Atherosclerosis is a key etiological event in the development of cardiovascular diseases (CVDs), strongly linked to the formation of foam cells. This study explored the effects of two blue mussel-derived bioactive peptides (BAPs), PIISVYWK (P1) and FSVVPSPK (P2), on inhibiting foam cell formation and mitigating inflammation in oxLDL-treated RAW264.7 macrophages. Both peptides significantly suppressed intracellular lipid accumulation and cholesterol levels while promoting cholesterol efflux by downregulating cluster of differentiation 36 (CD36) and class A1 scavenger receptors (SR-A1) and upregulating ATP binding cassette subfamily A member 1 (ABCA-1) and ATP binding cassette subfamily G member 1 (ABCG-1) expressions. The increased expression of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α) further validated their role in enhancing cholesterol efflux. Additionally, P1 and P2 inhibited foam cell formation in oxLDL-treated human aortic smooth muscle cells and exerted anti-inflammatory effects by reducing pro-inflammatory cytokines, nitric oxide (NO), prostaglandin E₂ (PGE₂), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), primarily through inhibiting NF-κB activation. Furthermore, P1 and P2 alleviated oxidative stress by activating the Nrf2/HO-1 pathway. Our findings demonstrate that P1 and P2 have significant potential in reducing foam cell formation and inflammation, both critical factors in atherosclerosis development. These peptides may serve as promising therapeutic agents for the prevention and treatment of CVDs associated with oxidative stress and inflammation.

Inhibitory effect of ark shell (Scapharca subcrenata (Lischke, 1869)) proteolytic hydrolysates (ASHs) on oxidized low-density lipoprotein (oxLDL)-induced macrophage foam cell formation was investigated. Two types of ASHs were prepared by Alcalase® and pepsin, ASAH (ark shell-Alcalase® hydrolysates), and ASPH (ark shell-pepsin hydrolysate). Oil Red O staining results showed that ASPH suppressed foam cell formation and lipid accumulation more than ASAH in oxLDL-induced foam cell formation of RAW264.7 macrophages. ASPH reduced the levels of total cholesterol, cholesterol ester, and free cholesterol in oxLDL-treated RAW264.7 macrophages. It was found that ASPH increased cholesterol efflux and decreased cholesterol influx rate. In this regard, protein expressions of CD36 and scavenger receptor class A1 (SR-A1) for cholesterol influx and ATP-binding cassette transporter A1 and G1 (ABCA1 and ABCG1) for cholesterol efflux were investigated. ASPH treatment resulted in an increase of ABCA1 and ABCG1 expression but downregulated CD36 and SR-A1 expression. Furthermore, ASPH suppressed production of proinflammatory cytokines, including tumor necrosis factor-α and interleukin-6 and -1β, through regulating nuclear factor-kappa B (NF-κB) in oxLDL-induced foam cell formation of RAW264.7 macrophages. Taken together, our data indicate that ASPH might be a useful ingredient in functional foods for ameliorating atherosclerosis by preventing foam cell formation.

Atherosclerosis, a leading contributor to cardiovascular diseases (CVDs), is characterized by foam cell formation driven by excessive lipid accumulation in macrophages and vascular smooth muscle cells. This study elucidates the anti-atherosclerotic potential of AWLNH (P3) and PHDL (P4) peptides by assessing their effects on foam cell formation, lipid metabolism, and oxidative stress regulation. P3 and P4 effectively suppressed intracellular lipid accumulation in RAW264.7 macrophages and human aortic smooth muscle cells (hASMCs), thereby mitigating foam cell formation. Mechanistically, both peptides modulated cholesterol homeostasis by downregulating cholesterol influx mediators, cluster of differentiation 36 (CD36), and class A1 scavenger receptor (SR-A1), while upregulating cholesterol efflux transporters ATP-binding cassette subfamily A member 1 (ABCA1) and ATP-binding cassette subfamily G member 1 (ABCG1). The activation of peroxisome proliferator-activated receptor-gamma (PPAR-γ) and liver X receptor-alpha (LXR-α) further substantiated their role in promoting cholesterol efflux and restoring lipid homeostasis. Additionally, P3 and P4 peptides exhibited potent antioxidative properties by attenuating reactive oxygen species (ROS) generation through activation of the HO-1/Nrf2 signaling axis. HO-1 silencing via siRNA transfection abolished these effects, confirming HO-1-dependent regulation of oxidative stress and lipid metabolism. Collectively, these findings highlight P3 and P4 peptides as promising therapeutic agents for atherosclerosis by concurrently targeting foam cell formation, cholesterol dysregulation, and oxidative stress, warranting further exploration for potential clinical applications.