Autoantibodies against 3-hydroxy-3-methylglutaryl-coenzyme A reductase in patients with statin-associated autoimmune myopathy

OBJECTIVE

In addition to inducing a self-limited myopathy, statin use is associated with an immune-mediated necrotizing myopathy (IMNM), with autoantibodies that recognize ∼200-kd and ∼100-kd autoantigens. The purpose of this study was to identify these molecules to help clarify the disease mechanism and facilitate diagnosis.

METHODS

The effect of statin treatment on autoantigen expression was addressed by immunoprecipitation using sera from patients. The identity of the ∼100-kd autoantigen was confirmed by immunoprecipitation of in vitro-translated 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) protein. HMGCR expression in muscle was analyzed by immunofluorescence. A cohort of myopathy patients was screened for anti-HMGCR autoantibodies by enzyme-linked immunosorbent assay and genotyped for the rs4149056 C allele, a predictor of self-limited statin myopathy.

RESULTS

Statin exposure induced expression of the ∼200-kd/∼100-kd autoantigens in cultured cells. HMGCR was identified as the ∼100-kd autoantigen. Competition experiments demonstrated no distinct autoantibodies recognizing the ∼200-kd protein. In muscle biopsy tissues from anti-HMGCR-positive patients, HMGCR expression was up-regulated in cells expressing neural cell adhesion molecule, a marker of muscle regeneration. Anti-HMGCR autoantibodies were found in 45 of 750 patients presenting to the Johns Hopkins Myositis Center (6%). Among patients ages 50 years and older, 92.3% had taken statins. The prevalence of the rs4149056 C allele was not increased in patients with anti-HMGCR.

CONCLUSION

Statins up-regulate the expression of HMGCR, the major target of autoantibodies in statin-associated IMNM. Regenerating muscle cells express high levels of HMGCR, which may sustain the immune response even after statins are discontinued. These studies demonstrate a mechanistic link between an environmental trigger and the development of sustained autoimmunity. Detection of anti-HMGCR autoantibodies may facilitate diagnosis and direct therapy.

Macrophagic myofasciitis lesions assess long-term persistence of vaccine-derived aluminium hydroxide in muscle

Macrophagic myofasciitis (MMF) is an emerging condition of unknown cause, detected in patients with diffuse arthromyalgias and fatigue, and characterized by muscle infiltration by granular periodic acid-Schiff's reagent-positive macrophages and lymphocytes. Intracytoplasmic inclusions have been observed in macrophages of some patients. To assess their significance, electron microscopy was performed in 40 consecutive cases and chemical analysis was done by microanalysis and atomic absorption spectrometry. Inclusions were constantly detected and corresponded to aluminium hydroxide, an immunostimulatory compound frequently used as a vaccine adjuvant. A lymphocytic component was constantly observed in MMF lesions. Serological tests were compatible with exposure to aluminium hydroxide-containing vaccines. History analysis revealed that 50 out of 50 patients had received vaccines against hepatitis B virus (86%), hepatitis A virus (19%) or tetanus toxoid (58%), 3-96 months (median 36 months) before biopsy. Diffuse myalgias were more frequent in patients with than without an MMF lesion at deltoid muscle biopsy (P < 0.0001). Myalgia onset was subsequent to the vaccination (median 11 months) in 94% of patients. MMF lesion was experimentally reproduced in rats. We conclude that the MMF lesion is secondary to intramuscular injection of aluminium hydroxide-containing vaccines, shows both long-term persistence of aluminium hydroxide and an ongoing local immune reaction, and is detected in patients with systemic symptoms which appeared subsequently to vaccination.

HTLV-1 and polymyositis in Jamaica

IgG antibodies to human T-cell lymphotropic virus (HTLV-1) were found in 11 of 13 (85%) Jamaican patients with idiopathic adult polymyositis. The association was first observed in 7 patients with polymyositis who were included in a control group of 100 patients with neurological and neuromuscular diseases in a serological investigation of the prevalence of HTLV-1 antibody in patients with tropical spastic paraparesis. All 7 patients with polymyositis were positive for the antibody by an enzyme-linked immunosorbent assay, confirmed by western blot. Because of this striking association a further 6 patients with polymyositis were identified and tested, 4 of whom were also seropositive for HTLV-1 antibody.

Frequency, mutual exclusivity and clinical associations of myositis autoantibodies in a combined European cohort of idiopathic inflammatory myopathy patients

Objectives

To determine prevalence and co-existence of myositis specific autoantibodies (MSAs) and myositis associated autoantibodies (MAAs) and associated clinical characteristics in a large cohort of idiopathic inflammatory myopathy (IIM) patients.

Methods

Adult patients with confirmed IIM recruited to the EuroMyositis registry (n = 1637) from four centres were investigated for the presence of MSAs/MAAs by radiolabelled-immunoprecipitation, with confirmation of anti-MDA5 and anti-NXP2 by ELISA. Clinical associations for each autoantibody were calculated for 1483 patients with a single or no known autoantibody by global linear regression modelling.

Results

MSAs/MAAs were found in 61.5% of patients, with 84.7% of autoantibody positive patients having a sole specificity, and only three cases (0.2%) having more than one MSA. The most frequently detected autoantibody was anti-Jo-1 (18.7%), with a further 21 specificities each found in 0.2–7.9% of patients. Autoantibodies to Mi-2, SAE, TIF1, NXP2, MDA5, PMScl and the non-Jo-1 tRNA-synthetases were strongly associated (p < 0.001) with cutaneous involvement. Anti-TIF1 and anti-Mi-2 positive patients had an increased risk of malignancy (OR 4.67 and 2.50 respectively), and anti-SRP patients had a greater likelihood of cardiac involvement (OR 4.15). Interstitial lung disease was strongly associated with the anti-tRNA synthetases, anti-MDA5, and anti-U1RNP/Sm. Overlap disease was strongly associated with anti-PMScl, anti-Ku, anti-U1RNP/Sm and anti-Ro60. Absence of MSA/MAA was negatively associated with extra-muscular manifestations.

Conclusions

Myositis autoantibodies are present in the majority of patients with IIM and identify distinct clinical subsets. Furthermore, MSAs are nearly always mutually exclusive endorsing their credentials as valuable disease biomarkers.

•

Myositis specific autoantibodies very rarely coexist in the one individual allowing endotypes to be more precisely defined.

•

The association of anti-TIF1 and cancer-associated myositis is confirmed with a cut-off age of over 58 years.

•

In a large combined European myositis cohort associations of anti-SRP with carditis and anti-Mi-2 with cancer have emerged.

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Myositis associated autoantibodies are strongly associated with having myositis in association with another connective tissue disease.

Bacterial pyomyositis in the United States

The incidence of reported bacterial pyomyositis is increasing in the United States, especially among immunocompromised persons. This review summarizes all reported cases of pyomyositis among human immunodeficiency virus (HIV)-infected persons worldwide and HIV-negative persons in the United States since 1981. During the era of combination antiretroviral therapy, bacterial pyomyositis among HIV-infected persons typically occurred in those with end-stage acquired immunodeficiency syndrome. Among non-HIV-infected patients, about half have a serious underlying medical problem, most commonly diabetes mellitus, malignancy, or a rheumatologic condition. These patients are more likely to have a gram-negative infection, a normal white blood cell count, multifocal involvement, or higher mortality than those without an underlying medical condition. The characteristics of cases in temperate areas are similar to tropical cases, except that the former occurs more often in immunocompromised persons; this may change with the HIV epidemic in tropical regions.

Prevalence and factors associated with left ventricular dysfunction in the EULAR Scleroderma Trial and Research group (EUSTAR) database of patients with systemic sclerosis

OBJECTIVES

To measure the prevalence of, and factors associated with, left ventricular (LV) dysfunction in systemic sclerosis (SSc).

METHODS

The EUSTAR database was first searched. A case-control study of a patient subset was then performed to further identify independent factors associated with LV dysfunction by simple and multiple regression.

RESULTS

Of 7073 patients, 383 (5.4%) had an LV ejection fraction (EF) of <55%. By multiple regression analysis, age, sex, diffuse cutaneous disease, disease duration, digital ulcerations, renal and muscle involvement, disease activity score, pulmonary fibrosis and pulmonary arterial hypertension were associated with LV dysfunction. In the second phase, 129 patients with SSc with LVEF <55% were compared with 256 patients with SSc with normal LVEF. Male sex (OR 3.48; 95% CI 1.74 to 6.98), age (OR 1.03; 95% CI 1.01 to 1.06), digital ulcerations (OR 1.91; 95% CI 1.05 to 3.50), myositis (OR 2.88; 95% CI 1.15 to 7.19) and use of calcium channel blockers (OR 0.41; 95% CI 0.22 to 0.74) were independent factors associated with LV dysfunction.

CONCLUSION

The prevalence of LV dysfunction in SSc is 5.4%. Age, male gender, digital ulcerations, myositis and lung involvement are independently associated with an increased prevalence of LV dysfunction. Conversely, the use of calcium channel blockers may be protective.

The EuroMyositis registry: an international collaborative tool to facilitate myositis research

AIMS

The EuroMyositis Registry facilitates collaboration across the idiopathic inflammatory myopathy (IIM) research community. This inaugural report examines pooled Registry data.

METHODS

Cross-sectional analysis of IIM cases from 11 countries was performed. Associations between clinical subtypes, extramuscular involvement, environmental exposures and medications were investigated.

RESULTS

Of 3067 IIM cases, 69% were female. The most common IIM subtype was dermatomyositis (DM) (31%). Smoking was more frequent in connective tissue disease overlap cases (45%, OR 1.44, 95% CI 1.09 to 1.90, p=0.012). Smoking was associated with interstitial lung disease (ILD) (OR 1.32, 95% CI 1.06 to 1.65, p=0.013), dysphagia (OR 1.43, 95% CI 1.16 to 1.77, p=0.001), malignancy ever (OR 1.78, 95% CI 1.36 to 2.33, p<0.001) and cardiac involvement (OR 2.40, 95% CI 1.60 to 3.60, p<0.001).Dysphagia occurred in 39% and cardiac involvement in 9%; either occurrence was associated with higher Health Assessment Questionnaire (HAQ) scores (adjusted OR 1.79, 95% CI 1.43 to 2.23, p<0.001). HAQ scores were also higher in inclusion body myositis cases (adjusted OR 3.85, 95% CI 2.52 to 5.90, p<0.001). Malignancy (ever) occurred in 13%, most commonly in DM (20%, OR 2.06, 95% CI 1.65 to 2.57, p<0.001).ILD occurred in 30%, most frequently in antisynthetase syndrome (71%, OR 10.7, 95% CI 8.6 to 13.4, p<0.001). Rash characteristics differed between adult-onset and juvenile-onset DM cases ('V' sign: 56% DM vs 16% juvenile-DM, OR 0.16, 95% CI 0.07 to 0.36, p<0.001). Glucocorticoids were used in 98% of cases, methotrexate in 71% and azathioprine in 51%.

CONCLUSION

This large multicentre cohort demonstrates the importance of extramuscular involvement in patients with IIM, its association with smoking and its influence on disease severity. Our findings emphasise that IIM is a multisystem inflammatory disease and will help inform prognosis and clinical management of patients.

Idiopathic inflammatory myopathies: epidemiology, classification, and diagnostic criteria

Epidemiologic studies have helped to define the prevalence and incidence of PM, DM, and IBM and have highlighted differences in risk between men and women and in the age at onset for the different forms of myositis. Additionally, these studies have shown that there is a substantially higher risk of PM and DM in certain racial groups which is likely to be genetically determined. These differences are all likely to be fundamental in terms of the pathogenesis of these diseases but, as yet, their full significance remains uncertain. They do, however, suggest that the interplay between genetic and environmental initiating factors is different in the three disorders. Additional population-based studies in homogeneous racial groups, in parallel with studies of susceptibility genes for autoimmune disease, such as those encoding the MHC and inflammatory cytokines, are needed to throw further light on the role of genetic factors in the pathogenesis of the IIMs [47]. Because of the paucity of epidemiologic data on IBM, further studies are required to determine the degree of variation in prevalence in different populations and racial groups, as well as the consistency of the male association and age spectrum of manifestations of the disease. The particularly strong association with DR3 in this form of IIM [48] clearly points to the importance of genetic factors in pathogenesis, but further studies of DR3-associated genes in the MHC and of other candidate genes are needed to define more precisely the genes that convey susceptibility to the disease in different racial groups. Epidemiologic studies also have the potential to identify environmental factors that may play a part in disease initiation in genetically susceptible individuals. Seasonal patterns of disease onset have been reported, particularly in patients with DM [49-51] as well as seasonal variation in the frequency of relapses [52], pointing to the probable involvement of intercurrent infections, ultraviolet light exposure, or other environmental factors in disease initiation and reactivation. Further prospective studies are required to determine the contribution of environmental exposures and how they interact with genetic susceptibility factors to lead to myositis. One of the major limitations of a number of the previous epidemiologic studies is the lack of precision in the diagnostic criteria used and the classification of cases of IIM. The Bohan and Peter criteria [1] which were used in most studies after 1975, were introduced before IBM was recognized as an entity distinct from PM; most of the published incidence and prevalence figures for PM are therefore likely to be inaccurate. Multicentered, interdisciplinary, prospective studies, incorporating comprehensive clinical, laboratory, and pathologic information, are needed to develop and validate better diagnostic and classification criteria and to determine the true prevalence and incidence of the many forms of IIM.

Infective Pyomyositis and Myositis in Children in the Era of Community‐Acquired, Methicillin‐ResistantStaphylococcus aureusInfection

BACKGROUND

Cases of pyomyositis and myositis have been increasing in frequency at Texas Children's Hospital (Houston) since 2000. The increase appears to correlate with the emergence of community-acquired methicillin-resistant Staphylococcus aureus (MRSA).

METHODS

The medical records of patients with pyomyositis and myositis hospitalized at Texas Children's Hospital during the period from January 2000 through December 2005 were reviewed. Available S. aureus isolates were obtained for susceptibility testing, to determine the presence of pvl (lukS-PV and lukF-PV), and for pulsed-field gel electrophoresis analysis.

RESULTS

Forty-five previously healthy children with bacterial pyomyositis or myositis were analyzed. The causes were S. aureus (in 57.8% of children) and Streptococcus pyogenes (in 2.2%); 40.0% of children had negative culture results. The number of cases increased between 2000 and 2005, primarily as a result of an increase in the prevalence of community-acquired MRSA. The mean patient age was 5.5 years (range, 0.06-15 years). The thigh (40.0% of children) and pelvis (28.9%) were the most commonly affected sites. The mean abscess diameter was 3.5 cm. Eighteen children required at least 1 muscle drainage procedure. Of the 24 available S. aureus isolates (15 community-acquired MRSA isolates and 9 community-acquired, methicillin-susceptible S. aureus [MSSA] isolates), 16 were found to be USA300 by pulsed-field gel electrophoresis, and 17 carried pvl. Patients with community-acquired MRSA, USA300, and/or pvl-positive strains required more drainage procedures than did those with community-acquired MSSA, non-USA300, and/or pvl-negative strains (81% vs. 40% [P=.05], 82% vs. 29% [P=.02], and 81% vs. 38% [P=.07], respectively).

CONCLUSIONS

Community-acquired MRSA is an increasing cause of pyomyositis and myositis in children. Community-acquired MRSA, USA300, pvl-positive S. aureus isolates caused more severe disease than did community-acquired MSSA, non-USA300, and pvl-negative isolates, respectively.

Prognostic factors in polymyositis/dermatomyositis. A computer-assisted analysis of ninety-two cases

An effort was made to identify all patients with polymyositis/dermatomyositis (PM/DM) admitted to hospitals in Israel from 1956-1976. The diagnosis of PM/DM was retrospectively reviewed in 92 (46 definite, 26 probable, and 20 possible) cases. The most common complaints and physical findings in the course of the disease were muscle weakness (86 patients), rash (53 patients), arthritis or arthralgia (39 patients), and dysphagia (35 patients). Elevated serum aldolase levels were found in 64% of the patients for whom data were available; 92% had abnormal electromyogram results, and 60.9% had muscle histopathology consistent with PM/DM. Malignancy was diagnosed in 13 patients. Malignancy, ischemic heart disease, and pulmonary complications were the most common causes of death. The actuarial survival curve was heterogeneous, with an accelerated mortality during the first year after diagnosis and a slower mortality during the following 7 years. Independent unfavorable prognostic signs were: failure to induce remission, leukocytosis, fever, older age, a shorter disease history, and dysphagia.

Clinical and human leucocyte antigen class II haplotype associations of autoantibodies to small ubiquitin-like modifier enzyme, a dermatomyositis-specific autoantigen target, in UK Caucasian adult-onset myositis

OBJECTIVES

Autoantibodies to a novel autoantigen small ubiquitin-like modifier activating enzyme (SAE) associated with dermatomyositis (DM) have previously been identified. The aim of this study was to establish the frequency of anti-SAE autoantibodies in a UK myositis cohort and investigate clinicoimmunogenetic associations.

METHODS

Clinical data and sera were studied from 266 patients recruited to the Adult Onset Myositis Immunogenetic Collaboration. Myositis sera, control sera including 250 patients with other connective tissue diseases and 50 healthy participants were screened using radio-immunoprecipitation. Immunodepletion was performed on all sera immunoprecipitating 40 and 90 kDa bands to confirm the presence of anti-SAE. DNA from 202 patients with myositis was genotyped for human leucocyte antigen (HLA)-DRB1 and DQB1; DQA1 data were inferred.

RESULTS

Out of 266 patients with myositis, 11 (4%) were positive for anti-SAE, which was found exclusively in DM with a frequency of 8%. Patients with anti-SAE had a high frequency of cutaneous lesions including heliotrope (82%) and Gottron rash (82%). Of the 11, 9 (82%) had systemic features and 7 of 9 (78%) developed dysphagia. Of those nine, seven (78%) presented with skin disease before myositis onset. All patients with anti-SAE possessed at least one copy of HLA-DQB1*03. HLA-DRB1*04-DQA1*03-DQB1*03 was a significant risk factor in anti-SAE positive versus patients who were anti-SAE negative (haplotype frequency 18% vs 6%, p<0.001, OR 5.7, 95% CI 1.9 to 17.3).

CONCLUSIONS

Anti-SAE is a myositis-specific autoantibody that identifies a subset of patients with adult DM. The majority of patients with anti-SAE presented with cutaneous disease and progressed to myositis with systemic features including dysphagia. This novel autoantibody has a strong association with the HLA-DRB1*04-DQA1*03-DQB1*03 haplotype.

COVID-19 and the nervous system

A pandemic due to novel coronavirus arose in mid-December 2019 in Wuhan, China, and in 3 months' time swept the world. The disease has been referred to as COVID-19, and the causative agent has been labelled SARS-CoV-2 due to its genetic similarities to the virus (SARS-CoV-1) responsible for the severe acute respiratory syndrome (SARS) epidemic nearly 20 years earlier. The spike proteins of both viruses dictate tissue tropism using the angiotensin-converting enzyme type 2 (ACE-2) receptor to bind to cells. The ACE-2 receptor can be found in nervous system tissue and endothelial cells among the tissues of many other organs.Neurological complications have been observed with COVID-19. Myalgia and headache are relatively common, but serious neurological disease appears to be rare. No part of the neuraxis is spared. The neurological disorders occurring with COVID-19 may have many pathophysiological underpinnings. Some appear to be the consequence of direct viral invasion of the nervous system tissue, others arise as a postviral autoimmune process, and still others are the result of metabolic and systemic complications due to the associated critical illness. This review addresses the preliminary observations regarding the neurological disorders reported with COVID-19 to date and describes some of the disorders that are anticipated from prior experience with similar coronaviruses.

Pyomyositis. Increasing recognition in temperate climates

Pyomyositis is common in the tropics yet is rarely reported in temperate climates. A woman in whom pyomyositis developed in a temperate climate is presented. Computed tomography was the key in the diagnosis of the disease involving the muscles of the left lateral chest wall. The patient's condition responded to intravenous antibiotics and open abscess drainage. The 31 cases reported in the United States are reviewed. Unfamiliarity still poses a barrier to early diagnosis, although pyomyositis is being more frequently described in temperate climates.

The clinical phenotypes of the juvenile idiopathic inflammatory myopathies

The juvenile idiopathic inflammatory myopathies (JIIM) are systemic autoimmune diseases characterized by skeletal muscle weakness, characteristic rashes, and other systemic features. Although juvenile dermatomyositis (JDM), the most common form of JIIM, has been well studied, the other major clinical subgroups of JIIM, including juvenile polymyositis (JPM) and juvenile myositis overlapping with another autoimmune or connective tissue disease (JCTM), have not been well characterized, and their similarity to the adult clinical subgroups is unknown. We enrolled 436 patients with JIIM, including 354 classified as JDM, 33 as JPM, and 49 as JCTM, in a nationwide registry study. The aim of the study was to compare demographics; clinical features; laboratory measures, including myositis autoantibodies; and outcomes among these clinical subgroups, as well as with published data on adult patients with idiopathic inflammatory myopathies (IIM) enrolled in a separate natural history study. We used random forest classification and logistic regression modeling to compare clinical subgroups, following univariate analysis. JDM was characterized by typical rashes, including Gottron papules, heliotrope rash, malar rash, periungual capillary changes, and other photosensitive and vasculopathic skin rashes. JPM was characterized by more severe weakness, higher creatine kinase levels, falling episodes, and more frequent cardiac disease. JCTM had more frequent interstitial lung disease, Raynaud phenomenon, arthralgia, and malar rash. Differences in autoantibody frequency were also evident, with anti-p155/140, anti-MJ, and anti-Mi-2 seen more frequently in patients with JDM, anti-signal recognition particle and anti-Jo-1 in JPM, and anti-U1-RNP, PM-Scl, and other myositis-associated autoantibodies more commonly present in JCTM. Mortality was highest in patients with JCTM, whereas hospitalizations and wheelchair use were highest in JPM patients. Several demographic and clinical features were shared between juvenile and adult IIM subgroups. However, JDM and JPM patients had a lower frequency of interstitial lung disease, Raynaud phenomenon, "mechanic's hands" and carpal tunnel syndrome, and lower mortality than their adult counterparts. We conclude that juvenile myositis is a heterogeneous group of illnesses with distinct clinical subgroups, defined by varying clinical and demographic characteristics, laboratory features, and outcomes.

Interstitial lung disease in anti-Jo-1 patients with antisynthetase syndrome

OBJECTIVE

To assess the outcome of interstitial lung disease (ILD) in anti-Jo-1 patients with antisynthetase syndrome, determine predictive variables of ILD deterioration in these patients, and compare features of anti-Jo-1 patients with and without ILD.

METHODS

Ninety-one anti-Jo-1 patients were identified by medical records search in 4 medical centers. All of these patients had undergone pulmonary function tests (PFTs) and high-resolution computed tomography (HRCT) scans.

RESULTS

Sixty-six patients (72.5%) had ILD. Patients could be divided into 3 groups according to their presenting lung manifestations: acute onset of lung disease (n = 12), progressive onset of lung signs (n = 35), and asymptomatic patients exhibiting abnormalities consistent with ILD on PFTs and HRCT scans (n = 19). Sixteen patients had resolution of ILD; 39 and 11 patients experienced improvement and deterioration of ILD, respectively. ILD led to decreased functional status, since 29.8% of patients exhibited a marked reduction of activities due to ILD and 13.6% had respiratory insufficiency requiring oxygen therapy; 5 of 6 patients died due to ILD complications. Predictive parameters of ILD deterioration were HRCT scan pattern of usual interstitial pneumonia, respiratory muscle involvement, and age ≥55 years. Furthermore, anti-Jo-1 patients with ILD, compared with those without, more frequently exhibited mechanic's hands and lower creatine kinase levels.

CONCLUSION

Our findings confirm that ILD is a frequent complication in anti-Jo-1 patients, resulting in high morbidity. We suggest that patients with predictive factors of ILD deterioration may require more aggressive therapy. Finally, anti-Jo-1 patients with ILD, compared with those without, may exhibit a particular clinical phenotype.

Interaction of HLA-DRB1*03 and smoking for the development of anti-Jo-1 antibodies in adult idiopathic inflammatory myopathies: a European-wide case study

OBJECTIVES

HLA-DRB1*03 is strongly associated with anti-Jo-1-positive idiopathic inflammatory myopathies (IIM) and there is now increasing evidence that Jo-1 antigen is preferentially expressed in lung tissue. This study examined whether smoking was associated with the development of anti-Jo-1 antibodies in HLA-DRB1*03-positive IIM.

METHODS

IIM cases were selected with concurrent information regarding HLA-DRB1 status, smoking history and anti-Jo-1 antibody status. DNA was genotyped at DRB1 using a commercial sequence-specific oligonucleotide kit. Anti-Jo-1 antibody status was established using a line blot assay or immunoprecipitation.

RESULTS

557 Caucasian IIM patients were recruited from Hungary (181), UK (99), Sweden (94) and Czech Republic (183). Smoking frequency was increased in anti-Jo-1-positive IIM cases, and reached statistical significance in Hungarian IIM (45% Jo-1-positive vs 17% Jo-1-negative, OR 3.94, 95% CI 1.53 to 9.89, p<0.0001). A strong association between HLA-DRB1*03 and anti-Jo-1 status was observed across all four cohorts (DRB1*03 frequency: 74% Jo-1-positive vs 35% Jo-1-negative, OR 5.55, 95% CI 3.42 to 9.14, p<0.0001). The frequency of HLA-DRB1*03 was increased in smokers. The frequency of anti-Jo-1 was increased in DRB1*03-positive smokers vs DRB1*03-negative non-smokers (42% vs 8%, OR 7.75, 95% CI 4.21 to 14.28, p<0.0001) and DRB1*03-positive non-smokers (42% vs 31%, p=0.08). In DRB1*03-negative patients, anti-Jo-1 status between smokers and non-smokers was not significantly different. No significant interaction was noted between smoking and DRB1*03 status using anti-Jo-1 as the outcome measure.

CONCLUSION

Smoking appears to be associated with an increased risk of possession of anti-Jo-1 in HLA-DRB1*03-positive IIM cases. The authors hypothesise that an interaction between HLA-DRB1*03 and smoking may prime the development of anti-Jo-1 antibodies.

Anti-PL-7 (anti-threonyl-tRNA synthetase) antisynthetase syndrome: clinical manifestations in a series of patients from a European multicenter study (EUMYONET) and review of the literature

Autoantibodies against several aminoacyl-transfer-RNA synthetases have been described in patients with myositis; anti-threonyl-tRNA synthetase (anti-PL-7) is one of the rarest. We describe the clinical and laboratory characteristics of a cohort of European anti-PL-7 patients, and compare them with previously reported cases. This multicenter study of patients positive for anti-PL-7, identified between 1984 and 2011, derives from the EUMYONET cohort. Clinical and serologic data were obtained by retrospective laboratory and medical record review, and statistical analyses were performed with chi-squared and Fisher exact tests. Eighteen patients, 15 women, were anti-PL-7 antibody positive. Median follow-up was 5.25 years (interquartile range, 2.8-10.7 yr), and 4 patients died. All patients had myositis (12 polymyositis, 5 dermatomyositis, and 1 amyopathic dermatomyositis), 10 (55.6%) had interstitial lung disease, and 9 (50%) had pericardial effusion. Occupational exposure to organic/inorganic particles was more frequent in patients with interstitial lung disease than in the remaining patients (5 of 10 vs. 1 of 7; p = 0.152), although the difference was not significant. Concurrent autoantibodies against Ro60 and Ro52 were seen in 8 of 14 (57%) patients studied. In the literature review the most common manifestations of anti-PL-7 antisynthetase syndrome were interstitial lung disease (77%), myositis (75%), and arthritis (56%). As in other subsets of the antisynthetase syndrome, myositis and interstitial lung disease are common features of the anti-PL-7 antisynthetase syndrome. In addition, we can add pericarditis as a possible manifestation related to anti-PL-7 antibodies.

Bacterial complications of primary varicella in children

Bacterial complications of varicella in 84 patients younger than 16 years of age (48 females; median age, 2.9 years) who required hospitalization between 1985 and 1995 were retrospectively analyzed. The purpose of the study was to describe demographics, clinical manifestations, bacteriology, and factors affecting outcome. Seventy-six percent of patients were younger than 5 years of age. The eldest children in households were significantly underrepresented (P = .00025). Skin infections occurred in 61 patients (73%), and deep-seated infections and/or shock occurred in 23 (27%). The latter complications were significantly associated with thrombocytopenia (P = .011) and bacteremia (P = .014) at the time of admission, prolonged fever (P = .001), prolonged hospitalization (P < .0001), intensive care management (P < .0001), and fatal outcome (P = .019). Group A beta-hemolytic streptococcus (59% of isolates) and Staphylococcus aureus (28%) were the predominant isolates. Before and after 1990, five (31%) of 16 and 13 (62%) of 21 streptococcal complications, respectively, were invasive infections (P = .09). These data underscore the need for universal immunization against chickenpox.

Prevalence of sporadic inclusion body myositis in Western Australia

A 10-year retrospective review was conducted to ascertain the prevalence of inclusion body myositis (IBM) in Western Australia. Seventeen patients with sporadic IBM aged 45-90 years were identified and the prevalence of IBM was calculated to be 9.3 x 10(-6). The prevalence was higher in men (10.9 x 10(-6)) than in women (7.7 x 10(-6)). The mean age of onset of IBM was 56.6 years, and the mean delay between onset of symptoms and diagnosis was 4.4 years. The age-adjusted prevalence over the age of 50 years was 35.3 x 10(-6). The results suggest a higher prevalence of IBM than has previously been reported.

Epidemiology of neuromuscular diseases, including the postpolio sequelae, in a Swedish county

The epidemiology of neuromuscular diseases was studied in the county of Orebro, Sweden (study population 270,000). Several different sources of data were utilized, compared and validated. On the prevalence of day (January 1, 1988) 474 patients were identified. The rate per 100,000 population was 92 for the postpolio sequelae (PPS) and 84 for the other neuromuscular diseases (motor neuron disease 9, hereditary neuropathies 9, myoneural disorders 16, myotonic disorders 19, muscular dystrophies 20 and myositis 11). Of the patients with the PPS, 80% reported late-onset symptoms. On the basis of an expanded survey including all medical records in one health care district, the prevalence of the PPS was estimated to be 186/100,000 population.

Differences in idiopathic inflammatory myopathy phenotypes and genotypes between Mesoamerican Mestizos and North American Caucasians: ethnogeographic influences in the genetics and clinical expression of myositis

OBJECTIVE

As part of a larger, worldwide study of the ethnogeography of myositis, we evaluated the clinical, serologic, and immunogenetic features of Mestizo (Mexican and Guatemalan) and North American Caucasian patients with idiopathic inflammatory myopathy (IIM).

METHODS

Clinical manifestations, autoantibodies, HLA-DRB1 and DQA1 alleles, and immunoglobulin Gm/Km allotypes were compared between 138 Mestizos with IIM and 287 Caucasians with IIM, using the same classification criteria and standardized questionnaires.

RESULTS

IIM in Mestizo patients was characterized by a higher proportion of dermatomyositis (69% of adult Mestizos versus 35% of adult Caucasians; P < 0.001) and anti-Mi-2 autoantibodies (30% versus 7% of adults, respectively, and 32% versus 4% of children, respectively; P < 0.01). Genetic risk factors also differed in these populations. Whereas Mestizos had no HLA risk factors for IIM, HLA-DRB1*0301, the linked allele DQA1*0501, and DRB1 alleles sharing the first hypervariable region motif (9)EYSTS(13) were major risk factors in Caucasian patients with IIM. Furthermore, different HLA-DRB1 and DQA1 alleles were associated with anti-Mi-2 autoantibodies (DRB1*04 and DQA1*03 in Mestizos and DRB1*07 and DQA1*02 in Caucasians). Immunoglobulin gamma-chain allotypes Gm(1), Gm(17) (odds ratio for both 11.3, P = 0.008), and Gm(21) (odds ratio 7.3, P = 0.005) and kappa-chain allotype Km(3) (odds ratio 7.3, P = 0.005) were risk factors for IIM in Mestizos; however, no Gm or Km allotypes were risk or protective factors in Caucasians. In addition, Gm and Km phenotypes were unique risk factors (Gm 1,3,17 5,13,21 and Gm 1,17 23 21 and Km 3,3) or protective factors (Km 1,1) for the development of myositis and anti-Mi-2 autoantibodies (Gm 1,2,3,17 23 5,13,21) in adult Mestizos.

CONCLUSION

IIM in Mesoamerican Mestizos differs from IIM in North American Caucasians in the frequency of phenotypic features and in the immune-response genes predisposing to and protecting from myositis and anti-Mi-2 autoantibodies at 4 chromosomal loci. These and other data suggest the likelihood that the expression of IIM is modulated by different genes and environmental exposures around the world.