Meanwhile, blood urea nitrogen
level, serum creatinine, proteinuria, blood routine tests and immunological parameters including serum C3, C4, immunoglobulins, CRP and autoantibodies (anti-dsDNA, AnuA and anti-Sm) levels were also analysed. For the control group, 43 age- and sex-matched normal individuals were included as healthy controls (HC, 41 women, two men; age of 33.6 ± 5.5). The study protocol was designed in compliance with Helsinki Declaration and approved by the Ethics SCH727965 molecular weight Board of Provincial Hospital Affiliated to Shandong University. Each participant signed an informed consent for participating in this study. Assay for sRAGE. Plasma was collected using EDTA as an anticoagulant, aliquoted and stored at −80 °C. The level of sRAGE was detected using an ELISA kit (R&D systems, Minneapolis, MN, USA) according to the manufacturer’s protocol. ELISA plates coated with monoclonal antibody specific for RAGE (extracellular domain) were used for quantitative analysis of sRAGE in plasma. The minimum detectable level of sRAGE was 4 pg/ml. As indicated in the datasheet, no significant cross-reactivities to EN-RAGE, FXR agonist HMGB1, S100A10 or S100B were observed. Assays for autoantibodies.
Antinuclear autoantibodies (ANA) were detected by ANA mosaic indirect immuno-fluorescence assay kit (Euroimmun Medizinische Labordiagnostika AG, Lübeck, Germany). Antibodies of the IgG class against dsDNA, Sm and nucleosome were detected by Methane monooxygenase ELISA kits from EUROIMMUN
according to the manufacturer’s instructions. The upper limit for anti-dsDNA recommended by EUROIMMUN was 100 International Units (IU)/ml and ≥100 IU/ml is regarded to be positive, while the upper limit for anti-Sm and AnuA was 20 Relative Units (RU)/ml. Measurement of C3, C4, IgA, IgG, IgM and CRP. Blood C3, C4, IgA, IgG, IgM and CRP were detected by nephelometric assay kits from Dade Behring Marburg GmbH (Germany) according to the manufacturer’s instructions. Quantification of proteinuria and urinalysis. Proteinuria was quantified by Olympus AU5400 (Olympus, Japan). Urinalysis was performed by Urisys 2400 Urinalysis System from Roche Diagnostics (USA). Statistical analysis. Data were expressed as the Mean ± SEM. Comparisons between patients with SLE and HC were analysed by the Student’s t-test, One-way anova. Correlation analysis was performed by Spearman’s rank correlation test. All analyses were performed by spss (version 17.0, SPSS Inc., Chicago, Illinois, USA). A two-tailed P-value <0.05 was considered as statistically significant. Characteristics of patients with SLE and HC are shown in Tables 1 and 2. The average level of plasma sRAGE in patients with SLE (842.7 ± 50.6 pg/ml) was significantly lower than that in HC (1129.3 ± 80.1 pg/ml) (P = 0.003, Fig. 1A).