Hyperbilirubinemia and Auditory Neuropathy

Total serum bilirubin levels and sensorineural hearing loss in the US adolescents: NHANES 2007-2010

OBJECTIVE

We aimed to investigate whether current levels of total serum bilirubin are associated with different subtypes of sensorineural hearing loss (SNHL) in adolescents.

METHODS

A set of cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) (2007-2010) was used. A subset of 1404 adolescents was sampled for measurements of total serum bilirubin, tympanometry, and average pure tone threshold at low-frequencies (LPTA: 500, 1000, 2000 Hz) or high-frequencies (HPTA: 3000, 4000, 6000, and 8000 Hz). SNHL was defined as the hearing loss that had type A tympanograms with a peak admittance of 0.3 ml or greater. Associations between serum bilirubin (square-root transformed) and different subtypes of SNHL were evaluated using binary or multinomial logistic regression models with 4-year sampling weights. The bootstrap method was used for estimation of variance and 10-fold cross-validation for assessment of overfitting issue.

RESULTS

Total serum bilirubin levels were found to be associated with any high-frequency (HPTA>15 dB in at least one ear, adjusted odds-ratio (OR_a)(bootstrap 95% confidence interval) = 3.29(1.31-8.19), p = 0.011), but not with any low-frequency (LPTA>15 dB in at least one ear), SNHL in the US adolescents. Furthermore, high-frequency SNHL with HPTA>15 dB in both ears (bilateral) or HPTA≥25 dB in at least one ear, compared to that with HPTA>15 dB in one ear only (unilateral) or HPTA = 15-25 dB in at least one ear, had a stronger association with total serum bilirubin levels (OR_a = 5.37(1.27-22.65), p = 0.022 for bilateral; OR_a = 2.64(0.84-8.25), p = 0.094 for unilateral; OR_a = 5.00(0.95-26.58), p = 0.058 for HPTA≥25 dB in at least one ear; as well as OR_a = 3.06(1.15-8.25), p = 0.025 for HPTA = 15-25 dB in at least one ear). No severe overfitting problems were found.

CONCLUSION

Our findings suggest that current levels of total serum bilirubin may be informative in predicting and/or targeting high-frequency SNHL in the US adolescents.

Efficacy of Human Adipose Tissue-Derived Stem Cells on Neonatal Bilirubin Encephalopathy in Rats

Kernicterus is a neurological syndrome associated with indirect bilirubin accumulation and damages to the basal ganglia, cerebellum and brain stem nuclei particularly the cochlear nucleus. To mimic haemolysis in a rat model such that it was similar to what is observed in a preterm human, we injected phenylhydrazine in 7-day-old rats to induce haemolysis and then infused sulfisoxazole into the same rats at day 9 to block bilirubin binding sites in the albumin. We have investigated the effectiveness of human adiposity-derived stem cells as a therapeutic paradigm for perinatal neuronal repair in a kernicterus animal model. The level of total bilirubin, indirect bilirubin, brain bilirubin and brain iron was significantly increased in the modelling group. There was a significant decreased in all severity levels of the auditory brainstem response test in the two modelling group. Akinesia, bradykinesia and slip were significantly declined in the experience group. Apoptosis in basal ganglia and cerebellum were significantly decreased in the stem cell-treated group in comparison to the vehicle group. All severity levels of the auditory brainstem response tests were significantly decreased in 2-month-old rats. Transplantation results in the substantial alleviation of walking impairment, apoptosis and auditory dysfunction. This study provides important information for the development of therapeutic strategies using human adiposity-derived stem cells in prenatal brain damage to reduce potential sensori motor deficit.