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…

The potassium channels TASK2 and TREK1 regulate functional differentiation of murine skeletal muscle cells.

Two-pore domain potassium (K2P) channels influence basic cellular parameters such as resting membrane potential, cellular excitability, or intracellular Ca2+-concentration [Ca2+]i. While the physiological importance of K2P channels in different organ systems (e.g., heart, central nervous system, or immune system) has become increasingly clear over the last decade, their expression profile and functional role in skeletal muscle cells (SkMC) remain largely unknown. The mouse SkMC cell line C2C12, wild-type mouse muscle tissue, and primary mouse muscle cells (PMMs) were analyzed using quantitative PCR, Western blotting, and immunohistochemical stainings as well as functional analysis includin…

Ultrastructural myopathology in the molecular era.

Electron microscopy is an essential component of myopathology, both in diagnostics and research of neuromuscular diseases. Although recently reduced in the diagnostic armamentarium, it has greatly been expanded to mouse models in research. Mostly it is descriptive, but a few additional techniques in combination with transmission electron microscopy have been employed. Foremost among them is immunoelectron microscopy, which assists in guiding molecular analysis in hereditary conditions, but may be vital in diagnostics of certain acquired entities, e.g., undulating tubules in dermatomyositis and in those congenital myopathies where genes and mutations remain to be identified, as in cylindrica…

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…

Review: Immune-mediated necrotizing myopathies - a heterogeneous group of diseases with specific myopathological features

Immune-mediated necrotizing myopathies (IMNMs) are now well recognized among the so-called idiopathic inflammatory myopathies (IIMs), which also comprise dermatomyositis (DM), polymyositis (PM), sporadic inclusion body myositis (sIBM) and non-specific myositis. All of these conditions are defined on the basis of distinct clinical symptoms, in combination with results derived from muscle biopsy and additional data, such as measurement of the serum creatine kinase (CK) level as well as myositis-associated and myositis-specific autoantibodies, electromyography (EMG) and modern imaging techniques. Importantly, diagnosis of one of the above mentioned myositis forms implies a specific clinical sy…

Human NCL Neuropathology

AbstractThe neuronal ceroid lipofuscinoses (NCL) currently encompass fourteen genetically different forms, CLN1 to CLN14, but are all morphologically marked by loss of nerve cells, particularly in the cerebral and cerebellar cortices, and the cerebral and extracerebral formation of lipopigments. These lipopigments show distinct ultrastructural patterns, i.e., granular, curvilinear/rectilinear and fingerprint profiles. They contain−although to a different degree among the different CLN forms−subunit C of ATP synthase, saposins A and D, and beta-amyloid proteins. Extracerebral pathology, apart from lipopigment formation, which provides diagnostic information, is scant or non-existent. The ret…

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-…

Cytoplasmic body myopathy revisited.

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.

G.P.192

After uneventful pregnancies, two newborn siblings, a girl and a boy – another sibling was stillborn – developed inspiratory stridor, hypertrophy of the right cardiac ventricle, reduction in spontaneous movements and mildly elevated creatine kinase. Muscle biopsies at ages of three months and seven weeks were performed and respectively, revealed a 'prepathological' pattern of infantile neurogenic atrophy suggesting spinal muscular atrophy (SMA). However, molecular analyses of SMN (SMA) and IGHMBP2 (SMARD1) genes did not disclose any mutations. Further histochemical staining of the skeletal muscle and heart demonstrated almost complete absence of cytochrome c oxidase while SDH was preserved.…

Practical application of electron microscopy to neuromuscular diseases.

Concerning individual neuromuscular conditions, electron microscopy may be considered “essential,” “helpful,” or “wasteful.” “Essential” electron microscopy should provide a clear diagnosis, because of the disease specificity of the ultrastructural findings, in particular as to inclusions within muscle fibers, such as cylindrical spirals and reducing bodies. Electron microscopy may be “helpful” in detecting ultrastructural features preceding typical light microscopic findings, for instance, undulating tubules in endothelial cells. Congenital, metabolic, and inflammatory myopathies may often be more easily and more reliably diagnosed by means of the electron microscope. Diagnostically “waste…

205th ENMC International Workshop: Pathology diagnosis of idiopathic inflammatory myopathies Part II 28-30 March 2014, Naarden, The Netherlands.

The idiopathic inflammatory myopathies (IM) are a heterogeneous group of diseases and diagnosis often necessitates a muscle biopsy. Five main entities are recognized: (1) dermatomyositis (DM); (2) polymyositis (PM); (3) necrotizing autoimmune myopathy (NAM); (4) sporadic inclusion body myositis (IBM); and (5) non-specific myositis. Other entities include granulomatous myopathy, macrophagic myofasciitis, and eosinophilic fasciitis (Shulman's syndrome). The pathological classification and subsequent identification of disease subgroups are extremely important for assessing treatment options and prognosis in the individual patient, yet classification criteria have not been standardized and vali…

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

Systematic retrospective study of 64 patients with anti-Mi2 dermatomyositis: A classic skin rash with a necrotizing myositis and high risk of malignancy

Morphology of Skeletal Muscle

Skeletal muscle makes up the largest organ of the body, by both volume and weight, comprising more than 40 %. More than 500 diseases concern muscle tissue, the majority of which originate in muscle, others secondarily affect the muscle, foremost by denervation. The functional and structural dependence of skeletal muscle on innervation—that is, the peripheral and central nervous systems—renders muscle tissue unique and adds a dimension to the nosology, more obviously than in other organs. Therefore, diseases affecting muscle are also termed neuromuscular diseases. Within the nosological spectrum of the muscle parenchyma, which encompasses hereditary and acquired conditions, muscular dystroph…

Autophagic vacuolar myopathy is a common feature of CLN3 disease

Abstract Objective The neuronal ceroid lipofuscinoses (NCL) are genetic degenerative disorders of brain and retina. NCL with juvenile onset (JNCL) is genetically heterogeneous but most frequently caused by mutations of CLN3. Classical juvenile CLN3 includes a rare protracted form, which has previously been linked to autophagic vacuolar myopathy (AVM). Our study investigates the association of AVM with classic, non‐protracted CLN3. Methods Evaluation of skeletal muscle biopsies from three, non‐related patients with classic, non‐protracted and one patient with protracted CLN3 disease by histology, immunohistochemistry, electron microscopy, and Sanger sequencing of the coding region of the CLN…

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…