Autoantibody Profiling on Human Proteome Microarray for Biomarker Discovery in Cerebrospinal Fluid and Sera of Neuropsychiatric Lupus

Chaojun Hu,Fengchun Zhang,Guang Song,Lin Wu,Yongzhe Li,Hua Chen,Qiang Shan,Wei Huang,Xuan Zhang,Heng Zhu,Ping Li,Masataka Kuwana

doi:10.1371/journal.pone.0126643

Abstract

Autoantibodies in cerebrospinal fluid (CSF) from patients with neuropsychiatric systemic lupus erythematosus (NPSLE) may be potential biomarkers for prediction, diagnosis, or prognosis of NPSLE. We used a human proteome microarray with~17,000 unique full-length human proteins to investigate autoantibodies associated with NPSLE. Twenty-nine CSF specimens from 12 NPSLE, 7 non-NPSLE, and 10 control (non-systemic lupus erythematosus)patients were screened for NPSLE-associated autoantibodies with proteome microarrays. A focused autoantigen microarray of candidate NPSLE autoantigens was applied to profile a larger cohort of CSF with patient-matched sera. We identified 137 autoantigens associated with NPSLE. Ingenuity Pathway Analysis revealed that these autoantigens were enriched for functions involved in neurological diseases (score = 43).Anti-proliferating cell nuclear antigen (PCNA) was found in the CSF of NPSLE and non-NPSLE patients. The positive rates of 4 autoantibodies in CSF specimens were significantly different between the SLE (i.e., NPSLE and non-NPSLE) and control groups: anti-ribosomal protein RPLP0, anti-RPLP1, anti-RPLP2, and anti-TROVE2 (also known as anti-Ro/SS-A). The positive rate for anti-SS-A associated with NPSLE was higher than that for non-NPSLE (31.11% cf. 10.71%; P = 0.045).Further analysis showed that anti-SS-A in CSF specimens was related to neuropsychiatric syndromes of the central nervous system in SLE (P = 0.009). Analysis with Spearman’s rank correlation coefficient indicated that the titers of anti-RPLP2 and anti-SS-A in paired CSF and serum specimens significantly correlated. Human proteome microarrays offer a powerful platform to discover novel autoantibodies in CSF samples. Anti-SS-A autoantibodies may be potential CSF markers for NPSLE.

Highlights

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by production of pathogenic autoantibodies and multiple organ and tissue damage[1]
Since the reproducibility of protein microarray data is crucial for biomarker identification, we first assessed their quality by probing a human proteome microarray, randomly selected from the same printing batch, with anti-GST monoclonal antibody (mAb)
To identify neuropsychiatric systemic lupus erythematosus (NPSLE)-specific Cerebrospinal fluid (CSF) autoantibodies, we profiled the autoimmune reactivity by incubating the human proteome microarrays with 29 individual CSF samples from 12 NPSLE, 7 non-NPSLE, and 10 non-SLE patients, and performed signal detection with Cy5-labeled anti-human immunoglobulin G (IgG) antibodies

Summary

Introduction

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease characterized by production of pathogenic autoantibodies and multiple organ and tissue damage[1]. A variety of autoantibodies have been detected in the CSF of SLE patients, including anti-glutamate receptor ε2 subunit (GluRε2)[3], anti-neuronal[4], anti-ganglioside[5], anti-glial fibrillary acidic protein[6], anti-dsDNA, anti-N-methyl-d-aspartate (NMDA) receptors[7], anti-triose-phosphateisomerase[8], anti-SSA/Ro (Anti-Sjögren’s-syndrome-related antigen A, or anti-Ro)[9], anti-ribosomal P protein[10], anti-cardiolipin[11], and anti-alphainternexin autoantibodies[12] Most of these autoantibodies can be detected in other autoimmune diseases; only a small fraction of them (such as anti-GluRε2 and antiNMDA)are associated with neuropsychiatric disorders[3, 7]. Based on the current literature, we hypothesized that there are additional autoantibodies in CSF that can be used to diagnose or predict NPSLE

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Results

Discussion

Conclusion