Ontogeny, immunocytochemical localization, and biochemical properties of the pregnancy-associated uterine elastase/cathepsin-G protease inhibitor, antileukoproteinase (ALP): monospecific antibodies to a synthetic peptide recognize native ALP.

Expression of the mRNA encoding the elastase/cathepsin-G protease inhibitor, antileukoproteinase (ALP), is highest in pig uterus during mid- and late pregnancy, suggesting a stage of pregnancy-dependent role for ALP in feto-maternal interactions. To elucidate a function for ALP in these events, immunogenic probes were developed to localize sites of ALP expression in the environment of the developing fetus. Monospecific antibodies raised against a 16-mer synthetic peptide corresponding to residues 21-36 (ALP 16P) of the deduced amino acid sequence of pig uterine ALP were generated by active immunization of sheep. ALP 16P conjugated to keyhole limpet hemocyanin elicited high titer antibodies that were specific to ALP. The antipeptide antibodies were used to characterize pig uterine ALP from allantoic fluids. Uterine ALP has an approximate mol wt of 14,000 and a pI of 8.2 and exhibits elastase inhibitor activity. Amino-terminal amino acid sequencing of uterine ALP indicated the sequence AENALKGGACPPRKIVQC, which has 44% identity with the corresponding region in human bronchial ALP. RIA for ALP, developed using ALP 16P as standard and iodinated tracer, demonstrated the presence of immunoreactive ALP in early, mid-, and late pregnant endometrium and myometrium, placenta, allantoic fluids, fetal cord blood, and fetal liver. ALP was undetectable in the maternal circulation. The ALP levels in endometrium, allantoic fluids, and fetal cord blood changed with the stage of pregnancy; however, ALP content in placenta, myometrium, and fetal liver, although different among tissues, remained invariant during gestation. By immunocytochemical analyses, ALP was localized in the glandular epithelium of the uterus, in placenta, and in fetal liver, consistent with the presence of immunoreactive ALP as measured by RIA. The localization of uterine ALP in placenta and its corresponding transport to fetal circulation provide strong evidence to support a physiological function for the protease inhibitor in the biological mechanisms controlling fetal development in utero.

Characterization and developmental expression of binding sites for the transplacental iron transport protein, uteroferrin, in fetal hematopoietic tissues.

In the pig, iron transport to the developing fetus during pregnancy involves, in part, uteroferrin (UF), a secreted progesterone-induced protein of the uterus. Neonatal pigs suffer from anemia, and the decrease in the synthesis of UF protein in late pregnancy was suggested to be partly responsible for this condition. To examine whether diminished capacity for UF uptake by pig fetuses may also contribute to neonatal anemia, binding sites for 125I-UF were examined in plasma membrane-enriched fractions of fetal liver and spleen, which are sites of fetal hematopoiesis. In addition, changes in the number of these binding sites as a function of fetal development were evaluated. Binding of 125I-UF to liver membrane fractions was displaced by intact UF greater than deglycosylated (aglyco) UF greater than ovalbumin, but not by yeast mannan. Scatchard analysis of radioligand binding showed the presence of a single class of binding sites with a dissociation constant of 10(-7) M. During fetal development and at postpartum (day 5), liver binding sites for UF remained invariant and displayed the same affinity. In contrast, the number of binding sites for UF in fetal spleen increased from midpregnancy to parturition and remained elevated in day 5 neonatal spleen. Affinity cross-linking of 125I-UF to liver membrane-associated binding sites and subsequent analysis by gel electrophoresis and autoradiography demonstrated a single labeled protein complex of Mr 58,000 and 87,000 under denaturing and nondenaturing conditions, respectively. The appearance of these bands was inhibited by intact UF, but not ovalbumin. The characteristics of the membrane-associated binding sites for UF differed from those of the mannose-related receptor previously described in reticuloendothelial cells of fetal liver. The invariant presence of UF binding components in sites of hematopoiesis during fetal development suggests that mechanism(s) unrelated to specific uptake of UF are responsible for neonatal anemia.

Uteroferrin: a progesterone-induced hematopoietic growth factor of uterine origin.

Uteroferrin is a purple progesterone-induced glycoprotein containing two molecules of iron per 35,000 molecular weight polypeptide, which has high amino acid sequence homology with Type 5 acid phosphatases from normal human placentae, from sera of patients with hairy cell leukemia, Gaucher's disease, and osteoporosis, as well as from normal spleens of pigs, cattle, rats, and mice. Results of the present study indicate that uteroferrin also has colony-forming unit (CFU) activity for committed erythroid (BFU-E) and granulocyte-monocyte/macrophage (CFU-GM) cell lines and exists as far back as the granulocyte, erythrocyte, monocyte/macrophage, megakaryocyte (CFU-GEMM) committed lineage. Uteroferrin exerts maximum CFU activities at 1 microgram/ml in serum-free culture medium with no supplemental iron (90 micrograms/ml ferric iron). However, when ferric iron concentration in medium was increased to 200 micrograms/ml, uteroferrin had maximum CFU activities at 100 pg/ml. Preincubation of uteroferrin with polyclonal antiserum or monoclonal antibody to uteroferrin effectively eliminated its CFU activities. Uteroferrin derived from human term placentae also exhibits BFU-E, CFU-GM, and CFU-GEMM activities. The mechanism by which uteroferrin stimulates proliferation and differentiation of primitive hematopoietic stem cells is unclear.

Characterization of feline conceptus proteins during pregnancy.

This study characterized proteins secreted de novo by feline conceptuses collected on Days 10, 12, and 15 (n = 22, preimplantation blastocysts); Days 15, 16, 17, 19, 21, and 25 (n = 6, postimplantation zonary girdle [ZG] i.e. trophoblast and endometrium); and Days 30, 36, 39, and 50 (n = 5, postimplantation ZG and free chorioallantois [CA]) and cultured in Minimal Essential Medium. De novo secretion was shown by incorporation of 3H-leucine into proteins detected in culture media by 2D-PAGE and fluorography. Western blotting, and NH2-terminal amino acid microsequencing. Major radiolabeled proteins identified as they appeared temporally on fluorographs were as follows: feline conceptus protein 1 (fCP1), Mr = 20,000, pI 5.0-5.3; fCP2, Mr = 80,000, pI 6.5-7.2; fCP3a, Mr = 67,000, pI 6.3-6.5; fCP3b, Mr = 67,000, pI 5.9-6.3; fCP4, Mr = 56,000, pI 5.0-6.0; and fCP5, Mr = 29,000, pI 5.0-5.8. The fCP1 was produced by blastocysts on Days 10-15, ZG on Days 16-25, and CA on Day 30; on Days 39-50, CA synthesized 5 proteins, possibly fCP1 isomers. The fCP2, fCP3a and b, and fCP4 were produced by blastocysts on Day 15, ZG on Day 25, and CA on Days 30-50. The fCP5 was made by ZG on Days 16-36 and by CA on Days 30-39. Western blotting identified fCP1 as retinol-binding protein (RBP), fCP2 as alpha fetoprotein, fCP3a as albumin, and fCP3b as transferrin. Amino acid sequence homologies between fCP1 and rabbit and human plasma RBP and porcine conceptus RBP2 were 93, 96, and 100%, respectively, at the first 37 NH2-terminal amino acids. The identities of fCP4 and fCP5 have not been established. Antiviral activity detected in all media was less than 3 units/ml when tested with feline fibroblast cells infected with vesicular stomatitis virus.

Evidence for steroid control of a putative angiogenic factor in the porcine uterus.

The formation of new capillaries, both in extraembryonic membranes and in the maternal endometrium, is an essential prerequisite for appropriate feto-maternal relationships throughout pregnancy. At present there is no indication of the nature of the uterine angiogenic stimulus. In-vitro, degradation products of hyaluronic acid, following its catalysis by hyaluronidase, have been shown to have angiogenic properties. In the current study, levels of hyaluronic acid in endometrial tissues and of hyaluronidase and hyaluronic acid in uterine flushings were measured during the oestrous cycle and early pregnancy. The concentration of both hyaluronic acid and hyaluronidase in uterine flushings followed the growth and regression of the corpus luteum, in that basal levels detected on days 0 and 6 increased to peak concentrations on days 12 and 15. By day 18, levels of both hyaluronidase and hyaluronic acid had decreased in cyclic gilts, but remained increased in pregnant pigs. Tissue concentrations of hyaluronic acid were not affected by pregnancy or by the day of the oestrous cycle. In a subsequent experiment, four groups of gilts were ovariectomized on day 4 and thereafter received daily injections of corn oil, progesterone, oestrogen or a combination of oestrogen and progesterone. Hyaluronidase was undetectable in uterine flushings collected on day 15 from corn oil- and oestrogen-treated gilts, but present in similar amounts in uterine flushings from gilts treated with progesterone and progesterone plus oestrogen. Similarly, uterine fluid concentrations of hyaluronic acid were increased in progesterone- and progesterone plus oestrogen-treated gilts, but not in corn oil- or oestrogen-treated pigs. Tissue concentrations of hyaluronic acid were unaffected by steroid treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of pregnancy, oxytocin, ovine trophoblast protein-1 and their interactions on endometrial production of prostaglandin F2 alpha in vitro in perifusion chambers.

Pregnancy and intrauterine infusion of ovine trophoblast protein one (oTP-1) decrease oxytocin-induced secretion of prostaglandin F2 alpha (PGF) from the uterus. In the present study, effects of oTP-1 and pregnancy on endometrial secretion of PGF were examined in an in vitro perifusion system. In Experiment 1, endometrium from day 14 pregnant and cyclic ewes was perifused sequentially on both the lumenal and myometrial sides with Krebs Ringers Bicorbonate solution (KRB), KRB plus oxytocin (1 IU/ml) and KRB alone. Endometrium from pregnant ewes secreted more PGF from both lumenal and myometrial sides than endometrium from cyclic ewes (P less than 0.05). Oxytocin stimulated secretion of PGF from both sides of endometrium regardless of status. Secretion of PGF was greater from the lumenal surface of endometrium compared to myometrium (P less than 0.05) for pregnant and cyclic ewes. For Experiment 2, endometrium was collected from day 15 cyclic ewes and perifused sequentially with KRB, KRB plus 300 ng/ml of either Bovine Serum Albumin (BSA) or oTP-1, KRB with or without BSA or oTP-1 plus oxytocin (1 IU/ml) and then KRB alone. Oxytocin stimulated greater release of PGF from oTP-1-treated than BSA-treated endometrium. Pretreatment of endometrium with oTP-1 had the same effect on oxytocin-induced PGF secretion as cotreatment with oTP-1 and oxytocin. In Experiment 3, uterine horns of cyclic ewes were catheterized on day 10 of the estrous cycle, and infused with either oTP-1 or day 16 pregnant sheep serum proteins on days 12, 13 and 14. Endometrium was collected on day 15 and perifused sequentially with KRB, KRB plus oxytocin (1 IU/ml) and then KRB alone. Treatment of ewes with oTP-1 attenuated endometrial secretion of PGF in response to oxytocin. Results of this study indicate that: (1) pregnancy stimulates basal secretion of PGF from endometrium and has no effect on oxytocin-induced secretion of PGF in vitro; (2) short-term oTP-1 treatment enhances oxytocin-induced PGF secretion from day 15 cyclic endometrium and (3) long-term oTP-1 treatment in vivo inhibits oxytocin-induced PGF secretion in ewes.

Effect of ovine conceptus secretory proteins and purified ovine trophoblast protein-1 on interoestrous interval and plasma concentrations of prostaglandins F-2 alpha and E and of 13,14-dihydro-15-keto prostaglandin F-2 alpha in cyclic ewes.

Conceptus secretory proteins (oCSP) were obtained from medium in which sheep conceptuses, collected on Day 16 of pregnancy, were cultured for 30 h. A portion of the culture medium (500 ml) was prepared for intrauterine infusion by concentrating the proteins by Amicon ultrafiltration (Mr 500 cutoff). A second portion (500 ml medium) was used to purify sheep trophoblast protein one (oTP-1). Proteins remaining after oTP-1 purification were concentrated and then passed through an anti-oTP-1 sepharose CL-4B affinity column to remove any remaining oTP-1 (oCSP-oTP-1). Serum proteins (oSP) were collected from a Day-16 pregnant ewe and diluted for infusion. Catheters were placed in the uterus of cyclic (Day 10) ewes. The following combinations of proteins were infused: 0.75 mg oCSP + 0.75 mg oSP (5 ewes), 0.75 mg oCSP - oTP-1 + 0.75 mg oSP (4 ewes), 0.05 mg oTP-1 + 1.45 mg oSP (5 ewes) and 1.5 mg oSP only (5 ewes). Infusions were twice daily on Days 12 and 13 (08:00 and 17:00 h) and once on Day 14 (08:00 h). On Day 14, ewes were injected intravenously at 08:00 h with 0.5 mg oestradiol-17 beta. Blood sampling began 30 min before oestradiol injection and continued every 30 min for 10 h. On Day 15 ewes received 10 i.u. oxytocin intravenously (08:00 h). Blood samples were collected 10 min before oxytocin and every 10 min for 1 h after oxytocin injection. Concentrations of prostaglandin (PG) F, PGE-2/PGE-1 (PGE) and 13,14-dihydro-15-keto-PGF-2 alpha (PGFM) were measured by specific radioimmunoassay. Ewes treated with oTP-1 and oCSP had longer (P less than 0.05) interoestrous intervals (27 and 25 days, respectively) compared to ewes treated with oSP and oCSP--oTP-1 (19 and 19 days, respectively) (s.e.m. = 1.56 days). These results indicate that oTP-1 alone is as potent as total conceptus secretory proteins in extending luteal maintenance. Ewes treated with oTP-1 and oCSP had no increase in PGF after oestradiol injection while production of PGF did increase 6-10 h after oestradiol in ewes treated with oSP and oCSP--oTP-1. PGFM was correlated with PGF concentrations (r = 0.57, P less than 0.01) although presence or absence of increases in production of PGFM for the treatment groups were not the same as those for PGF. No effects of treatment on PGE were detected.(ABSTRACT TRUNCATED AT 400 WORDS)