Rheumatoid arthritis (RA) synovitis is dominated by monocytes/macrophages with inflammatory patterns resembling microbial stimulation. In search of triggers, we reduced the intestinal microbiome in 20 RA patients (open label study DRKS00014097) by bowel cleansing and 7-day fasting (≤250 kcal/day) and performed immune monitoring and microbiome sequencing. Patients with metabolic syndrome (n = 10) served as a non-inflammatory control group. Scores of disease activity (DAS28/SDAI) declined within a few days and were improved in 19 of 20 RA patients after breaking the fast (median ∆DAS28 = −1.23; ∆SDAI = −43%) or even achieved remission (DAS28 < 2.6/n = 6; SDAI < 3.3/n = 3). Cytometric profiling with 46 different surface markers revealed the most pronounced phenomenon in RA to be an initially increased monocyte turnover, which improved within a few days after microbiota reduction and fasting. Serum levels of IL-6 and zonulin, an indicator of mucosal barrier disruption, decreased significantly. Endogenous cortisol levels increased during fasting but were insufficient to explain the marked improvement. Sequencing of the intestinal microbiota indicated that fasting reduced potentially arthritogenic bacteria and changed the microbial composition to species with broader metabolic capabilities. More eukaryotic, predominantly fungal colonizers were observed in RA, suggesting possible involvement. This study demonstrates a direct link between the intestinal microbiota and RA-specific inflammation that could be etiologically relevant and would support targeted nutritional interventions against gut dysbiosis as a causal therapeutic approach.

In rheumatoid arthritis (RA), the expression of many pro-destructive/pro-inflammatory proteins depends on the transcription factor AP-1. Therefore, our aim was to analyze the presence and functional relevance of mutations in the coding regions of the AP-1 subunits of the fos and jun family in peripheral blood (PB) and synovial membranes (SM) of RA and osteoarthritis patients (OA, disease control), as well as normal controls (NC). Using the non-isotopic RNAse cleavage assay, one known polymorphism (T252C: silent; rs1046117; present in RA, OA, and NC) and three novel germline mutations of the cfos gene were detected: (i) C361G/A367G: Gln121Glu/Ile123Val, denoted as “fos121/123”; present only in one OA sample; (ii) G374A: Arg125Lys, “fos125”; and (iii) C217A/G374A: Leu73Met/Arg125Lys, “fos73/125”, the latter two exclusively present in RA. In addition, three novel somatic cjun mutations (604–606ΔCAG: ΔGln202, “jun202”; C706T: Pro236Ser, “jun236”; G750A: silent) were found exclusively in the RA SM. Tansgenic expression of fos125 and fos73/125 mutants in NIH-3T3 cells induced an activation of reporter constructs containing either the MMP-1 (matrix metalloproteinase) promoter (3- and 4-fold, respectively) or a pentameric AP-1 site (approximately 5-fold). Combined expression of these two cfos mutants with cjun wildtype or mutants (jun202, jun236) further enhanced reporter expression of the pentameric AP-1 construct. Finally, genotyping for the novel functionally relevant germline mutations in 298 RA, 288 OA, and 484 NC samples revealed no association with RA. Thus, functional cfos/cjun mutants may contribute to local joint inflammation/destruction in selected patients with RA by altering the transactivation capacity of AP-1 complexes.

Idiopathic inflammatory myopathies (IIM) are a group of inflammatory muscle diseases in which biomarkers play an essential role in diagnosing the disease, evaluating its course and prognosis and stratifying each patient for disease-specific risks. In this context, biomarkers may be conventional serologic markers such as muscle enzymes or autoantibodies, specific inflammatory patterns in histology or genomic/genetic markers.

ZusammenfassungDie idiopathischen inflammatorischen Myopathien (IIM) sind eine Gruppe entzündlicher Muskelerkrankungen für deren Diagnosestellung, Verlaufsbeurteilung, Prognoseabschätzung und Risikostratifizierung Biomarker eine jeweils essentielle Rolle spielen. Biomarker in diesem Kontext können sowohl „herkömmliche“ serologische Marker wie Muskelenzyme oder Autoantikörper, histologische Marker wie entitätsspezifische inflammatorische Muster, aber auch genomische und genetische Marker sein. Der vorliegende Artikel gibt einen Überblick über bewährte und innovative Marker.

Advances in microbiome research suggest involvement in chronic inflammatory diseases such as rheumatoid arthritis (RA). Searching for initial trigger(s) in RA, we compared transcriptome profiles of highly inflamed RA synovial tissue (RA-ST) and osteoarthritis (OA)-ST with 182 selected reference transcriptomes of defined cell types and their activation by exogenous (microbial) and endogenous inflammatory stimuli. Screening for dominant changes in RA-ST demonstrated activation of monocytes/macrophages with gene-patterns induced by bacterial and fungal triggers. Gene-patterns of activated B- or T-cells in RA-ST reflected a response to activated monocytes/macrophages rather than inducing their activation. In contrast, OA-ST was dominated by gene-patterns of non-activated macrophages and fibroblasts. The difference between RA and OA was more prominent in transcripts of secreted proteins and was confirmed by protein quantification in synovial fluid (SF) and serum. In total, 24 proteins of activated cells were confirmed in RA-SF compared to OA-SF and some like CXCL13, CCL18, S100A8/A9, sCD14, LBP reflected this increase even in RA serum. Consequently, pathogen-like response patterns in RA suggest that direct microbial influences exist. This challenges the current concept of autoimmunity and immunosuppressive treatment and advocates new diagnostic and therapeutic strategies that consider microbial persistence as important trigger(s) in the etiopathogenesis of RA.

Idiopathic inflammatory myopathies represent still a diagnostic and therapeutic challenge in different disciplines including neurology, rheumatology, and dermatology. In recent years, the spectrum of idiopathic inflammatory myopathies has been significantly extended and the different manifestations were described in more detail leading to new classification criteria. A major breakthrough has also occurred with respect to new biomarkers especially with the characterization of new autoantibody-antigen systems, which can be separated in myositis specific antibodies and myositis associated antibodies. These markers are detectable in approximately 80% of patients and facilitate not only the diagnostic procedures, but provide also important information on stratification of patients with respect to organ involvement, risk of cancer and overall prognosis of disease. Therefore, it is not only of importance to know the significance of these markers and to be familiar with the optimal diagnostic tests, but also with potential limitations in detection. This article focuses mainly on antibodies which are specific for myositis providing an overview on the targeted antigens, the available detection procedures and clinical association. As major tasks for the near future, the need of an international standardization is discussed for detection methods of autoantibodies in idiopathic inflammatory myopathies. Furthermore, additional investigations are required to improve stratification of patients with idiopathic inflammatory myopathies according to their antibody profile with respect to response to different treatment options.

BACKGROUND:An acquired deficiency of interleukin-2 (IL-2) and related defects in regulatory T cell homeostasis are thought to play a crucial role in the pathogenesis of systemic lupus erythematosus. We hypothesised that reconstitution of regulatory T-cell homoeostasis with low doses of IL-2 would be beneficial to patients with systemic lupus erythematosus. METHODS:In this uncontrolled, phase 1 and 2a trial done in the Department of Rheumatology and Clinical Immunology at Charité-University Medicine Berlin (Berlin, Germany), we assessed the safety and tolerability of low-dose recombinant human IL-2 (aldesleukin) and its effects on regulatory T cells. We recruited patients aged 18-75 years with a confirmed diagnosis of systemic lupus erythematosus and moderate-to-severe disease activity despite previous treatment with at least two conventional therapies. Patients were given four cycles of low-dose aldesleukin daily for 5 days followed by a 9-16 day rest. The primary endpoints were safety and the number of patients who achieved at least a 100% increase in the proportion of CD25hi-expressing cells among circulating CD3 + CD4 + FOXP3 + CD127lo regulatory T cells at day 62 (ie, after four treatment cycles). Secondary endpoints included disease activity as measured by the Safety of Estrogens in Lupus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) and the British Isles Lupus Assessment Group (BILAG) score, disease flares as measured by the SLEDAI flare index, auto-antibody and complement concentrations at day 62. Exploratory endpoints included various cellular and immunological parameters. The trial is registered with WHO/ICTRP, number DRKS00004858. FINDINGS:Between March 31, 2014, and May 27, 2016, 13 patients were screened, of whom ten met eligibility criteria and were enrolled in the trial. Two additional patients were treated between April 1, 2013, and March 11, 2014, in a compassionate use setting. Eleven (92%) of the 12 patients achieved the primary endpoint. 159 adverse events were recorded, 75 (47%) of which were treatment related. Most treatment-related adverse events were transient and mild to moderate (grade 1-2). The most common adverse event was injection-site reaction (20%). No serious adverse events occurred during the treatment period. In ten (83%) of 12 patients, SELENA-SLEDAI scores were lower at day 62 than at baseline, and no severe disease flares were observed during the treatment period. Decreased disease activity correlated with the magnitude of increase in the proportion of activated regulatory T cells. IL-2 treatment resulted in a preferential proliferation of regulatory T cells that retained suppressive capacity. We observed decreases in cells that are involved in the regulation of germinal-centre reactions. INTERPRETATION:Low-dose IL-2 therapy is safe and well tolerated and selectively promotes the expansion of functional regulatory T cells in patients with moderate-to-severe systemic lupus erythematosus. Low-dose IL-2 treatment might also be beneficial in reducing disease activity, although larger trials are needed to address efficacy. FUNDING:German Research Foundation.

Big Data wird mit der Vision verknüpft, aus unüberschaubaren Datenmengen durch computerbasierte Analysemethoden neue Erkenntnisse zu gewinnen. Welche Analysekonzepte stehen hinter dieser Big-Data-Diskussion? Im Grunde sind mit dem Einsatz von Hochdurchsatztechnologien in der molekularen Forschung in der Rheumatologie schon seit ca. 15 Jahren Big Data vorhanden und Analysen in Entwicklung bzw. im Gebrauch. Hierzu gehören insbesondere die Omics-Technologien, wie z. B. Genomics, Transcriptomics oder Cytomics. Einige Basismethoden der Datenanalyse werden mit der Technologie geliefert. Dagegen müssen für die funktionelle Auswertung und Interpretation Softwarelösungen entwickelt bzw. an die Fragestellungen angepasst werden. Dabei sind die Strukturierung und Auswertung nach biologischen Zusammenhängen enorm wichtig und kein alleiniges mathematisches Problem. Dieser Aspekt muss bei molekularen Big Data noch weit mehr berücksichtigt werden als z. B. bei Big Data aus Gesundheitsökonomie und Epidemiologie. Molekulare Daten sind durch die Technologie der Erhebung in sich strukturiert und folgen in ihrer quantitativen Ausprägung biologischen Gesetzmäßigkeiten. Diese Zusammenhänge müssen in Softwarelösungen abgebildet werden, zum Teil auch durch die Vernetzung zwischen molekularen Big Data der gleichen oder auch unterschiedlichen Technologien, um technologieübergreifende Bestätigung zu erzielen. Mit immer umfangreicherer Erfassung molekularer Vorgänge in individuellen Patienten entstehen Big Data auch personenbezogen und stellen neue Anforderungen an die Bearbeitung, um datengetriebene individualisierte Lösungskonzepte zu entwickeln. Damit sind für die Umsetzung von Informationen aus Big Data im molekularen Bereich auch neue Anforderungen an Ausbildung und Berufskompetenzen zu erwarten.

Rheumatic diseases are among the most common chronic inflammatory disorders. Besides severe pain and progressive destruction of the joints, rheumatoid arthritis (RA), spondyloarthritides (SpA) and psoriatic arthritis (PsA) impair working ability, reduce quality of life and if treated insufficiently may enhance mortality. With the introduction of biologics to treat these diseases, the demand for biomarkers of early diagnosis and therapeutic stratification has been growing continuously. The main goal of the consortium ArthroMark is to identify new biomarkers and to apply modern imaging technologies for diagnosis, follow-up assessment and stratification of patients with RA, SpA and PsA. With the development of new biomarkers for these diseases, the ArthroMark project contributes to research in chronic diseases of the musculoskeletal system. The cooperation between different national centers will utilize site-specific resources, such as biobanks and clinical studies for sharing and gainful networking of individual core areas in biomarker analysis. Joint data management and harmonization of data assessment as well as best practice characterization of patients with new imaging technologies will optimize quality of marker validation.

Familial Mediterranean fever (FMF) is an autosomal recessive disease characterized by recurrent, acute, and self-limiting attacks of fever. Mutations in MEFV gene encoding pyrin account for FMF, but the high number of heterozygote patients with typical symptoms of the disease has driven a number of alternative aetiopathogenic hypotheses. The MEFV gene was knocked down in human myelomonocytic cells that express endogenous pyrin to identify deregulated microRNAs (miRNAs). Microarray analyses revealed 29 significantly differentially expressed miRNAs implicated in pathways associated with cellular integrity and survival. Implementation of in silico gene network prediction algorithms and bioinformatics analyses showed that miR-4520a is predicted to target genes implicated in autophagy through regulation of RHEB/mTOR signaling. Differential expression levels of RHEB were confirmed by luciferase reporter gene assays providing further evidence that is directly targeted by miR-4520a. Although the relative expression levels of miR-4520a were variable among FMF patients, the statistical expression of miR-4520a was different between FMF mutation carriers and controls (P = 0.0061), indicating an association between miR-4520a expression and MEFV mutations. Comparison between FMF patients bearing the M694V mutation, associated with severe disease, and healthy controls showed a significant increase in miR-4520a expression levels ( P = 0.00545). These data suggest that RHEB, the main activator of mTOR signaling, is a valid target of miR-4520a with the relative expression levels of the latter being significantly deregulated in FMF patients and highly dependent on the presence of pyrin mutations, especially of the M694V type. These results suggest a role of deregulated autophagy in the pathogenesis of FMF.(C) 2016 Wiley Periodicals, Inc.

The abundance and activation of macrophages in the inflamed synovial membrane/pannus significantly correlates with the severity of rheumatoid arthritis (RA). Although unlikely to be the ‘initiators’ of RA (if not as antigen-presenting cells in early disease), macrophages possess widespread pro-inflammatory, destructive, and remodeling capabilities that can critically contribute to acute and chronic disease. Also, activation of the monocytic lineage is not locally restricted, but extends to systemic parts of the mononuclear phagocyte system. Thus, selective counteraction of macrophage activation remains as efficacious approach to diminish local and systemic inflammation, as well as to prevent irreversible joint damage.

The multitude and abundance of macrophage-derived mediators in rheumatoid arthritis and their paracrine/autocrine effects identify macrophages as local and systemic amplifiers of disease. Although uncovering the etiology of rheumatoid arthritis remains the ultimate means to silence the pathogenetic process, efforts in understanding how activated macrophages influence disease have led to optimization strategies to selectively target macrophages by agents tailored to specific features of macrophage activation. This approach has two advantages: (a) striking the cell population that mediates/amplifies most of the irreversible tissue destruction and (b) sparing other cells that have no (or only marginal) effects on joint damage. Introduction Macrophages (Mφ) are of central importance in rheumatoid arthritis (RA) due to their prominent numbers in the inflamed synovial membrane and at the cartilage-pannus junction, their clear activation status [1,2] (see Table 1 for overview), and their response to successful anti-rheumatic treatment [3]. Although Mφ probably do not occupy a causal pathogenetic position in RA (except for their potential antigen-presenting capacity), they possess broad pro-inflammatory, destructive, and remodelling potential and contribute considerably to inflammation and joint destruction in acute and chronic RA. Also, activation of this lineage extends to circulating monocytes and other cells of the mononuclear phagocyte system (MPS), including bone marrow precursors of the myelomonocytic lineage and osteoclasts [2,4,5]. Thus, before a causal factor for RA is known, monocytes/Mφ remain an attractive research focus for the following reasons: (a) the radiological progression of joint destruction correlates with the degree of synovial Mφ infiltration [1], (b) the therapeutic efficacy of conventional anti-rheumatic therapy coincides with downregulation of MPS functions [6], (c) therapies directed at cytokines made predominantly by Mφ are effective in RA [7], (d) conventional or experimental drugs can be selectively targeted to Mφ or their different subcellular compartments (for example, [2,8]), (e) differential activation of intracellular signal transduction pathways underlies different Mφ effector functions [9], and (f) more specific inhibitors of key metabolic enzymes or particular signal transduction pathways may become available as selective targets of antirheumatic therapy [9,10]. In addition, the amplifying role of Mφ in RA has emerged so clearly that the effects of antirheumatic therapy (whether specific or conventional) on monocytes/Mφ may become an objective readout of the effectiveness of treatment [11-13] (Stuhlmuller B, Hernandez MM, Haeupl T, Kuban RJ, Gruetzkau A, Voss JW, Salfeld J, Kinne RW, Burmester GR, unpublished data). Differentiation and activation of the mononuclear phagocyte system in rheumatoid arthritis Cells of the myelomonocytic lineage differentiate into several cell types critically involved in disease (that is, monocytes/Mφ, osteoclasts, and dendritic cells) (Figure 1a). Due to their marked plasticity, these pathways can be influenced by an excess/imbalance of cytokines or growth factors, resulting in altered differentiation/maturation (Figure 1b). In RA, such imbalances clearly occur in inflamed joints, peripheral blood, and bone marrow (Table 2 and Figure 1b). Review Cells of the synovium in rheumatoid arthritis Macrophages Raimund W Kinne1, Bruno Stuhlmüller2 and Gerd-R Burmester2 1Experimental Rheumatology Unit, Department of Orthopedics, University Clinic, Jena, Klosterlausnitzer Str. 81, D-07607 Eisenberg, Germany 2Department of Rheumatology and Clinical Immunology, Charité University Hospital, Humboldt University of Berlin, Tucholskystr. 2, D-10117 Berlin, Germany Corresponding author: Raimund W Kinne, raimund.w.kinne@med.uni-jena.de Published: 21 December 2007 Arthritis Research & Therapy 2007, 9:224 (doi:10.1186/ar2333) This article is online at http://arthritis-research.com/content/9/6/224 © 2007 BioMed Central Ltd AP-1 = activator protein-1; CRP = C-reactive protein; GM-CSF = granulocyte macrophage colony-stimulating factor; IFN = interferon; IL = interleukin; IL-1RA = interleukin-1 receptor antagonist; LPS = lipopolysaccharide; Mφ = macrophage(s); MIF = migration inhibitory factor; MMP = metalloprotease; MPS = mononuclear phagocyte system; NF = nuclear factor; PPR = pattern-recognition receptor; RA = rheumatoid arthritis; ROS = reactive oxygen species; SEB = staphylococcal enterotoxin B; TGF-β = transforming growth factor-beta; TIMP = tissue inhibitor of metalloprotease; TLR = Toll-like receptor; TNF = tumor necrosis factor; TNF-R1 = tumor necrosis factor receptor 1; TNF-R2 = tumor necrosis factor receptor 2.

Die zunehmende Verfügbarkeit der Hochdurchsatz-Technologien, die exponentiell anwachsenden Informationen zum humanen Genom und der Genexpression, sowie die globale Vernetzung von Datenbanken mit strukturierten biomedizinischen Informationen wird die Betrachtungsweise entzündlich-rheumatischer Krankheitsbilder grundlegend verändern. Es stehen bereits heute in mehreren Forschungslaboren erste Datensätze zu umfangreichen Expressionsanalysen zur Verfügung. Der Umgang mit diesen Techniken lehrt, dass neben einer gewissenhaften Auswertung, Prüfung und Validierung der Ergebnisse auch auf Zellpopulationsebene eine anspruchsvolle Charakterisierung der Patienten nach besten konventionellen klinischen, labordiagnostischen, bildgebenden und insbesondere auch histologischen Methoden unabdingbar ist. Zur funktionellen Beurteilung werden invitro-Testsysteme, Tiermodelle und Medikamentenwirkungsstudien weiteren Aufschluss geben. Entwicklungsbedarf hat auch die bioinformatische Aufarbeitung der sich entwickelnden immensen Datenmengen. Das gesteckte Ziel ist, nach initialer genomweiter Betrachtung diejenigen Gene zu identifizieren, die zur Charakterisierung der Erkrankung, zur Einteilung nach molekular pathophysiologischen Gesichtspunkten, zur Beurteilung der Prognose und zur Entscheidungsfindung für das richtige therapeutische Vorgehen beitragen. Aus dem verbesserten Verständnis über die molekularen Abläufe werden sich weitere und – so die Erwartung – entscheidende Ansätze für eine effektive Therapie der chronischen Entzündung, Organ-Destruktion und pathologischen Immunantwort rheumatischer Erkrankungen ableiten lassen.

ZusammenfassungDie juvenile idiopathische Arthritis (JIA) ist eine heterogene Erkrankung, die bei Kindern und Jugendlichen auftritt und zur dauerhaften Beeinträchtigung mit großem Leidensdruck führen kann. Bisher ist über die Ätiologie und Pathogenese der JIA noch wenig bekannt und die Behandlung stellt sich schwierig dar, da sich die JIA erst im Verlauf in die verschiedenen Krankheitsformen einordnen lässt. Neben der oligoartikulären JIA gibt es Formen mit polyartikulärer Ausprägung oder systemischen Manifestationen bis hin zum Krankheitsbild mit Makrophagenaktivierungssyndrom. Dieser Artikel wird sich neben der systemischen JIA mit polygenem Erscheinungsbild auch mit den nichtsystemischen Formen der JIA mit monogenem Charakter beschäftigen und den aktuellen Kenntnisstand hinsichtlich Biomarker darstellen. Bei der JIA fehlen, genau wie bei der rheumatoiden Arthritis oder anderen Autoimmunerkrankungen, bis heute valide und kommerziell nutzbare Biomarker für die Diagnose mit schneller Subklassifizierung der Patienten, zur Prognose und Vorhersage des Ansprechens auf die Therapie, um die angestrebte patientenorientierte „individualisierte Medizin“ zu gewährleisten.

Idiopathic inflammatory myopathies (IIM) are chronic inflammatory diseases of muscle characterized by proximal muscle weakness. There are three main groups of diseases, dermatomyositis, polymyositis and inclusion body myositis. The muscle tissue is invaded by the humoral autoantibody producing immune system (B-cells) and by the cellular immune system with autoaggressive and inflammation modulating cells (e.g. dendritic cells, monocytes/macrophages, CD4 + and CD8 + T-cells and natural killer cells). The presence of specific or associated autoantibodies and inflammatory cellular infiltrates with cytotoxic and immune autoreactive properties are characteristic for IIM diseases. The pathogenesis is still unknown; nevertheless, there are several hints that exogenic factors might be involved in initiation and disease progression and bacterial, fungal and viral infections are thought to be possible initiators. Up to now information on prognostic markers to help with decision-making for individual treatment are limited. In addition, there has been only limited therapeutic success including conventional or novel drugs and biologicals and comparative validation studies are needed using similar outcome measurements. Moreover, to facilitate the use and development of novel therapies, elaboration of intracellular and cell-specific regulation could be useful to understand the etiopathogenesis and allow a better diagnosis, prognosis and possibly also a prediction for individualized subgroup treatment.

In vitro tissue models are useful tools for the development of novel therapy strategies in cartilage repair and care. The limited availability of human primary tissue and high costs of animal models hamper preclinical tests of innovative substances and techniques. In this study we tested the potential of porcine chondrocyte micromass cultures to mimic human articular cartilage and essential aspects of osteoarthritis (OA) in vitro. Primary chondrocytes were enzymatically isolated from porcine femoral condyles and were maintained in 96-multiwell format to establish micromass cultures in a high-throughput scale. Recombinant porcine tumor necrosis factor alpha (TNF-α) was used to induce OA-like changes documented on histological (Safranin O, collagen type II staining), biochemical (hydroxyproline assay, dimethylmethylene blue method), and gene expression level (Affymetrix porcine microarray, real time PCR) and were compared with published data from human articular cartilage and human micromass cultures. After 14 days in micromass culture, porcine primary chondrocytes produced ECM rich in proteoglycans and collagens. On gene expression level, significant correlations of detected genes with porcine cartilage (r = 0.90), human cartilage (r = 0.71), and human micromass culture (r = 0.75) were observed including 34 cartilage markers such as COL2A1, COMP, and aggrecan. TNF-α stimulation led to significant proteoglycan (-75%) and collagen depletion (-50%). Comparative expression pattern analysis revealed the involvement of catabolic enzymes (MMP1, -2, -13, ADAM10), chemokines (IL8, CCL2, CXCL2, CXCL12, CCXL14), and genes associated with cell death (TNFSF10, PMAIPI, AHR) and skeletal development (GPNMB, FRZB) including transcription factors (WIF1, DLX5, TWIST1) and growth factors (IGFBP1, -3, TGFB1) consistent with published data from human OA cartilage. Expression of genes related to cartilage ECM formation (COL2A1, COL9A1, COMP, aggrecan) as well as hypertrophic bone formation (COL1A1, COL10A1) was predominantly found decreased. These findings indicating significant parallels between human articular cartilage and the presented porcine micromass model and vice versa confirm the applicability of known cartilage marker and their characteristics in the porcine micromass model. TNF-α treatment enabled the initiation of typical OA reaction patterns in terms of extensive ECM loss, cell death, formation of an inflammatory environment through the induction of genes coding for chemokines and enzymes, and the modulation of genes involved in skeletal development such as growth factors, transcription factors, and cartilage ECM-forming genes. In conclusion, the porcine micromass model represents an alternative tissue platform for the evaluation of innovative substances and techniques for the treatment of OA.

Background and Objectives Rheumatoid arthritis (RA) is a chronic inflammatory disease associated with joint destruction. Joint inflammation is characterised by infiltration and activation of various immune cells. To avoid difficulties in sampling synovial tissue and to avoid fluctuation in cellular composition of leukocytes, which accompanies inflammation both in synovial tissue and blood, this study was focused on transcriptome analyses of synovial tissues, blood and bone marrow monocytes. The main aim was to analyse potential of blood monocytes in dissecting inflammation in RA and in reflecting inflammation that is evident in synovial tissue. Osteoarthritis (OA), which represents a non-inflammatory disease was used as control in this study. Materials and Methods Synovial tissues from 10 RA and 10 OA patients were used for gene-expression profiling by Affymetrix HG-U133A arrays. Blood and bone marrow monocytes, obtained from 8 RA and 8 OA patients undergoing hip replacement surgery, were utilised for gene-expression profiling by Affymetrix HG-U133Plus arrays. The BioRetis database was used for microarray analyses and generation of RA profiles. Results Transcriptome analyses of synovial tissues from RA and OA patients revealed more than 1000 differentially expressed genes. Increased expression of genes involved in chemotaxis (CCL13, CCL18, CXCL9, CXCL10, CXCL13), cell adhesion and activation (ICAM1, PECAM1, ITGAL, ITGB2, CD40, CD86) indicate to inflammation but also to infiltration of various cell types like monocytes/macrophages, NK, T- and B-cells. By comparing transcriptome of RA and OA monocytes, both from blood and bone marrow, it was obvious that monocytes were able to disclose differences between these two diseases. The RA disease-specific gene-expression profile was evident both in blood and bone marrow and it demonstrated only a minor overlap between these two bodies compartments. Altogether, a typical RA inflammatory profile disclosed in synovial tissues was greatly silenced in blood monocytes, and almost completely absent in bone marrow derived monocytes. Conclusions The RA gene-expression profile was the most specific and robust in synovial tissue, demonstrating the dominance of the inflammatory process in the joints. Nevertheless, the systemic nature of RA was also evident at the level of blood and bone marrow monocytes. Concerning that blood is a favourable and easily accessible material for diagnosis and that monocytes are able to exhibit disease-specific alterations, understanding monocyte response in different rheumatic diseases seems to be advantageous approach for biomarkers discovery. This approach should be essential for identifying the objective criteria relevant for disease and therapeutic stratification of patients with RA.

Idiopathische inflammatorische Myopathien (IIM) sind entzündliche Erkrankungen des Muskelapparates mit chronischem Verlauf und Muskelschwäche. Hierbei kommt es bei den 3 Haupterkrankungen, der Dermatomyositis, der Polymyositis und der Einschlusskörperchenmyositis, zu immunologischen Angriffsprozessen auf das Muskelgewebe durch das humorale antikörperbildende Immunsystem (B-Zellen), wie auch durch das zelluläre Immunsystem (dendritische Zellen, Monozyten/Makrophagen, CD4+- und CD8+-T-Zellen und natürliche Killerzellen). Letzteres wirkt dabei nicht nur autoaggressiv zytotoxisch, sondern unterhält auch die Entzündung. Über die Pathogenese der IIM ist bislang noch wenig bekannt. Dennoch scheinen genetische Prädispositionen und Umweltfaktoren eine unterstützende Rolle bei der Krankheitsinitiierung und im Verlauf zu spielen. Insbesondere scheinen auch Infektionen mit Pilzen, Bakterien und/oder Viren ätiologisch bedeutsam. Bis dato existieren nur wenige Merkmale zur Beurteilung der individuellen Prognose oder zur Abschätzung des therapiespezifischen Behandlungserfolgs. Konventionelle und neuere Behandlungsstrategien sind kritisch unter Berücksichtigung der Vergleichbarkeit der Studien zu bewerten. Zur Entwicklung neuer und zielgerichteter Therapien wird zunehmend die Einbeziehung von genomweiten Untersuchungsmethoden relevant, um molekulare Pathomechanismen systematisch zu erfassen und die Ätiopathogenese bei IIM besser zu verstehen. Diese Methoden wecken auch die Hoffnung, geeignete Biomarker für die Klassifikation, therapeutische Stratifizierung, Aktivitätsbestimmung, Prognose und die krankheitsspezifischen Subgruppen patientenspezifisch zu identifizieren.

Many cytokines are involved in the pathogenesis of autoimmune diseases and are recognized as relevant therapeutic targets to attenuate inflammation, such as tumor necrosis factor (TNF)-α in rheumatoid arthritis (RA) and interferon (IFN)-α/γ in systemic lupus erythematosus (SLE). To relate the transcriptional imprinting of cytokines in a cell type- and disease-specific manner, we generated gene expression profiles from peripheral monocytes of SLE and RA patients and compared them to in vitro-generated signatures induced by TNF-α, IFN-α2a, and IFN-γ. Monocytes from SLE and RA patients revealed disease-specific gene expression profiles. In vitro-generated signatures induced by IFN-α2a and IFN-γ showed similar profiles that only partially overlapped with those induced by TNF-α. Comparisons between disease-specific and in vitro-generated signatures identified cytokine-regulated genes in SLE and RA with qualitative and quantitative differences. The IFN responses in SLE and RA were found to be regulated in a STAT1-dependent and STAT1-independent manner, respectively. Similarly, genes recognized as TNF-α regulated were clearly distinguishable between RA and SLE patients. While the activity of SLE monocytes was mainly driven by IFN, the activity from RA monocytes showed a dominance of TNF-α that was characterized by STAT1 down-regulation. The responses to specific cytokines were revealed to be disease-dependent and reflected the interplay of cytokines within various inflammatory milieus. This study has demonstrated that monocytes from RA and SLE patients exhibit disease-specific gene expression profiles, which can be molecularly dissected when compared with in vitro-generated cytokine signatures. The results suggest that an assessment of cytokine-response status in monocytes may be helpful for improvement of diagnosis and selection of the best cytokine target for therapeutic intervention.