P162 Extracellular vesicles from patients with ankylosing spondylitis convey proteins related to immune response: new signaling pathways?
Authors: Y Huang, T Li, S Zheng, X Huang, Q Huang, W Deng
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Career situation of first and presenting author</h3> Young investigator. <h3>Introduction</h3> Ankylosing spondylitis (AS) is a chronic inflammatory disease, whose pathogenesis is still unclear. Many studies show the proteins in extracellular vesicle (EVs) would change regularly in many diseases. However, none of study has focused on the proteins profiles of serum-derived EVs in AS patients. <h3>Objectives</h3> The study aim to detect the proteins profiles of serum-derived EVs in AS patients by Label-free-LC-MS/MS technology. <h3>Methods</h3> EVs were isolated by ExoQuick-TC<sup>TM</sup> kit. The protein contents were evaluated by Label-free-LC-MS/MS technology. Venn diagram, volcano plot, hierarchical cluster, Gene Ontologies (GO), Encyclopedia of Genes and Genomes (KEGG) pathway and Protein-Protein Interaction (PPI) network analysis were constructed. Enzyme-linked immunosorbent assay (ELISA) was used to confirm the expression of the differently-expressed proteins. <h3>Results</h3> Label-free-LC-MS/MS results indicated a total of 677 proteins were detected, of which 65 were unique to AS group, 545 were identified in both AS and control group, and 67 were unique to control group. A heat map of the hierarchical clustering revealed a clearly distinct expression of proteins in AS group, compared with control group. With the cut off criteria of |log2 (fold-change)|≥1, p≤0.01 and unique peptides ≥2, 31 up-regulated proteins and 42 down-regulated proteins were found in the AS group. Among them, Serum amyloid A-1 (SAA1) protein and Complement C4-B were highly expressed in AS group. PPI network analysis yielded a highly clustered network (clustering coefficient: 0.584), with prothrombin (F2) and c-reactive protein(CRP) as the central/hub proteins. GO analysis of the biological process indicated that the differentially expressed proteins were significantly enriched in the 'Complement activation'. GO analysis of the cellular components demonstrated that most proteins were annotated as exosome, vesicle and micro-particle. KEGG pathway analysis revealed proteins were significantly enriched in 'Complement and coagulation cascades', 'Staphylococcus aureus infection', 'Systemic lupus erythematosus' and 'PI3K-Akt signaling pathway'. ELISA demonstrated that both EVs-derived SAA1 and serum SAA1 were more abundant in AS group, showed a consistent with the Label-free-LC-MS/MS data. <h3>Conclusions</h3> Differentially expressed proteins were found in serum-derived EVs of AS patients, and the functional analysis indicated that they may potentially involved in immune response. <h3>Reference</h3> Caruso S, Poon IKH. Apoptotic cell-derived extracellular vesicles: more than just debris. <i>Front Immunol</i> 2018;9:1486. <h3>Acknowledgements</h3> This study was supported by Medical Scientific Research Foundation of Guangdong Province(No. A2017551) and Natural Science Foundation of Guangdong Province (No.2017A030313526). <h3>Disclosure of Interest</h3> None declared.