Anti-topoisomerase I autoantibodies in systemic sclerosis

Nuclear-penetrating scleroderma autoantibody inhibits topoisomerase 1 cleavage complex formation

The contributions of anti-Topoisomerase 1 (Top1) autoantibodies to the pathophysiology of diffuse cutaneous systemic sclerosis (dcSSc), the most aggressive scleroderma subtype, are unknown. Top1 catalyzes DNA relaxation and unwinding in cell nuclei, a site previously considered inaccessible to antibodies. The discovery of autoantibodies in systemic lupus erythematosus that penetrate nuclei and inhibit DNA repair raised the possibility that nuclear-penetrating autoantibodies contribute to mechanisms of autoimmunity. Here we show that an anti-Top1 autoantibody produced by a single B cell clone from a patient with dcSSc penetrates live cells and localizes into nuclei. Functionally, the autoantibody inhibits formation of the Top1 cleavage complex necessary for DNA nicking, which distinguishes it from cytotoxic camptothecin Top1 inhibitors used in cancer therapy that trap the cleavage complex rather than preventing its formation. Discovery of a patient-derived cell-penetrating scleroderma anti-Top1 autoantibody that inhibits Top1 cleavage complex formation supports the hypothesis that anti-Top1 autoantibodies contribute to cellular dysfunction in dcSSc and offers a valuable antibody reagent resource for future studies on anti-Top1 autoantibody contributions to scleroderma pathophysiology.

Autoantibodies against DNA topoisomerase I promote renal allograft rejection by increasing alloreactive T cell responses

Antibodies reactive to self-antigens are an important component of posttransplant immune responses. The generation requirements and functions of autoantibodies, as well as the mechanisms of their influence on alloimmune responses, still remain to be determined. Our study investigated the contribution of autoimmunity during rejection of renal allografts. We have previously characterized a mouse model in which the acute rejection of a life-supporting kidney allograft is mediated by antibodies. At rejection, recipient sera screening against >4000 potential autoantigens revealed DNA topoisomerase I peptide 205-219 (TI-I205-219) as the most prominent epitope. Subsequent analysis showed TI-I205-219-reactive autoantibodies are induced in nonsensitized recipients of major histocompatibility complex-mismatched kidney allografts in a T cell-dependent manner. Immunization with TI-I205-219 broke self-tolerance, elicited TI-I205-219 immunoglobin G autoantibodies, and resulted in acute rejection of allogeneic but not syngeneic renal transplants. The graft loss was associated with increased priming of donor-reactive T cells but not with donor-specific alloantibodies elevation. Similarly, passive transfer of anti-TI-I205-219 sera following transplantation increased donor-reactive T cell activation with minimal effects on donor-specific alloantibody levels. The results identify DNA topoisomerase I as a novel self-antigen in transplant settings and demonstrate that autoantibodies enhance activation of donor-reactive T cells following renal transplantation.

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.

Serum microRNAs in Systemic Sclerosis, Associations with Digital Vasculopathy and Lung Involvement

Background and aims: Systemic sclerosis (SSc) is an autoimmune, rare multisystem chronic disease that is still not well-understood aetiologically and is challenging diagnostically. In the literature, there are ever-increasing assumptions regarding the epigenetic mechanisms involved in SSc development; one of them is circulating microRNAs. Many of them regulate TLR pathways and are significant in autoimmune balance. The aim of this study was to determine profile expression of selected microRNAs in SSc patients, including miR-126, -132, -143, -145, -155, -181a, -29a and -3148, in comparison to healthy controls. Methods: Serum microRNAs were isolated from 45 patients with SSc and 57 healthy donors (HC). Additionally, SSc patients were considered in the aspect of disease subtype, including diffuse systemic sclerosis (dcSSc) and limited systemic sclerosis (lcSSc). Results: miR-3148 was detected neither in the serum of HC nor in SSc patients. All of the rest of the analyzed microRNAs, excluding miR-126, miR-29a and miR-181a, were significantly upregulated in SSc patients in comparison to HC. However, miR-181a has been revealed only in the serum of patients with lcSSc but not dcSSc. Moderate positive correlations between the transfer factor of the lung for carbon monoxide (TLCO) and miR-126 and miR-145 were observed. A significant correlation has been found between serum miR-143 level and forced vital capacity (FVC). SSc patients with FVC ≤ 70% were characterized by significantly lower levels of miR-143 compared to patients with normal FVC. Additionally, the expression of miR-132 was significantly higher in dcSSc subgroup with detected active lung lesions compared to dcSSc patients with fibrotic lesions. Patients with an early scleroderma pattern of microangiopathy seen on nailfold video-capillaroscopy (NVC) revealed higher expression of miR-155 in serum than those with a late pattern. Conclusions: The expression profile of circulating cell-free miRNAs is significantly changed in the serum of SSc patients compared to healthy individuals. Downregulation of miRNA-181a and overexpression of miR-132, miR-143, miR-145 and miR-155 in serum may be significant in SSc in the context of biomarkers.

Increased Frequency of Activated Switched Memory B Cells and Its Association With the Presence of Pulmonary Fibrosis in Diffuse Cutaneous Systemic Sclerosis Patients

Disease-associated, high-affinity pathological autoantibody production is a well-described consequence of immune dysregulation affecting B cells in systemic sclerosis (SSc), including the distribution of B-cell subsets. We have previously shown that the increased relative frequency of CD19+CD27+IgD- switched memory B cells is associated with the severe form of SSc. This study sought to analyze memory B cell subsets using an extended range of markers for further subdivision based on CD19, IgD, CD27, CD38 and CD95 phenotype, to define relationship between the alterations of memory B cell subsets and the clinical features of SSc. Peripheral blood samples were obtained from 21 SSc patients, including 14 diffuse (dcSSc) and 7 limited (lcSSc) cutaneous SSc patients, with disease duration of 2.7 ( ± 1.6) years. After purification of CD19+ B cells, multiparametric flow cytometry was performed and the frequencies of CD19+IgD-CD27-CD38+ double negative (DN) 1, CD19+IgDloCD27+CD38+ unswitched, CD19+IgD-CD27+CD38+CD95- resting switched and CD19+IgD-CD27+CD38-CD95+ activated switched memory (ASM) B cells were determined, and correlated with clinical features of SSc. The dcSSc patients had a higher frequency of ASM B cells (p = 0.028) compared to lcSSc patients. The percentage of ASM B cells was elevated in anti-Scl-70 (anti-topoisomerase I) antibody positive patients compared to negative patients (p = 0.016). Additionally, the frequency of ASM B cells was also increased in patients with pulmonary fibrosis (p = 0.003) suggesting that patients with severe form of SSc have higher ASM B cell ratios. Furthermore, the ratio of DN1 B cells was decreased (p = 0.029), while the level of anti-citrate synthase IgG natural autoantibody was elevated (p = 0.028) in patients with active disease. Our observations on the increase of ASM B cells in dcSSc and in patients with pulmonary fibrosis may point to the association of this alteration with the severe form of the disease. Functionally the correlation of ASM B cells as effector memory-plasma cell precursors with anti-topoisomerase I antibody positivity could reflect their contribution to pathological autoantibody production, whereas the decrease of memory precursor DN B cells and the increase of anti-citrate synthase IgG autoantibody may have potential significance in the assessment of disease activity.

Classical Disease-Specific Autoantibodies in Systemic Sclerosis: Clinical Features, Gene Susceptibility, and Disease Stratification

Systemic sclerosis (SSc) is an autoimmune disease characterized by abnormalities in microcirculation, extracellular matrix accumulation, and immune activation. Autoantibodies are markers of immune abnormalities and provide diagnostic and predictive value in SSc. Anti-topoisomerase antibodies (ATAs), anticentromere antibodies (ACAs), and anti-RNA polymerase antibodies (ARAs) are the three classical specific antibodies with the highest availability and stability. In this review, we provide an overview of the recent progress in SSc research with respect to ATAs, ACAs, and ARAs, focusing on their application in distinguishing clinical phenotypes, such as malignancy and organ involvement, identifying genetic background in human leukocyte antigen (HLA) or non-HLA alleles, and their potential roles in disease pathogenesis based on the effects of antigen-antibody binding. We finally summarized the novel analysis using ATAs, ACAs, and ARAs on more detailed disease clusters. Considering these advantages, this review emphasizes that classical SSc-specific autoantibodies are still practical and have the potential for patient and risk stratification with applications in precise medicine for SSc.

Network pharmacology strategy for predicting the correlation of Systemic Scleroderma with Vitamin D deficiency

The deficiency of Vitamin D (V_D) is a common symptom of systemic scleroderma (SSc), but the correlation of V_D deficiency and SSc is not completely clear. Therefore, a strategy based on network pharmacology was designed to explore the correlation of V_D deficiency and SSc. After a series of network construction and analysis, 5 integrins were predicated as the kernel targets in the correlation of V_D deficiency and SSc, including ITGA5, ITGA4, ITGB3, ITGB1 and ITGAV. The crucial pathways in which the kernel targets participated were mainly involved in the function of immune, vascular and internal organ. The regulation modules of crucial pathways were closely related to the biological processes in the pathological of SSc. Taken together, the analysis predicted that the deficiency of V_D might affect the pathological of SSc through the mediation of these integrins. Therefore, targeted regulation of these integrins might be an effective therapy against SSc.

Immunological and Clinical Characteristics of Systemic Lupus Erythematosus: A Series from Morocco

Systemic Lupus Erythematosus (SLE) is a complex autoimmune disease with a high female predominance. To date, studies about SLE in Morocco are few. This retrospective study describes the clinical and immunological features in a series of 50 SLE Moroccan patients in University Hospital Center of Rabat, Morocco, between December 2011 and December 2013. All patients were screened for antinuclear antibodies (ANA) and anti-DNA antibodies by indirect immunofluorescence, followed by identification of anti-extractable nuclear antigen antibodies by ELISA. The female to male ratio was 6.1:1. Mean age was 31.72 years. The main clinical manifestations were arthritis (82%), mucocutaneous manifestations (80%), renal manifestations (50%), and hematological features (46%). Of the mucocutaneous features, the highest frequencies were observed in the malar rash (68%) and photosensitivity (60%). Of the hematological features, lymphopenia was most frequently observed in 30% of patients, followed by hemolytic anemia in 16% and leucopenia and thrombocytopenia in 8%. Central nervous system was involved in 10%. ANA were found in 88%, anti-DNA antibodies in 56%, and anti-Sm antibodies in 50%. Anti-SSA, anti-SSB, anti-Sm/RNP, and anti-Scl70 antibodies were detected in 38%, 10%, 48%, and 8%, respectively. Our data show that, in our patients, the main clinical and immunological features of SLE remain comparable to patients from other Arab countries.

Anti-centromere protein A antibodies in systemic sclerosis: Significance and origin

Systemic sclerosis (SSc) is systemic, autoimmune, connective tissue disorder characterized by vascular abnormalities, collagen deposition (fibrosis), and the production of autoantibodies to nuclear proteins. About 20%-40% of patients have antibodies to centromere protein (CENP)-A or -B. Despite the known association of anti-CENP antibodies with certain clinical features of SSc, the role of these antibodies in SSc physiopathology is still poorly understood. To better understand the clinical significance and origin of these antibodies, we and others have been studying the epitopic motifs (amino acid contact sites) on CENP-A with the aim of determining whether other proteins can prime or be targeted by them. Here, we review published and ongoing studies aimed at defining the fine specificity and origin of anti-CENP-A antibodies. We describe progress made in identifying the CENP-A epitopic motif amino acids, and the discovery of one of these motifs in forkhead box protein E3 (FOXE-3), a transcription factor previously studied only for its role in the development of lens fiber cells. Moreover, we discuss preliminary evidence for a possible role of FOXE-3 in SSc pathogenesis and for the association of different subsets of anti-CENP-A antibodies, heterogeneously expressed among SSc patients, with some clinical correlates.

Interstitial lung disease in systemic sclerosis

Based on international collaborative data, interstitial lung disease is now the most frequent cause of death in systemic sclerosis (SSc), having supplanted renal crisis in that regard. Despite detailed explorations of candidate mediators, no primary pathway in the pathogenesis of interstitial lung disease associated with SSc (SSc-ILD) has been definitively identified and, therefore, treatment with current agents is only partially successful. However, as immunomodulatory agents do, on average, retard progression of lung disease, early identification of SSc-ILD, using thoracic high resolution computed tomography (HRCT), is highly desirable. The decision whether to introduce therapy immediately is often difficult as the balance of risk and benefit favours a strategy of careful observation when lung disease is very limited, especially in long-standing SSc. The threshold for initiating treatment is substantially reduced when lung disease is severe, systemic disease is short in duration or ongoing progression is evident, based on pulmonary function tests and symptoms. This review summarises epidemiology, pathogenesis, difficult clinical problems and management issues in SSc-ILD.

Serum 25-OH vitamin D concentrations are linked with various clinical aspects in patients with systemic sclerosis: a retrospective cohort study and review of the literature

Low vitamin D serum concentrations have been reported in several autoimmune conditions. The study's aim was to explore such a relationship in a large multinational population of patients with systemic sclerosis (SSc) and to pursue possible clinical and laboratory correlates with vitamin D concentrations. 327 sera samples of European patients with SSc and 141 samples of compatible healthy controls were studied for vitamin D concentrations using the commercial kit LIAISON 25-OH vitamin D assay (Diasorin). Additionally, clinical parameters including the Rodnan skin score, diffusing lung capacity for carbon monoxide (DLCO), systolic pulmonary artery pressure (sPAP), forced vital capacity (FVC), and nailfold video capillaroscopic, erythrocyte sedimentation rate (ESR), anti-nuclear antibodies (ANA and scl70), rheumatoid factor (RF) were investigated. Vitamin D serum concentration was 13.5 ± 9.0 ng/ml (mean ± standard deviation) in patients with SSc compared to 21.6 ± 9.7 ng/ml in a control group (p<0.001). A negative correlation between patients' age and vitamin D concentration (r = -0.2, p<0.05, n = 96) was observed. An inverse relationship was found between skin involvement and vitamin D serum concentrations; Patients with a Rodnan skin score of 10 or lower (n = 11) had a mean vitamin D concentration of 17.7 ± 10.4 ng/ml compared to patients with a score above 10 (n = 28) 8 ± 10.1 ng/ml (p=0.02, by the Mann-Whitney test). In conclusion, Patients with SSc have significantly lower serum vitamin D concentrations compared to healthy controls; moreover fibrosis of the cutaneous tissue is inversely related to the vitamin D concentration.

Capillaroscopy as an Outcome Measure for Clinical Trials on the Peripheral Vasculopathy in SSc-Is It Useful?

Peripheral microvascular impairment in systemic sclerosis (SSc) may be easily detected and scored in a safe noninvasive way by nailfold videocapillaroscopy (NVC). The paper highlights clinical conditions related to SSc in which NVC may represent an outcome measure of therapeutical interventions, by elaborating on their already assessed relationship with the NVC patterns and eventually scores. The 3 important biological/clinical conditions are: the positivity for SSc-specific serum autoantibodies, the presence of SSc skin digital ulcers (DUs) and of pulmonary arterial hypertension (PAH) SSc associated. In conclusion, to the question if capillaroscopy (NVC) may represent in SSc an outcome measure for clinical trials on the peripheral vasculopathy, based on the growing evidence and our detailed studies, the answer is positive. Recent therapeutic trials in SSc are confirming this role, and the experience is growing rapidly.

Anti-Scl-70 (topo-I) antibodies in SLE: Myth or reality?

Autoantibodies to topoisomerase I (topo-I, also referred to as Scl-70, ATA) have historically been considered a specific marker for systemic sclerosis (SSc). Although found in approximately 20% of SSc sera, other evidence indicated that ATA also occur in up to 25% of systemic lupus erythematosus (SLE). Given that SLE is approximately 100 times more prevalent than SSc, the number of ATA positive SLE patients is at least 2-3 orders of magnitude greater than the prevalence of ATA in SSc. These observations have raised questions about the disease specificity and clinical value of ATA. Therefore, our objective was to analyse the prevalence of ATA in different disease conditions with a special focus on SLE employing a systematic literature review (meta-analysis) in combination with our experimental investigations.

Biomarkers in systemic sclerosis

Systemic sclerosis is an autoimmune inflammatory disorder of unknown etiologycharacterized b y pronounced fibroproliferative alterations in the microvasculature, and frequent cellular and humoral immunity abnormalities, culminating in a severe and often progressive fibrotic process. Numerous biomarkers reflecting the three main pathogenetic mechanisms in systemic sclerosis have been described; however, aside from several disease-specific autoantibodies, other biomarkers have not been thoroughly validated and require further study. Thus, there is an unmet need for validated biomarkers for diagnosis, disease classification, and evaluation of organ involvement and therapeutic response in systemic sclerosis.

Serum levels of soluble vascular endothelial growth factor receptor-2 in patients with systemic sclerosis

BACKGROUND

Although vascular endothelial growth factor (VEGF)-A/VEGF receptor 2 (KDR) signalling may play a major role in the microangiopathy of systemic sclerosis (SSc), serum levels of soluble KDR (sKDR) in this disease have not yet been determined.

OBJECTIVES

To evaluate the possibility that serum sKDR levels can be a specific disease marker of SSc.

METHODS

Serum sKDR levels of 42 patients with SSc, 10 patients with Raynaud's phenomenon (RP) and 22 healthy controls were measured with specific enzyme-linked immunosorbent assays. Quantitative real-time polymerase chain reaction (PCR) was performed to determine KDR mRNA levels.

RESULTS

In females, the serum sKDR levels were significantly higher in patients with SSc, especially limited cutaneous SSc, than in patients with RP or healthy controls. Quantitative real-time PCR with RNA from skin sections revealed that KDR mRNA levels were also increased in the skin of patients with SSc with elevated serum sKDR levels. A significantly lower prevalence of pulmonary fibrosis, higher percentage vital capacity, and a higher incidence of telangiectasia were seen in female patients with SSc with elevated serum sKDR levels than those with normal levels.

CONCLUSIONS

These results suggest that the skin can be one of the sources of elevated serum sKDR levels, and that serum sKDR levels are useful for diagnosis and may be a marker of microangiopathy in patients with SSc, especially females. The VEGF-A/KDR signalling system may be involved in the pathogenesis of the disease.