Abstract 16602: The PlGF-Nrp1 Interaction Promotes the Splenic Immune Response in Hypertension After Neuroimmune Activation

Introduction: We previously discovered that Placental Growth Factor (PlGF) is released in the spleen by a sympathetic discharge to elicit hypertension. Neuropilin1 (Nrp1) is one of PlGF receptors and, interestingly, is a transmembrane protein expressed on precursors of Dendritic cells (DCs).

Hypothesis: Here we investigated the involvement of Nrp1 as the PlGF receptor mediating the neuroimmune activation of immune response during hypertension.

Methods: We used flow cytometry and tail cuff to evaluate the involvement of PlGF-Nrp1 pathway in neuroimmune activation of splenic immune response in hypertension.

Results: To define Nrp1 role in transducing PlGF effect during hypertension, we evaluate its expression by flow cytometry finding that monocyte-derived DCs (MoDCs) increased Nrp1 expression in response to AngII (12.7±1.3 vs 28.8±3 % Nrp1 Veh vs AngII; p<0.01). This effect was blocked by splenic sympathetic denervation obtained by celiac ganglionectomy (CGX) (28.8±3 vs 14±1.5 % Nrp1 Sham AngII vs CGX AngII; p<0.01). To test the relevance of PlGF-Nrp1 pathway in hypertension, we generated a transgenic mouse model with a selective deletion of Nrp1 in myeloid lineage utilizing the LysMcre (Nrp1 ^myeKO mice). By using an in vitro standard differentiation protocol of maturation of monocytes in DCs, we observed that CD86 and MHCII expression was up-regulated in MoDCs from the spleen of WT mice cultured in the standard medium plus rmPlGF (0.014±0.001 vs 0.035±0.005 CD86+ DCs/total cells count respectively, p<0.05; 0.010±0.003 vs 0.030±0.003 MHCII+ DCs/total cells count respectively, p<0.01). On the contrary, CD86 and MHCII were similarly expressed on MoDCs from Nrp1 ^myeKO mice cultured with and without rmPlGF indicating that PlGF is involved in the maturation of MoDCs through its interaction with Nrp1. To confirm the involvement of Nrp1 in blood pressure (BP) increase, we infused AngII to Nrp1 ^myeKO mice, finding that they were protected from hypertension as compared to WT control mice (Systolic BP 106±1 vs 126±2 mmHg respectively, p<0.001).

Conclusions: These data demonstrate that PlGF-Nrp1 pathway is a key mechanism that promote the immune response involved in hypertension and blocking the splenic innervation, hampered this response and BP increase.