Anti-Ku antibodies: Clinical, genetic and diagnostic insights

Recognition of Idiopathic Inflammatory Myopathies Underlying Interstitial Lung Diseases

Interstitial Lung Disease (ILD) is one of the most common causes of mortality in idiopathic Inflammatory Myopathies (IIM). Despite these conditions being commonly associated with proximal weakness, skin rashes and arthritis, ILD can be the first or the sole clinical feature in up to 60% of patients, potentially leading to incorrect diagnosis. The early recognition of an underlying IIM in ILD patients can allow for prompt treatment, which could potentially stabilize or even improve the lung disease, also avoiding the development of other clinical features associated with the condition. The objective of this review is to describe the clinical, serological and radiological features associated with IIM-ILD, mainly focusing on dermatomyositis and antisynthetase syndrome.

Interstitial Lung Disease Associated with Anti-Ku Antibodies: A Case Series of 19 Patients

Background: Antibodies against Ku have been described in patients with various connective tissue diseases. The objective of this study was to describe the clinical, functional, and imaging characteristics of interstitial lung disease in patients with anti-Ku antibodies. Methods: This single-center, retrospective observational study was conducted at a tertiary referral institution. Patients with positive anti-Ku antibodies and interstitial lung disease identified between 2007 and 2022 were included. Clinical, immunological, functional, and imaging data were systematically reviewed. Results: Nineteen patients (ten females) with a mean age of 59 ± 12.6 years were included. The most frequent associated diagnosis was systemic sclerosis (42%), followed by rheumatoid arthritis (26%), Sjögren syndrome, undifferentiated connective tissue disease, and overlap between systemic sclerosis and idiopathic inflammatory myopathy (scleromyositis). Imaging revealed frequent septal and intralobular reticulations and ground-glass opacities, with nonspecific interstitial pneumonia as the predominant pattern (53%). The mean forced vital capacity was 82% ± 26 of the predicted value, and the mean diffusing capacity for carbon monoxide was 55% ± 21. Over the first year of follow-up, the mean annual forced vital capacity decline was 140 mL/year (range: 0-1610 mL/year). The overall survival rate was 82% at 5 years and 67% at 10 years. Conclusions: Most patients with interstitial lung disease and anti-Ku antibodies presented with dyspnea, a mild-to-moderate restrictive ventilatory pattern, and reduced diffusing capacity for carbon monoxide. The CT pattern was heterogeneous but was consistent with nonspecific interstitial pneumonia in half of the patients.

Not Just Myocarditis: Mixed Connective Tissue Disease (MCTD) and Overlap Myositis With Anti-Ku Positivity in a Young Male With Shortness of Breath

Mixed connective tissue disease (MCTD) is an autoimmune disorder characterized by high levels of anti-U1 ribonucleoprotein (RNP) antibodies and overlapping clinical features of autoimmune diseases, such as systemic lupus erythematosus (SLE), systemic sclerosis (SSc), and polymyositis (PM). Anti-Ku antibodies have been associated with overlap syndromes, which can present with symptoms such as Raynaud's phenomenon, arthritis, and myositis.  A 19-year-old male athlete presented with myositis, notable for cardiac involvement. Diagnostic testing revealed elevated anti-RNP and anti-Ku antibodies, and a muscle biopsy indicated scleromyositis/overlap myositis. The patient was treated with high-dose corticosteroids, intravenous immunoglobulin (IVIG), rituximab, and mycophenolate mofetil, which led to significant improvement in muscle strength and cardiac function. This case highlights the diagnostic complexity of MCTD when associated with positive anti-Ku antibodies, overlap syndromes, and cardiac involvement. Successful management emphasizes the importance of a tailored, multi-modal therapeutic approach.

Anti-Ku + myositis: an acquired inflammatory protein-aggregate myopathy

Myositis with anti-Ku-autoantibodies is a rare inflammatory myopathy associated with various connective tissue diseases. Histopathological studies have identified inflammatory and necrotizing aspects, but a precise morphological analysis and pathomechanistic disease model are lacking. We therefore aimed to carry out an in-depth morpho-molecular analysis to uncover possible pathomechanisms. Muscle biopsy specimens from 26 patients with anti-Ku-antibodies and unequivocal myositis were analyzed by immunohistochemistry, immunofluorescence, transcriptomics, and proteomics and compared to biopsy specimens of non-disease controls, immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). Clinical findings and laboratory parameters were evaluated retrospectively and correlated with morphological and molecular features. Patients were mainly female (92%) with a median age of 56.5 years. Isolated myositis and overlap with systemic sclerosis were reported in 31%, respectively. Isolated myositis presented with higher creatine kinase levels and cardiac involvement (83%), whereas systemic sclerosis-overlap patients often had interstitial lung disease (57%). Histopathology showed a wide spectrum from mild to pronounced myositis with diffuse sarcolemmal MHC-class I (100%) and -II (69%) immunoreactivity, myofiber necrosis (88%), endomysial inflammation (85%), thickened capillaries (84%), and vacuoles (60%). Conspicuous sarcoplasmic protein aggregates were p62, BAG3, myotilin, or immunoproteasomal beta5i-positive. Proteomic and transcriptomic analysis identified prominent up-regulation of autophagy, proteasome, and hnRNP-related cell stress. To conclude, Ku + myositis is morphologically characterized by myofiber necrosis, MHC-class I and II positivity, variable endomysial inflammation, and distinct protein aggregation varying from IBM and IMNM, and it can be placed in the spectrum of scleromyositis and overlap myositis. It features characteristic sarcoplasmic protein aggregation on an acquired basis being functionally associated with altered chaperone, proteasome, and autophagy function indicating that Ku + myositis exhibit aspects of an acquired inflammatory protein-aggregate myopathy.

Advanced Autoantibody Testing in Systemic Sclerosis

Systemic sclerosis is a systemic autoimmune rheumatic disease characterized by immune abnormalities, leading to vasculopathy and fibrosis. Autoantibody testing has become an increasingly important part of diagnosis and prognostication. Clinicians have been limited to antinuclear antibody (ANA), antitopoisomerase I (also known as anti-Scl-70) antibody, and anticentromere antibody testing. Many clinicians now have improved access to an expanded profile of autoantibody testing. In this narrative review article, we review the epidemiology, clinical associations, and prognostic value of advanced autoantibody testing in people with systemic sclerosis.

Scleromyositis: A distinct novel entity within the systemic sclerosis and autoimmune myositis spectrum. Implications for care and pathogenesis

Systemic sclerosis and autoimmune myositis are both associated with decreased quality of life and increased mortality. Their prognosis and management largely depend on the disease subgroups. Indeed, systemic sclerosis is a heterogeneous disease, the two predominant forms of the disease being limited and diffuse scleroderma. Autoimmune myositis is also a heterogeneous group of myopathies that classically encompass necrotizing myopathy, antisynthetase syndrome, dermatomyositis and inclusion body myositis. Recent data revealed that an additional disease subset, denominated "scleromyositis", should be recognized within both the systemic sclerosis and the autoimmune myositis spectrum. We performed an in-depth review of the literature with the aim of better delineating scleromyositis. Our review highlights that this concept is supported by recent clinical, serological and histopathological findings that have important implications for patient management and understanding of the disease pathophysiology. As compared with other subsets of systemic sclerosis and autoimmune myositis, scleromyositis patients can present with a characteristic pattern of muscle involvement (i.e. distribution of muscle weakness) along with multisystemic involvement, and some of these extra-muscular complications are associated with poor prognosis. Several autoantibodies have been specifically associated with scleromyositis, but they are not currently integrated in diagnostic and classification criteria for systemic sclerosis and autoimmune myositis. Finally, striking vasculopathic lesions at muscle biopsy have been shown to be hallmarks of scleromyositis, providing a strong anatomopathological substratum for the concept of scleromyositis. These findings bring new insights into the pathogenesis of scleromyositis and help to diagnose this condition, in patients with subtle SSc features and/or no autoantibodies (i.e. "seronegative" scleromyositis). No guidelines are available for the management of these patients, but recent data are showing the way towards a new therapeutic approach dedicated to these patients.

Autoantibodies and Clinical Correlations in Polish Systemic Sclerosis Patients: A Cross-Sectional Study

We evaluated the prevalence of systemic sclerosis (SSc)-related autoantibodies and their clinical significance and compared the sensitivity of two line immunoblot assays on a prospective study group of 96 Polish SSc patients (ACR-EULAR 2013 criteria) whose sera were assessed by indirect immunofluorescence (HEp-2 and monkey liver) and line immunoblot assays: ANA Profile 3 and Systemic Sclerosis Profile by EUROIMMUN (Lübeck, Germany). Organ involvement was evaluated according to the EUSTAR Minimal Essential Data Set. The following autoantibodies’ prevalence was found: Scl-70 (36%), Ro-52 (28%), CENP-B (22%), CENP-A (20%), PM-Scl-75 (20%), PM-Scl-100 (14%), fibrillarin (7%), Th/To (7%), RNA polymerase III 11 kDa (5%), RNA polymerase III 155 kDa (3%), PDGFR (3%), NOR-90 (2%), and Ku (1%). Significant associations between the autoantibodies’ presence and organ involvement were found: ATA (dcSSc > lcSSc, less prevalent muscle weakness), Ro-52 (gangrene, DLCO < 60), CENP-B and A (lcSSc > dcSSc, normal CK), CENP-B (rarer digital ulcers and joint contractures), PM-Scl-100 and 75 (PM/SSc overlap, CK increase, muscle weakness, muscle atrophy), PM-Scl-100 (dcSSc unlikely), PM-Scl-75 (lung fibrosis), fibrillarin (muscle atrophy, proteinuria, conduction blocks, palpitations), Th/To (proteinuria, arthritis, muscle weakness, and rarer esophageal symptoms), RNA Polymerase III 11 kDa (arterial hypertension, renal crisis), RNA polymerase III 155 kDa (renal crisis), and PDGFR (dcSSc, tendon friction rubs). Additionally, the Systemic Sclerosis Profile was significantly more sensitive in detecting SSc-related autoantibodies than ANA Profile 3 (p = 0.002). In conclusion, individual autoantibodies associated with specific characteristics of SSc.

Diagnostic accuracy and predictive value of autoantibody profiles in patients with systemic sclerosis: a single-center study

OBJECTIVE

To determine diagnostic accuracy and evaluate the predictive value of autoantibody profiles in patients with systemic sclerosis (SSc).

METHODS

A total of 140 patients with SSc (125 female, mean age 54.2 ± 14.2 years) were analyzed by a multiplex line immunoassay (Euroimmun) for autoantibodies against 12 SSc-related antigens. Associations between the presence of the autoantibodies and demographic clinical manifestations of patients with SSc were investigated.

RESULTS

The sensitivity and specificity of this assay were as follows: 32.9% and 99.4% for anti-Scl-70, 29.3% and 88.9% for anti-CENP A, 28.6% and 87.8% for anti-CENP B, 7.1% and 97.8% for anti-RP11, 5.7% and 100% for anti-RP155, 2.9% and 99.4% for anti-NOR 90, 2.9% and 98.9% for anti-Th/To, 1.4% and 96.7% for anti-PM-Scl-100, 5.0% and 98.3% for anti-PM-Scl-75, and 2.9% and 97.2% for anti-Ku, respectively. Anti-Scl-70 was significantly associated with sine scleroderma (P = 0.003), digital ulcers (P = 0.047), and Raynaud's phenomenon as the first clinical manifestation of onset (P = 0.017). SSc-ILD was more common in patients with anti-Scl-70 (P = 0.029) and less frequent in patients with anti-CENP A (P < 0.001) and anti-CENP B (P < 0.001). There was a significant association between PAH with anti-CENP A (P = 0.008) and anti-CENP B (P = 0.025). Renal involvement was significantly related to anti-NOR90 (P = 0.026) and anti-Th/To (P = 0.026).

CONCLUSIONS

This study confirmed the important role of autoantibodies in accurately diagnosing SSc. The autoimmune profile of patients with SSc was related to specific disease manifestations. Key Points • Autoantibody profiles were useful for diagnosing SSc and predicting clinical features of patients.

The manifestation of myositis in tick-borne encephalitis as a prophet of severe disease course: a rare case report

Tick-borne encephalitis (TBE) is one of the most serious neurological tick-transmitted diseases. The initial phase usually occurs with non-specific symptoms such as fever, headache, and muscular pain. The clinical spectrum of the second phase of the disease typically ranges from mild meningitis to severe meningoencephalitis. Our case demonstrates a rare clinical case of acute myositis as manifestation of TBE virus infection. A 33-year-old female was admitted to the Rheumatology centre with a fever followed by proximal muscle pain and weakness. Despite the tick bite history and marginally positive anti-TBE virus IgM titre, the patient did not present any neurological symptoms. Laboratory test results showed elevated creatine kinase (CK) and myoglobin. Other infections, idiopathic inflammatory myopathies, were excluded. TBE virus infection was confirmed by rapid seroconversion of specific IgG class antibodies in serum. The second phase of the disease was followed by neurological symptoms and a repeated increase of CK and myoglobin. We suggest that in the case of acute myositis of unknown cause and the history of thick bite, TBE virus infection should be considered and creatine kinase might be considered as a laboratory marker of disease activity that correlates with the severity of the disease.

Myositis Antibodies and Interstitial Lung Disease

BACKGROUND

Interstitial lung disease (ILD) comprises a heterogeneous group of inflammatory and fibrotic conditions, often resulting in progressive lung function decline and increased mortality. Connective tissue disease (CTD) should be considered in all patients with ILD, as distinguishing between CTD-ILD and other forms of fibrotic lung disease has important therapeutic and prognostic implications. The idiopathic inflammatory myopathies (IIM) represent a CTD subtype of growing interest to ILD experts. The expansion and availability of myositis-specific and myositis-associated antibody testing has allowed for improved disease detection and characterization.

CONTENT

In this review, we highlight the relationship between myositis antibodies and ILD. Select forms of IIM, such as the antisynthetase syndrome and clinically amyopathic dermatomyositis can present with rapidly progressive ILD, warranting timely disease diagnosis and management. Disease phenotypes, prevalence, laboratory testing, prognosis, and management strategies are described according to select myositis antibodies.

SUMMARY

Myositis antibodies provide valuable information for clinicians managing patients with ILD. This review aims to increase awareness of their role in disease detection, pathophysiology, and possibly therapeutics.

Anti-Ku Antibody-Positive Myositis Presenting as a Wide Range of Axial Myopathies and Myocarditis: A Case Report and Review of the Literature

Idiopathic inflammatory myopathies (IIMs) are autoimmune diseases predominantly affecting proximal muscles; paraspinal muscle involvement is relatively rare. Because paraspinal myopathies do not always cause clinically-evident symptoms, the diagnosis of IIMs with axial myopathies can be challenging. Anti-Ku autoantibodies, initially reported in polymyositis/systemic sclerosis overlap syndrome, are myositis-associated antibodies (MAAs) observed in patients with a wide variety of connective tissue diseases (CTDs). Few reports have been published demonstrating predominant axial myopathy in IIM patients with anti-Ku antibodies. Herein, we investigated a previously healthy Japanese woman in her early 70s who presented with Raynaud's phenomenon, back pain, and exertional dyspnea. The creatine kinase (CK) was elevated and antinuclear antibody staining was positive, but myositis-specific antibodies (MSAs) were negative. Magnetic resonance imaging (MRI) revealed myocarditis and a wide range of axial muscle inflammation, including bilateral thoracolumbar paraspinal, infraspinatus, and trapezius muscles. The muscle biopsy was consistent with IIM. In addition, anti-Ku antibody was positive. Administration of prednisolone and tacrolimus quickly alleviated the symptoms and the CK level returned to normal. The diagnosis of IIM was arduous in this case because she did not present with camptocormia, muscle weakness involving the proximal limbs was not apparent, and MSAs were negative. Whether axial myopathy and myocarditis are more prevalent in IIM patients with than without anti-Ku antibodies is uncertain. Clinicians should suspect axial myopathy and MAAs, such as anti-Ku antibodies, especially in patients in whom muscle weakness of the proximal limbs is not noticeable.

Biomarker und Histologie bei idiopathischen inflammatorischen Myopathien

Die idiopathischen inflammatorischen Myopathien (IIM) sind eine Gruppe entzündlicher Muskelerkrankungen für deren Diagnosestellung, Verlaufsbeurteilung, Prognoseabschätzung und Risikostratifizierung Biomarker eine jeweils essentielle Rolle spielen. Biomarker in diesem Kontext können sowohl „herkömmliche“ serologische Marker wie Muskelenzyme oder Autoantikörper, histologische Marker wie entitätsspezifische inflammatorische Muster, aber auch genomische und genetische Marker sein. Der vorliegende Artikel gibt einen Überblick über bewährte und innovative Marker.

The Ku complex: recent advances and emerging roles outside of non-homologous end-joining

Since its discovery in 1981, the Ku complex has been extensively studied under multiple cellular contexts, with most work focusing on Ku in terms of its essential role in non-homologous end-joining (NHEJ). In this process, Ku is well-known as the DNA-binding subunit for DNA-PK, which is central to the NHEJ repair process. However, in addition to the extensive study of Ku's role in DNA repair, Ku has also been implicated in various other cellular processes including transcription, the DNA damage response, DNA replication, telomere maintenance, and has since been studied in multiple contexts, growing into a multidisciplinary point of research across various fields. Some advances have been driven by clarification of Ku's structure, including the original Ku crystal structure and the more recent Ku-DNA-PKcs crystallography, cryogenic electron microscopy (cryoEM) studies, and the identification of various post-translational modifications. Here, we focus on the advances made in understanding the Ku heterodimer outside of non-homologous end-joining, and across a variety of model organisms. We explore unique structural and functional aspects, detail Ku expression, conservation, and essentiality in different species, discuss the evidence for its involvement in a diverse range of cellular functions, highlight Ku protein interactions and recent work concerning Ku-binding motifs, and finally, we summarize the clinical Ku-related research to date.

Blood purification in two patients with clinically amyopathic dermatomyositis associated with interstitial lung disease with anti-melanoma differentiation-associated gene-5 antibody (MDA-5)

Patients of clinically amyopathic dermatomyositis associated with rapidly progressive interstitial pneumonia (CADM-RFIP) with positive anti-MDA5 antibody usually presents rapid deterioration and traditional therapy such as cyclophosphamide combined with high-dose prednisone pulse therapy shows no clear benefit at whiles. However, blood purification combined with traditional therapy works according to the literature. We herein report two CADM-RFIP patients administered with DNA immunoadsorption combined with traditional therapy and then reviewed the literature of blood purification in CADM-RFIP patients at home and abroad to date. We emphasize blood purification such as DNA immunoadsorption could apply in the early stage of CADM-RFIP, which can decrease inflammation and allow us more time to control the condition better.

Integrating the DNA damage and protein stress responses during cancer development and treatment

During evolution, cells have developed a wide spectrum of stress response modules to ensure homeostasis. The genome and proteome damage response pathways constitute the pillars of this interwoven 'defensive' network. Consequently, the deregulation of these pathways correlates with ageing and various pathophysiological states, including cancer. In the present review, we highlight: (1) the structure of the genome and proteome damage response pathways; (2) their functional crosstalk; and (3) the conditions under which they predispose to cancer. Within this context, we emphasize the role of oncogene-induced DNA damage as a driving force that shapes the cellular landscape for the emergence of the various hallmarks of cancer. We also discuss potential means to exploit key cancer-related alterations of the genome and proteome damage response pathways in order to develop novel efficient therapeutic modalities. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.

Two-Parametric Immunological Score Development for Assessing Renal Involvement and Disease Activity in Systemic Lupus Erythematosus

Objective

Anti-double-stranded (ds) DNA and anti-C1q autoantibodies are useful tools in the assessment of disease activity and nephritis in systemic lupus erythematosus (SLE) patients. This study aimed to explore the utility of these antibodies along with anti-Ku antibodies in an oligoparametric model approach for the assessment of disease activity and lupus nephritis.

Methods

Samples from 261 well-characterized SLE patients were tested using chemiluminescent immunoassays (CIA) for anti-dsDNA and anti-Ku antibodies as well as by anti-C1q antibody ELISA (Inova Diagnostics, USA). Of these SLE patients, 26.4% had lupus nephritis (LN) at the time of blood draw or had a history of LN, and modified SLE disease activity index-2K (SLEDAI) scores were used to assess disease activity.

Results

All three antibodies demonstrated higher prevalence and higher antibody levels in active versus inactive SLE patients and in LN versus non-LN patients. When oligoparametric analysis was performed, the likelihood of LN and patients with active disease increased with dual and triple positivity.

Conclusions

Anti-dsDNA and anti-C1q antibodies are useful tools to identify disease activity and/or renal involvement in SLE patients. In addition, the combination of those antibodies in a two-parametric score might improve the clinical utility of those markers.

The prevalence and clinical significance of anti-PUF60 antibodies in patients with idiopathic inflammatory myopathy

Autoantibodies against poly-U-binding factor 60 kDa protein (PUF60) have been reported in Caucasian dermatomyositis (DM) patients. However, their clinical significance in idiopathic inflammatory myopathy (IIM) remains to be fully clarified. Our objective was to analyze the prevalence and clinical significance of anti-PUF60 antibodies in a large cohort of Chinese IIM patients. In our study, 388 IIM patients, 301 disease controls, and 167 healthy controls (HCs) were involved. An enzyme-linked immunosorbent assay (ELISA) was developed to detect serum anti-PUF60 levels and was validated using immunoblotting methods. Unpaired Mann-Whitney U test and Spearman correlation analysis were used when appropriate. Anti-PUF60 antibodies were observed in IIM patients at a frequency of 10.6% (41/388). Subgrouping analysis revealed that the prevalence of anti-PUF60 antibodies was 10% in DM, 5.5% in polymyositis (PM), 10% in immune-mediated necrotizing myositis (IMNM), and 26.5% in myositis-overlap syndrome. Anti-PUF60 antibodies were also observed in systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), and Sjögren's syndrome (SS) patients at a positive rate of 17.3, 14.5, and 10.1% respectively. Intriguingly, anti-PUF60 antibodies were frequently observed in clinically amyopathic dermatomyositis (CADM) patients and DM patients without currently known myositis autoantibodies. Furthermore, DM patients with anti-PUF60 antibodies had higher prevalence of skin ulcerations. Moreover, longitudinal investigation in eight DM patients with anti-PUF60 antibodies revealed that the antibodies levels decreased with disease remission. Anti-PUF60 antibodies were nonspecific for myositis, since they could be detected in other rheumatic diseases. Further investigation of anti-PUF60 antibodies may reveal shared pathogenic pathways in systemic autoimmune disorders.

Bench to bedside review of myositis autoantibodies

Idiopathic inflammatory myopathies represent a heterogeneous group of autoimmune diseases with systemic involvement. Even though numerous specific autoantibodies have been recognized, they have not been included, with the only exception of anti-Jo-1, into the 2017 Classification Criteria, thus perpetuating a clinical-serologic gap. The lack of homogeneous grouping based on the antibody profile deeply impacts the diagnostic approach, therapeutic choices and prognostic stratification of these patients. This review is intended to highlight the comprehensive scenario regarding myositis-related autoantibodies, from the molecular characterization and biological significance to target antigens, from the detection tools, with a special focus on immunofluorescence patterns on HEp-2 cells, to their relative prevalence and ethnic diversity, from the clinical presentation to prognosis. If, on the one hand, a notable body of literature is present, on the other data are fragmented, retrospectively based and collected from small case series, so that they do not sufficiently support the decision-making process (i.e. therapeutic approach) into the clinics.

Disease-related autoantibody profile in patients with systemic sclerosis

BACKGROUND

Autoantibodies (autoAbs) help in diagnosis and predicting clinical phenotypes in systemic sclerosis (SSc).

AIM OF THE STUDY

To determine the clinical utility of 13 SSc-related autoAbs in SSc patients.

MATERIAL AND METHODS

A total of 131 consecutive patients with SSc (111 female, mean age 58.1 ± 14 years; 49 with diffused cutaneous SSc [dcSSc] and 82 with limited cutaneous SSc [lcSSc]) were analysed by a multiplex line immunoassay (Euroimmun) for autoantibodies (autoAbs) against 13 SSc-related antigens. A total of 22 patients with primary Raynaud phenomenon (RP), and 22 healthy controls were also analysed.

RESULTS

ANA by indirect immunofluorescence was present in 128 (97.7%) patients with SSc. Excluding anti-Ro52, 113 (89.3%) SSc patients were positive for at least one autoAb: anti-Topoisomerase I (anti-Topo) I abs in 54 (41.2%), anti-centromere proteins (anti-CENP) in 37 (28.2%, all reactive with centromere protein-A (CENPA) and centromere protein B (CENPB)), anti-RNA polymerase III(RP11) in 19 (14.5%), anti-RNA polymerase III(RP155) in 13 (9.9%), anti-fibrillarin in 4 (3.1%), anti-Ku in 6 (4.6%), anti-nucleolus-organizing region (anti-NOR90) in 8 (6.1%), anti-PM-Scl100 in 2 (1.5%), and anti-PM-Scl75 in 4 (3.1%). There was no immunoreactivity for Th/To or platelet-derived growth factor receptor (PDGFR). Overall, 102 (77.9%) SSc patients had autoAbs against Topo I, CENPA or CENPB, RP11 or RP155. Anti-Topo I abs were strongly associated with dcSSc, interstitial lung disease (ILD) (p < .001), pulmonary hypertension (PH) (p = .019) and ILD-PH (p = .003). Anti-CENPB abs were associated with lcSSc, and negatively associated with ILD. Anti-RP11 and anti-NOR90 abs were associated with male gender, and anti-NOR90 associated with ILD.

CONCLUSIONS

Anti-Topo I, anti-CENP, and anti-RNA pol III are the most prevalent autoAbs in SSc. Anti-Topo I and anti-NOR90 abs are associated with ILD and/or PAH.

In Vivo Chronic Stimulation Unveils Autoreactive Potential of Wiskott-Aldrich Syndrome Protein-Deficient B Cells

Wiskott–Aldrich syndrome (WAS) is a primary immunodeficiency caused by mutations in the gene encoding the hematopoietic-specific WAS protein (WASp). WAS is frequently associated with autoimmunity, indicating a critical role of WASp in maintenance of tolerance. The role of B cells in the induction of autoreactive immune responses in WAS has been investigated in several settings, but the mechanisms leading to the development of autoimmune manifestations have been difficult to evaluate in the mouse models of the disease that do not spontaneously develop autoimmunity. We performed an extensive characterization of Was^−/− mice that provided evidence of the potential alteration in B cell selection, because of the presence of autoantibodies against double-stranded DNA, platelets, and tissue antigens. To uncover the mechanisms leading to the activation of the potentially autoreactive B cells in Was^−/− mice, we performed in vivo chronic stimulations with toll-like receptors agonists (LPS and CpG) and apoptotic cells or infection with lymphocytic choriomeningitis virus. All treatments led to increased production of autoantibodies, increased proteinuria, and kidney tissue damage in Was^−/− mice. These findings demonstrate that a lower clearance of pathogens and/or self-antigens and the resulting chronic inflammatory state could cause B cell tolerance breakdown leading to autoimmunity in WAS.

Clinical and serological associations of autoantibodies to the Ku70/Ku80 heterodimer determined by a novel chemiluminescent immunoassay

BACKGROUND

Autoantibodies targeting Ku, an abundant nuclear protein with DNA helicase activity, have been reported in patients with systemic autoimmune rheumatic diseases. Little is known about the clinical associations of anti-Ku antibodies, especially when novel diagnostic technologies are used. The objective of the present study was to analyse the prevalence of anti-Ku antibodies in different medical conditions using a novel chemiluminescent immunoassay.

PATIENTS AND METHODS

Serum samples from adult patients with systemic lupus erythematosus (SLE, n=305), systemic sclerosis (SSc, n=70) and autoimmune myositis patients (AIM, n=109) were the primary focus of the study. Results were compared with disease controls (rheumatoid arthritis, RA, n=30; infectious diseases, n=17) and healthy individuals (n=167). In addition, samples submitted for routine autoantibody testing from patients referred to a rheumatology clinic (n=1078) were studied. All samples were tested for anti-Ku antibodies by QUANTA Flash Ku chemiluminescent immunoassay (research use only, Inova Diagnostics, San Diego, USA) using full length recombinant human Ku. SLE patient samples were also tested for other autoantibodies. Clinical data of anti-Ku antibody positive patients (high titres) were obtained by retrospective chart review.

RESULTS AND FINDINGS

In the disease cohorts, 30/305 (9.8%) SLE, 3/70 (4.3%) systemic sclerosis and 4/109 (3.7%) autoimmune myositis (AIM) patients were positive, respectively. The four positive AIM patients had an overlap myositis syndrome that included two patients with SLE. The three systemic sclerosis (SSc) positive samples had diagnoses of SSc/SLE overlap, diffuse cutaneous SSc, and early edematous phase SSc. In the control cohorts, 2/170 (1.2%) healthy individuals (all low titre), 0/30 (0.0%) (RA) and 0/17 (0.0%) infectious disease patients were positive. The area under the curve values were: 0.75 for SLE vs. controls, 0.68 for SSc vs. controls and 0.37 for AIM vs.

CONTROLS

In the rheumatology clinic referral cohort, 12/1078 (1.1%) were positive for anti-Ku antibodies, nine showing low and three high titres. The diagnoses of the three high positive anti-Ku positive patients were: probable SLE, mixed connective tissue disease (MCTD) and ANA positive RA.

CONCLUSION

Anti-Ku antibodies detected by chemiluminescent immunoassay are most prevalent in SLE. When found in AIM and SSc, they were associated with overlap syndrome and early SSc.

Single-specificity anti-Ku antibodies in an international cohort of 2140 systemic sclerosis subjects: clinical associations

Autoantibodies directed against the Ku autoantigen are present in systemic sclerosis (SSc) and have been associated with myositis overlap and interstitial lung disease (ILD). However, there is a paucity of data on the clinical correlates of anti-Ku antibodies in the absence of other SSc-specific antibodies. The aim of this study was to assess the clinical correlates of single-specificity anti-Ku in SSc.An international (Canada, Australia, USA, Mexico) cohort of 2140 SSc subjects was formed, demographic and clinical variables were harmonized, and sera were tested for anti-Ku using a line immunoassay. Associations between single-specificity anti-Ku antibodies (i.e., in isolation of other SSc-specific antibodies) and outcomes of interest, including myositis, ILD, and survival, were investigated.Twenty-four (1.1%) subjects had antibodies against Ku, and 13 (0.6%) had single-specificity anti-Ku antibodies. Subjects with single-specificity anti-Ku antibodies were more likely to have ILD (58% vs 34%), and to have increased creatine kinase levels (>3× normal) at baseline (11% vs 1%) and during follow-up (10% vs 2%). No difference in survival was noted in subjects with and without single-specificity anti-Ku antibodies.This is the largest cohort to date focusing on the prevalence and disease characteristics of single-specificity anti-Ku antibodies in subjects with SSc. These results need to be interpreted with caution in light of the small sample. International collaboration is key to understanding the clinical correlates of uncommon serological profiles in SSc.

Overlap connective tissue disease syndromes

Overlap Syndromes (OSs) have been defined as entities satisfying classification criteria of at least two connective tissue diseases (CTDs) occurring at the same or at different times in the same patient. CTDs include systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), systemic sclerosis (SSc), polymyositis/dermatomyositis (PDM), and Sjögren syndrome (SS). Every combination between these disorders has been reported. In some OS a specific autoantibody has been indentified, supporting the hypothesis that these syndromes are not a mere association of two or more CTD in the same patient, but a well defined clinical entity with specific clinical characteristics. As an example, anti-t-RNA synthetase syndrome is characterized by the presence of anti-t-RNA synthetase antibodies. Notably, clinical manifestations observed in OS may be different from those observed in the single CTD. The treatment of OS is mainly based on the use of corticosteroids and immunosuppressants. Biologic drugs, i.e. anti-TNFα or anti-CD20 monoclonal antibodies, have been recently introduced as alternative treatments in refractory cases. Moreover, there are some concerns with the use of anti-TNF agents in patients with systemic autoimmune diseases due to the risk of triggering disease exacerbations. In this paper the most frequent OS are described with a special focus on the specific immunologic and clinical aspects. Furthermore, some personal data on anti-t-RNA synthetase syndrome and rhupus syndrome are reported.

Primary biliary cirrhosis and the nuclear pore complex

Experimental models of autoimmune diseases have led to the conclusion that an immune response to nuclear antigens is a sentinel marker for loss of tolerance and potential tissue damage. Various proteins are targets of antinuclear antibodies in a variety of autoimmune diseases, ranging from systemic rheumatologic disorders to diseases affecting specific organs such as the liver. Autoantibodies against specific nuclear constituents have also been used as probes to understand the structure and the function of the targeted components and their relevance to disease pathogenesis. Approximately a quarter of patients with primary biliary cirrhosis (PBC) have antibodies targeting proteins of the nuclear pore complex (NPC), a multi-protein structure that mediates molecular transport across the nuclear envelope. Autoantibodies against the integral membrane glycoprotein gp210 and nucleoporin p62 appear to be highly specific for PBC, an autoimmune disease characterized by progressive destruction of intrahepatic biliary epithelial cells. This review discusses the diagnostic and clinical relevance of anti-NPC antibodies in PBC and the possibility that this autoimmune response may arise as a result of molecular mimicry.

Camptocormia as a clinical manifestation of polymyositis/systemic sclerosis overlap myositis associated with anti-Ku

Camptocormia, an abnormal truncal flexion posture that occurs while walking or standing, is usually caused by various hypokinetic movement disorders, mainly Parkinson disease. We describe the case of a man with subacute onset of camptocormia. Quadriceps muscle biopsy showed significant rhabdomyolysis, few isolated inflammatory cells and mild expression of type I MHC in few fibers, a pattern usually found in immune-mediated necrotizing myopathies. Myositis was associated with Raynaud's phenomenon, mild sclerodactyly, and anti-Ku antibodies leading to the diagnosis of polymyositis/systemic sclerosis overlap myositis. The posture showed modest improvement in response to treatment.

Serologic laboratory findings in malignancy

Autoantibodies are extremely promising diagnostic and prognostic biomarkers of cancer, and have the potential to promote early diagnosis and to make a large impact by improving patient outcome and decreasing mortality. Moreover, autoantibodies may be useful reagents in the identification of subjects at risk for cancer, bearing premalignant tissue changes. Great efforts are being made in many laboratories to validate diagnostic panels of autoantibodies with high sensitivity and specificity that could be useful in a clinical setting. It is likely that prospective studies of sufficiently large cohorts of patients and controls using high-throughput technology may allow the identification of biomarkers with diagnostic significance, and perhaps of discrete antigen phenotypes with clinical significance. The identification of TAAs may also be essential for the development of anticancer vaccines, because autoantibodies found in cancer sera target molecules involved in signal transduction, cell-cycle regulation, cell proliferation, and apoptosis, playing important roles in carcinogenesis. On this basis, molecular studies of antigenantibody systems in cancer promise to yield valuable information on the carcinogenic process. TAAs identified by serum antibodies in cancer sera can be natural immunogenic molecules, useful as targets for cancer immunotherapy. An important problem encountered in the practice of medicine is the identification of healthy individuals in the general population who unknowingly are at high risk of developing cancer. For the rheumatologist, a related problem is the identification of those patients with rheumatic diseases who are at high risk for developing a malignant process. These problems encountered in the fields of cancer and the rheumatic diseases can in the future be helped by new diagnostic instruments based on antibodies. The need for promoting the early diagnosis of cancer is a recognized major public health problem in need of significant research support for the validation of multiple promising but inconclusive studies, with the intention of producing diagnostic panels of autoantibodies in various types of cancers. Cancer developing in patients with rheumatic diseases is also an important problem requiring prospective longterm follow-up studies of patients with rheumatic diseases, particularly because some of the new biologic therapies seem to increase the cancer risk. It is possible that a panel of autoantibodies common to patients with cancer and the rheumatic diseases may prove to be of value in the identification of those patients with ADs at high risk for neoplasms.

Interstitial lung disease outcomes by high-resolution computed tomography (HRCT) in Anti-Jo1 antibody-positive polymyositis patients: a single centre study and review of the literature

Interstitial lung disease (ILD) is a frequent complication of inflammatory myopathies with high rates of morbidity and mortality. Antibodies against aminoacyl-tRNA-synthetases are the strongest predictive factors in ILD. In this study, we reviewed the literature and we retrospectively analysed high-resolution computed tomography (HRCT) findings in a cohort of 131 consecutive subjects: 75 with polymyositis (PM), 43 with dermatomyositis (DM), one with amyophatic PM, two with paraneoplastic syndromes, and 10 with overlapping syndromes. The inclusion criteria were PM/DM, anti-Jo1 antibody positivity, and HRCT-assessed ILD. The effect of 12 months' treatment with cyclophosphamide (CYC) or cyclosporin A (CsA) plus steroids was assessed by comparing baseline and follow-up HRCT scans for evidence of stability, improvement or worsening. Fifteen patients (11.5%) had ILD and were Jo-1 positive. They were all women with PM, and had a mean age of 47.33 years and a median duration of symptoms of 7.26 months. At baseline, HRCT showed ground-glass attenuations in eight cases, septal thickening in seven, and honeycombing in four. Twelve months after diagnosis, ILD had worsened in nine patients (60%; exact confidence interval [ECI] 32-84) and was stable in four (two patients were lost to follow-up). Seven of the 15 patients were treated with CsA, and 12-month HRCT revealed a worsening in ILD in five cases (71%; ECI 0.29-0.96); ILD also worsened (ECI 16-84) in four of the eight patients treated with CYC pulses (50%). The evolution of the HRCT findings was not significantly different between the two groups. Our findings confirm that ILD is a common early manifestation in patients with Jo1-positive PM. Over twelve months, HRCT showed worsening ILD in most of our patients, with no difference in the HRCT changes between those treated with CYC or CsA.

Autoimmunity in 2010

There is now growing evidence that autoimmunity is the common trait connecting multiple clinical phenotypes albeit differences in tissue specificity, pathogenetic mechanisms, and therapeutic approaches cannot be overlooked. Over the past years we witnessed a constant growth of the number of publications related to autoimmune diseases in peer-reviewed journals of the immunology area. Original data referred to factors from common injury pathways (i.e. T helper 17 cells, serum autoantibodies, or vitamin D) and specific diseases such as multiple sclerosis, systemic lupus erythematosus, and rheumatoid arthritis. As an example, the issue of a latitudinal gradient in the prevalence and incidence rates has been proposed for all autoimmune diseases and was recently coined as geoepidemiology to suggest new environmental triggers for tolerance breakdown. The present article is aimed at reviewing the articles that were published over the past year in the major autoimmunity and immunology journals.