stilbenes and Pseudomonas-Infections

Quorum sensing (QS), a cell-to-cell communication mechanism present in many bacterial species plays a key role in regulating the virulence factor and biofilm formation in many pathogens, which causes severe public health risk. Therefore, interfering with QS mechanism offers an attractive strategy to combat bacterial infections. In the present study, anti-QS activity of a novel resveratrol formulation, Resveramax™, was detected using Chromobacterium violaceum biosensor bioassay and the effect of Resveramax on QS-regulated phenotypes in Pseudomonas aeruginosa PAO1 was assessed by standard protocols. Molecular docking analysis of resveratrol, the major active constituent of Resveramax, with LasR receptor protein was performed to evidence the QS-inhibitory potential of Resveramax. Results showed that Resveramax specifically inhibited the QS-mediated violacein pigment production in C. violaceum; pyocyanin production, proteolytic activity, swarming motility and biofilm formation in P. aeruginosa PAO1 in a concentration-dependent manner. Biofilms treated with Resveramax showed increased susceptibility to antibiotics when compared with the antibiotic treatment alone. Molecular docking analysis proved that resveratrol binds more rigidly with LasR receptor protein with docking score of -8.55 kJ/mol. These findings suggest that Resveramax could be used as novel QS-based antibacterial/anti-biofilm agent for the management of bacterial infections.

Topics: Anti-Bacterial Agents; Bacterial Proteins; Biofilms; Biological Availability; Biosensing Techniques; Drug Synergism; Microbial Sensitivity Tests; Models, Molecular; Molecular Conformation; Protein Binding; Pseudomonas aeruginosa; Pseudomonas Infections; Quorum Sensing; Resveratrol; Stilbenes; Trans-Activators

The aim of this study was to preliminarily investigate the effects of resveratrol on the treatment of systemic inflammatory response induced by severe burn wounding. Through the simulation experiment in vivo on burned mice and simulative experiment in vitro on mice macrophage respectively, differences of the related pro-inflammatory cytokines and SIRT1 expression levels between the resveratrol-treated group and the untreated control group were detected and analyzed. The results of the simulation experiment in vivo on burned mice manifested that the survival rate of the mice in the resveratrol-treated group was markedly higher than that of controls (p<0.05). Resveratrol could significantly reduce the levels of pro-inflammatory factors TNF-α, IL-1β, and IL-6 in serum (p<0.01) and greatly elevate the expression level of SIRT1 (p<0.01). The results of the simulative experiment in vitro on mice macrophage showed no significant difference in TNF-α, IL-1β, or IL-6 contents among three groups (C, mice macrophage control group; R, resveratrol-treated macrophage group; I, SIRT1-inhibitor-treated macrophage group). Whereas, after lipopolysaccharide (LPS) activation (L group), macrophage TNF-α, IL-1β, and IL-6 levels were significantly increased in L group, dramatically higher than those in L+R group (LPS and resveratrol treatment group) (p<0.01). After adding SITR1 inhibitor, three pro-inflammatory cytokines in L+R+I group all showed significant increases compared with those in L+R group (p<0.01). LPS activated macrophages were able to promote the expression of pro-inflammatory cytokines. By upregulating the expression levels of SIRT1, resveratrol could effectively inhibit the inflammation cascade reaction and increase the survival rate of severe burn with bacterial infections in a large extent.

Topics: Animals; Anti-Inflammatory Agents, Non-Steroidal; Burns; Cells, Cultured; Female; Inflammation; Interleukin-1beta; Interleukin-6; Lipopolysaccharides; Macrophage Activation; Macrophages; Male; Mice; Mice, Inbred C57BL; Pseudomonas aeruginosa; Pseudomonas Infections; Resveratrol; Sirtuin 1; Stilbenes; Survival Rate; Tumor Necrosis Factor-alpha

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that can cause severe pulmonary infection in immunocompromized individuals. During the infectious process, P. aeruginosa provokes a potent inflammatory response and induces the release of reactive oxygen species (ROS). Cells undergo oxidative stress when cellular antioxidants are unable to effectively scavenge and detoxify ROS, resulting in lung damage. Resveratrol (3,5,4'-trihydroxystilbene) is a natural polyphenolic compound with recognized antioxidant effects. We hypothesized that owing to its antioxidant activities, resveratrol can attenuate an inflammatory response in P. aeruginosa-infected cells. Lung epithelial A549 cells were pre-treated with 100 μmol/L of resveratrol for 5 h, followed by infection with P. aeruginosa. Intracellular ROS generation was used as an indicator of P. aeruginosa-induced oxidative stress, and cell surface expression of Fas receptor and activation of caspases-3 and -7 as indicators of apoptosis. We also measured the surface expression of intercellular adhesion molecule (ICAM)-1 and enzymes related to inflammation and redox signaling. Resveratrol significantly reduced ROS generation, ICAM-1, and human beta-defensin-2 expression, as well as the markers of apoptosis in A549 cells infected with P. aeruginosa, and up-regulated glutathione peroxidase, suggesting its potential therapeutic role in protecting the lungs against the deleterious effects of P. aeruginosa infection.

Topics: Antioxidants; Cell Line; Down-Regulation; Epithelial Cells; Humans; Inflammation; Lung; Pseudomonas aeruginosa; Pseudomonas Infections; Reactive Oxygen Species; Respiratory Mucosa; Resveratrol; Stilbenes

Pseudomonas aeruginosa is an opportunistic Gram-negative pathogen, which is the major cause of severe chronic lung infection in cystic fibrosis patients. It is also responsible for systemic infections in immunocompromised individuals and those presenting with significant pulmonary conditions in intensive care units. This microorganism has the capacity to initiate severe inflammation in infected lungs resulting in detrimental tissue damage. We have hypothesized that Syk protein tyrosine kinase mediates lung epithelial cellular responses to P. aeruginosa infection, and that a naturally occurring non-toxic Syk inhibitor piceatannol can protect infected human cells against the deleterious effects associated with this infection. We infected Syk-positive H292 or Syk-negative A549 human lung epithelial cell lines with P. aeruginosa and assessed the resulting cellular responses, i.e. production of proinflammatory cytokines, adhesion molecule expression, generation of reactive oxygen species, and apoptosis of infected cells, utilizing a multiplex bead-based immunoassay and flow cytometry. We also studied the internalization of P. aeruginosa using the gentamicin exclusion assay. We found that the piceatannol treatment significantly suppressed inflammation, oxidative stress and apoptosis in H292, but not in A549 cells implicating Syk participation in the regulation of the pathological processes induced by P. aeruginosa infection. Intriguingly, piceatannol was able to down-regulate the internalization of P. aeruginosa by both Syk-positive and Syk-negative cell lines, implying that the mechanisms of action of this compound extend beyond Syk inhibition. As piceatannol can interfere with several mechanisms of bacterial pathogenesis this natural compound deserves further study as a potential therapeutic option in P. aeruginosa infection.

Topics: Apoptosis; Cell Line; Cell Separation; Cytokines; Endocytosis; Flow Cytometry; Humans; Inflammation Mediators; Intercellular Adhesion Molecule-1; Intracellular Signaling Peptides and Proteins; Lung; Oxidative Stress; Protein-Tyrosine Kinases; Pseudomonas aeruginosa; Pseudomonas Infections; Respiratory Mucosa; Stilbenes; Syk Kinase