Spiral ligament fibrocytes release chemokines in response to otitis media pathogens

Abstract

Protein array analysis showed that in response to NTHi or S. pneumoniae, rat SLFs released monocyte chemotactic protein 1, macrophage inflammatory protein 3 alpha, TNF-alpha, and cytokine-induced neutrophil chemoattractant 2 and 3. Treatment with IL-1alpha, on the other hand, resulted in release of MCP-1 but not the other molecules. Tissue inhibitor of metalloproteinase 1 and vascular endothelial growth factor were released regardless of the inflammatory stimulus used.

Toll-Like Receptor 2-Dependent NF-κB Activation Is Involved in Nontypeable Haemophilus influenzae -Induced Monocyte Chemotactic Protein 1 Up-Regulation in the Spiral Ligament Fibrocytes of the Inner Ear

“…Our preliminary data showed that mononuclear cells infiltrated in the spiral ligament of the human cochlea with labyrinthitis, combined with OM, which is consistent with our hypothesis (data not shown). We also previously reported that the SLF cell line up-regulates various chemokines and cytokines upon exposure to lysate of NTHI, a common OM pathogen (72). NTHI-treated group (Fig.…”

“…A solid-phase, sandwich-enzyme-linked immunosorbent assay (ELISA)-format, multiplexed protein assay was performed to simultaneously detect various cytokines released by activated cells (72). Briefly, the culture medium of SLFs was collected 48 h after treatment with either NTHI or PBS.…”

“…Also, SLF cell lines (96) showed an induction in monocyte chemotactic protein 1 (MCP-1) expression after treatment with lysate of nontypeable Haemophilus influenzae (NTHI), one of the most common OM pathogens (72). Moreover, it has previously been shown that monocytes can infiltrate cochlea exhibiting chronic middle ear inflammation or acoustic trauma (22,34,37).…”

“…The type of inner ear cells that respond to proinflammatory signals entering the inner ear remain unknown. Considering that SLFs are one of the abundant cell types in the cochlea and that they secrete cytokines and chemokines after proinflammatory stimuli (72,97), we hypothesized that the SLFs are major responders to such signals.…”

Aging of the auditory system

“…Cochlear inflammation is supposed to disrupt fibrocyte function of the spiral ligament; the stimulated fibrocytes produce chemoattractant mediators that induce prolonged inflammation and consequently lead to structural 366 T.N. ROTH changes, as mentioned above Moon et al, 2006). The reduced endocochlear potential not only affects the sensory part of the inner ear but also leads to alteration of the supporting structures, e.g., fibrocytes and connective tissue.…”