Publications by authors named "Maarten Kraan"

Background: There is no effective treatment for sepsis-associated acute kidney injury (SA-AKI). Ilofotase alfa (human recombinant alkaline phosphatase) has been shown to exert reno-protective properties, although it remains unclear which patients might be most likely to benefit. We aimed to identify a clinical phenotype associated with ilofotase alfa's therapeutic efficacy.

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Human rhinovirus (RV) infections are a significant risk factor for exacerbations of asthma and chronic obstructive pulmonary disease. Thus, approaches to prevent RV infection in such patients would give significant benefit. Through RNA interference library screening, we identified lanosterol synthase (LSS), a component of the cholesterol biosynthetic pathway, as a novel regulator of RV replication in primary normal human bronchial epithelial cells.

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A substantial proportion of rheumatoid arthritis (RA)-patients experience an insufficient response to glucocorticoids, an important therapeutic agent in RA. The multidrug-resistance 1 (MDR1) gene product P-glycoprotein (P-gp) is an efflux pump that actively transports substrates, such as glucocorticoids, out of the cell. We investigated if the variation in response might be explained by single-nucleotide polymorphisms (SNPs) in the MDR1 gene.

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Background: Many patients with asthma have a T-helper type 2 (Th2) driven inflammation of the lung, whereas toll-like receptor 7 (TLR7) agonists, by inducing type I interferons, inhibit Th2 responses. In man, oral or parenteral TLR7 agonists can induce influenza-like symptoms through systemic induction of type I interferons. Design of a TLR7 agonist that is only active in the lung could reduce the risk of side effects and offer a new means for treating asthma.

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Introduction: Psoriatic arthritis (PsA) is an inflammatory joint disease associated with psoriasis. Alefacept (a lymphocyte function-associated antigen (LFA)-3 Ig fusion protein that binds to CD2 and functions as an antagonist to T-cell activation) has been shown to result in improvement in psoriasis but has limited effectiveness in PsA. Interleukin-20 (IL-20) is a key proinflammatory cytokine involved in the pathogenesis of psoriasis.

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Objective: C-C chemokine receptor type 5 (CCR5), a chemokine receptor expressed on T cells and macrophages, and its ligands are found in inflamed synovial tissue (ST) of patients with rheumatoid arthritis (RA). The rationale for testing CCR5 blockade in patients with RA was supported by the effects of a CCR5 antagonist in collagen-induced arthritis in rhesus monkeys. The effects of CCR5 blockade in patients with active RA were explored.

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In psoriasis, leukocytes that infiltrate skin lesions have been shown to be involved in the pathogenesis of this disease. Previous investigations reporting the presence of CXCR3(+) T lymphocytes in psoriatic lesional skin have suggested a role of this receptor in the recruitment of T cells into the lesion. The purpose of this study was to quantify the mRNA levels of CXCR3 and to perform a systematic analysis of the cell populations that express CXCR3 in human lesional and non-lesional psoriatic biopsies.

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Objective: To determine whether multidrug-resistance efflux transporters are expressed on immune effector cells in synovial tissue from patients with rheumatoid arthritis (RA) and compromise the efficacy of methotrexate (MTX) and leflunomide (LEF).

Methods: Synovial tissue biopsy samples obtained from RA patients before treatment and 4 months after starting treatment with MTX (n = 17) or LEF (n = 13) were examined by immunohistochemical staining and digital image analysis for the expression of the drug efflux transporters P-glycoprotein, multidrug resistance-associated protein 1 (MRP-1) through MRP-5, MRP-8, MRP-9, and breast cancer resistance protein (BCRP), and the relationship to clinical efficacy of MTX and LEF was assessed.

Results: BCRP expression was observed in all RA synovial biopsy samples, both pretreatment and posttreatment, but not in control noninflammatory synovial tissue samples from orthopedic patients.

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Objective: To determine the expression of folate receptor beta (FRbeta) in synovial biopsy tissues and peripheral blood lymphocytes from rheumatoid arthritis (RA) patients and to identify novel folate antagonists that are more selective in the targeting and internalization of FRbeta than methotrexate (MTX).

Methods: Immunohistochemistry and computer-assisted digital imaging analyses were used for the detection of FRbeta protein expression on immunocompetent cells in synovial biopsy samples from RA patients with active disease and in noninflammatory control synovial tissues. FRbeta messenger RNA (mRNA) levels were determined by reverse transcription-polymerase chain reaction analysis.

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Quantitative image analysis is a form of imaging that includes microscopic histological quantification, video microscopy, image analysis, and image processing. Hallmarks are the generation of reliable, reproducible, and efficient measurements via strict calibration and step-by-step control of the acquisition, storage and evaluation of images with dedicated hardware and software. Major advantages of quantitative image analysis over traditional techniques include sophisticated calibration systems, interaction, speed, and control of inter- and intraobserver variation.

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Several reports have indicated that the chemokine receptor CCR5 and its ligands, especially CCL5 (formerly known as RANTES), may play a role in the pathogenesis of psoriasis. The purpose of this investigation was to examine the expression of CCR5 and its ligands in chronic plaque psoriasis and to evaluate the clinical and immunohistochemical effect of a CCR5 receptor inhibitor. Immunohistochemical analysis showed low but significant increased total numbers of CCR5 positive cells in epidermis and dermis of lesional skin in comparison to non-lesional skin.

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Objectives: To evaluate inter-observer agreement for microscopic measurement of inflammation in synovial tissue using manual quantitative, semiquantitative and computerised digital image analysis.

Methods: Paired serial sections of synovial tissue, obtained at arthroscopic biopsy of the knee from patients with rheumatoid arthritis (RA), were stained immunohistochemically for T lymphocyte (CD3) and macrophage (CD68) markers. Manual quantitative and semiquantitative scores for sub-lining layer CD3+ and CD68+ cell infiltration were independently derived in 6 international centres.

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Rheumatoid arthritis (RA) is a chronic, immune-mediated inflammatory disease characterised by inflammation resulting in structural joint damage and functional disability. Tumour necrosis factor-alpha (TNFalpha) is a pivotal mediator and driver of inflammation in RA. Inflammation is closely related to the production of C-reactive protein (CRP), and a close correlation exists between serum CRP and TNFalpha levels.

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Traditionally the evaluation of the cellular infiltrate and protein expression in skin tissue sections is done by manual quantification. However, for reliable evaluation of histology in the development of new anti-psoriatic treatments there is a need for a more time-efficient and reproducible method. To test the use of digital image analysis (DIA) in this situation we compared the assessment of immunohistochemically stained skin sections with the more traditional manual quantification (MQ) and semi-quantitative analysis (SQA).

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Synovial fluid from patients with various arthritides contains procoagulant, cell-derived microparticles. Here we studied whether synovial microparticles modulate the release of chemokines and cytokines by fibroblast-like synoviocytes (FLS). Microparticles, isolated from the synovial fluid of rheumatoid arthritis (RA) and arthritis control (AC) patients (n = 8 and n = 3, respectively), were identified and quantified by flow cytometry.

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Objective: EMR2 and CD97 are closely related members of the epidermal growth factor (EGF)-TM7 family of adhesion class 7-span transmembrane (TM7) receptors. Chondroitin sulfates (CS) have recently been identified as ligands for EMR2 and CD97. CS have been implicated in the pathogenesis of rheumatoid arthritis (RA).

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Objective: To create greater understanding of the changes in synovial tissue parameters that occur in conjunction with clinical response by using an effective therapy, in order to facilitate the planning of future studies with therapeutic agents for rheumatoid arthritis (RA).

Methods: Twenty-one patients with active RA were randomized to receive either oral prednisolone (n = 10) or placebo (n = 11) for 2 weeks. In all patients, synovial tissue biopsy specimens were obtained by arthroscopy directly before treatment and after 14 days of treatment.

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Objective: Antibodies directed toward citrullinated proteins (e.g., anti-cyclic citrullinated peptide antibodies) are highly specific for rheumatoid arthritis (RA) and are produced locally at the site of inflammation.

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Psoriasis and psoriatic arthritis are inflammatory diseases that respond well to anti-tumour necrosis factor-alpha therapy. To evaluate the effects of anti-tumour necrosis factor-alpha treatment on expression of adhesion molecules and angiogenesis in psoriatic lesional skin and synovial tissue, we performed a prospective single-centre study with infliximab therapy combined with stable methotrexate therapy. Eleven patients with both active psoriasis and psoriatic arthritis received infusions of infliximab (3 mg/kg) at baseline, and at weeks 2, 6, 14 and 22 in an open-label study.

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Alefacept, a LFA-3/IgG1 fusion protein, interferes with the activation and proliferation of T cells by binding to the CD2 receptor on their surfaces. The clinical efficacy of this drug has been demonstrated in chronic plaque psoriasis. We performed a single-center, open-label study to investigate the immunohistochemical effects in psoriatic lesional skin.

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This report presents a case of community-acquired pneumonia due to Chlamydia psittaci presenting with a lobar infiltrate and diagnosed by a newly developed ompA gene-based polymerase chain reaction (PCR). This gene encodes a specific C. psittaci major outer membrane protein.

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Objective: To determine whether treatment with the chimeric anti-tumor necrosis factor alpha antibody infliximab could reduce cellularity by the induction of apoptosis in synovial tissue.

Methods: Twenty-four rheumatoid arthritis patients with active disease were randomized to receive either infliximab (3 mg/kg) (n = 12) or placebo (n = 12) intravenously. All patients were subjected to arthroscopic synovial biopsy directly before initiation of treatment.

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Objective: To generate a molecular description of synovial tissue from rheumatoid arthritis (RA) patients that would allow us to unravel novel aspects of pathogenesis and to identify different forms of disease.

Methods: We applied complementary DNA microarray analysis to profile gene expression, with a focus on immune-related genes, in affected joint tissues from RA patients and in tissues from osteoarthritis (OA) patients as a control. To validate microarray data, real-time polymerase chain reaction was performed on genes of interest.

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Objective: To determine the cellular origin of synovial microparticles, their procoagulant properties, and their relationship to local hypercoagulation.

Methods: Microparticles in synovial fluid and plasma from patients with rheumatoid arthritis (RA; n = 10) and patients with other forms of arthritis (non-RA; n = 10) and in plasma from healthy subjects (n = 20) were isolated by centrifugation. Microparticles were identified by flow cytometry.

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