Association of reduced maternal sHLA-G5 isoform levels and elevated TNF-α/IL-4 cytokine ratio with Recurrent Pregnancy Loss: A study on South Indian women

Maternal-Fetal Compatibility in Recurrent Pregnancy Loss

Nowadays, recurrent pregnancy loss (RPL) is an undesirable condition suffered by many patients of reproductive age. In this scenario, certain immune cell populations and molecules, involved in maternal-fetal compatibility, have emerged as factors related with the pathogenesis of RPL. Among them, uterine Natural Killer cells (uNKs) appear to be of great relevance. These cells are involved in numerous processes during pregnancy, such as the remodeling of uterine spiral arteries or the control of trophoblast invasion. These functions are regulated by the interactions that these cells establish with the extravillous trophoblast, mainly through their Killer Immunoglobulin-like Receptors (KIRs) and the Human Leukocyte Antigen-C (HLA-C) molecules expressed by the embryo. A high level of polymorphism has been reported for both molecules involved in this interaction, with some of the possible KIR-HLA-C combinations being associated with an increased risk of RPL. However, the complexity of the maternal-fetal interface goes beyond this, as other HLA molecules also appear to be related to this reproductive pathology. In this review, we will discuss the role of uNKs in pregnancy, as well as the polymorphisms and clinical implications of KIR-HLA-C binding. We will also address the involvement of other, different HLA molecules in RPL, and the current advice on the appropriate management of patients with 'immunological mismatch', thus covering the main aspects regarding the involvement of maternal-fetal compatibility in RPL.

Association of human leukocyte antigen-G and -F with recurrent miscarriage and implantation failure: A systematic review and meta-analysis

PROBLEM

The immune system plays an essential role in embryonic implantation and pregnancy, but the molecular details remain controversial. In the past four decades, human leukocyte antigen (HLA)-G and -F have garnered significant attention.

METHOD OF STUDY

MEDLINE, EMBASE, Web of Science, and the Cochrane Trials Registry were searched from their inception dates until December 2022. Studies were selected following PRISMA guidelines. Meta-analyses were used to assess the relationship of soluble HLA-G (sHLA-G) and HLA-G 3'-untranslated region polymorphisms with recurrent miscarriage (RM) and recurrent implantation failure (RIF). Narrative synthesis was conducted to determine the association of RM with other single nucleotide polymorphisms (SNPs) and HLA-G protein in tissues and of RIF with HLA-F. Risk-of-bias was assessed using ROBINS-I. Publication bias was assessed using Egger's and Begg's tests.

RESULTS

Finally, 42 articles were eligible for inclusion in the systematic review (32 in the meta-analysis; 13 in narrative synthesis). We found a significant association between the 14-bp ins/del HLA-G polymorphism and RM risk, but no definitive association with RIF risk. Women with RM had lower blood concentrations of sHLA-G during pregnancy and non-pregnancy than did controls. For women in the RIF group, no significant difference was found.

CONCLUSION

HLA-G protein and gene expression levels may be closely related to RM. The relevance of HLA-G to RIF is still being determined. A narrative synthesis of current studies has shown that HLA-F is likely associated with RIF.

UP-regulated levels of sHLA-G in women with a history of RPL in mid-gestation presumably to achieve ongoing pregnancy

PROBLEM

Recurrent Pregnancy Loss (RPL) is a disorder characterized by two or more pregnancy losses within 20th week of gestation. Globally 1-5% of the couples are affected, 50% of these cases are with unknown etiology. HLA-G, an Immuno-modulatory molecule is a non-classical MHC-1 protein, expressed abundantly on extravillous trophoblastic cells, responsible for spiral artery remodeling, maintaining maternal immune tolerance and fetal growth by adjusting pro and anti-inflammatory milieu during different gestational phases.

METHOD OF STUDY

In the present case-control study CD4+HLA-G+ tTreg cells were enumerated by flow cytometry and estimation of the circulating levels of sHLA-G in the blood samples of 300 mid-gestation pregnant women with (iRPL) and without history of RPL (nRPL) by Enzyme-linked Immunosorbent assay was done. The cases included 92 primary and 58 secondary RPL cases RESULTS: A significant reduction in number of tTregs and elevated levels of circulating sHLA-G in iRPL (.03, 200.9) versus nRPL (.09, 90.32) was observed. Further, the primary cases showed higher circulating sHLA-G and no difference in relation to CD4+HLA-G+ tTregs compared to the secondary cases. Receiver operating curve (ROC) characteristics of sHLA-G (AUC = .8) was superior to CD4+HLA-G+ (AUC = .7) for iRPL patients over nRPL group.

CONCLUSIONS

Our results are suggestive of the over-expression of sHLA-G which may be caused due to its shedding from surface of trophoblast as a compensatory mechanism to save the on-going pregnancy. To realize the present outcome, studies are required on on-going pregnancy follow-up cases with favorable and unfavorable pregnancy outcome.

Efficacy of mesenchymal stromal cells in the treatment of unexplained recurrent spontaneous abortion in mice: An analytical and systematic review of meta-analyses

OBJECTIVES

Unexplained recurrent spontaneous abortion (URSA) remains an intractable reproductive dilemma due to the lack of understanding of the pathogenesis. This study aimed to evaluate the preclinical evidence for the mesenchymal stromal cell (MSC) treatment for URSA.

METHODS

A meticulous literature search was independently performed by two authors across the Cochrane Library, EMBASE, and PubMed databases from inception to April 9, 2023. Each study incorporated was assessed using the Systematic Review Centre for Laboratory Animal Experimentation (SYRCLE) risk of bias tool. The amalgamated standardized mean difference (SMD) accompanied by 95% confidence interval (CI) were deduced through a fixed-effects or random-effects model analysis.

RESULTS

A total of ten studies incorporating 140 mice were subjected to data analysis. The MSC treatment yielded a significant reduction in the abortion rate within the URSA model (OR = 0.23, 95%CI [0.17, 0.3], P<0.00001). Moreover, it elicited a positive modulatory impact on the expression profiles of several inflammatory cytokines in the decidual tissue of URSA murine models, inclusive of IL4 (SMD 1.63, 95% CI [0.39, 2.86], P = 0.01), IL10 (SMD 1.60, 95% CI [0.58, 2.61], P = 0.002), IFN-γ (SMD -1.66, 95%CI [-2.79, -0.52], P = 0.004), and TNF-α (SMD -1.98, 95% CI [-2.93, -1.04], P< 0.0001). Subgroup analyses underscored that the administration mode of intraperitoneal and uterine horn injections, and sources of bone MSCs and adipose-derived MSCs contributed positively to the expression of IL4, IL10, and decreased the expression of IFN-γ in decidual tissue of URSA (P<0.05). Conversely, the tail vein injections subgroup was observed with no statistical significance (P>0.05).

CONCLUSIONS

The findings underscore the considerable potential of MSCs in URSA therapy. Nonetheless, the demand for enhanced transparency in research design and direct comparisons between various MSC sources and administration routes in URSA is paramount to engendering robust evidence that could pave the way for successful clinical translation.

HLA-G and Recurrent Pregnancy Loss

Placentation is an immunological compromise where maternal immune system cells and trophoblastic cells interact to reach an equilibrium condition. Although the cross talk between the two systems is complex and not completely understood, Human Leukocyte Antigen G (HLA-G), expressed on trophoblastic cell surfaces, seems to be one of the main molecules involved in the modulation of both local and systemic maternal immune response. The prevalence of recurrent pregnancy loss (RPL), probably underestimated, is 5% of all women who achieve pregnancy, and about 40-60% percent of RPL cases are unexplained. There is an immunological analogy between allograft rejection and miscarriage, and the purpose of this review is to describe how the HLA-G pathway alterations are involved in disrupting the immunologic balance and in increasing the risk of recurrent pregnancy loss.

Insights into the immunomodulatory regulation of matrix metalloproteinase at the maternal-fetal interface during early pregnancy and pregnancy-related diseases

Trophoblast immune cell interactions are central events in the immune microenvironment at the maternal-fetal interface. Their abnormalities are potential causes of various pregnancy complications, including pre-eclampsia and recurrent spontaneous abortion. Matrix metalloproteinase (MMP) is highly homologous, zinc(II)-containing metalloproteinase involved in altered uterine hemodynamics, closely associated with uterine vascular remodeling. However, the interactions between MMP and the immune microenvironment remain unclear. Here we discuss the key roles and potential interplay of MMP with the immune microenvironment in the embryo implantation process and pregnancy-related diseases, which may contribute to understanding the establishment and maintenance of normal pregnancy and providing new therapeutic strategies. Recent studies have shown that several tissue inhibitors of metalloproteinases (TIMPs) effectively prevent invasive vascular disease by modulating the activity of MMP. We summarize the main findings of these studies and suggest the possibility of TIMPs as emerging biomarkers and potential therapeutic targets for a range of complications induced by abnormalities in the immune microenvironment at the maternal-fetal interface. MMP and TIMPs are promising targets for developing new immunotherapies to treat pregnancy-related diseases caused by immune imbalance.

Tumour necrosis factor inhibitor combined with intravenous immunoglobulin and heparin for treatment of recurrent spontaneous abortion: A two-centre, retrospective, cohort study

WHAT IS KNOWN AND OBJECTIVE

Immune disorder is a key trigger of recurrent spontaneous abortion (RSA); meanwhile, tumour necrosis factor inhibitor (TNFi) is a fundamental therapeutic for multiple immune and inflammatory diseases. Hence, this real-world study aimed to explore the efficacy and safety of TNFi combined with intravenous immunoglobin (IVIG) and heparin therapy in RSA patients.

METHODS

A total of 105 RSA patients who received TNFi+IVIG+Heparin (enoxaparin) (n = 48) or IVIG+Heparin (enoxaparin) (n = 57) were retrospectively included in this two-centre cohort study.

RESULTS AND DISCUSSION

The live birth rate of RSA patients in the TNFi+IVIG+heparin group was 72.9% (95% confidence interval [CI]: 69.6%-85.9%). Besides, the live birth rate in the IVIG+heparin group was 52.6% (95% CI: 42.8%-62.4%). By comparison, the live birth rate was higher in the TNFi+IVIG+heparin group compared to the IVIG+heparin group (p = 0.033). After adjustment by the multivariate logistic regression model using the enter method, TNFi+IVIG+Heparin was also superior to IVIG+Heparin regarding increased live birth rate (odds ratio [OR] = 2.941, p = 0.015). Moreover, TNFi+IVIG+Heparin (vs. IVIG+Heparin) also served as an independent factor for increased live birth rate (OR = 2.423, p = 0.035) by the forward stepwise method in the multivariate analysis. Gestational weeks at delivery (38.3 ± 1.3 vs. 37.7 ± 2.0 weeks, p = 0.155), newborn weight (3123.9 ± 332.1 vs. 3056.6 ± 287.4 g, p = 0.390), Apgar score of newborns (9.8 ± 0.5 vs. 9.7 ± 0.7, p = 0.271) were of no difference between TNFi+IVIG+Heparin and IVIG+Heparin groups. In terms of safety profile, the adverse events were of no difference between the TNFi+IVIG+Heparin and the IVIG+Heparin groups (all p > 0.05), either.

WHAT IS NEW AND CONCLUSION

TNFi combined with IVIG and heparin therapy improves the live birth rate but does not elevate the adverse events compared to IVIG and heparin therapy in RSA patients.

Molecular investigation of association between common IL-6 polymorphism with cytomegalovirus (CMV) infection and recurrent miscarriage in Iranian women

BACKGROUND

Recurrent pregnancy loss (RPL) is described as two or more spontaneous abortions. To date, scientists in various fields of knowledge, such as genetics, endocrinology, anatomy, immunology, and microbiology, have identified some important factors that affect abortions; nonetheless, the precise basic etiology is not determined in up to 50% of RPL cases. Human cytomegalovirus (CMV) infection and host genetic background, like IL-6 SNP polymorphisms, play important roles in RPL etiology.

OBJECTIVE

This study aimed to evaluate the relationships among single nucleotide polymorphisms (-634C/G and -174 G/C) in the IL-6 gene with CMV infection and the risk of RPL for early detection and treatment.

MATERIALS AND METHODS

This case-control study was carried on 80 Iranian females with RPL and 80 healthy females as controls. DNA was extracted from samples and CMV and IL6 SNPs were detected using Tetra ARMS-PCR. Statistics were analyzed by Epi Info TM and SPSS software by X2 test for the roles of CMV detection and two polymorphisms in RPL.

RESULTS

The results indicated an increased rate of CMV infection in the RPL group (44%) compared to the control group (25.45%). The prevalence of IL-6-634C/G genotype among RPL patients with CMV infection was 80%, while the frequency of this genotype among RPL patients without CMV infection was 50%. Furthermore, no substantial relation was found between IL-6-174 G/C genotypes and RPL (p = 0.005).

CONCLUSION

This study not only indicated a significant role for CMV in RPL, but also showed an association between CMV and allele G in IL6-634 among Iranian women. In addition, the findings suggested the use of CMV and IL-6-634 GG genotypes as diagnostic and prognostic biomarkers for RPL in the Iranian population.