Activation of the antigen presentation function of mononuclear phagocyte populations associated with the basilar membrane of the cochlea after acoustic overstimulation. (10th September 2015)

• Record Type: Journal Article
• Authors: Yang, W.; Vethanayagam, R.R.; Dong, Y.; Cai, Q.; Hu, B.H.
• Is Part Of: Neuroscience. Volume 303(2015)
• Page Start: 1
• Page End: 15
• Publication Date: 2015-09-10
• Subjects: ABR auditory brainstem response -- BM basilar membrane -- BSA bovine serum albumin -- MHC major histocompatibility complex -- PBS phosphate-buffered saline -- qRT-PCR quantitative reverse transcription-polymerase chain reaction; macrophage -- cochlea -- noise -- antigen -- MHC II -- immunity; Neurochemistry -- Periodicals; Neurophysiology -- Periodicals; Neurology -- Periodicals; Neurochimie -- Périodiques; Neurophysiologie -- Périodiques; Neurochemistry; Neurophysiology; Electronic journals; Periodicals; Electronic journals; 612.8
• DOI: 10.1016/j.neuroscience.2015.05.081
• Languages: English
• ISSNs: 0306-4522

Abstract

Highlights: Diverse macrophage populations reside beneath the basilar membrane of the cochlea. Monocytes undergo a time-dependent transformation into macrophages after acoustic overstimulation. Acoustic overstimulation induces the upregulation of antigen-presenting proteins in the mononuclear phagocytes. CD4 + T cells participate in antigen-presenting activity in response to acoustic overstimulation. Activation of antigen-presenting function is an immune cell response to acoustic overstimulation. Abstract: 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. Notably, these cells in the apical and the basal sections of the basilar membrane display distinct morphologies and immune protein expression patterns. Following acoustic trauma, monocytes infiltrate into the region of the basilar membrane, and the infiltrated cells transform into macrophages. While monocyte infiltration and transformation occur in both the apical and the basal sections of the basilar membrane, only the basal monocytes and macrophages display a marked increase in the expression of major histocompatibility complex (MHC) II and class II transactivator (CIITA), a MHC II production cofactor, suggesting the site-dependent activation of antigen-presenting function. Consistent with the increased expression of the antigen-presenting proteins, CD4 + T cells, the antigen-presenting partner, infiltrate into the region of the basilar membrane where antigen-presenting proteins are upregulated. Further pathological analyses revealed that the basal section of the cochlea displays a greater level of sensory cell damage, which is spatially correlated with the region of antigen-presenting activity. Together, these results suggest that the antigen-presenting function of the mononuclear phagocyte population is activated in response to acoustic trauma, which could bridge the innate immune response to adaptive immunity.