Heterozygous mutation of Vegfr3 reduces renal lymphatics without renal dysfunction

Background: Lymphatic abnormalities are observed in several types of kidney disease, but the relationship between the renal lymphatic system and renal function is unclear. The discovery of lymphaticspecific proteins, advances in microscopy, and available genetic mouse models provide the tools to help elucidate the role of renal lymphatics in physiology and disease. Methods:We utilized a mouse model containing a missense mutation in Vegfr3 (dubbed Chy) that abrogates its kinase ability. Vegfr3Chy/+ mice were examined for developmental abnormalities and kidneyspecific outcomes. Control and Vegfr3Chy/+ mice were subjected to cisplatin-mediated injury. We characterized renal lymphatics using tissue clearing, light-sheet microscopy, and computational analyses. Results: In the kidney, VEGFR3 is expressed not only in lymphatic vessels, but also in various blood capillaries. Vegfr3Chy/+ mice had severely reduced renal lymphatics with 100% penetrance, but we found no abnormalities in blood pressure, serum creatinine, BUN, albuminuria, and histology. There was no difference in the degree of renal injury after low dose cisplatin (5 mg/kg), although Vegfr3Chy/+ mice developed perivascular inflammation. Cisplatin-Treated controls had no difference in total cortical lymphatic volume and length, but showed increased lymphatic density due to decreased cortical volume. Conclusions: We demonstrate that VEGFR3 is required for development of renal lymphatics. Our studies reveal that reduced lymphatic density does not impair renal function at baseline and induces only modest histological changes after mild injury. We introduce a novel quantification method to evaluate renal lymphatics in 3D and demonstrate that accurate measurement of lymphatic density in chronic kidney disease requires assessment of changes to cortical volume.