Characterization of prostate macrophage heterogeneity, foam cell markers, and CXCL17 upregulation in a mouse model of steroid hormone imbalance.

Benign prostatic hyperplasia (BPH) is a prevalent age-related condition often characterized by debilitating urinary symptoms. Its etiology is believed to stem from hormonal imbalance, particularly an elevated estradiol-to-testosterone ratio and chronic inflammation. Our previous studies using a mouse steroid hormone imbalance model identified a specific increase in macrophages that migrated and accumulated in the prostate lumen where they differentiated into lipid-laden foam cells in mice implanted with testosterone and estradiol pellets, but not in sham animals. The current study focused on further characterizing the cellular heterogeneity of the prostate in this model as well as identifying the specific transcriptomic signature of the recruited foam cells. Moreover, we aimed to identify epithelia-derived signals that drive macrophage infiltration and luminal translocation. Male C57BL/6J mice were implanted with slow-release testosterone and estradiol pellets (T + E2) or sham surgery was performed and the ventral prostates were harvested two weeks later for scRNA-seq analysis. We identified Ear2 + and Cd72 + macrophages that were elevated in response to steroid hormone imbalance, whereas a Mrc1 + resident macrophage population did not change. In addition, an Spp1 + foam cell cluster was almost exclusively found in T + E2 mice. Further markers of foam cells were also identified, including Gpnmb and Trem2, and GPNMB was confirmed as a novel histological marker with immunohistochemistry. Foam cells were also shown to express known pathological factors Vegf, Tgfb1, Ccl6, Cxcl16 and Mmp12. Intriguingly, a screen for chemokines identified the upregulation of epithelia-derived Cxcl17, a known monocyte attractant, in T + E2 prostates suggesting that it might be responsible for the elevated macrophage number as well as their translocation to the lumen. Our study identified macrophage subsets that responded to steroid hormone imbalance as well as further confirmed a potential pathological role of luminal foam cells in the prostate. These results underscore a potential pathological role of the identified prostate foam cells and suggests CXCL17-mediated macrophage migration as a critical initiating event.

Chrysin downregulates the expression of ADAMTS-4 in foam cells.

BACKGROUND: Chrysin, a polyphenolic compound, possesses antioxidant and anti-inflammatory properties. In this study, we investigated the effect of chrysin on the expression of A disintegrin and metalloproteinase with thrombospondin motifs-4 (ADAMTS-4), a protease enzyme involved in degrading extracellular matrix associated with atherosclerosis. METHODS AND RESULTS: We have studied the cell viability by MTT assay and foam cell formation by oil red O staining. The mRNA and protein expression of ADAMTS-4 was studied using quantitative polymerase chain reaction (qPCR) and Western blotting, respectively. Our study showed that chrysin significantly downregulates the expression of ADAMTS-4 in foam cells. CONCLUSION: Chrysin's ability to downregulate the expression of ADAMTS-4, a protease involved in degrading the extracellular matrix, bestows upon it a new therapeutic potential for managing atherosclerosis.

High expression levels of haem oxygenase-1 promote ferroptosis in macrophage-derived foam cells and exacerbate plaque instability.

Plaque rupture with consequent thrombosis is the leading cause of acute cardiovascular events, during which macrophage death is a hallmark. Ferroptosis is a pivotal intermediate link between early and advanced atherosclerosis. Existing evidence indicates the involvement of macrophage ferroptosis in plaque vulnerability; however, the exact mechanism remains elusive. The aim of this study was to explore key ferroptosis-related genes (FRGs) involved in plaque progression and the underlying molecular mechanisms involved. The expression landscape of FRGs was obtained from atherosclerosis-related GEO datasets. Molecular mechanism studies of ferroptosis were performed using bone marrow-derived macrophages (BMDMs) and macrophage-derived foam cells (MDFCs). Bioinformatics analysis and immunohistochemistry revealed that macrophage haem oxygenase-1 (HMOX1) is the key FRG involved in plaque destabilization. Hypoxic conditions induced a significant increase in Hmox1 expression in MDFCs but not in macrophages. In addition, the beneficial or deleterious effects of Hmox1 were dependent on the degree of Hmox1 induction. Hmox1 overexpression drove inflammatory responses and ferroptotic oxidative stress in MDFCs and aggravated the plaque burden in atherosclerotic model mice. Further mechanistic investigations demonstrated that hypoxia-mediated degradation of egl-9 family hypoxia-inducible factor 3 (Egln3) stabilized Hif1a, which subsequently promoted Hmox1 transcription. Our findings suggest that high Hmox1 expression under hypoxia is deleterious to MDFC viability and plaque stability, providing a reference for the management of acute cardiovascular events.

Extracellular vesicle-derived miR-146a as a novel crosstalk mechanism for high-fat induced atherosclerosis by targeting SMAD4.

INTRODUCTION: Exosome-miR-146a is significantly increased in patients with Atherosclerosis (AS), but its mechanism and effect on AS have not been fully elucidated. OBJECTIVES: 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. CONCLUSION: 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.

The in vitro effect of myeloperoxidase oxidized LDL on THP-1 derived macrophages.

Cardiovascular diseases (CVDs) linked to atherosclerosis remains the leading cause of death worldwide. Atherosclerosis is primarily caused by the accumulation of oxidized forms of low density lipoprotein (LDL) in macrophages (MΦs) in the subendothelial layer of arteries leading to foam cell and fatty streak formation. Many studies suggest that LDL that is modified by myeloperoxidase (MPO) is a key player in the development of atherosclerosis. MΦs can adopt a variety of functional phenotypes that include mainly the proinflammatory M1 and the anti-inflammatory M2 MΦ phenotypes which are both implicated in the process of atherogenesis. In fact, MΦs that reside in atherosclerostic lesions were shown to express a variety of phenotypes ranging between the M1- and M2 MΦ types. Recently, we pointed out the involvement of MPO oxidized-LDL (Mox-LDL) in increasing inflammation in MΦs by reducing their secretion of IL-10. Since little is known about Mox-LDL-mediated pro-atherosclerostic responses in MΦs, our study aimed at analyzing the in vitro effects of Mox-LDL at this level through making use of the well-established model of human THP-1-derived Mφs. Our results demonstrate that Mox-LDL has no effect on apoptosis, reactive oxygen species (ROS) generation and cell death in our cell model; yet, interestingly, our results show that Mox-LDL is significantly engulfed at a higher rate in the different MΦ subtypes supporting its key role in foam cell formation during the progression of the disease as well as previous data that were generated using another primary MΦ cell model of atherosclerosis.

Rice bran active peptide (RBAP) inhibited macrophage differentiation to foam cell and atherosclerosis in mice via regulating cholesterol efflux.

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. PURPOSE: 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-1ß, 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. CONCLUSION: 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.

Bixin, a New Atheroprotective Carotenoid Candidate, Prevents oxLDL-Induced Cytotoxicity and Mitochondrial Dysfunction in Macrophages: Involvement of the Nrf2 and NF-κB Pathways.

The accumulation of oxidized low-density lipoprotein (oxLDL) and its toxicity in the arterial wall have been implicated in atherosclerosis. This study aimed to investigate the mechanisms underlying the atheroprotective effect of bixin, a carotenoid obtained from the seeds of the tropical plant Bixa orellana, on Cu2+-induced LDL oxidation and oxLDL-mediated effects in J774A.1 macrophage cells. Bixin's effects were compared to those of lycopene, a carotenoid widely studied for its cardiovascular protective effects. LDL was isolated from human plasma, incubated with bixin or lycopene (positive control), and subjected to oxidation with CuSO4. Afterward, bixin or lycopene was incubated with J774A.1 macrophage cells and exposed to oxLDL. The levels of ROS, RNS, GSH, nitrite, mitochondrial function, and foam cell formation, as well as the expression of proteins related to the antioxidant and inflammatory status, were evaluated. The effect of bixin in inhibiting in vitro human-isolated LDL oxidation was more potent (5-6-fold) than that of lycopene. Bixin pretreatment reduced the atherogenic signaling triggered by oxLDL in the macrophages, namely the generation of reactive species, disturbance of nitric oxide homeostasis, mitochondrial dysfunction, and foam cell formation. The cytoprotective effects of bixin were accompanied by the upregulation of Nrf2 and the downregulation of the NF-kB pathways. Lycopene showed the same protective effect as bixin, except that it did not prevent mitochondrial dysfunction. The efficient performance of bixin makes it an ideal candidate for further trials as a new nutraceutical compound for the prevention of atherosclerosis.

Cannabidiol (CBD) Inhibits Foam Cell Formation via Regulating Cholesterol Homeostasis and Lipid Metabolism.

SCOPE: The cannabidiol (CBD) in hemp oil has important pharmacological activities. Accumulating evidence suggests that CBD is beneficial in the cardiovascular system and has been applied as a health supplement for atherosclerosis. However, the mechanism remains unclear. METHODS AND RESULTS: This study investigates the impact of CBD on foam cell formation, cholesterol homeostasis, and lipid metabolism in macrophages. CBD elevates the levels of peroxisome proliferator-activated receptor gamma (PPARγ) and its associated targets, such as ATP binding transporter A1/G1 (ABCA1/ABCG1), thus reducing foam cell formation, and increasing cholesterol efflux within macrophages. Notably, the upregulation of ABCA1 and ABCG1 expression induced by CBD is found to be attenuated by both a PPARγ inhibitor and PPARγ small interfering RNA (siRNA). Moreover, transfection of PPARγ siRNA results in a decrease in the inhibitory effect of CBD on foam cell formation and promotion of cholesterol efflux. Through lipidomics analysis, the study finds that CBD significantly reverses the enhancement of ceramide (Cer). Correlation analysis indicates a negative association between Cer level and the expression of ABCA1/ABCG1. CONCLUSION: This study confirms that CBD can be an effective therapeutic candidate for atherosclerosis treatment by activating PPARγ, up-regulating ABCA1/ABCG1 expression, and down-regulating Cer level.

Chronic consequences of ischemic stroke: Profiling brain injury and inflammation in a mouse model with reperfusion.

Stroke is a pervasive and debilitating global health concern, necessitating innovative therapeutic strategies, especially during recovery. While existing literature often focuses on acute interventions, our study addresses the uniqueness of brain tissue during wound healing, emphasizing the chronic phase following the commonly used middle cerebral artery (MCA) occlusion model. Using clinically relevant endpoints in male and female mice such as magnetic resonance imaging (MRI) and plasma neurofilament light (NFL) measurement, along with immunohistochemistry, we describe injury evolution. Our findings document significant alterations in edema, tissue remodeling, and gadolinium leakage through MRI. Plasma NFL concentration remained elevated at 30 days poststroke. Microglia responses are confined to the region adjacent to the injury, rather than continued widespread activation, and boron-dipyrromethene (BODIPY) staining demonstrated the persistent presence of foam cells within the infarct. Additional immunohistochemistry highlighted sustained B and T lymphocyte presence in the poststroke brain. These observations underscore potentially pivotal roles played by chronic inflammation brought on by the lipid-rich brain environment, and chronic blood-brain barrier dysfunction, in the development of secondary neurodegeneration. This study sheds light on the enduring consequences of ischemic stroke in the most used rodent stroke model and provides valuable insights for future research, clinical strategies, and therapeutic development.

Inhibition of Toll-like Receptors Alters Macrophage Cholesterol Efflux and Foam Cell Formation.

Arterial macrophage cholesterol accumulation and impaired cholesterol efflux lead to foam cell formation and the development of atherosclerosis. Modified lipoproteins interact with toll-like receptors (TLR), causing an increased inflammatory response and altered cholesterol homeostasis. We aimed to determine the effects of TLR antagonists on cholesterol efflux and foam cell formation in human macrophages. Stimulated monocytes were treated with TLR antagonists (MIP2), and the cholesterol efflux transporter expression and foam cell formation were analyzed. The administration of MIP2 attenuated the foam cell formation induced by lipopolysaccharides (LPS) and oxidized low-density lipoproteins (ox-LDL) in stimulated THP-1 cells (p < 0.001). The expression of ATP-binding cassette transporters A (ABCA)-1, ABCG-1, scavenger receptor (SR)-B1, liver X receptor (LXR)-α, and peroxisome proliferator-activated receptor (PPAR)-γ mRNA and proteins were increased (p < 0.001) following MIP2 administration. A concentration-dependent decrease in the phosphorylation of p65, p38, and JNK was also observed following MIP2 administration. Moreover, an inhibition of p65 phosphorylation enhanced the expression of ABCA1, ABCG1, SR-B1, and LXR-α. TLR inhibition promoted the cholesterol efflux pathway by increasing the expression of ABCA-1, ABCG-1, and SR-B1, thereby reducing foam cell formation. Our results suggest a potential role of the p65/NF-kB/LXR-α/ABCA1 axis in TLR-mediated cholesterol homeostasis.

Surgical Treatment of Multiple Large Tuberous and Tendinous Xanthoma Secondary to Familial Hypercholesterolaemia: A Case Report.

Xanthomas are well-circumscribed skin lesions that are commonly seen in patients with familial hypercholesterolemia (FH). The aim of this report is to present a rare case of multiple large tuberous and tendinous xanthomas. A 17-year-old female patient in this report presented with multiple asymptomatic and papulo-nodular masses in both sides of palms, elbows, buttocks, knees, and Achilles tendons. Surgical removal of the masses was carried out in combination with lipid-lowering therapy. A following up of 3 months showed all wounds were healing well, and no recurrence of masses was observed. Therefore, for patients with xanthomas related with familial hypercholesterolaemia, lipid-lowering therapy has reportedly reduced the size of masses, but surgical treatment may be essential for large xanthomas caused pain or limitation of daily activities.

PROSTATE CELL HETEROGENEITY AND CXCL17 UPREGULATION IN MOUSE STEROID HORMONE IMBALANCE.

Benign prostatic hyperplasia (BPH) is a prevalent age-related condition often characterized by debilitating urinary symptoms. Its etiology is believed to stem from hormonal imbalance, particularly an elevated estradiol-to-testosterone ratio and chronic inflammation. Our previous studies using a mouse steroid hormone imbalance model identified a specific increase in macrophages that migrate and accumulate in the prostate lumen where they differentiate into lipid-laden foam cells in mice implanted with testosterone and estradiol pellets, but not in sham animals. The current study focused on further characterizing the cellular heterogeneity of the prostate in this model as well as identifying the specific transcriptomic signature of the recruited foam cells. Moreover, we aimed to identify the epithelia-derived signals that drive macrophage infiltration and luminal translocation. Male C57BL/6J mice were implanted with slow-release testosterone and estradiol pellets (T+E2) and harvested the ventral prostates two weeks later for scRNA-seq analysis, or performed sham surgery. We identified Ear2+ and Cd72+ macrophages that were elevated in response to steroid hormone imbalance, whereas a Mrc1+ resident macrophage population did not change. In addition, an Spp1+ foam cell cluster was almost exclusively found in T+E2 mice. Further markers of foam cells were also identified, including Gpnmb and Trem2, and GPNMB was confirmed as a novel histological marker with immunohistochemistry. Foam cells were also shown to express known pathological factors Vegf, Tgfb1, Ccl6, Cxcl16 and Mmp12. Intriguingly, a screen for chemokines identified the upregulation of epithelial-derived Cxcl17, a known monocyte attractant, in T+E2 prostates suggesting that it might be responsible for the elevated macrophage number as well as their translocation to the lumen. Our study identified macrophage subsets that respond to steroid hormone imbalance as well as further confirmed a potential pathological role of luminal foam cells in the prostate. These results underscore a pathological role of the identified prostate foam cells and suggests CXCL17-mediated macrophage migration as a critical initiating event.

The Role of Fatty Acid Synthase in the Vascular Smooth Muscle Cell to Foam Cell Transition.

Vascular smooth muscle cells (VSMCs), in their contractile and differentiated state, are fundamental for maintaining vascular function. Upon exposure to cholesterol (CHO), VSMCs undergo dedifferentiation, adopting characteristics of foam cells-lipid-laden, macrophage-like cells pivotal in atherosclerotic plaque formation. CHO uptake by VSMCs leads to two primary pathways: ABCA1-mediated efflux or storage in lipid droplets as cholesterol esters (CEs). CE formation, involving the condensation of free CHO and fatty acids, is catalyzed by sterol O-acyltransferase 1 (SOAT1). The necessary fatty acids are synthesized by the lipogenic enzyme fatty acid synthase (FASN), which we found to be upregulated in atherosclerotic human coronary arteries. This observation led us to hypothesize that FASN-mediated fatty acid biosynthesis is crucial in the transformation of VSMCs into foam cells. Our study reveals that CHO treatment upregulates FASN in human aortic SMCs, concurrent with increased expression of CD68 and upregulation of KLF4, markers associated with the foam cell transition. Crucially, downregulation of FASN inhibits the CHO-induced upregulation of CD68 and KLF4 in VSMCs. Additionally, FASN-deficient VSMCs exhibit hindered lipid accumulation and an impaired transition to the foam cell phenotype following CHO exposure, while the addition of the fatty acid palmitate, the main FASN product, exacerbates this transition. FASN-deficient cells also show decreased SOAT1 expression and elevated ABCA1. Notably, similar effects are observed in KLF4-deficient cells. Our findings demonstrate that FASN plays an essential role in the CHO-induced upregulation of KLF4 and the VSMC to foam cell transition and suggest that targeting FASN could be a novel therapeutic strategy to regulate VSMC phenotypic modulation.

Unexpected omega-3 activities in intracellular lipolysis and macrophage foaming revealed by fluorescence lifetime imaging.

Omega-3 polyunsaturated fatty acids (PUFA) found primarily in fish oil have been a popular supplement for cardiovascular health because they can substantially reduce circulating triglyceride levels in the bloodstream to prevent atherosclerosis. Beyond this established extracellular activity, here, we report a mode of action of PUFA, regulating intracellular triglyceride metabolism and lipid droplet (LD) dynamics. Real-time imaging of the subtle and highly dynamic changes of intracellular lipid metabolism was enabled by a fluorescence lifetime probe that addressed the limitations of intensity-based fluorescence quantifications. Surprisingly, we found that among omega-3 PUFA, only docosahexaenoic acid (DHA) promoted the lipolysis in LDs and reduced the overall fat content by approximately 50%, and consequently helped suppress macrophage differentiation into foam cells, one of the early steps responsible for atherosclerosis. Eicosapentaenoic acid, another omega-3 FA in fish oil, however, counteracted the beneficial effects of DHA on lipolysis promotion and cell foaming prevention. These in vitro findings warrant future validation in vivo.

Fluvastatin Converts Human Macrophages into Foam Cells with Increased Inflammatory Response to Inactivated Mycobacterium tuberculosis H37Ra.

Cholesterol biosynthesis inhibitors (statins) protect hypercholesterolemic patients against developing active tuberculosis, suggesting that these drugs could help the host to control the pathogen at the initial stages of the disease. This work studies the effect of fluvastatin on the early response of healthy peripheral blood mononuclear cells (PBMCs) to inactivated Mycobacterium tuberculosis (Mtb) H37Ra. We found that in fluvastatin-treated PBMCs, most monocytes/macrophages became foamy cells that overproduced NLRP3 inflammasome components in the absence of immune stimulation, evidencing important cholesterol metabolism/immunity connections. When both fluvastatin-treated and untreated PBMCs were exposed to Mtb H37Ra, a small subset of macrophages captured large amounts of bacilli and died, concentrating the bacteria in necrotic areas. In fluvastatin-untreated cultures, most of the remaining macrophages became epithelioid cells that isolated these areas of cell death in granulomatous structures that barely produced IFNγ. By contrast, in fluvastatin-treated cultures, foamy macrophages surrounded the accumulated bacteria, degraded them, markedly activated caspase-1 and elicited a potent IFNγ/cytotoxic response. In rabbits immunized with the same bacteria, fluvastatin increased the tuberculin test response. We conclude that statins may enhance macrophage efficacy to control Mtb, with the help of adaptive immunity, offering a promising tool in the design of alternative therapies to fight tuberculosis.

Downregulation of HMGB1 carried by macrophage-derived extracellular vesicles delays atherosclerotic plaque formation through Caspase-11-dependent macrophage pyroptosis.

BACKGROUND: Macrophage-derived extracellular vesicle (macrophage-EV) is highly studied for its regulatory role in atherosclerosis (AS). Our current study tried to elucidate the possible role of macrophage-EV loaded with small interfering RNA against high-mobility group box 1 (siHMGB1) affecting atherosclerotic plaque formation. METHODS: In silico analysis was performed to find critical factors in mouse atherosclerotic plaque formation. EVs secreted by RAW 264.7 cells were collected by ultracentrifugation and characterized, followed by the preparation of macrophage-EV-loaded siHMGB1 (macrophage-EV/siHMGB1). ApoE-/- mice were used to construct an AS mouse model by a high-fat diet, followed by injection of macrophage-EV/siHMGB1 to assess the in vivo effect of macrophage-EV/siHMGB1 on AS mice. RAW264.7 cells were subjected to ox-LDL, LPS or macrophage-EV/siHMGB1 for analyzing the in vitro effect of macrophage-EV/siHMGB1 on macrophage pyrophosis and inflammation. RESULTS: In silico analysis found that HMGB1 was closely related to the development of AS. Macrophage-EV/siHMGB could inhibit the release of HMGB1 from macrophages to outside cells, and the reduced HMGB1 release could inhibit foam cell formation. Besides, macrophage-EV/siHMGB also inhibited the LPS-induced Caspase-11 activation, thus inhibiting macrophage pyroptosis and preventing atherosclerotic plaque formation. CONCLUSION: Our results proved that macrophage-EV/siHMGB could inhibit foam cell formation and suppress macrophage pyroptosis, finally preventing atherosclerotic plaque formation in AS mice.

The anti-atherosclerotic effect of Paeonol against the lipid accumulation in macrophage-derived foam cells by inhibiting ferroptosis via the SIRT1/NRF2/GPX4 signaling pathway.

Atherosclerosis (AS) is the underlying cause of many severe vascular diseases and is primarily characterized by abnormal lipid metabolism. Paeonol (Pae), a bioactive compound derived from Paeonia Suffruticosa Andr., is recognized for its significant role in reducing lipid accumulation. Our research objective is to explore the link between lipid buildup in foam cells originating from macrophages and the process of ferroptosis, and explore the effect and mechanism of Pae on inhibiting AS by regulating ferroptosis. In our animal model, ApoE-deficient mice, which were provided with a high-fat regimen to provoke atherosclerosis, were administered Pae. The treatment was benchmarked against simvastatin and ferrostatin-1. The results showed that Pae significantly reduced aortic ferroptosis and lipid accumulation in the mice. In vitro experiments further demonstrated that Pae could decrease lipid accumulation in foam cells induced by oxidized low-density lipoprotein (LDL) and challenged with the ferroptosis inducer erastin. Crucially, the protective effect of Pae against lipid accumulation was dependent on the SIRT1/NRF2/GPX4 pathway, as SIRT1 knockdown abolished this effect. Our findings suggest that Pae may offer a novel therapeutic approach for AS by inhibiting lipid accumulation through the suppression of ferroptosis, mediated by the SIRT1/NRF2/GPX4 pathway. Such knowledge has the potential to inform the creation of novel therapeutic strategies aimed at regulating ferroptosis within the context of atherosclerosis.

Avocado-derived extracellular vesicles loaded with ginkgetin and berberine prevent inflammation and macrophage foam cell formation.

Atherosclerosis, a chronic inflammatory disease of aorta, remains the major cause of morbidity and mortality among cardiovascular disease patients. Macrophage foam cell formation and inflammation are critically involved in early stages of atherosclerosis, hence chemopreventive targeting of foam cell formation by nutraceuticals may be a promising approach to curbing the progression of atherosclerosis. However, many nutraceuticals including berberine and ginkgetin have low stability, tissue/cell penetration and bioavailability resulting in inadequate chemotherapeutic effects of these nutraceuticals. We have used avocado-derived extracellular vesicles (EV) isolated from avocado (EVAvo ) as a novel carrier of nutraceuticals, in a strategy to alleviate the build-up of macrophage foam cells and expression of inflammatory genes. Our key findings are: (i) Avocado is a natural source of plant-derived EVs as shown by the results from transmission electron microscopy, dynamic light scattering and NanoBrook Omni analysis and atomic force microscopy; (ii) EVAvo are taken up by macrophages, a critical cell type in atherosclerosis; (iii) EVAvo can be loaded with high amounts of ginkgetin and berberine; (iv) ginkgetin plus berberine-loaded EVAvo (EVAvo(B+G) ) suppress activation of NFκB and NLRP3, and inhibit expression of pro-inflammatory and atherogenic genes, specifically Cd36, Tnfα, Il1ß and Il6; (v) EVAvo(B+G) attenuate oxidized low-density lipoprotein (oxLDL)-induced macrophage foam cell formation and (vi) EVAvo(B+G) inhibit oxLDL uptake but not its cell surface binding during foam cell formation. Overall, our results suggest that using EVAvo as a natural carrier of nutraceuticals may improve strategies to curb the progression of atherosclerosis by limiting inflammation and pro-atherogenic responses.