HLA-B27 polymorphism

A proposed HLA-B*27 screening method for ankylosing spondylitis detection based on tag-single nucleotide polymorphisms: a preliminary study

BACKGROUND

Ankylosing spondylitis (AS) is a type of inflammatory arthritis that affects primarily the spine. There is a strong association of the HLA-B*27 allele with AS pathogenesis, but recent studies have demonstrated the participation of ERAP1 gene in the genetic susceptibility. The aim of this study was to determine whether HLA-B tag-single nucleotide polymorphisms (SNPs) and ERAP1-related genetic variations associated with AS have equal or similarly performance in patients´ screening compared to HLA-B*27 standard genotyping in Mexican population.

METHODS AND RESULTS

Genomic DNA from patients with AS and population-based controls from Mexico City was analyzed for five single nucleotide polymorphisms (SNPs): rs4349859, rs13202464, rs116488202, tagging HLA-B*27; and rs30187 and rs27044 in ERAP1 gene. TaqMan genotype assay method was used for SNPs genotyping. We found a significant association between AS and the heterozygote genotypes and minor alleles of the HLA-B*27 tag-SNPs, as well as for their haplotypes. With respect to ERAP1 polymorphisms, no significant associations were observed (p > 0.05). The sensitivity and specificity analysis showed values of 0.96 and 1.00 for the rs4349859 SNP, and 0.96 and 0.94 for the rs116488202 SNP, respectively, in detecting HLA-B*27 compared to the B27 test as the gold standard.

CONCLUSIONS

HLA-B*27 tag-SNPs are associated with AS susceptibility; furthermore, the rs4349859 SNP by its own have an outstanding performance in detecting HLA-B*27 and therefore can be proposed as screening marker in the identification of HLA-B*27 in our population.

Comparison of HLA-B*27 subtypes between Chinese patients with ankylosing spondylitis and non-ankylosing spondylitis carriers

Objective

To investigate the distribution of subtypes between HLA-B*27 (+) patients with ankylosing spondylitis (AS) and carriers.

Methods

This case–control study recruited Chinese Han patients with HLA-B*27 (+) AS from six hospitals in Zhejiang Province, China between 2013 and 2018. Patients who were examined for HLA-B*27 because of back pain or arthralgia but who did not have AS or arthritis were recruited as controls. HLA-B*27 target DNA was amplified by amplification refractory mutation systems and HLA-B*27 subtypes were determined by sequencing.

Results

The positive rate of HLA-B*27 was significantly higher in the AS group than in the control group. In AS patients, HLA-B*2704 was predominant at 86.4%, followed by HLA-B*2705 at 12.6%; HLA-B*2704 and HLA-B*2705 were found in 70.0% and 10.0% of controls, respectively. HLA-B*2702 and HLA-B*2706 were detected at low frequencies in the control group, while the rare subtype HLA-B*2715 was only observed in two (1.0%) patients with AS. HLA-B*2707 was not detected in AS or control groups.

Conclusion

HLA-B*2704 is the predominant subtype among patients with AS and carriers in southeast China.

Association of HLA-B27 and Behcet's disease: a systematic review and meta-analysis

Background

To calculate the genetic impact of the “HLA-B27” allele on the risk of Behcet’s disease (BD) progression using a systematic review and meta-analysis on case control papers.

Methods

A systematic review search was conducted on the MeSH keywords of Behcet’s disease, HLAB27 and B27 in PubMed, Scopus, ProQuest, EMBASE, SID, Magiran, IranDoc and IranMedex databases from 1975 to Aug 2017. Data underwent meta-analysis (random effect model) in CMA2 software. Pooled odds ratios with 95% confidence intervals were calculated for each study. The heterogeneity of the articles was measured using the I² index.

Results

Twenty two articles met the inclusion criteria for 3939 cases and 6077 controls. The pooled OR of “HLA-B27” in BD patients compared with controls was [1.55 (CI 95% 1.01–2.38), P = 0.04]. The OR differ among different countries or geographical areas, focus on domination the European countries. Quality of studies was moderate and heterogeneity was relatively high (I² = 66.9%).

Conclusions

There is a significant correlation between HLA-B27 and Behcet’s Disease, but it was weak. Environmental and genetic factors might determine which the “HLA-B27” alleles manifest Behcet’s disease progression. Future researches is required to perform about what factors can do to positively and separately influence Behcet’s disease.

HLA-B*27 subtypes and their implications in the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is a highly heritable kind of arthritis that affects the vertebral column. AS risk has been associated strongly with Human leukocyte antigen (HLA)-B*27. In fact, some HLA-B*27 subtypes have been associated with the increased disease risk, although some specific subtypes have not shown such associations. It is supposed that HLA-B*27 plays a major role in the etiopathogenesis of the disease. However, the difference in pathogenic outcomes of HLA-B*27 certain subtypes needs to be clarified. The purpose of this review article is to overview on the detailed implications of the HLA-B*27 subtypes in the etiopathogenesis of AS. Moreover, the role of ERAP1 in AS and its epistasis with HLA-B*27 have been reviewed.

Low frequency of HLA-B27 in ankylosing spondylitis and its relationship with clinical findings in patients from Turkey

Objective

Human leukocyte antigen B27 (HLA-B27) is strongly associated with ankylosing spondylitis (AS). However, the association between clinical findings and HLA-B27 vary in terms of geographic area. This study aimed to determine the frequency of HLA-B27 positivity and its relationship with clinical findings.

Material and Methods

All subjects fulfilling the modified New York diagnosis criteria for AS enrolled in study. The demographic data and histories of the patients were collected retrospectively from patient files. Polymerase chain reaction-based HLA-B27 analysis of all cases was performed.

Results

The male to female ratio was 2.5, and mean age of disease onset was 28.3 years. HLA-B27 positivity was detected in 115 patients (70%). Although there was no significant connection between the clinical findings and HLA-B27 positivity, there was a positive relationship between the presence of syndesmophytes and HLA-B27 positivity (p=0.044). The number of patients treated with anti-tumor necrosis factor was higher in the HLA-B27-positive group; however, the difference was not significant (39.1% and 28.9%, respectively). More patients were treated with anti-tumor necrosis factor in the HLA-B27-positive group than in the HLA-B27-negative group; however, the difference was not significant (39.1% and 28.9%, respectively).

Conclusion

Compared with northern Europe, HLA-B27-positive rate of patients with AS has been shown to be lower in Turkey. Except for the presence of syndesmophytes, there was not a statistically significant relationship between HLA-B27 positivity and clinical and radiologic findings.

Ankylosing spondylitis: from cells to genes

Ankylosing spondylitis (AS) is a chronic inflammatory disease of unknown etiology, though it is considered an autoimmune disease. HLA-B27 is the risk factor most often associated with AS, and although the mechanism of involvement is unclear, the subtypes and other features of the relationship between HLA-B27 and AS have been studied for years. Additionally, the key role of IL-17 and Th17 cells in autoimmunity and inflammation suggests that the latter and the cytokines involved in their generation could play a role in the pathogenesis of this disease. Recent studies have described the sources of IL-17 and IL-23, as well as the characterization of Th17 cells in autoimmune diseases. Other cells, such as NK and regulatory T cells, have been implicated in autoimmunity and have been evaluated to ascertain their possible role in AS. Moreover, several polymorphisms, mutations and deletions in the regulatory proteins, protein-coding regions, and promoter regions of different genes involved in immune responses have been discovered and evaluated for possible genetic linkages to AS. In this review, we analyze the features of HLA-B27 and the suggested mechanisms of its involvement in AS while also focusing on the characterization of the immune response and the identification of genes associated with AS.

Distribution of HLA class I and II genes in ankylosing spondylitis patients from Morocco

OBJECTIVES

In Morocco, the patients affected by ankylosing spondylitis (AS) presents a high frequency of coxitis. Our study reports, for the first time, the polymorphism of Human Leukocyte Antigen (HLA) class I and class II molecules in the Moroccan patients.

METHODS

Forty-six patients diagnosed with an AS and coxitis were compared to a group of 183 healthy controls matched by age, sex and ethnic origin. The HLA typing was performed using microlymphocytotoxicity for the class I (-A, -B) and PCR-SSP for the class II (-DR, -DQ).

RESULTS

We found a significant increase of the HLA-B27 antigen frequency (P<0.0001, RR=20.9) in AS patients (29.3%) compared to the controls (3.2%) and a significant decrease in the frequency of HLA-B12 and HLA-B18 antigens. Examination of HLA class II distribution shows a significant increase of the HLA-DRB1*11 allele frequency in patients (P<0.0001). Concerning HLA-DQB1* alleles, no significant difference between patients and controls was appreciable.

CONCLUSIONS

The HLA-B27 antigen is involved in the predisposition to the AS with coxitis in the Moroccan population. However, the low frequency observed in our population suggests the existence of other genetic and/or environmental factors. Other HLA genes seem to confer a predisposing effect (DRB*11) or a protective effect (B12 and B18) against the disease.

Does HLA-B*2706 protect against ankylosing spondylitis? A meta-analysis

The human leukocyte antigen (HLA)-B*2706 is a relatively rare subtype of HLA-B27. In contrast to most HLA-B27 subtypes, some studies have reported HLA-B*2706 to be protective against ankylosing spondylitis (AS). A systematic review and a meta-analysis of available studies was performed to investigate the association of HLA-B*2706 with AS. After literature review a random effect meta-analysis was performed. No studies were found comparing the frequency of HLA-B*2706 in AS patients and controls. Meta-analysis of seven studies using HLA-B27-positive AS patients and controls showed a protective effect of HLA-B*2706 on development of AS in HLA-B27 individuals (odds ratio = 0.128, 95% CI = 0.043-0.378, P < 0.001). The results of the meta-analysis of HLA-B*2706 in HLA-B27-positive patients and controls is preliminary evidence of a protective effect of HLA-B*2706 against AS in the population. There is a clear need for additional studies on HLA-B*2706 in AS. Due to the fact that HLA-B*2706 is more or less restricted to Southeast Asia, researchers in this part of the world may have an essential role in performing these studies.

HLA B27 allele types in homogeneous groups of juvenile idiopathic arthritis patients in Latvia

Juvenile idiopathic arthritis (JIA) is a heterogeneous condition and therapeutic strategies vary in different JIA types. The routinely accepted practice to start with Sulphasalazine (SS) as the first line treatment in patients with HLA B27 positive JIA proves to be ineffective in a large proportion of children.

OBJECTIVE

to investigate HLA B27 positive JIA patients clinical characteristics, determined HLA B27 allele types and their connection with antirheumatic treatment in homogenous patient groups.

MATERIALS AND METHODS

56 patients diagnosed with JIA and observed over the period 2006 to 2009 included in the study. HLAB27 allele types were determined using PCR method.

RESULTS

In HLA B27 positive JIA patients mean disease onset was 12.34 ± 3.3 years. Most common (44%) JIA type was enthesitis related arthritis. Positive response to the treatment with SS was found in 32% of patients, Methotrexate (MTX) - in 43%, combined treatment - SS with MTX was effective in 12.5%. 12.5% of patients required combination MTX with Enbrel.Eight HLA B27 allele types were found in JIA patients in Latvia: *2702, *2703, *2704, *2705, *2710, *2715, *2717, *2728. The most common was *2705 - in 55% of cases. Among all the patients enthesitis related arthritis most commonly occurred in patients with HLAB*2705 allele (OR = 2.01, p < 0.02), oligoarthritis in patients with *2710 allele (OR = 3.0, p < 0.04) and polyarthritis with *2717 allele (OR = 3.0, p < 0.05). In patients with *2705 allele effective treatment was MTX (OR = 1.13, p < 0.03) and MTX with SS (OR = 2.02, p < 0.05), but in patients having *2703 allele - MTX with Enbrel (OR = 2.94, p < 0.02).

CONCLUSIONS

There are 8 different HLA B27 alleles in JIA patients in Latvia and the most common is *2705, but in order to assert them to be disease associated alleles, more extensive studies are needed, including control group of HLA B27 positive healthy individuals. Standard treatment approach with SS proves to be unsatisfactory in the majority of JIA patients. To improve children's quality of life achieving rapid disease control, the first line treatment in HLA B27 positive patients should be MTX. In order to start with the most appropriate drug it is necessary to determine HLAB 27 type at the onset of disease.

Predominant association of HLA-B*2704 with ankylosing spondylitis in Chinese Han patients

The HLA-B27 subtypes have a varied racial and ethnic prevalence throughout the world. However, the association of B27-subtypes with ankylosing spondylitis (AS) in the mainland China is unknown. To determine the association of B27-subtypes with AS in the Mainland Chinese Han population, a total of unrelated 153 patients with AS were enrolled in a large case-control association study, and 1545 unrelated, healthy, ethnically matched blood donors were included as controls. The genotyping of B27 and its subtypes was performed using the polymerase chain reaction with sequence specific primers (PCR-SSP). A total of 130 (84.97%) AS patients and 61 (3.95%) healthy controls were B27 positive. Three B27-subtypes, B*2704, B*2705 and B*2710, were further identified, of which both B*2704 and B*2705 were strongly AS associated. B*2710 was only detected in one AS patient and two other healthy controls. Considering only B27-positive cases and controls, a statistically different frequency of B27-subtypes was observed, with an over-representation of B*2704 (P = 0.018). B*2704 was clearly more strongly associated than B*2705 with AS [odds ratio (OR ) = 2.4, P = 0.011]. Furthermore, a combined analysis including three previous studies of B27-subtype distributions in Chinese AS cases confirmed the stronger association of B*2704 with AS than B*2705 (OR = 2.5, P = 0.00094).

Detection of a novel HLA-B27 allele, B*2740, in Taiwanese volunteer bone marrow donors by sequence-based typing: curiosity rewarded

We report here a novel HLA-B allele, B*2740, discovered in Taiwanese volunteer marrow donors. The new sequence has nucleotide variation at position 527 (T-->A) as compared to B*2708. The nucleotide change caused an amino acid substitution from valine (V) to glutamic acid (E) at codon 152. Since B*2740 carries sequence confers to HLA-Bw6 public epitope we believe that this novel B*27 allele might have been generated from a gene conversion involving a Bw4-specific allele (probably B*2704) and a Bw6-specific allele.

Low frequency of HLA-B27 in ankylosing spondylitis patients from Turkey

OBJECTIVES

Ankylosing spondylitis is strongly associated with HLA-B27. However, the strength of the association with HLA-B27 and the clinical features may vary in different parts of the world. The aim of this study is to compare the clinical features of AS and the frequencies of HLA-B27 and its alleles in patients from Turkey with other series.

METHODS

One hundred and twelve patients (72 male/40 female) fulfilling the modified New York criteria for the classification of AS and 55 (27 male/28 female) healthy controls were typed for HLA-B27 and allele frequencies by sequence specific primer (PCR/SSP) method and assessed for clinical manifestations.

RESULTS

Male to female ratio was 1.8, mean age at disease onset was 23.5 and 24.1% of patients reported juvenile onset of symptoms. Peripheral arthritis was seen in 52.7% of patients. Family history (p=0.01) and peripheral arthritis (p=0.02) were more frequent in females and spinal involvement in males. HLA-B27 was found to be positive in 70% of patients and associated with younger mean age, uveitis and shorter time elapsed from symptom to diagnosis. The frequency of HLA-B27 alleles associated with SpA was not different between ankylosing spondylitis patients and healthy controls.

CONCLUSION

Low frequency of HLA-B27 and clinical variations in ankylosing spondylitis may be due to different genetic and/or environmental factors in Turkey.

Ankylosing Spondylitis: A Contemporary Perspective on Diagnosis and Treatment

OBJECTIVES

In recent years, great progress has been made in the development of diagnostic tools, therapeutic approaches, and validated outcome measures in the understanding of the pathogenesis of ankylosing spondylitis (AS). The purpose of this review was to summarize these developments.

METHODS

We performed a PubMed search for the period 1978 to 2005, using the keyword, "ankylosing spondylitis," resulting in a total of 4878 publications, including 778 reviews. Articles were then selected based on their discussion of recent diagnostic tools and new treatment approaches in the pathogenesis of AS, leading to a final total of 104 articles.

RESULTS

In recent years, there have been 2 major developments in the management of AS that make earlier diagnosis possible and offer the hope of alleviating pain and preventing structural changes that result in loss of function. These developments include the use of magnetic resonance imaging to visualize the inflammatory changes in the sacroiliac joint and the axial spine, and the demonstration that tumor necrosis factor blocking agents are highly efficacious in reducing spinal inflammation and possibly in slowing radiographic progression.

CONCLUSIONS

There have been major advances in both the diagnostic tools and the therapeutic regimens available for patients with AS.

Pathogenesis of ankylosing spondylitis: current concepts

More than three decades after the discovery of HLA-B27 as a major genetic clue to the origins of ankylosing spondylitis, much has been learned about pathogenesis. However, the role of this major histocompatibility complex class I allele remains undefined. Studies from animal models have demonstrated that HLA-B27 overexpression can cause inflammatory disease with spondyloarthritis features, and together with investigations of patient-derived material, both innate adaptive and immune responses have been implicated. The gastrointestinal immune response to pathogens and even normal flora, with subclinical or overt inflammation, may play a role as an environmental component of these diseases. Although there has been a large conceptual emphasis on mechanisms involving autoreactive T-cell recognition of HLA-B27 complexes displaying arthritogenic peptides, and more recently non-canonical recognition of abnormal forms of HLA-B27 free of beta(2)m (heavy-chain dimers or monomers), it remains unclear whether immunological recognition plays a role in pathogenesis. The recognition that the HLA-B27 heavy chain misfolds during assembly, and causes endoplasmic reticulum 'stress', has led to the observation that this activates the unfolded protein response. This has opened additional areas of investigation into the response of immune system cells to protein misfolding, and suggested novel alternative concepts that may explain the role of HLA-B27 in pathogenesis. This chapter will discuss available data and current concepts regarding the pathogenesis of ankylosing spondylitis.

Immunogénétique de la spondylarthrite ankylosante

BACKGROUND

Ankylosing spondylitis (AS) is an inflammatory rheumatic disease with axial involvement but its physiopathology remains unexplained. This latter combines genetic and environmental factors as well as an abnormal immune response.

CURRENT TOPICS AND IMPORTANT RESULT

This review addresses the different aspects of AS immunogenetic. A genetic background in AS is suggested by familial cases, concordance rate in twins and transmission of the disease in siblings. Ankylosing spondylitis is strongly associated with the expression of the HLA Class I antigen, B27, but also with other genes not yet identified since currently, only chromosomic area have been linked to AS. Studies of candidate genes or genome screening allow to determine these chromosomic regions. HLA-B27 is directly associated with the disease physiopathology as suggested by animal models of rats transgenic for human HLA-B27 and beta2 microglobulin. This HLA molecule have original biological properties, in particular a slow heavy chain folding and the formation of heavy chain homodimers without light chain. However, HLA B27 is a functional molecule and assumes its property of presenting peptide of 9 amino acids to CD8+ T cells. Interaction modelling studies between HLA B27 and peptides have identified peptide and peptide groove amino acid sequences, with the identification of critical positions on the HLA B27 molecule for the peptide interaction. Original biochemical properties of HLA-B27 include diminished bacterial antigen response and CD4+ T lymphocyte stimulation. Innate immunity is also of interest in AS, as suggested by the presence of macrophage and polymorphonuclear neutrophils in AS synovitis, as well as the contribution of Toll-like receptors.

FUTURE PROSPECTS AND PROJECTS

Thus in AS, the inflammatory process and then the clinical consequences may be explained by the involvement of HLA-B27, a bacterial antigen presentation, an abnormal immune response and the contribution of innate immunity, T CD4+ but also T CD8+ cells. The original molecular structures of HLA-B27 are certainly involved in this complex physiopathology, but their direct influence on the disease remains to be precised.

A high-resolution polymerase chain reaction-sequence-specific primer HLA-B*27 typing set and its application in routine HLA-B27 testing

We designed a set of 35 polymerase chain reaction sequence-specific primers (PCR-SSP) in 29 SSP mixtures to assign 29 HLA-B*27 4-digit level alleles (B*2701-B*2721 and B*2723-B*2730). This was used in conjunction with our 41 PCR-SSP primer mixture low-resolution HLA-B typing set to fully differentiate B*27 from all other HLA-B alleles. Successful typing set validation used 521 B*27 samples covering 13 (B*2701-B*2710 and B*2712, B*2717, B*2723) alleles. The distribution of B*27 alleles was determined in a random population of 4020 local blood donors and the use of PCR-SSP B*27 typing in our routine flow cytometry-based HLA-B27/B2708 typing strategy is described.

Recent progress in ankylosing spondylitis treatment

Ankylosing spondylitis (AS) is a systemic inflammatory rheumatic disease responsible for back pain, stiffness and loss of functional capacity. The therapeutic management of AS includes regular physical exercise together with the use of NSAIDs. Second-line treatments, such as sulfasalazine, are required in cases of NSAID-refractory AS. Some patients have severe and inadequately controlled disease, explaining the need for the development of new treatments. This therapeutic development in AS involves the assessment of new NSAIDs, namely COX2 selective agents and new second-line treatments, such as methotrexate (MTX), pamidronate and anti-TNFalpha agents. Controlled studies are lacking for MTX. Pamidronate showed to be effective in NSAID refractory AS patients in open and controlled trials. Anti-TNFalpha agents (infliximab and etanercept) gave promising results with dramatic improvement of AS symptoms in open and preliminary controlled trials, but further studies are required to evaluate the real long-term effects and tolerability of these drugs.

Ankylosing spondylitis: an overview

Ankylosing spondylitis (AS) is a complex, potentially debilitating disease that is insidious in onset, progressing to radiological sacroiliitis over several years. Patients with symptomatic AS lose productivity owing to work disability and unemployment, have a substantial use of healthcare resources, and reduced quality of life. The pathogenesis of AS is poorly understood. However, immune mediated mechanisms involving human leucocyte antigen (HLA)-B27, inflammatory cellular infiltrates, cytokines (for example, tumour necrosis factor alpha and interleukin 10), and genetic and environmental factors are thought to have key roles. The detection of sacroiliitis by radiography, magnetic resonance imaging, or computed tomography in the presence of clinical manifestations is diagnostic for AS, although the presence of inflammatory back pain plus at least two other typical features of spondyloarthropathy (for example, enthesitis and uveitis) is highly predictive of early AS. Non-steroidal anti-inflammatory drugs (NSAIDs) effectively relieve inflammatory symptoms and are presently first line drug treatment. However, NSAID treatment has only a symptomatic effect and probably does not alter the disease course. For symptoms refractory to NSAIDs, second line treatments, including corticosteroids and various disease modifying antirheumatic drugs, are employed but are of limited benefit. Emerging biological therapies target the inflammatory processes underlying AS, and thus, may favourably alter the disease process, in addition to providing symptom relief.