Anna Nishimura (Gießen / DE), Dr. Alexander Mensch (Halle (Saale) / DE), Melanie Huber (Gießen / DE), Dr. Rebecca Hasseli-Fräbel (Gießen / DE), Angela Roth (Gießen / DE), PD Dr. Eva Neuen-Jacob (Düsseldorf / DE), Prof. Dr. Heidrun H. Krämer (Gießen / DE), Prof. Dr. Ulf Müller-Ladner (Gießen / DE), Prof. Dr. med Werner Stenzel (Berlin / DE), PD Dr. med. Tobias Ruck (Düsseldorf / DE), Prof. Dr. med Anne Schänzer (Gießen / DE)
Abstract-Text (inkl. Referenzen)
Background:Idiopathic inflammatory myopathies (IIM) are autoimmune diseases classified as dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), anti-synthetase syndrome (ASyS) and sporadic inclusion body myositis (sIBM). IIM subtypes follow different immune regulatory mechanisms necessitating adapted therapeutic strategies. Analyzing immune regulating proteins in skeletal muscle tissues increases the understanding of the underlying pathomechanisms.
Methods:Skeletal biopsies from adult patients (n=25) (average age 53.5 years; 57.14% female) with diagnosis of IIM (6 DM; 5 IMNM; 7 ASyS; 7 sIBM), neurogenic atrophy (NA; n=2) and controls (HC; n=6) were included in our study. Immunofluorescence staining was performed with antibodies against MHC class I, MHC class II, ICAM-1 and VCAM-1. The sections were subsequently digitalized using a Zeiss Axio Scan.Z1 slide scanner. Co-expression with skeletal muscle proteins (spectrin, desmin) or endomysial capillaries (CD31) were quantified on digitized whole sections using Fiji software.
Results/Conclusion:Analysis of digitized whole sections provides accurate data on entire skeletal muscle crosssections in comparison to evaluation of focal staining. Lower expression of MHC class I in IMNM suggests a different pathogenesis compared to other IIM. Upregulation of ICAM-1 on endomysial capillaries in both DM and ASyS suggests shared pathogenic pathways. Hence, both DM and ASyS might be amenable to similar therapeutic approaches.