Gilles Guillemin

ABSTRACT Alzheimer disease (AD) is a neurodegenerative disease which is characterized by the presence of extracellular senile plaques mainly composed of amyloid-β peptide (Aβ), intracellular neurofibrillary tangles, and selective synaptic and neuronal loss. AD brains revealed elevated levels of oxidative stress markers which have been implicated in Aβ-induced toxicity. Multiple components present in pomegranate and various pomegranate preparations are known to exert pleiotropic protective effects as demonstrated in various in vitro and in vivo model systems. The present study was designed to investigate the dietary supplementation of 4% pomegranate fruit grown in Oman on oxidative stress in the hippocampus, and hippocampal neuron injury in Tg2576 mice. The Tg 2576 mice were treated with 4% pomegranate by dietary supplementation for 15 months. After 15 months, the mice were sacrificed for measuring non-enzymatic [4-hydroxynonenal, TBARS, hydrogen peroxide, reduced glutathione (GSH), vitamin A, E, C and enzymatic antioxidants activity in the hippocampus, and expression of choline acetyltransferase (ChAT) positive neuron. The non-enzymatic and enzymatic antioxidants were significantly reduced along with elevated oxidative stress markers. Loss of ChAT positive neuron and severe damage to hippocampal neurons in Tg 2576 were also found. These abnormalities were significantly improved by 4% pomegranate treatment. In contrast, administration of 4% pomegranate diet to mice strongly suggested a putative delay in the formation of plaques, as indicated by a decreasing tendency of soluble and fibrillar Aβ levels in hippocampus which correlated with a decrease in Aβ (1-40, 1-42) plasma content. The study suggests that pomegranate could offer protection against neuronal injury and oxidative stress, and may be used as a potential agent in treatment of neurodegenerative diseases such as AD. This project was supported by a research grant from The Research Council, Oman (RC/AGR/FOOD/11/01).

An increase of plasma kynurenine concentrations, potentially bioactive metabolites of tryptophan, was found in subjects with obesity, resulting from low-grade inflammation of the white adipose tissue. Bariatric surgery decreases low-grade inflammation associated with obesity and improves glucose control. Our goal was to determine the concentrations of all kynurenine metabolites after bariatric surgery and whether they were correlated with glucose control improvement. Kynurenine metabolite concentrations, analysed by liquid or gas chromatography coupled with tandem mass spectrometry, circulating inflammatory markers, metabolic traits, and BMI were measured before and one year after bariatric surgery in 44 normoglycemic and 47 diabetic women with obesity. Associations between changes in kynurenine metabolites concentrations and in glucose control and metabolic traits were analysed between baseline and twelve months after surgery. Tryptophan and kynurenine metabolite concentrations wer...

ABSTRACT Although there are no proven ways to delay onset or slow progression of Alzheimer's disease (AD), studies suggest that diet can affect risk. Dates palm fruit are good sources of minerals (Se, Cu, K and Mg), vitamins (C, A, B6, B9, B2, B3), dietary fiber and total phenolics and natural antioxidants (anthocyanins & ferulic acid). Polyphenols have been shown to be neuroprotective in different model systems. We asked whether dietary supplementation with 2% dates or 4% dates would influence behavior and AD like pathology in a transgenic mouse model. The four month old mice with double Swedish APP mutation (APPsw/Tg2576) were purchased from Taconic Farm, NY, USA. The experimental groups of APP-transgenic mice from the age of 4 months were fed custom-mix diets (pellets) containing 2% dates or 4% dates. The control groups, i.e. tg mice and wild-type mice were fed diet without dates. Animals from all groups were undergone behavioral assessments at the age of 4-5 months and 14-15 months by Morris water maze test (for spatial memory and learning ability), T maze test (for position discrimination learning ability), rota rod test (for psychomotor coordination), elevated plus maze test (for anxiety-related behavior) and open field test (anxiety) to analyze the effect of diet rich in dates on learning skills, memory, anxiety, locomotors activity, and motor coordination. Both the diets rich in 2% dates & 4% dates fed tg mice showed a significant improvement in memory, learning ability, anxiety and motor development compared to the AD tg mice on diet without 2% dates & 4% dates. The more effect was observed in 4% dates diet fed animals than 2% fed. Our results suggest that dietary supplementation of date palm fruits may have beneficial effect in reducing the risk, delaying the onset or slowing the progression of Alzheimer's disease.This project was supported by a research grant from The Research Council, Oman (RC/AGR/FOOD/11/01).

ABSTRACT Ionising radiation (γ or X-rays) is the mandatory tool to treat cancer despite its detrimental effects in particular on skin cells which lead to severe dermatological diseases and carcinogenesis. Natural antioxidants caffeic acid (CA), rosmarinic acid (RA), trans cinnamic acid (TCA), p-coumaric acid (PCA), and hydroxyphenyllactic acid (HPA) acid are known to be potent anticancer and antioxidant agents. Current study is designed to provide experimental evidence as these compounds offer radiation protection for skin cells. Non-toxic concentrations of CA, RA, TCA, PCA, and HPA were tested for radiation protection, γ-radiation induced intracellular reactive oxygen species (ROS) by flow cytometry and DNA double strand break in human keratinocytes (HaCaT cells) by immunocytochemistry. CA, RA and TCA pre-treatment can protect the HaCaT cells by 40%, 20%, 15% respectively through scavenging γ-radiation induced ROS and decreasing number of post irradiation 53bp1 foci. Inclusion of these compounds in chemo-radiotherapy could facilitate to achieve multiple target protection (i.e. anti-cancer and skin radio protectant).

There is good evidence that the kynurenine pathway (KP) and one of its products, quinolinic acid (QUIN) play a role in the pathogenesis of neurological diseases. Monocytic cells are known to be the major producers of QUIN. However, macrophages have the ability to produce approximately 20 to 30-fold more QUIN than microglia. The molecular origin of this difference has not been clarified yet. Using unstimulated and IFN-gamma-stimulated cultures of human fcetal microglia and adult macrophages, we assayed mRNA expression of 8 key enzymes of the KP using RT-PCR and QUIN production using GC-MS. We found that after stimulation with IFN-gamma microglia produced de novo 20-fold less QUIN than macrophages. This quantitative difference in the ability to produce QUIN appears to be associated with a lower expression of 3 important enzymes of the KP in microglia: indoleamine 2,3-dioxygenase (IDO), kynureninase (KYNase) and kynurenine hydroxylase (KYN(OH)ase). These results suggest that activated infiltrating macrophages are the most potent QUIN producers during brain inflammatory diseases with playing a lesser role.

Although there are seven mammalian sirtuins (SIRT1-7), little is known about their expression in the aging brain. To characterize the change(s) in mRNA and protein expression of SIRT1-7 and their associated proteins in the brain of "physiologically" aged Wistar rats. We tested mRNA and protein expression levels of rat SIRT1-7, and the levels of associated proteins in the brain using RT-PCR and western blotting. Our data shows that SIRT1 expression increases with age, concurrently with increased acetylated p53 levels in all brain regions investigated. SIRT2 and FOXO3a protein levels increased only in the occipital lobe. SIRT3-5 expression declined significantly in the hippocampus and frontal lobe, associated with increases in superoxide and fatty acid oxidation levels, and acetylated CPS-1 protein expression, and a reduction in MnSOD level. While SIRT6 expression declines significantly with age acetylated H3K9 protein expression is increased throughout the brain. SIRT7 and Pol I protein expression increased in the frontal lobe. This study identifies previously unknown roles for sirtuins in regulating cellular homeostasis and healthy aging.

This study utilised a proteomics approach to identify any differential protein expression in a glial cell line, rat olfactory ensheathing cells (OECs), treated with the cyanotoxin β-methylamino-l-alanine (BMAA). Five proteins of interest were identified, namely Rho GDP-dissociation inhibitor 1 (RhoGDP1), Nck-associated protein 1 (NCKAP1), voltage-dependent anion-selective channel protein 1 (VDAC1), 3-hydroxyacyl-CoA dehydrogenase type-2 (3hCoAdh2), and ubiquilin-4 (UBQLN4). Four of these candidates, nuclear receptor subfamily 4 group A member 1 (Nur77), cyclophilin A (CyPA), RhoGDP1 and VDAC1, have been reported to be involved in cell growth. A microarray identified UBQLN4, palladin and CyPA, which have been implicated to have roles in excitotoxicity. Moreover, the NCKAP1, UBQLN4, CyPA and 3hCoAdh2 genes have been associated with abnormal protein aggregation. Differential expression of genes involved in mitochondrial activity, Nur77, 3hCoAdh2, VDAC1 and UBQLN4, were also identified....

Acute UVB exposure triggers inflammation leading to the induction of indoleamine 2,3 dioxygenase (IDO1), one of the first enzymes in the kynurenine pathway (KP) for tryptophan degradation. However, limited studies have been undertaken to determine the catabolism of tryptophan within the skin. The aim of this study was two-fold: (1) to establish if the administration of the proinflammatory cytokine interferon-gamma (IFN-γ) and/or UVB radiation elicits differential KP expression patterns in human fibroblast and keratinocytes, and (2) to evaluate the effect of KP metabolites on intracellular nicotinamide adenine dinucleotide (NAD(+) ) levels, and cell viability. Primary cultures of human fibroblasts and keratinocytes were used to examine expression of the KP at the mRNA level using qPCR, and at the protein level using immunocytochemistry. Cellular responses to KP metabolites were assessed by examining extracellular lactate dehydrogenase (LDH) activity and intracellular NAD(+) levels. M...

The accumulation and aggregation of alpha-synuclein (α-syn) in several tissue including the brain is a major pathological hallmark in Parkinson's disease (PD). In this study, we show that α-syn can be taken up by primary human cortical neurons, astrocytes and skin-derived fibroblasts in vitro. Our findings that brain and peripheral cells exposed to α-syn can lead to impaired mitochondrial function, leading to cellular degeneration and cell death, provides additional evidence for the involvement of mitochondrial dysfunction as a mechanism of toxicity of α-syn in human cells.

Alzheimer disease (AD) is one of the most common forms of dementia in the elderly. Several reports have suggested neurotoxic effects of amyloid beta protein (Aβ) and role of oxidative stress in AD. Figs are rich in fiber, copper, iron, manganese, magnesium, potassium, calcium, vitamin K, and are a good source of proanthocyanidins and quercetin which demonstrate potent antioxidant properties. We studied the effect of dietary supplementation with 4% figs grown in Oman on the memory, anxiety, and learning skills in APPsw/Tg2576 (Tg mice) mice model for AD. We assessed spatial memory and learning ability, psychomotor coordination, and anxiety-related behavior in Tg and wild-type mice at the age of 4 months and after 15 months using the Morris water maze test, rota-rod test, elevated plus maze test, and open-field test. Tg mice that were fed a control diet without figs showed significant memory deficits, increased anxiety-related behavior, and severe impairment in spatial, position discrimination learning ability, and motor coordination compared to the wild-type control mice on the same diet, and Tg mice fed on 4% fig diet supplementation for 15 months. Our results suggest that dietary supplementation of figs may be useful for the improvement of cognitive and behavioral deficits in AD.

... PMCID: PMC3195248. Copyright © the author(s), publisher and licensee Libertas Academica Ltd. ... Articles from International Journal of Tryptophan Research : IJTR are provided here courtesy of Libertas Academica. PubMed articles by these authors. Guillemin, G. Recent Activity. ...

Leukocyte immunoglobulin-like receptor A3 (LILRA3) is a soluble immune regulatory molecule primarily expressed by monocytes and macrophages. A homozygous 6.7kbp LILRA3 gene deletion that removes the first seven of its eight exons is predicted to lead to lack of LILRA3 protein, although this has not been experimentally confirmed. Moreover, there are conflicting results with regards to the link between the LILRA3 homozygous genetic deletion and susceptibility to multiple sclerosis (MS) in different European populations. The aim of this study was to investigate whether LILRA3 gene deletion is associated with MS susceptibility in a North American cohort of European ancestry and assess if serum LILRA3 protein level is a marker of clinical subtype and/or disease severity in MS. A total of 456 patients with MS and 99 unrelated healthy controls were genotyped for the 6.7kbp LILRA3 gene deletion and levels of LILRA3 protein in sera determined by in-house sandwich ELISA. We showed that LILRA3...

Inhibitory proteins, particularly Nogo 66, a highly conserved 66 amino acid loop of Nogo A, play key roles in limiting the intrinsic capacity of the central nervous system to regenerate after injury. Ligation of surface Nogo receptors (NgRs) and/or leukocyte immunoglobulin like receptor B2 (LILRB2) and its mouse orthologue the paired-immunoglobulin-like receptor B (PIRB) by Nogo 66 transduces inhibitory signals that potently inhibit neurite outgrowth. Here we show that soluble leukocyte immunoglobulin-like receptor A3 (LILRA3) is a high affinity receptor for Nogo 66, suggesting that LILRA3 might be a competitive antagonist to these cell surface inhibitory receptors. Consistent with this, LILRA3 significantly reversed Nogo 66-mediated inhibition of neurite outgrowth and promoted synapse formation in primary cortical neurons via regulation of the MEK/ERK pathway. LILRA3 represents a new antagonist to Nogo 66-mediated inhibition of neurite outgrowth in the CNS, a function distinct from...

Multiple system atrophy (MSA) is a progressive neurodegenerative disease presenting with combinations of autonomic dysfunction, parkinsonism, cerebellar ataxia and/or pyramidal signs. Oligodendroglial cytoplasmic inclusions (GCIs) rich in α-synuclein (α-syn) constitute the disease hallmark, accompanied by neuronal loss and activation of glial cells which indicate neuroinflammation. Recent studies demonstrate that α-syn may be released from degenerating neurons to mediate formation of abnormal inclusion bodies and to induce neuroinflammation which, interestingly, might also favor the formation of intracellular α-syn aggregates as a consequence of cytokine release and the shift to a pro-inflammatory environment. Here, we critically review the relationships between α-syn and astrocytic and microglial activation in MSA to explore the potential of therapeutics which target neuroinflammation.

Mitochondrial dysfunction and resulting energy impairment have been identified as features of many neurodegenerative diseases. Whether this energy impairment is the cause of the disease or the consequence of preceding impairment(s) is still under discussion, however a recovery of cellular bioenergetics would plausibly prevent or improve the pathology. In this study, we screened different natural molecules for their ability to increase intracellular adenine triphosphate purine (ATP). Among them, epigallocatechin-3-gallate (EGCG), a polyphenol from green tea, presented the most striking results. We found that it increases ATP production in both human cultured astrocytes and neurons with different kinetic parameters and without toxicity.Specifically, we showed that oxidative phosphorylation in human cultured astrocytes and neurons increased at the level of the routine respiration on the cells pre-treated with the natural molecule. Furthermore, EGCG-induced ATP production was only block...

Breast cancer (BrCa) is the leading cause of cancer related death in women. While current diagnostic modalities provide opportunities for early medical intervention, significant proportions of breast tumours escape treatment and metastasize. Gaining increasing recognition as a factor in tumour metastasis is the local immuno-surveillance environment. Following identification of the role played by the enzyme indoleamine dioxygenase 1 (IDO1) in mediating maternal foetal tolerance, the kynurenine pathway (KP) of tryptophan metabolism has emerged as a key metabolic pathway contributing to immune escape. In inflammatory conditions activation of the KP leads to the production of several immune-modulating metabolites including kynurenine, kynurenic acid, 3-hydroxykynurenine, anthranilic acid, 3-hydroxyanthranilic acid, picolinic acid and quinolinic acid. KP over-activation was first described in BrCa patients in the early 1960s. More evidence has since emerged to suggest that the IDO1 is el...

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) is an environmental toxin which selectively induces oxidative damage and mitochondrial and proteasomal dysfunctions to dopaminergic neurons in the substantia nigra leading to Parkinsonian syndrome in animal models and humans. MPTP is one of the most widely used in vitro models to investigate the pathophysiology of Parkinson's disease (PD) and, screen for novel therapeutic compounds that can slow down or ameliorate this progressive degenerative disease. We investigated the therapeutic effect of pomegranate juice extracts (PJE), Helow, Malasi, Qusum, and Hamadh against MPTP-induced neurotoxicity in primary human neurons by examining extracellular LDH activity, intracellular NAD(+) and ATP levels, and endogenous antioxidant levels including lipid peroxidation products, catalase, superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities, and reduced glutathione (GSH) levels. MPTP induced a reduction in SOD and GPx activities and intracellular NAD(+), ATP, and GSH levels parallel to an increase in extracellular LDH and CAT activities, although lipid peroxidation was not altered. We report that helow and malasi can ameliorate MPTP-induced neurotoxicity by attenuating the observed changes in redox function to a greater extent than qusum and hamedh. Selected PJE varieties may exhibit properties which may be of therapeutic value to slow down age-related degeneration and neurodegeneration in particular.

Dysfunction of the serotoninergic and glutamatergic systems is implicated in the pathogenesis of autism spectrum disorder (ASD) together with various neuroinflammatory mediators. As the kynurenine pathway (KP) of tryptophan degradation is activated in neuroinflammatory states, we hypothesized that there may be a link between inflammation in ASD and enhanced KP activation resulting in reduced serotonin synthesis from tryptophan and production of KP metabolites capable of modulating glutamatergic activity. A cross-sectional study of 15 different Omani families with newly diagnosed children with ASD (n = 15) and their age-matched healthy siblings (n = 12) was designed. Immunological profile and the KP metabolic signature were characterized in the study participants. Our data indicated that there were alterations to the KP in ASD. Specifically, increased production of the downstream metabolite, quinolinic acid, which is capable of enhancing glutamatergic neurotransmission was noted. Cor...

Here we report a simple new method for exposing cells to normoxic and hypoxic conditions using vacuum bags, normally employed for food storage, to establish and maintain low oxygen levels in vitro. Vacuum bags were gassed with a mixture containing specified levels of oxygen, then sealed, creating a hypoxic microenvironment for cells cultured in flasks placed therein. Oxygen levels in the gas mixture and culture medium in flasks inside the sealed bags equilibrated after two hours of incubation. The vacuum bags maintained low oxygen levels (either <2% or 5%) in medium for at least 4 days. Human fetal astrocytes grew normally in flasks for at least 4 days in a 5% oxygen/ 5% CO2/ 90% nitrogen atmosphere, but viability decreased at <2% oxygen. Vacuum bags can accommodate varying oxygen levels that would otherwise require systems with separate chambers or modules, but are less useful when repeated experimental manipulations of individual cultures are required.