Differential modulation of porcine theca, granulosa, and luteal cell steroidogenesis in vitro by tumor necrosis factor

Role of macrophage colony-stimulating factor (M-CSF) in human granulosa cells

Macrophage colony-stimulating factor (M-CSF) has been proved to have a positive role in the follicular development. We investigated its effect on human granulosa cells and found that M-CSF could stimulate the production of E₂. The production of FSH receptors was enhanced by M-CSF in vitro in a dose-dependent manner with or without the addition of tamoxifen (p <0.05). Correspondingly, FSH was also able to coordinate the expression of M-CSF and its receptor (p <0.05). That maybe important to maintain the level of Nppc and the meiotic arrest of the oocyte. The protein p-JAK2 and p-STAT3 in JAK/STAT-signaling pathway elevated after the influence of M-CSF (p < 0.05). These results suggest that M-CSF has a role in regulating the response of granulosa cells to gonadotropins. Its function is associated with JAK/STAT-signaling pathway.

Tumor necrosis factor-alpha activates nuclear factor-kappaB but does not regulate progesterone production in cultured human granulosa luteal cells

BACKGROUND

The role of tumor necrosis factor-alpha (TNF-alpha) in granulosa luteal cell function and steroidogenesis is still controversial. Our aim was to examine the steroidogenic response, together with the simultaneous expression and activation of nuclear factor-kappaB (NF-kappaB), in cultured human granulosa luteal cells (GLCs) following administration of TNF-alpha.

MATERIALS AND METHODS

This prospective controlled study was conducted in the Human Reproduction Division at the Institute of Maternal and Child Research, Faculty of Medicine, University of Chile and the San Borja Arriarán Hospital, National Health Service, Santiago, Chile. GLCs were obtained from aspirates of follicles from women undergoing in vitro fertilization (IVF). Thirty-two women undergoing IVF for tubal-factor and/or male-factor infertility participated in this study. Protein levels of NF-kappaB, the NF-kappaB inhibitor IkappaBalpha and steroidogenic acute regulatory protein (StAR) were determined by Western blot and localization of NF-kappaB was studied by indirect immunofluorescence. Progesterone production was determined by radioimmunoassay.

RESULTS

TNF-alpha did not affect the expression of StAR protein or the synthesis of progesterone. NF-kappaB was expressed in the GLCs and activated by TNF-alpha, resulting in degradation of IkappaBalpha and mobilization of the p65 NF-kappaB subunit into the nucleus.

CONCLUSIONS

These results indicate that TNF-alpha did not modulate steroidogenesis in cultured human GLCs. However, NF-kappaB was activated by TNF-alpha. Therefore the activation of NF-kappaB via the TNF-alpha pathway is likely associated with other preovulatory granulosa cell processes important for human ovarian function.

Changes in the expression of tumor necrosis factor (TNF) alpha, TNFalpha receptor (TNFR) 2, and TNFR-associated factor 2 in granulosa cells during atresia in pig ovaries

Tumor necrosis factor (TNF) alpha can induce both cell death and cell proliferation and exerts its effects by binding to either TNF receptor (TNFR) 1 or 2. When TNFalpha-bound TNFR2 interacts with TNFR-associated factor 2 (TRAF2), expression of survival/antiapoptotic genes is up-regulated. In the present study we determined the changes in localization of TNFalpha and TRAF2 and their mRNAs and the expression of TNFR2 in granulosa cells during follicular atresia in pig ovaries. In healthy follicles, intense signals for TNFalpha and TRAF2 and their mRNAs were demonstrated in the outer zone of the granulosa layer, where many proliferating cells and no apoptotic cells were observed. In atretic follicles, decreased or trace staining for TRAF2 and its mRNA and decreased expression of TNFR2 were observed in the granulosa layer, where many apoptotic cells were seen. These findings suggested that TNFalpha acts as a survival factor in granulosa cells during follicular atresia in pig ovaries.

Role of tumor necrosis factor in preovulatory follicles of swine

The effects of tumor necrosis factor (TNF) on cultured porcine granulosa cells that were obtained from preovulatory follicles were studied with regard to following parameters: 1) TNF receptor type I expression, 2) progesterone receptor and transforming growth factor beta receptor type II (TbetaR II) as markers of luteinization, 3) proliferation, and 4) apoptosis. For comparative purposes the effects of TNF were also studied on insulin/forskolin-treated cells, as this treatment is well established to induce luteinization. Cytochemical methods followed by semiquantitative analysis were used. Our data show that TNF treatment upregulates TNF receptor type I expression in granulosa cells. TNF downregulates the expression of TbetaR II of insulin/forskolin-stimulated and of unstimulated cells. The progesterone receptor is also downregulated by the cytokine after insulin/forskolin-induced luteinization. Supplementation of the medium with TNF leads to increased proliferation and at the same time it induces apoptosis. Our results indicate that TNF exerts an inhibitory influence on luteinization and that TNF influences the balance between follicular growth (proliferation) and atresia (apoptosis).

Receptors for insulin-like growth factor-I and tumor necrosis factor-alpha are hormonally regulated in bovine granulosa and thecal cells

Mastitis induces release of tumor necrosis factor-alpha (TNFalpha) and has been linked with reduced reproductive performance. To further elucidate the role and mechanism of action of TNFalpha on ovarian cells, the effect of TNFalpha on insulin-like growth factor-I (IGF-I)-induced steroidogenesis and IGF-I binding sites in granulosa and thecal cells as well as the hormonal regulation of TNFalpha receptors were evaluated. Granulosa and thecal cells were obtained from small (1-5mm) and large (> or =8mm) bovine ovarian follicles, respectively, and cultured for 3-4 days. During the last 2 days of culture, cells were treated with various hormones and steroid production and specific binding of 125I-IGF-I and 125I-TNFalpha was determined. Two-day treatment with 30 ng/ml of TNFalpha decreased (P<0.05) IGF-I-induced estradiol production by granulosa cells and IGF-I-induced androstenedione production by thecal cells. Two-day treatment with 10 and 30ng/ml of TNFalpha decreased (P<0.05) specific binding of 125I-IGF-I to thecal cells, but had no effect on specific binding of 125I-IGF-I to granulosa cells, or on specific binding of 125I-IGF-II to thecal cells. TNFalpha did not compete for 125I-IGF-I binding to granulosa or thecal cells whereas unlabeled IGF-I suppressed 125I-IGF-I binding. Insulin inhibited (P<0.10) whereas FSH had no effect on the number of specific 125I-TNFalpha binding sites in granulosa cells. In contrast, LH increased (P<0.10) whereas insulin had no effect on specific 125I-TNFalpha binding sites in thecal cells. These results suggest that IGF-I and TNFalpha receptors in granulosa and thecal cells are regulated by hormones differentially.

Influence of the drinking water disinfection by-product dibromoacetic acid on rat estrous cyclicity and ovarian follicular steroid release in vitro

The drinking water disinfection by-product, dibromoacetic acid (DBA) has been reported to affect gonadal functions in the male rat. However, there is little information regarding the influence of DBA on female reproductive activity. Consequently, the present study investigated the effects of DBA on estrous cyclicity and the impact in vitro of DBA on ovarian follicular steroid secretion. Regularly cycling animals were dosed with DBA (0 to 270 mg/kg/day) for 14 days and estrous cyclicity was monitored during treatment and for an additional 2-week posttreatment interval. A dose-related alteration in cyclicity was observed at 90 and 270 mg/kg/day, which persisted through the posttreatment monitoring in the high dose group. An in vitro exposure of preovulatory follicles to DBA was then used to assess the influence of DBA on steroid release. To select a concentration for use, a single oral exposure to 270 mg/kg was administered, and the mean blood levels were determined over a 5-h interval. For this in vitro work, pairs of preovulatory follicles from PMSG-primed immature rats were exposed to 0 or 50 microg/mL DBA over a 24-h period and evaluated for estradiol and progesterone release under baseline and hCG-stimulated conditions. The influence of tumor necrosis factor (TNFalpha) exposures under these conditions was also determined. In the nonstimulated condition, DBA was found to increase the release of estradiol, but had no detectable effect in response to hCG. Progesterone, however, showed marked suppression under hCG stimulation following exposure to DBA, while nonstimulated secretion was unaffected. TNFalpha by itself also suppressed stimulated progesterone release, but had no additional effect in combination with DBA. The data suggest that one factor in the disruption in estrous cyclicity could be an alteration in steroid production, which was characterized by separate effects on both estradiol and progesterone secretion.

Luteinizing hormone (LH) drives diverse intracellular calcium second messenger signals in isolated porcine ovarian thecal cells: preferential recruitment of intracellular Ca2+ oscillatory cells by higher concentrations of LH

The present study examines Ca2+ second messenger signaling driven by LH in isolated porcine thecal cells. To this end, we implemented semiquantitative fluorescent (fura-2) videomicroscopic imaging of single thecal cells in vitro. Stimulation of 388 cells with LH (5 microg/ml) elicited an intracellular Ca2+ ([Ca2+]i) signal in 85+/-5.3% of individual thecal cells (n = 11 experiments). Among 337 LH-responsive cells, we identified four predominant temporal modes of [Ca2+]i signaling: 1) [Ca2+]i oscillations with periodicities of 0.5 to 4.5 min(-1) (63+/-4.5%), 2) a [Ca2+]i spike followed by a sustained plateau (17+/-2.6%), 3) a [Ca2+]i spike only (5.8+/-2.6%); and 4) a [Ca2+]i plateau only (3.8+/-1.5%). The prevalence, but not the amplitude or frequency, of LH-induced [Ca2+]i oscillations in thecal cells was dependent on the agonist concentration. Reduced availability of extracellular Ca2+ induced by treatment with EGTA or cobaltous chloride did not block the initiation, but reversibly abolished ongoing [Ca2+]i oscillations (72% of cells) or increased the mean [Ca2+]i interspike periodicity from 1.09+/-0.16 to 0.59+/-0.07 min(-1) (P < 0.05). Putative phospholipase C inhibition with U-73122 (10 microM) also abolished or frequency-damped LH-driven [Ca2+]i oscillations in 95+/-4.7% of cells. [Ca2+]i oscillations in thecal cells were not abrogated by overnight pretreatment with pertussis toxin. We conclude that 1) thecal cells (unlike earlier findings in granulosa cells) manifest a diverse array of [Ca2+]i signaling responses to LH at the single cell level; 2) LH can dose dependently recruit an increasing number of individually [Ca2+]i oscillating thecal cells; 3) extracellular Ca2+ is required for LH to sustain (but not initiate) frequent and high amplitude [Ca2+] oscillations in thecal cells; and 4) these signaling actions of LH are mediated via phospholipase C, but not a pertussis-toxin sensitive mechanism. Accordingly, the present data extend the apparent complexity of LH-induced [Ca2+]i second messenger signaling and identify at the single cell level LH's dose-responsive drive of [Ca2+]i oscillations in gonadal cells.

Tumor necrosis factor-alpha and its receptor in bovine corpus luteum throughout the estrous cycle

The objective of this study was to investigate tumor necrosis factor alpha (TNF-alpha) expression, the presence of functional TNF-alpha receptors, and expression of TNF receptor type I (TNF-RI) mRNA in the bovine corpus luteum (CL) during different stages of the estrous cycle. Reverse transcription (RT)-polymerase chain reaction (PCR) showed no difference in TNF-alpha mRNA expression during the estrous cycle. Concentrations of TNF-alpha in the CL tissue increased significantly from the mid to the late luteal stage and decreased thereafter (P < 0.05). An RT-PCR analysis showed higher levels of TNF-RI mRNA in CL of Days 3-7 than of other stages (P < 0.05). (125)I-TNF-alpha binding to the membranes of bovine CL was maximal after incubation at 38 degrees C for 48 h. The binding was much greater for TNF-alpha than for related peptides. A Scatchard analysis revealed the presence of a high-affinity binding site in the CL membranes collected at each phase of the estrous cycle (dissociation constant: 3.60 +/- 0.58-5.79 +/- 0.19 nM). In contrast to TNF-RI mRNA expression, the levels of receptor protein were similar at each stage of the estrous cycle. When cultured cells of all luteal stages were exposed to TNF-alpha (1-100 ng/ml), TNF-alpha stimulated prostaglandin F(2alpha) and prostaglandin E(2) secretion by the cells in a dose-dependent fashion (P < 0.01), especially during the early luteal phase, although it did not affect progesterone secretion. These results indicate the local production of TNF-alpha and the presence of functional TNF-RI in bovine CL throughout the estrous cycle, and suggest that TNF-alpha plays some roles in regulating bovine CL function throughout the estrous cycle.

Alterations of events related to ovarian function in tumor necrosis factor receptor type I knockout mice

C57BL6 mice with targeted disruption of tumor necrosis factor (TNF) type 1 receptor (TNFRI) exhibited early vaginal opening when compared with wild-type mice (Day 24 +/- 0.6, n = 10, vs. 28 +/- 0.2, n = 11, P < 0.001). Equine CG- and hCG-treated TNFRI null mice ovulated more ova than did controls at two distinct times during the prepubertal period (Day 21: 13.4 +/- 1.7 vs. 7.3 +/- 1.4, P < 0.05; Day 25: 20.7 +/- 2.7 vs. 13.0 +/- 1.3, P < 0.05). Enhanced responsiveness to gonadotropins was not observed in adult mice. At 6 mo of age only 40% of TNFRI null mice exhibited estrous cycles. Those TNFRI null mice with estrous cycles spent significantly more time in diestrus and less time in estrus than controls. TNFRI null mice delivered significantly fewer litters (P < 0.001) than did C57BL6 and TNFRII null mice (TNFRI null 2.59 +/- 0.39; C57BL6 4.91 +/- 0.57; TNFRII null 5.40 +/- 0.60 litters/mo/10 pairs over a 12-mo period). Ovarian dispersates prepared on Day 25 of age from control and TNFRI knockout mice were cultured with and without 10 ng TNF/ml. TNF inhibited LH-stimulated progesterone and estradiol secretion by control dispersates but had no effect on cAMP. In contrast, TNF did not affect LH-stimulated accumulation of progesterone, estradiol, or cAMP by ovarian dispersates from TNFRI knockout mice. The results indicate that lack of TNFRI enhances ovarian responsiveness to gonadotropins during the prepubertal period and may be related to early vaginal opening. The lack of TNFRI is associated with early senescence and poor fertility. These studies demonstrate that the mechanism of TNF-mediated inhibition of steroidogenesis is most likely via TNFRI.

Local release of steroid hormones, prostaglandin E2, and endothelin-1 from bovine mature follicles In vitro: effects of luteinizing hormone, endothelin-1, and cytokines

Local regulation of ovulation involves the interaction of LH and intrafollicular factors including steroids, prostaglandins, and peptides derived from endothelial cells, leukocytes, fibroblasts, and steroidogenic cells. To estimate the intrafollicular role of endothelin-1 (ET-1) and its possible interaction with LH, tumor necrosis factor alpha (TNFalpha), and interleukin-1beta (IL-1beta), a microdialysis system was implanted into the theca layer of preovulatory bovine follicles that were maintained in organ culture chambers. The effects of LH, ET-1, TNFalpha, and IL-1beta on the local release of steroids, prostaglandin E2 (PGE2), and ET-1 from the cells surrounding the implanted capillary membrane were investigated. Each preovulatory follicle (selected based on the concentrations of steroids and PGE2) was dissected from surrounding stromal tissue and implanted with 4 capillary dialysis membranes (control, LH, cytokines or ET-1, and LH+cytokine or LH+ET-1) into the theca layer. They were then incubated in organ culture chambers and perfused with Ringer's solution for 14 h after pre-perfusion for 2 h. The stimulation with LH (5 microg/ml) between 4 and 6 h increased the release of progesterone (P4), androstenedione (A), estradiol-17beta (E2), PGE2 (p < 0.001), and ET-1 (p < 0.05). The infusion of ET-1 (250 ng/ml) between 8 and 10 h inhibited P4 and A release but stimulated E2 release (p < 0.05). The infusion of TNFalpha (100 ng/ml) between 8 and 10 h after LH exposure suppressed the release of A and E2 (p < 0.05). IL-1beta (10 ng/ml) between 8 and 10 h stimulated E2 release but inhibited A release (p < 0.05). Moreover, ET-1 and cytokines clearly stimulated PGE2 release (p < 0.05). ET-1 and TNFalpha induced further release of PGE2 stimulated by LH (p < 0. 05). Also, TNFalpha and IL-1beta induced further release of ET-1 stimulated by LH (p < 0.05). These results show that ET-1 is released from the theca layer of mature bovine follicles in vitro and that it affects follicular steroids and PGE2 secretion. The overall results suggest that interactions among ET-1, PGE2, and cytokines may have key roles in a local intermediatory/amplifying system of the LH-triggered ovulatory cascade in the bovine preovulatory follicle.

Tumor necrosis factor-alpha (TNF-alpha) inhibits steroidogenesis of bovine ovarian granulosa and thecal cells in vitro. Involvement of TNF-alpha receptors

The effect of recombinant bovine tumor necrosis factor-alpha (TNF-alpha) on steroidogenesis and numbers of bovine ovarian granulosa and thecal cells has been studied, and specific binding sites for 125I-TNF-alpha on ovarian cells have been determined. Granulosa cells have been examined from small (surface diameter 1-5 mm) follicles, whereas thecal cells from large (> or = 8 mm) follicles were utilized. Increasing doses of TNF-alpha significantly attenuated insulin- and IGF-I-induced estradiol production by granulosa cells from small follicles, but had no effect on basal estradiol production. Moreover, TNF-alpha significantly attenuated insulin- and LH-induced androstenedione production by thecal cells from large follicles. TNF-alpha had little or no effect on the numbers of granulosa and thecal cells in these same studies. Specific high-affinity, low-capacity binding of 125I-TNF-alpha was also demonstrable in granulosa and thecal cells. Thus, it appears that TNF-alpha inhibits insulin- and IGF-I-induced estradiol production by granulosa cells and androstenedione production by thecal cells via TNF-alpha binding to its own receptor.

Review: cytokine involvement in ovarian processes

PROBLEM

Expression of tumor necrosis factor-alpha (TNF) and interleukins 1 alpha and 1 beta (IL-1) have been reported in ovaries of several species and humans and are implicated in ovarian follicular development and atresia, ovulation, steroidogenesis, and corpus luteum function (including formation, development, and regression). The principal abnormal processes affected by these cytokines are ovarian cancer and reduction of ovarian function during sepsis.

METHODS

A literature review.

RESULTS

Numerous studies indicate that TNF and IL-1 inhibit gonadotropin-stimulated steroidogenesis of undifferentiated ovarian cells due to inhibition of adenylyl cyclase and post-cAMP sites. In differentiated ovarian cells, these cytokines either stimulate progesterone synthesis or have little to no effect on steroidogenesis. Both cytokines participate in ovulation and levels of these cytokines increase during the preovulatory period. Endotoxin inhibits gonadotropin-stimulated ovarian steroidogenesis and follicular development and these effects are mediated, in part, by TNF and by direct effects of endotoxin on ovarian cells. IN newly formed corpora lutea, progesterone secretion is inhibited by TNF and IL-1, although each has proliferative effects. TNF also has been implicated in regression of corpora lutea because TNF stimulates prostaglandin synthesis and luteal TNF increases after initiation of the decline in progesterone secretion. TNF and IL-1 are secreted by some ovarian cancer cells and stimulate growth of these cells.

CONCLUSIONS

Thus, TNF and IL-1 are multifunctional factors affecting various ovarian processes.

Epidermal growth factor (EGF) receptor localization in cultured human granulosa lutein cells and the stimulation of progesterone production by EGF and transforming growth factor-alpha (TGF-alpha)

PURPOSE

The purpose of this study was to investigate the expression of EGF receptor (EGF-R) in human granulosa cells undergoing luteinization and progesterone production by these cells in response to EGF an TGF-alpha alone or in combination with luteinizing hormone (LH). Granulosa cells were obtained from IF patients following oocyte retrieval 34 to 36 hr post-hCG injection. EGF receptor was localized in cells by means of immunoperoxidase staining using a polyclonal primary antibody directed against the human EGF-R. To assess progesterone production, cells were seeded overnight, washed, and cultured with the growth factors +/- LH. Medium and treatments were changed every 24 hr for 3 days.

RESULTS

Specific EGF-R staining was observed in the cultured cells compared to those incubated with antibody that was preabsorbed with a 10-fold excess of EGF. Basal progesterone accumulation per 24-hr period was stimulated dose dependently on each day of culture, by both EGF (up to 3.5-fold at 5 or 50 ng/ml) and TGF-alpha (up to 4-fold at 50 ng/ml). The addition of LH alone also stimulated progesterone accumulation daily, and this effect was further enhanced dose dependently by cotreatment with EGF or TGF-alpha. Furthermore, tyrphostin, an EGF-R-specific tyrosine kinase inhibitor, inhibited both basal and growth factor-stimulated progesterone production.

CONCLUSION

These data suggest an EGF receptor-mediated physiological role for EGF and TGF-alpha in human luteal function involving an autocrine and/or a paracrine stimulation of progesterone production.

Lipopolysaccharide-induced increases in porcine serum cortisol and progesterone concentrations are not mediated solely by prostaglandin F2 alpha

The increase in steroid hormone blood levels in response to bacterial lipopolysaccharide (LPS) appears to be an important mechanism by which mammalian species regulate inflammation. This study examined changes in serum concentrations of cortisol, progesterone, and 13,14-dihydro-15-keto-prostaglandin F2 alpha (PGFM) in diestrous pigs following the intravenous injection of LPS and determined whether indomethacin would attenuate these changes. Serum cortisol and progesterone concentrations increased (P < 0.05) within 30 min after the administration of LPS, and the increases in steroid hormones were accompanied by a sharp, transient increase (P < 0.05) in PGFM levels. In the presence of indomethacin, serum PGFM levels did not change (P > 0.05); however, LPS enhanced (P < 0.05) cortisol and progesterone concentrations, although the increases were delayed. Serum concentrations of cortisol acutely increased (P < 0.05) immediately following both infusions of indomethacin. In summary, cortisol and progesterone concentrations increased irrespective of serum PGFM concentrations, thereby indicating that prostaglandin F2 alpha was not the sole mediator of LPS-induced changes in cortisol and progesterone concentrations.

Tumor necrosis factor-alpha inhibits ovulation and steroidogenesis, but not prostaglandin production in the perfused rat ovary

OBJECTIVE

We tested the null hypothesis that tumor necrosis factor-alpha (TNF-alpha) does not decrease ovulation, estradiol and progesterone production, or prostaglandin (PG) E2, PGF2alpha, or 6 keto-PGF1alpha production in the open bursa rat ovarian perfusion model.

METHODS

Experimental animals were controlled for age, weight, litter, and pregnant mare's serum gonadotropin (PMSG) aliquot. Female Sprague-Dawley rats, 26-27 days old, were injected with 25 IU PMSG. Forty-eight hours later, the right ovary was dissected, the bursa removed, and the specimen placed in the perfusion chamber with defined media. Luteinizing hormone and isobutylmethylxanthine were given as an ovulatory trigger. Test perfusions also received TNF-alpha in 0.8-nmol/L, -pmol/L, and -fmol/L doses. Samples were collected at 0, 1, 3, 5, 7, 10, and 20 hours. Ovulations were counted at 20 hours. Steroids and PGs were measured.

RESULTS

The addition of TNF-alpha to the rat ovarian perfusion model resulted in a dose-dependent decrease in ovulations (mean +/- standard deviation): 16.14 +/- 6.2 in controls (n = 7) versus 2.38 +/- 3.4 with TNF-alpha 0.8 nmol/L (n = 7), and 4.3 +/- 1.5 with TNF-alpha 0.8 pmol/L (n = 3), both P < .001. Tumor necrosis factor-alpha also inhibited estradiol (P < .005) and progesterone production (P < .05) throughout, but produced no significant changes in PG production.

CONCLUSIONS

Tumor necrosis factor-alpha inhibits ovulation in a dose-dependent fashion, and inhibits estradiol and progesterone production without altering PG production in the open bursa rat ovarian perfusion model.