Inflammatory and non-inflammatory inclusion body myositis

Summary In ten patients with inclusion body myositis (IBM) five muscular biopsies showed profuse inflammatory exudates and three showed a few scattered inflammatory cells with partial invasion in some muscle fibers. No inflammatory cells were seen in two cases. In all patients, histopathological, histomorphometric and immunocytochemical studies were performed. Immunocytochemistry for the class I and class II major histocompatibility complex gene product (MHC) was performed in all cases and in ten control muscles including: normal muscles [3], dermatomyositis [3], polymyositis [3], scleroderma [1]. In the five cases of IBM with inflammatory exudates, subsets of lymphocytes were analyzed with a panel of monoclonal antibodies against B cells, T4 cells, T8 cells, K and natural killer cells and macrophages. Some muscle fibers expressed class I MHC antigens in the inflammatory cases of IBM. These fibers were near the inflammatory exudates and occasionally showed a partial invasion. No expression of class I MHC was found in normal muscles and in non-inflammatory cases of IBM. The antigen which triggers the mononuclear cells in the inflammatory forms of IBM is probably not the filamentous inclusions in rimmed vacuoles. In other inflammatory myopathies, expression of class I MHC was present on all fibers in polymyositis, only in the perifascicular area in dermatomyositis and in scleroderma. It could be suggested that the term inclusion body muscle disease be applied to cases with rimmed vacuoles and IBM-like filaments without inflammatory cells.     

Mitochondrial DNA variants in inclusion body myositis

Mitochondrial DNA variants have been shown to be associated with many diseases. Mutations at mitochondrial DNA nucleotide positions 3192, 3196, 3397 and 4336 have been described in association with late-onset Alzheimer's disease. The pathological similarities between inclusion body myositis and Alzheimer's disease prompted an analysis of the relationship between the reported mutations and sporadic inclusion body myositis. The 4336G variant was not significantly increased in patients with inclusion body myositis or Alzheimer's disease when compared to controls. None of the patients with inclusion body myositis carried mutations at nucleotide positions 3192, 3196 and 3397. A transition at nucleotide position 4580 was detected in some patients with inclusion body myositis and Alzheimer's disease but was not significantly higher in frequency when compared to controls. Phylogenetic analysis showed that the 4336G and 4580A variants clustered together in their respective group. A group of patients with inclusion body myositis also clustered together on a separate branch of the phylogenetic tree. Closer investigation of this group revealed a common polymorphism at nucleotide position 16311. The frequency of the 16311C variant was higher in inclusion body myositis than in Alzheimer's disease and controls, although when only caucasian patients were considered the increased frequency was not statistically significant. Further studies will be required to determine whether this variant plays a role in the pathogenesis of inclusion body myositis.     

Differential and quantitative neuroimaging characteristics of inclusion body myositis

In clinical settings, it is often difficult to distinguish inclusion body myositis (IBM) from other neuromuscular diseases. In order to clarify clinically useful characteristics for making the differential diagnosis of IBM, we performed clinical, epidemiological, and neuroimaging analyses in patients with various types of neuromuscular disorders. We enrolled 333 patients with myopathy and 12 patients with amyotrophic lateral sclerosis (ALS) who had been hospitalized in our department from January 1, 1979, to December 31, 2018. Among them, 18 patients with IBM, 16 patients with polymyositis (PM), and 12 patients with ALS who showed equivalent severity of muscle weakness in their lower limbs underwent the quantitative neuroimaging analysis using lower limb CT and clinical assessment. Patients with IBM exhibited significantly greater muscular degeneration in the rectus femoris, vastus, sartorius, adductor, anterior calf, and medial gastrocnemius muscles than those with PM or ALS. The ratio of the remaining muscle area of the quadriceps relative to that of the hamstrings and the duration from onset to CT imaging were negatively correlated in patients with IBM, indicating that the anterior thigh muscles were preferentially affected over the posterior muscles. Characteristic muscular degeneration in the lower limbs on CT imaging may aid for making the diagnosis of IBM.     

Dermatomyositis with inclusion body myositis pathology

The pathogenic role of inflammation in inclusion body myositis (IBM) remains uncertain. A 63‐year‐old man developed a severe, rapidly progressive myopathy with clinical features typical of dermatomyositis (DM), but muscle pathology was typical of IBM. Treatment with prednisone and methotrexate resulted in complete remission of symptoms. Together with two similar cases reported previously, this case suggests that the inflammatory process of DM may trigger the pathologic changes of IBM. Muscle Nerve, 2009     

Sporadic inclusion body myositis presenting with severe camptocormia

Sporadic inclusion body myositis (sIBM) is a slowly progressive idiopathic inflammatory myopathy. The characteristic early quadriceps and finger flexor muscle weakness often leads to the diagnosis of sIBM, especially when all canonical pathological features of sIBM are not present on muscle biopsy. Weakness of the paraspinal muscles, resulting in head drop and/or camptocormia, is a rare clinical finding along the course of sIBM, and even more rare as the presenting feature. We describe two patients with sIBM manifesting with camptocormia as the sole clinical manifestation for several years prior to the diagnosis by muscle biopsy. This observation emphasizes the role of sIBM in the etiology of camptocormia and the need to consider this common myopathy as a cause of weakness, despite the lack of classic quadriceps and finger flexor muscle weakness years after the onset of the paraspinal muscle weakness.     

A review on the treatment of sporadic inclusion body myositis with Bimagrumab and Alemtuzumab

Background: Sporadic inclusion body myositis is the most common inflammatory myopathy over the age of 50. The aetiopathogenesis of the disease remains unclear and to the day there is no effective treatment.

Objectives: The aim of the present review is to present the latest data on the new insights and developments in the treatment of sporadic inclusion body myositis, focusing on Bimagrumab and Alemtuzumab.

Methods: For the purpose of the review we searched multiple internet databases in order to find the most recent studies and clinical trials on the safety, tolerability and efficacy of Bimagrumab and Alemtuzumab in sporadic inclusion body myositis.

Results: We found four trials on Bimagrumab, with one of them being an extension phase III study, and one small series trial on Alemtuzumab. The first clincopathological trial on Bimagrumab showed promising evidence, which were partially confirmed by the double-blinded controlled multicentre trial, however the primary endpoint of improving 6-m walking distance or improving the muscle strength has not been reached. The evidence from the Alemtuzumab trial was also promising, but the risk of bias of the study was relatively high, because it was open labelled, the number of patient was low and the yearly disease progression was much higher than in other recent studies.

Conclusions: Although both Bimagrumab and Alemtuzumab were well tolerated and showed promising results, the Bimagrumab trial did not reach the primary endpoint, and the Alemtuzumab trial has a relatively high risk of bias and the results need to be interpreted with caution.     

A novel case of inclusion body myositis and myasthenia gravis

The co-existence of myasthenia gravis and other inflammatory myopathies has been reported in the literature before, but no clinical cases involving inclusion body myositis have been reported. We report a case of a 67-year-old patient who presented with dysphagia, exhibiting the typical electrophysiological features of postsynaptic neuromuscular junction defect with positive muscle acetylcholine receptor antibodies, consistent with the diagnosis of myasthenia gravis. Nevertheless, response to acetylcholinesterase inhibitors and immunomodulatory treatment was unexpectedly poor. As the disease progressed, the patient developed asymmetric muscle weakness, initially affecting mainly the quadriceps and the finger flexors. Muscle MRI imaging supported the presence of an inflammatory myopathy and muscle biopsy confirmed the diagnosis of inclusion body myositis. Thus, our patient represents the first reported overlap case of myasthenia gravis and inclusion body myositis.     

Inclusion body myositis with abundant ring fibers

Summary A 37-year-old male presenting with a 7-year history of leg weakness was found to have moderate weakness confined to the quadriceps and myopathic changes on electromyography. Serum creatine phosphokinase was 2130 units/liter. Biopsy of the quadriceps muscle revealed an inflammatory myopathy with cytoplasmic and nuclear filamentous inclusions characteristic of inclusion body myositis. An unusual finding was the large proportion of ring fibers along with severe atrophy and fibrosis. The pathogenesis of the ring fibers in this setting is discussed.     

Prognosis and prognostic factors in sporadic inclusion body myositis

Objectives – To describe the course of change in muscle strength sporadic inclusion body myositis (IBM) patients. Material and methods – We have studied a cohort of 66 IBM pateints using a hand‐held dynamometer. Results – Follow‐up during a mean of 61.1 months showed a deterioration of on average ?0.79% per month. The ‘natural course’ without immunosuppressive treatment (IS), analyzed in 43 patients (mean 46.4 months) was mean ?1.03% per month. Loss of muscle power was most rapid in knee extension ?1.12% (P < 0.001 when compared with elbow flexion, elbow extension and hip flexion). There was a tendency towards a more rapid decline in males than females and over the first 5 years after onset, while the level of serum creatine kinase (CK), age, or region affected at onset did not predict the prognosis. The mean change during periods with any IS treatment was ?0.76% per month which was significantly lower compared to the total of untreated periods ?1.03% (P < 0.05). Patients (n = 13) treated with mykofenolatmofetil showed a better prognosis of ?0.67% per month (P < 0.05). In this group elbow flexion and extension and hip flexion showed a positive response, while knee extension was seemingly unaffected. Conclusions – There is a mean of 1% loss in power per month in the untreated IBM patient – the rate of loss was greater in the quadriceps muscle and in untreated compared with IS‐treated patients.     

包涵体肌炎的临床与病理特点(附2例报告)

目的 探讨包涵体肌炎的临床与病理特点。方法 对2例包涵体肌炎患者的临床表现、肌肉组织化学、酶组织化学和超微结构等资料进行分析。结果 本组2例患者分别于41岁及54岁发病,均以双下肢无力起病,远端重于近端,并逐渐向上肢发展;血清肌酶轻～中度升高;肌电图示肌源性损害;肌肉活检光镜下主要表现为肌纤维内出现镶边空泡,少数变性坏死纤维,伴炎性细胞浸润。电镜观察证实肌浆内有大量涡轮状髓样小体及管状细丝包涵体。结论 包涵体肌炎临床表现缺乏特异性,肌肉病理学检查是诊断包涵体肌炎的重要手段。     

High-dose immunoglobulin therapy in sporadic inclusion body myositis: a double-blind, placebo-controlled study

Sporadic inclusion body myositis (s-IBM) is an acquired inflammatory muscle disease of unknown cause. In general, s-IBM presents with slowly progressive, asymmetric weakness, and atrophy of skeletal muscle. There is a mild transitory or nil responsiveness to standard immunosuppressive treatment. A controlled cross-over study of 22 s-IBM patients over 3 months showed a partial improvement in those treated with high-dose intravenous immunoglobulin therapy (IVIG) versus placebo. The present study included 22 patients aged 32-75 years and with a mean duration of disease of 5.2+/-3.6 years. They were randomized by a double-blind, placebo-controlled, cross-over design to monthly infusions of 2 g/kg bodyweight IVIG or to placebo for 6 months each, followed by the alternative treatment. After 6 and 12 months the response to treatment was evaluated, using a modified Medical Research Council scale, Neuromuscular Symptom Score (NSS), the patient's own assessment of improvement, arm outstretched time, and electromyography. No serious side effects were seen, in particular no viral infection and no major cardiac or neurological complications. Overall there was no progression of the disease in 90% of patients, unlike that which might have been expected in untreated patients. A mild and significant improvement (11%) in clinical symptoms was found using NSS, but not with other test procedures. There was a trend to mild improvement in treated patients when using other tests. Individual responses to treatment was heterogeneous. The validity of this study may be reduced by mismatch of groups with regard to age at onset and variability in disease expression. The findings of this study largely confirm those of a previous IVIG trial. Treatment with IVIG may be mildly effective in s-IBM by preventing disease progression or inducing mild improvement. Long-term studies are needed to evaluate further the benefit of IVIG therapy in s-IBM.     

Myonuclear breakdown in sporadic inclusion body myositis is accompanied by DNA double strand breaks

Rimmed vacuoles in sporadic inclusion body myositis (s-IBM) contain nuclear remnants. We sought to determine if the nuclear degeneration seen in s-IBM is associated with DNA damage. In muscle biopsy specimens from ten patients with s-IBM and 50 controls, we immunolocalized 1) phosphorylated histone H2AX (γ-H2AX), which is a sensitive immunocytochemical marker of DNA double-strand breaks and 2) DNA-PK, which is an enzyme involved in double-strand break repair. In s-IBM, vacuolar peripheries often showed strong immunoreactivity to γ-H2AX and the three components of DNA-PK (DNA-PKcs, Ku70, and Ku80). A triple fluorescence study of Ku70, emerin, and DNA displayed nuclear breakdown and it suggested impaired nuclear incorporation of Ku70. The percentage of positive nuclei for γ-H2AX was significantly higher in vacuolated fibers than non-vacuolated fibers in s-IBM, or fibers in polymyosits. We hypothesize that a dysfunction of nuclear envelope may cause nuclear fragility, double-strand breaks and impaired nuclear transport in s-IBM.     

Electrophysiological spectrum of inclusion body myositis

We present electrodiagnostic data on 30 patients with inclusion body myositis (IBM) in order to better delineate its electrophysiological features. Comprehensive electromyography (EMG) and nerve conduction studies (NCS) were performed in all cases. Twelve patients had single fiber electromyography (SFEMG). EMG showed abundant short-small motor unit potentials (MUP) with fibrillations and positive sharp waves in 56.6% of patients, and a mixed pattern of large and small MUP in 36.7%. In 6.7%, only "neurogenic" features were seen. NCS were slow in 33.3%. SFEMG revealed a mildly abnormal jitter and a slightly increased fiber density. IBM demonstrates a heterogeneous EMG profile. A pattern of large and small MUP is highly suggestive of IBM but is seen in only about one third of cases.     

Immune-mediated conditions and antibodies associated with sporadic inclusion body myositis

We reviewed 99 patients with sporadic inclusion body myositis (IBM), searching for a coexisting autoimmune disease, other conditions with altered immune function, or the presence of autoantibodies. Thirteen patients had one or more of 11 diseases with altered immune function. Forty-three patients had elevated titers of one or more of nine different, albeit nondisease-specific, autoantibodies. Twenty-five patients had dysproteinemia or dysproteinuria. We conclude that IBM is frequently associated with systemic immune disorders or nonspecific autoantibodies. Although aging may explain some of these phenomena, an altered immune function need to be considered in the pathogenesis of IBM. © 1998 John Wiley & Sons, Inc. Muscle Nerve, 21: 115–117, 1998.     

Four-year longitudinal study of clinical and functional endpoints in sporadic inclusion body myositis: Implications for therapeutic trials

Natural history studies in sporadic inclusion body myositis are of fundamental interest for future therapeutic trials. Previous works have demonstrated the particular relevance of knee extension strength in the follow-up of this disease. This work aimed to extend a preceding natural history over 9 months to a four year period. Thirteen patients were assessed using clinical and functional scales and dynamometry. Except wrist extension torque and manual muscle testing composite score, all the measurements presented a significant decline. The most important changes were observed for knee extension and ankle flexion and extension. The relative change in knee extension strength correlated with the level of strength at baseline. A non-linear correlation was found between 6-minute walk distance and knee extension strength. This study confirms that knee extension strength is particularly relevant to follow patients with sporadic inclusion body myositis. It also shows that a strength loss does not have linear consequences on motor ability. Finally strength and motor ability are complementing each other in the understanding of disease progression.     

Medication of inclusion body myositis: a systematic review

To investigate the existing evidence on the effectiveness of approaches to treating inclusion body myositis and to assess the methodological quality of this evidence. The Cochrane Controlled Trials Register (CENTRAL), Medline, Embase, Cinahl, Physiotherapy Evidence (Pedro), McMaster and Web of Science databases were searched. The references of identified articles and reviews were also checked for relevancy. The methodological quality was assessed according to the Cochrane Collaboration's domain‐based evaluation framework. Of the 331 identified records, 10 were considered relevant for a qualitative analysis. The risk of bias was considered being low for six studies and high for four. Eight studies were randomized controlled trials, and two were controlled clinical trials. In the samples, male gender predominated, and the mean age of the participants varied from 51 to 72 years. The duration of intervention varied from 3 to 17 months. One small trial on the effect of oxandrolone reported a significant positive result. The other trials observed no improvement or insignificant improvement among the participants treated with intravenous immunoglobulin, methotrexate, etanercept or interferon. Thus far, there is no evidence indicating that any specific treatment is the effective in treating inclusion body myositis.     

Coexistence of X-linked recessive Emery-Dreifuss muscular dystrophy with inclusion body myositis-like morphology

We reported three cases (two familial and one sporadic) of X-linked Emery-Dreifuss muscular dystrophy (EDMD), genetically documented. Two patients demonstrated a typical inclusion body myositis (IBM)-like morphology. The third patient had only minor changes. Patients had elbow and ankle contractures, progressive wasting of humeroperoneal muscles and cardiac failure (pacemaker implantation in all). There was a mutation within the Xq28 gene and complete absence of emerin in the nuclear membrane. Mononuclear cell infiltrations, rimmed vacuoles, amyloid deposits, as well as cytoplasmic and nuclear tubulofilamentous muscle inclusions were most unusual findings. Coexistence of IBM-like morphology and X-linked recessive EDMD might indicate that pathological features of IBM are nonspecific and may be present in other neuromuscular disorders.     

三例包涵体肌炎的临床与病理特点

目的探讨包涵体肌炎（ＩＢＭ）的临床与病理特点。方法总结３例ＩＢＭ病人的临床特点，并对肌活检标本进行酶组织化学、组织化学病理和超微病理研究。结果３例女性病人均在２４～３６岁发病，其临床特点为以双下肢无力起病，渐累及上肢，远端肢体受累常见。腱反射消失，血清肌酸激酶正常或轻度增高，肌活检光镜检查发现其主要病理改变为镶边空泡纤维，肌浆或肌核内有嗜酸性包涵体，肌内膜炎性细胞浸润和成群萎缩肌纤维。电镜观察发现３例均有肌浆内细丝或管状细丝包涵体，其中１例有核内包涵体。镶边空泡内含淀粉样细丝、髓样结构、絮状无结构物质和其他胞浆分解产物。肌核改变包括异染色质增多、核变大，核内包涵体及核崩解。结论电镜包埋、半薄切片定位是电镜下寻找包涵体并确诊ＩＢＭ的关键步骤。肌核改变可能是ＩＢＭ的病因基础，镶边空泡和肌浆内包涵体有可能来自于崩解的肌核。     

TREX1 mutations are not associated with sporadic inclusion body myositis

Background: Sporadic inclusion body myositis (sIBM) is the most frequent acquired myopathy above the age of fifty. The exact mechanism causing this disease is not known, but immune‐mediated features are prominent and are probably to play a role in its pathogenesis. TREX1 gene mutations are associated with a large range of autoimmune diseases, such as systemic lupus erythematosus. We investigated whether mutations in the TREX1 gene were associated with sIBM. Methods: Fifty‐four patients with sIBM were tested for TREX1 mutations by direct sequencing. Results: All 54 patients tested negative for pathogenic mutations in the TREX1 gene. One presumed non‐pathogenic polymorphism was found in 42 out of 54 patients. Conclusion: TREX1 mutations do not play a role in the pathogenesis of sIBM.