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Background: Ankylosing spondylitis (AS) is a chronic inflammatory joint disorder, necessitating early diagnosis and effective treatment. The specific mechanism of action of Cassia twigs in the treatment of AS is not fully understood., Methods: Blood samples and clinical data from 28,458 individuals (6,101 with AS, 22,357 without AS) were collected. To construct a predictive model, we utilized logistic regressions and machine learning techniques to create a dynamic nomogram. Immune cell infiltration was evaluated using the GSE73754 dataset. Subsequently, we obtained vertebral bone marrow blood from AS patients for 10X single-cell sequencing. We also extracted and purified total RNA from hip joint ligament tissue samples from six AS patients and six non-AS patients. The genes related to the expression of AS and Cassia twigs were analyzed comprehensively, and the specific drug targets were identified by molecular docking. The interactions between immune cells through cell communication analysis were elucidated., Results: We developed a dynamic nomogram incorporating the neutrophil count (NEUT) and other variables. Neutrophil immune responses were confirmed through immune infiltration analysis utilizing GSE73754. We observed the early involvement of neutrophils in the pathology of AS. The CAT-expressing Cassia twigs gene could be used as a drug target for the treatment of AS. Moreover, comprehensive RNA analysis revealed notable CAT expression in neutrophils and various other immune cells., Conclusions: Neutrophils play dual roles in AS, regulating inflammation and initiating differentiation signals to other cells. The CAT gene, which is expressed in Cassia twigs, has emerged as a potential therapeutic target for AS treatment., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: This study aimed to elucidate the causal relationships between antibodies and autoimmune diseases using Mendelian randomization (MR)., Methods: Data on 46 antibodies were obtained from genome-wide association studies (GWAS). Autoimmune disease data were sourced from the FinnGen consortium and the IEU OpenGWAS project. Inverse-variance weighted (IVW) analysis was the primary method, supplemented by heterogeneity and sensitivity analyses. We also examined gene expression near significant SNPs and conducted drug sensitivity analyses., Results: Antibodies and autoimmune diseases exhibit diverse interactions. Antibodies produced after Polyomavirus infection tend to increase the risk of several autoimmune diseases, while those following Human herpesvirus 6 infection generally reduce it. The impact of Helicobacter pylori infection varies, with different antibodies affecting autoimmune diseases in distinct ways. Overall, antibodies significantly influence the risk of developing autoimmune diseases, whereas autoimmune diseases have a lesser impact on antibody levels. Gene expression and drug sensitivity analyses identified multiple genes and drugs as potential treatment options for ankylosing spondylitis (AS), with the AIF1 gene being particularly promising., Conclusions: Bidirectional MR analysis confirms complex causal relationships between various antibodies and autoimmune diseases, revealing intricate patterns of post-infection antibody interactions. Several drugs and genes, notably AIF1, show potential as candidates for AS treatment, offering new avenues for research. Further exploration of the underlying mechanisms is necessary., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objective: This study aims to explore the effects of Triptolide (TP) on the differentiation of Th17 cells in ankylosing spondylitis (AS)., Methods: Peripheral blood mononuclear cells (PBMCs) collected from 10 patients with active AS patients were exposed to TP, GSK-J4 or vehicle. T lymphocyte subsets were analyzed using flow cytometry. ELISA was used to assess the level of IL-17. Western blot analysis and quantitative RT-PCR were used to measure the mRNA and protein levels of RORγt, JMJD3, EZH2, JAK2 and STAT3 in the JAK2/STAT3 signaling pathway., Results: We observed a tendency toward a greater percentage of IL-17-positive CD4+ T cells in peripheral blood mononuclear cells (PBMCs) from patients with active AS than in those from healthy controls. Triptolide (TP) and GSK-J4 significantly reduced IL-17 expression. In cultured PBMCs from patients with active AS, 24 h of treatment with TP or GSK-J4 decreased the expression of RORγt ( p  < 0.05), JAK2 and STAT3 (JAK2: p  < 0.05; STAT3: p  < 0.05). Furthermore, both triptolide and GSK-J4 increased the level of histone 3 with Lys 27 trimethylation (H3K27me3) in patient-derived PBMCs. H3K27me3 enrichment was detected at the promoters of the RORc, STAT3 and IL-17 genes. Consistent with this finding, triptolide upregulated the EZH2 gene and downregulated the JMJD3 gene., Conclusion: Triptolide inhibits Th17 cell differentiation via H3K27me3 upregulation and orchestrates changes in histone-modifying enzymes, including JMJD3 and EZH2. These findings support the clinical efficacy of triptolide for AS and may provide clues for identifying molecular targets for the development of novel treatments.

Objective: This study aims to comprehensively investigate immune-cell landscapes in ankylosing spondylitis (AS) patients and explore longitudinal immunophenotyping changes induced by biological agents., Methods: We employed mass cytometry with 35 cellular markers to analyze blood samples from 34 AS patients and 13 healthy controls (HC). Eleven AS patients were re-evaluated 1 month (4 patients) and 3 months (7 patients) after treatment with biological agents. Flow Self-Organizing Maps (FlowSOM) clustering was performed to identify specific cellular metaclusters. We compared cellular abundances across distinct subgroups and validated subset differences using gating strategies in flow cytometry scatter plots, visualized with FlowJo software. The proportions of differential subsets were then used for intercellular and clinical correlation analysis, as well as for constructing diagnostic models based on the random forest algorithm., Results: In AS patients, we identified and validated nine different immune-cell subsets compared to HC. Three subsets increased: helper T-cell 17 (Th17), mucosa-associated invariant T-cell (MAIT), and classical monocytes (CM). Six subsets decreased: effector memory T-cell (TEM), naïve B cells, transitional B cells, IL10+ memory B cells, non-classical monocytes (NCM), and neutrophils. Treatments with biological agents could rectify cellular abnormalities, particularly the imbalance of CM/NCM. Furthermore, these subsets may serve as biomarkers for assessing disease activity and constructing effective diagnostic models for AS., Conclusion: These findings provide novel insights into the specific patterns of immune cell in AS, facilitating the further development of novel biomarkers and potential therapeutic targets for AS patients., (© 2024 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.)

Aim: This study investigates changes in immune cell subsets in peripheral blood of ankylosing spondylitis (AS) patients with colitis or terminal ileitis. It aims to explore the connection between changes in lymphocyte subsets and gut inflammation, providing insights for early detection., Methods: Overall, 50 AS patients undergoing colonoscopy were enrolled. Flow cytometry was employed to analyze lymphocyte subsets, including T and B cells, in peripheral blood. Disease activity was assessed using CRP, ESR, BASDAI, ASDAS-CRP, and ASDAS-ESR., Results: Compared to AS patients without gut inflammation, those with colorectal inflammation showed a significant increase in total T cells (p < .05), an increase in exhausted CD4 + T cells (p < .05), and a decrease in Th2 cells and total Tc cells (p < .05). Notably, in AS patients with terminal ileitis, there was an increase in total B cells and classic switched B cells (p < .05), with a decrease in double-positive T cells (p < .05). However, no significant differences were observed in the distribution of Tfh-cell subpopulations (Tfh1, Tfh2, Tfh17) and Tc-cell subpopulations (Tc1, Tc2, Tc17) between AS patients with either colorectal inflammation or terminal ileitis (p > .05). We explored the relationship between disease activity scores, ESR, CRP, and lymphocyte subsets, but found no statistically significant correlation between them., Conclusion: Distinct immune patterns may exist in AS with different types of intestinal inflammation. Colitis in AS is primarily characterized by a significant increase in exhausted CD4 + T cells, along with a decrease in Th2 cells. In contrast, terminal ileum inflammation in AS is marked by an increase in total B cells and classic switched B cells. These findings offer new insights for early detection and therapeutic intervention., (© 2024 Asia Pacific League of Associations for Rheumatology and John Wiley & Sons Australia, Ltd.)

Objectives: Tuberculosis is a highly contagious disease that has a significant impact on global health. Emerging evidence suggests that tuberculosis can lead to an altered immune response. We investigated the association between tuberculosis and the onset of inflammatory arthritides (IA)., Methods: Patients with incident tuberculosis in the South Korean National Claims database from 2010 to 2021 were included, and those who had undergone appendectomy during 2010-2011 served as controls. The onset of IA (including seropositive rheumatoid arthritis [SPRA], ankylosing spondylitis [AS], and psoriatic arthritis [PsA]) after tuberculosis was compared between patients with tuberculosis and the control group. Sensitivity analysis was performed using stabilised inverse probability of treatment weighting (sIPTW)., Results: A total of 408,685 patients with tuberculosis and 159,675 controls were included. During the mean follow-up of 7.5 years, a total of 1,957 (0.3%) were diagnosed with IA (SPRA, 1,397; AS, 481; and PsA, 79). Multivariable Cox hazard analysis indicated that the overall risk of IA was elevated in the tuberculosis group (hazard ratio [HR], 1.71; 95% confidence interval [CI], 1.51-1.93) compared with controls. This increased incidence in patients with tuberculosis was identical among IA subgroups even after adjustment (SPRA [HR, 1.72; 95% CI, 1.49-2.00], AS [HR, 1.64; 95% CI, 1.30-2.06], and PsA [HR, 2.59; 95% CI, 1.32-5.07]) and was replicated in the sIPTW., Conclusions: The increased overall risk of developing IA after tuberculosis corroborates the hypothesis that tuberculosis can trigger dysregulated immunity. This necessitates an increased awareness of autoimmunity in this patient group.

The mechanisms of endotoxin tolerance (ET), which down-regulate inflammation, are well described in response to exogenous toll-like receptor ligands, but few studies have focused on ET-associated mechanisms in inflammatory disease. As blocking TNF can attenuate the development of ET, the effect of anti-TNF on the expression of key ET-associated molecules in inflammatory auto-immune disease was measured; changes in inflammatory gene expression were confirmed using an ET bioassay. The expression of immunomodulatory molecules was measured in a murine model of arthritis treated with anti-TNF and the expression of ET-associated molecules was measured in whole blood in rheumatoid arthritis (RA) and ankylosing spondylitis (AS) patients, before and after therapy. The expression of ET-associated genes was also measured in RA patient monocytes before and after therapy, in anti-TNF responders and non-responders. Tnfaip3, Ptpn6 and Irak3 were differentially expressed in affected paws, spleens, lymph nodes and circulating leucocytes in experimental murine arthritis treated with anti-TNF. Prior to therapy, the expression of TNFAIP3, INPP5D, PTPN6, CD38 and SIGIRR in whole blood differed between human healthy controls and RA or AS patients. In blood monocytes from RA patients, the expression of TNFAIP3 was significantly reduced by anti-TNF therapy in non-responders. Prior to therapy, anti-TNF non-responders had higher expression of TNFAIP3 and SLPI, compared to responders. Although the expression of TNFAIP3 was significantly higher in RA non-responders prior to treatment, the post-treatment reduction to a level similar to responders did not coincide with a clinical response to therapy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Background: Adalimumab induces the production of anti-drug antibodies (ADA) that may lead to reduced drug concentration and loss-of-response, posing significant clinical challenges. However, traditional immunoassays have limitations in terms of sensitivity and drug-tolerance, hindering the insights of ADA response., Methods: Herein, we developed an integrated immunoassay platform combining the electrochemiluminescence immunoassay with immunomagnetic separation strategy. A longitudinal cohort study involving 49 patients with ankylosing spondylitis was carried out to analyze the dynamic profiles of ADA and to investigate the impact of ADA on adalimumab pharmacokinetics using a population pharmacokinetic model. Additionally, cross-sectional data from 12 patients were collected to validate the correlation between ADA levels and disease relapse., Results: The ADA assay demonstrated high sensitivity (0.4 ng/mL) and drug-tolerance (100 μg/mL), while the neutralizing antibodies (NAB) assay showed a sensitivity of 100 ng/mL and drug-tolerance of 20 μg/mL. Analysis of the longitudinal cohort revealed that a majority of patients (44/49, 90%) developed persistent ADA within the first 24 weeks of treatment. ADA levels tended to plateau over time after an initial increase during the early immune response phase. Further, nearly all of the tested patients (26/27, 96%) were classified as NAB positive, with a strong correlation between ADA levels and neutralization capacity (R 2 = 0.83, P < 0.001). Population pharmacokinetic modeling revealed a significant positive association between model-estimated individual clearance and observed ADA levels. Higher ADA levels were associated with adalimumab clearance and disease relapse in a cross-sectional cohort, suggesting a promising ADA threshold of 10 for potential clinical application. Moreover, the IgG class was the primary contributor to ADA against adalimumab and the apparent affinity exhibited an increasing trend over time, indicating a T-cell dependent mechanism for ADA elicitation by adalimumab., Conclusion: In summary, this integrated immunoassay platform shows promise for in-depth analysis of ADA against biologics, offering fresh insights into immunogenicity and its clinical implications., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Ding, Xue, Wang, Zhu, Zhu, Jiang, Wu and Miao.)

This study aimed to analyze single-cell sequencing data to investigate immune cell interactions in ankylosing spondylitis (AS) and ulcerative colitis (UC). Vertebral bone marrow blood was collected from three AS patients for 10X single-cell sequencing. Analysis of single-cell data revealed distinct cell types in AS and UC patients. Cells significantly co-expressing immune cells (P < 0.05) were subjected to communication analysis. Overlapping genes of these co-expressing immune cells were subjected to GO and KEGG analyses. Key genes were identified using STRING and Cytoscape to assess their correlation with immune cell expression. The results showed the significance of neutrophils in both diseases (P < 0.01), with notable interactions identified through communication analysis. XBP1 emerged as a Hub gene for both diseases, with AUC values of 0.760 for AS and 0.933 for UC. Immunohistochemistry verified that the expression of XBP1 was significantly lower in the AS group and significantly greater in the UC group than in the control group (P < 0.01). This finding highlights the critical role of neutrophils in both AS and UC, suggesting the presence of shared immune response elements. The identification of XBP1 as a potential therapeutic target offers promising intervention avenues for both diseases., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Various lymphocyte subpopulations, including NK cells as well as γδ T cells, have been considered an important element in the pathogenesis of autoimmune, inflammatory, rheumatic diseases, such as rheumatoid arthritis (RA) and ankylosing spondylitis (AS). The aim of this study was to assess the potential role of polymorphic variations in the genes coding for three NK and γδ T cell receptors: NCR3, FCγR3A, and DNAM-1 (rs1052248, rs396991, and rs763361, respectively) in the disease susceptibility and the efficacy of treatment with TNF inhibitors. The study included 461 patients with RA, 168 patients with AS, and 235 voluntary blood donors as controls. The NCR3 rs1052248 AA homozygosity prevailed in RA in patients lacking rheumatoid factor (p = 0.044) as well as in those who manifested the disease at a younger age (p = 0.005) and had higher CRP levels after 12 weeks of anti-TNF therapy (p = 0.021). The FCγR3A rs396991 polymorphism was associated with pain visual analogue scale (VAS) values before the initiation of anti-TNF treatment. Lower VAS values were observed in the GG homozygous RA patients (p = 0.024) and in AS patients with the TT genotype (p = 0.012). Moreover, AS heterozygous patients with the TG genotype presented higher CRP levels in the 12th week of anti-TNF treatment (p = 0.021). The findings suggest that the NCR3 rs1052248 AA homozygosity may have an adverse effect on RA, while the T allele potentially plays a protective role in the development of AS. Moreover, the rs1052248 T allele and TT genotype appear to have a favorable impact on the response to anti-TNF therapy in RA patients., (© 2024. The Author(s).)

Ankylosing spondylitis (AS) stands as a persistent inflammatory ailment predominantly impacting the axial skeleton, with the immune system and inflammation intricately entwined in its pathogenesis. This study endeavors to elucidate gender-specific patterns in immune cell infiltration and diverse forms of cell demise within the AS milieu. The aim is to refine the diagnosis and treatment of gender-specific AS patients, thereby advancing patient outcomes. In the pursuit of our investigation, two datasets (GSE25101 and GSE73754) pertinent to ankylosing spondylitis (AS) were meticulously collected and normalized from the GEO database. Employing the CIBERSORT algorithm, we conducted a comprehensive analysis of immune cell infiltration across distinct demographic groups and genders. Subsequently, we discerned differentially expressed genes (DEGs) associated with various cell death modalities in AS patients and their healthy counterparts. Our focus extended specifically to ferroptosis-related DEGs (FRDEGs), cuproptosis-related DEGs (CRDEGs), anoikis-related DEGs (ARDEGs), autophagy-related DEGs (AURDEGs), and pyroptosis-related DEGs (PRDEGs). Further scrutiny involved discerning disparities in these DEGs between AS patients and healthy controls, as well as disparities between male and female patients. Leveraging machine learning (ML) methodologies, we formulated disease prediction models employing cell death-related DEGs (CDRDEGs) and identified biomarkers intertwined with cell death in AS. Relative to healthy controls, a myriad of differentially expressed genes (DEGs) linked to cell death surfaced in AS patients. Among AS patients, 82 FRDEGs, 29 CRDEGs, 54 AURDEGs, 21 ARDEGs, and 74 PRDEGs were identified. In male AS patients, these numbers were 78, 33, 55, 24, and 94, respectively. Female AS patients exhibited 66, 41, 40, 17, and 82 DEGs in the corresponding categories. Additionally, 36 FRDEGs, 14 CRDEGs, 19 AURDEGs, 10 ARDEGs, and 36 PRDEGs exhibited differential expression between male and female AS patients. Employing machine learning techniques, LASSO, RF, and SVM-RFE were employed to discern key DEGs related to cell death (CDRDDEGs). The six pivotal CDRDDEGs in AS patients, healthy controls, were identified as CLIC4, BIRC2, MATK, PKN2, SLC25A5, and EDEM1. For male AS patients, the three crucial CDRDDEGs were EDEM1, MAP3K11, and TRIM21, whereas for female AS patients, COX7B, PEX2, and RHEB took precedence. Furthermore, the trio of DDX3X, CAPNS1, and TMSB4Y emerged as the key CDRDDEGs distinguishing between male and female AS patients. In the realm of immune correlation, the immune infiltration abundance in female patients mirrored that of healthy controls. Notably, key genes exhibited a positive correlation with T-cell CD4 memory activation when comparing male and female patient samples. This study engenders a more profound comprehension of the molecular underpinnings governing immune cell infiltration and cell death in ankylosing spondylitis (AS). Furthermore, the discernment of gender-specific disparities among AS patients underscores the clinical significance of these findings. By identifying DEGs associated with diverse cell death modalities, this study proffers invaluable insights into potential clinical targets for AS patients, taking cognizance of gender-specific nuances. The identification of gender-specific biological targets lays the groundwork for the development of tailored diagnostic and therapeutic strategies, heralding a pivotal step toward personalized care for AS patients., (© 2024. The Author(s).)

Background & Aims: Patients with inflammatory bowel disease (IBD) frequently develop extraintestinal manifestations (EIMs) that contribute substantially to morbidity. We assembled the largest multicohort data set to date to investigate the clinical, serologic, and genetic factors associated with EIM complications in IBD., Methods: Data were available in 12,083 unrelated European ancestry IBD cases with presence or absence of EIMs (eg, ankylosing spondylitis [ankylosing spondylitis and sacroiliitis], primary sclerosing cholangitis [PSC], peripheral arthritis, and skin and ocular manifestations) across 4 cohorts (Cedars-Sinai Medical Center, National Institute for Diabetes and Digestive and Kidney Diseases IBD Genetics Consortium, Sinai Helmsley Alliance for Research Excellence Consortium, and Risk Stratification and Identification of Immunogenetic and Microbial Markers of Rapid Disease Progression in Children with Crohn's Disease cohort). Clinical and serologic parameters were analyzed by means of univariable and multivariable regression analyses using a mixed-effects model. Within-case logistic regression was performed to assess genetic associations., Results: Most EIMs occurred more commonly in female subjects (overall EIM: P = 9.0E-05, odds ratio [OR], 1.2; 95% CI, 1.1-1.4), with CD (especially colonic disease location; P = 9.8E-09, OR, 1.7; 95% CI, 1.4-2.0), and in subjects who required surgery (both CD and UC; P = 3.6E-19, OR, 1.7; 95% CI, 1.5-1.9). Smoking increased risk of EIMs except for PSC, where there was a "protective" effect. Multiple serologic associations were observed, including with PSC (anti-nuclear cytoplasmic antibody; IgG and IgA, anti-Saccharomyces cerevisiae antibodies; and anti-flagellin) and any EIM (anti-nuclear cytoplasmic antibody; IgG and IgA, anti-Saccharomyces cerevisiae antibodies; and anti-Pseudomonas fluorescens-associated sequence). We identified genome-wide significant associations within major histocompatibility complex (ankylosing spondylitis and sacroiliitis, P = 1.4E-15; OR, 2.5; 95% CI, 2.0-3.1; PSC, P = 2.7E-10; OR, 2.8; 95% CI, 2.0-3.8; ocular, P = 2E-08, OR, 3.6; 95% CI, 2.3-5.6; and overall EIM, P = 8.4E-09; OR, 2.2; 95% CI, 1.7-2.9) and CPEB4 (skin, P = 2.7E-08; OR, 1.5; 95% CI, 1.3-1.8). Genetic associations implicated tumor necrosis factor, JAK-STAT, and IL6 as potential targets for EIMs. Contrary to previous reports, only 2% of our subjects had multiple EIMs and most co-occurrences were negatively correlated., Conclusions: We have identified demographic, clinical, and genetic associations with EIMs that revealed underlying mechanisms and implicated novel and existing drug targets-important steps toward a more personalized approach to IBD management., (Copyright © 2024 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Objective: Th17 and Treg play important roles in AS, but their single and dual TCR pairing types, ratios, and CDR3 characteristics remain unknown., Methods: Single-cell RNA + TCR-seq results from six AS patients were used to cluster T-cell subpopulations and analyze the single and dual TCR T cell ratio, diversity/clonality/overlap of CDR3, and expression of transcription factors., Results: 1. AS patients have about 10% of dual TCR T cells, and SFMC have decreased diversity CDR3 libraries and significant clonal proliferation compared to PBMC. 2. Dual TCR ratio: memory T > naive T; pTh 17 > Th17; Treg /Th17/Th1/EM significantly higher than naive CD4 + T/CM, Pathogenic Th17 cells contain clonally proliferating single TCR and dual TCR cells. 3. The expression of single TCR and dual TCR transcription factors of each T cell subpopulation was basically the same, but there was differential expression of characteristic transcription factors, e.g. Foxp3, CTLA4, STAT5B, IL10RB, LAG3 in dual TCR Treg was higher than that of single TCR Treg; TNFSF10/12, TNFRSF4/14, CCL5, KLRB1 in dual TCR pTh17 were significantly higher than those in single TCR pTh17. 4. Between naive CD4 + T, pTh17, Th1 and Treg, there are partially identity identical tcr paired cells., Conclusions: The high proportion of dual TCR T cells such as pTh17 and Treg in AS and the high expression of some transcription factors suggested a close association with self-response in AS; The overlap of CDR3 between Th1, Th17,pTh17, and Treg in AS suggested that the subpopulations may be differentiated from each other to regulate the inflammatory homeostasis and progression., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Background: Ankylosing spondylitis (AS) with radiographic damage is more prevalent in men than in women. IL-17, which is mainly secreted from peripheral blood mononuclear cells (PBMCs), plays an important role in the development of AS. Its expression is different between male and female. However, it is still unclear whether sex dimorphism of IL-17 contribute to sex differences in AS., Methods: GSE221786, GSE73754, GSE25101, GSE181364 and GSE205812 datasets were collected from the Gene Expression Omnibus (GEO) database. Differential expressed genes (DEGs) were analyzed with the Gene Set Enrichment Analysis (GSEA), Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) methods. CIBERSORTx and EcoTyper algorithms were used for immune infiltration analyses. Machine learning based on the XGBoost algorithm model was used to identify the impact of DEGs. The Connectivity Map (CMAP) database was used as a drug discovery tool for exploring potential drugs based on the DEGs., Results: According to immune infiltration analyses, T cells accounted for the largest proportion of IL-17-secreting PBMCs, and KEGG analyses suggested an enhanced activation of mast cells among male AS patients, whereas the expression of TNF was higher in female AS patients. Other signaling pathways, including those involving metastasis-associated 1 family member 3 (MAT3) or proteasome, were found to be more activated in male AS patients. Regarding metabolic patterns, oxidative phosphorylation pathways and lipid oxidation were significantly upregulated in male AS patients. In XGBoost algorithm model, DEGs including METRN and TMC4 played important roles in the disease process. we integrated the CMAP database for systematic analyses of polypharmacology and drug repurposing, which indicated that atorvastatin, famciclocir, ATN-161 and taselisib may be applicable to the treatment of AS., Conclusions: We analyzed the sex dimorphism of IL-17-secreting PBMCs in AS. The results showed that mast cell activation was stronger in males, while the expression of TNF was higher in females. In addition, through machine learning and the CMAP database, we found that genes such as METRN and TMC4 may promote the development of AS, and drugs such as atorvastatin potentially could be used for AS treatment., (© 2024. The Author(s).)

The core components of the Hippo signaling pathway encompass upstream regulatory molecules, core kinase cascade complexes, and downstream transcriptional regulation complexes. This pathway modulates cellular behaviors by influencing the effector molecules of its core components and plays a pivotal role in immune regulation. Effector molecules,such as Yes-associated protein (YAP), transcriptional coactivator with PDZ-binding motif (TAZ), transcriptional enhanced associate domain transcriptional factor (TEAD), monopolar spindle-one binder (MOB1), large tumor suppressor (LATS), can stimulate fibroblast-like synovial cell migration and invasion in rheumatoid arthritis, regulate osteoarthritis disease progression, promote pathological new bone formation in ankylosing spondylitis, sustain submandibular gland development while delaying Sjogren's syndrome progression, mediate alpha-smooth muscle actin in systemic sclerosis, and refine the regulation of target genes associated with pulmonary fibrosis. This article provides an overview of the regulatory mechanisms involving Hippo signaling pathway-related effector molecules in the pathogenesis and progression of rheumatic immune system diseases, to serve as a reference for exploring novel therapeutic targets of rheumatic immune system diseases.

Objective: Immune checkpoints have emerged as promising therapeutic targets for autoimmune diseases. However, the specific roles of immune checkpoints in the pathophysiology of ankylosing spondylitis (AS) remain unclear., Methods: Hip ligament samples were obtained from two patient groups: those with AS and femoral head deformity, and those with femoral head necrosis but without AS, undergoing hip arthroplasty. Label-Free Quantification (LFQ) Protein Park Analysis was used to identify the protein composition of the ligaments. Peripheral blood samples of 104 AS patients from public database were used to validate the expression of key proteins. KEGG, GO, and GSVA were employed to explore potential pathways regulated by immune checkpoints in AS progression. xCell was used to calculate cell infiltration levels, LASSO regression was applied to select key cells, and the correlation between immune checkpoints and immune cells was analyzed. Drug sensitivity analysis was conducted to identify potential therapeutic drugs targeting immune checkpoints in AS. The expression of key genes was validated through immunohistochemistry (IHC)., Results: HLA-DMB and HLA-DPA1 were downregulated in the ligaments of AS and this has been validated through peripheral blood datasets and IHC. Significant differences in expression were observed in CD8 + Tcm, CD8 + T cells, CD8 + Tem, osteoblasts, Th1 cells, and CD8 + naive T cells in AS. The infiltration levels of CD8 + Tcm and CD8 + naive T cells were significantly positively correlated with the expression levels of HLA-DMB and HLA-DPA1. Immune cell selection using LASSO regression showed good predictive ability for AS, with AUC values of 0.98, 0.81, and 0.75 for the three prediction models, respectively. Furthermore, this study found that HLA-DMB and HLA-DPA1 are involved in Th17 cell differentiation, and both Th17 cell differentiation and the NF-kappa B signaling pathway are activated in the AS group. Drug sensitivity analysis showed that AS patients are more sensitive to drugs such as doramapimod and GSK269962A., Conclusion: Immune checkpoints and immune cells could serve as avenues for exploring diagnostic and therapeutic strategies for AS., (© 2024. The Author(s).)

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.

Background: Ankylosing spondylitis (AS) is a chronic autoimmune arthritis that mainly affects spine joints. To date, the pathogenesis of AS remains unclear, although immune cells and innate immune response cytokines have been suggested to be crucial players., Methods: By adopting a single-cell RNA sequencing approach in the AS cynomolgus model, we profiled and characterized PBMC proportions along disease progression., Results: Here, our primary focus was on the activation of an immune cascade-initiating lymphocyte subtype known as CD4 + CXCR5 + T follicular helper (Tfh) cells. These Tfhs demonstrated a localized residence in AS bone lesion as an ectopic lymphoid structure. Moreover, Tfhs would serve as an upstream initiator for a pro-angiogenic cascade. Then, an expansion in CD14 + monocytes and DC cells subsets resulted in enhanced expression of angiogenesis genes in these AS cynomolgus monkeys. With a confirmed higher abundance of TNF-α accompanying H-type vascular invasion in the osteophytic region, pronounced expansion of Tfhs at such lesion site signaling for monocytes and DCs intrusion is considered as the prelude to the characteristic angiogenic bony outgrowth in AS known as syndesmophytes., Conclusions: We explored the intimate relationship between local inflammation and bone formation in AS from the perspective of nascent vascularisation. Hence, our study lays the foundation for elucidating a unified AS pathogenesis through the immune-angiogenesis-osteogenesis axis., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Objectives: Various aspects of the concept of Vyadhikshamatva have been thoroughly explored, highlighting its profound significance in resisting disease manifestation, particularly in the context of Ankylosing spondylitis. Investigated the relationship between HLA-B27 and Ankylosing spondylitis (AS) by examining current knowledge and hypotheses Furthermore, efforts were made to portray the influence of prakruti (constitution) and balam (strength) on disease manifestation and progression., Methods: Ayurvedic literature along with contemporary research works was analyzed for correlating various aspects like vyadhikshamatva,oja (The final essence of all body elements), and balam along with their influence on the defensive mechanism of the body. A thorough literature search was conducted to explore the strong association between HLA-B27 and AS by examining various hypotheses like the Arthritogenic peptide hypothesis, the Misfolding hypothesis, the Surface Homodimer hypothesis, and the β2 microglobulin hypothesis that attempts to explain the pathogenic role of HLA-B27 in AS. Alongside classical Ayurvedic texts, databases like PubMed and Scopus were searched using keywords such as Immunity, Ankylosing spondylitis, Vyadhikshamatva, HLA-B27, Balam , and Autoimmune disorder with the help of Boolean operators., Results: The review highlighted the critical role of Vyadhikshamatva in disease prevention, particularly in influencing the manifestation of conditions like AS despite genetic predisposition (HLA-B27). Further, the understanding of the Ayurvedic concepts can clearly explain the conflict that has arisen in the determination of the positive HLAB27 gene in Ankylosing Spondylitis as a definite diagnosing criteria., Conclusions: This comprehensive understanding will uplift the need for personalized medicine in disease management. Further research must be needed to understand the interaction between genetic factors (HLAb27), individual constitution, and their vyadikshamatva ., (© 2024 Walter de Gruyter GmbH, Berlin/Boston.)

The gut microbiota plays a pivotal role in regulating host immunity, and dysregulation of this interaction is implicated in autoimmune and inflammatory diseases, including spondyloarthritis (SpA). This review explores microbial dysbiosis and altered metabolic function observed in various forms of SpA, such as ankylosing spondylitis (AS), psoriatic arthritis (PsA), acute anterior uveitis (AAU), and SpA-associated gut inflammation. Studies on animal models and clinical samples highlight the association between gut microbial dysbiosis, metabolic perturbations and immune dysregulation in SpA pathogenesis. These studies have received impetus through next-generation sequencing methods, which have enabled the characterization of gut microbial composition and function, and host gene expression. Microbial/metabolomic studies have revealed potential biomarkers and therapeutic targets, such as short-chain fatty acids, and tryptophan metabolites, offering insights into disease mechanisms and treatment approaches. Further studies on microbial function and its modulation of the immune response have uncovered molecular mechanisms underlying various SpA. Understanding the complex interplay between microbial community structure and function holds promise for improved diagnosis and management of SpA and other autoimmune disorders., Competing Interests: Declaration of competing interest None., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Human leukocyte antigen (HLA) class I association is a well-established feature of common and uncommon inflammatory diseases, but it is unknown whether it impacts the pathogenesis of these disorders. The "arthritogenic peptide" hypothesis proposed initially for HLA-B27-associated ankylosing spondylitis (AS) seems the most intuitive to serve as a model for other HLA class I-associated diseases, but evidence supporting it has been scarce. Recent technological advances and the discovery of epistatic relationships between disease-associated HLA class I and endoplasmic reticulum aminopeptidase (ERAP) coding variants have led to the generation of new data and conceptual approaches to the problem requiring its re-examination. Continued success in these endeavors holds promise to resolve a Gordian Knot in human immunobiology. It may ultimately benefit patients by enabling the development of new therapies and precision tools for assessing disease risk and predicting treatment responses., Competing Interests: Declaration of competing interest We have no disclosures relevant to this article to report., (Copyright © 2024. Published by Elsevier Ltd.)

Epigenetic processes, including non-coding RNA, histone modifications, and DNA methylation, play a vital role in connecting the environment to the development of a disorder, especially when there is a favorable genetic background. Ankylosing Spondylitis (AS) is a chronic type of spinal arthritis that highlights the significance of epigenetics in diseases related to autoimmunity and inflammation. MicroRNAs (miRNAs) are small non-coding RNAs that are involved in both normal and aberrant pathological and physiological gene expression. This study focuses on the pathophysiological pathways to clarify the role of miRNAs in AS. We have conducted a thorough investigation of the involvement of miRNAs in several processes, including inflammation, the production of new bone, T-cell activity, and the regulation of pathways such as BMP, Wnt, and TGFβ signaling. Undoubtedly, miRNAs play a crucial role in enhancing our comprehension of the pathophysiology of AS, and their promise as a therapeutic strategy is quickly expanding., Competing Interests: Declaration of competing interest The authors declare they have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Objectives: Gender has been shown to impact disease expression in ankylosing spondylitis (AS) and Th17 cells play a key role in AS pathogenesis. To better understand what Th17-associated immune pathways are different between men and women, we compared the transcriptome of IL-17-enriched peripheral blood mononuclear cells (PBMCs) in male and female AS patients, with a particular focus on inflammatory cytokine genes., Methods: PBMCs were collected from 10 female and 11 male AS patients at the Clinical Research Unit of MetroHealth Medical Center. IL-17-enriched PBMCs were isolated and stimulated with CytoStim. RNA-sequencing (RNA-seq) was performed on the samples, and the data were analysed using iPathwayGuide. Inflammatory markers and genes related to Th17 differentiation and function were identified based on previous studies., Results: RNA-seq identified 12,893 genes with 2,851 genes with p-values <0.05 with distinct patterns of gene expression between male and female AS patients. TGF-β, PGE2, and S100 proteins were significantly upregulated in males. Levels of IL-12B, a Th17 inducer, were lower in males compared to females. Additionally, receptors of IL-6, 12, 23, TGF-β, and PGE2 were downregulated in males, except for IL-17RC, which was upregulated. Genes involved in Th17 differentiation showed differential expression between genders, with elevated expression of BATF, SOCS1, NKD2, and ARID5A in men and decreased expression of FOXO1., Conclusions: Transcriptomic analysis revealed that male AS patients exhibit distinct expression patterns of IL-17 pro-inflammatory genes, which may contribute to the phenotypic differences observed between genders in AS.

Aim: This study aimed to construct prognostic mathematical models utilizing multifactorial regression analysis to assess the risk of developing drug-induced neutralizing antibodies in patients with rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis treated with tumor necrosis factor alpha blockers., (This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Objective: Previous research has partially revealed distinct gut microbiota in ankylosing spondylitis (AS). In this study, we performed non-targeted fecal metabolomics in AS in order to discover the microbiome-metabolome interface in AS. Based on prospective cohort studies, we further explored the impact of the tumor necrosis factor inhibitor (TNFi) on the gut microbiota and metabolites in AS., Methods: To further understand the gut microbiota and metabolites in AS, along with the influence of TNFi, we initiated a prospective cohort study. Fecal samples were collected from 29 patients with AS before and after TNFi therapy and 31 healthy controls. Metagenomic and metabolomic experiments were performed on the fecal samples; moreover, validation experiments were conducted based on the association between the microbiota and metabolites., Results: A total of 7,703 species were annotated using the metagenomic sequencing system and by profiling the microbial community taxonomic composition, while 50,046 metabolites were identified using metabolite profiling. Differential microbials and metabolites were discovered between patients with AS and healthy controls. Moreover, TNFi was confirmed to partially restore the gut microbiota and the metabolites. Multi-omics analysis of the microbiota and metabolites was performed to determine the associations between the differential microbes and metabolites, identifying compounds such as oxypurinol and biotin, which were correlated with the inhibition of the pathogenic bacteria Ruminococcus gnavus and the promotion of the probiotic bacteria Bacteroides uniformis . Through experimental studies, the relationship between microbes and metabolites was further confirmed, and the impact of these two types of microbes on the enterocytes and the inflammatory cytokine interleukin-18 (IL-18) was explored., Conclusion: In summary, multi-omics exploration elucidated the impact of TNFi on the gut microbiota and metabolites and proposed a novel therapeutic perspective: supplementation of compounds to inhibit potential pathogenic bacteria and to promote potential probiotics, therefore controlling inflammation in AS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Lai, Tang, Luo, Zheng, Zhang, Wang, Yu and Yang.)

Background: Ankylosing spondylitis (AS) is an autoimmune disease that affects millions of individuals. Immune cells have been recognized as having a crucial role in the pathogenesis of AS. However, their relationship has not been fully explored., Methods: We chose to employ Mendelian randomization (MR) to investigate the potential correlation between immune cells and AS. We sourced the data on immune cells from the latest genome-wide association studies (GWASs). We obtained data on AS from the FinnGen consortium. Our comprehensive univariable MR analysis covered 731 immune cells to explore its potential causal relationship with AS. The primary analysis method was inverse-variance weighted (IVW). Additionally, we used Cochran's Q test and the MR-Egger intercept test to assess the presence of pleiotropy and heterogeneity. We examined whether our results could be influenced by individual single-nucleotide polymorphisms (SNPs) using the leave-one-out test. We conducted a bidirectional MR to investigate the reverse relationship. We also applied multivariable MR to decrease the potential influence between the immune cells., Results: Overall, our univariable MR analysis revealed eight immune cells associated with AS. Among these, four immune cells contributed to an increased risk of AS, while four immune cells were identified as protective factors for AS. However, the Bonferroni test confirmed only one risk factor and one protective factor with a significance level of p < 6.84E-05. CD8 on effector memory CD8 + T cell could increase the risk of AS (p: 1.2302E-05, OR: 2.9871, 95%CI: 1.8289-4.8786). HLA DR on CD33 dim HLA DR + CD11b + could decrease the risk of AS (p: 1.2301E-06, OR: 0.5446, 95%CI: 0.4260-0.6962). We also identified a bidirectional relationship between CD4 on CD39 + activated CD4 regulatory T cells and AS utilizing the bidirectional MR. To address potential confounding among immune cells, we employed multivariable MR analysis, which revealed that only one immune cell had an independent effect on AS. HLA DR on CD33 dim HLA DR + CD11b + could decrease the risk of AS (p: 2.113E-06, OR: 0.0.5423, 95%CI: 0.4210-0.6983). Our findings were consistently stable and reliable., Conclusions: Our findings indicated a potential link between immune cells and AS, which could provide a new idea for future research. Nevertheless, the specific underlying mechanisms require further exploration., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Qin, Yu, Deng, Zhang, Chen, Wang, Hu, Lei, Yan and Cheng.)

Bacillus anthracis is the bacterium responsible for causing the zoonotic disease called anthrax. The disease presents itself in different forms like gastrointestinal, inhalation, and cutaneous. Bacterial spores are tremendously adaptable, can persist for extended periods and occasionally endanger human health. The Anthrax Toxin Receptor-2 ( ANTXR2 ) gene acts as membrane receptor and facilitates the entry of the anthrax toxin into host cells. Additionally, mutations in the ANTXR2 gene have been linked to various autoimmune diseases, including Hyaline Fibromatosis Syndrome (HFS), Ankylosing Spondylitis (AS), Juvenile Hyaline Fibromatosis (JHF), and Infantile Systemic Hyalinosis (ISH). This study delves into the genetic landscape of ANTXR2 , aiming to comprehend its associations with diverse disorders, elucidate the impacts of its mutations, and pinpoint minimal non-pathogenic mutations capable of reducing the binding affinity of the ANTXR2 gene with the protective antigen. Recognizing the pivotal role of single-nucleotide polymorphisms (SNPs) in shaping genetic diversity, we conducted computational analyses to discern highly deleterious and tolerated non-synonymous SNPs (nsSNPs) in the ANTXR2 gene. The Mutpred2 server determined that the Arg465Trp alteration in the ANTXR2 gene leads to altered DNA binding ( p = 0.22) with a probability of a deleterious mutation of 0.808; notably, among the identified deleterious SNPs, rs368288611 (Arg465Trp) stands out due to its significant impact on altering the DNA-binding ability of ANTXR2 . We propose these SNPs as potential candidates for hypertension linked to the ANTXR2 gene, which is implicated in blood pressure regulation. Noteworthy among the tolerated substitutions is rs200536829 (Ala33Ser), recognized as less pathogenic; this highlights its potential as a valuable biomarker, potentially reducing side effects on the host while also reducing binding with the protective antigen protein. Investigating these SNPs holds the potential to correlate with several autoimmune disorders and mitigate the impact of anthrax disease in humans.

Spondyloarthritis (SpA) constitute a group of chronic inflammatory immune-mediated rheumatic diseases characterized by genetic, clinical, and radiological features. Recent efforts have concentrated on identifying biomarkers linked to axial SpA associated with inflammatory bowel disease (IBD), offering predictive insights into disease onset, activity, and progression. Genetically, the significance of the HLA-B27 antigen is notably diminished in ankylosing spondylitis (AS) associated with IBD, but is heightened in concurrent sacroiliitis. Similarly, certain polymorphisms of endoplasmic reticulum aminopeptidase (ERAP-1) appear to be involved. Carriage of variant NOD2/CARD15 polymorphisms has been demonstrated to correlate with the risk of subclinical intestinal inflammation in AS. Biomarkers indicative of pro-inflammatory activity, including C-reactive protein (CRP) along with erythrocyte sedimentation rate (ESR), are among the consistent predictive biomarkers of disease progression. Nevertheless, these markers are not without limitations and exhibit relatively low sensitivity. Other promising markers encompass IL-6, serum calprotectin (s-CLP), serum amyloid (SAA), as well as biomarkers regulating bone formation such as metalloproteinase-3 (MMP-3) and Dickkopf-related protein 1 (DKK-1). Additional candidate indicators of structural changes in SpA patients include matrix metalloproteinase-3 (MMP-3), vascular endothelial growth factor (VEGF), tenascin C (TNC), and CD74 IgG. Fecal caprotein (f-CLP) levels over long-term follow-up of AS patients have demonstrated predictive value in anticipating the development of IBD. Serologic antibodies characteristic of IBD (ASCA, ANCA) have also been compared; however, results exhibit variability. In this review, we will focus on biomarkers associated with both axial SpA and idiopathic intestinal inflammation, notably enteropathic spondyloarthritis., Competing Interests: Declaration of Competing Iinterest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

Protein posttranslational modifications can break tolerance to the self-proteome.

Human leucocyte antigen B*27 (HLA-B*27) is strongly associated with inflammatory diseases of the spine and pelvis (for example, ankylosing spondylitis (AS)) and the eye (that is, acute anterior uveitis (AAU)) 1 . How HLA-B*27 facilitates disease remains unknown, but one possible mechanism could involve presentation of pathogenic peptides to CD8 + T cells. Here we isolated orphan T cell receptors (TCRs) expressing a disease-associated public β-chain variable region-complementary-determining region 3β (BV9-CDR3β) motif 2-4 from blood and synovial fluid T cells from individuals with AS and from the eye in individuals with AAU. These TCRs showed consistent α-chain variable region (AV21) chain pairing and were clonally expanded in the joint and eye. We used HLA-B*27:05 yeast display peptide libraries to identify shared self-peptides and microbial peptides that activated the AS- and AAU-derived TCRs. Structural analysis revealed that TCR cross-reactivity for peptide-MHC was rooted in a shared binding motif present in both self-antigens and microbial antigens that engages the BV9-CDR3β TCRs. These findings support the hypothesis that microbial antigens and self-antigens could play a pathogenic role in HLA-B*27-associated disease., (© 2022. The Author(s), under exclusive licence to Springer Nature Limited.)

Ankylosing spondylitis (AS) belongs to a group of diseases, called spondyloarthropathies (SpA), that are strongly associated with the genetic marker HLA-B27. AS is characterized by inflammation of joints and primarily affects the spine. Over 160 subtypes of HLA-B27 are known, owing to high polymorphism. Some are strongly associated with disease (e.g., B*2704), whereas others are not (e.g., B*2709). Misfolding of HLA-B27 molecules [as dimers, or as high-molecular-weight (HMW) oligomers] is one of several hypotheses proposed to explain the link between HLA-B27 and AS. Our group has previously established the existence of HMW species of HLA-B27 in AS patients. Still, very little is known about the mechanisms underlying differences in pathogenic outcomes of different HLA-B27 subtypes. We conducted a proteomics-based evaluation of the differential disease association of HLA B*2704 and B*2709, using stable transfectants of genes encoding the two proteins. A clear difference was observed in protein clearance mechanisms: whereas unfolded protein response (UPR), autophagy, and aggresomes were involved in the degradation of B*2704, the endosome-lysosome machinery was primarily involved in B*2709 degradation. These differences offer insights into the differential disease association of B*2704 and B*2709., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Thakur and Luthra-Guptasarma.)

Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Extensive research into ankylosing spondylitis (AS) has suggested the major role of genetics, immune reactions, and the joint-gut axis in its etiology, although an ultimate consensus does not yet exist. The available evidence indicates that both autoinflammation and T-cell-mediated autoimmune processes are actively involved in the disease process of AS. So far, B cells have received relatively little attention in AS pathogenesis; this is largely due to a lack of conventional disease-defining autoantibodies. However, against prevailing dogma, there is a growing body of evidence suggestive of B cell involvement. This is illustrated by disturbances in circulating B cell populations and the formation of auto-reactive and non-autoreactive antibodies, along with B cell infiltrates within the axial skeleton of AS patients. Furthermore, the depletion of B cells, using rituximab, displayed beneficial results in a subgroup of patients with AS. This review provides an overview of our current knowledge of B cells in AS, and discusses their potential role in its pathogenesis. An overarching picture portrays increased B cell activation in AS, although it is unclear whether B cells directly affect pathogenesis, or are merely bystanders in the disease process.

Background: Ankylosing spondylitis (AS) is a type of inflammatory arthritis that affects primarily the spine. There is a strong association of the HLA-B*27 allele with AS pathogenesis, but recent studies have demonstrated the participation of ERAP1 gene in the genetic susceptibility. The aim of this study was to determine whether HLA-B tag-single nucleotide polymorphisms (SNPs) and ERAP1-related genetic variations associated with AS have equal or similarly performance in patients´ screening compared to HLA-B*27 standard genotyping in Mexican population., Methods and Results: Genomic DNA from patients with AS and population-based controls from Mexico City was analyzed for five single nucleotide polymorphisms (SNPs): rs4349859, rs13202464, rs116488202, tagging HLA-B*27; and rs30187 and rs27044 in ERAP1 gene. TaqMan genotype assay method was used for SNPs genotyping. We found a significant association between AS and the heterozygote genotypes and minor alleles of the HLA-B*27 tag-SNPs, as well as for their haplotypes. With respect to ERAP1 polymorphisms, no significant associations were observed (p > 0.05). The sensitivity and specificity analysis showed values of 0.96 and 1.00 for the rs4349859 SNP, and 0.96 and 0.94 for the rs116488202 SNP, respectively, in detecting HLA-B*27 compared to the B27 test as the gold standard., Conclusions: HLA-B*27 tag-SNPs are associated with AS susceptibility; furthermore, the rs4349859 SNP by its own have an outstanding performance in detecting HLA-B*27 and therefore can be proposed as screening marker in the identification of HLA-B*27 in our population., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Objective: Genetic studies on ankylosing spondylitis (AS) have identified more than 100 pathogenic genes. Building a bridge between these genes and biologically targeted therapies is the current research hotspot., Methods: We integrated single-cell assaying transposase-accessible chromatin sequencing (scATAC-seq) and single-cell RNA sequencing (scRNA-seq) to explore the key genes and related mechanisms associated with AS pathogenesis., Results: We identified 18 cell types in peripheral mononuclear cells from patients with AS and normal controls and summarized the cell-type-specific abnormal genes by scRNA-seq. Interestingly, we found that the pathogenic gene NFKB involved in AS progression originated from CD8+ T cells. Moreover, we observed an abnormal tumor TNF pathway mediated by abnormal expression of TNF , NFKB , FOS , JUN , and JUNB , and scATAC-seq results confirmed the abnormal accessible binding sites of transcriptional factors FOS , JUN , and JUNB . The final magnetic bead sorting and quantitative real-time PCR(RT-qPCR) confirmed that NFKB , FOS , JUN , and JUNB in CD8+ T cells differed in the AS group., Conclusions: Our results revealed a possible mechanism by which NFKB abnormally regulates FOS , JUN , and JUNB and drives AS progression, providing a novel perspective from a single cell point of view in AS., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Xu, Yu, Liu, Wu, Zhang, Cai, Hong, Liu, Tang and Dai.)

TNF is important in immune-mediated inflammatory diseases, including spondyloarthritis (SpA). Transgenic (tg) mice overexpressing transmembrane TNF (tmTNF) develop features resembling human SpA. Furthermore, both tmTNF tg mice and SpA patients develop ectopic lymphoid aggregates, but it is unclear whether these contribute to pathology. Therefore, we characterized the lymphoid aggregates in detail and studied potential alterations in the B and T cell lineage in tmTNF tg mice. Lymphoid aggregates developed in bone marrow (BM) of vertebrae and near the ankle joints prior to the first SpA features and displayed characteristics of ectopic lymphoid structures (ELS) including presence of B cells, T cells, germinal centers, and high endothelial venules. Detailed flow cytometric analyses demonstrated more germinal center B cells with increased CD80 and CD86 expression, along with significantly more T follicular helper, T follicular regulatory, and T regulatory cells in tmTNF tg BM compared with non-tg controls. Furthermore, tmTNF tg mice exhibited increased IgA serum levels and significantly more IgA + plasma cells in the BM, whereas IgA + plasma cells in the gut were not significantly increased. In tmTNF tg × TNF-RI -/- mice, ELS were absent, consistent with reduced disease symptoms, whereas in tmTNF tg × TNF-RII -/- mice, ELS and clinical symptoms were still present. Collectively, these data show that tmTNF overexpression in mice results in osteitis and ELS formation in BM, which may account for the increased serum IgA levels that are also observed in human SpA. These effects are mainly dependent on TNF-RI signaling and may underlie important aspects of SpA pathology., (Copyright © 2021 by The American Association of Immunologists, Inc.)

Tumor necrosis factor- α (TNF- α ) inhibitors are the main types of biological conventional synthetic disease-modifying antirheumatic drugs and have efficacy in treating ankylosing spondylitis (AS) which is not sensitive for nonsteroidal anti-inflammatory drug. However, the impact of TNF- α inhibitors on immune cells in patients with AS is still clearly undefined, and the impact of immune cells on treatment response is also largely elusive. This study is aimed at evaluating the longitudinal changes of circulating immune cells after anti-TNF- α therapy and their associations with treatment response in AS patients. Thirty-five AS patients receiving the treatment of anti-TNF- α therapy were included into this prospective observational study. The frequencies of immune cells including Th1, Th2, Th17, regulatory T cell (Treg), T follicular helper cell (Tfh), and regulatory B cell (Breg) in the peripheral blood were measured by flow cytometry at baseline and 4 time points after therapy. The difference in the circulating immune cells between responders and nonresponders was compared. This study suggested that anti-TNF- α therapy could significantly reduce circulating proinflammatory immune cells such as Th17 and Tfh, but significantly increased the percentages of circulating Treg and Breg. Moreover, circulating Breg may be a promising predictor of response to anti-TNF- α therapy in AS patients., Competing Interests: All authors declare that they have no conflict of interest in this paper., (Copyright © 2021 Rongjuan Chen et al.)

Background: Various studies reported that increased proinflammatory cytokines in patients with ankylosing spondylitis (AS). Proinflammatory cytokines can affect the expression of various kynurenine pathway enzymes and therefore lead to metabolic changes that can affect the inflammatory response and immunity. Our aim was to measure serum levels of kynurenine pathway metabolites in patients with AS., Methods: The study included 85 patients with AS and 50 healthy volunteers. Serum tryptophan, kynurenine, kynurenic acid, 3-hydroxyanthranilic acid, 3-hydroxykynurenine, quinolinic acid concentrations were measured with tandem mass spectrometry. In addition, participants were divided into four groups according to the treatment regimen: TNF-α inhibitor group, conventional therapy group, control group and newly diagnosed AS group. These groups were compared in terms of kynurenine pathways metabolites, interleukin 6 (IL-6), erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels., Results: Serum tryptophan, kynurenic acid, 3-hydroxykynurenine levels were significantly decreased (p < 0.05) in both AS groups compared to the control group, while the levels of kynurenine, quinolinic acid, CRP, ESR, and IL-6 were higher (p < 0.05). The Kynurenine/Tryptophan ratio and CRP levels of the conventional therapy and anti-TNF therapy group were significantly lower than the newly diagnosed AS patients (p < 0.05)., Conclusion: As a result of our study, we found that altered kynurenine pathway metabolism in patients with AS. Conventional therapy and anti-TNF-α therapy are effective in reducing the Kynurenine/Tryptophan ratio and CRP levels, although the effect of both treatments on other metabolites appears to be limited., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: The systemic immune-inflammation index (SII) is a recently developed indicator for systemic inflammatory response. We aimed to explore the association between SII and disease activity in patients with ankylosing spondylitis (AS)., Methods: This retrospective study included 136 patients with AS and 63 healthy controls. Patients were divided into two groups according to Bath Ankylosing Spondylitis Disease Activity Index (BASDAI); active group (n = 60) and remission group (n = 76). Clinical, laboratory, and demographic characteristics were recorded. Spearman's correlation analysis was used to determine correlations of SII with C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), and BASDAI in AS patients. Binary logistic regression analysis was used to assess risk factors for AS disease activity. Receiver operating characteristic curve analysis was used to evaluate the diagnostic value of SII and the above variables for the active group compared with the remission group., Results: Systemic immune-inflammation index levels were higher in AS patients than in healthy controls (p < 0.001). SII levels were higher in the active group than in the remission group (p < 0.001). For patients with AS, SII correlated positively with CRP (r s  = 0.483, p < 0.001), ESR (r s  = 0.374, p < 0.001), and BASDAI (r s  = 0.667, p < 0.001). SII (OR = 1.009, 95% CI = 1.006-1.012, p < 0.001) was an independent risk factor affecting AS disease activity. The specificity and sensitivity of SII using a cutoff value of 513.2 were 83.33% and 86.84%, respectively, for the active group., Conclusion: Systemic immune-inflammation index was increased in AS. SII may be a novel indicator for monitoring AS disease activity., (© 2021 The Authors. Journal of Clinical Laboratory Analysis published by Wiley Periodicals LLC.)

Interleukin 37 (IL-37) is a newly identified cytokine that belongs to the IL-1 family. Unlike other members of the IL-1 family, it has been demonstrated that IL-37 possesses anti-inflammatory characteristics in both innate and acquired immune responses. Recently, significant progress has been made in understanding the role of IL-37 in inflammatory signaling pathways. Meanwhile, IL-37 has also attracted more and more attention in bone homeostasis and inflammatory bone diseases. The latest studies have revealed that IL-37 palys an essential role in the regulation of osteoclastogenesis and osteoblastogenesis. The levels of IL-37 are abnormal in patients with inflammatory bone diseases such as rheumatoid arthritis (RA), osteoarthritis (OA), ankylosing spondylitis (AS), and periodontitis. In addition, in vivo studies have further confirmed that recombinant IL-37 treatment displayed therapeutic potential in these diseases. The present review article aims to provide an overview describing the biological functions of IL-37 in bone homeostasis and inflammatory bone diseases, thus shedding new light on a novel therapeutic strategy in the future., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Ankylosing spondylitis (AS) is inflammatory arthritis predominantly affecting the spine, which is involved in the disorders of both immune and skeletal systems. The exact pathogenesis of AS is not fully understood. Osteoimmunology is a new subject of study in inflammatory arthritis, in particular the pathogenic events involved in the cross-regulation of both skeletal and immune systems. In this review, we discuss osteoimmunological and pathological changes of AS in the spine that are characterized by altered osteogenesis and osteolytic bone destruction, accompanied by the changes of the immune system. It was revealed that bone cells like mesenchymal stem cells, osteoblast, and osteoclast in crossing talking with immune cells such as T cells, B cells coregulate to the pathogenesis of AS. Further, an array of cytokines and molecules expressed by both skeletal and immune systems contribute to these complex interplays. Understanding the cellular and molecular mechanisms underlying the pathogenesis of AS will lay a foundation for the exploration of the potential new treatment to AS., (© 2021 Wiley Periodicals LLC.)

Ankylosing spondylitis is a complicated consequence of genetic predisposition and environmental factors. Enthesitis is believed to be the hallmark of ankylosing spondylitis, and the chronic inflammatory state of this disease is perpetuated by the disturbances of both the innate immune system and the acquired immune system. To clarify the alteration of immune system in patients with AS, we conducted a meta-analysis concerning the proportions of major lymphocyte subsets in the peripheral blood of AS patients. We systematically searched PubMed and China National Knowledge Infrastructure (CNKI) for articles related to this subject. A total of 95 articles involving 4,020 AS patients and 3,065 healthy controls were included in the analysis. This meta-analysis is performed on R platform using R package "meta", and Egger's tests were used to determine the presence of publication bias. Results showed that the percentages of T cells, NK cells and NKT cells were not significantly different between AS patients and healthy controls, but B cells were significantly increased. Among the subsets of T cells, the proportions of CD4+ T cells, Th17 cells, Tfh cells as well as Th1/Th2 ratio were significantly increased, while Tregs were significantly decreased. Subgroup analysis showed that the proportions of Th17 among both PBMCs, T cells and CD4+ T cells were significantly elevated, while Tregs were only significantly lower in PBMCs. Subgroup analysis also demonstrated that Tregs defined by "CD4+CD25+FoxP3+", "CD4+CD25+CD127low"or "CD4+CD25+CD127-"were significantly downregulated, indicating that the selection of markers could be critical. Further study is warranted in order to elucidate the complicated interactions between different lymphocyte subsets in AS patients. This study implied that the disequilibrium between Th17 and Tregs, as well as between Th1 and Th2 could contribute to the pathogenesis of ankylosing spondylitis, further cementing the understanding that ankylosing spondylitis is a consequence of disrupted balance of innate immune system and acquired immune system., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Liu, Liu, Lin and Gu.)

Ankylosing spondylitis (AS) is a chronic autoimmune inflammatory disease that mainly affects the axial and sacroiliac joints. Single-nucleotide polymorphisms (SNPs) in genes encoding cytokines have been associated with AS, which can interfere with the production of these cytokines and contribute to the development of AS. In order to contribute to a better understanding of the pathology of AS, our objective was to investigate a possible association of the IL10 -1082 A>G SNP (rs1800896) with AS and to evaluate the serum levels of TNF-α, IL-10, IL-17A, and IL-17F in AS patients and controls comparing them with their respective genotypes ( TNF rs1800629, IL10 rs1800896, IL17A rs2275913, and IL17F rs763780). Patients and controls were selected from the Maringá University Hospital and the Maringá Rheumatism Clinic, in Paraná State, Southern Brazil, and they were diagnosed by the ASAS Criteria. In total, 149 patients and 169 controls were genotyped for the IL10 -1082 A>G polymorphism using a polymerase chain reaction with sequence specific primers (PCR-SSP); the measurement of TNF-α serum levels was performed through the immunofluorimetric test and IL-10, IL-17A, and IL-17F using an ELISA test. There was a high frequency of the IL10 -1082 G allele in AS patients compared with controls with an odds ratio of 1.83 and 95% confidence interval of 1.32 to 2.54, and a significant difference in the genotype frequencies of the IL10 -1082 A/G+G/G between patients and healthy controls, with an odds ratio of 3.01 and 95% confidence interval of 1.75 to 5.17. In addition, increased serum levels of IL-10 were observed in AS patients: 2.38 (IQR, 0.91) pg/ml compared with controls 1.72 (IQR 0.93) pg/ml (P = 0.01). Our results also showed an association between IL17F rs763780 C/T+T/T genotypes and increased serum levels of IL-17F in patients with AS and also in controls. We can conclude that patients with the A/G and G/G genotypes for -1082 A>G (rs1800896) in the IL10 gene are three times more likely to develop AS, that the serum level of IL-10 was higher in AS patients and that the IL17F rs763780 polymorphism can affect the levels of IL-17F in the serum of patients and controls in the same way., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Braga, Lara-Armi, Neves, Rocha-Loures, Terron-Monich, Bahls-Pinto, de Lima Neto, Zacarias, Sell and Visentainer.)

Ankylosing spondylitis (AS) is a chronic inflammatory disorder of unknown aetiology. Unlike other systemic autoimmune diseases, in AS, the innate immune system has a dominant role characterized by aberrant activity of innate and innate-like immune cells, including γδ T cells, group 3 innate lymphoid cells, neutrophils, mucosal-associated invariant T cells and mast cells, at sites predisposed to the disease. The intestine is involved in disease manifestations, as it is at the forefront of the interaction between the mucosal-associated immune cells and the intestinal microbiota. Similarly, biomechanical factors, such as entheseal micro-trauma, might also be involved in the pathogenesis of the articular manifestation of AS, and sentinel immune cells located in the entheses could provide links between local damage, genetic predisposition and the development of chronic inflammation. Although these elements might support the autoinflammatory nature of AS, studies demonstrating the presence of autoantibodies (such as anti-CD74, anti-sclerostin and anti-noggin antibodies) and evidence of activation and clonal expansion of T cell populations support an autoimmune component to the disease. This Review presents the evidence for autoinflammation and the evidence for autoimmunity in AS and, by discussing the pathophysiological factors associated with each, aims to reconcile the two hypotheses.

Objective: We undertook this study to evaluate the activation and functional relevance of inflammasome pathways in ankylosing spondylitis (AS) patients and rodent models and their relationship to dysbiosis., Methods: An inflammasome pathway was evaluated in the gut and peripheral blood from 40 AS patients using quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), flow cytometry, and confocal microscopy, and was compared to that of 20 healthy controls and 10 patients with Crohn's disease. Bacteria was visualized using silver stain in human samples, and antibiotics were administered to HLA-B27-transgenic rats. The NLRP3 inhibitor MCC950 was administered to SKG mice, and ileal and joint tissues were assessed by IHC analysis and real-time qRT-PCR. The role of inflammasome in modulating the interleukin-23 (IL-23)/IL-17 axis was studied ex vivo., Results: Expression levels of Nlrp3, Nlrc4, and Aim2 were increased in the gut of HLA-B27-transgenic rats and reduced by antibiotic treatment (P < 0.05). In curdlan-treated SKG mice, NLRP3 blockade prevented ileitis and delayed arthritis onset (P < 0.05). Compared to healthy controls, AS patients demonstrated overexpression of NLRP3 (fold induction 2.33 versus 22.2; P < 0.001), NLRC4 (fold induction 1.90 versus 6.47; P < 0.001), AIM2 (fold induction 2.40 versus 20.8; P < 0.001), CASP1 (fold induction 2.53 versus 24.8; P < 0.001), IL1B (fold induction 1.07 versus 10.93; P < 0.001), and IL18 (fold induction 2.56 versus 15.67; P < 0.001) in the ileum, and caspase 1 activity was increased (P < 0.01). The score of adherent and invasive mucosa-associated bacteria was higher in AS (P < 0.01) and correlated with the expression of inflammasome components in peripheral blood mononuclear cells (P < 0.001). NLRP3 expression was associated with disease activity (the Ankylosing Spondylitis Disease Activity Score using the C-reactive protein level) (r 2 = 0.28, P < 0.01) and with IL23A expression (r 2 = 0.34, P < 0.001). In vitro, inflammasome activation in AS monocytes was paralleled by increased serum levels of IL-1β and IL-18. Induction of IL23A, IL17A, and IL22 was IL-1β-dependent., Conclusion: Inflammasome activation occurs in rodent models of AS and in AS patients, is associated with dysbiosis, and is involved in triggering ileitis in SKG mice. Inflammasomes drive type III cytokine production with an IL-1β-dependent mechanism in AS patients., (© 2021, American College of Rheumatology.)

Background: Ankylosing spondylitis (AS) is a chronic progressive inflammatory disease of the spine, which mainly invades the sacroiliac joint, spine, and large joints near the trunk, leading to fibrous and skeletal ankylosis and deformity, and can cause damage to the eyes, lung, cardiovascular, kidney and other organs. Chinese herbal formulas (CHF) is an important interventions of Traditional Chinese Medicine (TCM), and CHFs combined with western medicine are widely used in clinical practice to treat AS., Methods: Eight databases will be systematically retrieved from their inceptions to March 2021. Only randomized controlled trials (RCTs) of CHFs combined with western medicine for AS treatment will meet the inclusion criteria. The primary outcomes we focus on include clinical effectiveness rate, TCM syndrome score, TCM symptom score, Bath ankylosing spondylitis disease activity index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI), chest expansion, nocturnal spinal pain, adverse reactions, erythrocyte sedimentation rate (ESR), and C protein response (CRP). The research screening, data extraction, and risk of bias assessment will be performed independently by 2 researchers, and divergence will be solved by a third researcher. Revman 5.3 software will be used for meta-analysis. The confidence of evidence will be graded using grading of recommendations assessment, development, and evaluation (GRADE) algorithm and methodological quality will be assessed adopting risk of bias in systematic reviews (ROBIS)., Results: This systematic review (SR) will provide evidence-based medical evidence for AS therapy by CHF combined with western medicine and we will submit the findings of this SR for peer-review publication., Conclusions: This SR will provide latest and updated summary proof for assessing the effectiveness and safety of CHF combined with western medicine for AS., Registration Number: INPLASY 202150089., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 the Author(s). Published by Wolters Kluwer Health, Inc.)

Objective: Serology could help to define the real extent of SARS-CoV-2 diffusion, especially in individuals considered at higher risk of COVID-19, such as spondyloarthritis (SpA) patients undergoing immunosuppressant. Our aim was to detect, by serology, previous SARS-CoV-2 contact in SpA, compared to health care workers (HCW), and healthy controls., Methods: Sera from consecutive patients affected by SpA undergoing cytokine-targeted therapy, HCW and healthy controls from 2015 were analysed through chemiluminescent analytical system for the presence of IgG and IgM anti-SARS-CoV-2. Positive patients (IgM or IgG, or both) additionally underwent real-time Polymerase-Chain-Reaction (RT-PCR) to test for active infection. Serology was repeated at 3-months in SpA. Data across 3 groups were compared by Kruskal Wallis/Chi-square, and between 2 groups by Wilcoxon rank test/Chi-Square. P ≤ 0.05 were considered significant., Results: 200 SpA, 95 HCW and 101 controls were recruited. Positive serology was found in 25(12.5%) SpA, 8(8.4%) HCW, 0(0%) controls (p=0.001). SpA patients with positive serology more frequently reported COVID-19-like symptoms than those with negative serology (20% vs. 4%, p=0.009) and 2 had COVID-19 as confirmed by RT-PCR, non severe. No HCW reported symptoms or had positive RT-PCR. In SpA patients, at 3 months, mean IgM titres decreased from 2.76 ± 2.93 to 2.38 ± 2.95 (p=0.001), while IgG titres from 0.89 ± 3.25 to 0.31 ± 0.87 (p=ns)., Conclusions: Serology revealed that exposure to SARS-CoV-2 in SpA patients and HCW was higher than expected based on reported symptoms. In SpA, anti-cytokine therapy could act as a protective factor for a severe disease course. However, a seroconversion was not observed at 3-months., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ortolan, Lorenzin, Cosma, Cozzi, Padoan, Doria, Plebani and Ramonda.)

HLA-B27 is associated with increased susceptibility and disease activity of ankylosing spondylitis, but the effect of HLA-B27 on the activity of the broader category now called axial spondyloarthritis (AxSpA) is apparently the opposite. A modified Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) was used to assess disease activity among 3435 patients with spondyloarthritis (SpA) who participated in a survey designed to assess the effect of their disease and its treatment on the susceptibility and severity of Covid-19. Chi square testing was used to compare BASDAI scores between HLA-B27 positive and negative subjects. 2836 survey respondents were HLA B27 positive. The average BASDAI for the HLA-B27 negative cohort was 4.92 compared to 4.34 for the HLA-B27 positive subjects. Based on linear regression, a subject's sex could not fully account for the differing BASDAI score in HLA-B27 negative subjects compared to those who are HLA-B27 positive. The difference between B27 positive and negative subjects was skewed by those with a BASDAI score of one or two. HLA-B27 positive subjects were more than twice as likely to have a BASDAI score of 1 compared to HLA B27 negative subjects and about 60% more likely to have a BASDAI score of 2 (p < 0.0001). HLA-B27 positive subjects have less active spondyloarthritis compared to HLA-B27 negative subjects as measured by a BASDAI score. Our data indicate that patients with mild back pain and a diagnosis of AxSpA are disproportionately HLA-B27 positive. The HLA-B27 test facilitates the diagnosis of axial spondyloarthritis such that patients from a community survey with mild back pain may be disproportionately diagnosed as having AxSpA if they are HLA-B27 positive. The test result likely introduces a cognitive bias into medical decision making and could explain our observations.