Interleukin-10 down-regulates cathepsin B expression in fetal rat alveolar type II cells exposed to hyperoxia.
OBJECTIVE
Hyperoxia has the chief biological effect of cell death. We have previously reported that cathepsin B (CB) is related to fetal alveolar type II cell (FATIIC) death and pretreatment of recombinant IL-10 (rIL-10) attenuates type II cell death during 65%-hyperoixa. In this study, we investigated what kinds of changes of CB expression are induced in FATIICs at different concentrations of hyperoxia (65%- and 85%-hyperoxia) and whether pretreatment with rIL-10 reduces the expression of CB in FATIICs during hyperoxia.


METHODS
Isolated embryonic day 19 fetal rat alveolar type II cells were cultured and exposed to 65%- and 85%-hyperoxia for 12 h and 24 h. Cells in room air were used as controls. Cytotoxicity was assessed by lactate dehydrogenase (LDH) released into the supernatant. Expression of CB was analyzed by fluorescence-based assay upon cell lysis and western blotting, and LDH-release was re-analyzed after preincubation of cathepsin B-inhibitor (CBI). IL-10 production was analyzed by ELISA, and LDH-release was re-assessed after preincubation with rIL-10 and CB expression was re-analyzed by western blotting and real-time PCR.


RESULTS
LDH-release and CB expression in FATIICs were enhanced significantly in an oxygen-concentration-dependent manner during hyperoxia, whereas caspase-3 was not activated. Preincubation of FATIICs with CBI significantly reduced LDH-release during hyperoxia. IL-10-release decreased in an oxygen-concentration-dependent fashion, and preincubation of the cells with rIL-10 significantly reduced cellular necrosis and expression of CB in FATIICs which were exposed to 65%- and 85%-hyperoxia.


CONCLUSIONS
Our study suggests that CB is enhanced in an oxygen- concentration-dependent manner, and IL-10 has an inhibitory effect on CB expression in FATIICs during hyperoxia.
Department of Pediatrics, Kangwon National University Hospital, Kangwon National University School of Medicine, 156 Baengnyeong-ro, Chuncheon 200-722, Korea. premee@kangwon.ac.kr
Hyeon-Soo
HS
Lee
Chun-Ki
CK
Kim
D000818:Animals; D002401:Cathepsin B / Q000235:genetics* / Q000378:metabolism; D015536:Down-Regulation; D005786:Gene Expression Regulation; D018496:Hyperoxia / Q000235:genetics*; D016753:Interleukin-10 / Q000494:pharmacology* / Q000502:physiology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D009336:Necrosis / Q000139:chemically induced; D010100:Oxygen / Q000378:metabolism; D051381:Rats
D016753:Interleukin-10; D007770:L-Lactate Dehydrogenase; D002401:Cathepsin B; C533916:Ctsb protein, rat; D010100:Oxygen