The gut microbiome and HLA-B27-associated anterior uveitis: a case-control study.

BACKGROUND: The human gut microbiome (GM) is involved in inflammation and immune response regulation. Dysbiosis, an imbalance in this ecosystem, facilitates pathogenic invasion, disrupts immune equilibrium, and potentially triggers diseases including various human leucocyte antigen (HLA)-B27-associated autoinflammatory and autoimmune diseases such as inflammatory bowel disease (IBD) and spondyloarthropathy (SpA). This study assesses compositional and functional alterations of the GM in patients with HLA-B27-associated non-infectious anterior uveitis (AU) compared to healthy controls. METHODS: The gut metagenomes of 20 patients with HLA-B27-associated non-infectious AU, 21 age- and sex-matched HLA-B27-negative controls, and 6 HLA-B27-positive healthy controls without a history of AU were sequenced using the Illumina NovaSeq 6000 platform for whole metagenome shotgun sequencing. To identify taxonomic and functional features with significantly different relative abundances between groups and to identify associations with clinical metadata, the multivariate association by linear models (MaAsLin) R package was applied. RESULTS: Significantly higher levels of the Eubacterium ramulus species were found in HLA-B27-negative controls (p = 0.0085, Mann-Whitney U-test). No significant differences in microbial composition were observed at all other taxonomic levels. Functionally, the lipid IVA biosynthesis pathway was upregulated in patients (p < 0.0001, Mann-Whitney U-test). A subgroup analysis comparing patients with an active non-infectious AU to their age- and sex-matched HLA-B27-negative controls, showed an increase of the species Phocaeicola vulgatus in active AU (p = 0.0530, Mann-Whitney U-test). An additional analysis comparing AU patients to age- and sex-matched HLA-B27-positive controls, showed an increase of the species Bacteroides caccae in controls (p = 0.0022, Mann-Whitney U-test). CONCLUSION: In our cohort, non-infectious AU development is associated with compositional and functional alterations of the GM. Further research is needed to assess the causality of these associations, offering potentially novel therapeutic strategies.

Anti-HLA-B7/HLA-B44 strong cross immunoreactivity observed in flow cytometry HLA-B27 immunotyping.

Cross reactivities are known for human leukocyte antigen inside HLA-B7 related Cross-Reactive Group (B7CREG). Some CE-IVD flow-cytometry kits use double monoclonal antibodies (mAb) to distinguish HLA-B27 and HLA-B7 but practice reveals more complexes results. This study explores the performances of this test. Analysis of 466 consecutive cases using HLA-B27 IOTest™ kit on a Navios™ cytometer from Beckman-Coulter, partially compared to their genotypes. Expected haplotypes HLA-B27-/HLA-B7- (undoubtedly HLA-B27 negative) and HLA-B27+/HLA-B7- (undoubtedly HLA-B27+) were clearly identified according to the manufacturer's instructions. On the opposite, patients strongly labeled with anti-HLA-B7 showed three different phenotypes regarding anti-HLA-B27 labeling: (1) most of the cases were poorly labeled in accordance with cross reactivity inside B7CREG (HLA-B27-/HLA-B7+ haplotype); (2) rare cases had strong B7 and B27 labeling corresponding to HLA-B27+/HLA-B7+ haplotype; (3) even less cases had strong labeling by anti-HLA-B7 but non for anti-HLA-B27, all expressing HLA-B44 and no B7CREG molecules. Surprisingly, more cases were not labeled with anti-HLA-B7 antibody but partially labeled with anti-HLA-B27 suggesting another cross reactivity out of B7CREG. mAb HLA typing suggests new, cross reactivities of anti-HLA-B27 antibody to more molecules out of B7CREG and of anti-HLA-B7 antibody but not anti-HLA-B27 to HLA-B44 molecule also out of B7CREG. HLA-B27 could surely be excluded in most samples labeled with HLA-B27, below a "grey zone" on intermediate intensity. More comparison is needed in future studies.

HLA-B5 prevalence in patients with spondyloarthritis and impact on disease phenotype: a multicentric case-control study.

OBJECTIVE: The study aimed to estimate the prevalence of HLA-B51 and HLA-B52 in Lebanese patients with spondyloarthritis (SpA) compared to healthy controls (HC). We further aimed to evaluate the impact of HLA-B51 on phenotype and identify the distribution of the alleles in the HLA-B locus. METHODS: A case-control study enrolled consecutive SpA patients from three rheumatology clinics in Lebanon, including axial (axSpA), peripheral SpA (pSpA), and psoriatic arthritis (PsA) and HC from blood donors. Demographic and disease data were collected through interviews and file reviews, with testing of the entire HLA-B locus using molecular techniques. The prevalence of HLA-B51 and B52 was estimated in SpA patients versus controls. Prevalence comparisons were made, and logistic regression identified factors associated with HLA-B51 in patients. RESULTS: Data from 120 HC and 86 SpA patients (65 axSpA, 15 pSpA, 6 PsA), mean age 25.6 and 46.4 years, respectively, showed a higher HLA-B51 prevalence in SpA (25.6%), especially axSpA (29.2%) versus HC (12.5%), p = 0.016, and a numerically higher HLA-B52 prevalence (8.1% versus 4.2%, p = 0.230). HLA-B51 correlated with recurrent oral ulcerations (OR 7.99(95%CI 2.14-29.84) and radiographic juxta-articular erosions (OR 7.65(95%CI 1.14-38.03)). HLA-B35 was the most dominant allele in both groups (18.7%), followed by HLA-B27 (15.7%) and HLA-B51 (13.4%) in SpA. CONCLUSION: HLA-B51 was identified more frequently in patients with SpA compared to HC and was associated with recurrent oral ulcerations and juxta-articular radiographic erosions. Longitudinal studies are needed to determine whether this association indicates a disease overlap or might correlate with a specific SpA phenotype.

Sequence of Events in the Pathogenesis of Axial Spondyloarthritis: A Current Review-2023 SPARTAN Meeting Proceedings.

PURPOSE OF REVIEW: Over the past two decades, significant progress has been made to untangle the etiology of inflammation and new bone formation (NBF) associated with axial spondyloarthritis (axSpA). However, exact mechanisms as to how the disease initiates and develops remain elusive. RECENT FINDINGS: Type 3 immunity, centered around the IL-23/IL-17 axis, has been recognized as a key player in the pathogenesis of axSpA. Multiple hypotheses associated with HLA-B*27 have been proposed to account for disease onset and progression of axSpA, potentially by driving downstream T cell responses. However, HLA-B*27 alone is not sufficient to fully explain the development of axSpA. Genome-wide association studies (GWAS) identified several genes that are potentially relevant to disease pathogenesis leading to a better understanding of the immune activation seen in axSpA. Furthermore, gut microbiome studies suggest an altered microbiome in axSpA, and animal studies suggest a pathogenic role for immune cells migrating from the gut to the joint. Recent studies focusing on the pathogenesis of new bone formation (NBF) have highlighted the importance of endochondral ossification, mechanical stress, pre-existing inflammation, and activated anabolic signaling pathways during the development of NBF. Despite the complex etiology of axSpA, recent studies have shed light on pivotal pieces that could lead to a better understanding of the pathogenic events in axSpA.

The Impact of Different MEFV Genotypes on Clinical Phenotype of Patients with Familial Mediterranean Fever: Special Emphasis on Joint Involvement.

Familial Mediterranean Fever (FMF) is the most common monogenic autoinflammatory disease worldwide. In this retrospective cohort study, we aimed to assess the effects of various MEFV genotypes on the clinical characteristics of the patients, with a special focus on the joint involvement. In total, 782 patients with FMF were categorized into 3 groups according to the MEFV mutation; Group 1: Patients homozygous for M694V; Group 2: Patients carrying other pathogenic MEFV variants in exon 10 in homozygous or compound heterozygous states; and Group 3: FMF patients with other variants or without mutations. Clinical and demographic findings were compared between groups. Among the 782 FMF patients, total frequency of arthritis was 237 (30.3%): 207 (26.4%) were acute monoarthritis and 67 (8.5%) were chronic arthritis. Both the frequency of arthritis (acute and/or chronic) (40.4% vs. 24.8% vs. 26.7%; p:0.001) and acute monoarthritis (35.4% vs. 20% vs. 23.7%; p:0.001) were significantly higher in Group 1 than in the other groups. FMF patients with chronic arthritis showed a distinct juvenile idiopathic arthritis (JIA) distribution pattern with a more frequent enthesitis-related arthritis (ERA) subtype (43.2%). HLA-B27 was positive in 24% of the ERA patients.Conclusion: Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritis comparing to other MEFV genotypes. In addition, the risk of chronic arthritis seems not related to the MEFV mutations. However, FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA and undifferentiated arthritis subtype. What is known: • Homozygous M694V mutation is associated with a more frequent and longer acute monoarthritis What is new: • FMF patients with chronic arthritis show a distinct ILAR JIA distribution pattern with a more frequent ERA subtype • ERA patients with negative HLA-B27 antigen should also be assessed for polyserositis episodes of FMF, especially in countries with high FMF carrier frequency.

Prevalence of HLA-B27, clinical characteristics and treatment outcomes in children with enthesitis-related arthritis.

BACKGROUND: Enthesitis-related arthritis (ERA) is a subtype of juvenile idiopathic arthritis with high disease burden. The objectives of this study were to explore the prevalence of HLA-B27, clinical characteristics, and treatment outcomes in children with ERA and compare the differences between HLA-B27 positive and negative patients. METHODS: A retrospective cohort study at a pediatric rheumatology clinic in a tertiary referral hospital in Bangkok, Thailand, including ERA patients with at least 6 months of follow-up (July 2011-April 2022) was performed. Data were collected from medical records from diagnosis to recent follow-up, assessing disease activity and treatment outcomes, with an analysis comparing HLA-B27 positive and negative patients. Descriptive statistics were used for data analysis. RESULTS: There were 59 ERA patients with mean age ± SD at diagnosis 11.2 ± 2.5 years, 53 males (89.8%), and positive HLA-B27 in 38 patients (64.4%). The HLA-B27 positive group had significantly higher levels of inflammatory markers at initial diagnosis (p = 0.001), lower baseline hemoglobin (p = 0.001) and hematocrit (p = 0.002), higher disease activity assessed by the Juvenile Spondyloarthritis Disease Activity score at 6 and 12 months of follow-up (p = 0.028 and 0.040, respectively), increased utilization of bridging systemic corticosteroids (60.5% vs. 14.3%, p = 0.001) and anti-TNF (39.5% vs. 9.5%, p = 0.018), and longer duration of methotrexate (median[IQR] 1.7[1.1-3.1] vs. 1.3[0.6-1.9] years, p = 0.040). The HLA-B27 negative group had more prevalent hip arthritis than the positive group at initial diagnosis (66.7% vs. 28.9%, p = 0.005) and during the course of the disease (71.4% vs. 36.8%, p = 0.011). CONCLUSION: Most of the ERA patients tested positive for HLA-B27. Throughout the follow-up period, these patients demonstrated greater disease activity, greater use of corticosteroids and anti-TNF, and longer duration of methotrexate to control the disease.

Exploring the Pathogenesis of Spondylarthritis beyond HLA-B27: A Descriptive Review.

Spondylarthritis (SpA) is a chronic inflammatory condition that encompasses damage to the axial or peripheral skeleton, accompanied by specific extra-articular symptoms. Within this group, Ankylosing Spondylitis stands out as the hallmark member. Although the heritability of Ankylosing Spondylitis is estimated to be over 95%, only a portion of the heritability has been explained, with HLA-B27 accounting for 20.1% of it; therefore, ongoing research endeavors are currently concentrated on investigating the potential participation of different entities in the development of the disease. Genome-wide association studies have led to significant advances in our understanding of the genetics of SpA. In this descriptive review, we delve into the pathogenesis of Spondylarthritis beyond HLA-B27. We summarize the latest research on the potential participation of various entities in the development of the disease, including other genetic loci, immune dysregulation, microbiota, and environmental factors. The multifactorial nature of SpA and the complex interplay of genetic, immunological, and environmental factors are being increasingly recognized; therefore, it is of paramount importance to consider a holistic approach to comprehend the pathogenesis of SpA in order to identify novel therapeutic targets.

Changes in HLA-B27 Transgenic Rat Fecal Microbiota Following Tofacitinib Treatment and Ileocecal Resection Surgery: Implications for Crohn's Disease Management.

The therapeutic management of Crohn's disease (CD), a chronic relapsing-remitting inflammatory bowel disease (IBD), is highly challenging. Surgical resection is sometimes a necessary procedure even though it is often associated with postoperative recurrences (PORs). Tofacitinib, an orally active small molecule Janus kinase inhibitor, is an anti-inflammatory drug meant to limit PORs in CD. Whereas bidirectional interactions between the gut microbiota and the relevant IBD drug are crucial, little is known about the impact of tofacitinib on the gut microbiota. The HLA-B27 transgenic rat is a good preclinical model used in IBD research, including for PORs after ileocecal resection (ICR). In the present study, we used shotgun metagenomics to first delineate the baseline composition and determinants of the fecal microbiome of HLA-B27 rats and then to evaluate the distinct impact of either tofacitinib treatment, ileocecal resection or the cumulative effect of both interventions on the gut microbiota in these HLA-B27 rats. The results confirmed that the microbiome of the HLA-B27 rats was fairly different from their wild-type littermates. We demonstrated here that oral treatment with tofacitinib does not affect the gut microbial composition of HLA-B27 rats. Of note, we showed that ICR induced an intense loss of bacterial diversity together with dramatic changes in taxa relative abundances. However, the oral treatment with tofacitinib neither modified the alpha-diversity nor exacerbated significant modifications in bacterial taxa induced by ICR. Collectively, these preclinical data are rather favorable for the use of tofacitinib in combination with ICR to address Crohn's disease management when considering microbiota.

Spondyloarthropathies and arthritis post-infection: a historical perspective.

The spondyloarthropathies are a group of conditions characterised by spinal joint pain and have related clinical, epidemiological and genetic-related features. Ankylosing spondylitis, reactive arthritis, the spinal form of psoriatic arthritis and Crohn's and colitis enteropathic arthritis are the major clinical entities of the spondyloarthropathies, and principally occur in HLA-B27 positive individuals. Ankylosing spondylitis is much more common in males than females. Patients are usually seronegative for rheumatoid factor, and extra-articular features including iridocyclitis, mucous membrane and skin lesions: aortitis, may occur in some patients. The reactive arthritis form classically occurs following an infection of the gastrointestinal or genitourinary tract. The Crohn's and colitis enteropathic arthritis forms often have an associated large joint asymmetrical arthritis. Also discussed are acute rheumatic fever and Lyme disease which are conditions where the individual develops arthritis after an infection.

Looking back on 51 years of the Carol Nachman Prize in Rheumatology-significance for the field of spondyloarthritis research.

The city and casino of Wiesbaden, capital of the German state Hessen, have endowed the Carol Nachman Prize to promote research work in the field of rheumatology since 1972. The prize, endowed with 37,500 €, is the second highest medical award in Germany and serves to promote clinical, therapeutic, and experimental research work in the field of rheumatology. In June 2022, the 50-year anniversary was celebrated. In the symposium preceding the award ceremony, an overview was given on the significance of spondyloarthritis for the work of the awardees in the past 30 years. This overview has now been put together to inform the interested community of the work performed, including the opinion of the awardees regarding what they consider to be their most important contribution.

The possible protective role of HLA B27 and relevant immune markers in Juvenile Idiopathic Arthritis patients.

Background & Objectives: JIA is a disease with different immunological characteristics and a complicated genetic foundation. HLA B27 is a risk factor for the development of JIA, and its impact on immunopathogenesis of the disease is also an area of interest. To determine whether HLA B27 and immune markers varied between JIA patients and healthy population. Methods: This comparative cross-sectional study was conducted at Immunology Department of University of Health sciences (UHS), Lahore from February 2018 till August 2021. A total of (71) JIA patients and (34) healthy controls were enrolled. B cells were enumerated by flowcytometry, ELISA was used for serum cytokines estimation and HLA B27 allele was detected by SPSS polymerase chain reaction. Results: The HLA B27 allele was significantly more in the control group than in the patient group, suggesting it is a protective allele to prevent JIA. Peripheral blood B cell counts and percentages were significantly lower in the HLA B27 positive group than in the HLA B27 negative group of control population. Serum cytokine levels were not significantly different between the HLA B27 positive and HLA B27 negative allele of the two study populations. Conclusion: In this study B cells are different between the two groups of control population however; serum cytokines are comparable between the study groups. Though, it was indicated that HLA B27 may be a preventive allele in the onset of JIA.

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

BACKGROUND: HLA-B27 positivity is normal in patients undergoing rheumatic diseases. The diagnosis of many diseases requires an HLA-B27 examination. METHODS: This study screened totally 1503 patients who underwent HLA-B27 examination, liver/kidney function tests, and complete blood routine examination in First Affiliated Hospital of Guangxi Medical University. The training cohort included 509 cases with HLA-B27 positivity whereas 611 with HLA-B27 negativity. In addition, validation cohort included 147 cases with HLA-B27 positivity whereas 236 with HLA-B27 negativity. In this study, 3 ML approaches, namely, LASSO, support vector machine (SVM) recursive feature elimination and random forest, were adopted for screening feature variables. Subsequently, to acquire the prediction model, the intersection was selected. Finally, differences among 148 cases with HLA-B27 positivity and negativity suffering from ankylosing spondylitis (AS) were investigated. RESULTS: Six factors, namely red blood cell count, human major compatibility complex, mean platelet volume, albumin/globulin ratio (ALB/GLB), prealbumin, and bicarbonate radical, were chosen with the aim of constructing the diagnostic nomogram using ML methods. For training queue, nomogram curve exhibited the value of area under the curve (AUC) of 0.8254496, and C-value of the model was 0.825. Moreover, nomogram C-value of the validation queue was 0.853, and the AUC value was 0.852675. Furthermore, a significant decrease in the ALB/GLB was noted among cases with HLA-B27 positivity and AS cases. CONCLUSION: To conclude, the proposed ML model can effectively predict HLA-B27 and help doctors in the diagnosis of various immune diseases.

Predictors of long-term functional outcomes of juvenile idiopathic arthritis-enthesitis-related arthritis: a single centre experience.

OBJECTIVES: Long-term functional outcomes in enthesitis-related arthritis (ERA) is limited from developing countries. We assessed the clinical and genetic factors that predicted the long-term functional outcome in ERA. METHODS: Patients with ERA having ≥5 years of disease and >16 years of age were included in this cross-sectional study. Data on clinical features within 6 months of disease onset was collected from hospital records. Bath indices, HAQ Disability Index (HAQ-DI) and World Health Organization's Quality of Life (WHO-QOL) were assessed at last visit. Poor functional outcome (PFO) was defined as BASFI > 1.5 or HAQ-DI > 1. Persistent disease activity (PDA) was defined as BASDAI ≥ 4. Endoplasmic reticulum aminopeptidase 1 (ERAP1) and IL-23 receptor single nucleotide polymorphism genotyping was performed with the TaqMan method and HLA-B27 by PCR. RESULTS: One hundred and eighty-one patients [170 male, median (interquartile range) age of disease onset 12.5 (10-15) years, disease duration 7 (5-11) years] were recruited. There was a delay in diagnosis of 3 (1-5) years. The median Ankylosing Spondylitis Disease Activity Score (ASDAS)-ESR, BASDAI, HAQ-DI and BASFI at inclusion were 2.6 (1.8-3.6), 2.6 (1-5.2), 0.5 (0-0.5) and 1.6 (0.3-3.2), respectively. BASFI and HAQ-DI correlated with ASDAS-ESR, ASDAS-CRP and WHO-QOL-BREF. Those with PFO (n = 98) had a longer delay in diagnosis (4 vs 2 years, P < 0.001), lower prevalence of arthritis at onset [odds ratio (OR) = 0.3; 95% CI: 0.1, 0.8], higher prevalence of ERAP1 (rs27044) allele C (OR = 7.2; 95% CI: 1.5, 33.7) and higher disease activity currently. Delay in diagnosis (OR = 1.2; 95% CI: 1.08, 1.4) was the sole predictor of PFO in multivariate analysis. One-third of patients had PDA. Tarsitis at disease onset was the sole predictor of PDA (OR = 2.3; 95% CI: 1.009, 5.4). CONCLUSIONS: PFO was seen in one-half of JIA-ERA in the long-term and was associated with active disease with delay in diagnosis as its sole predictor.

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 ß 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.

Clinical significance of possible HLA biomarkers in axial spondyloarthritis beyond HLA-B27 positivity.

The aim of this study is to compare four forms of axial spondyloarthritis (axSpA): non-radiographic axial spondyloarthritis (nr-axSpA), ankylosing spondylitis (AS), non-radiographic axial psoriatic arthritis (nr-axPsA) and radiographic axial psoriatic arthritis (r-axPsA). In a cross-sectional retrospective study, gender difference, human leukocyte antigen (HLA) typing, laboratory C-reactive protein (CRP) and erythrocyte sedimentation (SE) values, and radiographic and magnetic resonance scans were analyzed. One hundred and thirty-seven patients were included in the study: 45 AS, 51 nr-axSpA, 32 r-axPsA and 9 nr-axPsA; 74 women and 63 men. Most of the gender, laboratory and radiological findings confirmed the results of previously conducted studies about each group of the investigated axSpA. The key findings of our study are the newly detected findings of HLA typing beyond HLA-27 positivity: HLA-DR16 in AS, HLA-DR11 in nr-axSpA, HLA-B13, HLA-B57, HLA-Cw12 and HLA-DR7 in r-axPsA, and HLA-B18 in nr-axPsA. Our study also confirmed some of the results of previously conducted studies on predominant genes of HLA typing in axSpA: HLA-B27 in AS, HLA-B39 and HLA-Cw6 in r-axPsA, and HLA-Cw7 in nr-axPsA. Important conclusions about the nr-axPsA group cannot be drawn because of the very small number of subjects included in this group of axSpA. Our results suggest that the newly detected HLA typing findings beyond HLA-B27 positivity could be possible biomarkers of early detection of axSpA, but further studies on larger samples are needed.

When MRI would be useful in patients without evidence of sacroiliitis on radiographs?

We aimed to identify when magnetic resonance imaging (MRI) would be useful to diagnose patients with suspected axial spondyloarthropathy (AxSpA) without evidence of sacroiliitis on radiographs. We retrospectively reviewed electronic medical records of patients who underwent pelvis MRI after radiographs at the rheumatology clinic in a single tertiary center in Korea. Patients underwent imaging from January 2020 to July 2022. We collected data including complete blood count, erythrocyte sedimentation rate, C-reactive protein (CRP), human leukocyte antigen (HLA)-B27, history of acute anterior uveitis (AAU), peripheral arthritis, dactylitis, inflammatory bowel disease (IBD), enthesopathy, and psoriasis. A total of 105 patients who showed no evidence of sacroiliitis on radiographs were included. The median age of patients was 41.0 years, and 44.8% were male. Of them, 34 showed sacroiliitis on MRI (group 1), and 71 showed no evidence of sacroiliitis even on MRI (group 2). Known AxSpA-related clinical features including AAU, peripheral arthritis, dactylitis, IBD, enthesopathy, and psoriasis were not different between the two groups. HLA-B27 positivity (79.4% vs. 40.0%, p < 0.001), median white blood cell count (7700 vs. 6300, p = 0.007), mean platelet count (307.7 ± 69.7 vs. 265.3 ± 68.9 × 103/µL, p = 0.005), and median CRP level (0.38 vs. 0.10, p = 0.001) showed significant differences between the two groups. In a multivariate analysis, HLA-B27 positivity and platelet count were significantly associated with sacroiliitis on MRI. In our cohort, sacroiliitis was observed on MRI in one-third of patients without radiographic evidence. MRI could be recommended to evaluate sacroiliitis in patients with positive HLA-B27 and a high platelet count.

Recent updates in enthesitis-related arthritis.

Enthesitis-related arthritis (ERA) is a category of juvenile idiopathic arthritis which belongs to the spectrum of diseases that are included in juvenile spondyloarthropathy. In recent years, there have been significant advances in understanding pathogenesis, tools to assess disease activity, early recognition of the axial disease, and targeted therapy using IL-17 inhibitors and small molecule inhibitors. The current narrative review highlights these new advances. Among many hypotheses linking HLA B27 to ERA, one of them is the effect of HLA B27 on gut dysbiosis. However, recent data suggest that gut dysbiosis is probably not determined by HLA B27. Though children present with arthritis and enthesitis, axial disease is present in 50-60% on MRI. Using data-driven approach, discriminative MRI finding for active and chronic diseases has been defined for children. This will help in the early recognition of disease. An abridged version of juvenile spondyloarthropathy disease activity (JSpADA) score without the need for acute phase reactants and Schober test performed as well as the original score may increase its acceptance in routine practice. Secukinumab (anti-IL-17 antibody) has shown a more than 75% response rate in children with ERA and may be a good alternative to anti-TNF therapy. Initial data with tofacitinib also look promising. All these will translate into better outcomes for children with ERA.

Rheumatologist's Perspective on Non-Infectious Uveitis: Patterns from Tertiary Referral Rheumatologic Clinics in Italy.

Non-infectious uveitis (NIU) can be an early or even the first extra-articular manifestation of systemic rheumatic diseases, or the first one; thus, rheumatologists are often involved in the diagnostic and therapeutic assessment of NIU. We evaluated 130 patients with a diagnosis of NIU who were admitted to two Italian rheumatologic clinics (Tor Vergata University Hospital in Rome, and Federico II University in Naples) from January 2018 to December 2021. Anterior uveitis (AU) occurred in 75.4% of patients, followed by posterior uveitis (PU, 21.5%); acute (54.6%) and recurrent (35.4%) NIU were more documented than chronic NIU (10%), and a bilateral involvement was observed in 38.7% of cases. Half of NIU cases were associated with spondyloarthritis (SpA); the remaining were affected by Behçet disease (BD)-related uveitis (13.9%) and idiopathic NIU (9.2%). HLA-B27+ patients (34.8%) had a higher prevalence of anterior and unilateral NIU (p = 0.005) with acute course (p = 0.04) than HLA-B27- patients. On the contrary, HLA-B51+ patients (19.6%) had mostly PU and bilateral NIU (p < 0.0001) and recurrent course (p = 0.04) than HLA-B51- patients. At the first rheumatologic referral, 117 patients (90%) received systemic treatments. Findings from this study demonstrate that rheumatologic referral has a pivotal role in the diagnostic work-up of NIU and may dramatically influence NIU-treatment strategies.

ERAP1 and ERAP2 Haplotypes Influence Suboptimal HLA-B*27:05-Restricted Anti-Viral CD8+ T Cell Responses Cross-Reactive to Self-Epitopes.

The human leukocyte antigen (HLA)-B*27 family of alleles is strongly associated with ankylosing spondylitis (AS), a chronic inflammatory disorder affecting the axial and peripheral joints, yet some HLA-B*27 variants not associated with AS have been shown. Since no major differences in the ligandome of associated compared to not-associated alleles have emerged, a plausible hypothesis is that the quantity rather than the quality of the presented epitopes makes the difference. In addition, the Endoplasmic Reticulum AminoPeptidases (ERAPs) 1 and 2, playing a crucial role in shaping the HLA class I epitopes, act as strong AS susceptibility factors, suggesting that an altered peptidome might be responsible for the activation of pathogenic CD8+ T cells. In this context, we have previously singled out a B*27:05-restricted CD8+ T cell response against pEBNA3A (RPPIFIRRL), an EBV peptide lacking the B*27 classic binding motif. Here, we show that a specific ERAP1/2 haplotype negatively correlates with such response in B*27:05 subjects. Moreover, we prove that the B*27:05 allele successfully presents peptides with the same suboptimal N-terminal RP motif, including the self-peptide, pDYNEIN (RPPIFGDFL). Overall, this study underscores the cooperation between the HLA-B*27 and ERAP1/2 allelic variants in defining CD8+ T cell reactivity to suboptimal viral and self-B*27 peptides and prompts further investigation of the B*27:05 peptidome composition.

A multicentre study of clinical features and HLA typing in Japanese patients with ankylosing spondylitis.

OBJECTIVES: Due to the low prevalence of HLA-B27 and ankylosing spondylitis (AS) in Japan, rheumatologists have little experience with AS. We conducted a multicentre study to identify the characteristics and frequency of HLA-B types. METHODS: We analysed epidemiological and clinical data, blood tests, spine radiographs, and HLA-B types in Japanese AS patients. RESULTS: We evaluated 111 AS patients, predominantly men (82.9%). The mean age, disease onset, diagnosis, and time from onset to diagnosis were 43.7, 24.2, 36.0, and 11.6 years, respectively. Inflammatory low back pain was found in 96 cases (86.5%); peripheral arthritis in 59 (53.2%), enthesitis in 35 (31.5%), and dactylitis in 6 (5.4%). Extra-articular symptoms included uveitis, psoriasis, and inflammatory bowel disease in 41 (36.9%), 1 (0.9%), and 5 (4.5%) cases, respectively. HLA-B27 was positive in 83 cases (74.8%; odds ratio, 1146.0); and HLA-B48 in 9 (8.1%; odds ratio, 3.0). HLA-B27-positive patients were younger at onset and had a shorter diagnostic delay. CONCLUSIONS: AS clinical symptoms were almost the same as other countries except for the low coexistence of psoriasis. HLA-B27 positivity in Japanese patients was 78%. HLA-B27-positive patients were younger and diagnosed earlier. In addition to HLA-B27, a relationship with HLA-B48 was suggested.