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Articles |
by Cultured Bovine Endometrial Cells in Response to Tumor Necrosis Factor : Cell Type Specificity and Intracellular Mechanisms1
a Laboratory of Reproductive Endocrinology, Faculty of Agriculture, Okayama University, Okayama 700–8530, Japan
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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(TNF) has been shown to be a potent stimulator of prostaglandin (PG) F2 secretion in the bovine endometrium. The aims of the present study were to determine the cell types in the endometrium (epithelial or stromal cells) responsible for the secretion of PGF2 in response to TNF, and the intracellular mechanisms of TNF action. Cultured bovine epithelial and stromal cells were exposed to TNF (0.006–6 nM) or oxytocin (100 nM) for 4 h. TNF resulted in a dose-dependent increase of PGF2 production in the stromal cells (P < 0.001) but not in the epithelial cells. On the other hand, oxytocin stimulated PGF2 output in the epithelial cells but not in the stromal cells. When the stromal cells were incubated for 24 h with TNF and inhibitors of phospholipase (PL) C or PLA2, only PLA2 inhibitor completely stopped the actions of TNF (P < 0.001). When the stromal cells were exposed to TNF and arachidonic acid, the action of TNF was augmented (P < 0.001). When the stromal cells were incubated for 24 h with a nitric oxide (NO) donor (S-NAP), S-NAP stimulated the PGF2 production dose-dependently. Although an NO synthase (NOS) inhibitor (L-NAME) reduced TNF-stimulated PGF2 production, an inhibitor of phosphodiesterase augmented the actions of TNF and S-NAP (P < 0.05). The overall results indicate that the target of TNF for stimulation of PGF2 production in cattle is the endometrial stromal cells, and that the actions of TNF are mediated via the activation of PLA2 and arachidonic acid conversion. Moreover, TNF may exert a stimulatory effect on PGF2 production via the induction of NOS and the subsequent NO-cGMP formation.
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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from the uterus in the late luteal phase induces luteolysis in many species including cattle [1]. Silvia et al. [2] have proposed that, in nonpregnant ruminants, this pulsatile PGF2 secretion is generated by a positive feedback loop between uterine PGF2 and ovarian oxytocin (OT). However, the role of luteal OT in these processes is still controversial in cattle [3, 4]. Therefore, we hypothesize that the bovine uterus possesses endogenous mechanisms for initiation of the luteolytic PGF2 secretion that are independent of external signals such as OT.
Recently, we found that tumor necrosis factor (TNF) stimulates PGF2 output from bovine endometrial tissue through specific binding sites [5]. The effects of TNF on PGF2 output were observed not only at the follicular phase but also at the late luteal phase. In contrast to TNF, OT stimulated endometrial PGF2 secretion during the follicular phase but not during the late luteal phase. These findings suggest that TNF of a uterine and/or ovarian origin [6, 7] is a factor in initiating luteolysis in cattle [5]. In addition, the existence of specific binding sites of TNF in the bovine endometrium throughout the estrous cycle [5] suggests that TNF plays one or more roles in the bovine uterus, including the regulation of PGF2 production. In rodents and humans, TNF has been implicated in the control of uterine cell growth, differentiation, and function throughout the estrous cycle and pregnancy [8].
The intracellular mechanisms of TNF that may act on PGF2 output from the bovine endometrium are not understood. In bovine endothelial cells [9] and luteal cells [10], TNF appears to require the stimulation of phospholipase (PL) and/or the metabolism of arachidonic acid (AA) for the production of PGF2. Another pathway of TNF action on various cells is the induction of nitric oxide (NO) synthase (NOS) [11]. Activation of NOS resulted in generation of NO, which in turn led to the formation of cGMP [12, 13]. NO synthesized by NOS is involved in the regulation of several biological functions in the cyclic and pregnant uterus in human and rodent species [14–17].
In the present study, we attempted to determine which cell types are responsible for the secretion of PGF2 in response to TNF. We also attempted to determine whether TNF can act on cultured bovine endometrial cells via an induction of PLA2 and/or NOS with subsequent stimulation of NO-cGMP formation.
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MATERIALS AND METHODS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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Uteri of Holstein cows were obtained from a local abattoir within 30 min after exsanguination and were transported on ice to the laboratory within 1–1.5 h. The stages of the estrous cycle were determined by macroscopic observation of the ovary as described previously [18]. In this study, uteri of the early estrous cycle (Days 2–5) were used. Epithelial and stromal cells from the bovine endometrium were separated using a modification of procedures described previously [19, 20]. The horn ipsilateral to the corpus luteum was used for culture. A polyvinyl catheter was inserted into the oviduct, and the end of the horn near the corpus uteri was tied shut in order to retain a collagenase solution for solubilizing the epithelial cells as described below. The uterine lumen was washed 3 times with 30–50 ml of sterile Ca2+- and Mg2+-free Hanks' balanced salt solution (HBSS) supplemented with 100 IU/ml penicillin and 100 µg/ml streptomycin and containing 0.1% BSA (Boehringer Mannheim GmbH, Mannheim, Germany; #735078). Thirty-fifty milliliters of enzyme solution (sterile HBSS containing 0.05% collagenase I [Sigma Chemical Co., St. Louis, MO; #C-0130], 0.005% deoxyribonuclease I [Sigma; #D-5025], and 0.1% BSA) was then infused into the uterine lumen through the catheter. Epithelial cells were isolated by incubation twice at 37°C for 45 min and 30 min with gentle shaking. The cell suspension obtained from the first and second digestions was filtered through metal mesh (100 µm and 80 µm) to remove undissociated tissue fragments. The filtrate was washed 3 times by centrifugation (10 min at 100 x g) with Dulbecco's modified Eagle's medium (DMEM; Sigma; #D-1152) supplemented with antibiotics and 0.1% BSA. After the washes, the cells were counted with a hemocytometer. The cell viability was higher than 95% as assessed by 0.5% trypan blue dye exclusion.
After collection of the epithelial cells, the uterine lumen was washed with sterile HBSS supplemented with antibiotics and 0.1% BSA. The horn was then cut transversely with scissors into several segments, which were slit to expose the endometrial surface. Intercaruncular endometrial strips were dissected from the myometrial layer with a scalpel and washed once in 50 ml of sterile HBSS containing antibiotics. The endometrial strips were then minced into small pieces (1 mm3). The minced tissues (approximately 5 g) were digested in 50 ml of the above-described enzyme solution. After stirring for 60 min, dissociated cells were filtered, washed, and counted as described above. The cell viability was higher than 85%. The cells obtained consisted of stromal cells and only a few fibroblasts, erythrocytes, and glandular epithelial cells.
Culture of Endometrial Cells
The final pellet of both of the stromal and epithelial cells was resuspended in culture medium (DMEM/Ham's F-12; 1:1 [v:v]; Sigma, #D-8900) supplemented with 10% calf serum (Sigma; #C-6278) and 20 mg/ml gentamicin. The cells of each cell type were separately seeded at a density of 1 x 105 viable cells/ml in 48-well plates (Costar, Cambridge, MA) and cultured at 37.5°C in a humidified atmosphere of 5% CO2, 95% air. To purify the stromal preparation, the medium was changed 12 h after plating, at which time selective attachment of stromal cells had occurred. Alternatively, since the epithelial cells attached 24–48 h after plating, the medium in the epithelial cell culture was changed 48 h after plating. The medium was changed every 2 days until confluence was reached. When the cells were confluent (6–7 days after the start of the culture), the medium was then replaced with fresh DMEM/Ham's F-12 supplemented with 0.1% BSA, 5 ng/ml sodium selenite, 0.5 mM ascorbic acid, 5 µg/ml transferrin, and 20 mg/ml gentamicin. The cells were then exposed to various stimulants for the following experiments.
Experiment 1. To determine the dose- and time-dependent effects of TNF on PGF2 production in the bovine epithelial and stromal cells, the cells were exposed to TNF (Dainippon Pharmaceutical Co. Ltd., Osaka, Japan; 0.006–6 nM) or OT (Teikoku Hormone MFG Co., Tokyo, Japan; 100 nM) for 2–72 h.
Experiment 2. To determine the intracellular mechanisms of TNF actions on the bovine stromal cells, the cells were exposed to a PLA2 inhibitor (anthranilic acid, ACA; Calbiochem, San Diego, CA; #104550; 1 µM), AA (Sigma; #A-9548; 10 µM) or a PLC inhibitor (U-73122, Calbiochem; #662035; 1 µM) with TNF for 24 h.
Experiment 3. To determine the effects of an NO donor and NOS inhibitors on PGF2 production in the bovine stromal cells, the cells were incubated for 24 h with two NOS inhibitors: NG-nitro-L-arginine methyl ester dihydrochloride (L-NAME; RBI, Natick, MA; #70–0011–61; 100 µM) or NG-nitro-L-arginine (L-NOARG, RBI; #70–0011–60; 100 µM) with an NO donor, S-nitroso-N-acetylpenicillamine (S-NAP, RBI; #70–1301–52; 1–1000 µM). Moreover, to evaluate whether NO-stimulated PG secretion is mediated by the formation of cGMP, the cells were exposed to an inhibitor of phosphodiesterase, 3-isobutyl-1-methylxanthine (IBMX; Calbiochem, #410957; 10 µM) with S-NAP (10 µM).
Experiment 4. To determine whether TNF-stimulated PGF2 production is dependent on NO-cGMP formation, the cells were exposed to L-NAME (100 µM) and L-NOARG (100 µM) or IBMX (10 µM) with TNF (0.06 nM) for 24 h.
At the end of each experiment, the culture media were stored at -30°C until assay for PGF2. The DNA content was estimated by a spectrophotometric method as described by Labarca and Paigen [21]. DNA contents were used to standardize the results.
During the characterization of the endometrial cells in vitro, we estimated stromal cell cultures to be 98% pure and epithelial cell cultures to be 95% pure. Contamination of the stromal and epithelial cell cultures (with epithelial cells and stromal cells, respectively) was evaluated by the method of Asselin et al. [22], in which it is assumed that only epithelial cells respond to OT [19, 22] and only stromal cells respond to TNF (our present observation).
Hormone Determination
Concentrations of PGF2 in the culture media were determined directly with an enzyme immunoassay as described previously [23]. The PGF2 standard curve ranged from 15.6 pg/ml to 4000 pg/ml, and the median effective dose (ED50) of the assay was 250 pg/ml. The intra- and interassay coefficients of variation were 7.9% (n = 10) and 10.4% (n = 10), respectively.
Statistical Analysis
The data are shown as the mean ± SEM of values obtained in 3–4 separate experiments, each performed in triplicate. The statistical significance of differences between controls and treated groups was assessed by one-way ANOVA followed by Bonferroni's multiple-comparison test (GraphPad PRISM; GraphPad Software, Inc., San Diego, CA).
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RESULTS |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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on PGF2 Production in Epithelial and Stromal Cells
Figure 1 shows PGF2 production by cultured bovine endometrial cells in response to TNF or OT for 4 h. Although TNF stimulated PGF2 production by stromal cells in a dose-dependent manner (P < 0.05), a stimulatory effect was not observed in epithelial cells. In contrast to TNF, OT stimulated PGF2 production in epithelial cells (600% of the basal secretion, P < 0.001) but not in stromal cells. Therefore, only stromal cells were used to characterize the mechanisms of TNF-stimulated PGF2 production in the following studies.
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Time-Dependent Effects of TNF on PGF2 Production in Stromal Cells
The stimulatory effects of TNF were observed at every incubation time examined (P < 0.05; Table 1). The highest stimulation was shown during 4–24 h after stimulation (P < 0.001). Twenty-four hours after stimulation, the stimulatory effects of TNF on the PGF2 production decreased (P < 0.05).
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Effects of PL Inhibitors and AA on TNF-Induced PGF2 Production in Stromal Cells
Basal production of PGF2 was not influenced by ACA in stromal cells (P > 0.05; Fig. 2). Although U-73122 showed no significant effect on basal and TNF-induced PGF2 production, ACA completely stopped the actions of TNF (P < 0.001; Fig. 2). AA increased basal PGF2 production in stromal cells (P < 0.001; Fig. 2). Moreover, the stimulatory effect of TNF on PGF2 production was significantly augmented by AA (P < 0.001).
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Effects of NOS Inhibitors and NO Donor on PGF2 Production in Stromal Cells
S-NAP stimulated PGF2 production in a dose-dependent manner (P < 0.05; Fig. 3). The highest stimulation was observed at 100 µM S-NAP (P < 0.001). Treatment with IBMX augmented the effect of S-NAP on PGF2 production (P < 0.01).
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Effects of Inhibitors of NOS and Phosphodiesterase on TNF-Induced PGF2 Production in Stromal Cells
When stromal cells were exposed to IBMX for 24 h, the stimulatory effect of TNF on PGF2 production was increased (P < 0.001; Fig. 4). Although L-NAME reduced TNF-stimulated PGF2 production, L-NOARG did not affect it (P > 0.05; Fig. 4).
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DISCUSSION |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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stimulates PGF2 production in the stromal cells, but not in the epithelial cells, of the bovine endometrium. It has been well demonstrated that epithelial cells principally produce PGF2 and stromal cells produce PGE2 [22, 24]. Our data showed that basal PGF2 production in stromal cells was 10 times lower than PGF2 production in epithelial cells. However, since the endometrium apparently consists of many more stromal cells than epithelial cells, the TNF-stimulated PGF2 from stromal cells could be sufficient to play a role in the initiation of luteolysis. Alternatively, TNF-induced PGF2 may stimulate PGF2 production in both stromal and epithelial cells as a paracrine and autocrine regulator, as has been suggested to occur in the ovine corpus luteum at luteolysis [25]. Consistent with this auto-amplification cascade, there are reports that PGF2 treatment acutely increased PGF2 output from the bovine [26] and ovine [27] uterus. Therefore, our present data along with previous findings suggest that TNF-induced PGF2 from the stromal cells can initiate luteolysis in cattle. Furthermore, TNF-induced PGF2 from the stromal cells may switch on the positive feedback loop between epithelial PGF2 and luteal OT that completes luteolysis in cattle.
In many species, it has been demonstrated that there are two types of TNF receptors (TNF-RI and TNF-RII), and that these receptors have different intracellular signaling pathways [8, 28, 29]. Moreover, it has been well demonstrated that a TNF/TNF-RI complex activates PLA2 [9, 30] and the PLC-protein kinase C pathway [31]. In the present study, ACA (an inhibitor of PLA2) completely stopped the actions of TNF (Fig. 2), whereas U-73122 (an inhibitor of PLC) did not significantly inhibit TNF-induced PGF2 production. It is generally accepted that PLA2 stimulates intracellular AA accumulation. Therefore, the failure of TNF to stimulate PGF2 production in stromal cells treated with ACA might also have been due to a lower accumulation of AA, which is a precursor of PGF2. This supposition is supported by our findings that exogenous AA strongly augmented TNF-stimulated PGF2 production (Fig. 2), suggesting that TNF may also affect the metabolism of AA. In view of the above findings, we postulate that TNF influences the secretory function of bovine stromal cells through the activation of PLA2 via TNF-RI.
A common pathway for the action of TNF in cells is the induction of NOS, resulting in the generation of NO and the subsequent production of cGMP [11, 12]. It has been assumed that NO directly influences the activity of heme-containing enzymes such as cyclooxygenase [32] and modulates PGF2 production in reproductive organs, including the uterus [33–35]. Our present results provide some evidence that the TNF-stimulated PGF2 production is in part mediated by induction of NOS activity and the subsequent NO-cGMP generation. The present study is the first to show that NO derived from S-NAP (an NO donor) stimulated production of PGF2 in cultured bovine stromal cells (Fig. 3). Secondly, both TNF-induced and S-NAP-stimulated PGF2 production was augmented by the simultaneous exposure to IBMX (a phosphodiesterase inhibitor), indicating that the accumulation of cGMP resulted in additional PGF2 production (Figs. 3 and 4). Finally, we demonstrated that the increase of PGF2 production after stimulation with TNF was reduced by the simultaneous exposure to L-NAME (a competitive inhibitor of arginine binding to NOS).
It has been well known that there are three different isoforms of NOS: one inducible isoform and two constitutively expressed isoforms. One of them, the constitutive-neuronal isoform, has been identified in bovine uterine nerves [36]. Although in the rat and human uterus NO is produced by the other two isoforms of NOS, the constitutive-endothelial and inducible isoforms [15, 37], it is not known whether those isoforms exist and act in the bovine uterus. However, whereas L-NAME does not discriminate between different NOS isoforms and inhibits the inducible and constitutive isoforms of NOS, L-NOARG has been found to be a potent inhibitor of the constitutive isoforms of NOS [38, 39]. In the present study, L-NAME inhibited TNF-induced PGF2 production, but L-NOARG did not affect it (Fig. 4). Thus, we assume that TNF predominantly induces inducible isoforms of NOS as reported previously in other tissues [40, 41].
The overall results indicate that 1) both types of endometrial cells (epithelial and stromal cells) possess distinct physiological properties in order to respond to TNF and OT, 2) the target of TNF for stimulating PGF2 production is the stromal cells, 3) the stimulatory effect of TNF on PGF2 production is mediated via the activation of PLA2 and AA conversion, and 4) TNF may exert its stimulatory effect on PGF2 production via the induction of NOS and subsequent cGMP formation. The present and previous results [5, 26] lead us to hypothesize that TNF directly induces the output of PGF2 from the stromal cells, and that the TNF-induced PGF2 from the stromal cells is the first component of an auto-amplification cascade within the bovine endometrium and switches on the positive feedback loop between the epithelial PGF2 and the luteal OT to complete luteolysis in cattle.
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ACKNOWLEDGMENTS |
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, the Dainippon Pharmaceutical Co., Ltd. (Osaka, Japan) for recombinant human TNF, and the Teikoku Hormone MFG Co. (Tokyo, Japan) for synthetic OT. |
FOOTNOTES |
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1 This research was supported by Grants-in-Aid for Scientific Research (No. 11556054 and 11460129) from the Ministry of Education, Science, Sports and Culture of Japan. D.J.S. was a postdoctoral fellow supported by the Japan Society for the Promotion of Science (JSPS). Y.M. is a research fellow of JSPS (No. 07809). 
2 Correspondence. FAX: 81 86 251 8388; kokuda{at}cc.okayama-u.ac.jp
3 Current address: Institute of Animal Reproduction and Food Research, Polish Academy of Sciences, 10–718 Olsztyn-Kortowo, Poland.
Accepted: October 26, 1999.
Received: July 20, 1999.
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REFERENCES |
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TOPABSTRACTINTRODUCTIONMATERIALS AND METHODSRESULTSDISCUSSIONREFERENCES |
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during luteolysis in ruminants. Biol Reprod 1991; 45:655–663.[Abstract] a trigger for the initiation of prostaglandin F2 release at luteolysis in cattle? Biol Reprod 2000; 62:1109–1115. gene in the female reproductive tract. Reprod Fertil Dev 1993; 5:141–153.[CrossRef][Medline] and progesterone within the bovine corpus luteum sampled by continuous-flow microdialysis during luteolysis in vivo. Biol Reprod 1995; 53:847–854.[Abstract]-stimulated prostaglandin production in cultured bovine luteal cells. Prostaglandins 1996; 52:361–373.[CrossRef][Medline] and E2 and response to oxytocin in cultured epithelial and stromal cells of the bovine endometrium. Biol Reprod 1996; 54:371–379.[Abstract] production by oxytocin and platelet-activating factor in bovine endometrial cells. J Reprod Fertil 1995; 103:239–247. induces expression of prostaglandin G/H synthase-2 in the ovine corpus luteum: a potential positive feedback loop during luteolysis. Biol Reprod 1997; 57:1016–1022.[Abstract] treatment in cattle. Theriogenology 1997; 48:733–742. stimulates utero-ovarian release of prostaglandin F2 in sheep: a possible component of the luteolytic mechanism of action of exogenous prostaglandin F2. Domest Anim Endocrinol 1996; 13:383–398.[CrossRef][Medline] induced clustering of ovarian theca-interstitial cells. Mol Cell Endocrinol 1993; 97:37–49.[CrossRef][Medline] production and the nitridergic system during embryonic implantation in the rat. Prostaglandins 1996; 51:363–376.[CrossRef][Medline] (TNF). Is this pathway implicated in the TNF-induced inhibition of luteinizing hormone-stimulated prorennin production? Biol Reprod 1997; 57:700–706.[Abstract]This article has been cited by other articles:
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|
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|
|
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|
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