Endothelial TLR4 coordinates angiogenesis and inflammation through a CXCR2-neutrophil-oxidative axis

To determine the endothelial-intrinsic role of TLR4 in inflammatory vascular remodeling and cytokine signaling, and to define how exogenous microbial and oxidation-derived endogenous signals are integrated by endothelial TLR4 to regulate vascular function.

Single-cell transcriptomic analyses of human tissues identified endothelial cells as a coherent, lineage-consistent TLR4-expressing population across tissues and disease states, distinguishing TLR4 from other endothelial Toll-like receptors. Using tamoxifen-inducible endothelial-specific TLR4 knockout mice (Cdh5-CreERT2; Tlr4flox/flox) we show that lack of TLR4 markedly impaired early venular remodeling, junctional loosening, vascular leakage, and neutrophil recruitment during skin wound healing, and suppressed tumor angiogenesis and growth in a syngeneic cancer model. Mechanistically, endothelial TLR4 activation induced a focused chemokine program dominated by CXCL1/2/5-CXCR2 signaling, promoting neutrophil recruitment and lipid-oxidation responses. Loss of endothelial TLR4 reduced myeloperoxidase (MPO)-positive inflammatory-cell accumulation and carboxyethylpyrrole lipid-peroxidation adduct deposition, supporting a feed-forward inflammatory loop in which neutrophil-derived oxidized lipids act as endogenous TLR4 ligands. Pharmacologic CXCR2 inhibition or combined ROS/MPO suppression phenocopied endothelial TLR4 deletion.

Endothelial-intrinsic TLR4 functions as a vascular inflammatory integrator that links microbial pattern recognition with endogenous oxidation-derived danger signaling to coordinate chemokine production, neutrophil recruitment, MPO-linked lipid-oxidation amplification, and angiogenesis. These findings identify endothelial TLR4 as a distinct and targetable vascular inflammatory node, functionally separable from hematopoietic TLR4, with implications for sterile inflammatory cardiovascular disease.