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Cochlear macrophage

Jacek Dutkiewicz, Violetta Zając, Jacek Sroka, Bernard Wasiński, Ewa Cisak, Anna Sawczyn, Anna Kloc, Angelina Wójcik-Fatla
<i>Streptococcus suis</i> is a re-emerging zoonotic pathogen that may cause severe disease, mostly meningitis, in pigs and in humans having occupational contact with pigs and pork, such as farmers, slaughterhose workers and butchers. The first stage of the pathogenic process, similar in pigs and humans, is adherence to and colonisation of mucosal and/or epithelial surface(s) of the host. The second stage is invasion into deeper tissue and extracellular translocation of bacterium in the bloodstream, either free in circulation or attached to the surface of monocytes...
March 14, 2018: Annals of Agricultural and Environmental Medicine: AAEM
Wei Liu, Matyas Molnar, Carolyn Garnham, Heval Benav, Helge Rask-Andersen
The human inner ear, which is segregated by a blood/labyrinth barrier, contains resident macrophages [CD163, ionized calcium-binding adaptor molecule 1 (IBA1)-, and CD68-positive cells] within the connective tissue, neurons, and supporting cells. In the lateral wall of the cochlea, these cells frequently lie close to blood vessels as perivascular macrophages. Macrophages are also shown to be recruited from blood-borne monocytes to damaged and dying hair cells induced by noise, ototoxic drugs, aging, and diphtheria toxin-induced hair cell degeneration...
2018: Frontiers in Immunology
Bo Hua Hu, Celia Zhang, Mitchell D Frye
The cochlea has an immune environment dominated by macrophages under resting conditions. When stressed, circulating monocytes enter the cochlea. These immune mediators, along with cochlear resident cells, organize a complex defense response against pathological challenges. Since the cochlea has minimal exposure to pathogens, most inflammatory conditions in the cochlea are sterile. Although the immune response is initiated for the protection of the cochlea, off-target effects can cause collateral damage to cochlear cells...
December 20, 2017: Hearing Research
Tejbeer Kaur, Kevin K Ohlemiller, Mark E Warchol
Cochlear hair cells are vulnerable to a variety of insults like acoustic trauma and ototoxic drugs. Such injury can also lead to degeneration of spiral ganglion neurons (SGNs), but this occurs over a period of months to years. Neuronal survival is necessary for the proper function of cochlear prosthetics, therefore, it is of great interest to understand the mechanisms that regulate neuronal survival in deaf ears. We have recently demonstrated that selective hair cell ablation is sufficient to attract leukocytes into the spiral ganglion, and that fractalkine signaling plays a role in macrophage recruitment and in the survival of auditory neurons...
April 1, 2018: Journal of Comparative Neurology
Wenjing Zhang, Jian Zheng, Juan Meng, Lingling Neng, Xiaohua Chen, Zhaobing Qin
Previous studies have suggested that macrophage migration inhibitory factor (MIF) serves an important role in hearing function; however, the underlying mechanism remains unclear. In the present study, perivascular‑resident macrophage‑like melanocytes (PVM/Ms) from the stria vascularis of the lateral cochlear wall in young and aged mice were isolated. The mRNA and protein expression levels of MIF were determined using reverse transcription‑quantitative polymerase chain reaction analysis, and western blotting, respectively...
December 2017: Molecular Medicine Reports
Yu Mizushima, Chisato Fujimoto, Akinori Kashio, Kenji Kondo, Tatsuya Yamasoba
It has been suggested that macrophages or inflammatory monocytes participate in the pathology of noise-induced hearing loss (NIHL), but it is unclear how extensively these cells contribute to the development of temporary and/or permanent NIHL. To address this question, we used clodronate liposomes to deplete macrophages and monocytes. After clodronate liposome injection, mice were exposed to 4-kHz octave band noise at 121 dB for 4 h. Compared to vehicle-injected controls, clodronate-treated mice exhibited significantly reduced permanent threshold shifts at 4 and 8 kHz and significantly smaller outer hair cell losses in the lower-apical cochlear turn...
November 18, 2017: Biochemical and Biophysical Research Communications
Celia Zhang, Wei Sun, Ji Li, Binbin Xiong, Mitchell D Frye, Dalian Ding, Richard Salvi, Mi-Jung Kim, Shinichi Someya, Bo Hua Hu
Sestrin 2 (SESN2) is a stress-inducible protein that protects tissues from oxidative stress and delays the aging process. However, its role in maintaining the functional and structural integrity of the cochlea is largely unknown. Here, we report the expression of SESN2 protein in the sensory epithelium, particularly in hair cells. Using C57BL/6J mice, a mouse model of age-related cochlear degeneration, we observed a significant age-related reduction in SESN2 expression in cochlear tissues that was associated with early onset hearing loss and accelerated age-related sensory cell degeneration that progressed from the base toward the apex of the cochlea...
October 11, 2017: Neuroscience
Jennifer T O'Malley, Barbara J Burgess, Donald Galler, Joseph B Nadol
HYPOTHESIS: Silicone as part of a cochlear implant electrode may be responsible for a foreign body response in the human. BACKGROUND: Clinical evidence of a foreign body response to a cochlear implant has been reported. In a previous study, particulate material found within the fibrous sheath and within macrophages surrounding a cochlear implant has been identified as being consistent with platinum. However, to date, there has been no histologic evidence of a role for silicone in this cellular immune response...
August 2017: Otology & Neurotology
Megan B Wood, Jian Zuo
Cells of the immune system have been shown to infiltrate the cochlea after acoustic trauma or ototoxic drug treatment; however, the contribution of the immune system to hair cell loss in the inner ear is incompletely understood. Most studies have concentrated on the immediate innate response to hair cell damage using CD45 as a broad marker for all immune cells. More recent studies have used RNA sequencing, GeneChip arrays and quantitative PCR to analyze gene expression in the entire cochlea after auditory trauma, leading to a better understanding of the chemokines and cytokines that attract immune cells to the cochlea...
2017: Frontiers in Cellular Neuroscience
Jinhui Zhang, Songlin Chen, Jing Cai, Zhiqiang Hou, Xiaohan Wang, Allan Kachelmeier, Xiaorui Shi
The vestibular blood-labyrinth barrier (BLB) is comprised of perivascular-resident macrophage-like melanocytes (PVM/Ms) and pericytes (PCs), in addition to endothelial cells (ECs) and basement membrane (BM), and bears strong resemblance to the cochlear BLB in the stria vascularis. Over the past few decades, in vitro cell-based models have been widely used in blood-brain barrier (BBB) and blood-retina barrier (BRB) research, and have proved to be powerful tools for studying cell-cell interactions in their respective organs...
March 2017: Hearing Research
Poornapriya Ramamurthy, Joshua B White, Joong Yull Park, Richard I Hume, Fumi Ebisu, Flor Mendez, Shuichi Takayama, Kate F Barald
BACKGROUND: To send meaningful information to the brain, an inner ear cochlear implant (CI) must become closely coupled to as large and healthy a population of remaining spiral ganglion neurons (SGN) as possible. Inner ear gangliogenesis depends on macrophage migration inhibitory factor (MIF), a directionally attractant neurotrophic cytokine made by both Schwann and supporting cells (Bank et al., 2012). MIF-induced mouse embryonic stem cell (mESC)-derived "neurons" could potentially substitute for lost or damaged SGN...
January 2017: Developmental Dynamics: An Official Publication of the American Association of Anatomists
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...
June 2, 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
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