Current trends in reproductive immunology: an overview

In women with thyroid autoimmunity, does low-dose prednisolone administration, compared with no adjuvant therapy, improve in vitro fertilization clinical results?

AIM

The objective of the study was to verify if prednisolone treatment may influence the in vitro fertilization (IVF) outcome in euthyroid women affected by thyroid autoimmunity.

METHODS

One hundred and ninety-four patients including 60 positive for antithyroid antibodies (ATA) underwent the ovarian stimulation in the standard long protocol for IVF and 30 women received the low-dose prednisolone from the day of oocyte retrieval.

RESULTS

The overall, clinical pregnancy and live birth rate in ATA-positive patients receiving prednisolone supplementation was significantly higher when confronted with ATA-positive untreated subjects (60.0% vs 30.0%, P = 0.02; 46.6% vs 16.6%, P = 0.03; and 46.6% vs 20.0%, P = 0.05, respectively). The same parameters in ATA-positive untreated women were significantly lower than in the controls (30.0% vs 50.7%, P = 0.0001; 16.6% vs 38.1%, P = 0.04; and 20.0% vs 40.3%, P = 0.04, respectively).

CONCLUSION

There is a strong association between the presence of thyroid autoantibodies and poor IVF outcome. The prednisolone co-treatment may improve the clinical pregnancy rate and reduce the miscarriage rate after IVF in women affected by thyroid autoimmunity.

Thyroid autoimmunity, infertility and miscarriage

Thyroid autoimmunity (TAI), infertility and miscarriage are currently issues of extreme interest that have attracted the attention of many investigators. Several papers have been published, focusing on women of childbearing age that include healthy women, women with recurrent miscarriage and those undergoing assisted conception. Most of these studies show a significant association between the presence of thyroid autoantibodies, infertility and a higher miscarriage rate. The underlying pathogenetic mechanisms, which might explain the association between TAI and infertility, remain speculative given the scarce information from animal models and from in vitro data addressing the potential effects of TAI on fertility. Adequate levels of circulating thyroid hormones are of primary importance for normal reproductive function and inadequate delivery of triiodothyronine to granulosa and stromal cells may disrupt normal female reproductive function. With regards to the association between TAI and miscarriage, a close relationship has been largely confirmed in recent studies. The aim of this review is to present the relevant information published so far in the literature regarding TAI and miscarriage in euthyroid female individuals.

Expression of a novel dipeptidyl peptidase 8 (DPP8) transcript variant, DPP8-v3, in human testis

AIM

To investigate the role of a novel dipeptidyl peptidase 8 transcript variant (DPP8-v3) gene in testis development and/or spermatogenesis.

METHODS

A human testis cDNA microarray was hybridized with mRNA of human adult and fetal testes. Differentially expressed clones were sequenced and characterized and their expression was analyzed by real-time reverse transcription polymerase chain reaction (RT-PCR) and Southern-blot analysis.

RESULTS

A new transcript variant of the human dipeptidyl peptidase (DPP8), exhibiting a 5-fold higher expression level in human adult than that in fetal testes, was cloned and was named DPP8 variant 3 (DPP8-v3). The full-length sequence of DPP8-v3 was 3,030 bp, encoding a protein of 898 amino acids.

CONCLUSION

DPP8-v3 is a novel human DPP8 transcript variant highly expressed in the adult testis. Similar to DPPIV, DPP8-v3 may play a key role in the immunoregulation of testes and accordingly may influence spermatogenesis and male fertility.

Antithyroid antibodies do not affect pregnancy outcome in women undergoing assisted reproduction

The purpose of this study was to determine the association of antibodies to thyroglobulin and thyroid peroxidase and pregnancy outcome in women undergoing assisted reproductive techniques. The study included three centres and retrospectively evaluated patient sera for antithyroid antibodies, then related the results to pregnancy outcome. Enzyme-linked immunosorbant assays for thyroglobulin and thyroid peroxidase antibodies were performed using two different commercially available kits. Controls included 200 healthy women of reproductive age. Women (n = 873) who were undergoing assisted reproductive techniques for pelvic adhesions, endometriosis, ovarian dysfunction, or unexplained/other were included. All women utilized a standard regimen of gonadotrophin releasing hormone agonist down-regulation followed by ovulation induction. Embryos were cultured for 3 days, at which time embryo transfer occurred. Statistical analysis utilized the two-tailed Fisher's exact test. Antithyroid antibodies were positive in 143 of 873 (16.4%) women undergoing assisted reproductive techniques while 29 of 200 (14.5%) normal controls were positive (not significant). Deliveries were achieved in 396 of 730 (54.2%) of women who had no thyroid antibodies versus 78 of 143 (54.5%) of women who had thyroid antibodies (not significant). No difference in biochemical pregnancies (not significant) or clinical pregnancy losses (not significant) were detected. Antithyroid antibodies were found no more frequently in women undergoing assisted reproductive techniques than in normal controls. There were no differences in pregnancy outcome based on antithyroid antibody positivity in women undergoing assisted reproductive techniques. These data do not support the testing or treatment for antithyroid antibodies of women undergoing assisted reproductive techniques.

Increased prevalence of antithyroid antibodies identified in women with recurrent pregnancy loss but not in women undergoing assisted reproduction

OBJECTIVE

To assess the prevalence of antibodies to thyroglobulin and thyroid peroxidase (or microsomal) in women with recurrent pregnancy loss and women undergoing assisted reproductive techniques (ART) compared with healthy controls.

DESIGN

Retrospective, two-centered study.

SETTING

University-affiliated private patient centers.

PATIENT(S)

Included were 700 women with a history of two or more consecutive pregnancy losses, 688 women with a history of infertility who were undergoing ART, and 200 healthy, reproductive-aged female controls.

INTERVENTION(S)

Blood was collected before ART cycles, frozen, and assayed.

MAIN OUTCOME MEASURE(S)

Standardized ELISAs were used to measure antithyroid antibodies and TSH levels. Statistical analysis was performed with use of the two-tailed Fisher's exact test.

RESULT(S)

Antithyroid antibodies were identified in 29 of 200 (14.5%) of controls and 158 of 700 (22.5%) of women with recurrent pregnancy loss and 132 of 688 (19.2%) of women undergoing ART. Less than 20% of the women with antithyroid antibodies were clinically hypothyroid.

CONCLUSION(S)

Antithyroid antibodies are identified more frequently in women with recurrent pregnancy loss than in controls but not in women undergoing ART. These autoantibodies may be markers of autoimmune activation and have been associated with an increased risk of pregnancy loss and postpartum thyroid disease.

The presence of antithyroid antibodies in euthyroid patients with unexplained infertility and tubal obstruction

PROBLEM

The presence of antithyroid antibodies in euthyroid patients with unexplained infertility and tubal obstruction.

METHOD

The presence of antithyroid autoantibodies (microsomal and thyroglobulin) was measured in 40 patients with unexplained infertility, and 40 patients with tubal obstruction infertility, and compared to 40 healthy nulligravidae.

RESULTS

Eight patients (20%) in the unexplained infertility study group, seven (17.5%) in the tubal obstruction group and two (5%) in the healthy nulligravida group, were positive for antithyroid autoantibodies: five (12.5%) were positive for antimicrosomal antibodies, two (5%) were positive for antithyroglobulin antibodies, and one patient (2.5%) was positive for both. The tubal obstruction group comprised seven (17.5%) patients positive for antithyroid autoantibodies: four (10%) for antimicrosomal antibodies, two (5%) for antithyroglobulin antibodies, and one patient (2.5%) was positive for both. In the healthy nulligravidae group only two patients (5%) were positive for antithyroid antibodies: one for antimicrosomal and one for antithyroglobulin. No significant differences were found in the presence of antithyroid antibodies between patients with unexplained infertility and those with tubal obstruction infertility. Both groups differed significantly from the healthy controls with regard to the presence of antithyroid antibodies (P < 0.05).

CONCLUSION

Subclinical presence of antithyroid autoantibodies is characteristic of both unexplained and mechanical infertility, as opposed to healthy controls. Further investigation of larger groups is needed to determine the prevalence of antithyroid antibodies in the unique population of infertile women.

Circulating autoimmune antibodies may be responsible for implantation failure in in vitro fertilization

OBJECTIVE

To investigate the role of autoimmune factors as a possible cause for implantation failure as manifested by chemical pregnancy after IVF and ET.

DESIGN

Anticardiolipin, anti-double-stranded DNA (dsDNA), antinuclear antibody, lupus anticoagulant, and rheumatoid factor serum levels were examined in patients with chemical pregnancies and in matched controls.

SETTING

An IVF unit, university-based IVF program.

PATIENTS

The study group included 21 patients who had one or more chemical pregnancies and no deliveries. The control group consisted of 21 patients who had conceived and delivered after IVF-ET treatment, without any history of fetal wastage, matched for age, type and duration of infertility, and number of previous IVF cycles.

RESULTS

The incidence of circulating autoimmune antibodies in the study group was 33.3% (7/21). Three patients (14.2%) were positive for anticardiolipin, two (9.5%) were positive for antidsDNA, one (4.7%) for antinuclear factor, and one (4.7%) for rheumatoid factor. Autoimmune antibodies were not detected in any of the control group.

CONCLUSION

Autoimmunity may play a role in implantation failure in IVF-ET. Circulating autoimmune antibody screening is therefore recommended after chemical pregnancy.

Ovarian failure and autoimmunity. Detection of autoantibodies directed against both the unoccupied luteinizing hormone/human chorionic gonadotropin receptor and the hormone-receptor complex of bovine corpus luteum

We developed an ELISA system for the detection of human anti-ovarian antibodies. Bovine corpora lutea were extracted in PBS (pH 7.2) and fractionated by ultracentrifugation. Both the soluble fraction obtained after 80,000 g (S80) and the Triton-extracted membrane fraction (ST288) were used as antigens. Additionally, the luteinizing hormone (LH)/human chorionic gonadotropin (hCG) receptor was isolated by affinity chromatography (wheat germ agglutinin and LH-Sepharose) and also used as an antigen. In 7 of 14 patients with primary sterility and endometriosis a positive reaction was observed. Similarly, 6 of 16 patients with secondary sterility and endometriosis were also positive. Patients being stimulated for in vitro fertilization and presenting either primary or secondary sterility were positive in 5 of 22 and 6 of 16 cases, respectively. In the S80 test 41 of 60 sera presented IgG2 antibodies, whereas in the ST288 test 38 of 60 belonged to the IgG1 subclass. Kappa and lambda chains were equally distributed. Some patients could recognize the unoccupied LH/hCG receptor as an antigen, while others recognized only the complex formed by the hormone plus the hormone receptor. The S80 and ST288 antigens were isolated by affinity chromatography. Gel permeation of the purified antigens revealed in each case the presence of an antigen complex. The apparent molecular weight was between 2,000 and 36,000 D. Cross-reactivity studies using affinity-purified antibodies demonstrated an antigenic relationship of the membrane, soluble, and extractable fractions. NAc-(beta-1----4)-D-glucosaminide and -D-galactopyranoside were the main terminal glycosides.

Presence of autoantibodies in women with unexplained infertility

Serum samples from 41 patients suffering from unexplained infertility and 351 normal pregnant women were assayed for a range of autoantibodies by means of immunofluorescence, counterimmunoelectrophoresis, double immunodiffusion, Western blots, and enzyme-linked immunosorbent assays. The prevalence of autoantibodies to smooth muscle, phospholipid, and nuclear antigens, the latter when detected by immunofluorescence, was elevated in women with infertility compared with normal pregnant women (p less than 0.001, less than 0.001, and less than 0.05, respectively). Antiviral antibodies were not detected. The reason for the high level of autoreactivity in infertile women is unclear, but smooth muscle and antiphospholipid antibodies may actively interfere with the reproductive process.

Existence of suppressor cells in the spleen of allogeneic and syngeneic primiparous pregnant mice

Mixed lymphocyte reaction (MLR) and in vitro induction of cytolytic cells against alloantigens were investigated using spleen cells from primiparous mice mated allogeneically or syngeneically. One-way MLR was reduced significantly in degree not only in allogeneic but also in syngeneic pregnant mice. MLR of virgin spleen cells was suppressed when mitomycin C-treated spleen cells taken from syngeneic or allogeneic pregnant mice were added as regulator cells. These suppressive effects disappeared when regulator cells were treated with anti-Thy 1 or anti-Lyt 2 serum plus complement. Generation of cytotoxic lymphocytes from syngeneic or allogeneic pregnancy spleen cells in MLR was depressed compared with that from virgin spleen cells. The addition of pregnancy spleen cells to MLR suppressed in vitro generation of cytotoxic lymphocytes from virgin spleen cells. These results indicated that reduction of in vitro cellular responses of pregnancy spleen cells was due to suppressor cells in the spleens. These cells suppressed non-specifically the reactions to alloantigens and could be detected both in allogeneic and syngeneic primiparous pregnancies.

T helper lymphocyte depression in early human pregnancy

Peripheral blood lymphocyte subclasses were determined in 60 women with normal pregnancies, 20 from each trimester, and in 20 controls using automated flow cytofluorimetry. The cells were stained with the monoclonal antibodies OKT3, OKT4 and OKT8 to stain total T cells, T helper and T suppressor-cytotoxic lymphocytes, respectively. A polyvalent rabbit anti-human Ig serum was used to stain B lymphocytes. Absolute numbers of T lymphocytes were significantly reduced in both the first and second trimesters. This was due to a significant decrease in T helper lymphocytes and a smaller, statistically not significant, reduction in the number of T suppressor lymphocytes. There was no significant change in lymphocyte subclasses during the third trimester. Total lymphocyte numbers were normal throughout pregnancy.