Jan De Bleecker

Immunolocalization of tumor necrosis factor-alpha and its receptors in inflammatory myopathies.

Adhesion molecule upregulation occurs in inflammatory myopathies, and is one of the myriad functions of tumor necrosis factor-alpha (TNF-alpha). TNF-alpha acts via two different receptors of 55 (TNF-R55) and 75 kD (TNF-R75). We immunolocalized TNF-alpha and its receptors in polymyositis, inclusion body myositis and dermatomyositis. In each myopathy, TNF-alpha was detected in macrophages, in myonuclei in regenerating muscle fibers, and freely dispersed in endomysial or perimysial connective tissue. Many endothelial cells in dermatomyositis expressed TNF-alpha. TNF-R55 was strongly expressed on myonuclei of regenerating muscle fibers. TNF-R75 was increased on endothelial cells in the midst of inflammatory infiltrates in each myopathy, and on perifascicular and perimysial endothelia, remote from inflammatory foci in dermatomyositis. Possible TNF-alpha-mediated effects include: increased transendothelial cell trafficking, activation of T/B cells and macrophages, induction of MHC-I gene products, and focal muscle fiber atrophy. In dermatomyositis, the upregulated TNF-R75, via its consensus elements for transcription factors, may be involved in endothelial cell degeneration. Strong TNF-R55 expression on regenerating myonuclei is consistent with a role of TNF-alpha and TNF-R55 in muscle regeneration.

Differential expression of chemokines in inflammatory myopathies

Background: Chemokines represent a family of small-molecular-weight cytokines that recruit and activate inflammatory cells in response to inflammation. Invasion of cytotoxic memory T cells and macrophages in nonnecrotic muscle fibers characterizes polymyositis and sporadic inclusion body myositis. Dermatomyositis is a complement-mediated endotheliopathy. Elucidation of the mechanisms guiding lymphocyte diapedesis and trafficking could lead to selective therapeutic interventions. Methods: Immunoblots and multistep immunofluorescence studies with non–cross-reactive antibodies recognizing interleukin-8, monocyte chemoattractant protein-1 (MCP-1), MCP-3, TARC (thymus and activation regulated cytokine), and RANTES (regulated upon activation, normal T-cell expressed and secreted), using appropriate positive and negative controls. In situ hybridization was used to localize MCP-1 mRNA. Results: MCP-1 protein was strongly expressed on T cells and a subset of macrophages actively invading a proportion of the nonnecrotic muscle fibers in polymyositis and inclusion body myositis alike. Capillaries and arterioles in the vicinity of endomysial inflammatory foci were immunoreactive for MCP-1, with faint or no expression in unaffected parts of the tissue. By contrast, widespread and strong endothelial MCP-1 expression occurred on perifascicular and perimysial endothelia in dermatomyositis, also at sites remote from inflammatory infiltrates. In some control specimens, a subset of capillaries also expressed MCP-1, possibly reflecting a role of this chemokine in normal immune surveillance. MCP-1 mRNA was detected in scattered macrophages in each inflammatory myopathy. All other chemokines were absent. Conclusion: Chemokines are differentially expressed in the symptomatic stage of inflammatory myopathies. MCP-1 plays a major role in the myocytotoxicity in polymyositis and inclusion body myositis. MCP-1 may be induced by membranolytic attack complex binding to endothelial cells in dermatomyositis.

European Pentoxifylline Multi-Infarct Dementia Study

A double-blind, placebo-controlled, parallel-group, multicentre study was conducted to evaluate the efficacy of pentoxifylline (Trental) in patients with multi-infarct dementia (MID) according to DSM-III-R criteria. Men and women aged 45 years or older, with a Hachinski Ischemia Scale score > or = 7 and a Mini Mental State Examination (MMSE) score of 10-25 at entry, and computed tomographic evidence of vascular disease were enrolled. A total of 289 patients were randomised to receive either oral pentoxifylline 400 mg t.i.d. or placebo for 9 months, and efficacy was assessed every 3 months. The primary outcome variable was the difference in scores between the two treatment groups, as measured on the Gottfries, Bråne, Steen (GBS) scale. Secondary outcome variables included the scores achieved on the Sandoz Clinical Assessment Geriatric (SCAG) scale and MMSE, and a battery of psychological and other tests. The intention-to-treat analysis for patients completing the study (n = 239) showed a statistically significant difference in the total GBS score in favour of pentoxifylline (improvement of 3.5 points, p = 0.028). A significant difference in the total GBS score in favour of pentoxifylline was even almost achieved in the intention-to-treat analysis for all evaluable patients (n = 269, improvement of 2.1 points, p = 0.065). It is concluded that treatment with pentoxifylline is beneficial for patients with MID, the global results of the GBS and SCAG scales being reinforced by significant improvements in those subscales specific for intellectual and cognitive function.

Expression and distribution of the nitric oxide synthases in idiopathic inflammatory myopathies

Different immune effector mechanisms have been characterised in the idiopathic inflammatory myopathies (IIM): in polymyositis (PM) and sporadic inclusion body myositis (sIBM), T-cell-mediated cytotoxicity targets nonnecrotic muscle fibres, whereas in dermatomyositis (DM) the complement-mediated immune response is directed against the microvasculature. As nitric oxide (NO) has an important function in cell signalling and in the cytotoxicity displayed by activated macrophages, it is potentially involved in the immunopathogenesis of IIM. Using immunohistochemical, in situ hybridisation and Western blotting techniques, we visualised the three isoforms of NO synthase (NOS) in muscle tissues from normal controls and from patients diagnosed with IIM. The levels of both constitutive isoforms of NOS (endothelial, i.e., eNOS, and neuronal, i.e., nNOS) were unchanged in IIM as compared with normal muscle. Both protein and mRNA of the inducible form (iNOS) were detected in half of the control biopsies. Constant and increased iNOS protein expression was found in endomysial infiltrates of PM and sIBM, whereas perimysial inflammatory cells in DM were largely negative. We developed a quantitative Western blotting protocol which confirmed the constitutive nature of nNOS and eNOS and the significant induction of iNOS in PM. Our results appoint iNOS with a dual function: a limited and transient role in normal muscle physiology and an active cytotoxic role in PM and sIBM.

Reversible Visual Deficit and Corpus callosum Lesions due to Metronidazole Toxicity

93 In conclusion, this is an exceptional case of right-sided hemiparkinsonism with an obvious unilateral bradyand hypokinesia of the face on the same side, i.e., hemihypomimia. Since this phenomenon has not yet been described in detail in the literature, the subtle lateralization of hypomimia may remain undetected in patients with PD – in particular, as a sign in the early stages of unilateral PD. It should, however, be considered in patients with PD.

Immunolocalization of Fas and Fas-ligand in inflammatory myopathies

Abstract. Fas/Fas ligand (FasL) interaction can induce apoptosis, have a costimulatory role or act as a mechanism by which cytotoxic T cells produce target cell lysis. We used several commercially available antibodies to study Fas and FasL expression in polymyositis (PM), inclusion body myositis (IBM), dermatomyositis (DM) and normal controls. A strong Fas signal occurred on the sarcolemma, and to a lesser extent in the sarcoplasm of neural cell adhesion molecule (NCAM)-positive or developmental myosin heavy chain-positive regenerating muscle fibers and of injured fibers with presumed abortive regenerative activity, including some nonnecrotic invaded fibers in PM and IBM and some of the atrophic perifascicular fibers in DM. Most fibers within groups of atrophic fibers in IBM were strongly Fas-positive, and statistically more muscle fibers were Fas-positive in IBM compared to PM. A subset of the actively invading CD8+ T cells in nonnecrotic muscle fibers in PM and IBM, and scattered CD4+ cells in each inflammatory myopathy, had up-regulated Fas expression, probably reflecting costimulation. No FasL antibody consistently labeled the positive control tissue (testis) or intramuscular elements in control or inflammatory myopathy specimens. Our study identifies regenerating muscle fibers as the main site of Fas immunoreactivity in inflammatory myopathies, and Fas expression may be part of an activated or reactivated developmental program of new gene expression in regenerating or denervated muscle fibers. Our data plead against a specific role of Fas/FasL interaction in the immunopathogenesis of the inflammatory myopathies.