Korean J Intern Med.  2023 Nov;38(6):934-944. 10.3904/kjim.2023.090.

Effects of aging on accompanying intermittent hypoxia in a bleomycin-induced pulmonary fibrosis mouse model

• Lee H
• Kim IK
• Im J
• Jin BS
• Kim HH
• Kim SW
• Yeo CD
• Lee SH

• KMID: 2547651
• DOI: http://doi.org/10.3904/kjim.2023.090

Abstract

Background/Aims
Obstructive sleep apnea (OSA) is prevalent in older patients with idiopathic pulmonary fibrosis (IPF); however, it is underrecognized. OSA is characterized by intermittent hypoxia (IH) and sleep fragmentation. In this study, we evaluated the effects of IH in an older mouse model of bleomycin-induced lung fibrosis.
Methods
Bleomycin-induced mice (C57BL/6, female) were randomly divided into four groups of young vs. old and room air (RA)-exposed vs. IH-exposed. Mice were exposed to RA or IH (20 cycles/h, FiO2 nadir 7 ± 0.5%, 8 h/day) for four weeks. The mice were sacrificed on day 28, and blood, bronchoalveolar lavage (BAL) fluid, and lung tissue samples were obtained.
Results
The bleomycin-induced IH-exposed (EBI) older group showed more severe inflammation, fibrosis, and oxidative stress than the other groups. The levels of inflammatory cytokines in the serum and BAL fluid increased in the EBI group. Hydroxyproline levels in the lung tissue increased markedly in the EBI group.
Conclusions
This study demonstrates the possible harmful impact of OSA in an elderly mouse model of lung fibrosis. This study further suggests that older patients with IPF and OSA may be more of a concern than younger patients with IPF. Further research is required in this area.

Keyword

Elderly; Fibrosis; Hypoxia; Inflammation; Mice; Model