The value of muscle biopsies in Pompe disease: Identifying lipofuscin inclusions in juvenile- and adult-onset patients
Journal
Acta Neuropathologica Communications
Journal Volume
2
Journal Issue
1
Pages
2
Date Issued
2014
Author(s)
Feeney E.J.
Austin S.
Mandel H.
Schoser B.
Prater S.
Ralston E.
Kishnani P.S.
Raben N.
Abstract
Background: Pompe disease, an inherited deficiency of lysosomal acid alpha-glucosidase (GAA), is a metabolic myopathy with heterogeneous clinical presentations. Late-onset Pompe disease (LOPD) is a debilitating progressive muscle disorder that can occur anytime from early childhood to late adulthood. Enzyme replacement therapy (ERT) with recombinant human GAA is currently available for Pompe patients. Although ERT shows some benefits, the reversal of skeletal muscle pathology - lysosomal glycogen accumulation and autophagic buildup - remains a challenge. In this study, we examined the clinical status and muscle pathology of 22 LOPD patients and one atypical infantile patient on ERT to understand the reasons for muscle resistance to ERT. Results: The patients were divided into three groups for analysis, based on the age of onset and diagnosis: adult-onset patients, juvenile-onset patients, and those identified through newborn screening (NBS). The areas of autophagic buildup found in patients' biopsies of all three groups, contained large autofluorescent inclusions which we show are made of lipofuscin, an indigestible intralysosomal material typically associated with ageing. These inclusions, analysed by staining, spectral analysis, time-resolved Fluorescence Lifetime Imaging (FLIM), and Second Harmonic Generation (SHG) imaging, were the major pathology remaining in many fibers after ERT. The best outcome of ERT both clinically and morphologically was observed in the NBS patients. Conclusions: The muscle biopsy, in spite of its shortcomings, allowed us to recognize an underreported, ERT-resistant pathology in LOPD; numerous lysosomes and autolysosomes loaded with lipofuscin appear to be a hallmark of LOPD skeletal muscle. Lipofuscin accumulation - a result of inefficient lysosomal degradation - may in turn exacerbate both lysosomal and autophagic abnormalities. ? 2014 Feeney et al.; licensee BioMed Central Ltd.
SDGs
Other Subjects
lipofuscin; lysosome associated membrane protein 2; adult; autophagy; biopsy; cell inclusion; early diagnosis; female; glycogen storage disease type 2; human; male; metabolism; middle aged; onset age; pathology; physiology; skeletal muscle; Adult; Age of Onset; Autophagy; Biopsy; Early Diagnosis; Female; Glycogen Storage Disease Type II; Humans; Inclusion Bodies; Lipofuscin; Lysosomal-Associated Membrane Protein 2; Male; Middle Aged; Muscle, Skeletal
Publisher
BioMed Central Ltd.
Type
journal article