Inclusion Body Myositis and Neoplasia: A Narrative Review.

Inclusion body myositis (IBM) is an acquired, late-onset inflammatory myopathy, with both inflammatory and degenerative pathogenesis. Although idiopathic inflammatory myopathies may be associated with malignancies, IBM is generally not considered paraneoplastic. Many studies of malignancy in inflammatory myopathies did not include IBM patients. Indeed, IBM is often diagnosed only after around 5 years from onset, while paraneoplastic myositis is generally defined as the co-occurrence of malignancy and myopathy within 1 to 3 years of each other. Nevertheless, a significant association with large granular lymphocyte leukemia has been recently described in IBM, and there are reports of cancer-associated IBM. We review the pathogenic mechanisms supposed to be involved in IBM and outline the common mechanisms in IBM and malignancy, as well as the therapeutic perspectives. The terminally differentiated, CD8+ highly cytotoxic T cells expressing NK features are central in the pathogenesis of IBM and, paradoxically, play a role in some cancers as well. Interferon gamma plays a central role, mostly during the early stages of the disease. The secondary mitochondrial dysfunction, the autophagy and cell cycle dysregulation, and the crosstalk between metabolic and mitogenic pathways could be shared by IBM and cancer. There are intermingled subcellular mechanisms in IBM and neoplasia, and probably their co-existence is underestimated. The link between IBM and cancers deserves further interest, in order to search for efficient therapies in IBM and to improve muscle function, life quality, and survival in both diseases.

Ceramide contributes to pathogenesis and may be targeted for therapy in VCP inclusion body myopathy.

Knock-in homozygote VCPR155H/R155H mutant mice are a lethal model of valosin-containing protein (VCP)-associated inclusion body myopathy associated with Paget disease of bone, frontotemporal dementia and amyotrophic lateral sclerosis. Ceramide (d18:1/16:0) levels are elevated in skeletal muscle of the mutant mice, compared to wild-type controls. Moreover, exposure to a lipid-enriched diet reverses lethality, improves myopathy and normalizes ceramide levels in these mutant mice, suggesting that dysfunctions in lipid-derived signaling are critical to disease pathogenesis. Here, we investigated the potential role of ceramide in VCP disease using pharmacological agents that manipulate the ceramide levels in myoblast cultures from VCP mutant mice and VCP patients. Myoblasts from wild-type, VCPR155H/+ and VCPR155H/R155H mice, as well as patient-induced pluripotent stem cells (iPSCs), were treated with an inhibitor of ceramide degradation to increase ceramide via acid ceramidase (ARN082) for proof of principle. Three chemically distinct inhibitors of ceramide biosynthesis via serine palmitoyl-CoA transferase (L-cycloserine, myriocin or ARN14494) were used as a therapeutic strategy to reduce ceramide in myoblasts. Acid ceramidase inhibitor, ARN082, elevated cellular ceramide levels and concomitantly enhanced pathology. Conversely, inhibitors of ceramide biosynthesis L-cycloserine, myriocin and ARN14494 reduced ceramide production. The results point to ceramide-mediated signaling as a key contributor to pathogenesis in VCP disease and suggest that manipulating this pathway by blocking ceramide biosynthesis might exert beneficial effects in patients with this condition. The ceramide pathway appears to be critical in VCP pathogenesis, and small-molecule inhibitors of ceramide biosynthesis might provide therapeutic benefits in VCP and related neurodegenerative diseases.

Miositis por cuerpos de inclusión esporádica / Sporadic inclusion body myositis

A pesar de ser la miopatía primaria más frecuente en hombres mayores de 50 años de edad, la miositis por cuerpos de inclusión (MCI) esporádica es una enfermedad rara. En muchas ocasiones su diagnóstico es retrasado por lo que se refuerza la importancia de una adecuada valoración clínica e indicación oportuna de estudios complementarios. En el presente artículo se presenta un caso que tiene la distinción de presentarse en un paciente mestizo, sin afectación demostrada en flexores profundos de las manos y con elementos de gravedad, determinadas por la presencia de disfagia alta funcional y disnea a la posición de decúbito supino. En la revisión realizada no se recogen hasta el presente reportes en publicaciones de esta enfermedad en Cuba. Clínicamente, la afección se caracteriza por debilidad muscular combinada distal y proximal, electromiografía (EMG) con alteración mixta neuropática y miopática, y escasa respuesta a la terapia inmunosupresora. La biopsia de músculo ayuda a establecer el diagnóstico definitivo al demostrar la presencia de inclusiones distintivas en las fibras musculares. El pronóstico es sombrío al mostrar un comportamiento progresivo con afectación de la calidad de vida y llevar a una discapacidad física avanzada(AU)

Despite being the most common primary myopathy in men over 50 years of age, sporadic inclusion body myositis (ICM) is a rare disease. On many occasions its diagnosis is delayed, which is why the importance of an adequate clinical assessment and timely indication of complementary studies is reinforced. This article reports a case that has the peculiarity of affecting a mestizo patient, with no established involvement in the deep flexors of his hands and with elements of severity, determined by the presence of high functional dysphagia and dyspnea in the supine position. There have not been publication reports on this disease in Cuba. Clinically, the condition is characterized by combined distal and proximal muscle weakness, electromyography (EMG) with mixed neuropathic and myopathic impairment, and poor response to immunosuppressive therapy. Muscle biopsy helps establish the definitive diagnosis by demonstrating the presence of distinctive inclusions in the muscle fibers. The prognosis is bleak, showing progressive behavior affecting quality of life and leading to advanced physical disability(AU)

MODERN ASPECTS OF ETIOPATHOGENESIS, DIAGNOSIS, CLINICAL COURSE AND TREATMENT OF SPORADIC INCLUSION BODY MYOSITIS.

While it is the most common inflammatory myopathy among middle-aged and elderly people, sporadic inclusion body myositis (IBM) presents as the most challenging disease to diagnose. The prevalence of IBM varies greatly depending on geographical, ethnic and age factors. Frequency of the disease incidence among the general population ranges from 1:1,000,000 to 1:14,000. Over the past 50 years, it has tripled. The etiology and pathogenetic mechanisms of IBM have not yet been fully studied and, therefore, the criteria for diagnosis and treatment have not been fully established. A treatment algorithm developed for other inflammatory myopathies is not effective in IBM. Thus, the aim of this work is to review, summarize and analyze the latest medical literature on etiopathogenesis, clinical phenotypes, global prevalence, genetic predisposition, diagnostic criteria and treatment trends for IBM, which will contribute to the improvement and practical application of current diagnostic and therapeutic methods of the disease.

Association of Ultraviolet Radiation Exposure With Dermatomyositis in a National Myositis Patient Registry.

OBJECTIVE: Dermatomyositis (DM) has been associated with geospatial differences in ultraviolet (UV) radiation, but the role of individual determinants of UV exposure prior to diagnosis is unknown. The objective was to examine the role of those individual determinants. METHODS: We analyzed questionnaire data from 1,350 adults in a US national myositis registry (638 with DM, 422 with polymyositis [PM], and 290 with inclusion body myositis [IBM] diagnosed at ages 18-65 years), examining the likelihood of DM compared with PM and IBM diagnosis, in relation to self-reported sunburn history and job- and hobby-related sun exposures in the year prior to diagnosis. We estimated odds ratios (ORs) and 95% confidence intervals (95% CIs) using logistic regression adjusted for age, skin tone, and sex, to determine the association of individual UV exposures with DM diagnosis. We also evaluated the proportion of DM by maximum daily ambient UV exposure, based on UVB erythemal irradiances for participant residence in the year prior to diagnosis. RESULTS: DM was associated with sunburn in the year before diagnosis (2 or more sunburns OR 1.77 [95% CI 1.28-2.43] versus PM/IBM; 1 sunburn OR 1.44 [95% CI 1.06-1.95]) and with having elevated job- or hobby-related sun exposure (high exposure OR 1.64 [95% CI 1.08-2.49] or moderate exposure OR 1.35 [95% CI 1.02-1.78] versus low or no exposure). Ambient UV intensity was associated with DM in females (ß = 3.97, P = 0.046), but not overall. CONCLUSION: Our findings suggest that high or moderate personal exposure to intense sunlight is associated with developing DM compared with other types of myositis. Prospective research on UV exposure as a modifiable risk factor for DM is warranted.

Inclusion body myositis: clinical features and pathogenesis.

Inclusion body myositis (IBM) is often viewed as an enigmatic disease with uncertain pathogenic mechanisms and confusion around diagnosis, classification and prospects for treatment. Its clinical features (finger flexor and quadriceps weakness) and pathological features (invasion of myofibres by cytotoxic T cells) are unique among muscle diseases. Although IBM T cell autoimmunity has long been recognized, enormous attention has been focused for decades on several biomarkers of myofibre protein aggregates, which are present in <1% of myofibres in patients with IBM. This focus has given rise, together with the relative treatment refractoriness of IBM, to a competing view that IBM is not an autoimmune disease. Findings from the past decade that implicate autoimmunity in IBM include the identification of a circulating autoantibody (anti-cN1A); the absence of any statistically significant genetic risk factor other than the common autoimmune disease 8.1 MHC haplotype in whole-genome sequencing studies; the presence of a marked cytotoxic T cell signature in gene expression studies; and the identification in muscle and blood of large populations of clonal highly differentiated cytotoxic CD8+ T cells that are resistant to many immunotherapies. Mounting evidence that IBM is an autoimmune T cell-mediated disease provides hope that future therapies directed towards depleting these cells could be effective.

Inclusion Body Myositis: Update on Pathogenesis and Treatment.

Inclusion body myositis is the most common acquired myopathy after the age of 50. It is characterized by progressive asymmetric weakness predominantly affecting the quadriceps and/or finger flexors. Loss of ambulation and dysphagia are major complications of the disease. Inclusion body myositis can be associated with cytosolic 5'-nucleotidase 1A antibodies. Muscle biopsy usually shows inflammatory cells surrounding and invading non-necrotic muscle fibers, rimmed vacuoles, congophilic inclusions, and protein aggregates. Disease pathogenesis remains poorly understood and consists of an interplay between inflammatory and degenerative pathways. Antigen-driven, clonally restricted, cytotoxic T cells represent a main feature of the inflammatory component, whereas abnormal protein homeostasis with protein misfolding, aggregation, and dysfunctional protein disposal is the hallmark of the degenerative component. Inclusion body myositis remains refractory to treatment. Better understanding of the disease pathogenesis led to the identification of novel therapeutic targets, addressing both the inflammatory and degenerative pathways.

Inclusion body myositis: advancements in diagnosis, pathomechanisms, and treatment.

PURPOSE OF REVIEW: To review new advances in inclusion body myositis (IBM) and discuss them in light of current knowledge on diagnosis, pathomechanisms, and treatment perspectives. RECENT FINDINGS: IBM is a treatment refractory inflammatory myopathy in middle-aged patients that leads to a slow, relentlessly progressive muscle weakness, and atrophy. Recent data collections suggest that mortality in IBM patients is somewhat elevated compared with the general population. One major risk factor for death is severe dysphagia, which can now be determined by a novel real-time MRI technique. Recently, proposed diagnostic criteria with a combination of clinical and histopathological features have improved sensitivity and specificity. cytosolic 5'-nucleotidase 1A antibodies have been characterized in IBM patients and their pathophysiologic role has recently been studied. New inflammatory pathomechanisms have been identified in IBM muscle and may help to design novel treatment strategies. A broad spectrum of immunosuppressive and immunomodulatory trials have been conducted, but - so far- no effective treatment is available. Current therapeutic attempts aim to block the myostatin pathway or restore the protein homeostasis. SUMMARY: The expanding knowledge of the complex disease, the refinement of diagnostic criteria, and developments in diagnostic procedures are expected to foster the much needed design of new treatment approaches for future clinical trials.

Ubiquitin- and ATP-dependent unfoldase activity of P97/VCP•NPLOC4•UFD1L is enhanced by a mutation that causes multisystem proteinopathy.

p97 is a "segregase" that plays a key role in numerous ubiquitin (Ub)-dependent pathways such as ER-associated degradation. It has been hypothesized that p97 extracts proteins from membranes or macromolecular complexes to enable their proteasomal degradation; however, the complex nature of p97 substrates has made it difficult to directly observe the fundamental basis for this activity. To address this issue, we developed a soluble p97 substrate-Ub-GFP modified with K48-linked ubiquitin chains-for in vitro p97 activity assays. We demonstrate that WT p97 can unfold proteins and that this activity is dependent on the p97 adaptor NPLOC4-UFD1L, ATP hydrolysis, and substrate ubiquitination, with branched chains providing maximal stimulation. Furthermore, we show that a p97 mutant that causes inclusion body myopathy, Paget's disease of bone, and frontotemporal dementia in humans unfolds substrate faster, suggesting that excess activity may underlie pathogenesis. This work overcomes a significant barrier in the study of p97 and will allow the future dissection of p97 mechanism at a level of detail previously unattainable.

Overlapping features of polymyositis and inclusion body myositis in HIV-infected patients.

OBJECTIVE: To characterize patients with myositis with HIV infection. METHODS: All HIV-positive patients with myositis seen at the Johns Hopkins Myositis Center from 2003 to 2013 were included in this case series. Muscle biopsy features, weakness pattern, serum creatine kinase (CK) level, and anti-nucleotidase 1A (NT5C1A) status of HIV-positive patients with myositis were assessed. RESULTS: Eleven of 1,562 (0.7%) patients with myositis were HIV-positive. Myositis was the presenting feature of HIV infection in 3 patients. Eight of 11 patients had weakness onset at age 45 years or less. The mean time from the onset of weakness to the diagnosis of myositis was 3.6 years (SD 3.2 years). The mean of the highest measured CK levels was 2,796 IU/L (SD 1,592 IU/L). On muscle biopsy, 9 of 10 (90%) had endomysial inflammation, 7 of 10 (70%) had rimmed vacuoles, and none had perifascicular atrophy. Seven of 11 (64%) patients were anti-NT5C1A-positive. Upon presentation, all had proximal and distal weakness. Five of 6 (83%) patients followed 1 year or longer on immunosuppressive therapy had improved proximal muscle strength. However, each eventually developed weakness primarily affecting wrist flexors, finger flexors, knee extensors, or ankle dorsiflexors. CONCLUSIONS: HIV-positive patients with myositis may present with some characteristic polymyositis features including young age at onset, very high CK levels, or proximal weakness that improves with treatment. However, all HIV-positive patients with myositis eventually develop features most consistent with inclusion body myositis, including finger and wrist flexor weakness, rimmed vacuoles on biopsy, or anti-NT5C1A autoantibodies.

T-Cell-Mediated Inflammatory Myopathies in HIV-Positive Individuals: A Histologic Study of 19 Cases.

T cell-mediated inflammatory myopathies (polymyositis [PM] and inclusion body myositis [IBM]) sometimes arise in conjunction with HIV infection; however, it is not understood whether PM and IBM arising in the context of HIV (HIV-PM and HV-IBM) differ from PM and IBM arising sporadically in HIV-negative individuals (sPM and sIBM). Here, we report the largest series of T cell-mediated inflammatory myopathies from HIV-infected patients (19 biopsies from 15 subjects); 5 cases were pathologically classified as PM (HIV-PM) and 14 as IBM (HIV-IBM). As with sporadic cases, quantitative immunohistochemistry for LC3, p62, and TDP-43 showed significantly greater percentage of stained fibers (% FS) in HIV-IBM compared to HIV-PM samples; however, there was no significant difference in % FS for any of the three markers between HIV-associated and sporadic cases. Despite histologic similarities between HIV-IBM and sIBM but in concordance with prior case reports, patients with HIV-IBM were significantly younger at diagnosis than patients with sIBM; in contrast, the mean age of HIV-PM and sPM patients was not significantly different. In summary, HIV-PM and HIV-IBM are morphologically similar to sPM and sIBM; thus, it remains unclear why patients with HIV-IBM, in contrast to patients with sIBM, sometimes show clinical improvement in response to immunosuppressive therapy.

[The etiology and pathogenesis of sporadic inclusion body myositis].

Sporadic inclusion body myositis (sIBM) is the most common acquired muscle disease in older individuals. Muscle weakness and atrophy in the quadriceps, wrist flexor, and finger flexors are the typical clinical findings in sIBM. The etiology and pathogenesis of sIBM are still poorly understood; however, genetic factors, aging, and environmental factors might possibly play a role. The pathological characteristics of sIBM include two unique features: inflammatory changes in muscle fibers, and cytoplasmic and intranuclear inclusions containing several Alzheimer-type proteins. Based on these pathological findings, there is a continuing debate on whether sIBM is primarily a T cell-mediated inflammatory myositis or a myodegenerative disorder characterized by abnormal protein aggregation, presence of inclusions bodies, and secondary inflammation. Unfortunately, sIBM is also generally refractory to immune therapy.

Cytokine profiling in patients with VCP-associated disease.

Valosin containing protein (VCP) disease (also known as Inclusion Body Myopathy, Paget Disease of Bone and Frontotemporal Dementia [IBMPFD] syndrome) is caused by mutations in the gene encoding VCP classically affecting the muscle, bone and brain. Although the genetic cause has been identified, details regarding the pathogenesis of IBMPFD have not been fully determined. Muscle wasting observed in VCP disease is suggestive of cytokine imbalance. We hypothesized that dysfunctional protein homeostasis caused by VCP mutations leads to cytokine imbalances thereby contributing to the muscle wasting phenotype. Circulating levels of interleukin-4 (IL-4), interleukin-6 (IL-6), tumor necrosis factor alpha (TNF a) and epidermal growth factor (EGF) were measured in plasma of patients with VCP disease or controls. TNF a and EGF were significantly altered in VCP disease as compared to control. TNF a was up-regulated, consistent with a cachexia phenotype and EGF levels were increased. No significant differences were observed in IL-4 and IL-6. Cytokine imbalances may be associated with VCP disease and may play a contributory role in VCP myopathy. Further understanding of how VCP dysfunction leads to aberrant protein homeostasis and subsequent cytokine imbalances may also aid in the understanding of other proteinopathies and in the development of novel treatments.

Update in inclusion body myositis.

PURPOSE OF REVIEW: The purpose of this study is to review recent scientific advances relating to the natural history, cause, treatment and serum and imaging biomarkers of inclusion body myositis (IBM). RECENT FINDINGS: Several theories regarding the aetiopathogenesis of IBM are being explored and new therapeutic approaches are being investigated. New diagnostic criteria have been proposed, reflecting the knowledge that the diagnostic pathological findings may be absent in patients with clinically typical IBM. The role of MRI in IBM is expanding and knowledge about pathological biomarkers is increasing. The recent description of autoantibodies to cytosolic 5' nucleotidase 1A in patients with IBM is a potentially important advance that may aid early diagnosis and provides new evidence regarding the role of autoimmunity in IBM. SUMMARY: IBM remains an enigmatic and often misdiagnosed disease. The pathogenesis of the disease is still not fully understood. To date, pharmacological treatment trials have failed to show clear efficacy. Future research should continue to focus on improving understanding of the pathophysiological mechanisms of the disease and on the identification of reliable and sensitive outcome measures for clinical trials. IBM is a rare disease and international multicentre collaboration for trials is important to translate research advances into improved patient outcomes.

[Inclusion body myositis--a rarely recognized disorder]. / Zárványtestes myositis--egy ritikán felismert betegség.

Inclusion body myositis is the most common disabling inflammatory myopathy in the elderly. It is more frequent in men and after the age of 50 years. Inflammatory and degenerative features coexist. There is a T-cell mediated autoimmunity driven by in situ clonally expanded cytotoxic CD8-positive T-cells invading non-necrotic muscle fibres expressing MHC-I antigen. The hallmarks of degeneration are the deposition of protein aggregates and the formation of vesicles. The course of the disease is slow and the diagnosis is usually set after several years. The muscle weakness and wasting is assymetric, affecting predominantly distal muscles of the upper extremity and proximal muscles of the legs. The signs and clinical course can be characteristic, but the diagnosis is established by muscle biopsy. There is currently no evidence based effective treatment for sIBM. Prednisone, azathioprine, methotrexate, cyclosporine and IFN-beta failed. Oxandrolon did not improve symptoms. Treatment with intravenous immunglobuline (IVIG) induced in some patients a transient improvement of swallowing and of muscle strenght, but the overall study results were negative. A T-cell depleting monoclonal antibody (alemtuzumab), in a small uncontrolled study slowed down disease progression for a six-month period. Repeated muscle biopsies showed the reduction of T-cells in the muscle and the suppression of some degeneration associated molecules. An effective therapeutic mean should act on both aspects of the pathomechanism, on the inflammatory and the degenerative processes as well.

[Inclusion body myositis].

Sporadic inclusion body myositis (sIBM) is an intractable and progressive skeletal muscle disease of unknown cause that has no curative treatment. Its prevalence varies among countries and ethnic groups. The clinical course is slow and chronic worsening. Diagnosis of sIBM is usually made 5 years after onset. Muscle weakness and atrophy in the quadriceps, wrist flexor, and finger flexors are the typical neurological findings of sIBM. Dysphagia and asymmetric weakness are often found as well. Serum creatine kinase is usually below 2,000 IU/L. Muscle biopsy typically reveals endomysial inflammation, invasion of mononuclear cells into non-necrotic fibers, and rimmed vacuoles, suggesting that inflammation and degeneration are coexist in the pathomechanism. The etiology of sIBM is still unknown; however, genetic factors, aging, lifestyle, and environmental factors may be involved. Recent studies have implicated amyloid beta accumulation, defects of proteolysis, and immune system abnormalities in the pathomechanism of sIBM. sIBM is generally refractory to current therapy, such as steroids or immunosuppressants. Recently, alemtuzumab, which targets T cells, has resulted in improvement in quantitative muscle strength testing. New strategies to induce proteolysis and autophagy, accelerate muscle regeneration, inhibit myostatin, and modulate inflammatory cells are promising. Elucidation of the pathomechanism of sIBM is the key to developing effective therapies.

Inclusion body myositis.

PURPOSE OF REVIEW: Sporadic inclusion body myositis (sIBM) is a poorly understood immune and degenerative disease of skeletal muscle. Here, current opinion of the nature of this disease is summarized. RECENT FINDINGS: Recent findings for sIBM include further characterization of muscle involvement through magnetic resonance imaging, the role of muscle as a host for immune cells, progress in the role of extranuclear TDP-43 in causing cellular injury, and the discovery of a new sIBM autoantibody. SUMMARY: sIBM understanding continues to advance, with progress regarding the mechanism of this disease.

Inclusion body myositis: diagnosis, pathogenesis, and treatment options.

Inclusion body myositis (IBM) is the most common acquired myopathy in people older than 50 years. IBM typically presents with distal upper extremity weakness accompanied by proximal lower extremity muscle weakness. Associated clinical findings include asymmetric weakness, foot drop, and dysphagia. The pathogenesis of IBM is not clear. In this article the authors briefly discuss postulated pathogenic mechanisms. Although no proven pharmacotherapy exists, some promising candidates are discussed.