No difference in natural killer or natural killer T-cell population, but aberrant T-helper cell population in the endometrium of women with repeated miscarriage

The skewed TCR-BV repertoire displayed at the maternal-fetal interface of women with unexplained pregnancy loss

PROBLEM

The study was undertaken to investigate T-cell receptor (TCR) variable beta (BV)-chain usage at maternal-fetal interface and explore the relationship between the skewed TCR-BV usage and unexplained pregnancy losses.

METHOD OF STUDY

A total of 57 patients with unexplained pregnancy loss including 39 cases with unexplained spontaneous abortion and 18 cases with unexplained recurrent spontaneous abortion (RSA) were chosen in Renji Hospital, Shanghai Second Medical University matched with 41 women with normal pregnancies in first trimester between September 2002 and November 2003. A high-resolution spectratyping analysis of complementarity-determining region 3 (CDR3) was used to detect and compare the degree and pattern of TCR-BV repertoire usage at the maternal-fetal interface between patients with pregnancy loss and normal controls.

RESULTS

There were two comparisons of TCR usage performed between patients and controls, which included the degree (mean value of every TCR-BVn expression) and the pattern (skewed TCR-BVn frequency). The skewed TCR-BVn is defined as an absolute BVn usage of > 5% calculated from the formula or a double increased BVn usage compared with the mean value of normal BVn. According to the degree of TCR-BV usage, BV2 (P = 0.046), BV10 (P = 0.016), and BV11 (P = 0.030) in spontaneous abortion group and BV19 (P = 0.038) in RSA group showed higher usage, while BV5.2 (P = 0.006 and P = 0.046) in both abortion groups showed significantly lower usage when compared with normal controls. About the pattern of skewed TCR-BV distribution, we found that TCR-BV2, -3, -6, and -7 were the four most common BV families in deciduas of patients with both types of abortion and normal controls. Women with spontaneous abortion demonstrated higher frequency of BV10 (P = 0.035) and lower frequencies of BV4 (P = 0.002) and BV5.2 (P = 0.003) in comparison with controls. In RSA, higher frequencies of BV15 (P = 0.018), BV19 (P = 0.049), and BV20 (P = 0.018), in the mean time, lower frequencies of BV4 (P = 0.026) and BV7 (P = 0.018) distributions were verified.

CONCLUSIONS

Our results suggested that a significant skewed TCR-BV repertoire occurred at the maternal-fetal interface with patients undergoing abortion. The specific skewed usages of TCR-BV might be associated with the susceptibility to unexplained pregnancy loss.

Enhanced expressions of endometrial tumour necrosis factor alpha and its receptors during early pregnancy in bonnet monkeys

Tumour necrosis factor alpha (TNF-alpha), a pro-inflammatory cytokine may play an active role in stimulating inflammatory reactions during pregnancy. However, the expression of endometrial TNF-alpha has not been investigated especially during early pregnancy, a phenomenon invariably accompanied by inflammatory reaction. In the present study, the endometrial expressions of TNF-alpha and its receptors (TNFR1 and TNFR2) during early pregnancy, when the embryo lies free in the zona hatched state in the uterine lumen, were analyzed by immunohistochemistry. The endometrial expressions of TNF-alpha, TNFR1 and TNFR2 were found to be significantly up-regulated (p < 0.05) in the glandular epithelium on day 6 post-ovulation in pregnant animals. The alteration in the expression of these molecules may contribute to the induction of local inflammatory reactions during implantation.

Divergence of natural killer cell receptor and related molecule in the decidua from sporadic miscarriage with normal chromosome karyotype

The aim of this cohort study was to investigate immunophenotypic characteristics of natural killer (NK) cells by assessing specific molecules expressed in the decidua of sporadic miscarriages and induced abortions. The deciduae were obtained from 29 consecutively seen women whose pregnancies ended in first trimester miscarriages (MS), and the fetal chromosome karyotype of these MS was analysed. Additionally, 13 deciduae were obtained from induced abortion (IA) with informed consent. The expression of perforin, CD94, CD161, CD158a, CD158b, CD244 on CD3-CD56+NK cells, and perforin on CD3+CD8+ T cells was analysed by flow cytometry. The CD158a (mean+/-SD, 26.2+/-14.7%) and CD94 (50.2+/-25.7%) expressions in MS with normal chromosome karyotype (MSNK; n=11) were significantly decreased as compared with those (41.5+/-19.5%, 71.4+/-20.4%) in MS with abnormal karyotype (MSAK; n=18) and those (44.3+/-21.9%, 80.8+/-17.5%) in IA (n=13). Conversely, the perforin expression on CD3-CD8-CD56+NK cells (76.3+/-11.0%) and CD3+CD8+T cells (30.6+/-9.2%) in MSNK was significantly increased as compared with those (66.8+/-16.6%, 23.6+/-8.7%) in MSAK and those (62.9+/-11.6%, 19.7+/-8.1%) in IA. A positive correlation between CD94 and CD158a expressions on NK cells, negative correlations between CD94 on NK cells and perforin on NK cells/T cells, and between CD158a on NK cells and perforin on T cells were found in the decidua. A divergence of NK cell repertoire in the decidua might be related to aetiology of sporadic MSNK.

Interleukin-4 gene polymorphism is not involved in the risk of recurrent pregnancy loss

PROBLEM

Enhanced secretion of type-2 T-helper (Th2) cytokine is a characteristic feature in normal physiological pregnancy. A study has demonstrated defective production of interleukine-4 (IL-4) and other Th2 cytokine in women with recurrent pregnancy loss (RPL). Several studies have suggested that IL-4 variable number of tandem repeat (VNTR) gene polymorphism is probably associated with different IL-4 production.

METHODS OF STUDY

The IL-4 VNTR genotypes were assessed in 109 Japanese women with RPL and 210 ethnically matched women experiencing at least one live birth and no spontaneous abortion.

RESULTS

No significant differences in IL-4 VNTR genotype frequencies were found between the RPL and the control [B1B1 genotype (reference); B1/B2 and B2/B2 genotypes, odds ratio, 0.91; 95% confidence interval, 0.58-1.45].

CONCLUSION

The present study suggests that the IL-4 VNTR allele is not a major genetic regulator in RPL.

Natural killer cells in pregnancy and recurrent pregnancy loss: endocrine and immunologic perspectives

The endocrine system and the immune system interact closely during implantation and maintenance of pregnancy. One of the most striking examples of this communication is at the level of the decidua (endometrium of pregnancy). Here, under the influence of sex steroids, there is a dramatic increase of a unique population of lymphocytes, the uterine natural killer (uNK) cells, in early pregnancy. These cells derive predominantly from a subset of peripheral blood NK cells, which under hormonal influence gets recruited to the uterus. In mice, uNK cells play an important role in the development of placental vasculature. The role of these cells in human pregnancy is still not definitively established; however, they are believed to promote placental and trophoblast growth and provide immunomodulation at the maternal-fetal interface. In contrast to their presumptive role in the maintenance of a healthy pregnancy, uNK cells and peripheral NK cells are dysregulated in unexplained recurrent pregnancy loss. Herein, we review NK cell populations, their changes in number and function in altered endocrine environments during the menstrual cycle and pregnancy, the current data on their potential role in unexplained recurrent pregnancy loss, and mechanisms for potential therapies targeted to NK cell function for this enigmatic disorder.

Natural killer cells, miscarriage, and infertility

Enthusiasm for new treatments aimed at natural killer cells in women with reproductive failure is unfortunately not backed up by the science