CXCL4-Induced PBMCs Modulate Vascular Extracellular Matrix via Wnt5a-Dependent Matrix Metalloproteinase-7 and...

Area of Science:

• Cardiovascular Biology
• Immunology
• Extracellular Matrix Biology

Background:

• Macrophage heterogeneity is crucial in vascular inflammation.
• Chemokine CXCL4 (chemokine [C-X-C motif] ligand 4) drives a monocyte/macrophage phenotype linked to atherosclerotic plaque destabilization.
• CXCL4-induced macrophages show increased S100A8 (S100 calcium-binding protein A8) and MMP7 (matrix metalloproteinase-7) expression, but underlying mechanisms remain unclear.

Purpose of the Study:

• Investigate the mechanisms of CXCL4-induced monocyte-mediated vascular inflammation.
• Characterize the phenotype and function of CXCL4-differentiated monocytes and their extracellular vesicles (EVs).
• Determine the role of the Wnt pathway in CXCL4-induced monocyte responses and vascular calcification.

Main Methods:

• Single-cell RNA sequencing of plaque macrophages.
• Differentiation of human peripheral blood-derived monocytes (PBMCs) with CXCL4.
• Analysis of osteogenic signatures and calcifying EV release.
• Investigation of Wnt pathway association.
• In vitro assessment of EV calcification potential and inflammatory effects on vascular smooth muscle cells.
• Histological validation in human carotid artery plaques.

Main Results:

• Single-cell sequencing identified a CXCL4-susceptible subpopulation of plaque macrophages with a proinflammatory signature.
• CXCL4-differentiated PBMCs showed upregulated S100A8, MMP7, and osteogenic markers, releasing EVs enriched with MMP7, S100A8, Anx5, and ALP.
• CXCL4-induced PBMCs and their EVs promoted extracellular matrix (ECM) calcification in vitro.
• The Wnt5a-CaMKII signaling axis was linked to CXCL4-induced osteogenic phenotype, EV calcification, and MMP7/S100A8 enrichment.
• CXCL4-polarized PBMC-derived EVs stimulated inflammatory gene expression in vascular smooth muscle cells.
• Human carotid plaques showed coinciding CXCL4-induced macrophage abundance, Wnt5a-CaMKII activation, and calcification.

Conclusions:

• A novel mechanism for monocyte-mediated ECM remodeling in procalcific inflammatory responses is identified.
• Wnt5a-CaMKII signaling activates the secretion of MMP7+/S100A8+ calcifying EVs by CXCL4-induced proinflammatory monocytes.
• This process contributes to vascular inflammation and atherosclerotic plaque calcification.