Inclusion body myositis with human immunodeficiency virus infection: four cases with clonal expansion of viral-specific T cells

Autoimmune inflammatory myopathies

The autoimmune inflammatory myopathies constitute a heterogeneous group of acquired myopathies that have in common the presence of endomysial inflammation and moderate to severe muscle weakness. Based on currently evolved distinct clinical, histologic, immunopathologic, and autoantibody features, these disorders can be best classified as dermatomyositis, necrotizing autoimmune myositis, antisynthetase syndrome-overlap myositis, and inclusion body myositis. Although polymyositis is no longer considered a distinct subset but rather an extinct entity, it is herein described because its clinicopathologic information has provided over many years fundamental information on T-cell-mediated myocytotoxicity, especially in reference to inclusion body myositis. Each inflammatory myopathy subset has distinct immunopathogenesis, prognosis, and response to immunotherapies, necessitating the need to correctly diagnose each subtype from the outset and avoid disease mimics. The paper describes the main clinical characteristics that aid in the diagnosis of each myositis subtype, highlights the distinct features on muscle morphology and immunopathology, elaborates on the potential role of autoantibodies in pathogenesis or diagnosis , and clarifies common uncertainties in reference to putative triggering factors such as statins and viruses including the 2019-coronavirus-2 pandemic. It extensively describes the main autoimmune markers related to autoinvasive myocytotoxic T-cells, activated B-cells, complement, cytokines, and the possible role of innate immunity. The concomitant myodegenerative features seen in inclusion body myositis along with their interrelationship between inflammation and degeneration are specifically emphasized. Finally, practical guidelines on the best therapeutic approaches are summarized based on up-to-date knowledge and controlled studies, highlighting the prospects of future immunotherapies and ongoing controversies.

Prevention of Adverse Outcomes and Treatment Side Effects in Patients with Neuromuscular Disorders

In this article, we review prevention of serious adverse clinical outcomes and treatment side effects in patients with neuromuscular disorders including myopathies and myasthenia gravis. While neither of these entities is preventable, their course can often be modified, and severe sequelae may be prevented, with the identification of risk factors and proactive attention toward treatment planning.

Inclusion body myositis and associated diseases: an argument for shared immune pathologies

Inclusion body myositis (IBM) is the most prevalent idiopathic inflammatory myopathy (IIM) affecting older adults. The pathogenic hallmark of IBM is chronic inflammation of skeletal muscle. At present, we do not classify IBM into different sub-entities, with the exception perhaps being the presence or absence of the anti-cN-1A-antibody. In contrast to other IIM, IBM is characterized by a chronic and progressive disease course. Here, we discuss the pathophysiological framework of IBM and highlight the seemingly prototypical situations where IBM occurs in the context of other diseases. In this context, understanding common immune pathways might provide insight into the pathogenesis of IBM. Indeed, IBM is associated with a distinct set of conditions, such as human immunodeficiency virus (HIV) or hepatitis C-two conditions associated with premature immune cell exhaustion. Further, the pathomorphology of IBM is reminiscent of other muscle diseases, notably HIV-associated myositis or granulomatous myositis. Distinct immune pathways are likely to drive these commonalities and senescence of the CD8+ T cell compartment is discussed as a possible mechanism of pathogenesis. Future effort directed at understanding the co-occurrence of IBM and associated diseases could prove valuable to better understand the enigmatic IBM pathophysiology.

Subtlety of Granulomatous Mycosis Fungoides: A Retrospective Case Series Study and Proposal of Helpful Multimodal Diagnostic Approach With Literature Review

ABSTRACT

Granulomatous mycosis fungoides (GMF) harbors a worse prognosis compared with classic MF and remains a significant diagnostic dilemma. We analyzed clinicopathologic, immunophenotypic, and molecular characteristics of GMF to develop a diagnostic algorithm. Our methodology involved a retrospective case series study of patients with GMF from our database between 2014 and 2020. A total of 8 patients with 9 biopsies of GMF were identified. Skin manifestations had variable clinical phenotype. Histologically, all cases demonstrated atypical CD4+ T-cell infiltrate with scant in 50% (n = 4), focal 37.5% (n = 3), and absent 25% (n = 2) epidermotropism. Granuloma formation was seen in 77.8% biopsies (n = 7) with sarcoid-type granulomas in 57.1% (n = 4) and granuloma annulare-like type in 42.9% (n = 3). In 66.7% of biopsies (n = 6), the CD4:CD8 ratio was >4:1 and 66.6% (n = 6) of biopsies showed ≥50% loss of CD7 expression. T-cell receptor gene rearrangement studies performed on biopsy sections were positive in all biopsies (n = 6), whereas peripheral blood T-cell receptor gene rearrangement studies did not identify clonality. In conclusion, GMF has subtle or absent epidermotropism and variable granulomatous reaction; thus, the diagnosis requires a multimodal approach, and our proposed algorithm provides a framework to approach this diagnostic challenge.

Complement in autoimmune inflammatory myopathies, the role of myositis-associated antibodies, COVID-19 associations, and muscle amyloid deposits

INTRODUCTION

The inflammatory myopathies (IM) have now evolved into distinct subsets requiring clarification about their immunopathogenesis to guide applications of targeted therapies.

AREAS COVERED

Immunohistopathologic criteria of IM with a focus on complement, anti-complement therapeutics, and other biologic immunotherapies. The COVID19-triggered muscle autoimmunity along with the correct interpretation of muscle amyloid deposits is discussed.

EXPERT OPINION

The IM, unjustifiably referred as idiopathic, comprise Dermatomyositis (DM), Necrotizing Autoimmune Myositis (NAM), Anti-synthetase syndrome-overlap myositis (Anti-SS-OM), and Inclusion-Body-Myositis (IBM). In DM, complement activation with MAC-mediated endomysial microvascular destruction and perifascicular atrophy is the fundamental process, while innate immunity activation factors, INF1 and MxA, sense and secondarily enhance inflammation. Complement participates in muscle fiber necrosis from any cause and may facilitate muscle-fiber necrosis in NAM but seems unlikely that myositis-associated antibodies participate in complement-fixing. Accordingly, anti-complement therapeutics should be prioritized for DM. SARS-CoV-2 can potentially trigger muscle autoimmunity, but systematic studies are needed as the reported autopsy findings are not clinically relevant. In IBM, tiny amyloid deposits within muscle fibers are enhanced by inflammatory mediators contributing to myodegeneration; in contrast, spotty amyloid deposits in the endomysial connective tissue do not represent 'amyloid myopathy' but only have diagnostic value for amyloidosis due to any cause.

Idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIM), also known as myositis, are a heterogeneous group of autoimmune disorders with varying clinical manifestations, treatment responses and prognoses. Muscle weakness is usually the classical clinical manifestation but other organs can be affected, including the skin, joints, lungs, heart and gastrointestinal tract, and they can even result in the predominant manifestations, supporting that IIM are systemic inflammatory disorders. Different myositis-specific auto-antibodies have been identified and, on the basis of clinical, histopathological and serological features, IIM can be classified into several subgroups - dermatomyositis (including amyopathic dermatomyositis), antisynthetase syndrome, immune-mediated necrotizing myopathy, inclusion body myositis, polymyositis and overlap myositis. The prognoses, treatment responses and organ manifestations vary among these groups, implicating different pathophysiological mechanisms in each subtype. A deeper understanding of the molecular pathways underlying the pathogenesis and identifying the auto-antigens of the immune reactions in these subgroups is crucial to improving outcomes. New, more homogeneous subgroups defined by auto-antibodies may help define disease mechanisms and will also be important in future clinical trials for the development of targeted therapies and in identifying biomarkers to guide treatment decisions for the individual patient.

Inflammatory myopathies: update on diagnosis, pathogenesis and therapies, and COVID-19-related implications

The inflammatory myopathies constitute a heterogeneous group of acquired myopathies that have in common the presence of endomysial inflammation. Based on steadily evolved clinical, histological and immunopathological features and some autoantibody associations, these disorders can now be classified in five characteristic subsets: Dermatomyositis (DM) Polymyositis (PM), Necrotizing Autoimmune Myositis (NAM), Anti-synthetase syndrome-overlap myositis (Anti-SS-OM), and Inclusion-Body-Myositis (IBM). Each inflammatory myopathy subset has distinct immunopathogenesis, prognosis and response to immunotherapies, necessitating the need to correctly identify each subtype from the outset to avoid disease mimics and proceed to early therapy initiation. The review presents the main clinicopathologic characteristics of each subset highlighting the importance of combining expertise in clinical neurological examination with muscle morphology and immunopathology to avoid erroneous diagnoses and therapeutic schemes. The main autoimmune markers related to autoreactive T cells, B cells, autoantibodies and cytokines are presented and the concomitant myodegenerative features seen in IBM muscles are pointed out. Most importantly, unsettled issues related to a role of autoantibodies and controversies with reference to possible triggering factors related to statins are clarified. The emerging effect SARS-CoV-2 as the cause of hyperCKemia and potentially NAM is addressed and practical guidelines on the best therapeutic approaches and concerns regarding immunotherapies during COVID-19 pandemic are summarized.

Guillain-Barré syndrome: The first documented COVID-19-triggered autoimmune neurologic disease: More to come with myositis in the offing

Objective

To present the COVID-19–associated GBS, the prototypic viral-triggered autoimmune disease, in the context of other emerging COVID-19–triggered autoimmunities, and discuss potential concerns with ongoing neuroimmunotherapies.

Methods

Eleven GBS cases in four key COVID-19 hotspots are discussed regarding presenting symptoms, response to therapies and cross-reactivity of COVID spike proteins with nerve glycolipids. Emerging cases of COVID-19–triggered autoimmune necrotizing myositis (NAM) and encephalopathies are also reviewed in the context of viral invasion, autoimmunity and ongoing immunotherapies.

Results

Collective data indicate that in this pandemic any patient presenting with an acute paralytic disease-like GBS, encephalomyelitis or myositis-even without systemic symptoms, may represent the first manifestation of COVID-19. Anosmia, ageusia, other cranial neuropathies and lymphocytopenia are red flags enhancing early diagnostic suspicion. In Miller-Fisher Syndrome, ganglioside antibodies against GD1b, instead of QG1b, were found; because the COVID-19 spike protein also binds to sialic acid-containing glycoproteins for cell-entry and anti-GD1b antibodies typically cause ataxic neuropathy, cross-reactivity between COVID-19–bearing gangliosides and peripheral nerve glycolipids was addressed. Elevated Creatine Kinase (>10,000) is reported in 10% of COVID-19–infected patients; two such patients presented with painful muscle weakness responding to IVIg indicating that COVID-19–triggered NAM is an overlooked entity. Cases of acute necrotizing brainstem encephalitis, cranial neuropathies with leptomeningeal enhancement, and tumefactive postgadolinium-enhanced demyelinating lesions are now emerging with the need to explore neuroinvasion and autoimmunity. Concerns for modifications-if any-of chronic immunotherapies with steroids, mycophenolate, azathioprine, IVIg, and anti-B-cell agents were addressed; the role of complement in innate immunity to viral responses and anti-complement therapeutics (i.e. eculizumab) were reviewed.

Conclusions

Emerging data indicate that COVID-19 can trigger not only GBS but other autoimmune neurological diseases necessitating vigilance for early diagnosis and therapy initiation. Although COVID-19 infection, like most other viruses, can potentially worsen patients with pre-existing autoimmunity, there is no evidence that patients with autoimmune neurological diseases stable on common immunotherapies are facing increased risks of infection.

Risk factors and disease mechanisms in myositis

Autoimmune diseases develop as a result of chronic inflammation owing to interactions between genes and the environment. However, the mechanisms by which autoimmune diseases evolve remain poorly understood. Newly discovered risk factors and pathogenic processes in the various idiopathic inflammatory myopathy (IIM) phenotypes (known collectively as myositis) have illuminated innovative approaches for understanding these diseases. The HLA 8.1 ancestral haplotype is a key risk factor for major IIM phenotypes in some populations, and several genetic variants associated with other autoimmune diseases have been identified as IIM risk factors. Environmental risk factors are less well studied than genetic factors but might include viruses, bacteria, ultraviolet radiation, smoking, occupational and perinatal exposures and a growing list of drugs (including biologic agents) and dietary supplements. Disease mechanisms vary by phenotype, with evidence of shared innate and adaptive immune and metabolic pathways in some phenotypes but unique pathways in others. The heterogeneity and rarity of the IIMs make advancements in diagnosis and treatment cumbersome. Novel approaches, better-defined phenotypes, and international, multidisciplinary consensus have contributed to progress, and it is hoped that these methods will eventually enable therapeutic intervention before the onset or major progression of disease. In the future, preemptive strategies for IIM management might be possible.

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 and human immunodeficiency virus type 1: A new case report and literature review

Prevalence of muscle disease in human immunodeficiency virus (HIV) infection is less than 1% of patients with acquired immune deficiency syndrome. Sporadic inclusion body myositis (IBM) is observed in a few cases of patients infected by retroviruses such as HIV-1. A Caucasian man was diagnosed with HIV when he was 30 years old. The viral load was undetectable and CD4 cell count was 600/mm³ when the diagnosis of inclusion body myositis was confirmed. Histological findings were typical of IBM. The treatment consisted of immunoglobulin therapy for three years without effect. Twenty-two patients were found in the English and French literature. They are younger than those who suffer from IBM without HIV (median age = 47, range: 30 to 59), and they are mostly men with considerable serum creatine kinase (CK) elevation (median CK level = 1322 IU/L, range: 465 to 10270), most of them were treated with Zidovudine.

Neuromuscular complications of HIV infection

With the introduction of combination antiretroviral therapy, human immunodeficiency virus (HIV)-infected individuals are living longer, and are commonly confronted with chronic neuromuscular complications. The spectrum of neuromuscular disorders in patients living with HIV infection is wide, and is caused by HIV per se and its products, particular antiretroviral drugs, or a combination of both. The purpose of this chapter is to review peripheral nervous system disorders in the setting of HIV infection, and to provide a general approach to diagnosis and management of these disorders. The early identification of these conditions may help with early intervention and management, allow prevention of morbidities associated with these disorders, and contribute to future research efforts in the field of HIV.

Immune and myodegenerative pathomechanisms in inclusion body myositis

Inclusion Body Myositis (IBM) is a relatively common acquired inflammatory myopathy in patients above 50 years of age. Pathological hallmarks of IBM are intramyofiber protein inclusions and endomysial inflammation, indicating that both myodegenerative and inflammatory mechanisms contribute to its pathogenesis. Impaired protein degradation by the autophagic machinery, which regulates innate and adaptive immune responses, in skeletal muscle fibers has recently been identified as a potential key pathomechanism in IBM. Immunotherapies, which are successfully used for treating other inflammatory myopathies lack efficacy in IBM and so far no effective treatment is available. Thus, a better understanding of the mechanistic pathways underlying progressive muscle weakness and atrophy in IBM is crucial in identifying novel promising targets for therapeutic intervention. Here, we discuss recent insights into the pathomechanistic network of mutually dependent inflammatory and degenerative events during IBM.

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.

Hepatitis C virus infection in inclusion body myositis: A case-control study

OBJECTIVE

To clarify whether there is any association between inclusion body myositis (IBM) and hepatitis C virus (HCV) infection.

METHODS

We assessed the prevalence of HCV infection in 114 patients with IBM whose muscle biopsies were analyzed pathologically for diagnostic purpose from 2002 to 2012 and in 44 age-matched patients with polymyositis diagnosed in the same period as a control by administering a questionnaire survey to the physicians in charge. We also compared clinicopathologic features including the duration from onset to development of representative symptoms of IBM and the extent of representative pathologic changes between patients with IBM with and without HCV infection.

RESULTS

A significantly higher number of patients with IBM (28%) had anti-HCV antibodies as compared with patients with polymyositis (4.5%; odds ratio 8.2, 95% confidence interval 1.9-36) and the general Japanese population in their 60s (3.4%). Furthermore, between patients with IBM with and without HCV infection, we did not find any significant difference in the clinicopathologic features, indicating that the 2 groups have essentially the same disease regardless of HCV infection.

CONCLUSION

Our results provide the statistical evidence for an association between IBM and HCV infection, suggesting a possible pathomechanistic link between the 2 conditions.

Idiopathic inflammatory myopathies: from immunopathogenesis to new therapeutic targets

Pathogenesis of idiopathic inflammatory myositis (IIM) involves strong interactions between dendritic cells (DCs), activated Th1 and Th17 cells, B cells, muscle cells, genes and environment. Local maturation of DCs permit the activation and polarization of CD4+ T cells into T(H)1 and T(H)17 that play a key role in maintaining chronic muscle inflammation. T-cell mediated myocytotoxicity promotes the liberation of specific muscle autoantigens from regenerating muscle cells with production of myositis-specific autoantibodies. Type I interferon signature is a key characteristic of IIM. Type I IFN that can be induced by immune complexes containing myositis-specific autoantibodies is produced by scattered plasmacytoid DCs but also by muscle cells particularly regenerating muscle cells. These immature muscle precursors appear to be critical in the pathogenesis of IIM as they up-regulate muscle autoantigens, type I IFN, HLA class I antigens and TLR3-7, all together involved in maintaining chronic muscle inflammation. In addition to the role of immune and muscle cells, genome-wide association studies have confirmed the importance of several MHC and non-MHC genes in IIM. Environmental factors can contribute to the pathogenesis of IIM. In sIBM, distinct features suggest both degenerative and inflammatory processes. In addition to our better understanding of the pathogenesis, identify molecular pathway leads to consider new targeted therapies including cytokine inhibition, B-cell and T-cell costimulation blockade, type I IFN neutralization or inhibition of the ubiquitin proteasome pathway.

[New aspects on the pathogenesis of myositis]

Idiopathic inflammatory myopathies (IIM) are chronic inflammatory diseases of muscle characterized by proximal muscle weakness. There are three main groups of diseases, dermatomyositis, polymyositis and inclusion body myositis. The muscle tissue is invaded by the humoral autoantibody producing immune system (B-cells) and by the cellular immune system with autoaggressive and inflammation modulating cells (e.g. dendritic cells, monocytes/macrophages, CD4 + and CD8 + T-cells and natural killer cells). The presence of specific or associated autoantibodies and inflammatory cellular infiltrates with cytotoxic and immune autoreactive properties are characteristic for IIM diseases. The pathogenesis is still unknown; nevertheless, there are several hints that exogenic factors might be involved in initiation and disease progression and bacterial, fungal and viral infections are thought to be possible initiators. Up to now information on prognostic markers to help with decision-making for individual treatment are limited. In addition, there has been only limited therapeutic success including conventional or novel drugs and biologicals and comparative validation studies are needed using similar outcome measurements. Moreover, to facilitate the use and development of novel therapies, elaboration of intracellular and cell-specific regulation could be useful to understand the etiopathogenesis and allow a better diagnosis, prognosis and possibly also a prediction for individualized subgroup treatment.

Clonal expansions of CD8+ T cells with IL-10 secreting capacity occur during chronic Mycobacterium tuberculosis infection

The exact role of CD8⁺ T cells during Mycobacterium tuberculosis (Mtb) infection has been heavily debated, yet it is generally accepted that CD8⁺ T cells contribute to protection against Mtb. In this study, however, we show that the Mtb-susceptible CBA/J mouse strain accumulates large numbers of CD8⁺ T cells in the lung as infection progresses, and that these cells display a dysfunctional and immunosuppressive phenotype (PD-1⁺, Tim-3⁺, CD122⁺). CD8⁺ T cell expansions from the lungs of Mtb-infected CBA/J mice were also capable of secreting the immunosuppressive cytokine interleukin-10 (IL-10), although in vivo CD8⁺ T cell depletion did not significantly alter Mtb burden. Further analysis revealed that pulmonary CD8⁺ T cells from Mtb-infected CBA/J mice were clonally expanded, preferentially expressing T cell receptor (TcR) Vβ chain 8 (8.2, 8.3) or Vβ 14. Although Vβ8⁺ CD8⁺ T cells were responsible for the majority of IL-10 production, in vivo depletion of Vβ8⁺ did not significantly change the outcome of Mtb infection, which we hypothesize was a consequence of their dual IL-10/IFN-γ secreting profiles. Our data demonstrate that IL-10-secreting CD8⁺ T cells can arise during chronic Mtb infection, although the significance of this T cell population in tuberculosis pathogenesis remains unclear.

Neuromuscular manifestations of HIV/AIDS

The human immunodeficiency virus (HIV) epidemic, now entering its fourth decade, affects approximately 33 million people living in both developed and resource-limited countries. Neurological complications of the peripheral nervous system are common in HIV-infected patients, and neuromuscular pathology is associated with significant morbidity. Peripheral neuropathy is the most common neuromuscular manifestation observed in HIV/AIDS, and in the antiretroviral era, its prevalence has increased. The purpose of this review was to describe the clinical spectrum of neuromuscular disorders in the setting of HIV infection and to provide an approach to diagnosis and management.

Stepwise approach to myopathy in systemic disease

Muscle diseases can constitute a large variety of both acquired and hereditary disorders. Myopathies in systemic disease results from several different disease processes including endocrine, inflammatory, paraneoplastic, infectious, drug- and toxin-induced, critical illness myopathy, metabolic, and myopathies with other systemic disorders. Patients with systemic myopathies often present acutely or sub acutely. On the other hand, familial myopathies or dystrophies generally present in a chronic fashion with exceptions of metabolic myopathies where symptoms on occasion can be precipitated acutely. Most of the inflammatory myopathies can have a chance association with malignant lesions; the incidence appears to be specifically increased only in patients with dermatomyositis. In dealing with myopathies associated with systemic illnesses, the focus will be on the acquired causes. Management is beyond the scope of this chapter. Prognosis is based upon the underlying cause and, most of the time, carries a good prognosis. In order to approach a patient with suspected myopathy from systemic disease, a stepwise approach is utilized.

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.

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.

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.

Polymyositis in African HIV-infected subjects

Polymyositis in HIV-infected subjects, clinically and pathologically resemble polymyositis in non-HIV-infected subjects. We report 14 consecutive HIV-associated polymyositis cases and compare specific features with 25 polymyositis cases seen over the same 6.5 year period. The HIV-polymyositis cases were all female and compared to the polymyositis cases were younger (median age 33 years, interquartile range (IQR) 29; 37 vs. 46 years, IQR 38; 52, p=0.002), and with 4-fold lower serum creatine kinase (CK) values (median 1158 vs. 5153IU/l; p=0.019). A definite clinical improvement on prednisone therapy was documented in eight HIV-polymyositis cases and one improved with anti-retroviral therapy alone. The recognition of HIV-polymyositis which is treatable, but may present with serum CK elevations less than twofolds above normal, is clinically relevant in sub-Saharan Africa where electromyography and muscle biopsies are not readily available.

Neuromuscular diseases associated with HIV-1 infection

Neuromuscular disorders are common in human immunodeficiency virus (HIV); they occur at all stages of disease and affect all parts of the peripheral nervous system. These disorders have diverse etiologies including HIV itself, immune suppression and dysregulation, comorbid illnesses and infections, and side effects of medications. In this article, we review the following HIV-associated conditions: distal symmetric polyneuropathy; inflammatory demyelinating polyneuropathy; mononeuropathy; mononeuropathy multiplex; autonomic neuropathy; progressive polyradiculopathy due to cytomegalovirus; herpes zoster; myopathy; and other, rarer disorders.

Idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies are a group of systemic autoimmune syndromes characterized by striated muscle inflammation. Here, we discuss the clinical features of this group of conditions and review the recent developments in the understanding of the pathogenesis and immunogenetics of the idiopathic inflammatory myopathies. The role of myositis-specific autoantibodies and their clinical significance and an overview of management are also provided.

How citation distortions create unfounded authority: analysis of a citation network

OBJECTIVE

To understand belief in a specific scientific claim by studying the pattern of citations among papers stating it.

DESIGN

A complete citation network was constructed from all PubMed indexed English literature papers addressing the belief that beta amyloid, a protein accumulated in the brain in Alzheimer's disease, is produced by and injures skeletal muscle of patients with inclusion body myositis. Social network theory and graph theory were used to analyse this network.

MAIN OUTCOME MEASURES

Citation bias, amplification, and invention, and their effects on determining authority.

RESULTS

The network contained 242 papers and 675 citations addressing the belief, with 220,553 citation paths supporting it. Unfounded authority was established by citation bias against papers that refuted or weakened the belief; amplification, the marked expansion of the belief system by papers presenting no data addressing it; and forms of invention such as the conversion of hypothesis into fact through citation alone. Extension of this network into text within grants funded by the National Institutes of Health and obtained through the Freedom of Information Act showed the same phenomena present and sometimes used to justify requests for funding.

CONCLUSION

Citation is both an impartial scholarly method and a powerful form of social communication. Through distortions in its social use that include bias, amplification, and invention, citation can be used to generate information cascades resulting in unfounded authority of claims. Construction and analysis of a claim specific citation network may clarify the nature of a published belief system and expose distorted methods of social citation.

Rheumatic conditions in human immunodeficiency virus infection

Many rheumatic diseases have been observed in HIV-infected persons. We, therefore, conducted a comprehensive literature search in order to review the prevalence, presentation and pathogenesis of rheumatic manifestations in HIV-infected subjects. Articular conditions (arthralgia, arthritis and SpAs) are either caused by the HIV infection itself, triggered by adaptive changes in the immune system, or secondary to microbial infections. Muscular symptoms may result from rhabdomyolysis, myositis or from side-effects of highly active anti-retroviral therapy (HAART). Osseous complications include osteonecrosis, osteoporosis and osteomyelitis. Some conditions such as the diffuse infiltrative lymphocytosis syndrome and sarcoidosis affect multiple organ systems. SLE may be observed but may be difficult to differentiate from HIV infection. Some anti-retroviral agents can precipitate hyperuricaemia and are associated with arthralgia. When indicated, immunosuppressants and even anti-TNF-alpha agents can be used in the carefully monitored HIV patient. Thus, rheumatic diseases and asymptomatic immune phenomena remain prevalent in HIV-infected persons even after the widespread implementation of highly active anti-retroviral therapy.

Inclusion body myositis associated with human T-lymphotropic virus-type I infection: eleven patients from an endemic area in Japan

The objective of this study was to investigate the association of human T-lymphotropic virus-type I (HTLV-I) infection with sporadic inclusion body myositis in 11 patients from an endemic area in Japan. The clinical features were consistent with sporadic inclusion body myositis, and anti-HTLV-I antibodies were present in the sera of all patients. Their muscle biopsies showed the diagnostic features of inclusion body myositis, including endomysial T-cell infiltration, rimmed vacuoles, deposits of phosphorylated tau, and abnormal filaments in the nuclei and cytoplasm of the myofibers. The fibers expressed major histocompatibility complex class I antigens and were invaded by CD8 and CD4 cells. In a single human leukocyte antigen-A2-positive patient, in situ human leukocyte antigen-A*0201 / Tax11-19-pentamer staining showed pentamer-positive cells surrounding the muscle fibers. Double-immunogold silver staining and polymerase chain reaction in situ hybridization revealed that HTLV-I proviral DNA was localized on helper-inducer T cells, but not on muscle fibers. Human T-lymphotropic virus-type I proviral loads in peripheral blood mononuclear cells from each patient were similar to those in HTLV-I-associated myelopathy/tropical spastic paraparesis. This study suggests that HTLV-I infection may be one of the causes of sporadic inclusion body myositis, as has been reported in human immunodeficiency virus type-1 infection.

Advances in the immunobiology and treatment of inflammatory myopathies

The clinical spectrum and immunopathogenesis of inflammatory myopathies are summarized with an update on possible triggering factors, cell degeneration, and emerging new therapies.