Effect of Alemtuzumab (CAMPATH 1-H) in patients with inclusion-body myositis

Idiopathic inflammatory myopathies: current trends in pathogenesis, clinical features, and up-to-date treatment recommendations

Recently, there have been important advances in the understanding of the pathophysiologic features, assessment, and management of patients with a newly diagnosed idiopathic inflammatory myopathy (IIM). Myositis-specific autoantibodies have been identified to define patient subgroups and offer prognostic implications. Similarly, proinflammatory cytokines, such as interleukin 6 and type 1 interferon-dependent genes, may serve as potential biomarkers of disease activity in adult and juvenile patients with dermatomyositis (DM). Moreover, magnetic resonance imaging has become an important modality for the assessment of muscle inflammation in adult IIM and juvenile DM. Immune-mediated necrotizing myopathies also are being recognized as a subset of IIM triggered by medications such as statins. However, confusion exists regarding effective management strategies for patients with IIM because of the lack of large-scale, randomized, controlled studies. This review focuses primarily on our current management and treatment algorithms for IIM including the care of pediatric patients with juvenile DM. For this review, we conducted a search of PubMed and MEDLINE for articles published from January 1, 1970, to December 1, 2011, using the following search terms: idiopathic inflammatory myopathies, dermatomyositis, polymyositis, juvenile dermatomyositis, sporadic inclusion body myositis, inclusion body myositis, inflammatory myositis, myositis, myopathies, pathogenesis, therapy, and treatment. Studies published in English were selected for inclusion in our review as well as additional articles identified from bibliographies.

Inclusion body myositis associated with Sjögren's syndrome

Inclusion body myositis (IBM) belongs to the group of idiopathic inflammatory myopathies. It is a poorly understood disease, which affects skeletal muscles. IBM usually occurs as an isolated condition, but in some cases, it may be associated with another autoimmune disorder, Sjögren’s syndrome. We report a case of a 47-year-old woman with headaches, symptoms of trigeminal neuralgia, progressive weakness in muscles of the upper and lower extremities and symptoms of dry eyes and mouth. On admission, creatine kinase level was increased to 6,956 IU/mL and lactate dehydrogenase (LDH) to 1,011 U/L in the serum. The increase in inflammatory factor (CRP, ESR) levels was not found. The diagnosis of inclusion body myositis associated with Sjögren’s syndrome was established on the basis of clinical picture and diagnostic tests. In this therapy, methotrexate and methylprednisolone were administered. The considerable improved muscle strength in the upper and lower extremities, improved speech and swallowing, disappearance of headache and reduction in CPK and LDH levels were found 8 months after establishing the diagnosis. Treatment with methotrexate and methylprednisolone improved the clinical symptoms and quality of life of this patient and may offer a therapeutic option for some patients with IBM and concomitant Sjögren’s syndrome.

Inclusion body myositis

The idiopathic inflammatory myopathies are a group of rare disorders that share many similarities. These include dermatomyositis (DM), polymyositis (PM), necrotizing myopathy (NM), and sporadic inclusion body myositis (IBM). Inclusion body myositis is the most common idiopathic inflammatory myopathy after age 50 and it presents with chronic proximal leg and distal arm asymmetric mucle weakness. Despite similarities with PM, it is likely that IBM is primarily a degenerative disorder rather than an inflammatory muscle disease. Inclusion body myositis is associated with a modest degree of creatine kinase (CK) elevation and an abnormal electromyogram demonstrating an irritative myopathy with some chronicity. The muscle histopathology demonstrates inflammatory exudates surrounding and invading nonnecrotic muscle fibers often times accompanied by rimmed vacuoles. In this chapter, we review sporadic IBM. We also examine past, essentially negative, clinical trials in IBM and review ongoing clinical trials. For further details on DM, PM, and NM, the reader is referred to the idiopathic inflammatory myopathies chapter.

Immune-mediated necrotizing myopathy is characterized by a specific Th1-M1 polarized immune profile

Immune-mediated necrotizing myopathy (IMNM) is considered one of the idiopathic inflammatory myopathies, comprising dermatomyositis, polymyositis, and inclusion body myositis. The heterogeneous group of necrotizing myopathies shows a varying amount of necrotic muscle fibers, myophagocytosis, and a sparse inflammatory infiltrate. The underlying immune response in necrotizing myopathy has not yet been addressed in detail. Affected muscle tissue, obtained from 16 patients with IMNM, was analyzed compared with eight non-IMNM (nIMNM) tissues. Inflammatory cells were characterized by IHC, and immune mediators were assessed by quantitative real-time PCR. We demonstrate that immune- and non-immune-mediated disease can be distinguished by a specific immune profile with significantly more prominent major histocompatibility complex class I expression and complement deposition and a conspicuous inflammatory infiltrate. In addition, patients with IMNM exhibit a strong type 1 helper T cell (T1)/classically activated macrophage M1 response, with detection of elevated interferon-γ, tumor necrosis factor-α, IL-12, and STAT1 levels in the muscle tissue, which may serve as biomarkers and aid in diagnostic decisions. Furthermore, B cells and high expression of the chemoattractant CXCL13 were identified in a subgroup of patients with defined autoantibodies. Taken together, we propose a diagnostic armamentarium that allows for clear differentiation between IMNM and nIMNM. In addition, we have characterized a Th1-driven, M1-mediated immune response in most of the autoimmune necrotizing myopathies, which may guide therapeutic options in the future.

Novel approaches in the treatment of myositis and myopathies

The inflammatory myopathies are a heterogeneous group of disorders characterized by muscle weakness and inflammation. Although no standard therapeutic guidelines exist, traditional treatment has included corticosteroids and a variety of second-line immunosuppressants. As treatment of refractory disease has been difficult, newer agents and approaches have been used with varying response. The advent of standardized treatment response criteria by the International Myositis Assessment and Clinical Studies (IMACS) group has helped investigators to evaluate and compare clinical trial outcomes in a more rigorous fashion. The use of intravenous immunoglobulin (IVIG), rituximab, biologic agents including tumor necrosis factor (TNF) inhibitors, stem-cell transplantation, gene therapy, and vascular occlusion resistance training are reviewed here. As our understanding of disease pathogenesis at the immunologic, genetic, and molecular level expands, the discovery of novel therapeutic targets hold promise for the successful treatment of these conditions.

Diagnosis and treatment of the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies (IIMs) are rare disorders with the unifying feature of proximal muscle weakness. These diseases include polymyositis(PM), dermatomyositis (DM) and inclusion body myositis (IBM) as the most common. The diagnosis is based on the finding of weakness on exam, elevated muscles enzymes, characteristic histopathology of muscle biopsies, electromyography abnormalities and rash in DM. Myositis-specific antibodies have been helpful in defining subsets of patients with different responses to treatment and prognosis. The cornerstone of therapy is corticosteroids with the addition of other immunosuppressives in severe or refractory disease or patients with intolerable side effects. IBM is particularly difficult to treat but is more slowly progressive as compared with PM or DM. There is still a great need to find more effective and less-toxic therapies.

Autoimmune neuromuscular disorders

Autoimmune neuromuscular disorders affecting peripheral nerves, neuromuscular junction or muscle have a wide clinical spectrum with diverse pathogenetic mechanisms. Peripheral nervous system may be targeted in the context of complex immune reactions involving different cytokines, antigen-presenting cells, B cells and different types of T cells. Various immunomodulating and cytotoxic treatments block proliferation or activation of immune cells by different mechanisms attempting to control the response of the immune system and limit target organ injury. Most treatment protocols for autoimmune neuromuscular disorders are based on the use of corticosteroids, intravenous immunoglobulins and plasmapheresis, with cytotoxic agents mostly used as steroid-sparing medications. More recently, development of specific monoclonal antibodies targeting individual cell types allowed a different approach targeting specific immune pathways, but these new treatments are also associated with various adverse effects and their long-term efficacy is still unknown.

Inclusion body myositis: therapeutic approaches

The idiopathic inflammatory myopathies are a heterogeneous group of diseases that include dermatomyositis (DM), polymyositis (PM), inclusion body myositis (IBM) and other less common myopathies. These are clinically and histopathologically distinct diseases with many shared clinical features. IBM, the most commonly acquired inflammatory muscle disease occurs in individuals aged over 50 years, and is characterized by slowly progressive muscle weakness and atrophy affecting proximal and distal muscle groups, often asymmetrically. Unlike DM and PM, IBM is typically refractory to immunotherapy. Although corticosteroids have not been tested in randomized controlled trials, the general consensus is that they are not efficacious. There is some suggestion that intravenous immunoglobulin slows disease progression, but its long-term effectiveness is unclear. The evidence for other immunosuppressive therapies has been derived mainly from case reports and open studies and the results are discouraging. Only a few clinical trials have been conducted on IBM, making it difficult to provide clear recommendations for treatment. Moreover, IBM is a slowly progressive disease so assessment of treatment efficacy is problematic due to the longer-duration trials needed to determine treatment effects. Newer therapies may be promising, but further investigation to document efficacy would be expensive given the aforementioned need for longer trials. In this review, various treatments that have been employed in IBM will be discussed even though none of the interventions has sufficient evidence to support its routine use.

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.

Clinical trials roundup in idiopathic inflammatory myopathies

PURPOSE OF REVIEW

To review recent advances in the treatment of idiopathic inflammatory myopathies (IIMs) with emphasis on new biological agents and on some less commonly used immunosuppressive drugs.

RECENT FINDINGS

Double-blinded comparison of oral high-dose pulse dexamethasone with standard high daily prednisolone doses showed similar efficacy in the composite score, significantly longer median time to relapse with prednisolone and fewer side effects with dexamethasone treatment. Use of intravenous immunoglobulins (IVIGs) in IIMs is associated with variable results; however, recent retrospective evaluation of IVIGs administration to steroid-resistant patients with esophageal involvement showed good effect. Whereas smaller open studies with rituximab reported a very good efficacy, even in notoriously difficult-to-treat anti-signal recognition particle-positive cases, the double-blind trial has not reached the primary endpoint. Studies with TNF neutralization are reporting results ranging from only a modest or no effect to a promising outcome in the most recent trial with etanercept. Pilot studies suggest efficacy of alemtuzumab in inclusion body myositis and allogeneic mesenchymal stem cell transplantation in polymyositis/dermatomyositis.

SUMMARY

Unmet need for efficacious therapy in IIMs exists and therefore a coordinated effort is necessary to properly evaluate various new classical and biological agents.

Inflammatory myopathies: management of steroid resistance

PURPOSE OF REVIEW

The inflammatory myopathies include polymyositis, dermatomyositis, necrotizing autoimmune myopathy (NAM), and inclusion body myositis (IBM). On the basis of clinical experience, most patients respond to corticosterioids to some degree or for a time period. For patients insufficiently responding or for steroid-sparing, the treatment options vary among practitioners, generating a genuine uncertainty. This timely review highlights emerging new therapies and provides practical therapeutic algorithms.

RECENT FINDINGS

For patients insufficiently responding to corticosteroids, the commonly used immunosuppressants, such as azathioprine, mycophenolate, methotrexate, or cyclosporine, may exert a nonevidence-based 'steroid-sparing' effect but provide minimal benefit on their own. The second line therapy is intravenous immunoglobulin (IVIg) based on a controlled study conducted in dermatomyositis; the drug is also effective in many patients with polymyositis and NAM. Rituximab and tacrolimus may offer additional benefit. Anti-TNF agents are disappointing. IBM remains difficult to treat; although early on some patients may partially respond to steroids or IVIg, they soon become unresponsive and the disease progresses. Emerging agents against T cells, B cells, and transmigration molecules are discussed as promising therapeutic options.

SUMMARY

New biological agents are in the offing for control trials. Appropriate outcome measures are however needed to assess and monitor responses.

Monoclonal antibodies and recombinant immunoglobulins for the treatment of multiple sclerosis

Multiple sclerosis (MS) is an inflammatory and degenerative disease leading to demyelination and axonal damage in the CNS. Autoimmunity plays a central role in MS pathogenesis. Per definition, monoclonal antibodies are recombinant biological compounds with a well defined target, thus carrying the promise of targeting pathogenic cells or molecules with high specificity, avoiding undesired off-target effects. Natalizumab was the first monoclonal antibody to be approved for the treatment of MS. Several other monoclonal antibodies are in development and have demonstrated promising efficacy in phase II studies. They can be categorized according to their mode of action into compounds targeting (i) leukocyte migration into the CNS (natalizumab); (ii) cytolytic antibodies (rituximab, ocrelizumab, ofatumumab, alemtuzumab); or (iii) antibodies and recombinant proteins targeting cytokines and chemokines and their receptors (daclizumab, ustekinumab, atacicept, tabalumab [Ly-2127399], secukinumab [AIN457]). In this review, we discuss the specific molecular targets, clinical efficacy and safety of these compounds and discuss criteria to anticipate the position of monoclonal antibodies in the diversifying armamentarium of MS therapy in the coming years.

Long-term observational study of sporadic inclusion body myositis

We describe a long-term observational study of a large cohort of patients with sporadic inclusion body myositis and propose a sporadic inclusion body myositis weakness composite index that is easy to perform during a clinic. Data collection from two groups of patients (Paris and Oxford) was completed either during a clinic visit (52%), or by extraction from previous medical records (48%). One hundred and thirty-six patients [57% males, 61 (interquartile range 55-69) years at onset] were included. At the last visit all patients had muscle weakness (proximal British Medical Research Council scale <3/5 in 48%, distal British Medical Research Council scale <3/5 in 40%, swallowing problems in 46%). During their follow-up, 75% of patients had significant walking difficulties and 37% used a wheelchair (after a median duration from onset of 14 years). The sporadic inclusion body myositis weakness composite index, which correlated with grip strength (correlation coefficient: 0.47; P < 0.001) and Rivermead Mobility Index (correlation coefficient: 0.85; P < 0.001), decreased significantly with disease duration (correlation coefficient: -0.47; P < 0.001). The risk of death was only influenced by older age at onset of first symptoms. Seventy-one (52%) patients received immunosuppressive treatments [prednisone in 91.5%, associated (in 64.8%) with other immunomodulatory drugs (intravenous immunoglobulins, methotrexate or azathioprine) for a median duration of 40.8 months]. At the last assessment, patients who had been treated were more severely affected on disability scales (Walton P = 0.007, Rivermead Mobility Index P = 0.004) and on the sporadic inclusion body myositis weakness composite index (P = 0.04). The first stage of disease progression towards handicap for walking was more rapid among patients receiving immunosuppressive treatments (hazard ratio = 2.0, P = 0.002). This study confirms that sporadic inclusion body myositis is slowly progressive but not lethal and that immunosuppressive treatments do not ameliorate its natural course, thus confirming findings from smaller studies. Furthermore, our findings suggest that immunosuppressant drug therapy could have modestly exacerbated progression of disability. The sporadic inclusion body myositis weakness composite index might be a valuable outcome measure for future clinical trials, but requires further assessment and validation.

A 12-year follow-up in sporadic inclusion body myositis: an end stage with major disabilities

Sporadic inclusion body myositis is considered to be a slowly progressive myopathy. Long-term follow-up data are, however, not yet available. Follow-up data are important with a view to informing patients about their prognosis and selecting appropriate outcome measures for clinical trials. We performed a follow-up study of 64 patients with sporadic inclusion body myositis who participated in a national epidemiological study in the Netherlands. Case histories were recorded, and manual and quantitative muscle tests as well as laboratory tests were performed at baseline and 12 years (median) after the first out-patient visit. Date and cause of death were recorded for all deceased patients. Forty-six patients died during the follow-up period, two patients chose not to participate and one patient was lost to follow-up. The remaining 15 surviving patients had a mean disease duration of 20 years and were clinically evaluated at the second time point. The mean decline in strength was 3.5 and 5.4% per year according to the manual muscle testing and quantitative muscle testing, respectively. This decline was most pronounced in the lower legs, which were also the weakest extremities. Life expectancy was normal at 81 years, but activities of daily life were clearly restricted. At follow-up, all patients were found to be using a wheelchair, seven of them (47%) being completely wheelchair-bound. Disorders of the respiratory system were the most common cause of death. In three patients, euthanasia was requested and in another three, continuous deep sedation was applied. The fact that end-of-life care interventions were used in six patients (13%) reflects the severe disability and loss of quality of life at the end stage of this disease. Sporadic inclusion body myositis is a chronic progressive disorder, leading to major disabilities at the end stage of the disease due to extensive muscle weakness.

Pathogenesis and therapies of immune-mediated myopathies

The most common autoimmune muscle disorders include dermatomyositis (DM), polymyositis (PM), necrotizing autoimmune myositis (NAM) and sporadic inclusion body myositis (sIBM). DM is a complement-mediated microangiopathy leading to destruction of capillaries, hypoperfusion and inflammatory cell stress on the perifascicular regions. NAM is an increasingly recognized subacute myopathy triggered by statins, viral infections, cancer or autoimmunity with macrophages as the final effector cells causing fiber injury. PM and IBM are T cell-mediated disorders where cytotoxic CD8(+) T cells clonally expand in situ and invade major histocompatibility complex class I expressing muscle fibers. In sIBM, in addition to autoreactive T cells, there are degenerative features characterized by vacuolization and accumulation of stressor or amyloid-related misfolded proteins; an interrelationship between inflammatory and degeneration-associated molecules is prominent and enhances the cascade of pathogenic factors. These disorders are treatable, hence the need to make the correct diagnosis from the outset. The applied therapeutic strategies are outlined and the promising new agents are reviewed.

[Monoclonal antibodies in inflammatory disease of the muscle and peripheral nervous system]

INTRODUCTION

A significant group of neuromuscular diseases are of autoimmune origin, but the classic immunomodulatory drugs are not often effective. For this reason, there is a need to find new more effective treatments that will lead to better control of these conditions, particularly those that are usually more resistant. In the last few years, the use of monoclonal antibodies against specific antigens of lymphocyte populations or against pro-inflammatory molecules has seen a great expansion, and has been demonstrated to be a useful alternative in autoimmune diseases. An intensive search was made in Medline using the Keywords neuromuscular, myopathy, neuropathy, myasthenia, Lambert-Eaton, monoclonal antibody, rituximab, alemtuzumab, and anti-TNF-α.

DEVELOPMENT

Clinical trials performed to evaluate the efficacy of monoclonal antibodies in neuromuscular disease are very limited and of reduced size. Thus, the experience in this field is basically limited to anecdotal cases or short series of patients on open-label treatment. The published data are encouraging, with favourable responses having been observed in patients resistant to classic treatments and in diseases that do not normally respond to the usual immunosuppressant drugs. On the other hand, it has been observed that anti-TNF-α antibodies may trigger the appearance of autoimmune neuromuscular diseases.

CONCLUSIONS

Monoclonal antibodies could be an effective alternative treatment in autoimmune neuromuscular diseases, but the favourable responses observed need to be confirmed by means of controlled clinical trials with a sufficient number of patients.

Pathophysiology of inflammatory and autoimmune myopathies

The main subtypes of inflammatory myopathies include dermatomyositis (DM), polymyositis (PM), necrotizing autoimmune myositis (NAM) and sporadic inclusion-body myositis (sIBM). The review provides an update on the main clinical characteristics unique to each subset, including fundamental aspects on muscle pathology helpful to assure accurate diagnosis, underlying immunopathomechanisms and therapeutic strategies. DM is a complement-mediated microangiopathy leading to destruction of capillaries, distal hypoperfusion and inflammatory cell stress on the perifascicular regions. NAM is an increasingly recognized subacute myopathy triggered by statins, viral infections, cancer or autoimmunity with macrophages as the final effector cells mediating fiber injury. PM and IBM are characterized by cytotoxic CD8-positive T cells which clonally expand in situ and invade MHC-I-expressing muscle fibers. In IBM, in addition to autoimmunity, there is vacuolization and intrafiber accumulation of degenerative and stressor molecules. Pro-inflammatory mediators, such as gamma interferon and interleukin IL1-β, seem to enhance the accumulation of stressor and amyloid-related misfolded proteins. Current therapies using various immunosuppressive and immunomodulating drugs are discussed for PM, DM and NAM, and the principles for effective treatment strategies in IBM are outlined.

Deciphering the clinical presentations, pathogenesis, and treatment of the idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies or myositis syndromes (the most common forms are polymyositis, dermatomyositis, and inclusion body myositis) are systemic autoimmune diseases defined by chronic muscle weakness and inflammation of unknown etiology and result in significant morbidity and mortality. Research suggests that categorizing heterogeneous myositis syndromes into mutually exclusive and stable phenotypes by using clinical and immune response features is useful for predicting clinical signs and symptoms, associated genetic and environmental risk factors, and responses to therapy and prognosis. Knowledge of myositis phenotypes should enhance clinicians' ability to recognize and manage these rare disorders.

Therapy update in nerve, neuromuscular junction and myopathic disorders

PURPOSE OF REVIEW

The objective of this review is to summarize recent advances in the treatment of various neuromuscular disorders including neuropathies, neuromuscular junction disorders, and myopathies.

RECENT FINDINGS

Immunotherapy with sophisticated agents for myasthenia gravis and inflammatory myopathies, neuroprotection with vitamin E for chemotherapy-induced neuropathy, and promising gene transfer and exon-skipping therapies for muscular dystrophy are among the most exciting recent developments in the treatment of neuromuscular disorders.

SUMMARY

In spite of significant advances, therapy in many neuromuscular diseases remains far from satisfactory. Better understanding of the underlying molecular and pathophysiologic processes for both hereditary and acquired disorders should lead to more refined and successful therapeutic approaches, reducing physical and other types of disability while posing fewer side effects.

Inclusion-body myositis in the elderly: an update

Sporadic inclusion-body myositis is a common inflammatory myopathy, which is often misdiagnosed. In contrast to other forms of myositis, no effective treatment is available. The disease leads to severe wasting of the quadriceps and long-finger flexors, so patients gradually lose ambulation and hand-grip strength. The pathology includes an intrafiber accumulation of aberrant molecules, such as β-amyloid, as well as an inflammatory cascade, with overexpression of key cytokines and chemokines, and the attack of muscle fibers by autoaggressive cytotoxic T cells. Recent data point to an early cell-stress response in muscle fibers and a unique interplay between inflammatory and degenerative pathomechanisms. Current efforts aim to improve methods for early diagnosis and design more effective targeted treatment strategies. This article will highlight recent advances in understanding the disease pathology, and how to identify promising candidate molecules for future clinical trials.

Expanded T cell receptor Vβ-restricted T cells from patients with sporadic inclusion body myositis are proinflammatory and cytotoxic CD28null T cells

OBJECTIVE

Sporadic inclusion body myositis (IBM) is characterized by T cell infiltrates in muscle tissue, but their functional role is unclear. Systemic signs of inflammation are lacking, and the absence of beneficial effects following immunosuppression has challenged the notion of a role for the immune system. This study was undertaken to investigate the phenotype and functionality of T cells, specifically a subset of proinflammatory, cytotoxic, and apoptosis-resistant T cells defined as CD28(null) T cells, in the pathogenesis of sporadic IBM.

METHODS

A cohort of 27 patients with sporadic IBM was analyzed for the frequency of circulating and muscle-infiltrating CD28(null) T cells. The T cell receptor (TCR) V(β) usage was determined using flow cytometry and immunohistochemistry. Anti-CD3-stimulated peripheral blood mononuclear cells were analyzed for intracellular interferon-γ and cytotoxic potential by flow cytometry.

RESULTS

We found striking accumulations of both CD8+CD28(null) and CD4+CD28(null) T cells, which represented the TCR V(β) -expanded T cells in sporadic IBM. Such CD28(null) T cells were abundant both in the inflamed muscle tissue and in the circulation. Although the specific TCR V(β) expansions varied between patients, both CD8+CD28(null) and CD4+CD28(null) T cells consistently displayed a highly proinflammatory and cytotoxic potential.

CONCLUSION

Our results suggest that CD28null T cell expansions represent the previously described expanded T cell subsets in sporadic IBM, and their proinflammatory capacity and presence in both muscle tissue and the circulation may imply a role of immune activation in sporadic IBM. In addition, CD4+CD28(null) T cells may exert cytotoxic effects directly on muscle fibers due to a cytotoxic potential similar to that in CD8+ T cells.

[Therapeutic monoclonal antibodies in clinical neurology]

Recombinant monoclonal antibodies break new ground in the treatment of immune-mediated nerve and muscle disorders but also of neurodegenerative diseases, in the field of neuro-oncology and in pain therapy, as they allow molecular targeting of defined cell populations or key pathophysiological molecules. However, safety risks might accompany a high efficacy. Basic understanding of this increasingly important class of agents and a steady update of knowledge, in particular on safety aspects, are therefore key requirements for responsible use based on an individual benefit-risk assessment.

Sporadic inclusion body myositis: variability in prevalence and phenotype and influence of the MHC

Sporadic inclusion body myositis (sIBM) is the most common myopathy presenting over the age of 40 years but its prevalence varies considerably in different populations. Genetic factors play a part in the pathogenesis of sIBM and in Caucasians susceptibility has been linked to the HLA-DR3 allele and the 8.1 MHC ancestral haplotype (AH) which is also associated with other autoimmune diseases. The variable prevalence of sIBM in different populations may be related to differences in the population frequency of this haplotype. Our recent observations indicate that the clinical phenotype at presentation is also quite variable and that the influence of the MHC is more complex than previously appreciated with HLA alleles also having modifying effects on the age-at-onset, severity and rate of progression of the disease. Recent recombinant mapping studies of polymorphisms in the Class II/III regions of the MHC by our group have further refined the susceptibility region and have identified a number of candidate genes warranting further investigation. The significance of these findings for the pathogenesis of the disease is discussed.