Association of genetic variants in the 3'UTR of HLA-G with Recurrent Pregnancy Loss

Opposing impacts of HLA-G haplotypes PROMO-G010104-UTR-3 and PROMO-G010101b/c-UTR-4 on risk of recurrent implantation failure

RESEARCH QUESTION

The human leukocyte antigen (HLA) class Ib molecules HLA-F and HLA-G are implicated in pregnancy success, but how do HLA-G and HLA-F genetic polymorphisms impact recurrent implantation failure (RIF)?

DESIGN

Prospective cohort study at a fertility clinic including a cohort of 84 women experiencing RIF and 35 IVF controls to assess the influence of HLA-G haplotypes and diplotypes and HLA-F single nucleotide polymorphisms (SNP) on RIF.

RESULTS

Over-representation trends for HLA-F SNP genotypes rs1362126, rs2523405 and rs2523393, previously linked with a short time-to-pregnancy, were detected in female control groups compared with RIF patients with no identified pathology linked to infertility. The HLA-G promoter haplotype PROMO-G010101b/c linked with the HLA-G 3'-untranslated region (3'UTR) haplotype UTR-4, which previously has been associated with positive IVF outcome and pregnancy success, was less frequent in the RIF group. For RIF patients carrying the UTR-4 haplotype, the odds ratio (OR) was 0.27 (95% CI 0.12-0.66; P = 0.0044, Pc = 0.026). The HLA-G PROMO-G010104-UTR-3 haplotype was associated with an increased risk of RIF. For RIF patients carrying the UTR-3 haplotype, the OR was 5.86 (95% CI 1.52-26.23; P = 0.0115, Pc = 0.069).

CONCLUSIONS

These results show that specific HLA-G haplotypes based on the promoter region and the 3'UTR are either associated with an increased risk of reduced fertility, including the manifestation of RIF, and lower chance of achieving pregnancy, or with a reduced risk of experiencing RIF.

Ewing sarcoma treatment: a gene therapy approach

Ewing sarcoma (ES) is an aggressive malignant tumor, characterized by non-random chromosomal translocations that produce fusion genes. Fusion genes and fusion protein products are promising targets for gene therapy. Therapeutic approaches and strategies vary based on target molecules (nucleotides, proteins) of interest. We present an extensive literature review of active molecules for gene therapy and methods of gene therapy delivery, both of which are necessary for successful treatment.

Pathophysiological, immunogenetic, anatomopathological profile of thrombophilia in pregnancy

Thrombophilic states have been associated with early and/or late pregnancy loss and possibly other severe obstetrical complications. Pregnancy-induced hypercoagulability, increased stasis, and the consequences of inherited and acquired thrombophilia are just a few of the factors that contribute to the development of thrombosis in pregnancy. In this review, we illustrate the impact that these factors have on the development of thrombophilia during pregnancy. We also explore how thrombophilia impact pregnancy outcomes. Next, we discuss how human leukocyte antigen G plays a part in thrombophilia during pregnancy by regulating cytokine release to prevent trophoblastic cell invasion and maintain local immunotolerance constant. Human leukocyte antigen class E is briefly explored with thrombophilia in pregnancy. Regarding the anatomopathologic aspect, we describe the different histopathological lesions of the placenta found in women with thrombophilia.

Understanding recurrent pregnancy loss: recent advances on its etiology, clinical diagnosis, and management

Recurrent pregnancy loss (RPL) has become an important reproductive health issue worldwide. RPL affects about 2%-3% of reproductive-aged women, and makes serious threats to women's physical and mental health. However, the etiology of approximately 50% of RPL cases remains unknown (unexplained RPL), which poses a big challenge for clinical management of these patients. RPL has been widely regarded as a complex disease where its etiology has been attributed to numerous factors. Heretofore, various risk factors for RPL have been identified, such as maternal ages, genetic factors, anatomical structural abnormalities, endocrine dysfunction, prethrombotic state, immunological factors, and infection. More importantly, development and applications of next generation sequencing technology have significantly expanded opportunities to discover chromosomal aberrations and single gene variants responsible for RPL, which provides new insight into its pathogenic mechanisms. Furthermore, based upon patients' diagnostic evaluation and etiologic diagnosis, specific therapeutic recommendations have been established. This review will highlight current understanding and recent advances on RPL, with a special focus on the immunological and genetic etiologies, clinical diagnosis and therapeutic management.

Association of parental HLA-G polymorphisms with soluble HLA-G expressions and their roles on recurrent implantation failure: A systematic review and meta-analysis

Introduction

HLA-G plays a central role in immune tolerance at the maternal-fetal interface. The HLA-G gene is characterized by low allelic polymorphism and restricted tissue expression compared with classical HLA genes. HLA-G polymorphism is associated with HLA-G expression and linked to pregnancy complications. However, the association of parental HLA-G polymorphisms with soluble HLA-G (sHLA-G) expression and their roles in recurrent implantation failure (RIF) is unclear. The study aims to systematically review the association of HLA-G polymorphisms with RIF, the association of sHLA-G expression with RIF, and the association of HLA-G polymorphisms with sHLA-G expressions in patients attending in-vitro fertilization (IVF) treatment.

Methods

Studies that evaluated the association of HLA-G polymorphisms with RIF, the association between sHLA-G expression with RIF, and the association between HLA-G polymorphisms with sHLA-G expressions in patients attending IVF treatment were included. Meta-analysis was performed by random-effect models. Sensitivity analysis was performed by excluding one study each time. Subgroup analysis was performed based on ethnicity.

Results

HLA-G 14bp ins variant is associated with a lower expression of sHLA-G in seminal or blood plasma of couples attending IVF treatment. The maternal HLA-G*010101 and paternal HLA-G*010102 alleles are associated with RIF risk compared to other alleles. However, single maternal HLA-G 14bp ins/del polymorphism, HLA-G -725 C>G/T polymorphism, or circulating sHLA-G concentration was not significantly associated with RIF in the general population. HLA-G 14bp ins/ins homozygous genotype or ins variant was associated with a higher risk of RIF in the Caucasian population.

Discussion

Specific HLA-G alleles or HLA-G polymorphisms are associated with sHLA-G expression in couples attending IVF treatment. Several HLA-G polymorphisms may be related to RIF, considering different ethnic backgrounds. A combined genetic effect should be considered in future studies to confirm the association of HLA-G polymorphisms and sHLA-G expressions in relation to RIF.

Endometrial HLA-F expression is influenced by genotypes and correlates differently with immune cell infiltration in IVF and recurrent implantation failure patients

STUDY QUESTION

Is human leukocyte antigen (HLA)-F protein expressed in mid-secretory endometrium, and are its expression levels influenced by HLA-F gene polymorphisms and correlated with the abundance of uterine natural killer (uNK) cells and anti-inflammatory M2 macrophages?

SUMMARY ANSWER

HLA-F protein is expressed in mid-secretory endometrium, and levels are correlated with immune cell infiltration, plasma progesterone concentrations and HLA-F single-nucleotide polymorphisms (SNPs), however, women experiencing recurrent implantation failure (RIF) show differences when compared to women attending their first IVF treatment.

WHAT IS KNOWN ALREADY

The immunomodulatory HLA class Ib molecules HLA-G and HLA-F are expressed on the extravillous trophoblast cells and interact with receptors on maternal immune cells. Little is known regarding HLA-F expression in endometrial stroma and HLA-F function; furthermore, HLA-F and HLA-G SNP genotypes and haplotypes have been correlated with differences in time-to-pregnancy.

STUDY DESIGN, SIZE, DURATION

Primary endometrial stromal cell (ESC) cultures (n = 5) were established from endometrial biopsies from women attending IVF treatment at a fertility clinic. Basic HLA-F and HLA-G protein expression by the ESCs were investigated. A prospective controlled cohort study was performed including 85 women with a history of RIF and 36 control women beginning their first fertility treatment and with no history of RIF. In some analyses, the RIF group was divided into unknown cause, male infertility, female infertility, and both female and male infertility. Endometrial biopsies and blood samples were obtained the day equivalent to embryo transfer in a hormone-substituted cycle.

PARTICIPANTS/MATERIALS, SETTING, METHODS

HLA protein expression by ESCs was characterized using flow cytometry and western blot. In the cohort study, the specific immune markers HLA-F and HLA-G, CD56 and CD16 (NK cells), CD163 (M2 macrophages), FOXP3 (regulatory T cells) and CD138 (plasma cells) were analysed by immunohistochemistry and a digital image analysis system in endometrial biopsies. Endometrial receptivity was assessed by an endometrial receptivity array test (the ERA® test). Endometrial biopsies were examined according to modified Noyes' criteria. SNPs at the HLA-F gene and HLA-G haplotypes were determined.

MAIN RESULTS AND THE ROLE OF CHANCE

HLA-F protein is expressed in the endometrium at the time of implantation. Furthermore, the HLA-F protein levels were different according to the womeńs HLA-F SNP genotypes and diplotypes, which have previously been correlated with differences in time-to-pregnancy. Endometrial HLA-F was positively correlated with anti-inflammatory CD163+ M2 macrophage infiltration and CD56+ uNK cell abundance for the entire cohort. However, this was not the case for CD56+ in the female infertility RIF subgroup. HLA-F levels in the endometrial stroma were negatively correlated with plasma progesterone concentrations in the RIF subgroup with known female infertility. Conversely, HLA-F and progesterone were positively correlated in the RIF subgroup with infertility of the male partner and no infertility diagnosis of the woman indicating interconnections between progesterone, HLA-F and immune cell infiltration. Glandular sHLA-G expression was also positively correlated with uNK cell abundance in the RIF subgroup with no female infertility but negatively correlated in the RIF subgroup with a female infertility diagnosis.

LARGE SCALE DATA

Immunohistochemistry analyses of endometrial biopsies and DNA sequencing of HLA genes. Data will be shared upon reasonable request to the corresponding author.

LIMITATIONS, REASONS FOR CAUTION

The control group of women attending their first IVF treatment had an anticipated good prognosis but was not proven fertile. A significant age difference between the RIF group and the IVF group reflects the longer treatment period for women with a history of RIF. The standardization of hormonal endometrial preparation, which allowed consistent timing of endometrial and blood sampling, might be a strength because a more uniform hormonal background may more clearly show an influence on the immune marker profile and HLA class Ib levels in the endometrium by other factors, for example genetic polymorphisms. However, the immune marker profile might be different during a normal cycle.

WIDER IMPLICATIONS OF THE FINDINGS

The findings further highlight the importance of HLA-F and HLA-G at the implantation site and in early pregnancy for pregnancy success. Diagnostic measures and modulation of the complex interactions between HLA class Ib molecules, maternal immune cells and hormonal factors may have potential to improve fertility treatment.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Region Zealand Health Sciences Research Foundation and the Zealand University Hospital through the ReproHealth Research Consortium ZUH. The authors declared there are no conflicts of interest.

The Association of HLA-G Gene Polymorphism and Its Soluble Form With Male Infertility

Successful reproduction depends on many factors. Male factors contribute to infertility in approximately 50% of couples who fail to conceive. Seminal plasma consists of secretions from different accessory glands containing a mixture of various cytokines, chemokines, and growth factors, which together can induce a local immune response that might impact on a male’s as well as a female’s fertility. Human leukocyte antigen (HLA)-G expression has been suggested as an immunomodulatory molecule that influences pregnancy outcome. The HLA-G gene encodes either membrane-bound or/and soluble proteins. The aim of this study was the evaluation of HLA-G polymorphisms and their impact on soluble HLA-G (sHLA-G) production. We tested the HLA-G polymorphism in three positions: rs1632947: c.-964G>A; rs1233334: c.-725G>C/T in the promoter region; rs371194629: c.∗65_∗66insATTTGTTCATGCCT in the 3′ untranslated region. We tested two cohorts of men: 663 who participated in in vitro fertilization (test material was blood or sperm), and 320 fertile controls who possessed children born after natural conception (test material was blood). Since 50% of men visiting assisted reproductive clinics have abnormal semen parameters, we wondered if men with normal sperm parameters differ from those with abnormal parameters in terms of HLA-G polymorphism and secretion of sHLA-G into semen. We found that certain rs1632947-rs1233334-rs371194629 HLA-G haplotypes and diplotypes were associated with male infertility, while others were protective. Normozoospermic men with the A-C-del haplotype and A-C-del/A-C-del diplotype secreted the most sHLA-G into semen (574.1 IU/mL and 1047.0 IU/mL, respectively), while those with the G-C-ins haplotype and G-C-ins/G-C-ins diplotype – the least (80.8 IU/mL and 75.7 IU/mL, respectively). Men with the remaining haplotypes/diplotypes secreted sHLA-G at an intermediate level. However, only in one haplotype, namely G-C-ins, did we observe strong significant differences in the concentration of sHLA-G in the semen of men with teratozoospermia compared to men with normal sperm parameters (p = 0.009). In conclusion, fertile men differ in the profile of HLA-G polymorphism from men participating in IVF. Among all HLA-G haplotypes, the most unfavorable for male fertility is the G-C-ins haplotype, which determines the secretion of the lowest concentration of the soluble HLA-G molecule. This haplotype may reduce sperm parameters.

Extended loci histocompatibility matching in HSCT-Going beyond classical HLA

Unrelated haematopoietic stem cell transplantation (HSCT) has evolved from an experimental protocol to a potentially curative first-line treatment in a variety of haematologic malignancies. The continuous refinement of treatment protocols and supportive care paired with ongoing achievements in the technological field of histocompatibility testing enabled this transformation. Without a doubt, HLA matching is still the foremost criterion for donor selection in unrelated HSCT. However, HSCT-related treatment complications still occur frequently, often resulting in patients suffering severely or even dying as a consequence of such complications. Current literature indicates that other immune system modulating factors may play a role in the setting of HSCT. In this review, we discuss the current clinical evidence of a possible influence of nonclassical HLA antigens HLA-E, HLA-F, and HLA-G as well as the HLA-like molecules MICA and MICB, in HSCT.

Role of the HLA-G immune checkpoint molecule in pregnancy

The non-classical HLA class I molecule HLA-G is expressed in trophoblasts where it contributes to maternal-fetal tolerance. HLA-G has been implicated in the control of trophoblast invasion, uterine vascular remodeling, and maintenance of a local immunosuppressive state. Understanding HLA-G biology at the maternal-fetal interface is therefore a critical issue in reproduction. In this regard, we review here: (i) the effects of HLA-G on decidual leucocytes and stromal cells, (ii) the contribution of trogocytosis in HLA-G expression on decidual cells, (iii) its interaction with the ILT2, ILT4 and KIR2DL4 receptors, (iv) the link between HLA-G polymorphism and pregnancy disorders, and (v) the expression of newly-described HLA-G isoforms at the maternal-fetal interface.

HLA-G Genotype/Expression/Disease Association Studies: Success, Hurdles, and Perspectives

The non-classical HLA-G is a well-known immune-modulatory molecule. In physiological condition, HLA-G surface expression is restricted to the maternal–fetal interface and to immune-privileged adult tissues, whereas soluble forms of HLA-G are detectable in various body fluids. HLA-G can be de novo expressed in pathological conditions including tumors, chronic infections, or after allogeneic transplantation. HLA-G exerts positive effects modulating innate and adaptive immune responses and promoting tolerance, or detrimental effects inducing immune escape mechanisms. HLA-G locus, in contrast to classical HLA class I gene, is highly polymorphic in the non-coding 3′ untranslated region (UTR) and in the 5′ upstream regulatory region (5′ URR). Variability in these regions influences HLA-G expression by modifying mRNA stability or allowing posttranscriptional regulation in the case of 3′ UTR or by sensing the microenvironment and responding to specific stimuli in the case of HLA-G promoter regions (5′ URR). The influence of genetic variations on the expression of HLA-G makes it an attractive biomarker to monitor disease predisposition and progression, or response to therapy. Here, we summarize the current knowledge, efforts, and obstacles to generate a general consensus on the correlation between HLA-G genetic variability, protein expression, and disease predisposition. Moreover, we discuss perspectives for future investigation on HLA-G genotype/expression in association with disease predisposition and progression.

HLA-G Polymorphisms Associated with HIV Infection and Preeclampsia in South Africans of African Ancestry

OBJECTIVES

HLA-G, part of the major histocompatibility complex (MHC), is associated with the risk of developing preeclampsia (PE). In this study, we determined the contribution of specific HLA-G polymorphisms on the risk of developing preeclampsia in HIV-infected and uninfected South Africans of African ancestry.

METHODS

One hundred and ninety-three women of African ancestry were enrolled (74 HIV-uninfected normotensive, 60 HIV-infected normotensive, 34 HIV-uninfected, and 25 HIV-infected preeclamptics). Sanger sequencing of the untranslated region was performed to genotype six SNPs, i.e., 14 bp Ins/Del of rs66554220, rs1710, rs1063320, rs1610696, rs9380142, and rs1707).

RESULTS

For rs66554220, we have the following results: (a) based on pregnancy type-the Ins/Ins and Del/Ins genotype frequency was higher in preeclampsia (PE) compared to normotensive pregnancies (Ins/Ins vs. Del/Ins, P = 0.02∗: OR (95%CI) = 13.44 (0.7222-249.9); Del/Del vs. Del/Ins, P = 0.03∗: OR (95%CI) = 2.95 (1.10-7.920)); (b) based on HIV status-the Ins/Ins showed both genotypic and allelic association with HIV infection. HIV-infected PE has higher Ins/Ins genotypic and allelic frequencies compared to HIV-uninfected PE (Ins/Ins vs. Del/Ins, P = 0.005∗∗: OR (95%CI) = 21.32 (1.71-4.17); Ins, P = 0.005∗∗; OR (95%IC) = 21.32 (1.71-4.17)). For rs1707, we have the following results: (a) based on pregnancy type-there were CT genotypic frequencies in PE, more especially LOPE compared to normotensive pregnancies (TT vs. CT, P = 0.0092∗∗: OR (95%CI) = 5.(1.39 - 25.64)), and no allelic association was noted; (b) based on HIV status-CT was higher in HIV-infected LOPE compared to uninfected LOPE (TT vs. TC, P = 0.0006∗∗∗: OR (95%CI) = 40.00 (2.89 - 555.1)). For rs1710 and rs1063320, no significant differences in the genotype and allele frequencies were noted based on pregnancy type and HIV status. For rs9380142, we have the following results: (a) based on pregnancy type-no significant differences were noted between normotensive compared to PE pregnancies; (b) based on HIV status-AA genotypes occurred more in the HIV-infected PE group (AA vs. GG, P = 0.02∗: OR (95%CI) = 13.97 (0.73 - 269.4)), while A allelic frequency occurred more in HIV-infected PE, especially LOPE compared to uninfected groups (A vs. G, P = 0.0003∗∗∗: OR (95%CI) = 10.72 (2.380 - 48.32); P = 0.02∗: OR (95%CI) = 9.00 (1.07 - 75.74)). For rs1610696, we have the following results: (a) based on pregnancy type-genotypic and allelic frequencies of CC were higher in PE compared to normotensive pregnancies (CC vs. GG, P = 0.0003∗∗∗: OR (95%CI) = 31.87 (1.861 - 545.9); C, P = 0.0001∗∗∗: OR (95%IC) = 21.91 (2.84 - 169.0)); (b) based on HIV status-GG frequencies were higher in the HIV-infected PE more especially LOPE groups (GG vs. GC, P = 0.02∗: OR (95%CI) = 16.87 (0.81 - 352.1); GG vs. CC, P = 0.0001∗∗∗: OR (95%CI) = 159.5 (13.10 - 1942)).

CONCLUSION

Selected HLA-G 14 bp polymorphisms (Ins/Ins) and genotypic and allelic differences in rs9380142, rs1610696, and rs1707 are associated with the pathogenesis of preeclampsia in HIV-infected South African women of African ancestry. More genetic studies evaluating the association between preeclampsia and HIV infection are needed to improve diagnosis and antenatal care.

Association between polymorphic markers human leucocyte antigen-G and tumour necrosis factor alpha and susceptibility to recurrent miscarriages among Bulgarian women

OBJECTIVE

To analyze the role of 14 base pair (bp) insertion (ins)/deletion (del) and tumour necrosis factor alpha (TNF-α) G/A polymorphisms as risk factors for spontaneous miscarriage in patients with two or more unsuccessful pregnancies and a group of control women with at least two normal live births.

MATERIALS AND METHODS

To investigate the role of these mutations, 50 patients with two or more idiopathic recurrent miscarriages and 50 normal fertile women were tested for the presence of human leucocyte antigen-G (HLA-G) 14 bp ins/del and TNF-α -308 G/A variants. The frequencies of the studied polymorphisms were compared between the two groups.

RESULTS

Individuals with a history of miscarriages had a significantly higher prevalence of 14 bp insertion alleles compared with control patients (p=0.04). There was also a two times higher relative risk for miscarriage among carriers of this variant. No statistical difference in allele frequencies of the TNF-α -308 G/A polymorphism was established between controls and study patients (p=0.78).

CONCLUSION

The 14 bp ins HLA-G variant could be associated with a higher risk for unsuccessful pregnancy according to the results from the study. There is no association between the studied TNF-α -308 GA polymorphism and rate of spontaneous abortions.

The HLA-G 14 bp insertion/deletion polymorphism and its association with soluble HLA-G levels in women with recurrent miscarriages

HLA-G, a nonclassical class-Ib gene is mainly expressed on extravillous trophoblasts at the fetal-maternal interface. HLA-G molecule is considered to play an important role in maternal immune suppression during pregnancy. The 14 bp insertion/deletion polymorphism (rs66554220) in exon eight of the HLA-G gene influences HLA-G mRNA stability and isoform splicing patterns. In this study, 202 recurrent miscarriage (RM) women with two or more than two consecutive miscarriages, their 202 partners and 204 fertile control women with at least one live birth and no miscarriages were analyzed for 14 bp insertion/deletion polymorphism. Soluble HLA-G (sHLA-G) levels were also determined and compared between randomly selected 111 RM women and 111 control women using QAYEE-Bio ELISA kits. Student's t test and χ² test were used to depict the statistical differences. The results showed no significant differences for 14 bp allele and genotype frequencies between the study groups. However, our study showed a significant difference (P = .0107) for sHLA-G levels in RM women and control women. Furthermore, a significant difference (P = .0135) for sHLA-G levels in relation to +/-14 bp heterozygous genotype was seen between the two groups. The 14 bp allele sharing between the partners did not show any significant association with the number of miscarriages in RM couples. The association of 14 bp polymorphism and recurrent miscarriages was not significant in our study.

European Patent in Immunoncology: From Immunological Principles of Implantation to Cancer Treatment

The granted European patent EP 2 561 890 describes a procedure for an immunological treatment of cancer. It is based on the principles of the HLA-supported communication of implantation and pregnancy. These principles ensure that the embryo is not rejected by the mother. In pregnancy, the placenta, more specifically the trophoblast, creates an “interface” between the embryo/fetus and the maternal immune system. Trophoblasts do not express the “original” HLA identification of the embryo/fetus (HLA-A to -DQ), but instead show the non-classical HLA groups E, F, and G. During interaction with specific receptors of NK cells (e.g., killer-immunoglobulin-like receptors (KIR)) and lymphocytes (lymphocyte-immunoglobulin-like receptors (LIL-R)), the non-classical HLA groups inhibit these immunocompetent cells outside pregnancy. However, tumors are known to be able to express these non-classical HLA groups and thus make use of an immuno-communication as in pregnancies. If this occurs, the prognosis usually worsens. This patent describes, in a first step, the profiling of the non-classical HLA groups in primary tumor tissue as well as metastases and recurrent tumors. The second step comprises tailored antibody therapies, which is the subject of this patent. In this review, we analyze the underlying mechanisms and describe the currently known differences between HLA-supported communication of implantation and that of tumors.

The association of HLA-G polymorphisms and the synergistic effect of sMICA and sHLA-G with chronic kidney disease and allograft acceptance

The HLA-G and MICA genes are stimulated under inflammatory conditions and code for soluble (sMICA and sHLA-G) or membrane-bound molecules that exhibit immunomodulatory properties. It is still unclear whether they would have a synergistic or antagonistic effect on the immunomodulation of the inflammatory response, such as in chronic kidney disease (CKD), contributing to a better prognosis after the kidney transplantation. In this study, we went from genetic to plasma analysis, first evaluating the polymorphism of MICA, NKG2D and HLA-G in a cohort from Southern Brazil, subdivided in a control group of individuals (n = 75), patients with CKD (n = 94), and kidney-transplant (KT) patients (n = 64). MICA, NKG2D and HLA-G genotyping was performed by polymerase chain reaction with specific oligonucleotide probes, Taqman and Sanger sequencing, respectively. Levels of soluble forms of MICA and HLA-G were measured in plasma with ELISA. Case-control analysis showed that the individuals with haplotype HLA-G*01:01/UTR-4 have a lower susceptibility to develop chronic kidney disease (OR = 0.480; p = 0.032). Concerning the group of kidney-transplant patients, the HLA-G genotypes +3010 GC (rs1710) and +3142 GC (rs1063320) were associated with higher risk for allograft rejection (OR = 5.357; p = 0.013 and OR = 5.357, p = 0.013, respectively). Nevertheless, the genotype +3010 GG (OR = 0.136; p = 0.041) was associated with kidney allograft acceptance, suggesting that it is a protection factor for rejection. In addition, the phenotypic analysis revealed higher levels of sHLA-G (p = 0.003) and sMICA (p < 0.001) in plasma were associated with the development of CKD. For patients who were already under chronic pathological stress and underwent a kidney transplant, a high sMICA (p = 0.001) in pre-transplant proved to favor immunomodulation and allograft acceptance. Even so, the association of genetic factors with differential levels of soluble molecules were not evidenced, we displayed a synergistic effect of sMICA and sHLA-G in response to inflammation. This increase was observed in CKD patients, that when undergo transplantation, had this previous amount of immunoregulatory molecules as a positive factor for the allograft acceptance.

Increased HLA-G Expression in Term Placenta of Women with a History of Recurrent Miscarriage Despite Their Genetic Predisposition to Decreased HLA-G Levels

Human leukocyte antigen (HLA)-G is an immune modulating molecule that is present on fetal extravillous trophoblasts at the fetal-maternal interface. Single nucleotide polymorphisms (SNPs) in the 3 prime untranslated region (3'UTR) of the HLA-G gene can affect the level of HLA-G expression, which may be altered in women with recurrent miscarriages (RM). This case-control study included 23 women with a medical history of three or more consecutive miscarriages who delivered a child after uncomplicated pregnancy, and 46 controls with uncomplicated pregnancy. Genomic DNA was isolated to sequence the 3'UTR of HLA-G. Tissue from term placentas was processed to quantify the HLA-G protein and mRNA levels. The women with a history of RM had a lower frequency of the HLA-G 3'UTR 14-bp del/del genotype as compared to controls (Odds ratio (OR) 0.28; p = 0.039), which has previously been related to higher soluble HLA-G levels. Yet, HLA-G protein (OR 6.67; p = 0.006) and mRNA (OR 6.33; p = 0.010) expression was increased in term placentas of women with a history of RM as compared to controls. In conclusion, during a successful pregnancy, HLA-G expression is elevated in term placentas from women with a history of RM as compared to controls, despite a genetic predisposition that is associated with decreased HLA-G levels. These findings suggest that HLA-G upregulation could be a compensatory mechanism in the occurrence of RM to achieve an ongoing pregnancy.

Genetic Polymorphism of HLA-G 14-bp Insertion/Deletion in Pancreas Transplant Recipients and Its Association With Type 1 Diabetes Mellitus

OBJECTIVES

Human leukocyte antigen-G is an immuno-modulatory factor that affects acute allograft rejection and autoimmune diseases such as type 1 diabetes mellitus. In this study, possible associations between human leukocyte antigen-G 14-bp insertion/deletion polymorphism and acute pancreas rejection were investigated.

MATERIALS AND METHODS

Human leukocyte antigen-G genotyping was assessed in 102 Iranian pancreas transplant recipients (including 41 with acute rejection and 61 with nonacute rejection). Results were compared with 100 individuals in a normal control group.

RESULTS

No significant differences in genotype frequencies of human leukocyte antigen-G 14-bp insertion / deletion were observed in recipients who had acute rejection episodes. On the other hand, the insertion / insertion genotype was a risk factor for susceptibility to type 1 diabetes mellitus (odds ratio = 3.82, 95% confidence interval, 1.37- 11.22; P = .005).

CONCLUSIONS

Our results provided evidence revealing that the human leukocyte antigen-G insertion / insertion genotype might be involved in the pathogenesis of type 1 diabetes mellitus.

Genetic association between HLA-G 14-bp polymorphism and diseases: A systematic review and meta-analysis

BACKGROUND

HLA-G is an immune checkpoint molecule. Since a differential molecule expression has been reported even for healthy individuals, many studies have focused on polymorphisms at HLA-G regulatory regions, particularly the 3' untranslated region (3'UTR). The presence/absence of a 14-bp sequence was the first polymorphism described and it is the most studied in association between HLA-G and disorders.

METHODS

In this study, we performed a systematic review and meta-analysis of all association studies published regarding the HLA-G 14-bp.

RESULTS

We verified association between 14-bp alleles and diseases in the following situations: (1) presence of 14-bp (insertion) conferred susceptibility to preeclampsia (child alleles evaluated) and systemic lupus erythematosus (OR = 1.42; 95%CI = 1.04-1.93; p = 0.026 and OR = 1.13; 95%CI = 1.01-1.27, p = 0.028); (2) 14-bp absence (deletion) was associated with increased risk to breast cancer (OR = 1.23; 95%CI = 1.06-1.43; p = 0.006) and human Cytomegalovirus infection (OR = 2.06; 95%CI = 1.60-2.64; p < 0.0001); and (3) a risk association was observed between the group of reproductive disorders and the 14-bp insertion (OR = 1.12; 95%CI = 1.01-1.24; p = 0.034).

CONCLUSIONS

Considering that others 14-bp associations were inconclusive and that other variation sites observed at HLA-G 3'UTR exhibit a proven role on post-transcriptional regulation of HLA-G expression, the complete 3'UTR segment should be analyzed in terms of disease susceptibility, instead of a single polymorphism.

Human leucocyte antigen-G 14-bp InDel polymorphism and oral squamous cell carcinoma risk in Chinese Han population: A case-control study

Human leucocyte antigen-G (HLA-G) is a nonclassical HLA class I molecule involved in tumour immune escape. The purpose of this study was to investigate the association between the 14-bp insertion/deletion (InDel) polymorphism in the 3' untranslated region (3'-UTR) of HLA-G gene and oral squamous cell carcinoma (OSCC) risk in Chinese Han population (216 cases and 193 healthy controls), and furthermore, to evaluate serum soluble HLA-G (sHLA-G) levels in the OSCC patients. Our results demonstrated that the Ins allele was significantly less frequent in the OSCC patients than that in the healthy controls (odds ratio [OR] = 0.75; 95% confidence interval [CI]: 0.57-0.99; p = 0.040). Distribution of the 14-bp genotypes in the OSCC patients and the healthy controls revealed that the Ins/Ins genotype was associated with decreased OSCC risk in both the codominant model (Ins/Ins versus Del/Del; OR = 0.57; 95% CI = 0.33-0.99; p = 0.044) and the log-additive model (OR = 0.76; 95% CI: 0.58-0.99; p = 0.044). The serum sHLA-G level was significantly higher in the OSCC patients than those in the healthy controls (p < 0.001). Receiver operating characteristic (ROC) curve revealed the valuable diagnostic value of sHLA-G for OSCC detection, with an area under the ROC curve (AUC) of 0.891 (95% CI: 0.856-0.925, p < 0.001). The OSCC patients with Ins/Ins genotype had lower serum sHLA-G levels than those with Ins/Del and Del/Del genotypes (p = 0.015). Furthermore, serum sHLA-G levels were significantly increased with the increasing TNM stages of the OSCC patients (p = 0.017). Our findings revealed that the HLA-G 14-bp InDel polymorphism might be a genetic risk factor for OSCC susceptibility, and the serum sHLA-G may act as a promising biomarker for noninvasive diagnosis of OSCC.

The impact of HLA-G, LILRB1 and LILRB2 gene polymorphisms on susceptibility to and severity of endometriosis

Endometriosis is a disease in which endometriotic tissue occurs outside the uterus. Its pathogenesis is still unknown. The most widespread hypothesis claims that ectopic endometrium appears as a result of retrograde menstruation and its insufficient elimination by immunocytes. Some reports have shown expression of non-classical HLA-G molecules on ectopic endometrium. HLA-G is recognized by KIR2DL4, LILRB1 and LILRB2 receptors on natural killer (NK) and other cells. These receptors are polymorphic, which may affect their activity. In this study we investigated whether HLA-G, KIR2DL4, LILRB1 and LILRB2 polymorphisms may influence susceptibility to endometriosis and disease progression. We used polymerase chain reaction (PCR), PCR-restriction fragment length polymorphism (PCR-RFLP) and allelic discrimination methods with TaqMan SNP Genotyping Assays for typing of 276 patients with endometriosis and 314 healthy fertile women. The HLA-G rs1632947:GG genotype was associated with protection against the disease and its severe stages; HLA-G rs1233334:CT protected against progression; LILRB1 rs41308748:AA and LILRB2 rs383369:AG predisposed to the disease and its progression. No effect of KIR2DL4 polymorphism was observed. These results support the role of polymorphisms of HLA-G and its receptors LILRB1 and LILRB2 in susceptibility to endometriosis and its progression.

Mitochondrial DNA variations are associated with recurrent pregnancy loss

Cases with three or more consecutive spontaneous abortions before the 20th week of gestation are termed as recurrent pregnancy loss (RPL). Problems in implantation of the foetus and any retarded growth of the foetus in the uterus can be correlated to RPL. Possible causes of RPL would include the genetic variations in the regulatory enzymes of the crucial metabolic pathways, clotting factors, hormones and hormone receptors. This defect of the mitochondrial respiratory chain is recognized as a major cause of human disease. We investigated 73 women with RPL and 100 healthy normal controls. By using the direct sequencing method, the amplified products including the mtDNA complex I genes were analyzed. Overall, seven variations in mitochondrial complex I genes were found (T4216C, A5153G, C10142T, C12062T, A12662G, G14179A and T14263C) using direct sequencing technique. The RPL group had significantly higher proportions of the different variants than those observed of the control group. In conclusion, more research is essentially needed to understand the effect and role of the mitochondrial variations in the progress of RPL, which may vary among individuals and different ethnic groups.

Haplotypes of the HLA-G 3' Untranslated Region Respond to Endogenous Factors of HLA-G+ and HLA-G- Cell Lines Differentially

The immune checkpoint HLA-G prevents maternal rejection of the fetus and contributes in cancer invasion and acceptance of allografts. The 5’ and 3’ regulatory regions of the HLA-G gene are polymorphic and balancing selection probably maintains this variability. It is proposed that nucleotide variations may affect the level of HLA-G expression. To investigate this issue we aimed to analyze how haplotypes of the 3’ untranslated region (3’UTR) with highest worldwide frequencies, namely UTR-1, UTR-2, UTR-3, UTR-4, UTR-5, UTR-18 and UTR-7, impact the expression of a luciferase reporter gene in vitro. Experiments performed with the HLA-G positive cell lines JEG-3 (choricarcinoma) and FON (melanoma), and with the HLA-G negative cell lines M8 (melanoma) and U251MG (glioblastoma) showed that the HLA-G 3’UTR polymorphism influences the response to endogenous cellular factors and may vary according to the cell type. UTR-5 and UTR-7 impact the activity of luciferase the most whereas UTR-2, UTR-3, UTR-4, and UTR-18 have intermediate impact, and UTR-1 has the lowest impact. These results corroborate the previous associations between amounts of plasma sHLA-G levels and 3’UTR haplotypes in healthy individuals and reinforce that 3’UTR typing may be a predictor of the genetic predisposition of an individual to express different levels of HLA-G.