Vesiculation from Pseudomonas aeruginosa under SOS

Bacterial infections can be aggravated by antibiotic treatment that induces SOS response and vesiculation. This leads to a hypothesis concerning association of SOS with vesiculation. To test it, we conducted multiple analyses of outer membrane vesicles (OMVs) produced from the Pseudomonas aeruginosa wild type in which SOS is induced by ciprofloxacin and from the LexA noncleavable (lexAN) strain in which SOS is repressed. The levels of OMV proteins, lipids, and cytotoxicity increased for both the treated strains, demonstrating vesiculation stimulation by the antibiotic treatment. However, the further increase was suppressed in the lexAN strains, suggesting the SOS involvement. Obviously, the stimulated vesiculation is attributed by both SOS-related and unrelated factors. OMV subproteomic analysis was performed to examine these factors, which reflected the OMV-mediated cytotoxicity and the physiology of the vesiculating cells under treatment and SOS. Thus, SOS plays a role in the vesiculation stimulation that contributes to cytotoxicity

Bacteria under SOS evolve anticancer phenotypes

Abstract Background The anticancer drugs, such as DNA replication inhibitors, stimulate bacterial adhesion and induce the bacterial SOS response. As a variety of bacterial mutants can be generated during SOS, novel phenotypes are likely to be selected under the drug pressure. Presentation of the hypothesis Bacteria growing with cancer cells in the presence of the replication inhibitors undergo the SOS response and evolve advantageous phenotypes for the bacteria to invade the cancer cells in order to evade the drug attack. This hypothesis predicts that bacteria produce the proteins that mediate bacterial capture and invasion of cancer cells--the advantageous phenotypes. Generation of the phenotypes may be facilitated during the SOS response induced by anticancer drugs. Testing the hypothesis Experimental design: 1) Examine attachment and invasion of bacterium Pseudomonas aeruginosa and the SOS mutant control to cancer cells in the presence of the anticancer drugs that inhibit DNA replication enzymes and trigger the SOS response. 2) Reveal the bacterial proteins that exhibit changes in expression. 3) Identify the genes encoding cancer adhesion and invasion. 4) Construct the mutants for the genes, clone and express these genes. 5) Examine the bacterial capture and invasion of cancer cells in contrast to non-cancer control. Expected results: 1) The bacterial proteins will be differentially induced during bacteria-cancer interaction under the SOS response to the anticancer drugs. 2) Knocking out the bacterial cancer-adhesion-invasion genes will disrupt the adhesion-invasion phenotypes of the bacteria. 3) Expressing these genes will direct the bacterial capture and invasion of cancer cells. Implications of the hypothesis Bacteria can evolve anticancer phenotypes targeting metastatic cells. If this hypothesis is true, the outcomes will contribute to development of a novel bacterial anti-metastasis regimen.</p

Biophysical and biochemical outcomes of Chlamydia pneumoniae infection promotes pro-atherogenic matrix microenvironment

Multiple studies support the hypothesis that infectious agents may be involved in the pathogenesis of atherosclerosis. Chlamydia pneumoniae is strongly implicated in atherosclerosis, but the precise role has been underestimated and poorly understood due to the complexity of the disease process. In this work, we test the hypothesis that C. pneumoniae-infected macrophages lodged in the subendothelial matrix contribute to atherogenesis through pro-inflammatory factors and by cell-matrix interactions. To test this hypothesis, we used a 3D infection model with freshly isolated PBMC infected with live C. pneumoniae and chlamydial antigens encapsulated in a collagen matrix, and analyzed the inflammatory responses over 7 days. We observed that infection significantly upregulates the secretion of cytokines TNF-, IL-1, IL-8, MCP-1, MMP, oxidative stress, transendothelial permeability, and LDL uptake. We also observed that infected macrophages form clusters, and substantially modify the microstructure and mechanical properties of the extracellular matrix to an atherogenic phenotype. Together, our data demonstrates that C. pneumoniae-infection drives a low-grade, sustained inflammation that may predispose in the transformation to atherosclerotic foci