CD40-TRAF Signaling Upregulates CX3CL1 and TNF-α in Human Aortic Endothelial Cells but Not in Retinal Endothelial Cells

• Published in: PloS one 2015-12, Vol.10 (12), p.e0144133
• Main Authors: Greene, Jennifer A, Portillo, Jose-Andres C, Lopez Corcino, Yalitza, Subauste, Carlos S
• Format: Article
• Language: English
• Subjects: Aorta; Aorta - cytology; Aorta - metabolism; Atherosclerosis; Autophagy; Binding sites; CD154 antigen; CD40 antigen; CD40 Antigens - genetics; CD40 Antigens - metabolism; CD40 Ligand - metabolism; CD40L protein; Cells, Cultured; Chemokine CCL2 - biosynthesis; Chemokine CX3CL1 - biosynthesis; Chemokines; Diabetes; Diabetes mellitus; Diabetic retinopathy; Endothelial cells; Endothelium, Vascular - metabolism; Gene expression; Human behavior; Human Umbilical Vein Endothelial Cells; Humans; Infectious diseases; Inflammation; Intercellular adhesion molecule 1; Intercellular Adhesion Molecule-1 - biosynthesis; Ligands; Medicine; Monocyte chemoattractant protein 1; Mutation; Neointima - pathology; Pathogenesis; Plaque, Atherosclerotic - pathology; Protein expression; Proteins; Recruitment; Retina; Retina - cytology; Retina - metabolism; Retinopathy; Secretion; Signal Transduction; Signaling; TRAF2 protein; TRAF6 protein; Tumor Necrosis Factor Receptor-Associated Peptides and Proteins - metabolism; Tumor necrosis factor receptors; Tumor Necrosis Factor-alpha - biosynthesis; Tumor necrosis factor-TNF; Tumor necrosis factor-α
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0144133

CD40, CX3CL1 and TNF-α promote atheroma and neointima formation. CD40 and TNF-α are also central to the development of diabetic retinopathy while CX3CL1 may play a role in the pathogenesis of this retinopathy. The purpose of this study was to examine whether CD40 ligation increases CX3CL1 and TNF-α protein expression in human endothelial cells from the aorta and retina. CD154 (CD40 ligand) upregulated membrane-bound and soluble CX3CL1 in human aortic endothelial cells. CD154 triggered TNF-α production by human aortic endothelial cells. TNF Receptor Associated Factors (TRAF) are key mediators of CD40 signaling. Compared to human aortic endothelial cells that express wt CD40, cells that express CD40 with a mutation that prevents TRAF2,3 recruitment, or CD40 with a mutation that prevents TRAF6 recruitment exhibited a profound inhibition of CD154-driven upregulation of membrane bound and soluble CX3CL1 as well as of TNF-α secretion. While both CD154 and TNF-α upregulated CX3CL1 in human aortic endothelial cells, these stimuli could act independently of each other. In contrast to human aortic endothelial cells, human retinal endothelial cells did not increase membrane bound or soluble CX3CL1 expression or secrete TNF-α in response to CD154 even though CD40 ligation upregulated ICAM-1 and CCL2 in these cells. Moreover, TNF-α did not upregulate CX3CL1 in retinal endothelial cells. In conclusion, CD40 ligation increases CX3CL1 protein levels and induces TNF-α production in endothelial cells. However, endothelial cells are heterogeneous in regards to these responses. Human aortic but not retinal endothelial cells upregulated CX3CL1 and TNF-α in response to CD40 ligation, as well as upregulated CX3CL1 in response to TNF-α. These dissimilarities may contribute to differences in regulation of inflammation in large vessels versus the retina.