Presence of BACE1 and BACE2 in muscle fibres of patients with sporadic inclusion-body myositis

Sporadic inclusion-body myositis (IBM) is the most common, progressive muscle disease of older individuals. We investigated the presence of BACE1 and BACE2—two β secretases that cleave amyloid-β-precursor protein—in muscle-biopsy samples from patients with IBM and from controls. On immunofluorescence, BACE1 and BACE2 co-localised with amyloid β in IBM vacuolated muscle fibres, but were not found in controls. Immunoblotting showed increased BACE2 but not BACE1 in patients with IBM compared with controls. Our study suggests that both of these proteases might participate in processing of amyloid-β-precursor protein in IBM muscle fibres.