A Unique Enhancement of Propionibacterium freudenreichii’s Ability to Remove Pb(II) from Aqueous Solution by Tween 80 Treatment
Microbial agents have promise for the bioremediation of Pb(II)-polluted environments and wastewater, the biodecontamination of foods, and the alleviation of toxicity in living organisms. The dairy bacterium Propionibacterium freudenreichii is poorly able to remove Pb(II) from aqueous solution at 25 ppm, ranging from 0 to 10% of initial concentration. Here, we report on an original strong enhancement of this activity (ranging from 75% to 93%, p < 0.01) following the addition of a polysorbate detergent (Tween® 80) during or either shortly after the growth of a P. freudenreichii culture. We evaluated the optimal Tween® 80 concentration for pretreatment conditions, documented the role of other detergents, and explored the possible mechanisms involved. Our results reveal a novel, environmentally friendly, low-cost pretreatment procedure for enhancing the selective removal of lead from water by probiotic-documented bacteria.
Fanny George, Marie Titécat, Nicolas Barois, Catherine Daniel, Anne Garat, Gwénaël Jan and Benoît Foligné
Surface tension of model tissues during malignant transformation and epithelial–mesenchymal transition
Epithelial–mesenchymal transition is associated with migration, invasion, and metastasis. The translation at the tissue scale of these changes has not yet been enlightened while being essential in the understanding of tumor progression. Thus, biophysical tools dedicated to measurements on model tumor systems are needed to reveal the impact of epithelial–mesenchymal transition at the collective cell scale. Herein, using an original biophysical approach based on magnetic nanoparticle insertion inside cells, we formed and flattened multicellular aggregates to explore the consequences of the loss of the metastasis suppressor NME1 on the mechanical properties at the tissue scale. Multicellular spheroids behave as viscoelastic fluids, and their equilibrium shape is driven by surface tension as measured by their deformation upon magnetic field application. In a model of breast tumor cells genetically modified for NME1, we correlated tumor invasion, migration, and adhesion modifications with shape maintenance properties by measuring surface tension and exploring both invasive and migratory potential as well as adhesion characteristics.
Irène Nagle, Alain Richert, Michael Quinteros, Sébastien Janel, Edgar Buysschaert, Nathalie Luciani, Henry Debost, Véronique Thevenet, Claire Wilhelm, Céline Prunier, Frank Lafont, Teresita Padilla-Benavides, Mathieu Boissan and Myriam Reffay
Impact of Collagen Crosslinking on Dislocated Human Shoulder Capsules—Effect on Structural and Mechanical Properties
Classical treatments of shoulder instability are associated with recurrence. To determine whether the modification of the capsule properties may be an alternative procedure, the effect of crosslinking treatment on the structure and mechanical properties of diseased human shoulder capsules was investigated. Joint capsules harvested from patients during shoulder surgery (n = 5) were treated or not with UV and/or riboflavin (0.1%, 1.0% and 2.5%). The structure and the mechanical properties of the capsules were determined by atomic force microscopy. The effect of treatments on cell death was investigated. Collagen fibrils were well-aligned and adjacent to each other with a D-periodicity of 66.9 ± 3.2 nm and a diameter of 71.8 ± 15.4 nm in control untreated capsules. No effect of treatments was observed on the organization of the collagen fibrils nor on their intrinsic characteristics, including D-periodicity or their mean diameter. The treatments also did not induce cell death. In contrast, UV + 2.5% riboflavin induced capsule stiffness, as revealed by the increased Young’s modulus values (p < 0.0001 for each patient). Our results showed that the crosslinking procedure changed the biomechanics of diseased capsules, while keeping their structural organisation unchanged at the single fibril level. The UV/riboflavin crosslinking procedure may be a promising way to preserve the functions of collagen-based tissues and tune their elasticity for clinically relevant treatments. Pauline Cornette, Ilhem Lilia Jaabar, Vincent Dupres, Jean-David Werthel, Francis Berenbaum, Xavier Houard, Jessem Landoulsi and Geoffroy Nourissat
Modulation of designer biomimetic matrices for optimized differentiated intestinal epithelial cultures
The field of intestinal biology is thirstily searching for different culture methods that complement the limitations of organoids, particularly the lack of a differentiated intestinal compartment. While being recognized as an important milestone for basic and translational biological studies, many primary cultures of intestinal epithelium (IE) rely on empirical trials using hydrogels of various stiffness, whose mechanical impact on epithelial orga- nization remains vague until now. Here, we report the development of hydrogel scaffolds with a range of elasticities and their influence on IE expansion, organization, and differentiation. On stiff substrates (>5 kPa), mouse IE cells adopt a flat cell shape and detach in the short-term. In contrast, on soft substrates (80–500 Pa), they sustain for a long-term, pack into high density, develop columnar shape with improved apical-basal polarity and differentiation marker expression, a phenotype reminiscent of features in vivo mouse IE. We then developed a soft gel molding process to produce 3D Matrigel scaffolds of close-to-nature stiffness, which support and maintain a culture of mouse IE into crypt-villus architecture. Thus, the present work is up-to-date informative for the design of biomaterials for ex vivo intestinal models, offering self-renewal in vitro culture that emulates the mouse IE.
Wang Xi, Jad Saleh, Ayako Yamada, Caterina Tomba, Barbara Mercier, Sébastien Janel, Tien Dang, Matis Soleilhac, Aurélie Djemat, Huiqiong Wu, Béatrice Romagnolo, Frank Lafont, René-Marc Mège, Yong Chen, Delphine Delacour
DHA-phospholipids control membrane fusion and transcellular tunnel dynamics
Metabolic studies and animal knockout models point to the critical role of polyunsaturated docosahexaenoic acid (22:6, DHA)-containing phospholipids (PLs) in physiology. Here, we investigated the impact of DHA-PLs on the dynamics of transendothelial cell macroapertures (TEMs) triggered by RhoA inhibition-associated cell spreading. Lipidomic analyses show that human umbilical vein endothelial cells (HUVECs) subjected to DHA-diet undergo a 6-fold enrichment in DHA-PLs at plasma membrane (PM) at the expense of monounsaturated OA-PLs. Consequently, DHA-PLs enrichment at the PM induces a reduction of cell thickness and shifts cellular membranes towards a permissive mode of membrane fusion for transcellular tunnel initiation. We provide evidence that a global homeostatic control of membrane tension and cell cortex rigidity minimizes overall changes of TEM area through a decrease of TEM size and lifetime. Conversely, low DHA-PL levels at the PM leads to the opening of unstable and wider TEMs. Together, this provides evidence that variations of DHA-PLs levels in membranes affect cell biomechanical properties.
Meng-Chen Tsai, Lucile Fleuriot, Sébastien Janel, David Gonzalez-Rodriguez, Camille Morel, Amel Mettouchi, Delphine Debayle, Stéphane Dallongeville, Jean-Christophe Olivo-Marin, Bruno Antonny, Frank Lafont, Emmanuel Lemichez, Hélène Barelli
Interactions of hydrophilic quantum dots with defect-free and defect containing supported lipid membranes
Quantum dots (QDs) are semiconductor nanoparticles with unique optical and electronic properties, whose interest as potential nano-theranostic platforms for imaging and sensing is increasing. The design and use of QDs requires the understanding of cell-nanoparticle interactions at a microscopic and nanoscale level. Model systems such as supported lipid bilayers (SLBs) are useful, less complex platforms mimicking physico-chemical properties of cell membranes. In this work, we investigated the effect of topographical homogeneity of SLBs bearing different surface charge in the adsorption of hydrophilic QDs. Using quartz-crystal microbalance, a label-free surface sensitive technique, we show significant differences in the interactions of QDs onto homogeneous and inhomogeneous SLBs formed following different strategies. Within short time scales, QDs adsorb onto topographically homogeneous, defect-free SLBs is driven by electrostatic interactions, leading to no layer disruption. After prolonged QD exposure, the nanomechanical stability of the SLB decreases suggesting nanoparticle insertion. In the case of inhomogeneous, defect containing layers, QDs target preferentially membrane defects, driven by a subtle interplay of electrostatic and entropic effects, inducing local vesicle rupture and QD insertion at membrane edges.
L.Bar, F.Perissinotto, L.Redondo-Morata, M.I.Giannotti, J.Goole, P.Losada-Pérez
Cell monolayers sense curvature by exploiting active mechanics and nuclear mechanoadaptation
The early development of many organisms involves the folding of cell monolayers, but this behaviour is difficult to reproduce in vitro; therefore, both mechanistic causes and effects of local curvature remain unclear. Here we study epithelial cell monolayers on corrugated hydrogels engineered into wavy patterns, examining how concave and convex curvatures affect cellular and nuclear shape. We find that substrate curvature affects monolayer thickness, which is larger in valleys than crests. We show that this feature generically arises in a vertex model, leading to the hypothesis that cells may sense curvature by modifying the thickness of the tissue. We find that local curvature also affects nuclear morphology and positioning, which we explain by extending the vertex model to take into account membrane–nucleus interactions, encoding thickness modulation in changes to nuclear deformation and position. We propose that curvature governs the spatial distribution of yes-associated proteins via nuclear shape and density changes. We show that curvature also induces significant variations in lamins, chromatin condensation and cell proliferation rate in folded epithelial tissues. Together, this work identifies active cell mechanics and nuclear mechanoadaptation as the key players of the mechanistic regulation of epithelia to substrate curvature.
Marine Luciano, Shi-Lei Xue, Winnok H. De Vos, Lorena Redondo-Morata, Mathieu Surin, Frank Lafont, Edouard Hannezo & Sylvain Gabriele
Adherent-Invasive and Non-Invasive Escherichia coli Isolates Differ in Their Effects on Caenorhabditis elegans’ Lifespan
Le pathotype Escherichia coli adhérent-invasif (AIEC) a été impliqué dans la pathogenèse des maladies inflammatoires de l’intestin en général et dans la maladie de Crohn (MC) en particulier. Les souches AIEC sont principalement caractérisées par leur capacité à adhérer aux cellules épithéliales intestinales et à les envahir. Cependant, les caractéristiques génétiques et phénotypiques des isolats d’AIEC varient considérablement en fonction de la clonalité de la souche, des facteurs de l’hôte et du microenvironnement intestinal. Il est donc essentiel d’identifier les déterminants de la pathogénicité des AIEC et de comprendre leur rôle dans le dysfonctionnement de la barrière épithéliale intestinale et l’inflammation. Nous avons pensé que le nématode du sol Caenorhabditis elegans (un modèle simple mais puissant d’interactions hôte-bactérie) pourrait être utilisé pour étudier la virulence des souches d’E. coli AIEC par rapport aux souches non AIEC. En effet, nous avons constaté que la colonisation de C. elegans (souche N2) par E. coli avait un impact sur la survie d’une manière spécifique à la souche. De plus, la capacité des souches AIEC à envahir les cellules in vitro était liée à la durée de vie médiane de C. elegans (souche PX627). Cependant, ni le caractère invasif intrinsèque d’E. coli (c’est-à-dire le fait pour une souche individuelle d’être caractérisée comme invasive ou non) ni les niveaux de virulence des AIEC (c’est-à-dire l’intensité de l’invasion, établie en % de l’inoculum infectieux) dans les cellules épithéliales intestinales n’ont été corrélés à la durée de vie de C. elegans dans l’essai de destruction. Néanmoins, la longévité des AIEC de C. elegans pourrait être un modèle pertinent pour le criblage de médicaments anti-adhésion et de probiotiques anti-invasifs.
Maria Beatriz de Sousa Figueiredo, Elizabeth Pradel, Fanny George, Séverine Mahieux, Isabelle Houcke, Muriel Pottier, Chantal Fradin, Christel Neut, Catherine Daniel, Antonino Bongiovanni, Benoît Foligné, and Marie Titécat
Persistence and dynamics of fluorescent Lactobacillus plantarum in the healthy versus inflamed gut
The gastrointestinal tract is the main ecological niche in which Lactobacillus strains may provide health benefits in mammals. There is currently a need to characterize host-microbe interactions in space and time by tracking these bacteria in vivo. We combined noninvasive whole-body imaging with ex vivo fluorescence confocal microscopy imaging to monitor the impact of intestinal inflammation on the persistence of orally administered Lactobacillus plantarum NCIMB8826 in healthy and inflamed mouse colons. We developed fluorescent L. plantarum strains and demonstrated that mCherry is the best system for in vivo imaging and ex vivo fluorescence confocal microscopy of these bacteria. We also used whole-body imaging to show that this anti-inflammatory, orally administered strain persists for longer and at higher counts in the inflamed colon than in the healthy colon. We confirmed these results by the ex vivo confocal imaging of colons from mice with experimental colitis for 3 days after induction. Moreover, extended orthogonal view projections enabled us to localize individual L. plantarum in sites that differed for healthy versus inflamed guts. In healthy colons, orally administered bacteria were localized in the lumen (in close contact with commensal bacteria) and sometimes in the crypts (albeit very rarely in contact with intestinal cells). The bacteria were observed within and outside the mucus layer. In contrast, L. plantarum bacteria in the inflamed colon were mostly located in the lumen and (in less inflamed areas) within the mucus layer. In more intensely inflamed areas (i.e., where the colon had undergone structural damage), the L. plantarum were in direct contact with damaged epithelial cells. Taken as a whole, our results show that fluorescently labeled L. plantarum can be used to study the persistence of these bacteria in inflamed guts using both noninvasive whole-body imaging and ex vivo fluorescence confocal microscopy.
Salomé-Desnoulez S, Poiret S, Foligné B, Muharram G, Peucelle V, Lafont F & Daniel C.
Assessment of Pb(II), Cd(II), and Al(III) Removal Capacity of Bacteria from Food and Gut Ecological Niches: Insights into Biodiversity to Limit Intestinal Biodisponibility of Toxic Metals
Published: 22 February 2021, Microorganisms
Toxic metals (such as lead, cadmium, and, to a lesser extent, aluminum) are detrimental to health when ingested in food or water or when inhaled. By interacting with heavy metals, gut and food-derived microbes can actively and/or passively modulate (by adsorption and/or seques- tration) the bioavailability of these toxins inside the gut. This “intestinal bioremediation” involves the selection of safe microbes specifically able to immobilize metals. We used inductively coupled plasma mass spectrometry to investigate the in vitro ability of 225 bacteria to remove the potentially harmful trace elements lead, cadmium, and aluminum. Interspecies and intraspecies comparisons were performed among the Firmicutes (mostly lactic acid bacteria, including Lactobacillus spp., with some Lactococcus, Pediococcus, and Carnobacterium representatives), Actinobacteria, and Proteobac- teria. The removal of a mixture of lead and cadmium was also investigated. Although the objective of the study was not to elucidate the mechanisms of heavy metal removal for each strain and each metal, we nevertheless identified promising candidate bacteria as probiotics for the intestinal bio- remediation of Pb(II) and Cd(II).
Fanny George, Séverine Mahieux, Catherine Daniel, Marie Titécat, Nicolas Beauval, Isabelle Houcke, Christel Neut, Delphine Allorge, Frédéric Borges, Gwénaël Jan, Benoît Foligné and Anne Garat