Controlling Neuropilin-2 Signaling to Improve Lymphatic Function

Lymphatics are vital for fluid recycling, immune surveillance, and lipid uptake. Abnormal lymphatics lead to lymphedema, metabolic changes, inflammation, and infections and contribute to the pathophysiology of many chronic illnesses. In response to the NIH mission (NOT-HL-23-099) promoting research on the biology of the lymphatic system to advance discovery of novel drugs for lymphatic diseases, we have identified Neuropilin-2 (NRP2) as a pivotal manipulator of lymphatic function. NRP2 is a unique transmembrane receptor in lymphatic endothelial cells (LEC) capable of signaling through disparate and opposing ligands. Our central hypothesis is that NRP2 acts as a dynamic rheostat by toggling between its ligands and downstream signaling pathways to either promote or restrain fluid and lipid uptake into lymphatic vessels. Using innovative biochemical, genomic, and pharmaceutical strategies in new animal models, we will test our hypothesis by defining, modulating, and controlling NRP2 ligand-dependent signaling in lymphatics. NRP2 binds VEGFC in complex with VEGFR3 to increase lymphatic function. Our compelling new data reveals that NRP2 is necessary for VEGFC-induced activation of VEGFR3, adult lymphangiogenesis, and proper lymphatic drainage functions in vivo. On the other hand, the inimitable NRP2 receptor can also bind SEMA3F in complex with PlexinA1 to inhibit lymphatic functions such as absorption and immune cell trafficking. In Aim 1, we will alter Nrp2 expression and ligand-dependent functions in the skin to sustain proper fluid drainage and ameliorate lymphedema. In preliminary studies, systemic neutralization of the endogenous Sema3F ligand in adult wildtype mice increases VEGFC binding to NRP2 and accelerates lymphangiogenesis following injury to restore lymphatic drainage and alleviate secondary lymphedema. However, increasing lymphatic drainage is not always advantageous. In the GI tract, specific lymphatic capillaries called lacteals facilitate lipid absorption. In Aim 2, we will temper Nrp2 expression and ligand-dependent functions in the intestine to block lipid influx and prevent diet-induced obesity. To date, the role of NRP2 in lacteal function, lipid absorption, or lipid transport has not been investigated, especially in relation to adult weight gain or digestive inflammatory disease. In accordance, global or conditional Nrp2 loss in lacteals correlates with lower basal body weight and reduced weight gain with high fat diet compared to controls. Specifically, we will establish the therapeutic potential of inhibiting differential ligand-binding domains in Nrp2 using systemic antibodies or exogenous competitive proteins in preclinical models to either promote VEGFC/NRP2 signaling to alleviate lymphedema or to limit VEGFC/NRP2 signaling in lacteals to hinder lipid absorption to prevent obesity or metabolic disease. Overall, our proposal is significant and warrants careful consideration as it will reveal distinct lymphatic regulatory mechanisms and use inventive approaches to curtail lymphedema or obesity and their comorbidities. Since humanized versions of these drugs already exist, our results may quickly translate into viable and effective treatments to improve lymphatic diseases. Project Number: 1R01HL179216-01 | Fiscal Year: 2025 | NIH Institute/Center: National Heart Lung and Blood Institute (NHLBI) | Principal Investigator: DIANE BIELENBERG (+1 co-PI) | Institution: BOSTON CHILDREN'S HOSPITAL, BOSTON, MA | Award Amount: $865,694 | Activity Code: R01 | Study Section: Integrative Vascular Physiology and Pathology Study Section[IVPP] View on NIH RePORTER: https://reporter.nih.gov/project-details/1R01HL17921601