LYVE1 ectodomain shedding blunts lymphatic transmigration and clearance of macrophages during kidney injury.

Although renal fibrosis is predominantly driven by the accumulated inflammatory cells that secrete proinflammatory factors within the kidney, the key mechanisms underlying macrophage clearance from the kidney are not well understood. The interaction of hyaluronan with lymphatic endothelial hyaluronan receptor 1 (LYVE1) constitutes a critical initial step in macrophage adhesion and removal by lymphatic vessels. This study investigates alterations in LYVE1 during kidney disease and elucidates its role in macrophage trafficking. Three renal fibrosis models demonstrated a reduction in full-length LYVE1 and an increase in the soluble LYVE1 fragment. Immunostaining of fibrotic kidneys showed significantly reduced expression of soluble LYVE1 compared with the intracellular fragment (Cyto-LYVE1), demonstrating ectodomain shedding of LYVE1 in vivo and in vitro. Functionally, human lymphatic endothelial cells exposed to TGF-β1 exhibited a significant decrease in macrophage adhesion and transendothelial migration compared with controls. Mechanistic analyses identified increased matrix metalloproteinase 9 (MMP9) in renal injury as a key upstream regulator of LYVE1 shedding. MMP9 inhibitors reduced LYVE1 shedding, enhanced macrophage adhesion and trafficking, and mitigated macrophage accumulation and disease progression. In conclusion, MMP9-induced LYVE1 shedding is linked to progressive kidney fibrosis and macrophage accumulation. LYVE1 shedding inhibitors offer potential as therapeutic agents for mitigating immune overload and kidney fibrosis.