HLA-G Expression in Tumor Tissues and Soluble HLA-G Plasma Levels in Patients with Gastrointestinal Cancer

Background: Overexpression of human leukocyte antigen G (HLA-G) and increased plasma levels of solubleHLA-G (sHLA-G) have been reported in different human malignancies, and are believed to be involved in tumor immuneevasion. Objectives: This study was designed to evaluate the expression of HLA-G in tumor tissues and the plasmalevels of sHLA-G in patients with gastrointestinal cancer, and to determine their associations with clinicopathologicalfactors. The link between Helicobacter pylori infection and increased HLA-G expression or sHLA-G levels was alsoinvestigated in patients with gastric cancer. Methods: HLA-G expression was investigated in tumor tissues from 100patients with gastric and colorectal adenocarcinoma using immunohistochemistry test, and plasma levels of sHLA-Gwere measured in 82 patients with ELISA method. The presence of H. pylori genome was investigated in tumortissues from 25 patients with gastric cancer by PCR method. Results: HLA-G expression was observed in 43% ofcolorectal cancers and 34.6% of gastric cancers, and was not related with any of the clinicopathological factors. Therewas a significant correlation between increased sHLA-G level and stage I tumors. Eight of 25 (32%) gastric cancerspecimens were positive for H. pylori, of which 3 samples were positive for HLA-G. Soluble HLA-G levels were abovethe cut-off value in all H. pylori-positive patients. Conclusion: Plasma levels of sHLA-G were significantly increasedin our patients with a sensitivity of 89% and a specificity of 62%. Soluble HLA-G level can be considered a usefulindicator for the early diagnosis of gastric and colorectal adenocarcinoma.     

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.     

Amniotic fluid soluble human leukocyte antigen-G in term and preterm parturition,and intra-amniotic infection/inflammation

Objective.?Circulating soluble human leukocyte antigen-G (sHLA-G) has been associated with pregnancy complications, and determination of sHLA-G concentrations in amniotic fluid (AF) has been reported in normal pregnancies. Our aim was to determine if the AF concentrations of sHLA-G change with advancing gestation, spontaneous labor at term, and in patients with spontaneous preterm labor (PTL) with intact membranes, as well as in those with preterm prelabor rupture of membranes (PROM), in the presence or absence of intra-amniotic infection/inflammation (IAI).

Study design.?This cross-sectional study included the following groups: (1) mid-trimester (n?=?55); (2) normal pregnancy at term with (n?=?50) and without (n?=?50) labor; (3) spontaneous PTL with intact membranes divided into: (a) PTL who delivered at term (n?=?153); (b) PTL who delivered preterm without IAI (n?=?108); and (c) PTL with IAI (n?=?84); and (4) preterm PROM with (n?=?46) and without (n?=?44) IAI. sHLA-G concentrations were determined by ELISA. Non-parametric statistics were used for analysis.

Results.?(1) Among patients with PTL, the median AF sHLA-G concentration was higher in patients with IAI than in those without IAI or women that delivered at term (p?<?0.001 for both comparisons); (2) Similarly, patients with preterm PROM and IAI had higher median AF sHLA-G concentrations than those without IAI (p?=?0.004); (3) Among patients with PTL and delivery, those with histologic chorioamnionitis and/or funisitis had a higher median AF sHLA-G concentration than those without histologic inflammation (p?<?0.001); and (4) The median AF sHLA-G concentration did not change with advancing gestational age.

Conclusions.?AF sHLA-G concentrations are elevated in preterm parturition associated to IAI as well as in histologic chorioamnionitis. We propose that sHLA-G may participate in the regulation of the host immune response against intra-amniotic infection.     

Effect of immune regulatory pathways after immunization with GMZ2 malaria vaccine candidate in healthy lifelong malaria-exposed adults

BackgroundDespite appreciable immunogenicity in malaria-naive populations, many candidate malaria vaccines are considerably less immunogenic in malaria-exposed populations. This could reflect induction of immune regulatory mechanisms involving Human Leukocyte Antigen G (HLA-G), regulatory T (Treg), and regulatory B (Breg) cells. Here, we addressed the question whether there is correlation between these immune regulatory pathways and both plasmablast frequencies and vaccine-specific IgG concentrations.MethodsFifty Gabonese adults with lifelong exposure to Plasmodium spp were randomized to receive three doses of either 30 µg or 100 µg GMZ2-CAF01, or 100 µg GMZ2-alum, or control vaccine (rabies vaccine) at 4-week intervals. Only plasma and peripheral blood mononuclear cells isolated from blood samples collected before (D0) and 28 days after the third vaccination (D84) of 35 participants were used to measure sHLA-G levels and anti-GMZ2 IgG concentrations, and to quantify Treg, Breg and plasmablast cells. Vaccine efficacy was assessed using controlled human malaria infection (CHMI) by direct venous inoculation of Plasmodium falciparum sporozoites (PfSPZ Challenge).ResultsThe sHLA-G concentration increased from D0 to D84 in all GMZ2 vaccinated participants and in the control group, whereas Treg frequencies increased only in those receiving 30 µg or 100 µg GMZ2-CAF01. The sHLA-G level on D84 was associated with a decrease of the anti-GMZ2 IgG concentration, whereas Treg frequencies on D0 or on D84, and Breg frequency on D84 were associated with lower plasmablast frequencies. Importantly, having a D84:D0 ratio of sHLA-G above the median was associated with an increased risk of P. falciparum infection after sporozoites injection.ConclusionRegulatory immune responses are induced following immunization. Stronger sHLA-G and Treg immune responses may suppress vaccine induced immune responses, and the magnitude of the sHLA-G response increased the risk of Plasmodium falciparum infection after CHMI. These findings could have implications for the design and testing of malaria vaccine candidates in semi-immune individuals.     

Influence of early ICSI-derived embryo sHLA-G expression on pregnancy and implantation rates: a prospective study

BACKGROUND: We have previously reported the retrospective observation that when at least one embryo, transferred on day 3, expressed sHLA-G above the geometric mean (sHLA-G+) 46 h post-ICSI, there was a marked improvement in both pregnancy (PR) and implantation (IR) rates. METHODS: The media surrounding individual embryos derived from ICSI performed on oocytes from 482 women < or =43 years of age were tested for sHLA-G expression by specific ELISA. RESULTS: We report here prospective results showing improved IVF results following the transfer of 'good quality' embryos (7-9 cells with <20% fragmentation) by preferentially including at least one sHLA-G+ embryos. PR and IR for women < or =38 years were 63% and 32% when one transferred embryo was sHLA-G+, and 69% and 36% when at least two embryos were sHLA-G+. When none of the embryos transferred was sHLA-G+, PR and IR were 25% and 13%, respectively. Comparable PR and IR for women 39-43 years were 29% and 11% when none of the transferred embryos were sHLA-G+; 38% and 15% when at least one sHLA-G+ embryo was transferred; and 61% and 26% when at least two 2 sHLA-G+ embryos were transferred. The data were stratified by patient age. CONCLUSIONS: PR and IR increased with the addition of each sHLA-G+ embryo, regardless of age. While there are significant barriers to routine embryo sHLA-G testing, we believe that if implemented, this would provide a mechanism for optimizing IVF PR while minimizing the risk of multiple pregnancies.     

Meta-analysis of the relationship between 14bp insertion/deletion polymorphism of HLA-G gene and susceptibility to systemic lupus erythematosus

We performed a meta-analysis to examine the relationship between the human leukocyte antigen-G (HLA-G) 14 base pairs sequence (14bp) insertion (ins)/deletion (del) polymorphism to systemic lupus erythematosus (SLE). Eligible studies were extracted in PubMed, Embase, Cochrane Library and CNKI (Chinese) up to March 31, 2014. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated to evaluate the strength of the association. Finally, 7 studies with 1864 cases and 2259 controls were involved in this meta-analysis. Overall, the HLA-G 14bp ins/del polymorphism was significantly associated with SLE susceptibility (ins vs. del: OR = 1.179, 95%CI = 1.037–1.341, P = 0.012; ins/ins vs. del/del: OR = 1.394, 95%CI = 1.153–1.684, P = 0.001; ins/del vs. del/del: OR = 1.199, 95%CI = 1.041–1.382, P = 0.012; ins/ins + ins/del vs. del/del: OR = 1.252, 95%CI = 1.097–1.430, P = 0.001). When stratified by ethnicity, significance was found in Asians (ins/ins vs. del/del: OR = 1.326, 95%CI = 1.001–1.756, P = 0.049) and Caucasians (ins/ins vs. del/del: OR = 1.454, 95%CI = 1.126–1.878, P = 0.004; ins/del vs. del/del: OR = 1.288, 95%CI = 1.051–1.579, P = 0.015; ins/ins + ins/del vs. del/del: OR = 1.340, 95%CI = 1.106–1.623, P = 0.003). Our results suggest that the HLA-G 14bp insertion allele might act as an increased risk against SLE. Besides, this is the first meta-analysis to report an association between the HLA-G 14bp ins/del polymorphism and SLE. Larger and well-designed studies are needed to further confirm these findings.     

HLA-G profile of infertile couples who underwent assisted reproduction treatment

HLA-G codes for a non-classical class I (Ib) protein which is mainly expressed in trophoblast cells. Many pieces of evidence pointed out its essential role conferring immunological tolerance to the fetus. Some HLA-G alleles have been linked to enhanced or reduced HLA-G protein levels expression, which have been associated with reproductive failure. In this study 33 couples undergoing ART (assisted reproduction treatment; n = 66) and 120 couples who conceived naturally (controls; n = 240) were enrolled in the study. Genotyping was performed by SBT and tagged an 1837 bp at 5′URR as well as exons 2, 3 and 4 of HLA-G. Alleles, genotypes and haplotypes were compared between infertile and control groups using Fisher Exact Test. The haplotype HLA-G¹010101b/HLA-G¹01:01:01 showed statistically significant higher frequency in control groups. The immunogenetics of infertility is complex and might be dependent on different genes involved in the establishment of a successful pregnancy. A better understanding of HLA-G alleles and haplotypes structure and how the genetic diversity at their regulatory sites could impact on their level of expression and build up the susceptibility or protection conditions may shed light on the comprehension of immunogenetics mechanisms acting at the fetus-maternal interface.     

Donor derived HLA-G polymorphisms have a significant impact on acute rejection in kidney transplantation

Human leucocyte antigen G (HLA-G) is a non-classical HLA-class I antigen that exerts immunoregulatory functions. The polymorphisms 14-base pair (bp) insertion/deletion (ins/del) (rs1704) and +3142C > G (rs1063320) could modify the expression level of HLA-G.We genotyped 175 kidney recipients (41 with acute rejection and 134 without rejection) and additionally the corresponding donors for both polymorphisms in order to assess their impact on acute rejections one year after transplantation. In addition, we analyzed soluble HLA-G (sHLA-G) levels in sera of 32 living kidney donors and compared the sHLA-G levels in terms of the present genotype.In kidney transplant recipients we did not observe an impact of the 14-bp ins/ins and the +3142GG genotypes on acute rejection. In contrast, we found a higher frequency of these genotypes in the donors of the no-rejection collective compared to the rejection collective (4.9% vs. 24.6%; p = 0.010; 9.8% vs. 31.3%; p = 0.006). Soluble HLA-G levels were highest in healthy kidney donors homozygous for the 14-bp insertion.We conclude that the HLA-G polymorphisms of the donor are of importance for susceptibility of acute rejection in kidney transplantation. We suggest that the 14-bp ins/ins and the +3142GG genotypes are protective against kidney transplant rejection.     

可溶性sHLA-G在子痫前期患者与正常晚孕妇女血中的表达

目的探讨可溶性白细胞抗原G（sHLA-G）在子痫前期发病中的意义。方法采用酶联免疫吸附法（ELISA）测定45例子痫前期患者,49例正常足月妊娠者外周静脉血及靠近胎盘部位处脐静脉血中可溶性（sHLA-G）水平。结果子痫前期组外周血sHLA-G浓度为（6.61±2.51）μg/L,正常组外周血sHLA-G浓度（22.03±3.12）μg/L,两组比较差异有统计学意义（P〈0.05）;子痫前期组脐静脉血sHLA-G浓度为（7.23±2.12）μg/L,正常组脐静脉血sHLA-G浓度（25.21±3.70）μg/L,差异有统计学意义（P〈0.05）;子痫前期组外周血sHLA-G浓度为（6.61±2.51）μg/L,脐静脉血sHLA-G浓度为（7.23±2.12）μg/L,差异无统计学意义（P〉0.05）;正常组外周血sHLA-G浓度（22.03±3.12）μg/L,脐静脉血sHLA-G浓度（25.21±3.70）μg/L,两组比较差异有统计学意义（P〈0.05）。结论妊娠妇女血中sHLA-G水平的下降可能导致子痫前期的发病,血中sHLA-G主要来源于胎盘组织。