Alpha-Tectorin, Interleukin-10 and Thiol-Disulfide Homeostasis in Children With Congenital Hearing Loss

This cross-sectional case-control study is conducted at the Departments of Otorhinolaryngology and Audiology, Harran University Faculty of Medicine, Sanliurfa, Turkey. Pediatric patients with congenital sensorineural hearing loss confirmed by audiological testing (auditory brainstem response, otoacoustic emissions and/or pure-tone audiometry) are enrolled prospectively in three groups: (1) children who have undergone cochlear implantation for congenital hearing loss and actively use the implant (n=40); (2) children with congenital hearing loss who have not undergone cochlear implantation and actively use hearing aids (n=40); and (3) age- and sex-matched healthy children with normal audiological evaluation (n=40).

Written informed consent is obtained from the legal guardians of all participants, and assent is obtained from the children where appropriate. Age, sex, birth history, perinatal risk factors, comorbidities, medications, degree of hearing loss, device type and duration of device use are recorded using a standard data collection form.

Approximately 5 mL of venous blood is collected from each participant. Serum is separated by centrifugation and stored at -80 C until analysis. Serum alpha-tectorin and IL-10 levels are measured quantitatively with commercial enzyme-linked immunosorbent assay (ELISA) kits according to the manufacturers' instructions. Thiol-disulfide homeostasis (native thiol, total thiol and disulfide levels and their ratios) is determined with an automated spectrophotometric method.

Biochemical parameters are compared between groups and analyzed in relation to clinical characteristics and the degree of hearing loss. Normality is assessed with the Kolmogorov-Smirnov and/or Shapiro-Wilk tests. Group comparisons are performed with the independent samples t-test or Mann-Whitney U test, and one-way ANOVA or Kruskal-Wallis test, as appropriate; categorical variables are compared with the chi-square or Fisher's exact test. Correlations are evaluated with Pearson or Spearman analysis, and multivariable linear regression is used to identify factors associated with biomarker levels. A p value <0.05 is considered statistically significant.

• Blood sample collection (Other): Collection of approximately 5 mL of venous blood for measurement of serum alpha-tectorin, interleukin-10 and thiol-disulfide homeostasis parameters; no additional intervention is applied.

Primary outcomes

• Serum alpha-tectorin level [At enrollment (single blood sample)]: Serum alpha-tectorin concentration measured by ELISA, compared among the cochlear implant, hearing aid and healthy control groups.
• Serum interleukin-10 (IL-10) level [At enrollment (single blood sample)]: Serum IL-10 concentration measured by ELISA, compared among the cochlear implant, hearing aid and healthy control groups.
• Serum thiol-disulfide homeostasis parameters [At enrollment (single blood sample)]: Native thiol, total thiol and disulfide levels (umol/L) and disulfide/native thiol, disulfide/total thiol and native thiol/total thiol ratios measured by an automated spectrophotometric method, compared among the cochlear implant, hearing aid and healthy control groups.

Secondary outcomes

• Correlation of biomarker levels with degree of hearing loss [At enrollment (single blood sample)]: Correlation of serum alpha-tectorin, IL-10 and thiol-disulfide parameters with the degree of hearing loss (mild, moderate, severe, profound) determined by audiological evaluation, and with device type and duration of device use, in children with congenital hearing loss.

Sex: All, ages: any to 17 Years, accepts healthy volunteers

Inclusion Criteria:

Congenital Hearing Loss Groups (Cochlear Implant Group and Hearing Aid Group)

* Age under 18 years
* Congenital sensorineural hearing loss diagnosed at the Otorhinolaryngology outpatient clinic and confirmed by audiological testing (auditory brainstem response, otoacoustic emissions and/or pure-tone audiometry)
* Active use of a cochlear implant (Cochlear Implant Group) or active use of a hearing aid without cochlear implantation (Hearing Aid Group)
* No condition preventing collection of a peripheral blood sample
* Written informed consent from the parent or legal guardian

Healthy Control Group

* Age under 18 years
* No diagnosis of hearing loss and normal audiological evaluation
* No condition preventing collection of a peripheral blood sample
* Written informed consent from the parent or legal guardian

Exclusion Criteria (all groups):

* Syndromic hearing loss
* Acute infection, chronic inflammatory disease, autoimmune disease or other systemic disease
* History of malignancy or active malignant disease
* Immunodeficiency or use of immunosuppressive therapy
* Use of systemic corticosteroids, biologic agents or immunomodulatory therapy within the last 4 weeks

• Servet Erdemes, MD, Principal investigator, Harran University