Prestin and otolin-1 proteins in the hearing loss of adults chronically exposed to lead

Abstract

BackgroundSome studies in animal models and humans suggest that exposure to lead is associated with hearing loss. Lead can reach the inner ear through the blood circulation; evidence suggests that lead could accumulate in the inner ear, causing inner ear damage.Aim: To evaluate prestin and otolin-1 protein levels and their relationship with an increased hearing threshold in participants exposed to lead. MethodsWe conducted a cross-sectional study with 315 participants from Tlaxcala, Mexico. Blood lead levels (BPb) were evaluated by graphite furnace atomic absorption spectrometry. Serum prestin and otolin-1 were quantified using ELISA. Auditory function at frequencies of 0.125 to 8 kHz was evaluated in a soundproof chamber. ResultsParticipants were classified according to BPb: group I (<10 μg/dL) had a median BPb of 6 μg/dL and prestin levels of 11.06 ng/mL. While participants in group II (≥10 μg/dL) had a median of BPb 20.7 μg/dL (p < 0.05) and prestin levels of 0.15 ng/mL (p < 0.001). Participants in both groups showed a normal hearing. Otolin-1 levels were higher for participants with normal hearing and lower for participants with hearing loss in both groups, p > 0.05. Multiple linear regression models predict an average decrease of 0.17 to 0.26 ng/mL in prestin levels per decibel increase for the frequencies evaluated. ConclusionsParticipants with high BPb showed an increase in hearing threshold, and prestin levels decreased proportionally to the hearing threshold increase. This is the first study to evaluate prestin as a potential biomarker for hearing damage, evaluated by audiometry, in participants with lead exposure.