Low-intensity pulsed ultrasound combined with microbubbles enhances amphotericin B delivery across the blood-brain barrier for improved therapy of cryptococcal meningitis.

Cryptococcal meningitis (CM), a life-threatening fungal infection of the central nervous system, faces therapeutic challenges due to poor blood‒brain barrier (BBB) penetration of amphotericin B. This study investigates the efficacy of low-intensity pulsed ultrasound (LIPUS) combined with microbubbles in enhancing BBB permeability and improving prognosis in a murine CM model. Our findings suggest that LIPUS combined with microbubbles treatment significantly increased BBB permeability, leading to elevated cerebral concentrations of amphotericin B and improved fungicidal activity against Cryptococcus neoformans in the brain. Mechanistic investigations revealed that LIPUS-microbubble treatment transiently upregulated vascular endothelial growth factor (VEGF) expression levels in cerebral tissues. Notably, these protein expression alterations and the associated BBB permeability enhancement completely normalized within 6 hours post-treatment. Pharmacological inhibition of VEGF abolished the ultrasound-induced BBB permeability increase, indicating that VEGF may serve as a pivotal upstream regulator mediating this transient barrier modulation. Compared with amphotericin B monotherapy, the combined regimen of LIPUS plus microbubbles and amphotericin B achieved a greater reduction in cerebral cryptococcal burden. The India ink staining revealed reduced cryptococcal capsule thickness and smaller yeast cell diameters in treated mice. Furthermore, the intervention ameliorated CM-associated clinical manifestations, including weight loss and neurological deficits, while prolonging survival time. These results suggest the potential of LIPUS-microbubble-mediated BBB modulation as a promising adjunctive strategy to optimize amphotericin B delivery and improve therapeutic efficacy in CM, offering new insights into overcoming the limitations of conventional treatments for neurotropic fungal infections.