Citrullinated and Malondialdehyde–Acetaldehyde-Modified Fibrinogen Activates Macrophages and Promotes Coronary Endothelial Cell Inflammation

Individuals with rheumatoid arthritis (RA) face increased cardiovascular mortality due to heart failure (HF) complications. Post-translational modifications, such as citrullination (CIT) and malondialdehyde-acetaldehyde (MAA) adduction, are implicated in RA pathogenesis. However, their role in RA-associated HF is not well understood. This study examines the deposition of MAA and CIT in cardiac tissues of RA-HF patients and investigates how MAA and CIT adducts on fibrinogen (FIB-MAA-CIT) drive crosstalk between macrophages and endothelial cells in vitro. We demonstrated elevated MAA and CIT adducts, strong perivascular MAA-CIT co-localization, and increased perivascular collagen deposition in the myocardium of RA-HF patients compared to non-RA HF controls. Treating human coronary artery endothelial cells (HCAECs) with FIB-MAA-CIT induced upregulation of inflammatory markers including MCP-1, IL-6, ICAM-1, and VCAM-1 compared to unmodified FIB. This response was amplified when HCAECs were treated with cell culture media obtained from FIB-MAA-CIT-stimulated macrophages. FIB-MAA-CIT activation of macrophages engaged NF-κB and p38 signaling pathways and inhibition of these pathways reduced FIB-MAA-CIT-mediated macrophage cytokine secretion and subsequent HCAEC responses. In summary, our findings support a novel mechanism by which endogenously modified proteins drive macrophage-endothelial cell crosstalk, promoting myocardial inflammation. Targeting these post-translational modifications may present novel therapeutic strategies to mitigate HF in RA.