[The role of HLA-B27 in the pathogenesis and diagnosis of axial spondyloarthritis : 50 years after discovery of the strong genetic association]

BACKGROUND

The association of the human lymphocyte antigen B27 (HLA-B27) with ankylosing spondylitis (AS), also now called axial spondylarthritis (axSpA), was first described 50 years ago.

OBJECTIVE

This article gives an overview of the available knowledge on the topic.

MATERIAL AND METHODS

This is a narrative review based on the experience of the authors.

RESULTS

The HLA-B27 is a member of the HLA class I family of genes of the major histocompatibility complex (MHC). The prevalence of HLA-B27 in the central European population is approximately 8 %, i.e., the vast majority of carriers of HLA-B27+ remain healthy. The frequency of HLA-B27 shows a decline from north to south. The HLA-B27 explains only 30 % of the genetic burden of axSpA. The prevalence of the disease correlates with the frequency of HLA-B27 in the population, i.e., there are geographic differences. Approximately 60-90 % of patients with axSpA worldwide are HLA-B27+. Some 200 subtypes of HLA-B27 can be differentiated using the polymerase chain reaction (PCR). In Thailand and Sardinia two subtypes were found that are not associated with axSpA. The physiological function of HLA class I molecules is the defence of the organism against microbes. Microbial peptides are presented to the immune system, which can be specifically attacked by CD8+ T‑cells. Genetic polymorphisms of the enzyme endoplasmic reticulum aminopeptidase 1 (ERAP1), which breaks down peptides in the endoplasmic reticulum, are associated only with HLA-B27+ diseases.

DISCUSSION

The pathogenesis of axSpA is unclear but a major hypothesis is that of the arthritogenic peptides. In this it is assumed that potentially pathogenic foreign or autologous peptides can be presented by HLA-B27. If nothing else, HLA-B27 plays an important role in the diagnosis, classification and determination of the severity of axSpA.

A Review of Laboratory Practices Using the HLA-B27 Survey by the College of American Pathologists: How Important Is Allele-Level Typing?

CONTEXT.—

Ankylosing spondylitis (AS) is an autoimmune disorder with a strong genetic risk, especially with HLA-B27. Clinical testing for HLA-B27 has been used to help diagnose patients with signs and symptoms of AS. Testing methods used by clinical laboratories for HLA-B27 fall into the broad categories of serologic/antibody- or molecular-based methods and have evolved over time. The College of American Pathologists (CAP) offers a proficiency testing survey for HLA-B27.

OBJECTIVE.—

To analyze HLA-B27 testing trends and their performance in the past decade, using the proficiency testing survey data submitted to CAP.

DESIGN.—

We analyzed the HLA-B27 CAP proficiency testing data from 2010 to 2020 for the method used, participant concordance, and error rates. Results from case scenarios to understand evolving scientific data around HLA-B27 risk alleles were also analyzed.

RESULTS.—

Antibody-based flow cytometry is the most common method, though it has decreased from 60% in 2010 to 52% in 2020, with a corresponding increase in molecular methods. Among the molecular methods, real-time polymerase chain reaction has increased from 2% to 15%. Flow cytometry had the highest error rate (5.33%), and sequence-specific oligonucleotide (0%) is the most accurate (0%). Results of case scenarios demonstrated that most participants understood that allele-level HLA-B27 typing results inform clinical interpretation, for example HLA-B*27:06 is not associated with AS.

CONCLUSIONS.—

These data demonstrated the changing trends for HLA-B27 testing during the past decade. HLA-B27 allelic typing provides a better understanding of AS association. This is possible by testing for the second field with methods like next-generation sequencing.

Development and validation of a machine learning-based nomogram for predicting HLA-B27 expression

BACKGROUND

HLA-B27 positivity is normal in patients undergoing rheumatic diseases. The diagnosis of many diseases requires an HLA-B27 examination.

METHODS

This study screened totally 1503 patients who underwent HLA-B27 examination, liver/kidney function tests, and complete blood routine examination in First Affiliated Hospital of Guangxi Medical University. The training cohort included 509 cases with HLA-B27 positivity whereas 611 with HLA-B27 negativity. In addition, validation cohort included 147 cases with HLA-B27 positivity whereas 236 with HLA-B27 negativity. In this study, 3 ML approaches, namely, LASSO, support vector machine (SVM) recursive feature elimination and random forest, were adopted for screening feature variables. Subsequently, to acquire the prediction model, the intersection was selected. Finally, differences among 148 cases with HLA-B27 positivity and negativity suffering from ankylosing spondylitis (AS) were investigated.

RESULTS

Six factors, namely red blood cell count, human major compatibility complex, mean platelet volume, albumin/globulin ratio (ALB/GLB), prealbumin, and bicarbonate radical, were chosen with the aim of constructing the diagnostic nomogram using ML methods. For training queue, nomogram curve exhibited the value of area under the curve (AUC) of 0.8254496, and C-value of the model was 0.825. Moreover, nomogram C-value of the validation queue was 0.853, and the AUC value was 0.852675. Furthermore, a significant decrease in the ALB/GLB was noted among cases with HLA-B27 positivity and AS cases.

CONCLUSION

To conclude, the proposed ML model can effectively predict HLA-B27 and help doctors in the diagnosis of various immune diseases.

Fifty years after the discovery of the association of HLA B27 with ankylosing spondylitis

The human lymphocyte antigen B27 (HLA B27) is a member of the HLA class I family of genes in the major histocompatibility complex whose name goes back to its discovery in studies of transplanted tissue compatibility. Its prevalence in the mid-European population is about 8%. The association of HLA B27 alleles with ankylosing spondylitis (AS), a highly heritable disease, which is part of the spectrum of axial spondyloarthritis (axSpA), was discovered 50 years ago. HLA B27 explains less than 30% of the total genetic load. About 60%-90% of axSpA patients worldwide carry HLA B27. The prevalence of the disease is linked to the frequency of HLA B27 in the population which implies that there are relevant differences. Among the roughly 200 subtypes known there are two which are not disease associated. The function of HLA class I molecules is to present peptides to the immune system to defend the organism against microbes targeted by CD8+T cells. This is much supported by the role of the endoplasmic reticulum aminopeptidase 1 (ERAP 1) in AS, an enzyme that is responsible for the intracellular trimming of peptides, since polymorphisms of this gene are only associated with HLA-B27+ disease. The arthritogenic peptide hypothesis trying to explain the pathogenesis of AS is based on that very immune function assuming that also self peptides can be presented. HLA-B27 also plays an important role in classification, diagnosis and severitiy of axSpA.

Association Between HLA Polymorphisms and Sympathetic Ophthalmia in Han Chinese

PURPOSE

Sympathetic ophthalmia (SO) is considered as an autoimmune disease with unclear mechanisms. This study investigated the relationship between HLA polymorphisms and SO.

METHODS

HLA typing was performed using the LABType reverse SSO DNA typing method. The allele and haplotype frequencies were assessed using the PyPop software. Statistical significance of genotype distributions between 116 patients and 84 healthy individuals (control) was determined using Fisher's exact test or Pearson's chi-squared test.

RESULTS

The SO group had a higher frequency of HLA-DRB1 * 04:05, HLA-DQB1 * 04:01, DRB1 * 04:05-DQB1 * 04:01 haplotype   as compared to the control group (Pc < 0.001 for all).

CONCLUSION

This study revealed that DRB1 * 04:05 and DQB1 * 04:01 alleles, as well as DRB1 * 04:05-DQB1 * 04:01 haplotye could be potential risk factors for SO.

Immunological Control of HIV-1 Disease Progression by Rare Protective HLA Allele

HLA-B57 is a relatively rare allele around world and the strongest protective HLA allele in Caucasians and African black individuals infected with HIV-1. Previous studies suggested that the advantage of this allele in HIV-1 disease progression is due to a strong functional ability of HLA-B57-restricted Gag-specific T cells and lower fitness of mutant viruses selected by the T cells.

Anti-N-methyl-D-aspartate receptor encephalitis associated with chronic myelogenous leukemia, causality or coincidence? A case report

Background

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is the most frequent autoimmune paraneoplastic encephalitis, and is primarily associated with ovarian teratomas. Here, we report the first case of a patient diagnosed with chronic myelogenous leukemia (CML) during the recovery phase of anti-NMDAR encephalitis.

Case presentation

The patient was admitted with fever, headache, and seizures. Brain MRI revealed a cerebrospinal fluid (CSF)-containing arachnoid cyst in the left temporal lobe with no other abnormal signals. EEG showed diffuse background slowing in the delta-theta range. The patient tested positive for anti-NMDAR antibodies in both the serum and CSF. One year after the onset of encephalitis, the patient was referred to the Department of Hematology for extreme leukocytosis. Karyotype analysis showed the presence of Philadelphia chromosome t(9;22)(q34;q11). Quantitative reverse transcriptase PCR analysis further identified BCR/ABL1 fusion transcripts; thus, CML was diagnosed.

Conclusions

To the best of our knowledge, this is the first case of anti-NMDAR encephalitis associated with CML. This report should alert clinicians to consider CML as a malignancy that is possibly associated with limbic encephalitis.

Acute Ischemic Stroke Due to Spontaneous Internal Carotid Artery Dissection in a Human Leukocyte Antigen (HLA) B27 Young Male

Carotid artery dissection is a significant cause of stroke in young patients. Here, we report a 33-year-old male who presented with right homonymous hemianopia and paresthesia of the right side of the body. Magnetic resonance imaging (MRI) of the brain revealed an acute infarct in the left parieto-occipital region. Magnetic resonance angiography (MRA) and duplex ultrasonography (USG) of the neck vessels suggested the left internal carotid artery dissection as the underlying cause. The patient was a known human leukocyte antigen (HLA) B27 and had a history of a previous attack of uveitis. This case report will raise awareness regarding the possible association of HLA B27 with the dissection of neck vessels.

Detection of Human Leukocyte Antigen B27 by Flowcytometry in Patients With Suspected Ankylosing Spondylitis in a Tertiary Care Centre

Introduction Human leukocyte antigen B27 (HLA-B27) is strongly implicated in the pathogenesis of ankylosing spondylitis (AS). Hence, HLA-B27 testing is routinely used in the diagnosis of AS. Objectives We aimed to establish the frequency of HLA-B27 in AS patients by flow cytometry and relate the differences between B27+ and B27- cases to the serum concentrations of rheumatoid arthritis factor (RA), erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP). Methods  The study population included a total of 210 patients who visited the tertiary health care center. The peripheral blood samples obtained from AS patients were subjected to a qualitative two-color direct immunofluorescence method using the HLA-B27/CD3 antibody for the rapid detection of HLA-B27 antigen expression in erythrocyte-lysed whole blood in FACSCalibur flow cytometer (Becton Dickinson, USA). Results Out of 210 AS patients, the distribution of HLA-B27 positivity was observed only in 46 (22%) patients. The remaining 164 patients (78.1%) were negative for HLA-B27. Of the 46 HLA positive patients, 39 (25.34%) were males and only seven (12.5%) were females. In both sexes, HLA-B27 frequency was significantly higher in the age group 21-30 years, followed by 41-50 years. The current study also revealed a significant association between sex and age of onset of HLA‑B27 detection in patients with suspected AS. Disease activity was not significantly correlated with RA, ESR, and CRP. Conclusions The detection of HLA-B27 by flow cytometry proved to be a reliable test in the screening of AS in the Indian population.

Comparison of Clinical Features in HLA-B27 Positive and Negative Patients With Axial Spondyloarthritis: Results From a Cohort of 4,131 Patients

Objective: The aim of our study was to assess the influence of the HLA-B27 status on axial spondyloarthritis (axSpA) in the largest cohort in China.

Methods: An observational, cross-sectional, and analytic study of axSpA patients from the China axSpA database was performed. Demographic and clinical data were compared in terms of the HLA-B27 status. Univariate and multivariate analyses were performed to identify variables related to HLA-B27 presence.

Results: We enrolled 4,131 patients in this study; of those, 36,95 (89.4%) were HLA-B27 positive. In the multivariate analysis, male gender (p < 0.001), younger age (p < 0.001), a disease duration of more than 3 years (p < 0.001), a family history of SpA (p < 0.001), uveitis (p < 0.001), ASDAS-CRP (p < 0.001), and biologic treatment (p < 0.001) were the main variables that were independently related to HLA-B27 presence, whereas a diagnosis delay time >36 months (p < 0.001) and psoriasis (p < 0.001) were independently related to HLA-B27 absence.

Conclusion: In Chinese axial SpA patients, presence of HLA-B27 is associated with the male sex, younger age, longer disease duration, greater family aggregation, and higher frequency of uveitis; absence of HLA-B27 is associated with longer diagnosis delay time and higher frequency of psoriasis.

Combined use of different antibody clones improves the efficiency of human leukocyte antigen B27 detection by flow cytometry

BACKGROUND

Human leukocyte antigen B27 (HLA-B27) is an major histocompatibility complex Class I cell surface antigen that shows strong association with spondylarthropathies. Although polymerase chain reaction (PCR) is the gold standard method for HLA-B27 detection, monoclonal antibodies, and flow cytometric analysis is also frequently used. We aimed to compare the efficiency of two commercially available monoclonal antibody clones and the DuraClone kit that uses simultaneously these clones.

METHODS

Blood samples drawn from 63 patients were analyzed by flow cytometry and PCR. For flow cytometry analysis ABCm3 and FD705 clones were used for flow cytometry as well as the DuraClone Reagent Kit. Results of flow cytometric analysis were confirmed by PCR.

RESULTS

Numbers of false-positive and equivocal samples were high when ABCm3 or FD705 clones were used separately: 34 out of 63 and 27 out of 63, respectively. Simultaneous use of the two antibody clones and pre-selection of CD3+ T cells, in the DuraClone kit, significantly decreased the number of these samples. Using the DuraClone kit, only 11 out of 63 samples were inconclusive. Influence of HLA-B7 expression was detectable in some cases when ABCm3 and FD705 were used separately.

CONCLUSIONS

Our results show that simultaneous use of HLA-B27 monoclonal antibodies and pre-selection of T cells significantly increased the specificity of the flow cytometric assay, however it did not reach the specificity of PCR. Nevertheless, based on our results, performing the PCR test exclusively in equivocal cases by DuraClone kit reduces the burden of PCR assays and the turn-around time.

What Does Human Leukocyte Antigen B27 Have to Do with Spondyloarthritis?

Human leukocyte antigen (HLA) B27 is the key laboratory parameter for axial spondyloarthritis (axSpA). Its prevalence is variable across different geographic zones and ethnicities, and often mirrors the prevalence of axSpA. HLA-B27 plays a role in axSpA physiopathology. It is correlated with spondyloarthritis phenotype with a consistent positive association with family history, early disease onset, shorter diagnostic delay, hip involvement, and acute anterior uveitis. HLA-B27 has a pivotal role in many referral strategies. However, these strategies were developed in European populations and need to be evaluated in populations with lower HLA-B27 background prevalence, and where additional parameters might be needed.

Is axial magnetic resonance imaging useful in early juvenile spondyloarthritis-preliminary report

INTRODUCTION/OBJECTIVES

Magnetic resonance imaging (MRI) is recommended for evaluation of changes in juvenile spondyloarthropathies (JSpA). To our knowledge, there is no previous prospective study analysing early changes on axial MRI. The objective is to investigate incidence of reparable changes on axial MRI in patients with established JSpA, lasting for less than 6 months.

MATERIALS AND METHODS

The pilot study included 27 patients with confirmed diagnosis of JSpA examined within 2 years. Prior to imaging, basic demographic and laboratory data and HLA-B27 were collected. Patients filled out a visual analogue scale for pain and a childhood health assessment questionnaire. A paediatric rheumatologist and a paediatric physiatrist examined patients and measured indices of flexion, extension and sagittal flexibility. Contrast-enhanced axial MRI examination and cervical x-ray were performed. Three experienced paediatric radiologists independently reviewed x-ray and MRI images of all patients.

RESULTS

There was no significant correlation between early changes detected on MRI and other parameters. The study revealed early changes of the cervical spine to be the most common finding. More patients had positive cervical MRI than positive sacroiliac joint (SIJ) MRI. Cervical x-ray and MRI were equally useful for diagnosis regardless of other parameters.

CONCLUSION

Study showed new information on axial involvement, striking cervical spine as the most involved part. The biggest study limitation is the small number of patients. Establishing early JSpA diagnosis is of utmost importance, especially in the light of novel therapy introduced in every day practice. It seems that cervical spine involvement is more represented than previously described in literature, especially in comparison with SIJ. Key Points • Contrast-enhanced MRI is considered the gold standard for detection early changes in JSpA. • Standardization of diagnostic criteria and better classification of changes using the unique scoring system for children are necessary. • It seems that cervical spine involvement is more represented than previously described in the literature, especially in comparison with SIJ involvement.

HLA-B27 prevalence in axial spondyloarthritis patients and in blood donors in a Lebanese population: Results from a nationwide study

AIM

To calculate the prevalence of human leukocyte antigen (HLA)-B27 in axial spondyloarthritis patients (axSpA) compared to blood donors (BD) in Lebanon, to identify the clinical and radiological findings associated with HLA-B27 and to estimate the proportion of patients fulfilling the clinical arm of the Assessment of the Spondyloarthritis International Association (ASAS) criteria.

METHOD

Consecutive Lebanese adult axSpA patients fulfilling the ASAS classification criteria were included from 12 rheumatology clinics across Lebanon. BD served as controls. A binary logistic regression was used to study the association between HLA-B27 and the disease features.

RESULTS

A total of 247 individuals were included (141 axSpA patients and 106 BD). The prevalence of HLA-B27 was 3.8% in BD and 41.1% in axSpA. Overall, 39.7% of the axSpA patients fulfilled the clinical arm of the ASAS classification criteria. Sensitivity of HLA-B27 for axSpA was 41.1%, specificity was 96.2%, positive predictive value was 93.6%, and negative predictive value was 55.13%. Positive likelihood ratio (LR) was 10.9 and negative LR was 1.63. We found a positive association of HLA-B27 with family history of SpA and psoriasis.

CONCLUSION

Our study confirmed a low prevalence of HLA-B27 in axSpA patients and BD in this Lebanese population, However, we found a high specificity and positive LR, as well as the same number of axSpA patients fulfilling the clinical arm of the ASAS criteria as in European studies. HLA-B27 is therefore valuable for identification of axSpA in Lebanese patients despite the overall low prevalence in this population. Our results may guide future evaluations the role of HLA-B27 in planning local referral strategies.

The clinical utility of human leucocyte antigen B27 in axial spondyloarthritis

The association between HLA-B27 and AS was first established in the early 1970s. Since then, our understanding of this disease has changed, such that we now recognize AS to be the extreme of the clinical phenotype within a disease spectrum known as axial SpA (axSpA). Recent advances in therapeutic options have driven the need for earlier diagnosis and many screening strategies have been proposed to facilitate this. In parallel, our understanding of axSpA genetics, and especially the contribution of HLA-B27, has expanded. In this article we will present and discuss the evidence supporting the use of HLA-B27 in clinical practice. We will briefly summarize the evolution of the concept of axSpA, the prevalence of HLA-B27 and axSpA and the potential role of HLA-B27 in the aetiopathogenesis of axSpA and focus on the utility of HLA-B27 in everyday clinical practice.

Role of Human Leukocyte Antigens (HLA) in Autoimmune Diseases

Since the discovery of HLA 60 years ago, it has contributed to the understanding of the immune system as well as of the pathogenesis of several diseases. Aside from its essential role in determining donor-recipient immune compatibility in organ transplantation, HLA genotyping is meanwhile performed routinely as part of the diagnostic work-up of certain autoimmune diseases. Considering the ability of HLA to influence thymic selection as well as peripheral anergy of T cells, its role in the pathogenesis of autoimmunity is understandable. The aim of this paper is to provide a brief overview of the role and current clinical relevance of HLA-B27 in spondyloarthritis and HLA-B51 in Behçet's disease as well as HLA-DQ2/DQ8 in celiac disease and HLA-DRB1 in rheumatoid arthritis and to discuss possible future implications.

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.

Role of Human Leukocyte Antigens (HLA) in Autoimmune Diseases

The aim of this review is to provide a brief overview of the role and current clinical relevance of HLA-B27 in spondyloarthritis and HLA-B51 in Behcet's disease as well as HLA-DQ2/DQ8 in celiac disease and HLA-DRB1 in rheumatoid arthritis and to discuss possible future implications.

Control of HIV-1 by an HLA-B*52:01-C*12:02 Protective Haplotype

HLA-B*52:01-C*12:02, which is found in approximately 20% of all Japanese persons, is well known to be associated with ulcerative colitis and Takayasu arteritis. This haplotype is also known to be protective in individuals infected with human immunodeficiency virus (HIV) type 1. Recent studies showed that HLA-B*52:01-restricted HIV-1-specific T cells suppress HIV-1 and that HLA-C*12:02 together with KIR2DL2 play an important role in natural killer cell-mediated control of HIV-1. However, the role of HLA-C*12:02-restricted cytotoxic T lymphocytes (CTLs) in suppressing HIV-1 replication remains unknown. In the present study, we demonstrated that HLA-C*12:02-restricted CTLs specific for 2 immunodominant epitopes, Pol IY11 and Nef MY9, contributed to the suppression of HIV-1 replication in HIV-1-infected individuals. Further analysis demonstrated that these 2 HLA-C*12:02-restricted CTLs together with 4 HLA-B*52:01-restricted ones effectively suppressed HIV-1 in individuals with the HLA-B*52:01-C*12:02 haplotype. Thus, both HLA-C*12:02 and HLA-B*52:01 alleles contribute to HIV-1 suppression via both HIV-1-specific CTLs and natural killer cells in individuals with this haplotype.

Progress of genome-wide association studies of ankylosing spondylitis

Ankylosing spondylitis (AS) is an immune-mediated arthritis which primarily affects the spine and sacroiliac joints. Significant progress has been made in discovery of genetic associations with AS by genome-wide association studies (GWAS) over past decade. These findings have uncovered novel pathways involved pathogenesis of the disease and have led to introduction of novel therapeutic treatments for AS. In this Review, we discuss the genetic variations associated with AS identified by GWAS, the major pathways revealed by these AS-associated variations and critical cell types involved in AS development.

An Unusual Cause of Myelopathy: Ochronotic Spondyloarthropathy With Positive HLA B27

Ochronosis is a late developing complication of alkaptonuria, a black brownish pigment in the fibrous and cartilaginous tissues. Although most previous studies reported alkaptonuria and back pain due to ochronosis, thoracic myelopathy is an extremely rare complication. In this report, a paraparetic patient who has ochronotic spondiloarthropathy with the presence of HLA B27 antigen is described. He had low back and leg pain and morning stiffness for 5 yrs. Last year, these were followed by tingling, numbness, and weakness the in lower extremities and he was operated on with preliminary diagnosis of prolapsed disc herniation and cord compression. Surgery is suggested for disc herniations related to ochronotic spondyloarthropathy if it is necessary or neurologic symptoms are present. However, his pain and weakness have partially recovered after the operation. After medical and physical treatment, he showed clinically significant improvements. This case report demonstrates that the management of ochronosis needs a multidisciplinary approach with physiologic, neurologic, and psychologic effects and proper treatment may significantly improve functional outcomes in these patients.

Role of HLA-B27 in the pathogenesis of ankylosing spondylitis (Review)

The study of ankylosing spondylitis (AS) has made significant progress over the last decade. Genome-wide association studies have identified and further substantiated the role of susceptibility genes outside the major histocompatibility complex locus. However, human leukocyte antigen (HLA)-B27 has been suggested to be important in the pathogenesis of AS, contributing to ~20.1% of AS heritability. The current review will present the classical and non-classical forms of HLA-B27, as well as their pathogenic roles, and further discuss the hypotheses regarding the potential pathogenesis of AS. In addition, the association between the pathogenic role of HLA-B27 and inflammatory indexes, including the interleukin-23/−17 axis will be investigated to provide novel insights into the pathogenesis of AS. The aim of the present review is to provide an update of the current research into the pathogenesis of AS, and provide a comprehensive description of the pathogenic role of HLA-B27 in AS.

Molecular Mimicry between Chikungunya Virus and Host Components: A Possible Mechanism for the Arthritic Manifestations

Background

Chikungunya virus (CHIKV), a reemerging pathogen causes a self limited illness characterized by fever, headache, myalgia and arthralgia. However, 10–20% affected individuals develop persistent arthralgia which contributes to considerable morbidity. The exact molecular mechanisms underlying these manifestations are not well understood. The present study investigated the possible occurrence of molecular mimicry between CHIKV E1 glycoprotein and host human components.

Methodology

Bioinformatic tools were used to identify peptides of CHIKV E1 exhibiting similarity to host components. Two peptides (A&B) were identified using several bioinformatic tools, synthesised and used to validate the results obtained in silico. An ELISA was designed to assess the immunoreactivity of serum samples from CHIKV patients to these peptides. Further, experiments were conducted in a C57BL/6J experimental mouse model to investigate if peptide A and peptide B were indeed capable of inducing pathology.

Findings

The serum samples showed reactivity of varying degrees, indicating that these peptides are indeed being recognized by the host immune system during CHIKV infection. Further, these peptides when injected into C57BL/6J mice were able to induce significant inflammation in the muscles of C57BL/6J mice, similar to that observed in animals that were injected with CHIKV alone. Additionally, animals that were primed initially with CHIKV followed by a subsequent injection of the CHIKV peptides exhibited enhanced inflammatory pathology in the skeletal muscles as compared to animals that were injected with peptides or virus alone. Collectively these observations validate the hypothesis that molecular mimicry between CHIKV E1 protein and host proteins does contribute to pathology in CHIKV infection.

The outcome of Chikungunya virus infection is usually benign but persistent arthritis has been reported in 10–20% of patients after Chikungunya fever. However, some reports have suggested that similarity between host proteins and viral proteins (molecular mimicry) leads to immune mediated damage. However, this has not been proved conclusively. Therefore, this study was undertaken to identify if molecular mimicry exists between CHIKV and host components. Using various bioinformatics tools we identified common sequences and structural homology between glycoprotein of the virus and two human host tissue proteins- HLA-B27 molecule and a domain of complement C3. Two peptides having homology to these human tissue components were synthesized. These peptides were recognized by antibodies present in serum of CHIKV patients. Experiments were conducted to investigate if the peptides were capable of inducing pathology in an experimental C57BL/6J mouse model. Both the peptides on their own were able to induce significant inflammation in the muscles of C57BL/6J mice similar to that observed in animals that were injected with CHIKV alone. Additionally, animals that were injected initially with CHIKV followed by a subsequent injection of the two CHIKV peptides exhibited increased pathology as compared to animals that were injected with peptides or virus alone.

Reactive Arthritis Caused by Yersinia enterocolitica Enteritis

We report a case of reactive arthritis (ReA) triggered by Yersinia enterocolitica enteritis. A 24-year-old Japanese man developed polyarthritis in the lower limbs. Two weeks prior to these symptoms, he noted diarrhea, right lower abdominal pain and a fever. Y. enterocolitica was not isolated from a stool culture; however, he was diagnosed with ReA based on the colonoscopic findings of a high anti-Y. enterocolitica antibody titer and HLA-B27 antigen positivity. Following treatment with methotrexate and steroids, his arthritis improved. This is the first reported Japanese case of ReA in the English literature after a gastrointestinal infection caused by Y. enterocolitica.

Prevalence, Incidence, and Disease Characteristics of Takayasu Arteritis by Ethnic Background: Data From a Large, Population-Based Cohort Resident in Southern Norway

OBJECTIVE

To study the epidemiology and clinical characteristics of Takayasu arteritis (TAK) in southeast Norway (population 2.8 million).

METHODS

All study area hospital databases were screened to capture every potential TAK case between 1999 and 2012. These cases were manually chart reviewed, and only patients fulfilling either the 1990 American College of Rheumatology classification or the 1995 Ishikawa diagnostic criteria were included.

RESULTS

Inclusion criteria were met by 78 patients (68 female, 10 male). Point prevalence (by 2012) segregated by ethnic origin was 22.0 per 10⁶ (95% confidence interval [95% CI] 17-29) in northern Europeans compared to 78.1 (95% CI 38-152) in Asian whites and 108.3 (95% CI 46-254) in Africans (P < 0.001). The incidence rate increased from 1 to 2 per 10⁶ in the first to last 5-year period of the study (P = 0.03). Northern Europeans were mean age 32.3 years at onset, and 47% had involvement confined to aortic arch branches (angiographic type I), while 24% had extensive type V disease. Mean onset age in Asian and African cases was 20.3 years and 47% had type V disease. Coexisting inflammatory bowel disease was observed in 8% and ankylosing spondylitis in 7%.

CONCLUSION

We report 2-4 times higher population prevalence than previously observed, and the highest prevalence ever found in Norwegians of Asian and African descent. The results support the idea that TAK in northern Europeans is marked by limited arterial involvement and older age at onset.

Molecular mechanism of the susceptibility difference between HLA-B*27:02/04/05 and HLA-B*27:06/09 to ankylosing spondylitis: substitution analysis, MD simulation, QSAR modelling, and in vitro assay

The human leukocyte antigen HLA-B27 is directly involved in the disease pathogenesis of ankylosing spondylitis (AS). HLA-B27 has a high degree of genetic polymorphism, with 105 currently known subtypes; the presence of aspartic acid at residue 116 (Asp116) has been found to play an essential role in AS susceptibility. Here, we systematically investigated the molecular mechanism of the susceptibility difference between the AS-associated subtypes HLA-B*27:02/04/05 and AS-unassociated subtypes HLA-B*27:06/09 to AS at sequence, structure, energetic and dynamic levels. In total seven variable residues were identified among the five studied HLA-B27 subtypes, in which Asp116 can be largely stabilized by a spatially vicinal, positively charged His114 through a salt bridge, while five other variable residues seem to have only a marginal effect on AS susceptibility. We also employed a quantitative structure-activity relationship approach to model the statistical correlation between peptide structure and affinity to HLA-B*27:05, a genetic ancestor of all other HLA-B27 subtypes and associated strongly with AS. The built regression predictor was verified rigorously through both internal cross-validation and external blind validation, and was then employed to identify potential HLA-B*27:05 binders from >20,000 cartilage-derived self-peptides. Subsequently, the binding potency of the top five antigenic peptides to HLA-B*27:05 was assayed in vitro using a FACS-based MHC stabilization experiment. Consequently, two (QRVGSDEFK and LRGAGTNEK) out of the five peptides were determined to have high affinity (BL50 = 5.5 and 15.8 nM, respectively) and, as expected, both of them possess positively charged Lys at the C-terminus.

Is there a common pathogenesis in aggressive periodontitis & ankylosing spondylitis in HLA-B27 patient?

HLA-B27 is having strong association to ankylosing spondylitis (AS) and other inflammatory diseases collectively known as seronegative spondyloarthropathy. In literature, although the evidence for association between AS and periodontitis as well as AS and HLA-B27 are there but the association of aggressive periodontitis in HLA-B27 positive patient with AS are not there. We hypothesize that there may be a common pathogenesis in aggressive periodontitis and ankylosing spondylitis in HLA-B27 patient. A 27-years-old female presented with the features of generalized aggressive periodontitis and difficulty in walking. On complete medical examination, ankylosing spondylitis was diagnosed with further positive HLA-B27 phenotype and negative rheumatic factor. This report may open up a new link to explore in the pathogenesis of aggressive periodontitis.

Anxiety and depression correlate with disease and quality-of-life parameters in Chinese patients with ankylosing spondylitis

AIM

To evaluate the relationship between mental and physical health in Chinese patients with ankylosing spondylitis (AS) and to identify the predictors of psychological status.

METHODS

Patients with AS (n=103) and healthy controls (n=121) were surveyed between 2010 and 2011 (cross-sectional study). The Bath Ankylosing Spondylitis Disease Activity Index, Bath Ankylosing Spondylitis Functional Index, Bath Ankylosing Spondylitis Metrology Index, pain visual analog scale, Health Assessment Questionnaire, revised Self-Rating Anxiety Scale, revised Self-Rating Depression Scale, and Short-Form 36 questionnaire were administered.

RESULTS

The frequency of anxiety and depression in patients with AS was higher than that in healthy controls (P<0.001). Severe disease status and reduced quality of life (QoL) were associated with anxiety and depression. Disease activity and somatic pain were more severe in the anxious and depressed subgroups. Impaired physical functioning (assessed by Bath Ankylosing Spondylitis Functional Index) was higher in the anxious and depressed subgroups, while measures of spinal mobility (assessed by Bath Ankylosing Spondylitis Metrology Index) were not associated with depression. Lower QoL was observed in the depressed subgroup.

CONCLUSION

Low socioeconomic status, lack of health insurance, and fatigue contributed to depression in Chinese patients with AS. These patients may require a psychological care approach that is different from those of other countries.

Genetic determinants of cocaine-associated agranulocytosis

Background

Drug-induced agranulocytosis is a recognized adverse drug event associated with serious infectious complications. Levamisole is an antihelminthic and immunomodulator withdrawn from North American markets in 2005 after reports of agranulocytosis. Previous studies of levamisole, suggest that the human leukocyte antigen (HLA)-B27 confers a genetic predisposition to this adverse drug event. Since 2009, emergency room visits due to agranulocytosis in individuals consuming levamisole-adulterated crack-cocaine have increased.

Methods

We performed a case–control study using a genotyping assay and novel gene chip to test the association between cocaine-associated agranulocytosis (CAA) and HLA-B27 and to identify pharmacokinetic and pharmacodynamic gene variants associated with the phenotype.

Results

Fifty-one CAA cases were identified through a provincial physician reporting system between 2008 and 2011. We examined eight of these cases and 26 matched controls. Genotyping revealed a significant association between HLA-B27 and CAA (odds ratio [OR] 9.2, 95% confidence interval [CI], 1.54–54.6). We also observed a similar association with the HLA-B27 tag single nucleotide polymorphism rs4349859 (OR 9.2, 95% CI 1.5–54.6) and rs13202464 (OR 6.7, 95% CI 1.1–41). Further associations were identified with variants in the ARBCC12 (OR 10.0, 95% CI 2.7–36.8) and CYP11A1 (OR 7.4, 95% CI 2.1–26.6) genes, while a novel protective association was observed with variants in the ARDB1 gene (OR 0.06, 95% CI 0.007–0.46).

Conclusions

We confirmed the association of HLA-B27 with CAA and identified additional susceptibility variants. Health care providers should inform people who are identified as having CAA that it is genetically determined and can recur with continued cocaine use. The severity of infections and subsequent hospitalization, and the risk of recurrence may prompt health-promoting behaviour changes of the affected individuals. These genetic associations warrant the attention of public health and knowledge translation efforts to highlight the implications for susceptibility to this severe adverse drug event.

A close association of autoimmune-mediated processes and autoimmune disorders with chronic myelomonocytic leukemia: observation from a single institution

Chronic myelomonocytic leukemia (CMML), a clonal hematopoietic stem cell disease, may be linked to immune-mediated processes and/or autoimmune disorders (AID), although the exact pathogens are still elusive. We retrospectively analyzed 123 CMML patients in our institution. Twenty-four CMML patients (19.5%) had at least one immune-mediated disorder, most commonly idiopathic thrombocytopenic purpura, gout and psoriasis. Four of these 24 patients (15%) had more than one AID. We found that, in contrast to the general population with a prevalence rate of 3.2-5.2%, newly diagnosed CMML patients demonstrated a high prevalence and variety of immune-mediated processes and/or AID. When we compared the results with those of myelodysplastic syndromes published in the literature, the prevalence of AID in these two groups of patients is similar. Our results also showed that the presence of cytogenetic abnormalities was less in CMML patients with AID (6 of 21; 28.6%) than in those without AID (37 of 94; 39.4%), although there was no statistical significance (p = 0.334). A multicenter large cohort study of CMML with AID is recommended to illustrate the molecular relationship between the two distinct groups.

HLA genotypes and rubella vaccine immune response: additional evidence

Recent population-based studies have demonstrated the genetic heritability of rubella vaccine response and assessed that the HLA system may explain about 20% of the inter-individual variance in humoral immune response to this vaccine. Our earlier studies compared HLA allelic associations with rubella vaccine-specific antibodies between two smaller cohorts of healthy Rochester, MN, children (346 and 396 subjects) after two doses of rubella-containing vaccine. This study found that specific HLA alleles were consistently associated with rubella-specific antibody titers (B*27:05, DPA1*02:01, and DPB1*04:01 alleles). The current study examined HLA associations in an independent larger cohort of 1012 healthy San Diego, CA, subjects (age 19-40 years) after rubella vaccine in order to replicate our previous findings in the Rochester subjects. Two HLA associations of comparable magnitudes were consistently observed between B*27:05 (median NT50 Rochester cohort 48.9, p=0.067; San Diego cohort 54.8, p=0.047) and DPB1*04:01 (median NT50 Rochester cohort 61.6, p<0.001; San Diego cohort 70.8, p=0.084) alleles and rubella virus-neutralizing antibody titers. Additional HLA alleles resulted in consistent effects on IL-6 production in both cohorts, but did not meet criteria for statistical significance. Our data suggest these HLA alleles play a role in rubella vaccine-induced immunity and provide the basis for future studies that may explain the mechanism(s) by which these HLA polymorphisms affect immune responses to rubella vaccine.

Cardiac conduction system abnormalities in ankylosing spondylitis: a cross-sectional study

Background

Cardiac conduction disturbances are common in spondyloarthropathies such as ankylosing spondylitis (AS). Whether their occurrence can be linked to signs and symptoms of rheumatic disease activity is an unsettled issue addressed in this study.

Methods

In this cross-sectional study patients with AS according to modified New York criteria but without psoriasis, inflammatory bowel disease, dementia, pregnancy, other severe diseases such as malignancy and difficulties in answering questionnaires were invited; and 210 participated (120 men), mean age 49 years (SD 13; range: 16–77). Questionnaires, physical examination, ECG, and laboratory tests were performed at the same visit.

Results

Cardiac conduction disturbances were common and diagnosed in 10-33%, depending on if conservative or less conservative predefined criteria were applied. They consisted mostly of 1^st degree atrio-ventricular block and prolonged QRS duration, but one patient had a pacemaker and 7 more had complete bundle branch blocks. Conduction abnormalities were associated mainly with age, male gender and body weight, and not with laboratory measures of inflammation or with Bath Ankylosing Spondylitis Disease Activity Index. Neither were they associated with the presence of HLA B27, which was found in 87% of all patients; the subtype B270502 dominated in all patients.

Conclusions

Cardiac conduction abnormalities are common in AS, but not associated with markers of disease activity or specific B27 subtypes. Even relatively mild conduction system abnormalities might, however, indirectly affect morbidity and mortality.

Immunomodulatory effects of clozapine and their clinical implications: what have we learned so far?

Clozapine remains the drug of choice for treatment resistant schizophrenia, but is associated with potentially life threatening side effects, including agranulocytosis and myocarditis. Immunological mechanisms may be involved in the development of these side effects or in the unique antipsychotic efficacy in subgroups of schizophrenia patients. This systematic review presents the immunomodulatory effects of clozapine from human in vitro and in vivo studies and relates these findings to the developments of adverse and therapeutic effects of clozapine. Several studies confirm the immunomodulatory actions of clozapine, but only few studies investigated their relationship to the unique adverse and therapeutic effects of clozapine. During the first month of clozapine treatment, up to 50% of patients develop fever and flu like symptoms, which is seemingly driven by increased cytokines. Within the same time period, the risk of side-effects with a suspected immunological mechanism peaks. Patients developing fever during the first weeks of treatment should have a thorough physical examination, and measurements of white blood cell count, absolute neutrophil count, ECG, C-reactive protein, creatinine kinase, and troponin to exclude infection, agranulocytosis, myocarditis and neuroleptic malignant syndrome. To what degree the unique antipsychotic efficacy of clozapine in subgroups of schizophrenia patients is related to its immunomodulatory effects has not been studied. Research relating the immunomodulatory actions of clozapine and its early markers to clinically relevant adverse and therapeutic outcomes is hoped to provide new leads for the understanding of the pathophysiology of schizophrenia and aid the development of novel treatment targets.

Bilateral macular thickening in mild unilateral anterior uveitis: is HLA-B27 involved?

BACKGROUND

Macular thickening (MT) without clinically recognized macular edema has been described in anterior uveitis (AU). Although fellow-eyes of patients have been used as controls in several studies, little is known about macular thickness in these eyes. We studied the rate and extent of MT in both AU-affected and quiescent fellow-eyes of phakic AU patients with good visual acuity (VA). We also assessed macular thickness related to HLA-B27 presence and to recurrence, since these issues have been almost unexplored by previous optical coherence tomography (OCT) studies.

METHODS

Patients with AU were prospectively included and macular thickness was measured with OCT initially and on follow up. Macular thickness in patients' affected eyes (n = 30) as well as in their quiet fellow-eyes (n = 28) was compared with eyes of age- and gender matched controls. Inter-ocular differences in macular thickness between AU affected eyes and their fellow-eyes were assessed in patients (n = 28), also in a subgroup with visual acuity ≥ 0.8 (n = 23) by one-sample Student's t-tests. Inter-ocular differences were also assessed related to HLA-B27 presence and related to the status of current AU episode (initial or relapse).

RESULTS

Subclinical MT is present in both quiet fellow-eyes and AU-affected eyes of patients. MT was found in most cases of AU, even in phakic eyes with good VA. There was a larger increase in macular thickness in HLA-B27-positive than in HLA-B27-negative patients. No differences in macular thickness were found between patients with their first AU episode and patients with recurrent episodes.

CONCLUSIONS

MT probably reflects systemic immune-mediated response to the inflammatory disorder in AU, and it is possible that HLA-B27-related factors are involved in the pathogenesis of AU. These observations are in line with and extend the current understanding of the mechanisms behind MT in AU.