Effect of endotoxin on keratin production of keratinocytes in vitro.

The rate of keratin protein accumulation appears to be a crucial factor in the pathogenesis of middle ear cholesteatoma. The effect of endotoxin on keratin production of keratinocytes was studied. Endotoxins are lipopolysaccharides contained within the cell wall of gram-negative bacteria. Various concentrations of endotoxin were added to keratinocytes derived from newborn rats. Syntheses of keratin proteins were studied by incorporation of 3H-leucine into each protein fraction. Extraction of keratin proteins with various salt solutions showed that endotoxin stimulated keratinocytes to produce keratohyalin granules and its related proteins as well as proteins in the stratum corneum (keratin proteins). These findings suggest that accumulation of keratin debris in cholesteatoma may result from the effect of infection in the epithelial cells.