Human leukocyte antigen-B*2705 is the predominant subtype in the Korean population with ankylosing spondylitis, unlike in other Asians

An immunogenetic investigation of 30 autoimmune and autoinflammatory diseases and their links to psychiatric disorders in a nationwide sample

Autoimmune and autoinflammatory diseases (AIIDs) involve a deficit in an individual's immune system function, whereby the immune reaction is directed against self-antigens. Many AIIDs have a strong genetic component, but they can also be triggered by environmental factors. AIIDs often have a highly negative impact on the individual's physical and mental wellbeing. Understanding the genetic underpinning of AIIDs is thus crucial both for diagnosis and for identifying individuals at high risk of an AIID and mental illness as a result thereof. The aim of the present study was to perform systematic statistical and genetic analyses to assess the role of human leukocyte antigen (HLA) alleles in 30 AIIDs and to study the links between AIIDs and psychiatric disorders. We leveraged the Danish iPSYCH Consortium sample comprising 65 534 individuals diagnosed with psychiatric disorders or selected as part of a random population sample, for whom we also had genetic data and diagnoses of AIIDs. We employed regression analysis to examine comorbidities between AIIDs and psychiatric disorders and associations between AIIDs and HLA alleles across seven HLA genes. Our comorbidity analyses showed that overall AIID and five specific AIIDs were associated with having a psychiatric diagnosis. Our genetic analyses found 81 significant associations between HLA alleles and AIIDs. Lastly, we show connections across AIIDs, psychiatric disorders and infection susceptibility through network analysis of significant HLA associations in these disease classes. Combined, our results include both novel associations as well as replications of previously reported associations in a large sample, and highlight the genetic and epidemiological links between AIIDs and psychiatric disorders.

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.

Spondyloarthritis in North Africa: an update

Spondyloarthritis (SpA) has been less well studied than rheumatoid arthritis in North Africa, due to a belief that it is rare and benign in certain populations. The main genetic trait of SpA is its association with human leukocyte antigen (HLA)-B27. The distribution of this allele largely explains the prevalence and severity of SpA. The prevalence of HLA-B27 in the general population of North Africa is estimated at about 4%, and rises to about 60% among people affected with SpA. Coxitis is one of the main features of North African SpA, but the response to treatment is comparable to the literature from the West. The major challenge in North Africa remains accessibility to specialized care and means of early diagnosis. Prevalent infections in North Africa do not seem to be a major obstacle to optimal treatment strategies.

Baseline extent of damage predicts spinal radiographic progression in Korean patients with ankylosing spondylitis treated with golimumab

BACKGROUND/AIMS

For patients with ankylosing spondylitis (AS), golimumab has consistent efficacy in controlling disease activity over 5 years but its benefit in preventing radiographic progression was less clear at 4 years. To predict radiographic progression, we analyzed the baseline characteristics of AS patients in a Korean population.

METHODS

Sixty-eight Korean patients with AS participated in the phase 3, multicenter, randomized, placebo-controlled, double-blind trial (GO-RAISE) which has previously been described. Baseline modified stoke AS spine score (mSASSS) and change in mSASSS from baseline (ΔmSASSS) until week 208 were analyzed in the Korean patients enrolled in the GO-RAISE study.

RESULTS

Although Korean patients had lower baseline mSASSS compared to non-Korean patients and received active management, radiographic progression was not prevented. Korean patients who did not undergo radiographic progression of spinal lesions of AS were younger and had shorter symptomatic duration, lower Bath AS functional and metrology indices, better chest expansion, and lower baseline mSASSS. The baseline mSASSS and ΔmSASSS were positively correlated in Korean AS patients (p < 0.001). Radiographic progression was more prevalent (80.0%) when baseline mSASSS > 10 and less common (13.0%) with baseline mSASSS = 0.

CONCLUSIONS

In Korean AS patients, radiographic progression of the spine after 4 years was predicted effectively by the initial severity of the spinal lesion(s) in patients treated with golimumab.

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.

Does HLA-B27 Status Influence Ankylosing Spondylitis Phenotype?

The association of HLA-B27 with ankylosing spondylitis (AS) remains as one of the intriguing models that could exist between a molecule and human disease in medicine. Although it was reported in 1973, its contribution to AS and related spondyloarthritis continues to be a major challenge for scientific community. It is important to understand its etiopathogenic mechanism and its functions in these diseases. Although the diagnostic and prognostic roles of HLA-B27 in AS are still debated, there is an increasing interest for HLA-B27–based effects especially in HLA-B27(+) patients with AS. This review will focus in the examination of published reports regarding the influence of HLA-B27 status on the demographic and clinical features in AS, with specific interest to its role on AS severity.

Ankylosing Spondylitis Patients with HLA-B*2704 have More Uveitis than Patients with HLA-B*2705 in a North Chinese Population

PURPOSE

To investigate the correlation between clinical features of ankylosing spondylitis (AS) and different human leukocyte antigen (HLA)-B27 subtypes.

METHODS

We conducted a cross-sectional study of 216 patients with AS. HLA-B27 and its subtypes were detected by polymerase chain reaction with sequence specific primer (PCR-SSP). Clinical features were compared between the different HLA-B27 subtypes. A meta-analysis on uveitis frequencies in AS patients with HLA-B*2705 vs 2704 was performed.

RESULTS

The most prevalent subtypes of HLA-B27 were HLA-B*2704 (66.1%) and HLA-B*2705 (32.2%). There were 57 HLA-B27-positive AS patients with the history of uveitis; 45 were B*2704 and 12 were B*2705. Patients with B*2704 had more uveitis than B*2705 (p = 0.021). After meta-analysis, there was no significant difference in the presence of uveitis between HLA-B*2704 and HLA-B*2705.

CONCLUSIONS

AS patients with B*2704 have a higher risk of uveitis than AS with B*2705 in a north Chinese people.

Flow cytometric human leukocyte antigen-B27 typing with stored samples for batch testing

Background

Flow cytometry (FC) HLA-B27 typing is still used extensively for the diagnosis of spondyloarthropathies. If patient blood samples are stored for a prolonged duration, this testing can be performed in a batch manner, and in-house cellular controls could easily be procured. In this study, we investigated various methods of storing patient blood samples.

Methods

We compared four storage methods: three methods of analyzing lymphocytes (whole blood stored at room temperature, frozen mononuclear cells, and frozen white blood cells [WBCs] after lysing red blood cells [RBCs]), and one method using frozen platelets (FPLT). We used three ratios associated with mean fluorescence intensities (MFI) for HLAB27 assignment: the B27 MFI ratio (sample/control) for HLA-B27 fluorescein-5-isothiocyanate (FITC); the B7 MFI ratio for HLA-B7 phycoerythrin (PE); and the ratio of these two ratios, B7/B27 ratio.

Results

Comparing the B27 MFI ratios of each storage method for the HLA-B27+ samples and the B7/B27 ratios for the HLA-B7+ samples revealed that FPLT was the best of the four methods. FPLT had a sensitivity of 100% and a specificity of 99.3% for HLA-B27 assignment in DNA-typed samples (N=164) when the two criteria, namely, B27 MFI ratio >4.0 and B7/B27 ratio <1.5, were used.

Conclusions

The FPLT method was found to offer a simple, economical, and accurate method of FC HLA-B27 typing by using stored patient samples. If stored samples are used, this method has the potential to replace the standard FC typing method when used in combination with a complementary DNA-based method.

HLA-B27 homozygosity has no influence on radiographic damage in ankylosing spondylitis: Observation Study of Korean spondyloArthropathy Registry (OSKAR) data

OBJECTIVES

To evaluate the influence of homozygosity for HLA-B27 on the radiographic damage in ankylosing spondylitis (AS).

METHODS

A total of 368 AS patients with positive HLA-B27 status from the Observation Study of Korean spondyloArthropathy Registry (OSKAR) cohort were recruited for this study. HLA-B27 positive patients out of all AS patients were assessed for whether they had homozygosity or heterozygosity for HLA-B27. First, all data were stratified in relation to the carrier state of positive HLA-B27 for cross-sectional survey. Then we compared the radiographic damage score between groups. Second, we evaluated collected clinical and radiographic parameters at two different time points. Then we compared radiographic progression between groups. To use the mSASSS, cervical and lumbar spinal radiographs were examined by two experienced bone and joint radiologists (S. Lee, K.B. Joo).

RESULTS

The agreement between the two readers regarding mSASSS was very good: ICC coefficient 0.70 (95% CI 0.60-0.81). The mean age (SD) of the AS patients was 37.0 (9.2) years, and the mean disease duration (SD) was 15.6 (9.1) years. Of these patients, 34.5% (127 patients) had HLA-B27 homozygosity. The mean mSASSS unit (SEM) was not significantly different between groups (homozygosity 28.57±4.12 vs heterozygosity 23.34±3.44, P=0.344) on cross-sectional survey. When it comes to radiographic progression between groups over 5 years, there was no significant difference in spite of adjusting for confounding variable (homozygosity 4.98±0.98 vs heterozygosity 4.21±0.82, P=0.562).

CONCLUSION

The carrier state of positive HLA-B27 plays no role in determining the radiographic progression in AS.

Evaluation of two commercial HLA-B27 real-time PCR kits

BACKGROUND

The standard PCR with sequence-specific primers (SSP) is a widely used method of HLA-B27 typing in clinical practice. The aim of our study was to evaluate 2 Korean HLA-B27 kits with different real-time PCR chemistries.

METHODS

To validate the accuracy of real-time PCR kits, we selected 28 HLA-B27-positive samples and 33 HLA-B27-negative samples with a wide range of different HLA-B specificities typed by standard PCR-SSP. The 2 real-time PCR kits used were the AccuPower HLA-B27 real-time PCR kit (Bioneer, Korea) with TaqMan probes and the Real-Q HLA-B*27 detection kit (BioSewoom, Korea) with SYBR Green I dye for melting curve analysis.

RESULTS

All 61 samples typed by PCR-SSP demonstrated a perfect concordance with the 2 real-time PCR assays. It was possible to clearly discriminate between HLA-B27-positive and -negative samples in both real-time assays.

CONCLUSIONS

In summary, both real-time PCR assays for HLA-B27 were fast, reliable, well-adapted for routine laboratory testing, and attractive alternatives to the conventional PCR-SSP method.

The association of HLA-B*27 subtypes with ankylosing spondylitis in Wuhan population of China

The aim of this study was to investigate the association of the B27 subtypes with ankylosing spondylitis (AS) in the Wuhan population of China. We selected 317 HLA-B27-positive individuals (145 controls and 172 patients with ankylosing spondylitis). The B27 subtypes were characterized using a PCR-SSP method. Six B27 subtypes were determined: B*2702, 03, 04, 05, 06 and B*13. HLA-B*2704 and HLA-B*2705 were the two high frequency genotypes in controls and patients. Compared with the controls, the AS patients had high frequency of B*2704 (patients 69.2% vs. controls 53.8%) and low frequency of B*2705 (patients 23.8% vs. controls 33.1%). B*2703 was detected in 10 (5.8%) patients and in 13 (8.9%) controls. B*2702, 06 and B*2713 were relatively rare. Our results show that the allele conferring risk to AS in the Wuhan population of China was B*2704 and B*2705. B*2704 is strongly associated with AS.