Non-invasive sampling procedure revealing the molecular events at different abutments of bone-anchored hearing systems-A prospective clinical pilot study

Martin L Johansson; Omar Omar; Margarita Trobos; Sofia Jonhede; Hanna Peters; Malou Hultcrantz; Peter Thomsen

doi:10.3389/fnins.2022.1058689

Non-invasive sampling procedure revealing the molecular events at different abutments of bone-anchored hearing systems-A prospective clinical pilot study

Front Neurosci. 2022 Nov 8:16:1058689. doi: 10.3389/fnins.2022.1058689. eCollection 2022.

Authors

Martin L Johansson^{1

2}, Omar Omar³, Margarita Trobos¹, Sofia Jonhede², Hanna Peters², Malou Hultcrantz⁴, Peter Thomsen¹

Affiliations

¹ Department of Biomaterials, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
² Research and Technology, Oticon Medical AB, Askim, Sweden.
³ Department of Biomedical Dental Sciences, College of Dentistry, Imam Abdulrahman Bin Faisal University, Dammam, Saudi Arabia.
⁴ Department of Clinical Science, Intervention and Technology, Karolinska Institutet, Stockholm, Sweden.

Abstract

Purpose: To investigate the molecular activities in different compartments around the bone-anchored hearing system (BAHS) with either electropolished or machined abutments and to correlate these activities with clinical and microbiological findings.

Materials and methods: Twelve patients received machined or electropolished abutments after implant installation of BAHS. Peri-abutment fluid and tissue were collected from baseline to 12 months. Gene expression of cytokines and factors related to tissue healing and inflammation, regeneration and remodelling, as well as bacterial recognition were determined using quantitative-polymerase chain reaction (qPCR). The clinical status was evaluated using the Holgers scoring system, and bacterial colonisation was investigated by culturing.

Results: The gene expression of inflammatory cytokines (IL-8, IL-1β, and IL-10) and bacteria-related Toll-like receptors (2 and 4) was higher in the peri-abutment fluid than at baseline and in the peri-abutment tissue at 3 and 12 months. Conversely, the expression of genes related to tissue regeneration (Coll1a1 and FOXO1) was higher in the tissue samples than in the peri-abutment fluid at 3 and 12 months. Electropolished abutments triggered higher expression of inflammatory cytokines (IL-8 and IL-1β) (in peri-abutment fluid) and regeneration factor FOXO1 (in peri-abutment tissue) than machined abutments. Several cytokine genes in the peri-abutment fluid correlated positively with the detection of aerobes, anaerobes and Staphylococcus species, as well as with high Holger scores.

Conclusion: This study provides unprecedented molecular information on the biological processes of BAHS. Despite being apparently healed, the peri-abutment fluid harbours prolonged inflammatory activity in conjunction with the presence of different bacterial species. An electropolished abutment surface appears to be associated with stronger proinflammatory activity than that with a machined surface. The analysis of the peri-abutment fluid deserves further verification as a non-invasive sampling and diagnostic procedure of BAHS.

Keywords: BAHS; Holgers score; abutment surface; bone-anchored hearing; gene expression; infection; inflammation; percutaneous.

Grants and funding

This study was sponsored by Oticon Medical AB, Sweden (Study ID C49) and supported by the Swedish Research Council (2018-02891), the Swedish state under an agreement between the Swedish government and the county councils, the ALF agreement (ALFGBG-725641), the Hjalmar Svensson Foundation, the Felix Neubergh Foundation, the Adlerbertska Foundation (GU 2019/86, 13/09/19), the IngaBritt and Arne Lundberg Foundation, and the Area of Advance Materials of Chalmers and GU Biomaterials within the Strategic Research Area initiative launched by the Swedish Government.