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Journal Article

Amine Oxidase (Copper-Containing); Animals; Bacterial Adhesion; Bioware; Cell Adhesion Molecules; Coxsackievirus Infections; Immunity, Mucosal; Immunoglobulin A; Lymphocyte Count; Lymphocytes; Lymphoid Tissue; Mice; Mice, Inbred C57BL; Mice, Knockout; Peyer's Patches; Receptors, Lymphocyte Homing; Staphylococcal Vaccines; Staphylococcus aureus; Xen36

VAP-1, an ecto-enzyme expressed on the surface of endothelial cells, is involved in leukocyte trafficking between the blood and tissues under physiological and pathological conditions. In this study, we used VAP-1-deficient mice to elucidate whether absence of VAP-1 alters the immune system under normal conditions and upon immunization and microbial challenge. We found that VAP-1-deficient mice display age-dependent paucity of lymphocytes, in the Peyer's patches of the gut. IgA concentration in serum was also found to be lower in VAP-1(-/-) animals than in wild-type mice. Although there were slightly less CD11a on B and T cells isolated from VAP-1-deficient mice than on those from wild-type mice, there were no differences in the expression of gut-homing-associated adhesion molecules or chemokine receptors. Because anti-VAP-1 therapies are being developed for clinical use to treat inflammation, we determined the effect of VAP-1 deletion on useful immune responses. Oral immunization with OVA showed defective T and B cell responses in VAP-1-deficient mice. Antimicrobial immune responses against Staphylococcus aureus and coxsackie B4 virus were also affected by the absence of VAP-1. Importantly, when the function of VAP-1 was acutely neutralized using small molecule enzyme inhibitors and anti-VAP-1 Abs rather than by gene deletion, no significant impairment in antimicrobial control was detected. In conclusion, VAP-1-deficient mice have mild deviations in the mucosal immune system and therapeutic targeting of VAP-1 does not appear to cause a generalized increase in the risk of infection.

Journal Article

Animals; Bioware; Cattle; Cells, Cultured; Cystic Fibrosis; Flavoproteins; Humans; Hydrogen peroxide; Immunity, Innate; Immunity, Mucosal; Lactoperoxidase; Lung Diseases; Pseudomonas aeruginosa; Rats; Reactive Oxygen Species; Respiratory Mucosa; RNA, Small Interfering; Staphylococcus aureus; Thiocyanates; Trachea; Xen8.1

RATIONALE The respiratory tract is constantly exposed to airborne microorganisms. Nevertheless, normal airways remain sterile without recruiting phagocytes. This innate immune activity has been attributed to mucociliary clearance and antimicrobial polypeptides of airway surface liquid. Defective airway immunity characterizes cystic fibrosis (CF), a disease caused by mutations in the CF transmembrane conductance regulator, a chloride channel. The pathophysiology of defective immunity in CF remains to be elucidated. OBJECTIVE We investigated the ability of non-CF and CF airway epithelia to kill bacteria through the generation of reactive oxygen species (ROS). METHODS ROS production and ROS-mediated bactericidal activity were determined on the apical surfaces of human and rat airway epithelia and on cow tracheal explants. MEASUREMENTS AND MAIN RESULTS Dual oxidase enzyme of airway epithelial cells generated sufficient H(2)O(2) to support production of bactericidal hypothiocyanite (OSCN(-)) in the presence of airway surface liquid components lactoperoxidase and thiocyanate (SCN(-)). This OSCN(-) formation eliminated Staphylococcus aureus and Pseudomonas aeruginosa on airway mucosal surfaces, whereas it was nontoxic to the host. In contrast to normal epithelia, CF epithelia failed to secrete SCN(-), thereby rendering the oxidative antimicrobial system inactive. CONCLUSIONS These data indicate a novel innate defense mechanism of airways that kills bacteria via ROS and suggest a new cellular and molecular basis for defective airway immunity in CF.

Journal Article

Anti-Infective Agents; Biofilms; Dental Pulp Cavity; Dental Pulp Diseases; Endodontics; Humans; Luminescence; Photochemotherapy; Polyethyleneimine; Porphyrins; Proteus Infections; Proteus mirabilis; Pseudomonas aeruginosa; Pseudomonas Infections; Xen5; Xen44

BACKGROUND AND OBJECTIVE To compare the effectiveness of antimicrobial photodynamic therapy (PDT), standard endodontic treatment and the combined treatment to eliminate bacterial biofilms present in infected root canals. STUDY DESIGN/MATERIALS AND METHODS Ten single-rooted freshly extracted human teeth were inoculated with stable bioluminescent Gram-negative bacteria, Proteus mirabilis and Pseudomonas aeruginosa to form 3-day biofilms in prepared root canals. Bioluminescence imaging was used to serially quantify bacterial burdens. PDT employed a conjugate between polyethylenimine and chlorin(e6) as the photosensitizer (PS) and 660-nm diode laser light delivered into the root canal via a 200-micro fiber, and this was compared and combined with standard endodontic treatment using mechanical debridement and antiseptic irrigation. RESULTS Endodontic therapy alone reduced bacterial bioluminescence by 90% while PDT alone reduced bioluminescence by 95%. The combination reduced bioluminescence by >98%, and importantly the bacterial regrowth observed 24 hours after treatment was much less for the combination (P<0.0005) than for either single treatment. CONCLUSIONS Bioluminescence imaging is an efficient way to monitor endodontic therapy. Antimicrobial PDT may have a role to play in optimized endodontic therapy.

Journal Article

Animals, Bone Marrow Cells/metabolism/microbiology, Gene Expression Regulation, Intestines/metabolism, Kinetics, Lectins/chemistry, Listeria Infections/*metabolism/*prevention & control, Listeria monocytogenes/*metabolism, Mice, Mice, Inbred C57BL, Mice, Transgenic, Myeloid Differentiation Factor 88/metabolism/*physiology, Proteins/*metabolism, Recombinant Proteins/metabolism, Toll-Like Receptors/metabolism IVIS, Xenogen, Xen32

Listeria monocytogenes is a food-borne bacterial pathogen that causes systemic infection by traversing the intestinal mucosa. Although MyD88-mediated signals are essential for defense against systemic L. monocytogenes infection, the role of Toll-like receptor and MyD88 signaling in intestinal immunity against this pathogen has not been defined. We show that clearance of L. monocytogenes from the lumen of the distal small intestine is impaired in MyD88(-/-) mice. The distal ileum of wild-type (wt) mice expresses high levels of RegIII gamma, which is a bactericidal lectin that is secreted into the bowel lumen, whereas RegIII gamma expression in MyD88(-/-) mice is nearly undetectable. In vivo depletion of RegIII gamma from the small intestine of wt mice diminishes killing of luminal L. monocytogenes, whereas reconstitution of MyD88-deficient mice with recombinant RegIII gamma enhances intestinal bacterial clearance. Experiments with bone marrow chimeric mice reveal that MyD88-mediated signals in nonhematopoietic cells induce RegIII gamma expression in the small intestine, thereby enhancing bacterial killing. Our findings support a model of MyD88-mediated epithelial conditioning that protects the intestinal mucosa against bacterial invasion by inducing RegIII gamma.

Journal Article

Adenosine Triphosphate; Aminoimidazole Carboxamide; AMP-Activated Protein Kinases; Bioware; Breast Neoplasms; Carcinoma, Squamous Cell; Cell Line, Tumor; DNA, Neoplasm; Drug Synergism; Enzyme Activation; Humans; Lipids; Methotrexate; Multienzyme Complexes; Nucleotide Deaminases; PC-3M-luc; Phosphoribosylaminoimidazolecarboxamide Formyltransferase; Phosphoribosylglycinamide Formyltransferase; Protein-Serine-Threonine Kinases; Purines; Ribonucleosides; Ribonucleotides; RNA Interference

Because of its ability to mimic a low energy status of the cell, the cell-permeable nucleoside 5-aminoimidazole-4-carboxamide (AICA) riboside was proposed as an antineoplastic agent switching off major energy-consuming processes associated with the malignant phenotype (lipid production, DNA synthesis, cell proliferation, cell migration, etc.). Key to the antineoplastic action of AICA riboside is its conversion to ZMP, an AMP mimetic that at high concentrations activates the AMP-activated protein kinase (AMPK). Here, in an attempt to increase the efficacy of AICA riboside, we pretreated cancer cells with methotrexate, an antimetabolite blocking the metabolism of ZMP. Methotrexate enhanced the AICA riboside-induced accumulation of ZMP and led to a decrease in the levels of ATP, which functions as an intrasteric inhibitor of AMPK. Consequently, methotrexate markedly sensitized AMPK for activation by AICA riboside and potentiated the inhibitory effects of AICA riboside on tumor-associated processes. As cotreatment elicited antiproliferative effects already at concentrations of compounds that were only marginally effective when used alone, our findings on the cooperation between methotrexate and AICA riboside provide new opportunities both for the application of classic antimetabolic chemotherapeutics, such as methotrexate, and for the exploitation of the energy-sensing machinery as a target for cancer intervention.