Western Blot Characterization of Human Serum Prestin, an Outer Hair Cell Biomarker.

Hypothesis: Western blot analysis of human prestin in the blood reveals multiple bands, rather than a single band.

Background: Previously, using the ELISA method, prestin was shown to be a good biomarker of outer hair cell (OHC) health and sensorineural hearing loss that could be measured in the blood. Recently, we found that a Western blot approach in an experimental model demonstrated three prestin bands providing greater insights into prestin in the blood and its origins. This approach has not yet been explored in humans.

Methods: Serum samples from 25 healthy human subjects were analyzed. An automated Western blot for each sample was generated, and bands were analyzed and compared with transient evoked otoacoustic emission levels (TEOAE).

Results: There were five bands at ~32, ~50, ~94, ~139, and ~171 kDa, respectively. Notably, the ~50-kDa band consistently was the most prominent. When the subjects were divided based on TEOAE level, those with high emission levels had a significantly larger ~94-kDa band than those with low emission levels.

Conclusions: Western blot characterization of OHC biomarker prestin in humans shows that the band closest to the previously estimated molecular weight of prestin (81 kDa) is related to a functional measure of OHCs. This finding increases confidence in the value of serum prestin as a biomarker. The Western blot method appears to offer higher-resolution information on serum prestin. Future work will be carried out under pathological conditions to inform on the application of this quantitative method in clinical settings.