Finnish HLA studies confirm the increased risk conferred by HLA-B27 homozygosity in ankylosing spondylitis

Prevalence and incidence of uveitis in patients with spondyloarthritis: the impact of the biologics era. Data from the international ASAS-COMOSPA study

OBJECTIVES

Uveitis is a common extra-musculoskeletal manifestation in SpA. The aim of this study was to analyze the prevalence of uveitis in SpA patients, and its association with geographical areas, and to determine whether its incidence differed between before and after the biologics era.

METHODS

ASAS-COMOSPA is a retrospective study that includes patients fulfilling Assessment in SpondyloArthritis International Society (ASAS) SpA classification criteria from 22 countries. The overall prevalence of uveitis was calculated, and factors associated with the onset of a first episode of uveitis were evaluated using a Cox regression. A Log-Rank test was performed to compare the new onset of uveitis in the non-biologics era (SpA onset before 2000) vs biologics era (SpA onset after 2000).

RESULTS

A total of 3984 patients were included. The likelihood of presenting a first uveitis episode increased over time, from a prevalence of 10.5% (95% CI 9.5-11.4%) at the time of the SpA diagnosis to 46.6% (41.6-51.5%) after 30 years since the SpA diagnosis. HLA-B27 positivity, family history of uveitis, peripheral enthesitis, and IBD were associated with higher risk of uveitis. Patients with SpA disease onset after the year 2000 showed a lower prevalence of uveitis compared with those with disease onset before the year 2000 (8.2% vs 25.5%, P <0.01), as well as a lower incidence (2.8 per 100 person-years vs 6.1 per 100 person-years, respectively).

CONCLUSION

In our study, the risk of having suffered from at least one episode of uveitis ranged from 10% at the time of the diagnosis of axial SpA to 47% after 30 years of disease duration. Patients with disease onset after biologic therapy introduction showed a significantly lower prevalence and incidence of first episodes of uveitis.

Decoding human leukocyte antigen Beta-27; its active alleles in Ankylosing Spondylitis and computational insights of potential inhibitors: HLA-B27 in AS; its variants and inhibitors

OBJECTIVES

This study aimed to determine the diverse inborn and adventitious variables that contribute to the rise of Ankylosing Spondylitis (AS) and to elucidate the genotypic study of HLA-B*27 alleles along with sub-alleles and in-silico inhibition of their respective abnormal receptor proteins by natural compounds.

METHODS

Case-control study was piloted. Allele-specific DNA-based HLA typing was performed after DNA extraction. Patient questionnaires and Molecular docking was applied to identify AS prognosis and potential HLA-B*27 inhibitors respectively.

RESULTS

Results revealed a 72.72% prevalence of HLA-B*27 alleles in patients versus 9.09% in controls. Sub-alleles HLA-B*27:02, 04, and 05 were identified in 87.5% of patients but were absent in controls. The chi-square (χ2) values for HLA-B*27 alleles and sub-alleles were significant, with p-values of 0.0024 and 0.0220, respectively. The study found no significant association of AS with gender, age, marital status, or environmental factors, but a strong association with family history of back pain, elevated CRP, ESR, body inflammation, and uveitis. In silico analysis identified Rutin, curcumin, and coumaroylquinic acid as natural compounds with the highest binding affinity to HLA-B27 chains A and F, suggesting their probability to modulate the structure and function of HLA-B27 proteins.

CONCLUSIONS

AS is more prevalent in individuals with family history of backache, uveitis and elevated inflammatory markers, Sub-alleles of HLA-B*27 should be used as diagnostic tools alongside alleles, as they were found only in patients, not in healthy individuals. Furthermore, Rutin, curcumin, and coumaroylquinic acid may temper the function of HLA associated with AS.

Major Histocompatibility Complex Class I and II Allele Frequencies and Disease Associations in Mexicans: A Systematic Review and Meta-Analysis

BACKGROUND

The major histocompatibility complex (MHC) plays a crucial role in immune responses and is associated with disease susceptibility. This study systematically reviews MHC class I and class II allele frequencies and their associations with diseases in the Mexican population from 1979 to 2023.

METHODS

A systematic review following PRISMA guidelines was conducted. Reports were obtained from the Allele Frequency Net Database and PubMed using keywords related to HLA and Mexican populations. A total of 776 reports were screened, and 214 were retained for final analysis. Seventy-six studies comprising allele frequency data from over 20,000 individuals across Mexican states and indigenous communities were analyzed. In addition, over 138 articles were examined to identify alleles associated with various diseases.

RESULTS

The analysis identified 117 alleles whose frequencies varied regionally within Mexico. While DPA1*01, DPB1*04:01, and DQA1*03 were predominant, DRB1*04, DQB1*03, and DQA1*05 were also prominent but variable. Certain alleles, such as A*02, B*35, C*04, and C*07, were relatively common in the population. Numerous disease correlations were uncovered, such as B*27's strong association with spondyloarthropathies. DRB1*15:01 and DRB1*04 conferred an increase in multiple sclerosis, while DRB1*04 may protect against some skin diseases.

CONCLUSION

This review improves the understanding of MHC allele frequencies and disease associations in Mexicans, highlighting genetic diversity. The findings lay the groundwork for future research on genetic predispositions and health outcomes, aiding healthcare strategies in this diverse population. Further studies are needed to address data gaps and refine genetic profiles for targeted medical applications.

Distribution of human leukocyte antigen B27 (HLA-B27) in Slovak patients

BACKGROUND AND OBJECTIVES

HLA-B27 is a genetic marker associated with spondyloarthropathies, particularly ankylosing spondylitis and axial spondyloarthritis. While its prevalence varies across populations, no data exist for Slovak patients. This study aimed to determine HLA-B27 prevalence in Slovak patients with suspected spondyloarthropathies and assess differences by sex and age.

METHODS

A retrospective cohort of 1,614 patients (888 females and 726 males) was analyzed for HLA-B27 status (positive/negative) using reverse hybridisation (HLA-B27 StripAssay). Statistical analyses included Pearson's Chi-square test and non-parametric Mann-Whitney U and Kruskal-Wallis tests for sex- and age-related differences.

RESULTS

HLA-B27 positivity was 20.57%, with a higher proportion in males (23.28%) than females (18.36%, p = 0.0177). The less than 20 age group had the highest absolute number of positive cases (126 cases; 17.80%), while the 21-40 group had the highest relative positivity (119 cases; 29.38%). The lowest positivity was in the more than 61 age group (17 cases; 13.08%), though age distribution differences were not statistically significant (p = 0.7765). Positivity varies across diagnoses, peaking in musculoskeletal (M) and eye disorders (H), where it exceeds 29%.

CONCLUSION

HLA-B27 positivity is strongly associated with rheumatologic and ophthalmologic conditions and exhibits age- and sex-related variability. These findings emphasize the diagnostic significance of HLA-B27 testing in Slovak patients, especially for early detection and management of spondyloarthropathies. Further research on HLA-B27 variability and its clinical implications is needed to optimize diagnostic strategies and patient care.

HLA-B27 and spondyloarthritis: at the crossroads of innate and adaptive immunity

HLA-B*27 confers a strong risk of developing spondyloarthritis (SpA), which includes axial SpA with or without peripheral arthritis, enthesitis, acute anterior uveitis and gastrointestinal inflammation. Although no definitive mechanism has been established to explain the role of this HLA class I protein in the pathogenesis of SpA, three main hypotheses have emerged. First is the idea that self-peptides displayed by HLA-B27 resemble microorganism-derived peptides, leading to the expansion of autoreactive CD8+ T cells that trigger disease. The second and third hypotheses focus on aberrant properties of HLA-B27, including its tendency to form cell-surface dimers that can activate innate killer immunoglobulin-like receptors on CD4+ T helper 17 cells, triggering the production of pathogenic cytokines. HLA-B27 also misfolds in the endoplasmic reticulum, which can activate the unfolded protein response, increasing IL-23 expression and thereby promoting the production of type 17 cytokines. HLA-B27 misfolding in mesenchymal stem cells has also been linked to enhanced bone formation by mesenchymal stem cell-derived osteoblasts, which could contribute to structural damage in axial SpA. In this Review we summarize prevailing ideas about the role of HLA-B27 in SpA, discuss the latest developments as well as the gaps in current knowledge, and provide recommendations for future research to address these unmet needs.

The Limitation of HLA Diversity as a Risk Factor for Pediatric-Onset Autoimmune Rheumatic Disease

Background: HLA homozygosity of specific alleles at a single locus is associated with increased risk for autoimmunity and/or more severe clinical phenotypes. However, the contribution of the overall limitation of HLA diversity across multiple loci to autoimmunity risk remains to be determined. Methods: We conducted a proof-of-concept case-control study of 413 individuals (279 cases with pediatric-onset autoimmune rheumatic diseases, 134 matched controls) examining the "Limitation of HLA Diversity" (LoHLAD) across multiple loci as an allele-independent risk factor for autoimmunity. We examined the association of LoHLAD with pediatric-onset autoimmune rheumatic diseases at five HLA loci (A, B, DQB1, DRB1, DRB3/4/5). LoHLAD was defined as (1) homozygosity at any of the examined loci, and/or (2) the presence of a single allele or the complete lack of an allele at the HLA-DRB3/4/5 locus. Results: The frequency of LoHLAD at any locus was significantly higher in cases compared to controls (65.95% vs. 30.60%, OR 4.39 [2.82-6.84], p < 0.0001). Higher frequencies of LoHLAD in cases compared to controls were observed at both class I (19.35% vs. 10.45%, OR 2.06 [1.10-3.86], p = 0.031) and class II (54.48% vs. 20.15%, OR 4.74 [2.92-7.69], p < 0.0001) loci. Specifically, significant differences between cases and controls were observed at the B (OR 8.63 [1.14-65.55], p = 0.016), DQB1 (OR 3.34 [1.27-8.78], p = 0.016), and DRB3/4/5 (OR 4.64 [2.77-7.75], p < 0.0001) loci. Multiple logistic regression models confirmed the ability of LoHLAD to positively predict autoimmunity. Conclusions: LoHLAD is a significant allele-independent risk factor for pediatric-onset autoimmune rheumatic disease.

Fast, Present and Future of the Concept of Spondyloarthritis

PURPOSE OF REVIEW

Axial spondyloarthritis (axSpA) is a rather prevalent chronic inflammatory rheumatic disease that affects already relatively young patients. It has been known better since the end of the nineteenth century but quite a lot has been learned since the early 60ies when the first classification (diagnostic) criteria for ankylosing spondylitis (AS) were agreed on. I have been part of many developments in the last 30 years, and I'm happy to have been able to contribute to the scientific progress in terms of diagnosis, imaging, pathophysiology and therapy. When I was asked to write a manuscript about the SpA concept I felt honored. Thus, the purpose of this extensive review was, on the one hand, to describe the history of AS and axSpA, and on the other hand, to reason about the concept and the gestalt of axSpA, and finally to deliver some ideas what future researchers could possibly do to further study the disease.

RECENT FINDINGS

The last 3 decades were full of innovations for both, classification and treatment of axSpA which also helped us to learn about the pathophysiology. Thus, TNFa, IL-17, IL-23 and Janus kinase are established targets to reduce inflammation. IL-17 and IL-23 are very special in that regard because they both work for psoriasis but only anti-IL-17 agents which don't work in IBD are approved for axSpA, while IL 23 inhibitors are approved for both, psoriasis and IBD, but they don't work in axSpA. New imaging techniques such as low dose CT and synthetic MRI are likely to improve the detection of both active and structural lesions of axSpA. This manuscript tries to describe the most important findings about axSpA. The main aim of research remains to discover the pathophysiology and to further improve treatment options in order to reduce and abolish inflammation and prevent new bone formation to increase the quality of life of our patients. The differences between male and female disease and the role of the immune system in axSpA are now the main challenges, and the role of special T-cell receptors seem to deserve special interest.

The Impact of HLA-A29 Homozygosity and of the Second HLA-A Allele on Susceptibility and Severity of Birdshot Chorioretinitis

Purpose

HLA-A29 is the main susceptibility factor for birdshot chorioretinitis (BSCR). Our study assessed the impact of the second HLA-A allele alongside HLA-A29 on BSCR severity and susceptibility, focusing on HLA-A29 homozygous patients and those with alleles from the HLA-Aw19 group.

Methods

We included 120 additional cases to our previous analysis of 286 patients with BSCR, all HLA-A29 positive. Patients were categorized based on the second allele being also HLA-A29 (A29/nonA29 vs. A29/A29) or belonging to the HLA-Aw19 family, including A29, A30, A31, and A33 (A29/nonAw19 vs. A29/Aw19). HLA-A32 was analyzed separately (A29/nonA32 vs. A29/A32). The prevalence of these groups among patients with BSCR was compared with their frequencies in a sample of 151,997 French subjects. Disease severity was approximated by assessing disease onset and visual function at the last visit and was compared between patient groups.

Results

When comparing the HLA-A29-positive patients with BSCR to HLA-A29-positive French subjects, we found an overrepresentation of HLA-A29 for the second HLA-A allele (χ² = 4.34; P = 0.037; odds ratio, 1.57; confidence interval, 1.01-2.44). Within the HLA-Aw19 broad antigen family, HLA-A32 was found to be under-represented (χ² = 6.15; P = 0.013; odds ratio, 0.40; confidence interval, 0.19-0.85). The nature of the second HLA-A allele did not impact disease severity.

Conclusions

Homozygosity for HLA-A29 increased the risk of developing BSCR without affecting disease severity. The under-representation of HLA-A32 in patients with BSCR suggests a potential protective role.

Complex Interactions between the Human Major Histocompatibility Complex (MHC) and Microbiota: Their Roles in Disease Pathogenesis and Immune System Regulation

The relationship between microbiota and the immune system is complex and characterized by the ways in which microbiota directs immune function interactions, both innate and acquired and also keeps activating the immune system throughout an individual's life. In this respect, the human Major Histocompatibility Complex (MHC, referred to as HLA in humans) plays a crucial role and is also established in self-defense against microbes by presenting microbial-derived peptides to the immune cells. However, this assumption has some unclear aspects that should be investigated. For example, how is the microbiota shaped by microbe species diversity, quantity and functions of the immune system, as well as the role and molecular mechanisms of the HLA complex during this process. There are autoimmune diseases related to both HLA and specific microbiota changes or alterations, many of which are mentioned in the present review. In addition, the HLA peptide presenting function should be put in a framework together with its linkage to diseases and also with HLA compatibility necessary for transplants to be successful. These are still quite an enigmatically statistical and phenomenological approach, but no firm pathogenic mechanisms have been described; thus, HLA's real functioning is still to be fully unveiled. After many years of HLA single-genes studies, firm pathogenesis mechanisms underlying disease linkage have been discovered. Finally, microbiota has been defined as conformed by bacteria, protozoa, archaea, fungi, and viruses; notwithstanding, endogenous viral sequences integrated into the human genome and other viral particles (obelisks) recently found in the digestive mucosa should be taken into account because they may influence both the microbiome and the immune system and their interactions. In this context, we propose to integrate these microbial-genetic particle components into the microbiome concept and designate it as "microgenobiota".

[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.

HLA-B*27 and Ankylosing Spondylitis: 50 Years of Insights and Discoveries

PURPOSE OF REVIEW

To commemorate the 50th anniversary of the groundbreaking discovery of a remarkably strong association between HLA-B*27 and ankylosing spondylitis (AS).

RECENT FINDINGS

In addition to HLA-B*27, more than 116 other recognized genetic risk variants have been identified, while epigenetic factors largely remain unexplored in this context. Among patients with AS who carry the HLA-B*27 gene, clonally expanded CD8 + T cells can be found in their bloodstream and within inflamed tissues. Moreover, the α and β chain motifs of these T-cell receptors demonstrate a distinct affinity for certain self- and microbial-derived peptides, leading to an autoimmune response that ultimately results in the onset of the disease. These distinctive peptide-binding and presentation characteristics are a hallmark of the disease-associated HLA-B*27:05 subtype but are absent in HLA-B*27:09, a subtype not associated with the disease, differing by only a single amino acid. This discovery represents a significant advancement in unraveling the 50-year-old puzzle of how HLA-B*27 contributes to the development of AS. These findings will significantly accelerate the process of identifying peptides, both self- and microbial-derived, that instigate autoimmunity. This, in return, will pave the way for the development of more accurate and effective targeted treatments. Moreover, the discovery of improved biomarkers, in conjunction with the emerging technology of electric field molecular fingerprinting, has the potential to greatly bolster early diagnosis capabilities. A very recently published groundbreak paper underscores the remarkable effectiveness of targeting and eliminating disease-causing T cells in a HLA-B*27 patients with AS. This pivotal advancement not only signifies a paradigm shift but also bolsters the potential for preventing the disease in individuals carrying high-risk genetic variants.

Drug switching in axial spondyloarthritis patients in Germany - a social listening analysis

Background

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease which primarily affects the axial skeleton resulting in chronic back pain and stiffness. According to the guideline, the first-line treatment includes non-steroidal anti-inflammatory drugs (NSAIDs), conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) and non-pharmacological treatment. Second line treatment involves biological disease-modifying antirheumatic drugs (bDMARDs) such as tumour necrosis factor and interleukin-17 inhibitors.

Objectives

The aim of this social media listening research project was to analyse switches of medication and the reasons thereof to gain valuable insights into real-life journeys of patients suffering from axSpA.

Methods

Publicly available posts in German-speaking disease-specific forums were scanned for disease-specific keywords and commonly used drugs by axSpA patients on the Permea platform. Posts containing at least two key words were selected and switches between medications were manually labelled. A total of 287 scraped posts between 01 July 2010 and 04 Feb 2022 were analysed.

Results

The largest group of described medication switches was initially using bDMARDs. Switches to a different bDMARD, termination of medication and switches to glucocorticoids were most frequently named. Patients on NSAIDs switched to glucocorticoids, a different NSAID or bDMARD, whereas patients on csDMARDs most frequently changed to bDMARDs. In all medication groups the main reason for switching was insufficient efficacy and side effects. Additionally, for the medication groups bDMARDs, csDMARDs and corticosteroids, pregnancy and lactation were given as a reason for switching, whereas patients in the NSAID group never mentioned pregnancy and breastfeeding as a reason for switching treatment.

Conclusion

Our analysis shows medication switches based on real-life patient experiences shared with peers in a social listening setting. We also show medication switches differing from advised guidelines. Gathering real-life insights into patients' journey dealing with chronic diseases allows us to understand, and thereby improve patient care and treatment.

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.

Factors Associated With Adverse Outcomes in Uveitis Related to Spondyloarthritis: Development of an Outcome Score (SpA-U)

BACKGROUND

Evaluating the efficacy and refractoriness to treatment and determining factors associated with adverse outcomes in uveitis associated with spondylarthritis (SpA) are complicated by the lack of validated outcome measures.

OBJECTIVES

The aims of this study were to develop an outcome score SpA-U in patients with uveitis associated with SpA and to determine factors associated with adverse outcomes in patients with uveitis under systemic treatment.

METHODS

The outcome score SpA-U was defined by best-corrected visual acuity, anterior chamber inflammation, macular edema and inflammation of posterior chamber, global assessment, and refractoriness to treatment. Factors associated with adverse outcomes in uveitis were studied using linear regression. For categorical factors, marginal averages and their SEs are displayed together with linear regression coefficients with 95% confidence intervals. For continuous factors, averages and SDs are reported in addition to linear regression coefficients with 95% confidence interval. Two regression coefficients are reported for each variable: unadjusted and adjusted for age at diagnosis and sex.

RESULTS

One hundred ninety-seven uveitis outbreaks were included. Sixty-two uveitis outbreaks (31%) were classified as severe, 42 as moderate (21%), and 93 as mild (47%) based on the definition and construction of outcome score. The results of the linear regression model revealed that the uveitis activity was more severe in patients with smoking history ( β = 0.34), axial and peripheral involvement ( β = 0.43), Ankylosing Spondylitis Disease Activity Score >2.1 ( β = 0.45), positive HLA-B27 ( β = 0.29), female sex ( β = 0.19), patients with C-reactive protein elevation ( β = 0.002), and bilateral ocular involvement ( β = 0.32). At the same time, shorter disease evolution ( β = -0.02) was associated with less severe uveitis activity.

CONCLUSION

We have determined factors associated with adverse outcomes in patients with uveitis associated with SpA by developing an outcome score SpA-U that integrates ocular inflammatory activity, visual acuity, global assessment, and refractoriness to treatment.

Conventional Synthetic Disease-Modifying Anti-Rheumatic Drugs and the Risk of Vascular Dementia in Patients with Spondyloarthritis: A Database Cohort Study

Axial spondyloarthritis (axSpA) is a chronic inflammatory rheumatic disease that mainly affects the axial bones, and dementia is characterized by a decline in cognitive function, leading to dependence in everyday activity. Although the association between dementia and ankylosing spondylitis has been investigated, the influence of axSpA medication on dementia risk is unclear. The aim of this study was to investigate the risk of dementia among axSpA patients and if the conventional synthetic disease-modifying anti-rheumatic drugs (csDMARDs) can reduce the risk of dementia. Patients with axSpA whose data were recorded during 2004-2008 and who were followed up until the end of 2010 were recruited. A control cohort was matched by age and sex. A Cox multivariate proportional hazards model was applied to analyze the risk factors for dementia. The hazard ratio (HR) and adjusted HR (aHR) were estimated between the study and control cohorts. The effects of csDMARDs and steroid use on the risk of different types of dementia were also analyzed. In total, 2341 and 11,705 patients constituted the axSpA and control cohort, respectively. The axSpA cohort had a greater risk of vascular dementia (aHR = 2.09 (1.36-3.20). The risk of dementia (aHR = 1.01 (0.55-1.85) did not significantly differ between patients with axSpA who received csDMARDs. In conclusion, patients with axSpA are at a risk of vascular dementia, which could be reduced by csDMARDs.

Immunogenetic Predisposition to SARS-CoV-2 Infection

Herein, we included 527 individuals from two Hospitals, Chemnitz and University-Hospital Leipzig. In total, 199 were negative for PCR and 328 were positive upon first admission. We used next generation sequencing for HLA-A, B, C, DRB1, DRB345, DQA1, DQB1, DPA1, and DPB1, and in some cases, HLA-E, F, G, and H. Furthermore, we molecularly defined 22 blood group systems comprising 26 genes and 5 platelet antigen genes. We observed a significant enrichment of homozygosity for DQA/DQB in the positive group. Within the negative subjects, HLA-B*57:01, HLA-B*55:01, DRB1*13:01, and DRB1*01:01 were enriched, and in the positive group, homozygosity for DQA/DQB, DRB1*09:01, and DRB1*15:01 was observed. DQA1*01:01, DQA1*02:01, and DQA1*01:03 were enriched in the negative group. HLA-DQB1*06:02 was enriched in the positive group, and HLA-DQB1*05:01 and HLA-DQB1*06:03 were enriched in the negative group. For the blood group systems MNS, RH, LE, FY, JK, YT, DO, and KN, enrichment was seen in both groups, depending on the antigen under observation. Homozygosity for D-positive RHD alleles, as well as the phenotypes M-N+ of the MNS blood group system and Yk(a-) of the KN system, were enriched in the positive group. All of these significances disappeared upon correction. Subjects who carried homozygous HPA-1a were more frequent in the negative group, contrasting with the finding that HPA-1ab was enriched in the positive group.

Recurrence of axial spondyloarthritis among first-degree relatives in a prospective 35-year-follow-up family study

Objective

The lifetime recurrence rate (RR) of axial spondyloarthritis (axSpA) among first-degree relatives (FDR) and the effect of proband’s gender, HLA-B27 and radiographic status is unclear. Our 35-year-follow-up family study has enabled these issues to be addressed.

Methods

In 1985, 363 ankylosing spondylitis (AS) probands (members of the Swiss AS Patient Society) and 806 FDR recruited into the study, completed questionnaires regarding axSpA manifestations, underwent a physical examination and most also underwent pelvic radiography and HLA-B27 typing. At follow-up in 2018–2019, of the former participants whose current addresses could be retrieved, 162 had died and 485 (125 patients with AS plus 360 FDR) completed a postal questionnaire.

Results

At follow-up, 48 of 177 HLA-B27(+) FDR had developed axSpA, an RR of 27.1% (95% CI 20.6% to 33.7%). 27/148 (18.2%) children of AS probands (modified New York (mNY) criteria) were affected versus 2/50 (4.0%) children of non-radiographic axSpA probands (p=0.0138, OR=5.36; 95% CI 1.23 to 23.40). Children of female probands were more often affected (12/22; 54.5%) than of male probands (15/78; 19.2%) (p=0.0003; OR=4.89; 95% CI 1.96 to 12.23). This increased risk applies equally to sons and daughters.

Conclusion

The lifetime RR of axSpA for HLA-B27(+) FDR is substantial (27.1%), and disease severity (as defined by radiographic sacroiliitis by the mNY criteria) is an additional risk factor. Affected mothers pass on the disease significantly more often to their offspring than do affected fathers. These findings may lead to better assessment of lifetime risk for axSpA in the offspring. Moreover, investigation of this gender effect may uncover additional putative disease susceptibility factors.

Spondyloarthritides: Theories and beyond

Spondyloarthritides (SpA) are a family of interrelated rheumatic disorders with a typical disease onset ranging from childhood to middle age. If left untreated, they lead to a severe decrease in patients' quality of life. A succesfull treatment strategy starts with an accurate diagnosis which is achieved through careful analysis of medical symptoms. Classification criterias are used to this process and are updated on a regular basis. Although there is a lack of definite knowledge on the disease etiology of SpA, several studies have paved the way for understanding plausible risk factors and developing treatment strategies. The significant increase of HLA-B27 positivity in SpA patients makes it a strong candidate as a predisposing factor and several theories have been proposed to explain HLA-B27 driven disease progression. However, the presence of HLA-B27 negative patients underlines the presence of additional risk factors. The current treatment options for SpAs are Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), TNF inhibitors (TNFis), Disease-Modifying Anti-Rheumatic Drugs (DMARDs) and physiotherapy yet there are ongoing clinical trials. Anti IL17 drugs and targeted synthetic DMARDs such as JAK inhibitors are also emerging as treatment alternatives. This review discusses the current diagnosis criteria, treatment options and gives an overview of the previous findings and theories to clarify the possible contributors to SpA pathogenesis with a focus on Ankylosing Spondylitis (AS) and enthesitis-related arthritis (ERA).

Bidirectional relationship between temporomandibular disorder and ankylosing spondylitis: a population-based cohort study

OBJECTIVES

This study aimed to determine the relation between temporomandibular disorder (TMD) and ankylosing spondylitis (AS) bidirectionally and ascertain the important comorbidities for AS occurrence in TMD patients.

MATERIALS AND METHODS

We conducted this population-based cohort study through Longitudinal Health Insurance Database, Taiwan. Study 1 investigated the risk of TMD in AS patients. Study 2 assessed the risk of AS in TMD patients.

RESULTS

In total, 3204 AS patients and 12,816 age-matched and gender-matched comparisons were enrolled in study 1. The TMD incidence in the AS cohort was 2.88-fold higher when compared with the comparisons (1.54 vs. 0.53 per 10,000 person-years). After adjusting for age, gender, and comorbidity, the AS cohort had a 2.66-fold (95% CI = 1.79-3.97) increased risk of TMD occurrence (P < 0.0001). The second study recruited 4998 TMD patients and 19,991 age-matched and gender-matched comparisons. Both TMD and comparison cohorts showed similar AS risk (HR = 1.49, 95% CI = 0.91-2.43, P = 0.1108) in the adjusted model. Study 2 identified a 3.66-fold increased risk of AS occurrence in TMD patients with comorbidity, including parapsoriasis, rheumatoid arthritis, osteoporosis, Cushing's syndrome, and climacteric arthritis (P < 0.012).

CONCLUSIONS

AS appears to significantly impact the occurrence of TMD. TMD might play a synergic role in AS development.

CLINICAL RELEVANCE

Clinicians have to be vigilant about the increased risk of TMD in AS patients and take care of AS disease activity and prognosis. The symptoms and signs of TMD could be a predictor of AS in patients with the aforementioned comorbidities.

Younger age of onset and uveitis associated with HLA-B27 and delayed diagnosis in Thai patients with axial spondyloarthritis

To identify characteristics associated with HLA-B27, and to identify factors associated with delayed diagnosis in Thai patients with axial spondyloarthritis (axSpA). This cross-sectional study included Thai patients were diagnosed with axSpA by a rheumatologist at Siriraj Hospital. Clinical data were collected. Regression analyses were employed to identify factors associated with study outcomes. Of total 177 patients, 127 (72%) were positive HLA-B27. Uveitis [Odds ratio (OR) 4.0], age at onset of the first musculoskeletal symptom of ≤ 28 years [OR 3.5], female [OR 0.4], and psoriasis [OR 0.4] were significantly associated with HLA-B27 in multiple regression analysis. Those with positive HLA-B27 had less spinal flexibility. Elevated C-reactive protein (p = 0.012) was associated with shorter delay in diagnosis, while uveitis (p < 0.001) and younger age at onset of the first symptom (p = 0.002) were associated with longer delay in diagnosis in multiple regression analysis. Younger age at onset of the first musculoskeletal symptom and uveitis were associated with HLA-B27 and delayed diagnosis in axSpA patients. Young people with musculoskeletal symptom and uveitis should be referred to a rheumatologist to rule out or make a timely diagnosis of axSpA.

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.

Biomarker development for axial spondyloarthritis

The term axial spondyloarthritis (axSpA) encompasses a heterogeneous group of diseases that have variable presentations, extra-articular manifestations and clinical outcomes, and that will respond differently to treatments. The prototypical type of axSpA, ankylosing spondylitis, is thought to be caused by interaction between the genetically primed host immune system and gut microbiota. Currently used biomarkers such as HLA-B27 status, C-reactive protein and erythrocyte sedimentation rate have, at best, moderate diagnostic and predictive value. Improved biomarkers are needed for axSpA to assist with early diagnosis and to better predict treatment responses and long-term outcomes. Advances in a range of 'omics' technologies and statistical approaches, including genomics approaches (such as polygenic risk scores), microbiome profiling and, potentially, transcriptomic, proteomic and metabolomic profiling, are making it possible for more informative biomarker sets to be developed for use in such clinical applications. Future developments in this field will probably involve combinations of biomarkers that require novel statistical approaches to analyse and to produce easy to interpret metrics for clinical application. Large publicly available datasets from well-characterized case-cohort studies that use extensive biological sampling, particularly focusing on early disease and responses to medications, are required to establish successful biomarker discovery and validation programmes.

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.

Patients with Axial Spondyloarthritis Are at Risk of Developing Adhesive Capsulitis: Real-World Evidence Database Study in Taiwan

Patients with axial spondyloarthritis (ax-SpA) present with inflammation invading the axial skeleton. Symptoms of ax-SpA interfere with patients' quality of life, and peripheral symptoms are also noted. Human leukocyte antigen B27 was associated with adhesive capsulitis. However, epidemiological studies investigating the associated incidence and risk factors for patients with ax-SpA with adhesive capsulitis are limited. The data of patients with ax-SpA were recorded during the 2004-2008 period and followed to the end of 2010. The control cohort comprised age- and sex-matched non-ax-SpA subjects. A Cox multivariate proportional hazards model was applied to analyze the risk factors for adhesive capsulitis. The hazard ratio (HR) and adjusted hazard ratio (aHR) were estimated between the study and control cohorts after confounders were adjusted for. Effects of sulfasalazine (SSZ), methotrexate (MTX), and hydroxychloroquine (HCQ) use on adhesive capsulitis risk were also analyzed. We enrolled 2859 patients with ax-SpA in the study cohort and 11,436 control subjects. A higher incidence of adhesive capsulitis was revealed in the ax-SpA cohort: The crude HR was 1.63 (95% CI, 1.24-2.13; p < 0.001), and the aHR was 1.54 (95% CI, 1.16-2.05; p = 0.002). For patients with ax-SpA using SSZ or HCQ, no difference in aHR was noted compared with control participants, but patients with ax-SpA treated with MTX had higher HR and aHR than controls. Patients with ax-SpA are at risk for adhesive capsulitis. When these patients receive SSZ or HCQ, the risk of adhesive capsulitis can be lowered compared with that of the control cohort.

HLA associations in inflammatory arthritis: emerging mechanisms and clinical implications

Our understanding of the mechanisms underlying HLA associations with inflammatory arthritis continues to evolve. Disease associations have been refined, and interactions of HLA genotype with other genes and environmental risk factors in determining disease risk have been identified. This Review provides basic information on the genetics and molecular function of HLA molecules, as well as general features of HLA associations with disease. Evidence is discussed regarding the various peptide-dependent and peptide-independent mechanisms by which HLA alleles might contribute to the pathogenesis of three types of inflammatory arthritis: rheumatoid arthritis, spondyloarthritis and systemic juvenile idiopathic arthritis. Also discussed are HLA allelic associations that shed light on the genetic heterogeneity of inflammatory arthritides and on the relationships between adult and paediatric forms of arthritis. Clinical implications range from improved diagnosis and outcome prediction to the possibility of using HLA associations in developing personalized strategies for the treatment and prevention of these diseases.

Optimization of HLA-B*27 ALLELE Genotyping by PCR-SSP

OBJECTIVES

HLA-B27 is strongly associated with ankylosing spondylitis (AS) and its presence helps to confirm AS diagnosis. Due to the high HLA polymorphism and the differentiated contribution of alleles and molecules encoded by them, HLA-B*27 allele identification is relevant in the clinical follow-up, diagnosis, and treatment of this spondyloarthropathy. Inexpensive genotyping techniques with high specificity and sensitivity are of great interest in histocompatibility laboratories. This work aimed to optimize HLA-B*27 genotyping by Polymerase Chain Reaction Sequence-specific Primer (PCR-SSP), which is an accessible and inexpensive technique.

METHODS

The PCR-SSP was standardized using 26 HLA-B*27 positive and 3 HLA-B*27 negative samples previously defined by Polymerase Chain Reaction Sequence-specific Oligonucleotide Probes (PCR-SSOP) (medium resolution, One Lambda®) and primers described by Duangchanchot et al. (2009). For validating the technique, 397 samples were genotyped using PCR-SSP as well as PCR-SSOP.

RESULTS

The PCR-SSP technique was standardized for identifying the alleles HLA-B*27:02, HLA-B*27:CAFRW (05/13/16/17/28/37/38/39/42), HLA-B*27:CAFRZ (08/26/40), HLA-B*27:09 and HLA-B*27:12, which were found in 90 positive samples (22.67%). There was 100% agreement between the two techniques for heterozygous samples; however, two homozygous samples could not be detected by PCR-SSP.

CONCLUSION

The HLA-B*27 genotyping using PCR-SSP, an easy-to-use, specific, and affordable technique, was optimized for heterozygous samples. This technique may contribute to AS diagnosis.

Treat to Target in Axial Spondyloarthritis

This article discusses treat-to-target strategies in axial spondyloarthritis and current status. Treatment ranging from nonsteroidal anti-inflammatory drugs to biologic and other disease-modifying drugs is discussed in the context of treat-to-target. The article explores evidence from landmark randomized, controlled trials and observational studies focusing on both radiographic and nonradiographic axial spondyloarthritis. The feasibility of treat-to-target, as well as predictors of remission are addressed in line with existing evidence. Finally, issues around management principles and challenges, as well as unmet need in the field, are highlighted.

Targeting inflammatory pathways in axial spondyloarthritis

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

Association Between Human Leukocyte Antigen-B*27 and Pathogenesis in Seronegative Spondyloarthropathies in Federation of Bosnia and Herzegovina

Objectives

This study aims to investigate the low-resolution human leukocyte antigen (HLA)-B locus polymorphisms between unrelated healthy individuals and patients with diagnosis of seronegative spondyloarthropathies and determine risky and protective allelic groups and genotypes.

Patients and methods

The study included 104 healthy control individuals (52 males, 52 females; median age 43 years; range 2 to 76 years) and 96 patients (43 males, 53 females; median age 28.5 years; range 2 to 67 years) diagnosed with: ankylosing spondylitis (AS) (n=19), reactive arthritis (n=19), psoriatic arthritis (n=28) and undifferentiated spondyloarthropathies (n=30). Genomic deoxyribonucleic acid was extracted from peripheral blood to detect allelic groups of HLA class I and II. Single-specific-primer polymerase chain reaction was used for HLA genotyping and visualization of products after their separation on 1.5% agarose gel for horizontal gel electrophoresis.

Results

Significantly increased frequency was found for HLA-A*02 and HLA-B*27 allelic variants in all groups of patients. The increased frequency of the HLA-B*35 allelic group in the control group represents the protective gene variant for the occurrence of AS. The predisposing genotype (HLA-B*27/B*44 and B*27/B*51) for the onset of disease was only found in AS patients.

Conclusion

This study shows the strong association of HLA-B*27 antigen with spondyloarthropathies, which is considered a risk variant of the gene for the onset of disease. Protective and risky allelic variants and genotypes are rare and their detection as well as increased frequency are possible if larger numbers of patients are involved.

Preventive effect of tumor necrosis factor inhibitors versus nonsteroidal anti-inflammatory drugs on uveitis in patients with ankylosing spondylitis

To compare the preventive effect of tumor necrosis factor (TNF) inhibitors (anti-TNF antibody and soluble TNF receptor fusion protein (TNFR)) and nonsteroidal anti-inflammatory drugs (NSAIDs) on uveitis in patients with ankylosing spondylitis (AS). This retrospective cohort study included all AS patients (n = 1055) who have been treated with either TNF inhibitor or NSAIDs at the Seoul National University Hospital from 2004 to 2016. Treatment episodes of each patient were assigned to anti-TNF antibody (n = 517), TNFR (n = 341), and NSAID (n = 704) groups. The incidence of uveitis in each group was compared using a Cox proportional hazard model. The incidence rates of uveitis before and after initiation of TNF inhibitors were also assessed. A propensity score-matched (PSM) comparison was performed for a sensitivity analysis. Uveitis was significantly less common in the anti-TNF antibody group than the NSAID group (adjusted hazard ratio (HR) 0.53; 95% confidence interval (CI) 0.29-0.96) while it was higher in the TNFR group (adjusted HR 2.25, 95% CI 1.43-3.53). Anti-TNF antibody further reduced the incidence of uveitis when prescribed with NSAIDs (combination therapy) (adjusted HR 0.39; 95% CI 0.19-0.79). Combination therapy was preventive in AS patients with a history of uveitis (adjusted HR 0.31; 95% CI 0.12-0.81), but not in those without history of uveitis. The incidence rate of uveitis fell from 6.36 to 2.60 per 100 person-years when anti-TNF antibody was added to NSAIDs. Anti-TNF antibody plus NSAIDs reduces the risk of uveitis to a greater extent than NSAIDs alone in AS patients with a history of uveitis. Combination therapy may be an effective secondary prevention measure.

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

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

Quantifying the genetic risk for the development of axial spondyloarthropathy: could this become a diagnostic tool?

PURPOSE OF REVIEW

To assess the utility of recent genetic findings in ankylosing spondylitis (AS) and axial spondyloarthropathy (SpA) in relation to diagnostic testing, prognosis and responses to biologic treatment and the development of new therapies.

RECENT FINDINGS

AS and other forms of SpA are polygenic with more than 100 genes contributing to disease susceptibility. The role of genes in determining the outcome of the disease and response to treatment is less clear. Here, we review some of the progress that has been made over the past decade in understanding the genetic contribution to these diseases and how this may be used to inform the development of new treatments. In those with a high pretest probability of SpA human leukocyte antigen (HLA)-B27 testing can increase the posttest predictive value to almost 100% in some cases. There are currently no reliable genetic predictors of disease severity or response to treatment.

SUMMARY

The utility of HLA-B27 as a diagnostic tool when coupled with careful clinical assessment is well established but other genetic markers probably have relatively little to add. In contrast, novel drug targets are likely to be identified from genetic association studies.

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.

Does HLA-B27 Status Influence Ankylosing Spondylitis Phenotype?

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

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.

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.

Ankylosing Spondylitis: HLA-B*27-Positive Versus HLA-B*27-Negative Disease

PURPOSE OF REVIEW

We review our current knowledge about the clinical features of patients with ankylosing spondylitis (AS) who possess HLA-B*27 versus those who lack this gene.

RECENT FINDINGS

ERAP1 association is present only in HLA-B*27+ patients, but other genetic associations are similar between the two groups. A genetic study supports the existence of an HLA-B27-independent common link between gut inflammation and AS. It is unusual to observe familial occurrence of primary AS among families of northern European extraction that show no segregation of HLA-B*27, psoriasis, or IBD. Although there are many similarities among AS patients possessing HLA-B*27 versus those lacking this gene, the former group has a younger age of onset, a shorter delay in diagnosis, a better clinical response to tumor necrosis factor inhibitors, a greater familial occurrence, a greater risk for occurrence of acute anterior uveitis, and a lower risk for occurrence of psoriasis and IBD. ERAP1 association is present only in HLA-B*27+ patients, but other genetic associations are similar between the two groups. It is unusual to observe occurrence of primary AS among families of northern European extraction that show no segregation of HLA-B*27, IBD, or psoriasis. A recent genetic study supports the existence of an HLA-B*27-independent common link between gut inflammation and AS.

Genetics and the Causes of Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a common inflammatory arthritis in which genetic factors are the primary determinants of disease risk and severity. Substantial progress has been made in identifying genetic pathways involved in the disease, and in translating those discoveries to drug discovery programs. Recently discovered novel disease pathways include those involved in control of DNA methylation, bacterial sensing, and mucosal immunity. Additional pathways are likely to be identified as a higher proportion of the genetic risk of AS is determined.

Axial spondyloarthritis

The term axial spondyloarthritis covers both patients with non-radiographic and radiographic axial spondyloarthritis, which is also termed ankylosing spondylitis. The disease usually starts in the third decade of life with a male to female ratio of two to one for radiographic axial spondyloarthritis and of one to one for non-radiographic axial spondyloarthritis. More than 90% heritabilty has been estimated, the highest genetic association being with HLA-B27. The pathogenic role of HLA-B27 is still not clear although various hypotheses are available. On the basis of evidence from trials the cytokines tumour necrosis factor (TNF)-α and interleukin-17 appear to have a relevant role in pathogenesis. The mechanisms of interaction between inflammation and new bone formation is still not completely understood but clarification will be important for the prevention of long-term structural damage of the bone. The development of new criteria for classification and for screening of patients with axial spondyloarthritis have been crucial for the early indentification and treatment of such patients, with MRI being the most important existing imaging method. Non-steroidal anti-inflammatory drugs and TNF blockers are effective therapies. Blockade of interleukin-17 is a new and relevant treatment option.

Golimumab in refractory uveitis related to spondyloarthritis. Multicenter study of 15 patients

OBJECTIVE

To assess the efficacy of golimumab (GLM) in refractory uveitis associated to spondyloarthritis (SpA).

METHODS

Multicenter study of SpA-related uveitis refractory to at least 1 immunosuppressive drug. The main outcome variables were degree of anterior and posterior chamber inflammation, visual acuity, and macular thickness.

RESULTS

A total of 15 patients (13 men/2 women; 18 affected eyes; mean age 39 ± 6 years) were evaluated. The underlying SpA subtypes were ankylosing spondylitis (n = 8), psoriatic arthritis (n = 6) and non-radiographic axial SpA (n = 1). The ocular involvement patterns were recurrent anterior uveitis in 8 patients and chronic anterior uveitis in 7. Before GLM they have received methotrexate (n = 13), sulfasalazine (n = 6), pulses of methylprednisolone (n = 4), azathioprine (n = 3), leflunomide (n = 2), and cyclosporine (n = 1). Overall, 10 of them had also been treated with TNF-α blockers; etanercept (n = 7), adalimumab (n = 7), infliximab (n = 6), and certolizumab (n = 1). GLM was given at the standard dose (50mg/sc/monthly) as monotherapy (n = 7) or in combination with conventional immunosuppressive drugs (n = 8), mainly methotrexate. Most patients had rapid and progressive improvement of intraocular inflammation parameters. The median number of cells in the anterior chamber at 2 years [0 (0-0)] was significantly reduced compared to baseline findings [1 (0-3); p = 0.04]. The mean best corrected visual acuity value also improved (0.84 ± 0.3 at 2 years versus 0.62 ± 0.3 at baseline; p = 0.03). Only minor side effects were observed after a mean follow-up of 23 ± 7 months.

CONCLUSIONS

Our results indicate that GLM may be a useful therapeutic option in refractory SpA-related uveitis.

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

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

Association study of genes related to bone formation and resorption and the extent of radiographic change in ankylosing spondylitis

OBJECTIVE

To identify genetic associations with severity of radiographic damage in ankylosing spondylitis (AS).

METHOD

We studied 1537 AS cases of European descent; all fulfilled the modified New York Criteria. Radiographic severity was assessed from digitised lateral radiographs of the cervical and lumbar spine using the modified Stoke Ankylosing Spondylitis Spinal Score (mSASSS). A two-phase genotyping design was used. In phase 1, 498 single nucleotide polymorphisms (SNPs) were genotyped in 688 cases; these were selected to capture >90% of the common haplotypic variation in the exons, exon-intron boundaries, and 5 kb flanking DNA in the 5' and 3' UTR of 74 genes involved in anabolic or catabolic bone pathways. In phase 2, 15 SNPs exhibiting p<0.05 were genotyped in a further cohort of 830 AS cases; results were analysed both separately and in combination with the discovery phase data. Association was tested by contingency tables after separating the samples into 'mild' and 'severe' groups, defined as the bottom and top 40% by mSASSS, adjusted for gender and disease duration.

RESULTS

Experiment-wise association was observed with the SNP rs8092336 (combined OR 0.32, p=1.2×10(-5)), which lies within RANK (receptor activator of NFκB), a gene involved in osteoclastogenesis, and in the interaction between T cells and dendritic cells. Association was also found with the SNP rs1236913 in PTGS1 (prostaglandin-endoperoxide synthase 1, cyclooxygenase 1), giving an OR of 0.53 (p=2.6×10(-3)). There was no observed association between radiographic severity and HLA-B*27.

CONCLUSIONS

These findings support roles for bone resorption and prostaglandins pathways in the osteoproliferative changes in AS.