Abstract 4141823: Deletion of Endothelial Neuropilin-1 Improves Cardiac Diastolic Function in Heart Failure with Preserved Ejection Fraction

Heart failure with preserved ejection fraction (HFpEF), characterized by cardiac diastolic dysfunction, leads to premature mortality with limited effective treatments. A recent study in HFpEF patients suggested neuropilin 1 (NRP1), an endothelial cell (EC) originated prognostic marker, might contribute to the pathogenesis of HFpEF. However, the functional role of NRP1 in the pathogenesis of HFpEF remains unclear. Purpose: To determine the functional role of NRP1 in the pathogenesis of HFpEF. Hypothesis: NRP-1 contributes to the pathogenesis of HFpEF, potentially mediated through chronic inflammation. Methods: HFpEF was induced by hypertensive and metabolic stresses in control (n=14) and tamoxifen-induced, endothelial cell-specific NRP1 knockout (NRP1 iEC-KO ) mice (n=13). We assessed cardiac diastolic function via echocardiography and pressure-volume loop through invasive catheters. To determine the inflammation level, we tested leukocyte adhesion, inflammatory marker vascular cell adhesion molecule 1 (VCAM-1), and intercellular adhesion molecule 1 (ICAM-1) mRNA level in control and NRP1 shRNA knockdown (NRP1 KD) human umbilical vein endothelial cells (HUVECs) with a stimulation of TNF-α. Student t-test (two tailed) was used and the criterion level of significance was set at p<0.05. Results: We found a significantly improved diastolic function in NRP1 iEC-KO mice, evidenced by a significantly reduced end diastolic pressure in NRP1 iEC-KO mice (8±2mmHg; n=7) compared to the controls (17±2mmHg; n=9; p=0.01) after HFpEF induction. E/A ratio was also significantly lower in NRP1 iEC-KO mice (2.0±0.2; n=10) compared to controls (2.7±0.3; n=12; p=0.04). Moreover, the isovolumic relaxation time was also significantly reduced in NRP1 iEC-KO mice (18±0.8ms; n=13) compared to controls (20±0.8ms; n=14; p=0.03). In addition, In HUVECs, NRP1 KD significantly reduced inflammatory marker VCAM-1 mRNA expression (95±16; n=5) compared to controls (293±36; n=5; p<0.01) upon TNF-α treatment. Similarly, NRP1 KD significantly reduced ICAM-1 mRNA expression (44±14; n=5) compared to controls (83±9; n=5; p=0.03) upon TNF-α treatment. Furthermore, leukocyte adhesion was significantly lower in the NRP1 KD group (57.0 ±8.6 cells/field) compared to the control group (90.8 ±9.1 cells/field; p=0.04). Conclusion: Endothelial NRP1 contributes to cardiac diastolic dysfunction and the pathogenesis of HFpEF, potentially mediated through the activation of chronic low-grade inflammation.