Genetic polymorphism in HLA-G 3′UTR 14-bp ins/del and risk of cancer: a meta-analysis of case–control study

HLA-G 14 bp Ins/Del (rs66554220) Variant Is Not Associated with Breast Cancer in Women from Western Mexico

HLA-G is a physiology and pathologic immunomodulator detrimentally related to cancer. Its gene is heavily transcriptionally and post-transcriptionally regulated by variants located in regulator regions like 3'UTR, being the most studied Ins/Del of 14-bp (rs66554220), which is known to influence the effects of endogen cell factors; nevertheless, the reports are discrepant and controversial. Herein, the relationship of the 14-bp Ins/Del variant (rs66554220) with breast cancer (BC) and its clinical characteristics were analyzed in 182 women with non-familial BC and 221 disease-free women as a reference group. Both groups from western Mexico and sex-age-matched (sm-RG). The rs66554220 variant was amplified by SSP-PCR and the fragments were visualized in polyacrylamide gel electrophoresis. The variant rs66554220 was not associated with BC in our population. However, we suggest the Ins allele as a possible risk factor for developing BC at clinical stage IV (OR = 3.05, 95% CI = 1.16-7.96, p = 0.01); nevertheless, given the small stratified sample size (n = 11, statistical power = 41%), this is inconclusive. In conclusion, the 14-bp Ins/Del (rs66554220) variant of HLA-G is not associated with BC in the Mexican population, but might be related to advanced breast tumors. Further studies are required.

Elevated sHLA-G plasma levels post chemotherapy combined with ILT-2 rs10416697C allele status of the sHLA-G-related receptor predict poorest disease outcome in early triple-negative breast cancer patients

Introduction

Triple negative breast cancer (TNBC) shows an aggressive growing and spreading behavior and has limited treatment options, often leading to inferior disease outcome. Therefore, surrogate markers are urgently needed to identify patients at high risk of recurrence and more importantly, to identify additional therapeutic targets enabling further treatment options. Based on the key role of the non-classical human leukocyte antigen G (HLA-G) and its related receptor immunoglobulin-like transcript receptor-2 (ILT-2) in immune evasion mechanisms of tumors, members of this ligand-receptor axis appear to be promising tool for both, defining risk groups and potential therapeutic targets.

Materials and methods

To follow this, sHLA-G levels before and after chemotherapy (CT), HLA-G 3' UTR haplotypes, and allele variations rs10416697 at the distal gene promoter region of ILT-2 were defined in healthy female controls and early TNBC patients. The results obtained were associated with clinical status, presence of circulating tumor cell (CTC) subtypes, and disease outcome of patients in terms of progression-free or overall survival.

Results

sHLA-G plasma levels were increased in TNBC patients post-CT compared to levels of patients pre-CT or controls. High post-CT sHLA-G levels were associated with the development of distant metastases, the presence of ERCC1 or PIK3CA-CTC subtypes post-CT, and poorer disease outcome in uni- or multivariate analysis. HLA-G 3' UTR genotypes did not influence disease outcome but ILT-2 rs10416697C allele was associated with AURKA-positive CTC and with adverse disease outcome by uni- and multivariate analysis. The prognostic value of the combined risk factors (high sHLA-G levels post-CT and ILT-2 rs10416697C allele carrier status) was an even better independent indicator for disease outcome in TNBC than the lymph nodal status pre-CT. This combination allowed the identification of patients with high risk of early progression/death with positive nodal status pre-CT or with non-pathological complete therapy response.

Conclusion

The results of this study highlight for the first time that the combination of high levels of sHLA-G post-CT with ILT-2 rs10416697C allele receptor status is a promising tool for the risk assessment of TNBC patients and support the concept to use HLA-G/ILT-2 ligand-receptor axis as therapeutic targets.

HLA-G 5'URR regulatory polymorphisms are associated with the risk of developing gliomas

BACKGROUND

Human leukocyte antigen G (HLA-G) belongs to non-classical MHC class I molecules that is involved in the suppression of immune response. As HLA-G plays important role in the maintenance of fetal tolerance, its overexpression has been associated with tumor progression. For the regulation of HLA-G levels, genetic variants within the 5' upstream regulatory region (5'URR) are of crucial importance. Our study aimed to analyze the association between 16 HLA-G 5'URR variants, sHLA-G level and clinical variables in glioma patients.

METHODS

We investigated 59 patients with gliomas (mean age 54.70 ± 15.10 years) and 131 healthy controls (mean age 41.45 ± 9.75 years). Patient's blood was obtained on the day of surgical treatment. The HLA-G 5'URR polymorphisms were typed by direct sequencing and the plasma level of sHLA-G assessed by ELISA.

RESULTS

Haploblock within HLA-G 5'URR consisting of -762T, -716G, -689G, -666T, -633A, followed by -486C and -201A alleles were significantly more frequent in patients with gliomas than in the controls (p < 0.05). No correlation of HLA-G 5'URR variants with sHLA-G plasma level was found. Analysis of HLA-G 5'URR variants with main clinical variables in patients with grade IV gliomas revealed that haploblock carriers of -762CT, -716TG, -689AG, -666GT, -633GA, -486AC, -477GC, -201GA followed by -369AC carriers tend to have lower age at onset as compared to other genotype carriers (p = 0.04).

CONCLUSION

Our results suggest genetic association of HLA-G 5'URR variants with risk of developing gliomas and possible contribution of HLA-G to disease pathology.

HLA-G 14bp Ins/Del Polymorphism, Plasma Level of Soluble HLA-G, and Association with IL-6/IL-10 Ratio and Survival of Glioma Patients

HLA-G is an immune checkpoint molecule with immunosuppressive and anti-inflammatory activities, and its expression and level of its soluble form (sHLA-G) may play an important role in tumor prognosis. The HLA-G 14bp ins/del polymorphism and the plasma level of soluble HLA-G (sHLA-G) were investigated by a polymerase chain reaction and ELISA, respectively, in 59 glioma patients. A significantly higher proportion of glioma patients had the 14 nt insert in both homozygous and heterozygous states compared to the control group. Glioma patients also had higher plasma levels of sHLA-G. Patients with methylated MGMT promoters had lower levels of sHLA-G than those with unmethylated MGMT promoters. The level of sHLA-G negatively correlated with the overall survival of patients. Glioblastoma patients who survived more than one year after diagnosis had lower levels of sHLA-G than those surviving less than one year. Patients with sHLA-G levels below the cut-off value of 40 U/mL survived significantly longer than patients with sHLA-G levels above 40 U/mL. The levels of sHLA-G were also negatively correlated with the level of IL-6 (p = 0.0004) and positively with IL-10/IL-6 (p = 0.046). Conclusion: The presence of the 14 nt insert in both homozygous and heterozygous states of the HLA-G 14bp ins/del polymorphism is more frequent in glioma patients and the elevated plasma levels of sHLA-G are negatively associated with their survival.

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.

HLA-G and single nucleotide polymorphism (SNP) associations with cancer in African populations: Implications in personal medicine

The immune system plays an important role in protecting the body against malignancy. During cancer immunoediting, the immune system can recognize and keep checking the tumor cells by down-expression of some self-molecules or by increasing expression of some novel molecules. However, the microenvironment created in the course of cancer development hampers the immune ability to recognize and destroy the transforming cells. Human Leukocyte Antigen G (HLA-G) is emerging as immune checkpoint molecule produced more by cancer cells to weaken the immune response against them. HLA-G is a non-classical HLA class I molecule which is normally expressed in immune privileged tissues as a soluble or membrane-bound protein. HLA-G locus is highly polymorphic in the non-coding 3′ untranslated region (UTR) and in the 5′ upstream regulatory region (5′ URR). HLA-G expression is controlled by polymorphisms located in these regions, and several association studies between these polymorphic sites and disease predisposition, response to therapy, and/or HLA-G protein expression have been reported. Various polymorphisms are demonstrated to modulate its expression and this is increasingly finding more significance in cancer biology. This review focuses on the relevance of the HLA-G gene and its polymorphisms in cancer development. We highlight population genetics of HLA-G as evidence to espouse the need and importance of exploring potential utility of HLA-G in cancer diagnosis, prognosis and immunotherapy in the currently understudied African population.

Retrieving the deleterious mutations before extinction: genome-wide comparison of shared derived mutations in liver cancer and normal population

STUDY PURPOSE

Deleterious mutations would be rapidly purged from natural populations along with the extinction of their carriers. The currently observed mutations in existing species are mostly neutral. The inaccessibility of deleterious mutations impedes the functional studies on how these mutations affect the fitness at individual level.

STUDY DESIGN

The connection between the deleterious genotype and the non-adaptive phenotype could be bridged by sequencing the genome before extinction. Although this approach is no longer feasible for evolutionary biologists, it is feasible for cancer biologists by profiling the mutations in tumour samples which are so deleterious that the carriers hardly live.

RESULTS

By comparing the derived mutation profile between normal populations and patients with liver cancer, we found that the shared mutations, which are highly deleterious, are suppressed to low allele frequencies in normal populations and tissues, but show remarkably high frequency in tumours. The density of shared mutations is negatively correlated with gene conservation and expression levels.

CONCLUSIONS

Deleterious mutations are suppressed in functionally important genes as well as in normal populations. This work deepened our understanding on how natural selection act on deleterious mutations by analogising the cancer evolution to species evolution, which are essentially the same molecular process but at different time scales.

Cost-efficiency tradeoff is optimized in various cancer types revealed by genome-wide analysis

The tradeoff between cost and efficiency is omnipresent in organisms. Specifically, how the evolutionary force shapes the tradeoff between biosynthetic cost and translation efficiency remains unclear. In the cancer community, whether the adjustment of cost-efficiency tradeoff acts as a strategy to facilitate tumor proliferation and contributes to oncogenesis is uninvestigated. To address this issue, we retrieved the gene expression profile in various cancer types and the matched normal samples from The Cancer Genome Atlas (TCGA). We found that the highly expressed genes in cancers generally have higher tAI/nitro ratios than those in normal samples. This is possibly caused by the higher tAI/nitro ratios observed in oncogenes than tumor suppressor genes (TSG). Furthermore, in the cancer samples, derived mutations in oncogenes usually lead to higher tAI/nitro ratios, while those mutations in TSG lead to lower tAI/nitro. For a special case of kidney cancer, we investigated several crucial genes in tumor samples versus normal samples, and discovered that the changes in tAI/nitro ratios are correlated with the changes in translation level. Our study for the first time revealed the optimization of cost-efficiency tradeoff in cancers. The cost-efficiency dilemma is optimized by the tumor cells, and is possibly beneficial for the translation and production of oncogenes, and eventually contributes to proliferation and oncogenesis. Our findings could provide novel perspectives in depicting the cancer genomes and might help unravel the cancer evolution.

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.

Genetic variation in the HLA-G 3'UTR 14-bp insertion/deletion and the associated cancer risk: evidence from 25 case-control studies

Human leucocyte antigen-G (HLA-G) plays an important role in the progression of human cancers. A growing number of published studies have investigated the correlation between the HLA-G 3' untranslated region (3'UTR) 14-bp insertion/deletion (Ins/Del) polymorphism and the associated cancer risk in different populations. However, results from previous studies are inconclusive and inconsistent for the different type of cancers. Therefore, we undertook a meta-analysis to assess the effects of the HLA-G 14-bp Ins/Del polymorphism on cancer risk. A systematic literature search was conducted in PubMed, Web of Science, CNKI, VIP, and Wanfang databases to obtain relevant studies up to 28 January 2019. The pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were used. Twenty-five published case-control studies comprising 4981 cases and 6391 controls were included in the current meta-analysis. The results of the overall analysis revealed that the HLA-G 14-bp Ins/Ins genotype and Ins allele were associated with the total cancer risk in the homozygote comparison model (Ins/Ins vs. Del/Del: OR = 0.80, CI = 0.64-1.00; P=0.049) and the allelic comparison model (Ins vs. Del: OR = 0.89, CI = 0.81-0.99; P=0.035), with a protective role. Further subgroup analyses indicated that the HLA-G 14-bp Ins/Del polymorphism was associated with the risk of breast cancer and oesophageal cancer (EC), and significant risk of cancer was also observed in Mixed populations and population-based (PB). The results of our meta-analysis show that the HLA-G 14-bp Ins/Del polymorphism plays an important role in cancer risk, particularly in breast cancer and esophageal cancer in Mixed populations. Additional case-control studies with different types of cancer spanning different ethnicities are needed to extend the present findings.

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.

HLA-G 3' untranslated region variants +3187G/G, +3196G/G and +3035T define diametrical clinical status and disease outcome in epithelial ovarian cancer

Expression of the non-classical human leukocyte antigen-G (HLA-G) promotes cancer progression in various malignancies including epithelial ovarian cancer (EOC). As single nucleotide polymorphisms (SNPs) in the HLA-G 3' untranslated region (UTR) regulate HLA-G expression, we investigated HLA-G 3'UTR haplotypes arranged by SNPs in healthy controls (n = 75) and primary EOC patients (n = 79) and determined soluble HLA-G (sHLA-G) levels. Results were related to the clinical status and outcome. Although haplotype frequencies were similar in patients and controls, (i) sHLA-G levels were increased in EOC independent of the haplotype, (ii) homozygosity for UTR-1 or UTR-2 genotypes were significantly associated with metastases formation and presence of circulating tumor cells before therapy, whereas (iii) the UTR-5 and UTR-7 haplotypes were significantly associated with a beneficial clinical outcome regarding negative nodal status, early FIGO staging, and improved overall survival. Lastly, (iv) the ambivalent impact on clinical EOC aspects could be deduced to specific SNPs in the HLA-G 3'UTR: +3187G, +3196G and +3035T alleles. Our results give evidence that even if the genetic background of the HLA-G 3'UTR is identical between patients and controls, certain SNPs have the potential to contribute to diametrical clinical status/outcome in EOC.

Variation sites at the HLA-G 3' untranslated region confer differential susceptibility to HIV/HPV co-infection and aneuploidy in cervical cell

Post-transcriptional regulatory elements associated with transcript degradation or transcript instability have been described at the 3' untranslated region (3'UTR) of the HLA-G gene. Considering that HPV infection and aneuploidy, which causes gene instability, are associated with cervical cell malignancy, as well as the fact that HIV infection and HLA-G may modulate the immune response, the present study aimed to compare the frequencies of HLA-G 3'UTR polymorphic sites (14-base pair insertion/deletion, +3142C/G, and +3187A/G) between 226 HIV+ women co-infected (n = 82) or not with HPV (n = 144) and 138 healthy women. We also evaluated the relationship between those HLA-G 3'UTR variants and aneuploidy in cervical cells. HPV types and HLA-G polymorphisms were determined by PCR and sequencing of cervical samples DNA. Aneuploidy in cervical cell was measured by flow cytometry. The HLA-G 3'UTR 14-bp ins/del was not associated with either HIV nor HIV/HPV co-infection. The +3142G allele (p = 0.049) and +3142GG genotype (p = 0.047) were overrepresented in all HIV-infected women. On the other hand, the +3187G allele (p = 0.028) and the +3187GG genotype (p = 0.026) predominated among healthy women. The +3142G (p = 0.023) and +3187A (p = 0.003) alleles were associated with predisposition to HIV infection, irrespective of the presence or not of HIV/HPV co-infection. The diplotype formed by the combination of the +3142CX (CC or CG) and +3187AA genotype conferred the highest risk for aneuploidy in cervical cell induced by HPV. The HLA-G 3'UTR +3142 and +3187 variants conferred distinct susceptibility to HIV infection and aneuploidy.

Fold change based approach for identification of significant network markers in breast, lung and prostate cancer

Cancer belongs to a class of highly aggressive diseases and a leading cause of death in the world. With more than 100 types of cancers, breast, lung and prostate cancer remain to be the most common types. To identify essential network markers (NMs) and therapeutic targets in these cancers, the authors present a novel approach which uses gene expression data from microarray and RNA-seq platforms and utilises the results from this data to evaluate protein-protein interaction (PPI) network. Differentially expressed genes (DEGs) are extracted from microarray data using three different statistical methods in R, to produce a consistent set of genes. Also, DEGs are extracted from RNA-seq data for the same three cancer types. DEG sets found to be common in both platforms are obtained at three fold change (FC) cut-off levels to accurately identify the level of change in expression of these genes in all three cancers. A cancer network is built using PPI data characterising gene sets at log-FC (LFC)>1, LFC>1.5 and LFC>2, and interconnection between principal hub nodes of these networks is observed. Resulting network of hubs at three FC levels highlights prime NMs with high confidence in multiple cancers as validated by Gene Ontology functional enrichment and maximal complete subgraphs from CFinder.

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.

Interleukin-10 rs1800896 polymorphism is associated with increased head and neck cancer risk but not associated with its clinical stages

BACKGROUND

The association of interleukin-10 rs1800896 polymorphism with head and neck cancer risk and its clinical stages has been investigated by many published studies, but the results remain inconsistent. Therefore, we conducted this meta-analysis for further investigation.

RESULTS

Six case-control studies involving 1,781 head and neck cancer patients and 1,978 controls were yielded. The results indicated an association between rs1800896 polymorphism and increased head and neck risk [odds ratio (95%confidence interval) for G vs. A, GA vs. AA, GG vs. AA, GA+GG vs. AA, and GG vs. AA + GA were 1.63 (1.30-2.04), 3.17 (2.11-4.76), 1.63 (1.17-2.26), 1.73 (1.25-2.39), and 2.73 (1.82-4.09), respectively]. The subgroup analyses all obtained similar results with overall populations. The results of clinical stages yielded a non-significant association. No publication bias was detected.

MATERIALS AND METHODS

The PubMed and Chinese National Knowledge Infrastructure databases were searched up to December 27, 2016. Two authors independently selected studies, extracted and analyzed the data using the RevMan 5 software. Either a fixed effect or a random effect model was used to estimate pooled odds ratio and its 95% confidence intervals.

CONCLUSIONS

We concluded that interleukin-10 rs1800896 polymorphism was significantly associated with head and neck cancer risk but not with the clinical stages thereof.

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.

HLA-G 14-bp Ins/Ins Genotype in Patients Harbouring Helicobacter pylori Infection: A Potential Risk Factor?

H. pylori is a potent pathogen due to its capacity to successfully evade host defence mechanisms. Despite inducing immune responses in infected individuals, sometimes these responses fail to clear the infection and the bacterium establishes a persistent infection leading to chronic inflammation. In this context, we hypothesized that human leucocyte antigen G (HLA-G), a non-classical major histocompatibility complex molecule that has the ability to regulate immune responses both in physiological and in pathological conditions, may play an important role in promoting tolerance and helping H. pylori to subvert host defence and consequently establish a chronic infection. Therefore, we evaluated the expression of HLA-G 14-bp Ins/Del polymorphism in patients harbouring H. pylori infection, as well as their relationship with histological and demographic variables, to gain a better understanding of the actual role of HLA-G and its genetic polymorphisms in bacterial infection. Sixty-eight patients with clinical symptoms suggestive of H. pylori infection were enrolled to assess HLA-G 14-bp Ins/Del polymorphism allele and genotype frequencies. After adjustment for covariates (age and gender), the odds of having the genotype Ins/Ins, compared to Del/Del, were 3.77 times greater among HP+ cases than among controls. These findings suggest that the 14-bp Ins/Ins genotype, already associated with inflammatory and autoimmune diseases as well as some viral and parasitic infections, could confer a greater risk of developing H. pylori infection.