Interleukin-8 production in response to tumor necrosis factor-alpha by cholesteatoma keratinocytes in cell culture

Objectives/Hypothesis: Keratinocytes harvested from acquired cholesteatoma and grown in cell culture will demonstrate increased interleukin-8 (IL-8) production in response to tumor necrosis factor (TNF)-alpha as compared with a control keratinocyte cell line. Immunohistochemical studies have identified IL-8 and TNF-alpha, mediators of bony destruction, in tissue samples of cholesteatoma. TNF-alpha stimulates IL-8 production in healthy epidermal keratinocyte cell lines. It is not known whether TNF-alpha stimulates IL-8 production in cultured cholesteatoma keratinocytes. Study Design: Prospective controlled tissue culture experiment. Methods: Tissue from an acquired cholesteatoma was dissociated and grown in keratinocyte serum-free media for 8 weeks. Cholesteatoma keratinocytes and a control cell line of skin epidermal keratinocytes were treated with TNF-alpha. Conditioned media were harvested; production of IL-8 was measured by enzyme-linked immunosorbent assay, and cell counts were performed. Results: At a zero concentration of TNF-alpha, mean production of IL-8 by cholesteatoma keratinocytes was 39,809 pg/mL/24hr/1 Ã - 10⁶ cells versus 1,907 pg/mL/24hr/1 Ã - 10 ⁶ cells from skin epidermal keratinocytes, a statistically significant difference (P <.05). The cholesteatoma keratinocytes showed a 2.1-fold increase in response to 2 pg/mL of TNF-alpha and a 2.44-fold increase in response to 20 pg/mL of TNF-alpha. The skin epidermal keratinocyte cell line demonstrated a 1.07- and 1.13-fold increase to respective concentrations of TNF-alpha. Conclusions: Cholesteatoma keratinocytes appear to retain cell signaling characteristics in vitro that distinguish them from skin epidermal keratinocytes. This finding may indicate that cholesteatoma keratinocytes undergo a change in behavior in vivo that is preserved after the cells are removed from the inflammatory environment of the middle ear.