Oxidized LDL upregulated ATP binding cassette transporter-1 in THP-1 macrophages

INTRODUCTIONOxidized lipid signaling in macrophages is centralto the pathogenesis of atherosclerosis[1]. Exposure ofmacrophages and other vascular cells to oxidized low-density lipoprotein (ox-LDL) leads to complex changesin gene expression that are collectively thought to influ-ence the development of the atherosclerotic lesion[2].Using two-dimensional gel electrophoresis, the overallprotein map in U937 control cells and U937 foam cellswas obtained. Compared with U937 cells, 37 spots…     

Ezetimibe reduces plaque inflammation in a rabbit model of atherosclerosis and inhibits monocyte migration in addition to its lipid-lowering effect

Background and purpose:

Ezetimibe, a selective inhibitor of intestinal cholesterol absorption, might also suppress inflammatory components of atherogenesis. We have studied the effects of ezetimibe on two characteristics of atherosclerotic plaques (infiltrate and fibrosis) and on expression of inflammatory genes in a rabbit model of accelerated atherosclerosis.

Experimental approach:

Femoral atherosclerosis was induced by a combination of endothelial desiccation and atherogenic diet. Animals were randomized to ezetimibe (0.6 mg·kg⁻¹·day⁻¹), simvastatin (5 mg·kg⁻¹·day⁻¹), ezetimibe plus simvastatin or no treatment, still on atherogenic diet. A control group of rabbits received normolipidemic diet.

Key results:

Rabbits fed the normolipidemic diet showed normal plasma lipid levels. Either the normolipidemic diet or drug treatment reduced the intima/media ratio (normolipidemic diet: 22%, ezetimibe: 13%, simvastatin: 27%, ezetimibe + simvastatin: 28%), compared with rabbits with atherosclerosis. Ezetimibe also decreased macrophage content and monocyte chemoattractant protein-1 expression in atherosclerotic lesions. Furthermore, ezetimibe reduced the increased activity of nuclear factor κB in peripheral blood leucocytes and plasma C-reactive protein levels in rabbits with atherosclerosis. In THP-1 cells, ezetimibe decreased monocyte chemoattractant protein-1-induced monocyte migration. Importantly, the combination of ezetimibe with simvastatin was associated with a more significant reduction in plaque monocyte/macrophage content and some proinflammatory markers than observed with each drug alone.

Conclusions and implications:

Ezetimibe had beneficial effects both on atherosclerosis progression and plaque stabilization and showed additional anti-atherogenic benefits when combined with simvastatin. Its effect on monocyte migration provides a potentially beneficial action, in addition to its effects on lipids.     

Binding Affinity and Capacity for the Uremic Toxin Indoxyl Sulfate

Protein binding prevents uremic toxins from removal by conventional extracorporeal therapies leading to accumulation in maintenance dialysis patients. Weakening of the protein binding may enhance the dialytic elimination of these toxins. In ultrafiltration and equilibrium dialysis experiments, different measures to modify the plasma binding affinity and capacity were tested: (i), increasing the sodium chloride (NaCl) concentration to achieve a higher ionic strength; (ii), increasing the temperature; and (iii), dilution. The effects on the dissociation constant K_D and the protein bound fraction of the prototypical uremic toxin indoxyl sulfate (IS) in plasma of healthy and uremic individuals were studied. Binding of IS corresponded to one site binding in normal plasma. K_D increased linearly with the NaCl concentration between 0.15 (K_D = 13.2 ± 3.7 µM) and 0.75 M (K_D = 56.2 ± 2.0 µM). Plasma dilution further reduced the protein bound toxin fraction by lowering the protein binding capacity of the plasma. Higher temperatures also decreased the protein bound fraction of IS in human plasma. Increasing the NaCl concentration was effective to weaken the binding of IS also in uremic plasma: the protein bound fraction decreased from 89% ± 3% to 81% ± 3% at 0.15 and 0.75 M NaCl, respectively. Dilution and increasing the ionic strength and temperature enhance the free fraction of IS allowing better removal of the substance during dialysis. Applied during clinical dialysis, this may have beneficial effects on the long-term outcome of maintenance dialysis patients.     

尼古丁对巨噬细胞肝X受体α表达及胆固醇外流的影响

目的通过研究尼古丁对巨噬细胞的肝X受体α(LXRα)及其下游的一些目的基因表达和胆固醇外流的影响,探讨尼古丁对LXR信号系统的作用。方法分离人外周血单核细胞,并转化为巨噬细胞。在尼古丁的作用下,观察巨噬细胞的aopA-Ⅰ介导的胆固醇外流的变化和LXR以及其下游一些目的基因mRNA表达。结果尼古丁明显影响巨噬细胞中一些涉及胆固醇代谢及炎症反应的基因表达,同时降低aopA-Ⅰ介导的胆固醇外流。结论巨噬细胞在尼古丁的作用下,由aopA-Ⅰ介导的胆固醇外流降低,这种效应与尼古丁下调LXRα及其下游的影响胆固醇代谢的目的基因有关,同时,也促进一些炎症因子基因的表达。提示尼古丁在动脉粥样硬化中的作用与其影响巨噬细胞LXR信号途径有关,从而影响泡沫细胞的形成。     

Atherosclerosis induced by chronic inhibition of the synthesis of nitric oxide in moderately hypercholesterolaemic rabbits is suppressed by pitavastatin

Background and purpose:

It is not clear if the new 3-hydroxyl-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor pitavastatin prevents atherogenesis by a direct effect. Statins have a cholesterol-lowering effect, so an accessible animal model of atherosclerosis showing only moderate hypercholesterolaemia as in humans, is needed. The effects of pitavastatin were evaluated on atherosclerotic lesions accumulating foam cells derived from macrophages, produced in rabbits with moderate hypercholesterolaemia by chronic inhibition of nitric oxide synthase (NOS).

Experimental approach:

White New Zealand rabbits were fed a 0.2% cholesterol diet with the NOS inhibitor N^ω-nitro-L-arginine methyl ester (L-NAME) in the same diet. Pitavastatin (0.1 and 0.3 mg·kg⁻¹) was given orally once a day for 8 weeks. The aortic arch and thoracic aorta were analysed by histochemistry and atherosclerotic lesions were quantified. The effect of pitavastatin on adhesion of THP-1 cells to endothelial cells, and cholesterol content in RAW264.7 cells incubated with oxidized or acetylated LDL were also investigated.

Key results:

Atherosclerotic lesions containing foam cells were induced in a model of atherosclerosis in rabbits with moderate hypercholesterolaemia by chronic inhibition of NOS. The area of atherosclerotic lesions was diminished by pitavastatin administration. The adhesion of THP-1 cells and cholesteryl ester content in RAW macrophages were decreased by pitavastatin treatment.

Conclusion:

Atherosclerosis induced by chronic inhibition of NOS in moderately hypercholesterolaemic rabbits was suppressed by pitavastatin via inhibition of macrophage accumulation and macrophage foam cell formation.     

Association of Sarcopenia and Gut Microbiota Composition in Older Patients with Advanced Chronic Kidney Disease,Investigation of the Interactions with Uremic Toxins,Inflammation and Oxidative Stress

Sarcopenia is a prevalent condition in chronic kidney disease (CKD). We determined gut microbiota (gMB) composition in CKD patients with or without sarcopenia. Furthermore, we investigated whether in these patients, there was any association between gMB, uremic toxins, inflammation and oxidative stress. We analyzed gMB composition, uremic toxins (indoxyl sulphate and p-cresyl sulphate), inflammatory cytokines (interleukin 10, tumor necrosis factor α, interleukin 6, interleukin 17, interleukin 12 p70, monocyte chemoattractant protein-1 and fetuin-A) and oxidative stress (malondialdehyde) of 64 elderly CKD patients (10 < eGFR < 45 mL/min/1.73 m², not on dialysis) categorized as sarcopenic and not-sarcopenic. Sarcopenia was defined according to European Working Group on Sarcopenia in Older People 2 criteria. Sarcopenic patients had a greater abundance of the Micrococcaceae and Verrucomicrobiaceae families and of Megasphaera, Rothia, Veillonella, Akkermansia and Coprobacillus genera. They had a lower abundance of the Gemellaceae and Veillonellaceae families and of Acidaminococcus and Gemella genera. GMB was associated with uremic toxins, inflammatory cytokines and MDA. However, uremic toxins, inflammatory cytokines and MDA were not different in sarcopenic compared with not-sarcopenic individuals, except for interleukin 10, which was higher in not-sarcopenic patients. In older CKD patients, gMB was different in sarcopenic than in not-sarcopenic ones. Several bacterial families and genera were associated with uremic toxins and inflammatory cytokines, although none of these latter substantially different in sarcopenic versus not-sarcopenic patients.     

The effect of T0901317 on ATP-binding cassette transporter A1 and Niemann-Pick type C1 in apoE-/- mice

Although a range of studies indicated Liver X receptor (LXR) activation inhibited the development of atherosclerosis in animal models, the mechanism of this effect for LXR agonists has not been fully understood. A recent study has suggested LXR activators increased the amount of free cholesterol in the plasma membrane of human macrophages by inducing Niemann-Pick type C1 (NPC1) gene expression. Therefore, we hypothesize that LXRs may also promote NPC1 expression in vivo. Here we investigated the effect of a synthetic LXR agonist T0901317 on ATP-binding cassette transporter A1 (ABCA1) and NPC1 in apolipoprotein E knockout (apoE-/-) mice. Male apoE-/- mice were randomized into four groups: baseline group (n = 10), vehicle group (n = 14), prevention group (n = 14), and treatment group (n = 14). En face analysis and Oil red O staining were used to examine the aortic atherosclerotic lesions. Macrophage content of aortic root atherosclerotic lesions and cholesterol efflux form peritoneal macrophages were measured. Gene and protein expression was analyzed by real-time quantitative polymerase chain reaction and Western blotting, respectively. T0901317 treatment reduced aortic atherosclerotic lesion area by 64.2% in prevention group (P < 0.001) and 58.3% in treatment group (P < 0.001) and resulted in a reduction in macrophage content. Plasma triglyceride, total cholesterol, high-density lipoprotein cholesterol, and apoA-I concentrations were markedly increased in T0901317-treated groups. T0901317 also promoted ABCA1 and NPC1 gene and protein levels in the aorta, liver, and small intestine of apoE-/- mice and significantly increased cholesterol efflux from peritoneal macrophages. T0901317 upregulates ABCA1 and NPC1. This study gives us a new insight into the mechanism for antiatherogenic effect of LXR synthetic agonists.     

Ibrolipim increases ABCA1/G1 expression by the LXRα signaling pathway in THP-1 macrophage-derived foam cells

Aim:

To determine the effects and potential mechanisms of ibrolipim on ATP-binding membrane cassette transporter A-1 (ABCA1) and ATP-binding membrane cassette transporter G-1 (ABCG1) expression from human macrophage foam cells, which may play a critical role in atherogenesis.

Methods:

Human THP-1 cells pre-incubated with ox-LDL served as foam cell models. Specific mRNA was quantified using real-time RT-PCR and protein expression using Western blotting. Cellular cholesterol handling was studied using cholesterol efflux experiments and high performance liquid chromatography assays.

Results:

Ibrolipim 5 and 50 μmol/L significantly increased cholesterol efflux from THP-1 macrophage-derived foam cells to apoA-I or HDL. Moreover, it upregulated the expression of ABCA1 and ABCG1. In addition, LXRα was also upregulated by the ibrolipim treatment. In addition, LXRα small interfering RNA completely abolished the promotion effect that was induced by ibrolipim.

Conclusion:

Ibrolipim increased ABCA1 and ABCG1 expression and promoted cholesterol efflux, which was mediated by the LXRα signaling pathway.     

Mechanism of allergic rhinitis treated by Centipeda minima from different geographic areas

ContextThe coriander plant Centipeda minima (L.) A. Braun et Aschers (Compositae) is used for the treatment of allergic rhinitis.ObjectiveAnalyze the difference of the C. minima volatile oil from 7 geographic areas and its therapeutic effect on allergic rhinitis.Materials and methodsThe volatile oils from different geographic areas were extracted and analyzed, the protein and biological pathway for the treatment of allergic rhinitis were predicted by network pharmacology. Established three groups of Sprague-Dawley rat allergic rhinitis models (n = 10). The treatment group was given 100 μL/nostril of 0.1% C. minima volatile oil, the blank and model groups were given the same amount of normal saline. After 15 days, serum inflammatory factors were detected by ELISA. Nasal mucosa tissues were examined by hematoxylineosin staining and immunuhistrochemistry.ResultsThere are differences in the content of volatile oil in the seven geographic areas. Experiments showed that the concentration of TNF-α in the serum of the administration group decreased from 63.66 ± 2.06 to 51.01 ± 4.10 (pg/mL), IL-4 decreased from 41.90 ± 3.90 to 28.68 ± 3.39 (pg/mL), IgE decreased from 22.18 ± 1.40 to 17.59 ± 1.60 (pg/mL), IL-2 increased from 314.14 ± 10.32 to 355.90 ± 10.01(pg/mL). Immunohistochemistry showed that compared with the model group, the PTGS2 and MAPK3 proteins in the administration group were significantly reduced.Discussion and conclusionsC. minima volatile oil is a multi-target and multi-pathway in the treatment of allergic rhinitis, which provides a new research basis and reference for the treatment of allergic rhinitis.     

Combination of virtual screening and high throughput gene profiling for identification of novel liver X receptor modulators

We conducted virtual docking studies using GLIDE with modified LXRbeta ligand-binding domain (LBD) on internal compound collection followed by the gene profiling with ArrayPlate mRNA assay. A total of 69 compounds were found to upregulate LXRalpha and certain LXR regulated genes from 1308 compounds selected by virtual screen (hit rate: 5.3%). Compound 4 was shown to significantly induce the expression of LXR target genes such as ABCA1, ABCG1, APOE, SCD-1, and SREBP-1c in THP-1 differentiated macrophages. In vitro binding assay confirmed that 4 binds to both LXRalpha and LXRbeta directly and recruits coactivator peptide SRC-1. It functions as a full LXR agonist in stimulating cholesterol efflux in THP-1 differentiated macrophages and induces lipogenesis in HepG2 cells. This study demonstrates that the combination of virtual screen and high throughput gene profiling is an efficient approach for rapid identification of novel LXR modulators.     

Haloperidol inhibits the development of atherosclerotic lesions in LDL receptor knockout mice

Background and Purpose

Antipsychotic drugs have been shown to modulate the expression of ATP-binding cassette transporter A1 (ABCA1), a key factor in the anti-atherogenic reverse cholesterol transport process, in vitro. Here we evaluated the potential of the typical antipsychotic drug haloperidol to modulate the cholesterol efflux function of macrophages in vitro and their susceptibility to atherosclerosis in vivo.

Experimental Approach

Thioglycollate-elicited peritoneal macrophages were used for in vitro studies. Hyperlipidaemic low-density lipoprotein (LDL) receptor knockout mice were implanted with a haloperidol-containing pellet and subsequently fed a Western-type diet for 5 weeks to induce the development of atherosclerotic lesions in vivo.

Key Results

Haloperidol induced a 54% decrease in the mRNA expression of ABCA1 in peritoneal macrophages. This coincided with a 30% decrease in the capacity of macrophages to efflux cholesterol to apolipoprotein A1. Haloperidol treatment stimulated the expression of ABCA1 (+51%) and other genes involved in reverse cholesterol transport, that is, CYP7A1 (+98%) in livers of LDL receptor knockout mice. No change in splenic ABCA1 expression was noted. However, the average size of the atherosclerotic size was significantly smaller (−31%) in the context of a mildly more atherogenic metabolic phenotype upon haloperidol treatment. More importantly, haloperidol markedly lowered MCP-1 expression (−70%) and secretion (−28%) by peritoneal macrophages.

Conclusions and Implications

Haloperidol treatment lowered the susceptibility of hyperlipidaemic LDL receptor knockout mice to develop atherosclerotic lesions. Our findings suggest that the beneficial effect of haloperidol on atherosclerosis susceptibility can be attributed to its ability to inhibit macrophage chemotaxis.     

P2Y receptors and atherosclerosis in apolipoprotein E-deficient mice

Background and purpose:

P2Y nucleotide receptors are involved in the regulation of vascular tone, smooth muscle cell (SMC) proliferation and inflammatory responses. The present study investigated whether they are involved in atherosclerosis.

Experimental approach:

mRNA of P2Y receptors was quantified (RT-PCR) in atherosclerotic and plaque-free aorta segments of apolipoprotein E-deficient (apoE^–/–) mice. Macrophage activation was assessed in J774 macrophages, and effects of non-selective purinoceptor antagonists on atherosclerosis were evaluated in cholesterol-fed apoE^–/– mice.

Key results:

P2Y₆ receptor mRNA was consistently elevated in segments with atherosclerosis, whereas P2Y₂ receptor expression remained unchanged. Expression of P2Y₁ or P2Y₄ receptor mRNA was low or undetectable, and not influenced by atherosclerosis. P2Y₆ mRNA expression was higher in cultured J774 macrophages than in cultured aortic SMCs. Furthermore, immunohistochemical staining of plaques demonstrated P2Y₆-positive macrophages, but few SMCs, suggesting that macrophage recruitment accounted for the increase in P2Y₆ receptor mRNA during atherosclerosis. In contrast to ATP, the P2Y₆-selective agonist UDP increased mRNA expression and activity of inducible nitric oxide synthase and interleukin-6 in J774 macrophages; this effect was blocked by suramin (100–300 µM) or pyridoxal-phosphate-6-azophenyl-2′-4′-disulphonic acid (PPADS, 10–30 µM). Finally, 4-week treatment of cholesterol-fed apoE^–/– mice with suramin or PPADS (50 and 25 mg·kg⁻¹·day⁻¹ respectively) reduced plaque size, without changing plaque composition (relative SMC and macrophage content) or cell replication.

Conclusions and implications:

These results suggest involvement of nucleotide receptors, particularly P2Y₆ receptors, during atherosclerosis, and warrant further research with selective purinoceptor antagonists or P2Y₆ receptor-deficient mice.     

Gynura procumbens ethanol extract improves vascular dysfunction by suppressing inflammation in postmenopausal rats fed a high-fat diet

ContextGynura procumbens (Lour.) Merr. (Asteraceae) has been reported to have various pharmacological activities including anti-inflammatory effects.ObjectiveThis study sought to determine whether Gynura procumbens (GP) could improve vascular reactivity by suppressing inflammation in postmenopausal rats fed with five-times heated palm oil (5HPO) diet.Materials and methodsForty-eight female Sprague-Dawley rats were randomly divided into sham [non-ovariectomized; grouped as control, GP extracts (250 and 500 mg/kg), atorvastatin (ATV, 10 mg/kg)] and postmenopausal (PM) groups [ovariectomized rats fed with 5HPO; grouped as PM, GP extracts (250 and 500 mg/kg) and ATV (10 mg/kg)]. Each group (n = 6) was either supplemented with GP extract or ATV orally once daily for 6 months.ResultsIn comparison with the untreated PM group, 250 and 500 mg/kg GP supplementation to PM groups reduced the systolic blood pressure (103 ± 2.7, 86 ± 2.4 vs. 156 ± 7.83 mmHg, p < 0.05), intima-media thickness (101.28 ± 3.4, 93.91 ± 2.93 vs. 143.78 ± 3.31 µM), vasoconstriction percentage induced by phenylephrine (102.5%, 88.3%, vs. 51.8%), sICAM-1 (0.49, 0.26 vs. 0.56 pg/mL) and sVCAM-1 (0.39, 0.25 vs. 0.45 pg/mL). GP extract supplementation increased vasorelaxation percentage induced by acetylcholine (78.4% vs. 47.3%) and sodium nitroprusside (84.2% vs. 53.7%), increased changes in plasma nitric oxide level (1.25%, 1.31% vs. 1.9%), and suppressed the elevation of TNF-α (0.39 vs. 1.02 pg/mL), IL-6 (0.43 vs. 0.77 pg/mL) and CRP (0.29 vs. 0.69 ng/mL) in the PM groups.ConclusionsGP extract might improve vascular dysfunction by suppressing the inflammatory response, consequently preventing blood pressure elevation.     

Isovitexin alleviates acute gouty arthritis in rats by inhibiting inflammation via the TLR4/MyD88/NF-κB pathway

ContextThe prevalence of gout has greatly increased, and it has become the most common inflammatory arthritis in men. Isovitexin possesses anti-inflammatory and antioxidant properties.ObjectiveWe explored the effects of isovitexin on rats with acute gouty arthritis (GA).Materials and methodsFifty-four Sprague-Dawley rats were assigned to five groups: sham, model, positive (colchicine, 0.3 mg/kg), isovitexin (100 mg/kg), TLR4 inhibitor (TAK-242, 3 mg/kg) and isovitexin + TAK-242. The gait of rats and the ankle joint swelling index were monitored. The levels of tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and IL-6, and pathological changes in the synovial tissues were determined.ResultsIsovitexin significantly reduced the ankle joint swelling index at day 7 compared to that in the model group (4.39 ± 1.01 vs. 6.09 ± 1.31). Moreover, isovitexin alleviated the infiltration of inflammatory cells and ameliorated the proliferation of synovial cells. The levels of TNF-α (93.42 ± 5.02 pg/mL), IL-1β (25.46 ± 1.91 pg/mL) and IL-6 (194.71 ± 7.92 pg/mL) in the isovitexin group were significantly lower than in the model group (129.39 ± 5.43, 39.60 ± 2.71 and 223.77 ± 5.35 pg/mL). The expression of TLR4, MyD88 and p-NF-κB-p65 was remarkably decreased after isovitexin and colchicine treatment. The effect of isovitexin was similar to that colchicine. Furthermore, the combination of isovitexin and TAK-242 had better effect, and there was no significantly difference with colchicine treatment.Discussion and conclusionsIsovitexin ameliorates joint inflammation in acute GA via the TLR4/MyD88/NF-κB pathway. Isovitexin may be a potential substitute medicine for GA.     

Flavocoxid,a dual inhibitor of cyclooxygenase and 5-lipoxygenase,blunts pro-inflammatory phenotype activation in endotoxin-stimulated macrophages

Background and purpose:

The flavonoids, baicalin and catechin, from Scutellaria baicalensis and Acacia catechu, respectively, have been used for various clinical applications. Flavocoxid is a mixed extract containing baicalin and catechin, and acts as a dual inhibitor of cyclooxygenase (COX) and 5-lipoxygenase (LOX) enzymes. The anti-inflammatory activity, measured by protein and gene expression of inflammatory markers, of flavocoxid in rat peritoneal macrophages stimulated with Salmonella enteritidis lipopolysaccharide (LPS) was investigated.

Experimental approach:

LPS-stimulated (1 µg·mL⁻¹) peritoneal rat macrophages were co-incubated with different concentrations of flavocoxid (32–128 µg·mL⁻¹) or RPMI medium for different incubation times. Inducible COX-2, 5-LOX, inducible nitric oxide synthase (iNOS) and inhibitory protein κB-α (IκB-α) levels were evaluated by Western blot analysis. Nuclear factor κB (NF-κB) binding activity was investigated by electrophoretic mobility shift assay. Tumour necrosis factor-α (TNF-α) gene and protein expression were measured by real-time polymerase chain reaction and enzyme-linked immunosorbent assay respectively. Finally, malondialdehyde (MDA) and nitrite levels in macrophage supernatants were evaluated.

Key results:

LPS stimulation induced a pro-inflammatory phenotype in rat peritoneal macrophages. Flavocoxid (128 µg·mL⁻¹) significantly inhibited COX-2 (LPS = 18 ± 2.1; flavocoxid = 3.8 ± 0.9 integrated intensity), 5-LOX (LPS = 20 ± 3.8; flavocoxid = 3.1 ± 0.8 integrated intensity) and iNOS expression (LPS = 15 ± 1.1; flavocoxid = 4.1 ± 0.4 integrated intensity), but did not modify COX-1 expression. PGE₂ and LTB₄ levels in culture supernatants were consequently decreased. Flavocoxid also prevented the loss of IκB-α protein (LPS = 1.9 ± 0.2; flavocoxid = 7.2 ± 1.6 integrated intensity), blunted increased NF-κB binding activity (LPS = 9.2 ± 2; flavocoxid = 2.4 ± 0.7 integrated intensity) and the enhanced TNF-α mRNA levels (LPS = 8 ± 0.9; flavocoxid = 1.9 ± 0.8 n-fold/β-actin) induced by LPS. Finally, flavocoxid decreased MDA, TNF and nitrite levels from LPS-stimulated macrophages.

Conclusion and implications:

Flavocoxid might be useful as a potential anti-inflammatory agent, acting at the level of gene and protein expression.     

Selective activation of liver X receptors by acanthoic acid-related diterpenes

Terpenoids constitute a large family of natural steroids that are widely distributed in plants and insects. We investigated the effects of a series of diterpenes structurally related to acanthoic acid in macrophage functions. We found that diterpenes with different substitutions at the C4 position in ring A are potent activators of liver X receptors (LXRalpha and LXRbeta) in both macrophage cell lines from human and mouse origin and primary murine macrophages. Activation of LXR by these diterpenes was evaluated in transient transfection assays and gene expression analysis of known LXR-target genes, including the cholesterol transporters ABCA1 and ABCG1, the sterol regulatory element-binding protein 1c, and the apoptosis inhibitor of macrophages (Spalpha). Moreover, active diterpenes greatly stimulated cholesterol efflux from macrophages. It is interesting that these diterpenes antagonize inflammatory gene expression mainly through LXR-dependent mechanisms, indicating that these compounds can activate both LXR activation and repression functions. Stimulation of macrophages with acanthoic acid diterpenes induced LXR-target gene expression and cholesterol efflux to similar levels observed with synthetic agonists 3-[3-[N-(2-chloro-3-trifluoromethylbenzyl)-(2,2-diphenylethyl)-amino]propyloxy]phenylacetic acid hydrochloride (GW3965) and N-(2,2,2-trifluoroethyl)-N-[4-[2,2,2-trifluoro-1-hydroxy-1-(trifluoromethyl)-ethyl]phenyl]-benzenesulfonamide [T1317 (T0901317)]. These effects observed in gene expression were deficient in macrophages lacking both LXR isoforms (LXRalpha,beta(-/-)). These results show the ability of certain acanthoic acid diterpenes to activate efficiently both LXRs and suggest that these compounds can exert beneficial effects from a cardiovascular standpoint through LXR-dependent mechanisms.     

Schizandrin A ameliorates cognitive functions via modulating microglial polarisation in Alzheimer’s disease mice

ContextSchizandrin A (Sch A) is a major phytochemical from Schisandra chinensis (Turcz.) Baill. (Schisandraceae), which exerts a neuroprotective effect in Alzheimer''s disease (AD).ObjectiveTo investigate the mechanism of Sch A in AD.Materials and methodsAD group: APP/PS1 transgenic mice served as AD models; AD + SCH group: APP/PS1 received 2 mg/kg Sch A by intragastric administration; WT: C57BL/6 mice were used as control. For in vitro assay, mouse microglial BV2 cells were treated with 0.5 µg/mL lipopolysaccharide or combined with 10 μmol/L Sch A for 24 h. The cognitive function and apoptosis in the mice was estimated. Microglial polarisation in the mice and cells was analysed.ResultsSch A treatment effectively improved spatial learning and memory ability and suppressed apoptosis in the brain tissues of APP/PS1 mice. APP/PS1 mice exhibited an increase in the levels of Aβ1-42 (2367.9 ± 431.1 pg/mg) and Aβ1-40 (1753.3 ± 253.4 pg/mg), which was abolished by Sch A treatment. Moreover, Sch A treatment repressed the proportions of iNOS⁺/Iba-1⁺ cells and IL-6 expression, while enhanced the proportions of Arg-1⁺/Iba-1⁺ cells and IL-10 expression in APP/PS1 mice. In vitro, Sch A treatment reduced the proportions of CD16/32⁺ cells, iNOS expression and IL-6 levels (25.7 ± 5.3 pg/mL) repressed M1 polarisation, and enhanced the proportions of CD206 cells, Arg-1 expression and IL-10 levels (75.9 ± 12.8 pg/mL) in BV2 cells.ConclusionsThis research confirms the neuroprotective effect of Sch A in AD, suggesting that Sch A may become a potential anti-AD agent.     

Taxifolin,a novel food,attenuates acute alcohol-induced liver injury in mice through regulating the NF-κB-mediated inflammation and PI3K/Akt signalling pathways

ContextTaxifolin (TAX) has effective anti-inflammatory, antioxidant and hepatoprotective activities, but its potential mechanism has not been revealed.ObjectiveTo evaluate the potential protective effect of TAX on acute alcohol-induced liver injury in mice.Materials and methodsAlcoholic liver injury model was established by oral alcohol in mice, and randomly distributed in five groups (n = 10): Normal group (oral saline only); Alcohol group (concentration of fermented alcohol: 56%, 6 mL/kg); TAX groups, mice were orally administered with alcohol, and then TAX with doses of 20, 40, 80 mg/kg, respectively. Oral administration was conducted for 6 weeks.ResultsTAX treatment illustrated that the level of alanine aminotransferase (ALT) was reduced to 65.90 ± 2.26 U/L and aspartate aminotransferase (AST) to 33.28 ± 5.62 U/L compared with alcohol group (ALT 124.51 ± 4.40 U/L, AST 61.70 ± 4.09 U/L), while superoxide dismutase (SOD) was increased to 49.81 ± 2.39 U/mg and glutathione (GSH) to 8.16 ± 0.44 μmol/g, but MDA was reversed to 2.53 ± 0.24 nmol/mg. Histopathological examination showed TAX treatment alleviated alcohol-induced hepatocyte necrosis and inflammatory infiltration. Meanwhile, Western blot and rt-PCR indicated TAX reduced IL-6 to 2.49 ± 0.25 pg/mL and TNF-α to 1.79 ± 0.20 pg/mL, and inhibiting NF-κB activation in liver. Moreover, TAX reversed alcohol-induced apoptosis by regulating the expression of PI3K/Akt and its downstream apoptotic factors.ConclusionsThe research provides novel evidence of the hepatoprotective effect of TAX on alcohol-induced liver injury, while also providing the possibility for future treatment of alcoholic liver disease.