Prolactin (PRL) induction of cyclooxygenase 2 (COX2) expression and prostaglandin (PG) production in hamster Leydig cells

Impact of COVID-19 on sperm quality and the prostaglandin and polyamine systems in the seminal fluid

BACKGROUND

The implications of SARS-CoV-2 infection on male fertility remain largely unknown. Besides their well-known pro- and anti-inflammatory actions, prostaglandins and polyamines are present in semen, where they play key roles in sperm quality.

OBJECTIVES

To analyze semen parameters, oxidative profile and the seminal fluid prostaglandin and polyamine systems in samples collected from individuals without coronavirus disease 2019 diagnosis and men who recovered from coronavirus disease 2019.

MATERIALS AND METHODS

This study compared semen collected from men without positive coronavirus disease 2019 diagnosis with samples obtained from individuals 1-6 months and 7-30 months post SARS-CoV-2 infection. Semen parameters, thiobarbituric acid reactive substances, cyclooxygenase 2 expression by fluorescence immunocytochemistry and immunoblotting, prostaglandin levels by enzyme immunoassay, ornithine decarboxylase activity by a radioactive assay, and polyamine and acetylated polyamine levels by thin-layer chromatography were assessed.

RESULTS

In both groups of semen samples from coronavirus disease 2019 recovered men, sperm vitality, total and progressive sperm motility, and putrescine levels were significantly decreased when compared with samples from the uninfected group. In contrast, lipid peroxidation, leukocyte-associated cyclooxygenase 2 expression, and prostaglandin D2 levels were higher in semen from coronavirus disease 2019 recovered men than in samples from uninfected individuals. While sperm concentration and morphology, ornithine decarboxylase activity, and N-acetylputrescine levels were statistically diminished in semen obtained up to 6 months after coronavirus disease 2019 recovery, these parameters remained unchanged when samples were collected 7-30 months after coronavirus disease 2019 recovery. Coronavirus disease 2019 vaccination did not show negative effects on any of the parameters evaluated.

DISCUSSION AND CONCLUSION

Our work provides insights into the detrimental impact of coronavirus disease 2019 on several sperm parameters, in some cases, even more than a year after SARS-CoV-2 infection, which would be accompanied by alterations in the seminal fluid prostaglandin and polyamine profiles. Therefore, future treatments targeting the prostaglandin and polyamine pathways in coronavirus disease 2019 recovered men could lead to a successful reinstatement of semen parameters.

Seasonal expressions of COX-1, COX-2, and EP4 in the scent glands of muskrats (Ondatra zibethicus)

Prostaglandins (PGs) serve as signaling molecules that regulate various physiological processes, including inflammation, immune response, blood clotting, and reproduction. The aim of this study was to investigate the immunolocalizations and expression patterns of prostaglandin-E2 (PGE2), cyclooxygenase (COX)-1, and COX-2, as well as its receptor subtypes 4 (EP4) in the scent glands of muskrats (Ondatra zibethicus) during the breeding and nonbreeding periods. There were significant seasonal differences in the scent glandular mass, with higher values in the breeding season and relatively low in the nonbreeding season. PGE2, EP4, COX-1, and COX-2 have been immunolocalized in the scent glandular and epithelial cells in both breeding and nonbreeding seasons, whereas no immunostaining was observed in the interstitial cells. The protein and mRNA expression levels of EP4, COX-1, and COX-2 were higher in the scent glands of the breeding season than those of the nonbreeding season. The mean mRNA levels of EP4, COX-1, and COX-2 were positively correlated with the scent glandular weights. The circulating follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), and PGE2, as well as scent glandular PGE2 and dihydrotestosterone (DHT) concentrations, were also significantly higher in the breeding season. In addition, the transcriptomic study in the scent glands identified that differentially expressed genes might be related to fatty carboxylic monocarboxylic acid, steroidogenic-related pathways, and prostanoid metabolic processes. These findings suggested that prostaglandin-E2 might play an essential autocrine or paracrine role in regulating seasonal changes in the scent glandular functions of the muskrats.

Identifying a causal link between prolactin signaling pathways and COVID-19 vaccine-induced menstrual changes

COVID-19 vaccines have been instrumental tools in the fight against SARS-CoV-2 helping to reduce disease severity and mortality. At the same time, just like any other therapeutic, COVID-19 vaccines were associated with adverse events. Women have reported menstrual cycle irregularity after receiving COVID-19 vaccines, and this led to renewed fears concerning COVID-19 vaccines and their effects on fertility. Herein we devised an informatics workflow to explore the causal drivers of menstrual cycle irregularity in response to vaccination with mRNA COVID-19 vaccine BNT162b2. Our methods relied on gene expression analysis in response to vaccination, followed by network biology analysis to derive testable hypotheses regarding the causal links between BNT162b2 and menstrual cycle irregularity. Five high-confidence transcription factors were identified as causal drivers of BNT162b2-induced menstrual irregularity, namely: IRF1, STAT1, RelA (p65 NF-kB subunit), STAT2 and IRF3. Furthermore, some biomarkers of menstrual irregularity, including TNF, IL6R, IL6ST, LIF, BIRC3, FGF2, ARHGDIB, RPS3, RHOU, MIF, were identified as topological genes and predicted as causal drivers of menstrual irregularity. Our network-based mechanism reconstruction results indicated that BNT162b2 exerted biological effects similar to those resulting from prolactin signaling. However, these effects were short-lived and didn't raise concerns about long-term infertility issues. This approach can be applied to interrogate the functional links between drugs/vaccines and other side effects.

SARS-CoV-2 Enters Human Leydig Cells and Affects Testosterone Production In Vitro

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a SARS-like coronavirus, continues to produce mounting infections and fatalities all over the world. Recent data point to SARS-CoV-2 viral infections in the human testis. As low testosterone levels are associated with SARS-CoV-2 viral infections in males and human Leydig cells are the main source of testosterone, we hypothesized that SARS-CoV-2 could infect human Leydig cells and impair their function. We successfully detected SARS-CoV-2 nucleocapsid in testicular Leydig cells of SARS-CoV-2-infected hamsters, providing evidence that Leydig cells can be infected with SARS-CoV-2. We then employed human Leydig-like cells (hLLCs) to show that the SARS-CoV-2 receptor angiotensin-converting enzyme 2 is highly expressed in hLLCs. Using a cell binding assay and a SARS-CoV-2 spike-pseudotyped viral vector (SARS-CoV-2 spike pseudovector), we showed that SARS-CoV-2 could enter hLLCs and increase testosterone production by hLLCs. We further combined the SARS-CoV-2 spike pseudovector system with pseudovector-based inhibition assays to show that SARS-CoV-2 enters hLLCs through pathways distinct from those of monkey kidney Vero E6 cells, a typical model used to study SARS-CoV-2 entry mechanisms. We finally revealed that neuropilin-1 and cathepsin B/L are expressed in hLLCs and human testes, raising the possibility that SARS-CoV-2 may enter hLLCs through these receptors or proteases. In conclusion, our study shows that SARS-CoV-2 can enter hLLCs through a distinct pathway and alter testosterone production.

Comparative transcriptome analysis reveals potential testosterone function-related regulatory genes/pathways of Leydig cells in immature and mature buffalo (Bubalus bubalis) testes

Leydig cells (LCs) are testosterone-generating endocrine cells that are located outside the seminiferous tubules in the testis, and testosterone is fundamental for retaining spermatogenesis and male fertility. In buffalo, adult Leydig cells (ALCs) are developed by immature Leydig cells (ILCs) in the postnatal testes. However, the genes/pathways associated to the regulation of testosterone secretion function during the development of postnatal LCs remains comprehensively unidentified. The present study comparatively analyzed the transcriptome profiles of ILC and ALC in buffalo with significant differences in testosterone secretion. Differentially expressed genes (DEGs) analysis identified 972 and 1,091 annotated genes that were significantly up- and down-regulated in buffalo ALC. Functional enrichment analysis showed that cAMP signaling being the most significantly enriched pathway, and testosterone synthesis and lipid transport-related genes/pathways were upregulated in ALC. Furthermore, gene set enrichment analysis (GSEA) shows that cAMP signaling and steroid hormone biosynthesis were activated in ALC, demonstrating that cAMP signaling may serve as a positive regulatory pathway in the maintenance of testosterone function during postnatal development of LCs. Protein-protein interaction (PPI) networks analysis highlighted that ADCY8, ADCY2, POMC, CHRM2, SST, PTGER3, SSTR2, SSTR1, NPY1R, and HTR1D as hub genes in the cAMP signaling pathway. In conclusion, this study identified key genes and pathways associated in the regulation of testosterone secretion function during the ILC-ALC transition in buffalo based on bioinformatics analysis, and these key genes might be deeply involved in cAMP generation to influencing testosterone levels in LCs. The results suggest that ALCs might increase testosterone levels by enhancing cAMP production than ILCs. Our data will enhance the understanding of developmental mechanism studies related to testosterone function and provide preliminary evidence for molecular mechanisms of LCs regulating spermatogenesis.

Male and female gonadal ageing: its impact on health span and life span

Ageing is linked to changes in the hypothalamic-pituitary-gonadal axis and a progressive decline in gonadal function. While women become infertile when they enter menopause, fertility decline in ageing men does not necessarily involve a complete cessation of spermatogenesis. Gonadal dysfunction in elderly people is characterized by morphological, endocrine and metabolic alterations affecting the reproductive function and quality of life. With advancing age, sexuality turns into a critical emotional and physical factor actually defining the number of years that ageing people live a healthy life. Gonadal ageing correlates with comorbidities and an increased risk of age-related diseases including diabetes, kidney problems, cardiovascular failures and cancer. This article briefly summarizes the current state of knowledge on ovarian and testicular senescence, explores the experimental models used in the study of gonadal ageing, and describes the local pro-inflammatory, oxidative and apoptotic events and the associated signalling pathways that take place in the gonads while people get older. Overall, literature reports that ageing exacerbates a mutual crosstalk among oxidative stress, apoptosis and the inflammatory response in the gonads leading to detrimental effects on fertility. Data also highlight the clinical implications of novel therapeutic interventions using antioxidant, anti-apoptotic and anti-inflammatory drugs on health span and life span.

Expression of PTGS2, PGFS and PTGFR during downregulation and restart of spermatogenesis following GnRH agonist treatment in the dog

Prostaglandins (PGs) and prostaglandin endoperoxide synthase (PTGS) are considered to be relevant for spermatogenesis and steroidogenesis. PTGS2, prostaglandin F synthase (PGFS) and PGF receptor (PTGFR) are investigated in the adult male dog using the model of the GnRH-agonist implant downregulated canine testis and its subsequent restart of spermatogenesis following abolition of treatment (3, 6, 9, 12 weeks after implant removal). On the mRNA level (ratio), PTGS2, PGFS and PTGFR expression did not differ between downregulation, different stages of recovery of spermatogenesis and untreated adult controls (CG). On the protein level, Sertoli and Leydig cells in all samples and some peritubular cells stained immunopositive for PTGS2. In the tubular compartment, the percentage of the PTGS2-immunopositive area (PIA) and the mean PTGS2-staining intensity (gray scale, GS) did not differ between groups but in the interstitial compartment, the PIA (p = 0.0494) and the GS (p < 0.0001) were significantly upregulated during early recrudescence (week 3/6). Comparing downregulation by two GnRH-agonist implants with juvenile controls (JG) and CG, the mRNA expression (ratio) did not differ. In the tubular compartment, the GS (p = 0.0321) was significantly higher at downregulation compared to CG and in the interstitial compartment, the PIA (p = 0.0073) and the GS (p = 0.0097) were significantly higher in JG compared to downregulation/CG. PTGS2, PGFS and PTGFR mRNA and PTGS2 protein are regularly expressed in the adult, juvenile and downregulated canine testis and downregulation and subsequent recrudescence affect PTGS2 protein expression mainly in Leydig cells. PTGS2 expression in the downregulated testis resembles the one in seasonal Syrian hamster but not juvenile canine testis.

Possible role of PGD2 in malaria infections

OBJECTIVE

To preliminarily investigate the possible role of prostaglandin D2 (PGD2) in malaria infections.

METHODS

Blood and urinary samples (n = 120 each) were collected from Thai patients with Plasmodium falciparum (P. falciparum) with moderate (n = 26) and high (n = 4) parasitemia, patients with Plasmodium vivax (P. vivax) (n = 30), patients with fever associated with other infections (n = 30), and healthy subjects (n = 30). PGD2 concentrations in plasma and urinary samples of healthy subjects, patients with fever associated with other infections and patients with malaria were determined using Prostaglandin D2-MOX express EIA kit (Cayman Chemical, USA).

RESULTS

The possible association between PGD2 and malaria infections is clearly demonstrated with PGD2 concentration in urine. The urinary PGD2 concentrations were relatively high (about 5-fold) in patients with P. falciparum with moderate parasitemia and P. vivax infections compared with other groups. Furthermore, the concentration in patients with P. falciparum with moderate parasitemia and P. vivax infection were significantly higher than that in healthy subjects and patients with fever associated with other infections.

CONCLUSIONS

Urinary PGD2 concentrations may offer a more dependable and useful tool for predicting malaria severity. Confirmation is this preliminary finding is required with a larger sample size.

Cyclooxygenase and prostaglandins in somatic cell populations of the testis

Prostaglandins (PGs) are synthesized through the action of the rate-limiting enzyme cyclooxygenase (COX) and further specific enzymes. The development ofCox-deficient mice in the 1990s gave insights into the reproductive roles of PGs. FemaleCox-knockout mice were subfertile or infertile. Interestingly, fertility was not affected in male mice deficient inCox, suggesting that PGs may not be critical for the functioning of the testis. However, this conclusion has recently been challenged by observations of important roles for PGs in both physiological and pathological processes in the testis. The two key somatic cell types in the testis, Leydig and Sertoli cells, express the inducible isoenzyme COX2 and produce PGs. Testicular COX2 expression in these somatic cells is regulated by hormonal input (FSH, prolactin (PRL), and testosterone) as well as by IL1β. PGs modulate steroidogenesis in Leydig cells and glucose uptake in Sertoli cells. Hence, the COX2/PG system in Leydig and Sertoli cells acts as a local modulator of testicular activity, and consequently may regulate spermatogenic efficiency. In addition to its expression in Leydig and Sertoli cells, COX2 has been detected in the seminiferous tubule wall, and in testicular macrophages and mast cells of infertile patients. These observations highlight the possible relevance of PGs in testicular inflammation associated with idiopathic infertility. Collectively, these data indicate that the COX2/PG system plays crucial roles not only in testicular physiology (i.e., development, steroidogenesis, and spermatogenesis), but more importantly in the pathogenesis or maintenance of infertility status in the male gonad. Further studies of these actions could lead to new therapeutic approaches to idiopathic male infertility.

Free German abstract

A German translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC1.

Free Spanish abstract

A Spanish translation of this abstract is freely available athttp://www.reproduction-online.org/content/149/4/R169/suppl/DC2.

Prolactin increases tumor necrosis factor alpha expression in peripheral CD14 monocytes of patients with rheumatoid arthritis

Tumor necrosis factor (TNF)-α is one of the major proinflammatory mediators of rheumatic arthritis (RA); the regulatory factors for TNF-α release is not fully understood. This study aims to investigate the role of prolactin receptor (PRLR) activation in regulating the expression and release of TNF-α from CD14(+) monocytes. The results showed that the expression of PRLR was detectable in CD14(+) monocytes of healthy subjects, which was markedly increased in RA patients. Exposure to PRL in the culture increased the expression and release of TNF-α from CD14(+) monocytes, which was abolished by the PRLR gene silencing or blocking the mitogen activated protein (MAPK) pathway. We conclude that exposure to PRL increases TNF-α release from CD14(+) monocytes of RA patients, which can be abolished by PRLR gene silencing or treating with MAPK inhibitor.

Loss of 15-hydroxyprostaglandin dehydrogenase indicates a tumor suppressor role in pituitary adenomas

15-hydroxyprostaglandin dehydrogenase (15-PGDH) may function as a tumor suppressor that antagonizes the action of the cyclooxygenase-2 (COX-2) oncogene in several types of tumors. However, it is unknown if it has a role in the pituitary. Recently, our group found that 15-PGDH expression was low in prolactin (PRL) secreting adenomas (prolactinomas) and growth hormone (GH) secreting adenomas (GHomas) using fiber-optic BeadArray technology. In this study, we examined the relative expression of 15-PGDH and COX-2 mRNA in clinical specimens and examined the effects of 15-PGDH on GH3 rat pituitary tumor cell proliferation, apoptosis and hormone secretion. 15-PGDH expression was lower and COX-2 expression was higher in prolactinomas and GHomas compared with normal controls. Overexpressed 15-PGDH inhibited tumor cell proliferation and induced apoptosis. It had a significant suppressive effect on mRNA levels and on the secretion of PRL and GH in GH3 cells. The inhibition of cell proliferation was accompanied by the decreased expression of cox-2, matrix metalloproteinase-9 (MMP-9) and B cell leukemia/lymphoma-2 (Bcl-2). These data are suggestive of a previously unrecognized pathway in pituitary tumorigenesis, and this novel observation may shed light on therapeutic strategies for pituitary tumors.