Biomedical subjects

Kimberly A Kelly

Publications and source records attributed to Kimberly A Kelly.

12 recordsLinked to original sources

PubMed2006

SPARC is a VCAM-1 counter-ligand that mediates leukocyte transmigration.

VCAM-1 is a cell surface molecule, which has been shown to mediate leukocyte adhesion to the endothelium and subsequent transmigration. Although VCAM-1 regulates adhesion through its interaction with VLA-4, VLA-4 does not play a role in VCAM-1-dependent diapedesis, an observation suggesting the presence of a second ligand for VCAM-1. We now report a novel interaction between VCAM-1 and secreted protein acidic and rich in cysteine (SPARC), which induces actin cytoskeletal rearrangement and intercellular gaps, physiological processes known to be important for leukocyte transmigration. The binding of leukocyte-derived SPARC to VCAM-1 was demonstrated to be necessary for leukocyte transmigration through endothelial monolayers (diapedesis) in vitro, and furthermore, SPARC null mice have abnormalities in leukocyte recruitment to the inflamed peritoneum in vivo. These findings provide new insight into the mechanisms of transendothelial leukocyte migration and suggest a potential, targetable interaction for therapeutic intervention.

Actins↗

PubMed2006

Noninvasive vascular cell adhesion molecule-1 imaging identifies inflammatory activation of cells in atherosclerosis.

BACKGROUND: Noninvasive imaging of adhesion molecules such as vascular cell adhesion molecule-1 (VCAM-1) may identify early stages of inflammation in atherosclerosis. We hypothesized that a novel, second-generation VCAM-1-targeted agent with enhanced affinity had sufficient sensitivity to enable real-time detection of VCAM-1 expression in experimental atherosclerosis in vivo, to quantify pharmacotherapy-induced reductions in VCAM-1 expression, and to identify activated cells in human plaques. METHODS AND RESULTS: In vivo phage display in apolipoprotein E-deficient mice identified a linear peptide affinity ligand, VHPKQHR, homologous to very late antigen-4, a known ligand for VCAM-1. This peptide was developed into a multivalent agent detectable by MRI and optical imaging (denoted VINP-28 for VCAM-1 internalizing nanoparticle 28, with 20 times higher affinity than previously reported for VNP). In vitro, VINP-28 targeted all cell types expressing VCAM-1. In vivo, MRI and optical imaging in apolipoprotein E-deficient mice (n=28) after injection with VINP-28 or saline revealed signal enhancement in the aortic root of mice receiving VINP-28 (P<0.05). VINP-28 colocalized with endothelial cells and other VCAM-1-expressing cells, eg, macrophages, and was spatially distinct compared with untargeted control nanoparticles. Atheromata of atorvastatin-treated mice showed reduced VINP-28 deposition and VCAM-1 expression. VINP-28 enhanced early lesions in juvenile mice and resected human carotid artery plaques. CONCLUSIONS: VINP-28 allows noninvasive imaging of VCAM-1-expressing endothelial cells and macrophages in atherosclerosis and spatial monitoring of anti-VCAM-1 pharmacotherapy in vivo and identifies inflammatory cells in human atheromata. This clinically translatable agent could noninvasively detect inflammation in early, subclinical atherosclerosis.

Amino Acid Sequence↗

PubMed2006

In vivo selection of phage for the optical imaging of PC-3 human prostate carcinoma in mice.

There is an increasing medical need to detect and spatially localize early and aggressive forms of prostate cancer. Affinity ligands derived from bacteriophage (phage) library screens can be developed to molecularly target prostate cancer with fluorochromes for optical imaging. Toward this goal, we used in vivo phage display and a newly described micropanning assay to select for phage that extravasate and bind human PC-3 prostate carcinoma xenografts in severe combined immune deficiency mice. One resulting phage clone (G1) displaying the peptide sequence IAGLATPGWSHWLAL was fluorescently labeled with the near-infrared fluorophore AlexaFluor 680 and was evaluated both in vitro and in vivo for its ability to bind and target PC-3 prostate carcinomas. The fluorescently labeled phage clone (G1) had a tumor-to-muscle ratio of approximately 30 in experiments. In addition, prostate tumors (PC-3) were readily detectable by optical-imaging methods. These results show proof of principle that disease-specific library-derived fluorescent probes can be rapidly developed for use in the early detection of cancers by optical means.

Animals↗

PubMed2006

In vivo imaging of molecularly targeted phage.

Rapid identification of in vivo affinity ligands would have far-reaching applications for imaging specific molecular targets, in vivo systems imaging, and medical use. We have developed a high-throughput method for identifying and optimizing ligands to map and image biologic targets of interest in vivo. We directly labeled viable phage clones with far-red fluorochromes and comparatively imaged them in vivo by multichannel fluorescence ratio imaging. Using Secreted Protein Acidic and Rich in Cysteine (osteonectin) and vascular cell adhesion molecule-1 as model targets, we show that: 1) fluorescently labeled phage retains target specificity on labeling; 2) in vivo distribution can be quantitated (detection thresholds of approximately 300 phage/mm(3) tissue) throughout the entire depth of the tumor using fluorescent tomographic imaging; and 3) fluorescently labeled phage itself can serve as a replenishable molecular imaging agent. The described method should find widespread application in the rapid in vivo discovery and validation of affinity ligands and, importantly, in the use of fluorochrome-labeled phage clones as in vivo imaging agents.

Animals↗

PubMed2005

Detection of vascular adhesion molecule-1 expression using a novel multimodal nanoparticle.

Endothelial vascular adhesion molecule-1 (VCAM-1) is a critical component of the leukocyte-endothelial adhesion cascade, and its strict temporal and spatial regulation make it an ideal target for imaging and therapy. The goal of this study was to develop novel VCAM-1-targeted imaging agents detectable by MRI and fluorescence imaging using phage display-derived peptide sequences and multimodal nanoparticles (NPs). We hypothesized that VCAM-1-mediated cell internalization of phage display-selected peptides could be harnessed as an amplification strategy to chaperone and trap imaging agents inside VCAM-1-expressing cells, thus improving target-to-background ratios. To accomplish our goal, iterative phage display was performed on murine endothelium under physiological flow conditions to identify a family of VCAM-1-mediated cell-internalizing peptides. One specific sequence, containing the VHSPNKK motif that has homology to the alpha-chain of very late antigen (a known ligand for VCAM-1), was shown to bind VCAM-1 and block leukocyte-endothelial interactions. Compared with VCAM-1 monoclonal antibody, the peptide showed 12-fold higher target-to-background ratios. A VHSPNKK-modified magnetofluorescent NP (VNP) showed high affinity for endothelial cells expressing VCAM-1 but surprisingly low affinity for macrophages. In contrast, a control NP without VCAM-1-targeting sequences showed no affinity for endothelial cells. In vivo, VNP successfully identified VCAM-1-expressing endothelial cells in a murine tumor necrosis factor-alpha-induced inflammatory model and colocalized with VCAM-1-expressing cells in atherosclerotic lesions present in cholesterol-fed apolipoprotein E apoE-/- mice. These results indicate that: (1) small peptide sequences can significantly alter targeting of NPs, (2) the used amplification strategy of internalization results in high target-to-background ratios, and (3) this technology is useful for in vivo imaging of endothelial markers.

Animals↗

PubMed2004

Fluorescein isothiocyanate-hapten immunoassay for determination of peptide-cell interactions.

We have developed a fluorescein isothiocyanate (FITC)-hapten immunoassay, where a FITC-labeled peptide binding to a cell is assayed as the amount of immunoreactive fluorescein present in a cell lysate. An antifluorescein-horseradish peroxidase conjugate binds to either a fluoresceinated peptide in the lysate or a fluorescein attached to the wells of a microtiter plate in a competitive fashion. After washing, solid-phase peroxidase activity is measured and inversely related to the amount of FITC-labeled peptide present. To demonstrate the assay, the interaction of a FITC-labeled bombesin-like peptide with the gastrin-releasing peptide receptor on PC-3 and HT-29 cells was investigated. Using PC-3 cells, we obtained similar displacement curves and numbers of binding sites per cell by both the FITC-hapten immunoassay and a reference radioreceptor assay. The FITC-hapten immunoassay is a sensitive and versatile method, since the same commercially available reagents can be used to assess interactions between any peptide and any receptor. In addition, the FITC-labeled peptide can be used to visualize receptors in fluorescent-activated cell sorting or fluorescent microscopy.

Bombesin↗

PubMed2003

Catecholase activity associated with copper-S100B.

This study addresses the spectroscopic properties and reactivity associated with the copper-loaded form of S100B isolated from bovine brain. Copper(II)-S100B displays EPR features typical of a type II copper center and is shown here to exhibit catecholase activity, the two-electron oxidation of catechols. The steady-state kinetics associated with the oxidation of several catecholamines has been probed in order to further characterize this activity. The evidence provided indicates that the catecholase chemistry is copper initiated. Superoxide dismutase has no effect on the rates of catecholamine oxidation catalyzed by Cu-S100B, establishing that superoxide is not produced during this reaction, ruling out an autoxidative mechanism. Addition of catalase to the Cu-S100B reaction with catechols reduces the amount of oxygen consumed by 50%, demonstrating that peroxide is released during this reaction. The release of peroxide is mechanistically distinct from the type III dinuclear copper proteins, catechol oxidase and tyrosinase.

Animals↗

PubMedDate not supplied

In vivo phage display selection yields atherosclerotic plaque targeted peptides for imaging.

PURPOSE: Atherosclerosis is a leading cause of morbidity and mortality in the Western world, yet specific imaging agents to detect and map inflammatory plaques are still lacking. PROCEDURES: We used in vivo phage display to interrogate early atherosclerotic lesions present in ApoE-/- mice with the goal of identifying plaque-associated endothelial cell internalized affinity ligands. RESULTS: We identified 30 phage families with some of these families exhibiting homology to known atherosclerotic proteins, namely, leukemia inhibitory factor, transferrin, and VLA-4. VLA-4 homologous peptides [termed vascular cellular adhesion molecule-1 (VCAM-1) internalizing peptide-28 (VINP28)] bound to and were internalized by VCAM-1-expressing cells and were inhibited by soluble VCAM-1. In addition, a VINP28 modified multimodal nanoparticle showed high affinity for endothelial cells expressing VCAM-1 but low affinity for macrophages or smooth muscle cells. CONCLUSION: The identified peptides represent a set of probes to interrogate the cell surface repertoire and potentially allow early detection of atherosclerosis.

Affinity Labels↗

PubMedDate not supplied

Isolation of a colon tumor specific binding peptide using phage display selection.

Colorectal cancer is the third most common malignancy in the United States. Improved detection sensitivity of early colorectal neoplasms would have important clinical applications. Herein, we report on using phage display to generate peptide libraries that detect colon carcinoma tissues. To accomplish this, we employed positive selection of a peptide-bearing phage library on poorly differentiated colon carcinoma cells (HT29) and combined this with negative selection of the phage library on well-differentiated colon carcinoma cells (HCT116). Analysis of the resulting library identified a nine-amino-acid, disulfide-constrained peptide, CPIEDRPMC (RPMrel), that stained HT29 colon carcinoma cells. Immunohistochemical staining using FITC-conjugated RPMrel peptide also showed binding of RPMrel to colon tumor tissues from four patients. We saw no binding of RPMrel to normal colon tissues. In addition, RPMrel failed to stain a panel of noncolon tissues including the lungs, liver, and stomach. We further demonstrated that RPMrel coupled to the mitochondrial toxin (KLAKLAK)2 killed HT29 cells. These studies suggest that RPMrel may be a promising lead candidate in the development of a useful colon tumor diagnostic and targeted drug delivery agent.

Amino Acid Sequence↗

PubMedDate not supplied

In vivo imaging of activated endothelium using an anti-VCAM-1 magnetooptical probe.

It has been suggested that vascular cell adhesion molecule-1 (VCAM-1) could serve as an early marker for inflammation of the endothelium. The ability to noninvasively image VCAM-1 could thus be a useful tool to diagnose a number of inflammatory diseases at early stages. Here we demonstrate that magnetooptical nanoparticles conjugated to anti-VCAM-1 antibodies can be used to specifically detect VCAM-1 expression on endothelial cells in culture and in vivo. Elevated VCAM-1 expression was detected on cultured murine heart endothelial cells by both fluorescence and magnetic resonance, while only basal expression levels were detected on murine dermal endothelial cells. Intravital microscopy of a murine inflammatory model injected with the VCAM-1 targeted nanoparticles revealed specific labeling of the activated endothelium, with labeling kinetics yielding a maximum vessel wall signal 6 h after injection. In contrast, nontargeted nanoparticles did not exhibit any specific labeling of the endothelium. These studies suggest that the developed nanoparticle would be useful for MR and optical detection of activated endothelium.

Animals↗

PubMedDate not supplied

High-throughput identification of phage-derived imaging agents.

The use of phage-displayed peptide libraries is a powerful method for selecting peptides with desired binding properties. However, the validation and prioritization of "hits" obtained from this screening approach remains challenging. Here, we describe the development and testing of a new analysis method to identify and display hits from phage-display experiments and high-throughput enzyme-linked immunosorbent assay screens. We test the method using a phage screen against activated macrophages to develop imaging agents with higher specificity for active disease processes. The new methodology should be useful in identifying phage hits and is extendable to other library screening methods such as small-molecule and nanoparticle libraries.

Affinity Labels↗

PubMedDate not supplied

Cellular imaging of inflammation in atherosclerosis using magnetofluorescent nanomaterials.

OBJECTIVE: Magnetofluorescent nanoparticles (MFNPs) offer the ability to image cellular inflammation in vivo. To better understand their cellular targeting and imaging capabilities in atherosclerosis, we investigated prototypical dextran-coated near-infrared fluorescent MFNPs in the apolipoprotein E-deficient (apo E-/-) mouse model. METHODS AND RESULTS: In vitro MFNP uptake was highest in activated murine macrophages (p < .001). Apo E-/- mice (n = 11) were next injected with the MFNP (15 mg/kg iron) or saline. In vivo magnetic resonance imaging (MRI) demonstrated strong plaque enhancement by the MFNPs (p < .001 vs. saline), which was confirmed by multimodality ex vivo MRI and fluorescence reflectance imaging. On fluorescence microscopy, MFNPs were found in cellular-rich areas of atheroma and colocalized with immunofluorescent macrophages over endothelial cells and smooth muscle cells (p < .001). CONCLUSIONS: Here we show that (1) the in vitro and in vivo cellular distribution of atherosclerosis-targeted MFNPs can be quantified by using fluorescence imaging methods; (2) in atherosclerosis, dextranated MFNPs preferentially target macrophages; and (3) MFNP deposition in murine atheroma can be noninvasively detected by in vivo MRI. This study thus provides a foundation for using MFNPs to image genetic and/or pharmacological perturbations of cellular inflammation in experimental atherosclerosis and for the future development of novel targeted nanomaterials for atherosclerosis.

Animals↗