Points to consider in renal involvement in systemic sclerosis

Identification of Anti-SNRPA as a Novel Serological Biomarker for Systemic Sclerosis Diagnosis

Systemic sclerosis (SSc) is a systemic autoimmune disorder that leads to vasculopathy and tissue fibrosis. A lack of reliable biomarkers has been a challenge for clinical diagnosis of the disease. We employed a protein array-based approach to identify and validate SSc-specific autoantibodies. Phase I involved profiled autoimmunity using human proteome microarray (HuProt arrays) with 90 serum samples: 40 patients with SSc, 30 patients diagnosed with autoimmune diseases, and 20 healthy subjects. In Phase II, we constructed a focused array with candidates identified antigens and used this to profile a much larger cohort comprised of serum samples. Finally, we used a western blot analysis to validate the serum of validated proteins with high signal values. Bioinformatics analysis allowed us to identify 113 candidate autoantigens that were significantly associated with SSc. This two-phase strategy allowed us to identify and validate anti-small nuclear ribonucleoprotein polypeptide A (SNRPA) as a novel SSc-specific serological biomarker. The observed positive rate of anti-SNRPA antibody in patients with SSc was 11.25%, which was significantly higher than that of any disease control group (3.33%) or healthy controls (1%). In conclusion, anti-SNRPA autoantibody serves as a novel biomarker for SSc diagnosis and may be promising for clinical applications.

Transfer of PBMC From SSc Patients Induces Autoantibodies and Systemic Inflammation in Rag2-/-/IL2rg-/- Mice

Objective

The contribution of sustained autologous autoantibody production by B cells to the pathogenesis of systemic sclerosis (SSc) and granulomatosis with polyangiitis (GPA) is not fully understood. To investigate this, a humanized mouse model was generated by transferring patient-derived peripheral blood mononuclear cells (PBMC) into immunocompromised mice.

Methods

PBMC derived from patients with SSc and GPA as well as healthy controls (HD) were isolated, characterized by flow cytometry, and infused into Rag2^-/-/IL2rg^-/- mice. In addition, PBMC from SSc patients treated with rituximab were transferred into mice. Twelve weeks later, human autoantibodies were determined in blood of the recipient mice and affected tissues were analyzed for pathological changes by histology and immunohistochemistry.

Results

Mice engrafted with PBMC derived from SSc patients developed autoantibodies such as antinuclear antibodies (ANA) mimicking the pattern of the respective donors. Moreover, cellular infiltrates dominated by B cells were observed in lung, kidney and muscles of the recipient mice. By contrast, PBMC derived from HD or GPA patients survived in recipient mice after transfer, but neither human autoantibodies nor inflammatory infiltrates in tissues were detected. Furthermore, these pathological changes were absent in mice transferred with PBMC from rituximab-treated SSc patients.

Conclusion

This humanized mouse model is indicative for cross-reactivity of human lymphocytes to murine autoantigens and argues for a pivotal role of B cells as well as of sustained autoimmunity in the pathogenesis of SSc. It provides a powerful tool to study interstitial lung disease and so far, under-recognized disease manifestations such as myositis and interstitial nephritis.

ANCA-associated vasculitis overlaps with systemic sclerosis: a case report and literature review

Background

Systemic sclerosis (SSc) and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) both affect the kidney and may cause renal failure. Treatment of AAV is dramatically different from that of SSc renal crisis (SRC). Kidney biopsy is not recommended for diagnosing SRC, but it is the only reliable diagnostic method for AAV.

Case presentation

Here, a 49-year-old male patient with diffuse SSc presented with acute renal insufficiency and detectable ANCA with myeloperoxidase-specific antibodies. A renal biopsy revealed necrotizing glomerulonephritis and was consistent with AAV. This finding confirms the existence of AAV and SSc overlap syndrome. The patient was treated with intravenous methylprednisolone, intravenous cyclophosphamide, tandem membrane plasma exchange, and hemodialysis. After treatment, his clinical symptoms remained stable, and his creatinine and C-reactive protein (CRP) levels have remained normalized as of his most recent follow-up after hospital discharge.

Conclusions

AAV can overlap with SSc; although this condition is rare, it is associated with considerable morbidity and mortality. Therefore, it is critical to recognize AAV in the setting of worsening renal function due to SSs and provide appropriate treatment. Several clinical features are suggestive of AAV rather than SRC, but renal biopsy is required for accurate diagnosis.

Myopathy is a Risk Factor for Poor Prognosis of Patients with Systemic Sclerosis: A retrospective cohort study

To compare clinical characteristics and identify long-term outcomes of Chinese patients with systemic sclerosis (SSc) with and without muscle involvement.We retrospectively investigated the medical records, laboratory results, and computed tomography images of 204 consecutive SSc patients. Kaplan-Meier analysis was performed to determine survival rates. Patients were allocated into groups with and without myopathy.The prevalence of myopathy was 21.6%. The myopathy group was more likely to develop diffuse cutaneous involvement (90.9% vs 56%, P = .006), interstitial lung disease (90% vs 56%, P < .001), digestive system involvement (56.7% vs 29.3%, P = .001), pulmonary hypertension (29.5% vs 10.5%, P = .004), and pericardial effusion (25% vs. 10%, P = .019). Patients with myopathy had lower single-breath diffusing capacity of the lung for carbon oxide (46.5 ± 11.1 vs 57.1 ± 13.4, P < .001).Further, the myopathy group has similar results in interstitial lung disease associated higher resolution computed tomography score (186.8 ± 64.5 vs 152.3 ± 45.5, P = .037), Valentini score for disease activity (3.4 ± 0.9 vs 2.0 ± 0.9, P < .001) and modified Rodnan total skin score (19.4 ± 6.1 vs 15.1 ± 7.7, P = .002), compared with non-myopathy group. Kaplan-Meier survival analysis revealed decreased overall survival rate of the myopathy group (P = .028).SSc Patients with myopathy had more severe clinical manifestations and higher disease activity compared with those without, which affected survival rates and indicated worse prognosis.

Analysis of anti-RNA polymerase III antibodies in Chinese Han systemic sclerosis patients

OBJECTIVES

This study aimed to assess the prevalence and clinical correlation of anti-RNA polymerase III antibodies (anti-RNAP III) in Chinese Han systemic sclerosis (SSc) patients.

METHODS

Serum samples from 236 patients with SSc, 125 patients with connective tissue diseases (CTD), and 166 healthy controls (HCs), recruited from Peking Union Medical College Hospital and 21 other medical centers in China, were tested for antibodies to RNA polymerase III by means of a line immunoassay (LIA) or an enzyme-linked immunosorbent assay (ELISA) kit.

RESULTS

Anti-RNAP III antibodies were found in 14/236 SSc patients (5.93%), 1/125 (0.80%) CTD patients, and 0/166 (0.00%) HCs. The prevalence of anti-RNAP III was higher in SSc patients than in the CTD and HC groups (p = 0.02, p = 0.001, respectively). Renal crisis was significantly more common in patients with anti-RNAP III than patients without anti-RNAP III (42.9 vs. 4.1%, p < 0.0001). Gastrointestinal involvement was significantly more common in patients without anti-RNAP III than patients with anti-RNAP III (53.6 vs. 21.4%, p = 0.039). There was good agreement between the ELISA and line immunoassay (LIA) detection capabilities for anti-RNAP III.

CONCLUSIONS

The anti-RNAP III antibody, which was detected by ELISA, has diagnostic value for SSc and predictive value for SSc-related renal crisis. Both ELISA and LIA are very reliable methods for anti-RNAP III.Key Points• The prevalence of anti-RNAP III antibody was determined in Chinese SSc patients and performed ethnic differences.• The clinical association between anti-RNAP III antibody and Chinese SSc patients was evaluated in this research.• Methodological consistency of detection of anti-RNAP III antibody using commercial ELISA and LIA methods was evaluated in this research.

Systemic sclerosis: state of the art on clinical practice guidelines

Systemic sclerosis (SSc) is an orphan disease characterised by autoimmunity, fibrosis of the skin and internal organs, and vasculopathy. SSc may be associated with high morbidity and mortality. In this narrative review we summarise the results of a systematic literature research, which was performed as part of the European Reference Network on Rare and Complex Connective Tissue and Musculoskeletal Diseases project, aimed at evaluating existing clinical practice guidelines or recommendations. Only in the domains ‘Vascular & Ulcers’ (ie, non-pharmacological approach to digital ulcer), ‘PAH’ (ie, screening and treatment), ‘Treatment’ and ‘Juveniles’ (ie, evaluation of juveniles with Raynaud’s phenomenon) evidence-based and consensus-based guidelines could be included. Hence there is a preponderance of unmet needs in SSc referring to the diagnosis and (non-)pharmacological treatment of several SSc-specific complications. Patients with SSc experience significant uncertainty concerning SSc-related taxonomy, management (both pharmacological and non-pharmacological) and education. Day-to-day impact of the disease (loss of self-esteem, fatigue, sexual dysfunction, and occupational, nutritional and relational problems) is underestimated and needs evaluation.

Points to consider when doing a trial primarily involving the heart

Cardiac involvement contributes to the severity of SSc and should carefully be investigated and managed in SSc patients. Although it is commonly sub-clinical, once symptomatic it has a poor prognosis. Several complementary tools (circulating biomarkers, electrocardiography, echocardiography, scintigraphy or MRI) allow the assessment of all the various cardiac structures (endocardium, myocardium and pericardium) and heart function. Treatment remains empirical but cardiac trials in SSc can add data to the treatment of this complication.