Study of the structure and impact of human leukocyte antigen (HLA)-G-A, HLA-G-B, and HLA-G-DRB1 haplotypes in families with recurrent miscarriage

Recurrent Pregnancy Loss Etiology, Risk Factors, Diagnosis, and Management. Fresh Look into a Full Box

Recurrent pregnancy loss is a complex health challenge with no universally accepted definition. Inconsistency in definitions involves not only the number of spontaneous abortions (two or three) that are accepted for recurrent pregnancy loss but the types of pregnancy and gestational age at miscarriage. Due to the heterogeneity of definitions and criteria applied by international guidelines for recurrent pregnancy loss, the true incidence of recurrent miscarriage, which is reported to range from 1% to 5%, is difficult to estimate. Moreover, the exact etiology of recurrent pregnancy loss remains questionable; thus, it is considered a polyetiological and multifactorial condition with many modifiable and non-modifiable factors involved. Even after thoroughly evaluating recurrent pregnancy loss etiology and risk factors, up to 75% of cases remain unexplained. This review aimed to summarize and critically analyze accumulated knowledge on the etiology, risk factors, relevant diagnostic options, and management approach to recurrent pregnancy loss. The relevance of various factors and their proposed roles in recurrent pregnancy loss pathogenesis remains a matter of discussion. The diagnostic approach and the management largely depend on the etiology and risk factors taken into consideration by a healthcare professional as a cause of recurrent miscarriage for a particular woman or couple. Underestimation of social and health consequences of recurrent pregnancy loss leads to compromised reproductive health and psychological well-being of women after miscarriage. Studies on etiology and risk factors for recurrent pregnancy loss, especially idiopathic, should be continued. The existing international guidelines require updates to assist clinical practice.

Pregnancy loss is associated with type 2 diabetes: a nationwide case-control study

AIMS/HYPOTHESIS

Type 2 diabetes is killing more people than ever, and early-life predictors remain critical for the development of effective preventive strategies. Pregnancy loss is a common event associated with later atherosclerotic disease and ischaemic heart failure and might constitute a predictor for type 2 diabetes. The objective of this study was to investigate whether pregnancy loss is associated with later development of type 2 diabetes.

METHODS

Using a Danish nationwide cohort, we identified all women born from 1957 through to 1997 and who had a diagnosis of type 2 diabetes during the period 1977 to 2017. The women were matched 1:10 on year of birth and educational level to women without diabetes in the general Danish population. Conditional logistic regression models provided odds ratios for type 2 diabetes with different numbers of pregnancy losses.

RESULTS

We identified 24,774 women with type 2 diabetes and selected 247,740 controls without diabetes. Women who had ever been pregnant (ever-pregnant women) with 1, 2 and ≥ 3 pregnancy losses had ORs of type 2 diabetes of 1.18 (95% CI 1.13, 1.23), 1.38 (95% CI 1.27, 1.49) and 1.71 (95% CI 1.53, 1.92) compared with ever-pregnant women with no pregnancy losses, respectively. Women who never achieved a pregnancy had an OR of type 2 diabetes of 1.56 (95% CI 1.51, 1.61) compared with ever-pregnant women with any number of losses. Similar results were found after adjustment for obesity and gestational diabetes.

CONCLUSIONS/INTERPRETATION

We found a significant and consistent association between pregnancy loss and later type 2 diabetes that increased with increasing number of losses. Thus, pregnancy loss and recurrent pregnancy loss are significant risk factors for later type 2 diabetes. Future studies should explore whether this association is due to common background factors or whether prediabetic metabolic conditions are responsible for this association. Graphical abstract.

Pregnancy Loss and Cancer Risk: A Nationwide Observational Study

BACKGROUND

Cancer is the second leading cause of death worldwide. Few studies have investigated if recurrent pregnancy loss is associated with an increased risk of cancer. We aimed to assess whether pregnancy loss is associated with later cancer development.

METHODS

We identified all invasive cancers after age 40, among all Danish women born between January 1957 and December 1972, ensuring a full reproductive history. Cases were matched by birth year 1:10 to cancer-free controls. Women were followed until the end of 2017. The number of pregnancy losses (miscarriages or still births) was correlated to long-term cancer risk using conditional logistic regression, providing odds ratios for specific cancers with different numbers of pregnancy losses, all adjusted for age, education, and other potential confounders.

FINDINGS

The study included 28,785 women with cancer (mean age 48.7 [SD 5.0]) and 283,294 matched controls (mean age 48.6 [SD 5.0]). We found no overall association between pregnancy loss and later development of 11 site-specific types of cancer or cancer overall. Taking the sequence of pregnancy losses into account, primary recurrent pregnancy loss (three consecutive pregnancy losses without prior live birth) was associated with later overall cancer by an odds ratio of 1.27 (1.04-1.56). Secondary recurrent pregnancy loss showed no association to cancer.

INTERPRETATION

Pregnancy loss was not associated with later cancer development. Women with primary recurrent pregnancy loss had a borderline significant association to later cancer overall, this may be a chance finding.

FUNDING

Ole Kirk's Foundation and Copenhagen University Hospital Rigshospitalet's Research Grant.

HLAIb worldwide genetic diversity: New HLA-H alleles and haplotype structure description

The classical HLA class I genes (HLA Ia) were extensively studied because of their implication in clinical fields and anthropology. Less is known about worldwide genetic diversity and linkage disequilibrium for non-classical HLA class I genes (HLA Ib) and HLA pseudogenes. Notably, HLA-H, which is deleted in a fraction of the population, remains scarcely explored. The aims of this study were 1/ to get further insight into HLA-H genetic diversity and into how this variability potentially affects its expression and 2/ to define HLA Ib worldwide allelic diversity and linkage. Exome sequence data from the 1000 Genomes Project were used to define second field HLA-A, -E, -F, -G and -H typing using PolyPheMe software. Allelic and two-loci haplotype frequencies were estimated using Gene[Rate] software both at worldwide and continental levels. Eleven novel HLA-H alleles identified in exome data were validated by NGS performed on 25 genomic DNA samples from the same cohort. Phylogenetic analysis and frequency distribution of HLA-H alleles revealed three clades, each predominantly represented in Admixed American, European and East Asian populations, African populations and South Asian populations. Among these eleven novel alleles, two potentially encode complete transmembrane HLA proteins. We confirm the high LD between HLA-H and -A, and between HLA-H and -G, and show the three genes have distinct worldwide allelic distribution. Conversely, HLA-E and HLA-F both showed little LD, displayed restricted allelic diversity and practically no difference in their distribution across the planet. Our work thus reveals an unexpectedly high HLA-H genetic diversity, with alleles highly represented in Asia possibly encoding a functional HLA protein. Functional implication of these results remains to be explored, both in physiological and pathological contexts.

Vitamin D, autoimmunity and recurrent pregnancy loss: More than an association

Recurrent pregnancy loss (RPL) affects close to 1% of couples; however, the etiology is known in only about 50% of the cases. Recent studies show that autoimmune dysregulation is a probable cause of RPL, which in some cases may be overlooked. In order for a pregnancy to proceed to term, early modulation of immunologic response is required to induce tolerance to the semi-allogenic fetus. Certain subsets of both the innate and adaptive immune responses play a role in the induction of fetomaternal tolerance. A relatively predominant T-cell helper (Th) 2 and T regulatory (Treg) cell population seem to favor a better pregnancy outcome, whereas Th1 and Th17 cell populations appear to have an opposite effect. Lately, the role of vitamin D in the modulation of immune response was established. Vitamin D has been shown to promote a more favorable environment for pregnancy through various mechanisms, such as enhancement of the shift toward Th2 cells and regulation of immune cell differentiation and cytokine secretion. Therefore, it seems that vitamin D deficiency sways the balance toward a worse outcome and may play a part in recurrent pregnancy loss. This review sheds light on the immunologic changes, which occur in early pregnancy and the regulatory role vitamin D has in the maintenance of this delicate balance.

Association of HLA-A and Non-Classical HLA Class I Alleles

The HLA-A locus is surrounded by HLA class Ib genes: HLA-E, HLA-H, HLA-G and HLA-F. HLA class Ib molecules are involved in immuno-modulation with a central role for HLA-G and HLA-E, an emerging role for HLA-F and a yet unknown function for HLA-H. Thus, the principal objective of this study was to describe the main allelic associations between HLA-A and HLA-H, -G, -F and -E. Therefore, HLA-A, -E, -G, -H and -F coding polymorphisms, as well as HLA-G UnTranslated Region haplotypes (referred to as HLA-G UTRs), were explored in 191 voluntary blood donors. Allelic frequencies, Global Linkage Disequilibrium (GLD), Linkage Disequilibrium (LD) for specific pairs of alleles and two-loci haplotype frequencies were estimated. We showed that HLA-A, HLA-H, HLA-F, HLA-G and HLA-G UTRs were all in highly significant pairwise GLD, in contrast to HLA-E. Moreover, HLA-A displayed restricted associations with HLA-G UTR and HLA-H. We also confirmed several associations that were previously found to have a negative impact on transplantation outcome. In summary, our results suggest complex functional and clinical implications of the HLA-A genetic region.

Association of HLA-G 3' Untranslated Region Polymorphisms with Systemic Lupus Erythematosus in a Japanese Population: A Case-Control Association Study

HLA-G plays a role in fetal-maternal tolerance as well as immunoregulation, and has been suggested to be involved in autoimmune diseases and cancers. HLA-G encodes two potentially functional polymorphisms in the 3' untranslated region, 14bp insertion/deletion (14bp indel, rs371194629) and a single nucleotide polymorphism rs1063320, previously reported to affect HLA-G expression level or splicing isoform and to be associated with susceptibility to systemic lupus erythematosus (SLE). However, the results of SLE association studies are inconsistent, probably due to the small sample size of each study and lack of consideration of linkage disequilibrium (LD) with HLA-class II haplotypes in each population. In this study, we performed association studies of these polymorphisms on 843 patients with SLE and 778 healthy controls in a Japanese population, in many of whom HLA-DRB1 alleles have been genotyped at the four-digit level. LD was detected between DRB1*13:02, protective against multiple autoimmune diseases in the Japanese, and the rs1063320 G (D' = 0.86, r2 = 0.02) and with 14bp del (D' = 0.62, r2 = 0.01), but not between SLE-susceptible DRB1*15:01 and HLA-G. Although significant association with overall SLE was not detected, 14bp ins allele was significantly associated with SLE with the age of onset <20 years, when compared with healthy controls (P = 0.0067, PFDR = 0.039, OR 1.44, additive model) or with SLE patients with the age of onset ≥20 (P = 0.033, PFDR = 0.0495, OR 2.09, additive model). This association remained significant after conditioning on DRB1*13:02 or DRB1*15:01. On the other hand, significant association was detected between rs1063320 C and anti-RNP antibody and anti-Sm antibody positive SLE, which was dependent on negative LD with DRB1*13:02. eQTL analysis showed reduced HLA-G mRNA level in 14bp ins/ins individuals. In conclusion, our observations showed that HLA-G 14bp ins allele represents a genetic contribution on early-onset SLE independent of DRB1.

Immunogenetic contributions to recurrent pregnancy loss

While sporadic pregnancy loss is common, occurring in 15 % of pregnancies, recurrent pregnancy loss (RPL) impacts approximately 5 % of couples. Though multiple causes are known (including structural, hormonal, infectious, autoimmune, and thrombophilic causes), after evaluation, roughly half of all cases remain unexplained. The idiopathic RPL cases pose a challenging therapeutic dilemma in addition to incurring much physical and emotional morbidity. Immunogenetic causes have been postulated to contribute to these cases of RPL. Natural Killer cell, T cell expression pattern changes in the endometrium have both been shown in patients with RPL. Human leukocyte antigen (HLA) and cytokine allelic variations have also been studied as etiologies for RPL. Some of the results have been promising, however the studies are small and have not yet put forth outcomes that would change our current diagnosis and management of RPL. Larger database studies are needed with stricter control criteria before reasonable conclusions can be drawn.

[SINGLE NUCLEOTIDE POLYMORPHISMS IN HUMAN PROGESTERONE RECEPTOR GENE AND ITS VALUE IN MISCARRIAGE OR PRETERM DELIVERY]

This article presents the current understanding of progesterone and its role in female reproductive function, described the structure and functionality of the progesterone receptor. The attention is focused on the meaning of the terms miscarriage and preterm delivery. Was described the today known causes of the miscarriage and preterm delivery, shown the value of single nucleotide polymorphisms of the progesterone receptor in miscarriage and preterm delivery by the analysis of publications in recent years in order to find connections between different polymorphisms of the progesterone receptor gene and a spontaneous abortion, premature labor, recurrent miscarriage and its impact on progesterone therapy.

Ex vivo immunosuppressive effects of mesenchymal stem cells on Crohn's disease mucosal T cells are largely dependent on indoleamine 2,3-dioxygenase activity and cell-cell contact

Introduction

Crohn’s disease (CD) is a disabling chronic enteropathy sustained by a harmful T-cell response toward antigens of the gut microbiota in genetically susceptible subjects. Growing evidence highlights the safety and possible efficacy of mesenchymal stem cells (MSCs) as a new therapeutic tool for this condition. Therefore, we aimed to investigate the effects of bone marrow-derived MSCs on pathogenic T cells with a view to clinical application.

Methods

T-cell lines from both inflamed and non-inflamed colonic mucosal specimens of CD patients and from healthy mucosa of control subjects were grown with the antigen muramyl-dipeptide in the absence or presence of donors’ MSCs. The MSC effects were evaluated in terms of T-cell viability, apoptotic rate, proliferative response, immunophenotype, and cytokine profile. The role of the indoleamine 2,3-dioxygenase (IDO) was established by adding a specific inhibitor, the 1-methyl-DL-tryptophan, and by using MSCs transfected with the small interfering RNA (siRNA) targeting IDO. The relevance of cell-cell contact was evaluated by applying transwell membranes.

Results

A significant reduction in both cell viability and proliferative response to muramyl-dipeptide, with simultaneous increase in the apoptotic rate, was found in T cells from both inflamed and non-inflamed CD mucosa when co-cultured with MSCs and was reverted by inhibiting IDO activity and expression. A reduction of the activated CD4⁺CD25⁺ subset and increase of the CD3⁺CD69⁺ population were also observed when T-cell lines from CD mucosa were co-cultured with MSCs. In parallel, an inhibitory effect was evident on the expression of the pro-inflammatory cytokines tumor necrosis factor-α, interferon-γ, interleukin-17A and -21, whereas that of the transforming growth factor-β and interleukin-6 were increased, and production of the tolerogenic molecule soluble HLA-G was high. These latter effects were almost completely eliminated by blocking the IDO, whose activity was upregulated in MSCs co-cultured with CD T cells. The use of a semipermeable membrane partially inhibited the MSC immunosuppressive effects. Finally, hardly any effects of MSCs were observed when T cells obtained from control subjects were used.

Conclusion

MSCs exert potent immunomodulant effects on antigen-specific T cells in CD through a complex paracrine and cell-cell contact-mediated action, which may be exploited for widespread therapeutic use.

Electronic supplementary material

The online version of this article (doi:10.1186/s13287-015-0122-1) contains supplementary material, which is available to authorized users.

Insights into HLA-G Genetics Provided by Worldwide Haplotype Diversity

Human leukocyte antigen G (HLA-G) belongs to the family of non-classical HLA class I genes, located within the major histocompatibility complex (MHC). HLA-G has been the target of most recent research regarding the function of class I non-classical genes. The main features that distinguish HLA-G from classical class I genes are (a) limited protein variability, (b) alternative splicing generating several membrane bound and soluble isoforms, (c) short cytoplasmic tail, (d) modulation of immune response (immune tolerance), and (e) restricted expression to certain tissues. In the present work, we describe the HLA-G gene structure and address the HLA-G variability and haplotype diversity among several populations around the world, considering each of its major segments [promoter, coding, and 3′ untranslated region (UTR)]. For this purpose, we developed a pipeline to reevaluate the 1000Genomes data and recover miscalled or missing genotypes and haplotypes. It became clear that the overall structure of the HLA-G molecule has been maintained during the evolutionary process and that most of the variation sites found in the HLA-G coding region are either coding synonymous or intronic mutations. In addition, only a few frequent and divergent extended haplotypes are found when the promoter, coding, and 3′UTRs are evaluated together. The divergence is particularly evident for the regulatory regions. The population comparisons confirmed that most of the HLA-G variability has originated before human dispersion from Africa and that the allele and haplotype frequencies have probably been shaped by strong selective pressures.

Relationship between HLA-G polymorphism and susceptibility to recurrent miscarriage: a meta-analysis of non-family-based studies

PURPOSE

The HLA-G 14-bp insertion/deletion polymorphism had been inconsistently associated with recurrent miscarriage (RM) risk. We examined the association by performing a meta-analysis.

METHODS

Eligible articles were searched in PubMed, EMBASE and CNKI without language limitation. We included all the articles about two or more miscarriages associated with HLA-G 14-bp polymorphism. The odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of associations. Statistical analyses were performed by the STATA10.0 software.

RESULTS

17 studies were included, representing 1786 cases and 1574 controls. The current meta-analysis showed that 14-bp polymorphism was not associated with RM risk in all genetic models and allele contrast(+14 bp vs. -14 bp: OR = 1.13; 95% CI, 0.96,1.32; +14 bp/+14 bp vs. -14 bp/-14 bp: OR = 1.16, 95% CI, 0.85, 1.59; +14 bp/-14 bp vs. -14 bp/-14 bp: OR = 1.21, 95% CI, 0.92,1.58; dominant model: OR = 1.33; 95% CI, 0.99,1.78; recessive model: OR = 1.06; 95% CI, 0.79,1.43). Moreover, a significant heterogeneity was evident across studies. On the other hand, the subgroup analysis demonstrated that there was a significant association between HLA-G 14-bp polymorphism and patients with three or more miscarriages(+14 bp vs. -14 bp: OR = 1.27; 95% CI, 1.04, 1.55; dominant model: OR = 1.52; 95% CI, 1.16, 1.99; and model +14 bp/-14 bp versus -14 bp/-14 bp: OR = 1.51; 95% CI, 1.15, 1.97;).

CONCLUSIONS

Our comprehensive meta-analysis indicated that there was insufficient evidence to demonstrate a conclusive association between the HLA-G 14-bp insertion/deletion polymorphism and the risk of RM. But HLA-G 14-bp insertion/deletion polymorphic variation was associated with RM risk in patients with three or more miscarriages. Larger and well-designed studies may eventually provide a better, comprehensive understanding of the association between the HLA-G 14-bp insertion/deletion polymorphism and RM in the future.

HLA-G5 induces IL-4 secretion critical for successful pregnancy through differential expression of ILT2 receptor on decidual CD4⁺ T cells and macrophages

Successful pregnancy in humans has been associated with production of IL-4 by T cells at the feto-maternal interface. Soluble HLA-G5 produced by trophoblasts potentially controls the decidual T cell cytokine profile. We studied the effect of HLA-G5 on the cytokine profile of purified human macrophages and Ag-specific T cells in vitro. We demonstrated that HLA-G5 increased production of IL-12 by purified peripheral blood macrophages. Although IL-12 production by macrophages is known to induce IFN-γ production by CD4(+) T cells, HLA-G5 increased production of IL-4 but not IFN-γ by CD4(+) T cells after Ag presentation by macrophages. We found that this apparent paradox was due to the differential expression of the ILT2 HLA-G5 receptor on activated T cells and macrophages. This receptor was upregulated in the former and downregulated in the latter after Ag presentation and activation of both cell types. This observation was confirmed in situ, where decidual macrophages and T cells are continuously exposed to HLA-G5 produced locally and activated by trophoblast alloantigens. Freshly isolated decidua basalis macrophages expressed lower levels of ILT2 than peripheral blood macrophages from the same pregnant women. They did not spontaneously produce IL-12, whereas freshly isolated decidual CD4(+) T cells expressed high levels of activation markers (CD25, HLA-DR, and CD69) as well as ILT2 and spontaneously produced IL-4 but not IFN-γ. Therefore, HLA-G5 could be responsible, at least in part, via its interaction with ILT2, for decidual T cell IL-4 production, known to be crucial for successful pregnancy.

HLA-G 3' untranslated region polymorphisms are associated with systemic lupus erythematosus in 2 Brazilian populations

OBJECTIVE

HLA-G has well recognized tolerogenic properties in physiological and nonphysiological conditions. The 3' untranslated region (3'UTR) of the HLA-G gene has at least 3 polymorphic sites (14-bpINS/DEL, +3142C/G, and +3196C/G) described as associated with posttranscriptional influence on messenger RNA production; however, only the 14-bpINS/DEL and +3142C/G sites have been studied in systemic lupus erythematosus (SLE).

METHODS

We investigated the HLA-G 3'UTR polymorphic sites (14-bpINS/DEL, +3003C/T, +3010C/G, +3027A/C, +3035C/T, +3142C/G, +3187A/G, and +3196C/G) in 190 Brazilian patients with SLE and 282 healthy individuals in allele, genotype, and haplotype analyses. A multiple logistic regression model was used to assess the association of the disease features with the HLA-G 3'UTR haplotypes.

RESULTS

Increased frequencies were observed of the 14-bpINS (p = 0.053), +3010C (p = 0.008), +3142G (p = 0.006), and +3187A (p = 0.013) alleles, and increased frequencies of the 14-bpINS-INS (p = 0.094), +3010 C-C (p = 0.033), +3142 G-G (p = 0.021), and +3187 A-A (p = 0.035) genotypes. After Bonferroni correction, only the +3142G (p = 0.05) and +3010C (p = 0.06) alleles were overrepresented in SLE patients. The UTR-1 haplotype (14-bpDEL/+3003T/+3010G/+3027C/+3035C/+3142C/+3187G/+3196C) was underrepresented in SLE (pcorr = 0.035).

CONCLUSION

These results indicate that HLA-G 3'UTR polymorphic sites, particularly +3142G and +3010C alleles, were associated with SLE susceptibility, whereas UTR-1 was associated with protection against development of SLE.

Genetics of recurrent miscarriage: challenges, current knowledge, future directions

Recurrent miscarriage (RM) occurs in 1-3% of couples aiming at childbirth. Due to multifactorial etiology the clinical diagnosis of RM varies. The design of genetic/"omics" studies to identify genes and biological mechanisms involved in pathogenesis of RM has challenges as there are several options in defining the study subjects (female patient and/or couple with miscarriages, fetus/placenta) and controls. An ideal study would attempt a trio-design focusing on both partners as well as pregnancies of the couple. Application of genetic association studies focusing on pre-selected candidate genes with potential pathological effect in RM show limitations. Polymorphisms in ∼100 genes have been investigated and association with RM is often inconclusive or negative. Also, implication of prognostic molecular diagnostic tests in clinical practice exhibits uncertainties. Future directions in investigating biomolecular risk factors for RM rely on integrating alternative approaches (SNPs, copy number variations, gene/protein expression, epigenetic regulation) in studies of single genes as well as whole-genome analysis. This would be enhanced by collaborative network between research centers and RM clinics.

Transancestral mapping of the MHC region in systemic lupus erythematosus identifies new independent and interacting loci at MSH5, HLA-DPB1 and HLA-G

Objectives

Systemic lupus erythematosus (SLE) is a chronic multisystem genetically complex autoimmune disease characterised by the production of autoantibodies to nuclear and cellular antigens, tissue inflammation and organ damage. Genome-wide association studies have shown that variants within the major histocompatibility complex (MHC) region on chromosome 6 confer the greatest genetic risk for SLE in European and Chinese populations. However, the causal variants remain elusive due to tight linkage disequilibrium across disease-associated MHC haplotypes, the highly polymorphic nature of many MHC genes and the heterogeneity of the SLE phenotype.

Methods

A high-density case-control single nucleotide polymorphism (SNP) study of the MHC region was undertaken in SLE cohorts of Spanish and Filipino ancestry using a custom Illumina chip in order to fine-map association signals in these haplotypically diverse populations. In addition, comparative analyses were performed between these two datasets and a northern European UK SLE cohort. A total of 1433 cases and 1458 matched controls were examined.

Results

Using this transancestral SNP mapping approach, novel independent loci were identified within the MHC region in UK, Spanish and Filipino patients with SLE with some evidence of interaction. These loci include HLA-DPB1, HLA-G and MSH5 which are independent of each other and HLA-DRB1 alleles. Furthermore, the established SLE-associated HLA-DRB1*15 signal was refined to an interval encompassing HLA-DRB1 and HLA-DQA1. Increased frequencies of MHC region risk alleles and haplotypes were found in the Filipino population compared with Europeans, suggesting that the greater disease burden in non-European SLE may be due in part to this phenomenon.

Conclusion

These data highlight the usefulness of mapping disease susceptibility loci using a transancestral approach, particularly in a region as complex as the MHC, and offer a springboard for further fine-mapping, resequencing and transcriptomic analysis.

Secondary recurrent miscarriage and H-Y immunity

BACKGROUND

Approximately half recurrent miscarriage (RM) cases remain unexplained after standard investigations. Secondary RM (SRM) is, in contrast to primary RM, preceded by a birth, which increases the transfer of fetal cells into the maternal circulation. Mothers of boys are often immunized against male-specific minor histocompatibility (H-Y) antigens, and H-Y immunity can cause graft-versus-host disease after stem-cell transplantation. We proposed the H-Y hypothesis that aberrant H-Y immunity is a causal factor for SRM.

METHODS

This is a critical review of the H-Y hypothesis based on own publications and papers identified by systematic PubMed and EMBASE searches.

RESULTS

SRM is more common after the birth of a boy and the subsequent live birth rate is reduced for SRM patients with a firstborn boy. The male:female ratio of children born prior and subsequent to SRM is 1.49 and 0.76 respectively. Maternal carriage of HLA-class II alleles presenting H-Y antigens to immune cells is associated with a reduced live birth rate and increased risk of obstetric complications in surviving pregnancies in SRM patients with a firstborn boy. In early pregnancy, both antibodies against HLA and H-Y antigens are increased in SRM patients compared with controls. Presence of these antibodies in early pregnancy is associated with a lower live birth rate and a low male:female ratio in subsequent live births, respectively. Births of boys are also associated with subsequent obstetric complications in the background population.

CONCLUSIONS

Epidemiological, immunogenetic and immunological studies support the hypothesis that aberrant maternal H-Y immune responses have a pathogenic role in SRM.

Particular human leukocyte antigen alleles are associated with biochemical traits in the Japanese population

We analyzed genetic associations among 7 biochemical traits (fasting plasma glucose, HbA1c, total cholesterol, low-density lipoprotein [LDL] cholesterol, high-density lipoprotein cholesterol, triglyceride, and uric acid) and 6 HLA loci using 1,616 individuals who visited the Health Evaluation and Promotion Center at Tokai University Hospital. Significant differences between the individuals carrying particular HLA alleles and those not carrying the alleles in certain biochemical traits were observed by Mann-Whitney U test. In female subjects, DPB1*03:01 was significantly associated with HbA1c (p = 0.0000665), and DRB1*14:03 was associated with total cholesterol concentration (p = 0.0015). In male subjects, C*14:02 demonstrated significant associations with fasting plasma glucose with p values of 0.0041. By contrast, Fisher's exact test indicated that female DRB1*14:03 was associated with a high concentration of total cholesterol (p = 000323, odds ratio [OR] = 4.32, 95% confidence interval [95% CI] = 1.83-10.36), whereas female DPB1*02:01 had a protective effect against a high concentration of LDL cholesterol (p =0.0043, OR = 0.41, 95% CI = 0.19-0.79). These associations have a statistical power of more than 0.8 and still retain significance after Bonferroni correction.

A genome-wide scan in affected sibling pairs with idiopathic recurrent miscarriage suggests genetic linkage

Previously, siblings of patients with idiopathic recurrent miscarriage (IRM) have been shown to have a higher risk of miscarriage. This study comprises two parts: (i) an epidemiological part, in which we introduce data on the frequency of miscarriage among 268 siblings of 244 patients with IRM and (ii) a genetic part presenting data from a genome-wide linkage study of 38 affected sibling pairs with IRM. All IRM patients (probands) had experienced three or more miscarriages and affected siblings two or more miscarriages. The sibling pairs were genotyped by the Affymetrix GeneChip 50K XbaI platform and non-parametric linkage analysis was performed via the software package Merlin. We find that siblings of IRM patients exhibit a higher frequency of miscarriage than population controls regardless of age at the time of pregnancy. We identify chromosomal regions with LOD scores between 2.5 and 3.0 in subgroups of affected sibling pairs. Maximum LOD scores were identified in four occurrences: for rs10514716 (3p14.2) when analyzing sister-pairs only; for rs10511668 (9p22.1) and rs341048 (11q13.4) when only analyzing families where the probands have had four or more miscarriages; and for rs10485275 (6q16.3) when analyzing one sibling pair from each family only. We identify no founder mutations. Concluding, our results imply that IRM patients and their siblings share factors which increase the risk of miscarriage. In this first genome-wide linkage study of affected sibling pairs with IRM, we identify regions on chromosomes 3, 6, 9 and 11 which warrant further investigation in order to elucidate their putative roles in the genesis of IRM.