Abstract
Foam cell formation as a result of imbalance of modified cholesterol influx and efflux by macrophages is a key to the occurrence and development of atherosclerosis. Oxidative stress is thought to be involved in the pathogenesis of atherosclerosis. SS-31 is a member of the Szeto-Schiller (SS) peptides shown to specifically target the inner mitochondrial membrane to scavenge reactive oxygen species. In this study, we investigated whether SS-31 may provide protective effect on macrophage from foam cell formation in RAW264.7 cells. The results showed that SS-31 inhibited oxidized low-density lipoproteins (ox-LDL)-induced foam cell formation and cholesterol accumulation, demonstrated by intracellular oil red O staining and measurement of cholesterol content. The mechanism was revealed that SS-31 did not only significantly attenuated ox-LDL-induced generation of reactive oxygen species (ROS) and increased the activities of superoxide dismutases, but also dose-dependently inhibited the expression of CD36 and LOX-1, two scavenger receptors of ox-LDL, while the expression of ATP-binding cassette A1 and G1, playing a pivotal role in cholesterol efflux, was not affected. As a result, SS-31 decreased pro-inflammatory cytokines such as interleukin 6 and tumor necrosis factor alpha, suggesting the prevention of inflammatory responses. In conclusion, our results demonstrate that SS-31 provides a beneficial effect on macrophages from foam cell formation, likely, through both ROS scavenging and inhibition of cholesterol influx. Therefore, SS-31 may potentially be of therapeutic relevance in prevention of human atherogenesis.
Highlights
Atherosclerosis, which is a leading cause of death in western societies, has become a worldwide epidemic affecting most developing and developed countries
Atherosclerotic lesion occurrence is determined by foam cell formation, which is associated with increased cholesterol in macrophages [6]
We first assessed the effect of SS-31 on foam cell formation in oxidized low-density lipoproteins (ox-LDL)-elicited RAW264.7 macrophages
Summary
Atherosclerosis, which is a leading cause of death in western societies, has become a worldwide epidemic affecting most developing and developed countries. Recent studies have established a basic role for inflammation in mediating the development of this disease from initiation through progression and, the thrombotic complexity of atherosclerosis [13,14,15] These new evidences favor the important links between risk factors and mechanisms of atherogenesis. SS-31 interacts with mitochondrial cardiolipin [17], improves ATP production, reduces mitochondrial ROS production, and decreases oxidative damage [18] These effects are associated with protection against ischemia-reperfusion injury [18], amyloid-β toxicity in Alzheimer’s disease neurons [19], cardiac hypertrophy and failure [20], and MPTP-induced dopaminergic neuron cell death, a model of Parkinson’s disease [21] in animal models. We report that treatment with SS-31 significantly inhibits ox-LDL-induced foam cell formation and reduces oxidative stress and inflammation in RAW264.7 cells
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