The role of jo-1 in the immunopathogenesis of polymyositis: Current hypotheses

Antisynthetase syndrome - much more than just a myopathy

The aim of the study was to summarize current knowledge on antisynthetase syndrome (ASS), including its epidemiology, pathogenesis, proposed so far diagnostic criteria, heterogeneity of clinical manifestations, prognostic factors and therapeutic possibilities. PubMed database was screened for "antisynthetase syndrome" OR "antisynthetase antibodies" between February and April 2020. Aminoacyl-tRNA synthetases participate in the immune system activation as antigens, but also serve chemoattractive and cytokine-resembling roles, initiating innate and adaptive pathways. Exposure to various inhaled antigens may induce the autoimmune cascade leading to ASS. NK cells with its impaired INF-y production as well as formation of NETs by neutrophils contribute to pathogenesis. The prevalence of symptoms vary significantly depending on the study with muscular, articular and pulmonary involvement being the most frequently observed. Although classified as subtype of idiopathic inflammatory myopathies, myositis may not necessarily be the prominent manifestation. Since clinical presentation is heterogeneous and symptoms can emerge gradually, ASS could be considered as a heterogeneous spectrum rather than a homogenous disease entity. The currently available classification criteria do not fully correspond with the clinical patterns of the disease. Therapy is based on glucocorticosteroids and other immunosuppressive agents. Randomized controlled trials, dedicated for patients with ASS, are needed to form treatment algorithms.

Antisynthetase syndrome pathogenesis: knowledge and uncertainties

PURPOSE OF REVIEW

Antisynthetase syndrome (ASyS) is an acquired myopathy characterized by the presence of myositis-specific autoantibodies directed against tRNA-synthetases. ASyS is potentially life threatening due to lung involvement and treatment remains a challenge to date. With symptoms not limited to muscles but also involving lung, skin and joints, ASyS appears specific and has a particular pathogenesis, different from the other inflammatory myopathies. This review is intended to discuss the current understanding of ASyS pathogenesis, pointing its current knowledge and also the crucial prospects that may lead to critical improvement of ASyS care.

RECENT FINDINGS

Regarding ASyS pathogenesis, initiation of the disease seems to arise in a multifactorial context, with first lesions occurring within the lungs. This may lead to aberrant self-antigen exposure and tolerance breakdown. The consequences are abnormal activation of both innate and adaptive immunity, resulting in the patients with favourable genetic background to autoimmune-mediated organ lesions. Immune and nonimmune roles of the antigen, as well as antigen presentation leading to specific T-cell and B-cell activation and to the production of specific autoantibodies belong to the disease process.

SUMMARY

This work aims to detail ASyS pathogenesis understanding, from initiation to the disease propagation and target tissue lesions, in order to considering future treatment directions.

Subcutaneous immunoglobulins for the treatment of a patient with antisynthetase syndrome and secondary chronic immunodeficiency after anti-CD20 treatment: a case report

Background

Antisynthetase syndrome is a rare and debilitating multiorgan disease characterized by inflammatory myopathy, interstitial lung disease, cutaneous involvement, and frequent chronic inflammation of the joints. Standard treatments include corticosteroids and immunosuppressants. In some cases, treatment resistance may develop. Administration of immunoglobulins intravenously is recommended in patients with drug-resistant antisynthetase syndrome.

Case presentation

Here, we describe the case of a 56-year-old woman of Algerian origin. She is the first case of a patient with multidrug-resistant antisynthetase syndrome featuring pulmonary involvement and arthropathy, and chronic secondary immune deficiency with recurrent infections, after anti-CD20 treatment, in which her primary antisynthetase syndrome-related symptoms and secondary immune deficiency were treated successfully with subcutaneous administration of immunoglobulin. The administration of immunoglobulin subcutaneously was introduced at a dose of 2 g/kg per month and was well tolerated. Clinical improvement was observed within 3 months of initiation of subcutaneous administration of immunoglobulin. After 22 months of treatment, she showed a significant improvement in terms of muscle strength, pulmonary involvement, arthralgia, and immunodeficiency. Her serum creatine phosphokinase and C-reactive protein levels remained normal. Finally, she was compliant and entirely satisfied with the treatment.

Conclusions

Taken together, these observations suggest that administration of immunoglobulin subcutaneously may be a useful therapeutic approach to tackle steroid-refractory antisynthetase syndrome while ensuring minimal side effects and improved treatment compliance. This treatment also allowed, in our case, for the regression of the chronic immunodeficiency secondary to rituximab treatment.

Three cases of anti-TNF induced myositis and literature review

Anti-tumor necrosis factor drugs are frequently preferred in the treatment of rheumatologic diseases and other inflammatory diseases. The development of myositis after using anti-tumor necrosis factor drugs is a rare clinical condition. Here we aimed to report cases who developed myositis after using anti-tumor necrosis factor drugs and review the current literature. We report two cases of rheumatoid arthritis and a case of ankylosing spondylitis developed idiopathic inflammatory myopathy following anti-tumor necrosis factor therapy. In conclusion, myositis could develop during anti-tumor necrosis factor therapy, so these patients should be evaluated carefully initially for myositis and should be closely monitored due to the potential for developing myositis in treatment process.

Role of Jo-1 in the Immunopathogenesis of the Anti-synthetase Syndrome

Histidyl-tRNA synthetase (HRS = Jo-1) represents a key autoantibody target in the anti-synthetase syndrome that is marked by myositis as well as extra-muscular organ complications including interstitial lung disease (ILD). Over the last 25 years, a wealth of clinical, epidemiological, genetic, and experimental data have collectively supported a role for Jo-1 in mediating deleterious cell-mediated, adaptive immune responses contributing to the disease phenotype of the anti-synthetase syndrome. Complementing these studies, more recent work suggests that unique, non-enzymatic functional properties of Jo-1 also endow this antigen with the capacity to activate components of the innate immune system, particularly cell surface as well as endosomal Toll-like receptors and their downstream signaling pathways. Combining these facets of Jo-1-mediated immunity now supports a more integrated model of disease pathogenesis that should lead to improved therapeutic targeting in the anti-synthetase syndrome and related subsets of idiopathic inflammatory myopathy.

Three cases of anti-TNF induced myositis and literature review

Anti-tumor necrosis factor (anti-TNF) drugs are frequently preferred in the treatment of rheumatologic diseases and other inflammatory diseases. The development of myositis after using anti-TNF is a rare clinical condition. Here we aimed to report cases who developed myositis after using anti-TNF and review the current literature. We report two cases of rheumatoid arthritis (RA) and a case of ankylosing spondylitis (AS) developed idiopathic inflammatory myopathy following anti-TNF therapy. In conclusion, myositis could develop during anti-TNF therapy, so these patients should be evaluated carefully initially for myositis and should be closely monitored due to the potential for developing myositis in treatment process.

Autoantibody levels in myositis patients correlate with clinical response during B cell depletion with rituximab

OBJECTIVES

To determine the longitudinal trends in serum levels of four myositis-associated autoantibodies: anti-Jo-1, -transcription intermediary factor 1 γ (TIF1-γ), -signal recognition particle (SRP) and -Mi-2, after B cell depletion with rituximab, and to determine the longitudinal association of these autoantibody levels with disease activity as measured by myositis core-set measures (CSMs).

METHODS

Treatment-resistant adult and pediatric myositis subjects (n = 200) received rituximab in the 44-week Rituximab in Myositis Trial. CSMs [muscle enzymes, manual muscle testing (MMT), physician and patient global disease activity, HAQ, and extramuscular disease activity] were evaluated monthly and anti-Jo-1 (n = 28), -TIF1-γ (n = 23), -SRP (n = 25) and -Mi-2 (n = 26) serum levels were measured using validated quantitative ELISAs. Temporal trends and the longitudinal relationship between myositis-associated autoantibodies levels and CSM were estimated using linear mixed models.

RESULTS

Following rituximab, anti-Jo-1 levels decreased over time (P < 0.001) and strongly correlated with all CSMs (P < 0.008). Anti-TIF1-γ levels also decreased over time (P < 0.001) and were only associated with HAQ, MMT and physician and patient global disease activity. Anti-SRP levels did not change significantly over time, but were significantly associated with serum muscle enzymes. Anti-Mi-2 levels significantly decreased over time and were associated with muscle enzymes, MMT and the physician global score.

CONCLUSION

Anti-Jo-1, anti-TIF1-γ and anti-Mi-2 levels in myositis subjects decreased after B cell depletion and were correlated with changes in disease activity, whereas anti-SRP levels were only associated with longitudinal muscle enzyme levels. The strong association of anti-Jo-1 levels with clinical outcomes suggests that anti-Jo-1 autoantibodies may be a good biomarker for disease activity.

Efficacy of Rituximab in Refractory Inflammatory Myopathies Associated with Anti- Synthetase Auto-Antibodies: An Open-Label, Phase II Trial

OBJECTIVE

Anti-synthetase syndrome (anti-SS) is frequently associated with myositis and interstitial lung disease (ILD). We evaluated prospectively, in a multicenter, open-label, phase II study, the efficacy of rituximab on muscle and lung outcomes.

METHODS

Patients were enrolled if they were refractory to conventional treatments (prednisone and at least 2 immunosuppressants). They received 1 g of rituximab at D0, D15, and M6. The primary endpoint was muscular improvement based on manual muscular testing (MMT10, Kendall score in 10 muscles) at M12. Secondary endpoints were normalization of creatine kinase (CK) level, ILD improvement based on forced vital capacity and/or diffuse capacity for carbon monoxide, and number and/or doses of associated immunosuppressants.

RESULTS

Twelve patients were enrolled, and 10 completed the study. Only 2 patients presented an improvement of at least 4 points on at least two muscle groups (primary end-point). Overall, seven patients had an increase of at least 4 points on MMT10. CK level decreased from 399 IU/L (range, 48-11,718) to 74.5 IU/L (range, 40-47,857). Corticosteroid doses decreased from 52.5 mg/d (range, 10-70) to 9 mg/d (range, 7-65) and six patients had a decrease in the burden of their associated immunosuppressants. At baseline, all 10 patients presented with ILD. At M12, improvement of ILD was observed in 5 out of the 10 patients, stabilization in 4, and worsening in 1.

CONCLUSIONS

This pilot study of rituximab treatment in patients with refractory anti-SS provided data on evolution of muscular and pulmonary parameters. Rituximab should now be evaluated in a larger, controlled study for this homogenous group of patients.

TRIAL REGISTRATION

Clinicaltrials.gov NCT00774462.

Predictors of clinical improvement in rituximab-treated refractory adult and juvenile dermatomyositis and adult polymyositis

OBJECTIVE

To identify the clinical and laboratory predictors of clinical improvement in a cohort of myositis patients treated with rituximab.

METHODS

We analyzed data for 195 patients with myositis (75 with adult polymyositis [PM], 72 with adult dermatomyositis [DM], and 48 with juvenile DM) in the Rituximab in Myositis trial. Clinical improvement was defined as 20% improvement in at least 3 of the following 6 core set measures of disease activity: physician's and patient's/parent's global assessment of disease activity, manual muscle testing, physical function, muscle enzymes, and extramuscular disease activity. We analyzed the association of the following baseline variables with improvement: myositis clinical subgroup, demographics, myositis damage, clinical and laboratory parameters, core set measures, rituximab treatment, and myositis autoantibodies (antisynthetase, anti-Mi-2, anti-signal recognition particle, anti-transcription intermediary factor 1γ [TIF-1γ], anti-MJ, other autoantibodies, and no autoantibodies). All measures were univariately assessed for association with improvement using time-to-event analyses. A multivariable time-dependent proportional hazards model was used to evaluate the association of individual predictive factors with improvement.

RESULTS

In the final multivariable model, the presence of an antisynthetase, primarily anti-Jo-1 (hazard ratio [HR] 3.08, P < 0.01), anti-Mi-2 (HR 2.5, P < 0.01), or other autoantibody (HR 1.4, P = 0.14) predicted a shorter time to improvement compared to the absence of autoantibodies. A lower physician's global assessment of damage (HR 2.32, P = 0.02) and juvenile DM (versus adult myositis) (HR 2.45, P = 0.01) also predicted improvement. Unlike autoantibody status, the predictive effect of physician's global assessment of damage and juvenile DM diminished by week 20. Rituximab treatment did not affect these associations.

CONCLUSION

Our findings indicate that the presence of antisynthetase and anti-Mi-2 autoantibodies, juvenile DM subset, and lower disease damage strongly predict clinical improvement in patients with refractory myositis.

Liver abnormalities in connective tissue diseases

The liver is a lymphoid organ involved in the immune response and in the maintenance of tolerance to self molecules, but it is also a target of autoimmune reactions, as observed in primary liver autoimmune diseases (AILD) such as autoimmune hepatitis, primary biliary cirrhosis, and primary sclerosing cholangitis. Further, the liver is frequently involved in connective tissue diseases (CTD), most commonly in the form of liver function test biochemical changes with predominant cholestatic or hepatocellular patterns. CTD commonly affecting the liver include systemic lupus erythematosus, antiphospholypid syndrome, primary Sjögren's syndrome, systemic sclerosis, dermatomyositis, polimyositis, and anti-synthetase syndrome, while overlap syndromes between AILD and CTD may also be diagnosed. Although liver cirrhosis and failure are extremely rare in patients with CTD, unusual liver conditions such as nodular regenerative hyperplasia or Budd-Chiari syndrome have been reported with increasing frequency in patients with CTD. Acute or progressing liver involvement is generally related to viral hepatitis reactivation or to a concomitant AILD, so it appears to be fundamental to screen patients for HBV and HCV infection, in order to provide the ideal therapeutic regimen and avoid life-threatening reactivations. Finally, it is important to remember that the main cause of biochemical liver abnormalities in patients with CTD is a drug-induced alteration or coexisting viral hepatitis. The present article will provide a general overview of the liver involvement in CTD to allow rheumatologists to discriminate the most common clinical scenarios.

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.

Plasmonic substrates for multiplexed protein microarrays with femtomolar sensitivity and broad dynamic range

Protein chips are widely used for high-throughput proteomic analysis, but to date, the low sensitivity and narrow dynamic range have limited their capabilities in diagnostics and proteomics. Here we present protein microarrays on a novel nanostructured, plasmonic gold film with near-infrared fluorescence enhancement of up to 100-fold, extending the dynamic range of protein detection by three orders of magnitude towards the fM regime. We employ plasmonic protein microarrays for the early detection of a cancer biomarker, carcinoembryonic antigen, in the sera of mice bearing a xenograft tumour model. Further, we demonstrate a multiplexed autoantigen array for human autoantibodies implicated in a range of autoimmune diseases with superior signal-to-noise ratios and broader dynamic range compared with commercial nitrocellulose and glass substrates. The high sensitivity, broad dynamic range and easy adaptability of plasmonic protein chips presents new opportunities in proteomic research and diagnostics applications.

Antisynthetase syndrome

Autoantibodies to eight of the aminoacyl-transfer RNA synthetases-the most well-recognized of which is anti-histidyl (Jo-1)-have all been implicated in the pathogenesis of antisynthetase syndrome (AS). AS is characterized by varying degrees of interstitial lung disease, myositis, arthropathy, fever, Raynaud's phenomenon, and mechanic's hands, and the morbidity and mortality of the disease are usually linked to the pulmonary findings. The value of a lung biopsy in AS cannot be overemphasized, as it serves to describe the underlying etiology of the interstitial lung disease, guide therapy, and estimate prognosis. Muscle disease shares many clinical features of polymyositis, yet histologically, the inflammatory involvement resembles that of dermatomyositis. Because inflammatory arthritis mimics rheumatoid arthritis, AS should be considered in atypical cases. Corticosteroids are the mainstay of acute therapy, although treatment often requires immunosuppressant medications such as cyclophosphamide, azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, or rituximab.

Rituximab treatment in patients with refractory inflammatory myopathies

OBJECTIVE

To assess the efficacy of rituximab on disease activity and muscle strength in patients with inflammatory myopathies refractory to conventional therapy. METHODS; Thirteen patients were treated with rituximab 1000 mg i.v., twice, with a 2-week interval and followed for a median of 27 months. Primary outcomes were disease activity measured by creatine phosphokinase (CPK), lactate dehydrogenase (LDH) levels and muscle strength measured by hand-held dynamometry and manual muscle testing (MMT). Secondary outcomes were improvement in secondary laboratory measures, global assessment of general health, disease activity and pain, CS dose, functional ability, health-related quality of life and safety. Retreatment with rituximab was conducted if disease activity relapsed. RESULTS; The median levels of CPK and LDH were significantly reduced by 93.2 and 39.8%, respectively, compared with baseline after 34.6 months. The median muscle strength measured by hand-held dynamometry was significantly improved by 21.5% after 24 months. The median increase in muscle strength measured with MMT was 7.0% after 24 months of follow-up, although this did not reach statistical significance. Secondary outcomes improved as well. CONCLUSION; Rituximab is an effective treatment in refractory inflammatory myopathies, showing a decrease in CPK and LDH, an increase in muscle strength and improvement in scores of disease activity, general health, functional ability and health related quality of life with sustained effect during a median of 27.1 months of follow-up.

Role of innate immunity in a murine model of histidyl-transfer RNA synthetase (Jo-1)-mediated myositis

OBJECTIVE

Previous studies in humans and in animal models support a key role of histidyl-transfer RNA synthetase (HisRS; also known as Jo-1) in the pathogenesis of idiopathic inflammatory myopathy. While most investigations have focused on the ability of HisRS to trigger adaptive immune responses, in vitro studies clearly indicate that HisRS possesses intrinsic chemokine-like properties capable of activating the innate immune system. The purpose of this study was therefore to examine the ability of HisRS to direct innate immune responses in a murine model of myositis.

METHODS

Following intramuscular immunization with soluble HisRS in the absence of exogenous adjuvant, selected strains of mice were evaluated at different time points for histopathologic evidence of myositis. Enzyme-linked immunosorbent assay-based assessment of autoantibody formation and carboxyfluorescein succinimidyl ester proliferation studies provided complementary measures of B cell and T cell responses triggered by HisRS immunization.

RESULTS

Compared to appropriate control proteins, a murine HisRS fusion protein induced robust, statistically significant muscle inflammation in multiple congenic strains of C57BL/6 and NOD mice. Time course experiments revealed that this inflammatory response occurred as early as 7 days postimmunization and persisted for up to 7 weeks. Parallel immunization strategies in DO11.10/RAG-2(-/-) and C3H/HeJ (TLR-4(-/-) ) mice indicated that the ability of murine HisRS to drive muscle inflammation was not dependent on B cell receptor or T cell receptor recognition and did not require Toll-like receptor 4 signaling.

CONCLUSION

Collectively, the findings of these experiments support a model in which HisRS can trigger both innate and adaptive immune responses that culminate in severe muscle inflammation that is the hallmark of idiopathic inflammatory myopathy.

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.

The pulmonary histopathologic manifestations of the anti-Jo-1 tRNA synthetase syndrome

Of the idiopathic inflammatory myopathies, the anti-aminoacyl tRNA synthetase syndrome has the greatest association with interstitial lung disease (ILD). We reviewed 13 open surgical lung biopsies, four autopsies, and three native lungs resected at transplantation, for pulmonary ILD associated with the presence of anti-histidyl tRNA synthetase (anti-Jo-1) autoantibodies. Fifty percent (N=10) of patients presented with an acute decompensation of pulmonary function manifested as diffuse alveolar damage, although in five patients (25%) this marked diminution in function was superimposed on an underlying chronic interstitial pneumonia (usual interstitial pneumonia (three); nonspecific interstitial pneumonia(two)). Seven (35%) patients had usual interstitial pneumonia and two (10%) had nonspecific interstitial pneumonia exclusively, whereas one patient presented with an organizing pneumonia (5%). This study is the first to highlight the high biopsy incidence of diffuse alveolar damage in this patient population both de novo and superimposed on underlying chronic ILD, and also shows that usual interstitial pneumonia remains a significant pattern of interstitial injury in this autoimmune group. On the basis of coexisting patterns of lung injury, this study also suggests that nonspecific interstitial pneumonia in connective tissue disorders may progress over time to a usual interstitial pneumonia pattern of fibrosis, an observation that could be better assessed with future inclusion of autopsy and transplanted native lungs in study groups.

Sensitive and robust luminescent profiling of anti-La and other autoantibodies in Sjogren's syndrome

Sjogren's syndrome (SjS) patients often have a variety of extraglandular manifestations including neurological and gastrointestinal involvement. In this study we evaluated the diagnostic performance of luciferase immunoprecipitation system (LIPS) that employs mammalian cell-produced recombinant antigens for analyzing SjS autoantibody responses. LIPS testing of mammalian cell-produced La, Ro60 and Ro52 recombinant antigens with defined commercial antibodies demonstrated highly specific immunoprecitation of each antigen without cross-reactivity. Next, sera from 57 SjS and 25 volunteers were evaluated by LIPS against a panel of human autoantigens. LIPS detected robust anti-La antibody levels in 43/57 SjS patients (75% sensitivity) and markedly outperformed an ELISA (46% sensitivity). Profiling of other SjS-associated autoantigens revealed the presence of anti-Ro60, anti-Ro52 in 63% and 61%, of SjS patients, respectively. Interestingly, a C-terminal fragment of Ro52 (Ro52-Delta2), a protein fragment not previously found to be antigenic by ELISA, also showed positive immunoreactivity in 42/57 SjS patients (65% sensitivity). Additional profiling of other autoantigens revealed that certain SjS patients also showed positive immunoreactivity with thyroid peroxidase (14%), AQP-4 (12%) and the H(+)/K(+) gastric ATPase (16%) suggesting potential autoantibody attack of thyroid, neuronal and gastric parietal cells, respectively. These heterogeneous autoantibody responses detected by LIPS in SjS will likely be useful for diagnosis and for evaluating extraglandular manifestations.

Defining cancer risk in dermatomyositis. Part II. Assessing diagnostic usefulness of myositis serology

In part 1 of this review, we examined the evidence behind the association between idiopathic inflammatory myopathies (IIM) and cancers. In view of the well-recognized association between cancer and myositis (hence the term cancer-associated myositis, or CAM), clinicians responsible for the management of patients with myositis must make important decisions regarding how intensively they undertake searches for malignancy. Clinicians must also decide how often such searches are repeated, and again how intensively, to optimize both cancer detection and treatment, and thus patient survival. As the risks of CAM are greatest in dermatomyositis, this is an issue of obvious importance to dermatologists. In this second of two reviews, we examine the role of autoantibodies as potential predictors of cancer risk in patients with IIM.

The diagnostic utility of myositis autoantibody testing for predicting the risk of cancer-associated myositis

OBJECTIVES

There is a known association between myositis and cancer. The risk is greater in dermatomyositis (DM) than polymyositis (PM), although reliable methods to predict cancer risk in specific patients with myositis are not presently available. This study was undertaken to determine whether risk of developing cancer in myositis can be predicted by antibody profiling.

METHODS

A cross-sectional study of UK Caucasian adults with PM (n = 109), DM (n = 103) and connective tissue disease overlap (myositis/CTD-overlap, n = 70). Patients were tested for a comprehensive range of myositis-specific/associated autoantibodies. Sensitivity and specificity analyses were performed for the optimal identification of cancer risk.

RESULTS

Sixteen patients had cancer-associated myositis (CAM) (15 DM, 1 myositis/CTD-overlap). CAM patients were older at disease onset, and patients without myositis-specific/associated autoantibodies on "routine" laboratory testing (negative for anti-Jo-1, anti-PM-Scl, anti-U1-RNP, anti-U3-RNP, anti-Ku antibodies) had a significantly increased risk of CAM. Possession of the antibody against 155 kDa and 140 kDa protein specificities (anti-155/140 antibody) represented a significant risk factor for CAM, and was found exclusively in DM. A positive anti-155/140 antibody result proved highly specific, moderately sensitive, with high negative predictive value for CAM. A "negative routine myositis antibody panel" result was highly sensitive, with high negative predictive value for CAM. The combination of these two approaches was 94% sensitive, detecting 15 of 16 CAM, with 100% sensitivity and negative predictive value in DM.

CONCLUSIONS

These results may help clinicians predict which patients with myositis are at greater risk of developing cancer, thus identifying those requiring aggressive diagnostic evaluation and intensive cancer surveillance at myositis onset and follow-up.