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Cochlear macrophage

R R Vethanayagam, W Yang, Y Dong, B H Hu
Acoustic overstimulation traumatizes the cochlea, resulting in auditory dysfunction. As a consequence of acoustic injury, the immune system in the cochlea is activated, leading to the production of inflammatory mediators and the infiltration of immune cells. However, the molecular mechanisms responsible for initiating these immune responses remain unclear. Here, we investigate the functional role of Toll-like receptor 4 (Tlr4), a cellular receptor that activates the innate immune system, in the regulation of cochlear responses to acoustic overstimulation...
2016: Cell Death & Disease
Hao Feng, Ilmari Pyykkö, Jing Zou
Silver nanoparticles (AgNPs) were shown to temporarily impair the biological barriers in the skin of the external ear canal, mucosa of the middle ear, and inner ear, causing partially reversible hearing loss after delivery into the middle ear. The current study aimed to elucidate the molecular mechanism, emphasizing the TLR signaling pathways in association with the potential recruitment of macrophages in the cochlea and the modulation of inflammation by ubiquitin-editing protein A20. Molecules potentially involved in these signaling pathways were thoroughly analysed using immunohistochemistry in the rat cochlea exposed to AgNPs at various concentrations through intratympanic injection...
December 2016: Nanoscale Research Letters
L Astolfi, E Simoni, N Giarbini, P Giordano, M Pannella, S Hatzopoulos, A Martini
Dexamethasone is a common anti-inflammatory agent added to cochlear implants to reduce hearing loss due to electrode insertion trauma. We evaluated the safety of eluting silicone rods containing 10% dexamethasone in a Guinea pig model. Animals were implanted with a dexamethasone eluting silicone electrode (DER) or with a non-eluting electrode (NER). The control group only underwent a cochleostomy (CS). Prior to implantation and during the two weeks following implantation, the hearing status of the animals was assessed by means of Compound Action Potentials (CAPs) with an electrode placed near the round window...
June 2016: Hearing Research
Kathryn Spiers, Tina Cardamone, John B Furness, Jonathan C M Clark, James F Patrick, Graeme M Clark
OBJECTIVES: The aim of this study was to analyse the tissue surrounding the University of Melbourne's (UOMs) multi-channel cochlear implant electrode array and cochlear limited replacements, after long-term implantations. In particular, it aimed to identify the particulate material in the fibrous tissue capsule of the arrays implanted in 1978, 1983, and 1998, by using the Australian Synchrotron for X-ray fluorescence microscopy (XFM) to reveal the characteristic spectrum of metal, in particular platinum...
May 2016: Cochlear Implants International
Xiaorui Shi
The blood-labyrinth barrier (BLB) in the stria vascularis is a highly specialized capillary network that controls exchanges between blood and the intrastitial space in the cochlea. The barrier shields the inner ear from blood-born toxic substances and selectively passes ions, fluids, and nutrients to the cochlea, playing an essential role in the maintenance of cochlear homeostasis. Anatomically, the BLB is comprised of endothelial cells (ECs) in the strial microvasculature, elaborated tight and adherens junctions, pericytes (PCs), basement membrane (BM), and perivascular resident macrophage-like melanocytes (PVM/Ms), which together form a complex "cochlear-vascular unit" in the stria vascularis...
August 2016: Hearing Research
Tejbeer Kaur, Darius Zamani, Ling Tong, Edwin W Rubel, Kevin K Ohlemiller, Keiko Hirose, Mark E Warchol
UNLABELLED: Macrophages are recruited into the cochlea in response to injury caused by acoustic trauma or ototoxicity, but the nature of the interaction between macrophages and the sensory structures of the inner ear remains unclear. The present study examined the role of fractalkine signaling in regulating the injury-evoked behavior of macrophages following the selective ablation of cochlear hair cells. We used a novel transgenic mouse model in which the human diphtheria toxin receptor (huDTR) is selectively expressed under the control of Pou4f3, a hair cell-specific transcription factor...
November 11, 2015: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Esperanza Bas, Stefania Goncalves, Michelle Adams, Christine T Dinh, Jose M Bas, Thomas R Van De Water, Adrien A Eshraghi
Conservation of a patient's residual hearing and prevention of fibrous tissue/new bone formation around an electrode array are some of the major challenges in cochlear implant (CI) surgery. Although it is well-known that fibrotic tissue formation around the electrode array can interfere with hearing performance in implanted patients, and that associated intracochlear inflammation can initiate loss of residual hearing, little is known about the molecular and cellular mechanisms that promote this response in the cochlea...
2015: Frontiers in Cellular Neuroscience
W Yang, R R Vethanayagam, Y Dong, Q Cai, B H Hu
The immune response is an important component of the cochlear response to stress. As an important player in the cochlear immune system, the basilar membrane immune cells reside on the surface of the scala tympani side of the basilar membrane. At present, the immune cell properties in this region and their responses to stress are not well understood. Here, we investigated the functional role of these immune cells in the immune response to acoustic overstimulation. This study reveals that tissue macrophages are present in the entire length of the basilar membrane under steady-state conditions...
September 10, 2015: Neuroscience
Shin Kariya, Mitsuhiro Okano, Yukihide Maeda, Haruka Hirai, Takaya Higaki, Yasuyuki Noyama, Takenori Haruna, Jun Nishihira, Kazunori Nishizaki
HYPOTHESIS: Macrophage migration inhibitory factor plays an important role in noise-induced hearing loss. BACKGROUND: Macrophage migration inhibitory factor is an essential factor in axis formation and neural development. Macrophage migration inhibitory factor is expressed in the inner ear, but its function remains to be elucidated. METHODS: Macrophage migration inhibitory factor-deficient mice (MIF(-/-) mice) were used in this study. Wild-type and MIF(-/-) mice received noise exposure composed of octave band noise...
July 2015: Otology & Neurotology
Jinhui Zhang, Songlin Chen, Zhiqiang Hou, Jing Cai, Mingmin Dong, Xiaorui Shi
Middle ear infection (or inflammation) is the most common pathological condition that causes fluid to accumulate in the middle ear, disrupting cochlear homeostasis. Lipopolysaccharide, a product of bacteriolysis, activates macrophages and causes release of inflammatory cytokines. Many studies have shown that lipopolysaccharides cause functional and structural changes in the inner ear similar to that of inflammation. However, it is specifically not known how lipopolysaccharides affect the blood-labyrinth barrier in the stria vascularis (intra-strial fluid-blood barrier), nor what the underlying mechanisms are...
2015: PloS One
Lingling Neng, Jinhui Zhang, Ju Yang, Fei Zhang, Ivan A Lopez, Mingmin Dong, Xiaorui Shi
Tight control over cochlear blood flow (CoBF) and the blood-labyrinth barrier (BLB) in the striavascularis is critical for maintaining the ionic, fluid and energy balance necessary for hearing function. Inefficient CoBF and disruption of BLB integrity have long been considered major etiologic factors in a variety of hearing disorders. In this study, we investigate structural changes in the BLB of the striavascularis in age-graded C57BL/6 mice (1 to 21 months) with a focus on changes in two blood barrier accessory cells, namely pericytes (PCs) and perivascular-resident macrophage-like melanocytes (PVM/Ms)...
September 2015: Cell and Tissue Research
Joseph B Nadol, Jennifer T O'Malley, Barbara J Burgess, Donald Galler
A cochlear implant array consists of biomaterials, including metal and polymeric in type which are biocompatible, but not necessarily bio-inert. Histologic evidence of a foreign body reaction has been described in temporal bones in patients who in life had undergone cochlear implantation. In the current study, the cellular immune response was characterized using immunohistochemical stains for B-cell lymphocytes (CD20), T-cell lymphocytes (CD3), and macrophages (CD68). In addition, energy dispersive spectroscopy by scanning electron microscopy (EDS-SEM) was performed to characterize the nature of particulate foreign material seen near the electrode array...
December 2014: Hearing Research
S Kariya, M Okano, Y Maeda, H Hirai, T Higaki, Y Noyama, T Haruna, J Nishihira, K Nishizaki
Hearing loss related to aging is the most common sensory disorder among elderly individuals. Macrophage migration inhibitory factor (MIF) is a multi-functional molecule. The aim of this study was to identify the role of MIF in the inner ear. MIF-deficient mice (MIF(-/-) mice) of BALB/c background and wild-type BALB/c mice were used in this study. Expression of MIF protein in the inner ear was examined by immunohistochemistry in wild-type mice (WT). The hearing function was assessed by the click-evoked auditory brainstem response in both MIF(-/-) mice and WT at 1, 3, 6, 9, 12, and 18months of age...
October 24, 2014: Neuroscience
Graeme M Clark, Jonathan Clark, Tina Cardamone, Maria Clarke, Prue Nielsen, Rob Jones, Benedicta Arhatari, Nick Birbilis, Roger Curtain, Jin Xu, Sheryl Wagstaff, Peter Gibson, Stephen O'Leary, John Furness
OBJECTIVE: To analyse the temporal bones and implant of the first University of Melbourne's (UOM) patient (MC-1) to receive the multi-channel cochlear prosthesis. METHODS: The left cochlea was implanted with the prototype multi-channel cochlear prosthesis on 1 August 1978, and the Cochlear versions CI-22 and CI-24 on 22 June 1983 and 10 November 1998, respectively. MC-1 died in 2007. RESULTS: Plain X-rays of the temporal bones showed that after the CI-22 had been explanted seven electrode bands remained in situ...
September 2014: Cochlear Implants International
Shan Sun, Huiqian Yu, Hui Yu, Mei Honglin, Wenli Ni, Yanping Zhang, Luo Guo, Yingzi He, Zhen Xue, Yusu Ni, Jin Li, Yi Feng, Yan Chen, Ruijin Shao, Renjie Chai, Huawei Li
One of the most unfortunate side effects of aminoglycoside (AG) antibiotics such as neomycin is that they target sensory hair cells (HCs) and can cause permanent hearing impairment. We have observed HC loss and microglia-like cell (MLC) activation in the inner ear (cochlea) following neomycin administration. We focused on CX3CL1, a membrane-bound glycoprotein expressed on neurons and endothelial cells, as a way to understand how the MLCs are activated and the role these cells play in HC loss. CX3CL1 is the exclusive ligand for CX3CR1, which is a chemokine receptor expressed on the surface of macrophages and MLCs...
February 2015: Molecular Neurobiology
Masato Fujioka, Yasuhide Okamoto, Seiichi Shinden, Hirotaka James Okano, Hideyuki Okano, Kaoru Ogawa, Tatsuo Matsunaga
Cochlear lateral wall has recently been reported as a common site of inflammation, yet precise molecular mechanisms of the inflammatory responses remain elucidated. The present study examined the inflammatory responses in the lateral wall following acute mitochondrial dysfunction induced by a mitochondrial toxin, 3-nitropropionic acid (3-NP). Reverse-transcription (RT)-PCR revealed increases in the expression of the proinflammatory cytokines interleukin (IL)-1β and IL-6. Immunohistochemistry showed an increase in the number of activated cochlear macrophages in the lateral wall, which were in close proximity to IL-6-expressing cells...
2014: PloS One
Martin Nue Møller, Christian Brandt, Christian Østergaard, Per Caye-Thomasen
OBJECTIVE: To examine the pathways of bacterial invasion and subsequent spreading in the inner ear during pneumococcal meningitis. STUDY DESIGN: A well-established adult rat model of Streptococcus pneumoniae meningitis was used. METHODS: Thirty rats were inoculated intrathecally with S. pneumoniae serotype 1, 3 or 9 V and received no additional treatment. The rats were sacrificed when reaching terminal illness or on Day 7 and then prepared for serial sectioning and PAS-Alcian blue staining for light microscopy...
June 2014: Otology & Neurotology
Gordana Elizabeth Kel, Justin Tan, Hayden Timothy Eastwood, Sarin Wongprasartsuk, Stephen John O'Leary
AIM: To examine the early cochlear response and intercellular cell adhesion molecule-1 (ICAM-1) expression to implantation of a cochlear electrode into the scala tympani. BACKGROUND: Understanding the early response of the cochlea to implantation may inform the duration which drug therapies should be delivered to protect hearing. METHODS: Guinea pigs were implanted with a cochlear electrode and survived 1, 2, or 7 days before they were euthanized, cochleae harvested, processed, and cryosectioned for light microscopy or ICAM-1 immunohistochemistry...
December 2013: Otology & Neurotology
Lourdes Quintanilla-Dieck, Barbara Larrain, Dennis Trune, Peter S Steyger
The objective was to detect changes in cytokine expression within cochleae in a murine model of systemic inflammation, with or without aminoglycoside exposure. Four groups of mice received 1 of the following: saline only, systemic bacterial lipopolysaccharides (LPS) for 6 hours to induce endotoxemia and inflammatory responses, systemic gentamicin for 3 hours, or both treatments. After exsanguination, pooled cochleae (4/group) were processed for enzyme-linked immunosorbent assay (ELISA) for 16 cytokines. Gentamicin alone did not change cochlear cytokine levels, while LPS (± gentamicin) substantially elevated cochlear expression of several cytokines, particularly interleukin-1α, interleukin-6, monocyte chemotactic protein-1, macrophage inflammatory protein-1α, and RANTES...
August 2013: Otolaryngology—Head and Neck Surgery
Johann Le Floc'h, Winston Tan, Ravindra S Telang, Srdjan M Vlajkovic, Alfred Nuttall, William D Rooney, Beau Pontré, Peter R Thorne
PURPOSE: To quantify spatial and temporal inflammation-induced changes in vascular permeability and macrophage infiltration in guinea-pig (GP) cochlea using MRI. MATERIALS AND METHODS: GPs were injected with lipopolysaccharide (LPS) to induce cochlear inflammation. One group was injected with a gadolinium based contrast agent (GBCA) and dynamic contrast enhanced (DCE)-MRI was performed at 4, 7, and 10 days after LPS treatment. A two-compartment pharmacokinetic model was used to determine the apparent rate constant of GBCA extravasation (K(trans) )...
January 2014: Journal of Magnetic Resonance Imaging: JMRI
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