Stepwise targeted strategies for improving neurological function by inhibiting oxidative stress levels and inflammation following ischemic stroke.

Ischemia-reperfusion injury is caused by excessive production of reactive oxygen species (ROS) and inflammation accompanied by ischemic injury symptoms and blood-brain barrier (BBB) dysfunction. This causes neuronal damage, for which no effective treatments or drugs exist. Herein, we provided a stepwise targeted drug delivery strategy and successfully prepared multifunctional ORD@SHp@ANG nanoparticles (NPs) that consist of a stroke homing peptide (DSPE-PEG2000-SHp), BBB-targeting peptide (DSPE-PEG2000-ANG), and ROS-responsive Danshensu (salvianic acid A) chain self-assembly. ORD@SHp@ANG NPs effectively crossed the BBB by ANG peptide and selectively targeted the ischemic brain sites using stroke-homing peptide. The results showed that ORD@SHp@ANG NPs can effective at scavenging ROS, and protect SH-SY5Y cells from oxidative damage in vitro. Furthermore, ORD@SHp@ANG NPs showed excellent biocompatibility. These NPs recognized brain endothelial cells and crossed the BBB, regulated the transformation of microglia into the anti-inflammatory phenotype, and inhibited the production of inflammatory factors in a rat ischemia-reperfusion model, thereby reducing cerebral infarction, neuronal apoptosis and preserving BBB integrity. Sequencing revealed that ORD@SHp@ANG NPs promote cell proliferation, activate immune responses, suppress inflammatory responses, and ameliorate ischemic stroke. In conclusion, this study reports a simple and promising drug delivery strategy for managing ischemic stroke.

Hepatic sialic acid synthesis modulates glucose homeostasis in both liver and skeletal muscle.

OBJECTIVE: Sialic acid is a terminal monosaccharide of glycans in glycoproteins and glycolipids, and its derivation from glucose is regulated by the rate-limiting enzyme UDP-GlcNAc 2-epimerase/ManNAc kinase (GNE). Although the glycans on key endogenous hepatic proteins governing glucose metabolism are sialylated, how sialic acid synthesis and sialylation in the liver influence glucose homeostasis is unknown. Studies were designed to fill this knowledge gap. METHODS: To decrease the production of sialic acid and sialylation in hepatocytes, a hepatocyte-specific GNE knockdown mouse model was generated, and systemic glucose metabolism, hepatic insulin signaling and glucagon signaling were evaluated in vivo or in primary hepatocytes. Peripheral insulin sensitivity was also assessed. Furthermore, the mechanisms by which sialylation in the liver influences hepatic insulin signaling and glucagon signaling and peripheral insulin sensitivity were identified. RESULTS: Liver GNE deletion in mice caused an impairment of insulin suppression of hepatic glucose production. This was due to a decrease in the sialylation of hepatic insulin receptors (IR) and a decline in IR abundance due to exaggerated degradation through the Eph receptor B4. Hepatic GNE deficiency also caused a blunting of hepatic glucagon receptor (GCGR) function which was related to a decline in its sialylation and affinity for glucagon. An accompanying upregulation of hepatic FGF21 production caused an enhancement of skeletal muscle glucose disposal that led to an overall increase in glucose tolerance and insulin sensitivity. CONCLUSION: These collective observations reveal that hepatic sialic acid synthesis and sialylation modulate glucose homeostasis in both the liver and skeletal muscle. By interrogating how hepatic sialic acid synthesis influences glucose control mechanisms in the liver, a new metabolic cycle has been identified in which a key constituent of glycans generated from glucose modulates the systemic control of its precursor.

Macrophage-to-endothelial cell crosstalk by the cholesterol metabolite 27HC promotes atherosclerosis in male mice.

Hypercholesterolemia and vascular inflammation are key interconnected contributors to the pathogenesis of atherosclerosis. How hypercholesterolemia initiates vascular inflammation is poorly understood. Here we show in male mice that hypercholesterolemia-driven endothelial activation, monocyte recruitment and atherosclerotic lesion formation are promoted by a crosstalk between macrophages and endothelial cells mediated by the cholesterol metabolite 27-hydroxycholesterol (27HC). The pro-atherogenic actions of macrophage-derived 27HC require endothelial estrogen receptor alpha (ERα) and disassociation of the cytoplasmic scaffolding protein septin 11 from ERα, leading to extranuclear ERα- and septin 11-dependent activation of NF-κB. Furthermore, pharmacologic inhibition of cyp27a1, which generates 27HC, affords atheroprotection by reducing endothelial activation and monocyte recruitment. These findings demonstrate cell-to-cell communication by 27HC, and identify a major causal linkage between the hypercholesterolemia and vascular inflammation that partner to promote atherosclerosis. Interventions interrupting this linkage may provide the means to blunt vascular inflammation without impairing host defense to combat the risk of atherosclerotic cardiovascular disease that remains despite lipid-lowering therapies.

Mitochondrial Substrate Utilization Regulates Cardiomyocyte Cell Cycle Progression.

The neonatal mammalian heart is capable of regeneration for a brief window of time after birth. However, this regenerative capacity is lost within the first week of life, which coincides with a postnatal shift from anaerobic glycolysis to mitochondrial oxidative phosphorylation, particularly towards fatty-acid utilization. Despite the energy advantage of fatty-acid beta-oxidation, cardiac mitochondria produce elevated rates of reactive oxygen species when utilizing fatty acids, which is thought to play a role in cardiomyocyte cell-cycle arrest through induction of DNA damage and activation of DNA-damage response (DDR) pathway. Here we show that inhibiting fatty-acid utilization promotes cardiomyocyte proliferation in the postnatatal heart. First, neonatal mice fed fatty-acid deficient milk showed prolongation of the postnatal cardiomyocyte proliferative window, however cell cycle arrest eventually ensued. Next, we generated a tamoxifen-inducible cardiomyocyte-specific, pyruvate dehydrogenase kinase 4 (PDK4) knockout mouse model to selectively enhance oxidation of glycolytically derived pyruvate in cardiomyocytes. Conditional PDK4 deletion resulted in an increase in pyruvate dehydrogenase activity and consequently an increase in glucose relative to fatty-acid oxidation. Loss of PDK4 also resulted in decreased cardiomyocyte size, decreased DNA damage and expression of DDR markers and an increase in cardiomyocyte proliferation. Following myocardial infarction, inducible deletion of PDK4 improved left ventricular function and decreased remodelling. Collectively, inhibition of fatty-acid utilization in cardiomyocytes promotes proliferation, and may be a viable target for cardiac regenerative therapies.

Identification of scavenger receptor B1 as the airway microfold cell receptor for Mycobacterium tuberculosis.

Mycobacterium tuberculosis (Mtb) can enter the body through multiple routes, including via specialized transcytotic cells called microfold cells (M cell). However, the mechanistic basis for M cell entry remains undefined. Here, we show that M cell transcytosis depends on the Mtb Type VII secretion machine and its major virulence factor EsxA. We identify scavenger receptor B1 (SR-B1) as an EsxA receptor on airway M cells. SR-B1 is required for Mtb binding to and translocation across M cells in mouse and human tissue. Together, our data demonstrate a previously undescribed role for Mtb EsxA in mucosal invasion and identify SR-B1 as the airway M cell receptor for Mtb.

SR-B1 drives endothelial cell LDL transcytosis via DOCK4 to promote atherosclerosis.

Atherosclerosis, which underlies life-threatening cardiovascular disorders such as myocardial infarction and stroke1, is initiated by passage of low-density lipoprotein (LDL) cholesterol into the artery wall and its engulfment by macrophages, which leads to foam cell formation and lesion development2,3. It is unclear how circulating LDL enters the artery wall to instigate atherosclerosis. Here we show in mice that scavenger receptor class B type 1 (SR-B1) in endothelial cells mediates the delivery of LDL into arteries and its accumulation by artery wall macrophages, thereby promoting atherosclerosis. LDL particles are colocalized with SR-B1 in endothelial cell intracellular vesicles in vivo, and transcytosis of LDL across endothelial monolayers requires its direct binding to SR-B1 and an eight-amino-acid cytoplasmic domain of the receptor that recruits the guanine nucleotide exchange factor dedicator of cytokinesis 4 (DOCK4)4. DOCK4 promotes internalization of SR-B1 and transport of LDL by coupling the binding of LDL to SR-B1 with activation of RAC1. The expression of SR-B1 and DOCK4 is increased in atherosclerosis-prone regions of the mouse aorta before lesion formation, and in human atherosclerotic arteries when compared with normal arteries. These findings challenge the long-held concept that atherogenesis involves passive movement of LDL across a compromised endothelial barrier. Interventions that inhibit the endothelial delivery of LDL into artery walls may represent a new therapeutic category in the battle against cardiovascular disease.

Nonnuclear Estrogen Receptor Activation Improves Hepatic Steatosis in Female Mice.

Estrogens have the potential to afford atheroprotection, to prevent excess adiposity and its metabolic complications including insulin resistance, and to lessen hepatic steatosis. Cellular responses to estrogens occur through gene regulation by nuclear estrogen receptors (ERs), and through signal initiation by plasma membrane-associated ER. Leveraging the potentially favorable cardiometabolic actions of estrogens has been challenging, because their reproductive tract and cancer-promoting effects adversely impact the risk to benefit ratio of the therapy. In previous works, we discovered that an estrogen dendrimer conjugate (EDC) comprised of ethinyl-estradiol (E2) molecules linked to a poly(amido)amine dendrimer selectively activates nonnuclear ER, and in mice, EDC does not invoke a uterotrophic response or support ER-positive breast cancer growth. In the present investigation, we employed EDC to determine how selective nonnuclear ER activation impacts atherosclerosis, adiposity, glucose homeostasis, and hepatic steatosis in female mice. In contrast to E2, EDC did not blunt atherosclerosis in hypercholesterolemic apoE-/- mice. Also in contrast to E2, EDC did not prevent the increase in adiposity caused by Western diet feeding in wild-type mice, and it did not affect Western diet-induced glucose intolerance. However, E2 and EDC had comparable favorable effect on diet-induced hepatic steatosis, and this was related to down-regulation of fatty acid and triglyceride synthesis genes in the liver. Predictably, only E2 caused a uterotrophic response. Thus, although nonnuclear ER activation does not prevent atherosclerosis or diet-induced obesity or glucose intolerance, it may provide a potential new strategy to combat hepatic steatosis without impacting the female reproductive tract or increasing cancer risk.

Loss of Reelin protects against atherosclerosis by reducing leukocyte-endothelial cell adhesion and lesion macrophage accumulation.

The multimodular glycoprotein Reelin controls neuronal migration and synaptic transmission by binding to apolipoprotein E receptor 2 (Apoer2) and very low density lipoprotein receptor (Vldlr) on neurons. In the periphery, Reelin is produced by the liver, circulates in blood, and promotes thrombosis and hemostasis. To investigate if Reelin influences atherogenesis, we studied atherosclerosis-prone low-density lipoprotein receptor-deficient (Ldlr(-/-)) mice in which we inducibly deleted Reelin either ubiquitously or only in the liver, thus preventing the production of circulating Reelin. In both types of Reelin-deficient mice, atherosclerosis progression was markedly attenuated, and macrophage content and endothelial cell staining for vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) were reduced at the sites of atherosclerotic lesions. Intravital microscopy revealed decreased leukocyte-endothelial adhesion in the Reelin-deficient mice. In cultured human endothelial cells, Reelin enhanced monocyte adhesion and increased ICAM1, VCAM1, and E-selectin expression by suppressing endothelial nitric oxide synthase (eNOS) activity and increasing nuclear factor κB (NF-κB) activity in an Apoer2-dependent manner. These findings suggest that circulating Reelin promotes atherosclerosis by increasing vascular inflammation, and that reducing or inhibiting circulating Reelin may present a novel approach for the prevention of cardiovascular disease.

Inhibition of ABCA1 protein degradation promotes HDL cholesterol efflux capacity and RCT and reduces atherosclerosis in mice.

ABCA1 plays a key role in the initial lipidation of apoA-I, which generates circulating HDL cholesterol. Whereas it is known that the transcriptional upregulation of ABCA1 promotes HDL formation and reverse cholesterol transport (RCT), it is not known how the inhibition of ABCA1 protein degradation impacts HDL function. Employing the small molecule triacetyl-3-hydroxyphenyladenosine (IMM-H007), we determined how the attenuation of ABCA1 protein degradation affects HDL cholesterol efflux capacity, RCT, and atherosclerotic lesion formation. Pulse-chase analysis revealed that IMM-H007 inhibits ABCA1 degradation and facilitates its cell-surface localization in macrophages, and additional studies in macrophages showed that IMM-H007 thereby promotes cholesterol efflux. IMM-H007 treatment of Paigen diet-fed mice caused an increase in circulating HDL level, it increased the cholesterol efflux capacity of HDL, and it enhanced in vivo RCT from macrophages to the plasma, liver, and feces. Furthermore, ABCA1 degradation suppression by IMM-H007 reduced atherosclerotic plaque formation in apoE(-/-) mice. Thus, via effects on both ABCA1-expressing cells and circulating HDL function, the inhibition of ABCA1 protein degradation by IMM-H007 promotes HDL cholesterol efflux capacity and RCT and attenuates atherogenesis. IMM-H007 potentially represents a lead compound for the development of agents to augment HDL function.

Novel LDL-oriented pharmacotherapeutical strategies.

Elevated levels of low-density cholesterol (LDL-C) are highly correlated with increased risk of cardiovascular diseases (CVD). Thus, current guidelines have recommended progressively lower LDL-C for cholesterol treatment and CVD prevention as the primary goal of therapy. Even so, some patients in the high risk category fail to achieve recommended LDL-C targets with currently available medications. Thereby, additional pharmaceutical strategies are urgently required. In the review, we aim to provide an overview of both current and emerging LDL-C lowering drugs. As for current available LDL-C lowering agents, attentions are mainly focused on statins, niacin, bile acid sequestrants, ezetimibe, fibrates and omega-3 fatty acids. On the other hand, the emerging drugs differ from mechanisms are including: intervention of cholesterol biosynthesis downstream enzyme (squalene synthase inhibitors), inhibition of lipoprotein assembly (antisense mRNA inhibitors of apolipoprotein B and microsomal transfer protein inhibitors), enhanced lipoprotein clearance (proprotein convertase subtilisin kexin type 9, thyroid hormone analogues), inhibition of intestinal cholesterol absorption (Niemann-Pick C1-like 1 protein and acyl coenzyme A:cholesterol acyltransferase inhibitors) and interrupting enterohepatic circulation (apical sodium-dependent bile acid transporter inhibitors). Several ongoing agents are in their different stages of clinical trials, in expectation of promising antihyperlipidemic drugs. Therefore, alternative drugs monotherapy or in combination with statins will be sufficient to reduce LDL-C concentrations to optimal levels, and a new era for better LDL-C managements is plausible.

Antifatigue activity of the liposoluble fraction from Acanthopanax senticosus.

The crude extract of Acanthopanax senticosus (AS) has been used extensively in Russia, China, Korea and Japan as an adaptogenic agent to fight against stress and fatigue. However, whether the liposoluble fraction possesses antifatigue activity or not is still unclear. A liposoluble fraction was administered orally to mice for 9 days. The swimming time to exhaustion was longer in the treatment groups (22.2 ± 3.3, 25.5 ± 4.8 min) than in the control group (13.7 ± 1.2 min, p < 0.05). The plasma TG (triglyceride) and BUN (blood urea nitrogen) levels in the high dose (500 mg/kg) groups were decreased significantly compared with the control group. Plasma lactate dehydrogenase (LDH) was lower in the treatment groups than in the control group. Chemical analysis from GC/MS revealed that the main components of the liposoluble fraction of AS were saturated fatty acid (12.98%), unsaturated fatty acid (33.13%), unsaturated alcohol (27.46%) and diolefine (15.76%). In conclusion, the liposoluble fraction enhanced the forced swimming capacity of mice by decreasing muscle damage, effectively preventing the increase in BUN concentration and increasing fat utilization. It is proposed that the antioxidant effect may be one of the antifatigue mechanisms of the liposoluble fraction of AS.

The effect of Eleutheroside E on behavioral alterations in murine sleep deprivation stress model.

Eleutheroside E (EE), a principal component of Eleutherococcus senticosus, has been reported to have anti-inflammatory and protective effects in ischemia heart etc. However, whether it can mitigate behavioral alterations induced by sleep deprivation, has not yet been elucidated. Numerous studies have demonstrated that memory deficits induced by sleep deprivation in experimental animals can be used as a model of behavioral alterations. The present study investigated the effect of EE, on cognitive performances and biochemical parameters of sleep-deprived mice. Animals were repeatedly treated with saline, 10 or 50mg/kg EE and sleep-deprived for 72 h by the multiple platform method. Briefly, groups of 5-6 mice were placed in water tanks (45 × 34 × 17 cm), containing 12 platforms (3 cm in diameter) each, surrounded by water up to 1cm beneath the surface or kept in their home cage. After sleep deprivation, mice showed significant behavioral impairment as evident by reduced latency entering into a dark chamber, locomotion and correctly rate in Y maze, and increased monoamines in hippocampus. However, repeated treatment with EE restored these behavioral and biochemical alterations in mice. In conclusion, the beneficial effect of EE may provide an effective and powerful strategy to alleviate behavioral alterations induced by sleep deprivation.

Acanthopanax senticosus: review of botany, chemistry and pharmacology.

Acanthopanax senticosus (Rupr. et Maxim) Harms (Araliaceae), also called Siberian Ginseng, Eleutherococcus senticosus, and Ciwujia in Chinese, is a widely used traditional Chinese herb that could invigorate qi, strengthen the spleen, and nourish kidney in the theory of Traditional Chinese Medicine. With high medicinal value, Acanthopanax senticosus (AS, thereafter) is popularly used as an "adaptogen" like Panax ginseng. In recent decades, a great number of chemical, pharmacological, and clinical studies on AS have been carried out worldwide. Several kinds of chemical compounds have been reported, including triterpenoid saponins, lignans, coumarins, and flavones, among which, phenolic compounds such as syringin and eleutheroside E, were considered to be the most active components. Considerable pharmacological experiments both in vitro and in vivo have persuasively demonstrated that AS possessed anti-stress, antiulcer, anti-irradiation, anticancer, anti-inflammatory and hepatoprotective activities, etc. The present review is an up-to-date and comprehensive analysis of the botany, chemistry, pharmacology, toxicity and clinical trials of AS.

Bioactivity-guided fractionation for anti-fatigue property of Acanthopanax senticosus.

ETHNOPHARMACOLOGICAL RELEVANCE: The root of Acanthopanax senticosus (also called Eleutherococcus senticosus or Siberian ginseng) has been used extensively in China, Russia and Japan as an adaptogen to fight against stress and fatigue. AIM OF THE STUDY: The present study was designed to ascertain the anti-fatigue property of Acanthopanax senticosus by load-weighted swimming test, sleep deprivation test, also to isolate and characterize the active constituents. MATERIALS AND METHODS: Animals were orally administered with the extract of Acanthopanax senticosus. The anti-fatigue effects of the four fractions with different polarities from the 80% ethanol extract, and the different eluates collected from D101 macroporous resin chromatography and eleutheroside E, were examined based on the weight-loaded swimming capacity (physical fatigue) and the change of biochemical parameters in ICR mice. Moreover, the active fraction was later submitted to sleep-deprived mice (mental fatigue). RESULTS: The results shown that the n-butanol fraction significant extends the swimming time of mice to exhaustion. Furthermore, the 60% ethanol-water eluate, more purified eleutherosides (including eleutheroside E, E(2) and derivatives), were the exactly active constituents. Two compounds were isolated, which were identified as eleutheroside E, E(2). CONCLUSIONS: The eleutherosides possess the potent abilities to alleviate fatigue both in physical and mental fatigue. Eleutheroside E may be responsible for the pharmacological effect of anti-fatigue. Furthermore, the possible mechanisms were reduced the level of TG by increasing fat utilization, delayed the accumulation of blood urea nitrogen (BUN), and increased the LDH to reduce the accumulation of lactic acid in muscle and then protect the muscle tissue.