Immunodystrophism, T cells, cytokines, and pregnancy failure

Effects of castration and eucalyptus oil supplementation on growth performance, nutrient digestibility, and blood-immunity indicators of male Holstein calves

The purpose of this study was to investigate the effects of early castration and eucalyptus oil (EUC) supplementation on dry matter intake (DMI), growth performance, and immune response of Holstein calves. Fifty-six male Holstein calves 52 d old and with an initial body weight (BW) of 63.5 ± 5.27 kg were used. The animals were blocked by BW and randomly assigned into 1 of the 4 treatment groups in a randomized complete block design with a 2 (no castration vs. castration) × 2 (without vs. with EUC) factorial arrangement of treatments. The treatments were (1) uncastrated calves fed without EUC, (2) uncastrated calves fed 0.5 g/d EUC (EUC group), (3) castrated calves (steers) fed without EUC (castrated group), and (4) steers fed with 0.5 g/d EUC (castrated + EUC). The experiment was 8 wk long, including pre- and postweaning (weaned at 72 d). The EUC × castrated interactions were not significant for DMI, growth performance, nutrient digestibility, and immune response. Castration did not affect the DMI, final BW, average daily gain (ADG), or feed efficiency, except that the ADG was greater for bull calves than for steers at postweaning. Supplementation with EUC increased DMI pre- and postweaning and increased the ADG of weaned calves. Digestibility in the total digestive tract was not affected by castration (except for organic matter digestibility), whereas adding EUC improved the digestibility of dry matter, acid detergent fiber, and crude protein. Blood concentration of IL-6 at d 94 was decreased by feeding EUC. These results indicate that the EUC could be fed to either intact or castrated dairy calves to promote growth and health postweaning; castration before weaning may reduce ADG and cause inflammatory stress without affecting feed intake or feed efficiency.

IL-1β, IL-2 and IL-4 concentration during porcine gestation

In pigs, given the type of epitheliochorial and non-invasive placenta, the trophoblast is in intimate contact with maternal tissues. The dialogue established between the conceptus and the endometrium involves, among others, the immune system, which minimizes the chances of rejection of the embryo and promotes the establishment of pregnancy. The aim of this work was to determine the concentration of IL-1β, IL-2 and IL-4 in sera and in extracts of maternal and fetal placenta from sows of different gestational periods. Reproductive tracts from 23 crossbreed sows, between 30 and 114 days of gestation (dg), and from 8 non-pregnant sows were used. The concentration of the cytokines was determined by ELISA. IL-1β, IL-2 and IL-4 demonstrated a similar pattern of concentration at the placental interface and serum; they were found elevated in tissues at 30 and 60-70 dg, and significantly decreased at term, period in which the cytokines were significantly increased in serum. These results show that IL-1β, IL-2, and IL-4 are differentially modulated during pregnancy and at term, and suggest an important role of these cytokines in defining the proinflammatory stage of these periods.

Increased interferon-gamma- and interleukin-4-synthesizing subsets of circulating T lymphocytes in pregnant asthmatics

BACKGROUND

Pregnancy frequently interferes with the course of bronchial asthma, and asthmatic pregnant women experience less successful pregnancies. T lymphocytes synthesizing IL-4 or IFN-gamma are important in allergic mechanisms of the airways as well as in materno-fetal immunity.

OBJECTIVE

We hypothesized that pregnancy (a T helper-2 polarized state) of asthmatics will enhance the number of circulating T2 lymphocytes, but decrease the subset-producing IFN-gamma (T1 lymphocytes) and thereby cause a culminating T2 dominance with possible clinical consequences.

METHODS

IL-4- or IFN-gamma-producing T lymphocytes were determined by flow cytometry in healthy (n=8) and asthmatic (n=13) non-pregnant women and healthy (n=18) and asthmatic (n=48) pregnant women of similar chronological and gestational (2nd-3rd trimester) age and asthma severity (Global Initiative for Asthma II-III).

RESULTS

In the blood of non-pregnant women--healthy or asthmatic--the numbers of IL-4- and IFN-gamma+ T cells were very low (<10/microL blood). In contrast, in asthmatic pregnant women, the cell counts were 182+/-27 and 39+/-6 for IFN-gamma+ and IL-4+ T cells/microL blood, respectively (both P<0.05 vs. respective control values of non-pregnant asthmatics). Within the asthmatic pregnant group, significant negative correlations were revealed between the numbers of IFN-gamma+ or IL-4+ T cells and maternal peak expiratory flow as well as birth weight of newborns (both P<0.05).

CONCLUSION

These data show a previously unknown immunological interference between asthma and pregnancy. The culminating proliferation of IFN-gamma+ and IL-4+ T lymphocytes may potentially impair maternal airway symptoms as well as fetal development.

Maternal plasma transforming growth factor-beta1 concentrations in preeclamptic and normotensive pregnant Zimbabwean women

OBJECTIVE

We examined the relationship between maternal plasma transforming growth factor-beta1 (TGF-beta1) concentrations and risk of preeclampsia among women delivering at Harare Maternity Hospital in Zimbabwe. We evaluated the relationship in the context of maternal systemic inflammation using plasma tumor necrosis factor-a soluble receptor p55 (sTNFp55) as a marker.

METHODS

132 women with preeclampsia and 180 controls were included in this case-control study analysis. Maternal post-diagnosis plasma TGF-beta1 and sTNFp55 concentrations were determined using immunoassays. Logistic regression procedures were used to estimate odds ratios (OR) and 95% confidence intervals (CI) adjusted for confounders.

RESULTS

A linear increase in preeclampsia risk was observed with increasing quartiles of TGF-beta1 concentrations (p<0.01). Women whose TGF-beta1 concentrations were >or=25.1 ng/ml (quartile 4) had a 2.5-fold (95% CI 1.2-5.6) increased risk of preeclampsia as compared with those women whose concentrations were <11.2 ng/ml (quartile 1). Relative to women with no evidence of systemic inflammation and no elevated TGF-beta1 concentrations, those women who were jointly positive for elevated TGF-beta1 and sTNFp55 concentrations experienced a 5.3-fold (95% CI 2.3-12.0) increased risk of preeclampsia.

CONCLUSION

Overall, we noted that elevated TGF-beta1 is associated with an increased risk of preeclampsia. We also noted that the preeclampsia risk is exaggerated in the presence of maternal systemic inflammation.

An update in recurrent spontaneous abortion

Recurrent spontaneous abortion (RSA) is defined as three or more consecutive pregnancy losses prior to the 20th week of gestation. The etiology of recurrent spontaneous abortion is often unclear and may be multifactorial, with much controversy regarding diagnosis and treatment. Reasonably accepted etiologic causes include, genetics, anatomical, endocrine, placental anomalies, hormonal problems, infection, smoking and alcohol consumption, exposure to environmental factors, psychological trauma and stressful life event, certain coagulation and immunoregulatory protein defects. Detection of an abnormality in any of these areas may result into specific therapeutic measures, with varying degrees of success. However, the majority of cases of RSA remains unexplained and is found to be associated with certain autoimmune (APA, ANA, ACA, ATA, AECA) and alloimmune (APCA, Ab2, MLR-Bf) antibodies that may play major role in the immunologic failure of pregnancy and may lead to abortion. Alteration in the expression of HLA-G molecules, T-helper-1 (Th-1) pattern of cytokines and natural killer (NK) cells activity may also induce abortion. Various forms of treatment like antithrombotic therapies such as aspirin and heparin, intravenous immunoglobulin (IVIg) therapy, immunotherapy with paternal lymphocytes and vitamin D3 therapy are effective mode of treatment for unexplained cause of fetal loss in women with RSA.

Immunoregulatory molecules during pregnancy and at birth

Regulation of the maternal immune response to the fetal allograft is essential for the success of pregnancy and delivery of a well-developed neonate. Numerous mechanisms have been postulated to mediate this. We hypothesised that the potent immunosuppressive molecules TGF-beta1 and IL-10 could contribute to this regulation in the mother and neonate during gestation. In comparison to non-pregnant women, TGF-beta1 and cortisol levels were increased significantly in mid (16-18 weeks) and late pregnancy (>37 weeks, no labour), with levels of both highest in late gestation. In contrast, IL-10 levels were significantly lower in maternal plasma in mid-gestation compared with that from late pregnancy and from non-pregnant women. TGF-beta1, IL-10 and cortisol were all detectable in umbilical cord blood plasma with TGF-beta1 levels significantly decreased in association with labour in contrast to cortisol levels that increased with labour. IL-10 levels in cord plasma were comparable to those of adults and did not change with mode of delivery. Elevated levels of TGF-beta1, but not IL-10, in the maternal and neonatal circulation could have a role in immunoregulation of the maternal response to the fetal allograft as well as growth and development of the fetus.

Type-1 and type-2 cytokines in human decidual tissue and trophoblasts from normal and abnormal pregnancies detected by reverse transcriptase polymerase chain reaction (RT-PCR)

PROBLEM

Cytokine expression at the maternal fetal interface has been well documented in rodents, but data in the human are scanty and controversial.

METHOD OF STUDY

We examined cytokine expression of human decidua and trophoblasts by semiquantitative visual grading of reverse transcriptase polymerase chain reaction (RT-PCR) products in five groups of patients: ten patients with uncomplicated term pregnancies undergoing elective cesarean section (Group 1); ten women having normal pregnancies at term and vaginal delivery (Group 2); ten patients having intrauterine growth-retarded infants of unknown cause after a spontaneous vaginal delivery at term (Group 3); ten childless women having their first, first-trimester spontaneous abortion (Group 4); and ten childless women with a history of one or more previous first-trimester spontaneous abortions and having a new miscarriage (Group 5).

RESULTS

Results favoring the T-helper 1 (Th1)/T-helper 2 (Th2) model during pregnancy were: significantly higher expression of interferon gamma (IFN-gamma) in trophoblast samples from Group 3 versus 2 and in decidual tissue from Group 5 versus 4; stronger positivity of interleukin (IL)-10 in decidual tissue samples from Group 1 versus Groups 2 and 5; and higher expression levels of tumor necrosis factor-beta (TNF)-beta by the trophoblast in Group 5 versus 1. Against the Th1/Th2 paradigm were the following findings: the significantly increased expression of IFN-gamma by decidual or trophoblast samples in Groups 1 versus 2, 2 versus 3, and 1 versus 5; and the significantly higher expression of TNF-alpha in decidual samples from patients in Group 1 (but also Group 4) as compared with Group 5. IL-2 mRNA and IL-4 mRNA could not be detected.

CONCLUSIONS

Overall, our findings suggest that there is a balance between type-1 and type-2 cytokines during pregnancy, which is mainly characterized by the expression of IFN-gamma (a type-1 cytokine) and IL-10 (a type-2 cytokine) at the maternal fetal interface.

Colony-stimulating factor-1 (CSF-1) expression in the uteroplacental unit of mice with spontaneous and induced pregnancy loss

CSF-1 plays an important role in female reproduction and normal embryo development. To understand further CSF-1 function in normal and, especially, in compromised pregnancy, we studied the pattern of its mRNA expression as well as expression of its receptor (c-fms) in the uteroplacental units of mice with induced (cyclophosphamide (CY)-treated) and spontaneous (CBA/J x DBA/2J mating combination) pregnancy loss. RNase protection analysis demonstrated the presence of two forms of CSF-1 mRNA in the uteroplacental unit corresponding to 1400- and 263-bp protective fragments. Densitometric analysis demonstrated that the level of 1400-bp mRNA form was decreased by 40% in the uteroplacental units of mice with CY-induced pregnancy loss compared with the control mice. About 20% decrease in 263-bp protective fragment was registered in resorbing versus non-resorbed placenta of CBA/J females mated to DBA/2J males. As judged by in situ hybridization assay, CSF-1 mRNA transcripts were localized in the uterine epithelium and stroma, while c-fms mRNA was found mainly in the trophoblast. The number of metrial gland cells as well as the number of uterine leucocytes expressing CSF-1 and c-fms mRNAs was substantially lower in the uteroplacental unit of mice with pregnancy loss than in control animals. Maternal immunostimulation, while significantly decreasing the resorption rate in mice with CY-induced pregnancy loss, also strengthened CSF-1 mRNA expression at the fetomaternal interface and resulted in reconstitution in the number of CSF-1+ uterine leucocytes and metrial gland cells. These data suggest a role for uterine CSF-1 in the physiology of normal and compromised pregnancy and demonstrate a possible involvement of CSF-1-associated signalling in mechanisms of placenta and endometrium repair following immunopotentiation.

Why did your mother reject you? Immunogenetic determinants of the response to environmental selective pressure expressed at the uterine level

PROBLEM

Maternal "rejection" of the implanted conceptus is considered to account for a significant proportion of miscarriages (abortions) in both humans and animals. Our understanding of mechanisms has been limited, and hence, explanations for nonrejection have remained largely speculative. Losses, when they occur, could represent either random accidental failure of protective mechanisms or a more purposeful discrimination.

METHOD OF STUDY

An analysis of the most recent data.

RESULTS AND CONCLUSIONS

The embryo is most akin to a parasite, and pregnancy is most akin to a host-parasite interaction. If one excludes chromosome abnormalities in the embryo as a cause of death, activation of coagulation mechanisms, leading to vasculitis affecting the maternal blood supply to the implanted embryo, appears to represent a major loss-causing mechanisms--a form of ischemic autoamputation. Proinflammatory T-helper (Th) 1-type cytokines trigger this process via upregulation of a novel prothrombinase, fgl2. Th2/3 cytokines, such as interleukin (IL)-4, IL-10, and transforming growth factor (TGF)-beta 2, may antagonize the processes involved. Cytokine balance is determined by the genetics of the mother, which regulate her response to stress; endotoxin (LPS); and paternal antigens, selectively expressed on the trophoblast of the embryo, via imprinting. Based on studies in abortion-prone mice, where immunity to paternal alloantigens prevents loss, three distinct gene products in the embryo are proposed to determine the cytokine response to maternal lymphomyeloid cells in the uterus.

Cytokine expression by first-trimester human chorionic villi

PROBLEM

Communication at the human maternal-fetal interface occurs by an intricate cytokine network. This study examines cytokine expression by normal first-trimester human chorionic villi.

METHOD OF STUDY

Tissues were obtained at elective pregnancy terminations (7-9 weeks). Total RNA was isolated from chorionic villi by guanidinium isothiocynate-acid phenol extraction. A reverse transcriptase-polymerase chain reaction technique was used to examine cytokine expression. beta-Actin was used as the housekeeping gene, and mitogen-stimulated lymphocytes served as positive controls.

RESULTS

beta-Actin was uniformly expressed by all chorionic villous samples. Interferon (IFN)-alpha and -beta also were highly expressed. Moderate expression was noted for interleukin (IL)-10, IL-6, tumor necrosis factor (TNF)-alpha, and IL-1 beta. In contrast, transforming growth factor-beta 1, IFN-gamma, IL-2, and IL-1 alpha were either weakly expressed or absent in first-trimester villi.

CONCLUSIONS

Cytokines may contribute to pregnancy immunotolerance (IFN-alpha, IFN-beta, and IL-10), viral resistance (IFNs), hormone secretion (IL-1 and IL-6), and cellular remodeling (IFN-gamma and TNF-alpha) within the chorionic villous.

Th1-type immunity is incompatible with successful pregnancy

Several years ago, the rather provocative question was raised: is successful pregnancy a T helper 2 (Th2) phenomenon? Implicit in this argument is the corollary that unsuccessful pregnancy is a Th1-type situation. Here, evidence from murine and human pregnancy is presented to show that, since Th1-type cytokines mediate pregnancy loss, a shift towards Th1-type immunity may help resolve 'unexplained' pregnancy failure.

Maternal anti-placental cell-mediated reactivity and spontaneous abortions

PROBLEM

Does Th1/Th2 balance determine pregnancy outcome, and if so, what determines Th1/Th2 balance in pregnancy?

METHOD

Review and synthesis of existing data.

RESULTS

A bias toward Th1 is strongly correlated with pregnancy failure in mice and humans. Pregnancy usually shifts the balance toward Th2 and placental factors/progesterone and progesterone-stimulated CD8+ T cell production of suppressor factor; TGFbeta2 and IL4/10 may be responsible. The bias toward a Th1 response may result from intracellular parasitic infection and other as yet undefined factors.

CONCLUSION

The Th1/Th2 balance thesis appears to be valid.