Detection of novel diagnostic antibodies in ankylosing spondylitis: An overview

IDO1-mediated M2 macrophage polarization alleviates the progression of ankylosing spondylitis

Indoleamine 2,3-dioxygenase 1 (IDO1) plays an anti-inflammatory role in autoimmune disease. However, its specific function in ankylosing spondylitis (AS) remain unclear. This study aimed to investigate the potential role of IDO1 in AS. Immunofluorescence, RT-qPCR, and western blot assays were employed to measure gene expression, while ELISA was used to quantify the release of M1 macrophage and M2 macrophage markers. CCK-8, EdU, flow cytometry, ALP staining, and Alizarin red staining (ARS) assays were conducted for functional analysis. JASPAR predicted the binding sites between PPARγ and the promoter, which were further validated by luciferase and ChIP assays. Our findings revealed that the expression of IDO1 was markedly elevated in AS patients. IDO1 overexpression promoted the proliferation of THP-1 cells and M2 macrophage polarization. Conversely, IDO1 knockdown facilitated the osteogenic differentiation of BMSCs. Furthermore, IDO1-mediated upregulation of PPARγ modulated RUNX2 transcription. PPARγ overexpression counteracted the effects of IDO1 knockdown, thereby inhibiting the osteogenic differentiation of BMSCs. In conclusion, the IDO1/PPARγ/RUNX2 signaling pathway may protect against AS by promoting M2 macrophage polarization and inhibiting osteogenic differentiation.

T2* cartilage mapping in early axial spondyloarthritis: diagnostic accuracy and correlation with clinical characteristics, sacroiliitis MRI scorings, and diffusion metrics

PURPOSE

To determine the performance of T2* cartilage mapping in diagnosing and assessing disease activity in early axial spondyloarthritis (axSpA), and to investigate the interaction of cartilage damage with clinical characteristics, sacroiliitis MRI scorings, and diffusion metrics.

MATERIALS AND METHODS

This prospective study included 83 axSpA patients and 37 no-axSpA patients. Clinical characteristics, the Assessment of SpondyloArthritis International Society-defined active sacroiliitis on MRI, and T2* SIJs values were recorded. In axSpA, disease activity was evaluated using the ankylosing spondylitis disease activity score-C-reactive protein; active sacroiliitis was evaluated using Spondyloarthritis Research Consortium of Canada, intravoxel incoherent motion, and diffusion kurtosis imaging; chronic sacroiliitis was assessed using composite structural damage score (CSDS) and structural score fat. Mann-Whitney U-test, Kruskal-Wallis test with false discovery rate (FDR), ROC curve, and linear regression were used for statistical analysis.

RESULTS

AxSpA patients had significantly higher T2*SIJs values than no-axSpA patients. (22.86 ± 2.42 ms vs 20.36 ± 1.30 ms, p < 0.001). The combination of T2*SIJs values and active sacroiliitis on MRI had the highest AUC for identifying axSpA. T2*SIJs values were significantly different between the inactive and very high, moderate and very high, high and very high, as well as inactive and high disease activity groups (all pFDR < 0.05). Dk (β = 0.48) and CSDS (β = 0.48) were independently associated with T2*SIJs values.

CONCLUSION

T2* values may be a promising biomarker for diagnosing and differentiating disease activity in early axSpA. Both acute and chronic sacroiliitis influence cartilage properties.

CLINICAL RELEVANCE STATEMENT

Sacroiliac joint cartilage abnormalities can be quantified with T2* relaxation time and allow better characterization of early axSpA.

KEY POINTS

T2* mapping may have value in evaluating axSpA. The combination of T2* values and active sacroiliitis on MRI enhances diagnostic performance for axSpA. Abnormalities measured with T2* values correlate with disease activity, acute sacroiliitis, and degree of structural damage.

Exploring the molecular mechanism of Epimedium for the treatment of ankylosing spondylitis based on network pharmacology, molecular docking, and molecular dynamics simulations

Ankylosing spondylitis (AS) is a rheumatic disease that causes inflammation and bone formation in the spine. Despite significant advances in treatment, adverse side effects have triggered research into natural compounds. Epimedium (EP) is a traditional Chinese herb with a variety of pharmacological activities, including antirheumatic, anti-inflammatory, and immunomodulatory activities; however, its direct effects on AS treatment and the underlying molecular mechanisms have not been systematically studied. Thus, here, we used network pharmacology, molecular docking, and molecular dynamics simulations to explore the targets of EP for treating AS. We constructed an interaction network to elucidate the complex relationship between EP and AS. Sixteen active ingredients in EP were screened; 80 potential targets were identified. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone, anhydroicaritin, and luteolin were the core components and TNF, IL-6, IL-1β, MMP9, and PTGS2 were the core targets. The GO and KEGG analyses indicated that EP may modulate multiple biological processes and pathways, including the AGE-RAGE, TNF, NF-κB/MAPK, and TLR signaling pathways, for AS treatment. Molecular docking and molecular dynamics simulations showed good affinity between the active components and core targets of EP, with stable binding within 100 nanoseconds. In particular, 8-(3-methylbut-2-enyl)-2-phenylchromone possessed the highest free energy of binding to PTGS2 and TNF (-115.575 and - 87.676 kcal/mol, respectively). Thus, EP may affect AS through multiple pathways, including the alleviation of inflammation, oxidative stress, and immune responses. In summary, we identified the active components and potential targets of EP, highlighting new strategies for the further experimental validation and exploration of lead compounds for treating AS.

A guideline on biomarkers in the diagnosis and evaluation in axial spondyloarthritis

Objective

To develop a guideline for selecting biomarkers in the diagnosis and assessment in patients with axial spondyloarthritis (axSpA).

Method

A joint effort was carried out by the core team, the literature review team and the multidisciplinary voting panel to formulate recommendations regarding biomarkers in axSpA, using an evidence-based and consensus-based strategy. Certainty of evidence and strength of recommendation were determined, and levels of agreement within the voting panel were calculated.

Results

A total of 20 recommendations were formulated in this guideline, with levels of agreement ranging from 6.48 to 9.71. The two strong recommendations, HLA-B27 testing in patients suspected of axSpA and regular-interval monitoring of CRP/ESR represent the status quo of axSpA evaluation, while the 13 conditional recommendations represent the promising biomarkers with clinical utility in diagnosis, disease activity assessment, prediction of radiographic progression and therapeutic responses. This guideline does not dictate clinical choices of tests on axSpA, and decisions should be made based on comprehensive consideration of costs, accessibility, patients' values and willingness as well as the objective of testing in the local context.

Conclusion

This guideline addresses the interpretation of the clinical significance of biomarkers in axSpA, and the biomarkers endorsed in this guideline composed a clinical toolkit for healthcare professionals to choose from.

Autoimmune diseases: targets, biology, and drug discovery

Autoimmune diseases (AIDs) arise from a breakdown in immunological self-tolerance, wherein the adaptive immune system mistakenly attacks healthy cells, tissues and organs. AIDs impose excessive treatment costs and currently rely on non-specific and universal immunosuppression, which only offer symptomatic relief without addressing the underlying causes. AIDs are driven by autoantigens, targeting the autoantigens holds great promise in transforming the treatment of these diseases. To achieve this goal, a comprehensive understanding of the pathogenic mechanisms underlying different AIDs and the identification of specific autoantigens are critical. In this review, we categorize AIDs based on their underlying causes and compile information on autoantigens implicated in each disease, providing a roadmap for the development of novel immunotherapy regimens. We will focus on type 1 diabetes (T1D), which is an autoimmune disease characterized by irreversible destruction of insulin-producing β cells in the Langerhans islets of the pancreas. We will discuss insulin as possible autoantigen of T1D and its role in T1D pathogenesis. Finally, we will review current treatments of TID and propose a potentially effective immunotherapy targeting autoantigens.

Potential Roles for B cells and Autoantibodies in Ankylosing Spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory rheumatic disease that predominantly affects young males. AS is a condition in which the spine and sacroiliac joints become inflamed. More specifically, most AS patients experience spine malformations over time, resulting in functional incapability. The etiopathogenesis of AS is a complex combination of genetic predisposition and environmental factors. Extensive studies on AS have revealed the central role of genetics and immune reactions in its etiology. However, an utmost agreement has yet to be created. The available evidence suggests that both autoinflammation and T-cell-mediated autoimmune processes have significant roles in the disease process of AS. So far, B cells have obtained moderately little attention in AS pathogenesis, primarily because of the absence of disease-defining autoantibodies. However, against general dogma, evidence is mounting showing B cell involvement. Disruptions depict this in circulating B cell populations, the increased expression of immunoglobulin (Ig)G, IgA, and IgM, and B cell infiltration within the axial skeleton of AS patients. Meanwhile, compared to many other inflammatory autoimmune disorders, AS has no disease-specific autoantibodies that help disease diagnosis. This study has provided an overview of the B lymphocytes and antibodies' role in AS pathogenesis. It also introduces autoantibodies that can be the prognosis and diagnosis biomarkers of AS.

Unravelling the immunobiology of innate lymphoid cells (ILCs): Implications in health and disease

Innate lymphoid cells (ILCs), a growing class of immune cells, imitate the appearance and abilities of T cells. However, unlike T cells, ILCs lack acquired antigen receptors, and they also do not undergo clonal selection or proliferation in response to antigenic stimuli. Despite lacking antigen-specific receptors, ILCs respond quickly to signals from infected or damaged tissues and generate an array of cytokines that regulate the development of adaptive immune response. ILCs can be categorized into four types based on their signature cytokines and transcription factors: ILC1, ILC2, ILC3 (including Lymphoid Tissue inducer- LTi cells), and regulatory ILCs (ILCregs). ILCs play key functions in controlling and resolving inflammation, and variations in their proportion are linked to various pathological diseases including cancer, gastrointestinal, pulmonary, and skin diseases. We highlight current advancements in the biology and classification of ILCs in this review. Additionally, we provide a thorough overview of their contributions to several inflammatory bone-related pathologies, including osteoporosis, rheumatoid arthritis, periodontitis, and ankylosing spondylitis. Understanding the multiple functions of ILCs in both physiological and pathological conditions will further mobilize future research towards targeting ILCs for therapeutic purposes.

Peripheral Spondyloarthritis Presenting with Fever and Severe Systemic Inflammatory Response Mimicking Infection: A Case Series and Literature Review

Objective

To describe four peripheral spondyloarthritis patients presenting with fever and severe systemic inflammatory response mimicking infection.

Methods

Between 2017 and 2019, four patients with the final diagnosis of peripheral spondyloarthritis had atypical presentation of fever and severe systemic inflammatory response requiring hospital admission and extensive workup.

Results

We reported four patients who were admitted to the hospital for fever and arthritis. They all had laboratory tests of the severe systemic inflammatory response (leukocytosis, thrombocytosis, high ESR, and high CRP) concerning infection. They underwent extensive workup for infectious causes, including septic arthritis, which came back negative. Other rheumatic diseases that are known to present with fever such as adult-onset Still's disease, reactive arthritis, and crystal arthritis were all excluded. The final diagnosis of spondyloarthritis was made during their follow-up: three patients with peripheral spondyloarthritis and one with psoriatic arthritis. All patients received conventional DMARDs (methotrexate and sulfasalazine) and two patients received tumor necrosis factor inhibitors in addition to conventional DMARDs to control their disease.

Conclusion

We observed a subgroup of peripheral spondyloarthritis patients presenting with fever and severe systemic inflammatory response requiring hospitalization. Recognition of this subgroup is important and should be considered once an infection is ruled out.

Pharmacological importance of Kunxian Capsule in clinical applications and its adverse effects: A review

Kunxian Capsule (KX) is a popular Chinese patent medicine for the treatment of rheumatoid arthritis, nephrotic syndrome, systemic lupus erythematosus, Henoch-Schönlein purpura, ankylosing spondylitis, psoriatic arthritis and eczema. However, there is scarcity of comprehensive information on the significance of KX in the clinical application and its side effects. Hence, it is aimed to provide a review of the significance of KX, with a focus on the pharmacological effects, clinical applications, and its adverse reactions. This review was based on the published literatures in PubMed, China National Knowledge Infrastructure and WanFang database. The articles were collected by two independent authors with no time limits applied until November 30, 2022. The search term includes Kunxian Capsule and/or clinical effect, pharmacology, disease, therapy, adverse effects and quality control. KX has been shown to be effective in the treatment of autoimmune arthritis by inhibiting inflammatory responses and inducing apoptosis. Many studies suggest that KX has anti-inflammatory and analgesic properties that aid in the improvement of joint functions. KX dispels wind, removes dampness, invigorates the kidneys, and promotes blood circulation, thereby curing various diseases. However, studies also suggest KX-related adverse reactions in multiple systems. Overall, this review highlights the scientific basis of KX in curing or preventing various diseases and provides novel insights for further research and clinical applications.

Antibodies of the immunoglobulin a isotype to novel antigens in early axial spondyloarthritis

Introduction

There is an unmet need for biomarkers to identify patients with axial spondyloarthritis (axSpA). Increasing evidence suggest the presence of autoantibodies in a subset of axSpA patients. The aim of this study was to identify novel IgA antibodies in early axSpA patients and to determine their diagnostic potential in combination with previously determined IgG antibodies against UH (Hasselt University)-axSpA-IgG antigens.

Methods

An axSpA cDNA phage display library constructed from axSpA hip synovium, was used to screen for novel IgA antibodies in plasma from early axSpA patients. The presence of these antibodies against novel UH-axSpA-IgA antigens was determined in two independent axSpA cohorts, in healthy controls and in patients with chronic low back pain.

Results

We identified antibodies to 7 novel UH-axSpA-IgA antigens, of which 6 correspond to non-physiological peptides and 1 to the human histone deacetylase 3 (HDAC3) protein. IgA antibodies against 2 of these 7 novel UH-axSpA-IgA antigens and IgG antibodies against 2 of the previously identified antigens were significantly more present in early axSpA patients from the UH cohort (18/70, 25.7%) and the (Bio)SPAR cohort (26/164, 15.9%), compared to controls with chronic low back pain (2/66, 3%). Antibodies to this panel of 4 antigens were present in 21.1% (30/142) of patients with early axSpA from the UH and (Bio)SPAR cohorts. The positive likelihood ratio for confirming early axSpA using antibodies to these 4 UH-axSpA antigens was 7.0. So far, no clinical correlation between the novel identified IgA antibodies and inflammatory bowel disease could be identified.

Discussion

In conclusion, screening an axSpA cDNA phage display library for IgA reactivity resulted in the identification of 7 novel UH-axSpA-IgA antigens, of which 2 show promising biomarker potential for the diagnosis of a subset of axSpA patients, in combination with previously identified UH-axSpA-IgG antigens.

Diagnostic value of anti-Kaiso autoantibody in axial spondyloarthritis

Objective

Axial spondyloarthritis (axSpA) is a chronic rheumatic disease predominantly characterized by inflammation and progressive structural damage. Patients are often diagnosed very late, which delays the optimal treatment period. Early diagnosis of axSpA, especially non-radiographic axSpA (nr-axSpA), remains a major challenge. This study aimed to investigate the diagnostic value of anti-Kaiso autoantibodies in axSpA and their correlation with clinical disease indicators.

Methods

Two pooled serum samples (seven patients with nr-axSpA and seven healthy controls) were profiled using HuProt arrays to investigate the diagnostic value of autoantibodies in nr-axSpA. Levels of anti-Kaiso autoantibodies in patients with axSpA and controls were determined using the Meso Scale Discovery assay system. Receiver operating characteristic curve analysis was performed to evaluate the diagnostic performance of anti-Kaiso autoantibodies in axSpA. Pearson's correlation was used to assess the correlation between anti-Kaiso autoantibodies and clinical parameters.

Results

Seven candidate autoantibodies were present in the serum of patients with nr-axSpA. The levels of anti-Kaiso autoantibodies were significantly higher in the nr-axSpA group than in the other groups. It can differentiate nr-axSpA from ankylosing spondylitis (AS), healthy controls, and rheumatoid arthritis. The level of early-stage AS among patients with nr-axSpA decreased when they progressed to the late stage. Of all patients with axSpA, serum anti-Kaiso autoantibody levels were positively correlated with the C-reactive protein level and the Bath Ankylosing Spondylitis Disease Activity Index score and negatively correlated with disease duration.

Conclusion

Anti-Kaiso autoantibody may be a valuable diagnostic biomarker for early-stage AS in the nr-axSpA period and may be a potential therapeutic target.

Inflammasomes and their roles in arthritic disease pathogenesis

The inflammasome is a molecular platform that is created in the cytosolic compartment to mediate the host immunological response to cellular injury and infection. Caspase-1 may be activated by the inflammasome, which leads to the generation of the inflammatory cytokines interleukin-1β (IL-1β) and IL-18 and the beginning of pyroptosis, which is a type of proinflammatory cell death. Scientists have identified a number of different inflammasomes in the last 2 decades. The NLRP3 inflammasome has been studied the most, and its activity may be triggered by a broad range of different inducers. However, activation of the NLRP3 inflammasome in a manner that is not properly controlled is also a factor in the etiology of many human illnesses. Accumulating evidence indicates that the NLRP3 inflammasome plays a significant role in the innate and adaptive immune systems and the development of various arthritic illnesses, such as rheumatoid arthritis, ankylosing spondylitis, and gout. The present review provides a concise summary of the biological properties of the NLRP3 inflammasome and presents the fundamental processes behind its activation and control. We discuss the role of the inflammasome in the pathogenesis of arthritic diseases, such as rheumatoid arthritis, ankylosing spondylitis, and gout, and the potential of newly developed therapies that specifically target the inflammasome or its products for the treatment of inflammatory diseases, with a particular emphasis on treatment and clinical application.

Evaluation of CX3CR1 gene DNA methylation in developmental dysplasia of the hip (DDH)

INTRODUCTION AND OBJECTIVE

Developmental dysplasia of the hip (DDH) is a musculoskeletal disorder. Genetic and epigenetic changes in C-X3-C motif chemokine receptor 1 (CX3CR1) may lead to disturbance in chondrocyte development and change the labrum dimensions, which indirectly result in hip joint instability. Considering the important role of this gene in cell migration, cell adhesion and bone and cartilage development, we aimed to evaluate the CX3CR1 gene methylation in DDH pathogenesis.

METHODS

Our study comprised of forty-five DDH patients and forty-five healthy control subjects with healthy femoral neck cartilage. The healthy controls had total or hemiarthroplasty for the femoral neck fracture. Samples were collected from the femoral head (cartilage) of DDH patients and healthy controls. Genomic DNA was obtained from the samples, and DNA methylation of CX3CR1 gene was analyzed via metabisulfite method.

RESULTS

Methylation analysis reveals no significant differences in promoter of CX3CR1 gene in cartilage samples from DDH patients and healthy control subjects (P = 0.33).

CONCLUSION

Methylation status of CX3CR1 gene showed no significant difference between the patient and control groups. Our results indicate that DNA methylation may not modulate this gene in this disease and other epigenetic mechanisms such as non-coding RNAs and histone modifications could be implicated.

Patients with ankylosing spondylitis have high risk of irritable bowel syndrome. A long-term nationwide population-based cohort study

OBJECTIVE

Ankylosing spondylitis (AS) is a chronic inflammatory disease, might carry a high risk of irritable bowel syndrome (IBS) due to abnormal gut microbiota or inflammatory reaction.

METHODS

We conducted a 14-year retrospective cohort study based on Taiwan's National Health Insurance Research Database (NHIRD). A total of 4007 patients with newly diagnosed AS (outpatient visits≧3 times, or hospitalization≧1 time) and 988,084 non-AS comparisons were enrolled during 2000-2012. To ensure baseline comparability, the propensity score was matched by age, gender, comorbidities, and other possible confounders. The outcome was the incidence of IBS, followed up to the end of 2013. Cox proportional hazard model calculated adjusted hazard ratio (aHR) and the cumulative incidence of both groups was analyzed by the Kaplan-Meier method.

RESULT

After propensity score matching, baseline demographic characteristics were comparable between AS patients and the comparison group. The crude HR for IBS in the AS group was significantly higher 2.41 (95%C.I. =1.84-3.16) than comparison group. After adjusting for possible confounders, adjusted HR was 2.50 (95%C.I.=1.91-3.29). The cumulative incidence of IBS in AS was significantly higher than non-AS comparisons during the 14-year follow-up (P<0.001).

CONCLUSION

This nationwide population-based cohort study showed that patients with AS have higher risks of IBS than those of the non-AS comparison group.

B Cell Involvement in the Pathogenesis of Ankylosing Spondylitis

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.

Cellular and molecular diversity in spondyloarthritis

The spondyloarthritides are a cluster of inflammatory rheumatic diseases characterized by different diagnostic entities with heterogeneous phenotypes. The current classification system groups spondyloarthritis patients in two main categories, axial and peripheral spondyloarthritis, providing a framework wherein the clinical picture guides the treatment. However, the heterogeneity of the clinical manifestations of the pathologies, even when residing in the same group, highlights the importance of analyzing the smallest features of each entity to understand how different cellular subsets evolve, what the underlying mechanisms are and what biological markers can be identified and validated to evaluate the stage of disease and the corresponding efficacy of treatments. In this review, we will focus mostly on axial spondyloarthritis, report current knowledge concerning the cellular populations involved in its pathophysiology, and their molecular diversity. We will discuss the implications of such a diversity, and their meaning in terms of patients' stratification.

CD27-CD38lowCD21low B-Cells Are Increased in Axial Spondyloarthritis

B-cells have received little attention in axial spondyloarthritis (axSpA) and for this reason their role in pathogenesis remains unclear. However, there are indications that B-cells may be involved in the disease process. Our objective was to obtain insights into the composition of the peripheral B-cell compartment of axSpA patients compared to healthy donors (HD) and patients with primary Sjögren's syndrome (pSS), a typical B-cell-associated autoimmune disease. Special emphasis was given to CD27-negative B-cells expressing low levels of CD21 (CD21low B-cells), since this subset is implicated in autoimmune diseases with strong involvement of B-cells. Transitional B-cells (CD38hi) were excluded from the analysis of the CD27-CD21low B-cell compartment. This study included 45 axSpA patients, 20 pSS patients and 30 HDs. Intriguingly, compared to HDs the frequency of CD27-CD38lowCD21low B-cells was significantly elevated in both axSpA and pSS patients (P<0.0001 for both comparisons). The frequency of CD27-CD38lowCD21low B-cells expressing the activation-induced immune markers T-bet and CD11c was decreased in axSpA patients compared to HDs. A higher proportion of CD27-CD38lowCD21low B-cells expressed the chemokine receptor CXCR3 in axSpA compared to HDs, suggestive for active involvement of these cells in an inflammatory process. The frequency of CD27-CD38lowCD21low B-cells in axSpA patients correlated positively with age and erythrocyte sedimentation rate. Furthermore, axSpA patients with extra-skeletal manifestations (ESM) showed increased frequencies of CD27-CD38lowCD21low B-cells compared to patients without ESM. In conclusion, our findings are suggestive of active B-cell involvement in the pathogenesis of axSpA, against prevailing dogma.

Gut microbiota-microRNA interactions in ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic autoimmune inflammatory disability that is part of the rheumatic disease group of spondyloarthropathies. AS commonly influences the joints of the axial skeleton. The contributions to AS pathogenesis of genetic susceptibility (particularly HLA-B27 and ERAP-1) and epigenetic modifications, like non-coding RNAs, as well as environmental factors, have been investigated over the last few years. But the fundamental etiology of AS remains elusive to date. The evidence summarized here indicates that in the immunopathogenesis of AS, microRNAs and the gut microbiome perform critical functions. We discuss significant advances in the immunological mechanisms underlying AS and address potential cross-talk between the gut microbiome and host microRNAs. This critical interaction implicates a co-evolutionary symbiotic link between host immunity and the gut microbiome.

NMR-based clinical metabolomics revealed distinctive serum metabolic profiles in patients with spondyloarthritis

Spondyloarthritis (SpA) is a common rheumatic disorder of the young, marred by delay in diagnosis, and paucity of biomarkers of disease activity. The present study aimed to explore the potential of serum metabolic profiling of patients with SpA to identify biomarker for the diagnosis and assessment of disease activity. The serum metabolic profiles of 81 patients with SpA were compared with that of 86 healthy controls (HCs) using nuclear magnetic resonance (NMR)-based metabolomics approach. Seventeen patients were followed up after 3 months of standard treatment, and paired sera were analyzed for effects of therapy. Comparisons were done using the multivariate partial least squares discriminant analysis (PLS-DA), and the discriminatory metabolic entities were identified based on variable importance in projection (VIP) statistics and further evaluated for statistical significance (p value < 0.05). We found that the serum metabolic profiles differed significantly in SpA as compared with HCs. Compared with HC, the SpA patients were characterized by increased serum levels of amino acids, acetate, choline, N-acetyl glycoproteins, Nα-acetyl lysine, creatine/creatinine, and so forth and decreased levels of low-/very low-density lipoproteins and polyunsaturated lipids. PLS-DA analysis also revealed metabolic differences between axial and peripheral SpA patients. Further metabolite profiles were found to differ with disease activity and treatment in responding patients. The results presented in this study demonstrate the potential of serum metabolic profiling of axial SpA as a useful tool for diagnosis, prediction of peripheral disease, assessment of disease activity, and treatment response.

Diagnostic value of anti-CD74 antibodies in early and late axial spondyloarthritis and its relationship to disease activity

OBJECTIVES

This study was designed to evaluate the role of anti-CD74 antibodies in diagnosis of axial spondyloarthritis (axSpA) and their relationship to disease duration and disease activity.

METHODS

Fifty patients with axSpA, 15 patients with RA and 15 healthy subjects were included in the study. Clinical examination and laboratory tests were done. The ESR, CRP level and ASDAS were measured as markers of the disease activity. Quantitative determination of human CD74 IgG antibodies was done.

RESULTS

The mean age of the patients was 38.22 (S.D.12.20) years. The level of CD74 autoantibodies was significantly higher in axSpA in comparison to control groups. Most patients with positive articular and extra-articular manifestations were positive for CD74 autoantibodies. In patients with inactive disease, 33.3% were positive for CD74 autoantibodies, as were 83% with active disease. High percentages of patients with early and late axSPA were CD74 autoantibody positive. The majority of patients with positive disease activity in early and late axSpA were CD74 autoantibody positive. CD74 autoantibodies had 80% sensitivity vs both control groups with 87% specificity vs the healthy control group and 80% vs the RA control group in the diagnosis of axSpA.

CONCLUSIONS

The frequency of positive anti-CD74 IgG antibodies was as high in patients with early axSpA as in those with late axSpA, with no significant differences. There was a significant difference in the frequency of positive anti-CD74 IgG antibodies between patients with positive and negative disease activity. Based on the sensitivity and specificity of anti-CD74 IgG, this is a promising diagnostic tool to support the clinical diagnosis of axSpA.

Revisiting B cell tolerance and autoantibodies in seropositive and seronegative autoimmune rheumatic disease (AIRD)

Autoimmune rheumatic diseases (AIRD) are categorized seropositive or seronegative, dependent upon the presence or absence of specific autoreactive antibodies, including rheumatoid factor and anti-citrullinated protein antibodies. Autoantibody-based diagnostics have proved helpful in patient care, not only for diagnosis but also for monitoring of disease activity and prediction of therapy responsiveness. Recent work demonstrates that AIRD patients develop autoantibodies beyond those contained in the original categorization. In this study we discuss key mechanisms that underlie autoantibody development in AIRD: defects in early B cell development, genetic variants involved in regulating B cell and T cell tolerance, environmental triggers and antigen modification. We describe how autoantibodies can directly contribute to AIRD pathogenesis through innate and adaptive immune mechanisms, eventually culminating in systemic inflammation and localized tissue damage. We conclude by discussing recent insights that suggest distinct AIRD have incorrectly been denominated seronegative.

Antibodies Against Three Novel Peptides in Early Axial Spondyloarthritis Patients From Two Independent Cohorts

OBJECTIVE

This study was undertaken to identify novel autoantibodies in axial spondyloarthritis (SpA) and determine their diagnostic potential in patients with early axial SpA and controls from 2 independent cohorts.

METHODS

An axial SpA complementary DNA phage display library was used to screen for novel IgG antibodies in plasma from patients with early axial SpA. The presence of these antibodies against novel peptides (i.e., peptides identified in an early axial SpA cohort from Hasselt University, designated UH-axSpA) was determined by enzyme-linked immunosorbent assay in 76 patients with early axial SpA, 75 controls with nonspecific chronic low back pain, 60 patients with rheumatoid arthritis, and 94 healthy controls from the UH cohort. Antibody reactivity to these novel peptides was further validated in 174 patients with axial SpA (of whom 79 had early axial SpA) from the University Hospitals Leuven (Bio)SPAR (Spondyloarthritis [Biologics]) cohort.

RESULTS

We identified antibodies to 9 novel UH-axSpA peptides, corresponding to randomly formed peptides and to a novel axial SpA autoantigen, double homeobox protein 4. Antibodies to 3 UH-axSpA peptides with the highest positive likelihood ratio (LR) for a diagnosis of axial SpA were present in significantly more patients with early axial SpA from the UH and (Bio)SPAR cohorts (14.2% [22/155]) compared to controls with chronic low back pain (5% [4/75]), resulting in 95% specificity. The positive LR for confirming axial SpA using antibodies to these 3 UH-axSpA peptides was 2.7, which is higher than the LR obtained with the currently used laboratory marker C-reactive protein. Testing for antibodies to these 3 UH-axSpA peptides in patients with chronic low back pain increased the posttest probability of a diagnosis of axial SpA from 79% to 91%.

CONCLUSION

Antibodies to 3 UH-axSpA peptides could provide a novel tool in the diagnosis of a subset of axial SpA patients.

Activated coagulation is associated with the disease activity of axial spondyloarthritis

BACKGROUND

Activation of the coagulation system has been related to disease activity in some inflammatory diseases. Here, we aimed to investigate the relationship between coagulation function and the disease activity of axial spondyloarthritis (axSpA).

METHODS

This study retrospectively recruited 144 axSpA patients and 55 healthy controls. The patients were divided into an active group (Bath Ankylosing Spondylitis Disease Activity Index, BASDAI ≥ 4) and a remission group (BASDAI < 4). The coagulation, inflammatory and clinical parameters were detected. The correlations between these parameters were analyzed with Spearman's correlation analysis. Receiver operating characteristic (ROC) curve analysis was performed to compare the values of these variables in discriminating disease activity. Furthermore, binary logistic regression analysis was used to assess the risk factors for axSpA disease activity.

RESULTS

Fibrinogen (FIB) was increased in the axSpA group compared to healthy controls (P < 0.001). Additionally, FIB and D-dimer were higher in the active group than in the remission group (P < 0.05, respectively). FIB and D-dimer were positively correlated with ESR, CRP, BASDAI, Bath Ankylosing Spondylitis Functional Index (BASFI) and Bath Ankylosing Spondylitis Metrology Index (BASMI) (P < 0.05, respectively). The area under the curve (AUC) of FIB was higher than that of ESR, CRP and D-dimer. The optimal cut-off value of FIB was 3.23 g/L, with a specificity of 62.0% and sensitivity of 75.0%. FIB (OR = 4.335, 95% CI: 1.262-14.888, P = 0.020) and BASFI score (OR = 1.878, 95% CI: 1.441-2.448, P < 0.001) were independent risk factors affecting disease activity.

CONCLUSION

Activated coagulation is closely related to the disease activity of axSpA. FIB and D-dimer might be novel indicators for monitoring the disease activity of axSpA.

Quantitative Proteomic Analyses To Reveal the Key Features of Proteins in New Onset Ankylosing Spondylitis Patients

Ankylosing spondylitis (AS) is a chronic immune-mediated disease. Various immune cells play an essential role in the AS pathogenesis. However, the specific pathogenesis of AS has not been well understood. Proteomic profiles of peripheral blood mononuclear cells (PBMCs) were applied to reveal the specific pathogenesis of AS. Quantitative proteomic analyses were performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based methods to investigate the protein profiling of PBMCs from new-onset AS patients (n = 9) and healthy controls (n = 9). We identified 782 differentially expressed proteins (DEPs) and 527 differentially phosphorylated proteins (DPPs) between AS patients and healthy controls. The subcellular location of DEPs and DPPs showed that most of the DEPs were from the cytoplasm (n = 296, 38%), were extracellular (n = 141, 18%), and from the nucleus (n = 114, 15%); most of the DPPs were from the cytoplasm (n = 37, 34%), nucleus (n = 35, 32%), and plasma membrane (n = 10, 9%). We further identified 89 proteins with both expression and phosphorylation differences. The functional annotation of the 89 differentially expressed and phosphorylated proteins enriched in the antigen processing and presentation pathway. Four DEPs with six phosphorylated positions were found in the antigen processing and presentation pathway. The differentially expressed and phosphorylated proteins may be helpful to uncover the pathogenesis of AS. The six AS-specific proteins may serve as candidate markers for AS diagnosis and new treatment targets.

Effects of etanercept and infliximab on bone metabolism indexes in patients with ankylosing spondylitis

Effect of etanercept and infliximab on bone metabolism indexes in patients with ankylosing spondylitis (AS) were evaluated. The clinical data of 80 patients with ankylosing spondylitis admitted to Affiliated Hospital of Hebei University of Engineering from June 2015 to March 2016 were selected. There were 39 patients treated with Enbrel as Enbrel group and 41 patients treated with Infliximab as Infliximab group. The general data of the two groups of patients were collected and various indexes before and 12 and 24 weeks after treatment were recorded. Adverse reactions of the two groups of patients after treatment were recorded and the clinical efficacy of the drugs was evaluated. C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) levels in both groups decreased significantly before and 12 and 24 weeks after treatment (P<0.05), and 24 weeks after treatment showed a downward trend compared with 12 weeks (P<0.05). The β-collagen special sequence (β-CTX) level in the two groups was significantly lower after treatment than before (P<0.0001). The adverse reaction rate of Infliximab group (21.95%) was higher than that of Enbrel group (5.13%) (P>0.05). The morning stiffness time, BASDAI and BASFI indexes of the two groups of patients after treatment were significantly lower than those before treatment (P<0.0001). Schober test was significantly higher than that before treatment (P<0.0001); BASDAI in Infliximab group was lower than that in etanercept group (P<0.05). Both etanercept and infliximab have good therapeutic effects on AS, which can reduce the bone metabolism level of β-CTX in AS patients and effectively improve the symptoms of affected medullary joints. The short-term efficacy of the two groups of patients is similar, but the incidence of adverse reactions of etanercept is slightly lower than that of infliximab.

DNA hypermethylation of GDF5 in developmental dysplasia of the hip (DDH)

INTRODUCTION & OBJECTIVE

Developmental Dysplasia of the Hip (DDH) is one of the most common congenital skeletal anomalies. Body of evidence suggests that genetic variations in GDF5 are associated with susceptibility to DDH. DDH is a multifactorial disease and its etiology has not been entirely determined. Epigenetic changes such as DNA methylation could be linked to DDH. In this scheme, we hypothesized that changes in GDF5 DNA methylation could predispose a susceptible individual to DDH.

METHODS

This study consisted of 45 DDH patients and 45 controls with healthy femoral neck cartilage, who underwent hemi-, or total arthroplasty for the femoral neck fracture. A cartilage sample of 1 cm in diameter and 1 mm in the thickness was obtained for DNA extraction. DNA was extracted and DNA methylation of GDF5 was evaluated by metabisulfite method.

RESULTS

Methylation analysis showed that the promoter of GDF5 in cartilage samples from DDH patients was hypermethylated in comparison to healthy controls (p = .001).

CONCLUSION

Our study showed that the methylation status of the GDF5 in patients with DDH is dysregulated. This dysregulation indicates that adjustment in the methylation might modify the expression of this gene. Since this gene plays an essential role in cartilage and bone development, thus reducing its expression can contribute to the pathogenesis of DDH. Further studies are needed to elucidate the role of GDF5 in this disease.

Ankylosing spondylitis: etiology, pathogenesis, and treatments

Ankylosing spondylitis (AS), a common type of spondyloarthropathy, is a chronic inflammatory autoimmune disease that mainly affects spine joints, causing severe, chronic pain; additionally, in more advanced cases, it can cause spine fusion. Significant progress in its pathophysiology and treatment has been achieved in the last decade. Immune cells and innate cytokines have been suggested to be crucial in the pathogenesis of AS, especially human leukocyte antigen (HLA)‑B27 and the interleukin‑23/17 axis. However, the pathogenesis of AS remains unclear. The current study reviewed the etiology and pathogenesis of AS, including genome-wide association studies and cytokine pathways. This study also summarized the current pharmaceutical and surgical treatment with a discussion of future potential therapies.

Comparison of secondary IgA nephropathy in patients with ankylosing spondylitis and rheumatoid arthritis

Objectives: The aim of the present study was to investigate the differences in clinic-pathological features of secondary IgA nephropathy (SIgAN) between patients with ankylosing spondylitis (AS) and rheumatoid arthritis (RA).Methods: Forty-six patients with SIgAN related to AS (SIgAN-AS) and 26 patients with SIgAN related to RA (SIgAN-RA) were enrolled in this retrospective study. The two groups were compared for their clinic-pathological characteristics.Results: The 10-year prevalence of SIgAN-AS and SIgAN-RA were 167 per 1000 and 51.3 per 1000, respectively. Compared with SIgAN-RA patients, SIgAN-AS patients had lower incidences of edema and nephrotic syndrome, but higher levels of eGFR, serum C3, and CD3- and CD8-positive T-cell counts, but less incidences of acute tubulointerstitial lesions and interlobular arterial lesions. IgM was the most familiar co-depositing immune complex on tissue with significantly different frequencies. In SIgAN-AS patients, those with positive HLA-B27 presented with lower levels of proteinuria, higher levels of serum IgG and C3, and less incidence of renal insufficiency, crescents >14.5%, glomerular sclerosis >32.6% and segmental sclerosis >5.2%.Conclusion: SIgAN was more prevalent in AS than in RA. SIgAN-AS patients differed from SIgAN-RA patients in certain clinic-pathological characteristics. HLA-B27 likely protected SIgAN-AS patients from renal insufficiency.

Anti-SIRT1 autoantibody is elevated in ankylosing spondylitis: a potential disease biomarker

Background

Little is known about the presence of specific autoantibodies in ankylosing spondylitis (AS), an immune-mediated inflammatory disease. The object of this study was to explore potential autoantibody profiles in AS patients.

Results

Levels of anti-SIRT1 autoantibodies were significantly higher in AS (P < 0.001) and psoriatic arthritis (PsA) (P < 0.01) patients but not rheumatoid arthritis (RA) patients compared with healthy controls. Additionally, titers of anti-NAD-dependent protein deacetylase sirtuin-1(SIRT1) antibodies were significantly higher in AS patients than in RA (P < 0.05) and PsA (P < 0.05) patients. Moreover, levels of anti-SIRT1 (P < 0.001) antibodies were significantly higher during the first year in patients with hip joint involvement. The anti-SIRT1 antibody positivity rate was 18.9% in AS patients.

Conclusions

Our findings indicate that anti-SIRT1 autoantibodies may serve as a marker for diagnosing AS and predicting hip joint involvement at an early stage.

Electronic supplementary material

The online version of this article (10.1186/s12865-018-0280-x) contains supplementary material, which is available to authorized users.

Acute Sarcomeric M-Line Disease Associated With ATP Synthase Subunit α Autoantibodies in Ankylosing Spondylitis

M-line is the narrow transverse band located in the center of the sarcomeric A-band that is mainly responsible for the stabilization of myosin thick filaments. A 27-year-old male patient with a positive medical history for ankylosing spondylitis presented with one month of proximal upper limb muscle weakness associated with pain on both acromioclavicular joints. A biopsy of deltoid muscle documented the disappearance of M-line, the misalignment of myofilaments, and the loss of the distinction between the A and I bands. Complete resolution of muscle weakness occurred after one year of treatment with antiTNFα agent Etanercept. Because of the acute onset of symptoms and the recovery after immunosuppressive treatment we hypothesized that an immune-mediated mechanism was responsible for the muscle disorder. The serum IgG-mediated autoreactivity to skeletal muscle antigens resolved by bidimensional electrophoresis was assessed in the described patient and compared with that of control subjects. The comparative analysis of the immunoreactive spots revealed that ATP synthase subunit α is specifically recognized by patient's serum, suggesting that the protein might represent a putative antigenic target in the disease. This study reports an acute reversible myopathy pathologically characterized by M-line involvement and associated with serological antibodies to the subunit α of ATP synthase.

Nature versus nurture in the spectrum of rheumatic diseases: Classification of spondyloarthritis as autoimmune or autoinflammatory

Spondyloarthritides (SpA) include inflammatory joint diseases with various clinical phenotypes that may also include the axial skeleton and/or entheses. SpA include psoriatic arthritis, reactive arthritis, enteropathic arthritis and ankylosing spondylitis; the latter is frequently associated with extra-articular manifestations, such as uveitis, psoriasis, and inflammatory bowel disease. SpA are associated with the HLA-B27 allele and recognize T cells as key pathogenetic players. In contrast to other rheumatic diseases, SpA affect women and men equally and are not associated with detectable serum autoantibodies. In addition, but opposite to rheumatoid arthritis, SpA are responsive to treatment regimens including IL-23 or IL-17-targeting biologics, yet are virtually unresponsive to steroid treatment. Based on these differences with prototypical autoimmune diseases, such as rheumatoid arthritis or connective tissue diseases, SpA may be better classified among autoinflammatory diseases, with a predominant innate immunity involvement. This would rank SpA closer to gouty arthritis and periodic fevers in the spectrum of rheumatic diseases, as opposed to autoimmune-predominant diseases. We herein provide available literature on risk factors associated with SpA in support of this hypothesis with a specific focus on genetic and environmental factors.

Autoimmunity in 2016

The number of peer-reviewed articles published during the 2016 solar year and retrieved using the "autoimmunity" key word remained stable while gaining a minimal edge among the immunology articles. Nonetheless, the quality of the publications has been rising significantly and, importantly, acquisitions have become available through scientific journals dedicated to immunology or autoimmunity. Major discoveries have been made in the fields of systemic lupus erythematosus, rheumatoid arthritis, autoimmunity of the central nervous system, vasculitis, and seronegative spondyloarthrithritides. Selected examples include the role of IL17-related genes and long noncoding RNAs in systemic lupus erythematosus or the effects of anti-pentraxin 3 (PTX3) in the treatment of this paradigmatic autoimmune condition. In the case of rheumatoid arthritis, there have been reports of the role of induced regulatory T cells (iTregs) or fibrocytes and T cell interactions with exciting implications. The large number of studies dealing with neuroimmunology pointed to Th17 cells, CD56(bright) NK cells, and low-level TLR2 ligands as involved in multiple sclerosis, along with a high salt intake or the micriobiome-derived Lipid 654. Lastly, we focused on the rare vasculitides to which numerous studies were devoted and suggested that unsuspected cell populations, including monocytes, mucosal-associated invariant T cells, and innate lymphoid cells, may be crucial to ANCA-associated manifestations. This brief and arbitrary discussion of the findings published in 2016 is representative of a promising background for developments that will enormously impact the work of laboratory scientists and physicians at an exponential rate.

Gastrointestinal and Hepatic Disease in Spondyloarthritis

The association of inflammatory arthritis with intestinal pathology extends back more than 100 years. This association is now supported by epidemiologic studies demonstrating an elevated prevalence of inflammatory bowel disease in spondyloarthritis and vice versa, compared with the general population. Genetic and intestinal microbiome studies have further linked these diseases. Although diabetes and nonalcoholic fatty liver disease disproportionately affect individuals with psoriatic arthritis, diseases of the esophagus, stomach, pancreas, and liver are not particularly common in spondyloarthritis. Clinicians should be aware of the differential diagnosis and the appropriate diagnostic tools available when evaluating digestive and hepatic disorders in spondyloarthritis.

Serum HMGB1 Serves as a Novel Laboratory Indicator Reflecting Disease Activity and Treatment Response in Ankylosing Spondylitis Patients

Objective. High mobility group box 1 (HMGB1) is a late inflammatory factor participating in the pathogenesis of various autoimmune and inflammatory diseases. In the current study, we analyzed the association between serum levels of HMGB1 and clinical features of AS patients before and during treatment. Methods. Serum HMGB1 was detected in 147 AS patients and 61 healthy controls using ELISA. We evaluated the association between HMGB1 and extra-articular manifestations as well as disease severity indices. Among these AS patients, 41 patients received close follow-up at 1, 3, and 6 months after treatment. This group comprised 25 patients treated with anti-TNF-α biologics and 16 patients receiving oral NSAIDs plus sulfasalazine. Results. The serum HMGB1 of AS patients was significantly higher than in healthy controls and positively correlated with BASDAI, BASFI, ASDAS-ESR, ASDAS-CRP, ESR, and CRP, but not with HLA-B27, anterior uveitis, and recurrent diarrhea. There was no significant difference between patients with radiographic damage of hip joints and those without. We observed that serum HMGB1 paralleled disease activity after treatment. Conclusion. Serum level of HMGB1 is higher in AS patients, and to some extent, HMGB1 can reflect the activity of AS and be used as a laboratory indicator to reflect the therapeutic response.