Citation Details

Journal Article

Animals, B16-F10-luc2, B16F10-luc2; Coloring Agents/administration & dosage/*diagnostic use; Indocyanine Green/administration & dosage/*diagnostic use; Injections, Intradermal; Liposomes/administration & dosage; Lymphatic Metastasis; Lymphatic Vessels/metabolism/*pathology; Melanoma, Experimental/blood supply/metabolism/*pathology; Mice; Mice, Inbred C57BL; Vascular Endothelial Growth Factor C/biosynthesis

Lymphatic vessels play a major role in cancer progression and in postsurgical lymphedema, and several new therapeutic approaches targeting lymphatics are currently being developed. Thus, there is a critical need for quantitative imaging methods to measure lymphatic flow. Indocyanine green (ICG) has been used for optical imaging of the lymphatic system, but it is unstable in solution and may rapidly enter venous capillaries after local injection. We developed a novel liposomal formulation of ICG (LP-ICG), resulting in vastly improved stability in solution and an increased fluorescence signal with a shift toward longer wavelength absorption and emission. When injected intradermally to mice, LP-ICG was specifically taken up by lymphatic vessels and allowed improved visualization of deep lymph nodes. In a genetic mouse model of lymphatic dysfunction, injection of LP-ICG showed no enhancement of draining lymph nodes and slower clearance from the injection site. In mice bearing B16 luciferase-expressing melanomas expressing vascular endothelial growth factor-C (VEGF-C), sequential near-IR imaging of intradermally injected LP-ICG enabled quantification of lymphatic flow. Increased flow through draining lymph nodes was observed in mice bearing VEGF-C-expressing tumors without metastases, whereas a decreased flow pattern was seen in mice with a higher lymph node tumor burden. This new method will likely facilitate quantitative studies of lymphatic function in preclinical investigations and may also have potential for imaging of lymphedema or improved sentinel lymph detection in cancer.

Journal Article

Animals, Blotting, Western, Xen26, Cell Line, Tumor, Diagnostic Imaging/methods, Gene Therapy/*methods, Genetic Engineering/*methods, Genetic Vectors/*therapeutic use, Humans, Male, Mice, Mice, Inbred BALB C, Neoplasms/*therapy, Perforin/*genetics/therapeutic use, Promoter Regions, Genetic, Salmonella typhimurium/*genetics, bcl-Associated Death Protein/genetics IVIS, Xenogen

Tumor-targeting bacteria have been studied in terms of their ability to visualize the infection pathway (through imaging probes) or to carry therapeutic molecules to tumors. To integrate these monitoring and therapeutic functions, we engineered attenuated Salmonella typhimurium defective in guanosine 5'-diphosphate-3'-diphosphate synthesis to carry cytotoxic proteins (cytolysin A) and express reporter genes. We successfully visualized the therapeutic process with these engineered bacteria in mice and found that they often mediated complete tumor (CT-26) eradication on cytotoxic gene induction. Furthermore, treatment with the engineered bacteria markedly suppressed metastatic tumor growth.

Journal Article

Animals, Ceftriaxone/therapeutic use, Cephalosporins/therapeutic use, Disease Models, Animal, Disease Susceptibility, Drosophila Proteins, Inflammation/genetics/immunology/microbiology/pathology, Listeria Infections/genetics/immunology, Listeria monocytogenes/genetics/immunology, Membrane Glycoproteins/ deficiency/genetics, Meningitis, Bacterial/ genetics/ immunology/microbiology/pathology, Mice, Mice, Inbred C57BL, Mice, Knockout, Pneumococcal Infections/genetics/immunology/microbiology/pathology, Receptors, Cell Surface/ deficiency/genetics, Streptococcus pneumoniae/ immunology, Time Factors, Toll-Like Receptor 2, Toll-Like Receptors IVIS, Xenogen, Xen10

Toll-like receptor-2 (TLR2) mediates host responses to gram-positive bacterial wall components. TLR2 function was investigated in a murine Streptococcus pneumoniae meningitis model in wild-type (wt) and TLR2-deficient (TLR2(-/-)) mice. TLR2(-/-) mice showed earlier time of death than wt mice (P<.02). Plasma interleukin-6 levels and bacterial numbers in blood and peripheral organs were similar for both strains. With ceftriaxone therapy, none of the wt but 27% of the TLR2(-/-) mice died (P<.04). Beyond 3 hours after infection, TLR2(-/-) mice had higher bacterial loads in brain than did wt mice, as assessed with luciferase-tagged S. pneumoniae by means of a Xenogen-CCD (charge-coupled device) camera. After 24 h, tumor necrosis factor activity was higher in cerebrospinal fluid of TLR2(-/-) than wt mice (P<.05) and was related to increased blood-brain barrier permeability (Evans blue staining, P<.02). In conclusion, the lack of TLR2 was associated with earlier death from meningitis, which was not due to sepsis but to reduced brain bacterial clearing, followed by increased intrathecal inflammation.

Journal Article

Animals, Chronic Disease, Disease Models, Animal, Immunity, Innate, Killer Cells, Natural/immunology, Macrophages/immunology, Mice, Mice, Inbred C3H, Mice, Inbred Strains, Monocytes/immunology, Neoplasms, Neovascularization, Pathologic, Osteomyelitis/*complications, Osteosarcoma/*complications/*immunology/pathology, Staphylococcal Infections/*complications IVIS, Xenogen, Xen36

Clinical studies over the past several years have reported that metastasis-free survival times in humans and dogs with osteosarcoma are significantly increased in patients that develop chronic bacterial osteomyelitis at their surgical site. However, the immunological mechanism by which osteomyelitis may suppress tumor growth has not been investigated. Therefore, we used a mouse model of osteomyelitis to assess the effects of bone infection on innate immunity and tumor growth. A chronic Staphylococcal osteomyelitis model was established in C3H mice and the effects of infection on tumor growth of syngeneic DLM8 osteosarcoma were assessed. The effects of infection on tumor angiogenesis and innate immunity, including NK cell and monocyte responses, were assessed. We found that osteomyelitis significantly inhibited the growth of tumors in mice, and that the effect was independent of the infecting bacterial type, tumor type, or mouse strain. Depletion of NK cells or monocytes reversed the antitumor activity elicited by infection. Moreover, infected mice had a significant increase in circulating monocytes and numbers of tumor associated macrophages. Infection suppressed tumor angiogenesis but did not affect the numbers of circulating endothelial cells. Therefore, we concluded that chronic localized bacterial infection could elicit significant systemic antitumor activity dependent on NK cells and macrophages.

Journal Article

Animals, Diagnostic Imaging/ methods, Female, Mice, Microscopy, Electron, Scanning, Photons, Proteus Infections/ diagnosis, Proteus mirabilis/drug effects/isolation & purification, Pseudomonas Infections/ diagnosis, Pseudomonas aeruginosa/drug effects/isolation & purification, Urinary Catheterization/ adverse effects, Urinary Tract Infections/ diagnosis IVIS, Xenogen, Xen5, Xen44

Urinary tract infections (UTIs) are among the most common bacterial infections acquired by humans, particularly in catheterized patients. A major problem with catheterization is the formation of bacterial biofilms on catheter material and the risk of developing persistent UTIs that are difficult to monitor and eradicate. To better understand the course of UTIs and allow more accurate studies of in vivo antibiotic efficacy, we developed a catheter-based biofilm infection model with mice, using bioluminescently engineered bacteria. Two important urinary tract pathogens, Pseudomonas aeruginosa and Proteus mirabilis, were made bioluminescent by stable insertion of a complete lux operon. Segments of catheter material (precolonized or postimplant infected) with either pathogen were placed transurethrally in the lumen of the bladder by using a metal stylet without surgical manipulation. The bioluminescent strains were sufficiently bright to be readily monitored from the outside of infected animals, using a low-light optical imaging system, including the ability to trace the ascending pattern of light-emitting bacteria through ureters to the kidneys. Placement of the catheter in the bladder not only resulted in the development of strong cystitis that persisted significantly longer than in mice challenged with bacterial suspensions alone but also required prolonged antibiotic treatment to reduce the level of infection. Treatment of infected mice for 4 days with ciprofloxacin at 30 mg/kg of body weight twice a day cured cystitis and renal infection in noncatheterized mice. Similarly, ciprofloxacin reduced the bacterial burden to undetectable levels in catheterized mice but did not inhibit rebound of the infection upon cessation of antibiotic therapy. This methodology easily allows spatial information to be monitored sequentially throughout the entire disease process, including ascending UTI, treatment efficacy, and relapse, all without exogenous sampling, which is not possible with conventional methods.