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

## TL;DR

This study shows that modified fibrinogen in rheumatoid arthritis patients can trigger heart inflammation through immune cell interactions.

## Contribution

Identifies a novel mechanism linking post-translational modifications of fibrinogen to macrophage-endothelial crosstalk in RA-associated heart failure.

## Key findings

- RA-HF patients show elevated MAA and CIT adducts and collagen deposition in heart tissue.
- FIB-MAA-CIT activates macrophages and endothelial cells, increasing inflammatory markers.
- NF-κB and p38 pathways mediate macrophage responses to FIB-MAA-CIT.

## Abstract

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.