Recombinant PAI-1 therapy restores myoendothelial junctions and erectile function in PAI-1-deficient mice

Myoendothelial junctions are specialised projections of cell : cell contact through the internal elastic lamina between endothelial cells and vascular smooth muscle cells. These junctions allow for endothelial cells and vascular smooth muscle cells to make direct membrane apposition and are involved in cell : cell communication. In this study, we evaluated for the presence of myoendothelial junctions in murine corporal tissue and used plasminogen activator inhibitor (PAI)-1-deficient mice, which lack myoendothelial junctions, to determine whether myoendothelial junctions affect erectile function. Transmission electron microscopy demonstrated the presence of myoendothelial junctions in the corporal tissue of wild-type mice and confirmed the decreased junction numbers in the tissue of PAI-1(-/-) mice. A potential role for myoendothelial junctions in tumescence was established; in that, PAI-1(-/-) mice demonstrated a significantly longer time to achieve maximal intracavernous pressure. Treatment of PAI-1(-/-) mice with recombinant PAI-1 restored the number of myoendothelial junctions in the corporal tissue and also induced a significant decrease in time to maximal corporal pressures. Myoendothelial junctions were similarly identified in the human corporal tissue. These results suggest a critical role for myoendothelial junctions in erectile pathophysiology and therapies aimed at restoring myoendothelial junction numbers in the corporal tissue may provide a novel therapy for erectile dysfunction.

Essential role of neutrophils in germ cell-specific apoptosis following ischemia/reperfusion injury of the mouse testis

This study investigates the role of neutrophils in ischemia-induced aspermatogenesis in the mouse. Previous studies in the rat have demonstrated that ischemia-inducing testicular torsion followed by torsion repair and reperfusion resulted in germ cell-specific apoptosis. This was correlated with an increase in neutrophil adhesion to subtunical venules, an increase in reactive oxygen species, and increased expression of several apoptosis-associated molecules. In the present investigation, wild-type C57BL/6 mice were subjected to various degrees and duration of testicular torsion. A torsion of 720 degrees for 2 h caused disruption of the seminiferous epithelium and significantly reduced testis weight and daily sperm production. An immunohistochemical method specific for apoptotic nuclei indicated that these effects were due to germ cell-specific apoptosis. An increase in myeloperoxidase (MPO) activity and an increase in the number of neutrophils adhering to testicular subtunical venules after torsion repair/reperfusion demonstrated an increase in neutrophil recruitment to the testis. In contrast, E-selectin knockout mice and wild-type mice rendered neutropenic showed a significant decrease in neutrophil recruitment as evidenced by MPO activity and microscopic examination of subtunical venules. Importantly, germ cell-specific apoptosis was also reduced. Thus, germ cell-specific apoptosis is observed after ischemia/reperfusion of the murine testis, and this apoptosis is directly linked to the recruitment of neutrophils to subtunical venules. Endothelial cell adhesion molecules, particularly E-selectin, play an important role in mediating this pathology.

Molecular pathway of germ cell apoptosis following ischemia/reperfusion of the rat testis

The present study investigates the molecular apoptotic pathway in germ cells following acute ischemia of the rat testis. Rats were subjected to ischemia-inducing torsion and testes were harvested after reperfusion. Apoptotic cells were identified with an antibody to single-stranded DNA. Seminiferous tubule RNA was examined by RNase protection assay or by reverse transcriptase-polymerase chain reaction (RT-PCR) for the presence and regulation of apoptotic molecules. Proteins from seminiferous tubules were used for Western blot analysis of cytochrome c. Germ cell apoptosis was maximal at 24 h after repair of torsion. Germ cells in stages II-III of the seminiferous epithelium cycle were the predominant early responders. The RNase protection assays revealed that Bcl-X(L) was the prominent mRNA species. Caspases 1, 2, 3, and Bax mRNA were consistently upregulated; however, the time of upregulation after torsion was variable. The Bcl-X(L) and Bcl-X(S) mRNAs were less consistently upregulated and there was no evidence for upregulation of Fas or Bcl-2. Fas ligand (FasL) was not detected by RNase protection assay, but RT-PCR revealed a significant increase in FasL expression 4 h after the repair of torsion. Western blot analysis for cytochrome c release demonstrated a significant increase 4 h after the repair of torsion. Results suggest that germ cell apoptosis following ischemia/reperfusion of the rat testis is initiated through the mitochondria-associated molecule Bax as well as Fas-FasL interactions.

Fluctuations in rat testicular interstitial oxygen tensions are linked to testicular vasomotion: persistence after repair of torsion

Testicular microvascular blood flow is known to exhibit vasomotion, which has been shown to be significantly altered in the short term following the repair of testicular torsion. This loss of vasomotion may ultimately be responsible for the loss of spermatogenesis observed after testicular torsion in rats. In the present study, testicular vasomotion and interstitial oxygen tensions were simultaneously measured prior to, during, and at various time points after repair of testicular torsion in the rat. Testicular torsion was induced by a 720 degrees rotation of the testis for 1 h. Laser-Doppler flowmetry and an oxygen electrode were used to simultaneously measure vasomotion and interstitial oxygen tensions (PO(2)), respectively. Pretorsion control testes had a mean blood flow of 16.3 +/- 1.3 perfusion units (PU) and displayed vasomotion with a cycle frequency of 12 +/- 0.2 cycles per minute and a mean amplitude of 4.2 +/- 0.3 PU. Mean testicular interstitial PO(2) was 12.5 +/- 2.6 mm Hg, which displayed a cyclical variation of 11.9 +/- 0.4 cycles per minute with a mean amplitude of 2.8 +/- 0.8 mm Hg. During the torsion period, both mean blood flow and interstitial PO(2) decreased to approximately zero. Upon detorsion, mean microvascular blood flow and mean interstitial PO(2) values returned to values that were not significantly different from pretorsion values within 30 min; however, vasomotion and PO(2) cycling did not return, even after 24 h. It was 7 days after the repair of torsion before a regular pattern of vasomotion and PO(2) cycling returned. These results demonstrate for the first time a correlation between testicular vasomotion and interstitial PO(2) cycling, and this correlation persists after the repair of testicular torsion.

Dithiolane analogs of lignans inhibit interferon-gamma and lipopolysaccharide-induced nitric oxide production in macrophages

AIM

To investigate the effect of a group of novel synthetic dithiolane analogs of lignans and a well characterized platelet-activating factor (PAF) receptor antagonist, L659,989 on PAF-receptor binding, IFN-gamma- and lipopolysaccharide (LPS)-induced NO production, and steady-state inducible nitric-oxide synthase (iNOS) mRNA expression.

METHODS

PAF-receptor binding study was performed by displacement of 3H-PAF from rabbit platelet membrane; NO production was quantitated by measuring the NO oxidation product, nitrite, in conditioned culture medium; expression of iNOS mRNA was assessed by Northern blot analysis.

RESULTS

The dithiolane analogs inhibited the production of NO, decreased iNOS mRNA expression and antagonized PAF-receptor binding. L659,989 had no effect on NO production and iNOS mRNA expression. Among the compounds tested, there was no simple correlation between their PAF-receptor antagonistic and iNOS inhibitory activities.

CONCLUSION

The dithiolane analogs are a new synthetic chemical class of iNOS expression regulators with dual biologic functions: inhibiting iNOS induction and blocking PAF-receptor.

Autocrine-paracrine regulation of human trophoblast invasiveness by insulin-like growth factor (IGF)-II and IGF-binding protein (IGFBP)-1

Trophoblast growth and invasion of the uterus are tightly regulated by locally produced factors. Since insulin-like growth factor (IGF)-II is produced by the invasive human extravillous trophoblast (EVT) cells and IGF-binding protein (IGFBP)-1 by the decidual cells in situ that are in proximity to each other, we examined the possible influence of these molecules on proliferation, migration, and invasiveness of first-trimester EVT cells in culture. These EVT cell functions were respectively measured by 3H-TdR uptake, in vitro migration, and invasion assays. Secretion of invasion-associated enzymes was assessed by zymography, and IGF-binding moieties on the EVT cell were examined by affinity cross-linking. Proliferation of serum-starved EVT cells was stimulated by addition of serum but unaffected by a wide range of IGF-I, IGF-II, and IGFBP-1 concentrations. IGF-II and IGFBP-1 or their combination stimulated EVT cell invasiveness and migration, when assays were conducted in serum-reduced media. Affinity cross-linking studies failed to detect the type 1 IGF receptor, although several IGF-II-specific and IGF-II-preferring binding molecules including type 2 IGF receptor were identified on the EVT cell surface. IGF-II enhancement of invasion was unaffected in the presence of IGF-1 receptor-blocking antibody and IGF-1 failed to influence EVT cell invasion, indicating that type 1 IGF receptor was not responsible for the IGF-II effects. Secretion of gelatinases or plasminogen activators was unaltered by IGF-II or IGFBP-1. We conclude that trophoblast-derived IGF-II and decidua-derived IGFBP-1 provide autocrine/paracrine enhancement of trophoblast invasiveness largely by stimulating migration, an essential step in invasion.

Effects of colony stimulating factor-1 on human extravillous trophoblast growth and invasion

Colony stimulating factor (CSF)-1 has been localized in a variety of tissues and shown to influence proliferation and differentiation of numerous cell types. Messenger RNA and protein products of CSF-1 and its receptor (c-fms) have been identified in the human placenta and decidua. We examined whether CSF-1 and c-fms mRNA and protein are expressed by normal human first trimester invasive extravillous trophoblast (EVT) cells propagated in culture and whether CSF-1 influences proliferation and/or invasion of these cells. CSF-1 mRNA and protein expression was determined by RT-PCR and immunofluorescence microscopy. Proliferation was assessed by the cellular uptake of tritiated thymidine and invasion was evaluated by Matrigel invasion assay as well as Northern blot analysis of mRNA expression for invasion-associated enzymes and their inhibitors. Results revealed that normal invasive EVT cells in culture express both CSF-1 and c-fms mRNA and protein. Under serum-free conditions, exogenous CSF-1 greatly stimulated the proliferation of these cells. CSF-1 neutralizing and c-fms receptor blocking antibody (Ab) each abolished the growth stimulatory effects of CSF-1, indicating that CSF-1 and c-fms interaction was responsible for these effects. In fact, c-fms Ab alone reduced proliferation to below background levels. While exogenous CSF-1 failed to influence EVT cell invasiveness, Northern blot analysis of mRNA indicated a slight upregulation of the invasion-associated enzyme 72 kDa type IV collagenase as well as its natural inhibitor tissue inhibitor of metalloprotease (TIMP)-1, so that the balance between the two remained unaltered. These findings suggest that CSF-1 may represent an autocrine (and possibly paracrine) growth stimulatory factor for the invasive trophoblast cells in situ with no net effect on their invasiveness.

alpha 2-Macroglobulin synthesis by the human monocytic cell line THP-1 is differentiation state-dependent

Human alpha 2-macroglobulin (alpha 2M) is a broad spectrum proteinase inhibitor and cytokine carrier synthesized by a number of cell types including monocytes and macrophages. In this study, we report on the expression of alpha 2M by THP-1 cells. This monocytic cell line can be differentiated into a macrophage-like phenotype by treatment with interferon-gamma (IFN-gamma) or phorbol 12-myristate 13-acetate (PMA). alpha 2M was synthesized by THP-1 cells at a rate of 75 ng/10(6) cells/24 h, as determined by Western blot analysis. After treating the cells with 500 U/ml of IFN-gamma or with 100 ng/ml PMA, the synthesis rate increased to 219 ng/10(6) cells/24 h and to 179 ng/10(6) cells/24 h, respectively. The same agents also increased alpha 2M expression, as determined by Northern blot analysis. When the alpha 2M receptor antagonist, receptor associated protein (RAP), was included in the THP-1 medium, the amount of alpha 2M recovered in the conditioned medium increased. This result suggests that THP-1-secreted proteinases react with secreted alpha 2M and that the resulting complexes are catabolized by the alpha 2M receptor, which is also called low density lipoprotein receptor-related protein (LRP). We conclude that alpha 2M synthesis by THP-1 cells depends on the state of cellular differentiation. Reaction of alpha 2M with secreted proteinases may have minimized previous estimates of the rate of synthesis of alpha 2M by certain cells in culture.

LDL receptor family-dependent and -independent pathways for the internalization and digestion of lipoprotein lipase-associated beta-VLDL by rat vascular smooth muscle cells

Lipoprotein lipase (LPL) promotes the binding and internalization of beta-VLDL (very low density lipoprotein) by many cell types. We examined the function of receptors in the LDL receptor family (LRF) and heparan sulfate proteoglycans (HSPG) in the metabolism of LPL-associated beta-VLDLa by rat vascular smooth muscle cells (VSMCs) in culture. These cells express LDL receptor-related protein and the VLDL receptor, but not the LDL receptor. LPL greatly increased the binding of 125I-labeled beta-VLDL to VSMCs at 4 degrees C. Binding was almost entirely inhibited by heparin, but essentially unaffected by the potent LRF-antagonist, receptor-associated protein (RAP), indicating that LRFs do not contribute significantly to the VSMC binding capacity for LPL-associated beta-VLDL. At 37 degrees C, RAP inhibited the rapid internalization of LPL-associated 125I-labeled beta-VLDL and the digestion of the beta-VLDL into trichloroacetic acid soluble radioactivity; these processes still occurred, but at a decreased rate. RAP did not inhibit the ability of beta-VLDL-LPL complex to stimulate VSMC ACAT activity. Furthermore, in Oil red-O histochemistry experiments, which model foam cell transformation in vitro, RAP paradoxically increased cholesteryl ester storage in VSMCs treated with beta-VLDL and LPL under specific cell culture conditions. These results support a model in which the internalization of LPL-associated beta-VLDL by VSMCs is mediated by two pathways, one involving LRFs and a second that is independent of LRFs, probably involving direct uptake by HSPG. The LRF-dependent pathway leads to less cellular storage of cholesteryl ester and thus may be antiatherogenic under certain conditions.

Murine alpha-macroglobulins demonstrate divergent activities as neutralizers of transforming growth factor-beta and as inducers of nitric oxide synthesis. A possible mechanism for the endotoxin insensitivity of the alpha2-macroglobulin gene knock-out mouse

alpha2-Macroglobulin null mice demonstrate increased resistance to endotoxin challenge (Umans, L., Serneels, L., Overbergh, L., Van Leuven, F., and Van den Berghe, H. (1995) J. Biol. Chem. 270, 19778-19785). We hypothesized that this phenotype might reflect the function of murine alpha2M (malpha2M) as a neutralizer of transforming growth factor-beta (TGF-beta) and inducer of nitric oxide synthesis in vivo. When incubated with wild-type mouse plasma, TGF-beta1 and TGF-beta2 bound only to malpha2M. Alternative TGF-beta-binding proteins were not detected in plasma from alpha2M(-/-) mice. Wild-type mouse plasma, but not plasma from alpha2M(-/-) mice, inhibited TGF-beta1 binding to TGF-beta receptors on fibroblasts. Purified malpha2M bound TGF-beta1 and TGF-beta2 with similar affinity; the KD values were 28 +/- 4 and 33 +/- 4 nM, respectively. Murinoglobulin, the second murine alpha-macroglobulin, bound both TGF-beta isoforms with 30-fold lower affinity. Malpha2M counteracted the activities of TGF-beta1 and TGF-beta2 in an endothelial cell growth assay. Malpha2M also induced NO synthesis when incubated with RAW 264.7 cells, an activity which probably results from the neutralization of autocrine TGF-beta activity. Human alpha2M induced NO synthesis comparably to malpha2M; however, MUG had no effect. These studies demonstrate that the ability to neutralize TGF-beta is a property of malpha2M, which is not redundant in the murine alpha-macroglobulin family or in murine plasma. Malpha2M is the only murine alpha-macroglobulin that promotes NO synthesis. The absence of malpha2M, in alpha2M(-/-) mice, may allow TGF-beta to more efficiently suppress excessive iNOS expression following endotoxin challenge.

Transcriptional regulation of LDL receptor-related protein by IFN-gamma and the antagonistic activity of TGF-beta(1) in the RAW 264.7 macrophage-like cell line

Low density lipoprotein receptor-related protein (LRP) is a major receptor for multiple ligands, including chylomicron and VLDL remnants, bacterial toxins, viruses, proteinases, lipoprotein lipase, and activated alpha2-macroglobulin (alpha2M). In this study, we used Northern blot analyses and nuclear run-on experiments to demonstrate that interferon-gamma (IFN-gamma) causes a concentration-dependent decrease in steady-state LRP mRNA expression and gene transcription rate in RAW 264.7 cells. IFN-gamma also markedly increased expression of inducible nitric oxide synthase (NOS), as expected; however, the increase in nitric oxide was not responsible for the down-regulation of LRP expression since the NOS inhibitor, N(G)-monomethyl-L-arginine, did not preserve LRP expression in IFN-gamma-treated cells. Transforming growth factor-beta1 (TGF-beta1; 2.5 ng/mL) had no independent effect on LRP expression and did not modify the response to IFN-gamma when the two cytokines were added simultaneously to cultures. When TGF-beta1 was added 24 h prior to IFN-gamma, the extent of LRP down-regulation was significantly reduced. Specific binding of the LRP ligand, activated (125)I-alpha2M, was decreased by 76 +/- 5% in cells treated with 100 U/mL IFN-gamma, but only by 45 +/- 7% in cells treated with 100 U/mL IFN-gamma after TGF-beta1-pretreatment. The antagonistic activity of TGF-beta1 on the IFN-gamma response in RAW 264.7 cells did not result from a change in LRP mRNA stability or IFN-gamma receptor expression, as determined by Northern blot analyses and (125)I-IFN-gamma binding experiments. The studies presented here suggest that the balance between IFN-gamma and TGF-beta1 may be critical in determining LRP expression at sites of infection and inflammation.

Alpha 2-macroglobulin functions as a cytokine carrier to induce nitric oxide synthesis and cause nitric oxide-dependent cytotoxicity in the RAW 264.7 macrophage cell line

Nitric oxide (NO) is an important mediator of macrophage activities. We studied the regulation of macrophage NO synthesis by alpha 2-macroglobulin (alpha 2M), a proteinase inhibitor and carrier of certain growth factors, including transforming growth factor-beta (TGF-beta). Native alpha 2M and the alpha 2M receptor-recognized derivative, alpha 2M-methylamine (alpha 2M-MA), increased nitrite generation by the RAW 264.7 murine macrophage cell line. The level of nitrite accumulation, which is an index of NO synthesis, was comparable to that observed with interferon-gamma. Native alpha 2M and alpha 2M-MA also increased inducible nitric oxide synthase (iNOS) mRNA levels and substantially reduced the number of viable cells, as determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium/succiny l dehydrogenase assay or trypan blue exclusion. At slightly higher alpha 2M concentrations, [3H]thymidine incorporation was inhibited. All of these activities were counteracted nearly completely when the iNOS competitive inhibitor NG-monomethyl-L-arginine was included. By in situ nick translation, native alpha 2M and alpha 2M-MA increased the percentage of cells with detectable single strand chromatin nicks from 4 to 12 and 17%, respectively. This change suggested apoptosis; however, electron microscopy studies demonstrated variability in the morphology of injured cells. To determine the mechanism by which alpha 2M increases macrophage NO synthesis, we studied proteolytic alpha 2M derivatives that retain partial activity. A 600-kDa derivative that retains growth factor binding activity increased RAW 264.7 cell NO synthesis and iNOS mRNA levels comparable to native alpha 2M and alpha 2M-MA. The purified 18-kDa alpha 2M receptor-binding fragment had no effect on NO synthesis or iNOS expression. Thus, the growth factor-carrier activity of alpha 2M and not its receptor-binding activity is essential for NO synthesis regulation. A TGF-beta-neutralizing antibody mimicked the activity of alpha 2M, increasing RAW 264.7 cell NO synthesis and decreasing cellular viability. These studies demonstrate that alpha 2M can regulate macrophage NO synthesis and profoundly affect cellular function without gaining entry into the cell and without binding specific plasma membrane receptors.

Characteristics of trophoblast cells migrating from first trimester chorionic villus explants and propagated in culture

We developed a method of propagating pure first trimester human trophoblast cells growing out of primary explants of mechanically derived chorionic villus fragments (Yagel et al, 1989; Graham et al, 1992). We have now extensively characterized these cells during their initial outgrowth and in long-term culture, employing a variety of markers and techniques as outlined below. By double label immunofluorescence using epithelial (cytokeratin) and mesenchymal (vimentin) cell markers, we identified the chorionic villus migrant cell populations as pure trophoblast (39 per cent of outgrowths) or a mixture of trophoblast and fibroblast (61 per cent). Further phenotyping of the pure trophoblast outgrowths by double label immunostaining using anti-cytokeratin antibody and a panel of other primary antisera revealed that these cells exhibit a variety of markers characteristic of extravillous invasive trophoblast cells in situ: insulin-like growth factor (IGF)-II, NDOG-5, proliferating cell nuclear antigen (PCNA), human leucocyte antigen framework antigen (W6/32) and a distinct set of integrins including alpha 1, alpha 3, alpha 5, alpha v and beta 1 subunits and alpha v beta 3/beta 5 vitonectin receptor. They were negative for alpha 6 and beta 4 integrin subunits. Immunogold electron microscopy of explants grown on type IV collagen gel revealed the production of conventional and oncofetal types of fibronectin by mononucleate trophoblast cells and human placental lactogen by multinucleate cells. Immunolabelling, flow cytometry and immunoprecipitation revealed that this phenotypic profile was retained with complete fidelity in the long-term culture; thus, trophoblasts migrating out of first trimester chorionic villus explants and their propagated progeny belong to the invasive extravillous trophoblast of the placenta.

Localization of amphiregulin in the human placenta and decidua throughout gestation: role in trophoblast growth

Amphiregulin (AR) is a growth regulatory glycoprotein with significant amino acid homology to members of the epidermal growth factor (EGF) family. Its effects are mediated via the EGF receptor tyrosine kinase or through specific nuclear targeting sequences. In this study, the localization of immunoreactive AR was examined in paraformaldehyde-glutaraldehyde fixed, paraffin-embedded human placentae and decidua obtained at various stages from 11 weeks to term pregnancy using the avidin-biotin complex/peroxidase method. In addition, the effects of AR on trophoblast proliferation were evaluated from 3HTdR uptake by first trimester human trophoblast cells. Results revealed immunolocalization of AR to the nucleus as well as the cytoplasm of the syncytiotrophoblast cell layer of chorionic villi until approximately week 18 of gestation after which no immunostaining was detected. Villous and extravillous cytotrophoblast cells as well as decidual tissue were negative for AR at all gestational ages examined. In the presence of exogenous AR, there was a dose-dependent increase in proliferation of the trophoblast at AR concentrations ranging from 1-100 ng/ml. These results suggest that AR may be an important paracrine or juxtacrine growth stimulatory molecule for cytotrophoblast cells in situ early in gestation.

Localization of transforming growth factor beta and its natural inhibitor decorin in the human placenta and decidua throughout gestation

Transforming growth factor beta (TGF beta) produced at the human fetomaternal interface has been shown to play a crucial role in controlling trophoblast invasion of the uterus. Decorin, a naturally occurring chondroitin-dermatan sulphate proteoglycan which binds TGF beta can inhibit its activity. In this study, immunohistochemical techniques were used to determine the locations of TGF beta and decorin within the human placenta and decidua throughout normal gestation. In addition, sites of TGF beta 1 mRNA synthesis were identified in early and late placenta by in situ hybridization. Results revealed the presence of immunoreactive TGF beta in the cytoplasm of villous syncytiotrophoblast and extravillous trophoblast cells throughout gestation. TGF beta immunostaining was absent from villous cytotrophoblast at all gestational ages examined. The extracellular matrix (ECM) of the villous core at all stages of gestation and cells of the cytotrophoblastic shell of the term placenta were immunoreactive for TGF beta. Within decidual tissue, TGF beta was primarily localized in the ECM during the first trimester and only a small proportion of decidual cells exhibited intracellular labelling. At later gestational ages the majority of decidual cells showed intracellular labelling accompanied by a decrease in ECM staining. This switch may reflect increased TGF beta synthesis by the decidual cells, decreased release, or altered TGF beta binding to one or more ECM proteins. In situ hybridization indicated that TGF beta 1 mRNA was primarily localized to the syncytiotrophoblast cell layer with low intensity signals present in extravillous trophoblast cells, in trophoblast cell columns, and in large decidual cells. At term, TGF beta 1 mRNA was located in both the syncytiotrophoblast and villous mesenchymal cells. Decorin was immunolocalized to the ECM of the mesenchymal core of the chorionic villi throughout gestation and no immunoreactivity was observed in either villous or extravillous trophoblast. In the first trimester decidua, decorin was localized to the ECM whereas decidual cells, decidual leucocytes, and the uterine epithelium were negative. At later gestational ages, the ECM as well as a few decidual cells displayed weak immunoreactivity. A strong co-localization of TGF beta and decorin in the ECM of first trimester decidual tissue suggests that decorin may aid TGF beta storage or limit its activity in the ECM.

Localization of transforming growth factor alpha in the human placenta and decidua: role in trophoblast growth

Transforming growth factor alpha (TGF alpha) is an important growth regulatory molecule, the location and function of which at the human fetomaternal interface remain to be determined. The present study examined the presence of TGF alpha in the human placenta, decidua, and fetal membranes throughout gestation (from a total of 29 subjects) as well as its functional role in the proliferation of first trimester trophoblasts. The peptide was localized immunocytochemically with a monoclonal anti-TGF alpha antibody (Ab) (MF9) on paraffin-embedded tissues via the avidin-biotin complex-peroxidase technique with diaminobenzidine (DAB) as the chromogen. Omission or TGF alpha absorption of the primary Ab served as negative controls. Specific (cytoplasmic) staining was noted in typical stromal-type decidual cells, including cells of the decidua basalis and parietalis and chorionic decidua, throughout gestation. Villous trophoblast cells (syncytiotrophoblast and to a minor extent cytotrophoblast) at all gestational ages as well as extravillous cytotrophoblast cells (intermediate and cytotrophoblastic shell) also showed specific cytoplasmic staining. Chorionic trophoblasts showed variable staining, and little or no immunoreactivity was seen in the amniocytes. Second-passage first trimester human trophoblast cells (characterized by their expression of cytokeratin as well as other markers) were cultured in the presence of TGF alpha or neutralizing anti-TGF alpha Ab (TAb-1) or no additive for 18 h prior to exposure to 3H-TdR for 6 h to measure 3H-TdR uptake. TGF alpha (0-100 ng/ml) caused a dose-dependent stimulation of proliferation, reaching a near plateau at 6-100 ng/ml to slightly more than double the basal level. The presence of anti-TGF alpha Ab alone (25 micrograms/ml) did not significantly influence the proliferation of the cells, indicating the absence of significant endogenous TGF alpha in these cultures; however, the Ab was able to abolish the stimulatory function of exogenous TGF alpha. Exogenous TGF alpha also increased the number of trophoblast nuclei immunoreactive for proliferating cell nuclear antigen and reduced the incidence of multinucleate cells in culture. These results indicate that TGF alpha is present in the cells of the fetomaternal interface throughout human gestation and may function as a stimulator of trophoblastic growth in situ.

In situ localization and characterization of bone marrow-derived cells in the decidua of normal murine pregnancy

The study reported here was designed to examine the in situ distribution and characteristics of hemopoietically derived decidual cells during normal pregnancy in mice prenatally reconstituted with bone marrow cells carrying a transgenic marker. Bone marrow cells from a transgenic CD-1 strain (CD-1 beta; carrying 1000 copies of beta-globin genes in tandem) were injected into the yolk sac of Day 17 conventional CD-1 embryos. The pregnant females were allowed to deliver normally, and the female offspring raised to puberty were mated with CD-1 males and then killed on Day 12 of gestation. The extent of chimerism in sections of their spleens, uteri, and other organs was evaluated by in situ hybridization of the sections with a biotinylated cDNA probe specific for the beta-globin genes followed by avidin-biotin-peroxidase staining. Tissue controls were provided by CD-1 beta and CD-1 mice, respectively. Tissues were also processed without the application of the probe or with the application of biotinylated lambda DNA as specificity controls. Reconstituted mice exhibited variable degrees of hemopoietic chimerism as indicated by labeling of their splenic lymphocytes (18-54%; mean 42%) as well as hemopoietic cells in other organs. Variable cellular labeling was also noted in their decidua basalis and metrial glands. Labeled cells in these tissues were identified as typical decidual cells, macrophages, and granulated metrial gland (GMG) cells. Labeling of typical decidual cells varied extensively among implantation sites in the same chimera, the average labeling ranging from 17% to 33% (mean 24%) in various chimeras. Labeling was also noted in GMG cells, lymphocytes, and some decidual cells migrating out of metrial gland explants after 24-h culture. The non-pregnant uterus of a chimeric mouse revealed significant labeling of endometrial stromal cells indicative of their hemopoietic origin. These results revealed a hemopoietic origin of certain typical decidual cells and GMG cells identified in situ during normal murine pregnancy and a hemopoietic origin of certain endometrial stromal cells that may represent precursors of decidual cells. The precise timing of the predecidual stem cell migration from the bone marrow to the uterus remains to be defined.

Localization of transforming growth factor-beta at the human fetal-maternal interface: role in trophoblast growth and differentiation

We examined the localization of transforming growth factor (TGF)-beta in first-trimester and term human decidua and chorionic villi and explored the role of this factor on the proliferation and differentiation of cultured trophoblast cells. Two antibodies, 1D11.16.8, a mouse monoclonal neutralizing antibody capable of recognizing both TGF-beta 1 and TGF-beta 2 and CL-B1/29, a rabbit polyclonal antibody capable of recognizing TGF-beta 2, were used to immunolocalize TGF-beta in fixed, paraffin-embedded, or fixed, frozen sections of placenta and decidua, providing similar results. Intense labeling was observed in the extracellular matrix (ECM) of the first-trimester decidua and cytoplasm of term decidual cells. Syncytiotrophoblast cell cytoplasm as well as the ECM in the core of the chorionic villi of both first-trimester and term placentas exhibited a moderate degree of labeling. Strong cytoplasmic labeling was observed in the cytotrophoblastic shell of the term placenta. To examine the role of TGF-beta on trophoblast proliferation and differentiation, early passage cultures of first-trimester and primary cultures of term trophoblast cells were established and characterized on the basis of numerous immunocytochemical and functional markers. These cells expressed cytokeratin, placental alkaline phosphatase, urokinase-type plasminogen activator, and pregnancy-specific beta glycoprotein, but not factor VIII or 63D3; they also produced hCG and collagenase type IV. Exposure of first-trimester trophoblast cultures to TGF-beta 1 significantly inhibited proliferation in a dose-dependent manner. An antiproliferative effect was also noted in the presence of TGF-beta 2. These effects were abrogated in the presence of the neutralizing anti-TGF-beta antibody (1D11.16.8) in a concentration-dependent manner. In a 3-day culture, exogenous TGF-beta 1 stimulated formation of multinucleated cells by the first trimester as well as term trophoblast cells. Addition of neutralizing anti-TGF-beta antibody to first-trimester trophoblast cells stimulated proliferation beyond control levels in a 24-h culture and reduced formation of multinucleated cells in a 3-day culture, indicating the presence of endogenous TGF-beta activity. These results indicate that TGF-beta produced at the human fetal-maternal interface plays a major regulatory role in the proliferation and differentiation of the trophoblast.

Activation of maternal killer cells in the pregnant uterus with chronic indomethacin therapy, IL-2 therapy, or a combination therapy is associated with embryonic demise

We have previously shown that NK lineage cells migrate to the murine decidua of pregnancy; but with advancing gestation, they are progressively inactivated in situ by prostaglandins of the E series (PGE2) secreted by decidual cells and decidual macrophages. We have also shown that the same mechanism inactivates all killer lineage cells in the human decidua, and that this inactivation is at least in part due to a down-regulation of IL-2 receptors and an inhibition of IL-2 production in situ. We examined whether chronic indomethacin therapy (to block prostaglandin synthesis), or a systemic administration of a high dose of IL-2, or a combination of both agents administered to pregnant mice could activate killer cells in situ and interfere with the progress of pregnancy; and if so, whether there was a causal relationship between the two events. Pregnant CD1 mice (Day 5 of gestation) were subjected to chronic indomethacin therapy (14 micrograms/ml in drinking water up to Day 15, or 50 micrograms twice daily sc or ip up to Day 10), high dose IL-2 therapy (25,000 Cetus U of human recombinant IL-2, ip every 8 or 12 hr for 3-5 days), or a combination of the two. These treatments led to pregnancy loss in 89-100% of mice, in contrast to 1% loss in control, vehicle-treated mice. Uterine mononuclear cells isolated from the embryo resorption sites exhibited high killer activity against YAC-1 lymphoma as well as murine trophoblast targets, with NK-like phenotype (Asialo GM-1+, Thy-1-) after indomethacin therapy and LAK-like phenotype (AGM-1+, Thy-1+) after IL-2 or indomethacin + IL-2 therapy. That AGM-1+ killer cells resulted in the pregnancy loss was suggested by the findings that in two of three separate experiments, iv injections of AGM-1 ab into pregnant indomethacin + IL-2-treated mice nearly completely prevented the fetoplacental demise (reducing it to 7.7% from 100%). These results reveal that PGE2-mediated inactivation of killer lineage cells in the decidua in situ is conducive to the survival of the conceptus.

Hemopoietic origin of certain decidual cell precursors in murine pregnancy

The possible hemopoietic origin of certain precursors of uterine decidual cells appearing during normal murine pregnancy was investigated in semiallogeneic hemopoietic chimeras with retained or regained fertility. Chimeras were produced by three different methods in two donor-host combinations: F1 [BALB/c female x C3H/HeJ male] cells introduced into the parental strain BALB/c female hosts or F1 [CBA/J female x C57BL/6 male] cells introduced into CBA/J female hosts. Prenatal chimeras (PN) were made by reconstituting mouse fetuses (day 13-17) with 10(6)-10(7) adult bone marrow or fetal liver cells through the yolk sac and they were allowed to be delivered naturally. Neonatal chimeras (NN) were made by injecting 1-2 x 10(7) adult bone marrow cells into the anterior facial vein of neonatal mice (less than 24 hr old). In both cases, experimental animals were raised to maturity. Ovary-transplanted chimeras (OT) were made by injecting 10(7) bone marrow cells into lethally irradiated (9.5 Gy) young adult female mice, followed 6 weeks later with bilateral orthotopic transplants of syngeneic ovary grafts to restore fertility. All female chimeras produced by the three different methods were mated with syngeneic male partners to produce normal pregnancy. The extent of chimerism at the cellular level was determined in all cases by a radioautographic identification of the H-2 phenotype of splenic lymphocytes and decidual cells and macrophages in the collagenase-dispersed decidua at day 11-16 of normal pregnancy, following a sandwich labelling with monospecific anti-H-2 antibodies and 125I-protein A. Morphological discrimination of typical decidual cells from macrophages in the collagenase-dispersed decidua was carried out on the basis of several distinctive markers: presence of surface Dec-1 and Thy-1 and absence of surface F4/80 or latex phagocytosis for decidual cells, in contrast to macrophages which were phagocytic and expressed F4/80 but not Dec-1 or Thy-1. While the degree of hemopoietic chimerism (judged by the incidence of donor-derived lymphocytes in the spleen) varied from animal to animal, in all three groups (PN, NN, and OT) comprising a total of 26 chimeras, the percentage of typical decidual cells expressing donor H-2 phenotype showed an excellent correlation with that for small lymphocytes in the spleen. These results reveal that at least a subpopulation of typical decidual cells of the pregnant uterus has a hemopoietic genealogy. A possible familial relationship of these cells to granulated metrial gland cells remains unclear.