Fine specificity of the Ro/SSA autoantibody response in relation to serological and clinical findings in 96 patients with self-reported cutaneous symptoms induced by the sun

Ro52/TRIM21 - From host defense to autoimmunity

Ro52 (TRIM21) belongs to the ubiquitin ligase family. This protein plays a crucial role in many immunological processes, including antibody-dependent intracellular neutralization, synergy with the complement system, antiviral response, death mediation, oxidative stress response, and protein ubiquitination. Abnormal expression of TRIM21 can break immunological tolerance and lead to the production of autoantibodies against TRIM21. Antibodies against TRIM21 are detected in various autoimmune diseases, including Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), or myositis. However, anti-TRIM21 presence is not limited to autoimmune connective tissue disorders. It was observed in patients with malignancies, various cancerous processes, infectious diseases, and idiopathic interstitial pneumonia. The occurrence of TRIM21 autoantibodies is also associated with clinical features, such as the prevalence of interstitial lung diseases and cardiac or haematological involvement in connective tissue disorders. The purpose of this review was to summarize current knowledge of the immunological functions of TRIM21 and analyze the clinical implications of anti-TRIM21 antibodies in the disease course.

Modulation of Immune Cells as a Therapy for Cutaneous Lupus Erythematosus

Cutaneous lupus erythematosus (CLE) is an autoimmune disorder like systemic lupus erythematosus (SLE). Both SLE and CLE characterize autoantibody secretion and immune cell recruitment. In particular, CLE can be divided into three more frequent types, varying in the severity of the skin lesions they present. The role of type I IFN was shown to be one of the leading causes of the development of this pathology in the skin. Different treatments have been developed and tested against these different variants of CLE to decrease the increasing levels of CLE in humans. In this article, a literature revision discussing the similarities between SLE and CLE is carried out. In addition, new advances in understanding the development of CLE and the leading treatments being evaluated in animal models and clinical trials are reviewed.

An updated review of anti-Ro52 (TRIM21) antibodies impact in connective tissue diseases clinical management

Anti-Ro52 (or anti-TRIM21) antibodies are part of the family of anti-Ro/SSA antibodies, historically markers of Sjögren syndrome and systemic lupus erythematosus. Anti-Ro52 antibodies represent one the most frequently encountered autoantibodies in patients with connective tissue disease (primary Sjögren syndrome, systemic lupus erythematosus, systemic sclerosis and idiopathic inflammatory myopathies). Because of their lack of specificity and detection in patients with non-autoimmune disorders, the usefulness of anti-Ro52 testing in connective tissue diseases is still matter of debate among clinicians and immunologists. Autoantibodies are mainly diagnostic markers for autoimmune diseases but some of them can also be directly involved in the generation of tissue damage. Over the past decade several authors reported associations of anti-Ro52 antibodies with some clinical features - especially interstitial lung disease - and survival in patients with connective tissue diseases. There is also a growing evidence of the role of anti-Ro52 antibodies in the pathogenesis of connective tissue diseases. In this review, we comprehensively discuss the clinical associations of anti-Ro52 antibodies in the different connective tissue diseases and the recent advances on their potential role in the inflammatory response.

Anti-Ro52 antibody is highly prevalent and a marker of better prognosis in patients with ovarian cancer

BACKGROUND AND AIMS

Anti-Ro52 antibody (Ab) reactivity is highly prevalent in autoimmune rheumatic diseases (ARDs), mainly Sjögren's syndrome (SjS) and systemic lupus erythematosus (SLE), but also in other inflammatory disorders. Thorough assessment of the prevalence, clinical significance and epitope specificity of Ro52-autoAbs in cancerous diseases is still lacking.

MATERIAL AND METHODS

Anti-Ro52 Ab reactivity was tested in a large cohort of 490 patients with various malignant diseases. Ro52-autoAb epitope mapping by an in house line immunoassay was carried out using 5 recombinant Ro52 polypeptides spanning Ro52.

RESULTS

Anti-Ro52 abs were significantly more prevalent in patients with ovarian cancer (30%) compared to patients with 6 other malignant diseases (median 8.1%, range 5.9-15.8%). The presence of anti-Ro52 abs in patients with ovarian cancer was strongly associated with better overall survival. Ro52 epitope mapping of patients with ovarian cancer was dissimilar to that of SLE and SjS ARDs, less frequently recognizing Ro52-1 and Ro52-4 fragments compared to patients with SLE and SjS.

CONCLUSION

We demonstrate for first time an unexpectedly high frequency of anti-Ro52 abs in patients with ovarian cancer, their presence indicating better overall survival. Their distinguishing epitope profile may suggest a non-SLE or SjS-related stimulus for autoAb production.

Current Insights in Cutaneous Lupus Erythematosus Immunopathogenesis

Cutaneous Lupus Erythematosus (CLE) is a clinically diverse group of autoimmune skin diseases with shared histological features of interface dermatitis and autoantibodies deposited at the dermal-epidermal junction. Various genetic and environmental triggers of CLE promote infiltration of T cells, B cells, neutrophils, antigen presenting cells, and NK cells into lesional skin. In this mini-review, we will discuss the clinical features of CLE, insights into CLE immunopathogenesis, and novel treatment approaches.

Diagnostic Utility of Separate Anti-Ro60 and Anti-Ro52/TRIM21 Antibody Detection in Autoimmune Diseases

Anti-SS-A antibodies are often sought for in autoimmune diseases diagnosis. Two different target proteins have actually been identified: Ro52 and Ro60. Clinical and immunological associations seem different depending on anti-Ro52 or anti-Ro60 antibodies presence. However, due to a heterogeneous presentation in the literature, some immunology laboratories in France have stopped providing anti-Ro52 antibody findings. We report here a new hospital study designed to determine the diagnostic utility of the separate detection of anti-Ro52 and anti-Ro60 antibodies. We conducted a retrospective, observational study, including every adult patient with positive antinuclear antibodies (ANA) tested in our immunology laboratory, and associated with anti-Ro52 and/or anti-Ro60 antibodies, between 2011 and 2014. Out of 13032 sera tested for ANA, 399 adults had antibodies to Ro52 and/or Ro60; 81.7% were female, with a mean age of 54.5 ± 17.0 years. Anti-Ro52 antibodies were found in 75.7% of the patients and anti-Ro60 antibodies in 56.9%. Among them, 43.1% were classified in the Ro52 + Ro60- group, 32.6% in the Ro52 + Ro60 + group and 24.3% in the Ro52-Ro60+ group. In the Ro52-Ro60+ group, systemic lupus was the most frequent diagnosis (48.5%), with a possible association with antiphospholipid antibodies (anti-cardiolipin antibodies: OR 2.5 (CI95 [1.0-5.0], p = 0.05) and lupus anticoagulant {OR 3.6 (CI95 [1.10-10.0] p = 0.02)}. In the Ro52+Ro60+, primary Sjögren Syndrome was the most likely (OR 4.2 95% CI [2.1-8.3] p < 10^-4), especially in patients Ro52+Ro60+La+. Patients with isolated anti-Ro52 had a wider variety of diseases associated, but among auto-immune diseases they were more prone to inflammatory myositis (OR 10.5 [1.4-81.7], p = 0.02) and inflammatory rheumatism (OR 4.6 [1.6-13.8], p = 0.006) in contrast to systemic lupus (OR 0.2 [0.1-0.3], p < 10^-4) or primary Sjögren's syndrome (OR 0.1 [0.06-0.2], p < 10^-4). We therefore suggest that, when anti-ENA antibodies are prescribed, it should include separate anti-Ro52 and anti-Ro60 antibodies determination. To go even further, we would like to suggest a change in ENA nomenclature to avoid confusion, abandoning the anti-SS-A label in favor of the anti-Ro52/TRIM21 or anti-Ro60 antibody for a clearer designation.

Anti-tubulin-α-1C autoantibody in systemic lupus erythematosus: a novel indicator of disease activity and vasculitis manifestations

A variety of autoantibodies has been involved in the pathogenesis of systemic lupus erythematosus (SLE), some of which are well known and applied as disease biomarkers. This study aimed to determine the prevalence of a novel autoantibody, anti-tubulin-α-1C, in patients with SLE and investigate its clinical significance. Anti-tubulin-α-1C autoantibody levels were determined by enzyme-linked immunosorbent assay (ELISA) in 128 SLE patients, 38 primary Sjögren's syndrome (pSS) patients, and 106 healthy controls (HCs).White blood cell (WBC) count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), IgM, IgG, C3, C4, RF, ANA, dsDNA, Sm, AnuA, aCL, anti-SSA, and anti-SSB were measured by standard laboratory techniques. SLE Disease Activity Index (SLEDAI) was evaluated accordingly. Anti-tubulin-α-1C antibody levels were significantly increased in SLE patients. Elevated anti-tubulin-α-1C were correlated with higher levels of SLEDAI, increased titers of anti-Sm antibody, and decreased titers of anti-dsDNA antibody and significantly associated with cutaneous and mucosal vasculitis and milder renal involvement. Anti-tubulin-α-1C may become a novel biomarker indicative of active vasculitis in SLE and could be applied in future clinical practice.

Association of anti-Ro52, anti-Ro60 and anti-La antibodies with diagnostic, clinical and laboratory features in a referral hospital in Jerez, Spain

OBJECTIVE

Several antibodies have proven to be useful in autoimmune diseases, as markers for diagnosis, prognosis or clinical manifestations. Our objective was to evaluate the diagnosis and manifestations associated for antibodies anti-Ro52, anti-Ro60 and anti-La at a referral hospital in Spain.

METHODS

We retrospectively analyzed the antigenic specificities of the consecutive samples submitted to the Immunology Unit for antinuclear antibody screening between 2002 and 2012. We included patients with more than one positive sample for some of the autoantibodies anti-Ro52, anti-Ro60 or anti-La. We also reviewed diagnosis, clinical and laboratory features. As dependent variable we evaluated possible combinations of anti-Ro52, anti-Ro60 and anti-La.

RESULTS

322 patients, 91% females, were studied (age 44.3±15.51 years). The most frequent diagnosis was Sjögren's syndrome (40.06%) and systemic lupus erythematosus (SLE) (36.6%). The most prevalent pattern by indirect immunofluorescence was the fine speckled (69.9%). Anti-Ro52+/anti-Ro60+/anti-La+ combination was positively associated with fine speckled pattern (p: 0.001) and negatively with homogeneous (p: 0.016) and cytoplasmic pattern (p: 0.002). Isolated anti-Ro52+ was negatively associated with fine speckled pattern (p<0.001) and positively with the cytoplasmic one (p<0.001). The main positive associations with clinical symptoms were xerostomia and xerophthalmia with anti-Ro52+/anti-Ro60+/anti-La+ (p<0.001), oral ulcers with anti-Ro52+/anti-Ro60+/anti-La- (p: 0.002) and alopecia with anti-Ro52-/anti-Ro60+/anti-La- (p: 0.003). Negative associations were xerophthalmia and photosensitivity with anti-Ro52+/anti-Ro60-/anti-La- (p: 0.003). Laboratory positive associations were hypergammaglobulinemia with anti-Ro52+/anti-Ro60+/anti-La+ (p: 0.003), and hypocomplementemia with anti-Ro52-/anti-Ro60+/anti-La- (p: 0.003). Leucopenia was negatively associated with anti-Ro52+/anti-Ro60-/anti-La- (p: 0.003).

CONCLUSION

Our study found significant relationships between clinical and laboratory manifestations with different patterns of antibodies to anti-Ro52, anti-Ro60 and anti-La. The combination of antibodies might be clinically useful due to prognostic and therapeutic implications.

Extended B cell phenotype in patients with myalgic encephalomyelitis/chronic fatigue syndrome: a cross-sectional study

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a heterogeneous condition of unknown aetiology characterized by multiple symptoms including fatigue, post-exertional malaise and cognitive impairment, lasting for at least 6 months. Recently, two clinical trials of B cell depletion therapy with rituximab (anti-CD20) reported convincing improvement in symptoms. A possible but undefined role for B cells has therefore been proposed. Studies of the relative percentages of B cell subsets in patients with ME/CFS have not revealed any reproducible differences from healthy controls (HC). In order to explore whether more subtle alterations in B cell subsets related to B cell differentiation exist in ME/CFS patients we used flow cytometry to immunophenotype CD19⁺ B cells. The panel utilized immunoglobulin (Ig)D, CD27 and CD38 (classical B cell subsets) together with additional markers. A total of 38 patients fulfilling Canadian, Centre for Disease Control and Fukuda ME/CFS criteria and 32 age- and sex-matched HC were included. We found no difference in percentages of classical subsets between ME/CFS patients and HC. However, we observed an increase in frequency (P < 0·01) and expression (MFI; P = 0·03) of CD24 on total B cells, confined to IgD⁺ subsets. Within memory subsets, a higher frequency of CD21⁺ CD38⁻ B cells (> 20%) was associated with the presence of ME/CFS [odds ratio: 3·47 (1·15-10·46); P = 0·03] compared with HC, and there was a negative correlation with disease duration. In conclusion, we identified possible changes in B cell phenotype in patients with ME/CFS. These may reflect altered B cell function and, if confirmed in other patient cohorts, could provide a platform for studies based on clinical course or responsiveness to rituximab therapy.

Smoking is highly associated with discoid lupus erythematosus and lupus erythematosus tumidus: analysis of 405 patients

BACKGROUND

Environmental factors appear to play a role in the pathogenesis of lupus erythematosus (LE).

OBJECTIVE

To determine the association between cigarette smoking and various types of cutaneous LE.

DESIGN

Retrospective descriptive study at a dermatology clinic of a tertiary referral hospital.

METHODS

All patients diagnosed with cutaneous and/or systemic LE from January 2000 to December 2012 at the outpatient clinic for dermatological autoimmune diseases were analyzed.

RESULTS

405 patients were diagnosed with LE. Smokers were more common among patients with cutaneous LE, especially those with LE tumidus or discoid LE. The frequency of cigarette smokers was not significantly higher among patients with other LE-specific skin lesions and patients with systemic LE compared to the general population. Smoking at the onset of disease was associated with LE tumidus (odds ratio OR 4.5), discoid LE (OR 2.05), the male gender (OR 3.31), age < 50 years (OR 1.03), and photosensitivity (OR 2.07).

LIMITATIONS

A retrospective descriptive study at a tertiary referral hospital.

CONCLUSION

Smoking is highly associated with cutaneous LE, but not systemic LE. Various risk factors appear to be involved in the pathogenesis of cutaneous and systemic LE.

The association of serum anti-ribosomal P antibody with clinical and serological disorders in systemic lupus erythematosus: a systematic review and meta-analysis

Objective

Anti-ribosomal P (anti-P) antibody is a serological specific marker of systemic lupus erythematosus (SLE). The aim of this study is to investigate the association of this antibody with clinical and serological disorders in SLE.

Methods

All relevant literature was retrieved from PubMed, EMBASE, Web of Science and CNKI databases. The qualities of these studies were evaluated using a modified version of the Newcastle–Ottawa scale. The associations of anti-P antibody with clinical and serological disorders were determined by the pooled odds ratio (OR) and the confidence interval (CI) calculated using meta-analysis with the Mantel–Haenszel method.

Results

Sixteen cohort studies with 2355 patients were included in this study. Malar rash, oral ulcer and photosensitivity were strongly associated with serum anti-P antibody, with OR (95% CI) values of 2.05 (1.42–2.92), 1.49 (1.05–2.13) and 1.44 (1.08–1.91), respectively. Arthritis and renal involvement were not associated with anti-P antibody, whereas a high heterogeneity was observed due to ethnicity and publication bias, respectively. Neuropsychiatric SLE (NPSLE), hepatic involvement, anti-dsDNA, anti-Sm and anti-cardiolipin antibodies (aCL) were observed more frequently in anti-P positive patients than in negative patients. Studies on hepatic involvement showed a low precision with substantially broad CI (2.56–11.2). A high heterogeneity presented among studies on NPSLE, anti-Sm and aCL.

Conclusions

Anti-P antibody is significantly associated with malar rash, oral ulcer, photosensitivity and serum anti-dsDNA antibody, and potentially associated with NPSLE, hepatic damage, serum anti-Sm and aCL.

Cutaneous lupus erythematosus: clinical aspects and molecular pathogenesis

Lupus erythematosus (LE) is an autoimmune disease with diverse clinical manifestations ranging from limited cutaneous (CLE) to potentially life-threatening systemic disease (SLE). Susceptibility to LE arises from genetic variation in multiple loci, and disease activity is provoked by exogenous or endogenous trigger(s), the best characterized of which is exposure to ultraviolet radiation (UVR). Amongst patients with LE, a cluster of photosensitive subjects with cutaneous lesions and positivity for anti-Ro/SSA autoantibodies have been described. The Ro52 antigen belongs to the tripartite motif protein family and has E3 ligase activity. New data reveal that Ro52 ubiquitinates interferon regulatory factors and modulates their transcriptional activity, indicating an important role for Ro52 in inflammation as a negative feedback regulator. Our findings indicate that UVR exposure induces upregulation of Ro52 in the CLE target cell, the keratinocyte, and that Ro52 is upregulated in spontaneous and UVR-induced CLE lesions. Recently described functional analysis of Ro52-deficient mice revealed that loss of Ro52 results in uncontrolled inflammation in response to minor skin injury leading to an LE-like condition. In summary, emerging data suggest that abnormal function or regulation of Ro52 contributes to the pathogenesis of UVR-induced CLE in genetically susceptible individuals. Ro52 may thus be an interesting therapeutic target, as its activation could contribute to downregulation of the chronic inflammatory process in LE. Here, we review the available data on the pathogenesis of CLE and, in particular, the role of the Ro52 autoantigen.

Autoantibodies to the functionally active RING-domain of Ro52/SSA are associated with disease activity in patients with lupus

The Ro52 protein of the Ro/SSA antigen was recently defined as an E3 ligase controlling cytokine production. Autoantibodies from systemic lupus erythematosus (SLE) patients targeting the Ro52-RING domain, containing the E3 ligase activity, have been shown to inhibit the E3 ligase activity of Ro52. The objective of the present study was to investigate correlations between clinical parameters in patients with SLE and levels of Ro/SSA (Ro52 and Ro60) and La/SSB autoantibodies, including autoantibodies directed towards the functional RING and B-box domains of the Ro52 protein. SLE patients (n=232) were clinically examined and disease activity indices collected concurrently to blood sampling. The samples were analyzed for immunological parameters including autoantibodies. Ro52 autoantibody levels were associated with more variables than the other analyzed antibodies and were significantly associated with several individual items related to sSS and the diagnosis of sSS itself (p=0.004). Other associated variables were high sedimentation rate (p=0.0003), levels of immunoglobulins (p=0.0003), and an inverse correlation with levels of lymphocytes (p=0.003) and leukocytes (p=0.01). Antibodies to the RING domain of Ro52, which is the functionally active domain with E3 ligase activity, were significantly correlated with disease activity as measured by the SLAM score. We conclude that autoantibodies against Ro52 and in particular its functional RING domain are important in lupus patients and associated with several clinical and laboratory features of the disease. The impact on disease activity of Ro52-RING specific antibodies was especially noted, and could imply a functional role for these autoantibodies in inhibiting Ro52 activity, which is important for the control of proinflammatory cytokine production, including type 1 interferons.

Clinical associations of anti-SSA/Ro60 and anti-Ro52/TRIM21 antibodies: Diagnostic utility of their separate detection

Clinical associations of anti-SSA/Ro60 and anti-Ro52/TRIM21 antibodies are not yet fully established. In order to analyse the diagnostic utility of their separate detection, we retrospectively revised the clinical data of 200 anti-SSA/Ro60 and/or anti-Ro52/TRIM21 positive patients identified by line immunoassay during ANA routine detection. Anti-SSA/Ro60 positive patients showed a significantly higher prevalence of autoimmune diseases (AIDs) independently on the presence of anti-Ro52/TRIM21 (OR 3.13, 95% CI 1.10-8.88, p = 0.032). Anti-SSA/Ro60 was independently associated with systemic lupus erythematosus (SLE) when comparing with Sjögren's syndrome (SS) and other systemic AIDs (OR 3.46, 95% CI 1.08-11.06, p = 0.036). The more frequent specificity found in cutaneous lupus erythematosus (CLE) was also anti-SSA/Ro60. In contrast, detection of isolated anti-Ro52/TRIM21 was characteristic of SS (7/35, 20.0%), diffuse cutaneous systemic sclerosis (dcSSc) (3/4, 75.0%), primary biliary cirrhosis (PBC) (4/5, 80.0%) and, specially, of polymyositis/dermatomyositis (PM/DM) (6/6, 100%). In fact, anti-Ro52/TRIM21 was the only antibody detected in 4 out of the 6 PM/DM patients. Malignancies mainly account for the observed high prevalence of mono-specific anti-Ro52/TRIM21 in patients with non-AIDs (10/15, 62.5%). In conclusion, this retrospective study supports the routine distinction of anti-SSA/Ro60 and anti-Ro52/TRIM21 due to their different clinical associations.

Polymorphisms of the ITGAM gene confer higher risk of discoid cutaneous than of systemic lupus erythematosus

Background

Lupus erythematosus (LE) is a heterogeneous disease ranging from mainly skin-restricted manifestations (discoid LE [DLE] and subacute cutaneous LE) to a progressive multisystem disease (systemic LE [SLE]). Genetic association studies have recently identified several strong susceptibility genes for SLE, including integrin alpha M (ITGAM), also known as CD11b, whereas the genetic background of DLE is less clear.

Principal Findings

To specifically investigate whether ITGAM is a susceptibility gene not only for SLE, but also for cutaneous DLE, we genotyped 177 patients with DLE, 85 patients with sporadic SLE, 190 index cases from SLE families and 395 population control individuals from Finland for nine genetic markers at the ITGAM locus. SLE patients were further subdivided by the presence or absence of discoid rash and renal involvement. In addition, 235 Finnish and Swedish patients positive for Ro/SSA-autoantibodies were included in a subphenotype analysis. Analysis of the ITGAM coding variant rs1143679 showed highly significant association to DLE in patients without signs of systemic disease (P-value  = 4.73×10⁻¹¹, OR  = 3.20, 95% CI  = 2.23–4.57). Significant association was also detected to SLE patients (P-value  = 8.29×10⁻⁶, OR  = 2.14, 95% CI  = 1.52–3.00), and even stronger association was found when stratifying SLE patients by presence of discoid rash (P-value  = 3.59×10⁻⁸, OR  = 3.76, 95% CI  = 2.29–6.18).

Significance

We propose ITGAM as a novel susceptibility gene for cutaneous DLE. The risk effect is independent of systemic involvement and has an even stronger genetic influence on the risk of DLE than of SLE.

Cutaneous manifestations and serological findings in 260 patients with systemic lupus erythematosus

The prevalence and prognostic value of cutaneous manifestations in patients with systemic lupus erythematosus (SLE) is not clear due to a lack of distinct criteria. Our aim was to investigate the prevalence of cutaneous manifestations in SLE patients according to strict dermatological classification, compare the results with other studies and to assess differences in serological markers between patients with and without cutaneous lupus erythematosus (CLE). Secondary aims were to investigate the validity of the criteria ‘malar rash’ and ‘photosensitivity’ for SLE diagnosis. We included 260 consecutive SLE patients, and 164 with skin complaints were examined by a dermatologist. CLE was found in 23% of the 260 SLE patients. There was agreement on the presence of malar rash in only 60% of patients seen by both rheumatologists and dermatologists. A history of polymorphous light eruption (PLE) was found in 42% of patients. Raynaud’s phenomenon was significantly more common in patients with CLE. In addition, four malignant melanomas were found. Based on our findings, we suggest that the American College of Rheumatology (ACR) criteria for SLE diagnosis include histopathologically confirmed CLE as one criterion, and that the criteria photosensitivity and malar rash should be re-defined. Regular examination by a dermatologist is called for in SLE patients.

Autoantibodies from mice exposed to Libby amphibole asbestos bind SSA/Ro52-enriched apoptotic blebs of murine macrophages

Asbestos exposure is associated with increased autoimmune responses in humans. For example, in Libby, MT where significant asbestos exposure has occurred due to an asbestos-contaminated vermiculite mine near the community, residents have developed increased autoimmune responses compared to an unexposed population. However, the exact mechanism by which Libby amphibole asbestos generates autoimmune responses is unclear. A murine model of amphibole asbestos-induced autoimmunity was recently established, and one of the targets of the autoantibodies (AAs) was the SSA/Ro52 autoantigen. The purpose of this study was to determine whether the SSA/Ro52 autoantigen is exposed at the surface of cells as a result of asbestos exposure as a possible mechanism leading to antigenicity. Our results indicate that Libby asbestos induces apoptosis in murine macrophages as determined by phosphatidylserine exposure, cleavage of poly(ADP-ribose) polymerase and morphological changes such as nuclear condensation. Moreover, asbestos-induced apoptosis results in the formation of apoptotic cell surface blebs enriched in SSA/Ro52 as determined by confocal microscopy. Most importantly, apoptotic cell surface blebs are recognized by AAs from mice exposed to amphibole asbestos suggesting that these cell surface structures may be antigenic when presented in a pro-inflammatory context. This study supports the hypothesis that the induction of apoptosis plays a key role in environmentally induced autoimmunity through cell surface exposure of a known autoantigen.