本长文共分三个部分，此篇为（一、8）第一部分内容的第8篇。
一、低生育力（不孕，RIF反复种植失败，RPL反复流产等，妊娠失败与妊娠病理）的生殖免疫学相关评估
前7篇链接
生殖免疫的核心：子宫内膜异位症和腺肌症的免疫炎症、生殖破坏、妊娠失败等相关病理生理（一、1）
1、免疫学检测在低生育能力（不孕症）临床环境中的作用The role of immunologic tests for subfertility in the clinical environment
Clearance
of senescent decidual cells by uterine natural killer cells in cycling human
endometriumElife .2017 Dec 11:6:e31274.在人类子宫内膜的周期变化中，经后内膜雌激素依赖性快速增长。排卵时，孕酮和细胞cAMP水平升高激活子宫内膜基质细胞(EnSCs)中的转录因子FOXO1，导致细胞退出细胞周期并分化为控制胚胎着床的蜕膜细胞（这是一个复杂纷繁的过程）。本研究发现FOXO1以IL-8依赖的方式引起蜕膜化EnSCs亚群的急性衰老。该亚群的选择性清除或富集表明，蜕膜衰老驱动了与子宫内膜容受性相关的短暂炎症反应。此外，在蜕膜化培养中，衰老细胞阻止子宫内膜间充质干细胞的分化。随着生殖周期的运行，IL-15激活子宫自然杀伤细胞(uNK)通过颗粒胞吐（granule exocytosis颗粒胞外分泌）机制选择性靶向和清除衰老蜕膜细胞。本研究表明，急性蜕膜衰老控制着胚胎着床时子宫内膜的更新和重塑，并证实uNK细胞在维持子宫内膜周期稳态中起着关键作用。子宫内膜异位症NK细胞功能缺陷，与异位病灶种植机制相关，同时也是子宫内膜异位症在位内膜病理原因之一，可能与本文研究机制具有关联性，是导致子宫内膜异位症和腺肌症患者蜕膜化缺陷产生的原因之一。
不同的哺乳动物采用不同的策略来确保胚胎成功植入。小鼠多个胚胎(平均6-8个)的同步植入依赖于循环中雌二醇(E2)的短暂上升，促使孕激素启动的子宫内膜具有接受性，并激活休眠的囊胚以植入。一旦突破子宫腔上皮层，植入的小鼠胚胎会触发子宫内膜基质层广泛重构的所谓蜕膜化过程，其特征是局部水肿，uNK细胞涌入，基质成纤维细胞分化为特化的蜕膜细胞，协调滋养细胞的侵袭和胎盘的形成。同样，人类子宫内膜短暂表达接受表型，在黄体中期持续2-4天。然而，这一植入窗口不受卵泡期E2激增的控制，这可能反映出多个人类胚胎的同步植入既不需要也不可取。此外，基质层的蜕膜化并不依赖于植入胚胎，而是在每个黄体中期开始，以响应周期性黄体酮水平升高和细胞内cAMP产生增加。同时，CD56brightCD16 uNK细胞在黄体期子宫内膜中积累。在怀孕期间，uNK细胞在协调血管适应和滋养细胞侵袭方面发挥着进化保守的作用，但它们在人类子宫内膜周期中的功能尚未完全清晰。人子宫内膜基质细胞(endometrial stromal cells，EnSCs)向蜕膜细胞的分化是一个多步骤的过程。在G0/G1退出细胞周期后，蜕膜化的EnSCs首先引发短暂的促炎反应，特征是自由基产生和各种趋化因子和其他炎症介质分泌。小鼠子宫暴露于这种炎症分泌蛋白激活了多个容受性基因，这表明小鼠的雌二醇分泌激增被人类子宫内的内源性炎症信号所取代。据称，反馈回路将炎症蜕膜反应限制在2-4天，与接下来的蜕膜期与植入的胚胎植入基质的时间重合。在此阶段，充分分化的蜕膜细胞现在紧密黏附并具有缝隙连接，在半同种异体孕体周围形成免疫特权基质。在没有着床的情况下，下降的孕酮水平触发第二次炎症性蜕膜反应，白细胞募集和激活后，导致内膜浅层组织破裂、局灶性出血和月经内膜脱落。无瘢痕组织修复涉及位于基底层的间充质干细胞样细胞(mesenchymal stem-like cells，MSCs)和上皮祖细胞的激活。月经后，卵泡E2水平升高促使组织快速生长，在约10天内使子宫内膜厚度增加数倍。临床上，子宫内膜生长不理想与生殖失败密切相关；但MSC活化后的强烈增殖如何与蜕膜化过程相关尚不清楚。FOXO1是一个核心的蜕膜转录因子，它根据分化信号控制EnSCs的细胞周期退出，并激活蜕膜标记基因如PRL（泌乳素）和IGFBP1（胰岛素样生长因子结合蛋白1）的表达。本研究证实FOXO1也诱导EnSCs亚群的急性衰老。发现衰老相关分泌表型(SASP)驱动与子宫内膜容受性相关的初始自身炎症蜕膜反应，并证据表明随着周期的进展，uNK细胞靶向并消除衰老蜕膜细胞。本文的发现揭示了一个迄今未被认识的急性细胞衰老在胚胎着床时的子宫内膜重塑中的作用；并表明uNK细胞在维持一个周期到另一个周期的组织稳态中起着重要作用。Decidualization induces acute senescence in a subpopulation of EnSCs蜕膜化诱导EnSC亚群急性衰老Figure 1 with 1 supplementDecidualization
induces acute senescence in a subpopulation of EnSCs.（A）Representative
SAβG staining in undifferentiated EnSCs (Day 0) or cells decidualized for the
indicated time points with 8-bromo-cAMP and MPA. Scale bar = 100 µm.
(B) SAβG activity, expressed in fluorescence intensity units (FIU), in
undifferentiated EnSCs (day 0) or cells decidualized for the indicated time
points. (C) Representative Western blot analysis of p53, p16, LMNB1,
HMGB2, mH2A, H3K9me3 and H.H1 levels in undifferentiated EnSCs and cells
decidualized for the indicated time points. β-actin served as a loading
control. (D) Left panel: representative immunofluorescence staining for
p16 expression in undifferentiated cells and cells decidualized for 8 days.
Nuclei were counterstained with DAPI. Scale bar = 50 µm. Right panel:
percentage of p16+ cells. (E) Left panel: representative
confocal microscopy images of undifferentiated (Day 0) or decidualized (Day 8)
EnSCs immune-probed for LMNB1, mH2A, H3K9me3 and H.H1. Scale bar = 10
µm. Right panel: nuclear size of undifferentiated EnSCs (n = 48) and
of cells first decidualized for 8 days with 8-br-cAMP and MPA (C + M)
(n = 48) was measured in three primary cultures. (F) Secretion
of IL-8, GROα, and IL-6 was measured in the supernatant of primary EnSCs
collected every 48 hr over an 8 day decidualization time-course. Data are
mean ±SEM of 3 biological replicates unless stated otherwise. **p<0.01, ***p<0.001.
Different letters above the error bars indicate that those groups are
significantly different from each other at p<0.05.、Figure 1—source data 1，Decidualization induces acute senescence
in a subpopulation of EnSCs.(A)在未分化EnSCs(第0天)或在指定时间点用8-brcamp-camp和MPA进行的蜕膜化细胞的代表性SAβG染色。比例尺= 100µm。(B) SAβG活性，在未分化的EnSCs(第0天)或在指定时间点蜕膜化的细胞中表达，以荧光强度单位(FIU)表示。(C)未分化的EnSCs和蜕膜化细胞中p53、p16、LMNB1、HMGB2、mH2A、H3K9me3和H.H1的代表性蛋白印迹分析。β-actin作为负载对照。(D)左图：未分化细胞和蜕膜化细胞p16表达的代表性免疫荧光染色。用DAPI对细胞核进行复染。比例尺=50µm。右图：p16+(阳性)细胞百分比。(E)左图：未分化(第0天)或蜕膜化(第8天)EnSCs免疫探针LMNB1、mH2A、H3K9me3和H.H1的代表性共聚焦显微镜图像。比例尺=10µm。右图：在三个原始培养中，测量了未分化的EnSCs（n=48）和用8-brcamp-cAMP和MPA（C+M）处理8天后首次出现树突状突起的细胞（n=48）的核大小。(F)在8天的蜕膜过程中，每48小时收集一次原代EnSCs的上清液，检测IL-8\GROα和IL-6的分泌。除非另有说明，数据是3个生物重复样本的均值±SEM。**p<0.01，***p<0.001。误差条上方的不同字母表示这些组在p<0.05时存在显著差异。Temporal regulation of senescent cell populations in cyclingendometrium子宫内膜周期变化中衰老细胞群的时相调控Senescent cells in
cycling human endometrium.(A)
Left panel: representative Western blot analysis of p53, p16, LMNB1, HMGB2,
mH2A, H3K9me3 and H.H1 levels in whole tissue biopsies from proliferative
endometrium (PE) and secretory endometrium (SE). β-actin served as a loading
control. Right panel: protein levels quantified relative to β-actin by
densitometry and expressed as arbitrary units (a.u.). (B) SAβG activity,
expressed in fluorescence intensity units (FIU)/mg protein, was measured in
biopsies from proliferative endometrium (PE; n= 7), early-secretory
(ES; n = 9), mid-secretory (MS; n = 38) and late-secretory
(LS; n = 19) endometrium. (C) Immunohistochemistry
demonstrating distribution of p16+ cells in the stromal
compartment and luminal epithelium. Scale bars = 200 µm. (D)
The abundance of p16+ cells during the luteal phase in
glandular epithelium, luminal epithelium and stroma compartment was analyzed by
color deconvolution using ImageJ software in 308 LH-timed endometrial biopsies
(average 48 samples per time point; range: 22 to 69). The centile graphs depict
the distribution of p16+ cells across the peri-implantation
window in each cellular compartment. Color key is on the right. Data are
mean ±SEM of 3 biological replicates unless stated otherwise. **p<0.01,
***p<0.001. Different letters above the error bars indicate that
those groups are significantly different from each other at p<0.05.Figure 2—source data 1，Senescent cells in cycling human endometrium.(A)左图：增殖期子宫内膜(PE)和分泌期子宫内膜(SE)全组织活检标本中p53、p16、LMNB1、HMGB2、mH2A、H3K9me3和H.H1的代表性蛋白印迹分析。β-actin作为负载对照。右图：通过密度测定法测定相对于β-肌动蛋白的蛋白质水平，并以任意单位(a.u)表示。(B) SAβG活性，以荧光强度单位(FIU)/mg蛋白表达，在增生的子宫内膜(PE;n = 7)、早期分泌(ES;n = 9)、分泌中期(MS;n = 38)和分泌晚期(LS;N = 19)子宫内膜。(C)免疫组化显示p16+细胞分布于间质室和腔上皮。比例尺= 200µm。(D)利用ImageJ软件对308例LH时子宫内膜活检标本(平均每个时间点48例;范围:22 ~ 69)。百分位图描述了每个细胞室中p16+细胞在植入期窗口的分布。颜色键在右边。除非另有说明，数据是3个生物重复样本的均数±SEM。**p<0.01，***p<0.001。误差条上方的不同字母表示这些组之间有显著差异，p<0.05。FOXO1 drives EnSC differentiation and senescence，FOXO1驱动EnSC分化和衰老Figure 3 with
1 supplement
A FOXO1/IL-8 axis
drives EnSC differentiation and senescence.(A)
SAβG activity in EnSCs either undifferentiated, or decidualized for 8 days with
8-bromo-cAMP, MPA, or a combination. (B) Top
left panel:FOXO1 mRNA levels in undifferentiated EnSCs and
cells treated with 8-br-cAMP and MPA (C + M) following transfection
with non-targeting (NT) or FOXO1 siRNA. Other panels: Secretion of IL-8, IL-6
and GROα was measured following FOXO1 knockdown in the supernatant of primary
EnSCs every 48 hr over an 8 day decidualization time-course. (C) SAβG
activity in EnSCs following transfection with NT or FOXO1 siRNA. The cultures
either remain untreated or decidualized for 8 days. (D) SAβG activity in
undifferentiated EnSCs treated for 8 days with increasing concentrations of
recombinant IL-8 and in cells decidualized for 8 days in the presence of
increasing concentrations of the CXCR2 antagonist, SB265610. (E) SAβG
activity in EnSCs following transfection with IL-8 siRNA. The cultures either
remain untreated or decidualized for 8 days. (F) PRL and IGFBP1 transcript
levels in EnSCs following transfection with IL-8 siRNA. The cultures either
remain untreated or decidualized for 8 days. (G) PRL and IGFBP1 expression
in undifferentiated EnSCs, cells decidualized for 8 days, and upon withdrawal
of 8-br-cAMP and MPA (C + M) for the indicated days. (H) Left
panel: SAβG activity in undifferentiated EnSCs, cells decidualized for 8 days,
and following withdrawal of C + M for the indicated days. Right
panel: representative Western blot analysis of p53, p16, LMNB1 and HMGB2 levels
in undifferentiated EnSCs, cells decidualized for 8 days, and following
withdrawal of C + M for the indicated days. β-actin served as a
loading control. Data are mean ±SEM of 3 biological replicates unless
stated otherwise. *p<0.05, **p<0.01 and ***p<0.005.
Different letters above the error bars indicate that those groups are
significantly different from each other at p<0.05.Figure 3—source data 1，A FOXO1/IL-8 axis drives EnSC
differentiation and senescence.图3附1 FOXO1/IL-8轴驱动EnSC分化和衰老。(A) 8-bromo-camp、MPA或两者联合作用下，未分化或蜕膜化8天的EnSCs的SAβG活性。(B)左上图：未分化的EnSCs和经8-br-cAMP和MPA (C + M)处理的细胞在转染非靶向(NT)或FOXO1 siRNA后的FOXO1
mRNA水平。其他图：在8天的蜕膜化过程中，每48小时检测FOXO1敲低后原代EnSCs上清液中IL-8、IL-6和GROα的分泌。(C)转染NT或FOXO1 siRNA后EnSCs中的SAβG活性。培养物不处理或蜕膜化8天。(D)在未分化的EnSCs中，随着重组IL-8浓度的增加处理8天，以及在CXCR2拮抗剂SB265610浓度的存在下蜕膜化8天的细胞中，SAβG活性。(E) IL-8 siRNA转染EnSCs后SAβG活性。培养物不处理或蜕膜化8天。(F)转染IL-8 siRNA后EnSCs中PRL和IGFBP1转录水平。培养物不处理或蜕膜化8天。(G) 未分化的EnSC、蜕膜化8天的细胞以及在指定天数内停用8-br-cAMP和MPA（C+M）后PRL和IGFBP1的表达。(H)左图：未分化的EnSCs，蜕膜化8天细胞，以及停用C + M后的SAβG活性。右图：未分化EnSCs、蜕膜化8天的细胞以及停用C+M指定天数后p53、p16、LMNB1和HMGB2水平的代表性蛋白质印迹分析。β-actin作为负载对照。除非另有说明，数据是3个生物重复样本的均数±SEM。*p<0.05，**p<0.01和***p<0.005。误差条上方的不同字母表示这些组之间有显著差异，p<0.05。Pleiotropic functions of senescent decidual cells衰老蜕膜细胞的多效性Figure 4 with
1 supplementFunctions of senescent
decidual cells.(A)
Pearson’s correlation analysis of SAβG activity in 75 matched undifferentiated
primary cultures and cultures decidualized for 8 days. (B)
Representative SAβG staining in undifferentiated (Day 0) and decidualizing
EnSCs (Day 8) following 4 days of pretreatment with vehicle, dasatinib (250 nM)
or palbociclib (1 μM). Scale bar= 100 µm. (C) PRL and IGFBP1 mRNA
expression in response to pretreatment with vehicle, dasatinib or palbociclib.
The cultures then remained undifferentiated or were decidualized for 8 days. (D)
IL-8, IL-6 and GROα secretion was measured every 48 hr in the supernatant of
primary EnSCs decidualized for the indicated time-points following pretreatment
with vehicle, dasatinib or palbociclib. (E) Colony forming unit (CFU)
activity in paired EnSC cultures that either remain undifferentiated (Day 0) or
were decidualized for 8 days (n = 10). (F) Left panel:
representative clonogenic assays established from EnSC cultures first
pretreated with vehicle, dasatinib or palbociclib and then decidualized for 8
days. Right panel: CFU activity in EnSC cultures first pretreated with vehicle,
dasatinib or palbociclib and then decidualized for 8 days. Data are
mean ±SEM of 3 biological replicates unless stated otherwise. *p<0.05,
**p<0.01 and ***p<0.001. Different letters above the error
bars indicate that those groups are significantly different from each other at
p<0.05.Figure 4—source data 1，Functions of senescent decidual cells.(A)对75个匹配的未分化原代培养物和蜕膜化8天的培养物的SAβG活性进行Pearson相关分析。(B)在溶剂、达沙替尼(250 nM)或哌柏西利(1 μM)预处理4天后，未分化(第0天)和蜕膜化(第8天)EnSCs的代表性SAβG染色。比例尺= 100µm。(C)溶剂、达沙替尼或哌柏西利预处理对PRL和IGFBP1 mRNA表达的影响。然后培养物保持未分化或蜕膜化8天。(D)经溶剂、达沙替尼或哌柏西利预处理后，每48小时检测蜕膜化原代EnSCs上清液中IL-8、IL-6和GROα的分泌。(E)在配对的EnSC培养中，要么保持未分化(第0天)，要么蜕膜化8天(n = 10)的集落形成单位(CFU)活性。(F)左图：用溶剂、达沙替尼或哌柏西利预处理EnSC，然后蜕膜化8天建立的代表性克隆生成分析。右图：先用溶剂、达沙替尼或哌柏西利预处理EnSC中的CFU活性，然后蜕膜化8天。除非另有说明，数据是3个生物样本重复的均数±SEM。*p<0.05，**p<0.01，***p<0.001。误差条上方的不同字母表示这些组之间有显著差异，p<0.05。Immune clearance of senescent decidual cells衰老蜕膜细胞的免疫清除Figure 5 with 1 supplement uNK cell mediated immune surveillance
and clearance of senescent cells.(A) Left panel: uNK cell density in
the subluminal stroma was quantified using a
standardized immunohistochemistry protocol in LH timed endometrial biopsies
(n= 1,997). Right panel: corresponding centile graph. Color code on
the left. (B) Left panel: example of the tissue distribution of CD56+ uNK
cells (brown staining) at LH + 10. Scale bar = 250 μm.
Right panel: Pearson’s correlation analysis of stromal cell and uNK cell
densities. A total of 80 randomly selected images from 20 biopsies were
analyzed. (C) Representative images of an eosin stained primary culture
decidualized for 8 days incubated for 18 hr with or without uNK cells isolated
from luteal phase endometrium. Scale bar = 100 μm. (D) SAβG
activity in undifferentiated or day eight decidualizedEnSCs co-cultured with or without uNK cells
in the presence or absence of the apoptosis inhibitor Z-VAD-FMK (Z-VAD, 10 μM)
or the granzyme activity inhibitor 3,4-DCI (25 μM). (E) Secretion of
IL-15 secretion was measured every 48 hr in the supernatant of primary EnSCs
decidualized for the indicated time-points following pretreatment with vehicle,
dasatinib (250 nM) or palbociclib (1 μM). (F) SAβG activity in
undifferentiated or day eight decidualized EnSCs co-cultured with or without
uNK cells in the presence or absence of an IL-15 blocking antibody (1 μg/ml).
Data are mean±SEM of 3 biological replicates unless stated otherwise.
Different letters above the error bars indicate that those groups are
significantly different from each other at p<0.05.Figure 5—source data 1，uNK cell mediated immune surveillance and
clearance of senescent cells.图5附1 uNK细胞介导的免疫监视和清除衰老细胞。(A)左图：在LH定时子宫内膜活检中，使用标准化的免疫组织化学方案对管腔下基质中的uNK细胞密度进行定量(n=1997)。右图：对应的百分位数图。颜色代码在左边。(B)左图：LH+10时CD56+uNK细胞(棕色染色)组织分布示例。比例尺=250μm。右图：Pearson相关分析基质细胞和uNK细胞密度。从20个活检组织中随机选取80个图像进行分析。(C)与从黄体期子宫内膜分离的uNK细胞一起孵育18小时或不孵育18小时的伊红染色蜕膜化8天的原代培养物的代表性图像。比例尺=100μm。(D)未分化或第8天蜕膜化的EnSCs与或不与uNK细胞共培养时，在加入或不加入凋亡抑制剂Z-VAD- fmk (Z-VAD, 10 μM)或颗粒酶活性抑制剂3,4- dci (25 μM)的情况下，SAβG活性。(E)用溶剂，达沙替尼(250 nM)或哌柏西利(1 μM)预处理后，每48小时检测一次原代EnSCs蜕膜化上清液中IL-15的分泌。(F)在IL-15阻断抗体(1 μg/ml)存在或不存在的情况下，未分化或第8天蜕膜化的EnSCs与或不与uNK细胞共培养时的SAβG活性。除非另有说明，数据是3个生物重复样本的均数±SEM。图表（error bars）上方的不同字母表示这些组之间有显著差异，p<0.05。本研究结果表明，黄体期子宫内膜的稳态取决于衰老蜕膜细胞的平衡诱导和清除。我们推测，这一过程是一个先验的动态过程，应该反映在不同周期中不同数量的uNK细胞中。作为概念证明，本文在三个不同周期的黄体中期（±1天）大约同时从三名患者的活检中定量了uNK细胞。如图6A所示，子宫基底层间质中uNK细胞的丰度在不同周期之间可能存在显著差异。随着水平的上升和下降，观察到的uNK细胞密度的周期间变化不太可能是由活检引起的组织损伤引发的，尽管不能排除对变化幅度的影响。图6补充1中给出了两个连续周期中uNK细胞波动的其他变化情况。Figure 6 with 1 supplement Dynamic inter-cycle fluctuations in uNK
cell levels.CD56 immunohistochemistry of LH-timed
endometrial biopsies obtained in three different cycles in three subjects. The
day of the biopsy and the percentage of CD56+uNK cells versus
stromal cells are indicated. The color of the box indicates the percentile
range of uNK when adjusted for the day of biopsy. Scale = 200 μm.三名受试者在三个不同周期的LH定时子宫内膜活检标本CD56免疫组化染色。显示了活检时间和CD56+uNK细胞与基质细胞的百分比。方框的颜色表示根据活检当天调整后的uNK的百分位数范围。比例=200μm。与机体衰老相关的慢性衰老相反，急性衰老是一个紧密协调的生物过程，涉及胚胎发育、伤口愈合和组织修复。通常，急性衰老细胞会产生具有特定旁分泌功能的特定环境SASP，并通过各种免疫细胞自行组织其清除。在这里，本研究提供的证据表明，急性蜕膜衰老是协调接受表型获得的关键过程伴随植入过程中子宫内膜重塑和更新。本文作者之前报道过，原代EnSC的蜕膜转化是一个逐步的过程，始于NOX4（NADPH 氧化酶4）依赖的自由基爆发和多种炎症介质的释放。将小鼠子宫暴露于这种炎性分泌组可诱导多种植入基因的表达，并使体外培养的小鼠胚胎能够有效植入。作者现已证明，这种蜕膜信号主要是由EnSC亚群的急性衰老驱动的。蜕膜化前后SAβG（senescence associated β-galactosidase，衰老相关β-半乳糖苷酶）活性之间的密切相关性表明，EnSC在细胞周期进入分化和衰老细胞时的极化不是随机的，而是由单个EnSC在前一个增殖阶段产生的复制应激水平决定的（图7）。急性衰老通过两种不同的机制使接受性子宫内膜恢复活力。首先，作者证明，用雷帕霉素阻断蜕膜衰老或用达沙替尼消除衰老细胞会导致分化的EnSC培养物中克隆MSC的丢失。相比之下，帕博西利处理中衰老的扩增持续增加了克隆细胞群。这些观察表明，蜕膜SASP（衰老相关分泌表型，senescence associated secretory phenotype）不仅在以下情况下“锁定”子宫内膜MSCs蜕膜化，但取决于炎症反应的幅度，也会将更多的定向细胞分化为克隆MSC。可以说，妊娠期蜕膜扩张可能需要足够的MSC群。其次，在uNK细胞激活后清除衰老的蜕膜细胞，确保胚胎嵌入大多数成熟的蜕膜细胞中。在共培养中，uNK细胞介导的SAβG+（阳性）细胞清除将蜕膜细胞单层转化为蜂窝状结构。如果在体内进行概括，这一观察表明uNK细胞在紧密粘附的蜕膜细胞基质中产生向内生长的作用，以促进滋养层细胞的侵袭和胚胎的锚定。与未分化的EnSC相比，蜕膜细胞对各种应激信号具有高度抵抗力，通过诱导11b羟基类固醇脱氢酶1型将无活性的可的松转化为皮质醇，并通过沉默编码关键趋化因子的基因来保护胚胎-母体界面免受T细胞的流入。综上所述，这些观察结果表明，衰老的蜕膜细胞会引发动态的组织反应，最终导致胚胎被包裹在免疫特权的蜕膜基质中。在怀孕期间，uNK细胞表达衰老标记物，是促血管生成的，而不是细胞毒性的。先前接触衰老蜕膜细胞是否会导致uNK细胞的这种妊娠表型有趣是但尚未经检测验证。Figure 7. Schematic summary.We propose that rapid endometrial growth during the proliferative phase is important for implantation as it imparts replication stress in a subpopulation of EnSCs. Upon cell cycle exit at G0/G1, this subpopulation of stressed EnSCs do not differentiate into specialist decidual cells but undergo acute cellular senescence and secrete a host of inflammatory mediators (senescence associated secretory phenotype; SASP) involved in endometrial receptivity. In parallel, Il-15 secreted by differentiated decidual cells activates uNK cells, which then target and eliminate senescent cells through granule exocytosis. Systematic clearance of acutely senescent decidual cells by uNK cells not only remodels but also rejuvenates the endometrium at the time of embryo implantation.
作者提出，增殖期子宫内膜的快速生长对植入很重要，因为它会在EnSC亚群中产生复制应激（replication stress复制压力：指在细胞DNA复制过程中，由于某些内外部因素导致DNA复制受到干扰或延迟，从而引发的一系列细胞应激反应）。当细胞周期在G0/G1期退出时，这种受应激的EnSC亚群不会分化为专门的蜕膜细胞，而是经历急性细胞衰老，并分泌许多参与子宫内膜容受性的炎症介质（衰老相关分泌表型，senescence associated secretory phenotype，SASP）。同时，分化的蜕膜细胞分泌的Il-15激活uNK细胞，然后通过颗粒胞吐（granule exocytosis颗粒胞外分泌）作用靶向并消除衰老细胞。uNK细胞系统清除急性衰老的蜕膜细胞不仅可以重塑胚胎植入时的子宫内膜，还可以使其恢复活力。值得注意的是，p16+（阳性）上皮细胞在整个着床窗口期内均有出现，但在腺上皮与基底上皮中分布不均，前者明显多于后者。可以推测，p16+ 基底上皮细胞可能在胚胎选择特定的植入位点过程中发挥重要作用。然而，在卵泡期向黄体期过渡时，两个上皮组织中p16+细胞的数量达到峰值。这反过来表明细胞衰老可能在使子宫内膜对进一步植入产生不耐受方面发挥作用。驱动子宫内膜上皮细胞衰老的机制可能与间质细胞衰老的机制存在显著差异。例如，子宫内膜上皮细胞不同于间质细胞，它们表达人类端粒酶逆转录酶（hTERT），并展现出动态变化的端粒酶活性。有趣的是，hTERT的表达及端粒酶活性在周期黄体期中期（即本研究观察到P16+上皮细胞数量增加之前）显著下降。在此阶段，染色体端粒长度达到最短，这表明存在另一种机制促使上皮细胞退出细胞周期并进入衰老状态。临床上，反复妊娠丢失（RPL）是令人苦恼的问题，尽管进行了广泛的检查，但往往仍然无法圆满解释原因。胚胎染色体不稳定性是自发性流产的主要原因。然而，随着每次额外失败的发生，潜在的子宫缺陷对正常胚胎发育的影响可能会增加。尽管如此，多次流产或体外受精失败后，累积活产率依然保持在较高水平。这表明胚胎与子宫内膜之间的相互作用具有内在的动态特性。本研究结果指向一个新的理论框架，能够解释观察到的反复流产现象并不排除成功怀孕的可能性。如果在增殖期的复制应激水平被黄体期由uNK细胞介导的对衰老蜕膜细胞的清除有效地平衡，子宫内膜的植入能力就得到了保证，并且在没有其他病理的情况下，生殖适应性应该达到最大。如果没有，预计异常周期的频率以及生殖失败的可能性会随着子宫内膜稳态不平衡的程度而增加。例如，RPL患者的子宫内膜以MSC缺乏，细胞衰老增强和蜕膜炎症反应延长和紊乱为特征。作者研究的模型预测，蜕膜的过度衰老可以通过增加uNK细胞的增殖和激活来平衡，从而趋于稳态并导致间歇性的正常周期。重要的是，子宫内膜MSC缺乏的程度与以前流产的次数相关，并与进一步失败的可能性相关。这一观察为我们之前的论断提供了佐证，即成功受孕的可能性与子宫内膜功能失调的严重程度成反比。内源性平衡细胞增殖与清除的能力意味着人类子宫内膜似乎对衰老具有抵抗力，并在整个生育期内保持其功能。总之，蜕膜化后基质细胞亚群的急性衰老会引发一个多步骤的过程，将周期性子宫内膜转化为妊娠组织。胚胎植入时的子宫内膜重塑受蜕膜衰老水平和免疫清除效果的时空控制。
下篇：生殖免疫的核心：子宫内膜异位症和腺肌症的免疫炎症、生殖破坏、妊娠失败等相关病理生理（一、9）：复发性流产的免疫病因和血栓形成
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