The Role of HLA-B27 in Spondyloarthritis

The Efficacy and Safety of Biologics in Treating Ankylosing Spondylitis and Their Impact on Quality of Life and Comorbidities: A Literature Review

Ankylosing spondylitis (AS) is a chronic inflammatory arthritis that affects the axial skeleton, causing intense pain, progressive joint destruction, and a gradual reduction in physical function. Additionally, AS can result in extra-musculoskeletal manifestations including inflammatory bowel disease (IBD), psoriasis, and acute anterior uveitis (AAU) affecting patients' quality of life (QoL). Furthermore, AS association with neurological and cardiovascular events has been documented. With the advent of biologics, treating AS has dramatically changed due to their high efficacy and tolerable safety. Nevertheless, there are differences in traits, including rapidity of onset, long-term efficacy, safety profile, and influence on comorbidities. A better understanding of such traits enables clinicians to make the best decision for each patient, increasing persistence, extending medication survival, enhancing patient satisfaction, and reducing the disease effect of AS. A review of the literature published in English in PubMed and Google Scholar databases from 2010 to 2023 was conducted. All relevant results fitting the scope of the topic were included. In this article, we emphasize biologics' efficacy and safety profile in patients with AS. In addition, we discuss the impact of biologics on comorbidities and health-related quality of life (HRQoL).

[Genetically engineered biological agents in the treatment of uveitis in patients with ankylosing spondylitis (clinical observations)]

The article describes clinical cases with effective use of some genetically engineered biological agents for arresting and preventing uveitis attacks, and discusses the potential usage of tumor necrosis factor (TNF)-alpha inhibitors and interleukin-17 inhibitors in the treatment of uveitis in patients with ankylosing spondylitis.

Prevalence of Temporomandibular Joint Disorders in Patients with Ankylosing Spondylitis: A Cross-Sectional Study

Background

This study sought to investigate which temporomandibular disorders (TMD) can be expected in patients with ankylosing spondylitis (AS) and to determine the combined impact of these conditions on the psychological status, chronic pain, and functional disability.

Material and Methods

A cross-sectional study composed of 30 patients between 18 and 65 years with ankylosing spondylitis was performed. The research protocol considered the evaluation of outcomes related to the ankylosing spondylitis (HLA-B27 antigen, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI) and Health Assessment Questionnaire – Spondylitis (HAQ-S)) and temporomandibular disorders (axis I and II of the Research Diagnostic Criteria for Temporomandibular Disorders – RDC/TMD). Descriptive analyses were applied to express the results.

Results

The sample presented both AS and TMD, most of them (24) were diagnosed with conventional AS (HLA-B27 positive). The BASDAI was scored as 7.70 (2.30) (high activity of AS disease). Functional disability represented by high scores of BASFI [7.00 (2.63)] and HAQ-S [1.79 (0.62)] demonstrates the severe impact of the disease on the daily routine and quality of life. According to RDC/TMD diagnostic criteria, 17 (57%) share the three groups of TMD, and 9 (30%) share two groups of TMD (Group I and III). Over 73% of the volunteers scored high levels of chronic pain (Grade III and IV) associated with a high depression scale score. The sample scored the somatization scale (with and without pain) as severe.

Conclusion

Patients with ankylosing spondylitis presented a high prevalence of temporomandibular disorder, most of them having the degenerative forms of TMJ disease. AS and TMD cause moderate to severe chronic pain and a negative impact on psychological status and functional capacities.

The efficacy of moxibustion and acupuncture therapy for ankylosing spondylitis: A protocol for an overview of systematic reviews and meta-analysis

BACKGROUND

Ankylosing spondylitis is a complex and progressive autoimmune inflammatory disease with a worldwide prevalence ranging up to 0.9%. Several systematic reviews and meta-analyses of traditional Chinese medicine alternative therapies, such as acupuncture or moxibustion, have demonstrated the effectiveness of moxibustion and acupuncture in the treatment of ankylosing spondylitis. However, there is no relevant literature to comprehensively evaluate the evidence. The purpose of this overview is to synthesize and evaluate the reliability of evidence generated in the systematic review (SR) and meta-analysis of moxibustion and acupuncture as a primary or complementary therapy for patients with ankylosing spondylitis.

METHODS

PubMed, EMBASE, the Cochrane Central Register of Controlled Trials, Chinese National Knowledge Infrastructure, Chinese VIP Information, Wanfang Database, and Chinese Biomedical Literature Database were searched for systematic reviews and meta-analysis that review the efficacy of acupuncture or moxibustion as the primary treatment for patients with Ankylosing Spondylitis. The literature published before August 2020 will be selected. Additionally, the relevant SRs and meta-analyses that unpublished or ongoing will be searched in PROSPERO and INPLASY. The methodological guidelines for overviews will be used to review and extract data by 2 reviewers, and their will do it independently. Methodology quality will be analyzed by the assessment of multiple systematic reviews-2and the risk of bias by POBIS. For the included studies, we will adopt the following results as primary evaluation indicators: effective rate, visual analogue scale and bath AS disease activity index. Reviewers will assess the certainty of evidence by Grading of Recommendations Assessment, Development and Evaluation.

RESULTS

The results will be published in a peer-reviewed journal.

CONCLUSION

This overview will provide comprehensive evidence of moxibustion and acupuncture for patients with Ankylosing Spondylitis.

Preliminary Report on Interleukin-22, GM-CSF, and IL-17F in the Pathogenesis of Acute Anterior Uveitis

Purpose:Anterior uveitis is the most common anatomic subset of uveitis. We developed a novel multi-parametric flow cytometry panel to identify immune dysregulation signatures in HLA B27-associated acute anterior uveitis (AAU) and axial spondyloarthritis (AxSpA).Methods: We used fluorescence activated cell sorting to characterize T cell cytokine expression in stimulated T cell subsets from patients with AAU (n = 4) compared to healthy controls (n = 14) or subjects with AxSpA (n = 6).Results: Positive findings among subjects with AAU included a statistically significant increase in stimulated granulocyte-macrophage colony stimulating factor (GM-CSF), IL-17, and IL-22 synthesized by CD8 cells, a trend for stimulated ILC (innate lymphoid cells)-3 cells to synthesize more IL-22 (p = .07), and stimulated MAIT (mucosa associated innate lymphoid cells)-like cells that express the T cell receptor V alpha 7.2 to express IL-17A, IL-17F, and IL-22 in a greater percentage of cells relative to controls. IL-17F, GM- CSF, and IL-22 represent potentially novel targets in AAU.Conclusion: Our report is arguably the first to implicate IL-17F or ILC-3 and MAIT cells in the pathogenesis of AAU.Abbreviations AAU: acute anterior uveitis; AxSpA: axial spondyloarthritis; BASDAI: Bath ankylosing spondylitis disease activity index; CCR: chemokine receptor; DMSO: dimethylsulfoxide; EULAR:European League Against Rheumatism; FACS: fluorescence activated cell sorter; FBS: fetal bovine serum; FSC: orward light scatter; GM-CSF: granulocyte-macrophage colony stimulating factor; HC: healthy control; ILC: innate lymphoid cell; KIR: killer immunoglobulin receptor; MAIT: mucosal associated immune T cell; ND: not detected; NK: natural killer cell; OHSU-Oregon Health & Science University; PBMC: peripheral blood mononuclear cell; SSC: side light scatter; TCR: T cell receptor.

Recent advances on the role of cytotoxic T lymphocytes in the pathogenesis of spondyloarthritis

Spondyloarthritis (SpA) is a chronic inflammatory disorder with complex etiology and pathogenesis. Its pathogenesis likely involves a combination of different factors. These factors include host genetics, environmental triggers, and immune and microbiota dysregulation. One of the strongest genetic associations with SpA is HLA-B27, implicating the involvement of cytotoxic T lymphocytes (CTLs) in SpA pathogenesis. Despite this discovery dating back decades ago, the CTL compartment that underlies SpA inflammation has yet to be fully defined until recently. Indeed, recent published studies support a significant role that CTLs play in contributing to chronic joint inflammation, which is a hallmark of SpA pathology. In this review chapter, we discuss emerging evidence that supports a newfound role of CTLs in SpA pathogenesis. This emerging evidence includes enrichment of CTL-related genes from genome-wide association studies, overrepresentation of pathogenic synovial CTL phenotype, clonal expansion, and immune dysregulation of CTLs. The discoveries of this mounting evidence suggest that CTL homeostasis is altered, and a disrupted adaptive immunity underlies the chronic inflammatory features seen in SpA pathology.

Aberrant antigen processing and presentation: Key pathogenic factors leading to immune activation in Ankylosing spondylitis

The strong association of HLA-B*27 with ankylosing spondylitis (AS) was first reported nearly 50 years ago. However, the mechanistic link between HLA-B*27 and AS has remained an enigma. While 85-90% of AS patients possess HLA-B*27, majority of HLA-B*27 healthy individuals do not develop AS. This suggests that additional genes and genetic regions interplay with HLA-B*27 to cause AS. Previous genome-wide association studies (GWAS) identified key genes that are distinctively expressed in AS, including the Endoplasmic Reticulum Aminopeptidase (ERAP) 1 and ERAP2. As these gene-encoding molecules are primarily implicated in the process of peptide processing and presentation, potential pathological interaction of these molecules with HLA-B*27 may operate to cause AS by activating downstream immune responses. The aberrant peptide processing also gives rise to the accumulation of unstable protein complex in endoplasmic reticulum (ER), which drives endoplasmic reticulum-associated protein degradation (ERAD) and unfolded protein response (UPR) and activates autophagy. In this review, we describe the current hypotheses of AS pathogenesis, focusing on antigen processing and presentation operated by HLA-B*27 and associated molecules that may contribute to the disease initiation and progression of AS.

IL-27 and autoimmune rheumatologic diseases: The good, the bad, and the ugly

The footprint of cytokines is evident in almost every biological process, such as development, as well as the pathogenesis of the different diseases, immune responses to pathogens, etc. These small proteins are categorized into different functional classes; for instance, they can play a pro-inflammatory or anti-inflammatory role in different situations, or they can confer a polarization to the immune system. Interleukin (IL)-27 is a member of the IL-12 family. Antigen-presenting cells are the primary source of IL-27 production, which exerts its effects by bindings to the IL-27 receptor expressed on the surface of target cells. Interaction of IL-27 and IL-27 receptor leads to activation of the JAK-STAT and p38 MAPK signaling pathways. Most studies focused on the inflammatory effects of this cytokine, but gradually anti-inflammatory effects were also revealed for this cytokine, which changed the traditional perception of the function of this cytokine. The functionality of IL-27 in the pathogenesis of rheumatic diseases has been attributed to a double-blade sword. Hence, novel therapeutic approaches have been devised targeting IL-12 family that has been accompanied with promising results. In this review, we focused on the inflammatory and anti-inflammatory properties of IL-27 in different autoimmune rheumatologic diseases and its plausible therapeutic potentials.

[Features of the course of anterior uveitis associated with HLA-B27 antigen]

PURPOSE

To perform comparative analysis of the frequency of various complications of anterior uveitis associated with HLA-B27 antigen in patients with and without spondyloarthritis.

MATERIAL AND METHODS

Retrospective analysis included 189 patients with anterior uveitis (AU) associated with histocompatibility antigen (HLA-B27). The Follow-up period lasted 10 years.

RESULTS

189 patients with AU associated with antigen HLA-B27 were divided into two groups. The first group included 108 patients with various diseases of the spondyloarthritis (SpA) group; the second study group consisted of 81 patient with no signs of SpA. Number of patients with complications was 1.5 times higher in the first group. Complicated cataract, glaucoma, synechiae, myodesopsia occurred significantly more frequently in patients of the first group compared to AU patients of the second group, where idiopathic AU was more prevalent. Cystoid macular edema, corneal degeneration, optic nerve atrophy were observed more often in patients with SpA, but differences between the groups were statistically insignificant. Combination of complications also occurred significantly more often in SpA patients. Comparison of the frequency of AU attacks showed that the amount of uveitis attacks per 100 patient-years was higher in patients with SpA. Mean number of AU attacks per year was also higher in the first study group, but differences between the groups were statistically insignificant.

CONCLUSION

Retrospective analysis of 189 patients with AU associated with HLA-B27 antigen revealed significantly higher frequency of complications, together with more frequent acute episodes in patients with SpA in comparison with patients without it confirming the notion that a systemic inflammatory disease can influence the severity of the course of AU.

Autoimmune aspects of psoriasis: Heritability and autoantigens

Chronic immune-mediated disorders (IMDs) constitute a major health burden. Understanding IMD pathogenesis is facing two major constraints: Missing heritability explaining familial clustering, and missing autoantigens. Pinpointing IMD risk genes and autoimmune targets, however, is of fundamental importance for developing novel causal therapies. The strongest association of all IMDs is seen with human leukocyte antigen (HLA) alleles. Using psoriasis as an IMD model this article reviews the pathogenic role HLA molecules may have within the polygenic predisposition of IMDs. It concludes that disease-associated HLA alleles account for both missing heritability and autoimmune mechanisms by facilitating tissue-specific autoimmune responses through autoantigen presentation.

Does the Microbiome Cause B27-related Acute Anterior Uveitis?

The microbiome is strongly implicated in a broad spectrum of immune-mediated diseases. Data support the concept that HLA molecules shape the microbiome. We provide hypotheses to reconcile how HLA-B27 might affect the microbiome and in turn predispose to acute anterior uveitis. These theories include bacterial translocation, antigenic mimicry, and dysbiosis leading to alterations in regulatory and effector T-cell subsets. Received 31 October 2015; revised 7 January 2016; accepted 8 January 2016; published online 22 March 2016.

Biologic agents in juvenile spondyloarthropathies

The juvenile spondyloarthropathies (JSpA) are a group of related rheumatic diseases characterized by involvement of peripheral large joints, axial joints, and entheses (enthesitis) that begin in the early years of life (prior to 16(th) birthday).The nomenclature and concept of spondyloarthropathies has changed during the last few decades. Although there is not any specific classification of JSpA, diseases under the spondyloarthropathy nomenclature umbrella in the younger patients include: the seronegative enthesitis and arthropathy (SEA) syndrome, juvenile ankylosing spondylitis, reactive arthritis, and inflammatory bowel disease-associated arthritis. Moreover, the ILAR criteria for Juvenile Idiopathic Arthritis includes two categories closely related to spondyloarthritis: Enthesitis-related arthritis and psoriatic arthritis.We review the pathophysiology and the use of biological agents in JSpA. JSpA are idiopathic inflammatory diseases driven by an altered balance in the proinflammatory cytokines. There is ample evidence on the role of tumor necrosis factor (TNF) and interleukin-17 in the physiopathology of these entities. Several non-biologic and biologic agents have been used with conflicting results in the treatment of these complex diseases. The efficacy and safety of anti-TNF agents, such as etanercept, infliximab and adalimumab, have been analysed in controlled and uncontrolled trials, usually showing satisfactory outcomes. Other biologic agents, such as abatacept, tocilizumab and rituximab, have been insufficiently studied and their role in the therapy of SpA is uncertain. Interleukin-17-blocking agents are promising alternatives for the treatment of JSpA patients in the near future. Recommendations for the treatment of patients with JSpA have recently been proposed and are discussed in the present review.

Diagnositic value of pelvic enthesitis on MRI of the sacroiliac joints in enthesitis related arthritis

BACKGROUND

To determine the prevalence and diagnostic value of pelvic enthesitis on MRI of the sacroiliac (SI) joints in enthesitis related arthritis (ERA).

METHODS

We retrospectively studied 143 patients aged 6-18 years old who underwent MRI of the SI joints for clinically suspected sacroiliitis between 2006-2014. Patients were diagnosed with ERA according to the International League of Associations for Rheumatology (ILAR) criteria. All MRI studies were reassessed for the presence of pelvic enthesitis, which was correlated to the presence of sacroiliitis on MRI and to the final clinical diagnosis. The added value for detection of pelvic enthesitis and fulfilment of criteria for the diagnosis of ERA was studied.

RESULTS

Pelvic enthesitis was seen in 23 of 143 (16 %) patients. The most commonly affected sites were the entheses around the hip (35 % of affected entheses) and the retroarticular interosseous ligaments (32 % of affected entheses). MRI showed pelvic enthesitis in 21 % of patients with ERA and in 13 % of patients without ERA. Pelvic enthesitis was seen on MRI in 7/51 (14 %) patients with clinically evident enthesitis, and 16/92 (17 %) patients without clinically evident enthesitis. In 7 of 11 ERA-negative patients without clinical enthesitis but with pelvic enthesitis on MRI, the ILAR criteria could have been fulfilled, if pelvic enthesitis on MRI was included in the criteria. There is a high correlation between pelvic enthesitis and sacroiliitis, with sacroiliitis present in 17/23 (74 %) patients with pelvic enthesitis.

CONCLUSIONS

Pelvic enthesitis may be present in children with or without clinically evident peripheral enthesitis. There is a high correlation between pelvic enthesitis and sacroiliitis on MRI of the sacroiliac joints in children. As pelvic enthesitis indicates active inflammation, it may play a role in assessment of the inflammatory status. Therefore, it should be carefully sought and noted by radiologists examining MRI of the sacroiliac joints in children.

Genetic markers as a predictive tool based on statistics in medical practice: ethical considerations through the analysis of the use of HLA-B(*)27 in rheumatology in France

INTRODUCTION

The use of genetic predictive markers in medical practice does not necessarily bear the same kind of medical and ethical consequences than that of genes directly involved in monogenic diseases. However, the French bioethics law framed in the same way the production and use of any genetic information. It seems therefore necessary to explore the practical and ethical context of the actual use of predictive markers in order to highlight their specific stakes. In this study, we document the uses of HLA-B(*)27, which are an interesting example of the multiple features of genetic predictive marker in general medical practice.

MATERIALS AND METHODS

The aims of this monocentric and qualitative study were to identify concrete and ethical issues of using the HLA-B(*)27 marker and the interests and limits of the legal framework as perceived by prescribers. In this regard, a thematic and descriptive analysis of five rheumatologists' semi-structured and face-to-face interviews was performed.

RESULTS

According to most of the interviewees, HLA-B(*)27 is an "overframed" test because they considered that this test is not really genetic or at least does not have the same nature as "classical genetic tests"; HLA-B(*)27 is not concerned by the ethical challenges of genetic test; the major ethics stake of this marker is not linked to its genetic nature but rather to the complexity of the probabilistic information. This study allows also showing that HLA-B(*)27, validated for a certain usage, may be used in different ways in practice.

DISCUSSION

This marker and its clinical uses underline the challenges of translating both statistical concepts and unifying legal framework in clinical practice. This study allows identifying some new aspects and stakes of genetics in medicine and shows the need of additional studies about the use of predictive genetic markers, in order to provide a better basis for decisions and legal framework regarding these practices.

Update on ankylosing spondylitis: current concepts in pathogenesis

Ankylosing spondylitis is an insidiously progressive and debilitating form of arthritis involving the axial skeleton. The long delay in diagnosis and insufficient response to currently available therapeutics both advocate for a greater understanding of disease pathogenesis. Genome-wide association studies of this highly genetic disease have implicated specific immune pathways, including the interleukin (IL)-17/IL-23 pathway, control of nuclear factor kappa B (NF-κB) activation, amino acid trimming for major histocompatibility complex (MHC) antigen presentation, and other genes controlling CD8 and CD4 T cell subsets. The relevance of these pathways has borne out in animal and human subject studies, in particular, the response to novel therapeutic agents. Genetics and the findings of autoantibodies in ankylosing spondylitis revisit the question of autoimmune vs. autoinflammatory etiology. As environmental partners to genetics, recent attention has focused on the roles of microbiota and biomechanical stress in initiating and perpetuating inflammation. Herein, we review these current developments in the investigation of ankylosing spondylitis pathogenesis.

Fecal calprotectin use in inflammatory bowel disease and beyond: A mini-review

Given the number of inflammatory disorders affecting the gastrointestinal tract directly and indirectly, coupled with the considerable overlap with functional disorders, it is evident that more useful noninvasive diagnostic tests are required to aid with diagnosis. If these tests can also have some utility for individual patient follow-up in terms of disease activity and response to treatment, as well as providing forewarning of disease relapse, it would be extremely useful information for the clinician. One recently described test that may fulfill several of these attributes is based on leakage of a mononuclear cell cytoplasmic protein, calprotectin, along the intestinal tract, which can then be quantified in feces. This has been used to distinguish patients exhibiting symptoms of irritable bowel syndrome from patients with inflammatory bowel disease, with a measure of success greater than with currently used techniques. The present article summarizes the experience with this test used in inflammatory bowel disease, as well as a variety of gastrointestinal disorders.

Increased production of interleukin-17 over interleukin-10 by treg cells implicates inducible costimulator molecule in experimental spondyloarthritis

OBJECTIVE

HLA-B27/human β2 -microglobulin (hβ2 m)-transgenic (B27-transgenic) rats develop an inflammatory disorder resembling spondyloarthritis, with accumulation of proinflammatory Th17 cells. Because Treg cells and Th17 cells have opposing effects in inflammatory disorders, we sought to determine whether biased expansion of Th17 cells could result from altered Treg cell frequency and/or function in B27-transgenic rats.

METHODS

We characterized the phenotype and function of Treg cells from B27-transgenic rats in comparison with those from control rats, by examining their expression of cell surface markers, suppressive activity, cytokine production, and differentiation pattern.

RESULTS

In B27-transgenic rats, the preferential accumulation of CD4+ Teff cells over Treg cells was not associated with a defect in Treg cell differentiation or suppressive activity. The expression of Treg cell markers was similar between B27-transgenic and control rats, with the exception of the inducible costimulator (ICOS) molecule, which was overexpressed in B27-transgenic rats. High levels of ICOS are considered to be a hallmark of Treg cells with heightened suppressive activity and interleukin-10 (IL-10) expression. Paradoxically, the production of IL-10 by Treg cells was reduced in B27-transgenic rats, whereas the production of IL-17 was enhanced. Moreover, the addition of anti-ICOS monoclonal antibodies during Treg cell differentiation in the presence of dendritic cells from B27-transgenic rats reversed this cytokine profile, restoring the balance between IL-10 and IL-17 in Treg cells from B27-transgenic rats.

CONCLUSION

We observed dysregulated production of IL-10 and IL-17 by Treg cells from B27-transgenic rats, which may contribute to disease development. Moreover, our data highlight a key role for ICOS signaling in the generation of imbalanced production of IL-10 and IL-17 by Treg cells in this experimental model of spondyloarthritis.

HLA-B27 subtype oligomerization and intracellular accumulation patterns correlate with predisposition to spondyloarthritis

OBJECTIVE

Mechanisms underlying the striking association of spondyloarthritis (SpA) with the class I major histocompatibility complex molecule HLA-B27 remain poorly understood. SpA-like disease develops spontaneously in B*2705-transgenic rats, in conjunction with high HLA-B27 expression levels. This study was undertaken to examine the effects of increased expression of HLA-B27 alleles that are differentially associated with SpA on oligomerization and intracellular redistribution.

METHODS

HeLa cells were transfected with complementary DNA encoding for HLA-B proteins fused to yellow fluorescent protein and/or Renilla luciferase and harvested at an early phase and a later phase of expression. We monitored HLA-B intracellular trafficking and localization by means of microscopy and live-cell imaging. Bioluminescence resonance energy transfer (BRET) and Western blotting were used to monitor HLA-B oligomerization.

RESULTS

At low expression levels, BRET signals were similarly elevated for all SpA-associated HLA-B27 alleles tested, but were lower for the nonassociated B*2706. Of note, at higher expression levels, HLA-B27 signals remained steady while signal for HLA-B7 decreased sharply, reaching the level observed for B*2706. This was due at least in part to a decreased oligomer proportion without unfolded protein response outbreak. Such differential behavior was not abrogated by proteasome inhibition. With increased expression, all HLA-B proteins accumulated to a high density in cytoplasmic vesicles with labile form and size. The extent of this phenomenon was closely correlated with the level of association with predisposition to SpA.

CONCLUSION

To our knowledge, this is the first report of a correlation between the level of predisposition to SpA conferred by HLA-B27 alleles and their biochemical behavior. These findings open new perspectives for understanding the pathogenicity of HLA-B27.

Reverse interferon signature is characteristic of antigen-presenting cells in human and rat spondyloarthritis

OBJECTIVE

In HLA-B27-transgenic rats, the development of a disorder that mimics spondyloarthritis (SpA) is highly correlated with dendritic cell (DC) dysfunction. The present study was undertaken to analyze the underlying mechanisms of this via transcriptome analysis.

METHODS

Transcriptome analysis of ex vivo-purified splenic CD103+CD4+ DCs from B27-transgenic rats and control rats was performed. Transcriptional changes in selected genes were confirmed by quantitative reverse transcriptase-polymerase chain reaction. A meta-analysis of our rat data and published data on gene expression in macrophages from ankylosing spondylitis (AS) patients was further performed.

RESULTS

Interferon (IFN) signaling was the most significantly affected pathway in DCs from B27-transgenic rats; the majority of genes connected to IFN were underexpressed in B27-transgenic rats as compared to controls. This pattern was already present at disease onset, persisted over time, and was conserved in 2 disease-prone B27-transgenic rat lines. In DCs from B27-transgenic rats, we further found an up-regulation of suppressor of cytokine signaling 3 (which may account for reverse IFN signaling) and a down-regulation of interleukin-27 (a cytokine that opposes Th17 differentiation and promotes Treg cells). The meta-analysis of data on conventional DCs from rats and data on monocyte-derived macrophages from humans revealed 7 IFN-regulated genes that were negatively regulated in both human and rat SpA (i.e., IRF1, STAT1, CXCL9, CXCL10, IFIT3, DDX60, and EPSTI1).

CONCLUSION

Our results suggest that expression of HLA-B27 leads to a defect in IFNγ signaling in antigen-presenting cells in both B27-transgenic rats and SpA patients, which may result in Th17 expansion and Treg cell alteration (as shown in B27-transgenic rats) and contribute to disease pathogenesis.

HLA-B27, but not HLA-B7, immunodominance to influenza is ERAP dependent

Endoplasmic reticulum-associated aminopeptidase-1 (ERAP1) plays a critical role in the processing of peptides prior to binding to MHC class I molecules. In this article, we show for the first time, to our knowledge, that the HLA-B27 immunodominant influenza nucleoprotein (NP) 383-391 epitope is made as an N-terminally extended 14-mer before it is trimmed by ERAP. In the absence of ERAP, there is a significant reduction in the CTL response to the B27/NP383-391 epitope in influenza A (flu)-infected B27/ERAP(-/-) mice. With the use of tetramer staining, the number of naive CD8(+) T cells expressing TCR Vβ8.1 in B27/ERAP(-/-) transgenic mice is significantly lower than that seen in B27/ERAP(+/+) mice. HLA-B27 surface expression in naive and flu-infected B27/ERAP(-/-) mice is also lower than the expression seen for the same allele in naive and flu-infected B27/ERAP(+/+) mice. In contrast, surface expression of HLA-B7 was unaffected by the absence of ERAP in B7/ERAP(-/-) transgenic mice. The B7-restricted NP418-426 CTL response in flu-infected B7/ERAP(-/-) and B7/ERAP(+/+) mice was also similar. These results provide, to our knowledge, the first in vivo demonstration of ERAP functionally influencing host immune response in an HLA allele-specific manner. This principle has relevance to diseases such as ankylosing spondylitis, in which HLA-B27 and ERAP jointly contribute to disease predisposition.

Does the microbiome play a causal role in spondyloarthritis?

The purpose of this study is to review the potential causal role of the microbiome in the pathogenesis of spondyloarthritis. The method used for the study is literature review. The microbiome plays a major role in educating the immune response. The microbiome is strongly implicated in inflammatory bowel disease which has clinical and genetic overlap with spondyloarthritis. The microbiome also plays a causal role in bowel and joint disease in HLA B27/human beta 2 microglobulin transgenic rats. The mechanism(s) by which HLA B27 could influence the microbiome is unknown but theories include an immune response gene selectivity, an effect on dendritic cell function, or a mucosal immunodeficiency. Bacteria are strongly implicated in the pathogenesis of spondyloarthritis. Studies to understand how HLA B27 affects bacterial ecosystems should be encouraged.

Anti–IFN-γ autoantibodies in adults with disseminated nontuberculous mycobacterial infections are associated with HLA-DRB1*16:02 and HLA-DQB1*05:02 and the reactivation of latent varicella-zoster virus infection

Anti–IFN-γ autoantibodies are associated with HLA-DRB1*16:02 and DQB1*05:02.

Molecular control of steady-state dendritic cell maturation and immune homeostasis

Dendritic cells (DCs) are specialized sentinels responsible for coordinating adaptive immunity. This function is dependent upon coupled sensitivity to environmental signs of inflammation and infection to cellular maturation-the programmed alteration of DC phenotype and function to enhance immune cell activation. Although DCs are thus well equipped to respond to pathogens, maturation triggers are not unique to infection. Given that immune cells are exquisitely sensitive to the biological functions of DCs, we now appreciate that multiple layers of suppression are required to restrict the environmental sensitivity, cellular maturation, and even life span of DCs to prevent aberrant immune activation during the steady state. At the same time, steady-state DCs are not quiescent but rather perform key functions that support homeostasis of numerous cell types. Here we review these functions and molecular mechanisms of suppression that control steady-state DC maturation. Corruption of these steady-state operatives has diverse immunological consequences and pinpoints DCs as potent drivers of autoimmune and inflammatory disease.

Markers of intestinal inflammation in patients with ankylosing spondylitis: a pilot study

Introduction

Inflammatory bowel disease (IBD) and ankylosing spondylitis (AS) are similar chronic inflammatory diseases whose definitive etiology is unknown. Following recent clinical and genetic evidence supporting an intertwined pathogenic relationship, we conducted a pilot study to measure fecal calprotectin (fCAL) and IBD-related serologies in AS patients.

Methods

Consecutive AS patients were recruited from a long-term prospectively collected longitudinal AS cohort at Cedars-Sinai Medical Center. Controls were recruited from Cedars-Sinai Medical Center employees or spouses of patients with AS. Sera were tested by ELISA for IBD-associated serologies (antineutrophil cytoplasmic antibodies (ANCA), anti-Saccharomyces cerevisiae antibody IgG and IgA, anti-I2, anti-OmpC, and anti-CBir1). The Bath Ankylosing Spondylitis Disease Activity Index, the Bath Ankylosing Spondylitis Functional Index, and the Bath Ankylosing Spondylitis Radiology Index were completed for AS patients.

Results

A total of 81 subjects (39 AS patients and 42 controls) were included for analysis. The average age of AS patients was 47 years and the average disease duration was 22 years. AS patients were predominantly male; 76% were HLA-B27-positive. Median fCAL levels were 42 μg/g and 17 μg/g in the AS group and controls, respectively (P < 0.001). When using the manufacturer's recommended cutoff value for positivity of 50 μg/g, stool samples of 41% of AS patients and 10% of controls were positive for fCAL (P = 0.0016). With the exception of ANCA, there were no significant differences in antibody levels between patients and controls. Median ANCA was 6.9 ELISA units in AS patients and 4.3 ELISA units in the controls. Among AS patients stratified by fCAL level, there were statistically significant differences between patients and controls for multiple IBD-associated antibodies.

Conclusion

Calprotectin levels were elevated in 41% of patients with AS with a cutoff value for positivity of 50 μg/g. fCAL-positive AS patients displayed higher medians of most IBD-specific antibodies when compared with healthy controls or fCAL-negative AS patients. Further studies are needed to determine whether fCAL can be used to identify and characterize a subgroup of AS patients whose disease might be driven by subclinical bowel inflammation.

The use of ultrasound for the assessment of enthesitis in patients with spondyloarthritis

Seronegative spondyloarthritis (SpA) represents a group of diseases that share certain genetic, clinical, and radiographic features. Enthesitis, inflammation at the site of tendon insertion into the bone, involving both the axial and the peripheral joints, is an important sign of SpA. Clinical diagnosis of enthesitis, however, is neither sensitive nor specific; thus, the diagnosis of enthesitis often relies on typical abnormalities in imaging studies. Due to its low costs and availability, ultrasound is emerging as the preferred technique for detection of enthesitis for both clinical and research purposes. Ultrasonographic features of enthesitis include tendon hypoechogenicity and thickening, calcifications, bone erosions, and Doppler signal. Several semi-quantitative scoring systems have been developed to quantify ultrasonographic abnormalities of the entheses. These methods have been used for early diagnosis and classification of SpA as well as for monitoring response to treatment.

Missing: a diagnostic technique to enumerate antigen-specific T cells

T lymphocytes are responsible for immune responses against pathogens, immune surveillance against cancer and maintenance of tolerance to self. While techniques available to detect antigen-specific T cells have been well described, there is a missing technique in our repertoire. While fluorescent multimers can be used for limited research applications, there is no existing technique suitable for detection of antigen-specific T cells in a diagnostic setting. The absence of such a technology has inhibited the search for "correlates of protection" against infectious, autoimmune or malignant disease. This critical review of existing methods will highlight the limitations of the data on which our current understanding of the immune system is based, in an effort to stimulate development of improved techniques.

A historical perspective of the spondyloarthritis

PURPOSE OF REVIEW

The history of ankylosing spondylitis, the main representative of the spondyloarthritides, is dating back to several thousand years BC and recently proven for medieval skeleton by HLA-B27 typing with modern molecular techniques. In modern time, the history of spondyloarthritis (SpA) is characterized by fluctuation between lumping and splitting. Actually, the recent advent of new classification criteria demands to discuss the consequences and clinical implications in the historical context of the development of the concept of SpA including the controversy of lumping and splitting.

RECENT FINDINGS

The new Assessment of SpondyloArthritis International Society classification criteria for axial and peripheral SpA are primarily developed to provide support for clinical trials with biologicals and other treatment modalities, which intend to cover the whole spectrum, especially early clinical manifestations of spondyloarthritides. New insights into genetics and the evolving etiological role of Chlamydia in SpA including the most recent finding of the effective combination antibiotic therapy are major advances in the evolving history of SpA.

SUMMARY

The concept of SpA is well accepted for the classification, diagnosis, and therapeutic management of a high proportion of individuals with inflammatory rheumatic conditions. For further advances research technologies are now available to enlarge the current body of clinical, immunologic, and genetic studies using pivotal microbiologic research and new antimicrobial therapeutic strategies.

Phenotype of resting and activated monocyte-derived dendritic cells grown from peripheral blood of patients with ankylosing spondylitis

Decreased levels of class II major histocompatibility complex (MHC) expression and impaired formation of immunological synapse by dendritic cells (DCs) of HLA-B27 transgenic rats have been recently demonstrated. The resulting dysfunction of DCs may be implicated in the pathogenesis of the HLA-B27-related disease in transgenic animals. The phenotype of DCs in patients with ankylosing spondylitis (AS) has not been evaluated. Monocyte-derived DCs (MDDCs) were grown from patients with active AS and age-matched healthy volunteers. Surface expression of HLA-DR, co-stimulation molecules CD80, CD86 and CD40, as well as CD83 was assessed by flow cytometry and compared between the groups under 3 conditions: in resting state, after stimulation by lipopolysaccharide (LPS) and after stimulation by LPS in the presence of etanercept, a soluble receptor of tumor necrosis factor α. Lower baseline expression of class II MHC molecules (HLA-DR) was observed by MDDCs grown from AS patients, as compared to healthy subjects. Post-stimulated levels of HLA-DR were comparable in both groups, suggesting greater up-regulation of class II MHC molecules by MDDCs from AS in response to LPS. No difference between groups in the levels of expression of co-stimulation molecules and CD83 was observed. Lower basic expression of class II MHC by the MDDCs grown from patients with AS may be associated with impaired regulation of their activity. Functional studies on DCs from patients with AS are needed to evaluate the integrity of their antigen-presenting function.

Ethnic Influence in Clinical and Functional Measures of Brazilian Patients with Spondyloarthritis

Objective.

Spondyloarthritides (SpA) can present different disease spectra according to ethnic background. The Brazilian Registry of Spondyloarthritis (RBE) is a nationwide registry that comprises a large databank on clinical, functional, and treatment data on Brazilian patients with SpA. The aim of our study was to analyze the influence of ethnic background in SpA disease patterns in a large series of Brazilian patients.

Methods.

A common protocol of investigation was prospectively applied to 1318 SpA patients in 29 centers distributed through the main geographical regions in Brazil. The group comprised whites (65%), African Brazilians (31.3%), and people of mixed origins (3.7%). Clinical and demographic variables and various disease index scores were compiled. Ankylosing spondylitis (AS) was the most frequent disease in the group (65.1%); others were psoriatic arthritis (18.3%), undifferentiated SpA (6.8%), enteropathic arthritis (3.7%), and reactive arthritis (3.4%).

Results.

White patients were significantly associated with psoriasis (p = 0.002), positive HLA-B27 (p = 0.014), and use of corticosteroids (p < 0.0001). Hip involvement (p = 0.02), axial inflammatory pain (p = 0.04), and radiographic sacroiliitis (p = 0.025) were associated with African Brazilian descent. Sex distribution, family history, and presence of peripheral arthritis, uveitis, dactylitis, urethritis, and inflammatory bowel disease were similar in the 3 groups, as well as age at disease onset, time from first symptom until diagnosis, and use of anti-tumor necrosis factor-α agents (p > 0.05). Schober test and thoracic expansion were similar in the 3 groups, whereas African Brazilians had higher Maastricht Ankylosing Spondylitis Enthesitis Scores (p = 0.005) and decreased lateral lumbar flexion (p = 0.003), while whites had a higher occiput-to-wall distance (p = 0.02). African Brazilians reported a worse patient global assessment of disease (p = 0.011). Other index scores and prevalence of work incapacity were similar in the 3 groups, although African Brazilians had worse performance in the Ankylosing Spondylitis Quality of Life questionnaire (p < 0.001).

Conclusion.

Ethnic background is associated with distinct clinical aspects of SpA in Brazilian patients. African Brazilian patients with SpA have a poorer quality of life and report worse disease compared to whites.

HLA class I-associated diseases with a suspected autoimmune etiology: HLA-B27 subtypes as a model system

Although most autoimmune diseases are connected to major histocompatibility complex (MHC) class II alleles, a small number of these disorders exhibit a variable degree of association with selected MHC class I genes, like certain human HLA-A and HLA-B alleles. The basis for these associations, however, has so far remained elusive. An understanding might be obtained by comparing functional, biochemical, and biophysical properties of alleles that are minimally distinct from each other, but are nevertheless differentially associated to a given disease, like the HLA-B*27:05 and HLA-B*27:09 antigens, which differ only by a single amino acid residue (Asp116His) that is deeply buried within the binding groove. We have employed a number of approaches, including X-ray crystallography and isotope-edited infrared spectroscopy, to investigate biophysical characteristics of the two HLA-B27 subtypes complexed with up to ten different peptides. Our findings demonstrate that the binding of these peptides as well as the conformational flexibility of the subtypes is greatly influenced by interactions of the C-terminal peptide residue. In particular, a basic C-terminal peptide residue is favoured by the disease-associated subtype HLA-B*27:05, but not by HLA-B*27:09. This property appears also as the only common denominator of distinct HLA class I alleles, among them HLA-B*27:05, HLA-A*03:01 or HLA-A*11:01, that are associated with diseases suspected to have an autoimmune etiology. We postulate here that the products of these alleles, due to their unusual ability to bind with high affinity to a particular peptide set during positive T cell selection in the thymus, are involved in shaping an abnormal T cell repertoire which predisposes to the acquisition of autoimmune diseases.

Prologue: 2009 Joint Meeting of Spondyloarthritis Research and Therapy Network (SPARTAN) and International Genetics of Ankylosing Spondylitis (IGAS)

In July 2009, a 3-day conference was held in Houston, Texas, USA, by members of several groups: the Spondyloarthritis Research and Therapy Network (SPARTAN); the International Genetics of Ankylosing Spondylitis (IGAS); and interested members of the Pan American League of Associations of Rheumatology (PANLAR). The purpose of this meeting was to bring together physician scientists, clinicians, and educators from around the world who are working together to improve their understanding of spondyloarthritis (SpA). In addition to the annual educational and Fellows sessions for SPARTAN members, the conference included a one-day international meeting dedicated to the role of HLA-B27, along with a series of sessions that summarized advances among various collaborative groups and defined opportunities for future genetic initiatives. This supplement provides a review of the SPARTAN and IGAS meetings.