Nitric Oxide-Loaded Nanobubbles for Ultrasound-Activated Therapy of Renal Fibrosis

Current therapies for renal fibrosis, predominantly antihypertensive agents and immunosuppressants, exhibit limited efficacy and significant off-target toxicity, failing to halt disease progression. To overcome these limitations, we engineered ultrasound-responsive phospholipid nanobubbles (NO-NBs) for spatiotemporally controlled nitric oxide (NO) delivery and real-time imaging. <i>In vitro</i> and <i>in vivo</i> studies demonstrate that NO-NBs enhance renal endothelial permeability and enable ultrasound-triggered NO release. Mechanistically, NO-NBs suppress fibrosis via three synergistic pathways: glutathione depletion-driven nitrosative stress, mitochondrial membrane permeabilization-induced dysfunction, and ATP depletion-mediated impairment of Smad2/3 phosphorylation, which collectively inhibit TGF-β signaling and downregulate profibrotic proteins. In unilateral ureteric obstruction (UUO) mice, NO-NBs combined with ultrasound significantly attenuated collagen deposition. Our findings establish that enhancing spatial NO bioavailability potently suppresses fibroblast activation, positioning NO-NBs as a dual-function theranostic platform for precision antifibrotic therapy with integrated real-time monitoring capability.