HLA-B27 subtypes determination in patients with ankylosing spondylitis from Zulia, Venezuela

The Epidemiology and Treatment of Ankylosing Spondylitis in Korea

Ankylosing spondylitis is a chronic inflammatory disorder characterized by inflammation of the axial skeleton and sacroiliac joints and to a lesser extent by peripheral arthritis and the involvement of some extra-articular organs. It is paramount for the provision of effective health care delivery to be familiar with the epidemiologic studies on prevalence, mortality, and disability. Furthermore, there is no systematic arrangement of studies related to the treatment of ankylosing spondylitis in Korea. In this review, we addressed Korean ankylosing spondylitis epidemiological studies related to prevalence, genetic factor especially human leucocyte antigen-B27, extra-articular manifestations, infections, mortality, radiologic progression, child-birth, and quality of life. Furthermore, we reviewed Korean ankylosing spondylitis treatment researches about treatment trend, patients' registration program called The KOrean College of Rheumatology BIOlogics and targeted therapy (KOBIO) registry project, biologics and biosimiliars, complications especially infections, and issues about bony progression. There would be value to further studying the epidemiology and treatment of Korean ankylosing spondylitis.

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.

Targeting inflammatory pathways in axial spondyloarthritis

The triggers and pathogenesis of axial spondyloarthritis (axSpA) are not yet completely understood. However, therapeutic agents targeting tumor necrosis factor-α and interleukin-17 inflammatory pathways have proven successful in suppressing many of the clinical symptoms and signs of axSpA, giving us an indication of which pathways are responsible for initiating and maintaining the inflammation. The mechanisms that eventuate in syndesmophytes and ankyloses are less clear. This review addresses these two critical pathways of inflammation, discussing their nature and these factors that may activate or enhance the pathways in patients with axSpA. In addition, genetic and other markers important to the inflammatory pathways implicated in axSpA are explored, and prognostic biomarkers are discussed. Treatment options available for the management of axSpA and their associated targets are highlighted.

HLA-B27 testing: A journey from flow cytometry to molecular subtyping

BACKGROUND

Determination of HLA-B27 status plays an important role as adjuvant in suspected cases for diagnosis of Ankylosing Spondilytis (AS). Objectives of this study were to evaluate (i) flow cytometry method in comparison with DNA microarray for HLA-B27 typing and (ii) EUROArray HLA-B27 Direct assay for HLA-B27 allele detection along with discrimination of AS/non-AS subtypes in Indian population.

METHODS

A total of 7543 patients with a presumptive clinical diagnosis of AS were referred for screening of HLA-B27. All samples were initially tested by flow cytometry, and based on its findings, 1560 samples were analyzed for the presence of HLA-B27 allele by microarray technology. A subset of samples (n = 200) were further tested by DNA sequencing for identification of HLA-B27 subtypes.

RESULTS

Screening of HLA-B27 by flow cytometry reported 1551 positive (20.56%) and 5556 negative (73.65%) cases. Remaining 436 (5.78%) samples were identified within equivocal zone. Of cases (n = 1560) analyzed by microarray method, 1333 (85.44%) and 227 (14.55%) were detected microarray positive and negative, respectively. DNA sequencing identified HLA-B*27:07 as the predominant subtype among cases showing ex2 positivity by microarray method. Of 200 cases, 20 cases (14 of HLA-B*07 and 6 of HLA-B*37) of HLA-B27 cross-reactive subtypes were also identified.

CONCLUSION

We recommend DNA typing as a complementary tool along with flow cytometry to accomplish successful HLA-B27 phenotype determination. This is the first study among Indian population to evaluate efficacy of EUROArray to detect B27 allele and its potential to indicate the presence of nondisease-associated alleles in Indian population.

Polymorphisms of HLA-A, -B, -Cw and DRB1 antigens in Moroccan patients with ankylosing spondylitis and a comparison of clinical features with frequencies of HLA-B*27

Ankylosing spondylitis (AS) is very often associated with human leukocyte antigen (HLA), particularly HLA-B*27. However, the strength of this association and clinical features may vary in different ethnic groups. Our study aims to assess the distribution of HLA-A, -B, -Cw and DRB1 alleles in Moroccan patients with AS and to compare the clinical features of AS and the frequencies of HLA-B27 in patients from Morocco with other series. Seventy-five patients diagnosed with AS and assessed for clinical manifestations were selected and compared to 100 healthy controls. HLA class I and II antigens were typed by polymerase chain reaction sequence-specific oligonucleotide. HLA-B27 subtypes were studied by polymerase chain reaction amplification with sequence-specific primers. HLA-B27 was found in 64% of patients. It was positively associated with younger age at disease onset, family history, and uveitis while it had a negative association with late onset. Six B*27 subtypes were identified in the AS group. HLA-B*2705 and B*2702 were the most common observed subtypes. Among other HLA genes, a significant increase in the prevalence of HLA-Cw*02 and HLA-DRB*15 was found in AS patients. HLA-B27 is involved in the predisposition of AS in the Moroccan population. HLA-B*2705 and B*2702 were the predominant subtypes supporting previous reports in Caucasian spondyloarthropathies. Other HLA genes, HLA-Cw*02 and HLA-DRB1*15, seem to confer predisposing effect to the disease. However, the lower frequency of HLA-B27 compared to the literature in our study suggests the existence of different genetic and/or environmental factors in Morocco.

One-tube HLA-B27/B2708 typing by flow cytometry using two "Anti-HLA-B27" monoclonal antibody reagents

BACKGROUND

Flow cytometry-based methods are widely used to detect the ankylosing spondylitis-associated HLA-B27/B2708 antigens. However, the generally used "HLA-B27" monoclonal antibodies (moabs) cross-react with many HLA specificities, including the common HLA-B7 antigen. Thus, using two "B27" moabs is highly recommended.

METHODS

The assay used two "HLA-B27" reagents, FITC and PE conjugated, respectively and a PE-Cy5 anti-CD3 antibody. Assay verification used 51 reference subjects possessing B*2705, B*2702, and B*2708 and a range of cross-reactive HLA antigens. A total of 1,006 consecutive patients' samples, referred for "HLA-B27 typing", were assayed alongside our standard flow cytometry method. A further 12 low frequency HLA-B*27 specificities were tested. Samples reacting with one "B27" moab only were B*27 allele typed by PCR using sequence-specific primers.

RESULTS

All patient B27/B2708 positives (28.3%) were identified by our one-tube method which detected B*2705, B*2702, B*2708, and 8/12 other B*27 specificities. It was unaffected by HLA-B7 and other cross-reactive antigens but required a minor adjustment, a reduction in the volume of one of the "B27" moabs used, to avoid detecting a minority of HLA-B57 subjects.

CONCLUSIONS

Our one-tube B27/B2708 assay is simple, robust, uses two "B27" moabs for typing precision and security, does not suffer from interference by HLA-B7 or other cross-reactive antigens and has the obvious advantage of using a single tube per typing.

The interplay between the geographic distribution of HLA-B27 alleles and their role in infectious and autoimmune diseases: a unifying hypothesis

Due to its strong association with Ankylosing Spondylitis and the other Spondyloarthropathies, the HLA-B27 family of alleles and, in particular, the ancestral HLA-B*2705, has been the object of numerous studies. More recently, some novel interesting features have emerged such as the ability of HLA-B27 to confer resistance to the progression of HIV infection and to promote a spontaneous CD8+ T cell-mediated viral clearance of HCV. The co-occurrence of these protective and pathogenic features suggests a common ground, i.e. to promote a more pronounced immune/inflammatory response leading to an effective clearance of some pathogens on one side and to autoimmunity on the other. This might be due to the antigen presenting properties and/or to the co-inheritance of gene variants that contribute to an altered homeostasis in case of microbial infections or tissue injury. The existence of conserved HLA haplotypes have since long been thought to result from a selective pressure by some pathogens that have edited the immune response genes. The peculiar distribution of the ancestor HLA-B*2705 along a latitude-dependent gradient and the opposite distribution of their variants have suggested a correlation with endemic malaria. In this respect, Sardinia, a small Mediterranean island plagued by malaria, represents an interesting laboratory since its population is enriched in conserved HLA haplotypes and several genetic studies have disclosed their correlation with infectious and autoimmune diseases.

Subtypes of HLA-B27: history and implications in the pathogenesis of ankylosing spondylitis

HLA-B27 represents a family of 38 closely related cell surface proteins (encoded by the alleles HLA-B*2701-39) called subtypes of HLA-B27, most of which have evolved from the ubiquitous HLA-B*2705 (specifically the B*27052 allele). HLA-B27 subtypes are largely characterized by nucleotide substitutions (mostly nonsynonymous) in exons 2 and 3 which encode alpha1 and alpha2 domains ofthe peptide binding groove respectively. Table 1 shows the description of sequences of HLA-B27 allele sequences. The subtypes could have arisen from B*2705 by point mutation (B*2703, B*2709, B*2704), gene conversion (B*2701, B*2702, B*2708) and reciprocal recombination (B*2707) B*2706 could have arisen by interlocus gene conversion. Studies from different parts of the world reveal differences in the population distribution.

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.

The study of the extended haplotypes of rare HLA-B*2730 allele using microsatellite loci

The aim of the present study was to compare haplotypes of the most frequent B*27 alleles among Croatians (B*2702 and *2705) and the rare B*2730 allele. For this purpose, 37 families with members carrying human leukocyte antigen (HLA)-B27 were selected. All individuals were analysed for eight microsatellites (Msats): D6S2927, short tandem repeat - MHC class I-related gene (STR_MICA), D6S2793, D6S2811, tumor necrosis factor a (TNFa), tumor necrosis factor d (TNFd), D6S273 and D6S1014, while individuals carrying the HLA-B27 specificity were subtyped. Of 39 analysed haplotypes, 20 individuals had B*2702, 15 subjects were positive for the B*2705 allele, the B*2730 allele was found in three haplotypes from different families, while one individual carried the B*2703 allele. HLA-A3 and -DRB1*16 were shared by all three B*2730 haplotypes. The DRB1*16 allele was also observed in the majority of B*2702 haplotypes (76.5%), while HLA-A3 was, after HLA-A2, the second most frequent HLA-A specificity in B*2702 haplotypes. No such correlation was found for the B*2705 haplotypes. Msat analysis showed that B*2730 haplotypes also share the same allele at all tested Msats. The D6S2927, D6S2793, MICA and TNFd Msats were not useful in distinguishing B*2702 and B*2705 alleles because D6S2927-213bp, STR_MICA-179bp, D6S2793-206bp, D6S2811-83bp and TNFd-130bp were detected in almost all cases. Conversely, for the TNFa, D6S273 and D6S1014 loci, haplotypes carrying B*2702 and B*2730 shared a single Msat allele in the majority of cases (TNFa-113bp, D6S1014-134bp and D6S273-134bp), which was not observed for B*2705 haplotypes. In conclusion, the similarity between B*2702 and B*2730 DNA sequences as well as their sharing of the same haplotypic combinations corroborates the proposed mechanism of B*2730 evolution from B*2702 by interallelic recombination.

Distribution of HLA-B27 Subtypes in Ankylosing Spondylitis in an Israeli Population

BACKGROUND

The aim of this study was to investigate the contribution of the B27 subtypes to ankylosing spondylitis (AS) expression in a group of Jewish patients from Israel and to compare their distribution with that found in Mexican Mestizo patients. Several HLA-B27 alleles have been clearly associated with AS. Among them, B( *)2705 and B( *)2702 are involved in susceptibility in different populations worldwide. The aim of this study was to investigate the associated subtypes in Israel and to compare the results with Mexican Mestizos, who have Semitic genes as part of their ancestry.

METHODS

This is a case/control study that included a group of 24 HLA-B27+ Israeli patients with AS and 51 B27+ healthy subjects, most of them Ashkenazi Jews. The B27 subtypes were characterized using a PCR-SSP method.

RESULTS

Only B( *)2702 and B( *)2705 alleles were present in AS patients. However, their allele frequency was not significantly different from that found in the control group, probably because of the small sample size: B( *)2702 (patients 62.5% vs. controls 41.2%, OR = 2.31) and B( *)2705 (patients 37.5% vs. controls 50.9%). Two additional alleles were present only in the controls in low frequency: B( *)2707(5.9%) and B( *)2701(1.9%). It is clear that the major susceptibility allele in Ashkenazi Jews from Israel is B( *)2702.

CONCLUSIONS

The only allele conferring risk to AS expression in Israeli Jews was B( *)2702, as was previously described in Mexican Mestizos. Populations of Mediterranean ancestry, such as Latin Americans, should be further explored to understand the contribution of ethnicity to the etiopathogenesis of AS.

HLA-B27 polymorphism in Turkish patients with ankylosing spondylitis

The aim of this study was to determine the distribution of human leukocyte antigen (HLA)-B27 subtypes in serologically HLA-B27-positive ankylosing spondylitis (AS) patients and healthy controls from the Turkish population and to compare this with other reports from other populations. We subtyped HLA-B27 in 38 HLA-B27-positive Turkish patients with AS and 47 HLA-B27-positive healthy controls without AS by polymerase chain reaction with specific sequence primers (PCR-SSP). The results demonstrated that: B*2705 was the predominant subtype among both of the patients (71.1%) and controls (68.0%). B*2702 was observed in 26.3% and 32.0% of the patients and controls, respectively. B*2708 subtype was found in 2.6% of the patients but not among the control group. When the distribution of B27 subtypes in Turkish populations was compared with that in other populations, similar frequencies with the Caucasian-Europe groups were noted. However, this should be interpreted carefully because of the small number of individuals in our study.