TRPV4 promotes acoustic wave-mediated BBB opening via Ca2+/PKC-δ pathway

Abstract Numerous studies have shown the ability of low-energy acoustic waves such as focused ultrasound or shockwave to transiently open blood-brain barrier (BBB) and facilitate drug delivery to the brain. Preclinical and clinical evidences have well demonstrated the efficacy and safety in treating various brain disorders. However, the molecular mechanisms of acoustic waves on the BBB are still not fully understood. The present study shows the crucial role of transient receptor potential vanilloid 4 (TRPV4) in acoustic wave-mediated BBB permeability, specifically its effect on compromising tight junction proteins, ZO-1 and occludin. Intracellular signal transduction analysis shows calcium influx through TRPV4 channels, and the activation of PKC-δ pathway to mediate dissociation of ZO-1 and occludin after acoustic wave stimulation. The activation of TRPV4 or PKC-δ signaling further increased the expression level of TRPV4, suggesting a feedback loop to regulate BBB permeability. Moreover, the tight junction proteins dissociation can be reversed by administration of PKC-δ inhibitor and TRPV4 antagonist. Our findings provide a new molecular perspective to explain acoustic wave-mediated BBB opening. In addition, activation of TRPV4 by agonists may reduce the threshold intensity level of acoustic waves for BBB opening, which may prevent undesirable mechanical damages while maintaining efficient BBB opening.