Proteomic Profiling Of Cerebrospinal Fluid And Serum In Patients With Neuropyschiatric Systemic Lupus Erythematosus

Part one:Proteomic profiling of cerebrospinal fluid identifies biomarkers for neuropsychiatric systemic lupus erythematosusObjective:To identify neuropsychiatric systemic lupus erythematosus (NPSLE) specific cerebrospinal fluid (CSF) biomarkers and construct a decision tree model for NPSLE classification. Methods:we compared the proteomic profile of CSF from27patients with neuropsychiatric systemic lupus erythematosus (NPSLE),17patients with scoliosis and10SLE patients without neuropsychiatric symptoms (non-NPSLE), using matrix assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF-MS) combined with weak cationic exchange magnetic beads. We developed a decision tree model for NPSLE classification with biomarker patterns software, and tested the model with other independent CNS diseases (16samples). We compared the proteomic profile of CSF from17NPSLE patients between before and after NPSLE relative treatment. Results:We identified25mass-to-charge (m/z) peaks with statistically significant (p<0.05) differences between NPSLE (before treatment) and control (scoliosis plus non-NPSLE) subjects. Of them, the m/z peaks at8595,7170,7661,7740and5806were used to construct a decision tree model to distinguish NPSLE from non-NPSLE and scoliosis (considered as healthy control) patients with a sensitivity of92.6%and a specificity of92.6%based on learning data, and a specificity of81.3%based on external blind testing data. There were4m/z peaks with statistically significant (p<0.05) differences between before and after treatment in the same group of NPSLE patients. Of them, the m/z peaks at4963and8595decreased, the m/z peaks at6637and6896increased after treatment. Conclusion:Our data suggested a potential application of MALDI-TOF-MS combined with weak cationic exchange magnetic beads to profile CSF proteome, several potential CSF biomarkers were indicated to detect, diagnose and monitor NPSLE, a decision tree model for NPSLE classification was set up with high sensitivity and specificity. Part Two:Proteomic profiling of serum identifies biomarkers for neuropsychiatric systemic lupus erythematosusObjective:To identify neuropsychiatric systemic lupus erythematosus (NPSLE) specific serum biomarkers. Methods:Using MALDI-TOF-MS combined with weak cationic exchange magnetic beads, we compared the proteomic profile of serum from24patients with NPSLE,21healthy volunteers and8non-NPSLE patients; compared the proteomic profile of serum from13NPSLE patients between before and after NPSLE relative treatment; compared the same m/z discriminating peaks (p<0.05) from both serum and CSF profile of the same patients, collected at the same time. Results:We identified35discriminating peaks between NPSLE (before treatment) and healthy control subjects,13discriminating peaks between NPSLE (before treatment) and non-NPSLE subjects,15discriminating peaks between non-NPSLE and healthy control subjects. Of them, the m/z peaks at6438,8122,8690,9280,28081present to be different in all the three groups. There were2discriminating m/z peaks at4959and6189between before and after treatment, both increased after treatment.4pairs of discriminating peaks (the same m/z values) were identified from both serum and CSF profile of the same patients, respectively, their m/z values were4959(serum)&4963(CSF),4959increased after treatment, while4963decreased after treatment;5905(serum)&5866(CSF), both increased in NPSLE (before treatment);7754(serum)&7740(CSF),8581(serum)&8595(CSF), both decreased in serum and increased in CSF in NPSLE (before treatment). Conclusion:Several potential serum biomarkers were indicated to detect, diagnose and monitor NPSLE,4pairs of discriminating peaks present in both serum and CSF indicated more significant potential biomarkers in the following study and clinical practice. Part three:Identifying one protein in the proteomic signature as serum amyloid protein ABackground and Objective:Serum amyloid protein A (SAA), an acute phase protein emerging as a cytokine-like molecule with the ability to activate various proinflammatory processes in many diseases, had been identified by SELDI-TOF-MS at m/z peak of11.7kd in several serum studies. We undertook this study to prove the presence of m/z peak of11.7kd in CSF profile as SAA protein. Methods:CSF was immunoprecipitated with anti-SAA antibody, after immunoprecipitation, the proteins of supernatant and agarose beads were detected by MALDI-TOF-MS and western blot, respectively. Results:The m/z peak of11.7kd in CSF profile was validated to be SAA protein by both immunoprecipitation combining with MALDI-TOF-MS&WCX magnetic beads and immunoprecipitation combining with western blot. Conclusion:Our results indicated that SAA level of CSF elevated in neuropsychiatric systemic lupus erythematosus (NPSLE), SAA protein might be a novel biomarker for NPSLE.