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The cell division cycle 20 (CDC20) protein is a co-activator of anaphase-promoting complex/cyclosome (APC/C), required for mitotic exit and also meiotic exit, containing seven WD40 repeats in the C-terminus responsible for protein-protein interactions. Recently, a previous study has shown that biallelic mutations in CDC20 are causative for female infertility with abnormalities in oocyte maturation and embryonic development. This study is to further identify new mutations of CDC20 and the prevalence of variants in our cohort. A cohort of 50 primary infertile females with oocyte maturation abnormality and early embryonic arrest were recruited. Genomic DNA was isolated from peripheral blood samples. Mutation screening of all the coding regions of CDC20 was performed by Sanger sequencing. The pathogenicity of the identified variants on the CDC20 protein was accessed in silico. Two CDC20 variants, a nonsense mutation p.R262* and a missense mutation p.A211T, identified in one female of 50 unrelated affected individuals, accounting for a relative small proportion of this cohort (2%). In silico analysis revealed that the p.R262* would cause no production of protein or a truncated protein lacking five WD40 repeats in the C-terminus; and that p.A211T may interfere with the formation of a deep hydrophobic pocket and thus disturb the binding of CDC20 protein to the substrates of APC/C. This study identified two novel mutations in CDC20, further expanding the mutation spectrum of this gene. Our findings further confirm that biallelic mutations in CDC20 occur in a proportion of infertile females with oocyte maturation abnormality and early embryonic arrest.

Maintaining homeostasis of the decidual immune microenvironment at the maternal–fetal interface is essential for placentation and reproductive success. Although distinct decidual immune cell subpopulations have been identified under normal conditions, systematic understanding of the spectrum and heterogeneity of leukocytes under recurrent miscarriage in human deciduas remains unclear. To address this, we profiled the respective transcriptomes of 18,646 primary human decidual immune cells isolated from patients with recurrent pregnancy loss (RPL) and healthy controls at single-cell resolution. We discovered dramatic differential distributions of immune cell subsets in RPL patients compared with the normal decidual immune microenvironment. Furthermore, we found a subset of decidual natural killer (NK) cells that support embryo growth were diminished in proportion due to abnormal NK cell development in RPL patients. We also elucidated the altered cellular interactions between the decidual immune cell subsets in the microenvironment and those of the immune cells with stromal cells and extravillous trophoblast under disease state. These results provided deeper insights into the RPL decidual immune microenvironment disorder that are potentially applicable to improve the diagnosis and therapeutics of this disease.

Declined quality and quantity of sperm is currently the major cause of patients suffering from infertility. Male germ cell development is spatiotemporally regulated throughout the whole developmental process. While it has been known that exogenous factors, such as environmental exposure, diet and lifestyle, et al, play causative roles in male infertility, recent progress has revealed abundant genetic mutations tightly associated with defective male germline development. In mammals, male germ cells undergo dramatic morphological change (i.e., nuclear condensation) and chromatin remodeling during post-meiotic haploid germline development, a process termed spermiogenesis; However, the molecular machinery players and functional mechanisms have yet to be identified. To date, accumulated evidence suggests that disruption in any step of haploid germline development is likely manifested as fertility issues with low sperm count, poor sperm motility, aberrant sperm morphology or combined. With the continually declined cost of next-generation sequencing and recent progress of CRISPR/Cas9 technology, growing studies have revealed a vast number of disease-causing genetic variants associated with spermiogenic defects in both mice and humans, along with mechanistic insights partially attained and validated through genetically engineered mouse models (GEMMs). In this review, we mainly summarize genes that are functional at post-meiotic stage. Identification and characterization of deleterious genetic variants should aid in our understanding of germline development, and thereby further improve the diagnosis and treatment of male infertility.

Although the thin endometrium (TE) has been widely recognized as a critical factor in implantation failure, the contribution of miRNA–mRNA regulatory network to the development of disease etiology remains to be further elucidated. This study performed an integrative analysis of the miRNA–mRNA expression profiles in the thin and adjacent normal endometrium of eight patients with intrauterine adhesion to construct the transcriptomic regulatory networks. A total of 1,093 differentially expressed genes (DEGs) and 72 differentially expressed miRNAs (DEMs) were identified in the thin adhesive endometrium of the TE group compared with the control adjacent normal endometrial cells. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the DEGs and the target genes of DEM were significantly enriched in angiogenesis, cell growth regulation, and Wnt signaling pathway. Multiple hub genes (CAV1, MET, MAL2, has-mir-138, ARHGAP6, CLIC4, RRAS, AGFG1, has-mir-200, and has-mir-429) were identified by constructing the miRNA–mRNA regulatory networks. Furthermore, a miRNA–mRNA pathway function analysis was conducted, and the hub genes were enriched in the FoxO signaling pathway, cell growth regulation, inflammatory response regulation, and regulation of autophagy pathways. Our study is the first to perform integrated mRNA-seq and miRNA-seq analyses in the thin adhesive endometrium and the control adjacent normal endometrial cells. This study provides new insights into the molecular mechanisms underlying the formation of thin endometrium.

Problem Immune checkpoint molecules are receptors that can transmit inhibitory signals into cells to negatively modulate the immune response. However, their roles in NK cells during normal pregnancy remain poorly understood. Method of Study Peripheral blood samples were collected from women during the first, second and third trimesters of pregnancy. Peripheral blood NK (pNK) cells and T cells were analyzed for the expression of the immune checkpoint molecules TIGIT and PD-1 by flow cytometry. In addition, the ability of pNK cells to secret functional molecules was also evaluated. Results The expression of TIGIT on pNK cells increased gradually throughout pregnancy, whereas that of PD-1 showed the opposite pattern. However, on T cells, the expression of both TIGIT and PD-1 peaked during early pregnancy, and then declined gradually thereafter. Moreover, the expressions of granzyme B, IFN-γ and CD107a by pNK cells also decreased over the course of pregnancy. Compared with TIGIT- NK cells, TIGIT + NK cells possessed reduced expression of functional molecules. Conclusions As pregnancy progressed, the levels of immune checkpoint molecules expressed on pNK cells and T cells changed and the two molecules showed different trends. Furthermore, the secretion of functional molecules from pNK cells was negatively correlated with the trend of TIGIT expression, indicating TIGIT may play an important role in modulating the functions of pNK cells during pregnancy. Further study of TIGIT expression on pNK cells may enhance our understanding of its role in maintaining maternal-fetal tolerance and provide a useful marker for predicting instability during pregnancy.

This study aims to compare the prevalence of sexually transmitted infections (STIs) with semen quality in men from couples with primary and secondary infertility. Semen samples were collected from 133 men who requested fertility evaluation. Seminal tract infection with Ureaplasma spp. (UU), Mycoplasma hominis (MH), Mycoplasma genitalium (MG), Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), and herpes simplex virus-2 (HSV-2) was assessed by PCR-based diagnostic assays. Among all patients, the prevalence of STIs was higher in men from couples with primary infertility than that in men from couples with secondary infertility (39.7% vs 21.7%, P = 0.03). The prevalence of UU was 28.8% and 13.3% in men from couples with primary and secondary infertility, respectively. Men from couples with primary infertility were more likely to be positive for UU than men from couples with secondary infertility (P = 0.04). Regarding the UU subtype, the prevalence of Ureaplasma urealyticum (Uuu) and Ureaplasma parvum (Uup; including Uup1, Uup3, Uup6, and Uup14) did not differ between the two groups. No associations between the prevalence rates of MH, MG, and CT were found in men from either infertility group. A lower sperm concentration was associated with STI pathogen positivity in men with primary infertility according to the crude model (P = 0.04). The crude and adjusted models showed that semen volume (both P = 0.03) and semen leukocyte count (both P = 0.02) were independently associated with secondary infertility. These findings suggest the importance of classifying the type of infertility during routine diagnosis of seminal tract infections.

Among causes of infertility, teratozoospermia is characterised by a percentage of morphologically abnormal spermatozoa4%. Macrozoospermia, one form of monomorphic teratozoospermia, is observed in1% of cases of male infertility and is described as approximately 100% large-headed and/or multitailed spermatozoa. This study reports that an infertile man with large-head spermatozoa presenting compound heterozygosity aurora kinase C (AURKC) mutations (c.382CT, c.572CT) by whole-exome sequencing. Consequently, both two novel AURKC mutations had high probability of damage-causing and conserved across species and extremely low allele frequency in the population. Flow cytometry analysis revealed a high ratio of sperm DNA fragmentation. Two intracytoplasmic sperm injection (ICSI) procedures were attempted for the patient, but all were unsuccessful. These results indicate that sequence analysis should be performed for the variants of AURKC in Chinese patients with macrozoospermia.

Abundant decidual natural killer (dNK) cells at the maternal-fetal interface are important during early pregnancy. However, functional subsets of dNK cells remain poorly understood. We describe a CD49a+PBX homeobox 1 (PBX1)+ dNK cell subset that promotes fetal development in humans and mice. The expression of PBX1 in dNK cells is up-regulated via the activated AKT1 pathway through the interaction of major histocompatibility complex G with the immunoglobulin-like transcript 2 receptor. PBX1 drives pleiotrophin and osteoglycin transcription in dNK cells, further promoting fetal development. Decreased PBX1 expression or the PBX1G21S mutant correlated with fetal growth restriction and pregnancy failure in patients with unexplained recurrent spontaneous abortion (URSA). Inactivation of Pbx1 in mouse dNK cells impairs fetal development by decreasing growth-promoting factors from CD49a+PBX1+ dNK cells. Impairment of PBX1 in dNK cells has positive correlation with URSA pathogenesis and may provide a potential marker for this condition.

Summary Natural killer (NK) cells are present in large populations at the maternal-fetal interface during early pregnancy. However, the role of NK cells in fetal growth is unclear. Here, we have identified a CD49a + Eomes + subset of NK cells that secreted growth-promoting factors (GPFs), including pleiotrophin and osteoglycin, in both humans and mice. The crosstalk between HLA-G and ILT2 served as a stimulus for GPF-secreting function of this NK cell subset. Decreases in this GPF-secreting NK cell subset impaired fetal development, resulting in fetal growth restriction. The transcription factor Nfil3, but not T-bet, affected the function and the number of this decidual NK cell subset. Adoptive transfer of induced CD49a + Eomes + NK cells reversed impaired fetal growth and rebuilt an appropriate local microenvironment. These findings reveal properties of NK cells in promoting fetal growth. In addition, this research proposes approaches for therapeutic administration of NK cells in order to reverse restricted nourishments within the uterine microenvironment during early pregnancy.

Natural killer (NK) cells accumulate at the maternal–fetal interface in large numbers, but their exact roles in successful pregnancy remain poorly defined. Here, we provide evidence that T H 17 cells and local inflammation can occur at the maternal–fetal interface during natural allogenic pregnancies. We found that decidual NK cells promote immune tolerance and successful pregnancy by dampening inflammatory T H 17 cells via IFN-γ secreted by the CD56 bright CD27 + NK subset. This NK-cell–mediated regulatory response is lost in patients who experience recurrent spontaneous abortions, which results in a prominent T H 17 response and extensive local inflammation. This local inflammatory response further affects the regulatory function of NK cells, leading to the eventual loss of maternal-fetal tolerance. Thus, our data identify NK cells as key regulatory cells at the maternal–fetal interface by suppressing T H 17-mediated local inflammation.