Determinants of work and social participation in patients with psoriatic arthritis in the Netherlands: an observational study.

BACKGROUND: Psoriatic arthritis can cause pain, disability, and permanent joint damage. This can lead to impairments in work and social participation. Little is known about the extent of these impairments in routine practice. With this study, we aim to examine the extent of work and activity impairment in (subgroups of) Dutch patients with psoriatic arthritis (PsA), and to examine determinants associated with this impairment. METHODS: This is an observational study using data collected from the electronic health records of PsA patients treated at the Sint Maartenskliniek, the Netherlands. Data about work and activity impairment were collected via the Work Productivity and Activity Impairment questionnaire. To compare our PsA-cohort with the Dutch general population, we used age- and sex-matched data derived from the Central Bureau of Statistics. Regression analyses were performed to examine determinants of work and activity impairment. RESULTS: In total, 246 patients were included, of which 126 (51.2%) were female. Mean age (S.D.) was 55.7 (13.2) years. Compared with the Dutch general population, work for pay (WFP) was significantly lower in PsA (52.9% versus 62.6%, P < 0.001). In PsA, younger age and better physical function were associated with WFP status (P < 0.05). Higher disease activity, worse physical function, and worse mental health-related quality of life were associated with both more work and activity impairment (P < 0.05). Furthermore, reaching low disease activity status (LDA) according to Psoriatic ArthritiS Disease Activity Score (PASDAS; ≤ 3.2) was associated with less work and activity impairment than reaching LDA according to DAS28-CRP (≤ 2.9) (P < 0.05). CONCLUSIONS: In PsA patients, worse physical function was associated with a lower likelihood of having WFP, and higher work and activity impairment. PASDAS LDA as a goal for treat to target, compared to DAS28-CRP, appears to favour the reduction of work and activity impairment.

Defining the minimal important change (MIC) and meaningful change value (MCV) for the Psoriatic Arthritis Disease Activity Score (PASDAS) in a routine practice cohort of patients with psoriatic arthritis.

OBJECTIVE: The aim of the study was to determine the Minimal Important Change (MIC) values and Meaningful Change (MCV) values for the Psoriatic Arthritis Disease Activity Score (PASDAS) and the Standard Error of Measurement (s.e.m.) of the PASDAS. METHODS: The routine practice data for 544 patients with PsA was available for analysis. An anchor-based method using linear regression analyses was used to determine the MICs and MCVs for the PASDAS. With this anchor-based method, we compared changes in the PASDAS score with an external reference (anchor). The anchor question inquired whether the patient's well-being had changed since their previous visit. It consisted of a 7-point Likert scale (range: very much improved to very much deteriorated). Interperiod correlation matrix analysis was performed to determine the s.e.m. RESULTS: The overall MIC and MCV for the PASDAS were 0.67 (95% CI: 0.55, 0.79) and 1.34 (95% CI: 1.21, 1.46), respectively. Results for improvement and deterioration were 0.65 (95% CI: 0.46, 0.83) and 0.71 (95% CI: 0.49, 0.93) for the MIC, respectively, and 1.29 (95% CI: 1.11, 1.48) and 1.42 (95% CI: 1.19, 1.64) for the MCV, respectively. The s.e.m. was determined at 0.81. CONCLUSION: The MIC for the PASDAS is a tool for physicians treating patients with PsA enabling them to give context to the patient's perspective of disease activity, while the MCV might aid the use of the PASDAS in PsA clinical trials.

Being overweight is associated with not reaching low disease activity in women but not men with psoriatic arthritis.

OBJECTIVE: To assess sex differences in disease activity parameters and health-related quality of life in PsA, and to assess whether determinants associated with not reaching treatment target differed between men and women. METHODS: Routine practice data of 855 PsA patients, who were all tightly monitored and treated, was used. Sex differences including, but not limited to, PsA Disease Activity Score (PASDAS), skin/nail disease, SF-12 PCS/MCS, and inflammatory back pain (IBP) were assessed. Multivariate analyses were used to examine determinants associated with not reaching treatment target (PASDAS ≤ 3.2) in men and women. RESULTS: Women had worse scores for-among others-swollen and tender joints, CRP, enthesitis and function (all P < 0.001). Higher PASDAS scores were found for women [3.5 (1.5)] than men [2.7 (1.5), P < 0.001]. Likewise, women were more often not at PASDAS treatment target (OR = 2.03, P < 0.001). No difference in current medication use was found. Nail disease, IBP, number of DMARDs used (past and current), and BMI were associated with not reaching treatment target in the overall sample. For women, but not men, BMI was associated with not reaching PASDAS low disease activity (LDA) (OR between 2.41 and 3.43, P < 0.001). CONCLUSIONS: Women with PsA in a tightly monitored and treated setting have more severe disease than men. This is demonstrated by worse scores for women in both subjective and objective disease activity measures, in addition to women less often reaching the treatment target. Notably, being overweight is associated with higher disease activity in women, but not men.

Comparing methotrexate monotherapy with methotrexate plus leflunomide combination therapy in psoriatic arthritis (COMPLETE-PsA): a double-blind, placebo-controlled, randomised, trial.

BACKGROUND: Conventional synthetic disease-modifying anti-rheumatic drugs (DMARDs) are the preferred first-line treatment in patients with psoriatic arthritis, although there is a paucity of evidence for the efficacy of conventional synthetic DMARDs and especially their combination. We aimed to investigate whether a combination of methotrexate plus leflunomide is superior to methotrexate monotherapy at improving disease activity in patients with psoriatic arthritis. METHODS: This single centre, investigator-initiated, double-blind, randomised, placebo-controlled trial was conducted at Sint Maartenskliniek in the Netherlands (locations included Boxmeer, Geldrop, Woerden, and Nijmegen). Patients aged 16 years or older with a clinical diagnosis of psoriatic arthritis and active disease (defined as two or more swollen joints; dactylitis counting as one swollen joint) were included. Patients were randomly allocated (1:1) and stratified by high disease activity (psoriatic arthritis disease activity score [PASDAS] ≥5·4) to either methotrexate plus leflunomide (combination therapy) or methotrexate plus placebo (monotherapy), using computer-generated stratified variable block randomisation. In both groups, patients received oral methotrexate 15 mg per week for the first 4 weeks and 25 mg per week thereafter combined with two leflunomide 10 mg tablets once per day or two placebo tablets. During the study period, the patients, nurses, researchers, and treating physicians were all masked to treatment allocation. The primary outcome was the difference in mean PASDAS at week 16, adjusted for baseline PASDAS, between the combination and monotherapy groups, assessed in the intention-to-treat population. This trial was registered with the Netherlands Trial Register (NL7404) on Dec 3, 2018. FINDINGS: Between Feb 19, 2019, and March 11, 2021, 82 patients were screened for eligibility. Four patients were ineligible and 78 were enrolled and randomly assigned to either methotrexate plus leflunomide (n=39) or methotrexate plus placebo (n=39). 50 (64%) of 78 patients were male, 28 (36%) were female, and the median age of patients was 55·0 years (IQR 42·0-64·0). Methotrexate plus leflunomide combination therapy was superior to methotrexate monotherapy at week 16 (PASDAS 3·1 [SD 1·4] vs 3·7 [SD 1·3]; treatment difference -0·6, 90% CI -1·0 to -0·1; p=0·025). There were no study deaths. The most frequently occurring adverse events were nausea or vomiting (17 [44%] of 39 patients in the methotrexate plus leflunomide group vs 11 [28%] of 39 in the methotrexate plus placebo group), tiredness (9 [23%] vs 13 [33%]) and elevated alanine aminotransferase (12 [31%] vs 7 [18%]. Generally, the incidence of mostly mild adverse events was higher in the methotrexate plus leflunomide group than in the methotrexate plus placebo group. INTERPRETATION: Methotrexate plus leflunomide combination therapy results in greater improvement in disease activity according to PASDAS in patients with psoriatic arthritis. However, methotrexate plus leflunomide combination therapy is less well tolerated than methotrexate monotherapy. FUNDING: Regional Junior Researcher Grant from the Sint Maartenskliniek.

Discovery of Arthritis in Psoriasis Patients for Early Rheumatological Referral (DAPPER): Protocol for a Longitudinal Observational Study.

BACKGROUND: One in three patients with psoriasis will develop psoriatic arthritis (PsA). If left untreated, this can lead to pain, impaired function, and irreversible joint damage. Timely recognition and referral to a rheumatologist are therefore key. However, current methods used to screen patients with psoriasis for those who might benefit from referral to a rheumatologist are not performing well enough. OBJECTIVE: The Discovery of Arthritis in Psoriasis Patients for Early Rheumatological Referral (DAPPER) study is designed to determine the prevalence of PsA in a psoriasis population and to find parameters that can be used to develop a new or enhance an existing instrument for a rheumatological referral. METHODS: DAPPER is a longitudinal observational study with a 1-year follow-up. Patients with psoriasis (N=300) who are treated at an outpatient dermatological clinic will be screened extensively for signs and symptoms of PsA by a trained rheumatologist. If there is clinical suspicion of PsA and the patient is not yet treated by a rheumatologist, referral to the Department of Rheumatology will follow for confirmation of the diagnosis and further care. After 1 year, data on changes in quality of life and PsA and psoriasis disease activity will be collected from the referred patients. The screening visit will be used to gather demographical and medical data, which can later be used to develop the aforementioned screening instrument. RESULTS: Inclusion started in June 2019 and finished in June 2021. Follow-up with newly discovered patients with PsA is ongoing. CONCLUSIONS: The DAPPER study is specifically designed to improve the detection of existing PsA in a dermatologic outpatient setting. Although internal validity will be tested, external validity will have to be checked using a second validation cohort. To predict the development of PsA in the future, longitudinal/prospective data collection is required and will be performed in a follow-up study (DAPPER-i). TRIAL REGISTRATION: Dutch Trial Register NTR7604; https://www.trialregister.nl/trial/7397. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/31647.

Blood-Based Immune Profiling Combined with Machine Learning Discriminates Psoriatic Arthritis from Psoriasis Patients.

Psoriasis (Pso) is a chronic inflammatory skin disease, and up to 30% of Pso patients develop psoriatic arthritis (PsA), which can lead to irreversible joint damage. Early detection of PsA in Pso patients is crucial for timely treatment but difficult for dermatologists to implement. We, therefore, aimed to find disease-specific immune profiles, discriminating Pso from PsA patients, possibly facilitating the correct identification of Pso patients in need of referral to a rheumatology clinic. The phenotypes of peripheral blood immune cells of consecutive Pso and PsA patients were analyzed, and disease-specific immune profiles were identified via a machine learning approach. This approach resulted in a random forest classification model capable of distinguishing PsA from Pso (mean AUC = 0.95). Key PsA-classifying cell subsets selected included increased proportions of differentiated CD4+CD196+CD183-CD194+ and CD4+CD196-CD183-CD194+ T-cells and reduced proportions of CD196+ and CD197+ monocytes, memory CD4+ and CD8+ T-cell subsets and CD4+ regulatory T-cells. Within PsA, joint scores showed an association with memory CD8+CD45RA-CD197- effector T-cells and CD197+ monocytes. To conclude, through the integration of in-depth flow cytometry and machine learning, we identified an immune cell profile discriminating PsA from Pso. This immune profile may aid in timely diagnosing PsA in Pso.

Clinical, laboratory, and genetic markers for the development or presence of psoriatic arthritis in psoriasis patients: a systematic review.

Twenty to thirty percent of psoriasis (Pso) patients will develop psoriatic arthritis (PsA). Detection of Pso patients that are (at risk for) developing PsA is essential to prevent structural damage. We conducted a systematic search of five bibliographic databases, up to May 2020. We searched for studies assessing markers (clinical, laboratory, genetic) associated with the development or presence of PsA in Pso patients. Study selection and quality assessment of the included studies was performed, followed by a qualitative best evidence synthesis to determine the level of evidence for a marker and its association with concomitant/developing PsA in Pso. Overall, 259 possible markers were identified in 119 studies that met the inclusion criteria. Laboratory markers related to inflammation and bone metabolism reached a strong level of evidence for the association (not prediction) of PsA in Pso. Only CXCL10 showed strong evidence for a positive predictive value for PsA in Pso. The importance of timely detecting PsA in a Pso population, and finding more (bio)markers contributing to early detection, remains high.

Measuring disease activity in psoriatic arthritis: PASDAS implementation in a tightly monitored cohort reveals residual disease burden.

OBJECTIVES: We aimed to investigate the disease activity and overall disease burden of (subgroups of) patients with PsA using the Psoriatic Arthritis Disease Activity Score (PASDAS) in an already tightly monitored cohort. METHODS: This is a cross-sectional study evaluating data from the first visit of 855 PsA patients after implementation of the PASDAS in our tightly monitored cohort [e.g. DAS 28 (DAS28) was provided as an anchor]. Differences in clinical outcomes between subgroups of patients using established cut-offs for disease activity status [i.e. very low (VLDA), low (LDA), moderate (MDA), and high disease activity (HDA)] were examined. RESULTS: Based on the PASDAS, 53.1% of patients were in VLDA/LDA. 29.5% of patients had ≥1 swollen joint, 20.6% had ≥1 enthesitis index point and 3.0% had active dactylitis. Based on DAS28, 77.5% of the patients were in VLDA/LDA. Patients reaching both DAS28 VLDA/LDA status and PASDAS VLDA/LDA status [N = 445 (52.0%)] were compared with patients reaching only DAS28 VLDA/LDA status [N = 218 (25.5%)]. For these latter patients, significantly worse scores on separate parameters were found in measures used for PASDAS/DAS28 calculation (e.g. swollen and tender joint count and patient's visual analogue scale global disease activity) as well as other disease measures (e.g. function and inflammatory back pain). This result remained, even when the stricter VLDA cut-off was used for the DAS28. CONCLUSION: PASDAS implementation uncovered relevant residual disease activity in a quarter of patients previously assessed as being in DAS28 VLDA/LDA, underscoring the potential value of PASDAS measurements in PsA clinical care.

Comparing methotrexate monotherapy with methotrexate plus leflunomide combination therapy in psoriatic arthritis: protocol of a randomized, placebo-controlled, double-blind clinical trial (COMPLETE-PsA).

BACKGROUND: Both methotrexate (MTX) and leflunomide (LEF) are registered and regularly prescribed as first-line treatments for the use in patients with psoriatic arthritis (PsA) and they are occasionally used in combination. However, evidence about their individual, and especially combined efficacy, in PsA is lacking. The aim of this study is to compare the effectiveness and safety of MTX and LEF combination therapy to MTX monotherapy in patients with PsA. METHODS: COMPLETE-PsA is a randomized, placebo-controlled, double-blind clinical trial. Disease-modifying antirheumatic drug (DMARD)-untreated patients (n = 78) with clinical diagnosis of active (i.e. ≥2 swollen joints) PsA will be randomized 1:1 (stratified for high disease activity, Psoriatic Arthritis Disease Activity Score [PASDAS] ≥ 5.4) to the combination or monotherapy. The intervention group receives MTX 25 mg (oral or subcutaneous) once weekly plus LEF 20 mg daily, and the control group receives the same but with placebo instead of LEF daily. Primary endpoint is between-group difference in PASDAS at 16 weeks, adjusted for baseline PASDAS. Key secondary parameters include between-group comparisons in change in Disease Activity in Psoriatic Arthritis (DAPSA) score, skin score, enthesitis score, dactylitis score, and swollen/tender joint count, as well as the proportion of patients fulfilling minimal disease activity (MDA), American College of Rheumatology (ACR) 20/50/70 response criteria at week 16. Furthermore, safety, function and quality of life (Health Assessment Questionnaire [HAQ], Psoriatic Arthritic Impact of Disease [PSAID], Short Form 12 [SF-12]) will be assessed. DISCUSSION: This is, to our knowledge, the first randomized, placebo-controlled, double-blind clinical trial assessing the effectiveness of MTX and LEF combination therapy in patients with PsA. The study will provide important information for treatment strategies and treatment recommendations. TRIAL REGISTRATION: Dutch Trial Register NTR7632 (3 December 2018). CMO NL66544.091.18 (19 November 2018).

Dose reduction and withdrawal strategy for TNF-inhibitors in psoriatic arthritis and axial spondyloarthritis: design of a pragmatic open-label, randomised, non-inferiority trial.

BACKGROUND: Tumour necrosis factor inhibitors (TNFi) are effective in the treatment of patients with spondyloarthritis (SpA), including psoriatic arthritis (PsA) and axial spondyloarthritis (axSpA). However, these drugs come with some disadvantages such as adverse events, practical burden for patients and high costs. Dose optimisation of TNFi after patients have reached low disease activity (LDA) has been shown feasible and safe in rheumatoid arthritis (RA). However, data on TNFi dose optimisation in PsA and axSpA are scarce, especially pragmatic, randomised strategy studies. METHODS: We developed an investigator-driven, pragmatic, open-label, randomised, controlled, non-inferiority trial (DRESS-PS) to compare the effects of a disease activity-guided treat-to-target strategy with or without a tapering attempt in patients with SpA (PsA and axSpA combined), ≥ 16 years of age, who are being treated with TNFi, and have had at least 6 months of low disease activity. The primary outcome is the percentage of patients in LDA after 12 months of follow up. Patients are assessed at baseline, 3, 6, 9, and 12 months of follow up. Bayesian power analyses with a weakened prior based on a similar study performed in RA resulted in a sample size of 95 patients in total. DISCUSSION: More knowledge on disease activity-guided treatment algorithms would contribute to better treatment choices and cost savings and potentially decrease the risk of side effects. In this article we elucidate some of our design choices on TNFi dose optimisation and its clinical and methodological consequences. TRIAL REGISTRATION: Dutch Trial Register, NL6771. Registered on 27 November 2018 (CMO NL66181.091.18, 23 October 2018).

Increased intra-articular granzyme M may trigger local IFN-λ1/IL-29 response in rheumatoid arthritis.

OBJECTIVES: Granzymes are serine proteases involved in eliminating tumour cells and virally infected cells. In addition, extracellular granzyme levels are elevated in inflammatory conditions, including several types of infection and autoimmune diseases, such as rheumatoid arthritis (RA). While GrA and GrB have been associated with RA, a role for the other three granzymes (GrH, GrK, and GrM) in this disease remains unclear. Here, we aimed to investigate the presence and role of GrM and GrK in serum and synovial fluid of patients with RA, psoriatic arthritis, and osteoarthritis. METHODS: Granzyme levels were determined in serum, synovial fluid, peripheral blood mononuclear cells (PBMCs) and synovial fluid mononuclear cells (SFMCs) of RA patients and relevant control groups. In addition, the link between GrM and inflammatory cytokines in synovial fluid was investigated. RESULTS: Serum GrM and GrK levels were not affected in RA. GrM, but not GrK, levels were elevated in synovial fluid of RA patients. GrM was mainly expressed by cytotoxic lymphocytes in SFMCs with a similar expression pattern as compared with PBMCs. Intra-articular GrM expression correlated with IL-25, IL-29, XCL1, and TNFα levels. Intriguingly, purified GrM triggered the release of IL-29 (IFN-λ1) from human fibroblasts in vitro. CONCLUSIONS: These data indicate that GrM levels are increased in RA synovial fluid and that GrM can stimulate proinflammatory IL-29 release from fibroblasts, suggesting a role of GrM in the pathogenesis of RA.

Impaired Porphyromonas gingivalis-Induced Tumor Necrosis Factor Production by Dendritic Cells Typifies Patients With Rheumatoid Arthritis.

OBJECTIVE: The prevalence of periodontitis is increased in patients with rheumatoid arthritis (RA), and the severity of periodontitis can affect the level of arthritis. Porphyromonas gingivalis is one of the main bacteria involved in periodontitis. Our aim was to determine if there are differences in the innate immune response against P gingivalis between healthy controls and RA patients. METHODS: Monocyte-derived dendritic cells (DCs) from healthy controls, RA patients, and patients with psoriatic arthritis (PsA) were stimulated with P gingivalis, a range of other bacteria, and Toll-like receptor agonists. Cytokine production was determined, and blocking studies were performed to determine which receptors were involved in differential recognition of P gingivalis. Effects on T cell cytokines were also determined in cultures of peripheral blood mononuclear cells (PBMCs). RESULTS: Upon stimulation with P gingivalis, RA patient DCs produced less tumor necrosis factor as compared to healthy control DCs, which was not observed in PsA patients or upon stimulation with other bacteria. In addition, P gingivalis-mediated activation of RA patient PBMCs showed a clear reduction of interferon-γ production. Among the various possible underlying mechanisms investigated, only blockade of CR3 abolished the difference between RA patients and healthy controls, suggesting the involvement of CR3 in this process. CONCLUSION: Immune cells from RA patients display a reduced response to P gingivalis, which has functional consequences for the immune response. This may result in prolonged survival of P gingivalis, possibly driving autoantibody formation and a self-perpetuating loop of chronic inflammation. The possible role of CR3 in this process warrants further investigation.

Brief report: enrichment of activated group 3 innate lymphoid cells in psoriatic arthritis synovial fluid.

OBJECTIVE: Innate lymphoid cells (ILCs) are a recently discovered group of cells that are essential to epithelial homeostasis and are implicated in psoriasis pathogenesis, yet they have never been reported in psoriatic arthritis (PsA). METHODS: ILC classes and subsets were characterized in the peripheral blood (PB) of healthy controls, patients with psoriasis, and patients with PsA and in the synovial fluid (SF) of patients with PsA and patients with rheumatoid arthritis (RA). Cell surface marker expression and intracellular cytokine production following stimulation were analyzed using flow cytometry. RESULTS: ILCs were identified in the SF and were 4-fold more abundant in PsA SF than in PsA PB. Fewer CCR6+ ILCs were found in PsA PB than in healthy control PB, while PsA SF was enriched for CCR6+ ILCs compared to PsA PB and RA SF. Natural cytotoxicity receptor NKp44+ group 3 ILCs were rare in PB and RA SF, but abundant in PsA SF. Increased numbers of interleukin-17A (IL-17A)-producing ILCs were present in PsA SF compared to RA SF. CCR6, NKp44, and melanoma cell adhesion molecule (MCAM) were expressed on the cell surface of SF ILCs that produced IL-17A. The number of circulating NKp44+, CCR6+, and MCAM+ ILCs in blood was inversely correlated with PsA disease activity. CONCLUSION: Our findings indicate that PsA SF is enriched for group 3 ILCs that express CCR6 and NKp44, which distinguishes the synovial compartment from RA. The increased IL-17A production by SF ILCs indicates a novel role for ILCs in PsA.

Perception of self: distinguishing autoimmunity from autoinflammation.

Rheumatic diseases can be divided in two groups, autoinflammatory and autoimmune disorders. The clinical presentation of both types of diseases overlap, but the pathological pathways underlying rheumatic autoinflammation and autoimmunity are distinct and are the subject of ongoing research. There are a number of ways in which these groups of diseases differ in terms of disease mechanisms and therapeutic responses. First, autoinflammatory diseases are driven by endogenous danger signals, metabolic mediators and cytokines, whereas autoimmunity involves the activation of T and B cells, the latter requiring V-(D)-J recombination of receptor-chain gene segments for maturation. Second, the efficacy of biologic agents directed against proinflammatory cytokines (for example IL-1ß and TNF) also highlights differences between autoinflammatory and autoimmune processes. Finally, whereas autoinflammatory diseases are mostly driven by inflammasome-induced IL-1ß and IL-18 production, autoimmune diseases are associated with type I interferon (IFN) signatures in blood. In this Review, we provide an overview of the monocyte intracellular pathways that drive autoinflammation and autoimmunity. We convey recent findings on how the type I IFN pathway can modulate IL-1ß signalling (and vice versa), and discuss why IL-1ß-mediated autoinflammatory diseases do not perpetuate into autoimmunity. The origins of intracellular autoantigens in autoimmune disorders are also discussed. Finally, we suggest how new mechanistic knowledge of autoinflammatory and autoimmune diseases might help improve treatment strategies to benefit patient care.

Fc gamma receptor IIb on GM-CSF macrophages controls immune complex mediated inhibition of inflammatory signals.

BACKGROUND: In rheumatoid arthritis (RA) macrophages play a major role in amplifying synovial inflammation. Important activating signals are those induced by Toll-like receptor (TLR) ligands and by activated T cells. The balance between activating and inhibitory Fc gamma receptors (FcγRs) on macrophages might be crucial in modulating these inflammatory responses. The purpose of this study was to determine FcγR expression on pro- and anti-inflammatory macrophages (gmMφ and mMφ, respectively) and identify functional consequences on immune complex uptake and macrophage activation. METHODS: Human monocytes were isolated and differentiated into gmMφ and mMφ. A full FcγR characterization of both macrophage subtypes was performed and uptake of fluorescent immune complexes (ICs) was determined. FcγRIIb isoforms were determined by qPCR. Macrophages were stimulated via different TLRs or cytokine activated T cells in the presence or absence of ICs and cytokine production was determined. Blocking studies were performed to look into the pathways involved. RESULTS: mMφ expressed high levels of the activating FcγRIIa and FcγRIII and low levels of the inhibitory FcγRIIb, while the FcγR balance on gmMφ was shifted towards the inhibitory FcγRIIb. This was accompanied by a clear increase in FcγRIIb1 mRNA expression in gmMφ. This resulted in higher IC uptake by mMφ compared to gmMφ. Furthermore, FcγR-mediated stimulation of gmMφ inhibited TLR2, 3, 4 and 7/8 mediated cytokine production via FcγRIIb and PI3K signaling. In addition, gmMφ but not mMφ produced TNFα upon co-culture with cytokine activated T cells, which was reduced by IC binding to FcγRIIb. The latter was dependent on PI3K signaling and COX2. CONCLUSIONS: FcγR expression patterns on gmMφ and mMφ are significantly different, which translates in clear functional differences further substantiating FcγRIIb as an interesting target for inflammation control in RA and other autoimmune/inflammatory diseases.

Soluble immune complexes shift the TLR-induced cytokine production of distinct polarized human macrophage subsets towards IL-10.

BACKGROUND: Costimulation of murine macrophages with immune complexes (ICs) and TLR ligands leads to alternative activation. Studies on human myeloid cells, however, indicate that ICs induce an increased pro-inflammatory cytokine production. This study aimed to clarify the effect of ICs on the pro- versus anti-inflammatory profile of human polarized macrophages. MATERIALS AND METHODS: Monocytes isolated from peripheral blood of healthy donors were polarized for four days with IFN-γ, IL-4, IL-10, GM-CSF, M-CSF, or LPS, in the presence or absence of heat aggregated gamma-globulins (HAGGs). Phenotypic polarization markers were measured by flow cytometry. Polarized macrophages were stimulated with HAGGs or immobilized IgG alone or in combination with TLR ligands. TNF, IL-6, IL-10, IL-12, and IL-23 were measured by Luminex and/or RT-qPCR. RESULTS: HAGGs did not modulate the phenotypic polarization and the cytokine production of macrophages. However, HAGGs significantly altered the TLR-induced cytokine production of all polarized macrophage subsets, with the exception of MΦ(IL-4). In particular, HAGGs consistently enhanced the TLR-induced IL-10 production in both classically and alternatively polarized macrophages (M1 and M2). The effect of HAGGs on TNF and IL-6 production was less pronounced and depended on the polarization status, while IL-23p19 and IL-12p35 expression was not affected. In contrast with HAGGs, immobilized IgG induced a strong upregulation of not only IL-10, but also TNF and IL-6. CONCLUSION: HAGGs alone do not alter the phenotype and cytokine production of in vitro polarized human macrophages. In combination with TLR-ligands, however, HAGGs but not immobilized IgG shift the cytokine production of distinct macrophage subsets toward IL-10.

Impaired dendritic cell proinflammatory cytokine production in psoriatic arthritis.

OBJECTIVE: The pathogenesis of psoriatic arthritis (PsA) remains poorly understood. The underlying chronic inflammatory immune response is thought to be triggered by unknown environmental factors potentially arising from a defective immune function. We undertook this study to determine whether an impaired acute inflammatory response by dendritic cells (DCs) might compromise the clearance of bacteria and predispose to chronic inflammation. METHODS: We determined cytokine production by DCs from healthy controls and from patients with rheumatoid arthritis, PsA, and psoriasis in response to Mycobacterium tuberculosis, Mycobacterium avium paratuberculosis, and a range of other bacteria and Toll-like receptor (TLR) ligands. Phenotypic differences involved in cellular responses against (myco)bacteria were determined by quantitative polymerase chain reaction and flow cytometry. RESULTS: The secretion of proinflammatory cytokines by PsA DCs was impaired upon in vitro challenge with mycobacteria and TLR-2 ligands. This impairment was associated with elevated serum levels of C-reactive protein. The expression of TLR-2 and other receptors known to mediate mycobacterial recognition was unaltered. In contrast, the intracellular TLR inhibitors suppressor of cytokine signaling 3 and A20 were more highly expressed in DCs from PsA patients. PsA DCs further demonstrated up-regulated levels of ATG16L1, NADPH oxidase 2, and LL37, which are molecules implicated in the immune response against intracellular bacteria. CONCLUSION: Our findings indicate that DCs from PsA patients have a disordered immune response toward some species of (myco)bacteria. This might predispose to impaired immune responses to, and in turn impaired clearance of, these bacteria, setting the stage for the chronic inflammation of joints, entheses, skin, and the gut.

TLR2 promotes Th2/Th17 responses via TLR4 and TLR7/8 by abrogating the type I IFN amplification loop.

TLR2 plays an important role in the removal of Gram-positive bacteria; contrastingly, it also appears to have important protective effects against unrestrained inflammation and subsequent organ injury during infection and autoimmunity. We hypothesized that TLR2 tunes the phenotype of dendritic cells (DCs) activated through other TLRs, thereby fulfilling a crucial role in the modulation of the immune response. TLR2 potently inhibited TLR4- and TLR7/8-induced cytokine production by human DCs. The inhibitory effect of TLR2 on the release of TNF-alpha but not of IL-12p70 was mediated by PI3K. TLR2 inhibits the production of IL-12p70 by dampening the type 1 IFN amplification loop. When DCs were triggered with the potent synergistic combination of LPS (TLR4) and R848 (TLR7/8) in conjunction with a TLR2 ligand, a clear shift to more Th2- and Th17-prone responses in the naive and memory T cell subpopulations was observed. This shift in T cell responses was inherent to the inability of TLR2-stimulated DCs to produce IL-12p70 and was dependent on the production of IL-1 and IL-6.

The functional variant (Asp299gly) of toll-like receptor 4 (TLR4) influences TLR4-mediated cytokine production in rheumatoid arthritis.

OBJECTIVE: To investigate functional consequences of the Toll-like receptor 4 (TLR4) variant (Asp299Gly) in rheumatoid arthritis (RA). METHODS: Peripheral blood mononuclear cells from 28 patients with RA carrying or not carrying the TLR4 variant were incubated with lipopolysaccharide (LPS) and heat shock protein B8 (HSPB8). Concentrations of interleukin 6 (IL-6), tumor necrosis factor-alpha(TNF-alpha), and IL-10 were determined along with TLR4 and CD14 expression. RESULTS: TLR4 expression was similar in patients carrying or not carrying the variant. In contrast, both LPS and HSPB8 resulted in significantly lower secretion of IL-6, TNF-alpha, and IL-10 in those who carried the variant, whereas the frequency of CD14+ cells was higher in these individuals. CONCLUSION: TLR4 variant clearly reduces its potency to mediate signaling. Correction for CD14+ cells is necessary in comparable experiments.