What the HLA-I!-Classical and Non-classical HLA Class I and Their Potential Roles in Type 1 Diabetes.

PURPOSE OF REVIEW: Hyperexpression of classical HLA class I (HLA-I) molecules in insulin-containing islets has become a widely accepted hallmark of type 1 diabetes pathology. In comparison, relatively little is known about the expression, function and role of non-classical subtypes of HLA-I. This review focuses on the current understanding of the non-classical HLA-I subtypes: HLA-E, HLA-F and HLA-G, within and outside the field of type 1 diabetes, and considers the possible impacts of these molecules on disease etiology. RECENT FINDINGS: Evidence is growing to suggest that non-classical HLA-I proteins are upregulated, both at the RNA and protein levels in the pancreas of individuals with recent-onset type 1 diabetes. Moreover, associations between non-classical HLA-I genotypes and age at onset of type 1 diabetes have been reported in some studies. As with classical HLA-I, it is likely that hyperexpression of non-classical HLA-I is driven by the release of diffusible interferons by stressed ß cells (potentially driven by viral infection) and exacerbated by release of cytokines from infiltrating immune cells. Non-classical HLA-I proteins predominantly (but not exclusively) transduce negative signals to immune cells infiltrating at the site of injury/inflammation. We propose a model in which the islet endocrine cells, through expression of non-classical HLA-I are fighting back against the infiltrating immune cells. By inhibiting the activity and function on NK, B and select T cells, the non-classical HLA-I, proteins will reduce the non-specific bystander effects of inflammation, while at the same time still allowing the targeted destruction of ß cells by specific islet-reactive CD8+ T cells.

The expression of selected molecular markers of immune tolerance in psoriatic patients.

BACKGROUND: Psoriasis is a chronic autoinflammatory disease whose underlying molecular mechanisms remain unclear. The disease is mediated by the cells and molecules of both the innate and adaptive immune systems. Some T cell surface molecules, including neuropilin-1 (NRP1), programmed death 1 (PD-1) and the human leukocyte antigen G (HLA-G), are known to play a role in the maintenance of immune tolerance. OBJECTIVES: The aim of this study was to investigate HLA-G, NRP1 and programmed cell death gene (PDCD1) mRNA expression in psoriatic patients. MATERIAL AND METHODS: The study included 72 psoriatic patients and 35 healthy individuals. Twentyone patients (29.17%) suffered from concomitant psoriatic arthritis. The mRNA expression of HLA-G, NRP1, and PDCD1 were determined using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The severity of skin lesions was assessed by means of the Psoriasis Area and Severity Index (PASI), Body Surface Area (BSA), the Patient Global Assessment (PGA), and the Dermatology Life Quality Index (DLQI). RESULTS: The median value of the PASI was 11.5, and of BSA was 15.8%. The expressions of NRP1 and PDCD1, but not HLA-G, were significantly lower in psoriatic patients in comparison with the control group. The expression of HLA-G, NRP1 and PDCD1 were not significantly different in the psoriatic arthritis and psoriasis vulgaris patients. CONCLUSIONS: The results of this study suggest that the molecular markers of immune tolerance, i.e., HLA-G, NRP1, and PD-1, may be involved in the immune response in psoriatic patients.

HLA-G regulatory variants and haplotypes with susceptibility to recurrent pregnancy loss.

HLA-G is a nonclassical Class I major histocompatibility complex (MHC) gene. This gene has a limited protein alteration that is produced by alternative splicing and can be important in the preservation of pregnancy. Recent findings suggest that alteration in HLA-G gene expression can lead to pregnancy failure, such as recurrent pregnancy loss (RPL). As the promoter SNPs of the gene may impact the HLA-G expression levels, the study of these SNPs is very important. In this study, for the promoter region of HLA-G gene in the case group (100 women with a history of two or more repeated miscarriages) and the control group (100 women with at least two successful pregnancies), PCR reaction was performed. Thereafter, PCR products were sequenced and the results were compared between the two groups. The results showed that -1573T>C and -1746C>A SNPs in the promoter of the HLA-G gene associated with RPL. The outcome of the haplotype analysis also showed that the association of two haplotypes, including H1 (ATCCAGGTACGCAA) and H2 (CTTCGAGAACGCAG) with RPL, is significant. The results showed that H1 is associated with a decreased and H2 is associated with an increased risk of RPL. These results indicate the importance of the HLA-G promoter SNPs in the pregnancy outcome. But to reach a more definite conclusion, subsequent studies on 3' UTR and other positions with polymorphism in the 5' UTR regions larger samples are necessary.

AAV vector-meditated expression of HLA-G reduces injury-induced corneal vascularization, immune cell infiltration, and fibrosis.

Over 1.5 million individuals suffer from cornea vascularization due to genetic and/or environmental factors, compromising visual acuity and often resulting in blindness. Current treatments of corneal vascularization are limited in efficacy and elicit undesirable effects including, ironically, vision loss. To develop a safe and effective therapy for corneal vascularization, adeno-associated virus (AAV) gene therapy, exploiting a natural immune tolerance mechanism induced by human leukocyte antigen G (HLA-G), was investigated. Self-complementary AAV cassettes containing codon optimized HLA-G1 (transmembrane) or HLA-G5 (soluble) isoforms were validated in vitro. Then, following a corneal intrastromal injection, AAV vector transduction kinetics, using a chimeric AAV capsid, were determined in rabbits. One week following corneal trauma, a single intrastromal injection of scAAV8G9-optHLA-G1 + G5 prevented corneal vascularization, inhibited trauma-induced T-lymphocyte infiltration (some of which were CD8+), and dramatically reduced myofibroblast formation compared to control treated eyes. Biodistribution analyses suggested AAV vectors persisted only in the trauma-induced corneas; however, a neutralizing antibody response to the vector capsid was observed inconsistently. The collective data demonstrate the clinical potential of scAAV8G9-optHLA-G to safely and effectively treat corneal vascularization and inhibit fibrosis while alluding to broader roles in ocular surface immunity and allogenic organ transplantation.

HLA-G 3' untranslated region polymorphic sites associated with increased HLA-G production are more frequent in patients exhibiting differentiated thyroid tumours.

BACKGROUND: HLA-G is a nonclassical class I histocompatibility molecule implicated on the immune escape mechanism of tumour cells. We evaluated the genetic diversity of HLA-G 3' untranslated region (3'UTR) and associated polymorphic sites with clinical presentation and with the magnitude of HLA-G thyroid expression. PATIENTS AND METHODS: Polymorphic sites at 3'UTR (14bpINS/DEL, +3003C/T, +3010C/G, +3027A/C, +3035C/T, +3142C/G, +3187A/G, +3196C/G) were characterized by sequencing analyses in blood samples of 72 patients exhibiting papillary thyroid carcinoma (PTC), 22 follicular thyroid carcinomas (FTC), 19 follicular adenomas (FA), 21 colloid goitres and 156 healthy controls. RESULTS: Compared to goitre and/or controls, patients with PTC exhibited higher frequency of 14bpDEL (P = 0·030), +3010G (P = 0·034), +3010CG (P = 0·044), +3142CG (P = 0·040), +3035C (P = 0·050) and +3187GG (P = 0·032). Patients with FTC presented higher frequency of 14bpINS/DEL (P = 0·020). The UTR-5 haplotype was underrepresented in PTC (P = 0·050). The +3003TT was more frequent in patients with PTC older than 45 years (P = 0·030). Male patients had a higher frequency of +3196GG (P = 0·040). Tumour multicentricity was associated with UTR-2 (P = 0·030). The following associations were observed in PTC and FTC combined: i) tumour size <2 cm with 14bpINS/INS (P = 0·030); ii) multicentricity with +3035CC (P = 0·030) and +3196GG (P = 0·030); iii) decreased thyroid HLA-G expression with +3196C and +3196CC; and iv) moderate HLA-G thyroid staining with UTR-2. CONCLUSIONS: HLA-G 3'UTR polymorphisms associated with a greater magnitude of HLA-G production were associated with differentiated thyroid tumours and with variables implicated in poor prognosis. These findings corroborate the unfavourable role of HLA-G in thyroid cancer.

HLA-G expression and role in advanced-stage classical Hodgkin lymphoma.

Non-classical human leucocyte antigen (HLA)-G class I molecules have an important role in tumor immune escape mechanisms. We investigated HLA-G expression in lymphonode biopsies taken from 8 controls and 20 patients with advanced-stage classical Hodgkin lymphoma (cHL), in relationship to clinical outcomes and the HLA-G 14-basepair (14-bp) deletion-insertion (del-ins) polymorphism. Lymphnode tissue sections were stained using a specific murine monoclonal HLA-G antibody. HLA-G protein expression was higher in cHL patients than controls. In the group of PET-2 positive (positron emission tomography carried out after 2 cycles of standard chemotherapy) patients with a 2-year progression-free survival rate (PFS) of 40%, we observed high HLA-G protein expression within the tumor microenvironment with low expression on Hodgkin and Reed-Sternberg (HRS) cells. Conversely, PET-2 negative patients with a PFS of 86% had higher HLA-G protein expression levels on HRS cells compared to the microenvironment. Lower expression on HRS cells was significantly associated with the HLA-G 14-bp ins/ins genotype. These preliminary data suggest that the immunohistochemical pattern of HLA-G protein expression may represent a useful tool for a tailored therapy in patients with cHL, based on the modulation of HLA-G expression in relation to achievement of negative PET-2.These preliminary data suggest that the immunohistochemical pattern of HLA-G protein expression may represent a useful tool for a tailored therapy in patients with cHL, based on the modulation of HLA-G expression in relation to achievement of negative PET-2.

Identification of novel microRNAs regulating HLA-G expression and investigating their clinical relevance in renal cell carcinoma.

The non-classical human leukocyte antigen G (HLA-G) is expressed at a high frequency in renal cell carcinoma (RCC) and is associated with a higher tumor grade and a poor clinical outcome. This might be caused by the HLA-G-mediated inhibition of the cytotoxicity of T and NK cells. Therefore a selective targeting of HLA-G might represent a powerful strategy to enhance the immunogenicity of RCC lesions. Recent studies identified a number of HLA-G-regulating microRNAs (miRs) and demonstrated an inverse expression of some of these miRs with HLA-G in RCC in vitro and in vivo. However, it was postulated that further miRs might exist contributing to the tightly controlled selective HLA-G expression.By application of a miR enrichment assay (miTRAP) in combination with in silico profiling two novel HLA-G-regulatory miRs, miR-548q and miR-628-5p, were identified. Direct interactions of both miRs with the 3' untranslated region of HLA-G were confirmed with luciferase reporter gene assays. In addition, qPCR analyses and immunohistochemical staining revealed an inverse, expression of miR-628-5p, but not of miR-548q to the HLA-G protein in primary RCC lesions and cell lines. Stable overexpression of miR-548q and miR-628-5p caused a downregulation of HLA-G mRNA and protein. This leads in case of miR-548q to an enhanced NK cell-mediated HLA-G-dependent cytotoxicity, which could be reverted by ILT2 blockade suggesting a control of the immune effector cell activity at least by this miR. The identification of two novel HLA-G-regulatory miRs extends the number of HLA-G-relevant miRs tuning the HLA-G expression and might serve as future therapeutic targets.

Co-expression of ILT4/HLA-G in human non-small cell lung cancer correlates with poor prognosis and ILT4-HLA-G interaction activates ERK signaling.

Non-small cell lung cancer (NSCLC) is the most common malignant tumor in the world, of which prognosis is generally poor due to insufficient mechanistic understanding. To explore the molecular pathogenesis of NSCLC, the co-expression of immunoglobulin-like transcript 4 (ILT4) and its ligand human leukocyte antigen G (HLA-G) in NSCLC tissues and cells were investigated. Here, we detected the expression of ILT4 and HLA-G in 81 tumor specimens from primary NSCLC patients, and we found that co-expression of ILT4/HLA-G was significantly associated with regional lymph node involvement, advanced stages, and the overall survival of patients. In NSCLC cell lines, HLA-G expression increased/decreased accordingly when ILT4 was up-/down-regulated, and ILT4 expression increased in a concentration-dependent manner via the stimulation of HLA-G fusion protein. Interestingly, HLA-G fusion protein could also up-regulate the phospho-ERK1/2 expression, which means the activation of extracellular signal-regulated kinase (ERK) signaling. All in all, our results indicate that the ILT4-HLA-G interaction might play an important role in NSCLC progression. Identification of ILT4 and HLA-G expression may provide an indicator to predict prognosis and guide prevention and treatment of NSCLC.

Upregulation of Soluble HLA-G5 and HLA-G6 Isoforms in the Milder Histopathological Stages of Helicobacter pylori Infection: A Role for Subverting Immune Responses?

The subversion mechanisms employed by Helicobacter pylori (H. pylori) to escape from immune surveillance and to establish persistent infection are poorly understood. Growing evidence indicates that expression of HLA-G, a non-classical major histocompatibility complex molecule, negatively regulates immune responses in pathological conditions, including infectious diseases. In this context, we aimed to evaluate HLA-G expression in the gastric microenvironment of individuals harbouring H. pylori and to correlate it with histological variables. Fifty-four gastric specimens from patients harbouring H. pylori infection were evaluated by immunohistochemistry using anti-HLA-G monoclonal antibody. As a result, HLA-G expression was detected in 43 of 54 specimens harbouring H. pylori. The presence of HLA-G was significantly associated with milder colonization by H. pylori (P < 0.02), milder inflammatory activity (P < 0.02) and bacterium histological location in the gastric antrum. This study is the first to explore HLA-G expression in the context of bacterial infection. Whether the biological role of HLA-G during H. pylori infection is beneficial or hazardous for patients remains to be defined.

TGF-ß induces HLA-G expression through inhibiting miR-152 in gastric cancer cells.

BACKGROUND: Mounting evidences have showed the important role of transforming growth factor-ß (TGF-ß) in immunological surveillance of tumors. Some studies have also indicated human leukocyte antigen (HLA)-G-associated immune escape involving TGF-ß management in gastric cancer (GC). However, the mechanism underlying it is unclear. This study aims to verify the correlations between HLA-G and TGF-ß, involving the potential targeting of miR-152 on HLA-G. RESULTS: TGF-ß and HLA-G levels were analyzed in blood samples from twenty GC patients with ELISA assays, while TGF-ß showed directly proportional to HLA-G levels in GC patients, and TGF-ß induced HLA-G up-regulation was also confirmed in GC cell lines. Furthermore, miR-152 expression could be inhibited by TGF-ß, and the negative post-transcriptionally regulation of miR-152 on HLA-G was also demonstrated through gain- and loss-of-function studies. Besides, miR-152 overexpression repressed HLA-G up-regulation induced by TGF-ß. And, miR-152 expression levels showed inversely proportional to both HLA-G and also TGF-ß levels in GC patients. CONCLUSION: TGF-ß could induce HLA-G expression in GC by inhibiting miR-152, involving its negative regulation on HLA-G. Since TGF-ß induced HLA-G up-regulation plays important role in immune escape, a potential application of miR-152 was suggested in GC treatment, or miR-152 might be one potential biomarker for GC.

Interaction between human mature adipocytes and lymphocytes induces T-cell proliferation.

BACKGROUND AIMS: Adipose tissue is a critical organ that plays a major role in energy balance regulation and the immune response through intricate signals. METHODS: We report on the inter-relation between mature adipocytes and lymphocytes in terms of adipocyte-derived T-cell chemo-attractants and adipocyte metabolic effects on lymphocytes. RESULTS: During the culture time, mature adipocytes changed their structural and functional properties into de-differentiated cells. Isolated mature adipocytes expressed significantly higher levels of CIITA, major histocompatibility complex II (human leukocyte antigen [HLA]-DR) and costimulatory signal molecule CD80 compared with adipocytes after the de-differentiation process. Moreover, human leukocyte antigen-G, which may prevent the immune responses of mesenchymal stromal cells, was expressed at lower level in mature adipocytes compared with de-differentiated adipocytes. In line with these molecular data, functional results showed different immunoregulatory properties between adipocytes before and after the de-differentiation process. Mature adipocytes stimulated the proliferation of total lymphocytes and immunoselected cell populations CD3+, CD4+ and CD8+ in a direct contact-dependent way that involved the major histocompatibility complex I and II pathways. Moreover, adipocytes secreted potential chemo-attractant factors, but data showed that adipocyte-derived culture medium was not sufficient to activate lymphocyte proliferation, suggesting that a direct contact between adipocytes and immune cells was needed. However, specific mature adipocyte cytokines enhanced lymphocyte proliferation in a mixed lymphocyte reaction. CONCLUSIONS: In conclusion, cross-talk occurs between adipocytes and lymphocytes within adipose tissue involving T-cell chemo-attraction by mature adipocytes. Our findings, together with current observations in the field, provide a rationale to identify adipocyte-lymphocyte cross-talk that instigates adipose inflammation.

Prominent HLA-G Expression in Liver Disease But Not After Liver Transplantation.

BACKGROUND: HLA-G is a nonclassical MHC class I molecule and its physiological expression restricted to placental extravillous trophoblasts contributes to maternal tolerance to the semiallogeneic fetus. Aberrant expression of HLA-G in human organ grafts has been proposed to contribute to graft acceptance. METHODS: We studied HLA-G expression in liver tissue and serum of adult liver transplant recipients before, early, and late after transplantation in relation to liver function and operational tolerance. RESULTS: Cirrhotic explant livers showed robust HLA-G expression on hepatocytes, whereas the majority of noncirrhotic livers and graft biopsies taken before or after liver transplantation (LTX) showed no, or weak, HLA-G expression. The HLA-G expression was induced on hepatocytes in vitro by TGF-ß, but not by other relevant cytokines. Serum levels of the HLA-G isoforms 1 + 5 gradually declined after LTX. Early after LTX, serum HLA-G levels were higher in patients with acute rejection episodes than nonrejectors. Late after LTX, serum HLA-G levels did not differ between operationally tolerant patients and patients on regular immunosuppressive therapy. CONCLUSIONS: Our data do not support a graft-protective role for HLA-G after LTX, but show that end-stage liver diseases are associated with HLA-G expression on hepatocytes, which may determine a negative feedback to protect the liver against immunological damage.

Genetic polymorphisms and expression of HLA-G and its receptors, KIR2DL4 and LILRB1, in non-small cell lung cancer.

Human leukocyte antigen-G (HLA-G) is a nonclassical HLA class I molecule absent from most normal tissues but detected in many malignant tumors. It is recognized by cells of the immune system using LILRB1, KIR2DL4 and LILRB2 receptors. We attempted to find out whether some polymorphisms of HLA-G, LILRB1 and KIR2DL4 genes are associated with susceptibility to nonsmall cell lung cancer (NSCLC). Four polymorphisms in HLA-G, i.e. -964A>G (rs1632947), -725C>G>T (rs1233334), -716T>G (rs2249863) in the promoter, and a 14 base pair insertion/deletion (14 bp indel) in the 3'-untranslated region (3'UTR), and five in LILRB1 - 5651G>A (rs41308748) in intron 14, 5717C>T L622L (rs1061684), 5724G>A E625K (rs16985478), 5774 C>A P641P (rs41548213) in exon 15, and 5806C>T (rs8101240) in 3'UTR - as well as 9620 9A/10A (rs11410751) polymorphism in exon 7 of KIR2DL4 were typed using different laboratory techniques. Only one single nucleotide polymorphism (SNP) in HLA-G (-964A>G) and one in LILRB1 (5724G>A) were found to influence the risk of NSCLC. In addition, 5724G>A was associated with protection from tumor cell infiltration of regional lymph nodes. Most importantly, we detected HLA-G and LILRB1 expression in tumor specimens, but no correlation with genetic polymorphisms was observed. HLA-G and LILRB1 protein expression levels in tumor tissue were significantly correlated with tumor stage.

Significance of tumour cell HLA-G5/-G6 isoform expression in discrimination for adenocarcinoma from squamous cell carcinoma in lung cancer patients.

Human leucocyte antigen (HLA)-G has seven isoforms, of which HLA-G1-G4 are membrane-bound and HLA-G5-G7 are soluble. Previous studies reinforced HLA-G expression was strongly related to poor prognosis in different types of cancers. Among these studies, the monoclonal antibody (mAb) 4H84 was used which detects all HLA-G isoform heavy chain; unfortunately, leaves the specific types of isoforms expressed in lesions undistinguished and its clinical significance needs to be clarified. To explore clinical significance of lesion soluble HLA-G (sHLA-G) in non-small-cell lung cancer (NSCLC), mAb 5A6G7 recognizing HLA-G5/-G6 molecules was used. Tumour cell sHLA-G expression in 131 primary NSCLC lesions (66 squamous cell carcinoma, 55 adenocarcinoma and 10 adenosquamous carcinoma) were analysed with immunohistochemistry. Data showed that sHLA-G expression was observed in 34.0% (45/131) of the NSCLC lesions, which was unrelated to patient age, sex, lymph nodal status, tumour-node-metastasis stage and patient survival. However, tumour cell sHLA-G expression in lesions was predominately observed in adenocarcinoma lesions (73.0%, 40/55) which was significantly higher than that in squamous cell carcinoma (6.0%, 4/66) and adenosquamous carcinoma lesions (10.0%, 1/10, P < 0.001). The area under the receiver operating characteristic curve for lesion sHLA-G was 0.833 (95% CI: 0.754-0.912, P < 0.001) for adenocarcinoma versus squamous cell carcinoma. Our findings for the first time showed that tumour cell sHLA-G was predominately expressed in lung adenocarcinoma, which could be a useful biomarker to discriminate adenocarcinoma from squamous cell carcinoma in NSCLC patients.

Imiquimod treatment effectively reduces the percentage of viable cells in a cervical carcinoma cell line but does not affect the expression of HLA-G or OCT-4.

OBJECTIVE: Cervical cancer is a challenging pathologic entity because of its lack of response to conventional chemotherapy. Imiquimod is a synthetic analogue which seems to activate skin immune cells, acting as a Toll-like receptor 7 agonist. Previous studies in the field of cervical cancer have showed that its application may play a significant role in the treatment of cervical HPV infection with or without cervical intraepithelial neoplasia (CIN). In the present study we investigate the therapeutic potential of imiquimod in a cervical carcinoma cell line and evaluate whether the expression of HLA-G and OCT-4 is altered during this treatment. METHODS: HeLa cells were cultured in Dulbecco's modified Eagle medium and treated with 200 µl of imiquimod diluted solution (50 µg/ml). Cultured cells were allocated in four groups 1) control, 2) DMSO only, 3) DMSO and imiquimod for 48 hours, 4) DMSO and imiquimod for 72 hours. RESULTS: In the imiquimod treated cell lines we observed a significant reduction of viable cells at 48 and 72 hours (p = .001). The relative expression analysis of OCT-4 and HLA-G genes at 48 and 72 hours did not reveal significant differences after imiquimod treatment. CONCLUSION: Imiquimod effectively reduces the percentage of viable HeLa cells and should be further evaluated in future clinical trials. This effect takes place as of 48 hours after its initial application and seems to persist at least until 72 hours. HLA-G and OCT-4 expression is not affected by this type of treatment.

A combination of single nucleotide polymorphisms in the 3'untranslated region of HLA-G is associated with preeclampsia.

Reduced expression of human leukocyte antigen-G (HLA-G) has been linked to onset of preeclampsia. Associations have also been reported between preeclampsia and single nucleotide polymorphisms (SNP) in the 3'-untranslated region (UTR) of the HLA-G gene. However, there are conflicting results between studies. This studied examined whether a SNP, by itself or in combination with other SNPs, in the 3'UTR of the HLA-G gene is associated with an increased risk of preeclampsia. Placenta samples were obtained from 47 preeclamptic and 68 control cases. DNA was extracted, and the 3'UTR was sequenced and analyzed for nine polymorphisms using different genetic models of inheritance. Four of these polymorphisms have never been analyzed for an association with preeclampsia. Disputing existing reports, preeclamptic cases were suggestively associated with a G/G-genotype at SNP +3187 (p<0.05). Several SNP combinations were more prevalent in preeclampsia cases. Following corrections for multiple testing, one SNP combination (+3027C/C and +3187G/G) was significantly more prevalent in preeclampsia cases using co-dominant, additive, and dominant models (p<0.001). Taken together with the current literature, the data suggests that HLA-G 3'UTR SNP-pair associations, and not individual SNPs, could be useful in a predictive test for the susceptibility to preeclampsia.

The human leukocyte antigen G molecule (HLA-G) expression in patients with nasal polyposis.

INTRODUCTION: Sinonasal polyposis (NP) is a chronic inflammatory pathology of the nasal/paranasal cavities which affects from 1%-4% of the population. Although polyps seem to be a manifestation of chronic inflammation in both allergic and non-allergic subjects, the pathogenesis of nasal polyposis remains unknown. HLA-G molecules are a kind of no classic class I antigen with anti-inflammatory and tolerogenic properties. Little attention has been paid to the role of HLA-G chronic inflammatory disorders. OBJECTIVE: The aim of this study is to investigate the expression of HLA-G in the NP. MATERIALS AND METHODS: Prospective study involving samples of patients presenting with nasal polyposis that were subjected to the immunohistochemistry technique. After a skin prick test, all patients were divided into atopic and nonatopic groups and classified as asthmatic or non-asthmatic. RESULTS: Immunohistochemical staining demonstrated a higher expression of the HLA-G molecule in samples from nonatopic than in those from atopic patients, and was significantly lower in the non-asthmatic patients. CONCLUSION: These results indicate that HLA-G may play an important role in the pathology of nasal polyposis. Considering the anti-inflammatory properties of HLA-G, this study suggests that it could reduce susceptibility to atopy and asthma.

The HLA-G 14bp insertion/deletion polymorphism in women with recurrent spontaneous abortion.

HLA-G is a non-classical HLA class Ib molecule with limited protein variability generated by alternative splicing. HLA-G displays immunotolerant properties and hence plays important roles in the maintenance of a successful pregnancy and maternal tolerance of the semiallogenic fetus. Polymorphism of the HLA-G gene may potentially affect the biological properties of the protein, and a 14-bp insertion/deletion polymorphism in exon 8 of the 3' untranslated region (3' UTR) of the HLA-G gene is thought to influence HLA-G expression. To study the association of the 14-bp insertion/deletion (INDEL) polymorphism with the risk of recurrent spontaneous abortion (RSA), we used polymerase chain reaction (PCR) amplification, and genotyped 85 women in the case group (women who have had two or more unexplained RSA) and 85 women in the control group (women who have had at least one normal pregnancy). Our results showed that the frequencies of the-14 bp/-14 bp and +14 bp/+14 bp genotypes were reduced in women with RSA, while that of the +14 bp/-14 bp genotype was significantly increased in RSA compared with the control group of normal fertile women; no significant differences in the allele frequencies of the HLA-G 14-bp polymorphism were observed. These results suggest a possible significance of the HLA-G 14-bp INDEL polymorphism in the outcome of pregnancy. However, further studies on other polymorphic sites in the 3 UTR and 5' UTR regions, as well as monitoring the serum HLA-G concentration are necessary in order to determine the potential implications of this marker in our population.

The human leukocyte antigen G molecule (HLA-G) expression in patients with nasal polyposis / A expressão do antígeno humano leucocitário G (HLA-G) em pacientes com polipose nasossinusal

INTRODUCTION: Sinonasal polyposis (NP) is a chronic inflammatory pathology of the nasal/paranasal cavities which affects from 1%-4% of the population. Although polyps seem to be a manifestation of chronic inflammation in both allergic and non-allergic subjects, the pathogenesis of nasal polyposis remains unknown. HLA-G molecules are a kind of no classic class I antigen with anti-inflammatory and tolerogenic properties. Little attention has been paid to the role of HLA-G chronic inflammatory disorders. OBJECTIVE: The aim of this study is to investigate the expression of HLA-G in the NP. MATERIALS AND METHODS: Prospective study involving samples of patients presenting with nasal polyposis that were subjected to the immunohistochemistry technique. After a skin prick test, all patients were divided into atopic and nonatopic groups and classified as asthmatic or non-asthmatic. RESULTS: Immunohistochemical staining demonstrated a higher expression of the HLA-G molecule in samples from nonatopic than in those from atopic patients, and was significantly lower in the non-asthmatic patients. CONCLUSION: These results indicate that HLA-G may play an important role in the pathology of nasal polyposis. Considering the anti-inflammatory properties of HLA-G, this study suggests that it could reduce susceptibility to atopy and asthma. .

INTRODUÇÃO: Polipose nasossinusal (PNS) é uma patologia inflamatória crônica das cavidades nasais/paranasais que afeta 1%-4% da população. Embora os pólipos pareçam ser uma manifestação de inflamação crônica em ambos os indivíduos alérgicos e não alérgicos, a patogênese da polipose nasal permanece desconhecida. Moléculas HLA-G são antígenos não clássicos da classe I com propriedades anti-inflamatórias e tolerogênicas. Pouca atenção tem sido dada ao papel do HLA-G em doenças inflamatórias crônicas. OBJETIVO: Investigar a expressão de HLA-G na PNS. MATERIAIS E MÉTODOS: Estudo prospectivo de pacientes com polipose nasal que foram submetidas à técnica de imuno-histoquímica. Após realizarem teste cutâneo, os pacientes foram divididos em grupos atópicos e não atópicos e classificados como asmáticos ou não asmáticos. RESULTADO: A coloração imuno-histoquímica mostrou uma maior expressão da molécula HLA-G em pacientes não atópicos do que naqueles atópicos e foi significativamente inferior nos pacientes não asmáticos. CONCLUSÃO: Os resultados indicam que o HLA-G pode ter um papel importante na patologia da polipose nasal. Considerando as propriedades anti-inflamatórias do HLA-G, este estudo sugere que ele poderia reduzir a susceptibilidade a atopia e asma. .

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.