Pathogenesis of spondyloarthritis: autoimmune or autoinflammatory?

Predictors of treatment failure of non-steroidal anti-inflammatory drugs in patients with axial spondyloarthritis with focus on haptoglobin, haptoglobin polymorphism and zonulin

According to the Assessment of SpondyloArthritis International Society-European Alliance of Associations for Rheumatology (ASAS-EULAR) recommendations for the management of axial spondyloarthritis (axSpA), patients should undergo at least two courses of non-steroidal anti-inflammatory drugs (NSAIDs) therapy. In our study, we enrolled axSpA patients both at onset and in a flare who had already been treated with NSAIDs ineffectively. Subsequently, according to the recommendations, they received modified NSAID treatment as another attempt to the first-line drug therapy and were monitored from there. We aimed to identify risk factors for treatment failure after 4 weeks (Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) score ≥ 4) especially amongst zonulin and haptoglobin concentrations, and haptoglobin polymorphism. Treatment failure was observed in 71% of patients, and the following variables were contributed for occurrence of this state: higher zonulin levels, ankylosing spondylitis, X-ray sacroiliitis, magnetic resonance imaging sacroiliitis, long duration of symptoms, high BASDAI, and high value of spinal pain intensity on visual analogue scale. In addition, the following positive correlations were found: haptoglobin concentration with C-reactive protein (r = 0.56; p = 0.0004), and erythrocyte sedimentation rate (r = 0.62; p < 0.0001), as well as between zonulin levels and white blood count (r = 0.5; p = 0.0003). The results of the study presented the identified factors related to the standard treatment failure in axSpA, amongst them zonulin levels. They might be applied to point out the patients for whom the search for a more appropriate method of treatment should be considered.

Estradiol is a key candidate for treating Ankylosing Spondylolisthesis with Traditional Chinese Medicine

Some Traditional Chinese Medicine (TCM) has shown anti-inflammatory and immunosuppressive effects on Ankylosing Spondylitis (AS) treatment. Wan Bikang (WBK) and Wan Biqing (WBQ) are two traditional empirical formulas for AS. However, the mechanism of their effects on AS is largely unknown. This study deciphered the underlying common molecular mechanisms of these TCM treatments for AS. The ultra-high-performance liquid chromatography-triple/time-of-flight mass spectrometry (UHPLC-Q-TOF-MS/MS) assays were employed to detect herbal ingredients. Target proteins of herbal ingredients were identified by ChEMBL Database. To infer the relationships between ingredients and AS-related proteins, network pharmacology was employed. Protein-protein interaction (PPI) network and core target analyses were carried out with tools Cytoscape and STRING. To find out the molecular basis and target of AS, molecular docking and an in vitro experiment were also conducted. It is found that estradiol may participate in the treatment of AS via the inhibition of inflammatory factors, and Estrogen Receptor 1 (ESR1) appears to be a key target. This research offers insight into the therapeutic mechanism of TCM formulas for AS and furthers our understanding of TCM pharmacology.

Monocyte subpopulations display disease-specific miRNA signatures depending on the subform of Spondyloarthropathy

Spondyloarthropathies (SpA) are a family of rheumatic disorders that could be divided into axial (axSpA) and peripheral (perSpA) sub-forms depending on the disease clinical presentation. The chronic inflammation is believed to be driven by innate immune cells such as monocytes, rather than self-reactive cells of adaptive immune system. The aim of the study was to investigate the micro-RNA (miRNA) profiles in monocyte subpopulations (classical, intermediate and non-classical subpopulations) acquired from SpA patients or healthy individuals in search for prospective disease specific and/or disease subtype differentiating miRNA markers. Several SpA-specific and axSpA/perSpA differentiating miRNAs have been identified that appear to be characteristic for specific monocyte subpopulation. For classical monocytes, upregulation of miR-567 and miR-943 was found to be SpA-specific, whereas downregulation of miR-1262 could serve as axSpA-differentiating, and the expression pattern of miR-23a, miR-34c, mi-591 and miR-630 as perSpA-differentiating markers. For intermediate monocytes, expression levels of miR-103, miR-125b, miR-140, miR-374, miR-376c and miR-1249 could be used to distinguish SpA patients from healthy donors, whereas the expression pattern of miR-155 was identified as characteristic for perSpA. For non-classical monocytes, differential expression of miR-195 was recognized as general SpA indicator, while upregulation of miR-454 and miR-487b could serve as axSpA-differentiating, and miR-1291 as perSpA-differentiating markers. Our data indicate for the first time that in different SpA subtypes, monocyte subpopulations bear disease-specific miRNA signatures that could be relevant for SpA diagnosis/differentiation process and may help to understand SpA etiopathology in the context of already known functions of monocyte subpopulations.

The effectiveness of hippotherapy simulation exercises for muscle strength, disease activity and quality of life in sedentary adults with ankylosing spondylitis

INTRODUCTION/OBJECTIVE

Newly created systems called hippotherapy simulators (HS) mimic the primitive movements of a live horse. As they are new systems, research examining their usefulness has been well received. The aim of this study is to research the effects of HS on disease activity, quality of life and muscle strength in patients with ankylosing spondylitis (AS).

METHODS

In a prospective, assessor-blinded, block-randomized trial, 48 AS patients were randomly assigned in a 1:1 ratio to receive either HS or conventional home (CH) exercise therapy. All Participants received 48 sessions, that is 4 sessions a week for 12 consecutive weeks. The primary outcome measures included the quadriceps muscle strength, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Bath Ankylosing Spondylitis Metrology Index (BASMI) and Ankylosing Spondylitis Quality of Life Scale (ASQoL).

RESULTS

Both groups demonstrated significant improvement in BASDAI, BASFI, BASMI, ASQoL and muscle strength scores compared to the baseline (p < 0.05). BASDAI, BASFI and BASMI scores decreased significantly in the HS group compared to the CH group at week 12 (p=.005, p=.003, p=.045, respectively), but there was no significant difference between the groups in terms of ASQoL and muscle strength scores at week 12 (p=.245, p=.212, respectively).

CONCLUSIONS

The results of this clinical trial of HS exercises for AS patients indicate a positive effect on disease activity, quality of life and muscle strength. Therefore, horse-riding simulator exercises can be used as an alternative method for the management of individuals with AS.

Identification of variants in genes associated with autoinflammatory disorders in a cohort of patients with psoriatic arthritis

Objectives

Besides adaptive immunity genes, genetic risk factors for psoriatic arthritis (PsA) include innate immunity loci, which suggests an autoinflammatory disease mechanism, at least in a subset of patients. Here, we aimed at investigating the autoinflammatory genetic background of PsA.

Methods

A total of 120 patients with PsA visiting the outpatient clinics of the Hannover University hospital underwent targeted next-generation sequencing, searching for variations in genes linked with inborn errors of immunity classified as autoinflammatory disorders (AIDs). Deleteriousness of rare variants was evaluated through in silico analysis.

Results

We found 45 rare predicted deleterious variants in 37 out of 120 (30.8%) patients with PsA. Relatively common were variants in AP1S3, PLCG2, NOD2 and NLRP12. All 45 variants were monoallelic and 25 of them, identified in 20 out of 120 (16.7%) patients, were localised in genes associated with autosomal dominant (AD) disorders. Detection of those variants is associated with pustular psoriasis or a coexisting inflammatory bowel disease (IBD).

Conclusions

Approximately 30% of patients with PsA harboured at least one variant in a gene associated with an AID, suggesting an autoinflammatory disease mechanism. Detection of variants in genes linked to AD-AIDs may explain extra-articular manifestations of PsA, such as pustular psoriasis and IBD.

Atlantoaxial instability and cervical noninfectious spondylodiscitis in a patient with Wegener’s granulomatosis: A case report

A 61‐year‐old male patient with Wegener's granulomatosis was admitted due to neck pain and quadriparesis. Clinical evaluation showed severe cervical noninfectious spondylodiscitis, myelopathy, sagittal imbalance, and atlantoaxial instability. A combined anterior and posterior approach was implemented. Postoperative clinical evaluation showed improved neurologic status.

Monocytes and Macrophages in Spondyloarthritis: Functional Roles and Effects of Current Therapies

Spondyloarthritis (SpA) is a family of chronic inflammatory diseases, being the most prevalent ankylosing spondylitis (AS) and psoriatic arthritis (PsA). These diseases share genetic, clinical and immunological features, such as the implication of human leukocyte antigen (HLA) class I molecule 27 (HLA-B27), the inflammation of peripheral, spine and sacroiliac joints and the presence of extra-articular manifestations (psoriasis, anterior uveitis, enthesitis and inflammatory bowel disease). Monocytes and macrophages are essential cells of the innate immune system and are the first line of defence against external agents. In rheumatic diseases including SpA, the frequency and phenotypic and functional characteristics of both cell types are deregulated and are involved in the pathogenesis of these diseases. In fact, monocytes and macrophages play key roles in the inflammatory processes characteristics of SpA. The aim of this review is analysing the characteristics and functional roles of monocytes and macrophages in these diseases, as well as the impact of different current therapies on these cell types.

The Complement System in Spondyloarthritis: What Do We Know?

Spondyloarthritis (SpA) encompasses a group of rheumatologic diseases, including axial spondyloarthritis (axSpA), psoriatic arthritis, arthritis with associated inflammatory bowel disease (i.e. Crohn’s disease and ulcerative colitis), reactive arthritis and undifferentiated SpA, which all share certain clinical, biological and genetic features. However, the pathogenesis remains largely unexplained. Recent evidence suggests an autoinflammatory component of the disease. The complement system is a cornerstone of the innate immune system. This review aims to evaluate the current knowledge of the complement system in SpA. Animal models have shown that complement activation is associated with axSpA. Complement proteins L-ficolin and H-ficolin levels are elevated in patients with axSpA, and complement factor C3 levels decrease after the initiation of tumour necrosis factor-inhibitor therapy. Associations with disease activity are inconsistent, as one study found that the serum levels of complement factors C3 and C4 did not differ in patients with different Bath Ankylosing Spondylitis Disease Activity Index scores but, in another study, were associated with baseline Ankylosing Spondylitis Disease Activity Score with C-reactive protein and Bath Ankylosing Spondylitis Disease Activity Index improvement after treatment with a tumour necrosis factor inhibitor. Future studies should focus on the complement system in various SpA entities, involvement in pathogenesis and disease progression under clinically relevant conditions.

Overexpression of Transmembrane TNF Drives Development of Ectopic Lymphoid Structures in the Bone Marrow and B Cell Lineage Alterations in Experimental Spondyloarthritis

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.

SARS-CoV-2 Infection in Spondyloarthritis Patients Treated With Biotechnological Drugs: A Study on Serology

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.

Ankylosing spondylitis: an autoimmune or autoinflammatory disease?

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.

Vagal Nerve Stimulation-Modulation of the Anti-Inflammatory Response and Clinical Outcome in Psoriatic Arthritis or Ankylosing Spondylitis

Objectives

The vagal nerve exerts an essential pathway in controlling the cholinergic anti-inflammatory reflex. Thus, the study is aimed at investigating the acute effect of a noninvasive transcutaneous vagus nerve stimulation on clinical disease activity and systemic levels of inflammation in patients with psoriatic arthritis or ankylosing spondylitis.

Methods

Twenty patients with psoriatic arthritis (PsA) and 20 patients with ankylosing spondylitis (AS) were included and stimulated bilaterally with a handheld vagal nerve stimulator for 120 seconds 3 times a day for 5 consecutive days. All patients were in remission. Cardiac vagal tone, clinical scores, CRP, and cytokine levels were assessed.

Results

In PsA and AS, decreased heart rate was observed, confirming compliance. Furthermore, in PsA, a clear reduction of clinical disease activity associated with a 20% reduction in CRP was shown. In AS, a reduction in interferon-γ, interleukin- (IL-) 8, and 10 was shown. No side effects were described.

Conclusion

This open-label study provides support for an anti-inflammatory effect of transcutaneous vagus nerve stimulation in patients with psoriatic arthritis and ankylosing spondylitis. The modulated immune response and reduced disease activity and CRP-levels raise the fascinating possibility of using neuromodulation as an add-on to existing pharmacological treatments.

Expression of VEGFA-mRNA in classical and MSX2-mRNA in non-classical monocytes in patients with spondyloarthritis is associated with peripheral arthritis

Spondyloarthritis (SpA) is characterized by chronic inflammation and structural damage involving spine and peripheral joints. Monocytes, as part of innate immune system, following migration into affected tissue, may play a role in the pathogenesis of SpA. Here, potential associations between osteogenesis-linked gene expression profile in particular monocyte subpopulations and clinical signs of SpA were investigated. The 20 patients with axial and 16 with peripheral SpA were enrolled in the study. Monocyte subpopulations (classical—CD14⁺⁺CD16⁻, intermediate—CD14⁺⁺CD16⁺ and non-classical—CD14⁺CD16⁺⁺) were isolated from blood using flow cytometry and gene expression analysis was performed using real-time PCR method and TaqMan Array, Human Osteogenesis, Fast 96-well plates. Next, the characteristic clinical features shared by axial and peripheral SpA were analyzed in the context of the expression of selected genes in the three subpopulations of monocytes. We demonstrated that expression of VEGFA in classical and MSX2 in non-classical monocytes were associated with the number of swollen and painful peripheral joints of SpA patients. We conclude that monocytes may contribute to the development of peripheral arthritis in SpA patients. This might be possible through subpopulation specific effects, linking number of inflamed joints with expression of VEGFA in classical monocytes and MSX2 in non-classical monocytes.

Farrerol ameliorate adjuvant-induced ankle injury via alteration of PPAR-γ signal pathway

This study evaluated the anti-inflammatory activity against lipopolysaccharide (LPS)-mediated mouse macrophages (in vitro) and assessed the protective effect of farrerol on arthritis caused by complete freund adjuvant (CFA) in rats. For the evaluation of the pharmacological effect of farrerol on the activity of nitric oxide (NO) and cyclooxygenase, pro-inflammatory cytokines including interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), and interleukin-1β, RAW 264.7 cells were used. A 0.1 ml CFA was injected subcutaneously for the induction of arthritis. The paw volume, body weight and arthritic score were estimated at regular intervals. Pro-inflammatory cytokines, inflammatory mediators, and antioxidant parameters were also estimated. Farrerol suppressed NO production and COX-catalyzed prostaglandin (PGE₂ ) in RAW 264.7. Farrerol also downregulated the p-p65, p-IκBα expression and upregulated the PPAR-γ expression in RAW 264.7 cells. Treatment of farrerol increased body weight substantially, and reduced paw edema and arthritic score. Farrerol treatment also significantly improved the level of hemoglobin (Hb), count of red blood cells (RBC), and decreased the rate of erythrocyte sedimentation (ESR), white blood cell (WBC) parameters, while the generation of pro-inflammatory cytokines inhibited. Together, farrerol also suppressed the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β. Obtained results directed that the farrerol exerted its therapeutic effect against CFA-induced arthritic rats through anti-inflammatory mechanism by regulation of the PPAR-γ. PRACTICAL APPLICATIONS: Increase the arthritis disease worldwide day-by-day. The current research study showed the anti-arthritic effect of farrerol (flavonoid phytoconstituent) of Rhododendron dauricum Linn. In this study, farrerol considerably inhibited the NF-κB to show the anti-arthritic effect. The finding showed the potential effect against acute and chronic inflammation via inhibition of inflammatory mediators and oxidative stress. The result suggests the anti-inflammatory and antioxidant effect of farrerol. On the basis of result, we can say that farrerol can be the beneficial drug to treat the arthritis.

Evaluating the strength of spinal and proximal girdle muscles in patients with axial spondyloarthritis: Correlation with activity, disability, and functionality

AIM

To compare the muscle strength of muscle groups in axial spondyloarthritis (axSpA) patients with the muscle powers of healthy volunteers and to examine the relationship of muscle strengths with disease activity, functionality, and disability.

METHOD

One hundred males (50 axSpA, 50 healthy) were included in the study. Bath Disease Activity Index (BASDAI), Functional Index (BASFI), and Health Assessment Questionnaire-Disability Index (HAQ-DI) scores were recorded. The maximum (max) and mean cervical flexion, extension, lateral flexion (CF, CE, CLF), truncal flexion, extension (TF, TE), root joint flexion, extension, abduction, internal and external rotation (SF, SE, SAB, SIR and SER for the shoulder; HF, HE, HAB, HIR and HER for the hip) muscle strengths of the patients in both groups were measured by a handheld dynamometer. Total muscle strength (CT, TT, ST, HT) was found according to the sum of the max and mean values for each region.

RESULTS

All muscle strengths were lower in the axSpA group compared to the healthy volunteers. The symptom duration was found to have a weak-moderate negative correlation with CT, TT, ST, HT and all individual muscle strengths except for the TE, CF, HIR, and HER. BASDAI and HAQ-DI had weak-moderate negative correlations with HIR and HER. BASFI had a weak-moderate negative correlation with cervical measurements, TE, TF, SF, SER, SIR, and hip measurements.

CONCLUSION

All muscle strengths were lower in patients compared to healthy volunteers. Strengthening specific muscle groups for the desired goal can be a reasonable strategy. The study is prospectively registered and available at www.clinicaltrials.gov (NCT04435860).

Haptoglobin and Its Related Protein, Zonulin-What Is Their Role in Spondyloarthropathy?

Haptoglobin (Hp) is an acute phase protein which supports the immune response and protects tissues from free radicals. Its concentration correlates with disease activity in spondyloarthropathies (SpAs). The Hp polymorphism determines the functional differences between Hp1 and Hp2 protein products. The role of the Hp polymorphism has been demonstrated in many diseases. In particular, the Hp 2-2 phenotype has been associated with the unfavorable course of some inflammatory and autoimmune disorders. Its potential role in modulating the immune system in SpA is still unknown. This article contains pathophysiological considerations on the potential relationship between Hp, its polymorphism and SpA.

Proteinase-Mediated Macrophage Signaling in Psoriatic Arthritis

Objective

Multiple proteinases are present in the synovial fluid (SF) of an arthritic joint. We aimed to identify inflammatory cell populations present in psoriatic arthritis (PsA) SF compared to osteoarthritis (OA) and rheumatoid arthritis (RA), identify their proteinase-activated receptor 2 (PAR2) signaling function and characterize potentially active SF serine proteinases that may be PAR2 activators.

Methods

Flow cytometry was used to characterize SF cells from PsA, RA, OA patients; PsA SF cells were further characterized by single cell 3’-RNA-sequencing. Active serine proteinases were identified through cleavage of fluorogenic trypsin- and chymotrypsin-like substrates, activity-based probe analysis and proteomics. Fluo-4 AM was used to monitor intracellular calcium cell signaling. Cytokine expression was evaluated using a multiplex Luminex panel.

Results

PsA SF cells were dominated by monocytes/macrophages, which consisted of three populations representing classical, non-classical and intermediate cells. The classical monocytes/macrophages were reduced in PsA compared to OA/RA, whilst the intermediate population was increased. PAR2 was elevated in OA vs. PsA/RA SF monocytes/macrophages, particularly in the intermediate population. PAR2 expression and signaling in primary PsA monocytes/macrophages significantly impacted the production of monocyte chemoattractant protein-1 (MCP-1). Trypsin-like serine proteinase activity was elevated in PsA and RA SF compared to OA, while chymotrypsin-like activity was elevated in RA compared to PsA. Tryptase-6 was identified as an active serine proteinase in SF that could trigger calcium signaling partially via PAR2.

Conclusion

PAR2 and its activating proteinases, including tryptase-6, can be important mediators of inflammation in PsA. Components within this proteinase-receptor axis may represent novel therapeutic targets.

IL-23 Inhibition in Ankylosing Spondylitis: Where Did It Go Wrong?

Axial spondyloarthritis is a prevalent form of chronic arthritis which is related to psoriatic arthritis and skin psoriasis. TNF and IL-17A as well as IL-17F are key cytokines contributing to the pathobiology of this disease, as evidence by the therapeutic efficacy of inhibition of these factors. Despite the evidence that IL-23 acts as an upstream driver of Th17 cells, the T lymphocytes producing IL-17, and that IL-23 inhibition shows profound efficacy in psoriasis, blocking IL-23 failed to show any evidence of clinical efficacy in axial spondyloarthritis. In this viewpoint article, we revisit the reasons-to-believe in a role of IL-23 in the pathobiology of axial spondyloarthritis, discuss what we have learned on the pathobiology of this disease in general and on the function of the IL-23/IL-17 axis in particular, and share a handful of lessons learned that are of relevance for the translation of emerging biological insights into clinical therapeutics.

Detection of selection signatures for response to Aleutian mink disease virus infection in American mink

Aleutian disease (AD) is the most significant health issue for farmed American mink. The objective of this study was to identify the genomic regions subjected to selection for response to infection with Aleutian mink disease virus (AMDV) in American mink using genotyping by sequencing (GBS) data. A total of 225 black mink were inoculated with AMDV and genotyped using a GBS assay based on the sequencing of ApeKI-digested libraries. Five AD-characterized phenotypes were used to assign animals to pairwise groups. Signatures of selection were detected using integrated measurement of fixation index (F_ST) and nucleotide diversity (θπ), that were validated by haplotype-based (hap-FLK) test. The total of 99 putatively selected regions harbouring 63 genes were detected in different groups. The gene ontology revealed numerous genes related to immune response (e.g. TRAF3IP2, WDR7, SWAP70, CBFB, and GPR65), liver development (e.g. SULF2, SRSF5) and reproduction process (e.g. FBXO5, CatSperβ, CATSPER4, and IGF2R). The hapFLK test supported two strongly selected regions that contained five candidate genes related to immune response, virus–host interaction, reproduction and liver regeneration. This study provided the first map of putative selection signals of response to AMDV infection in American mink, bringing new insights into genomic regions controlling the AD phenotypes.

Leukocyte toll-like receptor expression in pathergy positive and negative Behçet's disease patients

Objectives

To investigate whether the auto-inflammatory nature and the pathergic reaction in Behçet’s disease (BD) are driven by a disturbed toll-like receptor (TLR) response.

Methods

We compared both TLR expression by flow-cytometry and TLR response by stimulation assay in 18 BD patients (both pathergy positive and pathergy negative) with 15 healthy controls.

Results

Expression of TLR1 and 2 was significantly elevated in B-lymphocytes of BD patients compared with healthy controls. TLR1, 2 and 4 were significantly more highly expressed in both CD4⁺ and CD8⁺ T-lymphocytes of BD patients. Granulocytes of BD patients displayed significantly higher expression of TLR1, 2, 4 and 6. TLR2, 4 and 5 expression was significantly increased on classical monocytes of BD patients. Intermediate monocytes of BD patients showed an increase in expression of TLR2. Furthermore, TLR2 and 5 were significantly more highly expressed in non-classical monocytes of BD patients. In pathergy positive patients, TLR5 was even more highly expressed compared with pathergy negative patients on B- and T-lymphocytes and granulocytes. Furthermore, TLR2 and 5 showed an elevated TNF-α response to stimulation with their cognate ligands.

Conclusion

Immune cells of BD patients overexpress TLR1, 2, 4, 5 and 6. Furthermore, after stimulation of TLR2 and 5, BD patients demonstrate a more potent TNF-α response. Although this is a small cohort, in the pathergy positive patients, TLR5 expression is even further augmented, suggesting that a microbial (flagellin) or damage (HMGB1) associated signal may trigger the exaggerated immune response that is characteristic for the pathergy phenomenon in BD. In conclusion, these results point to an exaggerated TLR response in the auto-inflammatory nature of BD.

Neutrophil extracellular traps and inflammatory response: Implications for the immunopathogenesis of ankylosing spondylitis

AIM

Ankylosing spondylitis (AS) pathogenesis has focused on the adaptive immune response; however, innate immune responses may also play a role in the inflammatory response of AS. Dysregulated neutrophil activation can induce tissue damage and contribute to the pathogenesis of immune-related diseases. Hence, the aim of this study was to assess the effect of immune complexes formed with the p30 of Salmonella typhimurium and anti-p30 antibodies present in the sera of AS patients and controls in inducing the release of neutrophil extracellular traps (NETs) and the secretion of pro-inflammatory cytokines.

METHODS

We collected polymorphonuclear leukocytes (PMNs) from healthy donors. The PMNs isolated were stimulated with p30 alone or in immunocomplexes formed with antibodies presents in sera of AS patients or control subjects. Then, the NETs were analyzed by fluorescence microscopy. Concentrations of interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, IL-8 and IL-10, were determined using the Cytometric Bead Array kit.

RESULTS

Significant difference was observed in the release of NETs between the neutrophils stimulated with p30 + AS (70.52 ± 16.24) those unstimulated neutrophils (9.94 ± 12.12; P = .0095), stimulated with phorbol 12-myristate 13-acetate (39.78 ± 14.50; P = .0190), stimulated with control serum (CS) (10.85 ± 5.33; P = .0082) and serum of AS patient (10.28 ± 6.15; P = .0087). The stimulation of neutrophils with p30 alone induced a relatively low production of IL-6 (64.5 pg/mL), IL-8 (2658.3 pg/mL), IL-1β (31.11 pg/mL), and TNF-α (3.8 pg/mL), compared to p30 + AS and p30 + CS groups.

CONCLUSION

Our results show that neutrophils release NETs and pro-inflammatory cytokines in response to p30 in immunocomplexes. These findings could improve our understanding of the role of innate immunity in the initiation and/or maintenance of inflammatory responses, and in the progression of AS.

Hearing Loss in Patients With Ankylosing Spondylitis: A Systematic Review and Metaanalysis

OBJECTIVE

To determine the prevalence of hearing loss (HL) in patients with ankylosing spondylitis (AS) and to describe frequency-specific hearing threshold changes in this patient population compared to patients without AS.

METHODS

A systematic review querying 4 databases (PubMed, OVID Medline, Scopus, Cochrane) was performed to identify studies evaluating HL in patients with AS. Metaanalysis was performed to identify overall prevalence rate and OR of HL, as well as to compare mean differences in frequency-specific hearing thresholds between patients with and without AS.

RESULTS

Our metaanalysis included 14 studies and 1083 patients (598 with AS vs 485 without AS). The pooled prevalence of HL in patients with AS was 42.4% (95% CI 29.2-56.2). Patients with AS had a significantly higher OR of HL than patients without AS (OR 4.65, 95% CI 2.73-7.91). Mean differences in pure-tone hearing thresholds ranged from 0-5 decibels (dB) for frequencies of 0.25-4 kHz, and from 5-15 dB for frequencies of 6-16 kHz.

CONCLUSION

Patients with AS have higher odds of having HL than patients without AS. The AS population also presents with significantly impaired hearing thresholds across all conventional and extended pure-tone frequencies. This may manifest as slight to moderate HL. Results of this systematic review might justify increased attention to audiologic manifestations of patients with AS.

Uveitis in spondyloarthritis

Uveitis is the most frequent extra-articular manifestation of axial spondyloarthritis (SpA), occurring in up to one-third of the patients. In the majority of patients, uveitis is acute, anterior and unilateral and presents with photosensitivity, sudden onset of pain and blurred vision. Topical steroids are an effective treatment; however, recurrent or refractory cases may need conventional disease-modifying antirheumatic drugs or biological treatment with monoclonal tumor necrosis factor (TNF) inhibitors, thus also influencing treatment strategy of the underlying SpA. Though the exact pathogenesis of SpA and uveitis remains unknown, both seem to result from the interaction of a specific, mostly shared genetical background (among other HLA-B27 positivity), external influences such as microbiome, bacterial infection or mechanical stress and activation of the immune system resulting in inflammation. Up to 40% of patients presenting with acute anterior uveitis (AAU) have an undiagnosed SpA. Therefore, an effective referral strategy for AAU patients is needed to shorten the diagnostic delay of SpA and enable an early effective treatment. Further, the risk for ophthalmological manifestations increases with the disease duration in SpA; and patients presenting with ocular symptoms should be referred to an ophthalmologist. Thus, a close collaboration between patient, rheumatologist and ophthalmologist is needed to optimally manage ocular inflammation in SpA.

Translating IL-6 biology into effective treatments

In 1973, IL-6 was identified as a soluble factor that is secreted by T cells and is important for antibody production by B cells. Since its discovery more than 40 years ago, the IL-6 pathway has emerged as a pivotal pathway involved in immune regulation in health and dysregulation in many diseases. Targeting of the IL-6 pathway has led to innovative therapeutic approaches for various rheumatic diseases, such as rheumatoid arthritis, juvenile idiopathic arthritis, adult-onset Still’s disease, giant cell arteritis and Takayasu arteritis, as well as other conditions such as Castleman disease and cytokine release syndrome. Targeting this pathway has also identified avenues for potential expansion into several other indications, such as uveitis, neuromyelitis optica and, most recently, COVID-19 pneumonia. To mark the tenth anniversary of anti-IL-6 receptor therapy worldwide, we discuss the history of research into IL-6 biology and the development of therapies that target IL-6 signalling, including the successes and challenges and with an emphasis on rheumatic diseases.

In this Perspective article, the authors recount the earliest stages of translational research into IL-6 biology and the subsequent development of therapeutic IL-6 pathway inhibitors for the treatment of autoimmune rheumatic diseases and potentially numerous other indications.

Promotion of macrophage activation by Tie2 in the context of the inflamed synovia of rheumatoid arthritis and psoriatic arthritis patients

OBJECTIVE

To examine the role of Tie2 signalling in macrophage activation within the context of the inflammatory synovial microenvironment present in patients with RA and PsA.

METHODS

Clinical responses and macrophage function were examined in wild-type and Tie2-overexpressing (Tie2-TG) mice in the K/BxN serum transfer model of arthritis. Macrophages derived from peripheral blood monocytes from healthy donors, RA and PsA patients, and RA and PsA synovial tissue explants were stimulated with TNF (10 ng/ml), angiopoietin (Ang)-1 or Ang-2 (200 ng/ml), or incubated with an anti-Ang2 neutralizing antibody. mRNA and protein expression of inflammatory mediators was analysed by quantitative PCR, ELISA and Luminex.

RESULTS

Tie2-TG mice displayed more clinically severe arthritis than wild-type mice, accompanied by enhanced joint expression of IL6, IL12B, NOS2, CCL2 and CXCL10, and activation of bone marrow-derived macrophages in response to Ang-2 stimulation. Ang-1 and Ang-2 significantly enhanced TNF-induced expression of pro-inflammatory cytokines and chemokines in macrophages from healthy donors differentiated with RA and PsA SF and peripheral blood-derived macrophages from RA and PsA patients. Both Ang-1 and Ang-2 induced the production of IL-6, IL-12p40, IL-8 and CCL-3 in synovial tissue explants of RA and PsA patients, and Ang-2 neutralization suppressed the production of IL-6 and IL-8 in the synovial tissue of RA patients.

CONCLUSION

Tie2 signalling enhances TNF-dependent activation of macrophages within the context of ongoing synovial inflammation in RA and PsA, and neutralization of Tie2 ligands might be a promising therapeutic target in the treatment of these diseases.

GM-CSF drives dysregulated hematopoietic stem cell activity and pathogenic extramedullary myelopoiesis in experimental spondyloarthritis

Dysregulated hematopoiesis occurs in several chronic inflammatory diseases, but it remains unclear how hematopoietic stem cells (HSCs) in the bone marrow (BM) sense peripheral inflammation and contribute to tissue damage in arthritis. Here, we show the HSC gene expression program is biased toward myelopoiesis and differentiation skewed toward granulocyte-monocyte progenitors (GMP) during joint and intestinal inflammation in experimental spondyloarthritis (SpA). GM-CSF-receptor is increased on HSCs and multipotent progenitors, favoring a striking increase in myelopoiesis at the earliest hematopoietic stages. GMP accumulate in the BM in SpA and, unexpectedly, at extramedullary sites: in the inflamed joints and spleen. Furthermore, we show that GM-CSF promotes extramedullary myelopoiesis, tissue-toxic neutrophil accumulation in target organs, and GM-CSF prophylactic or therapeutic blockade substantially decreases SpA severity. Surprisingly, besides CD4+ T cells and innate lymphoid cells, mast cells are a source of GM-CSF in this model, and its pathogenic production is promoted by the alarmin IL-33.

Plasma levels of H- and L-ficolin are increased in axial spondyloarthritis: improvement of disease identification

Axial spondyloarthritis (axSpA) is a chronic inflammatory disease that primarily affects the axial skeleton. A predominance of innate versus adaptive immune responses have been reported in axSpA, indicating a prominent autoinflammatory component of the disease. Little is known about the lectin pathway proteins (LPPs) of the complement system in relation to axSpA. We have investigated LPPs in patients with axSpA and control individuals. Plasma samples were obtained from a cross-sectional cohort of 120 patients with a clinical diagnosis of axSpA and from 144 age- and gender-matched controls. The plasma concentrations of 11 LPPs were measured, using sandwich-type time-resolved immunofluorometric assays in patients and controls, and related to clinical diagnosis and disease activity. Three LPPs [H-ficolin (ficolin-3), L-ficolin (ficolin-2) and collectin liver 1 (CL-L1)] were significantly higher in axSpA patients than in controls (P < 0·0001) and one LPP, collectin kidney 1 (CL-K1), was significantly lower (P < 0·0001). Further, combining H- or L-ficolin concentrations above the 75th percentile of the respective H- or L-ficolin concentration measured in controls with human leucocyte antigen (HLA)-B27 positivity yielded axSpA diagnostic specificities of 99/99% and positive likelihood ratios of 68/62, respectively. H-ficolin and L-ficolin plasma concentrations were found to be elevated in axSpA patients regardless of time since diagnosis. H-ficolin and L-ficolin may represent diagnostic biomarkers for patients with axSpA and should be further evaluated. Our results showed no association between disease activity and the measured LPP concentrations. This result might be due to the cross-sectional design, and should be further investigated.

An add-on training program involving breathing exercises, cold exposure, and meditation attenuates inflammation and disease activity in axial spondyloarthritis - A proof of concept trial

Objectives

The primary objective of this trial was to assess safety and anti-inflammatory effects of an add-on training program involving breathing exercises, cold exposure, and meditation in patients with axial spondyloarthritis

Methods

This study was an open-label, randomised, one-way crossover clinical proof-of-concept trial. Twenty-four patients with moderately active axial spondyloarthritis(ASDAS >2.1) and hs-CRP ≥5mg/L were included and randomised to an intervention (n = 13) and control group (n = 11) group that additionally received the intervention after the control period. The intervention period lasted for 8 weeks. The primary endpoint was safety, secondary endpoints were change in hs-CRP, serum calprotectin levels and ESR over the 8-week period. Exploratory endpoints included disease activity measured by ASDAS-CRP and BASDAI, quality of life (SF-36, EQ-5D, EQ-5D VAS), and hospital anxiety and depression (HADS).

Results

We found no significant differences in adverse events between groups, with one serious adverse event occurring 8 weeks after end of the intervention and judged ‘unrelated’. During the 8-week intervention period, there was a significant decline of ESR from (median [interquartile range] to 16 [9–26.5] to 9 [5–23] mm/hr, p = 0.040, whereas no effect was found in the control group (from 14 [8.3–27.3] to 16 [5–37] m/hr, p = 0.406). ASDAS-CRP declined from 3.1 [2.5–3.6] to 2.3 [1.9–3.2] in the intervention group (p = 0.044). A similar trend was observed for serum calprotectin (p = 0.064 in the intervention group versus p = 0.182 in the control group), but not for hs-CRP.

Conclusions

This proof-of-concept study in axial spondyloarthritis met its primary endpoint with no safety signals during the intervention. There was a significant decrease in ESR levels and ASDAS-CRP upon the add-on training program in the intervention group. These findings warrant full-scale randomised controlled trials of this novel therapeutic approach in patients with inflammatory conditions.

Trial registration

ClinicalTrials.gov; NCT02744014

Emerging role of monocytes and their intracellular calcium pattern in spondyloarthritis

Spondyloarthritis (SpA) comprises multifactorial diseases characterized by a complex interplay between an inherited background and environmental factors that lead to immune response dysregulation and inflammation. Unlike for other rheumatic diseases, no specific biomarkers are available in clinical practice for diagnosing SpA. The aim of the present study was to search new potential biomarkers for SpA diagnosis by focusing on the innate immune response. An evaluation was made of the mRNA expression levels of inflammatory cytokines (TNF-α, IL-1β, TGF-β1, S100A8, S100A9) and matrix metalloproteinases (MMP3, MMP8, MMP9) in blood mononuclear cells of SpA patients (n = 64) with respect to controls (n = 100). In parallel, the pattern of intracellular calcium flows of blood monocytes was verified in order to ascertain whether any specific fingerprint characterizes innate immune cells in SpA patients. Inflammatory cytokines and MMPs expression levels were not correlated with SpA, while in this disease a reduced expression of the S100A8 and a decreased frequency of monocytes showing intracellular calcium flows were observed. In conclusion, no specific signs of systemic inflammation are detectable in SpA, but the disease affects the "on-off" mechanisms that regulate the concentration of intracellular calcium and calcium-related proteins. This potentially pave the way for the discovery of new biomarkers.

Routinely utilized in-house assays for infliximab, adalimumab and their anti-drug antibody levels

By monitoring serum concentrations of infliximab (IFX) and adalimumab (ADL) and levels of their antibodies in patients with inflammatory diseases, clinicians can adjust dose and increase safety and effectiveness of treatment. The aim was to develop and validate in-house enzyme-linked immunosorbent assays (ELISAs) for IFX and ADL, together with anti-IFX and anti-ADL ELISAs for routine detection and further analysis with acid dissociation of immune complexes. Furthermore, the objectives were to compare in-house assays with commercial ELISAs and reporter gene assays (RGAs) and to determine cross-reactivity between original Remicade®/Remsima™ and their antibodies. In-house ELISAs were validated (imprecision, accuracy among other criteria) and compared with commercial apDia ELISAs and RGAs. Correlation coefficients, intraclass correlation coefficients, agreement, and bias were calculated. All in-house ELISAs gave precise and repeatable results. The immune complexes between IFX and anti-IFX were found in 3% of samples, while complexes between ADL and anti-ADL were found in 14% of samples. Significant correlations were found between in-house and apDia ELISAs and RGA for IFX, ADL, anti-IFX, and anti-ADL results. Remicade®, Remsima™, and their antibodies could be accurately measured with either apDia or in-house IFX and anti-IFX ELISAs. Accurate and precise in-house ELISAs, highly comparable with commercial ELISAs and RGAs, were developed and validated for routine analysis of samples of patients treated with IFX (Remicade® or Remsima™) or ADL providing substantial cost benefit. Complex dissociation identified samples with anti-IFX-IFX (3%) and anti-ADL-ADL (14%) complexes indicating the benefit of adding acid dissociation to therapeutic drug monitoring of IFX and ADL.

ER stress abrogates the immunosuppressive effect of IL-10 on human macrophages through inhibition of STAT3 activation

Objective and design

To determine whether ER stress affects the inhibitory pathways of the human immune system, particularly the immunosuppressive effect of IL-10 on macrophages.

Material or subjects

In vitro stimulation of human monocyte-derived macrophages.

Treatment

Cells were stimulated with TLR ligands and IL-10, while ER stress was induced using thapsigargin or tunicamycin.

Methods

mRNA expression was determined using qPCR, while cytokine protein production was measured using ELISA. Protein expression of receptors and transcription factors was determined using flow cytometry. Student’s t test was used for statistics.

Results

While under normal conditions IL-10 potently suppresses pro-inflammatory cytokine production by LPS-stimulated macrophages, we demonstrate that ER stress counteracts the immunosuppressive effects of IL-10, leading to increased pro-inflammatory cytokine production. We identified that ER stress directly interferes with IL-10R signaling by reducing STAT3 phosphorylation on Tyr705, which thereby inhibits the expression of SOCS3. Moreover, we show that ER stress also inhibits STAT3 activation induced by other receptors such as IL-6R.

Conclusions

Combined, these data uncover a new general mechanism by which ER stress promotes inflammation. Considering its potential involvement in the pathogenesis of diseases such as Crohn’s disease and spondyloarthritis, targeting of this mechanism may provide new opportunities to counteract inflammation.

Targeting inflammatory pathways in axial spondyloarthritis

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

Genome-wide association study in Turkish and Iranian populations identify rare familial Mediterranean fever gene (MEFV) polymorphisms associated with ankylosing spondylitis

Ankylosing spondylitis (AS) is a highly heritable immune-mediated arthritis common in Turkish and Iranian populations. Familial Mediterranean Fever (FMF) is an autosomal recessive autoinflammatory disease most common in people of Mediterranean origin. MEFV, an FMF-associated gene, is also a candidate gene for AS. We aimed to identify AS susceptibility loci and also examine the association between MEFV and AS in Turkish and Iranian cohorts. We performed genome-wide association studies in 1001 Turkish AS patients and 1011 Turkish controls, and 479 Iranian AS patients and 830 Iranian controls. Serum IL-1β, IL-17 and IL-23 cytokine levels were quantified in Turkish samples. An association of major effect was observed with a novel rare coding variant in MEFV in the Turkish cohort (rs61752717, M694V, OR = 5.3, P = 7.63×10⁻¹²), Iranian cohort (OR = 2.9, P = 0.042), and combined dataset (OR = 5.1, P = 1.65×10⁻¹³). 99.6% of Turkish AS cases, and 96% of those carrying MEFV rs61752717 variants, did not have FMF. In Turkish subjects, the association of rs61752717 was particularly strong in HLA-B27-negative cases (OR = 7.8, P = 8.93×10⁻¹⁵), but also positive in HLA-B27-positive cases (OR = 4.3, P = 7.69×10⁻⁸). Serum IL-1β, IL-17 and IL-23 levels were higher in AS cases than controls. Among AS cases, serum IL-1β and IL-23 levels were increased in MEFV 694V carriers compared with non-carriers. Our data suggest that FMF and AS have overlapping aetiopathogenic mechanisms. Functionally important MEFV mutations, such as M694V, lead to dysregulated inflammasome function and excessive IL-1β function. As IL-1 inhibition is effective in FMF, AS cases carrying FMF-associated MEFV variants may benefit from such therapy.

Ankylosing spondylitis (AS) is a highly heritable immune-mediated arthritis. To identify new genetic associations with AS, we performed genome-wide association studies in Turkish and Iranian AS patients and controls. We identified a novel rare coding MEFV variant associated with AS. Rare polymorphisms of MEFV, which encodes the protein pyrin, are known to cause Familial Mediterranean Fever (FMF), a monogenic, autosomal recessive, autoinflammatory disease which can be complicated by arthritis. 99.6% of Turkish AS cases, and 96% of those carrying the MEFV variant, did not have FMF, and the association with AS remains excluding cases with FMF. In Turkish subjects, the MEFV variant association was particularly strong in HLA-B27-negative cases, but also positive in HLA-B27-positive cases. This represents the first rare variant association with AS, and has the highest odds ratio for AS of any non-MHC reported hitherto, indicating a major effect on disease pathogenesis. We assessed serum cytokine levels in the cohort, and found that IL-1β, IL-17 and IL-23 levels were higher in AS cases. Furthermore, among AS cases, IL-1β and IL-23 levels were increased in MEFV variant carriers compared with non-carriers. This study has therapeutic implications; as IL-1 inhibition is effective in FMF, AS cases carrying FMF-associated MEFV variants may benefit from such therapy.

Usefulness of complex bacteriological and serological analysis in patients with spondyloarthritis

Spondyloarthritis (SpA) is a group of associated chronic systemic inflammatory immune-mediated rheumatic diseases affecting axial and peripheral joints and entheses. The aim of the present study was to identify what parameters are useful to determine in order to better understand the correlation between the disease activity/severity and the microbiological results/immune status against intestinal and/or urogenital pathogens. Microorganisms known to trigger SpA, including Klebsiella spp., Yersinia spp., Salmonella spp., Campylobacter spp. and Chlamydia spp., were analyzed in various specimens (stool, urine, synovial fluid and serum) collected from 27 randomly selected SpA patients and 26 healthy controls using a combined direct and indirect approach relying on conventional culture technique and nucleic acid-based assays together with serological testing by ELISA. Although Escherichia coli derived from phylogroup A prevailed in the gut microflora of the patients and controls, differences were observed regarding the representatives of the other phylogroups with a higher prevalence of E.coli members of phylogenetic group B1 in the stool specimens of patients. Antibodies against the targeted species were detected in SpA patients and controls, and the serological profiles of the former were more diverse and complex. In conclusion, the detection of anti-bacterial antibodies combined with other specific laboratory investigations should be more extensively used to monitor SpA patients in association with their symptoms and in order to determine and administer more effective therapeutics.

Autoantibodies in Spondyloarthritis, Focusing on Anti-CD74 Antibodies

Spondyloarthritis (SpA) is an inflammatory rheumatic disease with diverse clinical presentation. The diagnosis of SpA remains a big challenge in daily clinical practice because of the limitation in specific biomarkers of SpA, more biomarkers are still needed for SpA diagnosis and disease activity monitoring. In the past, SpA was considered predominantly as auto-inflammatory disease vs. autoimmune disease. However, in recent years several researches demonstrated a broad autoantibody response in SpA patients. Study also indicated that mice lack of ZAP70 in T cell develop SpA featured inflammation. These studies indicated the autoimmune features of SpA and gave rise to the potential use of autoantibody in SpA management. In this article, we reviewed recent reports of autoantibodies associated with SpA patients, revealing the autoimmune features of SpA, suggesting the hypothesis that SpA was also an autoimmune disease, studies about the autoimmune features might provide more insights in the pathogenesis of SpA. In addition, as there are two opposite conclusions in the role of anti-CD74 autoantibody in the diagnosis of SpA, we also gave our own data on the diagnostic value of anti-CD74 in Chinese SpA patients. Though our data indicated that anti-CD74 might not be a good biomarker for SpA diagnosis in Asian people, CD74 was still a good molecule target in the research of SpA pathogenesis.

Role of Semaphorins in Immunopathologies and Rheumatic Diseases

Rheumatic diseases are disorders characterized by joint inflammation, in which other organs are also affected. There are more than two hundred rheumatic diseases, the most studied so far are rheumatoid arthritis, osteoarthritis, spondyloarthritis, systemic lupus erythematosus, and systemic sclerosis. The semaphorin family is a large group of proteins initially described as axon guidance molecules involved in nervous system development. Studies have demonstrated that semaphorins play a role in other processes such as the regulation of immunity, angiogenesis, bone remodeling, apoptosis, and cell migration and invasion. Moreover, semaphorins have been related to the pathogenesis of multiple sclerosis, asthma, Alzheimer, myocarditis, atherosclerosis, fibrotic diseases, osteopetrosis, and cancer. The aim of this review is to summarize current knowledge regarding the role of semaphorins in rheumatic diseases, and discuss their potential applications as therapeutic targets to treat these disorders.

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.

The antifibrotic drug pirfenidone inhibits spondyloarthritis fibroblast-like synoviocytes and osteoblasts in vitro

Background

The pathogenesis of spondyloarthritis (SpA) involves both inflammation and new bone formation in the spine. In line with this, the disease has been characterized as both inflammatory and fibrotic. The current treatment dampens inflammation while new bone formation can progress. Therefore, there is an unmet therapeutic need for the treatment of new bone formation in SpA. Fibrosis is mediated by myofibroblasts and new bone formation is the result of increased osteoblast mineralization and decreased osteoclast resorption. Here, we evaluate the potential effect of the newly approved anti-fibrotic agent pirfenidone (PFD) on fibrosis and new bone formation in cell culture models of SpA.

Methods

Fibroblast-like synoviocytes (FLSs) were isolated from SpA patients (n = 6) while the osteoblast cell line Saos-2 was purchased. The cells were cultured with PFD at 0.25 0.5, or 1.0 mg/ml. The proliferation of FLSs was analyzed with light microscopy and flow cytometry. The differentiation and activation of FLSs was assessed with flow cytometry, a membrane-based antibody array and enzyme-linked immunosorbant assays. The mineralization capacity of osteoblasts was studied with an assay measuring deposition of hydroxyapatite.

Results

PFD reduced the Ki67 expression 7.1-fold in untreated FLSs (p = 0.001) and 11.0-fold in FLSs stimulated with transforming growth factor beta (TGFβ), tumor necrosis factor alpha (TNFα), and interferon gamma (IFNγ) (p = 0.022). There were no statistically significant changes in membrane expression of alpha smooth muscle actin (αSMA), intercellular adhesion molecule 1 (ICAM-1), or human leukocyte antigen DR (HLA-DR). In supernatants from FLSs stimulated with TGFβ, TNFα, and IFNγ, PFD decreased the secretion of 3 of 12 proteins more than 2-fold in the membrane-based antibody array. The changes in secretion of monocyte chemoattractant protein 1 (MCP-1) and chitinase-3-like protein 1 (CHI3L1, YKL-40) were validated with ELISA. PFD decreased the secretion of both Dickkopf-related protein 1 (DKK1) (p = 0.006) and osteoprotegerin (OPG) (p = 0.02) by SpA FLSs stimulated with TGFβ, TNFα, and IFNγ. Finally, PFD inhibited the deposition of hydroxyapatite by osteoblasts in a dose-dependent manner (p = 0.0001).

Conclusions

PFD inhibited SpA FLS proliferation and function and osteoblast mineralization in vitro. This encourages studies of the in vivo effect of PFD in SpA.

Widespread pain in axial spondyloarthritis: clinical importance and gender differences

Background

There is a remarkable lack of detailed knowledge on pain areas in axial spondyloarthritis (axSpA), and their clinical relevance is largely unknown. Pain area may reflect local disease processes, but amplification of nervous system signalling may alter this relationship. Also, gender differences in pain area may exist in axSpA, possibly confounding disease activity outcomes. Therefore, we firstly detailed pain locations in axSpA and evaluated gender differences. Secondly, we explored the relationship of regional pain definitions with clinical outcomes. Finally, we explored the role of pain area in the assessment of disease activity.

Methods

Body charts informed on the presence of axial, peripheral articular and non-articular pain in 170 patients (108 men, 62 women) with axSpA. Multivariate Odds Ratios (ORs) were used to compare genders. General linear models were used to explore clinical differences in disease activity (Bath Ankylosing Spondylitis Disease Activity Index [BASDAI]), activity limitations (Bath Ankylosing Spondylitis Functional Index [BASFI]), fear of movement (Tampa Scale for Kinesiophobia 11-item version [TSK-11]), anxiety (Hospital Anxiety and Depression Scale subscale anxiety [HADS-A]) and depression (HADS subscale depression [HADS-D]) between four subgroups classified by widespread non-articular pain (WNAP+/−) and physician global assessment of disease activity (PGDA+/−) (p < .05). Principal Component Analysis (PCA) was performed to explore gender differences in the structure of disease activity.

Results

Axial thoracic pain was least prevalent (lumbar, 74.4%; cervical, 47.6%; cervicothoracic, 47.6%; thoracic, 32.4%), but it was about three times more likely in women (OR, 2.92; p = .009). Axial cervicothoracic junction pain spread more diffusely in women (OR, 2.48; p = .018). Women exhibited a two- to threefold increased likelihood of widespread axial (OR, 3.33; p = .007) and peripheral articular (OR, 2.34; p = .023) pain. A subgroup of WNAP+/PGDA− combined with low PGDA (27% of all patients) was associated with worse BASFI, BASDAI, HADS-A and HADS-D in men and worse TSK-11 and HADS-A in women (p < .05). Disease activity outcomes showed a two-factor structure in women but not in men.

Conclusions

In patients with axSpA, the location and spread of pain was different between genders and was related to worse clinical status. On the basis of pain area and PGDA, clinical subgroups exhibiting a remarkably distinct health status were identified. Outcome instruments such as BASDAI should acknowledge gender differences to ensure structural validity.

Electronic supplementary material

The online version of this article (10.1186/s13075-018-1626-8) contains supplementary material, which is available to authorized users.

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.

Antibody-based targeted delivery of interleukin-4 synergizes with dexamethasone for the reduction of inflammation in arthritis

Objectives

We have previously reported that F8-IL4, a fusion protein consisting of the F8 antibody specific to the alternatively-spliced extra domain A of fibronectin and of murine IL-4, cures mice with established arthritis, when used in combination with dexamethasone (DXM). The goal of this study was to assess whether other therapeutic agents, besides DXM, could induce cures in combination with F8-IL4 and to elucidate which leucocytes are most affected by the pharmacological treatment.

Methods

We performed therapy experiments in mice with CIA, using intravenous administrations of F8-IL4 in combination with DXM, MTX, murine cytotoxic T-lymphocyte-associated protein 4 fused to the fragment crystallizable portion of murine IgG2a, as well as mAbs to murine IL17A or the p40 subunit of murine IL12/IL23. Histology and immunohistochemistry for the identification of the various leucocytes were performed on the paws of mice euthanized at different therapy time points.

Results

Only the use of F8-IL4 in combination with DXM induced complete remissions, while all other combinations did not lead to cures. The light microscopical evaluation of paws with arthritis revealed a predominant infiltration of neutrophils, which substantially decreased 24 h after treatment with F8-IL4 and DXM.

Conclusion

The combination of F8-IL4 with DXM promotes a rapid anti-arthritic action by potently inhibiting neutrophil activity. A fully human analogue of F8-IL4 may find clinical utility for the treatment of neutrophil-driven chronic inflammatory conditions.

The Role of Autoantibodies in Bone Metabolism and Bone Loss

Many autoimmune diseases are associated with deranged bone metabolism. The resulting localized or systemic bone loss can compromise the quality of life of patients by causing local bone deformities or fragility fractures. There is emerging evidence that antibodies have a direct impact on key players of bone homeostasis, in particular osteoclasts. Clinical and pre-clinical studies provide insight into the function of autoantibodies related to Rheumatoid Arthritis (rheumatoid factor, anti-citrullinated protein antibodies, and anti-carbamylated protein antibodies) and their inflammation-independent interaction with bone cells. Furthermore, we summarize the current knowledge about neutralizing antibodies to the antiresorptive protein osteoprotegerin, which have been described in patients with Coeliac Disease, Rheumatoid Arthritis, and Spondyloarthritis.

Pathophysiology of axial spondyloarthritis: Consensus and controversies

BACKGROUND

Axial spondyloarthritis (axSpA) is a common inflammatory arthritis of the sacroiliac joints and the spine. The best-known and most studied form of axSpA is ankylosing spondylitis.

DESIGN

In this review, we provide a brief overview of the pathophysiology of axSpA. In addition, we performed a quantitative text analysis of reviews on the pathogenesis of axSpA published in the last 10 years to establish the current consensus in various fields of research into the pathogenesis of axSpA.

RESULTS

There appears to be broad consensus on genetic risk factors and the involvement of the immune system in the initiation phase of the disease although little consensus was found on which specific immune cells drive disease. Moreover, despite relatively little data available, alterations in the microbiome are commonly thought to be involved in disease. Abnormal bone formation is the most prominent pathogenic factor thought to be involved in disease progression.

CONCLUSION

So, although the pathophysiology of axSpA remains incompletely understood, the progress in recent years in several fields of research in axSpA including genetics, diagnosis, imaging and therapeutics, hold great promise for the future.

Proteinases and their receptors in inflammatory arthritis: an overview

Proteinases are enzymes with established roles in physiological and pathological processes such as digestion and the homeostasis, destruction and repair of tissues. Over the past few years, the hormone-like properties of circulating proteinases have become increasingly appreciated. Some proteolytic enzymes trigger cell signalling via proteinase-activated receptors, a family of G protein-coupled receptors that have been implicated in inflammation and pain in inflammatory arthritis. Proteinases can also regulate ion flux owing to the cross-sensitization of transient receptor potential cation channel subfamily V members 1 and 4, which are associated with mechanosensing and pain. In this Review, the idea that proteinases have the potential to orchestrate inflammatory signals by interacting with receptors on cells within the synovial microenvironment of an inflamed joint is revisited in three arthritic diseases: osteoarthritis, spondyloarthritis and rheumatoid arthritis. Unanswered questions are highlighted and the therapeutic potential of modulating this proteinase-receptor axis for the management of disease in patients with these types of arthritis is also discussed.