Detection of soluble HLA-G molecules in plasma and amniotic fluid

HLA-G Expression/Secretion and T-Cell Cytotoxicity in Missed Abortion in Comparison to Normal Pregnancy

The main role of HLA-G is to protect the semi-allogeneic embryo from immune rejection by proper interaction with its cognate receptors on the maternal immune cells. Spontaneous abortion is the most common adverse pregnancy outcome, with an incidence rate between 10% and 15%, with immunologic dysregulation being thought to play a role in some of the cases. In this study, we aimed to detect the membrane and soluble HLA-G molecule at the maternal-fetal interface (MFI) and in the serum of women experiencing missed abortion (asymptomatic early pregnancy loss) in comparison to the women experiencing normal early pregnancy. In addition, the proportion of T cells and their cytotoxic profile was evaluated. We observed no difference in the spatial expression of HLA-G at the MFI and in its serum levels between the women with missed abortions and those with normal early pregnancy. In addition, comparable numbers of peripheral blood and decidual total T and γδT cells were found. In addition, as novel data we showed that missed abortion is not associated with altered extravilous invasion into uterine blood vessels and increased cytotoxicity of γδT cells. A strong signal for HLA-G on non-migrating extravilous trophoblast in the full-term normal placental bed was detected. In conclusion, HLA-G production at the MFI or in the blood of the women could not be used as a marker for normal pregnancy or missed abortions.

Predictive Capabilities of Human Leukocyte Antigen-G and Galectin-13 Levels in the Amniotic Fluid and Maternal Blood for the Pregnancy Outcome

Background and Objectives: Increasing evidence points to the significant role of the angiogenic factor levels in screening for pregnancy outcome. To examine the potential relationship between concentrations of placental protein 13 (PP13) and soluble human leukocyte antigen-G (sHLA-G) in maternal serum and amniotic fluid at 16-23 weeks of gestation and the sonographic features of pregnancy as well as pregnancy outcome. Materials and Methods: PP13 and sHLA-G in serum and amniotic fluid, fetal biometrical data, and placental volume and perfusion indices were determined in 71 euploid, singleton pregnancies. Results: The serum sHLA-G level exhibits a negative correlation with the serum PP13 level (r = -0.186, p < 0.001) and a positive correlation with the sHLA-G level in amniotic fluid (r = 0.662, p < 0.001). A significant correlation was found between serum sHLA-G level and placental volume (r = 0.142, p < 0.05) and between amniotic sHLA-G level and placental perfusion (r = -0.450, p < 0.001). A low amniotic PP13 level significantly predicted the birth weight (r = -0.102, p < 0.05), the duration of pregnancy (r = -0.155, p < 0.05), and the fetal abdominal circumference (r = -0.098, p < 0.05). Conclusions: PP13 assayed in amniotic fluid might be a potential marker of fetal growth, and sHLA-G can be an adjunct modality reflecting placental sonographic parameters.

Soluble HLA-G blood levels are not increased during ongoing pregnancy in women with a history of recurrent pregnancy loss

Recurrent pregnancy loss (RPL) affects 1-2 % of couples who are trying to conceive. At some point, some couples do maintain a healthy pregnancy to term, but the underlying mechanism of RPL remains elusive. Human leukocyte antigen (HLA)-G is an immune modulatory molecule. Our group previously showed increased HLA-G levels in the decidua of term pregnancies after RPL, while other studies showed reduced soluble HLA-G (sHLA-G) blood levels in women with RPL. This led us to investigate sHLA-G levels in blood of women with RPL who had either a subsequent pregnancy loss (RPL-pregnancy loss) or a healthy term pregnancy (RPL-live birth), and compare these to healthy control pregnancies and non-pregnant controls. Soluble HLA-G concentrations were quantified by ELISA. Women with healthy term pregnancy had increased sHLA-G levels compared to non-pregnant controls. In contrast, RPL-live birth women at term did not have increased blood sHLA-G levels. Soluble HLA-G levels remained stable between first and third trimester. Interestingly, when comparing first trimester samples of RPL-live birth to RPL-pregnancy loss, sHLA-G levels also did not significantly differ. High sHLA-G levels in blood seem not to be crucial for an ongoing healthy pregnancy after RPL. However, since it was previously shown that women with RPL-live birth have increased HLA-G levels in term decidua compared to control pregnancies, the current data suggest that local and systemic immune regulation are not necessarily in concert. Further study of the contribution of fetus-derived HLA-G and HLA-G of maternal origin may provide more insight in the pathophysiology of RPL.

Investigating Serum sHLA-G Cooperation With MRI Activity and Disease-Modifying Treatment Outcome in Relapsing-Remitting Multiple Sclerosis

Relapsing-remitting multiple sclerosis (RRMS) is a demyelinating disease in which pathogenesis T cells have a major role. Despite the unknown etiology, several risk factors have been described, including a strong association with human leukocyte antigen (HLA) genes. Recent findings showed that HLA class I-G (HLA-G) may be tolerogenic in MS, but further insights are required. To deepen the HLA-G role in MS inflammation, we measured soluble HLA-G (sHLA-G) and cytokines serum level in 27 patients with RRMS at baseline and after 12 and 24 months of natalizumab (NTZ) treatment. Patients were divided into high (sHLA-G&gt;20 ng/ml), medium (sHLA-G between 10 and 20 ng/ml), and low (sHLA-G &lt;10 ng/ml) producers. Results showed a heterogeneous distribution of genotypes among producers, with no significant differences between groups. A significant decrease of sHLA-G was found after 24 months of NTZ in low producers carrying the +3142 C/G genotype. Finally, 83.3% of high and 100% of medium producers were MRI-activity free after 24 months of treatment, compared to 63.5% of low producers. Of note, we did not find any correlation of sHLA-G with peripheral cell counts or cytokines level. These findings suggest that serum sHLA-G level may partly depend on genotype rather than peripheral inflammation, and that may have impacted on MRI activity of patients over treatment.

Immunity at maternal-fetal interface: KIR/HLA (Allo)recognition

Both KIR and HLA are the most variable gene families in the human genome. The recognition of the semi-allogeneic embryo-derived trophoblasts by maternal decidual NK (dNK) cells is essential for the establishment of the functional placenta. This recognition is based on the KIR-HLA interactions and trophoblast expresses a specific HLA profile that constitutes classical polymorphic HLA-C and non-classical oligomorphic HLA-E, HLA-F, and HLA-G molecules. This review highlights some features of the KIR/HLA-C (allo)recognition by decidual NK (dNK) cells as a main immune cell population specifically enriched at maternal-fetal interface during human early pregnancy. How KIR/HLA-C axis operates in pregnancy disorders and in the context of transplacental infections is discussed as well. We summarized old and new data on dNK-cell functional plasticity, their selective expression of KIR and fetal maternal/paternal HLA-C haplotypes present. Results showed that KIR-HLA-C combinations and the corresponding axis operate differently in each pregnancy, determined by the variability of both maternal KIR haplotypes and fetus' maternal/paternal HLA-C allotype combinations. Moreover, the maturation of NK cells strongly depends on if or not HLA allotypes for certain KIR are present. We suggest that the unique KIR/HLA combinations reached in each pregnancy (normal and pathological) should be studied according to well-defined guidelines and unified methodologies to have comparable results ease to interpret and use in clinics.

Prognostic significance of high circulating sHLA-G in ovarian carcinoma

HLA-G is a non-classical major histocompatibility complex class Ib molecule. Its expression has been described in various cancer types, including ovarian cancer. HLA-G molecule has been implicated in immune escape and in progression of ovarian tumor cells. Our goal was to assess if total soluble (s)HLA-G molecules or HLA-G5 and sHLA-G1 isoforms could be considered as circulating ovarian tumor biomarkers, we measured the concentration of these molecules in ovarian carcinoma patients stratified according with their clinicopathological parameters. sHLA-G, sHLA-G1 and HLA-G5 concentrations were dosed in plasma samples by sandwich-ELISA. The sHLA-G dimerization was analyzed after immunoprecipitation and SDS-PAGE migration. Total sHLA-G and sHLA-G1 levels were significantly represented in plasma of ovarian carcinoma patients compared to healthy controls. sHLA-G1 isoform concentration was highly represented in ovarian carcinoma compared to HLA-G5 isoforms. Additionally, high sHLA-G molecules have been found in aged patients, as well as in patients with advanced stages, and those with metastatic lymph nodes and those with distant metastasis. Elsewhere, sHLA-G monomers were highly represented in ovarian carcinoma patients compared to controls. sHLA-G plasmatic protein was highly represented in ovarian carcinoma. In effect, HLA-G might be considered as a new checkpoint molecule that could be used to assess progression and recurrence of the disease, thus placing it as a potential biomarker for advanced and complicated ovarian carcinoma.

The Potential of Soluble Human Leukocyte Antigen Molecules for Early Cancer Detection and Therapeutic Vaccine Design

Human leukocyte antigen (HLA) molecules are essential for anti-tumor immunity, as they display tumor-derived peptides to drive tumor eradication by cytotoxic T lymphocytes. HLA molecules are primarily studied as peptide-loaded complexes on cell membranes (mHLA) and much less attention is given to their secretion as soluble HLA–peptide complexes (sHLA) into bodily fluids. Yet sHLA levels are altered in various pathologies including cancer, and are thus of high interest as biomarkers. Disconcordance in results across studies, however, hampers interpretation and generalization of the relationship between sHLA levels and cancer presence, thereby impairing its use as a biomarker. Furthermore, the question remains to what extent sHLA complexes exert immunomodulatory effects and whether shifts in sHLA levels contribute to disease or are only a consequence of disease. sHLA complexes can also bear tumor-derived peptides and recent advancements in mass spectrometry now permit closer sHLA peptide cargo analysis. sHLA peptide cargo may represent a “liquid biopsy” that could facilitate the use of sHLA for cancer diagnosis and target identification for therapeutic vaccination. This review aims to outline the contradictory and unexplored aspects of sHLA and to provide direction on how the full potential of sHLA as a quantitative and qualitative biomarker can be exploited.

Roles of HLA-G in the Maternal-Fetal Immune Microenvironment

During pregnancy, the maternal uterus and fetus form a special microenvironment at the maternal-fetal interface to support fetal development. Extravillous trophoblasts (EVTs), differentiated from the fetus, invade into the decidua and interact with maternal cells. Human leukocyte antigen (HLA)-G is a non-classical MHC-I molecule that is expressed abundantly and specifically on EVTs in physiological conditions. Soluble HLA-G (sHLA-G) is also found in maternal blood, amniotic fluid, and cord blood. The abnormal expression and polymorphisms of HLA-G are related to adverse pregnancy outcomes such as preeclampsia (PE) and recurrent spontaneous abortion (RSA). Here we summarize current findings about three main roles of HLA-G during pregnancy, namely its promotion of spiral artery remodeling, immune tolerance, and fetal growth, all resulting from its interaction with immune cells. These findings are not only of great significance for the treatment of pregnancy-related diseases but also provide clues to tumor immunology research since HLA-G functions as a checkpoint in tumors.

Artificial Antigen Presentosomes for T Cell Activation

CD8⁺ T cells constitute an essential component of the adaptive immune system. They are activated through T cell receptor (TCR) recognizing antigenic peptides presented by MHC class I molecules expressed by antigen-presenting cells, such as dendritic cells (DCs). Harvesting a large number of activated, antigen-specific human CD8⁺ T cells for functional studies has been a laborious task for immunologists, largely because of the variables associated with DC preparations. Here we describe a robust, cost-effective DC-free antigen-presenting system capable of generating a large number of antigen-specific CD8⁺ T cells in vitro.

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.

Effects of recombinant thrombomodulin therapy and soluble human leukocyte antigen-G levels during hematopoietic stem cell transplantation

BACKGROUND

Conditioning chemotherapies for hematopoietic stem cell transplantation (HSCT), especially those that include total body irradiation, can result in serious complications such as graft-versus-host disease (GVHD). Human leukocyte antigen G (HLA-G) is a non-classical class I molecule with multiple immunoregulatory functions.

METHODS

We measured interleukin (IL)-10, transforming growth factor (TGF)β₁, and soluble HLA-G (sHLA-G) in HSCT patients and examined the relationship between sHLA-G levels and acute GVHD (aGVHD). Additionally, we investigated the effect of recombinant soluble thrombomodulin (rTM) therapy on sHLA-G levels. Our study cohort included 135 patients who underwent allogeneic HSCT at several institutions in Japan.

RESULTS

Serum levels of IL-10 and TGFβ₁ exhibited no significant changes following HSCT. In contrast, levels of sHLA-G were significantly increased at days 21 and 28 post-HSCT. For patients with confirmed complications, the frequency of aGVHD was significantly lower in those with a > 2.8-fold increase in sHLA-G levels at day 28 relative to day 7 post-HSCT. sHLA-G levels in patients who received rTM therapy were significantly higher at days 21 and 28 post-HSCT compared with those in patients who did not receive rTM therapy.

CONCLUSION

These data suggest that HLA-G/sHLA-G participate in prevention of GVHD, and that rTM may prevent aGVHD following HSCT by promoting elevation of sHLA-G.

Recipient HLA-G +3142 CC Genotype and Concentrations of Soluble HLA-G Impact on Occurrence of CMV Infection after Living-Donor Kidney Transplantation

The expression modulation of the immunosuppressive non-classical Human leukocyte antigen-G (HLA-G) molecule and its soluble isoforms is an immune evasion strategy being deployed by cytomegalovirus (CMV). The +3142 C>G single nucleotide polymorphism (SNP) located within the 3′ untranslated region (3′UTR) is of crucial importance for the regulation of HLA-G expression. Therefore, we analyzed the influence of the +3142 C>G HLA-G SNP on the occurrence of CMV infection in a cohort of 178 living-donor kidney recipients and their 178 corresponding donors. In addition, soluble HLA-G (sHLA-G) levels were quantified before and after transplantation. The presence of the HLA-G +3142 CC genotype in recipients, but not donors of our cohort as along with elevated sHLA-G levels (≥6.1 ng/mL) were associated with higher susceptibility to CMV infection after transplantation. Our results provided evidence that (i) HLA-G is implicated in the establishment of CMV after living-donor kidney transplantation and (ii) recipient HLA-G +3142 CC genotype and sHLA-G concentration levels could represent important predictive risk markers for CMV infection.

HLA class Ib in pregnancy and pregnancy-related disorders

The HLA class Ib genes, HLA-E, HLA-F, and HLA-G, were discovered long after the classical HLA class Ia genes. The elucidation of their functions had a modest beginning. However, their basic functions and involvement in pathophysiology and a range of diseases are now emerging. Although results from a range of studies support the functional roles for the HLA class Ib molecules in adult life, especially HLA-G and HLA-F have most intensively been, and were also primarily, studied in relation to reproduction and pregnancy. The expression of HLA class Ib proteins at the feto-maternal interface in the placenta seems to be important for the maternal acceptance of the semi-allogenic fetus. In contrast to the functions of HLA class Ia, HLA-G possesses immune-modulatory and tolerogenic functions. Here, we review an accumulating amount of data describing the functions of HLA class Ib molecules in relation to fertility, reproduction, and pregnancy, and a possible role for these molecules in certain pregnancy complications, such as implantation failure, recurrent spontaneous abortions, and pre-eclampsia. The results from different kinds of studies point toward a role for HLA class Ib, especially HLA-G, throughout the reproductive cycle from conception to the birth weight of the child.

HLA-E allelic genotype correlates with HLA-E plasma levels and predicts early progression in chronic lymphocytic leukemia

BACKGROUND

Human leukocyte antigen-E (HLA-E) is a nonclassical major histocompatibility complex class I molecule that recently came into sharper focus as a putative marker of advanced tumor stages and disease progression. In solid tumors, increased HLA-E expression as well as elevated soluble HLA-E (sHLA-E) plasma levels are associated with a poor prognosis; however, a role for HLA-E in hematologic malignancies remains to be established.

METHODS

The authors analyzed HLA-E alleles and sHLA-E levels in a cohort of 110 individuals with chronic lymphocytic leukemia (CLL).

RESULTS

In patients with CLL, levels of sHLA-E increased with advanced disease stage (P = .01) and decreased after therapy (P = .01). Longitudinal follow-up revealed that both HLA-E*01:03 alleles and high levels of sHLA-E were significantly associated with a requirement for early treatment in patients with CLL (P = .027 and P = .023, respectively). In vitro, sHLA-E inhibited degranulation and interferon-γ production by natural killer (NK) cells when cocultivated with tumor cells. Moreover, sHLA-E loaded onto microspheres induced transforming growth factor-β release by NK cells. Multivariate analysis revealed that the presence of at least 1 HLA-E*01:03 allele was an independent predictor of a requirement for early treatment.

CONCLUSIONS

HLA-E alleles and sHLA-E levels may represent novel biomarkers for early disease progression in patients with CLL. Cancer 2017;123:814-23. © 2016 American Cancer Society.

Shift in Expression of HLA-G mRNA Spliceforms in Pregnancies Complicated by Preeclampsia

OBJECTIVE

Despite emerging data on the in vitro modulatory effects of trophoblast-associated human leukocyte antigen G (HLA-G), its in vivo function needs to be determined. Immunohistochemical studies show a decrease in protein expression of trophoblast HLA-G in preeclampsia. Such a decrease in protein might be the consequence of a shift in HLA-G mRNA spliceform patterns. In an exploratory pilot study we determined trophoblast HLA-G mRNA spliceform distribution in preeclampsia.

METHODS

Placental samples were collected immediately after cesarean delivery from pregnancies complicated by preeclampsia or the syndrome hemolysis, elevated liver enzymes, and low platelet count (HELLP) and uncomplicated normotensive pregnancies as controls. HLA-G mRNA spliceform distribution was analyzed using a semiquantitative reverse transcriptase polymerase chain reaction procedure.

RESULTS

Analysis of HLA-G spliceform distribution showed a significant increase in frequency of the G5 form encoding for a soluble HLA-G molecule in preeclampsia. This increase in G5 form was not found in pregnancies complicated by HELLP.

CONCLUSION

The increased frequency in the expression of the HLA-G G5 spliceform may play a role in the pathophysiology of preeclampsia, in particular through a recently suggested effect of this soluble HLA-G molecule on remodeling of the spiral arteries.

The impact of HLA-G 3' UTR variants and sHLA-G on risk and clinical correlates of schizophrenia

The Major Histocompatibility Complex (MHC)/Human Leukocyte Antigen (HLA) is known to influence the pathogenesis of several complex human diseases resulting from gene-environmental interactions. Recently, it has emerged as one of the risk determinants of schizophrenia. The HLA-G protein (a non-classical MHC class I molecule), encoded by the HLA-G gene, is shown to play important role in embryonic development. Importantly, its genetic variations and aberrant expression have been implicated in pregnancy complications like preeclampsia, inflammation, and autoimmunity. Converging evidence implicates these phenomena as risk mechanisms of schizophrenia. However, the functional implications of HLA-G in schizophrenia are yet to be empirically examined. The impact of two functional polymorphisms [14bp Insertion/Deletion (INDEL) and +3187 A>G] and soluble HLA-G (sHLA-G) levels on schizophrenia risk was evaluated. In this exploratory study, the Ins/Ins genotype of 14bp INDEL was found to confer a strong risk for schizophrenia. Further, low levels of sHLA-G were shown to have a significant impact on Clinical Global Impression (CGI) severity in people with schizophrenia.

Soluble monomers, dimers and HLA-G-expressing extracellular vesicles: the three dimensions of structural complexity to use HLA-G as a clinical biomarker

The HLA-G molecule belongs to the family of nonclassical human leukocyte antigen (HLA) class I. At variance to classical HLA class I, HLA-G displays (i) a low number of nucleotide variations within the coding region, (ii) a high structural diversity, (iii) a restricted peptide repertoire, (iv) a limited tissue distribution and (v) strong immune-suppressive properties. The physiological HLA-G surface expression is restricted to the maternal-fetal interface and to immune-privileged adult tissues. Soluble forms of HLA-G (sHLA-G) are detectable in various body fluids. Cellular activation and pathological processes are associated with an aberrant or a neo-expression of HLA-G/sHLA-G. Functionally, HLA-G and its secreted forms are considered to be key players in the induction of short- and long-term tolerance. Thus, its unique expression profile and tolerance-inducing functions render HLA-G/sHLA-G an attractive biomarker to monitor the systemic health/disease status and disease activity/progression for clinical approaches in disease management and treatments. Here, we place emphasis on (i) the current status of the tolerance-inducing functions by HLA-G/sHLA-G, (ii) the current complexity to implement this molecule as a meaningful clinical biomarker regarding the three dimensions of structural diversity (monomers, dimers and HLA-G-expressing extracellular vesicles) with its functional implications, and (iii) novel and future approaches to detect and quantify sHLA-G structures and functions.

The Potential of HLA-G-Bearing Extracellular Vesicles as a Future Element in HLA-G Immune Biology

The HLA-G molecule is a member of the non-classical HLA class I family. Its surface expression is physiologically restricted to the maternal–fetal interface and to immune privileged adult tissues. Despite the restricted tissue expression, HLA-G is detectable in body fluids as secreted soluble molecules. A unique feature of HLA-G is the structural diversity as surface expressed and as secreted molecules. Secreted HLA-G can be found in various body fluids either as free soluble HLA-G or as part of extracellular vesicles (EVs), which are composed of various antigens/ligands/receptors, bioactive lipids, cytokines, growth factors, and genetic information, such as mRNA and microRNA. Functionally, HLA-G and its secreted forms are considered to play a crucial role in the network of immune-regulatory tolerance mechanisms, preferentially interacting with the cognate inhibitory receptors LILRB1 and LILRB2. The HLA-G mediated tolerance is described in processes of pregnancy, inflammation, and cancer. However, almost all functional and clinical implications of HLA-G in vivo and in vitro have been established based on simple single ligand/receptor interactions at the cell surface, whereas HLA-G-bearing EVs were in minor research focus. Indeed, cytotrophoblast cells, mesenchymal stem cells, and cancer cells were recently described to secrete HLA-G-bearing EVs, displaying immunosuppressive effects and modulating the tumor microenvironment. However, numerous functional and clinical open questions persist. Here, we (i) introduce basic aspects of EVs biology, (ii) summarize the functional knowledge, clinical implications and open questions of HLA-G-bearing EVs, and (iii) discuss HLA-G-bearing EVs as a future element in HLA-G biology.

A Rational Strategy for the Use of Amniotic Epithelial Stem Cell Therapy for Liver Diseases

Stem cell-based therapies hold the potential to alleviate the burden of many serious diseases, including those of the liver. Among the different types of stem cells, human placenta-derived stem cells are potentially one of the most clinically applicable stem cells because of their tissue-specific advantages. They are a readily available cell source that can be procured in a noninvasive manner, and there are few ethical concerns regarding their use. Recent studies have demonstrated that the amniotic epithelium contains stem cells that possess four unique and advantageous properties; human amniotic epithelial cells (hAECs) have low immunogenicity, secrete several immune regulatory molecules, possess the potential to differentiate into all three germ layers, and contain abundant lysosomes allowing them to secrete lysosomal enzymes. This perspective article provides an overview of the beneficial properties of hAECs and proposes a rational strategy for translating placental stem cells toward clinical application for various liver diseases.

SIGNIFICANCE

This article provides an overview of the beneficial properties of one type of human placental stem cell and proposes a rational strategy for translating placental stem cells toward clinical application for various liver diseases.

The prognostic impact of soluble and vesicular HLA-G and its relationship to circulating tumor cells in neoadjuvant treated breast cancer patients

The non-classical human leukocyte antigen G (HLA-G) molecule and its soluble forms exert multiple immune suppressive regulatory functions in malignancy and in stem cells contributing to immune escape mechanisms. HLA-G can be secreted as free soluble HLA-G molecules or via extracellular vesicles (EVs). Here we evaluated these soluble HLA-G forms as prognostic marker for prediction of the clinical outcome of neoadjuvant chemotherapy (NACT) treated breast cancer (BC) patients. Plasma samples of BC patients procured before (n=142) and after (n=154) NACT were quantified for total soluble HLA-G (sHLA-Gtot) and HLA-G levels in ExoQuick™ derived EV fractions (sHLA-GEV) by ELISA. The corresponding increments were specified as free sHLA-G (sHLA-Gfree). Total and free sHLA-G were significantly increased in NACT treated BC patients compared to healthy controls (n=16). High sHLA-Gfree levels were exclusively associated to estrogen receptor expression before NACT. Importantly, high sHLA-GEV levels before NACT were related to disease progression and the detection of stem cell-like circulating tumor cells, but high sHLA-Gfree levels indicated an improved clinical outcome. Thus, this study demonstrates for the first time that the different sHLA-G subcomponents represent dissimilar qualitative prognostic impacts on the clinical outcome of NACT treated BC patients, whereas the total sHLA-G levels without separating into subcomponents are not related to clinical outcome.

Serum-soluble HLA-G is associated with specific IgE in patients with allergic rhinitis and asthma

Allergic rhinitis (AR) and allergic asthma (AA) are characterized by T helper (Th)2-polarized immune response. Soluble human leukocyte antigen G (sHLA-G) molecule plays an immunomodulatory activity. Previously, it has been reported that children with AR or AA had higher sHLA-G levels in comparison with normal subjects. Thus, the present study aimed at confirming these data in adults and investigating whether there was a relationship between serum sHLA-G levels and serum IgE levels, in patients with AR or AA. One hundred twenty symptomatic patients, suffering from respiratory symptoms, were enrolled: 45 non-allergic and 75 allergic. A group of 44 healthy subjects was considered as control. Serum sHLA-G levels and serum allergen-specific IgE were determined by immunoenzymatic methods. Allergic patients had significantly higher levels of sHLA-G molecules than non-allergic patients and normal controls (p<0.0001). There was no difference between AR and AA. sHLA-G moderately related with allergen-specific IgE both in AR (r=0.468) and AA patients (r=0.479). The present study confirms that serum sHLA-G molecules are significantly increased in allergic disease and demonstrates that sHLA-G levels are related with allergen-specific IgE levels.

sHLA-G involved in the apoptosis of decidual natural killer cells following Toxoplasma gondii infection

This study aims to assess whether soluble HLA-G (sHLA-G) is involved in apoptosis of decidual natural killer (dNK) cells following Toxoplasma gondii infection. dNK cells or NK-92 cells were infected with T. gondii and co-cultured with trophoblast cells or BeWo cells. Infected co-cultured cells were treated without or with sHLA-G neutralizing antibody. Uninfected co-cultured cells were used as controls. Apoptosis of dNK cells were analyzed by flow cytometry and confocal microscope. Real-time PCR and Western blot were used to determine caspase 3 and caspase 8 expression. sHLA-G in supernatant were measured by enzyme-linked immunosorbent assay (ELISA). In infection groups, sHLA-G was increased, while dNK apoptosis proteins caspase 3 and caspase 8 were up-regulated, but significantly decreased in the presence of sHLA-G neutralizing antibody compared to controls. Under the situation of T. gondii-infected dNK cells co-cultured with trophoblast cells, the up-regulation of sHLA-G could induce dNK cells apoptosis which ultimately may contribute to the abnormal pregnancy outcomes with T. gondii infection.

Maternal HLA-C2 and 14 bp insertion in HLA-G is associated with recurrent implantation failure after in vitro fertilization treatment

The major rate-limiting step in in vitro fertilization (IVF) success appears to be the implantation of the semi-allogeneic embryo into the maternal endometrium. To determine possible risk factors of recurrent failure of embryos to implant, we investigated immunogenetic determinants as level of human leukocyte antigen (HLA) histocompatibility, frequency of killer-cell immunoglobulin-like receptors (KIR) and HLA-C alleles and HLA-G polymorphism. We DNA typed women with recurrent implantation failure (RIF) and their partners for classical HLA Class I, HLA Class II, HLA-G and KIR alleles and compared these results with couples with successful embryo implantation after their first IVF and normal fertile couples. No association was found between RIF and the degree of histocompatibility between partners or sharing of a specific antigen. Also, no significant difference in KIR haplotype or combination of HLA-C group and KIR was observed. We did find a higher frequency of HLA-C2 and a higher frequency of 14 base pair (bp) insertion in HLA-G in women with RIF. Therefore we conclude that the degree of histocompatibility between partners is not a determining factor for the occurrence of RIF. However, presence of the HLA-C2 allotype and the HLA-G allele with a 14 bp insertion is a significant risk factor.

Human Amnion-Derived Stem Cells Have Immunosuppressive Properties on NK Cells and Monocytes

Human amnion-derived cells are considered to be a promising alternative cell source for their potential clinical use in tissue engineering and regenerative medicine because of their proliferation and differentiation ability. The cells can easily be obtained from human amnion, offering a potential source without medical intervention. It has been proven that human amnion-derived cells express immunosuppressive factors CD59 and HLA-G, implying that they may have an immunosuppressive function. To assess the immunosuppressive activity, we investigated the effect of human amnion-derived cells on NK cell and monocyte function. Amnion-derived cells inhibited the cytotoxicity of NK cells to K562 cells. The inhibition depended on the NK/amnion-derived cell ratio. The inhibition of NK cytotoxicity was recovered by continuous culturing without amnion-derived cells. The inhibition of NK cytotoxicity was related to the downregulation of the expression of the activated NK receptors and the production of IFN-γ, as well as the upregulation of the expression of IL-10 and PGE2 in human amnion-derived cells. The addition of antibody to IL-10 or PGE2 inhibitor tended to increase NK cytotoxicity. IL-10 and PGE2 might be involved in the immunosuppressive activity of amniotic cells toward NK cells. Amniotic cells also suppressed the activity of cytokine production in monocytes analyzed with TNF-α and IL-6. These data suggested that amniotic cells have immunosuppressive activity.

HLA-G as a tolerogenic molecule in transplantation and pregnancy

HLA-G is a nonclassical HLA class I molecule. In allogeneic situations such as pregnancy or allograft transplantation, the expression of HLA-G has been related to a better acceptance of the fetus or the allograft. Thus, it seems that HLA-G is crucially involved in mechanisms shaping an allogeneic immune response into tolerance. In this contribution we focus on (i) how HLA-G is involved in transplantation and human reproduction, (ii) how HLA-G is regulated by genetic and microenvironmental factors, and (iii) how HLA-G can offer novel perspectives with respect to therapy.

Some basic aspects of HLA-G biology

Human leukocyte antigen-G (HLA-G) is a low polymorphic nonclassical HLA-I molecule restrictively expressed and with suppressive functions. HLA-G gene products are quite complex, with seven HLA-G isoforms, four membrane bound, and other three soluble isoforms that can suffer different posttranslational modifications or even complex formations. In addition, HLA-G has been described included in exosomes. In this review we will focus on HLA-G biochemistry with special emphasis to the mechanisms that regulate its expression and how the protein modifications affect the quantification in biological fluids.

Soluble human leukocyte antigen-g5 activates extracellular signal-regulated protein kinase signaling and stimulates trophoblast invasion

Soluble human leukocyte antigen-G (HLA-G) is a non-classical class Ib HLA molecule that is secreted from blastocysts. Soluble HLA-G modulates the immune tolerance of the mother and can be used as a prognostic factor for the clinical pregnancy rate. However, the underlying mechanism of how soluble HLA-G5 affects pregnancy remains largely unknown. We hypothesized that soluble HLA-G5 promotes successful implantation and pregnancy by modulating trophoblast invasion through receptor binding and activation of extracellular signal-regulated protein kinase (ERK) signaling pathway. Recombinant HLA-G5 protein over-expressed in E. coli BL21 was purified to near homogeneity. We studied the expression of HLA-G5 and its receptors, the leukocyte immunoglobulin-like receptor subfamily B1 (LILRB1) and killer cell immunoglobulin-like receptor 2DL4 (KIR2DL4), in primary trophoblasts and trophoblastic (JAr and JEG-3) cell lines by florescence-labeled HLA-G5. HLA-G5 was detected in the primary trophoblasts and JEG-3 cells. The LILRB1 and KIR2DL4 receptors were expressed in both primary trophoblasts and trophoblastic cell lines. HLA-G5 stimulated cell invasion (p<0.05) and increased urokinase (uPA) and matrix metalloproteinases (MMPs) transcripts and their activity (p<0.05) in trophoblastic cells. HLA-G5 activated the ERK signaling pathway and induced ERK1/2 phosphorylation in the trophoblastic cell lines. Addition of ERK inhibitors (U0126 and PD98059) nullified the stimulatory effect of HLA-G5 on trophoblastic cell invasion. Taken together, HLA-G5 induced trophoblast invasion by binding to KIR2DL4 and LILRB1, by increasing uPA and MMPs expressions and by activating the ERK signaling pathway.

Amniotic membrane in oral and maxillofacial surgery

PURPOSE

Following its renaissance in ophthalmology during the 1990s, preserved human amniotic membrane (HAM) has become an attractive biomaterial for all surgical disciplines. This article reviews the current and potential use of HAM in oral and maxillofacial surgery, its postulated properties and common preservation techniques.

METHODS

Literature was identified by an electronic search of PubMed in July 2012; this was supplemented from the reference lists of the consulted papers.

RESULTS

HAM has been used in the field of oral and maxillofacial surgery from 1969 onwards because of its immunological preference and its pain-reducing, antimicrobial, mechanical and side-dependent adhesive or anti-adhesive properties. The effects of HAM on dermal and mucosal re-epithelialisation have been highlighted. Typically, HAM is applied after being banked in a glycerol-preserved, DMSO-preserved or freeze-dried and irradiated state. Whereas the use of HAM in flap surgery and in intra-oral and extra-oral lining is reported frequently, novel HAM applications in post-traumatic orbital surgery and temporomandibular joint surgery have been added since 2010. Tissue engineering with HAM is a fast-expanding field with a high variety of future options.

CONCLUSIONS

Preserved HAM is considered to be a safe and sufficient biomaterial in all fields of oral and maxillofacial wound healing. Recently published novel indications for HAM application lack a high level of evidence and need to be studied further.

Promoter sequences confirm the three different evolutionary lineages described for HLA-G

HLA-G alleles follow a different pattern of polymorphism generation that those of the HLA classical I alleles. However, this polymorphism maintenance could have an evolutionary specific pathways based on non coding regions as introns, 14 bp deletion/insertion (exon 8) or promoter regions. For this reason, a systematic sequencing study of HLA-G promoter region was done in 36 individuals with a total of 15 different alleles. From the 12 sequences obtained, 7 were new sequences and not previously described. Results show that the sequences have three different patterns of evolution confirming the results obtained in the rest of the sequence regions (exons, introns and 3'UTR) where three different lineages were established. Only one of these lineages includes the non-human primate promoter sequences suggesting the possibility of this lineage could come directly from non-human primates while the other two could be generated after the speciation. More non-human primates MHC-G promoter sequences must be obtained to confirm this hypothesis. Expression and functional assays could be done considering the differences obtained in the promoter regions involving the HLA-G function (mRNA expression, isoforms).

Immunomodulatory molecules are released from the first trimester and term placenta via exosomes

The semiallogenic fetus is tolerated by the maternal immune system through control of innate and adaptive immune responses. Trophoblast cells secrete nanometer scale membranous particles called exosomes, which have been implicated in modulation of the local and systemic maternal immune system. Here we investigate the possibility that exosomes secreted from the first trimester and term placenta carry HLA-G and B7 family immunomodulators. Confocal microscopy of placental sections revealed intracellular co-localization of B7-H1 with CD63, suggesting that B7-H1 associates with subcellular vesicles that give rise to exosomes. First trimester and term placental explants were then cultured for 24 h. B7H-1 (CD274), B7-H3 (CD276) and HLA-G5 were abundant in pelleted supernatants of these cultures that contained microparticles and exosomes; the latter, however, was observed only in first trimester pellets and was nearly undetectable in term explant-derived pellets. Further purification of exosomes by sucrose density fractionation confirmed the association of these proteins specifically with exosomes. Finally, culture of purified trophoblast cells in the presence or absence of EGF suggested that despite the absence of HLA-G5 association with term explant-derived exosomes, it is present in exosomes secreted from mononuclear cytotrophoblast cells. Further, differentiation of cytotrophoblast cells reduced the presence of HLA-G5 in secreted exosomes. Together, the results suggest that the immunomodulatory proteins HLA-G5, B7-H1 and B7-H3, are secreted from early and term placenta, and have important implications in the mechanisms by which trophoblast immunomodulators modify the maternal immunological environment.

Transdifferentiation of human amniotic epithelial cells into acinar cells using a double-chamber system

This study investigated the transdifferentiation of stem cells from human amnion tissue into functional acinar cells (ACs) using a co-culture system. Human amniotic epithelial cells (hAECs) were isolated from amnion tissue by mechanical mincing and enzymatic digestion. After primary culture, the phenotype of the cells was identified by flow cytometry (FCM) and immunocytochemical staining. hAECs were co-cultured with submandibular gland acinar cells of SD rats using a double-chamber system. The expression of α-amylase was determined by immunocytochemical method and fluorescent real-time quantitative reverse transcription polymerase chain reaction (RT-PCR) after induction for 1 and 2 weeks, respectively. Digestion with trypsin is an effective method for isolating hAECs from amnion tissue. These cells were positive for CD29 and CK19 and weakly positive for CD44 and α-amylase. Within 2 weeks, α-amylase in hAECs increased with induction time. The expression of α-amylase in hAECs was increased 3.38-fold after co-culturing for 1 week. This ratio increased to 6.6-fold, and these cells were positive for mucins, after co-culturing for 2 weeks. hAECs possess the potential to differentiate into ACs in vitro. They might be a stem cell resource for clinical applications of cell replacement therapy in salivary gland dysfunction diseases.

Heparin increases HLA-G levels in primary antiphospholipid syndrome

Objectives. The aim of this study was to investigate the HLA-G serum levels in Primary Antiphospholipid Syndrome (PAPS) patients, its impact on clinical and laboratory findings, and heparin treatment. Methods. Forty-four PAPS patients were age and gender matched with 43 controls. HLA-G serum levels were measured using an enzyme-linked immunosorbent assay (ELISA). Results. An increase in soluble HLA-G levels was found in patients compared to controls (3.35 (0–22.9) versus 1.1 (0–14), P = 0.017). There were no significant differences in HLA-G levels between patients with and without obstetric events, arterial thrombosis, venous thrombosis, or stroke. Sixty-six percent of patients were being treated with heparin. Interestingly, patients treated with heparin had higher HLA-G levels than ones who were not treated with this medication (5 (0–22.9) versus 1.8 (0–16) ng/mL, P = 0.038). Furthermore, patients on heparin who experienced obstetric events had a trend to increased HLA-G levels compared to patients who were not on heparin and did not have obstetric events (5.8 (0–22.9) versus 2 (0–15.2) ng/mL, P = 0.05). Conclusion. This is the first study to demonstrate that serum HLA-G levels are increased in APS patients. We also demonstrated that heparin increases HLA-G levels and may increase tolerance towards autoantigens.

The immunosuppressive molecule HLA-G and its clinical implications

Human leukocyte antigen G (HLA-G) is a non-classical major histocompatibility complex (MHC) class I molecule that, through interaction with its receptors, exerts important tolerogenic functions. Its main physiological expression occurs in placenta where it seems to participate in the maternal tolerance toward the fetus. HLA-G has been studied as a marker of pregnancy complications such as abortion or pre-eclapmsia. Although HLA-G is not expressed in most adult tissues, its ectopic expression has been observed in some diseases such as viral infections, autoimmune disorders, and especially cancer. HLA-G neo-expression in cancer is associated with the capability of tumor cells to evade the immune control. In this review, we will summarize HLA-G biology and how it participates in these physiopathological processes. Special attention will be paid to its role as a diagnostic tool and also as a therapeutic target.

Identification of circulating nonclassic human leukocyte antigen G (HLA-G)-like molecules in exudates

BACKGROUND

HLA-G in biological fluids has been proposed to be useful as a tumor marker as both a diagnostic and prognostic factor. Most HLA-G measurement procedures are based on ELISA methods using highly specific antibodies. However, results of published studies are in conflict regarding the clinical utility and even the nature of HLA-G present in circulation.

METHODS

We collected 118 exudates, 94 from cancer patients and 24 from patients without tumors. We measured HLA-G concentrations by ELISA using MEM-G/9 or G233 as capture antibody. Samples were immunoprecipitated with an anti-HLA-G antibody and analyzed by Western blot using a different anti-HLA-G antibody.

RESULTS

Discrepancies in HLA-G concentrations in exudates were observed depending on what capture anti-HLA-G antibody was used for ELISA (r = 0.376). These discrepancies were not observed when the ELISAs were performed using culture supernatants from HLA-G1-transfected cells (r = 0.983). Immunoprecipitation and Western blot of cell culture supernatants with 2 different anti-HLA-G antibodies produced the typical band at 39 kDa assigned to HLA-G. When the immunoprecipitation and western blot were performed with exudates, however, there were bands at 53 kDa and 70-76 kDa, higher molecular weights than those usually assigned to HLA-G. These HLA-G-like molecules were associated with β(2)-microglobulin and could also form disulfide bridges with other HLA-G-like molecules.

CONCLUSIONS

The main HLA-G antigenic molecules in exudates are HLA-G-like complexes, a factor that should be considered when analyzing HLA-G in biological fluids.

High level of soluble HLA-G in amniotic fluid is correlated with congenital transmission of Toxoplasma gondii

The expression of human leukocyte antigen (HLA)-G on cytotrophoblast cells contributes to maternal-fetal tolerance. Soluble forms of HLA-G (sHLA-G) can be detected in amniotic fluid (AF) and a decrease of sHLA-G is known to be correlated to fetal loss. In this work we investigated the role of sHLA-G in the transplacental passage of the protozoan parasite Toxoplasma gondii, responsible for congenital toxoplasmosis in about 30% of fetuses when primary infection (PI) occurs during pregnancy. We determined the sHLA-G concentration in 61 AF from women with PI and 24 controls. Our results showed higher sHLA-G levels in AF from PI than in controls (p<0.001). Moreover sHLA-G level from congenitally infected fetuses (n=12) was higher than in fetus in whom congenital infection was ruled out (n=49, p<0.05). These data suggest that sHLA-G could participate in immunomodulation necessary to avoid fetal loss due to Toxoplasma infection, but that over-expression could favor congenital transmission.

Innate immune natural killer cells and their role in HIV and SIV infection

The findings that early events during HIV-1 and SIV infection of Asian rhesus macaques dictate the levels of viremia and rate of disease progression prior to the establishment of mature and effective adaptive immune responses strongly suggest an important role for innate immune mechanisms. In addition, the fact that the major target of HIV and SIV during this period of acute infection is the gastrointestinal tissue suggests that whatever role the innate immune system plays must either directly and/or indirectly focus on the GI tract. The object of this article is to provide a general overview of the innate immune system with a focus on natural killer (NK) cells and their role in the pathogenesis of lentivirus infection. The studies summarized include our current understanding of the phenotypic heterogeneity, the putative functions ascribed to the subsets, the maturation/differentiation of NK cells, the mechanisms by which their function is mediated and regulated, the studies of these NK-cell subsets, with a focus on killer cell immunoglobulin-like receptors (KIRs) in nonhuman primates and humans, and finally, how HIV and SIV infection affects these NK cells in vivo. Clearly much has yet to be learnt on how the innate immune system influences the interaction between lentiviruses and the host within the GI tract, knowledge of which is reasoned to be critical for the formulation of effective vaccines against HIV-1.

HLA-G and immune evasion in cancer cells

Acquisition of novel gene products or new antigens in cancer cells elicits a host immune response that results in selection pressure for tumor clones to evade immunosurveillance. Similar to maternal-fetal tolerance and allotransplantation acceptance, upregulation of HLA-G expression has been found as one of the mechanisms that are programmed in cancer cells. HLA-G expression is frequently detected in a wide variety of human cancers and its protein levels negatively correlate with poor clinical outcome. The immune inhibitory effect can be achieved by binding of HLA-G molecules to the immunoglobulin-like inhibitory receptors that are expressed on the immunocompetent cells at all stages of the immune response. This review summarizes recent studies of HLA-G expression in human cancer, with a special focus on the molecular mechanisms that underlie how HLA-G molecules facilitate tumor cell evasion of the host immune response, and presents new directions for developing HLA-G-based diagnosis/therapeutics.

Soluble human leukocyte antigen-G isoforms in maternal plasma in early and late pregnancy

PROBLEM

Human Leukocyte Antigen (HLA)-G is a class Ib gene located in the human major histocompatibility complex (MHC). Several lines of investigation indicate that the HLA-G molecule is involved in the maternal acceptance of the semi-allogenic fetus during pregnancy and in the development of tolerance. Expression of soluble HLA-G (sHLA-G) is positively correlated with successful in vitro fertilization (IVF) treatments, and aberrant expression of HLA-G in certain complications of pregnancy, such as pre-eclampsia and spontaneous abortion, has been reported. The main purpose of this study was to investigate the levels of different soluble HLA-G isoforms in maternal plasma in early and late pregnancy.

METHOD OF STUDY

Soluble HLA-G (sHLA-G) can be detected in maternal blood, and in this study, two different isoforms of sHLA-G, namely sHLA-G1 generated by shedding of membrane-bound HLA-G1 and HLA-G generated by specific HLA-G transcripts, have been investigated early [median of 16.4 weeks of gestation (GW)] and late (median: 38.9 GW) in pregnancy in an original cohort of 580 pregnant Caucasian women.

RESULTS

Lower concentrations of sHLA-G1 were found late in pregnancy (>32 GW) in a group of women with severe pre-eclampsia compared with controls with uncomplicated pregnancies (P = 0.029, P(C) = 0.09; Mann-Whitney; Logistic regression analysis: P = 0.024, OR = 0.920, 95% CI: 0.855-0.989). However, this was not the case with HLA-G5, and significantly more of the cases with severe pre-eclampsia had detectable plasma HLA-G5 compared with that of the control group (P = 0.013, P(C) = 0.04; Mann-Whitney). Similar findings were not observed in women with gestational hypertension or existing hypertension continuing into pregnancy. Furthermore, there was a trend toward lower maternal plasma sHLA-G1 in a group of women with premature birth (<37 GW) compared with that of the control group (P = 0.028, P(C) = 0.17; Mann-Whitney). On the contrary, HLA-G5 was lower in the control group compared with that in the premature group (P = 0.004, P(C) = 0.02; Mann-Whitney).

CONCLUSION

This study shows in line with other published studies that a high, detectable soluble HLA-G concentration in maternal plasma or serum is not mandatory for a successful pregnancy. However, complications during pregnancy, such as (severe) pre-eclampsia, spontaneous abortion, IUGR, and premature birth, are associated with a low or undetectable level of soluble HLA-G in the maternal blood circulation. Also, this study indicates that sHLA-G1 is the interesting soluble HLA-G isoform in pre-eclampsia, and that low or undetectable levels of HLA-G5 at the end of pregnancy seem to be associated with an uncomplicated normal pregnancy, whereas in severe pre-eclampsia and possibly other pregnancy complications, such as preterm birth and IUGR, the level of HLA-G5 is higher.

The polymorphism of human leucocyte antigen-G gene in a healthy population of Iran

Human leucocyte antigen-G (HLA-G) is a non-classical HLA class I molecule that unlike the classical HLA, has low polymorphism. This molecule, initially, found on invasive trophoblast cells and is postulated to have mediatory role in maternal-fetal interface. So far 43 alleles of HLA-G gene have been found. Studies on alleles of HLA-G gene could be useful in understanding the genetic variants of HLA-G alleles in Iranian population. The goal of this research was to determine the polymorphism of HLA-G gene in a healthy population of Iran. Genomic DNA was isolated from the whole blood of 102 randomly selected, healthy, unrelated Iranian individuals using salting-out technique followed by polymerase chain reaction (PCR) amplification of the exons 2 and 3 of HLA-G gene. For the performance of PCR-restriction fragment length polymorphism method, the PCR products were digested with several restriction enzymes and the resulted fragments were analysed using gel electrophoresis. The obtained results indicated nine alleles of HLA-G in Iranian individuals including G*01011 (4%), G*01012 (29.86%), G*01013 (10.8%), G*01015 (1.47%), G*01017 (1.96%), G*01018 (2.45%), G*01041 (29.4%), G*01043 (1.96%) and the null allele G* 0105N (18.1%). According to this study, in the Iranian subjects the most incident alleles were G*01012 and G*01041. The results for the frequency of G*01012 showed some similarity with Caucasians (36.3%).

Impact of HLA-G in the outcome of vitiligo in Tunisian patients

Background:

The human leukocyte antigen (HLA) system in the skin coordinates the pigmentation and immune response and could be implicated in the pathogenesis of vitiligo. Human leukocyte antigen HLA-G is a nonclassic, major histocompatibility complex class I molecule expressed in the extravillous cytotrophoblast at the feto-maternal interface. It is known to protect the fetus from maternal cellular immunity. Analogically, it could be implicated in the pathogenesis of autoimmune diseases such as vitiligo.

Aims:

To compare the expression of HLA-G between vitiligo patients and healthy controls.

Materials and Methods:

In the present study, 22 vitiligo patients and 24 healthy controls were investigated to look for a possible correlation between HLA-G expression and this pathology. Expression of HLA-G in cutaneous biopsy specimens was investigated by immunohistochemical analysis.

Results:

HLA-G was detected in the biopsy specimens of 3 (13%) out of 22 patients. This number was significantly higher in healthy controls 18 (75%) out of 24 as compared to vitiligo patients (P < 0.001).

Conclusion:

There is significant negative correlation between HLA-G expression and vitiligo. In our mind, upregulation of HLA-G expression in lesional skin could be local (superficial expression) or systemic (soluble HLA-G isoforms) compensation to restore normal pigmentation in lesions.

Prognostic relevance of soluble human leukocyte antigen-G and total human leukocyte antigen class I molecules in lung cancer patients

The aim of this study was to determine the prognostic significance of soluble human leukocyte antigen (HLA) class I (sHLA-I) and HLA-G molecules in lung cancer patients. A total of 23 small-cell lung cancer (SCLC) and 114 non-small-cell lung cancer (NSCLC) patients, including 55 adenocarcinoma, 46 squamous cell carcinoma (SCC), and 13 patients with undifferentiated carcinoma, were prospectively enrolled. Levels of sHLA-G and sHLA-I were analyzed by specific enzyme-linked immunosorbent assay. Median levels of sHLA-G and sHLA-I were significantly increased in patients compared with controls (34 ng/ml [3.6-160] vs 14 ng/ml [0-98], p < 0.0001; 2580 ng/ml [749-5770] vs 1370 ng/ml [274-2670], p < 0.0001, respectively). Regarding the different subgroups, patients with NSCLC or SCLC showed increased sHLA-I levels, whereas sHLA-G was exclusively elevated in NSCLC, especially in patients with SCC. Patients with sHLA-I<2800 ng/ml (p = 0.008) or sHLA-G<40 ng/ml (p = 0.073) showed prolonged overall survival (OS). Using these cut-offs in patients with SCC, a pronounced prognostic significance for sHLA-G (p = 0.003) and sHLA-I (p = 0.004) was observed for the prediction of OS. Here, multivariate analysis confirmed sHLA-G and sHLA-I in addition to disease stage as independent prognostic factors. The prognostic power was further enhanced by combining the two factors and comparing the OS of patients with low sHLA-I and low sHLA-G against the remaining ones. In conclusion, plasma levels of sHLA-G and sHLA-I are potent predictors for OS in lung cancer patients.

Comprehensive analysis of MHC class I genes from the U-, S-, and Z-lineages in Atlantic salmon

BACKGROUND

We have previously sequenced more than 500 kb of the duplicated MHC class I regions in Atlantic salmon. In the IA region we identified the loci for the MHC class I gene Sasa-UBA in addition to a soluble MHC class I molecule, Sasa-ULA. A pseudolocus for Sasa-UCA was identified in the nonclassical IB region. Both regions contained genes for antigen presentation, as wells as orthologues to other genes residing in the human MHC region.

RESULTS

The genomic localisation of two MHC class I lineages (Z and S) has been resolved. 7 BACs were sequenced using a combination of standard Sanger and 454 sequencing. The new sequence data extended the IA region with 150 kb identifying the location of one Z-lineage locus, ZAA. The IB region was extended with 350 kb including three new Z-lineage loci, ZBA, ZCA and ZDA in addition to a UGA locus. An allelic version of the IB region contained a functional UDA locus in addition to the UCA pseudolocus. Additionally a BAC harbouring two MHC class I genes (UHA) was placed on linkage group 14, while a BAC containing the S-lineage locus SAA (previously known as UAA) was placed on LG10. Gene expression studies showed limited expression range for all class I genes with exception of UBA being dominantly expressed in gut, spleen and gills, and ZAA with high expression in blood.

CONCLUSION

Here we describe the genomic organization of MHC class I loci from the U-, Z-, and S-lineages in Atlantic salmon. Nine of the described class I genes are located in the extension of the duplicated IA and IB regions, while three class I genes are found on two separate linkage groups. The gene organization of the two regions indicates that the IB region is evolving at a different pace than the IA region. Expression profiling, polymorphic content, peptide binding properties and phylogenetic relationship show that Atlantic salmon has only one MHC class Ia gene (UBA), in addition to a multitude of nonclassical MHC class I genes from the U-, S- and Z-lineages.