(A) With the increase of the RSV concentration, the expression of MFN2 increased, except for the 40 μM RSV group,there were no statistically significant differences in other RSV groups when compared with the control group (p>0.05). (B) The MFN2 mRNA level in the 5 μM RSV+CSE and 20 μM RSV+CSE groups was increased compared with that in the CSE group, and the 20 μM RSV+CSE group had a higher expression level than the 5 μM RSV+CSE group (p<0.05). However, the MFN2 mRNA level was not significantly affected by 1 μM RSV+CSE compared with that in the CSE group. (C) a; Control group; b: RSV group; c: CSE group; d: RSV+CSE group. Hoechst staining of HBE cells. HBE cells pretreated with RSV exhibited fewer apoptotic cells (d) than that of the non-RSV-treated group (c), following a 24 h exposure to 3.5% CSE. Apoptotic cells are strongly stained bright turquoise. (D) CCK-8 assay. The RSV+CSE group has a higher cell viability than CSE group. *: p<0.05, #: p>0.05.