title: Inflammatory myopathy with abundant macrophages (IMAM): the immunology revisited.
abstract: We describe a patient with a clinically atypical presentation of inflammatory myopathy with abundant macrophages (IMAM) but with convincing muscle biopsy features of this subform of inflammatory myopathy. IMAM is characterized mainly by a conspicuous infiltration of muscle and connective tissue by numerous macrophages remote from necrotic and basophilic regenerating muscle fibers. Typically few, mostly CD4(+) T helper (Th) cells are also present. Here, we report a patient with IMAM and demonstrate, that most macrophages express the macrophage mannose receptor 1 (CD206) corresponding to alternatively activated (M2) polarization. Accordingly, signal transducer and activator of transcription 6 (STAT6), involved in Th2-M2 immunity, was expressed at high levels in skeletal muscle. However, TNFα, IFNγ and STAT1, mediators of the T helper 1-classically activated (M1) response were elevated in skeletal muscle and in blood, while expression of CD206 was elevated in skeletal muscle only. Our results argue that IMAM could be a distinct entity between the inflammatory myopathies rather than a subform of dermatomyositis.
authors: Department of Neuropathology, Charité - Universitätsmedizin Berlin, Germany. Electronic address: jan-leo.rinnenthal@charite.de.
authors: Jan Leo
authors: JL
authors: Rinnenthal
authors: Department of Neuropathology, Charité - Universitätsmedizin Berlin, Germany.
authors: Hans-Hilmar
authors: HH
authors: Goebel
authors: Department of Neuropathology, Charité - Universitätsmedizin Berlin, Germany.
authors: Corinna
authors: C
authors: Preuße
authors: Department of Gastroenterology, Infectiology and Rheumatology, Campus, Benjamin Franklin, Charité - Universitätsmedizin Berlin, Germany.
authors: Lydia
authors: L
authors: Lebenheim
authors: Department of Gastroenterology, Infectiology and Rheumatology, Campus, Benjamin Franklin, Charité - Universitätsmedizin Berlin, Germany.
authors: Michael
authors: M
authors: Schumann
authors: Department of Gastroenterology, Infectiology and Rheumatology, Campus, Benjamin Franklin, Charité - Universitätsmedizin Berlin, Germany.
authors: Verena
authors: V
authors: Moos
authors: Department of Gastroenterology, Infectiology and Rheumatology, Campus, Benjamin Franklin, Charité - Universitätsmedizin Berlin, Germany.
authors: Thomas
authors: T
authors: Schneider
authors: Department of Neuropathology, Charité - Universitätsmedizin Berlin, Germany.
authors: Frank L
authors: FL
authors: Heppner
authors: Department of Neuropathology, Charité - Universitätsmedizin Berlin, Germany.
authors: Werner
authors: W
authors: Stenzel
mesh_terms: D001706:Biopsy; D003937:Diagnosis, Differential; D006801:Humans; D007150:Immunohistochemistry; D007371:Interferon-gamma / Q000097:blood / Q000378:metabolism; D037181:Lectins, C-Type / Q000378:metabolism; D008264:Macrophages / Q000276:immunology*; D008297:Male; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins / Q000378:metabolism; D018482:Muscle, Skeletal / Q000276:immunology* / Q000473:pathology*; D009220:Myositis / Q000097:blood / Q000175:diagnosis / Q000276:immunology* / Q000473:pathology*; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000097:blood / Q000378:metabolism; D050800:STAT6 Transcription Factor / Q000378:metabolism; D013848:Thigh; D014409:Tumor Necrosis Factor-alpha / Q000097:blood / Q000378:metabolism; D055815:Young Adult
chemical_list: D037181:Lectins, C-Type; D000090323:Mannose Receptor; D037241:Mannose-Binding Lectins; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D050794:STAT1 Transcription Factor; C494079:STAT1 protein, human; D050800:STAT6 Transcription Factor; C494101:STAT6 protein, human; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma
keywords: Dermatomyositis; IMAM; Inflammatory myopathy with abundant macrophages; Macrophage polarization; Membrane attack complex; Myositis