Jacky Fourniat

Bio: Jacky Fourniat is an academic researcher. The author has contributed to research in topics: Lactobacillus acidophilus & Lactobacillus. The author has an hindex of 2, co-authored 2 publications receiving 501 citations.

Adhesion of human Lactobacillus acidophilus strain LB to human enterocyte-like Caco-2 cells

Abstract: Twenty-five strains of lactobacilli were tested for their ability to adhere to human enterocyte-like Caco-2 cells in culture. Seven Lactobacillus strains adhered well to the Caco-2 cells, of which three possessed calcium-independent adhesion properties. A high level of calcium-independent adhesion was observed with the human stool isolate Lactobacillus acidophilus strain LB. Scanning electron microscopy revealed that this strain adhered to the apical brush border of the cells. Adhesion increased in parallel with the morphological and functional differentiation of the Caco-2 cells. Two Lactobacillus components were involved in this adhesion. One was protease-resistant and bacterial-surface-associated; the other was heat-stable, extracellular and protease-sensitive.

Inhibition of adhesion of enteroinvasive pathogens to human intestinal Caco‐2 cells by Lactobacillus acidophilus strain LB decreases bacterial invasion

Abstract: Salmonella typhimurium and enteropathogenic Escherichia coli (EPEC) were found to adhere to the brush border of differentiated human intestinal epithelial Caco-2 cells in culture, whereas Yersinia pseudotuberculosis and Listeria monocytogenes adhered to the periphery of undifferentiated Caco-2 cells All these enterovirulent strains invaded the Caco-2 cells Using a heat-killed human Lactobacillus acidophilus (strain LB) which strongly adheres both to undifferentiated and differentiated Caco-2 cells, we have studied inhibition of cell association with and invasion within Caco-2 cells by enterovirulent bacteria Living and heat-killed Lactobacillus acidophilus strain LB inhibited both cell association and invasion of Caco-2 cells by enterovirulent bacteria in a concentration-dependent manner The mechanism of inhibition of both adhesion and invasion appears to be due to steric hindrance of human enterocytic pathogen receptors by whole-cell lactobacilli rather than to a specific blockade of receptors

Human gut-on-a-chip inhabited by microbial flora that experiences intestinal peristalsis-like motions and flow

Abstract: Development of an in vitro living cell-based model of the intestine that mimics the mechanical, structural, absorptive, transport and pathophysiological properties of the human gut along with its crucial microbial symbionts could accelerate pharmaceutical development, and potentially replace animal testing. Here, we describe a biomimetic ‘human gut-on-a-chip’ microdevice composed of two microfluidic channels separated by a porous flexible membrane coated with extracellular matrix (ECM) and lined by human intestinal epithelial (Caco-2) cells that mimics the complex structure and physiology of living intestine. The gut microenvironment is recreated by flowing fluid at a low rate (30 μL h−1) producing low shear stress (0.02 dyne cm−2) over the microchannels, and by exerting cyclic strain (10%; 0.15 Hz) that mimics physiological peristaltic motions. Under these conditions, a columnar epithelium develops that polarizes rapidly, spontaneously grows into folds that recapitulate the structure of intestinal villi, and forms a high integrity barrier to small molecules that better mimics whole intestine than cells in cultured in static Transwell models. In addition, a normal intestinal microbe (Lactobacillus rhamnosus GG) can be successfully co-cultured for extended periods (>1 week) on the luminal surface of the cultured epithelium without compromising epithelial cell viability, and this actually improves barrier function as previously observed in humans. Thus, this gut-on-a-chip recapitulates multiple dynamic physical and functional features of human intestine that are critical for its function within a controlled microfluidic environment that is amenable for transport, absorption, and toxicity studies, and hence it should have great value for drug testing as well as development of novel intestinal disease models.

Antagonistic activities of lactobacilli and bifidobacteria against microbial pathogens

Abstract: The gastrointestinal tract is a complex ecosystem that associates a resident microbiota and cells of various phenotypes lining the epithelial wall expressing complex metabolic activities. The resident microbiota in the digestive tract is a heterogeneous microbial ecosystem containing up to 1×1014 colony-forming units (CFUs) of bacteria. The intestinal microbiota plays an important role in normal gut function and maintaining host health. The host is protected from attack by potentially harmful microbial microorganisms by the physical and chemical barriers created by the gastrointestinal epithelium. The cells lining the gastrointestinal epithelium and the resident microbiota are two partners that properly and/or synergistically function to promote an efficient host system of defence. The gastrointestinal cells that make up the epithelium, provide a physical barrier that protects the host against the unwanted intrusion of microorganisms into the gastrointestinal microbiota, and against the penetration of harmful microorganisms which usurp the cellular molecules and signalling pathways of the host to become pathogenic. One of the basic physiological functions of the resident microbiota is that it functions as a microbial barrier against microbial pathogens. The mechanisms by which the species of the microbiota exert this barrier effect remain largely to be determined. There is increasing evidence that lactobacilli and bifidobacteria, which inhabit the gastrointestinal microbiota, develop antimicrobial activities that participate in the host's gastrointestinal system of defence. The objective of this review is to analyze the in vitro and in vivo experimental and clinical studies in which the antimicrobial activities of selected lactobacilli and bifidobacteria strains have been documented.

Screening of Probiotic Activities of Forty-Seven Strains of Lactobacillus spp. by In Vitro Techniques and Evaluation of the Colonization Ability of Five Selected Strains in Humans

Abstract: It is well known that the presence of lactobacilli is important for the maintenance of the intestinal microbial ecosystem (39). They have been shown to possess inhibitory activity toward the growth of pathogenic bacteria such as Listeria monocytogenes (3, 25, 36, 42), Escherichia coli, Salmonella spp. (8, 16, 27), and others (4, 13, 37). This inhibition could be due to the production of inhibitory compounds such as organic acids, hydrogen peroxide, bacteriocins (30), or reuterin (4) or to competitive adhesion to the epithelium. In order to survive in and colonize the gastrointestinal tract, probiotic bacteria should express high tolerance to acid and bile and have the ability to adhere to intestinal surfaces (31, 34). Survival in and temporary colonization of the human gastrointestinal tract have been demonstrated for some lactic acid bacteria (1, 23, 29). However, in vivo testing is expensive and time consuming and requires approval by ethical committees. Therefore, reliable in vitro methods for selection of promising strains are required. Enterocyte-like Caco-2 cells (38) have been successfully used for in vitro studies on the mechanism of cellular adhesion of nonpathogenic lactobacilli (10, 24, 40, 43) and bifidobacteria (5, 15). Moreover, this cell line has been used to examine the mechanism of cellular adhesion and invasion of pathogenic bacteria such as L. monocytogenes (21), Salmonella typhimurium (20), and E. coli (32). Recently, Caco-2 cells have been used to examine the antimicrobial activity of lactobacilli (6, 13, 27) and bifidobacteria (5) against pathogenic bacteria. Antimicrobial properties of lactobacilli have been determined by using three methods: inhibitory activity toward the growth of test bacteria in vitro (7, 13, 14), inhibitory activity toward cell association, and invasion of pathogens using cultured human intestinal cells (6, 7, 12–14, 27), as well as protection of conventional or germfree mice against bacterial infection (7, 13, 14, 27). These showed how antimicrobial activities observed by in vitro methods could be confirmed in vivo as well. In the present study, the Caco-2 cell line was used to study the adhesive properties of 47 potentially probiotic cultures in vitro. The cultures were also examined for antimicrobial properties toward pathogenic bacteria along with tolerance to low pH and bile salts. Among these cultures, five promising strains were examined by in vivo studies. The abilities of the selected strains to survive passage through the gastrointestinal tract and maintain colonization was tested in fecal samples using API 50CHL and internal transcribed spacer PCR (ITS-PCR) for primary selection of strains and restriction enzyme analysis (REA) combined with pulsed-field gel electrophoresis (PFGE) for confirmation of isolates recovered from fecal samples during and after administration. It was the main objective of this study to compare the in vitro evaluation of certain properties of various Lactobacillus spp. that are important for their survival in the gastrointestinal tract with their actual ability to survive in vivo.