Lisa Christopher-Stine

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

OBJECTIVEnIn 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.nnnMETHODSnThe 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.nnnRESULTSnStatin 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.nnnCONCLUSIONnStatins 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.

A novel autoantibody recognizing 200-kd and 100-kd proteins is associated with an immune-mediated necrotizing myopathy

OBJECTIVEnMyofiber necrosis without prominent inflammation is a nonspecific finding in patients with dystrophies and toxic or immune-mediated myopathies. However, the etiology of a necrotizing myopathy is often obscure, and the question of which patients would benefit from immunosuppression remains unanswered. The aim of this study was to identify novel autoantibodies in patients with necrotizing myopathy.nnnMETHODSnMuscle biopsy specimens and serum samples were available for 225 patients with myopathy. Antibody specificities were determined by performing immunoprecipitations from (35)S-methionine-labeled HeLa cell lysates. Selected biopsy specimens were stained for membrane attack complex, class I major histocompatibility complex (MHC), and endothelial cell marker CD31.nnnRESULTSnMuscle biopsy specimens from 38 of 225 patients showed predominantly myofiber necrosis. Twelve of these patients had a known autoantibody association with or other etiology for their myopathy. Sixteen of the remaining 26 sera immunoprecipitated 200-kd and 100-kd proteins; this specificity was observed in only 1 of 187 patients without necrotizing myopathy. Patients with the anti-200/100 autoantibody specificity had proximal weakness (100%), high creatine kinase levels (mean maximum 10,333 IU/liter), and an irritable myopathy on electromyography (88%). Sixty-three percent of these patients had been exposed to statins prior to the onset of weakness. All patients responded to immunosuppressive therapy, and many experienced a relapse of weakness when the medication was tapered. Immunohistochemical studies showed membrane attack complex on small blood vessels in 6 of 8 patients and on the surface of non-necrotic myofibers in 4 of 8 patients. Five of 8 patients had abnormal capillary morphology, and 4 of 8 patients expressed class I MHC on the surface of non-necrotic myofibers.nnnCONCLUSIONnAn anti-200/100-kd specificity defines a subgroup of patients with necrotizing myopathy who previously were considered to be autoantibody negative. We propose that these patients have an immune-mediated myopathy that is frequently associated with prior statin use and should be treated with immunosuppressive therapy.

Lupus Atherosclerosis Prevention Study (LAPS)

Background Cardiovascular disease is one of the major causes of death in systemic lupus erythematosus (SLE). A study was undertaken to investigate whether treatment with statins would reduce subclinical measures of atherosclerosis over a 2-year period. Methods 200 patients with SLE without clinical cardiovascular disease were randomised to receive atorvastatin 40 mg daily or an identical placebo. At baseline and after 2 years of follow-up, helical CT scanning (for coronary artery calcium) and carotid duplex (for intima media thickness/plaque) were performed. Patients were seen for measures of disease activity at 1 month, 3 months and quarterly thereafter. The primary outcome variable was change in coronary artery calcium. Results At baseline, 43% had coronary artery calcium. At 2 years there was no significant difference between the groups in progression of coronary artery calcium, carotid intima media thickness or carotid plaque. There was no significant difference between the groups in disease activity, measures of inflammation or endothelial cell activation. Conclusion This study provides no evidence that atorvastatin reduces subclinical measures of atherosclerosis or disease activity over 2 years in patients with SLE. In fact, it does not appear to reduce biochemical measures of inflammation. The anti-inflammatory effects of statins observed in the general population were not replicated in this SLE clinical trial. Clinicaltrials.gov (NCT 00120887).

Interstitial Lung Disease Associated With the Idiopathic Inflammatory Myopathies: What Progress Has Been Made in the Past 35 Years?

Interstitial lung disease is commonly associated with the autoimmune inflammatory myopathies dermatomyositis and polymyositis and accounts for significant morbidity and mortality in these conditions. In the 35 years since the association between inflammatory myopathy and interstitial lung disease was initially described, there has been progress in diagnosing and treating this dis-order. Nevertheless, there remains much about pathogenesis and therapeutics to be learned. This review examines the changes in the understanding of this complex condition, highlighting recent advances and areas deserving of further study.

Most patients with cancer-associated dermatomyositis have antibodies to nuclear matrix protein NXP-2 or transcription intermediary factor 1γ.

OBJECTIVEnSince dermatomyositis (DM) is associated with an increased risk of malignancy, accurate identification of patients likely to harbor cancers is important. Using immunoprecipitations from radiolabeled cell lysates, several groups recently showed that anti-transcription intermediary factor 1γ (anti-TIF-1γ) antibodies are associated with malignancy in DM. We undertook this study to develop sensitive, specific assays to detect antibodies against TIF-1γ and nuclear matrix protein NXP-2 and to evaluate their association with malignancy in DM.nnnMETHODSnTo detect anti-TIF-1γ antibodies, immunoprecipitations were performed using lysates made from HeLa cells overexpressing TIF-1γ, with detection by immunoblotting. Anti-NXP-2 antibodies were assayed by immunoprecipitation using (35) S-methionine-labeled NXP-2 generated by in vitro transcription/translation. We analyzed patient sera from DM cohorts seen at the Stanford University Dermatology Clinic (n = 111) and the Johns Hopkins Myositis Center (n = 102).nnnRESULTSnA total of 17% and 38% of patients had antibodies against NXP-2 and TIF-1γ, respectively. Reactivity against either NXP-2 or TIF-1γ identified 83% of patients with cancer-associated DM. In addition to older age and male sex, cancer was associated with antibodies to NXP-2 or TIF-1γ on multivariate analysis (odds ratio 3.78 [95% confidence interval 1.33-10.8]). Stratification by sex revealed that anti-NXP-2 was specifically associated with cancer in males (odds ratio 5.78 [95% confidence interval 1.35-24.7]).nnnCONCLUSIONnThese studies demonstrate that anti-NXP-2 and anti-TIF-1γ antibodies are frequent DM specificities (found in 55% of patients) and are present in most patients with cancer-associated DM.

Rituximab therapy for myopathy associated with anti–signal recognition particle antibodies: A case series

The myopathy associated with anti–signal recognition particle (anti‐SRP) is a severe necrotizing immune‐mediated disease characterized by rapidly progressive proximal muscle weakness, markedly elevated serum creatine kinase (CK) levels, and poor responsiveness to traditional immunosuppressive therapies. Reports on the efficacy of B cell depletion therapy for anti‐SRP–associated myopathy are mixed. We describe 8 patients with anti‐SRP–associated myopathy and their response to treatment with the anti‐CD20 monoclonal antibody rituximab.

Antibody levels correlate with creatine kinase levels and strength in anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase-associated autoimmune myopathy

OBJECTIVEnAutoantibodies recognizing 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) are found in patients with statin-associated immune-mediated necrotizing myopathy and, less commonly, in statin-unexposed patients with autoimmune myopathy. The main objective of this study was to define the association of anti-HMGCR antibody levels with disease activity.nnnMETHODSnAnti-HMGCR levels, creatine kinase (CK) levels, and strength were assessed in anti-HMGCR-positive patients. Associations of antibody level with CK level and strength at visit 1 were analyzed in 55 patients, 40 of whom were exposed to statins. In 12 statin-exposed and 5 statin-unexposed patients with serum from 5 serial visits, the evolution of antibody levels, CK levels, and strength was investigated.nnnRESULTSnAntibody levels were associated with CK levels (P < 0.001), arm strength (P < 0.05), and leg strength (P < 0.05) at visit 1, but these associations were only significant among statin-exposed patients in stratified analyses. With immunosuppressive treatment over 26.2 ± 12.6 months (mean ± SD), antibody levels declined (P < 0.05) and arm abduction strength improved (P < 0.05) in the 17 patients followed up longitudinally. The separate analysis showed that statin-exposed patients developed decreased antibody levels (P < 0.01), decreased CK levels (P < 0.001), improved arm strength (P < 0.05), and improved hip flexion strength (P < 0.05) with treatment. Anti-HMGCR antibody levels did not normalize in any patient.nnnCONCLUSIONnIn the entire cohort, initial anti-HMGCR levels correlated with indicators of disease activity; with immunosuppressive treatment, antibody levels declined and arm strength improved. Statin-exposed patients had significant improvements in CK levels and strength whereas statin-unexposed patients did not, suggesting a phenotypic difference between statin-exposed and statin-unexposed anti-HMGCR-positive patients.

Increased frequency of DRB1*11:01 in anti-hydroxymethylglutaryl-coenzyme A reductase-associated autoimmune myopathy.

To investigate the association of anti–hydroxymethylglutaryl‐coenzyme A reductase (anti‐HMGCR) myopathy with HLA class I and II antigens.

Ascertainment of collagen vascular disease in patients presenting with interstitial lung disease

INTRODUCTIONnPrevious studies of interstitial lung disease (ILD) suggest that prognosis and therapeutic response are influenced by the presence of underlying collagen vascular disease (CVD). Yet, what proportion of patients presenting with ILD have CVD is largely unknown. We sought to determine the frequency of a new CVD diagnosis in an ILD referral population.nnnMATERIALS/PATIENTS AND METHODSnWe retrospectively studied 114 consecutive patients evaluated at the Johns Hopkins Interstitial Lung Disease Clinic for the development of CVD.nnnRESULTSnIn this retrospective cohort, nearly one-third of the 114 patients with confirmed ILD satisfied published criteria for a CVD diagnosis. Seventeen (15%) patients were diagnosed with a new CVD as a direct consequence of their ILD evaluation. Patients with new CVD diagnosis were younger than those without new CVD diagnosis: 51.4years (95% CI 45-58years) and 60years (95% CI 57-63), respectively (p=0.01). Moreover, an ANA>or=1:640 (p=0.03) and elevated levels of creatine phosphokinase (CPK) or aldolase (p<0.001) were associated with a new CVD diagnosis.nnnCONCLUSIONSnUnrecognized collagen vascular disease may be more common than previously appreciated among patients referred with ILD. High titer ANA and an elevated CPK or aldolase are associated with a CVD diagnosis in this referral population.

Expression of the dermatomyositis autoantigen Mi-2 in regenerating muscle.

OBJECTIVEnAutoantibodies against the chromatin remodeler Mi-2 are found in a distinct subset of patients with dermatomyositis (DM). Previous quantitative immunoblotting experiments demonstrated that Mi-2 protein levels are up-regulated in DM muscle. This study was undertaken to define the population of cells expressing high levels of Mi-2 in DM muscle and to explore the regulation and functional role of Mi-2 during muscle regeneration.nnnMETHODSnThe expression of Mi-2 was analyzed by immunofluorescence microscopy in human muscle biopsy specimens. In an experimental mouse model, cardiotoxin was used to induce muscle injury and repair, and expression of Mi-2 during muscle regeneration was studied in this model by immunofluorescence and immunoblotting analyses. In addition, a cell culture system of muscle differentiation was utilized to artificially modulate Mi-2 levels during proliferation and differentiation of myoblasts.nnnRESULTSnIn human DM muscle tissue, increased Mi-2 expression was found preferentially in the myofibers within fascicles affected by perifascicular atrophy, particularly in the centralized nuclei of small perifascicular muscle fibers expressing markers of regeneration. In injured mouse muscle tissue, Mi-2 levels were dramatically and persistently up-regulated during muscle regeneration in vivo. Premature silencing of Mi-2 with RNA interference in vitro resulted in accelerated myoblast differentiation.nnnCONCLUSIONnExpression of Mi-2 is markedly up-regulated during muscle regeneration in a mouse model of muscle injury and repair. It is also up-regulated in human DM myofibers expressing markers of regeneration. Results of the in vitro studies indicate that this protein may play a role in modulating the kinetics of myoblast differentiation. Our findings thus suggest that high levels of Mi-2 expression in muscle biopsy tissue from patients with DM reflect the presence of incompletely differentiated muscle cells.