title: Cell stress molecules in the skeletal muscle of GNE myopathy.
abstract: BACKGROUND
  Mutations of the UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine-kinase (GNE)-gene are causally related to GNE myopathy. Yet, underlying pathomechanisms of muscle fibre damage have remained elusive. In sporadic inclusion body myositis (sIBM), the pro-inflammatory cell-stress mediators αB-crystallin and inducible nitric oxide synthase (iNOS) are crucial markers of the disease pathology.
  
  
  METHODS
  10 muscle biopsies from GNE myopathy patients were analyzed for mRNA-expression of markers of cell-stress, inflammation and β-amyloid and compared to non-myopathic controls. Using double-labeling immunohistochemistry, serial sections of skeletal muscle biopsies were stained for amyloid precursor protein (APP), major histocompatibility complex (MHC)-I, αB-crystallin, neural cell adhesion molecule (NCAM), interleukin (IL)-1β, β-amyloid, iNOS, and phosphorylated neurofilament (P-neurofilament) as well as hematoxylin/eosin histochemistry. Corresponding areas of all biopsies with a total of 2,817 muscle fibres were quantitatively assessed for all markers.
  
  
  RESULTS
  mRNA-expression of APP, NCAM, iNOS, TNF-α and TGF-β was higher in GNE myopathy compared to controls, yet this was not statistically significant. The mRNA-expression of APP and αB-crystallin significantly correlated with the expression of several pro-inflammatory and cell-stress-associated markers as NCAM, IL-1β, TGF-β, CCL-3, and CCL4. By immunohistochemistry, αB-crystallin and iNOS were co-upregulated and the number of fibres positive for αB-crystallin, NCAM, MHC-I and iNOS significantly correlated with each other. A large fraction of fibres positive for αB-crystallin were double positive for iNOS and vice-versa. Moreover, several fibres with structural abnormalities were positive for αB-crystallin and iNOS. Notably, particularly normal appearing fibres displayed an overexpression of these molecules.
  
  
  CONCLUSIONS
  The cell-stress molecules αB-crystallin and iNOS are overexpressed in GNE myopathy muscle and may identify early disease mechanisms. The data help to better understand the pathology of GNE myopathy.
authors.affiliation: Department of Neurology, University Medical Center, Göttingen, Germany.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Fischer
authors.forename: Konstanze
authors.initials: K
authors.lastname: Kleinschnitz
authors.forename: Arne
authors.initials: A
authors.lastname: Wrede
authors.forename: Ingrid
authors.initials: I
authors.lastname: Muth
authors.forename: Niels
authors.initials: N
authors.lastname: Kruse
authors.forename: Ichizo
authors.initials: I
authors.lastname: Nishino
authors.forename: Jens
authors.initials: J
authors.lastname: Schmidt
mesh_terms: D000328:Adult; D016564:Amyloid beta-Protein Precursor / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D015395:Histocompatibility Antigens Class I / Q000235:genetics / Q000378:metabolism; D006801:Humans; D019751:Intramolecular Transferases / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000473:pathology; D009135:Muscular Diseases / Q000235:genetics* / Q000473:pathology*; D009154:Mutation / Q000235:genetics; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics; D012044:Regression Analysis; D055815:Young Adult; D038203:alpha-Crystallin B Chain / Q000235:genetics* / Q000378:metabolism
chemical_list: D016564:Amyloid beta-Protein Precursor; D029681:Arabidopsis Proteins; D016207:Cytokines; D015395:Histocompatibility Antigens Class I; D019006:Neural Cell Adhesion Molecules; D038203:alpha-Crystallin B Chain; D052247:Nitric Oxide Synthase Type II; D017853:Phosphotransferases (Alcohol Group Acceptor); C018765:N-acylmannosamine kinase; D019751:Intramolecular Transferases; C568454:marneral synthase, Arabidopsis