Acoustic trauma is an important physical factor leading to cochlear damage and hearing impairments. Inflammation responds to this kind of cochlear damage stress. Macrophages, the major innate immune cells in the cochlea, are important drivers of inflammatory and tissue repair responses after cochlear injury. Recently, studies have shown that after noise exposure, the distribution, phenotype, and the number of cochlear macrophages have significantly changed, and the local environmental factors that shape macrophage differentiation and behavior are also drastically altered. However, the exact role of these immune cells in the cochlea after acoustic injury remains unknown. Here we review the properties of cochlear macrophages both under steady-state conditions and non-homeostatic conditions after cochlear acoustic injury and discuss their potential role in noise-exposed cochlea.
Figure 1. Macrophage changes after noise exposure in mouse cochlea (CX3CR1+/GFP transgenic mice generated on a CBA background). (A) In control cochlea, macrophages were relatively rare with ramified, dendritic phenotypes. (B) Seven days after noise exposure (110dB, white noise for 2 hours), cochlear macrophages were significantly increased with amoeboid morphology.
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