Skin Immune Landscape: Inside and Outside the Organism.

The skin is an essential organ to the human body protecting it from external aggressions and pathogens. Over the years, the skin was proven to have a crucial immunological role, not only being a passive protective barrier but a network of effector cells and molecular mediators that constitute a highly sophisticated compound known as the "skin immune system" (SIS). Studies of skin immune sentinels provided essential insights of a complex and dynamic immunity, which was achieved through interaction between the external and internal cutaneous compartments.

Identification of the epidermal growth factor receptor as the receptor for Salmonella Rck-dependent invasion.

The Salmonella Rck outer membrane protein binds to the cell surface, which leads to bacterial internalization via a Zipper mechanism. This invasion process requires induction of cellular signals, including phosphorylation of tyrosine proteins, and activation of c-Src and PI3K, which arises as a result of an interaction with a host cell surface receptor. In this study, epidermal growth factor receptor (EGFR) was identified as the cell signaling receptor required for Rck-mediated adhesion and internalization.

Biological Activity of Polynesian Calophyllum inophyllum Oil Extract on Human Skin Cells.

Oil from the nuts of Calophyllum inophyllum, locally called "Tamanu oil" in French Polynesia, was traditionally used for wound healing and to cure various skin problems and ailments. The skin-active effect of "Tamanu oil emulsion" was investigated on human skin cells (keratinocytes and dermal fibroblasts) and showed cell proliferation, glycosaminoglycan and collagen production, and wound healing activity. Transcriptomic analysis of the treated cells revealed gene expression modulation including genes involved in the metabolic process implied in O-glycan biosynthesis, cell adhesion, and cell proliferation.

Effect of Substance P in Staphylococcus aureus and Staphylococcus epidermidis Virulence: Implication for Skin Homeostasis.

Staphylococcus aureus and Staphylococcus epidermidis are two major skin associated bacteria, and Substance P (SP) is a major skin neuropeptide. Since bacteria are known to sense and response to many human hormones, we investigated the effects of SP on Staphylococci virulence in reconstructed human epidermis model and HaCaT keratinocytes. We show that SP is stimulating the virulence of S.

Pseudomonas aeruginosa Expresses a Functional Human Natriuretic Peptide Receptor Ortholog: Involvement in Biofilm Formation.

Unlabelled: Considerable evidence exists that bacteria detect eukaryotic communication molecules and modify their virulence accordingly. In previous studies, it has been demonstrated that the increasingly antibiotic-resistant pathogen Pseudomonas aeruginosa can detect the human hormones brain natriuretic peptide (BNP) and C-type natriuretic peptide (CNP) at micromolar concentrations. In response, the bacterium modifies its behavior to adapt to the host physiology, increasing its overall virulence.

Effects of a skin neuropeptide (substance p) on cutaneous microflora.

Background: Skin is the largest human neuroendocrine organ and hosts the second most numerous microbial population but the interaction of skin neuropeptides with the microflora has never been investigated. We studied the effect of Substance P (SP), a peptide released by nerve endings in the skin on bacterial virulence.

Methodology/principal Findings: Bacillus cereus, a member of the skin transient microflora, was used as a model.

Comparative study of normal and sensitive skin aerobic bacterial populations.

The purpose of this study was to investigate if the sensitive skin syndrome, a frequent skin disorder characterized by abnormal painful reactions to environmental factors in the absence of visible inflammatory response, could be linked to a modification in the skin bacterial population. A total of 1706 bacterial isolates was collected at the levels of the forehead, cheekbone, inner elbow, and lower area of the scapula on the skin of normal and sensitive skin syndrome-suffering volunteers of both sexes and of different ages. Among these isolates, 21 strains were randomly selected to validate in a first step the Matrix-Assisted Laser Desorption/Ionization (MALDI)-Biotyper process as an efficient identification tool at the group and genus levels, by comparison to API(®) strips and 16S ribosomal RNA gene sequencing identification techniques.

Antimicrobial peptides and pro-inflammatory cytokines are differentially regulated across epidermal layers following bacterial stimuli.

The skin is a natural barrier between the body and the environment and is colonised by a large number of microorganisms. Here, we report a complete analysis of the response of human skin explants to microbial stimuli. Using this ex vivo model, we analysed at both the gene and protein level the response of epidermal cells to Staphylococcus epidermidis (S.

In Planta Biocontrol of Pectobacterium atrosepticum by Rhodococcus erythropolis Involves Silencing of Pathogen Communication by the Rhodococcal Gamma-Lactone Catabolic Pathway.

The virulence of numerous Gram-negative bacteria is under the control of a quorum sensing process based on synthesis and perception of N-acyl homoserine lactones. Rhodococcus erythropolis, a Gram-positive bacterium, has recently been proposed as a biocontrol agent for plant protection against soft-rot bacteria, including Pectobacterium. Here, we show that the γ-lactone catabolic pathway of R.

Effect of GABA, a bacterial metabolite, on Pseudomonas fluorescens surface properties and cytotoxicity.

Different bacterial species and, particularly Pseudomonas fluorescens, can produce gamma-aminobutyric acid (GABA) and express GABA-binding proteins. In this study, we investigated the effect of GABA on the virulence and biofilm formation activity of different strains of P. fluorescens.

Pseudomonas fluorescens can induce and divert the human β-defensin-2 secretion in intestinal epithelial cells to enhance its virulence.

The effect of intestinal molecules produced by the host on the virulence of Pseudomonas fluorescens is poorly documented. In the present work, we evaluated the secretion of human β-defensin-2 (hBD-2) by enterocytes after infection with P. fluorescens (a species previously suggested to be involved in inflammatory bowel disease) and investigated the effect of this host-defense peptide on the bacterial virulence.

Virulence of the Pseudomonas fluorescens clinical strain MFN1032 towards Dictyostelium discoideum and macrophages in relation with type III secretion system.

Background: Pseudomonas fluorescens biovar I MFN1032 is a clinical isolate able to grow at 37°C. This strain displays secretion-mediated hemolytic activity involving phospholipase C and cyclolipopeptides, and a cell-associated hemolytic activity distinct from the secreted hemolytic activity. Cell-associated hemolysis is independent of biosurfactant production and remains in a gacA mutant.

Involvement of c-Src tyrosine kinase upstream of class I phosphatidylinositol (PI) 3-kinases in Salmonella Enteritidis Rck protein-mediated invasion.

The Salmonella outer membrane protein Rck mediates a Zipper entry mechanism controlled by tyrosine phosphorylation and class I phosphatidylinositol 3-kinase (PI 3-kinase). However, the underlying mechanism leading to this signaling cascade remains unclear. The present study showed that using Rck-coated beads or Rck-overexpressing Escherichia coli, Rck-mediated actin polymerization and invasion were blocked by PP2, a Src family tyrosine kinase inhibitor.

Salmonella enteritidis Rck-mediated invasion requires activation of Rac1, which is dependent on the class I PI 3-kinases-Akt signaling pathway.

The Salmonella outer membrane protein Rck mediates a Zipper-like entry mechanism controlled by Rac, the Arp2/3 complex, and actin polymerization. However, little is known about the early steps leading to Rac activation and Rck-mediated internalization. The use of pharmacological inhibitors or PI 3-kinase dominant-negative mutant induced more than 80% less invasion without affecting attachment.

Rck of Salmonella enterica, subspecies enterica serovar enteritidis, mediates zipper-like internalization.

Salmonella can invade non-phagocytic cells through its type III secretion system (T3SS-1), which induces a Trigger entry process. This study showed that Salmonella enterica, subspecies enterica serovar Enteritidis can also invade cells via the Rck outer membrane protein. Rck was necessary and sufficient to enable non-invasive E.