Serum levels of anti-streptolysin O antibodies: their role in evaluating rheumatic diseases

Long-Term Prognostic Factors in Patients With Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: A 15-Year Multicenter Retrospective Study

Background

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a multisystem autoimmune disease with small-vessel involvement. In AAV, microscopic polyangiitis (MPA) and granulomatosis with polyangiitis (GPA) are major clinicopathologic variants. In addition, myeloperoxidase (MPO) and proteinase 3 (PR3) are major target antigens. The objective of the study was to explore the predictive factors for long-term survival in AAV patients.

Materials and Methods

A multicenter retrospective study was carried out on 407 patients between 2005 and 2020. Clinical parameters were obtained from laboratory tests including the ANCA types, antinuclear antibody (ANA), extractable nuclear antigen (ENA), anti-streptolysin O (ASO), glomerular filtration rate (GFR), and the laboratory examinations for the blood routine, liver function, renal function, and immunity, etc. The data for clinical parameters were collected from electronic medical records (EMRs), and the data for patient survival were acquired through regular follow-up. The association of clinical parameters with overall survival (OS) along with 3-year and 5-year survival rates was analyzed, and the nomogram as a predictive model was established according to the analysis results.

Results

In the present study, 336 (82.6%) patients and 46 (11.3%) patients were diagnosed with MPA and GPA, respectively. The mean and median OS for all the patients were 2,285 and 2,290 days, respectively. The 1-year, 3-year, 5-year, and 10-year cumulative survival rates for all the patients were 84.2%, 76.3%, 57.2%, and 32.4%, respectively. Univariate and multivariate survival analyses indicated that the independent prognostic factors included age, pathological categories (MPA, GPA, and other types), serum ANCA types (negative or positive for MPO and/or PR3), ANA, ASO, GFR, lymphocyte, neutrophil-to-lymphocyte ratio (NLR), and C-reactive protein (CRP), and these clinical parameters except for ASO were used to construct a nomogram. The nomogram for 3-year and 5-year survival rates had a C-index of 0.721 (95% CI 0.676-0.766). The calibration curves showed that the predicted values of the nomogram for 3-year and 5-year survival rates were generally consistent with practical observed values, and decision curve analysis (DCA) further demonstrated the practicability and accuracy of the predictive model.

Conclusion

Laboratory tests at diagnosis have great significance in the prediction of long-term survival in AAV patients.

New-Onset of Crohn's Disease Is Associated with Antistreptolysin O Positive Titers

Objective

Different infectious agents have been presumed to be candidates acting as an etiologic factor or trigger of Crohn’s disease (CD). Group A Streptococcus (GAS) is a common human infection agent that can also trigger post-infectious immune-mediated conditions. The current study aimed to examine whether the immunogenic activity induced by GAS may trigger new-onset of CD.

Methods

Data for antistreptolysin O (ASO) level, throat culture for GAS, and history of streptococcal infection were collected from 91 patients with CD that were divided into three groups including; new-onset CD, CD in remission and active CD. The data were compared with the control group.

Results

All participants had negative results of throat culture for GAS and had no history of documented streptococcal infection in the past year. Our results indicate that new-onset CD, but not CD in remission or active CD, is associated with significantly increased positive ASO compared to controls. Half of the patients in the new-onset CD group were ASO positive, which was significantly higher compared to the control group in a univariant (OR: 4.00; 95% CI 1.27–12.58; P=0.02) and multivariant analysis (OR: 4.41; 95% CI 1.35–14.37; P=0.014).

Conclusion

Our study is the first to focus on ASO levels in patients with CD and to demonstrate a significant association between ASO and new-onset of CD. Large prospective randomized controlled studies are needed to confirm the validity of this data and to further clarify the clinical significance of our findings.

Tubulointerstitial Nephritis Associated with Enteritis and Sacroiliitis

The association between sacroiliitis and tubulointerstitial nephritis has not been reported. A 28-year-old man with a history of clinically diagnosed ulcerative colitis (4 years earlier) and sacroiliitis (6 months earlier) developed renal dysfunction 9 months ago, which progressed thereafter. We diagnosed him with tubulointerstitial nephritis by a renal biopsy, for which we started steroid therapy. Subsequently, his renal dysfunction, sacroiliitis, and enteritis partially improved. A pathological analysis of the kidney and intestine revealed lymphocyte infiltration and non-caseating granuloma in both organs. The similarities in the pathological findings and treatment response suggested a pathogenetic association between tubulointerstitial nephritis, enteritis, and sacroiliitis.

How to use antistreptolysin O titre

Group A streptococcus (GAS) is the cause of a wide range of acute suppurative and, following a latent period, non-suppurative diseases such as rheumatic fever and poststreptococcal glomerulonephritis. Diagnosis of the latter group requires evidence of preceding GAS infection. The bacteria produce a range of extracellular antigens, including streptolysin O, which induce an antibody response in the host. A rise in antistreptolysin O titre (ASOT) is indicative of preceding GAS infection. In clinical practice, often only a single ASOT measurement is available and its timing in relation to a possible GAS infection is unknown. Interpretation of the result in this context is liable to misdiagnosis. In order to optimise diagnosis of preceding GAS infection, at least two sequential ASOT measurements, together with simultaneous assay for anti-DNase B, a second antistreptococcal antibody, is recommended.

Pore-forming compounds as signal transduction elements for highly sensitive biosensing

Pore-forming compounds are attracting much attention due to the signal transduction ability for the development of highly sensitive biosensing. In this review, we describe an overview of the recent advances made by our group in the design of molecular sensing interfaces of spherical and planar lipid bilayers and natural bilayers. The potential uses of pore-forming compounds, such as gramicidin and MCM-41, in lipid bilayers and natural glutamate receptor channels in biomembrane are presented.