Expression of adhesion molecules by cultured spiral ligament fibrocytes stimulated with proinflammatory cytokines.
Secondary cultures from murine spiral ligament (SL) fibrocytes were stimulated with proinflammatory cytokines interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha), and expression of various adhesion molecules was investigated. Cultures without cytokine stimulation did not show positive immunostaining for vascular cell adhesion molecule-1 (VCAM-1), intercellular adhesion molecule-1 (ICAM-1), or mucosal addressin cell adhesion molecule-1 (MAdCAM-1). Although staining was also negative after stimulation with IL-1beta, VCAM-1 and ICAM-1 staining was observed after the cells were stimulated with TNF-alpha. Reverse transcription-polymerase chain reaction analysis showed messenger RNAs for both VCAM-1 and ICAM-1 expression to be present after fibrocytes were stimulated with TNF-alpha. These data suggest that activated fibrocytes may cause inflammatory cells to persist in the SL. Given that SL fibrocytes may play a role in homeostasis of cochlear fluid and ion concentrations, prolongation of the inflammatory response could lead to fibrocyte damage that might ultimately result in cochlear malfunction.