Differential expressions of plasma proteins in systemic lupus erythematosus patients identified by proteomic analysis.

INTRODUCTION: Systemic lupus erythematosus (SLE) is a chronic and complex autoimmune disease with a wide range of clinical manifestations that affects multiple organs and tissues. Therefore the differential expression of proteins in the serum/plasma have potential clinical applications when treating SLE.

METHODS: We have compared the plasma/serum protein expression patterns of nineteen active SLE patients with those of twelve age-matched and gender-matched healthy controls by proteomic analysis. To investigate the differentially expressed proteins among SLE and controls, a 2-dimensional gel electrophoresis coupled with high-resolution liquid chromatography tandem mass spectrometry was performed. To further understand the molecular and biological functions of the identified proteins, PANTHER and Gene Ontology (GO) analyses were employed.

RESULTS: A total of 14 significantly expressed (p < 0.05, p < 0.01) proteins were identified, and of these nine were up-regulated and five down-regulated in the SLE patients. The functional enrichment analysis assigned the majority of the identified proteins including alpha 2 macroglobulin, complement C4, complement factor H, fibrinogen beta chain, and alpha-1-antitrypsin were part of the complement/coagulation cascade, which is an important pathway that plays a crucial role in SLE pathogenesis. In addition to these proteins the differential expressions of ceruloplasmin, transthyretin, and haptoglobin play a potential role in the renal system abnormalities of SLE.

CONCLUSION: Therefore, the identified differentially expressed proteins are relevant to SLE patient's cohort. Most importantly the up-regulated proteins might be the potential candidates for renal system involvement in SLE disease pathogenesis. In order to confirm the diagnostic/therapeutic potential of the identified proteins, future validation studies are required.