Citation Details

Journal Article

Aging; Animals; Antigens, CD36; Cell Line; Dimerization; Ethylnitrosourea; Gene Deletion; Glycerides; Homozygote; Humans; Immunologic Deficiency Syndromes; Lipopeptides; Membrane Glycoproteins; Mice; Mice, Inbred C57BL; Mice, Knockout; Mutagenesis; Mutation; Oligopeptides; Peptidoglycan; Phenotype; Receptors, Cell Surface; Signal Transduction; Staphylococcal Infections; Staphylococcus aureus; Toll-Like Receptor 2; Toll-Like Receptors; Tumor Necrosis Factor-alpha; Zymosan

Toll-like receptor 2 (TLR2) is required for the recognition of numerous molecular components of bacteria, fungi and protozoa. The breadth of the ligand repertoire seems unusual, even if one considers that TLR2 may form heteromers with TLRs 1 and 6 (ref. 12), and it is likely that additional proteins serve as adapters for TLR2 activation. Here we show that an N-ethyl-N-nitrosourea-induced nonsense mutation of Cd36 (oblivious) causes a recessive immunodeficiency phenotype in which macrophages are insensitive to the R-enantiomer of MALP-2 (a diacylated bacterial lipopeptide) and to lipoteichoic acid. Homozygous mice are hypersusceptible to Staphylococcus aureus infection. Cd36(obl) macrophages readily detect S-MALP-2, PAM(2)CSK(4), PAM(3)CSK(4) and zymosan, revealing that some--but not all--TLR2 ligands are dependent on CD36. Already known as a receptor for endogenous molecules, CD36 is also a selective and nonredundant sensor of microbial diacylglycerides that signal via the TLR2/6 heterodimer.

Journal Article

in vivo imaging; nanomaterials; cancer

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Journal Article

FMT; bone; OsteoSense; FRFP; in vivo imaging

Bisphosphonate use has expanded beyond traditional applications to include treatment of a variety of low-bone-mass conditions. Complications associated with long-term bisphosphonate treatment have been noted, generating a critical need for information describing the local bisphosphonate-cell interactions responsible for these observations. This study demonstrates that a fluorescent bisphosphonate analogue, far-red fluorescent pamidronate (FRFP), is an accurate biomarker of bisphosphonate deposition and retention in vivo and can be used to monitor site-specific local drug concentration. In vitro, FRFP is competitively inhibited from the surface of homogenized rat cortical bone by traditional bisphosphonates. In vivo, FRFP delivery to the skeleton is rapid, with fluorescence linearly correlated with bone surface area. Limb fluorescence increases linearly with injected dose of FRFP; injected FRFP does not interfere with binding of standard bisphosphonates at the doses used in this study. Long-term FRFP retention studies demonstrated that FRFP fluorescence decreases in conditions of normal bone turnover, whereas fluorescence was retained in conditions of reduced bone turnover, demonstrating preservation of local FRFP concentration. In the mandible, FRFP localized to the alveolar bone and bone surrounding the periodontal ligament and molar roots, consistent with findings of osteonecrosis of the jaw. These findings support a role for FRFP as an effective in vivo marker for bisphosphonate site-specific deposition, turnover, and long-term retention in the skeleton.

Journal Article

FMT; OsteoSense; ProSense bone mineralization; bone turnover markers; molecular imaging; bisphosphonates; in vivo imaging

Abstract: FRFP binds to mineral at osteoblastic, osteoclastic, and quiescent surfaces, with accumulation likely modulated by vascular delivery. In vivo visualization and quantification of binding can be accomplished noninvasively in animal models through optical tomographic imaging.

Introduction: The development of near-infrared optical markers as reporters of bone metabolism will be useful for early diagnosis of disease. Bisphosphonates bind differentially to osteoblastic and osteoclastic surfaces depending on choice of side-chain and dose, and fluorescently tagged bisphosphonates provide a convenient way to visualize these sites. This study examines the ability of a fluorescently labeled pamidronate imaging probe to bind to regions of bone formation and resorption in vivo.

Materials and Methods: In vitro binding of a far-red fluorescent pamidronate (FRFP) to mineral was assessed using intact and demineralized dentine slices. In vivo, FRFP binding was studied in three models: developing neonatal mouse, bone healing after injury, and metastasis-induced osteolysis and fracture. 3D fluorescence molecular tomographic (FMT) imaging was used to visualize signal deep within the body.

Results: FRFP binding to bone depends on the quantity of mineral present and can be liberated from the bone during decalcification. In vivo, FRFP binds to surfaces of actively forming bone, as assessed by alkaline phosphatase staining, surfaces undergoing active resorption, as noted by scalloped bone border and presence of osteoclasts, and to quiescent surfaces not involved in formation or resorption. Binding is likely modulated by vascular delivery of the imaging agent to the exposed mineral surface and total quantity of surface exposed.FMT imaging is capable of visualizing regions of bone formation because of a large volume of labeled surface, but like radiolabeled bone scans, cannot discriminate pure osteolysis caused by metastasis.

Conclusions: FRFP may function as a local biomarker of bisphosphonate deposition to assess interplay between drug and cellular environment or may be combined with other imaging agents or fluorescent cells for the noninvasive assessment of local bone metabolism in vivo.

Journal Article

A549-luc-C8; Animals; Bioware; Cell Line, Tumor; Colonic Neoplasms; Fluorouracil; HT-29-luc-D6 cells; Humans; Image Interpretation, Computer-Assisted; Longitudinal Studies; Luciferases; Luminescent Measurements; Lung Neoplasms; Lymphatic Metastasis; Male; Mice; Mice, SCID; Mitomycin; Models, Biological; Neoplasm Transplantation; PC-3M-luc; Prostatic Neoplasms

Bioluminescent imaging (BLI) permits sensitive in vivo detection and quantification of cells specifically engineered to emit visible light. Three stable human tumor cell lines engineered to express luciferase were assessed for their tumorigenicity in subcutaneous, intravenous and spontaneous metastasis models. Bioluminescent PC-3M-luc-C6 human prostate cancer cells were implanted subcutaneously into SCID-beige mice and were monitored for tumor growth and response to 5-FU and mitomycin C treatments. Progressive tumor development and inhibition/regression following drug treatment were observed and quantified in vivo using BLI. Imaging data correlated to standard external caliper measurements of tumor volume, but bioluminescent data permitted earlier detection of tumor growth. In a lung colonization model, bioluminescent A549-luc-C8 human lung cancer cells were injected intravenously and lung metastases were monitored in vivo by whole animal imaging. Anesthetized mice were imaged weekly allowing a temporal assessment of in vivo lung tumor growth. This longitudinal study design permitted an accurate, real-time evaluation of tumor burden in the same animals over time. End-point bioluminescence measured in vivo correlated to total lung weight at necropsy. For a spontaneous metastatic tumor model, bioluminescent HT-29-luc-D6 human colon cancer cells implanted subcutaneously produced metastases to lung and lymph nodes in SCID-beige mice. Both primary tumors and micrometastases were detected by BLI in vivo. Ex vivo imaging of excised lung lobes and lymph nodes confirmed the in vivo signals and indicated a slightly higher frequency of metastasis in some mice. Levels of bioluminescence from in vivo and ex vivo images corresponded to the frequency and size of metastatic lesions in lungs and lymph nodes as subsequently confirmed by histology. In summary, BLI provided rapid, non-invasive monitoring of tumor growth and regression in animals. Its application to traditional oncology animal models offers quantitative and sensitive analysis of tumor growth and metastasis. The ability to temporally assess tumor development and responses to drug therapies in vivo also improves upon current standard animal models that are based on single end point data.