Molecular biological analysis for regenerated epithelial tissues on cutaneous wound healing process

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The skin function as a non-specific general defence line against infections and injury from the environment, and is an important region as an immune defense system composed of host cells such as keratinocytes, epidernal Langerhans cells, and T lymphocytes. In the present study, we examined various gene expressions in regenerated epithelial tissues in cutaneous wound healing model mice, and the response of human keratinocytes to v IL-6, IFN-y, and keratin 6 Mrna expressions in the regenerated epithelial tissues of mice were increased just after construction of cutaneous would and their expressions continued throughout the period of observation (21 days). Cutaneous would healing in mice administered with Escherichia coli LPS was delayed as compared with that of the control mice without LPS. Human keratinocyte cell line HaCaT expressed predominantly Mrna of TNFR and IFNGR, whereas Mrna of CD14, TLR2 and TLR4 were not detected. TNF-α upregulated IL-8 and MCP-1 Mrna expression in HaCaT cells, and IFN-y downregulated IL-8 Mrna expression and upregulated MCP-1 Mrna expression. On the other hand, these cytokine-related Mrna expressions were not seen in HaCaT cells after stimulation with E. coil LPS and Staphylococcus aureus peptidoglycan. IL-8 production in culture supematants of HaCaT cells stimulation with these test specimens was coincided with their IL-8 Mrna expression. HaCaT cell growth was delayed with treatment of TNF-α and IFN-y, but not of bacterial components. Thus HaCaT cells responded to endogenous factors such as TNF-α, and IFN-y, but not exogenous factors such as E. coli LPS and S. aureus peptidoglycan. These results suggest that human keratinocytes did not directly respond to bacterial cell components, however, the cells were activated by endogenous factors induced by host immune cells stimulated with pathogenic factors