Redox modulation by a synthetic thiol compound reduces LPS-induced pro-inflammatory cytokine expression in macrophages via AP-1/NLRP3 axis and influences the crosstalk with endothelial cells.

Abstract

Perturbation in redox status elicits multiple cellular pathways, including those involved in the inflammatory response. A thiol-based molecule (I-152), releasing N-acetyl-cysteine (NAC) and β-mercaptoethylamine (MEA), was exploited as a redox-modulating agent, and its effects on pro-inflammatory cytokine expression and secretion in lipopolysaccharide (LPS)-stimulated macrophages (MΦ) were investigated. I-152 inhibited cytokine gene expression as well as protein secretion of the most important inflammatory cytokines in three different MΦ models in vitro and ex vivo. It alleviated inflammation via the c-Jun/AP-1 and NF-κB signaling pathways, depending on the dose, and regulated NLRP3 inflammasome expression, leading to decreased IL-1β and IL-18 release and reduced pyroptotic cell death. Consequently, the influence of redox-modulated MΦ secretome on the crosstalk with endothelial cells was evaluated. Co-culture experiments between THP-1 MΦ, that had been pretreated with I-152 before LPS stimulation, and Human Vascular Endothelial Cells (HUVECs) showed reduced VCAM/ICAM expression in these cells in concomitance with a less oxidized and inflamed MΦ proteomic portrait. Overall, our findings suggest that I-152 redox modulation could target the AP-1/NLRP3 axis, affecting LPS-induced inflammation in MΦ and influencing HUVEC responses, revealing a complex and bidirectional interchange.