Effets des sécrétomes de Staphylococcus aureus et Staphylococcus epidermidis du microbiote cutané d'enfants atopiques sur la réponse immunitaire T CD4

La dermatite atopique (DA) est une maladie inflammatoire et prurigineuse de la peau, très fréquente chez les enfants et dont la prévalence augmente dans les pays industrialisés. La physiopathologie complexe de cette maladie met en jeu un défaut de la barrière cutanée et/ou des défauts génétiques résultant en une hypersensibilité aux allergènes de l'environnement tels que ceux issus d'acariens. Récemment, des études sur les interactions entre le système immunitaire et les bactéries commensales et pathogènes de la peau ont révélé leur importance dans cette maladie. Pour étudier le rôle du microbiote cutané dans la réponse T CD4+, des cohortes de jeunes enfants, atteints de DA et sensibilisés aux allergènes d'acariens (Der p) ou non DA (population contrôle), ont été recrutées. L'analyse du microbiote (MALDI-TOF) et du profil transcriptomique cutanés, ainsi que la quantification des T CD4+ anti-Derp (ELISpot) ont montré que la présence de S. aureus sur la peau inflammatoire des sujets AD était associée à des taux élevés d'IgE, des transcrits caractéristiques d'une orientation Th2/Th22 et à une réponse périphérique Th2. Des cellules dendritiques dérivées de monocytes (moDC) de donneurs sains produisent respectivement de l'IFN-gamma et de l'IL-10 en présence de sécrétomes issus de souches de S. aureus et S. epidermidis provenant de patients. La prolifération de lymphocytes T CD4+ stimulés avec des moDC allogéniques traitées avec le sécrétome de S. aureus est atténuée par le traitement simultané des moDC avec le sécrétome de S. epidermidis. Les sécrétomes de S. aureus sont capables d'inhiber directement l'activité suppressive de lymphocytes T régulateurs en l'absence de cellule présentatrice d'antigène. L'ensemble de nos résultats nous permet de penser que S. aureus est un facteur pro-inflammatoire de la DA en exacerbant la prolifération de lymphocytes Th2 résidents et en inhibant la fonction des lymphocytes T régulateurs. Favoriser les effets anti-inflammatoires des bactéries commensales telles que S. epidermidis liés à l'induction d'une sécrétion d'IL-10 par les cellules dendritiques de la peau pourrait bénéficier aux patients atteints de DA.Atopic dermatitis (AD) is an inflammatory and pruritic skin disease frequently affecting children. Its prevalence is increasing in industrialized countries. Its complex pathophysiology involves a skin barrier dysfunction and/or genetic abnormalities leading to sensitivity to environmental allergens such as house dust mites. Interactions between the immune system and skin bacteria, pathogens and commensals, appeared to be important in the disease. To study the influence of skin microbiota in the CD4+ T cell response, we designed a cohort of young AD children sensitized to house dust mite allergens (Der p) and their counterparts (controls). Analysis of skin microbiota (MALDI-TOF), transcripts profiling and quantification of anti-Der p CD4+ T cells showed that the presence of S. aureus on inflamed skin of AD subjects was associated with high IgE levels, Th2/Th22 transcripts and peripheral Th2 anti-Der p response. Monocyte-derived dendritic cells (moDC) were exposed to secretomes produced by S. aureus and S. epidermidis strains isolated from patients and released IFN-gamma and IL-10 respectively. Proliferation of CD4+ T cells induced by allogeneic moDC exposed to S. aureus secretome was blunted by concurrent exposure of moDC to S. epidermidis secretome. Regulatory T cells (Treg) lost their activity against conventional CD4+ T cells under the direct effect of S. aureus secretome. Overall, these results allow us to think that S. aureus is an important factor of the AD inflammation by inducing Th2 activation and silencing resident Treg. Commensals such as S. epidermidis could be used to counteract these effects by inducing IL-10 production by skin DC

Assessment of durability of biobased earth composites

Bio-based earth composites present various environmental benefits, such as usable wastes, coproducts, abundant or renewable materials, etc. Moreover, the incorporation of bioaggregates in the earth matrix allows the buildings to act as an effective carbon sink. A growing number of studies are now focusing on the mechanical and hygrothermal properties of bio-based earth building materials. However, the durability of these types of material is a major concern, and knowledge of their various aspects is essential to anticipate maintenance and sustain the performance levels. Here, the durability of compressed earth composites, valorizing discarded earth containing 3% of barley straw, hemp shiv, or rice husk, is investigated. Due to the lack of internationally recognized standards to assess the durability of earthen materials and products, we proposed some testing procedures and discussed their relevance. The addition of these three bioaggregates decreases stiffness, as estimated by ultrasound velocity, and improves the resistance to impact and erosion by water. However, water absorption under low pressure is increased, and dry abrasion resistance is decreased. Moreover, the rice husk composite presents the best compromise.publishersversionpublishe

Re-Baling Straw For Better Insulation

Agricultural straw bales, produced as a co-product of cereal crops such as wheat and rice, have been used in construction worldwide for over 100 years, but despite their favourable low environmental impact, sustainable supply chain, and good thermal insulation properties their use has remained largely niche compared with other competing products. However, straw bales have remained sub-optimal for building performance or practically for construction. The current study seeks to improve the insulation qualities of straw by manufacturing bales specifically for construction applications, with the straw stems oriented to maximise available thermal resistance. Technical development and characterisation of an insulating material produced from wheat straw, for use in conjunction with typical timber-framed construction for example, is reported. The paper describes aspects of developing an insulating prototype made from wheat straw, where the thermal properties relative to the orientation of the straw are investigated. Straw orientations other than that produced by traditional baling equipment, and on a scale designed for ease in construction use, require modified equipment. The design and development of small-scale baling equipment for the laboratory is presented. A series of small-scale thermal conductivity tests demonstrate the potential for improved performance through consideration of various straw orientations. Controlling the orientation of the individual straws results in improved thermal resistance, allowing thinner walls than conventional agricultural bales. Straw needs to be baled to specific thicknesses to support uptake in wider construction. With the capability of re-baling the straw into desirable dimensions, the overall width and length of a straw bale can be designed to fit with standard construction. This research will enable greater uptake of a novel low embodied carbon bio-based material into mainstream construction.<br/

Dynamic behaviour of bio-based and recycled materials for indoor environmental comfort

UK construction industry contributes 120 Mt of waste every year. Bio-based building materials may be a solution for this problem, as they combine re-use and recycling abilities together with hygroscopic characteristics, leading to buildings energy savings. For the first time, the dynamic response to hygrothermal changes of bio-based materials is examined in terms of Moisture Buffering Value (MBV), dry/wet thermal conductivity, microstructure, density and latent heat through daily cycles. It is shown that MBV is a useful tool for characterisation but needs to be combined with the shape of the change in mass of the final hygrothermal cycle. Mastering this is required to obtain significant improved indoor environment quality in buildings. Ten samples of bio-based insulation materials and one thermoplastic recycled polymer were analysed (wool, hemp, saw mill residue, wood, straw, cork and polyethylene terephthalate). Saw and wool are the most promising, as materials exhibit dynamic response to hygrothermal changes. Only half the amount of samples revealed equivalent efficient moisture transfer to be able to desorb the adsorbed quantity of water. Latent heat of vaporisation and condensation tests led to the conclusion that samples of wool and saw mill residue can qualify as bio-based materials for ‘green’ panels

Effects of staphylococcus aureus and staphylococcus epdidermidis secretomes from skin microbiota of atopic children on CD4T cell activation

La dermatite atopique (DA) est une maladie inflammatoire et prurigineuse de la peau, très fréquente chez les enfants et dont la prévalence augmente dans les pays industrialisés. La physiopathologie complexe de cette maladie met en jeu un défaut de la barrière cutanée et/ou des défauts génétiques résultant en une hypersensibilité aux allergènes de l'environnement tels que ceux issus d'acariens. Récemment, des études sur les interactions entre le système immunitaire et les bactéries commensales et pathogènes de la peau ont révélé leur importance dans cette maladie. Pour étudier le rôle du microbiote cutané dans la réponse T CD4+, des cohortes de jeunes enfants, atteints de DA et sensibilisés aux allergènes d'acariens (Der p) ou non DA (population contrôle), ont été recrutées. L'analyse du microbiote (MALDI-TOF) et du profil transcriptomique cutanés, ainsi que la quantification des T CD4+ anti-Derp (ELISpot) ont montré que la présence de S. aureus sur la peau inflammatoire des sujets AD était associée à des taux élevés d'IgE, des transcrits caractéristiques d'une orientation Th2/Th22 et à une réponse périphérique Th2. Des cellules dendritiques dérivées de monocytes (moDC) de donneurs sains produisent respectivement de l'IFN-gamma et de l'IL-10 en présence de sécrétomes issus de souches de S. aureus et S. epidermidis provenant de patients. La prolifération de lymphocytes T CD4+ stimulés avec des moDC allogéniques traitées avec le sécrétome de S. aureus est atténuée par le traitement simultané des moDC avec le sécrétome de S. epidermidis. Les sécrétomes de S. aureus sont capables d'inhiber directement l'activité suppressive de lymphocytes T régulateurs en l'absence de cellule présentatrice d'antigène. L'ensemble de nos résultats nous permet de penser que S. aureus est un facteur pro-inflammatoire de la DA en exacerbant la prolifération de lymphocytes Th2 résidents et en inhibant la fonction des lymphocytes T régulateurs. Favoriser les effets anti-inflammatoires des bactéries commensales telles que S. epidermidis liés à l'induction d'une sécrétion d'IL-10 par les cellules dendritiques de la peau pourrait bénéficier aux patients atteints de DA.Atopic dermatitis (AD) is an inflammatory and pruritic skin disease frequently affecting children. Its prevalence is increasing in industrialized countries. Its complex pathophysiology involves a skin barrier dysfunction and/or genetic abnormalities leading to sensitivity to environmental allergens such as house dust mites. Interactions between the immune system and skin bacteria, pathogens and commensals, appeared to be important in the disease. To study the influence of skin microbiota in the CD4+ T cell response, we designed a cohort of young AD children sensitized to house dust mite allergens (Der p) and their counterparts (controls). Analysis of skin microbiota (MALDI-TOF), transcripts profiling and quantification of anti-Der p CD4+ T cells showed that the presence of S. aureus on inflamed skin of AD subjects was associated with high IgE levels, Th2/Th22 transcripts and peripheral Th2 anti-Der p response. Monocyte-derived dendritic cells (moDC) were exposed to secretomes produced by S. aureus and S. epidermidis strains isolated from patients and released IFN-gamma and IL-10 respectively. Proliferation of CD4+ T cells induced by allogeneic moDC exposed to S. aureus secretome was blunted by concurrent exposure of moDC to S. epidermidis secretome. Regulatory T cells (Treg) lost their activity against conventional CD4+ T cells under the direct effect of S. aureus secretome. Overall, these results allow us to think that S. aureus is an important factor of the AD inflammation by inducing Th2 activation and silencing resident Treg. Commensals such as S. epidermidis could be used to counteract these effects by inducing IL-10 production by skin DC

Influence of sunflower stalks processing parameters on the properties of pith insulating materials

International audienc

Characterization of Barley Straw, Hemp Shiv and Corn Cob as Resources for Bioaggregate Based Building Materials

International audience12 Expanding the use of low-environmental impact materials in the field of building materials is a 13 major aim in a context of sustainable development. These alternative materials should be 14 non-polluting, eventually recycled, and locally available. Bioresources are already used in 15 some building materials but few studies have investigated their relevance in such 16 applications. The aim of this paper is to evaluate the suitability of three kinds of vegetal 17 aggregates: barley straw, hemp shiv and corn cob. The availability of these bioresources, 18 extracted from a French database, is discussed, as are their physical properties and 19 chemical compositions. Their microstructure is described with SEM images and their particle 20 size distributions are provided through image analysis. Sorption-desorption isotherms are 21 measured by a Dynamic Vapour Sorption system. Bulk density, thermal conductivity and 22 water absorption are also quantified. The results highlight a tubular structure for the three 23 different aggregates, with low bulk density and thermal conductivity (0.044, 0.051 and 0.096 24 W.m-1 .K-1 respectively for straw, hemp shiv and corn cob) and high water absorption, 25 especially for barley straw and hemp shiv (414 and 380% vs. 123% for corn cob). Their 26 hygric regulation capacity is also sufficiently good, with a water sorption of between 20 and 27 26% at 95% of relative humidity. These plant aggregates could therefore be used as 28 additions in an earth matrix, or a hydraulic, pozzolanic, air lime or gypsum binder, or just as 29 loose-fill insulation material. However, future research should focus on their resistance to fire 30 and bacterial growth to validate this approach. 31 3

Re-baling straw for better insulation

International audienceAgricultural straw bales, produced as a co-product of cereal crops such as wheat and rice, have been used in construction worldwide for over 100 years, but despite their favourable low environmental impact, sustainable supply chain, and good thermal insulation properties their use has remained largely niche compared with other competing products. However, straw bales have remained sub-optimal for building performance or practically for construction. The current study seeks to improve the insulation qualities of straw by manufacturing bales specifically for construction applications, with the straw stems oriented to maximise available thermal resistance. Technical development and characterisation of an insulating material produced from wheat straw, for use in conjunction with typical timber-framed construction for example, is reported. The paper describes aspects of developing an insulating prototype made from wheat straw, where the thermal properties relative to the orientation of the straw are investigated. Straw orientations other than that produced by traditional baling equipment, and on a scale designed for ease in construction use, require modified equipment. The design and development of small-scale baling equipment for the laboratory is presented. A series of small-scale thermal conductivity tests demonstrate the potential for improved performance through consideration of various straw orientations. Controlling the orientation of the individual straws results in improved thermal resistance, allowing thinner walls than conventional agricultural bales. Straw needs to be baled to specific thicknesses to support uptake in wider construction. With the capability of re-baling the straw into desirable dimensions, the overall width and length of a straw bale can be designed to fit with standard construction. This research will enable greater uptake of a novel low embodied carbon bio-based material into mainstream construction