Th2-M2 immunity in lesions of muscular sarcoidosis and macrophagic myofasciitis

Objective To analyse the paradox of a lack of giant cell formation and fibrosis in chronic lesions of macrophagic myofasciitis (MMF) in comparison with muscular sarcoidosis (MuS). Methods Inflammatory lesions and contiguous muscle regions from biopsy samples of 10 patients with MuS and 10 patients with MMF were cut out by laser microdissection. Mediators of the T helper cell (Th)1 inducing classical macrophage activation (e.g. STAT1, IFNγ and CXCR3), and Th2 inducing alternative activation of macrophages (e.g. CD206/MRC1, STAT6, SOCS1), molecules involved in development of fibrosis (e.g. TGFβ) and giant cells (e.g. TYROBP), were assessed by immunohistochemistry and real-time polymerase chai…

P.21.2 New insights into eosinophilic fasciitis

Eosinophilic fasciitis (EF), first described by Shulman in 1974, is a rare disease characterized by fibrosis and inflammatory infiltration of the muscle fascia as well as scleroderma-like skin indurations and blood eosinophilia. In contrast to other inflammatory myopathies, patients generally show less muscle weakness and myalgia, and a frequent increase in body weight. Thus, we hypothesize a unique immune mechanism underlying Shulman syndrome. The immunohistochemical expression pattern of leucocytes and a comprehensive panel of cytokine and chemokine expression on RNA level of muscle specimen from EF patients were compared to healthy control muscle. In patients with biopsy-proven EF the im…

Primary oligodendrocyte death does not elicit anti-CNS immunity.

Anti-myelin immunity is commonly thought to drive multiple sclerosis, yet the initial trigger of this autoreactivity remains elusive. One of the proposed factors for initiating this disease is the primary death of oligodendrocytes. To specifically test such oligodendrocyte death as a trigger for anti-CNS immunity, we inducibly killed oligodendrocytes in an in vivo mouse model. Strong microglia-macrophage activation followed oligodendrocyte death, and myelin components in draining lymph nodes made CNS antigens available to lymphocytes. However, even conditions favoring autoimmunity-bystander activation, removal of regulatory T cells, presence of myelin-reactive T cells and application of dem…

M2 Polarized Macrophages and Giant Cells Contribute to Myofibrosis in Neuromuscular Sarcoidosis

The etiopathogenesis of sarcoidosis, a systemic granulomatous disease, still remains obscure. A multitude of organs have been described to be affected in systemic sarcoidosis. Skeletal muscles may also be affected, leading to myalgia and weakness. A workup of the specific immune response with emphasis on the macrophage response is provided herein. Affected muscle tissue from seven patients with systemic sarcoidosis was analyzed and compared with that from seven patients with other myopathies containing macrophagocytic infiltration. Monocytes/macrophages and giant cells in granulomas of muscle tissue from patients with sarcoidosis show a status of alternative activation (M2) based on their e…

Immune-mediated necrotizing myopathy is characterized by a specific Th1-M1 polarized immune profile.

Immune-mediated necrotizing myopathy (IMNM) is considered one of the idiopathic inflammatory myopathies, comprising dermatomyositis, polymyositis, and inclusion body myositis. The heterogeneous group of necrotizing myopathies shows a varying amount of necrotic muscle fibers, myophagocytosis, and a sparse inflammatory infiltrate. The underlying immune response in necrotizing myopathy has not yet been addressed in detail. Affected muscle tissue, obtained from 16 patients with IMNM, was analyzed compared with eight non-IMNM (nIMNM) tissues. Inflammatory cells were characterized by IHC, and immune mediators were assessed by quantitative real-time PCR. We demonstrate that immune- and non–immune-…

Juvenile autophagic vacuolar myopathy - a new entity or variant?

Pipestem capillaries in necrotizing myopathy revisited.

Pipestem-capillaries in necrotizing myopathy, have been reported as a feature of a distinct type of myopathy. Here, we analyze four muscle biopsy specimens from patients exhibiting endomysial fibrosis associated with pipestem capillaries using histological and electronmicroscopic techniques. However, only one case displayed all of the originally described features, including necrotic fibres, capillary thickening and lack of a significant lymphocytic inflammation, while one case exhibited striking capillary pathology with minimal necrosis and absence of inflammation, and the other two cases were accompanied by additional pathological features. These data support the existence of a microangio…

Nuclear actin aggregation is a hallmark of anti-synthetase syndrome-induced dysimmune myopathy

Objective: To analyze antisynthetase syndrome–associated myositis by modern myopathologic methods and to define its place in the spectrum of idiopathic inflammatory myopathies (IIMs). Methods: Skeletal muscle biopsies from antisynthetase syndrome–associated myositis and other IIMs from different institutions worldwide were analyzed by histopathology, quantitative PCR, and electron microscopy. Results: Myonuclear actin filament inclusions were identified as a unique morphologic hallmark of antisynthetase syndrome–associated myositis. Nuclear actin inclusions were never found in dermatomyositis, polymyositis, sporadic inclusion body myositis, autoimmune necrotizing myopathy associated with si…

Fetal akinesia caused by a novel actin filament aggregate myopathy skeletal muscle actin gene (ACTA1) mutation.

We report a female newborn, diagnosed with fetal akinesia in utero, who died one hour after birth. Post-mortem muscle biopsy demonstrated actin-filament myopathy based on immunolabelling for sarcomeric actin, and large areas of filaments, without rod formation, ultrastructurally. Analysis of DNA extracted from the muscle disclosed a novel de novo heterozygous c.44G>A, GGC>GAC, 'p.Gly15Asp' mutation in the ACTA1 gene. Analysis of the location of the mutated amino-acid in the actin molecule suggests the mutation most likely causes abnormal nucleotide binding, and consequent pathological actin polymerization. This case emphasizes the association of fetal akinesia with actin-filament myopathy.

A Cre-inducible diphtheria toxin receptor mediates cell lineage ablation after toxin administration.

A new system for lineage ablation is based on transgenic expression of a diphtheria toxin receptor (DTR) in mouse cells and application of diphtheria toxin (DT). To streamline this approach, we generated Cre-inducible DTR transgenic mice (iDTR) in which Cre-mediated excision of a STOP cassette renders cells sensitive to DT. We tested the iDTR strain by crossing to the T cell- and B cell-specific CD4-Cre and CD19-Cre strains, respectively, and observed efficient ablation of T and B cells after exposure to DT. In MOGi-Cre/iDTR double transgenic mice expressing Cre recombinase in oligodendrocytes, we observed myelin loss after intraperitoneal DT injections. Thus, DT crosses the blood-brain bar…

Novel γ-sarcoglycan-mutation affects cardiac function and N-terminal dystrophin expression

Membrane-type 1 metalloproteinase is upregulated in microglia/brain macrophages in neurodegenerative and neuroinflammatory diseases

We previously reported that glioma cells induce the expression of membrane-type 1 metalloproteinase (MT1-MMP or MMP-14) in tumor-associated microglia/macrophages and promote tumor growth, whereas MMP-14 expression in microglia under physiological conditions is very low. Here, we show that the increase in MMP-14 expression is also found in microglia/macrophages associated with neurodegenerative and neuroinflammatory pathologies in mouse models as well as in human biopsies or post-mortem tissue. We found that microglial/macrophage MMP-14 expression was upregulated in Alzheimer's disease tissue, in active lesions of multiple sclerosis, and in tissue from stage II stroke as well as in the corre…

An unconventional role for miRNA: let-7 activates Toll-like receptor 7 and causes neurodegeneration

Activation of innate immune receptors by host-derived factors exacerbates CNS damage, but the identity of these factors remains elusive. We uncovered an unconventional role for the microRNA let-7, a highly abundant regulator of gene expression in the CNS, in which extracellular let-7 activates the RNA-sensing Toll-like receptor (TLR) 7 and induces neurodegeneration through neuronal TLR7. Cerebrospinal fluid (CSF) from individuals with Alzheimer’s disease contains increased amounts of let-7b, and extracellular introduction of let-7b into the CSF of wild-type mice by intrathecal injection resulted in neurodegeneration. Mice lacking TLR7 were resistant to this neurodegenerative effect, but thi…

A Paucisymptomatic Neuromuscular Disease Mimicking Type III 5q-SMA With Complex Rearrangements in the SMN Gene

Spinal muscular atrophy is an autosomal-recessive neuromuscular disorder, causing progressive proximal weakness and atrophy of the voluntary muscles. More than 96% of the spinal muscular atrophy patients show a homozygous absence of exons 7 and 8, or exon 7 only, in SMN1, the telomeric copy of the SMN gene. We report a young male patient with neurogenic symptoms and sparse muscle fiber atrophy, suggestive of a mild form of type III spinal muscular atrophy. He was found to be a carrier of intragenic mutations in both copies of the SMN gene, exhibiting a homozygous duplication of exons 7 and 8 in SMN1 and a homozygous deletion of exon 8 as well as a heterozygous deletion of exon 7 in SMN2. H…

P.20.3 Targeting fibrosis and inflammation in Duchenne Muscular Dystrophy

Duchenne Muscular Dystrophy is the most frequent genetic muscle disease worldwide affecting ∼1:5000 male births. It is caused by a defective DMD gene, which leads to reduced and defective dystrophin protein expression. The constant breakdown of fibres leads to focal necrosis, myophagocytosis and a considerable influx of inflammatory cells into the muscle tissue, which is followed by increasing endomysial fibrosis. Both, inflammation and fibrosis as well as a putative relation are not yet understood immunologically. Fibrosis directly correlates with adverse outcome and early loss of ambulation. We have studied how inflammation is linked to fibrosis in DMD, with an emphasis on the communicati…

IL-17A and IL-17F do not contribute vitally to autoimmune neuro-inflammation in mice

The clear association of Th17 cells with autoimmune pathogenicity implicates Th17 cytokines as critical mediators of chronic autoimmune diseases such as EAE. To study the impact of IL-17A on CNS inflammation, we generated transgenic mice in which high levels of expression of IL-17A could be initiated after Cre-mediated recombination. Although ubiquitous overexpression of IL-17A led to skin inflammation and granulocytosis, T cell–specific IL-17A overexpression did not have a perceptible impact on the development and health of the mice. In the context of EAE, neither the T cell–driven overexpression of IL-17A nor its complete loss had a major impact on the development of clinical disease. Sin…