Oxidative stress is thought to play a major role in the pathogenesis of PF (21, 22). Hyperlipidemia results in reduced protection against antioxidants and increased reactive oxygen species (ROS) levels (23); however, the potential role of hypercholesterolemia in the pathogenesis of PF has not been widely investigated. Many studies have demonstrated that elevated plasma lipid levels trigger the generation of ROS, which promotes the expansion of adipose tissue via hypertrophy and/or hyperplasia (21–23). These alterations activate the generation of adipokines, which leads to chroniclow-grade systemic inflammation (24). This phenomenon can cause injury to end organs, including the heart, kidneys, blood vessels, and especially the lungs (7, 25). Compared to other organs, the lungs are exposed to the highest levels of oxygen, which makes them highly vulnerable to oxidative stress (26). In general, the lungs have several antioxidant defense mechanisms to protect against the harmful eects of ROS (26). A reduction in these defenses contributes to oxidative stress, which may directly damage the lung or indirectly cause injury by reducing antiprotease activity and promoting the degradation of extracellular matrix (ECM) components (14, 22), leading to the progression of lung diseases, including PF (4, 27, 28). Moreover, high levels of circulating LDL-C directly alter lung cholesterol homeostasis, leading to alveolar type II cell injury and cholesterol overloading, which can