Oxidized low-density lipoprotein induced hepatoma-derived growth factor upregulation mediates foam cell formation of cultured rat aortic vascular smooth muscle cells

Study on the mechanism of Huangqi Chifeng decoction regulating ferroptosis inhibiting smooth muscle cells derived foam cell formation

ETHNOPHARMACOLOGICAL RELEVANCE

Chinese medicine, specifically Huangqi Chifeng Decoction (HQCF), is recognized for its efficacy in treating atherosclerosis (AS), a common cardiovascular disease. Despite its established benefits in addressing Qi deficiency, blood stasis, and collateral obstruction, the precise mechanism through which HQCF affects AS remains unclear.

AIM OF THE STUDY

This study investigated the potential of HQCF to mitigate AS by suppressing smooth muscle cell (SMC) foam formation through the ferroptosis pathway.

MATERIALS AND METHODS

An AS model was established using ApoE-/- mice fed a high-fat diet (HFD), and the role of HQCF in regulating ferroptosis in AS was examined. Using a single-cell proteomics analysis strategy, we identified the primary targets of HQCF in SMCs. Additionally, an oxidized low-density lipoprotein (ox-LDL)-treated SMC-derived foam cell model was established. The effects HQCF on SMC ferroptosis were analyzed, and ox-LDL-induced SMCs were pretreated with small interfering RNA (siRNA) and overexpressing carrier plasmids (pcDNA) to identify potential therapeutic targets, for specifically thioredoxin (TXN).

RESULTS

HQCF the pathological state of the aorta in ApoE-/- mice, regulated lipid levels, improved antioxidant capacity, modulated the phenotypic transformation of SMCs, and maintained the dynamic balance of extracellular matrix degradation and remodeling. Additionally, HQCF may inhibit ferroptosis via positive regulation of the GPX4/xCT signaling pathway. Single-cell proteomics revealed 36 common differentially expressed proteins (DEPs), suggesting that HQCF's treatment of AS may be associated with the regulation of cellular function and redox homeostasis. The abnormal expression of TXN in SMCs may be related to the phenotypic transition induced by AS. HQCF was also found to ameliorate oxidative stress and mitochondrial dysfunction during SMC foaming. Moreover, ferroptosis was involved in ox-LDL-induced foam cell formation, and HQCF alleviated these pathologies by inhibiting ferroptosis. The protective effect of HQCF on SMCs was enhanced by TXN overexpression but partially reversed by TXN knockdown, further indicating that HQCF's regulation of SMC function and inhibition of ferroptosis is, at least in part, mediated by TXN.

CONCLUSION

These findings suggest that HQCF protects SMCs from ferroptosis by regulating the TXN/xCT/GPX4 pathway, ameliorating the aortic pathological state, alleviating oxidative stress, and maintaining mitochondrial homeostasis in mice.

Myogenic Anti-Nucleolin Aptamer iSN04 Inhibits Proliferation and Promotes Differentiation of Vascular Smooth Muscle Cells

De-differentiation and subsequent increased proliferation and inflammation of vascular smooth muscle cells (VSMCs) is one of the mechanisms of atherogenesis. Maintaining VSMCs in a contractile differentiated state is therefore a promising therapeutic strategy for atherosclerosis. We have reported the 18-base myogenetic oligodeoxynucleotide, iSN04, which serves as an anti-nucleolin aptamer and promotes skeletal and myocardial differentiation. The present study investigated the effect of iSN04 on VSMCs because nucleolin has been reported to contribute to VSMC de-differentiation under pathophysiological conditions. Nucleolin is localized in the nucleoplasm and nucleoli of both rat and human VSMCs. iSN04 without a carrier was spontaneously incorporated into VSMCs, indicating that iSN04 would serve as an anti-nucleolin aptamer. iSN04 treatment decreased the ratio of 5-ethynyl-2'-deoxyuridine (EdU)-positive proliferating VSMCs and increased the expression of α-smooth muscle actin, a contractile marker of VSMCs. iSN04 also suppressed angiogenesis of mouse aortic rings ex vivo, which is a model of pathological angiogenesis involved in plaque formation, growth, and rupture. These results demonstrate that antagonizing nucleolin with iSN04 preserves VSMC differentiation, providing a nucleic acid drug candidate for the treatment of vascular disease.

TM6SF2 reduces lipid accumulation in vascular smooth muscle cells by inhibiting LOX-1 and CD36 expression

TM6SF2, predominantly expressed in the liver and intestine, is closely associated with lipid metabolism. We have demonstrated the presence of TM6SF2 in VSMCs within human atherosclerotic plaques. Subsequent functional studies were conducted to investigate its role in lipid uptake and accumulation in human vascular smooth muscle cells (HAVSMCs) using siRNA knockdown and overexpression techniques. Our results showed that TM6SF2 reduced lipid accumulation in oxLDL-stimulated VSMCs, likely through the regulation of lectin-like oxLDL receptor 1 (LOX-1) and scavenger receptor cluster of differentiation 36 (CD36) expression. We concluded that TM6SF2 plays a role in HAVSMC lipid metabolism with opposing effects on cellular lipid droplet content by downregulation of LOX-1 and CD36 expression.