Transgenerational Microchimerism in Pregnancy Loss

描述（由申请人提供）：微嵌合体（Mc）是指从遗传上不同的个体携带少量细胞或DNA。在怀孕期间，Mc是在母亲和胎儿之间的细胞交换中自然获得的。在先前的研究中，我们发现母亲的细胞在她的后代中一直存在到成年。在怀孕期间，已经从母亲那里感染了Mc的女性会获得额外的Mc来源，因为来自孕体的细胞和无细胞DNA进入她的循环。这些观察结果提出了一个问题，即跨代HLA关系是否会影响女性的妊娠结局，并且由于遗传多样性通常被认为是好的，跨代过度的HLA共享是否会导致复发性特发性妊娠丢失（RPL）。HLA分子是免疫应答的核心，用于区分自我和“其他”，并且广泛的多态性是HLA基因的标志性特征。由于HLA基因的多态性，大多数时候家庭成员之间的HLA等位基因存在许多差异。然而，偶尔增加的HLA共享观察到的家庭，无论是由于HLA纯合性或杂合HLA身份。以前的研究表明，过度的HLA共享的一个女人和她的合作伙伴与特发性RPL，虽然研究一直相互矛盾。该R21提案的第一个具体目标将检验以下假设：与活产且无流产史的先证者相比，当女性先证者患有原发性特发性RPL时，三代人的HLA关系具有较少的HLA差异（共享增加）。将对原发性特发性RPL女性及其母亲、孕体和伴侣进行DRB 1、DRB 3、DRB 4、DRB 5、DQA 1、DQB 1、A、B和C的HLA基因分型。具体目标2将识别和定量先证者母亲（MP-Mc）在妊娠前、妊娠期间和妊娠后的连续血液样本中的Mc，这些先证者患有原发性特发性RPL，随后流产或活产，健康女性无流产史。为此，开发了一组HLA特异性和其他遗传多态性特异性定量PCR检测，并将用于检测外周血单核细胞。特定目标3将使用与目标2相同的方法定量相同外周血样本中先证者孕体（CP-Mc）的Mc，以检测外周血单核细胞和血清。除了目标1的假设外，还将在目标2和3中检验第二个假设，即Mc的动态变化（MP-Mc或CP-Mc或两者）与特发性RPL相关。从多个来源携带Mc的后果和长期影响在很大程度上是未知的，因为从妊娠中自然获得的Mc只是最近才被认识到。据我们所知，目前还没有研究特发性RPL的HLA共享或跨代Mc的研究。携带少量源自遗传上不同的个体的细胞（或DNA）被称为微嵌合体（Mc）。女性从自己的母亲那里获得Mc，后来又从自己的怀孕中获得Mc，这一发现提出了一个问题，即跨代细胞群之间的相互作用有时是否会影响怀孕成功。因为它们有助于区分一个细胞与另一个特定的基因，称为HLA基因，是特别感兴趣的研究。

DESCRIPTION (provided by applicant): Microchimerism (Mc) refers to harboring a small number of cells or DNA from a genetically distinct individual. During pregnancy Mc is naturally acquired in the exchange of cells between a mother and conceptus. In prior studies we found that a mother's cells persist in her progeny into adult life. During pregnancy a woman who is already host to Mc from her mother acquires an additional source of Mc as cells and cell-free DNA from the conceptus enter her circulation. These observations raise the question of whether HLA-relationships across generations influence the outcome of pregnancy in women and, as genetic diversity is generally thought to be good, whether excessive HLA-sharing across generations contributes to recurrent idiopathic pregnancy loss (RPL). HLA molecules are central to immune responses, to distinguishing self from "other" and extensive polymorphism is the hallmark feature of HLA genes. Due to the polymorphism in HLA genes most of the time there are numerous differences in HLA alleles among family members. However, occasionally an increase of HLA-sharing is observed in families, either due to HLA-homozygosity or heterozygous HLA-identity. Previous studies have suggested that excessive HLA-sharing of a woman and her partner is associated with idiopathic RPL, although studies have been conflicting. The first Specific Aim of this R21 proposal will test the hypothesis that HLA-relationships over three generations have less HLA-disparity (increased sharing) when women probands have primary idiopathic RPL compared to probands with a live birth and no history of miscarriage. HLA-genotyping will be conducted for DRB1, DRB3, DRB4, DRB5, DQA1, DQB1, A, B and C for women with primary idiopathic RPL, their mothers, conceptus, and partners. Specific Aim 2 will identify and quantify Mc from the proband's mother (MP-Mc) in consecutive blood samples from before, during and after pregnancy for probands with primary idiopathic RPL with a subsequent miscarriage or with a live birth and healthy women with no history of miscarriage. For this purpose a panel of HLA-specific and other genetic polymorphism specific quantitative PCR assays has been developed and will be employed to tested peripheral blood mononuclear cells. Specific Aim 3 will quantify Mc from the conceptus of the proband (CP-Mc) in the same peripheral blood samples using the same methods as in Aim 2 to test peripheral blood mononuclear cells as well as serum. In addition to the hypothesis of Aim 1, a second hypothesis will be tested in Aims 2 and 3, that dynamic changes in Mc, either MP-Mc or CP-Mc or both, is associated with idiopathic RPL. The consequences and long-term effects of harboring Mc from multiple sources are largely unknown as naturally acquired Mc from pregnancy has only recently been recognized. To our knowledge there are no prior studies investigating HLA-sharing or Mc across generations in idiopathic RPL. Harboring a small number of cells (or DNA) that originated from a genetically distinct individual is referred to as microchimerism (Mc). The finding that women harbor Mc from their own mothers and later acquire Mc from their own pregnancy(ies) raises questions about whether interactions between cell populations across generations sometimes influences pregnancy success. Because they help distinguish one cell from another particular genes, called HLA genes, are of special interest to investigate.