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

Amphibole, but not chrysotile, asbestos induces anti-nuclear autoantibodies and IL-17 in C57BL/6 mice

Abstract Exposure to amphibole asbestos has been associated with production of autoantibodies in mice and humans, and increases the risk of systemic autoimmune disease. However, epidemiological studies of chrysotile exposure have not indicated a similar induction of autoimmune responses. To demonstrate this difference in controlled exposures in mice, and to explore possible mechanistic explanations for the difference, C57BL/6 mice were exposed intratracheally to amphibole or chrysotile asbestos, or to saline only. Serum antinuclear antibodies (ANA), antibodies to extractable nuclear antigens (ENA), serum cytokines, and immunoglobulin isotypes were evaluated 8 months after the final treatment. The percentages of lymphocyte sub-sets were determined in the spleen and lungs. The results show that amphibole, but not chrysotile, asbestos increases the frequency of ANA/ENA in mice. Amphibole and chrysotile both increased multiple serum cytokines, but only amphibole increased IL-17. Both fibers decreased IgG1, without significant changes in other immunoglobulin isotypes. Although there were no gross changes in overall percentages of T- and B-cells in the spleen or lung, there was a significant increase in the normally rare populations of suppressor B-cells (CD19(+), CD5(+), CD1d(+)) in both the spleen and lungs of chrysotile-exposed mice. Overall, the results suggest that, while there may be an inflammatory response to both forms of asbestos, there is an autoimmune response in only the amphibole-exposed, but not the chrysotile-exposed mice. These data have critical implications in terms of screening and health outcomes of asbestos-exposed populations.

Autoimmunity and asbestos exposure

Despite a body of evidence supporting an association between asbestos exposure and autoantibodies indicative of systemic autoimmunity, such as antinuclear antibodies (ANA), a strong epidemiological link has never been made to specific autoimmune diseases. This is in contrast with another silicate dust, crystalline silica, for which there is considerable evidence linking exposure to diseases such as systemic lupus erythematosus, systemic sclerosis, and rheumatoid arthritis. Instead, the asbestos literature is heavily focused on cancer, including mesothelioma and pulmonary carcinoma. Possible contributing factors to the absence of a stronger epidemiological association between asbestos and autoimmune disease include (a) a lack of statistical power due to relatively small or diffuse exposure cohorts, (b) exposure misclassification, (c) latency of clinical disease, (d) mild or subclinical entities that remain undetected or masked by other pathologies, or (e) effects that are specific to certain fiber types, so that analyses on mixed exposures do not reach statistical significance. This review summarizes epidemiological, animal model, and in vitro data related to asbestos exposures and autoimmunity. These combined data help build toward a better understanding of the fiber-associated factors contributing to immune dysfunction that may raise the risk of autoimmunity and the possible contribution to asbestos-related pulmonary disease.

Clinical heterogeneity and outcomes of antisynthetase syndrome

The autoimmune connective tissue disease antisynthetase syndrome (ASS) is an inflammatory myopathy associated with myositis-specific autoantibodies, e.g. anti-tRNA-synthetase antibodies (ASA). Since 1976 eight different ASA have been rigorously identified, of which anti-hystidyl-tRNA synthetase (anti-Jo1) is the most prevalent. Other phenotype features of ASS include interstitial lung disease (ILD), Raynaud's phenomenon, polyarthritis, fever, and mechanic's hands. The clinical presentation of ASS varies greatly, as does the severity of involvement of different organs-both among patients and/or over the course of the disease. ILD has been associated with poor outcomes, but in general the heterogeneity of ASS prevents identification of robust prognosis indicators. Early identification of patients requiring aggressive immunosuppressive treatment is very challenging, and there are very few prospective trials available to help match treatment management to ASS clinical characteristics. This review will focus on the biological, clinical, functional, and morphological features of ASS associated with patient outcome. Our objective is to use compiled data on these subjects to discuss the usefulness of patient stratification in developing future prospective therapeutic trials.

[Therapeutic strategy in inflammatory myopathies (polymyositis, dermatomyositis, overlap myositis, and immune-mediated necrotizing myopathy)]

Inflammatory myopathies (IM) are a heterogeneous group of autoimmune muscle disorders of unknown origin that share clinical symptoms such as muscle weakness and histological features with the presence in muscle of inflammatory infiltrate. Based on clinical, histological and serological characteristics, IM can be divided into polymyositis, dermatomyositis, overlap myositis, cancer-associated myositis, immune-mediated necrotizing myopathy, and inclusion-body myositis. Because of their resistance to corticosteroids and immunosuppressive drugs, inclusion-body myositis will be treated separately in this issue. Major obstacles in conducting high quality randomized controlled trials in inflammatory myopathies include the low prevalence and the heterogeneity of these diseases as well as the lack of international consensus on the outcome measures. In the absence of adequate controlled therapeutic trials, treatment of these disorders remains largely empirical. Corticosteroids are the cornerstone therapy. Due to the chronic course of the disease, there is a frequent need to use additional immunosuppressive treatment both to improve the disease response and to reduce the side effects of corticosteroids. Intravenous immunoglobulin infusion is a costly treatment option that is reserved in the presence of refractory dermatomyositis based on a trial showing superior efficacy against control in patients with impaired swallowing or with contraindications to immunosuppressive drugs. In patients who fail second-line therapy, which usually consists of methotrexate plus corticosteroids, the diagnosis should be carefully reassessed before considering other treatment options including methotrexate plus azathioprine or biological agents such as rituximab.

[Clinical phenotypes and prognosis of antisynthetase syndrome]

Antisynthetase syndrome (ASS) was first described in 1989 as an inflammatory myopathy associated with the presence of specific auto-antibodies, namely the anti-tRNA-synthetase antibodies (ASA). To date, the ASA family comprises eight different auto-antibodies, among which anti-hystidyl-tRNA-synthetase (anti-Jo1) is the most prevalent. In addition to myositis, a constellation of clinical features has also been described in ASS, including interstitial lung disease, Raynaud's phenomenon, polyarthritis, fever and mechanic's hands. Large variations in the distribution and the severity of each of these symptoms are reported from one patient to another, and also over the course of the disease. The heterogeneity of this autoimmune connective tissue disease has led to difficulties in the early identification of patients with a poor outcome (those who will require the most intensive treatments). Additionally, very few prospective trials have so far compared the efficacy of the different immunosuppressive drugs available, and evidence is lacking to help adapting therapeutic strategies to all of the different ASS clinical situations. We will review the different characteristics of ASS (namely biological, clinical, functional, and morphological ASS parameters) that have recently been shown to correlate with patients' outcome, our aim being to discuss the usefulness of patient stratification for elaborating targeted therapeutic trials for ASS in the future.

Functional outcome and prognostic factors in anti-Jo1 patients with antisynthetase syndrome

INTRODUCTION

The aims of this present study were firstly to assess the outcome, including functional course, in anti-Jo1 positive patients with antisynthetase syndrome (ASS), and secondly to determine predictive parameters of poor outcome in these patients.

METHODS

The medical records of 86 consecutive anti-Jo1 patients with ASS were reviewed in 4 academic centers.

RESULTS

13 patients (15.1%) achieved remission of ASS, whereas 55 (63.9%) improved and 18 (20.9%) deteriorated in their clinical status. Both steroid and cytotoxic drugs could be discontinued in only 4.7% of patients. ASS was associated with decreased quality of life at long-term follow-up: only 69.2% of patients considered to be in remission experienced a return to previous normal activities; and 24.7% of other patients with non-remitting ASS still had a marked reduction of activities (as shown by the disability scale of the Health Assessment Questionnaire). Decreased quality of life was further due to calcinosis cutis (8.1%) and adverse effects of steroid therapy (36%). Factors associated with ASS deterioration were older age, pulmonary and esophageal involvement, calcinosis cutis and cancer. Higher anti-Jo1 levels were further associated with disease severity in ASS patients.

CONCLUSIONS

The present study shows high morbidity related to ASS. Furthermore, we suggest that patients with predictive factors of ASS deterioration may require more aggressive therapy. Our findings also suggest that in anti-Jo1 patients with severe esophageal manifestations, combined high dose steroids and intravenous immunoglobulins might be proposed as the first line therapy. Finally, as cancer occurred in 14% of anti-Jo1 patients, our findings underscore that the search for cancer should be performed in these patients.