PKM2-dependent glycolysis promotes the proliferation and migration of vascular smooth muscle cells during atherosclerosis.

Increased glycolysis is involved in the proliferation and migration of vascular smooth muscle cells (VSMCs). Pyruvate kinase isoform M2 (PKM2), a key rate-limiting enzyme in glycolysis, accelerates the proliferation and migration of tumor cells. Although the intracellular mechanisms associated with oxidized low-density lipoprotein (oxLDL)-stimulated VSMC proliferation and migration have been extensively explored, it is still unclear whether oxLDL promotes the proliferation and migration of VSMCs by enhancing PKM2-dependent glycolysis. In the present study, we detected PKM2 expression and pyruvate kinase activity in oxLDL-treated VSMCs and explored the regulation of PKM2 in oxLDL-treated VSMCs and apoE-/- mice. The results showed that PKM2 expression in VSMCs was higher in the intima than in the media in plaques from atherosclerotic rabbits. Moreover, PKM2 level in VSMCs was increased during atherosclerosis progression in apoE-/- mice. Both PKM2 expression and pyruvate kinase activity were found to be upregulated by oxLDL stimulation in VSMCs. Shikonin (SKN), a specific inhibitor of PKM2, was found to inhibit the oxLDL-induced proliferation and migration in VSMCs, in addition to delaying the atherosclerosis progression in apoE-/- mice. More importantly, oxLDL increased glucose uptake, ATP and lactate production, and the extracellular acidification rate in VSMCs, which could be reversed by SKN. Meanwhile, oxygen consumption rate was unchanged after oxLDL stimulation, suggesting that glycolysis is the main contributor to the energy supply in oxLDL-treated VSMCs. Our results suggest that oxLDL induces VSMC proliferation and migration by upregulating PKM2-dependent glycolysis, thereby contributing to the atherosclerosis progression. Thus, targeting PKM2-dependent glycolysis might provide a novel therapeutic approach for the treatment of atherosclerosis.

Increased hepcidin in hemorrhagic plaques correlates with iron-stimulated IL-6/STAT3 pathway activation in macrophages.

Intraplaque hemorrhage (IPH) promotes the rapid progression of atherosclerotic plaques, resulting in cardiovascular events in a short time. Hepcidin increases iron retention and exerts proinflammatory effects in plaques. However, hepcidin expression levels in hemorrhagic plaques remain unknown. In the present study, we evaluated hepcidin expression in hemorrhagic plaques and the underlying mechanism. To investigate hepcidin expression in hemorrhagic plaques, carotid artery plaques were collected from patients undergoing carotid endarterectomy (CEA) and apolipoprotein E-deficient mice. The hepcidin expression level was increased in the area of IPH and positively correlated with the amount of hemorrhage as shown by immunohistochemistry. Hepcidin expression in macrophages within human plaques was confirmed by immunofluorescence. Furthermore, ferric ammonium citrate (FAC) was found to induce hepcidin and interleukin-6 (IL-6) expression in THP-1 macrophages and mouse peritoneal macrophages. Subsequently, activation of the IL-6/signal transducer and activator of transcription (STAT) 3 pathway was observed in rabbit hemorrhagic plaques. Macrophages were pretreated with antibodies that block IL-6/IL-6R interactions or STAT3 activation and dimerization inhibitor (STATTIC), and the results indicated that FAC induced hepcidin expression through the IL-6/STAT3 pathway. In conclusion, our data indicate that hepcidin levels are increased in hemorrhagic plaques, which correlates with iron-stimulated IL-6/STAT3 pathway activation in macrophages. Therefore, inhibition of the IL-6/STAT3 pathway may be a potential strategy to reduce hepcidin expression and further stabilize hemorrhagic plaques.

Hydrogen sulfide reduces serum triglyceride by activating liver autophagy via the AMPK-mTOR pathway.

Autophagy plays an important role in liver triglyceride (TG) metabolism. Inhibition of autophagy could reduce the clearance of TG in the liver. Hydrogen sulfide (H2S) is a potent stimulator of autophagic flux. Recent studies showed H2S is protective against hypertriglyceridemia (HTG) and noalcoholic fatty liver disease (NAFLD), while the mechanism remains to be explored. Here, we tested the hypothesis that H2S reduces serum TG level and ameliorates NAFLD by stimulating liver autophagic flux by the AMPK-mTOR pathway. The level of serum H2S in patients with HTG was lower than that of control subjects. Sodium hydrosulfide (NaHS, H2S donor) markedly reduced serum TG levels of male C57BL/6 mice fed a high-fat diet (HFD), which was abolished by coadministration of chloroquine (CQ), an inhibitor of autophagic flux. In HFD mice, administration of NaSH increased the LC3BII-to-LC3BI ratio and decreased the p62 protein level. Meanwhile, NaSH increased the phosphorylation of AMPK and thus reduced the phosphorylation of mTOR in a Western blot study. In cultured LO2 cells, high-fat treatment reduced the ratio of LC3BII to LC3BI and the phosphorylation of AMPK, which were reversed by the coadministration of NaSH. Knockdown of AMPK by siRNA in LO2 cells blocked the autophagic enhancing effects of NaSH. The same qualitative effect was observed in AMPKα2(-/-) mice. These results for the first time demonstrated that H2S could reduce serum TG level and ameliorate NAFLD by activating liver autophagy via the AMPK-mTOR pathway.

Sonodynamic therapy reduces iron retention of hemorrhagic plaque.

Intraplaque hemorrhage (IPH) plays a major role in the aggressive progression of vulnerable plaque, leading to acute cardiovascular events. We previously demonstrated that sonodynamic therapy (SDT) inhibits atherosclerotic plaque progression. In this study, we investigated whether SDT could also be applied to treat more advanced hemorrhagic plaque and addressed the underlying mechanism. SDT decreased atherosclerotic burden, positively altered atherosclerotic lesion composition, and alleviated iron retention in rabbit hemorrhagic plaques. Furthermore, SDT reduced iron retention by stimulating ferroportin 1 (Fpn1) expression in apolipoprotein E (ApoE)-/- mouse plaques with high susceptibility to IPH. Subsequently, SDT inhibited iron-overload-induced foam-cell formation and pro-inflammatory cytokines secretion in vitro. Moreover, SDT reduced levels of the labile iron pool and ferritin expression via the reactive oxygen species (ROS)-nuclear factor erythroid 2-related factor 2 (Nrf2)-FPN1 pathway. SDT exerted therapeutic effects on hemorrhagic plaques and reduced iron retention via the ROS-Nrf2-FPN1 pathway in macrophages, thereby suggesting that it is a potential translational strategy for patients with advanced atherosclerosis in clinical practice.

[Impact of magnetic attachment keepers on magnetic resonance imaging examination].

OBJECTIVE: To evaluate the effects of magnetic attachment keepers on MRI images. METHODS: In in vitro part, keepers of MAGFIT EX 400, MAGFIT EX 600 and MAGNEDISC 800 magnetic attachment systems were cast into standard root-caps with different alloy respectively, including nickel-chromium alloy and gold-palladium alloy, or not be cast for contrast. In in vivo part, volunteers with keepers in different position and amount were included. All the specimens and volunteers were imaged by a Siemens SONATA 1.5-T MRI scanner. Extent of the artifacts in every slice was measured. The magnitude of the artifacts and the distortion of the anatomic structures were compared. RESULTS: All kinds of keepers being studied produced obvious MRI artifacts. The extent of MRI artifacts induced by MAGFIT EX 400 keepers, MAGFIT EX 600 keepers and MAGNEDISC 800 keepers are 158.94 mm, 168.52 mm and 173.00 mm, respectively. The images of mental region, tongue, palate, jawbone and sinus were evidently obscured by artifacts in all cases. When keeper was put in the molar region, the keeper-related MRI artifact may obscure the imaging of brain, spinal cord. SE sequence with right-left frequency-encoding direction was more desirable in MRI for the patients with magnetic attachment keepers. CONCLUSION: Keepers of magnetic attachment system did induce obvious artifacts in MRI examination.

Early modulation of macrophage ROS-PPARγ-NF-κB signalling by sonodynamic therapy attenuates neointimal hyperplasia in rabbits.

Disruption of re-endothelialization and haemodynamic balance remains a critical side effect of drug-eluting stents (DES) for preventing intimal hyperplasia. Previously, we found that 5-aminolevulinic acid-mediated sonodynamic therapy (ALA-SDT) suppressed macrophage-mediated inflammation in atherosclerotic plaques. However, the effects on intimal hyperplasia and re-endothelialization remain unknown. In this study, 56 rabbits were randomly assigned to control, ultrasound, ALA and ALA-SDT groups, and each group was divided into two subgroups (n = 7) on day 3 after right femoral artery balloon denudation combined with a hypercholesterolemic diet. Histopathological analysis revealed that ALA-SDT enhanced macrophage apoptosis and ameliorated inflammation from day 1. ALA-SDT inhibited neointima formation without affecting re-endothelialization, increased blood perfusion, decreased the content of macrophages, proliferating smooth muscle cells (SMCs) and collagen but increased elastin by day 28. In vitro, ALA-SDT induced macrophage apoptosis and reduced TNF-α, IL-6 and IL-1ß via the ROS-PPARγ-NF-κB signalling pathway, which indirectly inhibited human umbilical artery smooth muscle cell (HUASMC) proliferation, migration and IL-6 production. ALA-SDT effectively inhibits intimal hyperplasia without affecting re-endothelialization. Hence, its clinical application combined with bare-metal stent (BMS) implantation presents a potential strategy to decrease bleeding risk caused by prolonged dual-antiplatelet regimen after DES deployment.

Sonodynamic Therapy Suppresses Neovascularization in Atherosclerotic Plaques via Macrophage Apoptosis-Induced Endothelial Cell Apoptosis.

During atherosclerosis plaque progression, pathological intraplaque angiogenesis leads to plaque rupture accompanied by thrombosis, which is probably the most important cause of arteries complications such as cerebral and myocardial infarction. Even though few treatments are available to mitigate plaque rupture, further investigation is required to develop a robust optimized therapeutic method. In this study using rabbit and mouse atherosclerotic models, sinoporphyrin sodium (DVDMS)-mediated sonodynamic therapy reduced abnormal angiogenesis and plaque rupture. Briefly, DVDMS is injected to animals, and then the plaque was locally exposed to pulse ultrasound for a few minutes. Furthermore, a small size clinical trial was conducted on patients with atherosclerosis. Notably, a significant reduction of arterial inflammation and angiogenesis was recorded following a short period of DVDMS-mediated sonodynamic therapy treatment. This beneficial outcome was almost equivalent to the therapeutic outcome after 3-month intensive statin treatment.

Membrane-permeabilized sonodynamic therapy enhances drug delivery into macrophages.

Macrophages play a pivotal role in the formation and development of atherosclerosis as a predominant inflammatory cell type present within atherosclerotic plaque. Promoting anti-atherosclerotic drug delivery into macrophages may provide a therapeutic potential on atherosclerotic plaque. In this study, we investigated whether membrane-permeabilized sonodynamic therapy (MP-SDT) enhances drug delivery into THP-1 macrophages. Images of confocal microscopy confirmed that the optimal plasma distribution of the sonosensitizer protoporphyrin IX (PpIX) was at 1 hour incubation. The non-lethal parameter of MP-SDT was determined by cell viability as measured by a CCK-8 assay. Bright field microscopy demonstrated plasma membrane deformation in response to MP-SDT. Using SYTOX Green, a model drug for cellular uptake, we found that MP-SDT significantly induced membrane permeabilization dependent on ultrasound intensity and exposure time. Using Fluo-3 AM, intracellular calcium elevation during MP-SDT was confirmed as a result of membrane permeabilization. Membrane perforation of MP-SDT-treated cells was observed by scanning electron microscopy and transmission electron microscopy. Moreover, MP-SDT-induced membrane permeabilization and perforation were remarkably prevented by scavenging reactive oxygen species (ROS) during MP-SDT. Furthermore, we assessed the therapeutic effect of MP-SDT in combination with anti-atherosclerotic drug atorvastatin. Our results showed that MP-SDT increased the therapeutic effect of atorvastatin on lipid-laden THP-1-derived foam cells, including decreasing lipid droplets, increasing the cholesterol efflux and the expression of PPARγ and ABCG1. In conclusion, MP-SDT might become a promising approach to facilitating the delivery of anti-atherosclerotic drugs into macrophages via membrane permeabilization.

In situ growth of Fe(ii)-MOF-74 nanoarrays on nickel foam as an efficient electrocatalytic electrode for water oxidation: a mechanistic study on valence engineering.

In this work, our theoretical results first demonstrate that varying the metal valence in MOFs plays a significant role in tuning their stable intrinsic electronic structure. Different valence Fe(ii) and Fe(iii) based pristine MOF-74 nanoarrays on nickel foam are further synthesized as electrodes for highly efficient electrocatalytic water oxidation.

Rapid inhibition of atherosclerotic plaque progression by sonodynamic therapy.

Aims: Currently, efficient regimens to reverse atherosclerotic plaques are not available in the clinic. Herein, we present sonodynamic therapy (SDT) as a novel methodology to rapidly inhibit progression of atherosclerotic plaques. Methods and results: In atherosclerotic rabbit and apoE-deficient mouse models, SDT efficiently decreased the atherosclerotic burden within 1 week, revealing a decrease in the size of the atherosclerotic plaque and enlarged lumen. The shrunken atherosclerotic plaques displayed compositional alterations, with a reduction in lesional macrophages and lipids. The rapid efficacy of SDT may be due to its induction of macrophage apoptosis, enhancement of efferocytosis, and amelioration of inflammation in the atherosclerotic plaque. Compared with atorvastatin, the standard of care for atherosclerosis, SDT showed more significant plaque shrinkage and lumen enlargement during 1 week treatment. Furthermore, SDT displayed good safety without obvious side effects. In a pilot clinical trial recruiting the patients suffering atherosclerotic peripheral artery disease, combination therapy of SDT with atorvastatin efficiently reduced progression of atherosclerotic plaque within 4 weeks, and its efficacy was able to last for at least 40 weeks. Conclusion: SDT is a non-invasive and efficacious regimen to inhibit atherosclerotic plaque progression.

Novel perovskite-based composites, La1-x Nd x FeO3@activated carbon, as efficient catalysts for the degradation of organic pollutants by heterogeneous electro-Fenton reactions.

Perovskites, which have excellent electrocatalytic properties, are promising for use in heterogeneous catalysis. However, the design and development of green and effective electrocatalysts for environmental water treatment remains an arduous challenge. To overcome such difficulties, we present a facile sol-gel method for the design and preparation of a series of perovskite-activated carbon (AC) composites (La1-x Nd x FeO3@AC) for the degradation of methyl orange (MO) by heterogeneous electro-Fenton reactions. Furthermore, the as-made La0.6Nd0.4FeO3@AC composite anode had the strongest oxidation ability and stability, with MO wastewater and COD removal rates reaching 99.81% and 96.66% within 10 minutes, respectively. As far as we know, the La1-x Nd x FeO3@AC composites can be regarded as a series of the most effective catalysts for the degradation of MO to date.