Effects of Heat Shock Protein 70 (HSP70) Induction after Lipopoly?saccharide Exposure on the IL-6 Production and the Cell Viability after Subsequent Lipopolysaccharide Challenge in Murine Alveolar Epithelial Cells / 결핵및호흡기질환

ABSTRACT

BACKGROUND AND AIMS: Pre-induction of heat shock protein 70 (HSP70) is known to effectively attenuate the lipopolysaccharide (LPS)-induced inflammatory response in lung tissue. However, it is unclear if HSP70 induction after LPS exposure attenuates the subsequent LPS-induced inflammatory response in alveolar epithelial cells. This study examined the effects of HSP70 induction after LPS exposure on the IL-6 production and the cell viability after a subsequent LPS challenge in murine alveolar epithelial cells, and investigated whether or not HSP70 itself may be involved in those effects. METHODS: Murine alveolar epithelial cells were cultured and divided into two groups; the Non-Pre-LPS group without a LPS pre-treatment and the Pre-LPS group with a LPS pre-treatment. Each group was subdivided into the following four subgroups subgroup C (control), subgroup Q (quercetin), subgroup HSP70 (HSP70 induction), and subgroup HSP70-Inh (HSP70 inhibition). HSP70 expression, which was induced by sodium arsenite and inhibited by quercetin, was analyzed by western blot analysis. The IL-6 levels in the culture supernatant were measured by ELISA, and the cell viability was measured using a simplified MTT assay. RESULTS: The IL-6 levels were lower in subgroup HSP70 than in subgroup C (p<0.01), and were higher in subgroup HSP70-Inh than in subgroup HSP70 in both the Non-Pre-LPS and Pre-LPS groups (p<0.05, p<0.01). The cell viability tended to decrease in the Pre-LPS group compared with the Non-Pre-LPS group. While the cell viability was higher in subgroups Q, HSP70, and HSP70-Inh than in subgroup C in the Non-Pre-LPS group (p<0.05, p<0.05, p<0.01), there was no difference in cell viability among the subgroups in the Pre-LPS group. CONCLUSION: HSP70 induction after a LPS pre-treatment in murine alveolar epithelial cells inhibits the subsequent LPS-induced IL-6 production without affecting the cell viability, and HSP70 by itself may play an important role in this proccess.