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Biomedical subjects

Ulf Müller-Ladner

Publications and source records attributed to Ulf Müller-Ladner.

At least 19 recordsLinked to original sources
PubMed2006

The potential of adiponectin in driving arthritis.

Articular adipose tissue is a ubiquitous component of human joints, but its local functions are largely unknown. Because recent studies revealed several links between adipose tissue, adipocytokines, and arthritis, we investigated the expression of the adipocytokine adiponectin and its functional role in articular adipose tissue and synovium of patients with different arthritides. In contrast to its protective role in endocrinological and vascular diseases, adiponectin was found to be involved in key pathways of inflammation and matrix degradation in the human joint. The effects of adiponectin in human synovial fibroblasts appear to be highly selective by inducing only two of the main mediators of rheumatoid arthritis pathophysiology, IL-6 and matrix metalloproteinase-1, via the p38 MAPK pathway. Owing to the observation that these effects could be inhibited by different TNF-alpha inhibitors, adipocytokines such as adiponectin may also be key targets for therapeutic strategies in inflammatory joint diseases. In summary, articular adipose tissue and adipocytokines cannot be regarded as innocent bystanders any more in chronic inflammatory diseases such as arthritis.

Adalimumab↗
PubMed2006

Three-dimensional Doppler sonographic vascular imaging in regions with increased MR enhancement in inflamed wrists of patients with rheumatoid arthritis.

OBJECTIVE: To compare three-dimensional (3D) power Doppler ultrasonography (PDUS) with contrast enhanced magnetic resonance imaging (MRI) in their capability to visualize synovial vascularity in inflamed wrists of patients with rheumatoid arthritis (RA). METHODS: Nine patients with RA showing clinically active arthritis of the wrist as determined by tenderness and swelling were examined by contrast enhanced MRI and 3D PDUS. Vascularity close to and inside the joint capsule was visualized by conventional power Doppler mode. In a region with high Doppler signal intensity (=region of interest/ROI) a 3D blood vessel tree was obtained by a free-hand sweep. 3D images were evaluated with regard to the number of blood vessels in the intra- and peri-articular region. MRI examinations were performed using a 1.5 T Scanner. In MRI, time resolved coronal contrast enhanced T1-weighted sequences with fat suppression were acquired during an 8 min period to assess tissue enhancement. Relative enhancement was calculated and compared to 3D PDUS findings. RESULTS: A 3D vascular tree consisting of peri- and intra-articular blood vessels could be demonstrated in the same anatomical ROI in which an increased gadolinium enhancement was measured by MRI in all examined RA patients. The number of penetrating vessels into the joint capsule, the number of intra-articular vessels and a semiquantitative estimation of the strength of blood flow were used to generate a 3D score for the intensity of synovial vascularity. CONCLUSION: When compared with clinical symptoms and the gold standard dynamic MRI, 3D PDUS is a reliable imaging technique for assessing synovial vascularity in inflamed wrists of RA patients.

Adult↗
PubMed2006

Different effects of adiponectin isoforms in human monocytic cells.

Adiponectin (APM) is an adipocyte-derived adipokine with immunosuppressive, antidiabetic, and antiatherosclerotic properties. Low molecular weight (LMW)- and higher molecular weight (HMW)-APM circulate in the serum and activate different signaling pathways. We were interested to see whether LMW-APM exerts different effects on monocytic cells compared with the HMW isoform. Therefore, the effects of recombinant LMW-APM produced in insect cells and the APM from higher eukaryotic cells containing HMW forms on monocytic cells were investigated with respect to apoptosis and inflammation. LMW- and HMW-APM induce apoptosis in nondifferentiated THP-1 cells, reduce macrophage scavenger receptor (MSR) A mRNA expression, and stimulate phosphorylation of adenosine monophosphate-activated protein kinase (AMPK). However, HMW-APM induces the secretion of interleukin (IL)-6 in human monocytes and THP-1 cells but does not suppress lipopolysaccharide (LPS)-induced IL-6 secretion. In contrast, LMW-APM reduces LPS-mediated IL-6 release and furthermore, stimulates IL-10 secretion, most likely by reducing the abundance of inhibitor of nuclear factor (NF)-kappaB kinase beta, leading to a diminished nuclear translocation of NF-kappaB p65. Our data indicate that the different APM isoforms do share common effects on monocytic cells but also induce isoform-specific responses. Although apoptosis, the activation of AMPK, and the reduction of MSR are mediated by all APM isoforms, only LMW-APM displays anti-inflammatory properties.

AMP-Activated Protein Kinases↗
PubMed2006

Monocyte chemoattractant protein 1 released from glycosaminoglycans mediates its profibrotic effects in systemic sclerosis via the release of interleukin-4 from T cells.

OBJECTIVE: Monocyte chemoattractant protein 1 (MCP-1; CCL2) has been implicated in the pathogenesis of fibrotic diseases and is up-regulated in patients with systemic sclerosis (SSc). The aim of the present study was to examine the mechanisms by which MCP-1 mediates its profibrotic effects in the setting of SSc. METHODS: The expression of receptors for MCP-1 on dermal fibroblasts was analyzed by real-time polymerase chain reaction and fluorescence-activated cell sorting. The ability of extracellular matrix proteins to bind and release MCP-1 was quantified by enzyme-linked immunosorbent assay. Th0 cells were isolated using a magnetic-activated cell sorting system and were stimulated twice in the presence of MCP-1. The synthesis of collagen was measured using the Sircol collagen assay kit. RESULTS: The glycosaminoglycan chondroitin sulfate, but not fibronectin or collagens, bound and released MCP-1 in a time-dependent manner. MCP-1 that was released from chondroitin sulfate induced the differentiation of interleukin-4 (IL-4)-producing T cells in a dose-dependent manner. In turn, dermal fibroblasts from patients with SSc expressed IL-4 receptor, and stimulation with IL-4 significantly increased the production of collagen in dermal fibroblasts. In contrast, CCR2a and CCR2b, as well as D6 and US28 (other potential receptors of MCP-1), were not detectable in SSc and normal fibroblasts, and their expression was not induced by platelet-derived growth factor, IL-1beta, or IL-4. In addition, MCP-1 had no direct effects on collagen production by fibroblasts. CONCLUSION: MCP-1 has no direct effects on dermal fibroblasts but contributes to fibrosis in patients with SSc by inducing the differentiation of IL-4-producing T cells. Because MCP-1 has both proinflammatory and profibrotic effects, pharmacologic targeting of MCP-1 could be a promising therapeutic approach in SSc.

Adolescent↗
PubMed2006

Anti-Jo-1 antibody positive polymyositis--successful therapy with leflunomide.

Idiopathic inflammatory myopathies (IM), including dermatomyositis (DM) and polymyositis (PM), are a group of systemic rheumatologic diseases of unknown etiology characterized by chronic myositis. Antisynthetase antibodies such as the anti-Jo-1 antibody are known to be highly specific for inflammatory myopathies. Patients with this antibody frequently show a combination of symptoms including interstitial lung disease, fever, polyarthritis, myositis, Raynaud's phenomenon and "mechanic's hands". In the management of PM with anti-Jo-1 antibody, immunosuppressive agents are used to control the disease. Leflunomide is a new immunosuppressive drug recently introduced in the treatment of rheumatoid and psoriatic arthritis. Here, we report two cases of female patients with PM and anti-Jo-1 antibodies, who were successfully treated with leflunomide.

Antibodies, Antinuclear↗
PubMed2006

Profiling adipocytokine secretion from creeping fat in Crohn's disease.

BACKGROUND: Adipose tissue is recognized as a compartment secreting highly active molecules. Creeping fat represents a characteristic feature of Crohn's disease (CD). Proinflammatory or anti-inflammatory adipose-derived secretory products, now generally called adipocytokines, may play a role in the pathogenesis of CD. MATERIALS AND METHODS: Adipose tissue specimens were obtained from creeping fat contiguous to the involved intestine of 10 patients with CD. Mesenteric adipose tissue specimens resected from 13 patients with colon cancer (CC) and from 7 patients with diverticulitis served as controls. Three fat tissue specimen per well and 6 to 8 wells per patient were incubated ex vivo for 24 h. The release of adiponectin, resistin, leptin, interleukin-6, macrophage colony-stimulating factor, monocyte chemotactic protein-1, and migration inhibitory factor was measured by ELISA. The expression of AdipoR1 and AdipoR2 receptors was investigated by real-time quantitative polymerase chain reaction in a subset of adipose tissues. RESULTS: The secretion of adiponectin and macrophage colony-stimulating factor, as well as leptin and migration inhibitory factor, was significantly upregulated in CD compared with CC and diverticulitis or CC only, respectively. Resistin, interleukin-6, and monocyte chemotactic protein-1 were not specifically induced in CD but were associated with unspecific inflammation. Adiponectin receptor expression was not different in CC, CD, or diverticulitis. Steroid treatment in CD patients had differential effects on the ex vivo secretion of adipocytokines. CONCLUSIONS: A specific secretion pattern of proinflammatory and anti-inflammatory adipocytokines indicates the significance of adipose tissue in intestinal inflammation in CD. Future investigations of this intestinal compartment may provide novel insights into the pathophysiological role of creeping fat and CD.

Adipose Tissue↗
PubMed2006

Fibroblast activation protein is expressed by rheumatoid myofibroblast-like synoviocytes.

Fibroblast activation protein (FAP), as described so far, is a type II cell surface serine protease expressed by fibroblastic cells in areas of active tissue remodelling such as tumour stroma or healing wounds. We investigated the expression of FAP by fibroblast-like synoviocytes (FLSs) and compared the synovial expression pattern in rheumatoid arthritis (RA) and osteoarthritis (OA) patients. Synovial tissue from diseased joints of 20 patients, 10 patients with refractory RA and 10 patients with end-stage OA, was collected during routine surgery. As a result, FLSs from intensively inflamed synovial tissues of refractory RA expressed FAP at high density. Moreover, FAP expression was co-localised with matrix metalloproteinases (MMP-1 and MMP-13) and CD44 splice variants v3 and v7/8 known to play a major role in the concert of extracellular matrix degradation. The pattern of signals appeared to constitute a characteristic feature of FLSs involved in rheumatoid arthritic joint-destructive processes. These FAP-expressing FLSs with a phenotype of smooth muscle actin-positive myofibroblasts were located in the lining layer of the synovium and differ distinctly from Thy-1-expressing and non-proliferating fibroblasts of the articular matrix. The intensity of FAP-specific staining in synovial tissue from patients with RA was found to be different when compared with end-stage OA. Because expression of FAP by RA FLSs has not been described before, the findings of this study highlight a novel element in cartilage and bone destruction of arthritic joints. Moreover, the specific expression pattern qualifies FAP as a therapeutic target for inhibiting the destructive potential of fibroblast-like synovial cells.

Antigens, Neoplasm↗
PubMed2006

Impact of thiopurine methyltransferase activity and 6-thioguanine nucleotide concentrations in patients with chronic inflammatory diseases.

As azathioprine is one of the standard immunosuppressive drugs used for treatment of patients with different chronic inflammatory diseases, the effect of the azathioprine metabolizing enzyme thiopurine methyltransferase (TPMT) activity on incidence of adverse events (AE) was examined. In addition, potential correlations between the concentration of the azathioprine metabolite 6-thioguanine nucleotide (6-TGN) in erythrocytes (RBC) and inflammatory disease activity as well as hematological AE were investigated. TPMT activities were investigated prospectively in 139 patients (35 male, 104 female) with chronic inflammatory diseases [systemic lupus erythematosus (SLE, 38), progressive systemic sclerosis (PSS, 13), Wegener's granulomatosis (4), rheumatoid arthritis (RA, 5), and other chronic inflammatory diseases (79)]. In addition, 6-TGN concentrations were investigated in a second cohort of 58 patients (17 patients with SLE, 5 with PSS, 5 with vasculitides, 4 with undifferentiated connective tissue diseases, 1 with dermatomyositis, 1 with Sjögren's syndrome, 1 with RA, 20 with Crohn's disease, and 4 with ulcerative colitis) prior to and during therapy with azathioprine. The distribution of activities of TPMT in 139 patients showed a normal Gaussian distribution in the Caucasian population. Within the group of 96 patients taking azathioprine, known azathioprine-related AE could be observed: minor AE (sickness, rash, and increase in cholestasis parameters) in 11 patients (11.4%), and severe AE (bone marrow toxicity) in 7 patients (7.3%). Below a "cutoff" value of 11.9 nmol/mL RBC x h of TPMT activity, AE were significantly more frequent. In the second cohort of patients, no significant correlations could be observed between 6-TGN concentrations and parameters of disease activity. Reduced activity of TPMT in patients with chronic inflammatory diseases requiring immunosuppressive therapy with azathioprine, especially below a distinct cutoff, appears to inherit a substantial risk for development of AE.

Adult↗
PubMed2005

Developing the concept of adoptive cellular gene therapy of rheumatoid arthritis.

Progressive destruction of articular cartilage and bone is the pivotal problem of rheumatoid arthritis (RA). Joint destruction is the cause of severe disability and determines the long-term outcome of disease. Conventional therapy does not control this destructive process sufficiently and the anti-rheumatic drugs available today can cause severe systemic adverse effects. Local application of chondroprotective and osteoprotective agents by means of gene therapy would be an attractive alternative to conventional therapy of RA and could provide long-term expression of the therapeutic agents and minimize systemic adverse effects. For this purpose, we have developed the concept of adoptive cellular gene therapy. This treatment strategy is based on using genetically engineered cells that home specifically to sites of autoimmune inflammation and thus allow local delivery of therapeutic gene products. Ex vivo transduction of these cells avoids systemic exposure of the host to the transgene-encoding vector and thus adds to the safety of this approach. In this article of the CIS Spring School in Autoimmune Diseases 2005 proceedings, we review our work on developing the strategy of adoptive cellular gene therapy and summarize recent advances in the evaluation of therapeutic effects and the identification of novel therapeutic targets.

Adoptive Transfer↗
PubMed2005

[Advances in basic-science rheumatology research 2004/2005].

Major advances in basic-science rheumatology research have been achieved in various fields including molecular techniques, signaling pathways, experimental strategies, and in several bench-to-bedside approaches. Using laser-mediated microdissection, small areas of interest in a given diseased tissue can be analyzed in a high-resolution setting. Molecular imaging, especially the combination of labeled molecules such as albumin that are metabolized by active cells together with smart probes, can be used to visualize key mechanisms in rheumatoid synovial tissue in a real-time setting. Recently discovered microparticles and Toll-like receptors have been found to be dominant players in innate immunity-driven inflammation and destruction in the rheumatoid joint. Moreover, long-lived plasma cells appear to be a major factor in resistance to immunosuppressive drugs in autoimmune disease. With regard to bench-to-bedside strategies, various targeted therapies including various gene transfer strategies yielded promising preclinical results.

Biomedical Research↗
PubMed2005

[Acute coronary syndrome in a 17-year-old female with systemic lupus erythematosus].

CASE REPORT: A 17-year-old female was admitted to the hospital with epigastric pain radiating into the chest and neck. The patient had a known, long-standing history of systemic lupus erythematosus (SLE) with predominantly renal involvement. Diagnostic examinations including left heart catheterization showed acute myocardial infarction based on a coronary three-vessel disease. Percutaneous transluminal coronary angioplasty (PTCA) with dilatation of the left marginal branch and the left posterolateral branch was performed. 8 weeks after PTCA, the patient was admitted again showing occlusion of the same coronary artery. A coronary stent was implanted which, after 8 weeks, also showed signs of occlusion. This case report describes premature myocardial infarction in a young woman with SLE and addresses and discusses the problem that myocardial infarction in SLE can be caused by atherosclerosis and/or arteritis of the coronary arteries.

Adolescent↗
PubMed2005

Expression of interleukin-21 receptor in epidermis from patients with systemic sclerosis.

OBJECTIVE: To examine the expression and regulation of interleukin-21 (IL-21) and IL-21 receptor (IL-21R) in patients with systemic sclerosis (SSc; scleroderma). METHODS: Skin biopsy specimens were obtained from 23 patients with SSc and 15 healthy controls. IL-21/IL-21R messenger RNA (mRNA) was quantified using real-time polymerase chain reaction (PCR). The expression pattern of IL-21/IL-21R was analyzed by in situ hybridization and Western blotting. Stimulation experiments were performed with cultured dermal fibroblasts from patients with SSc and healthy controls as well as with keratinocytes, using IL-1beta, platelet-derived growth factor BB, monocyte chemoattractant protein 1, transforming growth factor beta, and IL-21. The SCID-hu skin mouse model was used for in vivo experiments. RESULTS: IL-21R mRNA was detected in all biopsy specimens from patients with SSc and controls, with a 4.7-fold increase observed in SSc samples. In situ hybridization and immunohistochemical analysis showed an up-regulation of IL-21R in samples of epidermis from SSc patients, whereas no signal was detected in skin specimens from healthy controls. These results were confirmed in vitro, in that cultured keratinocytes expressed significant levels of IL-21R, whereas no signal was observed in fibroblasts. Interestingly, mRNA for IL-21 could not be detected by real-time PCR and in situ hybridization. Various concentrations of key cytokines in the pathogenesis of SSc did not stimulate the expression of IL-21R mRNA in cultured keratinocytes and dermal fibroblasts. In the SCID mouse transplantation model, the overexpression of IL-21R mRNA in SSc keratinocytes remained unchanged after transplantation. CONCLUSION: The up-regulation of IL-21R in keratinocytes indicates that, similar to fibroblasts and endothelial cells, the expression pattern is altered in SSc. Moreover, the expression of IL-21R appears to be independent of key cytokines that are operant in SSc.

Adolescent↗
PubMed2005

Retroviral gene transfer of an antisense construct against membrane type 1 matrix metalloproteinase reduces the invasiveness of rheumatoid arthritis synovial fibroblasts.

OBJECTIVE: Membrane type 1 matrix metalloproteinase (MT1-MMP) is expressed prominently in rheumatoid arthritis synovial fibroblasts (RASFs), but the specific contribution of MT1-MMP to fibroblast-mediated destruction of articular cartilage is incompletely understood. This study used gene transfer of an antisense expression construct to assess the effects of MT1-MMP inhibition on the invasiveness of RASFs. METHODS: Retroviral gene transfer of a pLXIN vector-based antisense RNA expression construct (MT1-MMPalphaS) to MT1-MMP was used to stably transduce RASFs. Levels of MT1-MMP RNA and protein were determined by quantitative polymerase chain reaction, Western blotting, and immunocytochemistry in MT1-MMPalphaS-transduced RASFs as well as in control cells, with monitoring for 60 days. The effects of MT1-MMPalphaS on the invasiveness of RASFs were analyzed in the SCID mouse co-implantation model of RA. RESULTS: MT1-MMPalphaS-transduced RASFs produced high levels of antisense RNA that exceeded endogenous levels of MT1-MMP messenger RNA by 15-fold and resulted in a down-regulation of MT1-MMP at the protein level. Inhibition of MT1-MMP production was maintained for 60 days and significantly reduced the invasiveness of RASFs in the SCID mouse model. Whereas prominent invasion into cartilage by non-transduced and mock-transduced RASFs was observed (mean invasion scores 3.0 and 3.1, respectively), MT1-MMPalphaS-transduced cells showed only moderate invasiveness (mean invasion score 1.8; P < 0.05). CONCLUSION: The data demonstrate that an antisense RNA expression construct against MT1-MMP can be generated and expressed in RASFs for at least 60 days. Inhibition of MT1-MMP significantly reduces the cartilage degradation by RASFs.

Animals↗
PubMed2005

The different stages of synovitis: acute vs chronic, early vs late and non-erosive vs erosive.

Rheumatoid arthritis is a systemic inflammatory disease that, by definition, can affect all parts of the human body, including severe complications such as uveitis/episcleritis and vasculitis of the heart, lungs, kidneys and the central and peripheral nervous systems. Its primary and by far the most common manifestations, however, affect the joints and are characterised by inflammatory reactions and activation of the synovial lining tissue and associated structures, the latter resulting in tenovaginitis and rheumatoid nodules. As all pathophysiological mechanisms are based on pathways that are inherent in the different components of a joint, it is necessary to examine the unique features of normal synovium prior to analysing disease-specific pathways. This chapter will therefore describe the physiological structure of the synovium and the inflammatory pathology of rheumatoid synovitis in early and chronic stages of the disease.

Acute Disease↗
PubMed2005

Mechanisms of disease: the molecular and cellular basis of joint destruction in rheumatoid arthritis.

Rheumatoid arthritis is a complex systemic disease that ultimately leads to the progressive destruction of articular and periarticular structures. Novel data indicate that the innate immune system (through activation of Toll-like receptors) is involved in articular pathophysiology, including the recruitment of inflammatory cells, and that periarticular factors such as adipocytokines contribute to the perpetuation of joint inflammation. The deleterious process of joint destruction is mediated by intracellular signaling pathways involving transcription factors, such as nuclear factor kappaB, cytokines, chemokines, growth factors, cellular ligands, and adhesion molecules. Advances in molecular biology techniques have identified T-cell-independent and B-cell-independent pathways that operate at different stages of the disease. Cytokine-independent pathways appear to be responsible for maintaining basic disease activity that is not affected by currently available therapies. Using this knowledge in combination with gene-transfer and gene-silencing approaches, bench-to-bedside strategies will be developed, thus enabling the creation of novel treatments for rheumatoid arthritis.

Animals↗