title: Interferon-alpha/beta-mediated innate immune mechanisms in dermatomyositis.
abstract: Dermatomyositis has been modeled as an autoimmune disease largely mediated by the adaptive immune system, including a local humorally mediated response with B and T helper cell muscle infiltration, antibody and complement-mediated injury of capillaries, and perifascicular atrophy of muscle fibers caused by ischemia. To further understand the pathophysiology of dermatomyositis, we used microarrays, computational methods, immunohistochemistry and electron microscopy to study muscle specimens from 67 patients, 54 with inflammatory myopathies, 14 with dermatomyositis. In dermatomyositis, genes induced by interferon-alpha/beta were highly overexpressed, and immunohistochemistry for the interferon-alpha/beta inducible protein MxA showed dense staining of perifascicular, and, sometimes all myofibers in 8/14 patients and on capillaries in 13/14 patients. Of 36 patients with other inflammatory myopathies, 1 patient had faint MxA staining of myofibers and 3 of capillaries. Plasmacytoid dendritic cells, potent CD4+ cellular sources of interferon-alpha, are present in substantial numbers in dermatomyositis and may account for most of the cells previously identified as T helper cells. In addition to an adaptive immune response, an innate immune response characterized by plasmacytoid dendritic cell infiltration and interferon-alpha/beta inducible gene and protein expression may be an important part of the pathogenesis of dermatomyositis, as it appears to be in systemic lupus erythematosus.
authors.affiliation: Department of Neurology, Division of Neuromuscular Disease, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02115, USA. sagreenberg@partners.org
authors.forename: Steven A
authors.initials: SA
authors.lastname: Greenberg
authors.forename: Jack L
authors.initials: JL
authors.lastname: Pinkus
authors.forename: Geraldine S
authors.initials: GS
authors.lastname: Pinkus
authors.forename: Travis
authors.initials: T
authors.lastname: Burleson
authors.forename: Despina
authors.initials: D
authors.lastname: Sanoudou
authors.forename: Rabi
authors.initials: R
authors.lastname: Tawil
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Barohn
authors.forename: David S
authors.initials: DS
authors.lastname: Saperstein
authors.forename: Hannah R
authors.initials: HR
authors.lastname: Briemberg
authors.forename: Maria
authors.initials: M
authors.lastname: Ericsson
authors.forename: Peter
authors.initials: P
authors.lastname: Park
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Amato
mesh_terms: D000328:Adult; D000368:Aged; D001808:Blood Vessels / Q000378:metabolism; D017252:CD3 Complex / Q000096:biosynthesis; D015704:CD4 Antigens / Q000096:biosynthesis; D003713:Dendritic Cells / Q000473:pathology; D003882:Dermatomyositis / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology*; D005260:Female; D019204:GTP-Binding Proteins / Q000096:biosynthesis; D005786:Gene Expression Regulation / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D016898:Interferon-alpha / Q000502:physiology*; D016899:Interferon-beta / Q000502:physiology*; D037181:Lectins, C-Type / Q000096:biosynthesis; D008297:Male; D008562:Membrane Glycoproteins; D016253:Microscopy, Immunoelectron; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000473:pathology / Q000503:physiopathology; D018979:Myositis, Inclusion Body / Q000473:pathology; D064547:Myxovirus Resistance Proteins; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D009468:Neuromuscular Diseases / Q000473:pathology / Q000503:physiopathology; D020411:Oligonucleotide Array Sequence Analysis; D011401:Promoter Regions, Genetic / Q000235:genetics; D011446:Prospective Studies; D011971:Receptors, Immunologic; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D017252:CD3 Complex; D015704:CD4 Antigens; C443299:CLEC4C protein, human; D016898:Interferon-alpha; D037181:Lectins, C-Type; C579071:MX1 protein, human; D008562:Membrane Glycoproteins; D064547:Myxovirus Resistance Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D016899:Interferon-beta; D019204:GTP-Binding Proteins