cumulus cells and follicular fluid were collected from 25 women with PCOS and 25 controls at our IVF centre. A dihydrotestosterone (DHT)-induced PCOS mouse model was constructed and treated with or without metformin. Primary mouse GCs and cumulus-oocyte complexes (COCs) were cultured with testosterone, metformin, a p38 MAPK inhibitor, or p38 MAPK small interfering RNA.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The levels of UPR sensor proteins and UPR-related genes were measured in cumulus cells from PCOS and control patients by real-time quantitative PCR (qPCR) and western blot. The ovaries, oocytes, GCs and COCs were collected from PCOS mice treated with metformin and controls. The expressions of ER stress markers and p38 MAPK phosphorylation were assessed by qPCR, western blot and immunofluorescence. A subsequent in vitro analysis with primary cultured GCs and COCs was used to confirm the influence of metformin on ER stress activation by qPCR and western blot. Finally, the effects of ER stress activation on GCs and COCs in relation to LH responsiveness were examined by qPCR and COC expansion.

MAIN RESULTS AND THE ROLE OF CHANCE

The expression of the ER stress markers GRP78, CHOP and XBP1s in the cumulus cells was higher in PCOS patients than in control patients, as were the levels of the UPR sensor proteins p-IRE1α, p-EIF2α and GRP78. Compared to those of control mice, the ovaries, GCs and COCs of DHT-treated PCOS mice showed increased levels of ER stress marker genes and proteins. Hyperandrogenism in PCOS mouse ovaries also induced p38 MAPK phosphorylation in COCs and GCs. Metformin inhibited ER stress activation was associated with decreased p-p38 MAPK levels. In vitro experiments, testosterone-induced ER stress was mitigated by metformin or p38 MAPK inhibition in primary cultured GCs and COCs. COCs expanded rapidly in the presence of testosterone during LH administration, and ovulation-related genes, namely, Areg, Ereg, Ptgs2, Sult1e1, Ptx3 and Tnfaip6, were strongly expressed in the COCs and GCs. These effects were reversed by treatment with metformin, an ER stress inhibitor or by knockdown of p38 MAPK.

LIMITATIONS, REASONS FOR CAUTION

The number of PCOS patients in this study was small.

WIDER IMPLICATIONS OF THE FINDINGS

This study provides further evidence for metformin as a PCOS treatment.

STUDY FUNDING/COMPETING INTEREST(S)

This study was funded by the National Key Research and Developmental Program of China (2018YFC1004800), the Key Research and Development Program of Zhejiang Province (2017C03022), the Zhejiang Province Medical Science and Technology Plan Project (2017KY085, 2018KY457), the National Natural Science Foundation of China (31701260, 81401264, 81701514), and the Special Funds for Clinical Medical Research of the Chinese Medical Association (16020320648). The authors report no conflict of interest in this work and have nothing to disclose.

TRIAL REGISTRATION NUMBER

N/A.

A functional role for AMPK in female fertility and endometrial regeneration

Adenosine monophosphate-activated protein kinase (AMPK) is a highly conserved heterotrimeric complex that acts as an intracellular energy sensor. Based on recent observations of AMPK expression in all structures of the female reproductive system, we hypothesized that AMPK is functionally required for maintaining fertility in the female. This hypothesis was tested by conditionally ablating the two catalytic alpha subunits of AMPK, Prkaa1 and Prkaa2, using Pgr-cre mice. After confirming the presence of PRKAA1, PRKAA2 and the active phospho-PRKAA1/2 in the gravid uterus by immunohistochemistry, control (Prkaa1/2 fl/fl ) and double conditional knockout mice (Prkaa1/2 d/d ) were placed into a six-month breeding trial. While the first litter size was comparable between Prkaa1/2 fl/fl and Prkaa1/2 d/d female mice (P = 0.8619), the size of all subsequent litters was dramatically reduced in Prkaa1/2 d/d female mice (P = 0.0015). All Prkaa1/2 d/d female mice experienced premature reproductive senescence or dystocia by the fourth parity. This phenotype manifested despite no difference in estrous cycle length, ovarian histology in young and old nulliparous or multiparous animals, mid-gestation serum progesterone levels or uterine expression of Esr1 or Pgr between Prkaa1/2 fl/fl and Prkaa1/2 d/d female mice suggesting that the hypothalamic-pituitary-ovary axis remained unaffected by PRKAA1/2 deficiency. However, an evaluation of uterine histology from multiparous animals identified extensive endometrial fibrosis and disorganized stromal-glandular architecture indicative of endometritis, a condition that causes subfertility or infertility in most mammals. Interestingly, Prkaa1/2 d/d female mice failed to undergo artificial decidualization. Collectively, these findings suggest that AMPK plays an essential role in endometrial regeneration following parturition and tissue remodeling that accompanies decidualization.

Molecular Studies on Pregnancy with Mouse Models

Pregnancy is a complex process that involves crosstalk among multiple cell types in both the endometrial and myometrial compartments at the maternal side to support the fetus. Genetic engineered mouse models have served as a major platform to dissect the convolute genetic interactions in a physiological context. Combining with various applications of next generation sequencing and genome editing, functional assays by mouse models have expanded the spectrum to include both coding and noncoding genome. The present review will highlight recent findings that are primarily based on studies of mouse models with emphasis on pathways for endometrial receptivity and myometrial contraction. Emerging novel technologies that may advance the research in these two aspects will also be discussed.

The (endo)cannabinoid signaling in female reproduction: What are the latest advances?

Cannabis extracts like marijuana have the highest consumption rate worldwide. Yet, their societal acceptance as recreational and therapeutic drugs could represent a serious hazard to female human reproduction, because cannabis ingredients [termed (phyto)cannabinoids] can perturb an endogenous system of lipid signals known as endocannabinoids. Accumulated evidence on animal models and humans has demonstrated a crucial role of these endogenous signals on different aspects of female reproduction, where they act through an ensamble of proteins that synthesize, transport, degrade and traffic them. Several reports have recently evidenced the potential role of endocannabinoids as biomarkers of female infertility for disease treatment and prevention, as well as their possible epigenetic effects on pregnancy. The purpose of this review is to provide an update of data collected in the last decade on the effects of cannabinoids and endocannabinoids on female reproductive events, from development and maturation of follicles and oocytes, to fertilization, oviductal transport, implantation and labor. In this context, a particular attention has been devoted to the ovary and the production of fertilizable oocytes, because recent studies have addressed this hot topic with conflicting results among species.

Metformin from mother to unborn child - Are there unwarranted effects?

For more than 40 years, metformin has been used before and during pregnancy. However, it is important to note that metformin can cross the placenta and circulate in the developing foetus. Recent studies reported that the concentration of metformin in foetal cord blood ranges from half to nearly the same concentration as in the maternal plasma. Since metformin has anti-cell growth and pro-apoptotic effects, there are persistent concerns over the use of metformin in early pregnancy. Current human studies are limited by sample size, lack of controls or, short follow-up durations. In this review, we examine the settings in which metformin can be passed on from mother to child during pregnancy and address the current controversies relating to the cellular and molecular mechanisms of metformin. Our efforts highlight the need for more data on the effects of metformin on general offspring health as well as further scrutiny into foetal development upon exposure to metformin.

Placental exosome-mediated Bta-miR-499-Lin28B/let-7 axis regulates inflammatory bias during early pregnancy

Abnormal inflammatory bias in the maternal-fetal interface leads to reproductive failure in mammals. Placental exosomes are involved in maternal-fetal communication during pregnancy. However, whether the placenta or fetus is involved in regulating the balance of uterine local inflammation through exosomes remains unclear, and the mechanism must be further explored. Here we demonstrated that placenta-specific exosomes are abundant in the peripheral blood of dairy cows during early pregnancy and selectively load miRNAs, such as bta-miR-499. In vitro, placental exosome-derived bta-miR-499 inhibits the activation of NF-κB via the Lin28B/let-7 axis, thus repressing LPS-induced inflammation in bovine endometrial epithelial (BEND) cells. Subsequently, inhibition of mmu-miR-499 leads to an impaired balance of inflammation at the maternal-fetal interface in vivo, resulting in an increased risk of pregnancy failure due to placental loss and fetal growth restriction. Thus, our data demonstrate that placental exosomal miR-499 may be a critical immune regulator in the regulation of the inflammation balance at the maternal-fetal interface in the early gestation of dairy cows and other mammals.