Human MHC Class II and Invariant Chain Knock-in Mice Mimic Rheumatoid Arthritis with Allele Restriction in Immune Response and Arthritis Association.

Transgenic mice expressing human major histocompatibility complex class II (MHCII) risk alleles are widely used in autoimmune disease research, but limitations arise due to non-physiologic expression. To address this, physiologically relevant mouse models are established via knock-in technology to explore the role of MHCII in diseases like rheumatoid arthritis. The gene sequences encoding the ectodomains are replaced with the human DRB1*04:01 and 04:02 alleles, DRA, and CD74 (invariant chain) in C57BL/6N mice. The collagen type II (Col2a1) gene is modified to mimic human COL2. Importantly, DRB1*04:01 knock-in mice display physiologic expression of human MHCII also on thymic epithelial cells, in contrast to DRB1*04:01 transgenic mice. Humanization of the invariant chain enhances MHCII expression on thymic epithelial cells, increases mature B cell numbers in spleen, and improves antigen presentation. To validate its functionality, the collagen-induced arthritis (CIA) model is used, where DRB1*04:01 expression led to a higher susceptibility to arthritis, as compared with mice expressing DRB1*04:02. In addition, the humanized T cell epitope on COL2 allows autoreactive T cell-mediated arthritis development. In conclusion, the humanized knock-in mouse faithfully expresses MHCII, confirming the DRB1*04:01 alleles role in rheumatoid arthritis and being also useful for studying MHCII-associated diseases.

[Epidemiological data and medical care situation of patients with chronic inflammatory diseases in Germany : Real-world evidence on prevalence, disease combinations, care]. / Epidemiologische Daten und medizinische Versorgungssituation von Patienten mit chronischen Entzündungserkrankungen in Deutschland : Real-World-Evidenz zu Prävalenz, Erkrankungskombinationen, Versorgung.

BACKGROUND: Chronic inflammatory diseases (immune-mediated inflammatory diseases, IMID) can overlap or occur simultaneously due to clinical similarities. The resulting utilization of heathcare structures has not yet been investigated across disciplines but is of potential importance for optimizing the treatment of patients with IMID. AIM OF THE WORK: Analysis of epidemiological data including utilization of care services in patients with selected IMIDs: psoriasis, psoriatic arthritis (PsA), rheumatoid arthritis (RA), ankylosing spondylitis, ulcerative colitis, Crohn's disease and connective tissue disease. MATERIAL AND METHODS: In a retrospective cross-sectional analysis based on health insurances accounting data with a sample of approximately 4 million insured persons, the prevalence of the abovementioned IMID and the frequency of IMID combinations were analyzed based on documented diagnoses (ICD-10 GM). The frequency of hospitalizations and utilization of outpatient physician contacts was recorded in predefined specialist disciplines (general medicine, dermatology, gastroenterology, rheumatology) and compared with an age-adjusted and gender-adjusted reference population. RESULTS: A total of 188,440 patients had at least 1 of the IMID diagnoses analyzed (4.7%), with an age peak of 61-70 years. The highest prevalence was observed for psoriasis (1.85%), followed by rheumatoid arthritis (1.38%). Combinations with at least one other IMID were relatively common (29%), with this being most common in patients with psoriatic arthritis (82.9%, of which 68.2% had psoriasis), followed by ankylosing spondylitis (27.5%) and Crohn's disease (21.6%). Compared to the reference population, patients with IMID were hospitalized more often and more frequently utilized the outpatient disciplines. DISCUSSION: The study results describe that IMIDs occur in combination and that the patients make comparatively more use of care structures of different disciplines. A multidisciplinary approach could increase the efficiency of care; an evaluation is still pending.

GWAS meta-analysis of psoriasis identifies new susceptibility alleles impacting disease mechanisms and therapeutic targets.

Psoriasis is a common, debilitating immune-mediated skin disease. Genetic studies have identified biological mechanisms of psoriasis risk, including those targeted by effective therapies. However, the genetic liability to psoriasis is not fully explained by variation at robustly identified risk loci. To move towards a saturation map of psoriasis susceptibility we meta-analysed 18 GWAS comprising 36,466 cases and 458,078 controls and identified 109 distinct psoriasis susceptibility loci, including 45 that have not been previously reported. These include susceptibility variants at loci in which the therapeutic targets IL17RA and AHR are encoded, and deleterious coding variants supporting potential new drug targets (including in STAP2, CPVL and POU2F3). We conducted a transcriptome-wide association study to identify regulatory effects of psoriasis susceptibility variants and cross-referenced these against single cell expression profiles in psoriasis-affected skin, highlighting roles for the transcriptional regulation of haematopoietic cell development and epigenetic modulation of interferon signalling in psoriasis pathobiology.

Antigen-presenting autoreactive B cells activate regulatory T cells and suppress autoimmune arthritis in mice.

B cells undergo several rounds of selection to eliminate potentially pathogenic autoreactive clones, but in contrast to T cells, evidence of positive selection of autoreactive B cells remains moot. Using unique tetramers, we traced natural autoreactive B cells (C1-B) specific for a defined triple-helical epitope on collagen type-II (COL2), constituting a sizeable fraction of the physiological B cell repertoire in mice, rats, and humans. Adoptive transfer of C1-B suppressed arthritis independently of IL10, separating them from IL10-secreting regulatory B cells. Single-cell sequencing revealed an antigen processing and presentation signature, including induced expression of CD72 and CCR7 as surface markers. C1-B presented COL2 to T cells and induced the expansion of regulatory T cells in a contact-dependent manner. CD72 blockade impeded this effect suggesting a new downstream suppressor mechanism that regulates antigen-specific T cell tolerization. Thus, our results indicate that autoreactive antigen-specific naïve B cells tolerize infiltrating T cells against self-antigens to impede the development of tissue-specific autoimmune inflammation.

Impact of different classes of immune-modulating treatments on B cell-related and T cell-related immune response before and after COVID-19 booster vaccination in patients with immune-mediated diseases and primary immunodeficiency: a cohort study.

OBJECTIVES: To evaluate the potential of immunosuppressed patients to mount B-cell and T-cell responses to COVID-19 booster vaccination (third vaccination). METHODS: Patients with primary immunodeficiency (PID), immune-mediated inflammatory diseases (IMIDs) on CD20-depleting treatment with rituximab (RTX), or IMIDs treated with conventional synthetic disease-modifying antirheumatic drugs (csDMARDs) or biological disease-modifying antirheumatic drug (bDMARDs) were included and assessed before (baseline visit (BL)) and 2, 4 and 8 weeks after COVID-19 booster vaccination. Serum B-cell responses were assessed by antibody levels against SARS-CoV-2 spike protein (anti-spike IgG antibody (S-AB)) and a surrogate virus neutralisation test (sVNT). T-cell responses were assessed by an interferon gamma release assay (IGRA). RESULTS: Fifty patients with PID (n=6), treated with RTX therapy (n=13), or treated with csDMARDs/bDMARDs (n=31) were included. At BL, anti-S-AB titres in PID and csDMARD/bDMARD-treated patients were low (although significantly higher than RTX patients); measures of B-cell-mediated response increased significantly after booster vaccination. In the RTX cohort, low BL anti-S-AB and sVNT values did not improve after booster vaccination, but patients had significantly elevated IGRA responses post booster vaccination compared with the other groups. csDMARD/bDMARD-treated patients showed the highest BL values in all three assays with greater increases in all parameters after booster vaccination compared with patients with PID. CONCLUSION: Patients with IMID on therapeutic B-cell depletion have low anti-S-AB and sVNT values before and after booster vaccination but show significantly higher levels of IGRA compared with other immunosuppressed patients, suggesting an underlying mechanism attempting to compensate compromised humoral immunity by upregulating T-cell responsiveness. PID appears to have a stronger impact on antiviral immune response than csDMARD/bDMARD treatment.

Therapy targeting antigen-specific T cells by a peptide-based tolerizing vaccine against autoimmune arthritis.

A longstanding goal has been to find an antigen-specific preventive therapy, i.e., a vaccine, for autoimmune diseases. It has been difficult to find safe ways to steer the targeting of natural regulatory antigen. Here, we show that the administration of exogenous mouse major histocompatibility complex class II protein bounding a unique galactosylated collagen type II (COL2) peptide (Aq-galCOL2) directly interacts with the antigen-specific TCR through a positively charged tag. This leads to expanding a VISTA-positive nonconventional regulatory T cells, resulting in a potent dominant suppressive effect and protection against arthritis in mice. The therapeutic effect is dominant and tissue specific as the suppression can be transferred with regulatory T cells, which downregulate various autoimmune arthritis models including antibody-induced arthritis. Thus, the tolerogenic approach described here may be a promising dominant antigen-specific therapy for rheumatoid arthritis, and in principle, for autoimmune diseases in general.

The role of antidrug antibodies in ustekinumab therapy and the impact of methotrexate.

OBJECTIVE: We investigated the impact of concomitant MTX on ustekinumab (UST) levels and antidrug antibody (ADA) formation in PsA and evaluated consequences in pharmacodynamics and pharmacokinetics. METHODS: We conducted a post-hoc analysis on 112 PsA serum samples of subjects treated with open-label UST and either concomitant MTX (UST/MTX, n = 58) or placebo (UST/pbo, n = 54) obtained in a randomized (1:1), double-blind, multicentre trial. A validated antibody-binding-based multitiered testing was used to detect ADA and ADA with neutralizing capacity (nADA). The impact of MTX on UST immunogenicity was analysed by comparison of UST/pbo with UST/MTX cohorts at different time points. Patient- and disease-related predispositions for ADA formation were investigated with multiple linear regression analysis. Immunogenicity impact on pharmacokinetics, safety and efficacy was determined by cohort comparison between patients with and without ADA formation. RESULTS: Over 52 weeks, 11 UST/pbo- and 19 UST/MTX-treated patients developed ADA (P > 0.05). In the UST/pbo cohort, the visit-dependent UST levels were in the range of 0.047 (0.05) -0.110 (0.07) µg/ml overall, and 0.037 (0.04)-0.091 (0.08) µg/ml in ADA-confirmed subjects. In UST/MTX-treated patients, the UST levels exhibited an intervisit variation in the range of 0.0502 (0.04)-0.106 (0.07) µg/ml overall and 0.029 (0.03)-0.097 (0.07) µg/ml in ADA positive subjects (P > 0.05). At week 52, ADA-confirmed patients did not differ significantly (P > 0.05) in safety or clinical outcomes from ADA-negative patients. CONCLUSION: Concomitant MTX had no significant impact on UST immunogenicity. Furthermore, ADA formation was not associated with impairments in UST safety, efficacy or trough levels. TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT03148860.

[Mechanisms of immunological tolerance and their dysregulation in rheumatic diseases]. / Mechanismen immunologischer Toleranz und ihrer Dysregulation bei rheumatischen Erkrankungen.

The major tasks of the immune system are protection against infectious agents, maintaining homeostasis by recognizing and neutralizing noxious substances from the environment, and monitoring pathological, e.g. neoplastic tissue changes. It accomplishes these tasks through complex interactions of cellular and humoral components of the innate and adaptive immune system. This review article focuses on a central problem of self versus non-self discrimination in the development of B and T lymphocytes as carriers of adaptive immunity. During maturation of the lymphocytes in the bone marrow, large repertoires of lymphocyte receptors are randomly generated by somatic recombination, which as a whole have the capability of recognizing any foreign antigen. In order to reduce the implicit risk of autoaggressive immunity that might arise from evolutionary conserved structural motifs in self and foreign antigens, the adaptive immune system must provide redundant mechanisms (clonal deletion, anergy, quiescence and suppression) to eliminate or inactivate lymphocytes expressing highly avid receptors for autoantigens. Thus, the provision of costimulatory signals resulting in a reduced activation threshold of potentially autoreactive anergic T cells through infection, molecular mimicry, disrupted apoptosis regulation, altered "self" by post-translational modification, genetic changes in transcription factors with critical importance for thymic tolerance induction or signaling components of apoptosis can lead to a disruption of self-tolerance and the induction of pathogenic autoimmunity.

The role of YAP1 target gene CTGF in the anoikis resistance of rheumatoid arthritis synovial fibroblasts.

OBJECTIVE: To analyse pro-survival mechanisms elicited in RA synovial fibroblasts (RASFs) upon detachment from their extracellular matrix dependent on the disintegrin metalloproteinase ADAM15 and Yes-associated protein kinase 1 (YAP1). METHODS: Detachment-induced apoptosis was determined by caspase 3/7 assays. Immunofluorescent stainings, cell surface biotinylation and immunoblotting were applied to analyse phosphorylated kinases and subcellular localization of YAP1 and connective tissue growth factor (CTGF). Caspase and transwell transmigration assays served to study CTGF function. RESULTS: Silencing of ADAM15 or YAP1 in RASFs leads to significantly increased levels of detachment-induced caspase activity. In non-silenced RASFs detachment causes simultaneous ADAM15-enhanced phosphorylation of YAP1 at S127, known for promoting its cytoplasmic localization, and Src-dependent phosphorylation at tyrosine Y357. The majority of nuclear YAP1 leaves the nucleus shortly after cell detachment, but prolonged detachment causes a marked nuclear re-entry of YAP1, resulting in significantly increased synthesis of CTGF. The newly synthesized CTGF, however, is not detectable in the supernatant, but is bound to the outside of the plasma membrane. In vitro studies demonstrated autocrine binding of CTGF to the EGF receptor and ß1 integrin, with concomitant triggering of survival kinases, AKT1, ERK1/2, Src and focal adhesion kinase. Functional studies revealed anti-apoptotic effects of CTGF on detached RASFs and an enhancement of their potential for endothelial transmigration using HUVEC-coated transwells. CONCLUSION: The elucidation of a new molecular mechanism that protects RASFs in the highly pro-apoptotic environment of inflamed RA joints by promoting anoikis-resistance and transendothelial migration via ADAM15/YAP1-mediated CTGF upregulation uncovers potentially new targets for future therapeutic intervention.

Methotrexate plus ustekinumab versus ustekinumab monotherapy in patients with active psoriatic arthritis (MUST): a randomised, multicentre, placebo-controlled, phase 3b, non-inferiority trial.

BACKGROUND: The role of methotrexate in combination with biological agents in patients with psoriatic arthritis remains unclear. The MUST phase 3b trial aimed to compare the efficacy of ustekinumab plus placebo with ustekinumab plus methotrexate in patients with active psoriatic arthritis. METHODS: In this investigator-initiated, randomised, multicentre, placebo-controlled, phase 3b non-inferiority trial done in 22 centres in Germany, patients with active psoriatic arthritis received open-label ustekinumab and were randomly assigned (1:1) to masked concomitant therapy with placebo or methotrexate (ongoing or new). The primary outcome was non-inferiority of mean Disease Activity Score-28 joints (DAS28) at week 24 for ustekinumab monotherapy (ustekinumab plus placebo) versus ustekinumab combination therapy (ustekinumab plus methotrexate), stratified by previous methotrexate treatment. The key secondary analysis was non-inferiority of DAS28 at week 52. The primary analysis was based on a stratified van Elteren test with an α of 2·5% and a non-inferiority margin of 12·5% by Mann-Whitney estimator. Adverse events and serious adverse events were assessed. This study is registered with ClinicalTrials.gov, NCT03148860. FINDINGS: Between Jan 24, 2017, and April 12, 2021, 186 patients with active psoriatic arthritis were screened, of whom 173 (93%) patients were enrolled and randomly assigned (1:1) to receive concomitant methotrexate therapy (n=88) or placebo (n=85). 84 patients were receiving methotrexate at baseline, and 89 patients had no previous methotrexate treatment. 166 (96%) patients (87 in the ustekinumab plus methotrexate group and 79 in the ustekinumab plus placebo group) were included in the safety and efficacy analyses at week 24 (69 [42%] female; 97 [58%] male; mean age 48·2 years [SE 1·1]). Ustekinumab plus placebo was non-inferior to ustekinumab plus methotrexate in DAS28 at week 24 (2·9 [SD 1·31] vs 3·1 [1·42]); the stratified Mann-Whitney estimator for treatment comparison was 0·5426 (95% CI 0·4545-0·6307). Non-inferiority for ustekinumab plus placebo was also observed in DAS28 at week 52. Serious adverse events occurred in seven (9%) patients in the ustekinumab plus placebo group and eight (9%) patients in the ustekinumab plus methotrexate group. No specific serious adverse events affected more than one patient, and there were no deaths. INTERPRETATION: Interleukin (IL)-12 and IL-23 inhibition with ustekinumab is an effective treatment for psoriatic arthritis independent of methotrexate use; concomitant methotrexate did not increase efficacy of ustekinumab (based on DAS28). On the basis of these data, there is no evidence to support the addition or maintainance of methotrexate when initiating ustekinumab in patients with active psoriatic arthritis. FUNDING: Janssen Cilag.

Effectiveness of Different Rituximab Doses Combined with Leflunomide in the Treatment or Retreatment of Rheumatoid Arthritis: Part 2 of a Randomized, Placebo-Controlled, Investigator-Initiated Clinical Trial (AMARA).

BACKGROUND: The optimal dose of rituximab in combination with leflunomide in patients with rheumatoid arthritis (RA) is not known. METHODS: In Part 1 (previously reported) of the investigator-initiated AMARA study (EudraCT 2009-015950-39; ClinicalTrials.gov NCT01244958), improvements at week (W)24 were observed in patients randomized to rituximab + leflunomide compared with placebo + leflunomide. In the study reported here (Part 2), Part 1 responders received rituximab 500 or 1000 mg at W24/26 plus ongoing leflunomide. Patients were randomized at baseline to their eventual W24 treatment group. The Part 2 primary outcome was the mean Disease Activity Score-28 joints (DAS28) at W52, based on the last observation carried forward (LOCF) analyses and a two-sided analysis of variance. Patient-reported outcomes (PROs) and adverse events were evaluated. RESULTS: Eighty-three patients received rituximab at W24/26 (31 rituximab→rituximab 1000 mg; 29 rituximab→rituximab 500 mg; 10 placebo→rituximab 1000 mg; 13 placebo→rituximab 500 mg). At W52, there were no significant differences in DAS28 between rituximab doses in patients originally treated with rituximab or those originally treated with placebo. In the Part 1 placebo group, the higher rituximab dose was associated with greater improvements in ACR response rates and some PROs. Adverse events were similar regardless of rituximab dose. CONCLUSIONS: Retreatment with rituximab 500 mg and 1000 mg showed comparable efficacy, whereas an initial dose of rituximab 500 mg was associated with lower response rates versus 1000 mg. Reduced treatment response with the lower dose in patients initially treated with placebo may have been influenced by small numbers and baseline disease activity.

Sarilumab reduces disease activity in rheumatoid arthritis patients with inadequate response to janus kinase inhibitors or tocilizumab in regular care in Germany.

OBJECTIVES: The aim was to evaluate the safety and effectiveness of sarilumab in RA patients after inadequate response (IR) to janus kinase inhibitors (JAKi) and tocilizumab. METHODS: The prospective, observational, 24-month single-arm PROSARA study (SARILL08661) is currently running in Germany at 96 sites. RA patients were prospectively selected at the physician's discretion according to label. This interim analysis included 536 patients over a treatment course of ≤6 months. Patients were stratified in four groups according to pretreatment before the start of sarilumab therapy: last prior treatment JAKi (JAKi-IR); last prior treatment tocilizumab (tocilizumab-IR); any other biological DMARD (bDMARD) in treatment history (bDMARD TH); and patients who had not received any bDMARDs or targeted synthetic (ts) DMARDs (b/tsDMARD naive) before. RESULTS: For this preplanned interim analysis, 536 patients were included in the baseline population, of whom 502 patients had at least one corresponding post-baseline effectiveness assessment documented (main analysis population). In all analysed cohorts, safety was consistent with the anticipated profile of sarilumab, without new safety signals. Six months of sarilumab treatment attenuated disease activity in JAKi-IR, tocilizumab-IR, bDMARD TH and b/tsDMARD-naive patients to a very similar extent. Physical function did not change substantially over the course of treatment. Rates of premature study discontinuation were comparable between cohorts. CONCLUSION: Sarilumab treatment was effective in patients with IR to JAKi and tocilizumab, with an expectable safety profile and drug retention over 6 months. Confirmation of these promising results should encourage further studies on this treatment sequence, which is of high practical relevance. STUDY REGISTRATION: Paul-Ehrlich-Institut-Federal Institute for Vaccine and Biomedics, SARILL08661.

Key interactions in the trimolecular complex consisting of the rheumatoid arthritis-associated DRB1*04:01 molecule, the major glycosylated collagen II peptide and the T-cell receptor.

OBJECTIVES: Rheumatoid arthritis (RA) is an autoimmune disease strongly associated with the major histocompatibility complex (MHC) class II allele DRB1*04:01, which encodes a protein that binds self-peptides for presentation to T cells. This study characterises the autoantigen-presenting function of DRB1*04:01 (HLA-DRA*01:01/HLA-DRB1*04:01) at a molecular level for prototypic T-cell determinants, focusing on a post-translationally modified collagen type II (Col2)-derived peptide. METHODS: The crystal structures of DRB1*04:01 molecules in complex with the peptides HSP70289-306, citrullinated CILP982-996 and galactosylated Col2259-273 were determined on cocrystallisation. T cells specific for Col2259-273 were investigated in peripheral blood mononuclear cells from patients with DRB1*04:01-positive RA by cytofluorometric detection of the activation marker CD154 on peptide stimulation and binding of fluorescent DRB1*0401/Col2259-273 tetramer complexes. The cDNAs encoding the T-cell receptor (TCR) α-chains and ß-chains were cloned from single-cell sorted tetramer-positive T cells and transferred via a lentiviral vector into TCR-deficient Jurkat 76 cells. RESULTS: The crystal structures identified peptide binding to DRB1*04:01 and potential side chain exposure to T cells. The main TCR recognition sites in Col2259-273 were lysine residues that can be galactosylated. RA T-cell responses to DRB1*04:01-presented Col2259-273 were dependent on peptide galactosylation at lysine 264. Dynamic molecular modelling of a functionally characterised Col2259-273-specific TCR complexed with DRB1*04:01/Col2259-273 provided evidence for differential allosteric T-cell recognition of glycosylated lysine 264. CONCLUSIONS: The MHC-peptide-TCR interactions elucidated in our study provide new molecular insights into recognition of a post-translationally modified RA T-cell determinant with a known dominant role in arthritogenic and tolerogenic responses in murine Col2-induced arthritis.

Fluorescence-optical imaging as a promising easy-to-use imaging biomarker to increase early psoriatic arthritis detection in patients with psoriasis: a cross-sectional cohort study with follow-up.

OBJECTIVES: To evaluate the ability of fluorescence-optical imaging (FOI) to detect preclinical musculoskeletal inflammatory signs in patients with skin psoriasis at risk of developing psoriatic arthritis (PsA). METHODS: This investigator-initiated prospective exploratory study evaluated adult patients with psoriasis with musculoskeletal complaints and/or nail psoriasis within the last 6 months. Patients underwent a comprehensive rheumatological clinical examination (CE) along with musculoskeletal ultrasound (MSUS) and FOI of both hands at a single visit. Patients with CE-/MSUS-/FOI+ findings had MRI performed on the symptomatic or dominant hand within 7 days. If MRI was negative, the patients were followed over 2 years for the onset of clinically manifest PsA. RESULTS: A total of 389 patients were referred from dermatology centres and evaluated at 14 rheumatology sites in Germany. Seventy-seven (20%) patients with CE-/US-/FOI- were considered to have psoriasis only. PsA was diagnosed in 140/389 patients (36%) based on CE alone and in another 55 patients (14%) by additional MSUS; overall, 50% of the patient cohort was diagnosed with PsA. One hundred sixteen patients (30%) were FOI+ (CE-) of which 40 (37%) were FOI+/MRI+. In the 2-year follow-up of the FOI+/CE- patients, clinical PsA was confirmed in another 12%. CONCLUSION: FOI is a promising method for the detection of signs of musculoskeletal inflammation in hands that may serve as an early imaging biomarker for transitions from psoriasis to PsA. This imaging technique has the potential to detect PsA in at-risk patients with psoriasis, reduce time to PsA diagnosis and improve patient outcomes.

A Novel Pro-Inflammatory Mechanosensing Pathway Orchestrated by the Disintegrin Metalloproteinase ADAM15 in Synovial Fibroblasts.

Mechanotransduction is elicited in cells upon the perception of physical forces transmitted via the extracellular matrix in their surroundings and results in signaling events that impact cellular functions. This physiological process is a prerequisite for maintaining the integrity of diarthrodial joints, while excessive loading is a factor promoting the inflammatory mechanisms of joint destruction. Here, we describe a mechanotransduction pathway in synovial fibroblasts (SF) derived from the synovial membrane of inflamed joints. The functionality of this pathway is completely lost in the absence of the disintegrin metalloproteinase ADAM15 strongly upregulated in SF. The mechanosignaling events involve the Ca2+-dependent activation of c-Jun-N-terminal kinases, the subsequent downregulation of long noncoding RNA HOTAIR, and upregulation of the metabolic energy sensor sirtuin-1. This afferent loop of the pathway is facilitated by ADAM15 via promoting the cell membrane density of the constitutively cycling mechanosensitive transient receptor potential vanilloid 4 calcium channels. In addition, ADAM15 reinforces the Src-mediated activation of pannexin-1 channels required for the enhanced release of ATP, a mediator of purinergic inflammation, which is increasingly produced upon sirtuin-1 induction.

Rituximab plus leflunomide in rheumatoid arthritis: a randomized, placebo-controlled, investigator-initiated clinical trial (AMARA study).

OBJECTIVE: To investigate the efficacy and safety of rituximab + LEF in patients with RA. METHODS: In this investigator-initiated, randomized, double-blind, placebo-controlled phase 3 trial, patients with an inadequate response to LEF who had failed one or more DMARD were randomly assigned 2:1 to i.v. rituximab 1000 mg or placebo on day 1 and 15 plus ongoing oral LEF. The primary efficacy outcome was the difference between ≥50% improvement in ACR criteria (ACR50 response) rates at week 24 (P ≤ 0.025). Secondary endpoints included ACR20/70 responses, ACR50 responses at earlier timepoints and adverse event (AE) rates. The planned sample size was not achieved due to events beyond the investigators' control. RESULTS: Between 13 August 2010 and 28 January 2015, 140 patients received rituximab (n = 93) or placebo (n = 47) plus ongoing LEF. Rituximab + LEF resulted in an increase in the ACR50 response rate that was significant at week 16 (32 vs 15%; P = 0.020), but not week 24 (27 vs 15%; P = 0.081), the primary endpoint. Significant differences favouring the rituximab + LEF arm were observed in some secondary endpoints, including ACR20 rates from weeks 12 to 24. The rituximab and placebo arms had similar AE rates (71 vs 70%), but the rituximab arm had a higher rate of serious AEs (SAEs 20 vs 2%), primarily infections and musculoskeletal disorders. CONCLUSION: The primary endpoint was not reached, but rituximab + LEF demonstrated clinical benefits vs LEF in secondary endpoints. Although generally well tolerated, the combination was associated with additional SAEs and requires monitoring. TRIAL REGISTRATION: EudraCT: 2009-015950-39; ClinicalTrials.gov: NCT01244958.

Innovative Imaging Technique for Visualization of Vascularization and Established Methods for Detection of Musculoskeletal Inflammation in Psoriasis Patients.

Psoriasis (PsO) is one of the common chronic inflammatory skin diseases. Approximately 3% of the European Caucasian population is affected. Psoriatic arthritis (PsA) is a chronic immune-mediated disease associated with PsO characterized by distinct musculoskeletal inflammation. Due to its heterogeneous clinical manifestations (e.g., oligo- or polyarthritis, enthesitis, dactylitis, and axial inflammation), early diagnosis of PsA is often difficult and delayed. Approximately 30% of PsO patients will develop PsA. The responsible triggers for the transition from PsO only to PsA are currently unclear, and the impacts of different factors (e.g., genetic, environmental) on disease development are currently discussed. There is a high medical need, recently unmet, to specifically detect those patients with an increased risk for the development of clinically evident PsA early to initiate sufficient treatment to inhibit disease progression and avoid structural damage and loss of function or even intercept disease development. Increased neoangiogenesis and enthesial inflammation are hypothesized to be early pathological findings in PsO patients with PsA development. Different disease states describe the transition from PsO to PsA. Two of those phases are of value for early detection of PsA at-risk patients to prevent later development of PsA as changes in biomarker profiles are detectable: the subclinical phase (soluble and imaging biomarkers detectable, no clinical symptoms) and the prodromal phase (imaging biomarkers detectable, unspecific musculoskeletal symptoms such as arthralgia and fatigue). To target the unmet need for early detection of this at-risk population and to identify the subgroup of patients who will transition from PsO to PsA, imaging plays an important role in characterizing patients precisely. Imaging techniques such as ultrasound (US), magnetic resonance imaging (MRI), and computerized tomography (CT) are advanced techniques to detect sensitively inflammatory changes or changes in bone structure. With the use of these techniques, anatomic structures involved in inflammatory processes can be identified. These techniques are complemented by fluorescence optical imaging as a sensitive method for detection of changes in vascularization, especially in longitudinal measures. Moreover, high-resolution peripheral quantitative CT (HR-pQCT) and dynamic contrast-enhanced MRI (DCE-MRI) may give the advantage to identify PsA-related early characteristics in PsO patients reflecting transition phases of the disease.

Cell-Type Targeted NF-kappaB Inhibition for the Treatment of Inflammatory Diseases.

Deregulated NF-k activation is not only involved in cancer but also contributes to the pathogenesis of chronic inflammatory diseases like rheumatoid arthritis (RA) and multiple sclerosis (MS). Ideally, therapeutic NF-KappaB inhibition should only take place in those cell types that are involved in disease pathogenesis to maintain physiological cell functions in all other cells. In contrast, unselective NF-kappaB inhibition in all cells results in multiple adverse effects, a major hindrance in drug development. Hitherto, various substances exist to inhibit different steps of NF-kappaB signaling. However, powerful tools for cell-type specific NF-kappaB inhibition are not yet established. Here, we review the role of NF-kappaB in inflammatory diseases, current strategies for drug delivery and NF-kappaB inhibition and point out the "sneaking ligand" approach. Sneaking ligand fusion proteins (SLFPs) are recombinant proteins with modular architecture consisting of three domains. The prototype SLC1 binds specifically to the activated endothelium and blocks canonical NF-kappaB activation. In vivo, SLC1 attenuated clinical and histological signs of experimental arthritides. The SLFP architecture allows an easy exchange of binding and effector domains and represents an attractive approach to study disease-relevant biological targets in a broad range of diseases. In vivo, SLFP treatment might increase therapeutic efficacy while minimizing adverse effects.