Human endometrium and menstrual fluid contain placental protein 10 (PP10)

Placental protein 10 (PP10), a newly isolated protein from the human placenta, was detected by radioimmunoassay in 10 out of 23 extracts of proliferative and secretory endometrium and in all of the 20 menstrual fluids examined. The concentrations were higher in the secretory phase, when the tissue PP10 content ranged from less than 0.2 to 1.3 microgram/g of endometrial cytosol protein. In menstrual fluid, PP10 was found at concentrations of 16 to 270 micrograms/l. In RIA, the dose-response curves of endometrial, menstrual fluid and purified PP10 were parallel. In gel filtration, the major part of PP10 from the endometrium and menstrual fluid eluted in the same fraction as purified placental PP10. Our results add another placental protein to the list of placental proteins which also appear in the endometrium.

Progesterone-associated proteins PP12 and PP14 in the human endometrium

Two proteins, designated as PP12 and PP14 were originally isolated from soluble extracts of the human placenta and its adjacent membranes. We have shown that they are synthesized by decidualized/secretory endometrium and not by placenta. Both proteins occur at high concentrations in human amniotic fluid, which is therefore an excellent source for purification. PP12 is a 34-kDa glycoprotein, which has an N-terminal amino acid sequence of Ala-Pro-Trp-Gln-Cys-Ala-Pro-Cys-Ser-Ala. This is identical with that of somatomedin-binding protein purified from the amniotic fluid. PP12 too binds somatomedin-C, or IGF-I (insulin-like growth factor-I). Human secretory endometrium synthesizes and secretes PP12, and progesterone stimulates its secretion. PP14 is a 28-kDa glycoprotein. Its N-terminal sequence shows homology to that of beta-lactoglobulins from various species. We have found PP14 in the human endometrium, serum and milk. Immunologically, PP14 is related to progestagen-associated endometrial protein (PEP), alpha-2 pregnancy-associated endometrial protein (alpha-2, PEG), endometrial protein 15 (EP15), alpha-uterine protein (AUP) and chorionic alpha-2 microglobulin (CAG-2). In ovulatory menstrual cycles, the concentration of PP14 increases in endometrial tissue as the secretory changes advance. In serum, the PP14 concentration begins to rise later than the progesterone levels, and high serum PP14 levels are maintained for the first days of the next cycle. By contrast, no elevation of serum PP14 level is seen in anovulatory cycles. Our results show that progesterone-associated proteins are synthesized by the human endometrium and appear in the peripheral circulation, where they can be quantitatively measured using immunochemical techniques.

Placental protein 5 in benign and malignant ovarian cyst fluids

Placental protein 5 (PP5), a serine protease inhibitor, was measured by radioimmunoassay in fluids aspirated from benign and malignant cystic ovarian tumours. PP5 was found in 7 out of 9 malignant and in 12 out of 29 benign cyst fluids (p less than 0.01), the levels ranging from 3.0 to 73.4 micrograms/l. No PP5 was found in the corresponding serum samples from 4 patients whose malignant cystadenocarcinomas contained PP5. In those tumours where PP5 was found, no difference was observed in the PP5 levels between benign and malignant, or between serous and mucinous tumours.

Insulin-like growth factor-binding protein PP12 in ovarian cyst fluid

Elevated levels of insulin-like growth factor-binding protein (IGF-bp) were recently found in the serum of patients with ovarian tumors. We studied the concentration of IGF-bp in cyst fluids of 37 women operated on for benign or malignant ovarian cysts. The levels were elevated (greater than 47 micrograms/l) in 6 of 28 benign, but in none of the nine malignant ovarian cysts. The highest IGF-bp concentration (447 micrograms/l) was observed in a benign serous cystadenoma.

Placental protein 10 (PP10) in the serum of patients with trophoblastic and nontrophoblastic gynaecological tumours

Serum levels of placental protein 10 (PP10) were measured by radioimmunoassay in patients with trophoblastic (n = 23) and non-trophoblastic (n = 122) gynaecological tumours before, during and after treatment. Elevated levels (greater than 2.0 micrograms/l) were found in 96% of patients with an untreated trophoblastic tumour, and in 22%, 20% and 12% of patients with endometrial, cervical and ovarian carcinoma, respectively. After treatment the levels fell in patients with trophoblastic disease. Although PP10 may be tumour-associated in such cases, it is premature to assume any significance for PP10 as a tumour marker in clinical practice, because changes in serum hCG levels are much more informative.

Biologically active domain in somatomedin-binding protein

We have found that human decidua synthesizes a 34K somatomedin-binding protein PP12. Purification of PP12 by immunochemical techniques from human placenta and adjacent membranes has also yielded lower-molecular weight immunoreactive polypeptides designated as PP12B. An individual 21K fragment of somatomedin-binding protein, and a mixture of fragments with molecular weight from 17K to 20K were isolated from this material using high performance liquid chromatography (HPLC). These fragments reacted with antibodies to native PP12 as shown by Western blotting. They all shared the same N-terminal amino acid sequence: Ala-Pro-Trp-Gln-, which is identical with that obtained for PP12. The 21K fragment was shown to bind somatomedin-C, or IGF-I (insulin-like growth factor-I). Since the N-terminal end of the 21K fragment is identical with that of the 34K somatomedin-binding protein, our results suggest that the 21K fragment is the N-terminal part of somatomedin-binding protein, and the somatomedin-binding domain resides in this N-terminal portion.

Elevated levels of a somatomedin-binding protein PP12 in patients with ovarian cancer

The circulating levels of placental protein 12 (PP12), a somatomedin-binding protein, were measured by radioimmunoassay in 37 postmenopausal women with ovarian tumors. Elevated levels (above 47 micrograms/l) were observed in 16 of 25 patients (64%) with malignant and 2 of 12 patients (17%) with benign tumors. Elevated levels were more frequent and higher in patients with advanced disease. Within 1 week of surgery, the levels fell in 13 of 17 cases (77%). In addition to clinical interest, these results contribute to our knowledge of carrier proteins of growth factors in patients bearing malignant ovarian neoplasms.

Placental proteins in oncology

Many placental proteins appear in the serum and tumours of patients with malignant disease, but few have achieved an established position in clinical management. Chorionic gonadotrophin is a sensitive and effective marker for trophoblastic disease. Gonadal germ cell tumours containing extraembryonic structures can secrete hCG and SPl, which both may provide unique clinical information about recurrent disease. Placental proteins belonging to the PP series are an interesting new group which has added to our knowledge of the biology of tumours. However, none of them has yet proven to be important in clinical practice. Placental alkaline phosphatase isoenzymes are secreted by seminomas and dysgerminomas, and, in some clinics, they are routinely examined for monitoring treatment of these tumours. Whereas the clinical usefulness of the above markers is well established for the monitoring of treatment and early detection of recurrent disease, none of them can be used for the screening of cancer in an apparently healthy population.

The content and immunohistochemical localization of placental protein 10 (PP10) in the fallopian tube

Radioimmunoassay, gel filtration and immunoperoxidase staining were used to study the content and localization of placental protein 10 (PP10) in 15 fallopian tubes removed on medical grounds from patients aged between 35 and 53 years. PP10 was consistently present in all parts of the tube at all ages and in all phases of the menstrual cycle. The PP10 concentration in tissue ranged from 0.08 to 2.95 micrograms/g of tubal cytosol protein. Immunoperoxidase staining localized PP10 in monocytic and lymphoid cells that were unevenly scattered in the subepithelial layer of the mucosa. In gel filtration, PP10 from the fallopian tube and purified placental PP10 eluted in the same volume, and graded amounts of PP10-immunoreactive material from the tube and purified PP10 gave parallel dose-response curves in radioimmunoassay. We conclude that PP10 is another 'placental protein' that has been identified in the fallopian tube.

Human endometrium and menstrual fluid contain placental protein 5 (PP5)

Placental protein 5 (PP5), a serine protease inhibitor, was found in the endometrium and menstrual fluid of non-pregnant women. PP5 was present in all 16 endometrial samples taken at various phases of the menstrual cycle. In the secretory phase, the endometrial PP5 content was higher (median 17.4 micrograms/g protein; n = 8) than in the proliferative phase (median 3.8 micrograms/g protein; n = 8). In gel filtration, endometrial tissue homogenates yielded one immunoreactive peak corresponding to a mol. wt of 28,000 daltons, whereas placental PP5 eluted at 32,000 daltons. In sodium dodecyl sulphate polyacrylamide gel electrophoresis, endometrial PP5 comigrated with purified placental PP5 corresponding to a mol. wt of 30,000 daltons. All menstrual fluid samples (n = 14) contained immunoreactive PP5 at concentrations from 77 to 1150 micrograms/l. The mol. wt of menstrual fluid PP5-immunoreactivity was 13,000 daltons. The dose-response curves of purified PP5 standard and endometrial and menstrual fluid PP5 were parallel in the PP5 radioimmunoassay. The higher concentration of PP5 in secretory endometrium indicates association of PP5 with endocrine events of the menstrual cycle.

Elevated circulating levels of a decidual protein, placental protein 12, in preeclampsia

The serum concentration of placental protein 12 was measured by radioimmunoassay in 111 apparently healthy pregnant women at 33 to 40 weeks, and the results were compared with those of 39 women with preeclampsia either with or without proteinuria at similar stages of pregnancy. Because the placental protein 12 levels were similar between 33 and 40 weeks of pregnancy, all data were pooled for the analysis of results. The levels were generally higher in preeclamptic patients: 175 +/- 81.5 micrograms/L (mean +/- SD) for preeclampsia versus 112 +/- 38.8 micrograms/L for controls (P less than .001). Those patients with proteinuric preeclampsia had the highest levels (207 +/- 92.1 micrograms/L; P less than .001). In preeclampsia the levels were above the normal 90th percentile in 15 (38%) cases (P less than .001). Because placental protein 12 has recently been found to be synthesized by decidua and not placenta, these results suggest that decidua may be affected in preeclampsia.

Human fallopian tube contains placental protein 14

Radioimmunoassay and immunoperoxidase staining were used to study the tissue content and localization of an endometrial protein, placental protein 14, in the human fallopian tube. Placental protein 14 immunoreactivity was found in saline extracts from all fallopian tubes tested (n = 14). In the fimbrial part the placental protein 14 content was higher in the secretory than in the proliferative phase (p less than 0.01). No difference was found in the placental protein 14 content between the isthmic, ampullar, and fimbrial parts of the tube. Immunoperoxidase staining localized placental protein 14 to the ciliated and secretory epithelial cells of the mucosa in all parts of the tube regardless of the phase of menstrual cycle. The occurrence of the same protein in the endometrium and fallopian tube is compatible with the common embryonic origin from the müllerian duct of these tissues.

Secretory endometrium synthesizes placental protein 14

Saline extracts of human nonpregnant endometrium were found to contain placental protein 14 (PP14). The tissue PP14 content was highest in the late secretory phase (median, 7.7 mg/g protein; n = 14), whereas proliferative endometrium (n = 8) was either PP14 negative or showed a low PP14 content (median, 0.15 mg/g protein). By immunoperoxidase staining, PP14 was localized in the glandular epithelial cells of endometrium. In tissue culture, secretory endometrium released more PP14 than proliferative endometrium, and cycloheximide markedly decreased this release. Synthesis of PP14 by secretory endometrium was demonstrated by incorporation of [35S]methionine into immunoprecipitable PP14. These results show that PP14 is synthesized and secreted by the nonpregnant endometrium.

Placental protein 12 is a decidual protein that binds somatomedin and has an identical N-terminal amino acid sequence with somatomedin-binding protein from human amniotic fluid

Placental protein 12 (PP12) was originally isolated from term human placenta and adjacent membranes. Recently we found that the site of PP12 synthesis is decidua but not placenta. In this work, the purity of PP12 was first tested by sodium dodecyl sulfate polyacrylamide slab-gel electrophoresis and by reverse phase HPLC, and the N-terminal amino acid sequence of 15 residues was determined by a liquid-phase sequencer. A single amino acid sequence of Ala-Pro-Trp-Gln-Cys-Ala-Pro-Cys-Ser-Ala-Asp-Glu-Leu-Ala-Leu was obtained showing identity to the known N-terminal amino acid sequence of somatomedin-binding protein from human amniotic fluid. Like the latter, PP12 bound somatomedin (insulin-like growth factor I) as demonstrated in gel chromatography by a shift in the elution pattern of [125I]iodo-insulin-like growth factor I after incubation with PP12. These data show that PP12 is a somatomedin-binding protein and extend through previous literature on PP12 the existing knowledge on the physiology and pathophysiology of somatomedin-binding protein(s) in human reproduction and cancer.

Ovarian cancer antigen CA 125 levels in pelvic inflammatory disease and pregnancy

Circulating CA 125 levels were studied in patients with gynecologic cancer and pelvic inflammatory disease, and in pregnant women. The CA 125 level was elevated (greater than 35 U/ml) in 69% (9/13) of patients with active ovarian cancer, in 32% (7/22) of patients with active cervical or endometrial cancer, in 24% (11/46) of pregnant women, and in 33% (10/30) of patients with acute pelvic inflammatory disease. Sixty-three other patients with nonmalignant gynecologic disorders, including 15 patients with ectopic pregnancy, had normal CA 125 levels. The occurrence of elevated CA 125 levels in patients with pelvic inflammatory disease can limit the use of the assay for diagnosis of cancer in young women. Gynecologic tumors may be associated with inflammatory reactions that may contribute to elevated CA 125 levels in some cancer patients.

Synthesis of placental protein 12 by human endometrium

We have previously shown that placental protein 12 (PP12) is synthesized and secreted by human term pregnancy decidua in vitro. In the present study, fragments of proliferative and secretory phase endometrium were cultured in media in the presence and absence of progesterone (P) and 17 beta-estradiol (E2) for 96 h. The PP12 concentrations in the media and tissues were measured by RIA, and de novo synthesis was investigated by measuring the incorporation of [35S]methionine into PP12. Before culture, PP12 could not be detected in any proliferative endometria, whereas all secretory endometria contained PP12. All secretory endometria released PP12 into the medium in the presence and absence of added P and E2. Secretory endometria released significantly more PP12 than proliferative endometria. Three of seven proliferative endometria did not release PP12 in the absence of P, but all did so after P had been added. The addition of P to culture medium caused a 2.4-to over 71-fold increase in PP12 secretion over control values in proliferative endometria and up to a 3.5-fold increase in secretory endometrium. E2 had no significant effect. Cycloheximide totally inhibited the PP12 release induced by P from proliferative endometrium, and in secretory endometrium, it either totally blocked PP12 release or inhibited the stimulation due to P. [35S]Methionine was incorporated into immunoprecipitable PP12 in cultures of secretory and P-treated proliferative phase endometria. These results demonstrate de novo synthesis of PP12 by nonpregnant endometrium in tissue culture and suggest that the biosynthesis and secretion of PP12 by nonpregnant endometrium are regulated by P.

Is decidua affected in gestational hypertension? Indication by elevated PP14 levels

The serum concentration of placental protein 14 (PP14) was measured by radioimmunoassay in 129 apparently healthy pregnant women at 33-40 weeks, and the results were compared with those of 40 women with gestational hypertension either with or without proteinuria at similar weeks. In normal pregnancy, maternal serum PP14 levels decreased towards term. Therefore, the results were expressed as multiples of the normal median for each week. In gestational hypertension, the values were higher than normal (p less than 0.001): they were above the normal median in 32 (80%) cases (p less than 0.005), and above the normal 90th percentile in 15 (38%) cases (p less than 0.001). The presence or absence of proteinuria did not affect the result. Since recent findings suggest that PP14 is synthesized by late pregnancy decidua and not by the placenta, our results suggest that decidua may be affected in gestational hypertension.

Placental protein 14 and progestagen-dependent endometrial protein are immunologically indistinguishable

Placental protein 14 isolated from the human placenta and its adjacent membranes, and progestagen-dependent endometrial protein (PEP) isolated from the endometrium have been described independently by two groups. We report results of the radioimmunological and immunodiffusion tests which show that the proteins are immunologically indistinguishable from each other.

Serum levels of placental protein 14 reflect ovulation in nonconceptional menstrual cycles

Placental protein 14 (PP14), originally isolated from the human placenta and its adjacent membranes, was detected in the serum of nonpregnant women. The levels were measured by radioimmunoassay in 218 serum samples from 19 women throughout the menstrual cycle. In 13 women with a normal ovulatory cycle, the levels showed consistent variation. They were highest (up to 172 ng/ml) in the late secretory phase and remained high for the first days of the next cycle. Low concentrations were found from the midproliferative to the early luteal phase of the cycle. No similar variation was seen in anovulatory cycles of six other women. Compared with ovulatory cycles, anovulatory cycles exhibited lower PP14 levels in the latter part of the cycle (P less than 0.001) and in the beginning of the next cycle (P less than 0.01). In ovulatory cycles, the sustained elevation of serum PP14 concentration over the following period may be explained by the fairly long half-life (42 hours) of PP14 in serum: once the level has increased, it declines slowly. These results suggest that PP14 measurement may become a novel means to distinguish between ovulatory and anovulatory cycles even after the onset of the next period.

Placental protein 10 (PP10) in normal pregnancy and cholestasis of pregnancy

The circulating concentrations of placental protein 10 (PP10) were measured by radioimmunoassay in 288 women with normal pregnancy and ten women (55 samples) with cholestasis of pregnancy. Serum PP10 levels were not affected by changes in incubation and storage temperature, and no diurnal variation was observed. The highest PP10 levels (36-85 micrograms/l) in normal pregnancy were found at 34 weeks. The postpartum decline of serum PP10 concentration corresponded to an average half-life of 18 h. In cholestasis of pregnancy at 32-39 weeks, the serum PP10 levels were found to be lower than normal. Negative correlation was observed between aminotransferase and PP10 levels in serum and between the bile acid levels and the PP10 concentration. These results suggest that the severity of maternal liver disorder is reflected in the circulating PP10 concentration.

Distribution of placental protein 14 in tissues and body fluids during pregnancy

Placental protein 14 (PP14) levels were measured in serum samples from non-pregnant and pregnant women, amniotic fluid, cord blood, and extracts of placenta, decidua and fetal membranes. The levels were low (15-40 micrograms/l) in serum of non-pregnant women. In four pregnancies following in-vitro fertilization, the serum PP14 levels started to rise 2-12 days after embryo replacement. In normal pregnancy, the highest serum PP14 concentrations (up to 2200 micrograms/l) were detected between 6 and 12 weeks. After 16 weeks the level decreased and plateaued at 24 weeks to around 200 micrograms/l. In amniotic fluid, the highest PP14 levels (232 mg/l) were found between 12 and 20 weeks, being considerably higher than those in maternal serum throughout pregnancy. In cord blood, the levels were low (15-22 micrograms/l) or undetectable. In early pregnancy decidua, the PP14 content was higher (41-160 mg/g total protein) than in late pregnancy decidua (60-2700 micrograms/g total protein). In amnion and chorion laeve, the PP14 concentration varied from 50 to 750 and 50 to 1000 micrograms/g protein, respectively. Early pregnancy placenta contained 0.25-15 mg/g and late pregnancy placenta 3-430 micrograms/g protein of PP14. These results show that the levels of PP14 in pregnancy serum have a similar profile to hCG, but in contrast to other placental proteins, the amniotic fluid PP14 levels are remarkably high. This may be explained by suggesting that decidua is a source of PP14.

Pregnancy-associated plasma protein-A and placental protein 5 in human seminal plasma

Human seminal plasma contains two glycoproteins which are physiochemically and immunologically indistinguishable from pregnancy-associated plasma protein-A and placental protein 5. Seminal concentrations of both glycoproteins did not correlate with clinical assessment of semen quality. Furthermore, analysis of split ejaculates indicated a nontesticular origin for both proteins, which are possibly secreted into the distal portions of the tract by the accessory glands (prostate gland and seminal vesicles). The physiological significance of these findings has yet to be determined. However, it is suggested that pregnancy-associated plasma protein-A, a known potent inhibitor of leukocyte elastase, protects the deposited sperm against proteolytic attack originating from the localized leukocyte reaction within the female reproductive tract, thus contributing towards sperm survival within this immunologically hostile environment and enabling fertilization to occur.

The world collaborative report on in vitro fertilization and embryo replacement: current state of the art in January 1984

A questionnaire was sent to potential participants of the III World Congress of in Vitro Fertilization and Embryo Transfer, held in Helsinki in 1984, concerning their current practice in and results with IVF to the end of January 1984. Sixty-five teams reported information concerning 10,028 cycles. Embryo replacement was performed in 7993 cycles to yield 600 infants to date from 523 confinements; 572 continuing pregnancies; 324 clinical abortions; and 19 ectopic and 285 "biochemical" pregnancies. The best success rates were seen in couples where the woman was less than 30 years of age (13.6%) compared with those where the woman was over 40 years of age (7.2%); where normal semen was used; where higher numbers of embryos were replaced per patient (9.7% with one, 14.6% with two, 19.3% with three, and 24.1% with four or more); and where the women presented with secondary infertility. Of the 523 confinements reported, 457 were singleton deliveries; 57 twin deliveries (10.9%); 7 triplet deliveries (1.3%); and two quadruplet deliveries (one set was born after January 1984). The cesarean section rate was 49%. No infant was reported to be born with a chromosomal abnormality. Nine conceptuses from spontaneous abortions were reported to have a chromosomal abnormality, but this is likely to be an underestimate since not all underwent chromosome analysis. There were 9 other severe fetal defects, including intrauterine fetal death (1.5%). Results of this collaborative study show that in vitro fertilization is widely accepted as a method for the treatment of infertility and does not carry a higher than normal risk of fetal abnormalities.

Pregnancy proteins in seminal plasma, seminal vesicles, preovulatory follicular fluid, and ovary

A number of proteins previously thought to be specific for the placenta or pregnancy have been identified in the fluids bathing both the oocyte and the sperm. In many cases their concentrations in follicular fluid and seminal plasma greatly exceeded those in the serum of nonpregnant women or men, and sometimes they even exceeded the levels in pregnancy sera. We report here the occurrence of PP5, PP12, PP14 and PAPP-A in follicular fluid and seminal plasma. In follicular fluid, the levels of PP5, PP12, and PAPP-A correlate with the estrogen concentration of the same fluid, and the PP12 and PAPP-A levels also bear a positive correlation to the progesterone concentration. The levels of PP12 and PAPP-A increase as the follicle grows, as do the levels of many steroid hormones. Therefore, the apparent correlations observed may be merely coincidental. However, circumstantial evidence from other reproductive organs indicates that the synthesis of PP12 and PAPP-A is stimulated by progesterone. Results of immunohistochemical staining show that PP12 and PAPP-A are localized in the luteinized granulosa cells and the corpus luteum. Previous studies indicate that PP5 and PAPP-A inhibit the action of proteolytic enzymes plasmin and elastase, which are believed to be involved in the mechanisms of ovulation. The study of the significance of these various placental proteins for human reproduction is only at its beginning. Clearly, elucidation of their function is the key to a more fundamental understanding of their role in the events governing ovulation and implantation.