Pregnancy, Microchimerism, and the Maternal Grandmother

A WOMAN OF REPRODUCTIVE AGE OFTEN HARBORS A SMALL NUMBER OF FOREIGN CELLS, REFERRED TO AS MICROCHIMERISM: a preexisting population of cells acquired during fetal life from her own mother, and newly acquired populations from her pregnancies. An intriguing question is whether the population of cells from her own mother can influence either maternal health during pregnancy and/or the next generation (grandchildren).Microchimerism from a woman's (i.e. proband's) own mother (mother-of-the-proband, MP) was studied in peripheral blood samples from women followed longitudinally during pregnancy who were confirmed to have uncomplicated obstetric outcomes. Women with preeclampsia were studied at the time of diagnosis and comparison made to women with healthy pregnancies matched for parity and gestational age. Participants and family members were HLA-genotyped for DRB1, DQA1, and DQB1 loci. An HLA polymorphism unique to the woman's mother was identified, and a panel of HLA-specific quantitative PCR assays was employed to identify and quantify microchimerism. Microchimerism from the MP was identified during normal, uncomplicated pregnancy, with a peak concentration in the third trimester. The likelihood of detection increased with advancing gestational age. For each advancing trimester, there was a 12.7-fold increase in the probability of detecting microchimerism relative to the prior trimester, 95% confidence intervals 3.2, 50.3, p<0.001. None of the women with preeclampsia, compared with 30% of matched healthy women, had microchimerism (p = 0.03).These results show that microchimerism from a woman's own mother is detectable in normal pregnancy and diminished in preeclampsia, supporting the previously unexplored hypothesis that MP microchimerism may be a marker reflecting healthy maternal adaptation to pregnancy

Comparing HLA Shared Epitopes in French Caucasian Patients with Scleroderma

Although many studies have analyzed HLA allele frequencies in several ethnic groups in patients with scleroderma (SSc), none has been done in French Caucasian patients and none has evaluated which one of the common amino acid sequences, 67FLEDR71, shared by HLA-DRB susceptibility alleles, or 71TRAELDT77, shared by HLA-DQB1 susceptibility alleles in SSc, was the most important to develop the disease. HLA-DRB and DQB typing was performed for a total of 468 healthy controls and 282 patients with SSc allowing FLEDR and TRAELDT analyses. Results were stratified according to patient’s clinical subtypes and autoantibody status. Moreover, standardized HLA-DRß1 and DRß5 reverse transcriptase Taqman PCR assays were developed to quantify ß1 and ß5 mRNA in 20 subjects with HLA-DRB1*15 and/or DRB1*11 haplotypes. FLEDR motif is highly associated with diffuse SSc (χ2 = 28.4, p<10−6) and with anti-topoisomerase antibody (ATA) production (χ2 = 43.9, p<10−9) whereas TRAELDT association is weaker in both subgroups (χ2 = 7.2, p = 0.027 and χ2 = 14.6, p = 0.0007 respectively). Moreover, FLEDR motif- association among patients with diffuse SSc remains significant only in ATA subgroup. The risk to develop ATA positive SSc is higher with double dose FLEDR than single dose with respectively, adjusted standardised residuals of 5.1 and 2.6. The increase in FLEDR motif is mostly due to the higher frequency of HLA-DRB1*11 and DRB1*15 haplotypes. Furthermore, FLEDR is always carried by the most abundantly expressed ß chain: ß1 in HLA DRB1*11 haplotypes and ß5 in HLA-DRB1*15 haplotypes

Early Developing Pig Embryos Mediate Their Own Environment in the Maternal Tract

The maternal tract plays a critical role in the success of early embryonic development providing an optimal environment for establishment and maintenance of pregnancy. Preparation of this environment requires an intimate dialogue between the embryo and her mother. However, many intriguing aspects remain unknown in this unique communication system. To advance our understanding of the process by which a blastocyst is accepted by the endometrium and better address the clinical challenges of infertility and pregnancy failure, it is imperative to decipher this complex molecular dialogue. The objective of the present work is to define the local response of the maternal tract towards the embryo during the earliest stages of pregnancy. We used a novel in vivo experimental model that eliminated genetic variability and individual differences, followed by Affymetrix microarray to identify the signals involved in this embryo-maternal dialogue. Using laparoscopic insemination one oviduct of a sow was inseminated with spermatozoa and the contralateral oviduct was injected with diluent. This model allowed us to obtain samples from the oviduct and the tip of the uterine horn containing either embryos or oocytes from the same sow. Microarray analysis showed that most of the transcripts differentially expressed were down-regulated in the uterine horn in response to blastocysts when compared to oocytes. Many of the transcripts altered in response to the embryo in the uterine horn were related to the immune system. We used an in silico mathematical model to demonstrate the role of the embryo as a modulator of the immune system. This model revealed that relatively modest changes induced by the presence of the embryo could modulate the maternal immune response. These findings suggested that the presence of the embryo might regulate the immune system in the maternal tract to allow the refractory uterus to tolerate the embryo and support its development

Monocarboxylate transporter 8 modulates the viability and invasive capacity of human placental cells and fetoplacental growth in mice

Monocarboxylate transporter 8 (MCT8) is a well-established thyroid hormone (TH) transporter. In humans, MCT8 mutations result in changes in circulating TH concentrations and X-linked severe global neurodevelopmental delay. MCT8 is expressed in the human placenta throughout gestation, with increased expression in trophoblast cells from growth-restricted pregnancies. We postulate that MCT8 plays an important role in placental development and transplacental TH transport. We investigated the effect of altering MCT8 expression in human trophoblast in vitro and in a Mct8 knockout mouse model. Silencing of endogenous MCT8 reduced T3 uptake into human extravillous trophoblast-like cells (SGHPL-4; 40%, P<0.05) and primary cytotrophoblast (15%, P<0.05). MCT8 over-expression transiently increased T3 uptake (SGHPL-4∶30%, P<0.05; cytotrophoblast: 15%, P<0.05). Silencing MCT8 did not significantly affect SGHPL-4 invasion, but with MCT8 over-expression T3 treatment promoted invasion compared with no T3 (3.3-fold; P<0.05). Furthermore, MCT8 silencing increased cytotrophoblast viability (∼20%, P<0.05) and MCT8 over-expression reduced cytotrophoblast viability independently of T3 (∼20%, P<0.05). In vivo, Mct8 knockout reduced fetal:placental weight ratios compared with wild-type controls at gestational day 18 (25%, P<0.05) but absolute fetal and placental weights were not significantly different. The volume fraction of the labyrinthine zone of the placenta, which facilitates maternal-fetal exchange, was reduced in Mct8 knockout placentae (10%, P<0.05). However, there was no effect on mouse placental cell proliferation in vivo. We conclude that MCT8 makes a significant contribution to T3 uptake into human trophoblast cells and has a role in modulating human trophoblast cell invasion and viability. In mice, Mct8 knockout has subtle effects upon fetoplacental growth and does not significantly affect placental cell viability probably due to compensatory mechanisms in vivo

The pendulum swings: Tolerance versus priming to NIMA

Fetal and/or perinatal exposure to noninherited maternal antigens (NIMA) has been reported to induce NIMA-specific tolerance. This tolerant state is highly beneficial in transplantation settings; enhanced graft acceptance has been observed when transplanted tissues express NIMA. Reduction in severe graft-vs-host disease has also been noted when bone marrow grafts originate from donors exposed to NIMA in early life. However, there is emerging evidence that exposure to NIMA can alternatively lead to specific priming. The processes regulating tolerance versus priming to NIMA are poorly understood and probably multifactorial. Based on studies in both humans and mice, we propose that both the quality and the quantity of NIMA exposure will be found to be key determinants of these opposing outcomes

Increased maternal T cell microchimerism in the allogeneic fetus during LPS-induced preterm labor in mice

Fetal surgery is a promising strategy to treat fetuses with severe congenital abnormalities but its clinical applications are often limited by preterm labor. In normal pregnancy, multiple mechanisms protect the semi-allogeneic fetus from attack by maternal T cells. Maternal microchimerism (the presence of maternal cells in the fetus) has been suggested to be one mechanism of maternal-fetal tolerance in that it exposes the fetus to non-inherited maternal antigens and leads to the generation of fetal regulatory T cells that can suppress a maternal T cell response. Preterm labor may represent a breakdown of this robust tolerance network. We hypothesized that during inflammation-associated preterm labor, maternal leukocytes cross the maternal-fetal interface and enter the fetal circulation. Consistent with this hypothesis, we found that during preterm labor in mice, the percentage of maternal microchimerism in fetal blood increased and the frequency of fetuses with high levels of trafficking (greater than 0.5%) also increased. Finally, we showed that the maternal leukocytes trafficking into the fetus are primarily Gr-1(+) cells in both syngeneic and allogeneic pregnancy, while T cell trafficking into the fetus specifically increases during allogeneic pregnancies. Our results demonstrate that trafficking of maternal leukocytes during pregnancy is altered during preterm labor. Such alterations may be clinically significant in affecting maternal-fetal tolerance

Maternal and fetal microchimerism in granulocytes

Cell trafficking during pregnancy may result in durable microchimerism, both fetal microchimerism in the mother and maternal microchimerism in her children. Whether microchimerism is continuously replenished has not been well-described. To address this question, we isolated granulocytes, cells with relatively short half-lives, from peripheral blood of healthy women. CD66b-positive cells were isolated by fluorescence activated cell sorting and a panel of polymorphism-specific quantitative pCR assays was employed to investigate fetal and maternal microchimerism. Overall 33% (10/30) of study subjects had at least one source of microchimerism in CD66b+ cells. Interestingly, maternal microchimerism was more common than fetal microchimerism, 40% vs. 15%, respectively (p = 0.05) and was present at higher levels (p = 0.03). The identification of maternal and fetal origin CD66b+ cells is strong evidence for an active microchimeric hematopoietic stem and progenitor cell niche. Furthermore, microchimeric CD66b+ cells could have an impact on innate and adaptive immune responses