Bioinformatic Analysis Of Cytokine Expression Profile In Abdominal Aortic Aneurysm On Mouse Model

Objective:Abdominal aortic aneurysm(AAA)is characterized by irreversible progressive weakening and dilation of the abdominal aorta.Inflammation is considered a crucial part in its pathogenesis,indicated by significant infiltration of immune cells and upregulation of pro-inflammatory cytokines in AAA specimen of human and animal models.Identifying the inflammatory molecules and pathways in AAA pathogenesis may contribute to development of novel biomarkers and treatment methods.In the present study,we used advanced antibody array analysis to investigate the characteristics of cytokine expression profiles and pathways involved in the pathogenesis of AAA in a mouse model.The findings may provide further insights into the mechanism of AAA and help discover new candidate molecules for research and clinical application.Methods:Cytokine levels in abdominal aortic walls of Apolipoprotein E-/-mice treated with angiotensin ?(n=5)or saline control(n=5)were measured using a 200-cytokine antibody-based protein array.Statistical analysis revealed differentially expressed proteins in AAA tissue.The differentially expressed proteins were subjected for function and pathway enrichment analysis.Among them,expression newly identified AAA-related cytokines which had not been studied in AAA pathogenesis were tested by enzyme-linked immunosorbent serologic assay to confirm the results from cytokine arrays.To further indicate their possible roles in AAA pathogenesis,bivariate correlation analysis between these cytokines and protease activity was performed.The examined proteases included matrix metalloproteinase(MMP)-1,MMP-9,Cathepsin B and Cathepsin L.Results:Among the 200 cytokines tested in the array.21 cytokines fit the criteria of differentially expressed protein.Principle component analysis and clustering heatmap revealed that there was significant difference of cytokine expression profiles between control and AAA groups,and that the consistence within each group was acceptable.Function and pathway enrichment analysis indicated that leukocyte migration and positive regulation of cell adhesion were the most significant biological processes.Cytokine-cytokine receptor interaction and Jak-STAT signaling pathway were most significant in pathway enrichment analysis.Among the 21 differentially expressed proteins,7 cytokines have not previously been studied in AAA formation.Enzyme-linked immunosorbent serologic assay confirmed their differential expression in AAA.Bivariate correlation between the newly identified cytokines and protease activity in aortic tissues of all subjects revealed significant correlations between specific cytokines and proteases.Granulocyte colony-stimulating factor(G-CSF),macrophage inflammatory protein 1g(MIP-1g),cardiotrophin 1(CT-1),milk fat globule-EGF factor 8 protein(MFG-E8),interleukin 33(IL-33)and periostin were positively correlated with MMP-1,MMP-9,cathepsin B and cathepsin L.G-CSF was positively correlated with cathepsin L.Conclusion:Our data provided a comprehensive protein array study and bioinformatic analysis of differentially expressed proteins in angiotensin ? induced AAA in apolipoprotein E-/-mice,and demonstrated that cytokine profile is significantly altered in AAA.Functional analysis was performed on cytokines with altered expression.The study newly identified crucial cytokines which might be involved in the progress of AAA.Furthermore,significant correlations were found between these cytokines and protease activity,indicating the newly identified cytokines may participate in AAA pathogenesis by directly or indirectly influencing protease activities.The study provides a set of useful targets for future investigation into the molecular mechanisms and biomarkers of AAA.