Abstract 024: Genetically Inducing Renal Lymphangiogenesis Prevents Angiotensin II-Induced Hypertension in Mice

Angiotensin II (AII)-dependent hypertension (AIIHTN) is associated with renal immune cell infiltration and inflammation. Lymphatic vessels drain interstitial fluid and traffic immune cells to draining lymph nodes; however, the role of renal lymphatics in AIIHTN is unknown. Our hypotheses were that: 1) renal lymphatic vessel density is increased in mice with AIIHTN, and 2) that further augmenting renal lymphatic vessels will prevent AIIHTN. Male and female mice were infused with AII (490 ng/kg/min) or saline for 2 or 3 weeks by subdermal osmotic mini pumps. Male and female mice with AIIHTN had markedly increased renal lymphatic vessel density compared to controls. AIIHTN males had significantly increased renal gene expression of the lymphatic vessel markers Lyve1, Pdpn, and Vegfr3, while Pdpn and the lymphangiogenic signal Vegfc were increased significantly in AIIHTN females. Kidneys of AIIHTN males had significantly increased F4/80+ macrophages at 2 weeks and F4/80+ macrophages and CD3e+ T cells at 3 weeks as determined by flow cytometry. Unlike in males, renal CD11c+ dendritic cells were increased significantly in females. Renal mRNA levels of the pro-inflammatory cyto/chemokines Tnfa, Il1b, Mcp1, and Cxcl13 were elevated significantly in males at 2 and 3 weeks and in females at 3 weeks. To determine whether augmenting renal lymphatic vessels prior to AII infusion could prevent AIIHTN, we used transgenic mice that overexpress the lymphangiogenic signal VEGF-D only in the kidney under the control of doxycycline (KidVD+ mice) and thus exhibit renal-specific lymphangiogenesis. Doxycycline initiated 1 week prior to 3-week AII infusion prevented AIIHTN in KidVD+ mice while KidVD- mice still developed AIIHTN (Males SBP: 122±2 vs. 161±3 mmHg; p<0.05; Females SBP: 114±1 vs. 131±4 mmHg; p<0.05). KidVD+ AIIHTN mice had significantly decreased renal levels of CD11c+ dendritic cells and CD8+ T cells. Renal gene expression of Tnfa and Il1b were normalized in all KidVD+ mice. These data demonstrate that renal lymphatic vessel density is increased in AIIHTN and that genetically inducing renal lymphangiogenesis prior to AII infusion can prevent AIIHTN by reducing renal immune cells and inflammation.