Can malignant and inflammatory pleural effusions in dogs be distinguished using computed tomography

Computed tomography (CT) is the primary imaging modality used to investigate human patients with suspected malignant or inflammatory pleural effusion, but there is a lack of information about the clinical use of this test in dogs. To identify CT signs that could be used to distinguish pleural malignant neoplasia from pleuritis, a retrospective case‐control study was done based on dogs that had pleural effusion, pre‐ and postcontrast thoracic CT images, and cytological or histopathological diagnosis of malignant or inflammatory pleural effusion. There were 20 dogs with malignant pleural effusion (13 mesothelioma, 6 carcinoma; 1 lymphoma), and 32 dogs with pleuritis (18 pyothorax; 14 chylothorax). Compared to dogs with pleuritis, dogs with malignant pleural effusions were significantly older (median 8.5 years vs. 4.9 years, P = 0.001), more frequently had CT signs of pleural thickening (65% vs.34%, P = 0.05), tended to have thickening of the parietal pleura only (45% vs. 3%, P = 0.002) and had more marked pleural thickening (median 3 mm vs. 0 mm, P = 0.03). Computed tomography signs of thoracic wall invasion were observed only in dogs with malignant pleural effusions (P = 0.05). There were no significant differences in pleural fluid volume, distribution or attenuation, degree of pleural contrast accumulation, amount of pannus, or prevalence of mediastinal adenopathy. Although there was considerable overlap in findings in dogs with malignant pleural effusion and pleuritis, marked thickening affecting the parietal pleural alone and signs of thoracic wall invasion on CT support diagnosis of pleural malignant neoplasia, and may help prioritize further diagnostic testing

Quantitative assessment of angiogenesis in murine antigen-induced arthritis by intravital fluorescence microscopy

Inhibition of angiogenesis might be a therapeutic approach to prevent joint destruction caused by the overgrowing synovial tissue during chronic joint inflammation. The aim of this study was to investigate angiogenesis in the knee joint of mice with antigen-induced arthritis (AIA) by means of intravital microscopy. In 14 mice (C57BL6/129Sv) intravital microscopic assessment was performed on day 8 after AIA induction in two groups (controls, AIA). Synovial tissue was investigated by intravital fluorescence microscopy using FITC-dextran (150 kD). Quantitative assessment of vessel density was performed according to the following categories: functional capillary density (FCD, vessels 10 mum) and FVD of vessels with angiogenic criteria (convoluted vessels, abrupt changes of diameter, vessels which are generated by sprouting and progressively pruned and remodelled). Microvessel count was performed using immunohistochemistry. There was no significant difference in FCD between the control group (337 +/- 9 cm/cm(2); mean +/-SEM) and the AIA group (359 +/- 13 cm/cm(2)). The density of vessels larger than 10 gm diameter was significantly increased in animals with AIA (135 +/- 10 vs. 61 +/- 5 cm/cm(2) in control). The density of blood vessels with angiogenic criteria was enhanced in arthritic animals (79 +/- 17 vs. 12 +/- 2 cm/cm(2) in control). There was a significant increase in the microvessel count in arthritic animals (297 +/- 25 vs. 133 +/- 16 mm(-2) in control). These findings demonstrate that angiogenesis in murine AIA can be assessed quantitatively using intravital microscopy. Further studies will address antiangiogenic strategies in AIA

Myeloid DAP12-associating lectin (MDL)-1 regulates synovial inflammation and bone erosion associated with autoimmune arthritis.

DNAX adaptor protein 12 (DAP12) is a trans-membrane adaptor molecule that transduces activating signals in NK and myeloid cells. Absence of functional Dap12 results in osteoclast defects and bone abnormalities. Because DAP12 has no extracelluar binding domains, it must pair with cell surface receptors for signal transduction. There are at least 15 known DAP12-associating cell surface receptors with distinct temporal and cell type-specific expression patterns. Our aim was to determine which receptors may be important in DAP12-associated bone pathologies. Here, we identify myeloid DAP12-associating lectin (MDL)-1 receptor (also known as CLEC5A) as a key regulator of synovial injury and bone erosion during autoimmune joint inflammation. Activation of MDL-1 leads to enhanced recruitment of inflammatory macrophages and neutrophils to the joint and promotes bone erosion. Functional blockade of MDL-1 receptor via Mdl1 deletion or treatment with MDL-1-Ig fusion protein reduces the clinical signs of autoimmune joint inflammation. These findings suggest that MDL-1 receptor may be a therapeutic target for treatment of immune-mediated skeletal disorders

Effect of a small molecule inhibitor of nuclear factor-κB nuclear translocation in a murine model of arthritis and cultured human synovial cells

A small cell-permeable compound, dehydroxymethylepoxyquinomicin (DHMEQ), does not inhibit phosphorylation and degradation of IκB (inhibitor of nuclear factor-κB [NF-κB]) but selectively inhibits nuclear translocation of activated NF-κB. This study aimed to demonstrate the antiarthritic effect of this novel inhibitor of the NF-κB pathway in vivo in a murine arthritis model and in vitro in human synovial cells. Collagen-induced arthritis was induced in mice, and after onset of arthritis the mice were treated with DHMEQ (5 mg/kg body weight per day). Using fibroblast-like synoviocyte (FLS) cell lines established from patients with rheumatoid arthritis (RA), NF-κB activity was examined by electrophoretic mobility shift assays. The expression of molecules involved in RA pathogenesis was determined by RT-PCR, ELISA, and flow cytometry. The proliferative activity of the cells was estimated with tritiated thymidine incorporation. After 14 days of treatment with DHMEQ, mice with collagen-induced arthritis exhibited decreased severity of arthritis, based on the degree of paw swelling, the number of swollen joints, and radiographic and histopathologic scores, compared with the control mice treated with vehicle alone. In RA FLS stimulated with tumor necrosis factor-α, activities of NF-κB components p65 and p50 were inhibited by DHMEQ, leading to suppressed expression of the key inflammatory cytokine IL-6, CC chemokine ligand-2 and -5, matrix metalloproteinase-3, intercellular adhesion molecule-1, and vascular cell adhesion molecule-1. The proliferative activity of the cells was also suppressed. This is the first demonstration of an inhibitor of NF-κB nuclear translocation exhibiting a therapeutic effect on established murine arthritis, and suppression of inflammatory mediators in FLS was thought to be among the mechanisms underlying such an effect

Alterations in the self-renewal and differentiation ability of bone marrow mesenchymal stem cells in a mouse model of rheumatoid arthritis

Introduction: Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease primarily involving the synovium. Evidence in recent years has suggested that the bone marrow (BM) may be involved, and may even be the initiating site of the disease. Abnormalities in haemopoietic stem cells' (HSC) survival, proliferation and aging have been described in patients affected by RA and ascribed to abnormal support by the BM microenvironment. Mesenchymal stem cells (MSC) and their progeny constitute important components of the BM niche. In this study we test the hypothesis that the onset of inflammatory arthritis is associated with altered self-renewal and differentiation of bone marrow MSC, which alters the composition of the BM microenvironment. Methods: We have used Balb/C Interleukin-1 receptor antagonist knock-out mice, which spontaneously develop RA-like disease in 100% of mice by 20 weeks of age to determine the number of mesenchymal progenitors and their differentiated progeny before, at the start and with progression of the disease. Results: We showed a decrease in the number of mesenchymal progenitors with adipogenic potential and decreased bone marrow adipogenesis before disease onset. This is associated with a decrease in osteoclastogenesis. Moreover, at the onset of disease a significant increase in all mesenchymal progenitors is observed together with a block in their differentiation to osteoblasts. This is associated with accelerated bone loss. Conclusions: Significant changes occur in the BM niche with the establishment and progression of RA-like disease. Those changes may be responsible for aspects of the disease, including the advance of osteoporosis. An understanding of the molecular mechanisms leading to those changes may lead to new strategies for therapeutic intervention

The role of proteases in pathologies of the synovial joint

Synovial (diarthrodial) joints are employed within the body to provide skeletal mobility and have a characteristic structure adapted to provide a smooth almost frictionless surface for articulation. Pathologies of the synovial joint are an important cause of patient morbidity and can affect each of the constituent tissues. A common feature of these pathologies is degenerative changes in the structure of the tissue which is mediated, at least in part, by proteolytic activity. Most tissues of the synovial joint are composed primarily of extracellular matrix and key pathological roles in the degeneration of this matrix are performed by metalloproteinases such as matrix metallproteinases (MMPs) and a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS). However, other proteases such as cathepsin K are likely to play an important role, especially in bone turnover. In addition to the cleavage of structural proteins, proteolytic activities are employed to regulate the activity of other proteases, growth factors, cytokines and other inflammatory mediators. Proteases combine to form complex regulatory networks, the correct functioning of which is required for tissue homeostasis and the imbalance of which may be a feature of pathology. A precise understanding of the proteases involved in these networks is required for a true understanding of the associated pathology

Fibroblast-Like Synoviocytes Glucose Metabolism as a Therapeutic Target in Rheumatoid Arthritis.

Metabolomic studies show that rheumatoid arthritis (RA) is associated with metabolic disruption that may be therapeutically targetable. Among them, glucose metabolism and glycolytic intermediaries seem to have an important role in fibroblast-like synoviocytes (FLS) phenotype and might contribute to early stage disease pathogenesis. RA FLS are transformed from quiescent to aggressive and metabolically active cells and several works have shown that glucose metabolism is increased in activated FLS. Glycolytic inhibitors reduce not only FLS aggressive phenotype in vitro but also decrease bone and cartilage damage in several murine models of arthritis. Essential glycolytic enzymes, including hexokinase 2 (HK2) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB) enzymes, have important roles in FLS behavior. Of interest, HK2 is an inducible enzyme present only in the inflamed rheumatic tissues compared to osteoarthritis synovium. It is a contributor to glucose metabolism that could be selectively targeted without compromising systemic homeostasis as a novel approach for combination therapy independent of systemic immunosuppression. More information about metabolic targets that do not compromise global glucose metabolism in normal cells is needed