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.

IgG Subclasses Shape Cytokine Responses by Human Myeloid Immune Cells through Differential Metabolic Reprogramming.

IgG Abs are crucial for various immune functions, including neutralization, phagocytosis, and Ab-dependent cellular cytotoxicity. In this study, we identified another function of IgG by showing that IgG immune complexes elicit distinct cytokine profiles by human myeloid immune cells, which are dependent on FcγR activation by the different IgG subclasses. Using monoclonal IgG subclasses with identical Ag specificity, our data demonstrate that the production of Th17-inducing cytokines, such as TNF, IL-1ß, and IL-23, is particularly dependent on IgG2, whereas type I IFN responses are controlled by IgG3, and IgG1 is able to regulate both. In addition, we identified that subclass-specific cytokine production is orchestrated at the posttranscriptional level through distinct glycolytic reprogramming of human myeloid immune cells. Combined, these data identify that IgG subclasses provide pathogen- and cell type-specific immunity through differential metabolic reprogramming by FcγRs. These findings may be relevant for future design of Ab-related therapies in the context of infectious diseases, chronic inflammation, and cancer.

Dual Blockade of TNF and IL-17A Inhibits Inflammation and Structural Damage in a Rat Model of Spondyloarthritis.

The tumor necrosis factor (TNF) and IL-23/IL-17 axes are the main therapeutic targets in spondyloarthritis. Despite the clinical efficacy of blocking either pathway, monotherapy does not induce remission in all patients and its effect on new bone formation remains unclear. We aimed to study the effect of TNF and IL-17A dual inhibition on clinical disease and structural damage using the HLA-B27/human ß2-microglobulin transgenic rat model of SpA. Immunized rats were randomized according to arthritis severity, 1 week after arthritis incidence reached 50%, to be treated twice weekly for a period of 5 weeks with either a dual blockade therapy of an anti-TNF antibody and an anti-IL-17A antibody, a single therapy of either antibody, or PBS as vehicle control. Treatment-blinded observers assessed inflammation and structural damage clinically, histologically and by micro-CT imaging. Both single therapies as well as TNF and IL-17A dual blockade therapy reduced clinical spondylitis and peripheral arthritis effectively and similarly. Clinical improvement was confirmed for all treatments by a reduction of histological inflammation and pannus formation (p < 0.05) at the caudal spine. All treatments showed an improvement of structural changes at the axial and peripheral joints on micro-CT imaging, with a significant decrease for roughness (p < 0.05), which reflects both erosion and new bone formation, at the level of the caudal spine. The effect of dual blockade therapy on new bone formation was more prominent at the axial than the peripheral level. Collectively, our study showed that dual blockade therapy significantly reduces inflammation and structural changes, including new bone formation. However, we could not confirm a more pronounced effect of dual inhibition compared to single inhibition.

C-Reactive Protein Promotes Inflammation through FcγR-Induced Glycolytic Reprogramming of Human Macrophages.

C-reactive protein (CRP) is an acute-phase protein produced in high quantities by the liver in response to infection and during chronic inflammatory disorders. Although CRP is known to facilitate the clearance of cell debris and bacteria by phagocytic cells, the role of CRP in additional immunological functions is less clear. This study shows that complexed CRP (phosphocholine [PC]:CRP) (formed by binding of CRP to PC moieties), but not soluble CRP, synergized with specific TLRs to posttranscriptionally amplify TNF, IL-1ß, and IL-23 production by human inflammatory macrophages. We identified FcγRI and IIa as the main receptors responsible for initiating PC:CRP-induced inflammation. In addition, we identified the underlying mechanism, which depended on signaling through kinases Syk, PI3K, and AKT2, as well as glycolytic reprogramming. These data indicate that in humans, CRP is not only a marker but also a driver of inflammation by human macrophages. Therefore, although providing host defense against bacteria, PC:CRP-induced inflammation may also exacerbate pathology in the context of disorders such as atherosclerosis.

C-Reactive Protein Controls IL-23 Production by Human Monocytes.

C-reactive protein (CRP) is an acute-phase protein in humans that is produced in high quantities by the liver upon infection and under inflammatory conditions. Although CRP is commonly used as a marker of inflammation, CRP can also directly contribute to inflammation by eliciting pro-inflammatory cytokine production by immune cells. Since CRP is highly elevated in serum under inflammatory conditions, we have studied the CRP-induced cytokine profile of human monocytes, one of the main innate immune cell populations in blood. We identified that CRP is relatively unique in its capacity to induce production of the pro-inflammatory cytokine IL-23, which was in stark contrast to a wide panel of pattern recognition receptor (PRR) ligands. We show that CRP-induced IL-23 production was mediated at the level of gene transcription, since CRP particularly promoted gene transcription of IL23A (encoding IL-23p19) instead of IL12A (encoding IL-12p35), while PRR ligands induce the opposite response. Interestingly, when CRP stimulation was combined with PRR ligand stimulation, as for example, occurs in the context of sepsis, IL-23 production by monocytes was strongly reduced. Combined, these data identify CRP as a unique individual ligand to induce IL-23 production by monocytes, which may contribute to shaping systemic immune responses under inflammatory conditions.

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.

The inflammatory function of human IgA.

The prevailing concept regarding the immunological function of immunoglobulin A (IgA) is that it binds to and neutralizes pathogens to prevent infection at mucosal sites of the body. However, recently, it has become clear that in humans IgA is also able to actively contribute to the initiation of inflammation, both at mucosal and non-mucosal sites. This additional function of IgA is initiated by the formation of immune complexes, which trigger Fc alpha Receptor I (FcαRI) to synergize with various other receptors to amplify inflammatory responses. Recent findings have demonstrated that co-stimulation of FcαRI strongly affects pro-inflammatory cytokine production by various myeloid cells, including different dendritic cell subsets, macrophages, monocytes, and Kupffer cells. FcαRI-induced inflammation plays a crucial role in orchestrating human host defense against pathogens, as well as the generation of tissue-specific immunity. In addition, FcαRI-induced inflammation is suggested to be involved in the pathogenesis of various chronic inflammatory disorders, including inflammatory bowel disease, celiac disease, and rheumatoid arthritis. Combined, IgA-induced inflammation may be used to either promote inflammatory responses, e.g. in the context of cancer therapy, but may also provide new therapeutic targets to counteract chronic inflammation in the context of various chronic inflammatory disorders.

Correction: HLA-C*07 in axial spondyloarthritis: data from the German Spondyloarthritis Inception Cohort and the Spondyloarthritis Caught Early cohort.

The original version of this Article contained an error in the spelling of the author Denis Poddubnyy, which was incorrectly given as Denis Podubbnyy. This has now been corrected in both the PDF and HTML versions of the Article.

HLA-C*07 in axial spondyloarthritis: data from the German Spondyloarthritis Inception Cohort and the Spondyloarthritis Caught Early cohort.

We aimed to assess the mRNA expression of MHC class 1-related molecules in ankylosing spondylitis (AS) patients vs healthy controls (HCs) and, subsequently, if the absence of HLA-C*07 is associated with genetic susceptibility to axial spondyloarthritis (axSpA). HLA-C*07 was assessed in (a) an exploratory cohort of 24 AS patients vs 40 HCs, (b) a confirmatory cohort of 113 AS patients and 83 non-radiographic axSpA patients from the GErman SPondyloarthritis Inception Cohort (GESPIC) vs 134,528 German potential stem cell donors, and (c) an early back pain cohort with 94 early axSpA patients vs 216 chronic back pain (CBP) patients from the SPondyloArthritis Caught Early (SPACE) cohort. In the exploratory cohort, 79% of the AS patients were HLA-C*07 negative compared to 35% of the HCs (p < 0.001). This difference was confirmed in GESPIC with 73% of AS patients being HLA-C*07 negative compared to 50% of the controls (p < 0.0001); 59% of the nr-axSpA patients were HLA-C*07 negative. In the SPACE cohort, 70% of the axSpA patients were HLA-C*07 negative compared to 44% of CBP patients (p < 0.0001); the association between HLA-C*07 negativity and a diagnosis of axSpA was independent from HLA-B*27. In conclusion, the absence of HLA-C*07 is associated with genetic susceptibility to axSpA.

Fc gamma receptor IIa suppresses type I and III interferon production by human myeloid immune cells.

Type I and type III interferons (IFNs) are fundamental for antiviral immunity, but prolonged expression is also detrimental to the host. Therefore, upon viral infection high levels of type I and III IFNs are followed by a strong and rapid decline. However, the mechanisms responsible for this suppression are still largely unknown. Here, we show that IgG opsonization of model viruses influenza and respiratory syncytial virus (RSV) strongly and selectively suppressed type I and III IFN production by various human antigen-presenting cells. This suppression was induced by selective inhibition of TLR, RIG-I-like receptor, and STING-dependent type I and III IFN gene transcription. Surprisingly, type I and III IFN suppression was mediated by Syk and PI3K independent inhibitory signaling via FcγRIIa, thereby identifying a novel non-canonical FcγRIIa pathway in myeloid cells. Together, these results indicate that IgG opsonization of viruses functions as a novel negative feedback mechanism in humans, which may play a role in the selective suppression of type I and III IFN responses during the late-phase of viral infections. In addition, activation of this pathway may be used as a tool to limit type I IFN-associated pathology.

BOB.1 controls memory B-cell fate in the germinal center reaction.

During T cell-dependent (TD) germinal center (GC) responses, naïve B cells are instructed to differentiate towards GC B cells (GCBC), high-affinity long-lived plasma cells (LLPC) or memory B cells (Bmem). Alterations in the B cell-fate choice could contribute to immune dysregulation leading to the loss of self-tolerance and the initiation of autoimmune disease. Here we show that mRNA levels of the transcription regulator BOB.1 are increased in the lymph node compartment of patients with rheumatoid arthritis (RA), a prototypical autoimmune disease caused by the loss of immunological tolerance. Investigating to what extent levels of BOB.1 impact B cells during TD immune responses we found that BOB.1 has a crucial role in determining the B cell-fate decision. High BOB.1 levels promote the generation of cells with phenotypic and functional characteristics of Bmem. Mechanistically, overexpression of BOB.1 drives ABF1 and suppresses BCL6, favouring Bmem over LLPC or recycling GCBC. Low levels of BOB.1 are sufficient for LLPC but not for Bmem differentiation. Our findings demonstrate a novel role for BOB.1 in B cells during TD GC responses and suggest that its dysregulation may contribute to the pathogenesis of RA by disturbing the B cell-fate determination.

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.

Serum IgA Immune Complexes Promote Proinflammatory Cytokine Production by Human Macrophages, Monocytes, and Kupffer Cells through FcαRI-TLR Cross-Talk.

IgA is predominantly recognized to play an important role in host defense at mucosal sites, where it prevents invasion of pathogens by neutralization. Although it has recently become clear that IgA also mediates other immunological processes, little remains known about the potential of IgA to actively contribute to induction of inflammation, particularly in nonmucosal organs and tissues. In this article, we provide evidence that immune complex formation of serum IgA plays an important role in orchestration of inflammation in response to pathogens at various nonmucosal sites by eliciting proinflammatory cytokines by human macrophages, monocytes, and Kupffer cells. We show that opsonization of bacteria with serum IgA induced cross-talk between FcαRI and different TLRs, leading to cell type-specific amplification of proinflammatory cytokines, such as TNF-α, IL-1ß, IL-6, and IL-23. Furthermore, we demonstrate that the increased protein production of cytokines was regulated at the level of gene transcription, which was dependent on activation of kinases Syk and PI3K. Taken together, these data demonstrate that the immunological function of IgA is substantially more extensive than previously considered and suggest that serum IgA-induced inflammation plays an important role in orchestrating host defense by different cell types in nonmucosal tissues, including the liver, skin, and peripheral blood.

New treatment paradigms in spondyloarthritis.

PURPOSE OF REVIEW: The review presents the recent rapid expansion of therapeutical options in spondyloarthritis. Additionally, it focuses on the importance of additional questions raised by the growing therapeutic possibilities related to the optimal use of these drugs. RECENT FINDINGS: The emergence of new treatment options opens new avenues and opportunities for treating patients with nonresponse, contraindications, or intolerance for classic drugs. However, it becomes more relevant than ever to define not only drugs and treatment options but also treatment strategies. We address current literature and remaining questions on strategies such as early intervention, combination treatment, personalized medicine, and treat-to-target. SUMMARY: Not only the treatment as such, but also the treatment strategy is crucial to reveal the full therapeutic potential and benefit for patients. Whereas cautious but crucial steps have been taken in the last years to explore these aspects, related to timing and sequence of treatment (including combination treatments), stratified medicine approaches, and treat-to-target strategies, it is now time for full-scale investment in prospective strategy trials.

Class 3 semaphorins modulate the invasive capacity of rheumatoid arthritis fibroblast-like synoviocytes.

Objective: Class 3 semaphorins regulate diverse cellular processes relevant to the pathology of RA, including immune modulation, angiogenesis, apoptosis and invasive cell migration. Therefore, we analysed the potential role of class 3 semaphorins in the pathology of RA. Methods: Protein and mRNA expression in RA synovial tissue, SF and fibroblast-like synoviocytes (FLS) were determined by immunoblotting and quantitative PCR (qPCR). RA FLS migration and invasion were determined using wound closure and transwell invasion assays, respectively. PlexinA1, neuropilin-1 and neuropilin-2 expression was knocked down using small interfering RNA (siRNA). Activation of FLS intracellular signalling pathways was assessed by immunoblotting. Results: mRNA expression of semaphorins (Sema)3B, Sema3C, Sema3F and Sema3G was significantly lower in the synovial tissue of early arthritis patients at baseline who developed persistent disease compared with patients with self-limiting disease after 2 years follow-up. Sema3B and Sema3F expression was significantly lower in arthritis patients fulfilling classification criteria for RA compared with those who did not. FLS expression of Sema3A was induced after stimulation with TNF, IL-1ß or lipopolysaccharides (LPS), while Sema3B and Sema3F expression was downregulated. Exogenously applied Sema3A induced the migration and invasive capacity of FLS, while stimulation with Sema3B or Sema3F reduced spontaneous FLS migration, and platelet-derived growth factor induced cell invasion, effects associated with differential regulation of MMP expression and mediated by the PlexinA1 and neuropilin-1 and -2 receptors. Conclusion: Our data suggest that modulation of class 3 semaphorin signaling could be a novel therapeutic strategy for modulating the invasive behaviour of FLS in RA.

Residual disease activity in psoriatic arthritis: discordance between the rheumatologist's opinion and minimal disease activity measurement.

Objective: To assess how many PsA patients with an acceptable disease state according to the treating rheumatologist have quiescent disease defined as minimal disease activity (MDA). Methods: This cross-sectional study included 250 PsA patients. To assess current clinical practice as closely as possible, acceptable disease state was not determined by predefined activity measures, but instead was defined by asking rheumatologists to refer those patients whom they considered sufficiently treated. Patients were evaluated for current disease activity including clinical assessments and patient reported outcomes (PROs). Results: One-third (88/250) of the patients with acceptable disease state according to the rheumatologist did not fulfil MDA (MDA-). The presence of tender joints and patient pain and global disease activity scores most frequently contributed to not fulfilling MDA (not achieved in 83, 82 and 80%, respectively). However, also objective signs of disease activity were higher in the MDA- than MDA+ patient group: a swollen joint count >1 occurred in 35% vs 7% (P < 0.001), enthesitis >1 in 14% vs 3% (P = 0.002) and Psoriasis Area and Severity Index >1 in 43% vs 26% (P = 0.002). Residual disease was more frequent in females, elder patients and those with a raised BMI, independent of the treatment schedule, and negatively influenced PROs of function and quality of life. Conclusion: One-third of the PsA patients with acceptable disease state according to the treating rheumatologist did not fulfil the MDA criteria and had residual disease activity on both subjective and objective disease activity measurements. As residual disease activity was associated with worse PROs, future strategy trials should evaluate if treatment adjustments are beneficial for this patient group.

Bone formation in ankylosing spondylitis during anti-tumour necrosis factor therapy imaged by 18F-fluoride positron emission tomography.

Objectives: Excessive bone formation is an important hallmark of AS. Recently it has been demonstrated that axial bony lesions in AS patients can be visualized using 18F-fluoride PET-CT. The aim of this study was to assess whether 18F-fluoride uptake in clinically active AS patients is related to focal bone formation in spine biopsies and is sensitive to change during anti-TNF treatment. Methods: Twelve anti-TNF-naïve AS patients [female 7/12; age 39 years (SD 11); BASDAI 5.5 ± 1.1] were included. 18 F-fluoride PET-CT scans were performed at baseline and in two patients, biopsies were obtained from PET-positive and PET-negative spine lesions. The remaining 10 patients underwent a second 18F-fluoride PET-CT scan after 12 weeks of anti-TNF treatment. PET scans were scored visually by two blinded expert readers. In addition, 18F-fluoride uptake was quantified using the standardized uptake value corrected for individual integrated whole blood activity concentration (SUVAUC). Clinical response to anti-TNF was defined according to a ⩾ 20% improvement in Assessment of SpondyloArthritis international Society criteria at 24 weeks. Results: At baseline, all patients showed at least one axial PET-positive lesion. Histological analysis of PET-positive lesions in the spine confirmed local osteoid formation. PET-positive lesions were found in the costovertebral joints (43%), facet joints (23%), bridging syndesmophytes (20%) and non-bridging vertebral lesions (14%) and in SI joints (75%). After 12 weeks of anti-TNF treatment, 18F-fluoride uptake in clinical responders decreased significantly in the costovertebral (mean SUVAUC -1.0; P < 0.001) and SI joints (mean SUVAUC -1.2; P = 0.03) in contrast to non-responders. Conclusions: 18F-fluoride PET-CT identified bone formation, confirmed by histology, in the spine and SI joints of AS patients and demonstrated alterations in bone formation during anti-TNF treatment.

Histone deacetylase 3 regulates the inflammatory gene expression programme of rheumatoid arthritis fibroblast-like synoviocytes.

OBJECTIVES: Non-selective histone deacetylase (HDAC) inhibitors (HDACi) have demonstrated anti-inflammatory properties in both in vitro and in vivo models of rheumatoid arthritis (RA). Here, we investigated the potential contribution of specific class I and class IIb HDACs to inflammatory gene expression in RA fibroblast-like synoviocytes (FLS). METHODS: RA FLS were incubated with pan-HDACi (ITF2357, givinostat) or selective HDAC1/2i, HDAC3/6i, HDAC6i and HDAC8i. Alternatively, FLS were transfected with HDAC3, HDAC6 or interferon (IFN)-α/ß receptor alpha chain (IFNAR1) siRNA. mRNA expression of interleukin (IL)-1ß-inducible genes was measured by quantitative PCR (qPCR) array and signalling pathway activation by immunoblotting and DNA-binding assays. RESULTS: HDAC3/6i, but not HDAC1/2i and HDAC8i, significantly suppressed the majority of IL-1ß-inducible genes targeted by pan-HDACi in RA FLS. Silencing of HDAC3 expression reproduced the effects of HDAC3/6i on gene regulation, contrary to HDAC6-specific inhibition and HDAC6 silencing. Screening of the candidate signal transducers and activators of transcription (STAT)1 transcription factor revealed that HDAC3/6i abrogated STAT1 Tyr701 phosphorylation and DNA binding, but did not affect STAT1 acetylation. HDAC3 activity was required for type I IFN production and subsequent STAT1 activation in FLS. Suppression of type I IFN release by HDAC3/6i resulted in reduced expression of a subset of IFN-dependent genes, including the chemokines CXCL9 and CXCL11. CONCLUSIONS: Inhibition of HDAC3 in RA FLS largely recapitulates the effects of pan-HDACi in suppressing inflammatory gene expression, including type I IFN production in RA FLS. Our results identify HDAC3 as a potential therapeutic target in the treatment of RA and type I IFN-driven autoimmune diseases.

Killer immunoglobulin receptor genes in spondyloarthritis.

PURPOSE OF REVIEW: We focus on the role of killer immunoglobulin receptor (KIR) interactions with the human leukocyte antigens (HLA)-B27 ligand and the potential contribution of KIR-expressing natural killer and T cells in spondyloarthritis, more specifically in ankylosing spondylitis (AS). RECENT FINDINGS: In AS strong epidemiological evidence of significant genetic associations with the major histocompatibility complex was convincingly identified. HLA-B27-positive first-degree relatives of AS cases are 5-16 times more likely to develop disease than HLA-B27-positive carriers in the general community. The GWAS era has enabled rapid progress in identifying non-major histocompatibility complex associations of AS. SUMMARY: These findings show a number of important pathways in AS pathogenesis, including the IL-23-IL-17 pathway, aminopeptidases, peptide presentation, and KIR-HLA-B27 interactions. Studies using genetic markers, including KIRs may be used for a risk assessment about whom may benefit most from the various treatment protocols in spondyloarthritis, now that alternative therapeutic options have become feasible.

A psychometric analysis of outcome measures in peripheral spondyloarthritis.

OBJECTIVES: To assess the discriminatory capacity of various outcome measures and response criteria in patients with peripheral spondyloarthritis (pSpA). METHODS: Data originated from two randomised controlled trials, ABILITY-2 and Tnf Inhibition in PEripheral SpondyloArthritis (TIPES). Continuous outcome measures included patient's global assessment (PGA)/physician's global assessment of disease (PhGA), C-reactive protein (CRP), tender joint counts (TJC)/swollen joint counts (SJC), Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), and the Ankylosing Spondylitis Disease Activity Score (ASDAS). Dichotomous response criteria included Peripheral SpondyloArthritis Response Criteria (PSpARC), American College of Rheumatology (ACR), ASDAS and BASDAI response criteria. The capacity to discriminate between adalimumab and placebo groups was assessed by standardised mean differences (SMD) for continuous variables, and Pearson's χ(2) for dichotomous response criteria. RESULTS: Within each trial, the composite indices for axial SpA assessment, ASDAS-CRP (SMD: -0.63 and -0.89 in ABILITY-2 and the TIPES trial, respectively) and BASDAI (SMD: -0.50 and -0.73), and the single-item measures PGA (SMD: -0.47 and -1.12) and PhGA (SMD: -0.64 and -0.87) performed better than other single-item measures, such as CRP (SMD: -0.18 and -0.53), SJC or TJC. In general, the PSpARC and ACR response criteria discriminated better than ASDAS and BASDAI response criteria. CONCLUSIONS: The axial SpA-specific ASDAS-CRP and BASDAI, but also PGA and PhGA, demonstrated good discriminatory ability in patients with pSpA. The pSpA-specific pSpARC response criteria and the rheumatoid arthritis-specific ACR response criteria also discriminated well. To fully capture typical pSpA manifestations, it may be worth developing new pSpA-specific indices with better performance and face validity. TRIAL REGISTRATION NUMBERS: ABILITY-2: NCT01064856; TIPES: EUDRACT 2008-006885-27.