The genetics of hydatidiform moles: new lights on an ancient disease

Novel scoring system provides high separation of diploidy and triploidy to aid partial hydatidiform mole diagnosis: an adaption of HER2 D-DISH for ploidy analysis

AIMS

Diagnosis of hydatidiform mole or molar pregnancy based on morphology alone can be challenging, particularly in early gestation, necessitating the use of ancillary techniques for accurate diagnosis. We sought to adapt the VENTANA HER2 dual-colour dual-hapten in-situ hybridisation (D-DISH) assay by using the internal chromosome 17 enumeration probe to determine ploidy status.

METHODS

We selected 25 products of conception, consisting of molar and non-molar cases, to validate the HER2 D-DISH assay. These cases had prior morphological assessment by a perinatal pathologist and ploidy analysis using molecular cytogenetics. Three independent observers, blinded to the original histopathological and genetic diagnosis, scored 10 representative areas on each slide. Interobserver variability was assessed by comparing the total scores of each observer using analysis of variance (ANOVA) and the kappa statistic.

RESULTS

Our ploidy scoring system accurately determined the correct number of diploid and triploid conceptuses, demonstrating complete concordance with pre-existing ploidy status and the initial diagnosis. Interobserver agreement between three independent scorers was robust: ANOVA (p=0.36) and kappa statistic (0.812, p<0.001). We achieved clear separation of average nuclear signals for diploid and triploid conceptuses, which was statistically significant (p<0.05). Employing our innovative scoring system, known as the 'rule of 5', we established ploidy decision thresholds for all 25 cases.

CONCLUSIONS

Our modified HER2 D-DISH ploidy assay simplifies the process of ploidy determination and improves the accuracy of morphological diagnosis of molar pregnancy. The HER2 D-DISH assay was selected for ploidy analysis due to the widespread availability of in-situ hybridisation in pathology laboratories.

Hydatidiform Mole-Between Chromosomal Abnormality, Uniparental Disomy and Monogenic Variants: A Narrative Review

A hydatidiform mole (HM) or molar pregnancy is the most common benign form of gestational trophoblastic disease characterized by a proliferation of the trophoblastic epithelium and villous edema. Hydatidiform moles are classified into two forms: complete and partial hydatidiform moles. These two types of HM present morphologic, histopathologic and cytogenetic differences. Usually, hydatidiform moles are a unique event, but some women present a recurrent form of complete hydatidiform moles that can be sporadic or familial. The appearance of hydatidiform moles is correlated with some genetic events (like uniparental disomy, triploidy or diandry) specific to meiosis and is the first step of embryo development. The familial forms are determined by variants in some genes, with NLRP7 and KHDC3L being the most important ones. The identification of different types of hydatidiform moles and their subsequent mechanisms is important to calculate the recurrence risk and estimate the method of progression to a malign form. This review synthesizes the heterogeneous mechanisms and their implications in genetic counseling.

Advances in the diagnosis and early management of gestational trophoblastic disease

Gestational trophoblastic disease describes a group of rare pregnancy related disorders that span a spectrum of premalignant and malignant conditions. Hydatidiform mole (also termed molar pregnancy) is the most common form of this disease. Hydatidiform mole describes an abnormal conceptus containing two copies of the paternal genome, which is classified as partial when the maternal genome is present or complete when the maternal genome is absent. Hydatidiform mole typically presents in the first trimester with irregular vaginal bleeding and can be suspected on ultrasound but confirmation requires histopathological evaluation of the products of conception. Most molar pregnancies resolve without treatment after uterine evacuation, but occasionally the disease persists and develops into gestational trophoblastic neoplasia. Close monitoring of women after molar pregnancy, with regular measurement of human chorionic gonadotrophin concentrations, allows for early detection of malignancy. Given the rarity of the disease, clinical management and treatment is best provided in specialist centres where very high cure rates are achievable. This review looks at advances in the diagnosis and early management of gestational trophoblastic disease and highlights updates to disease classification and clinical guidelines. Use of molecular genotyping for improved diagnostic accuracy and risk stratification is reviewed and future biomarkers for the earlier detection of malignancy are considered.

NLRP7: From inflammasome regulation to human disease

Nucleotide-binding oligomerization domain (NOD) and leucine-rich repeat (LRR)-containing receptors or NOD-like receptors (NLRs) are cytosolic pattern recognition receptors, which sense conserved microbial patterns and host-derived danger signals to elicit innate immune responses. The activation of several prototypic NLRs, including NLR and pyrin domain (PYD) containing (NLRP) 1, NLRP3 and NLR and caspase recruitment domain (CARD) containing (NLRC) 4, results in the assembly of inflammasomes, which are large, cytoplasmic multiprotein signalling platforms responsible for the maturation and release of the pro-inflammatory cytokines IL-1β and IL-18, and for the induction of a specialized form of inflammatory cell death called pyroptosis. However, the function of other members of the NLR family, including NLRP7, are less well understood. NLRP7 has been linked to innate immune signalling, but its precise role is still controversial as it has been shown to positively and negatively affect inflammasome responses. Inflammasomes are essential for homeostasis and host defence, but inappropriate inflammasome responses due to hereditary mutations and somatic mosaicism in inflammasome components and defective regulation have been linked to a broad spectrum of human diseases. A compelling connection between NLRP7 mutations and reproductive diseases, and in particular molar pregnancy, has been established. However, the molecular mechanisms by which NLRP7 mutations contribute to reproductive diseases are largely unknown. In this review, we focus on NLRP7 and discuss the current evidence of its role in inflammasome regulation and its implication in human reproductive diseases.

The pivotal roles of the NOD-like receptors with a PYD domain, NLRPs, in oocytes and early embryo development†

Nucleotide-binding oligomerization domain (NOD)-like receptors with a pyrin domain (PYD), NLRPs, are pattern recognition receptors, well recognized for their important roles in innate immunity and apoptosis. However, several NLRPs have received attention for their new, specialized roles as maternally contributed genes important in reproduction and embryo development. Several NLRPs have been shown to be specifically expressed in oocytes and preimplantation embryos. Interestingly, and in line with divergent functions, NLRP genes reveal a complex evolutionary divergence. The most pronounced difference is the human-specific NLRP7 gene, not identified in rodents. However, mouse models have been extensively used to study maternally contributed NLRPs. The NLRP2 and NLRP5 proteins are components of the subcortical maternal complex (SCMC), which was recently identified as essential for mouse preimplantation development. The SCMC integrates multiple proteins, including KHDC3L, NLRP5, TLE6, OOEP, NLRP2, and PADI6. The NLRP5 (also known as MATER) has been extensively studied. In humans, inactivating variants in specific NLRP genes in the mother are associated with distinct phenotypes in the offspring, such as biparental hydatidiform moles (BiHMs) and preterm birth. Maternal-effect recessive mutations in KHDC3L and NLRP5 (and NLRP7) are associated with reduced reproductive outcomes, BiHM, and broad multilocus imprinting perturbations. The precise mechanisms of NLRPs are unknown, but research strongly indicates their pivotal roles in the establishment of genomic imprints and post-zygotic methylation maintenance, among other processes. Challenges for the future include translations of findings from the mouse model into human contexts and implementation in therapies and clinical fertility management.

Pregnancy after oocyte donation in a patient with NLRP7 gene mutations and recurrent molar hydatidiform pregnancies

Molar pregnancies are benign trophoblastic diseases associated with a risk of malignant transformation. If aetiology remains mostly unknown, the risk of recurrent molar pregnancy is around 1.5% after one molar pregnancy and around 25% after 2 molar pregnancies. In the later situation, genetic mutations have been described, increasing hugely this risk. In case of mutations, probability to obtain a normal pregnancy is estimated around 1.8%. We report the case of a Caucasian 30-year-old woman whose previous five spontaneous pregnancies had a negative outcome: a spontaneous miscarriage and then 4 complete hydatidiform moles. Genetic testing revealed that the patient carried two heterozygous mutations in the NLRP7 gene (c.2982-2A > G and Y318CfsX7). According to this, counselling was conducted to advocate for oocyte donation in order to obtain a normal pregnancy. This technique enabled a complication-free, singleton pregnancy that resulted in a healthy term live birth of a 2900 g female. Few months after delivery, the patient presented a new complete hydatidiform mole. Women presented with mutations in the NLRP7, KHDC3L or PADI6 genes are unlikely to obtain normal pregnancies, with a major risk of reproductive failure. In such a context, oocyte donation may be the best option. Only 4 normal pregnancies and deliveries have been published in this situation through this technique to our knowledge.

Generation of human androgenetic induced pluripotent stem cells

In humans, parthenogenesis and androgenesis occur naturally in mature cystic ovarian teratomas and androgenetic complete hydatidiform moles (CHM), respectively. Our previous study has reported human parthenogenetic induced pluripotent stem cells from ovarian teratoma-derived fibroblasts and screening of imprinted genes using genome-wide DNA methylation analysis. However, due to the lack of the counterparts of uniparental cells, identification of new imprinted differentially methylated regions has been limited. CHM are inherited from only the paternal genome. In this study, we generated human androgenetic induced pluripotent stem cells (AgHiPSCs) from primary androgenetic fibroblasts derived from CHM. To investigate the pluripotency state of AgHiPSCs, we analyzed their cellular and molecular characteristics. We tested the DNA methylation status of imprinted genes using bisulfite sequencing and demonstrated the androgenetic identity of AgHiPSCs. AgHiPSCs might be an attractive alternative source of human androgenetic embryonic stem cells. Furthermore, AgHiPSCs can be used in regenerative medicine, for analysis of genomic imprinting, to study imprinting-related development, and for disease modeling in humans.

Identification of a hydatidiform mole in twin pregnancy following assisted reproduction

PURPOSE

The aim of this study was to identify a co-existing hydatidiform mole (HM) in twin pregnancy from the abnormal mixed-genomic products of conception (POC) after assisted reproduction by histopathological review, evaluation of p57^kip2 immunostaining and short tandem repeat genotyping.

METHODS

Thirty-seven patients were collected with suspicion for HM by pathological morphology. They had two embryos individually transferred to their uterus after in vitro fertilization and presented two gestational sacs with undeveloped embryos or one sac with an abnormal area by ultrasonography.

RESULTS

Thirty patients were diagnosed as singleton pregnancy, including twenty-two non-molar gestations, six trisomy gestations, one homozygous complete mole and one heterozygous partial mole. Although six patients had ultrasonic imaging of two gestational sacs, the embryonic components in the vacant sac might fade away after transferring. Other seven patients were considered as twin pregnancy by the allelic genotype from two individual conceptions. For the patients with uniform p57^kip2 positivity, excessive paternal alleles indicated the potential partial HM in the twin pregnancy. For the patients demonstrated divergent and/or discordant p57^kip2 immunostaining, twin pregnancy with co-existing complete HM or mosaic conception were confirmed by genotyping of different villi population respectively. These patients were monitored by serum β-HCG, while one twin pregnancy with complete mole suffered invasive mole and received chemotherapy.

CONCLUSIONS

A strategy composed of selective clinicopathological screening, immunohistochemical interpretation and accurate genotyping is recommended for diagnostically challenging mixed-genomic POC of potential twin pregnancy with HM, especially to differentiate a non-molar mosaic conception from a partial mole.

Dysregulation of Placental Functions and Immune Pathways in Complete Hydatidiform Moles

Gene expression studies of molar pregnancy have been limited to a small number of candidate loci. We analyzed high-dimensional RNA and protein data to characterize molecular features of complete hydatidiform moles (CHMs) and corresponding pathologic pathways. CHMs and first trimester placentas were collected, histopathologically examined, then flash-frozen or paraffin-embedded. Frozen CHMs and control placentas were subjected to RNA-Seq, with resulting data and published placental RNA-Seq data subjected to bioinformatics analyses. Paraffin-embedded tissues from CHMs and control placentas were used for tissue microarray (TMA) construction, immunohistochemistry, and immunoscoring for galectin-14. Of the 14,022 protein-coding genes expressed in all samples, 3,729 were differentially expressed (DE) in CHMs, of which 72% were up-regulated. DE genes were enriched in placenta-specific genes (OR = 1.88, p = 0.0001), of which 79% were down-regulated, imprinted genes (OR = 2.38, p = 1.54 × 10-6), and immune genes (OR = 1.82, p = 7.34 × 10-18), of which 73% were up-regulated. DNA methylation-related enzymes and histone demethylases were dysregulated. "Cytokine-cytokine receptor interaction" was the most impacted of 38 dysregulated pathways, among which 17 were immune-related pathways. TMA-based immunoscoring validated the lower expression of galectin-14 in CHM. In conclusion, placental functions were down-regulated, imprinted gene expression was altered, and immune pathways were activated, indicating complex dysregulation of placental developmental and immune processes in CHMs.

NLRP7 and KHDC3L variants in Chinese patients with recurrent hydatidiform moles

OBJECTIVE

Recurrent hydatidiform moles are reportedly biparental complete moles and related to mutated NLRP7 and KHDC3L. This study was designed to identify mutations of gene NLRP7 and KHDC3L in biparental complete moles.

METHODS

In this study, we have screened NLRP7 and KHDC3L mutations in five patients with recurrent moles and five with sporadic moles. Molar tissues and blood samples were collected from patients and their partners. Genotypes of the molar tissues were determined based on short tandem repeat polymorphism. The coding exons of NLRP7 and KHDC3L were sequenced.

RESULTS

Two patients with recurrent moles had biparental complete moles, while all other patients had androgenetic complete moles. Three non-synonymous variants in NLRP7 (c.955 G>A, c.1280 T>C and c.1441 G>A) and one in KHDC3L (c.602 C>G) were identified in patients with recurrent moles. NLRP7 c.1441 G>A and c.1280 T>C were mutations found in the Chinese population, while c.1441 G>A was only detected in patients with biparental complete moles in this study.

CONCLUSIONS

Genotyping can be used to differentiate biparental complete moles from androgenetic moles and to predict the risk of recurrent moles in future pregnancies. NLRP7 c.1441 G>A may associate with biparental complete moles. Biparental complete moles exhibit genetic heterogeneity.

Hydatidiform molar pregnancy following assisted reproduction

INTRODUCTION

The use of assisted reproduction techniques (ART) is increasing; however, reports of molar pregnancy following ART remain scarce. Currently, the Human Fertility and Embryology Authority (HFEA) collates data on the molar pregnancies that have resulted through the use of ART. Recently, they have indicated that they will no longer collect these data.

AIM

This paper aimed to examine the incidence of molar pregnancy amongst patients undergoing assisted reproduction.

METHODS

We contacted HFEA and placed a request under the Freedom of Information Act (2000) for the number of molar pregnancies that resulted from fresh/frozen embryo transfer since HFEA started collecting data in 1991 to February 2018. We also asked how many patients who had suffered a molar pregnancy went on to have a normal pregnancy and how many had subsequent molar pregnancies, in subsequent treatment cycles.

RESULTS

Between 68 and 76 molar pregnancies occurred within this period using ART (n = 274,655). The incidence of molar pregnancy using fresh intracytoplasmic sperm injection (ICSI) (1/4302) and fresh in vitro fertilisation (IVF) (1/4333) was similar. The risk of recurrence of molar pregnancy following a previous molar was higher following ART compared to spontaneous conceptions.

CONCLUSION

The use of ICSI should be protective against triploidy; however, the retrospective data suggests that molar pregnancy is not eliminated with the use of ART. It is pertinent to continue to record this data, through the gestational trophoblastic disease centres, in order to ensure no further increase in incidence, appropriate follow-up, and transparency in communication.

Whole-exome sequencing reveals genetic variants in ERC1 and KCNG4 associated with complete hydatidiform mole in Chinese Han women

Complete hydatidiform mole (CHM) is a rare pregnancy-related disease with invasive potential. The genetics underlying the sporadic form of CHM have not been addressed previously, but maternal genetic variants may be involved in biparental CHM. We performed whole-exome sequencing of 51 patients with CHM and 47 healthy women to identify genetic variants associated with CHM. In addition, candidate variants were analyzed using single base extension and Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry in 199 CHM patients and 400 healthy controls. We validated candidate variants using Sanger sequencing in 250 cases and 652 controls, including 205 new controls. Two single nucleotide polymorphisms, c.G48C(p.Q16H) inERC1 and c.G1114A(p.G372S) in KCNG4, were associated with an increased risk of CHM (p<0.05). These variants may contribute to the pathogenesis of CHM and could be used to screen pregnant women for this genetic abnormality.

The Diagnosis of Choriocarcinoma in Molar Pregnancies: A Revised Approach in Clinical Testing

Background

Hydatidiform moles occur in approximately 1 in 1,500 pregnancies; however, early miscarriages or spontaneous abortions may not be correctly identified as molar pregnancies due to poor differentiation of chorionic villi.

Methods

The current clinical testing algorithm used for the detection of hydatidiform moles uses a combination of morphological analysis and p57 immunostaining followed by ploidy testing to establish a diagnosis of either a complete or partial molar pregnancy. We review here 198 referrals for fluorescence in situ hybridization (FISH) ploidy testing, where the initial diagnosis based on morphology is compared to the final diagnosis based on a combination of morphology, FISH and p57 immunohistochemical (IHC) staining.

Results

Approximately 40% of cases were determined to be genetically abnormal, but only 28.8% of cases were diagnosed as molar pregnancies. The underestimation of complete molar pregnancies and those with androgenetic inheritance was also found to be likely using conventional diagnostic methods, as atypical p57 staining was observed in approximately 10% of cases.

Conclusions

Our findings suggest that a revised approach to testing products of conception is necessary, with cases screened according to their clinical history in order to distinguish molar pregnancy referrals from hydropic pregnancies.

The hydatidiform mole

The hydatidiform mole (HM) is a placental pathology of androgenetic origin. Placental villi have an abnormal hyperproliferation event and hydropic degeneration. Three situations can be envisaged at its origin: 1. The destruction/expulsion of the female pronucleus at the time of fertilization by 1 or 2 spermatozoa with the former being followed by an endoreplication of the male pronucleus leading to a complete hydatidiform mole (CHM) 2. A triploid zygote (fertilization by 2 spermatozoa) leading to a partial hydatidiform mole (PHM) but can also lead to haploid and diploid clones. The diploid clone may produce a normal fetus while the haploid clone after endoreplication generates a CHM 3. A nutritional defect during the differentiation of the oocytes or the deterioration of the limited oxygen pressure during the first trimester of gestation may lead to the formation of a HM. In countries with poor medical health care system, moles (mainly the CHM) can become invasive or, in rare cases, lead to gestational choriocarcinomas.

Analyzing the most frequent disease loci in targeted patient categories optimizes disease gene identification and test accuracy worldwide

Background

Our genomewide studies support targeted testing the most frequent genetic diseases by patient category: (1) pregnant patients, (2) at-risk conceptuses, (3) affected children, and (4) abnormal adults. This approach not only identifies most reported disease causing sequences accurately, but also minimizes incorrectly identified additional disease causing loci.

Methods

Diseases were grouped in descending order of occurrence from four data sets: (1) GeneTests 534 listed population prevalences, (2) 4129 high risk prenatal karyotypes, (3) 1265 affected patient microarrays, and (4) reanalysis of 25,452 asymptomatic patient results screened prenatally for 108 genetic diseases. These most frequent diseases are categorized by transmission: (A) autosomal recessive, (B) X-linked, (C) autosomal dominant, (D) microscopic chromosome rearrangements, (E) submicroscopic copy number changes, and (F) frequent ethnic diseases.

Results

Among affected and carrier patients worldwide, most reported mutant genes would be identified correctly according to one of four patient categories from at-risk couples with <64 tested genes to affected adults with 314 tested loci. Three clinically reported patient series confirmed this approach. First, only 54 targeted chromosomal sites would have detected all 938 microscopically visible unbalanced karyotypes among 4129 karyotyped POC, CVS, and amniocentesis samples. Second, 37 of 48 reported aneuploid regions were found among our 1265 clinical microarrays confirming the locations of 8 schizophrenia loci and 20 aneuploidies altering intellectual ability, while also identifying 9 of the most frequent deletion syndromes. Third, testing 15 frequent genes would have identified 124 couples with a 1 in 4 risk of a fetus with a recessive disease compared to the 127 couples identified by testing all 108 genes, while testing all mutations in 15 genes could have identified more couples.

Conclusion

Testing the most frequent disease causing abnormalities in 1 of 8 reported disease loci [~1 of 84 total genes] will identify ~7 of 8 reported abnormal Caucasian newborn genotypes. This would eliminate ~8 to 10 of ~10 Caucasian newborn gene sequences selected as abnormal that are actually normal variants identified when testing all ~2500 diseases looking for the remaining 1 of 8 disease causing genes. This approach enables more accurate testing within available laboratory and reimbursement resources.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-014-0333-8) contains supplementary material, which is available to authorized users.

NLRP7 affects trophoblast lineage differentiation, binds to overexpressed YY1 and alters CpG methylation

Maternal-effect mutations in NLRP7 cause rare biparentally inherited hydatidiform moles (BiHMs), abnormal pregnancies containing hypertrophic vesicular trophoblast but no embryo. BiHM trophoblasts display abnormal DNA methylation patterns affecting maternally methylated germline differentially methylated regions (gDMRs), suggesting that NLRP7 plays an important role in reprogramming imprinted gDMRs. How NLRP7-a component of the CATERPILLAR family of proteins involved in innate immunity and apoptosis-causes these specific DNA methylation and trophoblast defects is unknown. Because rodents lack NLRP7, we used human embryonic stem cells to study its function and demonstrate that NLRP7 interacts with YY1, an important chromatin-binding factor. Reduced NLRP7 levels alter DNA methylation and accelerate trophoblast lineage differentiation. NLRP7 thus appears to function in chromatin reprogramming and DNA methylation in the germline or early embryonic development, functions not previously associated with members of the NLRP family.

NLRP7 and related inflammasome activating pattern recognition receptors and their function in host defense and disease

Host defense requires the maturation and release of the pro-inflammatory cytokines interleukin (IL)-1β and IL-18 and the induction of pyroptotic cell death, which depends on the activation of inflammatory Caspases within inflammasomes by innate immune cells. Several cytosolic pattern recognition receptors (PRRs) have been implicated in this process in response to infectious and sterile agonists. Here we summarize the current knowledge on inflammasome-organizing PRRs, emphasizing the recently described NLRP7, and their implications in human disease.

Developmental expression and possible functional roles of mouse Nlrp4e in preimplantation embryos

Increasing evidence suggests that some Nlrp genes are crucial for oogenesis, folliculogenesis, and early embryonic development. Nlrp4e is one of seven copies of Nlrp4, which plays a putative role in the reproduction system in mice. Gene duplication is regarded as an important driving force behind the evolution of novel genes with new or altered functions. We investigated the role of Nlrp4e in oocyte and preimplantation embryos by determining its expression profile using quantitative real-time polymerase chain reaction. Nlrp4e mRNA accumulated during oogenesis. Moreover, Nlrp4e transcripts were upregulated during the two-cell stage and then declined sharply and became almost undetectable, which represents a crucial time for major embryonic genome activation in the mouse. Knockdown of Nlrp4e in fertilized eggs using RNA interference resulted in arrested development between the two- and eight-cell stages in a dose-dependent manner. However, targeted inhibition of Nlrp4e in germinal-vesicle-stage oocytes had no phenotypic effects on oocyte maturation. The above experiments were also carried out in parthenogenetic embryos to determine the effects of Nlrp4e in embryos without a paternal genome. The results of this study indicate that Nlrp4e, a maternal-zygotic-effect gene, may not be involved in oocyte maturation but may play a critical role in early embryogenesis.

NLRP7 mutation analysis in sporadic hydatidiform moles in Tunisian patients: NLRP7 and sporadic mole

CONTEXT

Hydatidiform mole, an aberrant human pregnancy, is commonly a nonrecurrent disease. Recently, a rare autosomal recessive form of familial and/or recurrent molar pregnancies was associated with mutations in the NLRP7 gene.

OBJECTIVE

To investigate whether NLRP7 mutations exist in Tunisian women with sporadic hydatidiform moles.

DESIGN

Genomic DNA from 38 unrelated Tunisian patients with sporadic hydatidiform moles were screened by sequencing all NLRP7 exons. A high-resolution melting curve analysis was performed on 170 DNA controls to analyze new sequence variants.

RESULTS

More than 13% of these patients were heterozygous for NLRP7 mutations. We found 2 novel missense mutations in the heterozygous state, c.544G>A (p.Val182Met) in 1 patient and c.1480G>A (p.Ala494Thr) in 2 patients, and 2 already reported mutations, c.1532A>G (p.Lys511Arg) and c.2156C>T (p.Ala719Val), in 2 patients. None of these mutations were identified in 170 controls except for 1 woman who was heterozygous for p.Val182Met.

CONCLUSION

As homozygous NLRP7 mutations are associated with recurrent hydatidiform mole or conception loss, the heterozygous state could represent a risk factor for nonrecurrent mole.

Diagnostic reproducibility of hydatidiform moles: ancillary techniques (p57 immunohistochemistry and molecular genotyping) improve morphologic diagnosis

Distinction of hydatidiform moles (HMs) from nonmolar specimens (NMs) and subclassification of HMs as complete hydatidiform moles (CHMs) and partial hydatidiform moles (PHMs) are important for clinical practice and investigational studies; yet, diagnosis based solely on morphology is affected by interobserver variability. Molecular genotyping can distinguish these entities by discerning androgenetic diploidy, diandric triploidy, and biparental diploidy to diagnose CHMs, PHMs, and NMs, respectively. Eighty genotyped cases (27 CHMs, 27 PHMs, and 26 NMs) were selected from a series of 200 potentially molar specimens previously diagnosed using p57 immunostaining and genotyping. Cases were classified by 3 gynecologic pathologists on the basis of H&E slides (masked to p57 immunostaining and genotyping results) into 1 of 3 categories (CHM, PHM, or NM) during 2 diagnostic rounds; a third round incorporating p57 immunostaining results was also conducted. Consensus diagnoses (those rendered by 2 of 3 pathologists) were determined. Genotyping results were used as the gold standard for assessing diagnostic performance. Sensitivity of a diagnosis of CHM ranged from 59% to 100% for individual pathologists and from 70% to 81% by consensus; specificity ranged from 91% to 96% for individuals and from 94% to 98% by consensus. Sensitivity of a diagnosis of PHM ranged from 56% to 93% for individual pathologists and from 70% to 78% by consensus; specificity ranged from 58% to 92% for individuals and from 74% to 85% by consensus. The percentage of correct classification of all cases by morphology ranged from 55% to 75% for individual pathologists and from 70% to 75% by consensus. The κ values for interobserver agreement ranged from 0.59 to 0.73 (moderate to good) for a diagnosis of CHM, from 0.15 to 0.43 (poor to moderate) for PHM, and from 0.13 to 0.42 (poor to moderate) for NM. The κ values for intraobserver agreement ranged from 0.44 to 0.67 (moderate to good). Addition of the p57 immunostain improved sensitivity of a diagnosis of CHM to a range of 93% to 96% for individual pathologists and 96% by consensus; specificity was improved from a range of 96% to 98% for individual pathologists and 96% by consensus; there was no substantial impact on diagnosis of PHMs and NMs. Interobserver agreement for interpretation of the p57 immunostain was 0.96 (almost perfect). Even with morphologic assessment by gynecologic pathologists and p57 immunohistochemistry, 20% to 30% of cases will be misclassified, and, in particular, distinction of PHMs and NMs will remain problematic.

An NLRP7-containing inflammasome mediates recognition of microbial lipopeptides in human macrophages

Cytosolic pathogen- and damage-associated molecular patterns are sensed by pattern recognition receptors, including members of the nucleotide-binding domain and leucine-rich repeat-containing gene family (NLR), which cause inflammasome assembly and caspase-1 activation to promote maturation and release of the inflammatory cytokines interleukin-1β (IL-1β) and IL-18 and induction of pyroptosis. However, the contribution of most of the NLRs to innate immunity, host defense, and inflammasome activation and their specific agonists are still unknown. Here we describe identification and characterization of an NLRP7 inflammasome in human macrophages, which is induced in response to microbial acylated lipopeptides. Activation of NLRP7 promoted ASC-dependent caspase-1 activation, IL-1β and IL-18 maturation, and restriction of intracellular bacterial replication, but not caspase-1-independent secretion of the proinflammatory cytokines IL-6 and tumor necrosis factor-α. Our study therefore increases our currently limited understanding of NLR activation, inflammasome assembly, and maturation of IL-1β and IL-18 in human macrophages.

Mosaics and moles

Hydatidiform mole (HM) is an abnormal human pregnancy, where the placenta presents with vesicular swelling of the chorionic villi. A fetus is either not present, or malformed and not viable. Most moles are diploid androgenetic as if one spermatozoon fertilized an empty oocyte, or triploid with one maternal and two paternal chromosome sets as if two spermatozoa fertilized a normal oocyte. However, diploid moles with both paternal and maternal markers of the nuclear genome have been reported. Among 162 consecutively collected diploid moles, we have earlier found indications of both maternal and paternal genomes in 11. In the present study, we have performed detailed analysis of DNA-markers in tissue and single cells from these 11 HMs. In 3/11, we identified one biparental cell population only, whereas in 8/11, we demonstrated mosaicism: one biparental cell population and one androgenetic cell population. One mosaic mole was followed by persistent trophoblastic disease (PTD). In seven of the mosaics, one spermatozoon appeared to have contributed to the genomes of both cell types. Our observations make it likely that mosaic conceptuses, encompassing an androgenetic cell population, result from various postzygotic abnormalities, including paternal pronuclear duplication, asymmetric cytokinesis, and postzygotic diploidization. This corroborates the suggestion that fertilization of an empty egg is not mandatory for the creation of an androgenetic cell population. Future studies of mosaic conceptuses may disclose details about fertilization, early cell divisions and differentiation. Apparently, only a minority of diploid moles with both paternal and maternal markers are 'genuine' diploid biparental moles (DiBiparHMs).

Inflammasomes and their activation

The innate immune system relies on the recognition of pathogens by pattern recognition receptors as a first line of defense and to initiate the adaptive immune response. Substantial progress has been made in defining the role of Nod (nucleotide-binding oligimerization domain)-like receptors and AIM2 (absent in melanoma 2) as pattern recognition receptors that activate inflammasomes in macrophages. Inflammasomes are protein platforms essential for the activation of inflammatory caspases and subsequent maturation of their pro-inflammatory cytokine substrates and induction of pyroptosis. This paper summarizes recent developments regarding the function of Nod-like receptors in immunity and disease.

[Review: Repetitive hydatidiform moles]

Repetitive moles are rare. They are either sporadic or familial, with or without consanguinity. Some of them can be explained by a NLRP7 mutation, which causes genomic parental imprinting alteration, with a preferential paternal phenotypic expression. Currently, no effective therapeutic solution has been developed. Among the 1687 patients declared to the French Trophoblastic Disease Reference Center, 13 presented at least two hydatidiform moles, thus less than 1% of the patients. A mutation of the NLRP7 gene was shown in six of 12 tested patients (50%) among whom three presented a homozygous mutation and three a heterozygous mutation. For an affected patient, type of mole can indifferently be a complete hydatidiform mole or a partial hydatidiform mole. We describe these cases and compare them to those already published.

A definitive haplotype map as determined by genotyping duplicated haploid genomes finds a predominant haplotype preference at copy-number variation events

The majority of complete hydatidiform moles (CHMs) harbor duplicated haploid genomes that originate from sperm. This makes CHMs more advantageous than conventional diploid cells for determining haplotypes of SNPs and copy-number variations (CNVs), because all of the genetic variants in a CHM genome are homozygous. Here we report SNP and CNV haplotype structures determined by analysis of 100 CHMs from Japanese subjects via high-density DNA arrays. The obtained haplotype map should be useful as a reference for the haplotype structure of Asian populations. We resolved common CNV regions (merged CNV segments across the examined samples) into CNV events (clusters of CNV segments) on the basis of mutual overlap and found that the haplotype backgrounds of different CNV events within the same CNV region were predominantly similar, perhaps because of inherent structural instability.

Three-dimensional structure of the NLRP7 pyrin domain: insight into pyrin-pyrin-mediated effector domain signaling in innate immunity

The innate immune system provides an initial line of defense against infection. Nucleotide-binding domain- and leucine-rich repeat-containing protein (NLR or (NOD-like)) receptors play a critical role in the innate immune response by surveying the cytoplasm for traces of intracellular invaders and endogenous stress signals. NLRs themselves are multi-domain proteins. Their N-terminal effector domains (typically a pyrin or caspase activation and recruitment domain) are responsible for driving downstream signaling and initiating the formation of inflammasomes, multi-component complexes necessary for cytokine activation. However, the currently available structures of NLR effector domains have not yet revealed the mechanism of their differential modes of interaction. Here, we report the structure and dynamics of the N-terminal pyrin domain of NLRP7 (NLRP7 PYD) obtained by NMR spectroscopy. The NLRP7 PYD adopts a six-alpha-helix bundle death domain fold. A comparison of conformational and dynamics features of the NLRP7 PYD with other PYDs showed distinct differences for helix alpha3 and loop alpha2-alpha3, which, in NLRP7, is stabilized by a strong hydrophobic cluster. Moreover, the NLRP7 and NLRP1 PYDs have different electrostatic surfaces. This is significant, because death domain signaling is driven by electrostatic contacts and stabilized by hydrophobic interactions. Thus, these results provide new insights into NLRP signaling and provide a first molecular understanding of inflammasome formation.

Evolution and functional divergence of NLRP genes in mammalian reproductive systems

Background

NLRPs (Nucleotide-binding oligomerization domain, Leucine rich Repeat and Pyrin domain containing Proteins) are members of NLR (Nod-like receptors) protein family. Recent researches have shown that NLRP genes play important roles in both mammalian innate immune system and reproductive system. Several of NLRP genes were shown to be specifically expressed in the oocyte in mammals. The aim of the present work was to study how these genes evolved and diverged after their duplication, as well as whether natural selection played a role during their evolution.

Results

By using in silico methods, we have evaluated the evolution and functional divergence of NLRP genes, in particular of mouse reproduction-related Nlrp genes. We found that (1) major NLRP genes have been duplicated before the divergence of mammals, with certain lineage-specific duplications in primates (NLRP7 and 11) and in rodents (Nlrp1, 4 and 9 duplicates); (2) tandem duplication events gave rise to a mammalian reproduction-related NLRP cluster including NLRP2, 4, 5, 7, 8, 9, 11, 13 and 14 genes; (3) the function of mammalian oocyte-specific NLRP genes (NLRP4, 5, 9 and 14) might have diverged during gene evolution; (4) recent segmental duplications concerning Nlrp4 copies and vomeronasal 1 receptor encoding genes (V1r) have been undertaken in the mouse; and (5) duplicates of Nlrp4 and 9 in the mouse might have been subjected to adaptive evolution.

Conclusion

In conclusion, this study brings us novel information on the evolution of mammalian reproduction-related NLRPs. On the one hand, NLRP genes duplicated and functionally diversified in mammalian reproductive systems (such as NLRP4, 5, 9 and 14). On the other hand, during evolution, different lineages adapted to develop their own NLRP genes, particularly in reproductive function (such as the specific expansion of Nlrp4 and Nlrp9 in the mouse).

Invasive hydatidiform mole: immunohistochemical labelling of inhibin/activin subunits, Ki67, p53 and glycodelin A in a rare case

Invasive trophoblastic mole is an extremely rare condition. Its early recognition is essential since it can transform into an invasive type of tumour. Immunohistochemistry was performed with monoclonal antibodies against inhibin-alpha, -betaA and -betaB, Ki67, p53 and glycodelin A in a rare case of accidentally diagnosed invasive trophoblastic mole. There was labelling of the inhibin/activin subunits, Ki67 and p53, while glycodelin A showed minimal immunopositivity. Therefore, since the pathological diagnosis of an invasive mole is difficult, the immunohistochemical detection of inhibin/activin subunits, Ki67, p53 and glycodelin A might be additional useful tumour markers.

The inflammasomes: guardians of the body

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1beta and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.

Horror autoinflammaticus: the molecular pathophysiology of autoinflammatory disease (*)

The autoinflammatory diseases are characterized by seemingly unprovoked episodes of inflammation, without high-titer autoantibodies or antigen-specific T cells. The concept was proposed ten years ago with the identification of the genes underlying hereditary periodic fever syndromes. This nosology has taken root because of the dramatic advances in our knowledge of the genetic basis of both mendelian and complex autoinflammatory diseases, and with the recognition that these illnesses derive from genetic variants of the innate immune system. Herein we propose an updated classification scheme based on the molecular insights garnered over the past decade, supplanting a clinical classification that has served well but is opaque to the genetic, immunologic, and therapeutic interrelationships now before us. We define six categories of autoinflammatory disease: IL-1beta activation disorders (inflammasomopathies), NF-kappaB activation syndromes, protein misfolding disorders, complement regulatory diseases, disturbances in cytokine signaling, and macrophage activation syndromes. A system based on molecular pathophysiology will bring greater clarity to our discourse while catalyzing new hypotheses both at the bench and at the bedside.

The Inflammasomes: Guardians of the Body

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1β and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.

The Inflammasomes: Guardians of the Body

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1β and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.

The Inflammasomes: Guardians of the Body

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1β and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.

The Inflammasomes: Guardians of the Body

The innate immune system relies on its capacity to rapidly detect invading pathogenic microbes as foreign and to eliminate them. The discovery of Toll-like receptors (TLRs) provided a class of membrane receptors that sense extracellular microbes and trigger antipathogen signaling cascades. More recently, intracellular microbial sensors have been identified, including NOD-like receptors (NLRs). Some of the NLRs also sense nonmicrobial danger signals and form large cytoplasmic complexes called inflammasomes that link the sensing of microbial products and metabolic stress to the proteolytic activation of the proinflammatory cytokines IL-1β and IL-18. The NALP3 inflammasome has been associated with several autoinflammatory conditions including gout. Likewise, the NALP3 inflammasome is a crucial element in the adjuvant effect of aluminum and can direct a humoral adaptive immune response. In this review, we discuss the role of NLRs, and in particular the inflammasomes, in the recognition of microbial and danger components and the role they play in health and disease.

Androgenetic embryonic stem cells form neural progenitor cells in vivo and in vitro

Uniparental zygotes with two paternal (androgenetic [AG]) or two maternal (gynogenetic [GG]; parthenogenetic [PG]) genomes are not able to develop into viable offspring but can form blastocysts from which embryonic stem cells (ESCs) can be derived. Although some aspects of the in vitro and in vivo differentiation potential of PG and GG ESCs of several species have been studied, the developmental capacity of AG ESCs is much less clear. Here, we investigate the potential of murine AG ESCs to undergo neural differentiation. We observed that AG ESCs differentiate in vitro into pan-neural progenitor cells (pnPCs) that further give rise to cells that express neuronal- and astroglial-specific markers. Neural progeny of in vitro-differentiated AG ESCs exhibited fidelity of expression of six imprinted genes analyzed, with the exception of Ube3a. Bisulfite sequencing for two imprinting control regions suggested that pnPCs predominantly maintained their methylation pattern. Following blastocyst injection of AG and biparental (normal fertilized [N]) ESCs, we found widespread and evenly distributed contribution of ESC-derived cells in both AG and N chimeric early fetal brains. AG and N ESC-derived cells isolated from chimeric fetal brains by fluorescence-activated cell sorting exhibited similar neurosphere-initiating cell frequencies and neural multilineage differentiation potential. Our results indicate that AG ESC-derived neural progenitor/stem cells do not differ from N neural progenitor/stem cells in their self-renewal and neural multilineage differentiation potential. Disclosure of potential conflicts of interest is found at the end of this article.

A recurrent intragenic genomic duplication, other novel mutations in NLRP7 and imprinting defects in recurrent biparental hydatidiform moles

A complete hydatidiform mole (CHM) is an abnormal pregnancy with hyperproliferative vesicular trophoblast and no fetal development. Most CHM are sporadic and androgenetic, but recurrent HM have biparental inheritance (BiHM) with disrupted DNA methylation at differentially methylated regions (DMRs) of imprinted loci. Some women with recurrent BiHM have mutations in the NLRP7 gene on chromosome 19q13.42. Using bisulfite genomic sequencing at eight imprinted DMRs on DNA from two BiHMs, we found a pattern of failure to acquire or maintain DNA methylation at DMRs (PEG3, SNRPN, KCNQ1OT1, GNAS exon 1A) that normally acquire CpG methylation during oogenesis, but not at H19, which acquires CpG methylation during spermatogenesis. Secondary imprints at the GNAS locus showed variable abnormal patterns with both gain and loss of CpG methylation. We found novel missense and splice-site mutations in NLRP7 in women with non-familial recurrent BiHM. We identified and characterized a homozygous intragenic tandem duplication including exons 2 through 5 of NLRP7 that results in a predicted truncated protein in affected women of three unrelated Egyptian kindreds, suggesting a founder effect. Our findings firmly establish that NLRP7 mutations are a major cause of BiHM and confirm presence of a complex pattern of imprinting abnormalities in BiHM tissues.

From inflammasomes to fevers, crystals and hypertension: how basic research explains inflammatory diseases

Pattern-recognition receptors, such as Toll-like receptors and NOD-like receptors (NLRs), are able through the recognition of pathogen-associated molecular patterns and danger-associated molecular patterns to sense microbe-dependent and microbe-independent danger and thereby initiate innate immune responses. In some autoinflammatory conditions, abnormalities in NLR signaling pathways are involved in pathogenesis, as exemplified by NOD2 mutations associated with Crohn's disease. Some other NLRs are components of the inflammasome, a caspase-1- and prointerleukin-1beta-activating complex. Clinical and experimental studies are beginning to reveal the central role of the inflammasome in innate immunity. Here, we focus on monogenic hereditary inflammatory diseases, such as Muckle-Wells syndrome, which are associated with mutations in proteins that modulate the activity of the inflammasome, and on some multifactorial disorders, such as Type 2 diabetes and hypertension.

NALP inflammasomes: a central role in innate immunity

Inflammasomes are cytoplasmic multiprotein complexes that mediate the maturation of the proinflammatory cytokines interleukin-1beta (IL-1beta), IL-18, and possibly IL-33 by controlling the activation of the inflammatory caspases-1 and -5. Assembly of inflammasomes depends on NOD-like receptor (NLR) family members such as NALPs, NAIP, and IPAF. Various microbial and endogenous stimuli activate different types of inflammasomes. This article focuses on the Pyrin domain containing NLRs, known as NALP proteins. Recent findings provide exciting insights into how these proteins might be activated and also provide evidence of the critical role of the NALP inflammasomes in innate immunity and inflammatory diseases.