Tumour necrosis factor-alpha receptors are present in the corpus luteum throughout the oestrous cycle and during the early gestation period in pigs

Changes in Porcine Corpus Luteum Proteome Associated with Development, Maintenance, Regression, and Rescue during Estrous Cycle and Early Pregnancy

Corpus luteum (CL), a transitory gland, undergoes rapid growth in a limited time to produce progesterone (P4) followed by its regression. A complex molecular signaling is involved in controlling luteal P4 production. In the present study, 2D gel electrophoresis-based proteomics and in silico functional analysis were used to identify changes in key proteins and pathways in CL along the different stages of the estrous cycle as its development progresses from early (Day 3) to mid-luteal phase (Day 9), effective functioning (Day 12) followed by regression (Day 15) or, in the case of pregnancy, rescue of function (Day 15). A total of 273 proteins were identified by MALDI-MS/MS analysis that showed significant changes in abundances at different stages of CL development or regression and rescue. Functional annotation of differentially abundant proteins suggested enrichment of several important pathways and functions during CL development and function maintenance including cell survival, endocytosis, oxidative stress response, estradiol metabolism, and angiogenesis. On the other hand, differentially abundant proteins during CL regression were associated with decreased steroid synthesis and metabolism and increased apoptosis, necrosis, and infiltration of immune cells. Establishment of pregnancy rescues CL from regression by maintaining the expression of proteins that support steroidogenesis as pathways such as the super-pathway of cholesterol biosynthesis, RhoA signaling, and functions such as fatty acid metabolism and sterol transport were enriched in CL of pregnancy. In this study, some novel proteins were identified along CL development that advances our understanding of CL survival and steroidogenesis.

Regression of corpus luteum in cetaceans: A systematic review

Functional and structural change of corpus luteum through the cascade of several genes in the ovary leads to ovulation and pregnancy. In most mammals, the absence of pregnancy leads to the disintegration of the corpus luteum. In the ovary of cetaceans, the regression of the corpus luteum gets delayed and persists on the surface as scars (corpus albicans). The database on luteolysis of mammals was collected and examined to know the mechanisms involved in the corpus luteum regression of cetaceans. Surprisingly, there existed no data on the concerned topic. Some past findings reported the persistence of ovarian scars through the entire life span, while few reported the regression. Also, those investigations were about the physiology and histology of corpus luteum regression. The pathways and the genes involved in the regression of the cetacean corpus luteum remain unexplored. This review is all about the regression of corpus luteum and recommends gene-based evolutionary studies in the future to resolve the existing theories on ovarian scar persistence in cetaceans.

Progesterone inhibits cytokine/TNF-α production by porcine CL macrophages via the genomic progesterone receptor

In pigs, luteolytic sensitivity to PGF-2α (=LS) is delayed until d 13 of the estrous cycle. While the control of LS is unknown, it is temporally associated with macrophage (MAC; which secretes tumor necrosis factor [TNF]-α) infiltration into the corpora lutea (CL), and previous studies have shown that TNF-α induces LS in porcine luteal cells (LCs) in culture. This study was designed to explore the control of LS by CL macrophage (CL MAC)/TNF-α by progesterone (P4), and to examine the hypothesis that P4 acting via the genomic P4 receptor (PGR) inhibits CL MAC TNF-α and thus plays a key role in regulating LS during the pig estrous cycle. In experiment 1, the effects of LCs on CL MAC cytokine/TNF-α mRNA expression in co-culture were examined (MID cycle; ~d 7-12; no LS); results showed that LC was inhibitory to cytokine/TNF-α. In experiment 2, the effects of P4 or R5020 (PGR-agonist) on CL MAC cytokine/TNF-α mRNA expression were examined (MID cycle; ~d 7-12; no LS); results showed that both P4 and R5020 dose-dependently inhibited TNF-α. In experiment 3, CL MACs were isolated from CL at MID (~d 7-12; no LS) and LATE (~d 13-18; + LS) cycle, and TNF-α/PGR mRNA measured. Results indicated that while TNF-α mRNA was 4.2-fold greater in CL MACs from LATE vs MID cycle, PGR mRNA was 4.5-fold greater in CL MACs from MID vs LATE cycle. These data support our hypothesis and suggest that progesterone, acting via PGR, plays a critical physiological role in the control of TNF-α production by CL MACs and LS during the pig estrous cycle.

Expression of factors associated with apoptosis in the porcine corpus luteum throughout the luteal phase of the estrous cycle and early pregnancy: their possible involvement in acquisition of luteolytic sensitivity

The studies on the acquisition of luteolytic sensitivity have been focused mainly on molecular changes induced in the luteal tissue after treatment with exogenous PGF2α or on physiological changes occurring during the estrous cycle. The comparison of changes leading to the acquisition of luteolytic sensitivity after Day 12 of the estrous cycle and corresponding days of pregnancy has not been investigated in the pig. The present study was undertaken to evaluate (1) apoptosis measured as the proportions of early apoptotic, late apoptotic, and viable cells; (2) expression of factors involved in the extrinsic (TNFA/TNFα, TNFRSF1A/TNFR1, TNFRSF1B/TNFR2, FAS/Fas, and FASLG/FasL) and intrinsic (CASP3/Casp3, TP53/p-53, BAX/Bax, and BCL2/Bcl-2) apoptotic pathways, with two components of the activating protein-1 complex, i.e., FOS/Fos and JUN/Jun and IFNG/IFNγ; and (3) concentrations of luteal and blood plasma progesterone (P4) throughout the luteal phase of the estrous cycle and early pregnancy. Corpora lutea (CL) were collected postmortem on Days 8, 10, 12, and 14 of the estrous cycle and the corresponding days of pregnancy. The luteal tissue was subjected to RNA and/or protein isolation and disaggregation of CL cells followed by flow cytometry analysis aimed to determine apoptotic changes. Luteal and blood plasma P4 concentrations decreased on Day 14 of the estrous cycle versus pregnancy (P < 0.05 and P < 0.001, respectively). A significant increase in the number of early apoptotic cells and a decrease in the number of viable cells were observed on Day 14 of the estrous cycle (P < 0.001 and P < 0.05, respectively). Increase (P < 0.05) of TNFA messenger RNA (mRNA) level coincided with that of IFNG on Day 12 of the estrous cycle but not on the corresponding day of pregnancy. The content of FAS mRNA and protein increased on Day 14 of the estrous cycle versus pregnancy (P < 0.05). The mRNA expression of CASP3, BCL-2 and BAX was unchanged in cyclic and pregnant CL, while level of TP53 increased (P < 0.05) on Day 12 of the estrous cycle versus Day 8. The level of FOS and JUN mRNA increased (P < 0.05) on Day 14 of the estrous cycle versus the remaining days. The level of FOS and JUN mRNA was significantly higher (P < 0.001 and P < 0.05, respectively) on Day 14 of the estrous cycle than that on the corresponding day of pregnancy. In summary, the simultaneous increase of TNFA and IFNG transcript in cyclic CL suggests the crucial role of both cytokines in sensitization of porcine CL to further luteolytic action of PGF2α. The upregulated expression of FAS, FOS, and JUN mRNA in the late luteal phase in cyclic CL can indicate their involvement in structural luteolysis. The increased viability of luteal cells and elevated P4 concentrations in pregnant CL confirm the protective role of luteal P4 against apoptosis.

Expressions of tumor necrosis factor-α, its receptor I, II and receptor-associated factor 2 in the porcine corpus luteum during the estrous cycle and early pregnancy

We examined the gene and protein levels of tumor necrosis factor (TNF)-α, its receptors (types I and II, designated TNF-RI and TNF-RII, respectively), TNF receptor-associated factor 2 (TRAF2) and morphological features in the porcine corpus luteum (CL), on Days 13 and 17 (Day 0 = the last day of estrus) of the estrous cycle or of early pregnancy. Gene expression levels of TNF-α, TNF-RI, TNF-RII and TRAF2 were unaffected by the day or reproductive status. TNF-α concentration was significantly higher in the CL on Day 17 of pregnancy than on Day 13 of pregnancy and on day 17 of the estrous cycle. The TNF-RI protein level was significantly higher in the CL on Days 13 and 17 of pregnancy than those of the estrous cycle, significantly increasing on Day 17 compared with those on Day 13 in pregnancy. In relation to TNF-RII protein levels, although there were no change during pregnancy, there was a tendency (P = 0.0524) to up-regulate as pregnancy proceeded. In estrous cycle, TNF-RII protein levels decreased significantly as luteolysis proceeded. TRAF2 protein level was significantly higher in the CL on Days 13 and 17 of pregnancy than during estrous. There were few apoptotic bodies in the CL between Days 13 and 17 of pregnancy than during esrous. There were few apoptotic bodies in the CL between Days 13 and 17 of pregnancy. The number of apoptotic bodies was much greater than the CL on Day 17 of the estrous than those of pregnancy. Thus, the TNF-α and TNF-RI and TNF-RII pathways including the TRAF2 protein, known to control of cell differentiation, tissue renewal and apoptosis, might participate in maintaining the porcine CL during early pregnancy.

Luteal macrophage conditioned medium affects steroidogenesis in porcine granulosa cells

The purpose of the study was to examine the effect of luteal macrophage conditioned medium (LMCM) on progesterone and estradiol production by cultured granulosa cells. Porcine granulosa cells were cultured for 48 h with or without LMCM in the absence or presence of 100 ng/ml LH, FSH or prolactin. Progesterone and estradiol concentrations were measured by radioimmunoassay. Granulosa cells were analyzed histochemically and immunocytochemically for the activity and presence of Δ5, 3β-hydroxysteroid dehydrogenase (3β-HSD), respectively. LMCM stimulated basal and LH-, FSH- or prolactin-induced progesterone secretion. Similarly, LMCM augmented basal and stimulated activity of 3β-HSD in the examined cells. In contrast, LMCM decreased LH- and prolactin-induced estradiol secretion but increased FSH-induced estradiol secretion. These data demonstrate the clear stimulatory effect of LMCM on granulosal progesterone production. It is concluded that substances secreted by macrophages modulate gonadotropin effect on follicular progesterone secretion in a paracrine manner via 3β-HSD activity.

The effect of Escherichia coli lipopolysaccharide and tumour necrosis factor alpha on ovarian function

PROBLEM

Pelvic inflammatory disease and metritis are important causes of infertility in humans and domestic animals. Uterine infection with Escherichia coli in cattle is associated with reduced ovarian follicle growth and decreased estradiol secretion. We hypothesized that this effect could be mediated by the bacterial lipopolysaccharide (LPS) or cytokines such as tumour necrosis factor alpha (TNFalpha).

METHOD OF STUDY

In vitro, bovine ovarian theca and granulosa cells were treated with LPS or TNFalpha and steroid secretion measured. In vivo, the effect of LPS or TNFalpha intrauterine infusion was determined by ovarian ultrasonography and measurement of hormones in cattle.

RESULTS

Lipopolysaccharide reduced granulosa cell estradiol secretion, whilst TNFalpha decreased theca and granulosa cell androstenedione and estradiol production, respectively. In vivo, fewer animals ovulated following intrauterine infusion with LPS or TNFalpha.

CONCLUSION

Lipopolysaccharide and TNFalpha suppress ovarian cell function, supporting the concept that pelvic inflammatory disease and metritis are detrimental for bovine ovarian health.

Influence of tumor necrosis factor-α on estradiol, progesterone, insulin-like growth factor-II, and insulin-like growth factor binding protein-1, 2, and 3 in cultured human luteinized granulosa cells

OBJECTIVE

The objective was to investigate the influence of tumor necrosis factor (TNF)-alpha on estradiol, progesterone, insulin-like growth factor (IGF)-II, and insulin-like growth factor binding protein (IGFBP)-1, 2, and 3 in cultured human luteinized granulosa cells.

STUDY DESIGN

Human luteinized granulosa cells were obtained from follicular fluid by transvaginal oocyte aspiration from infertile patients undergoing controlled ovarian hyperstimulation (COH) for in vitro fertilization (IVF). The cells were cultured for 72 h with TNF-alpha at concentrations of 1.0, 10.0, and 100.0 ng/ml. The cells not treated with TNF-alpha served as controls. Radioimmunoassay (RIA) and reverse transcription-polymerase chain reaction (RT-PCR) were used to examine the influence of TNF-alpha on estradiol, progesterone, IGF-II, and IGFBP-1, 2, and 3. Results were analyzed using the Kolmogorov-Smirnov test and analysis of variance (ANOVA). Statistical significance was defined as p<0.05.

RESULTS

The concentrations of progesterone seemed to decrease as the concentrations of TNF-alpha increased and the concentration of progesterone in the 100.0 ng/ml TNF-alpha group was significantly lower than that in the control and other TNF-alpha groups. The expressions of IGF-II mRNA in the 10.0 and 100.0 ng/ml TNF-alpha groups were significantly lower than that in the control group. The expressions of IGFBP-2 mRNA seemed to be decreased in the 10.0 and 100.0 ng/ml TNF-alpha groups compared with that in the control group, but there were no statistical significances.

CONCLUSION

TNF-alpha may play a role as a regulator of human ovarian physiology by modulating the IGF systems in luteinized granulosa cells.

Prostaglandins and reproduction in female farm animals

Prostaglandins impact on ovarian, uterine, placental, and pituitary function to regulate reproduction in female livestock. They play important roles in ovulation, luteal function, maternal recognition of pregnancy, implantation, maintenance of gestation, microbial-induced abortion, parturition, postpartum uterine and ovarian infections, and resumption of postpartum ovarian cyclicity. Prostaglandins have both positive and negative effects on reproduction; they are used to synchronize oestrus, terminate pseudopregnancy in mares, induce parturition, and treat retained placenta, luteinized cysts, pyometra, and chronic endometritis. Improved therapeutic uses for prostaglandins will be developed when we understand better their involvement in implantation, maintenance of luteal function, and establishment and maintenance of pregnancy.

Tumor necrosis factor-alpha (TNF alpha) inhibits progesterone and estradiol-17beta production from cultured granulosa cells: presence of TNFalpha receptors in bovine granulosa and theca cells

The aim of this study was to investigate whether functional tumor necrosis factor-alpha (TNFalpha) receptors are present in the granulosa cells and the cells of theca interna (theca cells), obtained from bovine follicles classified into one of three groups. Each group was defined as either small vesicular ovarian follicles (small follicles; 3-5 mm in diameter), preovulatory mature ovarian follicles (preovulatory follicles) or atretic follicles (12-18 mm) according to gross examination of the corpus luteum in the epsilateral or contralateral ovary and the uterus (size, color, consistency and mucus), and the ratio of progesterone (P(4)) and estradiol-17beta (E(2)) concentrations in follicular fluid. A Scatchard analysis showed the presence of a high-affinity binding site on both granulosa and theca cells from all follicles examined (dissociation constant: 4.7 +/- 0.15 to 6.9 +/- 1.40 nM). Moreover, TNFalpha receptor concentrations in granulosa and theca cells obtained from atretic follicles were significantly higher than those in the cells from preovulatory follicles (P<0.05). Exposure of cultured granulosa cells from small antral follicles to recombinant human TNFalpha (rhTNFalpha; 0.06-6 nM) inhibited E(2) secretion in a dose-dependent fashion (P<0.01), but did not affect P(4) secretion. In addition, rhTNFalpha inhibited follicle stimulating hormone-, forskolin- or dibutylyl cyclic AMP-induced P(4) and E(2) secretion by the cells (P<0.01). These results indicate the presence of functional TNFalpha receptors in bovine granulosa and theca cells in small, preovulatory and atretic follicles, and suggest that TNFalpha plays a role in regulating their secretory function.

Possible actions of tumor necrosis factor-alpha in ovarian function

Tumor necrosis factor-alpha (TNFalpha) is a multifunctional cytokine that was first described as a tumoricidal factor produced by activated macrophages. Extensive research over the last two decades has suggested that TNFalpha has physiologically diverse actions in ovarian function in a variety of species. TNFalpha and its specific receptors are present in the ovaries of many species. Furthermore, TNFalpha plays multiple and probably important roles in corpus luteum (CL) function as well as ovarian cell function throughout the estrous cycle. This review focuses on recent studies documenting TNFalpha in ovarian follicles and CL in several mammals. In addition, possible roles of TNFalpha in ovarian function throughout the estrous cycle and in the gestation period are discussed.

Local interaction of prostaglandin F2α with endothelin-1 and tumor necrosis factor-α on the release of progesterone and oxytocin in ovine corpora lutea in vivo: a possible implication for a luteolytic cascade

Endothelin-1 (ET-1) and tumor necrosis factor-α (TNFα) participate in the cascade of luteolysis. Thus, in the present study the interactions of ET-1 and TNFα with prostaglandin F2α (PGF2α) on the release of progesterone and oxytocin (OT) within the corpus luteum (CL) were investigated. A microdialysis system (MDS) was surgically implanted in ovine CL (one MDS line/CL; 5–10 lines/ewe) formed after super-ovulation. A 4-h perfusion with PGF2α (0.01–1 μmol l −1) induced no clear effect on progesterone release, but acutely stimulated OT release in a dose-dependent manner. A perfusion of PGF2α (1 μmol l −1) increased ET-1 release over a period of 12 h. Two perfusions of ET-1 (0.1 μmol l−1) or a perfusion of ET-1 followed by TNFα (200 ng ml−1) decreased progesterone release (56–64% at 36–48 h). When the CL were pre-perfused with PGF2α (1 μmol l−1), two consecutive perfusions of ET-1 decreased progesterone release more rapidly. Similarly, a pre-perfusion with PGF2α followed by consecutive perfusions of ET-1 and then TNFα rapidly decreased progesterone release, with the inhibition most pronounced (35%) at 36–48 h. The simultaneous infusion of ET-1 with PGF2α induced a rapid decrease in progesterone release (36% at 36–48 h). In a further study, the possible second messenger systems involved in PGF2α action on the release of progesterone, OT and ET-1 were investigated. A perfusion with 12-O-tetradecanoyl-phorbol-13-acetate (TPA; 10 μmol l−1), A23187 (10 μmol l−1), or PGF2α + A23187 increased progesterone release during infusion, but decreased it after perfusion. All treatments induced a massive release of OT during infusion, and increased ET-1 release after infusion. These results show that ET-1 is capable of suppressing progesterone release in the PGF2α-primed ovine CL in vivo and thus ET-1 works as a local luteolysin together with PGF2α during the process of functional luteolysis. During structural luteolysis, TNFα may interact with PGF2α and ET-1 to cause a rapid drop in progesterone release and accelerate the process of luteolysis. This result supports the contention that ET-1 and TNFα interact with PGF2α as local luteolytic mediators in the ewe as previously suggested.

Multiple roles of TNF super family members in corpus luteum function

The main function of the corpus luteum (CL) is the production of progesterone. Adequate luteal progesterone is crucial for determining the physiological duration of the estrous cycle and for achieving a successful pregnancy. The CL is regulated not only by hypophyseal gonadotropin, but also by a number of cytokines that are locally produced. Tumor necrosis factor-alpha (TNF) and its specific receptors (TNFR) are present in the CL of many species. TNF plays multiple and likely important roles in CL function throughout the estrous cycle. TNF appears to have luteotropic and luteolytic roles in the CLs. In contrast, Fas ligand (Fas L), another member of TNF super family (TNF-SF), is primarily recognized for its apoptotic actions. Presumably, Fas L binds its cognate receptor (Fas) to induce structural luteolysis. This review is designed to focus on recent studies documenting the expression of TNF and Fas L, their receptors, and intracellular signaling mechanisms in the CL.