Differences in autoantibody response to Th/To between systemic sclerosis and other autoimmune diseases

Anti-Th/To Antibodies in Scleroderma: Good Prognosis or Serious Concern?

Systemic sclerosis (SSc) represents a rare and intricate autoimmune connective tissue disease, the pathophysiology of which has not been fully understood. Its key features include progressive fibrosis of the skin and internal organs, vasculopathy and aberrant immune activation. While various anti-nuclear antibodies can serve as biomarkers for the classification and prognosis of SSc, their direct role in organ dysfunction remains unclear. Anti-Th/To antibodies are present in approximately 5% of SSc patients, and are particularly prevalent among those with the limited subtype of the disease. Although the presence of these autoantibodies is associated with a mild course of the disease, there is a strong connection between them and severe clinical manifestations of SSc, including interstitial lung disease, pulmonary arterial hypertension and gastrointestinal involvement. Also, the additional clinical correlations, particularly with malignancies, need further research. Moreover, the disease's course seems to be influenced by antibodies, specific serum cytokines and TLR signaling pathways. Understanding the relationships between presence of anti-Th/To, its molecular aspects and response to treatment options is crucial for the development of novel, personalized therapeutic techniques and should undergo profound analysis in future studies.

A case of anti-HMGCR myopathy in a patient with breast cancer and anti-Th/To antibodies

Statins competitively inhibit the activity of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase), which is a key enzyme in cholesterol synthesis. These are effective drugs for the management of cardiovascular disease and are generally well tolerated but several side effects have been reported. Muscular adverse symptoms are various and, rarely, statin exposure may lead to authentic immune-mediated necrotizing myopathy (IMNM), namely anti-HMGCR myopathy. However, cases of IMNM associated with cancer have been described. We discuss herein a case of IMNM in a patient with breast cancer previously exposed to statins and with the presence of anti-Th/To antibodies without clinical correlation.

The axis of complement C1 and nucleolus in antinuclear autoimmunity

Antinuclear autoantibodies (ANA) are heterogeneous self-reactive antibodies that target the chromatin network, the speckled, the nucleoli, and other nuclear regions. The immunological aberration for ANA production remains partially understood, but ANA are known to be pathogenic, especially, in systemic lupus erythematosus (SLE). Most SLE patients exhibit a highly polygenic disease involving multiple organs, but in rare complement C1q, C1r, or C1s deficiencies, the disease can become largely monogenic. Increasing evidence point to intrinsic autoimmunogenicity of the nuclei. Necrotic cells release fragmented chromatins as nucleosomes and the alarmin HMGB1 is associated with the nucleosomes to activate TLRs and confer anti-chromatin autoimmunogenecity. In speckled regions, the major ANA targets Sm/RNP and SSA/Ro contain snRNAs that confer autoimmunogenecity to Sm/RNP and SSA/Ro antigens. Recently, three GAR/RGG-containing alarmins have been identified in the nucleolus that helps explain its high autoimmunogenicity. Interestingly, C1q binds to the nucleoli exposed by necrotic cells to cause protease C1r and C1s activation. C1s cleaves HMGB1 to inactive its alarmin activity. C1 proteases also degrade many nucleolar autoantigens including nucleolin, a major GAR/RGG-containing autoantigen and alarmin. It appears that the different nuclear regions are intrinsically autoimmunogenic by containing autoantigens and alarmins. However, the extracellular complement C1 complex function to dampen nuclear autoimmunogenecity by degrading these nuclear proteins.

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.

Clinical Significance of Antinucleolar Antibodies: Biomarkers for Autoimmune Diseases, Malignancies, and others

Nucleolar staining is one of the standard patterns in immunofluorescence antinuclear antibodies (ANA), seen in 5-9% of ANA in various conditions. Antinucleolar antibodies (ANoA) are classified into 3 patterns in the International Consensus on ANA Patterns (ICAP) classification; AC-8 homogeneous pattern, AC-9 clumpy pattern, and AC-10 punctate pattern. Specificities known to show AC-8 include anti-Th/To, -PM-Scl, -nucleophosmin/B23, -nucleolin/C23, -No55, and others. AC-9 is seen by anti-fibrillarin/U3RNP and AC-10 by anti-RNA polymerase I and hUBF/NOR-90. ANoA has been classically known to be associated with scleroderma (SSc) and the characterization of nucleolar antigens identified several autoantigens recognized by SSc autoantibodies. The clinical association of anti-Th/To, PM-Scl, fibrillarin/U3RNP, and RNA polymerase I with SSc or SSc-overlap syndrome is well established, and commercial assays are developed. Anti-hUBF/NOR90, nucleophosmin/B23, and nucleolin/C23 are known for decades and reported in systemic autoimmune rheumatic diseases (SARDs), malignancies, graft versus host disease (GVHD), and others; however, their clinical significance remains to be established.

Development of Pulmonary Hypertension in Over One-Third of Patients With Th/To Antibody-Positive Scleroderma in Long-Term Follow-Up

OBJECTIVE

This study was undertaken to describe clinical manifestations in patients with Th/To antibody-positive systemic sclerosis (SSc) during long-term follow-up.

METHODS

We performed a case-control study involving anti-Th/To antibody-positive patients with SSc who were newly referred to the University of Pittsburgh Medical Center and the Pittsburgh Scleroderma Center from 1980 to 2015. For every case, 2 anti-Th/To antibody-negative SSc patients (the first 2 consecutively seen after a case) were used as controls. Long-term disease manifestations and survival were then compared between cases and controls.

RESULTS

A total of 204 anti-Th/To antibody-positive SSc patients and 408 controls were identified. The cohort had a mean ± SD age of 52 ± 12.9 years, and 76% of individuals were women. Anti-Th/To antibody-positive patients more often presented without skin thickening (P < 0.0001) and had a higher rate of pulmonary hypertension (PH) (P < 0.0001) and interstitial lung disease (P = 0.05) compared to anti-Th/To antibody-negative SSc controls. Anti-Th/To antibody-positive SSc patients also had less frequent muscle and joint involvement than anti-Th/To antibody-negative SSc controls (P < 0.0001). After a median clinical follow-up period of 6.1 years (interquartile range 2.4-12.7), 38% of anti-Th/To-positive patients had developed PH compared to 15% of anti-Th/To antibody-negative SSc controls (P < 0.0001). The rate of PH classified as World Health Organization (WHO) Group 1 pulmonary arterial hypertension [PAH] was 23% in anti-Th/To-positive patients compared to 9% in anti-Th/To antibody-negative SSc controls (P < 0.0001). After adjusting for age and sex, anti-Th/To antibody positivity was associated with a hazard ratio (HR) of 3.3 (95% confidence interval 2.3-4.9) for increased risk of developing PH at 10 years of follow-up from the first scleroderma center visit.

CONCLUSION

This is the largest cohort of patients with anti-Th/To antibody-positive SSc with long-term follow-up data. The very high rate (38%) and associated independent risk of anti-Th/To antibody-positive patients developing PH in follow-up, particularly in WHO Group 1 PAH patients, is striking. Patients presenting with limited skin involvement should be tested for Th/To antibodies, and if present, careful monitoring for PH is warranted.

RPP40 is a prognostic biomarker and correlated with tumor microenvironment in uterine corpus endometrial carcinoma

Ribonuclease P/MRP Subunit P40 (RPP40), a component of ribonuclease P and multimeric ribonuclease P complex, was reported as one of the promoting factors for the chemoresistance of acute myeloid leukemia and a recurrence predictor of early-stage triple-negative breast cancer. However, the functional role of RPP40 in uterine corpus endometrial carcinoma (UCEC) is unclear. In this study, comprehensive bioinformatic analyses were conducted to explore the predictive role of RPP40 on UCEC diagnosis and prognosis, as well as the underlying mechanism. Differential analyses of multiple databases showed that both messenger RNA (mRNA) and the protein expression of RPP40 were significantly upregulated in UCEC tumor tissues. Furthermore, the RPP40 mRNA expression level was significantly correlated with the clinicopathological characteristics of UCEC patients, including the clinical stage, primary therapy outcome, histological type, histologic grade, overall survival event, disease-specific survival event, and progression-free interval event. Receiver operating characteristic (ROC) analysis showed that RPP40 was a reliable predictor for UCEC diagnosis with an area under the curve (AUC) of 0.775, a sensitivity of 0.829, and a specificity of 0.719. Kaplan–Meier, Cox regression, and nomogram analyses showed that high RPP40 expression was an independent prognostic factor for the 1-year, 3-year, and 5-year survival of UCEC patients. In addition, the enrichment analysis of RPP40-associated differentially expressed genes and correlation analyses showed that the expression of RPP40 was correlated with the regulation of extracellular matrix and immune cell infiltration. In conclusion, the upregulation of RPP40 is significantly correlated with the poor survival and tumor microenvironment of UCEC, suggesting that RPP40 is a promising biomarker of poor prognosis and a potential target of chemotherapy or immunotherapy in UCEC.

Clinical and radiological features of lung disorders related to connective-tissue diseases: a pictorial essay

Connective tissue diseases (CTDs) include a spectrum of disorders that affect the connective tissue of the human body; they include autoimmune disorders characterized by immune-mediated chronic inflammation and the development of fibrosis. Lung involvement can be misdiagnosed, since pulmonary alterations preceded osteo-articular manifestations only in 20% of cases and they have no clear clinical findings in the early phases. All pulmonary structures may be interested: pulmonary interstitium, airways, pleura and respiratory muscles. Among these autoimmune disorders, rheumatoid arthritis (RA) is characterized by usual interstitial pneumonia (UIP), pulmonary nodules and airway disease with air-trapping, whereas non-specific interstitial pneumonia (NSIP), pulmonary hypertension and esophageal dilatation are frequently revealed in systemic sclerosis (SSc). NSIP and organizing pneumonia (OP) may be found in patients having polymyositis (PM) and dermatomyositis (DM); in some cases, perilobular consolidations and reverse halo-sign areas may be observed. Systemic lupus erythematosus (SLE) is characterized by serositis, acute lupus pneumonitis and alveolar hemorrhage. In the Sjögren syndrome (SS), the most frequent pattern encountered on HRCT images is represented by NSIP; UIP and lymphocytic interstitial pneumonia (LIP) are reported with a lower frequency. Finally, fibrotic NSIP may be the interstitial disease observed in patients having mixed connective tissue diseases (MCTD). This pictorial review therefore aims to provide clinical features and imaging findings associated with autoimmune CTDs, in order to help radiologists, pneumologists and rheumatologists in their diagnoses and management.

Systemic Sclerosis-Specific Antibodies: Novel and Classical Biomarkers

Disease-specific autoantibodies are considered the most important biomarkers for systemic sclerosis (SSc), due to their ability to stratify patients with different severity and prognosis. Anti-nuclear antibodies (ANA), occurring in subjects with isolated Raynuad's phenomenon, are considered the strongest independent predictors of definite SSc and digital microvascular damage, as observed by nailfold videocapillaroscopy. ANA are present in more than 90% of SSc, but ANA negativity does not exclude SSc diagnosis: a little rate of SSc ANA negative exists and shows a distinct subtype of disease, with less vasculopathy, but more frequent lower gastrointestinal involvement and severe disease course. Anti-centromere, anti-Th/To, and anti-Topoisomerase I antibodies could be considered as classical biomarkers, covering about 60% of SSc and defining patients with well-described cardio-pulmonary complications. In particular, anti-Topoisomerase I represent a risk factor for development of diffuse cutaneous involvement and digital ulcers in the first 3 years of disease, as well as severe interstitial lung disease (ILD). Anti-RNA polymerase III is a biomarker with new clinical implications: very rapid skin thickness progression, gastric antral vascular ectasia, the occurrence of synchronous cancers, and possible association with silicone breast implants rupture. Moreover, novel SSc specific autoantibodies have been globally described in about 10% of "seronegative" SSc patients: anti-elF2B, anti-RuvBL1/2 complex, anti-U11/U12 RNP, and anti-BICD2 depict specific SSc subtypes with severe organ complications. Many autoantibodies could be considered markers of overlap syndromes, including SSc. Anti-Ku are found in 2-7% of SSc, strictly defining the PM/SSc overlap. They are associated with synovitis, joint contractures, myositis, and negatively associated with vascular manifestation of disease. Anti-U3RNP are associated with a well-defined clinical phenotype: Afro-Caribbean male patients, younger at diagnosis, and higher risk of pulmonary hypertension and gastrointestinal involvement. Anti-PM/Scl define SSc patients with high frequency of ILD, calcinosis, dermatomyositis skin changes, and severe myositis. The accurate detection of autoantibodies SSc specific and associated with overlap syndromes is crucial for patients' stratification. ANA should be correctly identified using indirect immunofluorescent assay and a standardized way of patterns' interpretation. The gold-standard technique for autoantibodies' identification in SSc is still considered immunoprecipitation, for its high sensitivity and specificity, but other assays have been widely used in routine practice. The identification of SSc autoantibodies with high diagnostic specificity and high predictive value is mandatory for early diagnosis, a specific follow-up and the possible definition of the best therapy for every SSc subsets. In addition, the validation of novel autoantibodies is mandatory in wider cohorts in order to restrict the gap of so-called seronegative SSc patients.

RPP25 as a Prognostic-Related Biomarker That Correlates With Tumor Metabolism in Glioblastoma

RPP25, a 25 kDa protein subunit of ribonuclease P (RNase P), is a protein-coding gene. Disorders associated with RPP25 include chromosome 15Q24 deletion syndrome and diffuse scleroderma, while systemic sclerosis can be complicated by malignancy. However, the functional role of RPP25 expression in glioblastoma multiforme (GBM) is unclear. In this study, comprehensive bioinformatics analysis was used to evaluate the impact of RPP25 on GBM occurrence and prognosis. Differential analysis of multiple databases showed that RPP25 was commonly highly expressed in multiple cancers but lowly expressed in GBM. Survival prognostic results showed that RPP25 was prognostically relevant in six tumors (CESC, GBM, LAML, LUAD, SKCM, and UVM), but high RPP25 expression was significantly associated with poor patient prognosis except for CESC. Analysis of RPP25 expression in GBM alone revealed that RPP25 was significantly downregulated in GBM compared with normal tissue. Receiver operating characteristic (ROC) combined with Kaplan-Meier (KM) analysis and Cox regression analysis showed that high RPP25 expression was a prognostic risk factor for GBM and had a predictive value for the 1-year, 2-year, and 3-year survival of GBM patients. In addition, the expression of RPP25 was correlated with the level of immune cell infiltration. The gene set enrichment analysis (GSEA) results showed that RPP25 was mainly associated with signalling pathways related to tumor progression and tumor metabolism.

Prevalence and risk factors of systemic sclerosis-associated interstitial lung disease in East Asia: A systematic review and meta-analysis

Objective

Interstitial lung disease (ILD) is a common and potentially life‐threatening complication for individuals with systemic sclerosis (SSc). The purpose of this study was to complete a systematic review and meta‐analysis on prevalence and risk factors of SSc‐ILD in East Asia.

Methods

Medline, EMBASE, and Cochrane Library were searched up to January 22, 2021. The Reporting of Observational Studies in Epidemiology (STROBE) statement was applied to access the methodological quality of the eligible studies. Study characteristics and magnitude of effect sizes were extracted. Then, we calculated the pooled prevalence, weighted mean differences (WMDs), pooled odds ratios (ORs) with corresponding 95% confidence intervals (CIs), and performed subgroup analysis, sensitivity analysis, and publication bias with Egger's test.

Results

Twenty‐seven of 1584 articles were eligible and a total of 5250 patients with SSc were selected in the meta‐analysis. The pooled prevalence of SSc‐ILD in East Asia was 56% (95% CI 49%‐63%). The SSc‐ILD prevalence was higher in China (72%) than in Japan (46%) and Korea (51%). Longer disease duration (WMD = 1.97, 95% CI 0.55‐3.38), diffuse SSc (OR = 2.84, 95% CI 1.91‐4.21), positive anti‐topoisomerase I antibody (ATA) (OR = 4.92, 95% CI 2.74‐8.84), positive anti‐centromere body antibody (ACA) (OR = 0.14, 95% CI 0.08‐0.25), positive anti‐U3 ribonucleoprotein (RNP) antibody (OR = 0.17, 95% CI 0.04‐0.66), and higher erythrocyte sedimentation rate (ESR) (WMD = 6.62, 95% CI 1.19‐12.05) were associated with SSc‐ILD in East Asia.

Conclusion

Through this systematic review and meta‐analysis, we found that ILD occurs in up to approximately 56% of patients with SSc in East Asia. Longer disease duration, diffuse SSc, positive ATA, negative ACA, negative anti‐U3 RNP antibody, and higher ESR were risk factors for SSc‐ILD.

[A case of anti-Th/To antibody-positive systemic sclerosis with muscle symptoms and interstitial pneumonia]

A 62-year-old Japanese man with swollen fingers and walking difficulty due to myalgia and muscle weakness in proximal limb muscles was admitted to our hospital. Serum creatine kinase was remarkably increased (7,380 U/l) and rapidly progressing interstitial pneumonia developed. Muscle biopsy showed necrotic and regenerating fibers without mononuclear infiltration and fibrosis. Anti-Th/To antibodies were detected in the serum, and anti-Th/To antibody-positive systemic sclerosis was diagnosed. Anti-Th/To antibody-positive sclerosis-associated myopathy has not yet been reported in the literature. The present case suggests that anti-Th/To antibody-positive systemic sclerosis can be accompanied by immune-mediated necrotizing myopathy and be effectively treated with immunotherapy comprising corticosteroids, tacrolimus and immunoglobulin.

Joint contractures responsive to immunosuppressive therapy in a girl with childhood-onset systemic sclerosis double-seropositive for rare anti-nucleolar autoantibodies: a case report

BACKGROUND

Systemic sclerosis (SSc; scleroderma) is an autoimmune connective tissue disease that affects the skin and subcutaneous tissue, in addition to the internal organs of the whole body. Onset in childhood is uncommon; however, both patients with childhood-onset and adult-onset SSc are positive for anti-nuclear antibodies (ANAs).Detection of SSc-related anti-nuclear antibodies is often useful for predicting clinical features, disease course, and outcomes.

CASE PRESENTATION

A 5-year-old Japanese female manifested gradually progressive abnormal gait disturbance, regression of motor development, Raynaud's phenomenon, and the shiny appearance of the skin of the face and extremities at age 2. On admission, she presented a mask-like appearance, loss of wrinkles and skin folds, puffy fingers, moderate diffuse scleroderma (18/51 of the modified Rodnan total skin thickness score), and contracture in the ankle and proximal interphalangeal joints. Grossly visible capillary hemorrhage on nail fold and severe abnormal capillaroscopy findings including bleeding, giant loop and disappearance of capillaryconsistent with the late phase in SSc. A skin biopsy showed fibrous thickening of the dermis, entrapment of an eccrine sweat glands, and thickened fiber. Chest high-resolution computed tomographic scanning demonstrated patchy areas of ill-defined air-space opacity and consolidation predominantly involving the posterior basilar aspects of the lower lobes presenting withinterstitial lung disease. Positive ANA (1:160 nucleolar and homogeneous nuclear staining by indirect fluorescent antibody technique) and double-seropositive for anti-Th/To and anti-PM-Scl antibodies were identified. She was diagnosed with diffuse cutaneous SSc based on the Pediatric Rheumatology European Society/American College of Rheumatology/European League Against Rheumatism Provisional Classification Criteria for Juvenile Systemic Sclerosis and was successfully treated with immunosuppressive agents, including methylprednisolone pulses and intravenous cyclophosphamide.

CONCLUSIONS

We experienced the first case of juvenile SSc with anti-PM-Scl and anti-Th/To antibodies. ILD was identified as a typical feature of patients with these autoantibodies; however, diffuse cutaneous SSc and joint contraction were uncharacteristically associated. The case showed unexpected clinical findings though the existence of SSc-related autoantibodies aids in determining possible organ involvement and to estimate the children's outcome.

Cancer in Systemic Sclerosis: Analysis of Antibodies Against Components of the Th/To Complex

OBJECTIVE

The aim of this study is to describe 4 of the most common autoantibodies against components of the Th/To complex: human POP1 (hPOP1), RPP25, RPP30, and RPP40. We report their prevalence and clinical characteristics in a systemic sclerosis (SSc) population, and determine whether these specificities are associated with cancer.

METHODS

A case-control study was performed using data from the Johns Hopkins Scleroderma Center Cohort. A total of 804 adult patients with SSc were included; 401 SSc patients with no history of cancer after at least 5 years of disease were compared to 403 SSc patients who ever had a history of cancer. Antibodies against hPOP1, RPP25, RPP30, and RPP40 were assayed by immunoprecipitation of 35 S-methionine-labeled proteins generated by in vitro transcription/translation. Demographic and clinical characteristics were compared between groups.

RESULTS

Of 804 patients, 67 (8.3%) had antibodies against any component of the Th/To complex. Patients with antibodies to any component were significantly more likely to have limited cutaneous disease, less likely to have tendon friction rubs, and more likely to have findings consistent with interstitial lung disease or pulmonary hypertension. Patients with antibodies against hPOP1, RPP25, RPP30, and/or RPP40 were significantly less likely to develop cancer within 2 years of SSc onset (0% versus 11% of antibody-negative patients; P = 0.009).

CONCLUSION

SSc patients who produce autoantibodies to components of the Th/To complex have a clinical phenotype characterized by limited cutaneous disease and pulmonary involvement. Our findings show that the presence of any Th/To autoantibody may have a protective effect against contemporaneous cancer.

Pathogenic roles of autoantibodies in systemic sclerosis: Current understandings in pathogenesis

The potential pathogenic role for autoantibodies in systemic sclerosis has captivated researchers for the past 40 years. This review answers the question whether there is yet sufficient knowledge to conclude that certain serum autoantibodies associated with systemic sclerosis contribute to its pathogenesis. Definitions for pathogenic, pathogenetic and functional autoantibodies are formulated, and the need to differentiate these autoantibodies from natural autoantibodies is emphasized. In addition, seven criteria for the identification of pathogenic autoantibodies are proposed. Experimental evidence is reviewed relevant to the classic systemic sclerosis antinuclear autoantibodies, anti-topoisomerase I and anticentromere, and to functional autoantibodies to endothelin 1 type A receptor, angiotensin II type 1 receptor, muscarinic receptor 3, platelet-derived growth factor receptor, chemokine receptors CXCR3 and CXCR4, estrogen receptor α, and CD22. Pathogenic evidence is also reviewed for anti-matrix metalloproteinases 1 and 3, anti-fibrillin 1, anti-IFI16, anti-eIF2B, anti-ICAM-1, and anti-RuvBL1/RuvBL2 autoantibodies. For each autoantibody, objective evidence for a pathogenic role is scored qualitatively according to the seven pathogenicity criteria. It is concluded that anti-topoisomerase I is the single autoantibody specificity with the most evidence in favor of a pathogenic role in systemic sclerosis, followed by anticentromere. However, these autoantibodies have not been demonstrated yet to fulfill completely the seven proposed criteria for pathogenicity. Their contributory roles to the pathogenesis of systemic sclerosis remain possible but not yet conclusively demonstrated. With respect to functional autoantibodies and other autoantibodies, only a few criteria for pathogenicity are fulfilled. Their common presence in healthy and disease controls suggests that major subsets of these immunoglobulins are natural autoantibodies. While some of these autoantibodies may be pathogenetic in systemic sclerosis, establishing that they are truly pathogenic is a work in progress. Experimental data are difficult to interpret because high serum autoantibody levels may be due to polyclonal B-cell activation. Other limitations in experimental design are the use of total serum immunoglobulin G rather than affinity-purified autoantibodies, the confounding effect of other systemic sclerosis autoantibodies present in total immunoglobulin G and the lack of longitudinal studies to determine if autoantibody titers fluctuate with systemic sclerosis activity and severity. These intriguing new specificities expand the spectrum of autoantibodies observed in systemic sclerosis. Continuing elucidation of their potential mechanistic roles raises hope of a better understanding of systemic sclerosis pathogenesis leading to improved therapies.

Characteristics of Systemic Sclerosis patients with positive anti-Th/To antibodies: About 6 patients and literature review

Among the antibodies described in Systemic Sclerosis (SSc), anti-Th/To antibodies (anti-Th/To) are rare and have been poorly studied. Thus, little is known about the profile of anti-Th/To positive patients. From our local Biobank (Marseille, France), we retrospectively selected data for 6 patients positive for anti-Th/To with an Immunodot assay. All of them suffered from SSc, sharing clinical and biological common features such as a limited cutaneous form of SSc, a decreased lung diffusing capacity and a speckled nuclear nucleolar immunofluorescence pattern of antinuclear antibodies screening on HEp-2 cells. In order to further characterize patients positive for anti-Th/To, we performed a thorough literature review. From 402 studied patients positive for anti-Th/To, we confirmed that these antibodies are associated with the limited cutaneous form of the disease (88% of the patients), and with an SSc related-pulmonary involvement (50%). The review analysis pointed out the rarity of the anti-Th/To with an estimated mean frequency of 3.4% of all SSc patients worldwide, their usual exclusivity with respect to the specific antibodies of scleroderma, and their high specificity (around 98%) for the diagnosis of SSc.

Autoantibodies to a novel Rpp38 (Th/To) derived B-cell epitope are specific for systemic sclerosis and associate with a distinct clinical phenotype

Objective

Detection of antinuclear antibodies and specific autoantibodies is important in the diagnosis and classification of SSc. Several proteins of the Th/To complex, including Rpp25, Rpp38 and hPop1 are the target of autoantibodies in SSc patients. However, very little is known about the epitope distribution of this autoantigen. Consequently, we screened Rpp25, Rpp38 and hPop1 for B cell epitopes and evaluated their clinical relevance.

Methods

Serum pools with (n = 2) and without (n = 1) anti-Th/To autoantibodies were generated and used for epitope discovery. Identified biomarker candidate sequences were then utilized to synthesize synthetic, biotinylated, soluble peptides. The peptides were tested to determine reactivity with sera from SSc cohorts (n = 202) and controls (n = 159) using a chemiluminescence immunoassay. Additionally, samples were also tested for antibodies to full-length recombinant Rpp25 antibodies by chemiluminescence immunoassay.

Results

Several immunodominant regions were found on the three proteins. The strongest reactivity was observed with an Rpp38 peptide (aa 229–243). Autoantibodies to the Rpp38 peptide were detected in 8/149 (5.4%) limited cutaneous SSc patients, but not in any of 159 controls (P = 0.003 by two-sided Fisher's exact probability test). Although reactivity to the novel antigenic peptide was correlated with the binding to Rpp25 (rho = 0.44; P < 0.0001), subsets of patient sera either reacted strongly with Rpp25 or with the novel Rpp38-derived peptide.

Conclusion

A novel Rpp38 epitope holds promise to increase the sensitivity in the detection of anti-Th/To autoantibodies, thus enhancing the serological diagnosis of SSc.

Anti-nuclear autoantibodies in systemic sclerosis : News and perspectives

Systemic sclerosis is a connective tissue disorder characterized by microvascular damage and excessive fibrosis of the skin and internal organs. One hallmark of the immunological abnormalities in systemic sclerosis is the presence of anti-nuclear antibodies, which are detected in more than 90% of patients with systemic sclerosis. Anti-centromere antibodies, anti-DNA topoisomerase I antibodies, and anti-RNA polymerase III antibodies are the predominant anti-nuclear antibodies found in systemic sclerosis patients. Other systemic sclerosis-related anti-nuclear antibodies include those targeted against U3 ribonucleoprotein, Th/To, U11/U12 ribonucleoprotein, and eukaryotic initiation factor 2B. Anti-U1 ribonucleoprotein, anti-Ku antibodies, anti-PM-Scl, and anti-RuvBL1/2 antibodies are associated with systemic sclerosis overlap syndrome. Anti-human upstream binding factor, anti-Ro52/TRIM21, anti-B23, and anti-centriole antibodies do not have specificity to systemic sclerosis, but are sometimes detected in sera from patients with systemic sclerosis. Identification of each systemic sclerosis-related antibody is useful to diagnose and predict organ involvement, since the particular type of systemic sclerosis-related antibodies is often predictive of clinical features, severity, and prognosis. The clinical phenotypes are largely influenced by ethnicity. Currently, an immunoprecipitation assay is necessary to detect most systemic sclerosis-related antibodies; therefore, the establishment of an easy, reliable, and simple screening system is warranted.

Circulating Anti-Nuclear Antibodies in Systemic Sclerosis: Utility in Diagnosis and Disease Subsetting

The presence of circulating anti-nuclear antibodies (ANAs) is a hallmark of immune dysregulation in patients with systemic sclerosis (SSc). Currently, a variety of SSc-specific ANAs, including anticentromere, anti-topoisomerase I, and anti-RNA polymerase III antibodies, have been well characterized, and their commercial kits are available worldwide. Since these autoantibodies are specifically detected in SSc patients and are associated with unique sets of disease manifestations, they are widely used in routine clinical practice for diagnosis, clinical subgrouping, and prediction of future organ involvements and prognosis. In addition, SSc-specific ANAs are also useful in predicting future development of SSc in patients with Raynaud's phenomenon without any scleroderma skin changes, because their production often precedes onset of SSc symptoms. Application of circulating SSc-specific ANA measurement to clinical practice has greatly improved patient care, but utility of the autoantibody testing could be maximized by combining other clinical information, such as degree and extent of skin thickness and disease duration.

Autoantibody to scaffold attachment factor B (SAFB): A novel connective tissue disease-related autoantibody associated with interstitial lung disease

OBJECTIVE

To identify and characterize a novel connective tissue disease (CTD)-related autoantibody (autoAb) directed against scaffold attachment factor B (SAFB).

METHODS

AutoAb specificity was analyzed using RNA and protein-immunoprecipitation assays. Autoimmune targets were affinity purified using patients' sera and subjected to liquid chromatography mass spectrometry.

RESULTS

By immunoprecipitation assay, 10 sera reacted with a protein with a molecular weight of approximately 160 kDa. Liquid chromatography mass spectrometry of the partially purified autoantigen and additional immunoblot-based analyses revealed that the Ab specifically recognized SAFB. Anti-SAFB Abs were detected in 2 of 646 patients with systemic sclerosis (SSc) (0.3%), 1 of 1570 patients with polymyositis/dermatomyositis (0.06%), 4 of 270 patients with interstitial lung disease (ILD) (1.5%), 1 of 43 patients with overlap syndrome (2.3%) and 2 patients with other diseases including primary Raynaud's disease and eosinophilic pneumonia. Five patients with anti-SAFB Abs had Raynaud's phenomenon and 3 had nail fold punctate hemorrhage. Of note, 8 of the 10 patients (80%) suffered from ILD. None of the patients with anti-SAFB Abs had pulmonary arterial hypertension, heart disease, or renal involvement.

CONCLUSIONS

Anti-SAFB Ab is a novel CTD-related autoAb possibly associated with ILD.

Ethnic Differences in Autoantibody Diversity and Hierarchy: More Clues from a US Cohort of Patients with Systemic Sclerosis

OBJECTIVE

To determine the autoantibody repertoire and clinical associations in a multiethnic cohort of American patients with systemic sclerosis (SSc).

METHODS

There were 1000 patients with SSc (196 Hispanic, 228 African American, 555 white, and 21 other) who were screened for antinuclear antibodies (ANA), including anticentromere antibodies (ACA) by indirect immunofluorescence assay, antitopoisomerase-1 (topo-1/Scl-70) by immunodiffusion, and anti-RNA polymerase III (RNAP III) by ELISA. Sera from 160 patients with mainly nucleolar and/or speckled ANA pattern, but negative for ACA, Scl-70, and RNAP III, were further characterized by immunoprecipitation for SSc-specific antibodies.

RESULTS

The prevalence of antibodies against RNAP III, Th/To, and PM/Scl did not differ significantly among the ethnic groups. The frequency of anti-Scl-70 was lowest in whites (18.0%) compared with 24.0% and 26.8% in Hispanics and African Americans (p = 0.01), respectively. Compared with African American patients, Hispanic and white subjects had a higher frequency of ACA (p < 0.0001) and lower frequency of U3-RNP (p < 0.0001). U3-RNP antibodies were uniquely higher in African American patients, independent of clinical subset, while Th/To autoantibodies were associated with limited cutaneous SSc in white subjects. Overall, Hispanic and African American patients had an earlier age of onset and a predominance of diffuse cutaneous SSc compared with their white counterparts.

CONCLUSION

SSc-specific antibodies may predict disease subset; however, the hierarchy of their prevalence differs across ethnic groups. This study provides the most extensive analysis to date on the relevance of autoantibodies in the diagnosis and clinical manifestations of SSc in Hispanic American patients.

Serological profile and clinical features of nucleolar antinuclear pattern in patients with systemic lupus erythematosus from southwestern Spain

Nucleolar staining of antinuclear antibodies (ANAs) is not exclusive to patients suffering systemic sclerosis (SSc) since it can occur in other autoimmune diseases, such as systemic lupus erythematosus (SLE). The nucleolar ANA pattern presents a low incidence in patients with SLE, with less than 9% reported in some studies. The significance of nucleolar staining and antinucleolar antibodies (ANoA) in SLE is still unknown, as is its association with clinical manifestations. To address these issues, a case-control study was carried out. Twenty-eight cases of SLE with nucleolar staining were enrolled, as well as 73 controls with no nucleolar staining and different ANA patterns (homogeneous, speckled, and combined homogeneous and speckled). The homogeneous nucleolar pattern was the most frequent (27 out of 28), and in 75% was combined with other ANA patterns. The anti-double stranded DNA antibodies showed no differences between the two groups of patients, nor the auto-antibodies detected by line immunoassay (LIA). However, we have found an increased frequency of anti-PM-Scl antibodies with respect to the controls ( p = 0.02), in addition to the association between Raynaud's phenomenon (RP) and anti-PM-Scl antibodies (OR = 20.72, 95% CI 1.33–323.19, p = 0.03). Moreover, the cases of SLE showed a 7.78-fold increase in the risk of developing cancer (95%, CI 1.85–32.75, p = 0.005) with respect to the control group. Taken together these findings suggest that nucleolar staining represents a comorbidity factor in patients with SLE, although its significance must still be determined.

Autoantibodies to the Rpp25 component of the Th/To complex are the most common antibodies in patients with systemic sclerosis without antibodies detectable by widely available commercial tests

OBJECTIVE

Antinuclear antibodies (ANA) occur in up to 95% of patients with systemic sclerosis (SSc). In most, SSc-associated antibodies are detected (i.e., centromere, topoisomerase I, RNA polymerase III, PM/Scl, Ro52/TRIM21, and U1RNP). Ribonuclease P protein subunit p25, (Rpp25) is an autoantigenic component of the Th/To complex. The contribution of anti-Th/To and anti-Rpp25 antibodies to ANA positivity in patients with SSc remains unknown.

METHODS

Sera from 873 patients with SSc were tested for ANA, and SSc-associated antibodies were measured. Samples without antibodies to extractable nuclear antigens (ENA; n = 53, ANA+/ENA-), were analyzed by immunoprecipitation (IP) and metabolically labeled proteins and for anti-Rpp25 antibodies (n = 50) by a chemiluminescent immunoassay (CLIA) and Rpp25 ELISA.

RESULTS

Anti-Th/To antibodies occurred in 19/53 (36%), as determined by IP, and were the most common autoantibody in ANA+/ENA- SSc. Of those samples, 50/53 were available for additional testing by CLIA and ELISA. Anti-Rpp25 antibodies were detected in 12 (24% CLIA) or 10 (20% ELISA) of 50 patients. Receiver-operating characteristic curve analysis showed similar discrimination between Th/To IP-positive (n = 19) and -negative samples (n = 31) by CLIA and ELISA (area under the curve 0.90 vs 0.87; p = 0.6691). The positive percent agreement between IP and CLIA or ELISA was 12/19 (63.2%, 95% CI 38.4-83.7%) or 10/19 (52.6%, 95% CI 73.3-94.2%), respectively. Negative percent agreement was 100% for both assays.

CONCLUSION

Autoantibodies to the Th/To autoantigen are important in patients with SSc who have been considered negative for SSc-specific or SSc-associated antibodies by widely available commercial assays. Rpp25 can be considered a major target of anti-Th/To antibodies. Assays detecting anti-Th/To and anti-Rpp25 antibodies may be important in SSc.

Rpp25 is a major target of autoantibodies to the Th/To complex as measured by a novel chemiluminescent assay

Introduction

Autoantibodies to the Th/To antigen have been described in systemic sclerosis (SSc) and several proteins of the macromolecular Th/To complex have been reported to react with anti-Th/To antibodies. However, anti-Th/To has not been clinically utilized due to unavailability of commercial tests. The objective of the present study is to evaluate the newly developed ELISA and chemiluminescent immunoassay (CLIA) to measure autoantibodies to Rpp25 (a component of the Th/To complex) using immunoprecipitation (IP) as the reference method.

Methods

The first cohort consisted of 123 SSc patients including 7 anti-Th/To positive samples confirmed by IP. Additional seven anti-Th/To positive samples from non-SSc patients were also tested. For evaluation of the QUANTA Flash Rpp25 CLIA (research use only), 8 anti-Th/To IP positives, a cohort of 70 unselected SSc patients and sera from various disease controls (n = 357) and random healthy individuals (n = 10) were studied.

Results

Anti-Rpp25 antibodies determined by ELISA were found in 11/14 anti-Th/To IP positive but only in 1/156 (0.6%) negative samples resulting in a positive percent agreement of 78.6% (95% confidence interval [CI] 49.2, 95.3%) and a negative percent agreement of 99.4% (95% CI 96.4, 100.0%). To verify the results using a second method, 53 samples were tested by ELISA and CLIA for anti-Rpp25 reactivity and the results were highly correlated (rho = 0.71, 95% CI 0.56, 0.81; P < 0.0001). To define the cutoff of the CLIA, anti-Th/To IP positive and negative sera were tested using the anti-Rpp25 CLIA. At the cutoff selected by receiver operating characteristic (ROC) analysis 8/8 (100.0%) of the anti-Th/To positive sera but only 2/367 (0.5%) of the controls were positive for anti-Rpp25 antibodies. The positive and negative percent agreements were 100.0% (95% CI 63.1, 100.0%) and 99.5% (95% CI 98.0, 99.9%), respectively. In the disease cohorts 2/70 (2.9%) of the SSc patients were positive for anti-Rpp25 antibodies compared to 2/367 (0.5%) of the controls (P = 0.032). ROC analysis showed discrimination between SSc patients and controls with an area under the curve value of 0.732 (95% CI 0.655, 0.809).

Conclusion

Rpp25 is a major target of autoantibodies to the Th/To autoantigen complex. Further studies are needed to evaluate the clinical utility of the new assays.

Systemic sclerosis: demographic, clinical and serological features in 100 Iranian patients

To evaluate demographic, clinical and laboratory features associated with scleroderma-specific auto-antibodies. Sera of 100 patients with systemic sclerosis (SSc) were analyzed by an indirect immunofluorescence technique with HEp-2 cells as a substrate. Specific ANA such as anti-centromere antibodies (ACA), anti-topoisomerase (TOPO), anti-RNA polymerase III (Pol 3), anti-U3-RNP (U3-RNP), anti-Th/To (Th/To) and anti-PM/Scl (PM/Scl) were detected by line immunoassay and anti-U1-RNP (U1-RNP) by ELISA. Frequency of clinical features associated with a specific antibody group was reported cumulatively over the follow-up period. Frequency of specific clinical features was compared across the two disease subtype including limited cutaneous (lcSSc) or diffuse cutaneous (dcSSc) as well as the auto-antibody groups. Ninety-four percent of patients were ANA positive with significant higher skin score, Raynauds and digital ulcer/gangrene. Anti-TOPO was detected in 71% of all patients, in 90.5% of dcSSC and in 65.8% of lcSSc. Anti-TOPO was significantly associated with dcSSc, higher skin score, digital ulcer/gangrene, pulmonary fibrosis, DLCO <70%. U1-RNP antibody was associated with lower fibrosis in lung. ACA was positive in 7% of patients and exclusively in those with lcSSc. We did not find association between gender and presence of auto-antibodies. Anti-TOPO antibody had a high prevalence in contrast to low prevalence of ACA antibody. There were no differences in clinical subtypes of the disease in patients with positive anti-TOPO and positive ACA. Differences in prevalence of auto-antibodies are suggestive of further genetic study.

Relationship of other cytoplasmic ribonucleoprotein bodies (cRNPB) to GW/P bodies

GW/P body components are involved in the post-transcriptional -processing of messenger RNA (mRNA) through the RNA interference and 5' → 3' mRNA degradation pathways, as well as functioning in mRNA transport and stabilization. It is currently thought that the relevant mRNA silencing and degrading factors are partitioned to these cytoplasmic microdomains thus effecting post-transcriptional regulation and the prevention of accidental degradation of functional mRNA. Although much attention has focused on GW/P bodies, a variety of other cytoplasmic RNP bodies (cRNPB) also have highly specialized functions and have been shown to interact or co-localize with components of GW/P bodies. These cRNPB include neuronal transport RNP granules, stress granules, RNP-rich cytoplasmic germline granules or chromatoid bodies, sponge bodies, cytoplasmic prion protein-induced RNP granules, U bodies and TAM bodies. Of clinical relevance, autoantibodies directed against protein and miRNA components of GW/P bodies have been associated with autoimmune diseases, neurological diseases and cancer. Understanding the molecular function of GW/P bodies and their interactions with other cRNPB may provide clues to the etiology or pathogenesis of diseases associated with autoantibodies directed to these structures. This chapter will focus on the similarities and differences of the various cRNPB as an approach to understanding their functional relationships to GW/P bodies.

Anti-Th/To Are Common Antinucleolar Autoantibodies in Italian Patients with Scleroderma

Objective.

Patients with scleroderma (systemic sclerosis; SSc) can be classified into subsets based on autoantibody profile and clinical features. Specificities such as anti-Th/To and anti-fibrillarin (U3RNP) are detectable mainly by immunoprecipitation (IP), which is not widely used in clinical laboratories. We examined the autoantibody profiles and clinical manifestations in a cohort of Italian patients with SSc, focusing on anti-Th/To and anticentromere (ACA) antibodies, associated with limited cutaneous SSc (lcSSc).

Methods.

Sera from 216 consecutive patients with SSc were tested for ACA (by indirect immunofluorescence), antitopoisomerase I (topo I; by counterimmunoelectrophoresis), and anti-RNA polymerase III (RNAPIII; by ELISA). Forty-one sera negative for these specificities were tested by IP analysis of proteins (35S-methionine labeled K562 cell extract) and RNA (silver staining).

Results.

Among 216 SSc patients analyzed, anti-topo I, ACA, and anti-RNAPIII were detected in 38% (81/216), 31% (67/216) and 7% (15/216), respectively. Among 41 sera negative for ACA, anti-topo I, and anti-RNAPIII and which were tested by IP, 14 were nucleolar stain-positive. Eight out of 14 (57%) showed anti-Th/To reactivity, but no anti-U3RNP was found. In comparison with ACA-positive patients, anti-Th/To-positive patients were younger (p = 0.0046) and more commonly were male (p = 0.0006). All 8 anti-Th/To-positive and all but one ACA-positive patients had lcSSc. Interstitial lung disease (ILD) and pericarditis were more frequent in anti-Th/To-positive patients.

Conclusion.

Anti-Th/To are common in antinucleolar antibody-positive Italian patients with SSc. Anti-Th/To and ACA patients had lcSSc, with excellent prognosis. The anti-Th/To group had frequent pericarditis and ILD, although impairment of pulmonary function appeared mild.

Clinical interpretation of antinuclear antibody tests in systemic rheumatic diseases

Autoantibody tests have been used extensively in diagnosis and follow-up of patients in rheumatology clinics. Immunofluorescent antinuclear antibody test using HEp-2 cells is still considered the gold standard for screening of autoantibodies, and most of specific autoantibodies are currently tested by ELISA as a next step. Among the many autoantibody specificities described, some have been established as clinically useful diagnostic markers and are included in the classification criteria of diseases. Despite a long history of routine tests and attempts to standardize such assays, there are still limitations and problems that clinicians need to be aware of. Clinicians should be able to use autoantibody tests more efficiently and effectively with a basic knowledge on the significance of and potential problems in autoantibody tests.

The clinical relevance of serum antinuclear antibodies in Japanese patients with systemic sclerosis

Background

Systemic sclerosis (SSc) is a connective tissue disorder with excessive fibrosis of the skin and various internal organs. Although SSc is a heterogeneous disease, it has been reported that the particular antinuclear antibodies (ANA) are often indicative of clinical features, disease course and overall severity.

Objective

To clarify the association of clinical and prognostic features with serum ANA in Japanese patients with SSc.

Methods

We studied 203 Japanese patients diagnosed with SSc, who visited our hospital during the period 1983–2005. Six SSc-related ANA were identified using indirect immunofluorescence, double immunodiffusion and immunoprecipitation assays.

Results

Patients with SSc were classified into six ANA-based subgroups and a group without ANA. As expected, antitopoisomerase I antibody (Ab, n = 64), anti-RNA polymerases (RNAP) Ab (n = 12) and anti-U3 RNP Ab (n = 5) were associated with diffuse cutaneous SSc, whereas anticentromere Ab (ACA, n = 75), anti-Th/To Ab (n = 7) and anti-U1 RNP Ab (n = 10) were frequently detected in patients with limited cutaneous SSc. Clinical features of the ANA-negative group (n = 10) were heterogeneous. Consistent with previous findings in Caucasian and/or black African patients, antitopoisomerase I Ab was associated with the involvement of vascular and pulmonary fibrosis, leading to decreased survival rate. However, no patients with anti-RNAP Ab developed renal crisis and the frequency of isolated pulmonary hypertension in patients with ACA, anti-Th/To Ab or anti-U3 RNP Ab was similar to that in other ANA-based subgroups.

Conclusion

These results indicate that the clinical relevance of SSc-related ANA in Japanese patients differs in some aspects from that in Caucasian and/or black African patients.

HLA-associated production of anti-DFS70/LEDGF autoantibodies and systemic autoimmune disease

Autoantibodies against DFS70/LEDGF, which is also known as an important partner of HIV-1 integrase, are found in 10% of healthy Japanese people, but in only approximately 2% of patients with systemic autoimmune disease (SAD). We wished to characterize the association of HLA class II alleles with the presence of autoantibodies against this molecule. MHC class II genes (DR, DQ, and DP alleles) were analyzed by the polymerase chain reaction-sequence specific primer method in 24 individuals with anti-DFS70 antibodies. The frequencies of HLA-DRB1*0410, -DQB1*0402, and -DPB1*0301 were increased in anti-DFS70 Ab-positive patients, while HLA-DQB1*0302 was decreased compared to Japanese controls. All anti-DFS70 Ab-positive individuals expressed at least one HLA-DQB1 allele with an aspartic acid at residue 57. The immunogenetic background of Japanese individuals with anti-DFS70 antibodies differs from that of patients with SAD. HLA class II genes influence the production of anti-DFS70 antibodies among individuals with various clinical manifestations.

Autoantibodies in systemic sclerosis and fibrosing syndromes: clinical indications and relevance

PURPOSE OF REVIEW

Systemic sclerosis, or scleroderma, is associated with a variety of autoantibodies, each of them having their own clinical associations. The fibrosing disorders, other than systemic sclerosis, represent a diverse group of diseases with systemic or localized effect and with limited understanding of their pathogenesis. The purpose of this review is to analyze the literature on the clinical usefulness of examining serum autoantibodies in patients with known or suspected scleroderma and fibrosing disorders.

RECENT FINDINGS

Studies on autoantibodies within the past year highlight their clinical utility in systemic sclerosis. Anticentromere antibodies are most often seen with limited cutaneous involvement and lower frequency of pulmonary fibrosis and lower mortality (despite an increased risk for pulmonary hypertension) compared with anti-Scl-70 and antinucleolar antibodies. Anti-Scl-70 antibodies are associated with diffuse cutaneous involvement, increased frequency of pulmonary fibrosis, and higher mortality. The anti-polymyositis-scleroderma autoantibody is associated with the polymyositis-scleroderma overlap syndrome. Anti-Th/To antibodies are associated with milder skin and systemic involvement but with more severe pulmonary fibrosis and overall worse prognosis. Anti-RNA-polymerase family antibodies and antifibrillarin antibodies are predictive of diffuse cutaneous and systemic involvement and greater mortality. Less specific autoantibodies for systemic sclerosis and limited data on some other autoantibodies limit their clinical utility in patients with systemic sclerosis. For the most part, the association between autoantibodies and fibrosing disorders other than systemic sclerosis remains inconclusive.

SUMMARY

Autoantibodies in systemic sclerosis provide important and prognostic information and are useful in defining clinical subsets of the disease. When used appropriately, they can be a useful instrument in the management of scleroderma.

Lack of circulating autoantibodies to bone morphogenetic protein receptor-II or activin receptor-like kinase 1 in mixed connective tissue disease patients with pulmonary arterial hypertension

OBJECTIVES

To examine whether autoantibodies against bone morphogenetic protein receptor-II (BMPR-II) or activin receptor-like kinase 1 (ALK-1) are associated with pulmonary arterial hypertension (PAH) in patients with mixed connective tissue disease (MCTD).

METHODS

We studied sera from 37 MCTD patients with or without PAH, six patients with idiopathic PAH, and 30 healthy controls. Circulating anti-BMPR-II and anti-ALK-1 antibodies were detected using immunoprecipitation of recombinant antigens generated by in vitro transcription/translation and indirect immunofluorescence of cultured cells that were induced to express these antigens by gene transfer. Anti-BMPR-II antibodies were further examined by immunoprecipitation and immunoblotting using a recombinant fragment of the extracellular domain of BMPR-II.

RESULTS

Serum anti-BMPR-II and anti-ALK-1 autoantibodies were not detected in MCTD patients irrespective of the presence or absence of PAH, or in patients with idiopathic PAH.

CONCLUSIONS

Our finding does not support the hypothesis that autoantibody-mediated dysregulation of signals through BMPR-II or ALK-1 contributes to the development of PAH in patients with connective tissue diseases.

Antibodies in scleroderma: direct pathogenicity and phenotypic associations

Scleroderma is an autoimmune disease involving endothelial cell damage and fibroblast overproduction of extracellular matrix. Several autoantibodies present in the sera of patients with scleroderma, including anti-endothelial cell, antifibroblast, anti-matrix metalloproteinase, and antifibrillin-1 antibodies, may directly contribute to disease pathogenesis. Scleroderma also is characterized by the presence of antinuclear and antinucleolar antibodies, which correlate with particular phenotypes. These include antitopoisomerase-I, anticentromere, antihistone, anti-polymyositis/scleroderma, anti-Th/To, anti-U3-small nucleolar ribonucleoprotein particle, anti-U1-small nuclear ribonucleoprotein particle, anti-RNA polymerase, and anti-B23 antibodies. Other antibodies classically associated with other autoimmune diseases, such as antiphospholipid, antineutrophil cytoplasmic, and antimitochondrial antibodies, also have been described in patients with scleroderma. This review will summarize the various autoantibodies associated with scleroderma, their putative pathogenic roles, and their phenotypic correlations.

Autoantigenicity of nucleolar complexes

Autoantibodies targeting nucleolar autoantigens (ANoA) are most frequently found in sera from patients with systemic sclerosis (SSc, also designated scleroderma) or with SSc overlap syndromes. During the last decade an extensive number of nucleolar components have been identified and this allowed a more detailed analysis of the identity of nucleolar autoantigens. This review intends to give an overview of the molecular composition of the major (families of) autoantigenic nucleolar complexes, to provide some insight into their functions and to summarise the data concerning their autoantigenicity.

Classic pars planitis: strong correlation of class II genes with gender and some clinical features in Mexican mestizos

The purpose of this study was the investigation of human leukocyte antigen (HLA) genes in Mexicans with classical Pars Planitis (CPP). Seventy-nine unrelated patients and 204 healthy controls were studied. HLA-A, -B, and -C typing was done on T cells isolated with immunomagnetic beads. HLA-DRB1, -DQA1, and -DQB1 loci were typed by polymerase chain reaction-sequence-specific oligonucleotide probes. The significance and strength of HLA associations were assessed. Stratification analyses were performed to analyze correlations between HLA alleles and clinical manifestations or gender. The mean age of CPP patients was 10 years old. The disease was recurrent (21.3%); 58% were males and 89.6% were bilaterally affected. A 3-year follow-up demonstrated no other associated disease. DRB1*0802 was significantly increased (odds ratio [OR] = 2.8, etiologic fraction [EF] = 18.96%). In females, HLA-B51 (OR = 9.8) was associated with nonsymmetrical onset and HLA-Cw1 (OR = 4.7) with symmetrical onset; DRB1*0802 was increased in males (OR = 3.9, p =5.0 E-05, EF = 38.3%) and contributed to their symmetrical onset (OR = 4.6, p =4.6 E-06, EF = 29.4%). Corneal peripheral endotheliopathy correlated with DQB1*0602 in females (OR = 17, EF = 47.1%). A susceptibility allele of Amerindian ancestry is responsible for juvenile CPP in Mexicans; HLA-B locus contributes to severity in females and DRB1*0802 in males. CPP should be classified as an heterogeneous illness taking into account ethnicity, and clinical and genetic characteristics.

The clinical relevance of autoantibodies in scleroderma

Scleroderma (systemic sclerosis) is associated with several autoantibodies, each of which is useful in the diagnosis of affected patients and in determining their prognosis. Anti-centromere antibodies (ACA) and anti-Scl-70 antibodies are very useful in distinguishing patients with systemic sclerosis (SSc) from healthy controls, from patients with other connective tissue disease, and from unaffected family members. Whereas ACA often predict a limited skin involvement and the absence of pulmonary involvement, the presence of anti-Scl-70 antibodies increases the risk for diffuse skin involvement and scleroderma lung disease. Anti-fibrillarin autoantibodies (which share significant serologic overlap with anti-U3-ribonucleoprotein antibodies) and anti-RNA-polymerase autoantibodies occur less frequently and are also predictive of diffuse skin involvement and systemic disease. Anti-Th/To and PM-Scl, in contrast, are associated with limited skin disease, but anti-Th/To might be a marker for the development of pulmonary hypertension. Other autoantibodies against extractable nuclear antigens have less specificity for SSc, including anti-Ro, which is a risk factor for sicca symptoms in patients with SSc, and anti-U1-ribonucleoprotein, which in high titer is seen in patients with SSc/systemic lupus erythematosus/polymyositis overlap syndromes. Limited reports of other autoantibodies (anti-Ku, antiphospholipid) have not established them as being clinically useful in following patients with SSc.