The mechanisms underlying meningeal lymphatic vessel (mLV)-mediated immune cell clearance after stroke remain unclear. Using a mouse middle cerebral artery occlusion model, we performed single-cell RNA sequencing to analyze post-ischemic meningeal macrophages. In vitro co-culture and CCR2 inhibition (RS504393) validated the CCL2-CCR2 axis between lymphatic endothelial cells and macrophages. Macrophage trafficking to mLVs and cervical lymph nodes was assessed by Evans Blue tracing and F4/80 immunofluorescence. We utilized VEGF-C to enhance meningeal lymphatic vessel function and concomitantly evaluated neurological deficits, brain edema, and neuroinflammation. Ischemia expanded meningeal macrophages, whose crosstalk with lymphatic endothelial cells relied on CCL2-CCR2 axis. CCR2 inhibition impaired macrophage trafficking to mLVs and cervical lymph nodes, worsening edema, motor deficits, and inflammation, whereas VEGF-C enhanced mLV drainage and improved outcomes. We identify a novel mechanism where in mLVs recruit macrophages via CCL2 for perivascular clearance post-ischemia. Combining VEGF-C with modulation of the CCL2-CCR2 axis presents a promising synergistic therapeutic strategy for stroke.
Wang et al. (Sat,) studied this question.