Anti-LCN2 antibody treatment is associated with attenuated hearing loss and blood-labyrinth barrier disruption in a mouse model of chronic kidney disease.

Chronic kidney disease (CKD) is associated with sensorineural hearing loss, but the mechanisms linking renal injury to cochlear dysfunction remain incompletely defined. Because lipocalin-2 (LCN2/NGAL) is markedly increased in CKD and has been implicated in endothelial dysfunction and barrier injury, we investigated whether LCN2 contributes to cochlear damage in a mouse model of CKD. Male C57BL/6J mice underwent 5/6 nephrectomy, and CKD mice received either an anti-LCN2 monoclonal antibody or an isotype control three times weekly for seven weeks beginning one week after completion of surgery. Auditory function, cochlear morphology, blood-labyrinth barrier integrity, cochlear perfusion, and LCN2-associated signaling were assessed using auditory brainstem responses, distortion product otoacoustic emissions, whole-mount immunofluorescence, FITC-dextran extravasation, Western blotting, quantitative PCR, and laser Doppler flowmetry. CKD mice developed elevated auditory brainstem response thresholds, reduced distortion product otoacoustic emission amplitude at a single primary tone pair with f2 = 8.0 kHz, outer hair cell loss, and a reduction in the number of CtBP2-positive presynaptic ribbon puncta per inner hair cell. These changes were accompanied by increased serum and cochlear LCN2, upregulation of 24p3R/SLC22A17 and NLRP3, increased blood-labyrinth barrier permeability, reduced claudin-5 and ZO-1 expression, impaired cochlear blood flow, stria vascularis atrophy, and decreased expression of strial ion-transport genes. Anti-LCN2 antibody treatment improved auditory thresholds and otoacoustic emission responses, attenuated outer hair cell and synaptic injury, reduced vascular leakage, partially restored tight junction and ion-transport gene expression, and improved cochlear perfusion, without measurably lowering serum blood urea nitrogen or creatinine. These findings support a possible contribution of LCN2 to CKD-associated cochlear vascular dysfunction and hearing loss. Targeting LCN2 may represent a therapeutic strategy for preserving hearing in CKD, although validation in additional CKD models, both sexes, and human tissues is required.