Abstract P2162: Controlled Porous Structures Of Nitric Oxide-releasing Inhaler For Pulmonary Arterial Hypertension Vascular Reverse Remodeling

Abstract

Pulmonary arterial hypertension (PAH) is an incurable disease characterized by elevated blood pressure in the pulmonary artery. Nitric oxide (NO) is a potent regulator of hemodynamics and macrophage reprogramming. However, the therapeutic effects of NO depend on its concentration and its half-life is very short. Pulmonary delivery has advantages such as the ability to escape first-pass metabolism and the large absorptive surface area. In this study, we prepared NO-releasing inhalers with controlled porous structures to modulate the deposition in the respiratory system. NO-releasing inhalers with micro-sized pores showed improved nebulization efficiency than nano-sized ones. Furthermore, the cGMP expression and macrophage polarization were evaluated to confirm the vasodilatory and anti-inflammatory effects of NO. The customized nebulizer system was prepared for efficiency test of NO-MPs. The fluorescence intensity of Nile red was analyzed using photoluminescence spectroscopy to confirm the amounts of NO-MPs on the slide glass. As with confocal images, 0.8k BPEI/NO-MPs could arrive the lower region than 25k BPEI/NO-MPs. NO produced by endothelial nitric oxide synthase (eNOS) induce vasodilation by increasing cyclic guanosine monophosphate (cGMP) in vascular smooth muscle cells. Hence, the delivery of NO mimicking the physical production of the endothelium in range of 0.05-0.4 nmol cm -2 min -1 is required to restore vascular homeostasis as NO has a concentration-dependent effect on cells. Therefore, BPEI0.8k/NO-MPs release 0.277 nmol cm -2 min -1 of NO that mimics the environment in healthy endothelium, while BPEI25k/NO-MPs showed a higher concentration of NO release, 0.548 nmol cm -2 min -1 . BPEI0.8k/NO-MPs increased the synthesis of cGMP in cells, whereas BPEI25k/NO-MPs presented adverse effects due to an initial burst release. When cell populations were quantified, BPEI0.8k/NO-MPs increased the number of M2-like cells while decreasing the number of M1-like cells. Furthermore, when we analyzed proteins and gene levels of cells, anti-inflammatory factors increased in BPEI0.8k/NO-MPs treatment groups. In conclusion, NO-releasing inhalers could deliver NO to deep lungs and has the potential for pulmonary vascular recovery.