Decreased proteasomal function accelerates cigarette smoke-induced pulmonary emphysema in mice

Area of Science:

• Pulmonary Medicine
• Cellular Biology
• Aging Research

Background:

• Chronic obstructive pulmonary disease (COPD) involves lung destruction and inflammation, with oxidative stress-induced apoptosis implicated.
• The proteasome system maintains protein homeostasis but declines with age, potentially contributing to age-related diseases.
• The role of proteasome dysfunction in COPD pathogenesis remains largely unexplored.

Purpose of the Study:

• To investigate the role of impaired proteasomal function in the development of cigarette smoke-induced pulmonary emphysema.
• To examine the impact of decreased proteasomal activity on apoptosis in lung cells exposed to cigarette smoke.

Main Methods:

• Utilized a transgenic (Tg) mouse model with reduced proteasomal chymotrypsin-like activity.
• Exposed Tg and wild-type mice to cigarette smoke (CS) and assessed lung pathology.
• Investigated apoptosis and aggresome formation in cigarette smoke extract (CSE)-exposed mouse and human fibroblastic cells in vitro.

Main Results:

• CS-exposed Tg mice exhibited accelerated emphysema, characterized by significant airspace enlargement and inflammation.
• Apoptotic cells were prevalent in the lungs of affected Tg mice.
• Impaired proteasomal activity enhanced CSE-induced apoptosis in fibroblastic cells, with increased aggresome formation and nuclear translocation of apoptosis-inducing factor.

Conclusions:

• Decreased proteasomal function exacerbates CS-induced pulmonary emphysema.
• Coordinated effects of CS exposure and impaired proteasome activity enhance apoptotic cell death in alveolar walls.
• This mechanism may contribute to emphysema development and progression in susceptible populations, such as the elderly.