Csf1 Signaling Regulates Maintenance of Resident Macrophages and Bone Formation in the Mouse Cochlea

In the mammalian cochlea, resident macrophages settle in the spiral ligament, spiral ganglion, and stria vascularis, even at the steady state. Resident macrophages in the cochlea are believed to maintain homeostasis in the inner ear and become active, as part of the front line defense, following inner ear damage. However, the exact roles of cochlear resident macrophages require further clarification. Colony stimulating factor-1 (Csf1) signaling regulates survival, proliferation, and differentiation of resident macrophages and appears to be essential for resident macrophages in the inner ear. To examine the roles of Csf1 signaling in auditory function, we examined the ossicles and inner ear of homozygous Csf1 mutant (Csf1op/op) mice. The ossicles including the incus and stapes of Csf1op/op mice macroscopically demonstrated bone thickening, and the otic capsules of the inner ear were also thick and opaque. Histological analyses demonstrated that the otic capsules in Csf1op/op mice were thickened and showed spongy bone degeneration. Measurements of the auditory brainstem response revealed significant elevation of thresholds in 4-week old Csf1op/op mice compared with wild-type littermates, indicating that Csf1op/op mice demonstrate hearing loss due to, at least in part, deformity of the ossicles and bone capsule of the inner ear. Furthermore, Csf1op/op mice are deficient in the number of resident macrophages in the spiral ligament and stria vascularis, but not in the spiral ganglion. These data provide evidence that Csf1 signaling is important not only for bone formation in the inner ear, but also for the maintenance of resident macrophages in the spiral ligament and stria vascularis in the adult mouse cochlea

Early Development of Resident Macrophages in the Mouse Cochlea Depends on Yolk Sac Hematopoiesis

Resident macrophages reside in all tissues throughout the body and play a central role in both tissue homeostasis and inflammation. Although the inner ear was once believed to be “immune-privileged, ” recent studies have shown that macrophages are distributed in the cochlea and may play important roles in the immune system thereof. Resident macrophages have heterogeneous origins among tissues and throughout developmental stages. However, the origins of embryonic cochlear macrophages remain unknown. Here, we show that the early development of resident macrophages in the mouse cochlea depends on yolk sac hematopoiesis. Accordingly, our results found that macrophages emerging around the developing otocyst at E10.5 exhibited dynamic changes in distribution and in situ proliferative capacity during embryonic and neonatal stages. Cochlear examination in Csf1r-null mice revealed a substantial decrease in the number of Iba1-positive macrophages in the spiral ganglion and spiral ligament, whereas they were still observed in the cochlear mesenchyme or on the intraluminal surface of the perilymphatic space. Our results demonstrated that two subtypes of resident macrophages are present in the embryonic cochlea, one being Csf1r-dependent macrophages that originate from the yolk sac and the other being Csf1r-independent macrophages that appear to be derived from the fetal liver via systemic circulation. We consider the present study to be a starting point for elucidating the roles of embryonic cochlear resident macrophages. Furthermore, resident macrophages in the embryonic cochlea could be a novel target for the treatment of various inner ear disorders

Stepwise fate conversion of supporting cells to sensory hair cells in the chick auditory epithelium

In contrast to mammals, the avian cochlea, specifically the basilar papilla, can regenerate sensory hair cells, which involves fate conversion of supporting cells to hair cells. To determine the mechanisms for converting supporting cells to hair cells, we used single-cell RNA sequencing during hair cell regeneration in explant cultures of chick basilar papillae. We identified dynamic changes in the gene expression of supporting cells, and the pseudotime trajectory analysis demonstrated the stepwise fate conversion from supporting cells to hair cells. Initially, supporting cell identity was erased and transition to the precursor state occurred. A subsequent gain in hair cell identity progressed together with downregulation of precursor-state genes. Transforming growth factor β receptor 1-mediated signaling was involved in induction of the initial step, and its inhibition resulted in suppression of hair cell regeneration. Our data provide new insights for understanding fate conversion from supporting cells to hair cells in avian basilar papillae

Disinfection of otorhinolaryngological endoscopes with electrolyzed acid water: A cross-sectional and multicenter study

Glutaraldehyde, a germicide for reprocessing endoscopes that is important for hygiene in the clinic, might be hazardous to humans. Electrolyzed acid water (EAW) has a broad anti-microbial spectrum and safety profile and might be a glutaraldehyde alternative. We sought to assess EAW disinfection of flexible endoscopes in clinical otorhinolaryngological settings and its in vitro inactivation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and bacteria commonly isolated in otorhinolaryngology. Ninety endoscopes were tested for bacterial contamination before and after endoscope disinfection with EAW. The species and strains of bacteria were studied. The in vitro inactivation of bacteria and SARS-CoV-2 by EAW was investigated to determine the efficacy of endoscope disinfection. More than 20 colony-forming units of bacteria at one or more sampling sites were detected in 75/90 microbiological cultures of samples from clinically used endoscopes (83.3%). The most common genus detected was Staphylococcus followed by Cutibacterium and Corynebacterium at all sites including the ears, noses, and throats. In the in vitro study, more than 107 CFU/mL of all bacterial species examined were reduced to below the detection limit ( 105 PFU) was decreased to less than 5 PFU. Effective inactivation of SARS-CoV-2 was also observed with a 19:1 ratio of EAW to the virus. EAW effectively reprocessed flexible endoscopes contributing to infection control in medical institutions in the era of the coronavirus disease 2019 pandemic

Organ accumulation and carcinogenicity of highly dispersed multi-walled carbon nanotubes administered intravenously in transgenic rasH2 mice

Purpose: Multiwalled carbon nanotubes (MWCNTs) have been known to enter the circulatory system via the lungs from inhalation exposure; however, its carcinogenicity and subsequent accumulation in other organs have not been adequately reported in the literature. Moreover, the safety of MWCNTs as a biomaterial has remained a matter of debate, particularly when the material enters the circulatory system. To address these problems, we used carcinogenic rasH2 transgenic mice to intravenously administer highly dispersed MWCNTs and to evaluate their carcinogenicity and accumulation in the organs. Methods: Two types of MWCNTs (thin-and thick-MWCNTs) were intravenously administered at a high dose (approximately 0.7 mg per kg body weight) and low dose (approximately 0.07 mg per kg body weight). Results: MWCNTs showed pancreatic accumulation in 3.2% of mice administered with MWCNTs, but there was no accumulation in other organs. In addition, there was no significant difference in the incidence of tumor among the four MWCNTs-administered groups compared to the vehicle group without MWCNTs administration. Blood tests revealed elevated levels in mean red blood cell volume and mean red blood cell hemoglobin level for the MWCNTs-administered group, in addition to an increase in eotaxin. Conclusion: The present study demonstrated that the use of current technology to sufficiently disperse MWCNTs resulted in minimal organ accumulation with no evidence of carcinogenicity.ArticleINTERNATIONAL JOURNAL OF NANOMEDICINE. 14:6465-6480 (2019)journal articl

Drug retention of biologics and Janus kinase inhibitors in patients with rheumatoid arthritis: the ANSWER cohort study

OBJECTIVES: This multicentre retrospective study in Japan aimed to assess the retention of biological disease-modifying antirheumatic drugs and Janus kinase inhibitors (JAKi), and to clarify the factors affecting their retention in a real-world cohort of patients with rheumatoid arthritis. METHODS: The study included 6666 treatment courses (bDMARD-naïve or JAKi-naïve cases, 55.4%; tumour necrosis factor inhibitors (TNFi) = 3577; anti-interleukin-6 receptor antibodies (aIL-6R) = 1497; cytotoxic T lymphocyte-associated antigen-4-Ig (CTLA4-Ig) = 1139; JAKi=453 cases). The reasons for discontinuation were divided into four categories (ineffectiveness, toxic adverse events, non-toxic reasons and remission); multivariate Cox proportional hazards modelling by potential confounders was used to analyse the HRs of treatment discontinuation. RESULTS: TNFi (HR=1.93, 95% CI: 1.69 to 2.19), CTLA4-Ig (HR=1.42, 95% CI: 1.20 to 1.67) and JAKi (HR=1.29, 95% CI: 1.03 to 1.63) showed a higher discontinuation rate due to ineffectiveness than aIL-6R. TNFi (HR=1.28, 95% CI: 1.05 to 1.56) and aIL-6R (HR=1.27, 95% CI: 1.03 to 1.57) showed a higher discontinuation rate due to toxic adverse events than CTLA4-Ig. Concomitant use of oral glucocorticoids (GCs) at baseline was associated with higher discontinuation rate due to ineffectiveness in TNFi (HR=1.24, 95% CI: 1.09 to 1.41), as well as toxic adverse events in JAKi (HR=2.30, 95% CI: 1.23 to 4.28) and TNFi (HR=1.29, 95%CI: 1.07 to 1.55). CONCLUSIONS: TNFi (HR=1.52, 95% CI: 1.37 to 1.68) and CTLA4-Ig (HR=1.14, 95% CI: 1.00 to 1.30) showed a higher overall drug discontinuation rate, excluding non-toxicity and remission, than aIL-6R.Ebina K., Etani Y., Maeda Y., et al. Drug retention of biologics and Janus kinase inhibitors in patients with rheumatoid arthritis: the ANSWER cohort study. RMD open 9, (2023); https://doi.org/10.1136/rmdopen-2023-003160

Large-Area Fluorescence and Electron Microscopic Correlative Imaging With Multibeam Scanning Electron Microscopy

Recent improvements in correlative light and electron microscopy (CLEM) technology have led to dramatic improvements in the ability to observe tissues and cells. Fluorescence labeling has been used to visualize the localization of molecules of interest through immunostaining or genetic modification strategies for the identification of the molecular signatures of biological specimens. Newer technologies such as tissue clearing have expanded the field of observation available for fluorescence labeling; however, the area of correlative observation available for electron microscopy (EM) remains restricted. In this study, we developed a large-area CLEM imaging procedure to show specific molecular localization in large-scale EM sections of mouse and marmoset brain. Target molecules were labeled with antibodies and sequentially visualized in cryostat sections using fluorescence and gold particles. Fluorescence images were obtained by light microscopy immediately after antibody staining. Immunostained sections were postfixed for EM, and silver-enhanced sections were dehydrated in a graded ethanol series and embedded in resin. Ultrathin sections for EM were prepared from fully polymerized resin blocks, collected on silicon wafers, and observed by multibeam scanning electron microscopy (SEM). Multibeam SEM has made rapid, large-area observation at high resolution possible, paving the way for the analysis of detailed structures using the CLEM approach. Here, we describe detailed methods for large-area CLEM in various tissues of both rodents and primates

Ambient fine and coarse particles in Japan affect nasal and bronchial epithelial cells differently and elicit varying immune response

Ambient particulate matter (PM) epidemiologically exacerbates respiratory and immune health, including allergic rhinitis (AR) and bronchial asthma (BA). Although fine and coarse particles can affect respiratory tract, the differences in their effects on the upper and lower respiratory tract and immune system, their underlying mechanism, and the components responsible for the adverse health effects have not been yet completely elucidated. In this study, ambient fine and coarse particles were collected at three different locations in Japan by cyclone technique. Both particles collected at all locations decreased the viability of nasal epithelial cells and antigen presenting cells (APCs), increased the production of IL-6, IL-8, and IL-1β from bronchial epithelial cells and APCs, and induced expression of dendritic and epithelial cell (DEC) 205 on APCs. Differences in inflammatory responses, but not in cytotoxicity, were shown between both particles, and among three locations. Some components such as Ti, Co, Zn, Pb, As, OC (organic carbon) and EC (elemental carbon) showed significant correlations to inflammatory responses or cytotoxicity. These results suggest that ambient fine and coarse particles differently affect nasal and bronchial epithelial cells and immune response, which may depend on particles size diameter, chemical composition and source related particles types

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京都大学0048新制・課程博士博士(医学)甲第13669号医博第3184号新制||医||965(附属図書館)UT51-2008-C587京都大学大学院医学研究科外科系専攻(主査)教授 篠原 隆司, 教授 芹川 忠夫, 教授 野田 亮学位規則第4条第1項該当Doctor of Medical ScienceKyoto UniversityDA