Aging-induced isoDGR-modified fibronectin activates monocytic and endothelial cells to promote atherosclerosis

• Main Authors: Park, Jung Eun, JebaMercy, Gnanasekaran, Pazhanchamy, Kalailingam, Guo, Xue, Ngan, SoFong Cam, Liou, Ken Cheng Kang, Soe, Lynn EinSi, Ng, Ser Sue, Meng, Wei, Lim, Su Chi, Leow, Melvin Khee-Shing, Richards, A. Mark, Pennington, Daniel J., de Kleijn, Dominique P. V., Sorokin, Vitaly, Ho, Hee Hwa, McCarthy, Neil E., Sze, Siu Kwan
• Other Authors: School of Biological Sciences
• Format: Article
• Language: English
• Published: 2022
• Subjects: Science::Biological sciences; Science::Medicine; Atherosclerosis; Vascular Inflammation
• Online Access: https://hdl.handle.net/10356/159531
• Institution: Nanyang Technological University

Background and aims: Aging is the primary risk factor for cardiovascular disease (CVD), but the mechanisms underlying age-linked atherosclerosis remain unclear. We previously observed that long-lived vascular matrix proteins can acquire 'gain-of-function' isoDGR motifs that might play a role in atherosclerotic pathology. Methods: IsoDGR-specific mAb were generated and used for ELISA-based measurement of motif levels in plasma samples from patients with coronary artery diseases (CAD) and non-CAD controls. Functional consequences of isoDGR accumulation in age-damaged fibronectin were determined by bioassay for capacity to activate monocytes, macrophages, and endothelial cells (signalling activity, pro-inflammatory cytokine expression, and recruitment/adhesion potential). Mice deficient in the isoDGR repair enzyme PCMT1 were used to assess motif distribution and macrophage localisation in vivo. Results: IsoDGR-modified fibronectin and fibrinogen levels in patient plasma were significantly enhanced in CAD and further associated with smoking status. Functional assays demonstrated that isoDGR-modified fibronectin activated both monocytes and macrophages via integrin receptor ‘outside in’ signalling, triggering an ERK:AP-1 cascade and expression of pro-inflammatory cytokines MCP-1 and TNFα to drive additional recruitment of circulating leukocytes. IsoDGR-modified fibronectin also induced endothelial cell expression of integrin β1 to further enhance cellular adhesion and matrix deposition. Analysis of murine aortic tissues confirmed accumulation of isoDGR-modified proteins co-localised with CD68+ macrophages in vivo. Conclusions: Age-damaged fibronectin features isoDGR motifs that increase binding to integrins on the surface of monocytes, macrophages, and endothelial cells. Subsequent activation of ‘outside-in’ signalling elicits a range of potent cytokines and chemokines that drive additional leukocyte recruitment to the developing atherosclerotic matrix.