Human Leukocyte Antigen (HLA) Typing Study Identifies Maternal DQ2 Susceptibility Alleles among Infertile Women: Potential Associations with Autoimmunity and Micronutrients

No evidence of genetic causation between iron and infertility: a Mendelian randomization study

Background

Observational studies have explored the impact of iron homeostasis on infertility; however, establishing definitive causal relationships remains challenging. This study utilized a two-sample Mendelian randomization approach to investigate the potential causal relationship between iron status and infertility.

Materials and methods

Four indicators of iron status-serum iron, ferritin, transferrin saturation, and total iron binding capacity, were considered as exposure factors. Infertility was the outcome variable for both men and women. Robust causality was assessed using the primary inverse-variance-weighted method, complemented by three supplementary Mendelian randomization approaches. Sensitivity analyses were performed to enhance the precision and reliability of the results.

Results

No statistically significant associations were identified between the four indicators of iron status and infertility. These results remained consistent across multiple Mendelian randomization methodologies.

Conclusion

In conclusion, there is no evidence of a genetic causal relationship between iron status and infertility. Nevertheless, this does not preclude the possibility of a connection between iron status and infertility at different mechanistic levels.

Recent Advances in Folates and Autoantibodies against Folate Receptors in Early Pregnancy and Miscarriage

Though firstly identified in cerebral folate deficiency, autoantibodies against folate receptors (FRAbs) have been implicated in pregnancy complications such as miscarriage; however, the underlying mechanism needs to be further elaborated. FRAbs can be produced via sensitization mediated by folate-binding protein as well as gene mutation, aberrant modulation, or degradation of folate receptors (FRs). FRAbs may interfere with folate internalization and metabolism through blocking or binding with FRs. Interestingly, different types of FRs are expressed on trophoblast cells, decidual epithelium or stroma, and macrophages at the maternal-fetal interface, implying FRAbs may be involved in the critical events necessary for a successful pregnancy. Thus, we propose that FRAbs may disturb pregnancy establishment and maintenance by modulating trophoblastic biofunctions, placental development, decidualization, and decidua homeostasis as well as the functions of FOLR2+ macrophages. In light of these findings, FRAbs may be a critical factor in pathological pregnancy, and deserve careful consideration in therapies involving folic acid supplementation for pregnancy complications.

Human Leukocyte Antigen Alleles Compatibility and Immunophenotypic Profile Associations in Infertile Couples

Introduction: The maternal immune system has a major role in the successful embryo implantation and maintenance of the pregnancy. This study aimed to investigate the maternal immunophenotyping profile (percentage of Natural Killer [NK] cells and the CD4/CD8 [cluster designation] ratio in peripheral blood lymphocytes) and the HLA (Human Leukocyte Antigen)-DQA1 alleles sharing in infertile couples.

Methods: This cross-sectional study included 78 women who had experienced at least two spontaneous miscarriages and 110 women with a history of recurrent implantation failures after in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) and embryo transfer (ET) (IVF-ET failures). The NK cell percentage and the CD4/CD8 ratio were determined by flow cytometry. Genotyping of the HLA-DQA1 alleles was carried out for all women and their partners, and couple HLA-DQA1 compatibility was expressed as the percentage of common HLA-DQA1 alleles (totaling 35 alleles) shared between spouses to the sum of the unique alleles observed.

Results: In women with recurrent miscarriages, high values (%) of the NK population with a median (interquartile range [IQR]) of 10.3% (7.7% to 12.5%) and CD4/CD8 ratio (1.7) (1.5 to 2.1) were found. In women with IVF-ET failures, the (%) NK population (10.5%) (8.6% to 12.5%) and CD4/CD8 ratio (1.8) (1.5 to 2.1) were similarly increased (p=0.390, and p=0.490, respectively). The proportion of women with >10% NK cells was 53.8% and 58.2% in women with miscarriages and IVF-ET failures, respectively (p=0.554). The prevalence of HLA-DQA1*5 allele carriage was elevated in women with miscarriages as well as those with IVF-ET failures (52.6% and 61.8%, respectively; p=0.206). The proportion of couples with high (>50%) HLA-DQA1 sharing was 65.4% in the group with miscarriages and 73.6% in the group with IVF-ET failures, respectively (p=0.222). The CD4/CD8 ratio was statistically significantly positively correlated with the (%) NK population in women with IVF-ET failures (rho = 0.297, p=0.002) and with the (%) HLA-DQA1 sharing in the group with miscarriages (rho = 0.266, p=0.019). The couples in which both spouses were carriers of the HLA-DQA1*5 allele had an increased probability of high (>50%) HLA-DQA1 compatibility compared with the couples in which neither of the spouses carried the allele in the miscarriage group (OR = 24.3, 95% CI: 3.0 to 198.9, p<0.001), and the IVF-ET failure group (OR = 10.5, 95% CI: 2.2 to 49.8, p<0.001).

Conclusion: The peripheral NK (%) population and CD4/CD8 ratio, as well as the prevalence of the HLA-DQA1*5 allele, were elevated in women with recurrent miscarriages and IVF-ET failures. Furthermore, these couples with negative reproductive outcomes had a high percentage of HLA-DQA1 allele similarity. The presence of the HLA-DQA1*5 allele in spouses was strongly associated with overall couple HLA-DQA1 compatibility, implying that it could be used as a surrogate marker for assessing overall immunological compatibility in infertile couples.

Association between serum vitamin D level during pregnancy and recurrent spontaneous abortion: a systematic review and meta-analysis

PROBLEM

Previous studies had shown that there might be an association between serum vitamin D concentrations and the occurrence of recurrent spontaneous abortion (RSA). However, the conclusions remained controversial. The objective of this study was to systematically review the evidence for an epidemiological association between vitamin D and RSA.

METHOD OF STUDY

The literature search was performed in the following databases: PubMed, Web of Science, Embase and Chinese databases. The I² statistic was used to evaluate heterogeneity. Effect sizes were calculated using fixed or random effects models, including standardized mean difference (SMD), odds ratios (OR) and their 95% confidence intervals (95%CI). Then we performed subgroup analysis, sensitivity analysis and publication bias analysis.

RESULTS

Fourteen studies from five countries were included. Based on the results, patients with RSA had lower vitamin D levels than controls (SMD = -1.48, 95%CI: -2.01, -0.94, P<0.001), and pregnant women with vitamin D deficiency (VDD) had a higher risk of developing RSA (OR = 4.02, 95%CI: 2.23, 7.25, P<0.001). There was remarkable heterogeneity between studies (I² _SMD = 97.3%, P<0.001; I² _OR = 82.2%, P<0.001). The results of the subgroup analysis suggested that heterogeneity may be caused by the assay method, age and region. Sensitivity analysis showed the analysis results were robust.

CONCLUSION

Patients with RSA had lower serum vitamin D levels than normal pregnant women, and pregnant women with VDD might be at higher risk for RSA. This article is protected by copyright. All rights reserved.