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PubMed2006

Raised troponin T in inclusion body myositis is common and serum levels are persistent over time.

Cardiac Troponin T (cTnT), creatine kinase (CK) and creatine kinase isoenzyme MB (CKMB) were measured in 42 consecutive patients with sporadic inclusion body myositis (s-IBM). 26 patients (62%) had a cTnT level >0.05 microg/L, the cut off used in the diagnosis of myocardial infarction. The cTnT levels correlated somewhat more closely to CKMB (rho=0.83, p<0.0001) than to CK (rho=0.60, p<0.0001). Patients on immunosuppressive treatment had lower cTnT levels than untreated, while there were no significant differences according to age, disease duration or gender. Repeated samples in 26 patients showed that the cTnT levels were essentially unchanged over time up to 17 months. None of the patients had signs of myocardial damage or renal failure at time of sampling. It may be of value to analyse cTnT at some occasion(s) in s-IBM patients.

Aged↗

PubMed2006

Familial inclusion body myositis in a mother and son with different ancestral MHC haplotypes.

An Ashkenazi Jewish family in which the mother and a son both have inclusion body myositis (IBM) is reported. The condition developed at an earlier age and was more rapidly progressive and less responsive to treatment in the son than in the mother or other IBM patients in our clinic. Genetic analysis showed that the mother carried alleles of the 8.1 MHC ancestral haplotype (AH; HLA-B8, DRB1*0301), which is found in 85% of IBM patients in Western Australia. The son did not inherit this haplotype, but carried alleles characteristic of the 52.1AH (HLA-B5, DRB1*1502) of paternal origin. The findings indicate that in this family either the 8.1AH or 52.1AH may carry susceptibility for IBM and that the 52.1AH is associated with a more severe and treatment-resistant form of the disease.

Alleles↗

PubMed2005

Proteasome inhibition and aggresome formation in sporadic inclusion-body myositis and in amyloid-beta precursor protein-overexpressing cultured human muscle fibers.

The 26S proteasome system is involved in eliminating various proteins, including ubiquitinated misfolded/unfolded proteins, and its inhibition results in cellular accumulation of protein aggregates. Intramuscle-fiber ubiquitinated multiprotein-aggregates are characteristic of sporadic inclusion-body myositis (s-IBM) muscle fibers. Two major types of aggregates exist, containing either amyloid-beta (Abeta) or phosphorylated tau (p-tau). We have now asked whether abnormalities of the 26S proteasome contribute to s-IBM pathogenesis and whether the multiprotein aggregates have features of aggresomes. Using cultured human muscle fibers we also studied the effect of amyloid-beta precursor protein (AbetaPP) overexpression on proteasome function and the influence of proteasome inhibition on aggresome formation. We report that in s-IBM muscle biopsies 26S proteasome subunits were immunodetected in the gamma-tubulin-associated aggresomes, which also contained Abeta, p-tau, ubiquitin, and HSP70. In addition, a) expression of proteasome subunits was greatly increased, b) the 20Salpha proteasome subunit co-immunoprecipitated with AbetaPP/Abeta, and c) the three major proteasomal proteolytic activities were reduced. In cultured muscle fibers, AbetaPP-overexpressing fibers displayed diminished proteasomal proteolytic activities, and addition of proteasome inhibitor strikingly increased aggresome formation. Accordingly, proteasome dysfunction in s-IBM muscle fibers may play a role in accumulation of misfolded, potentially cytotoxic proteins and may be induced by increased intracellular AbetaPP/Abeta.

Amyloid beta-Protein Precursor↗

PubMed2004

Endoplasmic reticulum stress and unfolded protein response in inclusion body myositis muscle.

Proteins in the endoplasmic reticulum (ER) require an efficient system of molecular chaperones whose role is to assure their proper folding and to prevent accumulation of unfolded proteins. The response of cells to accumulation of unfolded proteins in the ER is termed "unfolded protein response" (UPR). UPR is a functional mechanism by which cells attempt to protect themselves against ER stress, resulting from the accumulation of the unfolded/misfolded proteins. Because intracellular inclusions, containing either amyloid-beta (Abeta) or phosphorylated tau, are the characteristic feature of sporadic inclusion body myositis (s-IBM) muscle biopsies, we studied expression and immunolocalization of five ER chaperones, calnexin, calreticulin, GRP94, BiP/GRP78, and ERp72, in s-IBM and control muscle biopsies. Physical interaction of the ER chaperones with amyloid-beta precursor protein (AbetaPP) was studied by a combined immunoprecipitation/immunoblotting technique in s-IBM and control muscle biopsies, and in AbetaPP-overexpressing cultured human muscle fibers. In all s-IBM muscle biopsies, all five of the ER chaperones were immunodetected in the form of inclusions that co-localized with amyloid-beta. By immunoblotting, expression of ER chaperones was greatly increased as compared to the controls. By immunoprecipitation/immunoblotting experiments, ER chaperones co-immunoprecipitated with AbetaPP. Our studies provide evidence of the UPR in s-IBM muscle and demonstrate for the first time that the ER chaperones calnexin, calreticulin, GRP94, BiP/GRP78, and ERp72 physically associate with AbetaPP in s-IBM muscle, suggesting their playing a role in AbetaPP folding and processing.

Amyloid beta-Protein Precursor↗

PubMed2000

Paired helical filaments of inclusion-body myositis muscle contain RNA and survival motor neuron protein.

Sporadic inclusion-body myositis (s-IBM) is the most common progressive muscle disease of older persons. Pathologically, the muscle biopsy manifests various degrees of inflammation and specific vacuolar degeneration of muscle fibers characterized by paired helical filaments (PHFs) composed of phosphorylated tau. IBM vacuolated fibers also contain accumulations of several other Alzheimer-characteristic proteins. Molecular mechanisms leading to formation of the PHFs and accumulations of proteins in IBM muscle are not known. We report that the abnormal muscle fibers of IBM contained (i) acridine-orange-positive RNA inclusions that colocalized with the immunoreactivity of phosphorylated tau and (ii) survival motor neuron protein immunoreactive inclusions, which by immuno-electron microscopy were confined to paired helical filaments. This study demonstrates two novel components of the IBM paired helical filaments, which may lead to better understanding of their pathogenesis.

Acridine Orange↗

PubMed1998

Transgenic mice over-expressing the C-99 fragment of betaPP with an alpha-secretase site mutation develop a myopathy similar to human inclusion body myositis.

Inclusion body myositis (IBM) is the most common muscle disease in the elderly. Amyloid-beta protein (A beta) has been shown to accumulate abnormally in the vacuolated fibers and to localize to amyloid-like fibrils in muscles from IBM patients. We studied the skeletal muscles from a line of transgenic mice over-expressing the carboxyl-terminal 99 amino acids (C99) of the beta-amyloid precursor protein (betaPP) with a substitution of lysine-612 to valine (K612V), intended to abolish alpha-secretase recognition and to preserve the A beta domain of C99. The majority (87%) of the 24-month-old transgenic mice showed myopathic changes, and approximately one-third of them had degenerating fibers with sarcoplasmic vacuoles and thioflavin-S-positive deposits. Ultrastructurally, the inclusions were aggregates of short thin amyloid-like fibrils, 6 to 8 nm in diameter. These features are similar to those of human IBM. Immunocytochemistry using an antibody against A beta showed membranous staining in most muscle fibers of transgenic mice, as well as granular or vacuolar cytoplasmic staining in the atrophic fibers. Western blots showed a high level of accumulation of carboxyl-terminal fragments of betaPP in the muscles of the transgenic mice with the most severe IBM-like lesions. The expression of IBM-like lesions was age dependent. These transgenic mice provide a model for the study of IBM and for the peripheral expression of a key element in the pathogenesis of Alzheimer disease.

Age Factors↗

PubMed1997

Inclusion body myositis and transitional cell carcinoma of the bladder: significant resolution of symptoms after tumor excision.

Inclusion body myositis (IBM) is a separate class of the inflammatory myopathies with recently proposed clinical and pathological diagnostic criteria. An association between inflammatory myopathies and malignancy has been questioned in the literature. Recent reviews of the inflammatory myopathies suggest that only dermatomyositis is associated with malignancy. The largest study to date of patients with IBM found that 15% had a malignancy (6 of 40). We report the first documented case of IBM and concurrent transitional cell carcinoma of the bladder. We suggest that a causal relationship between IBM and malignancy may exist because of significantly improved functional strength gained after tumor removal.

Carcinoma, Transitional Cell↗

PubMed1988

Early myositis ossificans: a new echographic sign.

A case of soft tissue swelling of the thigh in which myositis ossificans developed is presented. A series of ultrasound examinations showed previously unreported changes which suggested the diagnosis. The use of ultrasound and other imaging modalities in this condition are discussed and the ultrasound appearances are related to the histology.

Adolescent↗

PubMed1995

Muscle fibre expression of transforming growth factor-beta 1 and latent transforming growth factor-beta binding protein in canine masticatory muscle myositis.

Masticatory muscle myositis (MMM) is presumed to be an immunologically mediated canine myopathy but is of unknown origin. Severe atrophy and degeneration of masticatory muscle fibres, infiltration of eosinophilic granulocytes, and proliferation of the fibrous interstitial tissue are the hallmarks of MMM. Transforming growth factor-beta (TGF-beta) is a multifunctional regulatory peptide controlling myogenesis, inflammation and tissue repair. We investigated immunocytochemically the expression of TGF-beta 1 and latent transforming growth factor-beta binding protein (LTBP), a TGF-beta modulator protein, in cases of MMM. The study demonstrated the presence of TGF-beta and LTBP in muscle fibres. infiltrating leucocytes and extracellular matrix in MMM, and suggested that TGF-beta and LTBP play a role in muscle tissue repair, inflammation and fibrogenesis in MMM.

Animals↗

PubMed1992

Benign acute myositis associated with rotavirus gastroenteritis.

Acute myositis developed concomitantly with gastroenteritis in a 2-year-old girl. She had temporary pain and swelling of the calf muscles and transient marked elevation of serum creatine kinase values. Rotavirus antigen was detected in stool by latex agglutination, and there was seroconversion of complement-fixation antibody to rotavirus.

Acute Disease↗

PubMed2000

Peripheral neuropathy associated with hereditary and sporadic inclusion body myositis: confirmation by electron microscopy and morphometry.

Inclusion body myositis (IBM) is a disabling myopathy affecting proximal and distal muscle groups. The involvement of peripheral nerves in IBM is still a controversial matter. In a previous morphometric study at the light microscopic level only, we described a peripheral neuropathy in sural nerve biopsies of eight patients with sporadic IBM (s-IBM). Here we present a larger series of 14 cases in which a combined muscle and nerve biopsy was available for additional electron microscopic investigation. In two of the new cases, the IBM had a hereditary background (h-IBM). The presence of neuropathy was confirmed in all 14 cases studied. Morphometry using an optic-electronic, digital evaluation system showed large variation of severity presumably due to age and coincidal factors such as diabetes mellitus or lymphoma. Ultrastructural analysis revealed a variety of changes considered to be non-specific. Signs of axonal damage predominated. In addition, there were numerous changes in Schwann cells and myelin sheaths. Neither inflammatory changes nor tubulofilamentous inclusions were detectable in the sural nerves. Peripheral neuropathy, although occasionally without apparent clinical manifestation, appears to be a common and aggravating feature in IBM; its pathogenesis, however, remains elusive.

Adolescent↗

PubMed2001

Mycophenolate (CellCept) treatment of myasthenia gravis, chronic inflammatory polyneuropathy and inclusion body myositis.

We report favorable results of the long term use of mycophenolate in the treatment of three patients with myasthenia gravis (MG), two patients with chronic inflammatory demyelinating polyneuropathy (CIDP), one patient with secondary polymyositis (PM), and one patient with inclusion body myositis (IBM). Side effects were mild. Mycophenolate appears to be a useful addition to the armamentarium of immunosuppressants for treatment of chronic immunologically mediated neuromuscular diseases.

Adult↗

PubMed1996

Experimental autoimmune myositis in SJL/J mice produced by immunization with syngeneic myosin B fraction. Transfer by both immunoglobulin G and T cells.

An experimental autoimmune myositis (EAM) was produced by immunizing SJL/J mice with the myosin B (MB) fraction of the syngeneic muscle. Immunoblot analysis of the IgG of the EAM mice demonstrated antibodies against a variety of muscle proteins. The condition was then transferred to normal mice by both injecting immunoglobulin G or T cells from the EAM mice. This is the first model of transferrable EAM caused by syngeneic muscle fraction, and it has an unique resemblance to human inflammatory myopathies involving both humoral and cellular immune mechanisms.

Animals↗

PubMed1997

Granulomatous myositis: pathologic re-evaluation by immunohistochemical analysis of infiltrating mononuclear cells.

To characterize the non-caseating granuloma formation in granulomatous myositis, we analyzed infiltrating mononuclear cells in 7 patients including 2 sarcoid patients, using monoclonal antibodies with a modified immunoperoxidase method. All granulomas consisting of epithelioid, infiltrating mononuclear cells and multinucleated giant cells had markedly increased numbers of CD45Ro-positive cells. The infiltrating inflammatory cells were mostly T lymphocytes and macrophages. The majority of T lymphocytes behaved as T helper/inducer subtype, expressing CD4 positivity. Although the ratio of CD4- to CD8-positive cells in the granuloma in muscle biopsies was not significantly different from that in other organs seen in systemic sarcoidosis, T helper/inducer and T suppressor/cytotoxic cells showed some characteristic distributions: CD4-positive cells accumulated in the center of, and CD8-positive cells at the periphery of, the granuloma. The distribution of infiltrating cells did not differ between muscle biopsies from patients with and without systemic sarcoidosis, suggesting that both groups share the same pathogenetic mechanism in granuloma formation.

Aged↗

PubMed1997

Painful small-fibre multifocal mononeuropathy and local myositis following influenza B infection.

A 47-year-old man experienced multifocal mononeuropathy and putative ganglionopathy associated with influenza B infection, characterized by aching and dysesthesia in the right arm and left leg with normal deep sense. He displayed muscle atrophy in the affected limbs, which might have resulted from local myositis or a disorder similar to neuralgic amyotrophy. Sural nerve biopsy revealed a severe loss of unmyelinated and thinly myelinated fibres, consistent with a small fibre neuropathy, without evidence of angiopathy or inflammation. We could not detect any other cause of the neuropathy except influenza B. In this case, it may be inferred that small-diameter neurons in the dorsal root ganglia and thinly- or nonmyelinated fibres were selectively involved through a post-infectious immune process. To our knowledge, small fibre neuropathy following influenza B has never been reported.

Humans↗

PubMed1979

Focal myositis of the neck.

Focal myositis is a recently defined, rapidly growing, inflammatory pseudotumor of skeletal muscle. It is characterized by marked myopathic changes of muscle fibers, hypocellular fibrosis of perimysium and endomysium, and an intense inflammatory reaction in the fibrous septa. This report describes the first instance involving the neck muscle of a 40 year old man. A brief discussion of other histologically similar subcutaneous lesions is also presented.

Adolescent↗

PubMed1987

Myositis and acquired immunodeficiency syndrome.

Clinical and pathologic observations made in a patient with inflammatory myopathy associated with the acquired immunodeficiency syndrome (AIDS) are presented. Multinucleated giant cells were a prominent histopathologic feature in the muscle biopsy samples. The findings indicate that in some patients with AIDS myositis, inflammatory myopathy may be the direct result of infection with the human immunodeficiency virus.

Acquired Immunodeficiency Syndrome↗

PubMed1998

Rimmed vacuoles with beta-amyloid and ubiquitinated filamentous deposits in the muscles of patients with long-standing denervation (postpoliomyelitis muscular atrophy): similarities with inclusion body myositis.

In the chronically denervated muscles of patients with prior paralytic poliomyelitis, there are secondary myopathic features, including endomysial inflammation and rare vacuolated fibers. To assess the frequency and characteristics of the vacuoles and their similarities with those seen in inclusion body myositis (IBM), we examined 58 muscle biopsy specimens from patients with prior paralytic poliomyelitis for (1) the presence of rimmed vacuoles; (2) acid-phosphatase reactivity; (3) Congo-red-positive amyloid deposits; (4) electron microscopy, searching for tubulofilaments; and (5) immunoelectron microscopy, using antibodies against beta-amyloid and ubiquitin. We found vacuolated muscle fibers in 18 of 58 (31%) biopsies, with a mean frequency of 2.06 +/- 0.42 fibers per specimen. The vacuoles contained acid phosphatase-positive material in 6 of the 18 (33.30%) specimens and stained positive for Congo red in five (27.80%). By immunoelectron microscopy, the vacuoles contained 5.17 +/- 0.13 nm fibrils and 14.9 +/- 0.31 nm filaments that immunoreacted with antibodies to beta-amyloid and ubiquitin in a pattern identical to the one seen in IBM. We conclude that vacuolated muscle fibers containing filamentous inclusions positive for amyloid and ubiquitin are not unique to IBM and the other vacuolar myopathies but can also occur in a chronic neurogenic condition, such as postpoliomyelitis. The chronicity of the underlying disease, rather than the cause, may lead to vacuolar formation, amyloid deposition, and accumulation of ubiquitinated filaments.

Amyloid beta-Peptides↗