Abstract 712: IL-19 Is A Lymphokine That Induces Prox1-dependent Lymphangiogenesis And Permeability

Introduction: Atherosclerosis is a vascular inflammatory disease associated with lymphangiogenesis, but whether lymphangiogenesis contributes to disease progression or is simply a compensatory attempt at disease resolution is currently unresolved. Recent studies are revealing a role for lymphatic vessels in reverse cholesterol transport (RCT), which could attenuate atherosclerosis. We have previously reported that Interleukin-19 (IL-19), an anti-inflammatory cytokine, uniquely attenuates atherosclerotic plaque progression while also being pro-angiogenic. This drives our hypothesis that one mechanism whereby IL-19 is atheroprotective is by promoting functional lymphangiogenesis and lymphatic flux. Methods & Results: IL-19 can significantly induce human dermal lymphatic endothelial cell (hdLEC) proliferation, migration, and tube formation, to the same degree as VEGFC, a potent inducer of lymphangiogenesis. RNA sequencing analysis indicates that IL-19 induces an angiogenic transcriptional program through Prox1, a master regulator of lymphangiogenesis. Knockdown of Prox1 led to a significant decrease in IL-19-associated proliferation and migration. IL-19 also increased expression of Angpt2, an endothelial cell protein that induces permeability through regulation of tight junctions, through a Prox1-dependent mechanism. Electric Cell-substrate Impedance Sensing assays showed that IL-19 treatment increased hdLEC permeability and mitigated oxLDL-associated decreased permeability, suggestive of maintaining lymphatic barrier function during atherosclerosis. IL-19 treatment also increased dil-HDL transport across an hdLEC barrier. Preliminary in vivo data suggests injection of rmIL-19 in Il19 -/- mice increases lymphatic permeability and flux through increased lymphatic uptake of Evans blue dye. Conclusion: These data suggest that IL-19 increases lymphangiogenesis, permeability, and may increase RCT to plausibly decrease atherosclerosis. These results can influence our understanding of the association between the lymphatic system and atherosclerosis.