HLA-E regulates NKG2C+ natural killer cell function through presentation of a restricted peptide repertoire

NK cells interact with the HLA-E molecule via the inhibitory receptor NKG2A and the activating receptor NKG2C. Hence, HLA-E can have a dual role in the immune response. In the present study, we aim to investigate the functional consequences of HLA-E for NKG2A and NKG2C expressing NK cell subsets by using a panel of HLA-E binding peptides derived from CMV, Hsp60 and HLA class I. PBMC derived from healthy subjects were used as targets for isolated NK cells and NK cell activation was examined by analysis of the expression of the degranulation marker CD107a. Peptide induced HLA-E expression inhibited degranulation of NKG2A+ NK cell subsets with almost all peptides, whereas NKG2A− NKG2C+ NK cell responses were enhanced only after incubation with four peptides; 1.3-fold with CMV(I), A80 and B13 and 3.2-fold with HLA-G derived peptide. In addition, the HLA-E:G peptide complex triggered NKG2C receptor internalization, as evidenced by reduction in the percentage of NKG2C+ NK cells when incubated with the peptide, which could be restored by addition of Bafilomycin. In conclusion: in contrast to NKG2A, NKG2C is regulated by HLA-E only when HLA-E is in complex with a restricted peptide repertoire, especially in combination with the HLA-G leader peptide.     

Polymorphisms within the human leucocyte antigen-E gene and their associations with susceptibility to rheumatoid arthritis as well as clinical outcome of anti-tumour necrosis factor therapy

Involvement of the non-classical human leucocyte antigen-E (HLA-E) in both innate and acquired immune response suggests its possible role in development of autoimmune pathologies. This study was undertaken to investigate relationships between the HLA-E gene single nucleotide polymorphisms (SNPs) and a risk of rheumatoid arthritis (RA), as well as to evaluate a potential of these polymorphisms to modulate clinical outcome of anti-tumour necrosis factor (TNF) treatment in female patients. A total of 223 female patients with RA receiving anti-TNF biological therapy and 134 female healthy subjects were enrolled into the study. Genotypings for two SNPs within the HLA-E gene (rs1264457 HLA-E*01:01/01:03; rs1059510 HLA-E*01:03:01/01:03:02) were performed using a polymerase chain reaction (PCR) amplification employing LightSNiP assays. Clinical response was evaluated according to the European League Against Rheumatism (EULAR) criteria at 12 and 24 weeks after initiation of the therapy. The frequency of the HLA-E*01:01/01:01 genotype was decreased significantly in RA patients in comparison to controls (P = 0·031). The presence of the HLA-E*01:01/01:01 genotype in patients correlated with better EULAR response after 12 weeks of anti-TNF treatment, while 01:03 allele carriers were generally unresponsive to the treatment (P = 0·014). The HLA-E*01:03/01:03 genotype was also over-represented among non-responding patients in comparison to HLA-E*01:01/01:01 homozygotes (P = 0·021). With respect to the HLA-E rs1059510 variation, a better response after 12 weeks was observed more frequently in patients carrying the HLA-E*01:03:01/01:03:01 genotype than other genotypes (P = 0·009). The results derived from this study imply that HLA-E polymorphisms may influence RA susceptibility and affect clinical outcome of anti-TNF therapy in female RA patients.     

HCMV感染与滋养细胞HLA-E蛋白表达的相关性

目的：研究HCMV感染与滋养细胞HLA-E蛋白表达的相关性。方法：体外分离、培养的滋养细胞系HTP-8,用HCMV AD169标准病毒株感染细胞。免疫荧光法检测HCMV感染后滋养细胞中HLA-E蛋白的表达。结果：病毒感染后10天内,细胞胞浆和胞膜均有HLA-E蛋白表达,感染后1-5天表达水平较低,6-10天表达强度显著增强。结论：滋养细胞HLA-E蛋白的表达与HCMV感染有相关性。     

Pure red cell aplasia associated with expansion of CD3+ CD8+ granular lymphocytes expressing cytotoxicity against HLA-E+ cells

T-cell granular lymphocyte-proliferative disorder (T-GLPD) is characterized by the proliferation of cytotoxic T lymphocytes, and is often associated with pure red cell aplasia (PRCA). The mechanism involved in the development of PRCA in T-GLPD is unknown. Peripheral blood mononuclear cells were isolated from 20 patients with T-GLPD. Ten patients had associated PRCA. Granular lymphocytes (GLs) of T-GLPD are positive for CD94, but not NKG2A. To clarify the functional role of CD94 in T-GLPD, we performed a cytotoxicity assay against the trophoblast cell line, BeWo, which is known to express human leucocyte antigen (HLA)-E, a natural ligand of CD94, and is deficient in other HLA class I and class II antigens. GLs isolated from T-GLPD with PRCA patients killed BeWo cells more significantly than GLs from T-GLPD without PRCA patients. Furthermore, GLs from T-GLPD with PRCA were significantly stimulated by a monoclonal antibody against CD94, whereas those of T-GLPD without PRCA were not. Taken together, HLA-E, a ligand of CD94, was suggested to stimulate CD94+ cells to kill HLA-E+ cells in T-GLPD with PRCA. GLs of T-GLPD with PRCA have a potential positive activity against HLA-E+ cells, whereas GLs from T-GLPD without PRCA do not. CD94 may play a key role in the pathogenesis of PRCA in T-GLPD.     

HLA-E-bound peptides influence recognition by inhibitory and triggering CD94/NKG2 receptors: preferential response to an HLA-G-derived nonamer

The HLA-E class Ib molecule constitutes a major ligand for the lectin-like CD94/NKG2 natural killer (NK) cell receptors. Specific HLA class I leader sequence-derived nonapeptides bind to endogenous HLA-E molecules in the HLA-defective cell line 721.221, inducing HLA-E surface expression, and promote CD94/NKG2A-mediated recognition. We compared the ability of NK clones which expressed either inhibitory or activating CD94/NKG2 receptors to recognize HLA-E molecules on the surface of 721.221 cells loaded with a panel of synthetic nonamers derived from the leader sequences of most HLA class I molecules. Our results support the notion that the primary structure of the HLA-E-bound peptides influences CD94/NKG2-mediated recognition, beyond their ability to stabilize surface HLA-E. Further, CD94/NKG2A⁺ NK clones appeared more sensitive to the interaction with most HLA-E-peptide complexes than did effector cells expressing the activating CD94/NKG2C receptor. However, a significant exception to this pattern was HLA-E loaded with the HLA-G-derived nonamer. This complex triggered cytotoxicity very efficiently over a wide range of peptide concentrations, suggesting that the HLA-E/G-nonamer complex interacts with the CD94/NKG2 triggering receptor with a significantly higher affinity. These results raise the possibility that CD94/NKG2-mediated recognition of HLA-E expressed on extravillous cytotrophoblasts plays an important role in maternal-fetal cellular interactions.     

Is there a role played by HLA-E,if any,in HPV immune evasion?

Cervical cancer incidence worldwide exceeds half a million new cases per year. The human papillomavirus (HPV) being the major causative agent of CC uses a variety of strategies to evade immune surveillance, where the immune status varies amongst individuals. This immune evasion altered by HPV is reflected in persistent infections, causing the evolution of cervical neoplasia. The role of the immune system in viral recognition and elimination is of extreme relevance in the development of CC. The interactions of the HLA-E ligand in the target cell along with CD94/NKG2 receptors, which are expressed predominantly, but not exclusively, on NK cells’ surface, are responsible for activating or inhibiting cytotoxic activity according to their function. The engagement between HLA-E and CD94/NKG2 molecules is one of the fundamental surveillance mechanisms in patients with CIN I, II and III, where HLA-E expression increases significantly, especially in HPV 16 and 18 infections. Higher HLA-E expression was observed in most histopathological types of CC, and at the same time was correlated to best survival of the patient. This review aims to summarize and discuss the immunological role of HLA-E in the context of HPV infection and immune system evasion, and the oncogenic process of cervical cancer.     

HLA-E基因与allo-HSCT移植效果关系的研究

目的： 探讨HLA-E基因与异基因造血干细胞移植（allo-HSCT）效果的关系。方法：用PCR-SSP方法分别检测22对allo-HSCT供者及受者的HLA-E基因型，并分2组：供受者HLA-E相合组和供受者HLA-E不合组。比较2组在移植后植入率、移植物抗宿主病（GVHD）、免疫重建、自体恢复或恶性病复发等方面的差异。结果：22对移植病例的供受者中，共检出3个HLA-E等位基因，分别为E*0101、E*01031和E*01032，未检出E*0102和*0104。供受者HLA-E相合组9对，供受者HLA-E不合组13对。两组在移植后植入率、GVHD、免疫重建、自体恢复或恶性病复发等无统计学差异。结论：HLA-E基因多态性与allo-HSCT移植效果未见相关性。     

Nonclassical human leukocyte antigen (HLA-G,HLA-E,and HLA-F) in coronary artery disease

AimsSeveral evidences suggest the association between the evolution of coronary artery disease (CAD) and the development of coronary syndrome that is often associated with disrupted plaque and partial or complete thrombosis of the related artery. Because of the inflammatory nature of CAD, we investigated the human leukocyte antigen (HLA)-G, HLA-E, and HLA-F genetic polymorphisms within CAD patients and evaluated their potential association with this disease in Tunisian population.MethodsDifferent polymorphisms in HLA-G (14-bp Insertion/Deletion, +3142C/G), HLA-E (HLA-E*01:01/01:03 A/G), HLA-F (HLA-F*01:02 T/C, 01:03 C/T, 01:04 A/C) genes were typed using different laboratory techniques in a cohort of 89 CAD patients and 84 controls.ResultsA significant association was reported between the HLA-G +3142 G allele (OR = 1.64, 95% CI = 1.05–2.56, p = 0.02) and increased risk of CAD. No association was found for the other studied polymorphisms. When we considered the haplotypes, we found TDELCA and TDELGG haplotypes associated to CAD with p = 0.008 and p = 0.030, respectively, suggesting the potential interaction between HLA-G and HLA-E genes.ConclusionsOur findings indicated that the HLA-G +3142C/G polymorphism and TDELCA and TDELGG haplotypes can harbour a reliable diagnosis value for the risk of CAD development suggesting that HLA-G, -E and -F molecules might be involved in the pathogenesis of the disease. However, further studies are necessary to confirm our results.     

Low variability at the HLA-E promoter region in the Brazilian population

Little information has been reported regarding the regulatory region of the HLA-E gene. Only a proximal segment (300 bp immediately before exon 1) has been described at IMGT/HLA database. We aimed to evaluate the genetic diversity of the promoter region by PCR amplification and DNA sequencing. We observed a pattern of sequencing interruption in the same position in all samples, suggesting the presence of a secondary structure hampering the DNA polymerase sliding during the sequencing process, which was confirmed after bioinformatics analysis. Considering the promoter region evaluated (nucleotide −440 to −1), only three variation sites were found, including one new variation site at position −104, and the concomitant deletions already described at positions −187 and −186. We concluded that the promoter region of the HLA-E gene presents few and rare variable sites in this population sample; however, the double-stranded branch formation hampered the evaluation of the distant promoter by conventional sequencing.