Evaluation des Effets de l'Exposition au TiO2 sur le Cerveau Adulte et Vulnérable

The overwhelming presence of nanoparticles (NPs) in products including foods, medications, cosmetics, or textiles raises serious concerns about their potential harmful effects on human health. In the wide diversity of NPs, titanium dioxide (TiO2) NPs are among those produced on a large industrial scale and can already be found in several commercial products such as paints, cosmetics or in environmental decontamination systems. In the past, TiO2 NPs was considered inert, but, very recently, the International Agency for Research in Cancer (IARC) has classified TiO2 as possibly carcinogenic (group 2B) to human beings. Numerous in vitro and in vivo studies have shown the potential neuro-toxicity of TiO2 NPs, but very few studies focus on the central nervous system (CNS), Nowadays, notwithstanding the reported advances, the biokinetic and bioaccumulation ofTiO2 NPs and the consequences on the physiology of the blood-brain barrier (BBB) in vivo are unknown. In addition, NPs effect on susceptible population such as the elderly have been mostly ignored. In this context, the target of the present studies is to evaluate the in vivo impact of exposure to NPs on the BBB physiology and brain inflammation which could promote neurotoxicity in young adults and aging. Our results have shown that TiO2 NPs bioaccumulate in organs and tissues (lungs, spleen and liver especially) and don’t translocate to the brain either after IV or subacute inhalation exposure. In IV administration case, the direct interaction between NPs and brain endothelial cells induces BBB functional alterations. Despite the lack of CNS translocation, the biopersistence of titanium in peripheral organs may be indirectly the cause of BBB permeability alteration and brain inflammation. The involvement of circulating mediators linking titanium biopersitence in peripheral organs and brain impact has been demonstrated using an in vitro BBB model. An exacerbated response in term of neuro-inflammation and BBB permeability modulation has established the vulnerability of the aging brain to inhaled NPs toxicity. Taken together, our findings demonstrated that despite lack of brain translocation, exposure to TiO2 NPs induce BBB physiology alteration and neuro-inflammation that may lead to CNS disorders. Thereafter, identification of mediators and description of the neurotoxic effects may complete the assessment of the impact of TiO2 NPs exposure on the brain.La présence croissante de nanoparticules (NPs) dans les produits de la vie quotidienne (alimentation, médicaments, cosmétiques, textiles…) soulève de sérieuses inquiétudes quant à leurs potentiels effets nocifs pour la santé humaine. Les NPs de dioxyde de titane (TiO2) sont produites à l’échelle industrielle et peuvent déjà être trouvées dans plusieurs produits commerciaux tels que les peintures, les cosmétiques ou dans les systèmes de décontamination de l’eau ou de l’air. Dans le passé, les NPs de TiO2 étaient considérées comme inertes, mais, très récemment, l'Agence Internationale pour la Recherche sur le Cancer les a classées comme possiblement cancérogènes (groupe 2B) pour l’homme. De nombreuses études in vitro et in vivo ont démontré la potentielle neuro-toxicité des NPs de TiO2, mais très peu d'études se sont concentrées plus spécifiquement sur la barrière hémato-encéphalique (BHE), protégeant le cerveau. Aujourd'hui, en dépit des avancées constatées, la bio-cinétique et la bio-accumulation des NPs de TiO2 ainsi que les conséquences sur la physiologie de la barrière hémato-encéphalique (BHE) in vivo restent très peu documentées. De plus, dans l’évaluation du risque lié à l’exposition aux NPs, des facteurs de risque tel que l’âge ont jusqu’ici été quasiment ignorés. Dans ce contexte, l’objectif de ce projet est donc d’évaluer chez le rat adulte et âgé, l’impact d’une exposition aux NPs de TiO2 sur les fonctions de la BHE et sur le métabolisme cérébral. Nos résultats ont montré que les NPs de TiO2 s’accumulent dans certains organes et tissus (principalement dans les poumons, la rate et le foie) et ne sont pas distribuées au système nerveux central (SNC) que ce soit après injection intra-veineuse (IV) ou après une inhalation subaiguë à un nano-aérosol de TiO2. Après administration IV, une interaction directe entre NPs et les cellules endothéliales microvasculaires conduit à des altérations fonctionnelles au niveau de la BHE. Malgré l'absence de translocation vers le SNC, la bio-persistance du titane dans les organes périphériques semble être la cause de modulations de perméabilité de la BHE et d’une inflammation cérébrale. L'implication de médiateurs circulants faisant le lien entre la bio-persitance de titane dans les organes périphériques et les modulations observées au niveau cérébral a été démontré en utilisant un modèle in vitro de BHE. Une réponse exacerbée en termes de neuro-inflammation et de modulation de perméabilité de la BHE établit la vulnérabilité du cerveau âgé à la toxicité des NPs inhalées. Ces résultats ont démontré que malgré l'absence de translocation cérébrale, l'exposition aux NPs de TiO2 induit des altérations fonctionnelles de la BHE et une neuro-inflammation qui pourraient conduire à des troubles neurologiques. L’identification des médiateurs et la description des effets neurotoxiques restent encore à préciser

Anti-Cytokine Therapy to Attenuate Ischemic-Reperfusion Associated Brain Injury in the Perinatal Period

Perinatal brain injury is a major cause of morbidity and long-standing disability in newborns. Hypothermia is the only therapy approved to attenuate brain injury in the newborn. However, this treatment is unfortunately only partially neuroprotective and can only be used to treat hypoxic-ischemic encephalopathy in full term infants. Therefore, there is an urgent need for adjunctive therapeutic strategies. Post-ischemic neuro-inflammation is a crucial contributor to the evolution of brain injury in neonates and constitutes a promising therapeutic target. Recently, we demonstrated encouraging neuroprotective capacities of anti-cytokine monoclonal antibodies (mAbs) in an ischemic-reperfusion (I/R) model of brain injury in the ovine fetus. The purpose of this review is to summarize the current knowledge regarding the inflammatory response in the perinatal sheep brain after I/R injury and to review our recent findings regarding the beneficial effects of treatment with anti-cytokine mAbs

Interactions des nanoparticules avec les barrières physiologiques

Du fait de la présence de croissante des nanoparticules dans notre environnement, les expositions et leurs effets toxiques deviennent un sujet de préoccupation. Les barrières physiologiques ont un rôle de protection de l'organisme ou d'organes particuliers. L'étude des interactions entre nanoparticules et ces barrières permet donc de comprendre leur absorption et leur distribution. Il semblerait que ces protections ne représentent pas un obstacle infaillible au passage des nanoparticules. Ces barrières exercent également des fonctions vitales qui peuvent être altérées par l'exposition aux nanoparticules. Les mécanismes d'actions toxiques souvent évoqués dans la littérature sont l'induction de stress oxydant, d'une inflammation et cytotoxicité. Les données disponibles sont encore insuffisantes pour évaluer le risque lié à l'exposition aux nanoparticules et les connaissances sur la toxicité aiguë et chroniques nécessitent d'être approfondies.Due to the presence of an increasingly large number of nanoparticles in our environment, exposure to them and their toxic effects become a cause of concern. Physiological barriers play a role in protecting the body or specific organs. The study of the interactions between nanoparticles and these barriers can therefore help the understanding of their biodistribution. It seems that these protections are not an effective obstacle against the passage of nanoparticles. These barriers also perform vital functions which may be affected by biological changes due to interference between nanoparticles and cells. In literature, the most frequently quoted toxic mechanisms of action are the induction of oxidative stress, inflammation and cytotoxicity. Available data are still insufficient to assess the risk link to nanoparticles exposure. Additional information, including in vivo studies is needed to increase knowledge about acute and chronic toxicity.RENNES1-BU Santé (352382103) / SudocLYON1-BU Santé (693882101) / SudocSudocFranceF

Anti-Cytokine Therapy to Attenuate Ischemic-Reperfusion Associated Brain Injury in the Perinatal Period

Perinatal brain injury is a major cause of morbidity and long-standing disability in newborns. Hypothermia is the only therapy approved to attenuate brain injury in the newborn. However, this treatment is unfortunately only partially neuroprotective and can only be used to treat hypoxic-ischemic encephalopathy in full term infants. Therefore, there is an urgent need for adjunctive therapeutic strategies. Post-ischemic neuro-inflammation is a crucial contributor to the evolution of brain injury in neonates and constitutes a promising therapeutic target. Recently, we demonstrated encouraging neuroprotective capacities of anti-cytokine monoclonal antibodies (mAbs) in an ischemic-reperfusion (I/R) model of brain injury in the ovine fetus. The purpose of this review is to summarize the current knowledge regarding the inflammatory response in the perinatal sheep brain after I/R injury and to review our recent findings regarding the beneficial effects of treatment with anti-cytokine mAbs

Minéralisation de nanoparticules de TiO2 pour la détermination du titane dans les tissus de rat

International audienceIn order to draw appropriate conclusions about the possible adverse biological effects of titanium dioxide nanoparticles (TiO 2-NPs), the so-called "dose-effect" relationship must be explored. This requires proper quantification of titanium in complex matrices such as animal organs for future toxicological studies. This study presents the method development for mineralizing TiO 2-NPs for analysis of biological tissues. We compared the recovery and quantification limits of the four most commonly used mineralization methods for metal oxides. Microwave-assisted dissolution in an HNO 3-HF mixture followed by H 2 O 2 treatment produced the best results for a TiO 2-NPs suspension, with 96 ± 8% recovery and a limit of quantification as low as 0.9 μg/L. This method was then used for the determination of titanium levels in tissue samples taken from rats. However, our tests revealed that even this method is not sensitive enough for quantifying titanium levels in single olfactory bulbs or hippocampus in control animals.Afin de tirer des conclusions appropriées sur les effets biologiques néfastes possibles des nanoparticules de dioxyde de titane (TiO 2-NP), la relation dite «dose-effet» doit être explorée. Cela nécessite une quantification appropriée du titane dans des matrices complexes telles que des organes animaux pour de futures études toxicologiques. Cette étude présente le développement de la méthode de minéralisation des TiO 2-NP pour l'analyse des tissus biologiques. Nous avons comparé les limites de récupération et de quantification des quatre méthodes de minéralisation les plus couramment utilisées pour les oxydes métalliques. La dissolution assistée par micro-ondes dans un mélange HNO 3-HF suivie d'un traitement H 2 O 2 a donné les meilleurs résultats pour une suspension de TiO 2-NPs, avec une récupération de 96 ± 8% et une limite de quantification aussi basse que 0,9 μg / L. Cette méthode a ensuite été utilisée pour la détermination des niveaux de titane dans des échantillons de tissus prélevés sur des rats. Cependant, nos tests ont révélé que même cette méthode n'est pas assez sensible pour quantifier les niveaux de titane dans les bulbes olfactifs uniques ou l'hippocampe chez les animaux témoins

Biopersistence and translocation to extrapulmonary organs of titanium dioxide nanoparticles after subacute inhalation exposure to aerosol in adult and elderly rats

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Brain Inflammation, Blood Brain Barrier dysfunction and Neuronal Synaptophysin Decrease after Inhalation Exposure to Titanium Dioxide Nano-aerosol in Aging Rats

Abstract Notwithstanding potential neurotoxicity of inhaled titanium dioxide nanoparticles (TiO2 NPs), the toxicokinetics and consequences on blood-brain barrier (BBB) function remain poorly characterized. To improve risk assessment, we need to evaluate the impact on BBB under realistic environmental conditions and take into account vulnerability status such as age. 12–13 week and 19-month-old male rats were exposed by inhalation to 10 mg/m3 of TiO2 nano-aerosol (6 hrs/day, 5 day/week, for 4 weeks). We showed an age-dependent modulation of BBB integrity parameters suggesting increased BBB permeability in aging rats. This alteration was associated with a significant increase of cytokines/chemokines in the brain, including interleukin-1β, interferon-γ, and fractalkine as well as a decreased expression of synaptophysin, a neuronal activity marker. These observations, in absence of detectable titanium in the brain suggest that CNS-related effects are mediated by systemic-pathway. Moreover, observations in terms of BBB permeability and brain inflammation underline age susceptibility. Even if TiO2 NPs were not evidenced in the brain, we observed an association between the exposure to TiO2 NPs and the dysregulation of BBB physiology associated with neuroinflammation and decreased expression of neuronal activity marker, which was further exacerbated in the brain of aged animal’s

Additional file 1: of Tissue biodistribution of intravenously administrated titanium dioxide nanoparticles revealed blood-brain barrier clearance and brain inflammation in rat

BBB integrity assessment after IV injection of 10 mg/kg TiO 2 NPs in rats. BBB integrity was estimated by the ratio between atenolol concentrations in brain and plasma (partition coefficient or Kp). Each data point represents the mean ± SD of n = 8 rats. Statistical comparison was performed by two tailed Mann-Whitney test, * P < 0.05. (TIFF 4945 kb

Deciphering neuronal deficit and protein profile changes in human brain organoids from patients with creatine transporter deficiency

International audienceCreatine transporter deficiency (CTD) is an X-linked disease caused by mutations in the SLC6A8 gene. The impaired creatine uptake in the brain results in intellectual disability, behavioral disorders, language delay, and seizures. In this work, we generated human brain organoids from induced pluripotent stem cells of healthy subjects and CTD patients. Brain organoids from CTD donors had reduced creatine uptake compared with those from healthy donors. The expression of neural progenitor cell markers SOX2 and PAX6 was reduced in CTD-derived organoids, while GSK3β, a key regulator of neurogenesis, was up-regulated. Shotgun proteomics combined with integrative bioinformatic and statistical analysis identified changes in the abundance of proteins associated with intellectual disability, epilepsy, and autism. Re-establishment of the expression of a functional SLC6A8 in CTD-derived organoids restored creatine uptake and normalized the expression of SOX2, GSK3β, and other key proteins associated with clinical features of CTD patients. Our brain organoid model opens new avenues for further characterizing the CTD pathophysiology and supports the concept that reinstating creatine levels in patients with CTD could result in therapeutic efficacy