Congophilic Inclusions Research Articles

Inclusion body myositis: correlation of clinical outcomes with histopathology, electromyography and laboratory findings.

To determine whether histopathological, electromyographic and laboratory markers correlate with clinical measures in inclusion body myositis (IBM). We reviewed our electronic medical records to identify patients with IBM according to European Neuromuscular Center (ENMC) 2011 criteria, seen between 2015 and 2020. We only included patients who had a muscle biopsy and needle electromyography (EMG) performed on the same muscle (opposite or same side). We used a detailed grading system [0 (normal) to 4 (severe)] to score histopathological and EMG findings. Clinical severity was assessed by the modified Rankin scale (mRS), muscle strength sum score (SSS), quadriceps strength and severity of dysphagia on swallow evaluation. Serum markers of interest were creatine kinase level and cN-1A antibodies. We included 50 IBM patients, with a median age of 69 years; 64% were males. Median disease duration at diagnosis was 51 months. On muscle biopsy, endomysial inflammation mainly correlated with dysphagia, and inversely correlated with mRS. Vacuoles and congophilic inclusions did not correlate with any of the clinical measures. On EMG, the shortness of motor un it potential (MUP) duration correlated with all clinical measures. Myotonic discharges, and not fibrillation potentials, correlated with the severity of inflammation. Serum markers did not have a statistically significant correlation with any of the clinical measures. Dysphagia was the main clinical feature of IBM correlating with endomysial inflammation. Otherwise, inclusion body myositis clinical measures had limited correlation with histopathological features in this study. The shortness of MUP duration correlated with all clinical measures.

Interstitial amyloidosis in sporadic inclusion body myositis.

Intracellular congophilic inclusions within muscle fibers, although nonspecific, are one of the pathological hallmarks of sporadic inclusion body myositis (sIBM). Extracellular amyloid deposits in muscle, on the other hand, are the canonical findings of amyloid myopathies, which occur with or without systemic amyloidosis. We reviewed the muscle biopsy database (1998-2020) to identify sIBM patients with extracellular amyloid deposits. Clinical and laboratory data were reviewed. We identified five sIBM patients (three clinicopathologically defined and two clinically defined) with extracellular amyloid deposits in muscle. Mean age at diagnosis was 74.8y (range, 68-84 y). All patients had a typical sIBM pattern of weakness without associated sensory or autonomic symptoms. None had electrophysiological evidence of peripheral neuropathy. Only one patient had a monoclonal gammopathy (immunoglobulin M-lambda, IgM-λ) with normal bone marrow biopsy. This patient with monoclonal gammopathy and three other patients underwent abdominal fat pad aspirate and were negative for amyloid. Cardiac evaluation was unrevealing in the four patients tested. Three patients without monoclonal gammopathy had normal transthyretin gene sequencing and inconclusive mass spectrometry-based analysis. The patient with monoclonal gammopathy died of pneumosepsis 5y after diagnosis and autopsy revealed multi-organ transthyretin amyloidosis. Detection of extracellular amyloid deposition in muscle should trigger an aggressive search for systemic amyloidosis independently from other associated myopathological abnormalities. Amyloid subtyping is crucial for early therapy and mortality prevention. An isolated monoclonal gammopathy should not halt a search for non-hematological causes of systemic amyloidosis.

P.21Genetic analysis of first-degree relatives with inclusion body myositis

Inclusion body myositis (IBM) is a sporadic clinicopathologically defined myopathy characterised by finger flexor and quadriceps weakness, along with the histological triad of endomysial autoaggressive inflammation, rimmed vacuoles and protein aggregates. Rare familial occurrences of IBM have however been reported. We have identified 3 such families. Families 1 and 2 consisted of pairs of affected siblings, while family 3 consisted of a mother and her two children. The onset of symptoms was between 55 and 73 years. Patients displayed finger flexion greater than shoulder abduction and/or quadriceps greater than iliopsoas weakness. One individual in family 3 developed amyotrophic lateral sclerosis (ALS) 5 years after the diagnosis of IBM. An autoaggressive endomysial inflammatory infiltrate was present in all patients, while congophilic inclusions and rimmed vacuoles were observed in 6 and 5 patients, respectively. Anti-cytosolic 5′-nucleotidase 1A (cN1A) antibodies were present in the only 2 patients tested. Whole genome sequencing was performed in all patients and failed to identify causative variants in well-characterised Mendelian myopathy genes, including myopathies with rimmed vacuoles. The two siblings of family 1 both carried a heterozygous frameshift variant in TANK binding kinase 1 (TBK1). In the other 2 families, no candidate variant has so far been identified. Loss-of-function variants in TBK1 have recently been reported to cause ALS. TBK1 is a ubiquitously-expressed protein kinase known to regulate autophagy, mitophagy, neuroinflammation and adipose tissue energy metabolism. Several of these pathways have been hypothesised to play a role in the development of IBM. Further research is therefore warranted to explore the role of TBK1 in the pathogenesis of both familial and sporadic IBM.

Myopathies featuring non-caseating granulomas: Sarcoidosis, inclusion body myositis and an unfolding overlap

Granulomatous myopathies are etiologically heterogeneous myopathies, pathologically characterized by the presence of intramuscular granulomas. Treatment outcomes are variable. We aimed to identify prognostic factors of treatment outcomes in myopathies featuring non-caseating granulomas. Sixteen patients were identified (9 sarcoid myopathy, 6 inclusion body myositis, and 1 granulomatous myopathy of indeterminate cause) over a 21-year period. The median age at diagnosis was 67 years in sarcoid myopathy group, and 64 years in inclusion body myositis group. Three inclusion body myositis patients were initially diagnosed with sarcoid myopathy based on the presence of systemic features of sarcoidosis and findings on muscle biopsies, but subsequent biopsies performed because of treatment refractoriness, showed all canonical pathologic features of inclusion body myositis. We identified sarcoplasmic congophilic inclusions in 6 sarcoid myopathy patients without associated rimmed vacuoles or typical weakness pattern of inclusion body myositis. Four inclusion body myositis and 4 of 5 sarcoid myopathy patients with congophilic inclusions were refractory to immunotherapy. Our study portrays the overlapping clinical and pathological features of sarcoid myopathy and inclusion body myositis. The presence of sarcoplasmic congophilic inclusions in sarcoid myopathy may predict an unfavorable outcome of immunosuppressive therapy, but a larger prospective study is required to further validate this observation.

Muscle Biopsy and Electromyography Correlation.

Introduction: In myopathies, the correlation of individual electromyographic and histopathologic findings remains poorly explored, as most previous studies have focused on the ability of muscle biopsy and electromyography to distinguish the neuropathic vs. myopathic nature of the underlying neuromuscular disease.Methods: We identified 100 patients who had a muscle biopsy and electromyography performed on identical muscles. We used a detailed grading system ranging from 0- normal to 4- severe; and graded 16 histopathologic findings in each biopsy. Electromyography findings were also graded from 0 to 4 according to the standard protocol in our EMG laboratory. We used Kendall's tau for non-parametric ordinal correlation analysis.Results: Fibrillation potentials correlated with atrophic, necrotic, and regenerating fibers, fibers harboring vacuoles, fiber splitting, fibers reacting for non-specific esterase, fibers with congophilic inclusions, inflammation (endoymysial and perimysial), and increased endomysial connective tissue. Short-duration motor unit potentials correlated with atrophic, necrotic, and regenerating fibers, increased endomysial connective tissue, and perimysial inflammation. Long-duration motor unit potentials correlated with fiber-type grouping. Increased phases of motor unit potentials correlated with atrophic fibers, increased endomysial connective tissue, and fibers reacting for non-specific esterase; while increased turns correlated with atrophic and regenerating fibers, increased endomysial connective tissue and target formations. Rapid recruitment correlated with regenerating fibers, perimysial inflammation, and increased endomysial connective tissue.Discussion: By demonstrating a clear correlation of various electromyographic and histopathologic findings, this study improves interpreting electrodiagnostic testing in myopathies, and serves as the basis to further assess the correlation between clinical, electromyographic, and histopathologic findings.

G.P.315 - Coexisting TIA1 and MYH7 distal myopathy

Distal myopathies are genetically heterogeneous. TIA1 mutations cause Welander distal myopathy. MYH7 mutations result in various clinical phenotypes, including Laing distal myopathy, myosin storage myopathy and hypertrophic/dilated cardiomyopathy. We describe a family affected by distal myopathy and variable presence of cardiomyopathy due to coexisting TIA1 and MYH7 mutations. The propositus is a 67-year-old woman of Swedish and Greek descent with history of easy tripping since childhood who has experienced a stepwise progression of asymmetric distal limb weakness in the past 20 years. Neurological examination revealed mild to severe asymmetric distal lower >upper limb weakness. CK value was normal. EMG study showed myopathic changes with minimal fibrillation potentials and myotonic discharges. Biopsy of the extensor carpi radialis muscle showed: rare rimmed vacuoles, minicore-like structures and congophilic inclusions; few necrotic and regenerating fibers; fiber splitting; increased internal nuclei; and fiber type grouping. There was no cardiac involvement by ECG and echocardiogram. Her 66-year-old sister has 8 years of mild distal limb weakness, supraventricular tachycardia and hypertrophic cardiomyopathy documented by echocardiogram and MRI. Another sibling has distal weakness while parents were asymptomatic. Both sisters carry a known pathogenic heterozygous TIA1 mutation (p.Glu384Lys) and a rare heterozygous MYH7 variant (c.5459G > A; p.Arg1820Gln), which involves a highly conserved residue and is predicted to be pathogenic. Because a homozygous MYH7 mutation (p.Arg1820Trp) was reported in recessive myosin storage myopathy, aCGH deletion/duplication analysis of MYH7 was performed in the proband and it was normal. The clinical phenotype is dictated by the coexistent TIA1 and MYH7 mutations, which can result in similar pathological findings. The proband's early onset of distal leg weakness and the sister's cardiomyopathy support the pathogenicity of the MYH7.

DNAJB6 myopathy: A vacuolar myopathy with childhood onset

DNAJB6 mutations cause an autosomal dominant myopathy that can manifest as limb-girdle muscular dystrophy (LGMD1D/1E) or distal-predominant myopathy. In the majority of patients this myopathy manifests in adulthood and shows vacuolar changes on muscle biopsy. Clinical, electrophysiological, pathological, and molecular findings are reported. We report a 56-year-old woman, who, like 3 other family members, became symptomatic in childhood with slowly progressive limb-girdle muscle weakness, normal serum creatine kinase (CK) values, and myopathic electromyographic findings. Muscle biopsy showed vacuolar changes and congophilic inclusions, and molecular analysis revealed a pathogenic mutation in the DNAJB6 gene. Differences and similarities with previously described cases are assessed. Childhood-onset of DNAJB6 myopathy is more frequent than previously believed; congophilic inclusions may be present in the muscle of these patients.

A Novel Autosomal Dominant Inclusion Body Myopathy Linked to 7q22.1-31.1

We describe a novel autosomal dominant hereditary inclusion body myopathy (HIBM) that clinically mimics limb girdle muscular dystrophy in a Chinese family. We performed a detailed clinical assessment of 36 individuals spanning four generations. The age of onset ranged from the 30s to the 50s. Hip girdle, neck flexion and axial muscle weakness were involved at an early stage. This disease progressed slowly, and a shoulder girdle weakness appeared later in the disease course. Muscle biopsies showed necrotic, regenerating, and rimmed vacuolated fibers as well as congophilic inclusions in some of the fibers. Electron micrograph revealed cytoplasmic inclusions of 15–21 nm filaments. A genomewide scan and haplotype analyses were performed using an Illumina Linkage-12 DNA Analysis Kit (average spacing 0.58 cM), which traced the disease to a new locus on chromosome 7q22.1–31.1 with a maximum multi-point LOD score of 3.65. The critical locus for this unique disorder, which is currently referred to as hereditary inclusion body myopathy 4 (HIBM4), spans 8.78 Mb and contains 65 genes. This localization raises the possibility that one of the genes clustered within this region may be involved in this disorder.

Increased aging in primary muscle cultures of sporadic inclusion-body myositis

Ageing is thought to participate to the pathogenesis of sporadic inclusion-body myositis (s-IBM). Although the regenerative potential of s-IBM muscle is reduced in vivo, age-related abnormalities of satellite cells possibly accounting for the decline of muscle repair have not been demonstrated. Here we show that proliferation rate and clonogenicity of s-IBM myoblasts are significantly lower and doubling time is longer than normal age-matched controls, indicating that proliferative capacity of s-IBM muscles becomes exhausted earlier. Telomere shortening is detected in s-IBM cells suggesting premature senescence. Differently from controls, s-IBM myoblasts show increased active beta-catenin mainly localized within myonuclei, indicating active Wnt stimulation. After many rounds of muscle growth, only s-IBM myoblasts accumulate congophilic inclusions and immunoreactive Abeta(1-40) deposits. Therefore, s-IBM myoblasts seem to have a constitutively impaired regenerative capacity and the intrinsic property, upon sufficient aging in vitro, to accumulate Abeta. Our results might be valuable in understanding molecular mechanisms associated with muscle aging underlying the defective regeneration of s-IBM muscle and provide new clues for future therapeutic strategies.

Age-related congophilic inclusions in the brains of apolipoprotein E-deficient mice

The hippocampal region of apolipoprotein E-deficient mice of varying ages was examined for any morphological changes by light and electron microscopy. Unusual periodic acid–Schiff-positive granules were seen in the hippocampal area of these animals as early as the fourth week of life and their numbers increased gradually with age. These granules were never found in control C57BL/6J (B6) mice before six months-of-age and their numbers were invariably low. They were strongly congophilic when stained with a modified Congo Red technique and reacted with a monoclonal antibody specific to amino acids 17–24 and 35–43 of the β-amyloid peptide. The immunostaining of these granules with the β-amyloid peptide was lost after specific adsorption with the appropriate synthetic peptide. These granules were identified ultrastructurally as non-membrane-bound fibrillogranular material in the cytoplasm of protoplasmic astrocytes. The data indicate that an amyloid-like protein accumulates in the protoplasmic astrocytes of the hippocampus of apolipoprotein E-deficient mice, especially in the brains of old animals.

Age-related accumulation of congophilic fibrillar inclusions in endocrine cells

Intracellular fibrillar congophilic inclusions are well known as neurofibrillary tangles in neurons and as Biondi bodies in choroid plexus epithelial cells. Recently similar amyloid-like inclusions in adrenal cortical cells were described (Eriksson and Westermark 1990). This study on 150 adrenal glands confirms these observations. In our material the age-related accumulation of congophilic inclusions starts earlier (in the sixth decade) and reaches a higher incidence (42.7%). We found similar intracellular inclusions in other endocrine organs, for example in the anterior lobe of the pituitary, in the cells of parathyroid glands and in Sertoli cells. The age-related incidence of these fibrillar inclusions in the pituitary was 68%: the co-incidence with interstitial amyloid deposits was 49.5%. Thus the intracellular accumulation of congophilic fibrils in old age is a wide-spread phenomenon and occurs not only in neurons but also in endocrine cells (adrenal, pituitary and parathyroid glands) and in active secretory cells (choroid plexus and Sertoli cells).