Purinergic signaling in the ovary

Sex-related differences in the response of anti-platelet drug therapies targeting purinergic signaling pathways in sepsis

Sepsis, a complex clinical syndrome resulting from a serious infection, is a major healthcare problem associated with high mortality. Sex-related differences in the immune response to sepsis have been proposed but the mechanism is still unknown. Purinergic signaling is a sex-specific regulatory mechanism in immune cell physiology. Our studies have shown that blocking the ADP-receptor P2Y12 but not P2Y1 receptor was protective in male mice during sepsis, but not female. We now hypothesize that there are sex-related differences in modulating P2Y12 or P2Y1 signaling pathways during sepsis. Male and female wild-type (WT), P2Y12 knock-out (KO), and P2Y1 KO mice underwent sham surgery or cecal ligation and puncture (CLP) to induce sepsis. The P2Y12 antagonist ticagrelor or the P2Y1 antagonist MRS2279 were administered intra-peritoneally after surgery to septic male and female mice. Blood, lungs and kidneys were collected 24 hours post-surgery. Sepsis-induced changes in platelet activation, secretion and platelet interaction with immune cells were measured by flow cytometry. Neutrophil infiltration in the lung and kidney was determined by a myeloperoxidase (MPO) colorimetric assay kit. Sepsis-induced platelet activation, secretion and aggregate formation were reduced in male CLP P2Y12 KO and in female CLP P2Y1 KO mice compared with their CLP WT counterpart. Sepsis-induced MPO activity was reduced in male CLP P2Y12 KO and CLP P2Y1 KO female mice. CLP males treated with ticagrelor or MRS2279 showed a decrease in sepsis-induced MPO levels in lung and kidneys, aggregate formation, and platelet activation as compared to untreated male CLP mice. There were no differences in platelet activation, aggregate formation, and neutrophil infiltration in lung and kidney between female CLP mice and female CLP mice treated with ticagrelor or MRS2279. In human T lymphocytes, blocking P2Y1 or P2Y12 alters cell growth and secretion in vitro in a sex-dependent manner, supporting the data obtained in mice. In conclusion, targeting purinergic signaling represents a promising therapy for sepsis but drug targeting purinergic signaling is sex-specific and needs to be investigated to determine sex-related targeted therapies in sepsis.

Functional expression of P2Y2 receptors in mouse ovarian surface epithelium (OSE)

Ovarian surface epithelium (OSE) is a cell monolayer surrounding the ovary; it is involved in the regulation of the ovulatory process and the genesis of ovarian carcinoma. However, intercellular messengers regulating signaling events, like proliferation in the OSE, have not been completely described. Purines have emerged as novel intercellular messengers in the ovary, in which expression of purinergic receptors has been reported in different cell types. In the present work, we described the functional expression of P2Y2 receptor (P2Y2R), a purinergic receptor widely associated with cell proliferation, in the OSE. The expression of P2Y2R by immunofluorescence and RT-PCR, and its functionality by Ca²⁺ recording was demonstrated in primary cultured OSE. Functional expression of P2Y2R was also exhibited in situ, by recording of intracellular Ca²⁺ release and detection of ERK phosphorylation after injection of a selective agonist into the ovarian bursa. Furthermore, P2Y2R activation with UTPγS, in situ, induced cell proliferation at 24 h, whereas continuous stimulation of P2Y2R during a complete estrous cycle significantly modified the size distribution of the follicular population. This is the first evidence of the functional expression of purinergic P2Y2R in the OSE and opens new perspectives on the roles played by purines in ovarian physiology.

Autocrine and paracrine purinergic signaling in the most lethal types of cancer

Cancer comprises a collection of diseases that occur in almost any tissue and it is characterized by an abnormal and uncontrolled cell growth that results in tumor formation and propagation to other tissues, causing tissue and organ malfunction and death. Despite the undeniable improvement in cancer diagnostics and therapy, there is an urgent need for new therapeutic and preventive strategies with improved efficacy and fewer side effects. In this context, purinergic signaling emerges as an interesting candidate as a cancer biomarker or therapeutic target. There is abundant evidence that tumor cells have significant changes in the expression of purinergic receptors, which comprise the G-protein coupled P2Y and AdoR families of receptors and the ligand-gated ion channel P2X receptors. Tumor cells also exhibit changes in the expression of nucleotidases and other enzymes involved in nucleotide metabolism, and the concentrations of extracellular nucleotides are significantly higher than those observed in normal cells. In this review, we will focus on the potential role of purinergic signaling in the ten most lethal cancers (lung, breast, colorectal, liver, stomach, prostate, cervical, esophagus, pancreas, and ovary), which together are responsible for more than 5 million annual deaths.

Adipose-Derived Mesenchymal Stem Cell Transplantation in Chemotherapy-Induced Premature Ovarian Insufficiency: the Role of Connexin and Pannexin

In women undergoing chemotherapy, it is inevitable that infertility risk will increase because of impaired reproductive functions. Premature ovarian insufficiency (POI), which occurs as a devastating result of chemotherapy, is the complete depletion or dysfunction of ovarian follicles. Adipose-derived mesenchymal stem cells (ADMSCs) transplantation is among the alternative treatment methods for POI, which currently do not have an effective treatment method. Apoptosis of granulosa cells in POI is seen as the main mechanism of the disease. It is also reported that in addition to molecules directly associated with apoptosis, connexins, and pannexins are also potential effector molecules in apoptosis. The roles of these molecules in POI, which are known to play a role in many important mechanisms in the ovary, are unknown. In this study, it was aimed to analyze the expressions of Connexin43 and Pannexin1, which are thought to be effective in the formation of POI, and to show the relationship between the antiapoptotic effects of ADMSCs transplantation and these molecules in POI. For this purpose, Caspase3, Connexin43, Pannexin1 proteins, and mRNA expressions were analyzed by immunohistochemistry and RT-qPCR, and AMH levels were measured by ELISA. It was determined that Pannexin1, Caspase3 proteins, and mRNA levels increased in the POI, while Pannexin1 and Caspase3 expressions decreased in the ADMSCs treated group. While Connexin43 level decreased in POI, Connexin43 protein and mRNA levels increased in ADMSCs group. Consequently, this study demonstrated for the first time that Connexin43 and Pannexin1 were associated with apoptosis in POI. In addition, it was revealed that ADMSCs transplantation could produce antiapoptotic effects by modulating these molecules.

Purinergic Signaling in Endometriosis-Associated Pain

Endometriosis is an estrogen-dependent gynecological disease, with an associated chronic inflammatory component, characterized by the presence of endometrial tissue outside the uterine cavity. Its predominant symptom is pain, a condition notably altering the quality of life of women with the disease. This review is intended to exhaustively gather current knowledge on purinergic signaling in endometriosis-associated pain. Altered extracellular ATP hydrolysis, due to changes in ectonucleotidase activity, has been reported in endometriosis; the resulting accumulation of ATP in the endometriotic microenvironment points to sustained activation of nucleotide receptors (P2 receptors) capable of generating a persistent pain message. P2X3 receptor, expressed in sensory neurons, mediates nociceptive, neuropathic, and inflammatory pain, and is enrolled in endometriosis-related pain. Pharmacological inhibition of P2X3 receptor is under evaluation as a pain relief treatment for women with endometriosis. The role of other ATP receptors is also discussed here, e.g., P2X4 and P2X7 receptors, which are involved in inflammatory cell–nerve and microglia–nerve crosstalk, and therefore in inflammatory and neuropathic pain. Adenosine receptors (P1 receptors), by contrast, mainly play antinociceptive and anti-inflammatory roles. Purinome-targeted drugs, including nucleotide receptors and metabolizing enzymes, are potential non-hormonal therapeutic tools for the pharmacological management of endometriosis-related pain.

Purinergic signaling in hepatic disease

Extracellular purines (ATP and adenosine) are ubiquitous intercellular messengers. During tissular damage, they function as damage-associated molecular patterns (DAMPs). In this context, purines announce tissue alterations to initiate a reparative response that involve the formation of the inflammasome complex and the recruitment of specialized cells of the immune system. The present review focuses on the role of the purinergic system in liver damage, mainly during the onset and development of fibrosis. After hepatocellular injury, extracellular ATP promotes a signaling cascade that ameliorates tissue alterations to restore the hepatic function. However, if cellular damage becomes chronic, ATP orchestrates an aberrant reparative process that results in severe liver diseases such as fibrosis and cirrhosis. ATP and adenosine, their receptors, and extracellular ectonucleotidases are mediators of unique processes that will be reviewed in detail.

Dydrogesterone exposure induces zebrafish ovulation but leads to oocytes over-ripening: An integrated histological and metabolomics study

Dydrogesterone (DDG) is a synthetic progestin widely used in numerous gynecological diseases. DDG has been shown to disturb fish reproduction, however, the mechanism is still unclear. Here we studied the histological changes and differences of metabolome between exposed and control fish gonads after exposure of zebrafish (Danio rerio) embryos to 2.8, 27.6, and 289.8 ng/L DDG until sexual maturity for a total of 140 days. Dydrogesterone exposure led to male-biased zebrafish sex ratios. Histological examination revealed that DDG induced postovulatory follicles and atretic follicles in the ovary of the female fish. Postovulatory follicles indicated the occurrence of ovulation. DDG also increased spermatids and spermatozoa in the male fish testis, suggesting promotion of spermatogenesis. Ovarian metabolome showed that DDG increased the concentrations of free amino acids, urea, putrescine, free fatty acids, acylcarnitines, lysophospholipids, and other metabolites catabolized from phospholipids. Most of these metabolites are biodegradation products of proteins and lipids, suggesting the existence of ovulated oocytes over-ripening. Further, DDG upregulated arachidonic acid (AA) and its 5‑lipoxygenase (5-LOX) metabolites 5‑oxo‑6,8,11,14‑eicosatetraenoic acid (5-oxo-ETE) in the ovary, which could lead to suppression of AA cyclooxygenase (COX) metabolite prostaglandin F2α (PGF2α). It is believed that AA induced oocyte maturation, while 5-oxo-ETE and related metabolites in purinergic signaling promoted ovulation. Whereas, the suppression of PGF2α production might block spawning and damaged follicular tissue digestion, which explained the oocytes over-ripening and atretic follicles in the treated ovary. Overall, our results suggested that DDG exposure induced zebrafish oocyte maturation and ovulation but led to oocytes over-ripening via the AA metabolic pathway and purinergic signaling.

Experimental polycystic ovarian syndrome is associated with reduced expression and function of P2Y2 receptors in rat theca cells

Extracellular purines through specific receptors have been recognized as new regulators of ovarian function. It is known that P2Y2 receptor activity induces theca cell proliferation, we hypothesized that purinergic signaling controls the changes related to hyperthecosis in polycystic ovarian syndrome (PCOS). The aim of this study was to analyze the expression of UTP-sensitive P2Y receptors and their role in theca cells (TC) proliferation in experimentally-induced PCOS (EI-PCOS). In primary cultures of TC from intact rats, all the transcripts of P2Y receptors were detected by polymerase chain reaction; in these cells, UTP (10 μM) induced extracellular signal-regulated kinases (ERK) phosphorylation. Rats with EI-PCOS showed a reduced expression of P2Y2R in TC whereas P2Y4R did not change. By analyzing ERK phosphorylation, it was determined that P2Y2R is the most relevant receptor in TC. UTP promoted cell proliferation in TC from control but not from EI-PCOS rats. The in silico analysis of P2yr2 promoter indicated the presence of androgen response elements; the stimulation of TC primary cultures with testosterone promoted a significant reduction in the expression of the P2yr2 transcript. We concluded that P2Y2R participates in controlling the proliferative rate of TCs from healthy ovaries, but this regulation is lost during EI-PCOS.