NK cells detect changes in adaptive immunity within mouse decidua from gestation day eight

Imaging of vascular development in early mouse decidua and its association with leukocytes and trophoblasts

In species with endometrial decidualization and hemochorial placentation (humans, mice, and others), leukocytes localize to early implant sites and contribute to decidual angiogenesis, spiral arterial remodeling, and trophoblast invasion. Relationships between leukocytes, trophoblasts, and the decidual vasculature are not fully defined. Early C57BL/6J implant sites were analyzed by flow cytometry to define leukocyte subsets and by whole-mount immunohistochemistry to visualize relationships between leukocytes, decidual vessels, and trophoblasts. Ptprc(+) (CD45(+)) cells increased in decidua between Gestational Day (GD) 5.5 and GD 9.5. Uterine natural killer (uNK) cells that showed dynamic expression of Cd (CD) 69, an activating receptor, and Klrg1 (KLRG1), an inhibitory receptor, localized mesometrially and were the dominant CD45(+) cells between GD 5.5 and GD 7.5. At GD 8.5, immature monocytes that occurred throughout decidua exceeded uNK cells numerically and many leukocytes acquired irregular shapes, and leukocyte-leukocyte conjugates became frequent. Vessels were morphologically heterogeneous and regionally unique. Migrating trophoblasts were first observed at GD 6.5 and, at GD 9.5, breached endothelium, entered vascular lumens, and appeared to occlude some vessels, as described for human spiral arteries. No leukocyte-trophoblast conjugates were detected. Whole-mount staining gave unparalleled decidual vascular detail and cell-specific positional information. Its application across murine models of pregnancy disturbances should significantly advance our understanding of the maternal-fetal interface.

Circulating CD56+ cells of diabetic women show deviated homing potential for specific tissues during and following pregnancy

BACKGROUND

Human uterine natural killer (uNK) cells, the dominant lymphocytes in early pregnancy decidua, are important for spiral arterial remodelling. uNK cells are thought to arise from circulating CD56(bright) NK cells that egress into decidualizing endometrium. Both incomplete spiral arterial modification and aberrant NK cell function have been linked with pre-eclampsia, a syndrome that is more prevalent in diabetic women. Since previous in vitro studies have shown that changes in decidual endothelium induced by type 1 diabetes (T1D) reduce its interactions with circulating leucocytes, we hypothesized that diabetes additionally has direct effects on circulating CD56(+) NK cells that impair their decidual homing potential.

METHODS

Serial blood samples were collected from control, T1D and T2D pregnant women throughout and after pregnancy. In vitro adhesion under shear forces was used to assay the functional capacity of circulating leucocytes and of CD56(+) cells to adhere to endothelium in cryostat sections of gestation day (gd) 7 normal mouse decidua, pancreas and lymph node.

RESULTS

Fewer CD56(+) cells from diabetic compared with control women adhered to normal decidual endothelium. The CD56(+) cell/total cell adhesion ratio was also lower in diabetics. More diabetic CD56(+) cells adhered to pancreatic endothelium and their proportion was greater than for controls. Neither absolute nor proportional adhesion of CD56(+) cells to lymph node endothelium differed between diabetics and controls.

CONCLUSIONS

The CD56(+) cell adhesion patterns of T1D and T2D women differ from those of non-diabetic women and support the hypothesis that diabetes impairs mechanisms that could be used by CD56(+) cells for egress into decidua.

Reproductive immunology: a focus on the role of female sex hormones and other gender-related factors

Reproductive immunology has attracted the attention of researchers interested in fertility and pregnancy as well as those interested in immunity and autoimmunity. Over the past couple of decades, a wealth of data on the immune-reproductive interactions has been generated. This issue of the Journal will examine several topics including the role of immune factors in the induction of anti-Ro antibody-mediated autoimmunity in neonates and the immunological effects of gender and sex hormones. The possible implications of the research reviewed here for the development of novel therapeutic approaches are also addressed.

Altered DNA methylation in leukocytes with trisomy 21

The primary abnormality in Down syndrome (DS), trisomy 21, is well known; but how this chromosomal gain produces the complex DS phenotype, including immune system defects, is not well understood. We profiled DNA methylation in total peripheral blood leukocytes (PBL) and T-lymphocytes from adults with DS and normal controls and found gene-specific abnormalities of CpG methylation in DS, with many of the differentially methylated genes having known or predicted roles in lymphocyte development and function. Validation of the microarray data by bisulfite sequencing and methylation-sensitive Pyrosequencing (MS-Pyroseq) confirmed strong differences in methylation (p<0.0001) for each of 8 genes tested: TMEM131, TCF7, CD3Z/CD247, SH3BP2, EIF4E, PLD6, SUMO3, and CPT1B, in DS versus control PBL. In addition, we validated differential methylation of NOD2/CARD15 by bisulfite sequencing in DS versus control T-cells. The differentially methylated genes were found on various autosomes, with no enrichment on chromosome 21. Differences in methylation were generally stable in a given individual, remained significant after adjusting for age, and were not due to altered cell counts. Some but not all of the differentially methylated genes showed different mean mRNA expression in DS versus control PBL; and the altered expression of 5 of these genes, TMEM131, TCF7, CD3Z, NOD2, and NPDC1, was recapitulated by exposing normal lymphocytes to the demethylating drug 5-aza-2′deoxycytidine (5aza-dC) plus mitogens. We conclude that altered gene-specific DNA methylation is a recurrent and functionally relevant downstream response to trisomy 21 in human cells.

Down syndrome (DS; trisomy 21) is caused by the gain of a single extra chromosome 21. However, the mechanisms by which this extra chromosome produces the medical abnormalities seen in DS, including not only mental retardation but also susceptibility to autoimmune diseases and recurrent infections, are still not understood. DNA methylation is a mechanism that might contribute to these abnormalities. To test this possibility, we profiled DNA methylation in white blood cells from adults with DS and normal controls and found recurrent abnormalities of gene methylation in DS, with several of the differentially methylated genes having roles in blood cells. Among the genes with hypo- or hyper-methylation in white blood cells or purified T-lymphocytes from adults with DS, compared to these same types of cells from normal adults, were TMEM131, TCF7, CD3Z, SH3BP2, EIF4E, SUMO3, CPT1B, NOD2/CARD15, NPDC1, and PLD6. Several of these genes showed not only different methylation but also different expression in DS versus control blood cells, which was recapitulated by exposing normal white blood cells to a demethylating drug. These findings show that altered DNA methylation of a specific group of genes is a fundamental cellular response to the gain of an extra chromosome 21 in humans. The abnormally methylated genes identified here may contribute to immune system abnormalities in people with DS.