Effect of lipoteichoic acid on proliferation and differentiation of keratinocytes.

Bacterial infection is always found to be associated with cholesteatoma. Accumulation of keratin debris is one of the crucial factors for the growth of cholesteatoma. The effects of lipoteichoic acid, a cell wall component of gram-positive bacteria, on the proliferation and differentiation of keratinocytes were studied. Various concentrations of lipoteichoic acid (0 to 100 micrograms/ml) were added to keratinocytes. DNA synthesis and protein synthesis were inhibited by decreasing the incorporation of 3H-thymidine and 3H-leucine into keratinocytes. The effects of lipoteichoic acid on terminal differentiation were then studied by measuring the number of sodium dodecyl sulfate-insoluble cornified cell envelopes and the transglutaminase activity (a marker of terminal differentiation) determined by incorporation of 3H-putrescine into cornified envelopes. These studies showed that lipoteichoic acid stimulated the formation of cornified cell envelopes and transglutaminase activity. These findings suggest that lipoteichoic acid stimulated the terminal differentiation and accumulation of keratin debris and that lipoteichoic acid might have stimulatory effects on the development of cholesteatoma.