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PubMed1993

Treatment of inclusion-body myositis with high-dose intravenous immunoglobulin.

We report the treatment of four patients with inclusion-body myositis (IBM) and severe slowly progressive weakness using high-dose intravenous immunoglobulin (IVIg). After two monthly infusions, the strength of the proximal and less atrophic muscle groups improved or normalized in three of the four patients. The improvement lasted from 2 to 4 months. Intravenous immunoglobulin is the first treatment modality to improve the strength of some muscles in patients with this disabling inflammatory myopathy. In view of the high cost of IVIg, the unexpected but encouraging results from this pilot study warrant a controlled trial.

Creatine Kinase↗

PubMed1993

Inclusion body myositis presenting solely as dysphagia.

Two patients presenting with dysphagia due to cricopharyngeal muscle dysfunction developed limb weakness 2 to 3 years later. Cricopharyngeal and limb muscle biopsies demonstrated changes typical of inclusion body myositis (IBM). Both patients improved following cricopharyngeal myotomy. IBM should be considered in patients presenting with dysphagia.

Biopsy↗

PubMed1995

Inclusion body myositis presenting with isolated erector spinae paresis.

We report a 70-year-old patient who presented with a 4-year history of weakness of paravertebral muscles. Electrodiagnostic studies revealed a mixed neurogenic-myopathic pattern. Light microscopic examination revealed atrophic fibers with rimmed vacuoles; electron microscopy demonstrated cytoplasmic and intranuclear filaments measuring about 16 nm in width, consistent with the diagnosis of inclusion body myositis. Therapy with corticosteroids provided only a mild and transient benefit. Ten months after the initial evaluation, clinical and electrodiagnostic examination demonstrated mild progression of the disease.

Aged↗

PubMed1995

Inclusion body myositis: explanation for poor response to immunosuppressive therapy.

We treated eight patients who had inclusion body myositis (IBM) with oral prednisone therapy, and we performed muscle biopsies before and after treatment. We documented the patients' clinical response to therapy and changes in serum CK. Although the serum CK level fell, muscle strength worsened after prednisone treatment. In addition, while inflammation decreased in the muscle biopsy specimens, the number of vacuolated and amyloid-positive fibers increased after oral prednisone therapy. These observations indicate that the inflammatory response in IBM may play a secondary role in the pathogenesis of IBM. The unique findings of intracellular amyloid deposits and rimmed vacuoles distinguishing IBM from other inflammatory myopathies, and recognition that suppression of inflammation has no effect on the clinical course, suggest that IBM may represent a degenerative muscle disorder.

Aged↗

PubMed1997

Inclusion body myositis: no evidence for a neurogenic component.

Because electrophysiologic, clinical, and histopathologic observations have suggested that inclusion body myositis (IBM) may have a coexistent neurogenic component, we used macro-electromyography (macro-EMG) to search for changes in the motor unit territory and signs of reinnervation. We studied 11 patients, aged 53 to 77 years (mean, 65.2 years), with typical, nonfamilial IBM lasting a mean of 8.5 years, and eight healthy volunteers aged 54 to 70 years (mean, 64.6 years), as control subjects. Nerve conduction studies showed focal abnormalities in 5 of the patients, but no evidence of a polyneuropathy. Concentric needle EMG in various proximal and distal muscles of the upper and lower limbs revealed short- or long-duration complex motor unit potentials (MUPs) or a mixture of both types of MUPs. Macro-EMG studies in the tibialis anterior muscle showed smaller macro-MUP amplitudes and areas in patients than in normal subjects. Four patients had abnormal macro-EMG studies with an increased number of small macro-MUPs, 1 patient had an equivocal study with large-amplitude but normal-area macro-MUPs, and the remaining 6 patients had normal studies. These findings are consistent with a primary muscle disorder similar to those seen in other myopathies. We conclude that macro-EMG does not support a coexistent neurogenic component in patients with IBM compared with normal subjects of similar age.

Aged↗

PubMed1997

Treatment of inclusion-body myositis with IVIg: a double-blind, placebo-controlled study.

We randomized 19 patients with inclusion-body myositis (IBM) to a double-blind, placebo-controlled, crossover study using monthly infusions of 2 g/kg intravenous immunoglobulin (IVIg) or placebo for 3 months. Patients crossed over to the alternate treatment after a washout period. We evaluated responses at baseline and at the end of each treatment period using expanded (0-10) MRC scales, the Maximum Voluntary Isometric Contraction (MVIC) method, symptom and disability scores, and quantitative swallowing studies. We calculated the differences in scores between IVIg and placebo from baseline to end of treatment. Of the 19 patients, 9 (mean age, 61.2 years; mean disease duration, 5.6 years) were randomized to IVIg and 10 (mean age, 66.1 years; mean disease duration, 7.4 years) to placebo. During IVIg the patients gained a mean of 4.2 (-16 to +39.8) MRC points, and during placebo lost 2.7 (-10 to +8) points (p < 0.1). These gains were not significant. Similar results were obtained with the MRC and MVIC scores when the patients crossed to the alternate treatment. Six patients had a functionally important improvement by more than 10 MRC points that declined when crossed over to placebo. Limb-by-limb analysis demonstrated that during IVIg the muscle strength in 39% of the lower extremity limbs significantly increased compared with placebo (p < 0.05), while a simultaneous decrease in 28% of other limbs was detected. The clinical importance of these minor gains is unclear. The duration of swallowing functions measured in seconds with ultrasound improved statistically in the IVIg-randomized patients (p < 0.05) compared with placebo. Although the study did not establish efficacy of IVIg, possibly because of the small sample size, the drug induced functionally important improvement in 6 (28%) of the 19 patients. Whether the modest gains noted in certain muscle groups justify the high cost of trying IVIg in IBM patients at a given stage of the disease remains unclear.

Activities of Daily Living↗

PubMed1997

Magnetic resonance imaging of the forearm as a diagnostic aid in patients with sporadic inclusion body myositis.

Because weakness of finger flexors and atrophy of the forearms are frequent findings in inclusion body myositis (IBM) patients, we examined the forearm muscles by MRI to determine if involvement of the distal musculature has a characteristic diagnostic pattern. We performed MRI of the forearms in 21 randomly selected patients with histologically confirmed IBM and in 9 patients with other, age-matched, neuromuscular diseases who served as controls. In addition, we analyzed axial images of 10 individual forearm muscles blindly without knowledge of the clinical status or diagnosis of the patients. T1-weighted MR images showed marbled brightness of the flexor digitorum profundus (FDP) in 20 of 21 IBM patients, of the flexor carpi ulnaris in 7, the flexor digitorum superficialis (FDS) in 6, the flexor carpi radialis in 4, the supinator in 3, and the brachioradialis in 1. The extensors were normal. The abnormalities of the FDP correlated with the severity but not the duration of the disease and in some patients preceded overt clinical signs of FDP weakness. In contrast, the FDS was spared even late in the disease. We conclude that selective involvement of the FDP may occur early in the course of IBM and can be easily demonstrated by MRI in up to 95% of patients. Because selective FDP involvement appears to be a very frequent and characteristic finding in patients with IBM, MRI of the forearm is a useful noninvasive test in supporting the diagnosis of sporadic IBM.

Adult↗

PubMed1998

Inclusion body myositis in twins.

Sporadic inclusion body myositis (s-IBM) is characterized by late onset of slowly progressive weakness that involves the quadriceps and volar forearm muscles early in the course of the disease. There are hereditary forms of inclusion body myopathy (h-IBM) that histologically resemble s-IBM. The lack of inflammation on biopsy and the different ages at onset and patterns of muscle weakness distinguish s-IBM from h-IBM. We report twin brothers with the typical clinical and histologic features of s-IBM. The occurrence of s-IBM in these twins suggests the possibility of a genetic susceptibility to developing s-IBM.

Age of Onset↗

PubMed1998

Controlled studies with high-dose intravenous immunoglobulin in the treatment of dermatomyositis, inclusion body myositis, and polymyositis.

There are three major subsets of the inflammatory myopathies: polymyositis (PM), dermatomyositis (DM), and inclusion-body myositis (IBM). High-dose intravenous immunoglobulin (IVIg) has been tried in controlled clinical trials in patients with DM and IBM but not with PM. In patients with DM that is resistant or partially responsive to conventional therapies, IVIg was very effective. The treated patients experienced dramatic improvement not only in muscle strength but also of their skin rash. Repeated muscle biopsies with quantitative histologic studies showed the IVIg-treated patients had a statistically significant improvement of the muscle cytoarchitecture, with resolution of the aberrant immunopathologic parameters. In two controlled clinical trials conducted in IBM patients, IVIg showed marginal improvements in muscle strength which were nonsignificant. However, a few IBM patients had a definite clinical improvement with increased activities of daily living, but when analyzed within the entire IVIg-treated group, their total gains in muscle strength did not reach statistical significance compared to the placebo-treated group. Of interest is that certain muscle groups in the IVIg-treated patients, such as the muscles of swallowing, showed significant improvement compared to those of the placebo-treated patients, implying mild regional effects. In PM, uncontrolled trials have shown improvements in muscle strength, but the controlled clinical trial is still ongoing.

Dermatomyositis↗

PubMed1999

Aberrant expression of cyclin-dependent kinase 5 in inclusion body myositis.

OBJECTIVE: To investigate abnormal protein expression in inclusion body myositis (IBM). BACKGROUND: In IBM, ectopic deposition of beta-amyloid protein as well as several other proteins in some muscle fibers occurs. Some, but not all, of these proteins are also expressed in myofibrillar myopathy (MFM). The authors recently reported aberrant expressions of several cyclin-dependent kinases (CDKs)-enzymes regulating the cell replication cycle-in MFM. They therefore tested the notion that aberrant expression of CDKs also occurs in IBM. Among CDKs, CDK1, CDK2, and CDK5 have been demonstrated to phosphorylate tau, which is a component of inclusions in IBM. CDK5 appears in a stage of myogenesis when CDK1 and CDK2 are downregulated. METHODS: Cryostat sections of muscle specimens from 10 patients with sporadic IBM were immunostained for CDK1, CDK2, and CDK5. Fourteen patients with polymyositis and eight individuals with dermatomyositis served as disease control subjects. RESULTS: In IBM, numerous CDK5-positive inclusions were present in vacuolated fibers. CDK5 expression was not observed in any disease control subject. Regenerating fibers expressed CDK1 and CDK2 in all diseases. CONCLUSION: The results suggest that cyclin-dependent kinases (CDK)5, but no other CDKs, is involved in the formation of inclusions in IBM.

Adult↗

PubMed1999

Cultured inclusion-body myositis muscle fibers do not accumulate beta-amyloid precursor protein and can be innervated.

Cultured muscle fibers from patients with sporadic inclusion-body myositis (s-IBM), similar to normal control muscle fibers, 1) did not have beta-amyloid precursor protein (betaAPP) immunoreactivity; and 2) became normally innervated, as evidenced by the following features: full cross-striation, continuous contraction, and acetylcholinesterase and acetylcholine receptors accumulated only at neuromuscular junctions. Thus, factors responsible for betaAPP accumulation and denervation-like changes in s-IBM muscle biopsies are not operative in the relatively short-term, non-aged, cultured s-IBM muscle fibers.

Aged↗

PubMed2000

AlphaB-crystallin immunolocalization yields new insights into inclusion body myositis.

OBJECTIVE: To study the expression of the small heat shock protein, alphaB-crystallin (alphaBC), in inclusion body myositis (IBM). BACKGROUND: In humans, alphaBC is constitutively expressed in the eye lens, muscle, and heart, but not in lymphoid tissues. Induced expression of alphaBC occurs under metabolic stress, in virus-infected lymphocytes, and in degenerative brain lesions, including neurofibrillary tangles and senile plaques in AD. The previously reported pathologic similarities between AD and IBM prompted us to study alphaBC expression in IBM. METHODS: Immunolocalization of alphaBC in muscle of 11 patients with IBM, 50 patients with other muscle diseases, and 4 controls; and quantitative analysis of the frequency of fibers with 1) increased alphaBC expression in IBM and polymyositis and 2) structural abnormality (vacuolated, non-necrotic and invaded by mononuclear cells, Congo red-positive, SMI-31 positive, and ubiquitin positive) in IBM. RESULTS: We detected enhanced expression of alphaBC not only in all structurally abnormal IBM fibers, but also, and with severalfold higher frequency, in IBM fibers without significant structural abnormality (X fibers) (p values in paired t-tests < 0.001). We also found enhanced alphaBC in abnormal fibers in other diseases; X fibers, however, were extremely sparse or absent, except in two atypical cases of polymyositis refractory to immunotherapy. CONCLUSION: That the X fibers are much more frequent than the structurally abnormal fibers in IBM points to a pathogenic stressor acting upstream to the development of structural abnormalities. The identification of this stressor is now of paramount importance for deciphering the enigma of IBM.

Adult↗

PubMed2000

The muscle mitogen-activated protein kinase is altered in sporadic inclusion body myositis.

OBJECTIVE: To examine the origin of hyperphosphorylated proteins within the vacuolated myofibers in sporadic inclusion body myositis (s-IBM) and search for dysregulated intracellular protein phosphorylation. BACKGROUND: s-IBM is morphologically characterized by primary endomysial inflammation and vacuolated myofibers containing tubulofilaments that originate from cytoskeletal proteins. Mitogen-activated protein kinases (MAPKs) play a role in regulating phosphorylation and maintaining the stability of the cytoskeletal architecture. METHODS: Muscle biopsies from seven patients with s-IBM and 15 controls were examined for the expression of the active components of the various MAPKs, including p44/42MAPK, p38MAPK, p46JNK1, p54JNK2, and p54JNK3, using immunocytochemistry and Western blot analysis. The expression of selected phosphorylated components was also examined in the same specimens. RESULTS: In s-IBM, but not the disease controls, the vacuolated muscle fibers express active p42MAPK but not JNK or p38MAPK. Western blots of cell lysates confirmed the hyperexpression of p42MAPK and demonstrated a novel 35 kD phosphoprotein. Antibodies against phosphoepitopes of the 35 kD protein preferentially immunostained antigens within the vacuolated muscle fibers of s-IBM but not disease controls. CONCLUSION: In s-IBM, there is increased p42MAPK activation and abnormal intracellular protein phosphorylation with selective accumulation of a 35 kD phosphoprotein within the vacuolated fibers. Although the hyperexpression of 35kD protein may represent cytoskeletal by-products due to heightened p42MAPK activation, its abundant expression only in s-IBM implies that hyperphosphorylated myofibrillar proteins may be involved in the primary disease process.

Aged↗

PubMed2000

Adeno-associated virus in normal and myositis human skeletal muscle.

The normal tissue tropism of adeno-associated virus (AAV) is poorly defined, although the majority of humans test seropositive for this virus. Eighty-five muscle biopsy specimens were tested for AAV genomes; AAV DNA was identified in 17% of normal and 10% of Duchenne muscular dystrophy muscle biopsy specimens, but in only 3% of peripheral blood samples. AAV genomes were absent from all 37 muscle biopsy specimens from patients with myositis tested. Muscle is a major target organ for AAV, and infection is associated with autoimmune disease of muscle.

Adolescent↗

PubMed2000

Disease progression in sporadic inclusion body myositis: observations in 78 patients.

Functional decline for each decade at symptom onset and need for cane, walker, or wheelchair were assessed in 78 biopsy-proved patients with sporadic inclusion body myositis. Patients with disease onset between 40 and 59 years used a walker after 10.2 +/- 5.8 years, whereas those with disease onset between 60 and 79 years used a walker after 5.7 +/- 5.0 years (p = 0.05). Because patients progress faster to disability when symptoms begin after the age of 60, age at disease onset may define patient subsets for stratification in clinical trials.

Adult↗

PubMed2000

Epidemiology of inclusion body myositis in the Netherlands: a nationwide study.

Epidemiologic data on inclusion body myositis (IBM) are scarce, and possibly biased, because they are derived from larger neuromuscular centers. The present nationwide collaborative cross-sectional study, which culminated on July 1, 1999, resulted in identification of 76 patients with IBM and the establishment of a prevalence of 4.9 patients with IBM per million inhabitants in the Netherlands. Several discrepancies suggest that this may be an underestimation. The most frequently identified pitfall in diagnosing IBM was an erroneous diagnosis of polymyositis or motor neuron disease.

Adult↗

PubMed2001

Inclusion body myositis: expression of extracellular signal-regulated kinase and its substrate.

OBJECTIVE: To assess abnormal intracellular signal transduction in inclusion body myositis (IBM). BACKGROUND: Mitogen-activated protein kinases (MAPKs) play pivotal roles in intracellular signal transduction and regulate cell growth and differentiation. Upon their activation, MAPKs translocate from the cytoplasm into the nucleus. DESIGN/METHODS: The authors investigated the localization of several forms of the MAPK family-extracellular signal-regulated kinase (ERK), c-Jun N-terminal protein kinase (JNK), and p38 MAPK (p38)-in 10 patients with sporadic IBM and in 52 control subjects. The relationship between the localization of immunopositive deposits and nuclei was tested with bis-benzimide. RESULTS: Vacuolated fibers in IBM displayed very strong focal immunoreactivity of ERK, but not of JNK or p38. The ERK-positive deposits in these vacuolated fibers colocalized with the nuclear substrate of ERK, Elk-1. ERK- and Elk-1-positive deposits were located frequently on the surface of the nuclei in vacuolated fibers in IBM. Similar findings to those of sporadic IBM were observed in three patients with distal myopathy with rimmed vacuoles, but not in eight normal or the other 41 disease controls. CONCLUSION: There is evidence for impaired molecular transport to the nucleus from the cytoplasm in the vacuolated fibers in IBM. This could be due to cytoplasmic aggregation of ERK and Elk-1 or to abnormal nuclear pore machinery involved in the transport of ERK and its substrate upon ERK activation.

Adult↗

PubMed2001

A prospective natural history study of inclusion body myositis: implications for clinical trials.

Eleven patients with untreated inclusion body myositis (IBM) were prospectively studied during a 6-month period that included muscle strength, lean body mass, and muscle mass measurements. There was an overall quantifiable mean decline in percent of predicted normal muscle strength of 4% from baseline in a 6-month period, but one third of patients showed no change or slight improvements in strength. Short-term treatment trials in IBM will require large numbers of patients to detect slowing, arrest, or even slight improvement in muscle strength.

Aged↗