Immunologic mechanisms in the maternal-fetal relationship

Reproductive immunology in viviparous mammals: evolutionary paradox of interactions among immune mechanisms and autologous or allogeneic gametes and semiallogeneic foetuses

Literally, reproductive immunology was born in bovine on-farm reproduction where seminal experiments intended for developing methods for embryo transfer in cattle were performed. Actually, these experiments led to two of major concepts and fundamental principles of reproductive immunology using the bovine species as a model for biomedical research, namely the concept of acquired immunological tolerance and the paradox of the semiallogeneic bovine foetus whereby such organism can develop within an immunologically competent host. Peter Medawar, a scientist who together with Frank Macfarlande Burnet shared the 1960 Nobel Prize in physiology or medicine for discovery of acquired immunological tolerance, while studying dizygotic cattle twins, thereby giving birth to reproductive immunology. Also, these findings significantly influenced development of organ transplants and showed that using farm animals as models for studying transplantation immunology had general relevance for mammalian biology and health including those of humans. However, the interest for further research of the fascinating maternal immune influences on pregnancy and perinatal outcomes and of the prevention and treatment of immunologically mediated reproductive disorders in viviparous mammals of veterinary relevance by veterinary immunologists and reproductive clinicians have been very scarce regarding the application of nonspecific immunomodulatory agents for prevention and treatment of subfertility and infertility in pigs and cattle, but still broadening knowledge in this area and hold great potential for improving such therapy in the future. The aim of the current overview is to provide up-to-date information and explaining/translating relevant immunology phenomena into veterinary practice for specialists and scientists/clinicians in reproduction of animals.

Immunologic regulation in pregnancy: from mechanism to therapeutic strategy for immunomodulation

The immunologic interaction between the fetus and the mother is a paradoxical communication that is regulated by fetal antigen presentation and/or by recognition of and reaction to these antigens by the maternal immune system. There have been significant advances in understanding of abnormalities in the maternal-fetal immunologic relationship in the placental bed that can lead to pregnancy disorders. Moreover, immunologic recognition of pregnancy is vital for the maintenance of gestation, and inadequate recognition of fetal antigens may cause abortion. In this paper, we illustrate the complex immunologic aspects of human reproduction in terms of the role of human leukocyte antigen (HLA), immune cells, cytokines and chemokines, and the balance of immunity in pregnancy. In addition, we review the immunologic processes of human reproduction and the current immunologic therapeutic strategies for pathological disorders of pregnancy.

Novacor LVAD bridge to transplantation in peripartum cardiomyopathy

We report the case of a 22-year-old woman suffering from peripartum cardiomyopathy who was successfully bridged to cardiac transplantation with a Novacor left ventricular assist device (LVAD). Her course with the device is presented and emphasis is put on the size mismatch between the patient and the device, a fact with normally precludes the implantation of the Novacor LVAD.

Thyroid disease and pregnancy

Thyroid disease is common in younger women and may be a factor in reproductive dysfunction. This probably only applies to severe cases of hyper- or hypothyroidism. Once adequately treated, neither of these disorders significantly impacts on fertility. The key is to recognize and to treat thyroid disorders in the reproductive-age woman before conception. Thyroxine therapy and even antithyroid drug therapy should be continued during pregnancy as necessary. Pregnancy is a euthyroid state that is normally maintained by complex changes in thyroid physiology. The fetal and neonatal hypothalamic-pituitary-thyroid system develops independently, but it may be influenced by thyroid disease in the mother. Early pregnancy is characterized by an increase in maternal T4 secretion stimulated by hCG and an increase in TBG, resulting in the elevated total serum T4 in pregnancy. The debate continues as to whether maternal T4 is important in early or late fetal brain development. If so, the physiologic changes in thyroid hormone secretion and transport in early pregnancy would help to ensure that a sufficient amount of thyroid hormone was available. There is new evidence in human subjects that substantial maternal T4 can cross the placenta during pregnancy, and this may be particularly important when fetal thyroid function is compromised as a result of congenital hypothyroidism. Maternal and fetal/neonatal outcomes in pregnancy are adversely affected if severe hypothyroidism is undiagnosed or inadequately treated. Thyroid function tests should be obtained during gestation in women taking T4 and appropriate dose adjustments should be made for TSH levels outside a normal range. The TSH-receptor blocking antibodies from the mother are a recognized cause of congenital hypothyroidism in the fetus and neonate that can be permanent or transient. If neonatal hypothyroidism is detected through neonatal screening programs, and prompt and adequate T4 replacement therapy is instituted as soon as possible following delivery, subsequent growth and development are usually normal. Paradoxically, pregnancy often has a favorable effect on the course of maternal Hashimoto's disease, although there is the risk of relapse postpartum. Pathophysiologic conditions of hCG secretion such as gestational trophoblastic disease and hyperemesis gravidarum may present as thyrotoxicosis in pregnancy, but the main cause of this syndrome is Graves' disease. The mainstay of treatment is antithyroid drugs and either propylthiouracil or methimazole may be used safely. Subtotal thyroidectomy, after medical control, is the alternative treatment, but radioiodine ablation is contraindicated.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunological factors responsible for pathogenetic cell degeneration in pregnancy

The placenta has an important role as an immunological barrier during pregnancy. When the placental barrier is disrupted, materno-embryonic transfusion takes place. Several clinical reports relate congenital malformations or abortion to intrauterine bleeding or transplacental transfusion. In an earlier experiment, pathogenetic cell degeneration was induced using an in vitro whole rat embryo culture. Transplacental transfusion was simulated by intracardiac injection of an allogeneic rat-antirat serum directed against the blood group antigens. The present study examines the morphological and immunological effects on the development of rat embryos 9 to 10 days old (stages 8-10 somites) of the separate administration of primary allogeneic antisera, obtained 10-17 days after immunization, and secondary allogeneic antisera, obtained after booster immunization on day 45-52. Rat-antirat alloantibodies were directed against the blood group antigens. Transplacental transfusion was simulated by the embryonic intracardiac microinjection of approximately 0.5 microliters serum enriched with either primary or secondary obtained allogeneic antibodies. After 48 hours' incubation, the embryos were examined microscopically, and it appeared that the secondary antisera, which had hemolytic activity, was more potent (P less than 0.005) in the induction of pathogenetic cell degeneration. It is well known that IgG antibodies display hemolytic activity. This finding was confirmed by direct immunofluorescence performed on rat embryos 2, 4, and 6 hours after injection, where incubation with rabbit-antirat anti-IgG antibodies gave a strong reaction. The hypothesis discussed is whether or not pathogenetic cell degeneration subsequent to transplacental transfusion of maternal antibodies can be initiated by similar immunological events.

Immunological induction of endometritis-model investigations in cows

The course of the inflammatory reaction in the uterus after local or systemic administration of specific or non-specific antigens was studied. The study was carried out on 40 cows, 10-11 weeks after labour and between 6 and 8 days after ovulation. A specific cell-mediated type of reaction was induced by intrauterine challenge with PPD in cows previously vaccinated with M. bovis subcutaneously or by intrauterine administration. A specific inflammatory process of the type of Arthus reaction was induced by intrauterine challenge with C. fetus ssp. veneralis in animals immunized with these bacteria subcutaneously or by intrauterine instillation of these bacteria. A non-specific inflammatory process in the uterus was initiated by one instillation of lipopolysaccharide (LPS) into the left uterine horn. The cells were washed out from the uterus before and 6, 24, 48 and 72 hours after initiation of the specific or non-specific inflammatory process. The per cent proportions of various cell types were determined. It was demonstrated that intrauterine instillation of specific or non-specific antigens in cows caused a significant rise in PMNs per cent in relation to the control group.

Peripartum myocarditis and cardiomyopathy

The clinical and pathologic features of 18 consecutive patients with peripartum cardiomyopathy at The Johns Hopkins Hospital were examined in an attempt to define the incidence of myocarditis and to determine its response to immunosuppressive agents. In addition to routine studies, patients were evaluated with echocardiography, nuclear ventriculography, right heart catheterization, and myocardial biopsy. Fourteen of the 18 patients (78%) showed evidence of myocarditis. Of these, 10 were treated with immunosuppressive therapy. Nine of the 10 treated patients with myocarditis had subjective and objective improvement. Follow-up endomyocardial biopsies in these patients showed resolution or substantial improvement in myocarditis. Four patients with myocarditis not treated with immunosuppressives also improved. All patients improving spontaneously presented with congestive heart failure within 1 month of delivery and improved dramatically within days of presentation. Four of the 18 patients showed no evidence of myocarditis. Of these, two improved, and two deteriorated (both requiring cardiac transplantation). None of these four patients were treated with immunosuppressive therapy. We conclude that in patients with peripartum cardiomyopathy, 1) the etiology remains unclear although myocarditis was present in 78% of those with this condition, 2) resolution of myocarditis is associated with significant improvement in left ventricular function, 3) myocarditis may resolve spontaneously without detectable loss of cardiac function, and 4) immunosuppressive therapy in patients with myocarditis and persistent left ventricular dysfunction may improve left ventricular function and prognosis.

[Which immunologic mechanisms facilitate a successful pregnancy]

Three possibilities are discussed for the immunological mechanisms which may be operative in establishing and maintaining a successful grafting of a semiallogenic embryo: (1) The lack of maternal allogenic recognition due to either the absence or a decreased alloantigenicity of paternal alloantigens (HLA). (2) The local suppression of maternal immune reactions against the embryo by hormonally induced decidual suppressor cells and by molecules released from the placenta. (3) The placenta may serve as an immunological barrier filtering potentially cytotoxic cells and molecules out of the maternal circulation before they reach the fetus.

Human leukocyte antigen compatibility in a couple with idiopathic recurrent hydramnios

Recurrent hydramnios of unknown cause is a very rare obstetric complication. Only three cases have been reported. We report a case of idiopathic recurrent hydramnios associated with human leukocyte antigen compatibility between the patient and her husband.