The role of peroxisome proliferator-activated receptor γ in lipid metabolism and inflammation in atherosclerosis.

Cardiovascular disease events are the result of functional and structural abnormalities in the arteries and heart. Atherosclerosis is the main cause and pathological basis of cardiovascular diseases. Atherosclerosis is a multifactorial disease associated with dyslipidemia, inflammation, and oxidative stress, among which dyslipidemia and chronic inflammation occur in all processes. Under the influence of lipoproteins, the arterial intima causes inflammation, necrosis, fibrosis, and calcification, leading to plaque formation in specific parts of the artery, which further develops into plaque rupture and secondary thrombosis. Foam cell formation from macrophages is an early event in the development of atherosclerosis. Lipid uptake causes a vascular inflammatory response, and persistent inflammatory infiltration in the lesion area further promotes the development of the disease. Inhibition of macrophage differentiation into foam cell and reduction of the level of proinflammatory factors in macrophages can effectively alleviate the occurrence and development of atherosclerosis. Peroxisome proliferator-activated receptor γ (PPARγ) is a ligand-activated nuclear receptor that plays an important antiatherosclerotic role by regulating triglyceride metabolism, lipid uptake, cholesterol efflux, macrophage polarity, and inhibiting inflammatory signaling pathways. In addition, PPARγ shifts its binding to ligands and co-activators or co-repressors of transcription of target genes through posttranslational modification, thereby affecting the regulation of its downstream target genes. Many ligand agonists have also been developed targeting PPARγ. In this review, we summarized the role of PPARγ in lipid metabolism and inflammation in development of atherosclerosis, the posttranslational regulatory mechanism of PPARγ, and further discusses the value of PPARγ as an antiatherosclerosis target.

Xylarianins A-D from the endophytic fungus Xylaria sp. SYPF 8246 as natural inhibitors of human carboxylesterase 2.

Eighteen secondary metabolites were isolated from the fermentation broth of the endophytic fungus Xylaria sp. SYPF 8246, including four new compounds, xylarianins A-D (1-4), three new natural products, 6-methoxycarbonyl-2'-methyl-3,5,4',6'-tetramethoxy-diphenyl ether (5), 2-chlor-6-methoxycarbonyl-2'-rnethyl-3,5,4',6'-tetramethoxy-diphenyl ether (6), and 2-chlor-4'-hydroxy-6-methoxy carbonyl-2'-methyl-3,5,6'-trimethoxy-diphenyl ether (7), and eleven known compounds (8-18). Their structural elucidations were conducted by using 1D and 2D NMR, HRESIMS, and Rh2(OCOCF3)4-induced electronic circular dichroism (ECD) spectra analyses. The integrated 1H and 13C NMR data of three new natural products 5-7 were reported for the first time. All the isolated compounds were assayed for their inhibitory activities against human carboxylesterase 2 (hCE 2). Compounds 1, 5-9, and 18 displayed significant inhibitory activities against hCE 2 with IC50 values of 10.43 ±â€¯0.51, 6.69 ±â€¯0.85, 12.36 ±â€¯1.27, 18.25 ±â€¯1.78, 29.78 ±â€¯0.48, 18.86 ±â€¯1.87, and 20.72 ±â€¯1.51 µM, respectively. The interactions between compounds 1 and 5 with hCE 2 were anaylzed by molecular docking.

Free radical scavenging activity and neuroprotective potentials of D138, one Cu(II)/Zn(II) Schiff-base complex derived from N,N'-bis(2-hydroxynaphthylmethylidene)-1,3-propanediamine.

There is increasing evidence that free radicals play an important role in neuronal damages induced by diabetes mellitus or cerebral ischemia insults. Antioxidants with free radical scavenging activities have been shown to be beneficial and neuroprotective for these pathological conditions. Here, we report free radical scavenging activity and neuroprotective potential of D138, one copper(II)/zinc(II) Schiff-base complex derived from N,N'-2(2-hydroxynaphthylmethylidene)-1,3-propanediamine. The data from three in vitro assays, 2,2-diphenyl-1-picrylhydrazyl assay, nitro blue tetrazolium assay and hydroxyl radical scavenging assay, indicated that D138 presented a potent free radical scavenging activity. The neuroprotective and antioxidative effects of D138 were further evaluated in vivo using bilateral common carotid artery occlusion (BCCAO) mouse model and streptozotocin (STZ) diabetic mouse model. Our results indicated that treatment of D138 significantly ameliorated the hippocampal neuronal damage and the oxidative stress levels in these animal models. Moreover, D138 also reversed the behavioral deficiencies induced by BCCAO or STZ, as assessed by Y-maze test and fear conditioning test. In conclusion, all these findings support that D138 exerts free radical scavenging and neuroprotective activities and has the potentials to be a potent therapeutic candidate for brain oxidative damage induced by cerebral ischemia or diabetes mellitus.

Effects of frog skin peptide temporin-1CEa and its analogs on ox-LDL induced macrophage-derived foam cells.

Purpose: Atherosclerosis is one of the most important pathological foundations of cardiovascular and cerebrovascular diseases with high morbidity and mortality. Studies have shown that macrophages play important roles in lipid accumulation in the vascular wall and thrombosis formation in atherosclerotic plaques. This study aimed to explore the effect of frog skin antimicrobial peptides (AMPs) temporin-1CEa and its analogs on ox-LDL induced macrophage-derived foam cells. Methods: CCK-8, ORO staining, and intracellular cholesterol measurements were used to study cellular activity, lipid droplet formation and cholesterol levels, respectively. ELISA, real-time quantitative PCR, Western blotting and flow cytometry analysis were used to study the expression of inflammatory factors, mRNA and proteins associated with ox-LDL uptake and cholesterol efflux in macrophage-derived foam cells, respectively. Furthermore, the effects of AMPs on inflammation signaling pathways were studied. Results: Frog skin AMPs could significantly increase the cell viability of the ox-LDL-induced foaming macrophages and decrease the formation of intracellular lipid droplets and the levels of total cholesterol and cholesterol ester (CE). Frog skin AMPs inhibited foaming formation by reducing the protein expression of CD36, which regulates ox-LDL uptake but had no effect on the expression of efflux proteins ATP binding cassette subfamily A/G member 1 (ABCA1/ABCG1). Then, decreased mRNA expression of NF-κB and protein expression of p-NF-κB p65, p-IκB, p-JNK, p-ERK, p-p38 and the release of TNF-α and IL-6 occurred after exposure to the three frog skin AMPs. Conclusion: Frog skin peptide temporin-1CEa and its analogs can improve the ox-LDL induced formation of macrophage-derived foam cells, in addition, inhibit inflammatory cytokine release through inhibiting the NF-κB and MAPK signaling pathways, thereby inhibiting inflammatory responses in atherosclerosis.

Jujuboside a promotes proliferation and neuronal differentiation of APPswe-overexpressing neural stem cells by activating Wnt/ß-catenin signaling pathway.

Mobilization of hippocampal neurogenesis has been considered as a potential strategy for the treatment of neurodegenerative diseases, including Alzheimer's disease (AD). In present study, we evaluated both the neuroprotective effects and the effects on the proliferation and differentiation of APP-overexpressing neural stem cells (APP-NSCs) by Jujuboside A (JuA) in vitro. Our results demonstrated that JuA (50 µM) decreased apoptosis and suppressed oxidative stress damage of APP-NSCs. JuA (50 µM) upregulated the secretion of brain-derived neurotrophic factor and promoted the proliferation and neuronal differentiation of APP-NSCs. Moreover, JuA (50 µM) upregulated Wnt-3a and ß-catenin protein expression, and enhanced the expression of downstream genes Ccnd1, Neurod1 and Prox1. However, XAV-939, an inhibitor of the Wnt/ß-catenin signaling pathway, inhibited these positive effects of JuA. Taken together, these findings suggest that JuA promote proliferation and neuronal differentiation of APP-NSCs partly by activating the Wnt/ß-catenin signaling pathway. We hope that this study will provide a viable strategy for the treatment of AD.

Antihyperglycemic and neuroprotective effects of one novel Cu-Zn SOD mimetic.

Increasing evidence supports that OS plays important roles in diabetes mellitus and cerebral ischemia. This suggests that recovering an impaired endogenous superoxide dismutase (SOD) enzyme system induced by OS with a mimetic would be beneficial and protective for these diseases. In present study, one nonpeptidyl small molecular weight compound (D34) was synthesized. Its SOD mimetic activity and the potential therapeutic actions were also evaluated both in vivo and in vitro. The in vitro nitro blue tetrazolium (NBT) assay indicated that D34 presents an SOD mimetic activity. D34 (20µmol/kg) exhibited significant antihyperglycemic activity in alloxan-diabetic mice. D34 could also ameliorate the cerebral neuronal death in hippocampus of global cerebral ischemia mice. Furthermore, the D34 treatment significantly decreased malondialdehyde (MDA) contents and increased SOD activities in brains or livers of diabetes mice or cerebral ischemic mice. In conclusion, these preliminary findings support that D34 exhibits SOD mimetic activity and possesses significant antihyperglycemic and neuroprotective effects.

Melanoma cell surface-expressed phosphatidylserine as a therapeutic target for cationic anticancer peptide, temporin-1CEa.

We have previously reported that temporin-1CEa, a cationic antimicrobial peptide, exerts preferential cytotoxicity toward cancer cells. However, the exact molecular mechanism for this cancer-selectivity is still largely unknown. Here, we found that the negatively charged phosphatidylserine (PS) expressed on cancer cell surface serves as a target for temporin-1CEa. Our results indicate that human A375 melanoma cells express 50-fold more PS than non-cancerous HaCaT cells. The expression of cell surface PS in various cancer cell lines closely correlated with their ability to be recognized, bound and killed by temporin-1CEa. Additionally, the cytotoxicity of temporin-1CEa against A375 cells can be ameliorated by annexin V, which binds to cell surface PS with high affinity. Moreover, the data of isothermal titration calorimetry assay further confirmed a direct binding of temporin-1CEa to PS, at a ratio of 1:5 (temporin-1CEa:PS). Interestingly, the circular dichroism spectra analysis using artificial biomembrane revealed that PS not only provides electrostatic attractive sites for temporin-1CEa but also confers the membrane-bound temporin-1CEa to form α-helical structure, therefore, enhances the affinity and membrane disrupting ability of temporin-1CEa. In summary, these findings suggested that the melanoma cells expressed PS may serve as a promising target for temporin-1CEa or other cationic anticancer peptides.

Design of potent, non-toxic anticancer peptides based on the structure of the antimicrobial peptide, temporin-1CEa.

Recent advances in the search for novel anticancer agents have indicated that the positively charged antimicrobial peptides have emerged as promising agents offering several advantages over the conventional anticancer drugs. As a naturally occurring, cationic, α-helical antimicrobial peptide, temproin-1CEa has been proved to exhibit a potent anticancer effect and a moderate hemolytic activity. In order to reduce the hemolytic activity of temporin-1CEa and improve its anticancer potency towards a range of human breast cancer cells, in the present study, six analogs of temporin-1CEa were rationally designed and synthesized. The amphipathicity levels and α-helical structural patterns of peptides were reserved, while their cationic property and hydrophobicity were changed. The results of MTT and hemolysis assay indicated that the analog peptides displayed an improved anticancer activity and showed an overall optimized therapeutic index. The hydrophobicity of peptides was positively correlated with their hemolytic and antitumor activities. Moreover, the data suggest a strategy of increasing the cationicity while maintaining the moderate hydrophobicity of naturally occurring amphipathic α-helical peptides to generate analogs with improved cytotoxicity against tumor cells but decreased activity against non-neoplastic cells such as human erythrocytes. This work highlights the potential for rational design and synthesis of improved antimicrobial peptides that have the capability to be used therapeutically for treatment of cancers.

Rapid cytotoxicity of antimicrobial peptide tempoprin-1CEa in breast cancer cells through membrane destruction and intracellular calcium mechanism.

Temporin-1CEa is an antimicrobial peptide isolated from the skin secretions of the Chinese brown frog (Rana chensinensis). We have previously reported the rapid and broad-spectrum anticancer activity of temporin-1CEa in vitro. However, the detailed mechanisms for temporin-1CEa-induced cancer cell death are still weakly understood. In the present study, the mechanisms of temporin-1CEa-induced rapid cytotoxicity on two human breast cancer cell lines, MDA-MB-231 and MCF-7, were investigated. The MTT assay and the LDH leakage assay indicated that one-hour of incubation with temporin-1CEa led to cytotoxicity in a dose-dependent manner. The morphological observation using electronic microscopes suggested that one-hour exposure of temporin-1CEa resulted in profound morphological changes in both MDA-MB-231 and MCF-7 cells. The membrane-disrupting property of temporin-1CEa was further characterized by induction of cell-surface exposure of phosphatidylserine, elevation of plasma membrane permeability and rapid depolarization of transmembrane potential. Moreover, temporin-1CEa evoked intracellular calcium ion and reactive oxygen species (ROS) elevations as well as collapse of mitochondrial membrane potential (Δφm). In summary, the present study indicates that temporin-1CEa triggers rapid cell death in breast cancer cells. This rapid cytotoxic activity might be mediated by both membrane destruction and intracellular calcium mechanism.

Antitumor effects and cell selectivity of temporin-1CEa, an antimicrobial peptide from the skin secretions of the Chinese brown frog (Rana chensinensis).

Many antimicrobial peptides from amphibian exhibit additional anticancer properties due to a similar mechanism of action at both bacterial and cancer cells. We have previously reported the cDNA sequence of the antimicrobial peptide temporin-1CEa precursor cloned from the Chinese brown frog Rana chensinensis. In this study, we purified, synthesized and structurally characterized temporin-1CEa from the skin secretions of R. chensinensis. The cytotoxicity and cell selectivity of temporin-1CEa were further examined on twelve human carcinoma cell lines and on normal human umbilical vein smooth muscle cells (HUVSMCs). Our results indicated that temporin-1CEa has the amino acid sequence of FVDLKKIANIINSIF-NH(2), and exhibits 50-56% identity with temporin family peptides from other frog species. The CD spectra for temporin-1CEa adopted a well-defined α-helical structure in 50% TFE/water solution. The results of MTT assay showed that temporin-1CEa exhibits cytotoxicity to all tested cancer cell lines in a concentration-dependent manner, being MCF-7 cells the most sensitive. Moreover, temporin-1CEa had lower hemolytic effect to human erythrocytes and had no significant cytotoxicity to normal HUVSMCs at concentrations showed potent antitumor activity. In summary, temporin-1CEa, an amphiphilic α-helical cationic peptide, may represent a novel anticancer agent for breast cancer therapy, considering its cancer cell selectivity and relatively lower cytotoxicity to normal cells.