Fluid Exudates From Inflamed Bone-Anchored Hearing Aids Demonstrate Elevated Levels of Cytokines and Biomarkers of Tissue and Bone Metabolism

Objective: The purpose of the current study was to determine the presence of biomarkers of tissue and bone metabolism and 10 cytokines within the fluid exudate from around bone anchored hearing aids (BAHAs), with a view to understanding the mechanisms of peri-BAHA inflammation. Study Design: Fluid exudate from around BAHAs was collected from volunteers (n = 10) with inflammation and controls (n = 10) without inflammation around the BAHA. Setting: Studies of periodontitis and dental peri-implantitis have demonstrated that fluid exudate, arising from the hard tissue-soft tissue junction, is increased during disease; this fluid contains biomarkers of tissue metabolism, bone metabolism and inflammation. Patients: Volunteers were recruited from the Queen Elizabeth Hospital, Birmingham, UK and New Cross Hospital, Wolverhampton, UK. Interventions: This was an observational study and no interventions were carried out as part of the study. Main Outcome Measure: Biomarkers of tissue metabolism (MMP9, TIMP1 and 2), bone metabolism ( RANKL and OPG) and cytokines (GM-CSF, interferon (IFN)-*, IL-1A, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10 and TNF>) were measured in the fluid samples by Luminex multianalyte assay. Results: Volumes of fluid exudate were significantly higher (p < 0.05) at sites of inflammation than from un-inflamed tissues surrounding BAHAs. IL-1*, IL-6, IL-8, TNF*, MMP9, TIMP1 and 2 were found in both inflamed and un-inflamed samples and levels were significantly higher in samples from inflamed sites. RANKL, IFN*, IL-2, IL-4, and GM-CSF were detected only at inflamed sites whereas OPG, IL- 5 and IL- 10 were not detected in any samples. Conclusion: These data demonstrate that peri-BAHA tissues showing clinical signs of inflammation are associated with increased fluid exudate, which contains elevated levels of key biomarkers of inflammation and a biomarker profile that is consistent with increased tissue and bone remodeling around BAHAs.