Autoantigens as Partners in Initiation and Propagation of Autoimmune Rheumatic Diseases.

Systemic autoimmune diseases are characterized by specific targeting of a limited group of ubiquitously expressed autoantigens by the immune system. This review examines the mechanisms underlying their selection as immune targets. Initiation of autoimmune responses likely reflects the presentation of antigens with a distinct structure not previously encountered by the immune system, in a proimmune context (injury, malignancy, or infection). Causes of modified structure include somatic mutation and posttranslational modifications (including citrullination and proteolysis). Many autoantigens are components of multimolecular complexes, and some of the other components may provide adjuvant activity. Propagation of autoimmune responses appears to reflect a bidirectional interaction between the immune response and the target tissues in a mutually reinforcing cycle: Immune effector pathways generate additional autoantigen, which feeds further immune response. We propose that this resonance may be a critical principle underlying disease propagation, with specific autoantigens functioning as the hubs around which amplification occurs.

Comparing anti-tumor and anti-self immunity in a patient with melanoma receiving immune checkpoint blockade.

BACKGROUND: Tumor regression following immune checkpoint blockade (ICB) is often associated with immune-related adverse events (irAEs), marked by inflammation in non-cancerous tissues. This study was undertaken to investigate the functional relationship between anti-tumor and anti-self immunity, to facilitate irAE management while promoting anti-tumor immunity. METHODS: Multiple biopsies from tumor and inflamed tissues were collected from a patient with melanoma experiencing both tumor regression and irAEs on ICB, who underwent rapid autopsy. Immune cells infiltrating melanoma lesions and inflamed normal tissues were subjected to gene expression profiling with multiplex qRT-PCR for 122 candidate genes. Subsequently, immunohistochemistry was conducted to assess the expression of 14 candidate markers of immune cell subsets and checkpoints. TCR-beta sequencing was used to explore T cell clonal repertoires across specimens. RESULTS: While genes involved in MHC I/II antigen presentation, IFN signaling, innate immunity and immunosuppression were abundantly expressed across specimens, irAE tissues over-expressed certain genes associated with immunosuppression (CSF1R, IL10RA, IL27/EBI3, FOXP3, KLRG1, SOCS1, TGFB1), including those in the COX-2/PGE2 pathway (IL1B, PTGER1/EP1 and PTGER4/EP4). Immunohistochemistry revealed similar proportions of immunosuppressive cell subsets and checkpoint molecules across samples. TCRseq did not indicate common TCR repertoires across tumor and inflammation sites, arguing against shared antigen recognition between anti-tumor and anti-self immunity in this patient. CONCLUSIONS: This comprehensive study of a single patient with melanoma experiencing both tumor regression and irAEs on ICB explores the immune landscape across these tissues, revealing similarities between anti-tumor and anti-self immunity. Further, it highlights expression of the COX-2/PGE2 pathway, which is known to be immunosuppressive and potentially mediates ICB resistance. Ongoing clinical trials of COX-2/PGE2 pathway inhibitors targeting the major COX-2 inducer IL-1B, COX-2 itself, or the PGE2 receptors EP2 and EP4 present new opportunities to promote anti-tumor activity, but may also have the potential to enhance the severity of ICB-induced irAEs.

Autoantibodies in post-treatment Lyme disease and association with clinical symptoms.

OBJECTIVES: Autoantibodies have been described in the post-infectious state, specifically after Lyme disease and COVID-19. We aimed to describe the prevalence and potential clinical utility of several commercially available autoantibodies after these infections. METHODS: Euroimmun panels (myositis, scleroderma and ANA5) were assayed using sera from patients with Lyme disease with return to health (RTH) (n=70), post-treatment Lyme disease (n=58), COVID-19 RTH (n=47) and post-acute symptoms of COVID-19 (n=22). The post-Lyme questionnaire of symptoms (PLQS) was used to determine symptom burden after Lyme disease. RESULTS: There was no statistically significant difference in autoantibody prevalence across the four groups (p=0.746). A total of 21 different antibodies were found in the Lyme cohorts and 8 different antibodies in the COVID-19 cohorts. The prevalence of scleroderma-associated antibodies was higher after Lyme disease than COVID-19 (12.5% vs. 2.9%, p=0.026). There was no statistically significant difference in symptom burden based on antibody status. CONCLUSIONS: Several autoantibodies were found after Borrelia burgdorferi and SARS-CoV2 infection, although the prevalence was similar in those with persistent symptoms and those who returned to health. While our data show no difference in autoantibody prevalence across the four post-infectious states, we do not imply that autoantibodies are irrelevant in this setting. Rather, this study highlights the need for novel antibody discovery in larger cohorts of well-defined patient populations.

Association between anti-SSSCA1 antibodies and cancer in systemic sclerosis.

OBJECTIVE: To define the clinical phenotype of SSc patients with antibodies against Sjogren's syndrome (SS)/scleroderma autoantigen 1 (SSSCA1), and to examine the association between these antibodies and cancer in SSc patients. METHODS: We conducted a case-control study using data from 209 patients with SSc and cancer, and 205 SSc patients without cancer. All were randomly selected from the Johns Hopkins Scleroderma Center Research Registry. Antibodies against SSSCA1 were assayed by immunoprecipitation of 35S-methionine-labelled protein generated by in vitro transcription and translation. We performed logistic regression analysis to examine the relationship between anti-SSSCA1 antibodies and cancer. RESULTS: Among the 414 study patients, 31 (7%) were anti-SSSCA1 antibody positive. Antibody-positive patients were more likely to have severe RP, a lower minimum ejection fraction, a trend towards more severe heart involvement and a lower baseline diffusing capacity of the lungs for carbon monoxide percent predicted than anti-SSSCA1-negative patients. Patients with cancer were significantly more likely to be anti-SSSCA1 positive compared with those without cancer [22/209 (11%) vs 9/205 (4%), respectively; P = 0.018]. Among patients with cancer, there was a trend towards longer cancer-SSc interval in anti-SSSCA1-positive patients compared with anti-SSSCA1-negative patients. Patients with anti-SSSCA1 antibodies had an increased adjusted risk of cancer (odds ratio 2.46, 95% CI 1.06, 5.70) compared with anti-SSSCA1-negative patients. CONCLUSIONS: These data suggest anti-SSSCA1 antibody status may be of utility as a cancer biomarker in SSc. Anti-SSSCA1-positive patients with SSc may be more likely to have severe Raynaud's and cardiac involvement.

Cumulative disease damage and anti-PM/Scl antibodies are associated with a heavy burden of calcinosis in systemic sclerosis.

OBJECTIVES: Ectopic calcification (calcinosis) is a common complication of SSc, but a subset of SSc patients has a heavy burden of calcinosis. We examined whether there are unique risk factors for a heavy burden of calcinosis, as compared with a light burden or no calcinosis. METHODS: We reviewed the medical records of all patients in the Johns Hopkins Scleroderma Center Research Registry with calcinosis to quantify calcinosis burden using pre-specified definitions. We performed latent class analysis to identify SSc phenotypic classes. We used multinomial logistic regression to determine whether latent phenotypic classes and autoantibodies were independent risk factors for calcinosis burden. RESULTS: Of all patients, 29.4% (997/3388) had calcinosis, and 13.5% (130/963) of those with calcinosis had a heavy burden. The latent phenotypic class with predominantly diffuse skin disease and higher disease severity (characterized by pulmonary hypertension, interstitial lung disease, cardiomyopathy, severe RP, gastrointestinal involvement, renal crisis, myopathy and/or tendon friction rubs) was associated with an increased risk of both a heavy burden [odds ratio (OR) 6.92, 95% CI 3.66, 13.08; P < 0.001] and a light burden (OR 2.88, 95% CI 2.11, 3.95; P < 0.001) of calcinosis compared with the phenotypic class with predominantly limited skin disease. Autoantibodies to PM/Scl were strongly associated with a heavy burden of calcinosis (OR 17.31, 95% CI 7.72, 38.81; P < 0.001) and to a lesser degree a light burden of calcinosis (OR 3.59, 95% CI 1.84, 7.00; P < 0.001). CONCLUSIONS: Calcinosis burden is associated with cumulative SSc-related tissue damage. Independent of disease severity, autoantibodies to PM/Scl are also associated with a heavy burden of calcinosis.

Anti-MDA5-positive dermatomyositis and remission in a single referral centre population.

OBJECTIVES: To describe a single-centre North American adult cohort of anti-MDA5-positive dermatomyositis patients, with emphasis on drug-free long-term remission. METHODS: We conducted an observational retrospective cohort study of anti-MDA5-positive DM patients. All consented patients seen in the Johns Hopkins Myositis Centre from 2003-2020 with suspected muscle disease were routinely screened for myositis-specific autoantibodies. All sera were screened for anti-MDA5 autoantibodies by line blot; positives were verified by enzyme-linked immunoassay. Patients whose sera were anti-MDA5 positive by both assays (n=52) were followed longitudinally. If clinical status was unavailable, structured telephone interviews were conducted. Clinical remission was defined as being off all immunosuppression >1 year while remaining asymptomatic. RESULTS: 38/52 (73%) of the patients were women with a median age at disease-onset of 47 (IQR 40-54). Twenty-five of the patients (48%) were White, 16 (30%) were Black and 3 (6%) were Asian. Most patients (42/52, 80%) had interstitial lung disease, defined by inflammatory or fibrotic changes on high resolution computed tomography (HRCT). 18/52 (35%) of patients required pulse-dose methylprednisolone, 4/52 (8%) experienced spontaneous pneumothorax/pneumomediastinum, 6/52 (12%) required intubation, and 5/52 (10%) died. Over longitudinal follow-up (median 3.5 years), 9 (18%) patients achieved clinical remission. The median time from symptom onset to clinical remission was 4 years, and the median duration of sustained remission was 3.5 years (range 1.4-7.8). No demographic or disease characteristics were significantly associated with remission. CONCLUSIONS: In this single centre, tertiary referral population of anti-MDA5-positive dermatomyositis, ~20% of patients experienced long-term drug-free remission after a median disease duration of 4 years. No clinical or biologic factors were associated with clinical remission.

Granzyme B Induces IRF-3 Phosphorylation through a Perforin-Independent Proteolysis-Dependent Signaling Cascade without Inducing Cell Death.

Granzyme B (GrB) is an immune protease implicated in the pathogenesis of several human diseases. In the current model of GrB activity, perforin determines whether the downstream actions of GrB occur intracellularly or extracellularly, producing apoptotic cytotoxicity or nonapoptotic effects, respectively. In the current study, we demonstrate the existence of a broad range of GrB-dependent signaling activities that 1) do not require perforin, 2) occur intracellularly, and 3) for which cell death is not the dominant outcome. In the absence of perforin, we show that GrB enzymatic activity still induces substoichiometric activation of caspases, which through nonlethal DNA damage response signals then leads to activity-associated phosphorylation of IFN regulatory factor-3. These findings illustrate an unexpected potential interface between GrB and innate immunity separate from the traditional role of GrB in perforin-dependent GrB-mediated apoptosis that could have mechanistic implications for human disease.

Autoantibodies targeting telomere-associated proteins in systemic sclerosis.

OBJECTIVES: Systemic sclerosis (SSc) is an autoimmune fibrotic disease affecting multiple tissues including the lung. A subset of patients with SSc with lung disease exhibit short telomeres in circulating lymphocytes, but the mechanisms underlying this observation are unclear. METHODS: Sera from the Johns Hopkins and University of California, San Francisco (UCSF) Scleroderma Centers were screened for autoantibodies targeting telomerase and the shelterin proteins using immunoprecipitation and ELISA. We determined the relationship between autoantibodies targeting the shelterin protein TERF1 and telomere length in peripheral leucocytes measured by qPCR and flow cytometry and fluorescent in situ hybridisation (Flow-FISH). We also explored clinical associations of these autoantibodies. RESULTS: In a subset of patients with SSc, we identified autoantibodies targeting telomerase and the shelterin proteins that were rarely present in rheumatoid arthritis, myositis and healthy controls. TERF1 autoantibodies were present in 40/442 (9.0%) patients with SSc and were associated with severe lung disease (OR 2.4, p=0.04, Fisher's exact test) and short lymphocyte telomere length. 6/6 (100%) patients with TERF1 autoantibodies in the Hopkins cohort and 14/18 (78%) patients in the UCSF cohort had a shorter telomere length in lymphocytes or leukocytes, respectively, relative to the expected age-adjusted telomere length. TERF1 autoantibodies were present in 11/152 (7.2%) patients with idiopathic pulmonary fibrosis (IPF), a fibrotic lung disease believed to be mediated by telomere dysfunction. CONCLUSIONS: Autoantibodies targeting telomere-associated proteins in a subset of patients with SSc are associated with short lymphocyte telomere length and lung disease. The specificity of these autoantibodies for SSc and IPF suggests that telomere dysfunction may have a distinct role in the pathogenesis of SSc and pulmonary fibrosis.

A Bayesian approach to restricted latent class models for scientifically structured clustering of multivariate binary outcomes.

This paper presents a model-based method for clustering multivariate binary observations that incorporates constraints consistent with the scientific context. The approach is motivated by the precision medicine problem of identifying autoimmune disease patient subsets or classes who may require different treatments. We start with a family of restricted latent class models or RLCMs. However, in the motivating example and many others like it, the unknown number of classes and the definition of classes using binary states are among the targets of inference. We use a Bayesian approach to RLCMs in order to use informative prior assumptions on the number and definitions of latent classes to be consistent with scientific knowledge so that the posterior distribution tends to concentrate on smaller numbers of clusters and sparser binary patterns. The paper derives a posterior sampling algorithm based on Markov chain Monte Carlo with split-merge updates to efficiently explore the space of clustering allocations. Through simulations under the assumed model and realistic deviations from it, we demonstrate greater interpretability of results and superior finite-sample clustering performance for our method compared to common alternatives. The methods are illustrated with an analysis of protein data to detect clusters representing autoantibody classes among scleroderma patients.

Estimating autoantibody signatures to detect autoimmune disease patient subsets.

Autoimmune diseases are characterized by highly specific immune responses against molecules in self-tissues. Different autoimmune diseases are characterized by distinct immune responses, making autoantibodies useful for diagnosis and prediction. In many diseases, the targets of autoantibodies are incompletely defined. Although the technologies for autoantibody discovery have advanced dramatically over the past decade, each of these techniques generates hundreds of possibilities, which are onerous and expensive to validate. We set out to establish a method to greatly simplify autoantibody discovery, using a pre-filtering step to define subgroups with similar specificities based on migration of radiolabeled, immunoprecipitated proteins on sodium dodecyl sulfate (SDS) gels and autoradiography [Gel Electrophoresis and band detection on Autoradiograms (GEA)]. Human recognition of patterns is not optimal when the patterns are complex or scattered across many samples. Multiple sources of errors-including irrelevant intensity differences and warping of gels-have challenged automation of pattern discovery from autoradiograms.In this article, we address these limitations using a Bayesian hierarchical model with shrinkage priors for pattern alignment and spatial dewarping. The Bayesian model combines information from multiple gel sets and corrects spatial warping for coherent estimation of autoantibody signatures defined by presence or absence of a grid of landmark proteins. We show the pre-processing creates more clearly separated clusters and improves the accuracy of autoantibody subset detection via hierarchical clustering. Finally, we demonstrate the utility of the proposed methods with GEA data from scleroderma patients.

Distinct dermatomyositis populations are detected with different autoantibody assay platforms.

OBJECTIVES: To compare autoantibody-defined dermatomyositis sub-populations using immunoprecipitation-based assays, a commercially available line immunoblot assay and alternate commercial ELISA assays. METHODS: Banked plasma from 261 carefully phenotyped dermatomyositis patients was studied. Immunoprecipitation-based assays were used to detect antibodies against Mi2, TIF1-γ MDA5, NXP2, SAE1 and PM-Scl, while anti-Jo1 antibodies were assayed using ELISA. These data were compared with that obtained using a commercial line immunoblot, and, additionally, for Mi2, TIF1-γ, MDA5, commercially available ELISA kits. Test agreement was measured using Cohen's kappa statistic, and phenotypic differences between differentially identified groups are described. RESULTS: Line immunoblot, immunoprecipitation, and ELISA detected increasingly larger nested pools of anti-TIF1-γ samples, with increasing frequency of concurrent anti-Mi2 reactivity and decreasing incidence of malignancy. Line immunoblot and immunoprecipitation showed fair concordance for identifying anti-NXP2 antibodies (Cohen's kappa=0.71) but very good agreement for identifying antibodies against Mi2, MDA5, and SAE1 (Cohen's κ=0.9, 0.94, 0.88, respectively). Anti-PM-Scl results showed moderate agreement (Cohen's κ=0.48) between immunoblot and immunoprecipitation. CONCLUSIONS: Our results demonstrate that for some specificities, especially anti-TIF1-γ, antibody results obtained using different assay platforms vary, and identify significantly different patient populations. These findings highlight the need for standard adoption of carefully validated platforms to detect dermatomyositis autoantibodies.

Systematic autoantigen analysis identifies a distinct subtype of scleroderma with coincident cancer.

Scleroderma is a chronic autoimmune rheumatic disease associated with widespread tissue fibrosis and vasculopathy. Approximately two-thirds of all patients with scleroderma present with three dominant autoantibody subsets. Here, we used a pair of complementary high-throughput methods for antibody epitope discovery to examine patients with scleroderma with or without known autoantibody specificities. We identified a specificity for the minor spliceosome complex containing RNA Binding Region (RNP1, RNA recognition motif) Containing 3 (RNPC3) that is found in patients with scleroderma without known specificities and is absent in unrelated autoimmune diseases. We found strong evidence for both intra- and intermolecular epitope spreading in patients with RNA polymerase III (POLR3) and the minor spliceosome specificities. Our results demonstrate the utility of these technologies in rapidly identifying antibodies that can serve as biomarkers of disease subsets in the evolving precision medicine era.

An update on autoantibodies in scleroderma.

PURPOSE OF REVIEW: New research continues to provide important insights into the utility of antibody specificities. This review provides an update of recent findings, and the important insights they provide into disease mechanism. RECENT FINDINGS: A growing number of autoantibodies have been discovered in scleroderma patients with unique clinical associations. A subgroup of these antibodies may have functional consequences and contribute to disease pathogenesis, driving the vascular and fibrotic phenotype. Recent research into the relationship between malignancy and scleroderma onset provides important new insights into disease mechanism, and highlights the utility of autoantibodies as unique research probes. SUMMARY: Continued advances in the study of scleroderma antibody specificities has led to important insights into disease pathogenesis and clinical subgrouping. These advances include newly described specificities, functional antibodies and an emerging understanding of the cancer-scleroderma relationship.

Autoantibodies and scleroderma phenotype define subgroups at high-risk and low-risk for cancer.

OBJECTIVES: Recent studies demonstrate autoantibodies are powerful tools to interrogate molecular events linking cancer and the development of autoimmunity in scleroderma. Investigating cancer risk in these biologically relevant subsets may provide an opportunity to develop personalised cancer screening guidelines. In this study, we examined cancer risk in distinct serologic and phenotypic scleroderma subsets and compared estimates with the general population. METHODS: Patients in the Johns Hopkins Scleroderma Center observational cohort were studied. Overall and site-specific cancer incidence was calculated in distinct autoantibody and scleroderma phenotypic subsets, and compared with the Surveillance, Epidemiology and End Results registry, a representative sample of the US population. RESULTS: 2383 patients with scleroderma contributing 37 686 person-years were studied. 205 patients (8.6%) had a diagnosis of cancer. Within 3 years of scleroderma onset, cancer risk was increased in patients with RNA polymerase III autoantibodies (antipol; standardised incidence ratio (SIR) 2.84, 95% CI 1.89 to 4.10) and those lacking centromere, topoisomerase-1 and pol antibodies (SIR 1.83, 95% CI 1.10 to 2.86). Among antipol-positive patients, cancer-specific risk may vary by scleroderma subtype; those with diffuse scleroderma had an increased breast cancer risk, whereas those with limited scleroderma had high lung cancer risk. In contrast, patients with anticentromere antibodies had a lower risk of cancer during follow-up (SIR 0.59, 95% CI 0.44 to 0.76). CONCLUSIONS: Autoantibody specificity and disease subtype are biologically meaningful filters that may inform cancer risk stratification in patients with scleroderma. Future research testing the value of targeted cancer screening strategies in patients with scleroderma is needed.

More severe disease and slower recovery in younger patients with anti-3-hydroxy-3-methylglutaryl-coenzyme A reductase-associated autoimmune myopathy.

Objective: To study disease severity and response to therapy in a large cohort of patients with anti-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR)-associated myositis. Methods: Muscle strength, creatine kinase levels and treatments were assessed in anti-HMGCR-positive patients at each clinical visit. Univariate and multivariate analyses were used to analyse the influence of clinical characteristics on strength and the change in strength over time. Whole exome sequencing was performed in a subset of patients. Results: . Among 50 patients followed for ⩾2 years, only 22 (44%) reached full strength with immunosuppressive therapy; even among those with full strength, 55% continued to have CK levels in excess of 500 IU/l and only three could be tapered off immunosuppressive therapy. Both univariate and multivariate analysis showed that patients who were older at disease onset were stronger at all time points (P < 0.001) and improved faster (P < 0.008) than younger patients; a history of statin exposure was not independently associated with the improvement rate. Younger patients were more likely to have refractory disease (P = 0.02) than older patients. Among eight refractory patients with DNA available for testing, whole exome sequencing did not reveal pathogenic mutations in known dystrophy genes. The risk of cancer was not increased in anti-HMGCR myositis patients compared with the general population. Conclusions: Anti-HMGCR myositis is usually a chronic disease requiring long-term immunosuppression. Although younger patients had more severe disease and a worse prognosis than older patients, they did not have evidence of a known co-existing muscular dystrophy to explain their persistent, and sometimes progressive, muscle weakness.

Evaluation of cancer-associated myositis and scleroderma autoantibodies in breast cancer patients without rheumatic disease.

OBJECTIVES: Systemic sclerosis (scleroderma) and dermatomyositis are two prototypic autoimmune diseases that are strongly associated with malignancy. While specific autoantibodies in these diseases are markers of an increased risk of cancer at scleroderma and dermatomyositis onset, it is not known whether these autoantibodies are biomarkers of cancer risk in patients without rheumatic disease. METHODS: In a matched case-control study of women without rheumatic disease, identified from a familial breast cancer cohort, 50 breast cancer cases and 50 controls were assayed for 3 autoantibodies that are known markers of cancer-associated scleroderma and dermatomyositis: anti-RNA polymerase III, anti-NXP2, and anti-TIF1γ. RESULTS: No subject had moderate or strong autoantibody positivity. Eleven women were borderline positive for at least one autoantibody. The prevalence of borderline autoantibody positivity did not differ between cases and controls. CONCLUSIONS: Our results suggest that scleroderma and dermatomyositis autoantibodies are cancer biomarkers only in patients with clinical manifestations of specific rheumatic diseases and are unlikely to improve risk stratification for cancer in the general population. However, prospective studies are needed to examine whether scleroderma and dermatomyositis autoantibodies are markers of malignancy in other cancer types.

PUF60: a prominent new target of the autoimmune response in dermatomyositis and Sjögren's syndrome.

OBJECTIVES: Autoantibodies are used clinically to phenotype and subset patients with autoimmune rheumatic diseases. We detected a novel 60 kDa autoantibody specificity by immunoblotting using a dermatomyositis (DM) patient's serum. Our objective was to identify the targeted autoantigen and to evaluate disease specificity and clinical significance of this new autoantibody. METHODS: A new 60 kDa specificity was detected by immunoblotting HeLa cell lysates. The targeted autoantigen was identified as poly(U)-binding-splicing factor 60 kDa (PUF60) using (i) a human protein array and (ii) two-dimensional gel electrophoresis and liquid chromatography tandem mass spectrometry peptide sequencing. Anti-PUF60 antibodies were assayed by ELISA using sera from patients with primary Sjögren's syndrome (SS; n=84), systemic lupus erythematosus (SLE; n=71), DM (n=267), polymyositis (n=45), inclusion body myositis (n=45) and healthy controls (n=38). RESULTS: PUF60 was identified as a new autoantigen. Anti-PUF60 antibodies were present in 25/84 (30%) patients with SS, 6/71 (8.5%) patients with SLE and 2/38 (5.0%) control subjects (SS vs controls, p=0.002; SLE vs controls, p=0.711). Anti-PUF60 antibodies were present in 48/267 (18.0%) patients with DM versus 4/45 (8.9%) and 5/45 (11.1%) patients with inclusion body myositis and polymyositis, respectively. The antibody was significantly associated with anti-Ro52 antibodies, rheumatoid factor and hyperglobulinemia in the patients with primary SS. In patients with DM, the antibody was associated with anti-transcription intermediary factor 1 gamma seropositivity and Caucasian race. CONCLUSIONS: PUF60 represents a novel autoantigen in patients with SS and DM. PUF60 antibodies are associated with distinct clinical features and different immune responses in different diseases.

Cancer and scleroderma: a paraneoplastic disease with implications for malignancy screening.

PURPOSE OF REVIEW: Recent data suggest a paraneoplastic mechanism of scleroderma pathogenesis in unique subsets of scleroderma patients. In this article, we review these data, explore potential links between cancer and scleroderma, and propose an approach to malignancy screening in scleroderma. RECENT FINDINGS: Emerging data have demonstrated that patients with scleroderma and RNA polymerase III autoantibodies have a significantly increased risk of cancer within a few years of scleroderma onset. Genetic alterations in the gene encoding RNA polymerase III (POLR3A) have been identified, and patients with somatic mutations in POLR3A have evidence of mutation specific T-cell immune responses with generation of cross-reactive RNA polymerase III autoantibodies. These data strongly suggest that scleroderma is a by-product of antitumor immune responses in some patients. Additional epidemiologic data demonstrate that patients developing scleroderma at older ages may also have a short cancer-scleroderma interval, suggestive of paraneoplastic disease. SUMMARY: Scleroderma may be a paraneoplastic disease in unique patient subsets. Aggressive malignancy screening in these patients may aid in early cancer detection. Further study is required to determine whether cancer therapy could improve scleroderma outcomes in this patient population.