Targeting TRPV4 to restore glymphatic system function and alleviate cerebral edema in ischemic stroke.

Abstract

Emerging studies underscore the pivotal role of glymphatic system (GS) dysfunction in the pathogenesis of cerebral edema following brain injury. The transient receptor potential vanilloid 4 (TRPV4) channels have been implicated in modulating the polarization of aquaporin-4 (AQP4), a key protein involved in GS function. This study investigates the potential of targeting TRPV4 to alleviate GS dysfunction and reduce cerebral edema following ischemic stroke. TRPV4 inhibitor HC067047 or a vehicle was administered via lateral ventricle cannulation in a mouse model of middle cerebral artery occlusion and reperfusion (MCAO/R). The function of the GS was assessed through tracer injection experiments, including in vivo transcranial imaging, ex vivo brain tissue and section analysis, and fluorescence retention in deep cervical lymph nodes (dCLNs). Cerebral edema was quantified using magnetic resonance imaging. AQP4 polarization and β-dystroglycan (β-DG) expression were evaluated by immunofluorescence. Western blotting was employed to measure protein levels of β-DG, matrix metalloproteinase-9 (MMP9), and Ras homolog family member A (RhoA). Long-term neurological outcomes were assessed via behavioral testing. MCAO/R mice exhibited significant GS dysfunction, cerebral edema, and disrupted AQP4 polarization. Additionally, β-DG expression was markedly reduced, while TRPV4 expression was elevated in the ischemic penumbra. Western blotting revealed increased expression of MMP9 and RhoA. The inhibition of TRPV4 by HC067047 significantly improved GS function, reduced cerebral edema, and enhanced neurological recovery. Mechanistically, HC067047 partially restored AQP4 polarization, upregulated β-DG expression, and suppressed the expression of MMP9 and RhoA. These findings highlight the therapeutic potential of TRPV4 inhibition in ischemic stroke by restoring GS function, mitigating cerebral edema, and promoting neurological recovery, thereby positioning TRPV4 as a promising target for future interventions.