Hippocampal neuronal cells that accumulate α-synuclein fragments are more vulnerable to Aβ oligomer toxicity via mGluR5--implications for dementia with Lewy bodies.

BackgroundIn dementia with Lewy bodies (DLB) abnormal interactions between α-synuclein (α-syn) and beta amyloid (Aβ) result in selective degeneration of neurons in the neocortex, limbic system and striatum. However, factors rendering these neurons selectively vulnerable have not been fully investigated. The metabotropic glutamate receptor 5 (mGluR5) has been shown to be up regulated in DLB and might play a role as a mediator of the neurotoxic effects of Aβ and α-syn in vulnerable neuronal populations. In this context, the main objective of the present study was to investigate the role of mGluR5 as a mediator of the neurotoxic effects of α-syn and Aβ in the hippocampus.ResultsWe generated double transgenic mice over-expressing amyloid precursor protein (APP) and α-syn under the mThy1 cassette and investigated the relationship between α-syn cleavage, Aβ, mGluR5 and neurodegeneration in the hippocampus. We found that compared to the single tg mice, the α-syn/APP tg mice displayed greater accumulation of α-syn and mGluR5 in the CA3 region of the hippocampus compared to the CA1 and other regions. This was accompanied by loss of CA3 (but not CA1) neurons in the single and α-syn/APP tg mice and greater loss of MAP 2 and synaptophysin in the CA3 in the α-syn/APP tg. mGluR5 gene transfer using a lentiviral vector into the hippocampus CA1 region resulted in greater α-syn accumulation and neurodegeneration in the single and α-syn/APP tg mice. In contrast, silencing mGluR5 with a lenti-shRNA protected neurons in the CA3 region of tg mice. In vitro, greater toxicity was observed in primary hippocampal neuronal cultures treated with Aβ oligomers and over-expressing α-syn; this effect was attenuated by down-regulating mGluR5 with an shRNA lentiviral vector. In α-syn-expressing neuronal cells lines, Aβ oligomers promoted increased intracellular calcium levels, calpain activation and α-syn cleavage resulting in caspase-3-dependent cell death. Treatment with pharmacological mGluR5 inhibitors such as 2-Methyl-6-(phenylethynyl)pyridine (MPEP) and 3-((2-Methyl-4-thiazolyl)ethynyl)pyridine (MTEP) attenuated the toxic effects of Aβ in α-syn-expressing neuronal cells.ConclusionsTogether, these results support the possibility that vulnerability of hippocampal neurons to α-syn and Aβ might be mediated via mGluR5. Moreover, therapeutical interventions targeting mGluR5 might have a role in DLB

Neuroprotective effects of the immunomodulatory drug FK506 in a model of HIV1-gp120 neurotoxicity.

BackgroundHIV-associated neurocognitive disorders (HAND) continue to be a common morbidity associated with chronic HIV infection. It has been shown that HIV proteins (e.g., gp120) released from infected microglial/macrophage cells can cause neuronal damage by triggering inflammation and oxidative stress, activating aberrant kinase pathways, and by disrupting mitochondrial function and biogenesis. Previous studies have shown that FK506, an immunophilin ligand that modulates inflammation and mitochondrial function and inhibits calcineurin, is capable of rescuing the neurodegenerative pathology in models of Parkinson's disease, Alzheimer's disease, and Huntington's disease. In this context, the main objective of this study was to evaluate if FK506 could rescue the neuronal degeneration and mitochondrial alterations in a transgenic (tg) animal model of HIV1-gp120 neurotoxicity.MethodsGFAP-gp120 tg mice were treated with FK506 and analyzed for neuropathology, behavior, mitochondrial markers, and calcium flux by two-photon microscopy.ResultsWe found that FK506 reduced the neuronal cell loss and neuro-inflammation in the gp120 tg mice. Moreover, while vehicle-treated gp120 tg mice displayed damaged mitochondria and increased neuro-inflammatory markers, FK506 rescued the morphological mitochondrial alterations and neuro-inflammation while increasing levels of optic atrophy 1 and mitofusin 1. By two-photon microscopy, calcium levels were not affected in the gp120 tg mice and no effects of FK506 were detected. However, at a functional level, FK506 ameliorated the gp120 tg mice hyperactivity in the open field.ConclusionsTogether, these results suggest that FK506 might be potentially neuroprotective in patients with HAND by mitigating inflammation and mitochondrial alterations

Accumulation of oligomer-prone α-synuclein exacerbates synaptic and neuronal degeneration in vivo

The toxicity of α-synuclein invivo is not well understood. Rockenstein etal. describe an α-synuclein transgenic model expressing the E57K mutant that forms stable oligomers. They show that oligomers accumulate at synapses and that the mutation interferes with synaptic vesicles and is associated with behavioural deficits and neurodegeneratio

Chlorella vulgaris biomass enriched by biosorption of polyphenols

Cell walls of microalgae are variable and contain non-specific domains where different molecules can bind. The enrichment of microalgal biomass with nutrients through adsorption can be an interesting process for the food and feed industry. In this study, naturally occurring polyphenols ((+)-catechin, ()-epicatechin, quercetin, rutin and xanthohumol) were adsorbed onto nonliving cells of freshwater microalgae Chlorella vulgaris. The essential adsorption parameters such as biomass dose and contact time were examined and the adsorption was quantified with Langmuir, Sips and DubininRadushkevich adsorption isotherms. The evaluation of isotherms proved the highest affinity towards Chlorella vulgaris biomass for xanthohumol and quercetin. The biosorption mechanism of Chlorella vulgaris biomass was well described by a pseudo second order kinetic model, with a high regression coefficient. The polyphenol-enriched microalgal biomass was also evaluated for its antioxidant activity. The highest antioxidant activity was detected in the case of biomass enriched with quercetin (77.5% of decolorized DPPH).The financial support by the Ministry of Education, Youth and Sports of the Czech Republic through grant MSM6046137305 is gratefully acknowledged. Cristina Quintelas is thankful to Fundacao para a Ciencia e a Tecnologia (FCT, Portugal) for funding the CEB researcher unit at the University of Minho and thanks the Project "BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028" co-funded by the Programa Operacional Regional do Norte (ON.2 - O Novo Norte), QREN and FEDER

The many faces of α-synuclein: from structure and toxicity to therapeutic target

Disorders characterized by α-synuclein (α-syn) accumulation, Lewy body formation and parkinsonism (and in some cases dementia) are collectively known as Lewy body diseases. The molecular mechanism (or mechanisms) through which α-syn abnormally accumulates and contributes to neurodegeneration in these disorders remains unknown. Here, we provide an overview of current knowledge and prevailing hypotheses regarding the conformational, oligomerization and aggregation states of α-syn and their role in regulating α-syn function in health and disease. Understanding the nature of the various α-syn structures, how they are formed and their relative contributions to α-syn-mediated toxicity may inform future studies aiming to develop therapeutic prevention and intervention

Differential effects of immunotherapy with antibodies targeting α-synuclein oligomers and fibrils in a transgenic model of synucleinopathy

Disorders with progressive accumulation of α-synuclein (α-syn) are a common cause of dementia and parkinsonism in the aging population. Accumulation and propagation of α-syn play a role in the pathogenesis of these disorders. Previous studies have shown that immunization with antibodies that recognize C-terminus of α-syn reduces the intra-neuronal accumulation of α-syn and related deficits in transgenic models of synucleinopathy. These studies employed antibodies that recognize epitopes within monomeric and aggregated α-syn that were generated through active immunization or administered via passive immunization. However, it is possible that more specific effects might be achieved with antibodies recognizing selective species of the α-syn aggregates. In this respect we recently developed antibodies that differentially recognized various oligomers (Syn-O1, -O2, and -O4) and fibrilar (Syn-F1 and -F2) forms of α-syn. For this purpose wild-type α-syn transgenic (line 61) mice were immunized with these 5 different antibodies and neuropathologically and biochemically analyzed to determine which was most effective at reducing α-syn accumulation and related deficits. We found that Syn-O1, -O4 and -F1 antibodies were most effective at reducing accumulation of α-syn oligomers in multiple brain regions and at preventing neurodegeneration. Together this study supports the notion that selective antibodies against α-syn might be suitable for development new treatments for synucleinopathies such as PD and DLB

Evaluation of the estrogenic effects of dietary perinatal Trifolium pratense

This study was designed to investigate the potential estrogenic effects of perinatal dietary phytoestrogens on the rat uterus. Pregnant rats were divided to three groups provided the following diets: (1) rat chow, (2) rat chow with 7.5% Trifolium (T.) pratense, or (3) rat chow supplemented with 17β-estradiol (0.5 mg/kg). The dams in each group were kept on the same diet during pregnancy and lactation. Female offspring were euthanized on day 21 at which time body and organ weights were recorded and tissue samples were taken for histology. Immunohistochemistry was performed to detect estrogen receptor alpha (ERα) and progesterone receptor (PR) levels. Our results revealed estrogen-like biological effects of perinatal T. pratense exposure. Relative uterus and ovary weights in the experimental groups were increased compared to control. The number of uterine glands and luminal epithelium heights were also increased. However, there were no statistically significant changes detected in the immunostaining intensity of ERα and PR between the groups

High-Content Screening and Mechanism-Based Evaluation of Estrogenic Botanical Extracts

Symptoms associated with menopause can greatly affect the quality of life for women. Botanical dietary supplements have been viewed by the public as safe and effective despite a lack of evidence indicating a urgent necessity to standardize these supplements chemically and biologically. Seventeen plants were evaluated for estrogenic biological activity using standard assays: competitive estrogen receptor (ER) binding assay for both alpha and beta subtypes, transient transfection of the estrogen response element luciferase plasmid into MCF-7 cells expressing either ER alpha or ER beta, and the Ishikawa alkaline phosphatase induction assay for both estrogenic and antiestrogenic activities. Based on the combination of data pooled from these assays, the following was determined: a) a high rate of false positive activity for the competitive binding assays, b) some extracts had estrogenic activity despite a lack of ability to bind the ER, c) one extract exhibited selective estrogen receptor modulator (SERM) activity, and d) several extracts show additive/synergistic activity. Taken together, these data indicate a need to reprioritize the order in which the bioassays are performed for maximal efficiency of programs involving bioassay-guided fractionation. In addition, possible explanations for the conflicts in the literature over the estrogenicity of Cimicifuga racemosa (black cohosh) are suggested

Modeling Alzheimer’s disease related phenotypes in the Ts65Dn mouse: impact of age on Aβ, Tau, pTau, NfL, and behavior

IntroductionPeople with DS are highly predisposed to Alzheimer’s disease (AD) and demonstrate very similar clinical and pathological features. Ts65Dn mice are widely used and serve as the best-characterized animal model of DS.MethodsWe undertook studies to characterize age-related changes for AD-relevant markers linked to Aβ, Tau, and phospho-Tau, axonal structure, inflammation, and behavior.ResultsWe found age related changes in both Ts65Dn and 2N mice. Relative to 2N mice, Ts65Dn mice showed consistent increases in Aβ40, insoluble phospho-Tau, and neurofilament light protein. These changes were correlated with deficits in learning and memory.DiscussionThese data have implications for planning future experiments aimed at preventing disease-related phenotypes and biomarkers. Interventions should be planned to address specific manifestations using treatments and treatment durations adequate to engage targets to prevent the emergence of phenotypes