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Effect of endotoxin on cultured rat middle ear epithelium, rat meatal epidermis, and human keratinocytes
S C Hesseling1, C A van Blitterswijk, D J Lim
1Laboratory for Otobiology and Biocompatibility, Leiden University Hospital, The Netherlands.
Abstract:
Several factors seem to contribute to the series of events in the pathogenesis of otitis media and cholesteatoma. Endotoxin is likely to be one of these factors, since it has been found in human middle ear effusions and since injection of this substance into the middle ear, in animal experiments, gave rise to prominent reactions. Provoking of epithelial cells in vitro with endotoxin led to distinct cell responses that might be associated with cholesteatoma formation. In this study the effect of endotoxin on serially cultured rat middle ear epithelium, rat meatal epidermis, and human keratinocytes was investigated. Endotoxin strongly stimulated the proliferation of middle ear epithelium and human keratinocytes and inhibited that of meatal epidermis. Furthermore, endotoxin affected the morphology of the three types of tissue. Rat middle ear epithelium revealed epithelial cell tracks with interconnecting bridge-like structures protruding above the culture plane, whereas rat meatal epidermis showed increased terminal differentiation expressing large areas of blister-like structures detaching from the culture dish. Cross-linked envelope analysis of human keratinocytes showed an increased terminal differentiation that was morphologically confirmed but was not confirmed by cytokeratin analysis. The results of this study support the hypothesis that endotoxin may play an important role in the pathogenesis of otitis media and cholesteatoma.
Insights
Endotoxin exposure significantly impacts middle ear and skin cells, potentially driving otitis media and cholesteatoma development. This study reveals endotoxin
Area of Science:
- Otolaryngology
- Cell Biology
- Pathogenesis Research
Background:
- Otitis media and cholesteatoma pathogenesis involve multiple factors.
- Endotoxin is implicated due to its presence in middle ear effusions and experimental induction of reactions.
Purpose of the Study:
- To investigate the effect of endotoxin on cultured middle ear epithelium, meatal epidermis, and keratinocytes.
- To explore endotoxin's role in the cellular events leading to otitis media and cholesteatoma.
Main Methods:
- Serial culturing of rat middle ear epithelium and meatal epidermis.
- Culture of human keratinocytes.
- Exposure of these cell types to endotoxin and analysis of proliferation and morphology.
Main Results:
- Endotoxin strongly stimulated proliferation in rat middle ear epithelium and human keratinocytes.
- Endotoxin inhibited proliferation in rat meatal epidermis.
- Distinct morphological changes were observed, including altered cell structures and increased terminal differentiation in specific tissues.
Conclusions:
- Endotoxin significantly influences the behavior of middle ear and epidermal keratinocytes.
- Findings support the hypothesis that endotoxin is a key factor in the pathogenesis of otitis media and cholesteatoma.