Predicting toxic effects observed in vivo after acute exposure to poorly soluble and inhalable nanomaterials by using more complex in vitro models

International audienceAnimal models are powerful tools to predict potential adverse effects in human after inhalation of Nanomaterials (NM), because of similar levels of complexity. Nevertheless, considering the number of poorly soluble NM used and their physicochemical diversity, it seems difficult to rely only on animal experimentation. In vitro studies represent alternatives to assess acute toxicity after inhalation. In vitro, cells in monoculture are usually exposed to suspensions of NM, to study mechanisms of toxicity or because they are cheaper and easier to implement than in vivo studies. However, using too simple experimental conditions does not allow mimicking accurately the complexity of interactions occurring between particles and lungs in the human body. Moreover, in submerged conditions, particles may interact with some components of the culture medium, resulting in the formation of a specific corona, which may modify cell-particle interactions. In this context, the general aim of our work was to assess if using more complex in vitro method, by exposing alveolar cells in monoculture or co-culture at the Air Liquid Interface (ALI) to aerosols of poorly soluble NM, better simulates adverse effects observed in vivo. Animal and cell models were exposed to TiO2 (NM105: 21 nm, NM101: 6 nm, NM100: 100 nm) and CeO2 (NM212: 28 nm) NM. In vitro, alveolar epithelial cells in monoculture (A549) or in co-culture with alveolar macrophages (A549 + THP-1) were exposed either at the ALI to aerosols, or in submerged condition to suspensions. The real mass deposited on cells in vitro was either assessed by direct dosage (ALI exposures) or estimated using the in vitro sedimentation diffusion and dosimetry (ISDD) model, after measuring the hydrodynamic diameter and the effective density of agglomerates. In vivo, rats were exposed by intratracheal instillation. Deposition on cells in vivo was assessed by dividing the lung charge by the alveolar surface. Biological activity (viability, oxidative stress and inflammation) was assessed at 24h, in vitro on cells and in vivo on bronchoalveolar lavage fluids. Doses were expressed in mass/surface to allow in vitro /in vivo comparisons. According to our results, pro-inflammatory effects were the most relevant biological markers, to compare in vitro and in vivo results after 24h exposure. In vitro, co-cultures appeared more sensitive than mono-cultures. We observed significant effects for all NM and at lower doses when cells were exposed at the ALI to aerosols compared to suspensions. Moreover in vitro, NM101 and NM105 appeared more toxic than NM100 and NM212. In vivo, we observed significant adverse effects for TiO2 NM101 and NM105 and CeO2 NM212, but not with TiO2 NM100. These effects were observed at lower doses than in vitro. In vivo results are in agreement with literature observation where toxic effects observed are dependent on NM size. Both in vivo and in vitro, TiO2 nanomaterials were ranked similarly in function of toxic effects observed and whatever the exposure method used. However, CeO2 was ranked differently in vivo compared to in vitro. In conclusion, we showed that in vitro methods could be used for the relative ranking of TiO2 NM, and we propose the hypothesis that in vitro methods could be used also for the ranking of poorly soluble NM of similar chemical form. We also showed that ALI method seems to better simulate in vivo adverse effects regarding biological activation levels

Air-liquid interface exposure to aerosols of poorly soluble nanomaterials induces different biological activation levels compared to exposure to suspensions

Background: Recently, much progress has been made to develop more physiologic in vitro models of the respiratory system and improve in vitro simulation of particle exposure through inhalation. Nevertheless, the field of nanotoxicology still suffers from a lack of relevant in vitro models and exposure methods to predict accurately the effects observed in vivo, especially after respiratory exposure. In this context, the aim of our study was to evaluate if exposing pulmonary cells at the air-liquid interface to aerosols of inhalable and poorly soluble nanomaterials generates different toxicity patterns and/or biological activation levels compared to classic submerged exposures to suspensions. Three nano-TiO2 and one nano-CeO2 were used. An exposure system was set up using VitroCell® devices to expose pulmonary cells at the air-liquid interface to aerosols. A549 alveolar cells in monocultures or in co-cultures with THP-1 macrophages were exposed to aerosols in inserts or to suspensions in inserts and in plates. Submerged exposures in inserts were performed, using similar culture conditions and exposure kinetics to the air-liquid interface, to provide accurate comparisons between the methods. Exposure in plates using classical culture and exposure conditions was performed to provide comparable results with classical submerged exposure studies. The biological activity of the cells (inflammation, cell viability, oxidative stress) was assessed at 24 h and comparisons of the nanomaterial toxicities between exposure methods were performed.Results: Deposited doses of nanomaterials achieved using our aerosol exposure system were sufficient to observe adverse effects. Co-cultures were more sensitive than monocultures and biological responses were usually observed at lower doses at the air-liquid interface than in submerged conditions. Nevertheless, the general ranking of the nanomaterials according to their toxicity was similar across the different exposure methods used.Conclusions: We showed that exposure of cells at the air-liquid interface represents a valid and sensitive method to assess the toxicity of several poorly soluble nanomaterials. We underlined the importance of the cellular model used and offer the possibility to deal with low deposition doses by using more sensitive and physiologic cellular models. This brings perspectives towards the use of relevant in vitro methods of exposure to assess nanomaterial toxicity

Study of TiO2 P25 Nanoparticles Genotoxicity on Lung, Blood, and Liver Cells in Lung Overload and Non-Overload Conditions After Repeated Respiratory Exposure in Rats

International audienceInhaled titanium dioxide (TiO2) nanoparticles (NPs) can have negative health effects, and have been shown to cause respiratory tract cancer in rats. Inflammation has been linked to oxidative stress, and both have been described as possible mechanisms for genotoxicity of NPs, but rarely examined side-by-side in animal studies. In the present study, a wide range of complementary endpoints have been performed to study TiO2 P25 NP-induced genotoxicity in lung overload and non-overload conditions. Additionally, lung burden, inflammation, cytotoxicity and oxidative stress have also been evaluated in order to link genotoxicity with these responses. To assess quick and delayed responses after recovery, endpoints were evaluated at two time points: 2 h and 35 days after three repeated instillations. This study confirmed the previously described lung overload threshold at approximately 200-300 cm2 of lung burden for total particle surface area lung deposition or 4.2 µl/kg for volume-based cumulative lung exposure dose, above which lung clearance is impaired and inflammation is induced. Our results went on to show that these overload doses induced delayed genotoxicity in lung, associated with persistent inflammation only at the highest dose. The lowest tested doses had no toxicity or genotoxicity effects in the lung. In blood, no lymphocyte DNA damage, erythrocytes chromosomal damage or gene mutation could be detected. Our data also demonstrated that only overload doses induced liver DNA lesions irrespective of the recovery time. Tested doses of TiO2 P25 NPs did not induce glutathione changes in lung, blood or liver at both recovery times

Les chemins de Saint-Jacques à l’épreuve des temps

À un moment où nombre de biens patrimoniaux sont bousculés par des interrogations multiples (rentabilité des investissements consentis ; possibles dégradations et mise en danger de l’intégrité du bien ; remise en cause de tel ou tel critère matériel et/ou immatériel, …) il semble très pertinent de se livrer à un examen serré de ce qui justement fait la singularité de ce bien dans le paysage certes géographique, mais aussi juridique, historique, économique et sociétal. Les Chemins sont très largement dans leur acception actuelle une re-découverte et reconstruction de la dernière génération – la nôtre – en lien avec des problématiques de voyage ; de découverte y compris de la « Nature » ; de valorisation adaptées à un cheminement maîtrisé. De la sorte, le bien est abordé sous tous ses aspects : physique (les tracés ; les variations de ces tracés ; les usages et leur hiérarchie ; leur inscription durable dans la trame du paysage, …), juridique (la pérennité d’une possible circulation dans un espace quadrillé par les itinéraires goudronnés, …), sociétal (le retour des marcheurs/ou autres modes de parcours de mobilité douce ; l’activation des circuits d’un nouvel imaginaire appuyé sur les traditions et les vecteurs de l’idéel…). Le colloque a abordé plusieurs thèmes comme par exemple la reconnaissance juridique des chemins de randonnée, le régime juridique des chemins de randonnée pédestre, les conflits d’usage – existe-t-il un droit de la promenade ou à la promenade ?, la continuité des itinéraires et le droit de propriété, la police et la responsabilité relatives aux conditions d’utilisation des chemins inscrits

ELA/APELA precursor cleaved by furin displays tumor suppressor function in renal cell carcinoma through mTORC1 activation

International audienc

Inactivation of Proprotein Convertases in T Cells Inhibits PD-1 Expression and Creates a Favorable Immune Microenvironment in Colorectal Cancer

International audienc

Niche-expressed Galectin-1 is involved in pre-B acute lymphoblastic leukemia relapse through pre-B cell receptor activation

B-cell acute lymphoblastic leukemia (B-ALL) reflects the malignant counterpart of developing B cells in the bone marrow (BM). Despite tremendous progress in B-ALL treatment, the overall survival of adults at diagnosis and patients at all ages after relapse remains poor. Galectin-1 (GAL1) expressed by BM supportive niches delivers proliferation signals to normal pre-B cells through interaction with the pre-B cell receptor (pre-BCR). Here, we asked whether GAL1 gives non-cell autonomous signals to pre-BCR+ pre-B ALL, in addition to cell-autonomous signals linked to genetic alterations. In syngeneic and patient-derived xenograft (PDX) murine models, murine and human pre-B ALL development is influenced by GAL1 produced by BM niches through pre-BCR-dependent signals, similarly to normal pre-B cells. Furthermore, targeting pre-BCR signaling together with cell-autonomous oncogenic pathways in pre-B ALL PDX improved treatment response. Our results show that non-cell autonomous signals transmitted by BM niches represent promising targets to improve B-ALL patient survival

J Infect

Background In France about 32% of hospitalized patients have a vascular access placement. However, a common complication associated with these is catheter-related bloodstream infection (CRBI) due to the introduction of microorganisms from the skin during catheter insertion. There is no consensus on the best way to clean the skin prior to catheter insertion, which could be a key element of CRBI prevention. The two techniques most commonly used to apply antiseptic to the skin are the concentric circle and back-and-forth techniques, but these have not been compared in clinical trials. Hence, this study conducted this comparison. Methods This single-center, non-comparative, randomized, matched pilot study investigated the levels of cutaneous microorganisms before and after antiseptic application using both techniques in a population of healthy French volunteers. The two application methods were used on each participant's arms at the elbow fold, with randomization for the application side (right or left). Quantification of cutaneous microorganisms was performed in a blinded manner with regard to the technique used. Findings From April 8 to July 17, 2019, 132 healthy volunteers participated in the study. For the whole study population, the mean initial colonization level was 2.68 log10 colony forming units (CFU)/mL (SD 0.82) before the back-and-forth technique, and 2.66 log10 CFU/mL (SD 0.85) before the concentric circle technique. The mean differences in number of microorganisms between the initial sample and the final sample were 2.45 log10 CFU/mL (95% CI: 2.29 to 2.61) for the back-and-forth technique and 2.43 log10 CFU/mL (95% CI: 2.27 to 2.59) for the concentric circle technique. The mean difference in reduction in microorganisms between the back-and-forth technique and the concentric circle technique was 0.02 log10 CFU/mL (95% CI: –0.11 to 0.15). Interpretation There was no clinically difference in reduction of microorganisms between the concentric circle and back-and-forth techniques at the bend of the healthy volunteer's elbow, after the 30 s of drying of the antiseptic. These findings have a significant impact on time required to achieve antiseptic application before catheter insertion because there is yet no argument to justify application for 30 s, because a single concentric circle pass was much faster with similar results. Future studies should investigate the impact of skin application technique on the prevention of infectious risk associated with catheter insertion on admission to health care facilities (conventional, outpatient, or emergency) and throughout the period of stay in a health care facility