Effect of systemic lipopolysaccharide-induced inflammation on cytokine levels in the murine cochlea: A pilot study

The objective was to detect changes in cytokine expression within cochleae in a murine model of systemic inflammation, with or without aminoglycoside exposure. Four groups of mice received 1 of the following: saline only, systemic bacterial lipopolysaccharides (LPS) for 6 hours to induce endotoxemia and inflammatory responses, systemic gentamicin for 3 hours, or both treatments. After exsanguination, pooled cochleae (4/group) were processed for enzyme-linked immunosorbent assay (ELISA) for 16 cytokines. Gentamicin alone did not change cochlear cytokine levels, while LPS (±gentamicin) substantially elevated cochlear expression of several cytokines, particularly interleukin-1α, interleukin-6, monocyte chemotactic protein-1, macrophage inflammatory protein-1α, and RANTES. Since cytokines increase blood-brain barrier permeability, we hypothesize that cytokine-enhanced permeability of the blood-labyrinth barrier (BLB) could potentiate aminoglycoside-induced ototoxicity. This pilot study demonstrated the feasibility of detecting cytokine expression in murine cochleae using ELISA and facilitates future studies investigating BLB permeability in animal models of systemic inflammation.