Role of Adhesion Molecules in the Mechanism of Non-MHC (Major Histocompatibility Complex) Restricted Cell-Mediated Cytotoxicity

Adhesion molecules involved in the interaction between immune system effector cells and tumor targets are surface molecules which contribute to the formation of cell-to-cell contacts and belong to the integrin family. In this paper, the role played by the adhesion molecules in the process of cell-mediated cytotoxicity is reviewed. Furthermore, the contact area between effector and target cells has been analyzed by scanning electron microscopy. This region, termed closed chamber , seems to contribute to killing efficiency by creating an intimate contact region in which cytotoxic factors can easily induce lethal hit in target cell. Thus, the extension of the closed chamber seems to be positively related to effector cell killing potential as well as to target cell sensitivity and, in this context, the adhesion molecules prove to play a pivotal role. In fact, a receptor-ligand interaction occurs between CD11a/CD18 (LFA-1) and CD2 molecules, expressed on the effector cells, and the respective counterparts on target cells, i.e., ICAM-1, ICAM-2, or LFA-3. Treatment with antibodies against such molecules strongly modifies closed chamber formation without inhibiting cell-to-cell binding. Nevertheless, in these conditions, the killing ability of different effector cells toward tumor targets appears to be strongly impaired. Hence, the adhesion molecules seem to be strongly involved in the formation of the closed chamber as well as in the activation of effector cell killing machinery

A Scanning Electron Microscopy Analysis of Human Cytotoxic Cell Subsets and of Their Mode of Conjugation with Tumor Cell Targets

In this study we describe the surface features of non-MHC (Major Histocompatibility Complex)-restricted cytotoxic cells isolated from human peripheral blood. Purified populations of CD3-, natural killer (NK) cells were allowed to interact with NK-sensitive (K562) and NK-resistant (THP-1-0) tumor cell targets. The type of effector to target cell binding was investigated by scanning electron microscope (SEM) analysis. A different interaction with the effectors is described for NK-resistant targets in comparison with NK-susceptible tumor cells. SEM was also used to investigate the relationship between interleukin 2 (IL2)-activated cytotoxic cells (lymphokine-activated killer, LAK, cells) and the tumor targets. We also describe the unique growth features of certain clones of cytotoxic T cells expressing γδ antigen receptors which support the contention that these cells may have a special ability of homing into tissues. We conclude that non-specific cytotoxic cells constitute a diverse population of effectors which differ not only for the expression of surface antigens, but also for their ability to interact with tumor cell targets and to home into the peripheral tissues where they may exert their lytic functions

WITHDRAWN: Electrogenic and hydrocarbonoclastic biofilm at the oil-water interface as microbial responses to oil spill

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Bovine lactoferrin interacts with cable pili of Burkholderia cenocepacia

In this study we evaluated the ability of lactoferrin, the most abundant antimicrobial protein in airway secretions, to bind the surface structures of a Burkholderia strain cystic fibrosis-isolated. Burkholderia cenocepacia is a gram-negative bacterium involved as respiratory pathogen in cystic fibrosis patient infections. This bacterium possesses filamentous structures, named cable pili that have been proposed as virulence factors because of their ability to bind to respiratory epithelia and mucin. Previously, we demonstrated that bovine lactoferrin was able to influence the efficiency of invasion of different iron-regulated morphological forms of B. cenocepacia. Bovine lactoferrin showed to efficiently inhibit invasion of alveolar epithelial cells by free-living bacteria or iron-induced aggregates or biofilm. Results of the present study demonstrate that bovine lactoferrin is also able to specifically bind to B. cenocepacia cells and show that cable pili are involved in this interaction. The attachment of bovine lactoferrin to pili led to a reduced binding of bacterial cells to mucin. Since cable pili are implicated in mediating the bacterial interactions with mucin and epithelial cells, lactoferrin binding to these structures could play an important role in neutralizing bacterial infection in cystic fibrosis patients

Towards the Standardization of Intestinal In Vitro Advanced Barrier Model for Nanoparticles Uptake and Crossing: The SiO₂ Case Study

Increasing interest is being addressed to the development of a reliable, reproducible and relevant in vitro model of intestinal barrier, mainly for engineered nanomaterials hazard and risk assessment, in order to meet regulatory and scientific demands. Starting from the consolidated Caco-2 cell model, widely used for determining translocation of drugs and chemicals, the establishment of an advanced intestinal barrier model with different level of complexity is important for overcoming Caco-2 monoculture limitations. For this purpose, a tri-culture model, consisting of two human intestinal epithelial cells (Caco-2 and HT29-MTX) and a human lymphocyte B cell (Raji B), was developed by several research groups to mimic the in vivo intestinal epithelium, furnishing appropriate tools for nanotoxicological studies. However, tri-culture model shows high levels of variability in ENM uptake/translocation studies. With the aim of implementing the standardization and optimization of this tri-culture for ENM translocation studies, the present paper intends to identify and discuss such relevant parameters involved in model establishment as: tri-culture condition set-up, barrier integrity evaluation, mucus characterization, M-cell induction. SiO2 fluorescent nanoparticles were used to compare the different models. Although a low level of SiO2 translocation is reported for all the different culture conditions. a relevant role of mucus and M-cells in NPs uptake/translocation has been highlighted

Listeria monocytogenes Behaviour in Presence of Non-UV-Irradiated Titanium Dioxide Nanoparticles

Listeria monocytogenes is the agent of listeriosis, a food-borne disease. It represents a serious problem for the food industry because of its environmental persistence mainly due to its ability to form biofilm on a variety of surfaces. Microrganisms attached on the surfaces are a potential source of contamination for environment and animals and humans. Titanium dioxide nanoparticles (TiO2 NPs) are used in food industry in a variety of products and it was reported that daily exposure to these nanomaterials is very high. Anti-listerial activity of TiO2 NPs was investigated only with UV-irradiated nanomaterials, based on generation of reactive oxigen species (ROS) with antibacterial effect after UV exposure. Since both Listeria monocytogenes and TiO2 NPs are veicolated with foods, this study explores the interaction between Listeria monocytogenes and non UV-irradiated TiO2 NPs, with special focus on biofilm formation and intestinal cell interaction. Scanning electron microscopy and quantitative measurements of biofilm mass indicate that NPs influence both production and structural architecture of listerial biofilm. Moreover, TiO2 NPs show to interfere with bacterial interaction to intestinal cells. Increased biofilm production due to TiO2 NPs exposure may favour bacterial survival in environment and its transmission to animal and human hosts

Silk Fibroin Scaffolds as Biomaterials for 3D Mesenchymal Stromal Cells Cultures

Silk fibroin (SF), a protein-based fiber extracted from Bombyx mori cocoons, has recently emerged with great potential for the biomedical field to be used as a biomaterial processable in a variety of formats and applications, due to its natural characteristics. The aims of the present study were to characterize the structural properties of the SF scaffolds, in the format of porous sponges, and to investigate their feasibility to support the adhesion of mesenchymal stromal/stem cells isolated from human Wharton’s jelly of the umbilical cord (WJ-MSC). Adhesion is a prerequisite for using the SF scaffold as biomaterial for supporting three-dimensional (3D) WJ-MSC cultures for several applications. The integration among micro-computed tomography, confocal analysis, and field emission scanning electron microscopy allowed carrying out a deep investigation based on quantitative morphological parameters and qualitative observations at high resolution. High levels of porosity, interconnection, and contact surface–volume ratio confirmed the appropriateness of the designed SF porous scaffolds as supports for cell cultures. WJ-MSC was demonstrated to be capable of adhering to and colonizing the SF scaffold applicable as a 3D cell culture system, of conducting in vitro experiments in a more controlled environment, and possibly of being used in tissue engineering, regenerative medicine, and applications in oncology

Lactoferrin prevents invasion and inflammatory response following E. coli strain LF82 infection in experimental model of Crohn's disease

BACKGROUND: Crohn's disease is a multifactorial disease in which an aberrant immune response to commensal intestinal microbiota leads to chronic inflammation. The small intestine of patients with Crohn's disease is colonized by a group of adherent-invasive Escherichia coli strongly able to adhere and invade intestinal epithelial cells lactoferrin is an iron-binding glycoprotein known to have anti-bacterial and anti-inflammatory activities. AIMS: We explore the ability of bovine lactoferrin to modulate the interactions between the adherent-invasive E. coli strain LF82 and intestinal epithelial cells as well as the inflammatory response. METHODS: Bacterial adhesion and invasion assays were used to assess the antimicrobial activity of lactoferrin. Electron microscopy was used to characterize bacteria-cell interactions. The mRNA expression of pro-inflammatory cytokines was measured both in cultured cells and in biopsies taken from intestine of patients affected by Crohn's disease. RESULTS: Lactoferrin inhibited bacterial invasion through minimally affecting adhesion. This divergence was due to a mannose-dependent lactoferrin binding to the bacterial type 1 pili and consequent bacterial aggregation on the intestinal epithelial cell surface. Expression of pro-inflammatory cytokines, such as TNF-alpha, IL-8, and IL-6, was markedly inhibited by lactoferrin both in cultured and Crohn-derived intestinal cells. CONCLUSIONS: Bovine lactoferrin might function via an antibacterial and/or anti-inflammatory mechanism in the treatment of Crohn's disease

Antibiotic susceptibility by the Kirby-Bauer disk diffusion test.^a

a<p>Growth inhibition halo diameters were measured after 20 (PAO1) or 40 h (PAO1 Δ<i>tolB araC-</i>P_BAD<i>tolB</i>) of growth at 37°C on MH agar plates, containing or not arabinose at the indicated concentration. Values are the average ±SD of at least three independent assays. Asterisks indicate statistically significant differences compared to wild type (one-way ANOVA; ^*<i>P</i><0.05; ^**<i>P</i><0.01; ^***<i>P</i><0.001).</p>b<p>Abbreviations: Gm, gentamycin; Sm; streptomycin, Tc, tetracyclin, Ap, ampicillin; Ipm, imipenem; Cip, ciprofloxacin, Caz, ceftazidime, Ct, colistin, PmB, polymyxin B.</p