Julia Wanschitz

Hereditary spastic paraplegias with autosomal dominant, recessive, X-linked, or maternal trait of inheritance

Hereditary spastic paraplegia (SPG) is a clinically and genetically heterogeneous group of neurodegenerative disorders that are clinically characterised by progressive spasticity and weakness of the lower-limbs (pure SPG) and, majoritorian, additional more extensive neurological or non-neurological manifestations (complex or complicated SPG). Pure SPG is characterised by progressive spasticity and weakness of the lower-limbs, and occasionally sensory disturbances or bladder dysfunction. Complex SPGs additionally include cognitive impairment, dementia, epilepsy, extrapyramidal disturbances, cerebellar involvement, retinopathy, optic atrophy, deafness, polyneuropathy, or skin lesions in the absence of coexisting disorders. Nineteen SPGs follow an autosomal-dominant (AD-SPG), 27 an autosomal-recessive (AR-SPG), 5 X-linked (XL-SPG), and one a maternal trait of inheritance. SPGs are due to mutations in genes encoding for proteins involved in the maintenance of corticospinal tract neurons. Among the AD-SPGs, 40-45% of patients carry mutations in the SPAST-gene (SPG4) and 10% in the ATL1-gene (SPG3), while the other 9 genes are more rarely involved (NIPA1 (SPG6), KIAA0196 (SPG8), KIF5A (SPG10), RNT2 (SPG12), SPGD1 (SPG13), BSCL2 (SPG17), REEP1 (SPG31), ZFYVE27 (SPG33, debated), and SLC33A1 (SPG42, debated)). Among the AR-SPGs, ~20% of the patients carry mutations in the KIAA1840 (SPG11) gene whereas the 15 other genes are rarely mutated and account for SPGs in single families yet (CYP7B1 (SPG5), SPG7 (SPG7), ZFYVE26 (SPG15), ERLIN2 (SPG18), SPG20 (SPG20), ACP33 (SPG21), KIF1A (SPG30), FA2H (SPG35), NTE (SPG39), GJA12/GJC2 (SPG44), KIAA0415 (SPG48) and 4 genes encoding for the AP4-complex (SPG47)). Among the XL-SPGs, 3 causative genes have been identified (L1CAM (SPG1), PLP1 (SPG2), and SLC16A2 (SPG22)). The diagnosis of SPGs is based on clinical, instrumental and genetic investigations. Treatment is exclusively symptomatic.

Hypoxia up-regulates the angiogenic cytokine secretoneurin via an HIF-1α- and basic FGF-dependent pathway in muscle cells

Expression of angiogenic cytokines like vascular endothelial growth factor is enhanced by hypoxia. We tested the hypothesis that decreased oxygen levels up‐regulate the angiogenic factor sec‐retoneurin. In vivo, muscle cells of mouse ischemic hind limbs showed increased secretoneurin expression, and inhibition of secretoneurin by a neutralizing antibody impaired the angiogenic response in this ischemia model. In a mouse soft tissue model of hypoxia, secretoneurin was increased in subcutaneous muscle fibers. In vitro, secretoneurin mRNA and protein were up‐regulated in L6 myoblast cells after exposure to low oxygen levels. The hypoxia‐depen‐dent regulation of secretoneurin was tissue specific and was not observed in endothelial cells, vascular smooth muscle cells, or AtT20 pituitary tumor cells. The hypoxia‐dependent induction of secretoneurin in L6 myoblasts is regulated by hypoxia‐inducible factor‐la, since inhibition of this factor using si‐RNA inhibited up‐regulation of secretoneurin. Induction of secretoneurin by hypoxia was dependent on basic fibroblast growth factor in vivo and in vitro, and inhibition of this regulation by heparinase suggests an involvement of low‐affinity basic fibroblast growth factor binding sites. In summary, our data show that the angiogenic cytokine secretoneurin is up‐regulated by hypoxia in muscle cells by hypoxia‐inducible factor‐1α‐ and basic fibroblast growth factor‐dependent mechanisms.—Egger, M., Schgoer, W., Beer, A. G. E., Jeschke, J., Leierer, J., Theurl, M., Frauscher, S., Tepper, O. M., Niederwanger, A., Ritsch, A., Kearney, M., Wanschitz, J., Gurtner, G. C., Fischer‐Colbrie, R., Weiss, G., Piza‐Katzer, H., Losordo, D. W., Patsch, J. R., Schratzberger, P., Kirchmair, R. Hypoxia up‐regulates the angiogenic cytokine secretoneurin via an HIF‐1α‐ and basic FGF‐dependent pathway in muscle cells. FASEB J. 21, 2906–2917 (2007)

Abnormalities of satellite cells function in amyotrophic lateral sclerosis

Abstract Amyotrophic lateral sclerosis (ALS) is characterized by progressive denervation leading to muscle atrophy prevented, during the early phase, by compensatory reinnervation. Little is known about muscle fibre regeneration capacity in ALS. We have carried out in vivo and in vitro investigation of skeletal muscle in ALS. Seven ALS patients underwent a deltoid muscle biopsy. Immunohistochemical analysis revealed various degrees of denervation- and reinnervation-related changes in the ALS muscle biopsies including satellite cells (SCs) activation and regenerating fibres. Only 3/7 primary cultures of ALS muscle cells were successfully established and had sufficient myogenicity, as assessed by desmin positivity, to be used without further purification. This was in contrast with the cultures derived from control muscles, predominantly desmin-positive cells. Although capable to proliferate in vitro, ALS-derived SCs presented an abnormal senescent-like morphology. Markers of senescence, including senescent-associated (SA)-βGal activity and p16 expression, were increased. Furthermore, ALS-derived SCs were also unable to fully differentiate in vitro as shown by abnormal myotubes morphology and reduced MHC isoform expression, compared to control myotubes. Our study suggests that SC function is altered in ALS. This could limit the efficacy of compensatory processes and therefore could contribute to the progression of muscle atrophy and weakness.

Th1 response and systemic treg deficiency in inclusion body myositis.

Objective Sporadic inclusion body myositis (sIBM), the most frequent myositis in elderly patients, is characterized by the presence muscle inflammation and degeneration. We aimed at characterizing immune responses and regulatory T cells, considered key players in the maintenance of peripheral immune tolerance, in sIBM. Methods Serum and muscle tissue levels of 25 cytokines and phenotype of circulating immune cells were measured in 22 sIBM patients and compared with 22 healthy subjects. Cytokine data were analysed by unsupervised hierarchical clustering and principal components analysis. Results Compared to healthy controls, sIBM patients had increased levels of Th-1 cytokines and chemokines such as IL-12 (261±138 pg/mL vs. 88±19 pg/mL; p<0.0001), CXCL-9 (186±12 pg/mL vs. 13±7 pg/mL; p<0.0001), and CXCL-10 (187±62 pg/mL vs. 13±6 pg/mL; p<0.0001). This was associated with an increased frequency of CD8+CD28− T cells (45.6±18.5% vs. 13.5±9.9%; p<0.0001), which were more prone to produce IFN-γ (45.6±18.5% vs. 13.5±9.9%; p<0.0001). sIBM patients also had a decreased frequency of circulating regulatory T cells (CD4+CD25+CD127lowFOXP3+, 6.9±1.7%; vs. 5.2±1.1%, p = 0.01), which displayed normal suppressor function and were also present in affected muscle. Conclusion sIBM patients present systemic immune activation with Th1 polarization involving the IFN-γ pathway and CD8+CD28− T cells associated with peripheral regulatory T cell deficiency.

Correlation of frataxin content in blood and skeletal muscle endorses frataxin as a biomarker in Friedreich ataxia.

Friedreich ataxia is an autosomal recessive disorder caused by mutations in the frataxin gene, leading to reduced levels of the mitochondrial protein frataxin. Assays to quantitatively measure frataxin in peripheral blood have been established. To determine the validity of frataxin as a biomarker for clinical trials, we assessed frataxin in clinically affected tissue.

The prion protein in human neuromuscular diseases

The basis of human prion diseases affecting the nervous system is accumulation of a disease‐associated conformer (PrPSc) of the normal cellular prion protein (PrPC). Earlier studies demonstrated increased expression of PrPC in inclusion body myositis (IBM), dermato‐, and polymyositis, as well as neurogenic muscle atrophy. To define the spectrum and reliability of PrPC immunoreactivity, its expression was examined systematically in a series of pathologically characterized muscular disorders by means of immunohistochemistry, confocal laser microscopy, and immunogold electron microscopy. Anti‐PrPC immunolabelling of rimmed vacuoles was observed in IBM, inclusions of myofibrillary myopathy, targets, regenerating, and atrophic fibres, mononuclear cells, in addition to ragged red fibres in mitochondrial myopathies, and focal sarcolemmal immunostaining in non‐diseased controls. Quantitative analysis demonstrated that, in neurogenic muscle lesions, anti‐PrPC staining detects a significantly broader spectrum of fibres than anti‐vimentin or anti‐NCAM. In dystrophic muscle, PrPC expression was mainly restricted to regenerating fibres. In IBM, PrPC expression was not confined to rimmed vacuoles or vacuolated fibres and only a small percentage (7.1%) of rimmed vacuoles were PrPC positive. Ultrastructurally, PrPC was observed in the cytoplasm of lymphocytes, in the myofibrillar network of targets, and in rimmed vacuoles. Knowledge of disease circumstances with altered expression of PrPC is important in the setting of a potentially increased chance for extraneural PrPC–PrPSc conversion. In addition, our observations suggest that PrPC may have a general stress–response effect in various neuromuscular disorders. Copyright

Endothelial and Myogenic Differentiation of Hematopoietic Progenitor Cells in Inflammatory Myopathies

Incorporation of circulating hematopoietic progenitor cells (HPCs) into damaged skeletal muscle has been proposed as a novel mechanism of tissue repair complementary to satellite cell-dependent regeneration. We studied the occurrence and myoendothelial differentiation of HPCs in muscle of patients with inflammatory myopathies. Muscle biopsies from untreated patients with dermatomyositis, polymyositis, inclusion body myositis, and controls were investigated for the expression of endothelial (CD31, von Willebrand factor, vascular endothelial growth factor receptor 2), hematopoietic (CD34, CD133, CD45), and myogenic (Pax7, MyoD) markers by immunohistochemistry and reverse-transcriptase-polymerase chain reaction. Confocal laser scanning microscopy was used to visualize coexpression of CD34, CD133, von Willebrand factor, or Pax7 on individual cells. Morphometric analysis revealed significantly increased numbers of CD133+ cells per square millimeter in polymyositis and inclusion body myositis compared with controls (p < 0.001); this correlated with the density of CD45+ infiltrates (p < 0.001). By confocal laser scanning microscopy, we detected several mononuclear cells that coexpressed either CD34/von Willebrand factor or CD133/Pax7 with or without CD34 reactivity, indicating endothelial or myogenic commitment of some HPCs in skeletal muscle. Rarely, CD133+/CD34±/Pax7+ cells seemed to occupy satellite cell niches or to incorporate into preexisting myofibers. Our findings suggest that circulating HPCs colonize skeletal muscle in inflammatory conditions and provide evidence for in situ myoendothelial differentiation of some of these cells.

Serotonergic nuclei of the raphe are not affected in human ageing

Sleep disorders increase with ageing. The serotonergic system has been linked with sleep regulation. In fatal familial insomnia, a prion disease with insomnia as one major clinical feature, we recently observed a disturbance in the serotonergic system as likely substrate of typical symptoms. Using immunohistochemistry for the serotonin synthesizing enzyme, tryptophan hydroxylase, we investigated the serotonergic median raphe nuclei (dorsal raphe nucleus, superior central nucleus, and raphe obscurus nucleus) in brains of an older (n = 12; age range 62–84 years) and a younger group (n = 10; age range 5–29 years). We found no significant difference between age groups in the percentage of neurons able to synthesize serotonin. Other changes might relate to sleep disturbances in the elderly.

Guidelines on dermatomyositis – excerpt from the interdisciplinary S2k guidelines on myositis syndromes by the German Society of Neurology

The present guidelines on dermatomyositis (DM) represent an excerpt from the interdisciplinary S2k guidelines on myositis syndromes of the German Society of Neurology (available at www.awmf.org). The cardinal symptom of myositis in DM is symmetrical proximal muscle weakness. Elevated creatine kinase, CRP or ESR as well as electromyography and muscle biopsy also provide important diagnostic clues. Pharyngeal, respiratory, cardiac, and neck muscles may also be affected. Given that approximately 30 % of patients also develop interstitial lung disease, pulmonary function tests should be part of the diagnostic workup. Although the cutaneous manifestations in DM are variable, taken together, they represent a characteristic and crucial diagnostic criterion for DM. Approximately 5–20 % of individuals exhibit typical skin lesions without any clinically manifest muscle involvement (amyopathic DM). About 30 % of adult DM cases are associated with a malignancy. This fact, however, should not delay the treatment of severe myositis.

Prognosis and prognostic factors in non‐traumatic acute‐onset compressive mononeuropathies – radial and peroneal mononeuropathies

Little is known about the natural history of non‐traumatic compressive mononeuropathies. To improve patient management, prognostic factors and outcome in patients with non‐traumatic peroneal and radial mononeuropathies were studied.