Endoplasmic reticulum stress-induced necroptosis promotes cochlear inflammation: Implications for age-related hearing loss

Age-related hearing loss (ARHL) is the most common sensory disorder associated with human aging. Chronic inflammation is supposed to be an important contributor to ARHL. Yet, the underlying mechanisms of developing cochlear inflammation are still not well understood. In this study, we found that the inflammation, endoplasmic reticulum (ER) stress and Necroptosis signalings are activated in the cochlea of aged C57BL/6 mice. ER stress activator tunicamycin (TM) induced Necroptosis in cochlear HEI-OC1 cells and cochlear explants, while Necroptosis inhibitors protected cochlear cells from ER stress-induced cell death. The antioxidants inhibited Necroptosis and protected HEI-OC1 cells from TM insults. Necroptotic HEI-OC1 cells promoted the activation of the co-cultured macrophages via MyD88 signaling. Moreover, Necroptosis Inhibitor protected from TM-induced hearing loss, and inhibited inflammation in C57BL/6 mice. These findings suggest that ER stress-induced Necroptosis promotes cochlear inflammation and hearing loss. Targeting Necroptosis serves as a potential approach for the treatment of cochlear inflammation and ARHL.

Age-related hearing loss; Cochlea; Endoplasmic reticulum stress; Inflammation; Macrophage; Necroptosis.