Serum activin A and inhibin A. New clinical markers for hydatidiform mole

Serum and urine profiles of TGF-β superfamily members in reproductive aged women

BACKGROUND

TGF-β superfamily members are important biomarkers of reproductive health in women desiring fertility and during pregnancy. TGF-β proteins derived from the ovary and/or placenta have been detected in serum in women, but there have been very few attempts to measure them non-invasively, such as in urinary samples, and to compare them to serum concentrations.

METHODS

We measured inhibin A, inhibin B, total inhibin, AMH, activin A, activin B, activin AB, follistatin, the GDF-9/BMP-15 complex, and GDF-15 in paired serum and urine samples from healthy reproductive aged women and in pregnant (second trimester) women.

RESULTS

We detected all hormones in serum in both pregnant and non-pregnant women. Inhibin A, total inhibin, activin A, activin AB, follistatin, and GDF-15 were significantly higher in pregnant than in non-pregnant women. GDF-15 was the only hormone consistently detected in urine. We also measured, for the first time, the GDF-9/BMP-15 functional heterodimer and the GDF-15 protein harboring the H202D polymorphism.

CONCLUSIONS

We report the successful measurement of the GDF-9/BMP-15 heterodimer (its native form) in serum and the ability to measure GDF-15 non-invasively, in urinary samples. This novel GDF-15 assay also captures the antigen in the presence of a common genetic variant.

Invasive hydatidiform mole: immunohistochemical labelling of inhibin/activin subunits, Ki67, p53 and glycodelin A in a rare case

Invasive trophoblastic mole is an extremely rare condition. Its early recognition is essential since it can transform into an invasive type of tumour. Immunohistochemistry was performed with monoclonal antibodies against inhibin-alpha, -betaA and -betaB, Ki67, p53 and glycodelin A in a rare case of accidentally diagnosed invasive trophoblastic mole. There was labelling of the inhibin/activin subunits, Ki67 and p53, while glycodelin A showed minimal immunopositivity. Therefore, since the pathological diagnosis of an invasive mole is difficult, the immunohistochemical detection of inhibin/activin subunits, Ki67, p53 and glycodelin A might be additional useful tumour markers.

Single serum activin a testing to predict ectopic pregnancy

CONTEXT

Ectopic pregnancy (EP) is an important cause of maternal deaths in early pregnancy because most fatal cases result from delayed diagnosis and inappropriate investigation.

OBJECTIVE

We evaluated whether the measurement of activin A may be useful in the diagnosis of EP in women with unknown pregnancy location.

DESIGN

The study was designed as an open observational study.

SETTING

The study was set in a tertiary referral center for obstetric care.

PATIENTS

Patients were women with unknown pregnancy location (n = 536) who had complaints of bleeding, pain, or cramping.

INTERVENTIONS

Interventions included clinical examination; transvaginal ultrasound scan; human chorionic gonadotropin (hCG), progesterone, and activin A measurements; laparoscopy; uterine curettage; and histological examination.

MAIN OUTCOME MEASURES

Main outcome measures were pregnancy outcomes and evaluation of sensitivity, specificity, and predictive values of hCG, progesterone, and activin A as diagnostic tests for the detection of EP.

RESULTS

Pregnancy outcomes included 155 (28.9%) viable intrauterine pregnancies (IUP), 305 (56.9%) first-trimester spontaneous abortion (SAB), and 76 (14.2%) EP. SAB had the lowest (P < 0.0001) hCG and progesterone concentrations, significantly lower than EP (P < 0.001) and IUP (P < 0.001). In EP, levels were significantly (P < 0.001) lower than in IUP. On the contrary, activin A levels were lowest (P < 0.0001) in EP, significantly lower than in SAB (P < 0.001) and IUP (P < 0.001). IUP had significantly (P < 0.001) lower activin A levels than SAB. When evaluated by the receiver operating curve analysis, activin A at the cutoff of 0.37 ng/ml combined a sensitivity and a specificity of 100 and 99.6%, respectively, for prediction of EP. When activin A concentrations were below the cutoff, the positive predictive value for EP was 97.43%, and 0% for concentrations higher than 0.37 ng/ml.

CONCLUSIONS

Activin A measurement may identify patients at risk of EP with a high sensibility and specificity.

TGF-β superfamily expression and actions in the endometrium and placenta

Transforming growth factor β (TGFβ) superfamily members are closely associated with tissue remodelling events and reproductive processes. This review summarises the current state of knowledge regarding the expression and actions of TGFβ superfamily members in the uterus, during the menstrual cycle and establishment of pregnancy. TGFβs and activin β subunits are abundantly expressed in the endometrium, where roles in preparation events for implantation have been delineated, particularly in promoting decidualisation of endometrial stroma. These growth factors are also expressed by epithelial glands and secreted into uterine fluid, where interactions with preimplantation embryos are anticipated. Knockout models and embryo culture experiments implicate activins, TGFβs, nodal and bone morphogenetic proteins (BMPs) in promoting pre- and post-implantation embryo development. TGFβ superfamily members may therefore be important in the maternal support of embryo development. Following implantation, invasion of the decidua by fetal trophoblasts is tightly modulated. Activin promotes, whilst TGFβ and macrophage inhibitory cytokine-1 (MIC-1) inhibit, trophoblast migration in vitro, suggesting the relative balance of TGFβ superfamily members participate in modulating the extent of decidual invasion. Activins and TGFβs have similar opposing actions in regulating placental hormone production. Inhibins and activins are produced by the placenta throughout pregnancy, and have explored as a potential markers in maternal serum for pregnancy and placental pathologies, including miscarriage, Down’s syndrome and pre-eclampsia. Finally, additional roles in immunomodulation at the materno-fetal interface, and in endometrial inflammatory events associated with menstruation and repair, are discussed.

Inhibins in female and male reproductive physiology: role in gametogenesis, conception, implantation and early pregnancy

A great deal of new information has arisen in the recent years concerning inhibin physiology and clinical relevance in reproductive medicine. It is now recognized that the two inhibin isoforms, named inhibin A and inhibin B, are produced by the gonads in the course of gamete maturation and in women have a different pattern of secretion throughout the menstrual cycle. Since inhibins are also produced by placenta and fetal membranes, it has been suggested that there is an involvement in physiological adaptation of pregnancy. Evidence from several sources has underlined the clinical usefulness of the measurement of inhibin-related proteins in the diagnosis and follow-up of different fertility disturbances and early pregnancy viability. In the male, inhibin B is produced in the testis, principally by the Sertoli cells. Inhibin B expression and secretion are positively correlated with Sertoli cell function, sperm number, and spermatogenic status and are negatively correlated with FSH. This review covers the most recent advances on the role of inhibins in human reproductive function. Considerable progress in the understanding of inhibin physiology has resulted from selective measurement of the two inhibin molecular forms, named inhibin A and B. Newly recognized alterations of inhibin levels in gynaecological diseases as well as in normal and pathological pregnancy are discussed, with particular emphasis on the potential clinical usefulness of assessing inhibin levels in serum and other biological fluids.

Second-trimester maternal serum markers in twin pregnancy with complete mole: report of 2 cases

We present second-trimester serum marker levels in cases of twin pregnancy with complete hydatidiform mole and a coexistent fetus (CHMCF). Second-trimester inhibin A (InhA) levels have not been previously reported in such cases. Second-trimester maternal serum screening, alpha-fetoprotein (AFP), unconjugated estriol (uE3), human chorionic gonadotropin (hCG), and InhA measurements combined with maternal age to estimate a patient's risk of Down syndrome during pregnancy was performed as a routine prenatal test in 2 cases of CHMCF. Hospital records containing serum marker data, patient history, pathology reports, and pregnancy outcome were reviewed. In cases of CHMCF, maternal serum AFP and uE3 levels were similar to those of a normal singleton pregnancy, whereas hCG and InhA levels were markedly increased. Second-trimester maternal serum marker profiles in cases of CHMCF are a composite of normal singleton and molar tissue secretions. We have found, for the first time, that second-trimester InhA levels are markedly increased in these cases. Serum marker levels may be useful in diagnosis of CHMCF, prenatal counseling, and evaluation of risk for persistent trophoblastic disease.

Advances in the clinical laboratory detection of gestational trophoblastic disease

BACKGROUND

Gestational trophoblastic disease (GTD) consists of a spectrum of disorders that are characterized by an abnormal proliferation of trophoblastic tissue. Gestational trophoblastic neoplasia (GTN) refers to a subset of GTD with a persistently elevated serum hCG in the absence of a normal pregnancy and with a history of normal or abnormal pregnancy. Although previously a lethal disease, GTN is considered today the most curable gynecologic cancer. However, a delay in the diagnosis may increase the patient's risk of developing malignant GTN, and therefore the prompt identification of GTN is important.

SERUM MARKERS

hCG test is essential for detection of GTN. It has emerged that there are problems with hCG tests. In addition to regular hCG, at least five major variants of hCG are present in serum samples. False-positive hCG (phantom hCG) can occur in the absence of GTN. Low-level real hCG may occasionally persist in the absence of clinical evidence of pregnancy or GTD. Alternatively, low-level real hCG may be due to pituitary hCG. Other placental hormones, human placental lactogen (hPL), inhibin and activin, and progesterone have also been evaluated as tumor markers for GTD.

CONCLUSION

hCG has high diagnostic sensitivity, approaching 100% sensitivity, for managing the treatment of GTN and for detecting recurrences of disease. It is recommended to use hCG test that recognizes all forms of the hCG molecule. In cases where low-level hCG persists, it must be differentiated whether it is real or false. Real-hCG may be due to quiescent gestational trophoblastic disease or pituitary hCG. It has not yet been established whether measurement of markers other than hCG (hPL, inhibin, activin, and progesterone) is useful in the detection and follow-up of GTD.

Inhibins and activins in pregnancy

Human placenta, decidua, and fetal membranes are the major sites of production and secretion of inhibin A and activin A in maternal serum, amniotic fluid, and umbilical cord blood. These tissues also express follistatin-related gene and betaglycan, the binding proteins of activin A and inhibin A, respectively, recently identified. They show a different expression throughout pregnancy, suggesting new functional roles into gestational tissues. The availability of suitable assays for measuring inhibin A and activin A lead us the possibility to investigate their secretion in healthy pregnancy. In addition, several evidences underline the potential role and the clinical usefulness of their measurement in the diagnosis, prevention, prognosis and follow-up of different gestational pathologies such as: threatened abortion, placental tumors, hypertensive disorders of pregnancy, intrauterine growth restriction, fetal hypoxia. The measurement of inhibin A and activin A into the biological fluids of pregnancy will offer in the future further possibilities in early diagnosis, prediction, and monitoring pregnancy diseases.

Maternal serum inhibin A levels may predict pregnancy outcome in women with threatened abortion

Determination of maternal serum inhibin A in women with threatened abortion may be helpful in predicting the failure of pregnancies.

The TGF-beta superfamily and its roles in the human ovary and placenta

The transforming growth factor-beta (TGF-beta) superfamily consists of a large group of growth and differentiation factors, such as TGF-betas, activins, inhibins, growth and differentiation factors (GDFs), and bone morphogenetic proteins (BMPs). These molecules act through specific receptor complexes that are composed of type I and type II serine/threonine receptor kinases. The receptor kinases subsequently activate Smad proteins, which then propagate the signals into the nucleus to regulate target gene expression. Several ligands in this family, such as TGF-betas, activins, inhibins, BMP-15, and GDF-9, play important roles in regulating human ovarian functions, including follicle development and maturation. Activin and TGF-beta are also involved in regulating placental development and functions. Abnormal expression or function of these ligands has been found in several pathological conditions. This review summarizes the role of the TGF-beta superfamily in human ovarian and placental regulation and function, and the potential clinical implications.

Paracrine regulation of endometrial function: interaction between progesterone and corticotropin-releasing factor (CRF) and activin A

Under the influence of ovarian steroid hormones, endometrial cells aer able to produce a wide variety of growth factors and peptide hormones that area believed to promote: (1) physiological growth and differentiation during the endometrial cycle; (2) decidualization, an essential preparative event for establishment of pregnancy; and (3) pathological growth and differentiation in endometriosis and cancer. Among the local factors produced by the human endometrium, corticotropin-releasing factor (CRF) and activin A have been evaluated in terms of localization and effects. CRF is a neuropeptide expressed by the epithelial and stromal cells of the human endometrium in increasing amounts from the endometrial proliferative to the secretory phase. CRF expression also increases in the pregnant endometrium, from early in the pregnancy until term. CRF-type 1 receptor mRNA is only expressed by stromal cells. Progesterone induces CRF gene expression and release from decidualized cells and CRF decidualizes cultured stromal endometrial cells. Urocortin, a CRF-related peptide, has been identified in endometrial epithelial and stromal cells, and its function is still under investigation. Activin A is a growth factor expressed in increasing amounts throughout endometrial phases by both epithelial and stromal cells. This growth factor is secreted into the uterine cavity with higher levels in the secretory phase. Maternal decidua expresses activin A mRNA in increasing amounts from early pregnancy until term. Human endometrium also expresses activin-A receptors and follistatin, its binding protein. Activin A decidualizes cultured human endometrial stromal cells (an effect reversed by follistatin) and modulates embryonic trophoblast differentiation and adhesion. Activin A is expressed in endometriosis and endometrial adenocarcinoma.

Activin a plasma levels at birth: an index of fetal hypoxia in preterm newborn

Activin-A is a growth factor involved in cell growth and differentiation, neuronal survival, early embryonic development and erythropoiesis. Hypoxemia is a specific trigger for increasing activin-A in fetal lamb circulation. We tested the hypothesis that fetal hypoxia induces activin-A secretion in preterm newborn infants. Fifty newborn infants with gestational ages ranging from 26 to 36 wk were enrolled in a prospective study performed at the Pediatrics, Obstetrics and Reproductive Medicine Department, University of Siena, Italy. Heparinized blood samples were obtained from the umbilical vein after cord clamping, immediately after delivery. Activin A, hypoxanthine (Hx), xanthine (Xa) plasma levels and absolute nucleated red blood cell (NRBC) count were measured. Activin-A levels (p < 0.0001) and NRBC (p < 0.0001) were significantly higher in hypoxic than in non hypoxic preterm newborns. Cord activin A levels were significantly related with Hx (taua=0.64, taub=0.64, p < 0.0001) and Xa (taua=0.56, taub=0.57, p < 0.0001) levels, NRBC ((taua=-0.45, taub=-0.46, p < 0.0001) count; pH (taua=-0.47, taub=-0.48, p < 0.0001) and base deficit (taua=-0.36, taub=0.-0.36, p = 0.0002). Preterm newborns with signs of perinatal hypoxia at birth have increased activin-A levels, suggesting that activin-A may reflect indirectly intrauterine hypoxia.

Inhibin alpha distinguishes hemangioblastoma from clear cell renal cell carcinoma

Inhibin alpha subunit (inhibin A) expression in hemangioblastomas has not been previously reported in the literature. We analyzed the expression of inhibin A in 25 hemangioblastomas from 22 patients. Eleven cases were from 8 patients with von Hippel-Lindau disease, and these tumors were multicentric and/or recurrent. The remaining 14 cases from 14 patients were sporadic. The male-to-female ratio was 8:3, and the age at presentation ranged from 19 to 78 years (mean 35 years; median 45 years). Eighteen tumors were located in the cerebellum/posterior fossa, 1 in the medulla, 1 in the occipital lobe, and 5 in the spinal cord. Four metastatic renal cell carcinomas in brain, 10 renal cell carcinomas from 8 patients with von Hippel-Lindau disease, and 5 sporadic clear cell renal cell carcinomas were also included. Two patients with von Hippel-Lindau disease had both renal cell carcinoma and hemangioblastoma. The stromal cells of all 25 cases of hemangioblastoma expressed inhibin A. Strong, moderate, and weak cytoplasmic immunoreactivity was noted in 17, 5, and 3 cases, respectively. In contrast, none of the 19 renal cell carcinomas, primary as well as metastatic, expressed inhibin A. There was no difference in the inhibin A staining pattern between the sporadic hemangioblastoma and those associated with VHL. These findings demonstrate inhibin A to be a useful marker in distinguishing hemangioblastoma from metastatic clear cell renal cell carcinoma. While the diagnostic importance is evident, the pathophysiology of inhibin A expression by the stromal cells of hemangioblastoma remains unknown and further investigation is required.

Inhibin A, inhibin B and activin A concentrations in umbilical cord artery and vein

Activin A and inhibins (A and B) are growth factors expressed during pregnancy by the human placenta, decidua and fetal membranes, and by several fetal organs. They are secreted in both the maternal and the fetal circulations, but the net contribution of the fetus to inhibins/activin A production is still unclear. In the present study we determined whether there was a difference in the serum concentration of activin A, inhibin A and inhibin B between the artery and vein of the umbilical cord. Arterial and venous umbilical cord blood was obtained immediately before elective Cesarean section of 16 term infants from uncomplicated pregnancies. Inhibins and activin A levels were assayed by specific enzyme-linked immunosorbent assays. The paired t-test and linear regression analysis were used to calculate statistical significance. Inhibin A levels did not differ between the artery and vein of the umbilical cord. In contrast, arterial inhibin B levels were significantly (p < 0.001) lower, and activin A concentrations significantly (p < 0.05) higher than the respective venous concentrations. A significant correlation between arterial and venous levels of inhibin A (r = 0.591; p < 0.05), inhibin B (r = 0.749; p < 0.0001) and activin A (r = 0.571; p < 0.05) was found. The present findings suggest that the human placenta is the main source of inhibin B, and the fetus of activin A, in the umbilical cord. In light of the possible roles played by inhibin and activin in erythroid differentiation, protection of neurons against brain injury and modulation of adrenal and pancreatic hormone release, the present data may be of help in evaluating their changes in the umbilical cord when gestational diseases occur.