Nutritional contributions to dementia prevention: main issues on antioxidant micronutrients

There is an impressing body of evidence supporting the beneficial role of balanced nutrition in lowering the risk of dementia and its commonest form, Alzheimer’s disease. Nevertheless, and despite worldwide dementia epidemic, there is much unfounded skepticism and lack of information among physicians. As a result, the diagnosis of cognitive impairment occurs still far too late, at best symptomatic drugs keep being prescribed and patients and caregivers are left with little concrete support in the hands of the natural history of the disease. This review summarizes knowledge about the impact of nutrition as part of a healthy lifestyle and of micronutrients in particular on delaying and avoiding dementia onset.     

Arsenite and arsenate impact the oxidative status and antioxidant responses in Ocimum tenuiflorum L

Physiology and Molecular Biology of Plants - Biochemical responses of Ocimum tenuiflorum plants were studied upon exposure to arsenite (AsIII) and arsenate (AsV) for 1 to 10 d. Plants...     

Donepezil attenuates high glucose-accelerated senescence in human umbilical vein endothelial cells through SIRT1 activation

Cellular senescence of endothelial cells is a damage and stress response which induces pro-inflammatory, pro-atherosclerotic, and pro-thrombotic phenotypes. Donepezil is a drug used for the treatment of mild to moderate dementia of the Alzheimer’s disease (AD). The aim of the present study was to investigate the attenuation of endothelial cell senescence by donepezil and to explore the mechanisms underlying the anti-aging effects of donepezil. Our results indicated that high glucose (HG) markedly decreased cell viability of human umbilical vein endothelial cells (HUVECs), and this phenomenon was reversed by treatment with donepezil. Importantly, our results displayed that the frequency of senescent (SA-ß-gal-positive) cells and the expression level of senescence genes (PAI-1 and p21) were significantly higher in the HG group compared with the normal glucose (NG) group, and these changes were blocked by treatment with donepezil. Also, our results showed that donepezil inhibits the generation of reactive oxygen species (ROS), which promotes cellular senescence. Pretreatment with nicotinamide (NAM), a sirtuin 1 (SIRT1) inhibitor, inhibited the reduction in senescence associated with donepezil. Indeed, our results indicated that donepezil increased the SIRT1 enzyme activity. Therefore, these results show that donepezil delays cellular senescence that is promoted under HG condition via activation of SIRT1.     

Isoform-Specific Effects of Apolipoprotein E on Markers of Inflammation and Toxicity in Brain Glia and Neuronal Cells In Vitro

Mutations to the cholesterol transport protein apolipoprotein E (ApoE) have been identified as a major risk factor for the development of sporadic or late-onset Alzheimer’s disease (AD), with the e4 allele representing an increased risk and the rare e2 allele having a reduced risk compared to the primary e3 form. The reasons behind the change in risk are not entirely understood, though ApoE4 has been connected to inflammation and toxicity in both the brain and the periphery. The goal of this study was to better understand how the ApoE isoforms (ApoE2/3/4) confer differential AD-related risk by assessing cell-specific ApoE-related neuroinflammatory and neurotoxic effects. We compared the effects of ApoE isoforms in vitro on human astrocytes, a human immortalized microglia cell line (HMC3), and the human neuroblastoma cell line SH-SY5Y. Cells were treated for 24 h with or without recombinant ApoE2, ApoE3, or ApoE4 (20 nM) and inflammation and toxicity markers assessed. Our results indicated the expression of inflammatory cytokines IL-1β, TNFα, and IL-6 in human astrocytes was increased in response to all ApoE isoforms, with ApoE4 evoking the highest level of cytokine expression. In response to ApoE2 or ApoE3, microglial cells showed reduced levels of microglial activation markers TREM2 and Clec7a, while ApoE4 induced increased levels of both markers. ApoE2 promoted neuron survival through increased BDNF release from astrocytes. In addition, ApoE2 promoted, while ApoE4 reduced, neuronal viability. Overall, these results suggest that ApoE4 acts on cells in the brain to promote inflammation and neuronal injury and that the deleterious effects of ApoE4 on these cells may, in part, contribute to its role as a risk factor for AD.     

Oxidative stress induces distinct physiological responses in the two Trebouxia phycobionts of the lichen Ramalina farinacea

Background and Aims

Most lichens form associations with Trebouxia phycobionts and some of them simultaneously include genetically different algal lineages. In other symbiotic systems involving algae (e.g. reef corals), the relative abundances of different endosymbiotic algal clades may change over time. This process seems to provide a mechanism allowing the organism to respond to environmental stress. A similar mechanism may operate in lichens with more than one algal lineage, likewise protecting them against environmental stresses. Here, the physiological responses to oxidative stress of two distinct Trebouxia phycobionts (provisionally named TR1 and TR9) that coexist within the lichen Ramalina farinacea were analysed.

Methods

Isolated phycobionts were exposed to oxidative stress through the reactive oxygen species propagator cumene hydroperoxide (CuHP). Photosynthetic pigments and proteins, photosynthesis (through modulated chlorophyll fluorescence), the antioxidant enzymes superoxide dismutase (SOD) and glutathione reductase (GR), and the stress-related protein HSP70 were analysed.

Key Results

Photosynthetic performance was severely impaired by CuHP in phycobionts, as indicated by decreases in the maximal PSII photochemical efficiency (F_v/F_m), the quantum efficiency of PSII (Φ_PSII) and the non-photochemical dissipation of energy (NPQ). However, the CuHP-dependent decay in photosynthesis was significantly more severe in TR1, which also showed a lower NPQ and a reduced ability to preserve chlorophyll a, carotenoids and D1 protein. Additionally, differences were observed in the capacities of the two phycobionts to modulate antioxidant activities and HPS70 levels when exposed to oxidative stress. In TR1, CuHP significantly diminished HSP70 and GR but did not change SOD activities. In contrast, in TR9 the levels of both antioxidant enzymes and those of HSP70 increased in response to CuHP.

Conclusions

The better physiological performance of TR9 under oxidative conditions may reflect its greater capacity to undertake key metabolic adjustments, including increased non-photochemical quenching, higher antioxidant protection and the induction of repair mechanisms.     

Shp2 signaling suppresses senescence in PyMT-induced mammary gland cancer in mice

In this study, we have used techniques from cell biology, biochemistry, and genetics to investigate the role of the tyrosine phosphatase Shp2 in tumor cells of MMTV-PyMT mouse mammary glands. Genetic ablation or pharmacological inhibition of Shp2 induces senescence, as determined by the activation of senescence-associated β-gal (SA-β-gal), cyclin-dependent kinase inhibitor 1B (p27), p53, and histone 3 trimethylated lysine 9 (H3K9me3). Senescence induction leads to the inhibition of self-renewal of tumor cells and blockage of tumor formation and growth. A signaling cascade was identified that acts downstream of Shp2 to counter senescence: Src, focal adhesion kinase, and Map kinase inhibit senescence by activating the expression of S-phase kinase-associated protein 2 (Skp2), Aurora kinase A (Aurka), and the Notch ligand Delta-like 1 (Dll1), which block p27 and p53. Remarkably, the expression of Shp2 and of selected target genes predicts human breast cancer outcome. We conclude that therapies, which rely on senescence induction by inhibiting Shp2 or controlling its target gene products, may be useful in blocking breast cancer.     

Cudrania cochinchinensis attenuates amyloid β protein-mediated microglial activation and promotes glia-related clearance of amyloid β protein

Background

Microglial inflammation may significantly contribute to the pathology of Alzheimer’s disease. To examine the potential of Cudrania cochinchinensis to ameliorate amyloid β protein (Aβ)-induced microglia activation, BV-2 microglial cell line, and the ramified microglia in the primary glial mixed cultured were employed.

Results

Lipopolysaccharide (LPS), Interferon-γ (IFN-γ), fibrillary Aβ (fAβ), or oligomeric Aβ (oAβ) were used to activate microglia. LPS and IFN-γ, but not Aβs, activated BV-2 cells to produce nitric oxide through an increase in inducible nitric oxide synthase (iNOS) expression without significant effects on cell viability of microglia. fAβ, but not oAβ, enhanced the IFN-γ-stimulated nitric oxide production and iNOS expression.The ethanol/water extracts of Cudrania cochinchinensis (CC-EW) and the purified isolated components (i.e. CCA to CCF) effectively reduced the nitric oxide production and iNOS expression stimulated by IFN-γ combined with fAβ. On the other hand, oAβ effectively activated the ramified microglia in mixed glial culture by observing the morphological alteration of the microglia from ramified to amoeboid. CC-EW and CCB effectively prohibit the Aβ-mediated morphological change of microglia. Furthermore, CC-EW and CCB effectively decreased Aβ deposition and remained Aβ in the conditioned medium suggesting the effect of CC-EW and CCB on promoting Aβ clearance. Results are expressed as mean ± S.D. and were analyzed by ANOVA with post-hoc multiple comparisons with a Bonferroni test.

Conclusions

The components of Cudrania cochinchinensis including CC-EW and CCB are potential for novel therapeutic intervention for Alzheimer’s disease.     

A comparison of metrics for estimating phylogenetic signal under alternative evolutionary models

Several metrics have been developed for estimating phylogenetic signal in comparative data. These may be important both in guiding future studies on correlated evolution and for inferring broad-scale evolutionary and ecological processes (e.g., phylogenetic niche conservatism). Notwithstanding, the validity of some of these metrics is under debate, especially after the development of more sophisticated model-based approaches that estimate departure from particular evolutionary models (i.e., Brownian motion). Here, two of these model-based metrics (Blomberg’s K-statistics and Pagel’s λ) are compared with three statistical approaches [Moran’s I autocorrelation coefficient, coefficients of determination from the autoregressive method (ARM), and phylogenetic eigenvector regression (PVR)]. Based on simulations of a trait evolving under Brownian motion for a phylogeny with 209 species, we showed that all metrics are strongly, although non-linearly, correlated to each other. Our analyses revealed that statistical approaches provide valid results and may be still particularly useful when detailed phylogenies are unavailable or when trait variation among species is difficult to describe by more standard Brownian or O-U evolutionary models.     

S. choloroleuca, S. mirzayanii and S. santolinifolia protect PC12 cells from H(2)O (2)-induced apoptosis by blocking the intrinsic pathway

Several studies have shown that neuronal cell death due to apoptosis is the major reason for cognitive decline in Alzheimer's disease. In this study, we report the anti-apoptotic effects of three Salvia species from Iran-S. choloroleuca, S. mirzayanii and S. santolinifolia-against H(2)O(2)-induced cytotoxicity in neuron-like PC12 cells. We showed that these antioxidant species could interfere with the intrinsic pathway of apoptosis by attenuating Bax/Bcl-2 ratio, decreasing outer mitochondrial membrane break and decreasing cytochrome c release to cytoplasm. Interestingly, we found that these species were able to replenish reduced glutathione level which affects cellular redox status and cytochrome c activity. Moreover, the decreased level of caspase-3, the executioner caspase, resulted in decrease of PARP-1 cleavage. Anti-apoptotic effects of these species along with their antioxidant effects, may represent a promising approach for treatment of neurodegenerative diseases.     

PIP2 depletion and altered endocytosis caused by expression of Alzheimer's disease‐protective variant PLCγ2 R522

Variants identified in genome‐wide association studies have implicated immune pathways in the development of Alzheimer’s disease (AD). Here, we investigated the mechanistic basis for protection from AD associated with PLCγ2 R522, a rare coding variant of the PLCG2 gene. We studied the variant''s role in macrophages and microglia of newly generated PLCG2‐R522‐expressing human induced pluripotent cell lines (hiPSC) and knockin mice, which exhibit normal endogenous PLCG2 expression. In all models, cells expressing the R522 mutation show a consistent non‐redundant hyperfunctionality in the context of normal expression of other PLC isoforms. This manifests as enhanced release of cellular calcium ion stores in response to physiologically relevant stimuli like Fc‐receptor ligation or exposure to Aβ oligomers. Expression of the PLCγ2‐R522 variant resulted in increased stimulus‐dependent PIP₂ depletion and reduced basal PIP₂ levels in vivo. Furthermore, it was associated with impaired phagocytosis and enhanced endocytosis. PLCγ2 acts downstream of other AD‐related factors, such as TREM2 and CSF1R, and alterations in its activity directly impact cell function. The inherent druggability of enzymes such as PLCγ2 raises the prospect of PLCγ2 manipulation as a future therapeutic approach in AD.     

Structure–activity relationship,in vitro and in vivo evaluation of novel dienyl sulphonyl fluorides as selective BuChE inhibitors for the treatment of Alzheimer's disease

To discover novel scaffolds as leads against dementia, a series of δ-aryl-1,3-dienesulfonyl fluorides with α-halo, α-aryl and α-alkynyl were assayed for ChE inhibitory activity, in which compound A10 was identified as a selective BuChE inhibitor (IC₅₀ = 0.021 μM for eqBChE, 3.62 μM for hBuChE). SAR of BuChE inhibition showed: (i) o- > m- > p-; –OCH₃ > –CH₃ > –Cl (–Br) for δ-aryl; (ii) α-Br > α-Cl, α-I. Compound A10 exhibited neuroprotective, BBB penetration, mixed competitive inhibitory effect on BuChE (K_i = 29 nM), and benign neural and hepatic safety. Treatment with A10 could almost entirely recover the Aβ_1-42-induced cognitive dysfunction to the normal level, and the assessment of total amount of Aβ_1-42 confirmed its anti-amyloidogenic profile. Therefore, the potential BuChE inhibitor A10 is a promising effective lead for the treatment of AD.     

Design,synthesis, and evaluation of chalcone-Vitamin E-donepezil hybrids as multi-target-directed ligands for the treatment of Alzheimer’s disease

A novel series of chalcone-Vitamin E-donepezil hybrids was designed and developed based on multitarget-directed ligands (MTDLs) strategy for treating Alzheimer’s disease (AD). The biological results revealed that compound 17f showed good AChE inhibitory potency (ratAChE IC₅₀ = 0.41 µM; eeAChE IC₅₀ = 1.88 µM). Both the kinetic analysis and docking study revealed that 17f was a mixed type AChE inhibitor. 17f was also a good antioxidant (ORAC = 3.3 eq), selective metal chelator and huMAO-B inhibitor (IC₅₀ = 8.8 µM). Moreover, it showed remarkable inhibition of self- and Cu²⁺-induced Aβ_1–42 aggregation with a 78.0 and 93.5% percentage rate at 25 µM, respectively, and disassembled self-induced and Cu²⁺-induced aggregation of the accumulated Aβ_1–42 fibrils with 72.3 and 84.5% disaggregation rate, respectively. More importantly, 17f exhibited a good neuroprotective effect on H₂O₂-induced PC12 cell injury and presented good blood-brain barrier permeability in vitro. Thus, 17f was a promising multi-target-directed ligand for treating AD.     

Effects of DISC1 on Alzheimer’s disease cell models assessed by iTRAQ proteomics analysis

Alzheimer’s disease (AD) is a form of neurodegenerative disease in the elderly with no cure at present. In a previous study, we found that the scaffold protein, disrupted in Schizophrenia 1 (DISC1) is down-regulated in the AD brains, and ectopic expression of DISC1 can delay the progression of AD by protecting synaptic plasticity and down-regulating BACE1. However, the underlying mechanisms remain not to be elucidated. In the present study, we compared the proteomes of normal and DISC1^high AD cells expressing the amyloid precursor protein (APP) using isobaric tag for relative and absolute quantitation (iTRAQ) and mass spectrometry (MS). The differentially expressed proteins (DEPs) were identified, and the protein–protein interaction (PPI) network was constructed to identify the interacting partners of DISC1. Based on the interaction scores, NDE1, GRM3, PTGER3 and KATNA1 were identified as functionally or physically related to DISC1, and may therefore regulate AD development. The DEPs were functionally annotated by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases with the DAVID software, and the Non-supervised Orthologous Groups (eggNOG) database was used to determine their evolutionary relationships. The DEPs were significantly enriched in microtubules and mitochondria-related pathways. Gene set enrichment analysis (GSEA) was performed to identify genes and pathways that are activated when DISC1 is overexpressed. Our findings provide novel insights into the regulatory mechanisms underlying DISC1 function in AD.     

Functional and Structural Effects of Amyloid-β Aggregate on Xenopus laevis Oocytes

Xenopus laevis oocytes exposed to amyloid-β aggregate generated oscillatory electric activity (blips) that was recorded by two-microelectrode voltage-clamp. The cells exhibited a series of “spontaneous” blips ranging in amplitude from 3.8 ± 0.9 nA at the beginning of the recordings to 6.8 ± 1.7 nA after 15 min of exposure to 1 μM aggregate. These blips were similar in amplitude to those induced by the channel-forming antimicrobial agents amphotericin B (7.8 ± 1.2 nA) and gramicidin (6.3 ± 1.1 nA). The amyloid aggregate-induced currents were abolished when extracellular Ca²⁺ was removed from the bathing solution, suggesting a central role for this cation in generating the spontaneous electric activity. The amyloid aggregate also affected the Ca²⁺-dependent Cl⁻ currents of oocytes, as shown by increased amplitude of the transient-outward chloride current (T_out) and the serum-activated, oscillatory Cl⁻ currents. Electron microcopy revealed that amyloid aggregate induced the dissociation of the follicular cells that surround the oocyte, thus leading to a failure in the electro-chemical communication between these cells. This was also evidenced by the suppression of the oscillatory Ca²⁺-dependent ATP-currents, which require proper coupling between oocytes and the follicular cell layer. These observations, made using the X. laevis oocytes as a versatile experimental model, may help to understand the effects of amyloid aggregate on cellular communication.     

A brief overview of amyloids and Alzheimer’s disease

Amyloid fibrils are self-assembled fibrous protein aggregates that are associated with a number of presently incurable diseases such as Alzheimer’s and Parkinson’s disease. Millions of people worldwide suffer from amyloid diseases. This review summarizes the unique cross-β structure of amyloid fibrils, morphological variations, the kinetics of amyloid fibril formation, and the cytotoxic effects of these fibrils and oligomers. Alzheimer’s disease is also explored as an example of an amyloid disease to show the various approaches to treat these amyloid diseases. Finally, this review investigates the nanotechnological and biological applications of amyloid fibrils; as well as a summary of the typical biological pathways involved in the disposal of amyloid fibrils and their precursors.     

Design,synthesis, and evaluation of 3,7-substituted coumarin derivatives as multifunctional Alzheimer’s disease agents

Multitarget directed ligands (MTDLs) are emerging as promising treatment options for Alzheimer’s disease (AD). Coumarin derivatives serve as a good starting point for designing MTDLs due to their inherent inhibition of monoamine oxidase (MAO) and cholinesterase enzymes, which are complicit in AD’s complex pathophysiology. A preliminary series of 3,7-substituted coumarin derivatives were synthesised and evaluated for enzyme inhibitory activity, cytotoxicity as well as neuroprotective ability. The results indicated that the compounds are weak cholinesterase inhibitors with five compounds demonstrating relatively potent inhibition and selectivity towards MAO-B with IC₅₀ values between 0.014 and 0.498 hx00B5;µM. Significant neuroprotective effects towards MPP⁺-compromised SH-SY5Y neuroblastoma cells were also observed, with no inherent cytotoxicity at 10 µM for all compounds. The overall results demonstrated that substitution of the phenylethyloxy moiety at the 7-position imparted superior general activity to the derivatives, with the propargylamine substitution at the 3-position, in particular, displaying the best MAO-B selectivity and neuroprotection.     

The effect of treadmill exercise on inflammatory responses in rat model of streptozotocin-induced experimental dementia of Alzheimer’s type

[Purpose]

The aim of this study was to investigate the effect of treadmill exercise on inflammatory response in streptozotocin (STZ)-induced animal model of Alzheimer’s disease (AD).

[Methods]

To induce the animal model of AD, Sprague-Dawley rats were injected into intracerebroventricular (ICV) injection with 1.5 mg/kg of STZ. Rats were divided into three groups as Sham-con group (n = 7), STZ-con group (n = 7) and STZ-exe group (n = 7). Exercise group ran on the treadmill for 30 min/day, 5 days/week during 6 weeks.

[Results]

The results of this study were as follows: First, STZ-exe group was improved on cognitive function when compared to STZ-con group in water maze test. Second, STZ-exe group help reduce the expression level of amyloid-beta (Aβ). In addition, Toll-like receptors-4 (TLR4), Nuclear factor-kB (NF-kB), Tumor necrosis factor-α (TNF-α) and Interleukin-1α (IL-1α) level of STZ-exe group was significantly decreased when compared to STZ-con group.

[Conclusion]

These results show that treadmill exercise had positive effect on cognitive function and reduced inflammatory response in STZ-induced animal model of AD.