BACKGROUND: Exosome-miR-146a is significantly increased in patients with Atherosclerosis (AS), but its mechanism and effect on AS have not been fully elucidated.
OBJECTIVE: To explore the change rule and mechanism of exosomes release, and the role and molecular mechanism of exosome-miR-146a in AS.
METHODS: We isolated and identified exosomes from THP-1 macrophages after treating them with ox-LDL. Then used co-immunoprecipitation and silver staining to identify the proteins involved in regulating exosome release. PKH67 was used to label exosomes to confirm that cells can absorb them, and then co-culture with HVSMCs for cell proliferation and migration detection. The target genes of miR-146a were screened and identified through bioinformatics and luciferase activity assay, and the expression of miR-146a and related proteins was detected through qRT-PCR and Western blot in HUVECs. An AS model in LDLR-/- mice induced by a high-fat diet was developed to investigate the impact of exosome-miR-146a on AS.
RESULTS: The results showed that experimental foam cells from AS showed higher expression of miR-146a. It was observed that NMMHC IIA and HSP70 interacted to regulate the release of exosomes. And HUVECs can absorb exosomes derived from macrophages. In addition, we also found that miR-146a directly targeted the SMAD4 gene to modulate the p38 MAPK signaling pathway, thereby mediating HUVECs damage. Furthermore, exosome-miR-146a induced abnormal proliferation and migration of HVSMCs. The expression of miR-146a was significantly reduced in miR-146a-mimics mice and increased in miR-146a inhibitor mice whereas the inhibition of miR-146a effectively reduced while increasing miR-146a worsened AS in mice.
CONCLUSIONS: Our findings expressed the potential of miR-146a as a favorable therapeutic target for AS, however, further exploration is suggestive for deep understanding of the mechanisms regulating exosome-miR-146a release in vivo and to develop effective therapeutic strategies involving miR-146a.

Atherosclerotic plaque formation is largely attributed to the impaired efferocytosis, which is known to be associated with the pathologic upregulation of cluster of differentiation 47 (CD47), a key antiphagocytic molecule. By gene expression omnibus (GEO) datasets analysis, we identified that four miRNAs are aberrantly downregulated in atherosclerosis, coronary artery disease, and obesity. Of them, hsa-miR-299-3p (miR-299-3p) was predicted to target the 3\'UTR of human CD47 mRNA by bioinformatics analysis. Further, we demonstrated that miR-299-3p negatively regulates CD47 expression by binding to the target sequence \"CCCACAU\" in the 3\'UTR of CD47 mRNA through luciferase reporter assay and site-directed mutagenesis. Additionally, we found that miR-299-3p was downregulated by ~32% in foam cells in response to oxidized low-density lipoprotein (ox-LDL) stimulation, thus upregulating CD47 and contributing to the impaired efferocytosis. Whereas, restoration of miR-299-3p reversed the ox-LDL-induced upregulation of CD47, thereby facilitating efferocytosis. In high-fat diet (HFD) fed ApoE-/- mice, we discovered that miR-299-3p was downregulated thus leading to upregulation of CD47 in abdominal aorta. Conversely, miR-299-3p restoration potently suppressed HFD-induced upregulation of CD47 and promoted phagocytosis of foam cells by macrophages in atherosclerotic plaques, thereby reducing necrotic core, increasing plaque stability, and mitigating atherosclerosis. Conclusively, we identify miR-299-3p as a negative regulator of CD47, and reveal a molecular mechanism whereby the ox-LDL-induced downregulation of miR-299-3p leads to the upregulation of CD47 in foam cells thus contributing to the impaired efferocytosis in atherosclerosis, and propose miR-299-3p can potentially serve as an inhibitor of CD47 to promote efferocytosis and ameliorate atherosclerosis.

The rising incidences of atherosclerosis have necessitated efforts to identify novel targets for therapeutic interventions. In the present study, we observed increased expression of the mechanosensitive calcium channel Piezo1 transcript in mouse and human atherosclerotic plaques, correlating with infiltration of PIEZO1-expressing macrophages. In vitro administration of Yoda1, a specific agonist for PIEZO1, led to increased foam cell apoptosis and enhanced phagocytosis by macrophages. Mechanistically, PIEZO1 activation resulted in intracellular F-actin rearrangement, elevated mitochondrial ROS levels and induction of mitochondrial fragmentation upon PIEZO1 activation, as well as increased expression of anti-inflammatory genes. In vivo, ApoE-/- mice treated with Yoda1 exhibited regression of atherosclerosis, enhanced stability of advanced lesions, reduced plaque size and necrotic core, increased collagen content, and reduced expression levels of inflammatory markers. Our findings propose PIEZO1 as a novel and potential therapeutic target in atherosclerosis.

The formation of macrophage-derived foam cells has been recognized as the pathological hallmark of atherosclerotic diseases. However, the pathological evolution dynamics and underlying regulatory mechanisms remain largely unknown. Herein, we introduce a single-particle rotational microrheology method for pathological staging of macrophage foaming and antiatherosclerotic explorations by probing the dynamic changes of lysosomal viscous feature over the pathological evolution progression. The principle of this method involves continuous monitoring of out-of-plane rotation-caused scattering brightness fluctuations of the gold nanorod (AuNR) probe-based microrheometer and subsequent determination of rotational relaxation time to analyze the viscous feature in macrophage lysosomes. With this method, we demonstrated the lysosomal viscous feature as a robust pathological reporter and uncovered three distinct pathological stages underlying the evolution dynamics, which are highly correlated with a pathological stage-dependent activation of the NLRP3 inflammasome-involved positive feedback loop. We also validated the potential of this positive feedback loop as a promising therapeutic target and revealed the time window-dependent efficacy of NLRP3 inflammasome-targeted drugs against atherosclerotic diseases. To our knowledge, the pathological staging of macrophage foaming and the pathological stage-dependent activation of the NLRP3 inflammasome-involved positive feedback mechanism have not yet been reported. These findings provide insights into in-depth understanding of evolutionary features and regulatory mechanisms of macrophage foaming, which can benefit the analysis of effective therapeutical drugs as well as the time window of drug treatment against atherosclerotic diseases in preclinical studies.

BACKGROUND: Atherosclerosis is a long-lasting inflammatory condition affecting the walls of arteries, marked by the buildup of fats, plaque formation, and vascular remodeling. Recent findings highlight the significance of cholesterol removal pathways in influencing atherosclerosis, yet the connection between cholesterol removal and regulation of macrophage inflammation remains poorly understood. RBAP could serve as an anti-inflammatory agent; however, its role in atherosclerosis and the mechanism behind it are still not well understood.
OBJECTIVE: The objective of this research is to explore how RBAP impacts cholesterol efflux, which is a considerable element in the advancement of atherosclerosis.
METHODS: An atherosclerosis mouse model was established by using an ApoE KO strain mouse on a high-fat diet (HFD) to assess the effects of RBAP, conducted either orally or through injection. Additionally, in vitro experiments were conducted where the induction of THP-1 cells was conducted for the differentiation towards macrophages, and along with mouse RAW264.7 cells, were challenged with ox-LDL to evaluate the impact of RBAP.
RESULTS: In this study, RBAP was found to reduce the production and downregulate TNF-α, IL-1β, and IL-6 levels and inhibited the activation of the TLR4/MyD88/NF-κB signaling in atherosclerosis model mice, as well as in ox-LDL-challenged THP-1 cells and mouse RAW264.7 macrophages. RBAP\'s effectiveness also improved the enhancement of reverse cholesterol transport (RCT) and cholesterol removal to HDL and apoA1 by increasing the activity of genes related to cholesterol removal PPARγ/LXRα/ABCA1/ABCG1, both in ApoE-/- mice and in THP-1 cells and mouse RAW264.7 macrophages. Notably, RBAP exerted similar effects on atherosclerosis model mice and macrophages to those of TAK-242, an inhibitor of the TLR4 signaling. When RBAP and TAK-242 were applied simultaneously, the improvement was not enhanced compared with either RBAP or TAK-242 treatment alone.
CONCLUSIONS: These findings suggest that RBAP, as a TLR4 inhibitor, has anti-atherosclerotic effects by improving inflammation and promoting cholesterol effection, indicating its therapeutic potential in intervening atherosclerosis.

Macrophage lipid accumulation indicates a pathological change in atherosclerosis. Ilexgenin A (IA), a pentacyclic triterpenoid compound, plays a role in preventing inflammation, bacterial infection, and fatty liver and induces a potential anti-atherogenic effect. However, the anti-atherosclerotic mechanism remains unclear. The present study investigated the effects of IA on lipid accumulation in macrophage-derived foam cells and atherogenesis in apoE-/- mice. Our results indicated that the expression of adenosine triphosphate-binding cassette transporter A1 (ABCA1) was up-regulated by IA, promoting cholesterol efflux and reducing lipid accumulation in macrophages, which may be regulated by the protein tyrosine phosphatase non-receptor type 2 (PTPN2)/ERK1/2 signalling pathway. IA attenuated the progression of atherosclerosis in high-fat diet-fed apoE-/- mice. PTPN2 knockdown with siRNA or treatment with an ERK1/2 agonist (Ro 67-7476) impeded the effects of IA on ABCA1 upregulation and cholesterol efflux in macrophages. These results suggest that IA inhibits macrophage lipid accumulation and alleviates atherosclerosis progression via the PTPN2/ERK1/2 signalling pathway.

This study was to investigate the therapeutic effect of Bacillus amyloliquefaciens (Ba) on atherosclerosis (AS). THP-1 monocyte was differentiated to THP-1 macrophage (THP-M) through phorbol 12-myristate 13-acetate. After pre-treatment by 108 cfu/ml Ba lasting 6 h, THP-M was induced with 100 mg/l ox-LDL lasting 48 h to form macrophage foam cell (THP-F). RT-qPCR and flow cytometry were employed to determine the polarization of THP-M and THP-F. ApoE-/- mice with high-fat and high-cholesterol diet were used for constructing an AS model to evaluate the effect of Ba on AS. Our in vitro results showed that Ba vegetative cells pre-treatment distinctly inhibited the levels of iNOS and CD16/CD32 (M1 macrophage markers), and increased the levels of FIZZ1, Ym1, Arg1, CD163, and CD206 (M2 macrophage markers), indicating that Ba pre-treatment promoted anti-inflammatory M2-like polarization both in THP-M and THP-F. Meanwhile, it also suppressed cholesterol uptake, esterification, and hydrolysis, and efflux by THP-M and THP-F. Additionally, our animal experiments demonstrated that Ba vegetative cells treatment suppressed high cholesterol, hyperglycemia, hyperlipidemia, and the release of inflammatory factors (TNF-α, IL-6 and IL-1β) in ApoE-/- AS mice. In a word, our results indicated that Ba may protect against AS through alleviating foam cell formation and macrophage polarization through targeting certain stages of AS.

Atherosclerosis (AS) is the main pathological basis of cardiovascular diseases such as coronary heart disease. Black phosphorus quantum dots (BPQDs) are a novel nanomaterial with good optical properties and biocompatibility, which was applied in the treatment of AS in mice, with good results shown in our previous study. In this study, BPQDs were injected into high-fat diet-fed apolipoprotein E knockout mice as a preventive drug for 12 weeks. Simvastatin, a classic preventive drug for AS, was used as a control to verify the preventive effect of BPQDs. The results showed that after preventive treatment with BPQDs, the plaque area in mice was significantly reduced, the vascular elasticity was increased, and serum lipid levels were significantly lower than those in the model group. To explore the mechanism, macrophages were induced to become foam cells using oxidized low-density lipoprotein. We found that BPQDs treatment could increase cell autophagy, thereby regulating intracellular lipid metabolism. Taken together, these data revealed that BPQDs may serve as a functional drug in preventing the development of AS.

While the cardiovascular system is a primary target of organophosphorus flame retardants (OPFRs), particularly aryl-OPFRs, it is still exclusive whether the diisodecyl phenyl phosphate (DIDPP), widely used and broadly present in the environment at high concentrations, elicits atherosclerosis effects. Liver X receptors (LXRs) play a direct role in regulating the formation of atherosclerotic lesions. This study was the first to demonstrate that DIDPP acts as an LXRα ligand and functions as an LXRα antagonist with a half-maximal inhibitory concentration of 16.2 μM. We showed that treatment of an in vitro macrophage model with 1 to 10 μM of DIDPP resulted in the downregulation of direct targets of LXRα, namely ABCA1, ABCG1 and SR-B1, thereby leading to a 7.9-13.2 % reduction in cholesterol efflux. This caused dose-dependent, 24.1-43.1 % increases in the staining intensity of foam cells in the macrophage model. This atherosclerotic effect of DIDPP was proposed to be due to its antagonism of LXRα activity, as DIDPP treatment did not alter cholesterol influx. In conclusion, the findings of this study demonstrate that exposure to DIDPP may be a risk factor for atherosclerosis due to the LXRα-antagonistic activity of DIDPP and its ubiquity in the environment.

Atherosclerosis is a chronic inflammatory vascular disease characterized by lipid metabolism disorder and lipid accumulation. Equisetin (EQST) is a hemiterpene compound isolated from fungus of marine sponge origin, which has antibacterial, anti-inflammatory, lipid-lowering, and weight loss effects. Whether EQST has anti-atherosclerotic activity has not been reported. In this study, we revealed that EQST displayed anti- atherosclerosis effects through inhibiting macrophage inflammatory response, lipid uptake and foam cell formation in vitro, and finally ameliorated high-fat diet (HFD)-induced atherosclerosis in AopE-/- mice in vivo. Mechanistically, EQST directly bound to STAT3 with high-affinity by forming hydrophobic bonds at GLN247 and GLN326 residues, as well as hydrogen bonds at ARG325 and THR346 residues. EQST interacted with STAT3 physically, and functionally inhibited the transcription activity of STAT3, thereby regulating atherosclerosis. Therefore, these results supports EQST as a candidate for developing anti-atherosclerosis therapeutic agent.