FIGURE 3.

Cochlin-deficient mice demonstrate reduced pro-inflammatory response to acoustic trauma in cochlear soft tissue and perilymph. Six-week-old Coch^–/– and Coch^+/+ mice were exposed to 8–16 kHz noise for 2 h at 103 dB SPL. Unexposed mice served as controls. (A) Six hours post exposure, cochlear perilymph of wild-type animals demonstrated significantly increased levels of the cleaved LCCL domain (18 kDa fragment) compared to unexposed animals. Data are shown as group means of relative protein level of 18 kDa LCCL fragment (p18) ± standard error of the mean. ^∗∗P < 0.01 (unpaired t-test). Cochlear perilymph was collected through the posterior semicircular canal. Expression of LCCL fragment was determined by Western blotting using an anti-cochlin monoclonal antibody. Protein level of LCCL fragment was calculated as a ratio of LCCL p18 protein bands relative to the total protein bands. N = 3 ears from unexposed mice, 7 ears from exposed mice. (B) Cochleae collected 6 h post exposure had statistically significant elevation of Il6 and Cxcl1 gene expression in Coch^+/+ compared to Coch^–/– mice, and demonstrated a similar trend that did not meet our criterion for significance for Adamts4, Il1b, and Tnf. N = 7 animals per group. Data are shown as group means ± standard error of the mean. ^∗P < 0.05, ^∗∗P < 0.01. (C) Six hours post exposure, perilymph demonstrated significantly lower CXCL1 levels in Coch^–/– compared to Coch^+/+ mice and trends toward lower IL-6, TNF-α, and IL-1β levels, that did not meet our criterion of statistical significance. Data are shown as group means ± standard error of the mean. ^∗P < 0.05, ^****P < 0.0001. Vestibular perilymph (vPLF), cochlear perilymph (cPLF), and cerebrospinal fluid (CSF) were collected through the posterior semicircular canal. N = 4 Coch^+/+ unexposed ears, 5 Coch^+/+ exposed ears, 9 Coch^–/– unexposed ears, and 10 Coch^–/– exposed ears.