Tissue-resident and recruited mononuclear phagocyte organization in the cochlea under homeostasis and implant-induced inflammation
- 1Department of Otolaryngology-Head and Neck Surgery, University of Iowa , , ,
Abstract
Background: The cochlea contains a diverse population of immune cells that contribute to tissue homeostasis and to responses to injury. Among these, mononuclear phagocytes including tissue-resident macrophages, dendritic cells, and microglia-like cells play central roles in immune surveillance and inflammation. Cochlear implantation induces a robust foreign body response, and here we sought to map the spatial distribution of mononuclear phagocytes across distinct cochlear compartments in healthy cochleae and following implantation.
Materials and methods: We used two reporter mice in this study: C57BL/6-Tmem119em2Gfng/J (TMEM119+/GFP as reporter for microglia), B6. FVB-1700016L21RikTg (Itgax-DTR/EGFP)57Lan/J (CD11c+/GFP as reporter for dendritic cells). To define the spatial organization of different types of mononuclear phagocytes in normal cochleae and after implantation, 30-μm mid-modiolar cochlear sections from these reporter mice were imaged using a confocal microscope. Immunolabeling with cell-specific and activation markers was used to further characterize the cellular distributions and responses.
Results: We identify heterogeneous distribution of mononuclear phagocytes throughout the cochlea. CD11c-positive dendritic cells display a more restricted baseline distribution, residing primarily in Rosenthal’s canal and the spiral ligament; they selectively accumulate at the implant–tissue interface in the scala tympani after implantation and upregulate major histocompatibility complex class II expression, consistent with antigen-presenting phenotypes. In addition, expression of microglia-associated markers, including TMEM119 and P2Y12, identifies a microglia-like population within specific cochlear sub-regions that persists following implantation.
Conclusion: Together, these findings reveal an immune landscape in the cochlea under both healthy and implant-associated inflammatory conditions. CD11c-positive dendritic cells appear to play a central role in the inflammatory response to cochlear implants, becoming activated and localizing to the interface with the biomaterial surface.
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BibTeX
@article{fatima2026tissueresident,
title = {{Tissue-resident and recruited mononuclear phagocyte organization in the cochlea under homeostasis and implant-induced inflammation}},
author = {Shakila Mahmuda Fatima and Muhammad Taifur Rahman and Brian J. Mostaert and Ibrahim Razu and Bryce Hunger and Shanta Afrin and Sharar Naiarin Haque and Nashwaan Ali Khan and Zhenshen Zhang and Alexander D. Claussen and Marlan R. Hansen},
journal = {Frontiers in cellular neuroscience},
year = {2026},
month = oct,
doi = {10.3389/fncel.2026.1895870},
url = {https://europepmc.org/article/PMC/PMC13719395},
note = {CC BY},
}
RIS
TY - JOUR
TI - Tissue-resident and recruited mononuclear phagocyte organization in the cochlea under homeostasis and implant-induced inflammation
AU - Shakila Mahmuda Fatima
AU - Muhammad Taifur Rahman
AU - Brian J. Mostaert
AU - Ibrahim Razu
AU - Bryce Hunger
AU - Shanta Afrin
AU - Sharar Naiarin Haque
AU - Nashwaan Ali Khan
AU - Zhenshen Zhang
AU - Alexander D. Claussen
AU - Marlan R. Hansen
PY - 2026
DA - 2026/10/16
JO - Frontiers in cellular neuroscience
DO - 10.3389/fncel.2026.1895870
UR - https://europepmc.org/article/PMC/PMC13719395
AB - Background: The cochlea contains a diverse population of immune cells that contribute to tissue homeostasis and to responses to injury. Among these, mononuclear phagocytes including tissue-resident macrophages, dendritic cells, and microglia-like cells play central roles in immune surveillance and inflammation. Cochlear implantation induces a robust foreign body response, and here we sought to map the spatial distribution of mononuclear phagocytes across distinct cochlear compartments in healthy cochleae and following implantation. Materials and methods: We used two reporter mice in this study: C57BL/6-Tmem119em2Gfng/J (TMEM119+/GFP as reporter for microglia), B6. FVB-1700016L21RikTg (Itgax-DTR/EGFP)57Lan/J (CD11c+/GFP as reporter for dendritic cells). To define the spatial organization of different types of mononuclear phagocytes in normal cochleae and after implantation, 30-μm mid-modiolar cochlear sections from these reporter mice were imaged using a confocal microscope. Immunolabeling with cell-specific and activation markers was used to further characterize the cellular distributions and responses. Results: We identify heterogeneous distribution of mononuclear phagocytes throughout the cochlea. CD11c-positive dendritic cells display a more restricted baseline distribution, residing primarily in Rosenthal’s canal and the spiral ligament; they selectively accumulate at the implant–tissue interface in the scala tympani after implantation and upregulate major histocompatibility complex class II expression, consistent with antigen-presenting phenotypes. In addition, expression of microglia-associated markers, including TMEM119 and P2Y12, identifies a microglia-like population within specific cochlear sub-regions that persists following implantation. Conclusion: Together, these findings reveal an immune landscape in the cochlea under both healthy and implant-associated inflammatory conditions. CD11c-positive dendritic cells appear to play a central role in the inflammatory response to cochlear implants, becoming activated and localizing to the interface with the biomaterial surface.
SN - 1662-5102
ER -