Browsing by Subject "Macrophage"
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Item Development and application of optical imaging techniques in diagnosing cardiovascular disease(2012-05) Wang, Tianyi, 1982-; Milner, Thomas E.; Feldman, Marc; Johnston, Keith; Dunn, Andrew; Tunnell, JamesAtherosclerosis and specifically rupture of vulnerable plaques account for 23% of all deaths worldwide, far surpassing both infectious diseases and cancer. Plaque-based macrophages, often associated with lipid deposits, contribute to atherogenesis from initiation through progression, plaque rupture and ultimately, thrombosis. Therefore, the macrophage is an important early cellular marker related to vulnerability of atherosclerotic plaques. The objective of my research is to assess the ability of multiple optical imaging modalities to detect, and further characterize the distribution of macrophages (having taken up plasmonic gold nanoparticles as a contrast agent) and lipid deposits in atherosclerotic plaques. Tissue phantoms and macrophage cell cultures were used to investigate the capability of nanorose as an imaging contrast agent to target macrophages. Ex vivo aorta segments from a rabbit model of atherosclerosis after intravenous nanorose injection were imaged by optical coherence tomography (OCT), photothermal imaging (PTW) and two-photon luminescence microscopy (TPLM), respectively. OCT images depicted detailed surface structure of atherosclerotic plaques. PTW images identified nanorose-loaded macrophages (confirmed by co-registration of a TPLM image and corresponding RAM-11 stain on a histological section) associated with lipid deposits at multiple depths. TPLM images showed three-dimensional distribution of nanorose-loaded macrophages with a high spatial resolution. Imaging results suggest that superficial nanorose-loaded macrophages are distributed at shoulders on the upstream side of atherosclerotic plaques at the edges of lipid deposits. Combination of OCT with PTW or TPLM can simultaneously reveal plaque structure and composition, permitting assessment of plaque vulnerability during cardiovascular interventions.Item Influence of insulin-like growth factor-I on skeletal muscle regeneration(2012-12) Hammers, David Wayne; Farrar, Roger P; Suggs, Laura J; Adamo, Martin L; Sweeney, H. Lee; Thompson, Wesley J; Ivy, John LSkeletal muscle regeneration involves a tightly regulated coordination of cellular and signaling events to remodel and repair the site of injury. When this coordination is perturbed, the regenerative process is impaired. The expression of insulin-like growth factor-I (IGF-I) is robust in the typical muscle regenerative program, promoting cell survival and increasing myoblast activity. In this project, we found that severely depressed IGF-I expression and intracellular signaling in aged skeletal muscle coincided with impaired regeneration from ischemia/reperfusion (I/R). To hasten muscle regeneration, we developed the PEGylated fibrin gel (PEG-Fib) system as a means to intramuscularly deliver IGF-I in a controlled manner to injured muscle. This strategy resulted in greatly improved muscle function and histological assessment following 14 days of reperfusion, which are likely mediated by improved myofiber survival. Recent evidence suggests macrophages (MPs) are responsible for the upregulation of IGF-I following injury, therefore we developed a rapid, reproducible, and cost-effective model of investigating MP profiles in injured muscle via flow cytometry. Using information gathered from this model, we found that increasing the number of a non-inflammatory MP population improves the recovery of muscle from I/R. These data demonstrate that immunomodulatory therapies have the potential to greatly improve the recovery of skeletal muscle from injury.Item Macrophage Polarization And Nitric Oxide Mechanisms In Lymphatic Dysfunction In A Rat Model Of Metabolic Syndrome(2014-12-10) Zawieja, Scott DMetabolic syndrome (MetSyn) is the clustering of multiple metabolic disorders that further increase the risk for cardiovascular disease and has been recently linked to poor lymphatic function. The lymphatic system plays a crucial role in maintaining oncotic balance and returning excess fluid and macromolecules back to the blood circulation. In this dissertation we addressed the role of macrophage polarization and nitric oxide mechanisms in lymphatic dysfunction in a rat model of MetSyn. We hypothesized that mesenteric lymphatic vessel dysfunction would be associated with a polarization switch of resident macrophages after induction of peritonitis or metabolic syndrome. We used an intra-peritoneal injection of lipopolysaccharide (LPS) to simulate peritonitis in the rat and a seven-week high fructose-feeding regime to induce the MetSyn. We distinguished macrophage polarization and recruitment to the lymphatic collecting vessels using immunofluorescence and a combination of CD163, CD206, and major histocompatibility complex II (MHCII) expression. We determined the intrinsic mesenteric lymphatic contractility using the isolated mesenteric lymphatic vessel isobaric preparation. LPS-induced peritonitis increased the macrophage accumulation two fold and increased both CD163+CD206+ and CD163-CD206+ cell populations and had severely impaired lymphatic contractility. We also found evidence for a phenotype switch from CD163+MHCII- M2 macrophages to a M1 skewed CD163+MHCII+ phenotype in the MetSyn rats and impaired lymphatic contractility. Additionally, cultured lymphatic endothelial and muscle cells were found to express macrophage maturation and expansion markers in response to LPS stimulation. We also examined the role of nitric oxide in the contractile regulation of lymphatic thoracic ducts isolated from MetSyn rats. We found a reduced flow-dependent inhibition of contractility in metabolic syndrome thoracic ducts despite a normal response to the exogenous nitric oxide donor S-nitro-N-acetylpenicillamine (SNAP). The reactive oxygen species scavenging agent 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) did not restore flow sensitivity, however control vessels treated with the nitric oxide synthase inhibitor L-NG-nitro arginine methyl ester (LNAME) had comparable flow inhibition to MetSyn thoracic ducts. Western blots of thoracic ducts revealed a 60% reduction in the expression of eNOS, which can explain the loss of shear sensitivity. Thus, this study demonstrates the mechanisms that underlie lymphatic dysfunction in the MetSyn.Item New Insights Into the Role of Equine Infectious Anemia Virus S2 Protein in Disease Expression(2011-08-08) Covaleda Salas, Lina M.Equine infectious anemia virus (EIAV) is an important animal model to study the contribution of macrophages in viral persistence during lentiviral infections. EIAV is unique amongst the lentiviruses in that it causes a rapid, rather than the very slow disease progression, characteristic of other lentiviral infections. The accessory gene, S2, unique to EIAV, is an important determinant in viral pathogenesis. A functional S2 gene is required to achieve high-titer viremia and the development of disease in infected horses. Despite its essential role, the mechanisms by which S2 influences EIAV pathogenesis remain elusive. The goal of this research was to gain insight into the role of S2 in pathogenesis. To accomplish this goal we: (i) Examined the effects of EIAV and its S2 protein in the regulation of the cytokine and chemokine responses in macrophages, (ii) Assessed the influence of EIAV infection and the effect of S2 on global gene expression in macrophages and (iii) Identified host cellular proteins that interact with S2 as a starting point for the identification of host factors implicated in S2 function. The results from this study provide evidence for a role of S2 in enhancing a proinflammatory cytokine and chemokine response in infected macrophages. Specifically, S2 enhances the expression of IL-1 alpha, IL-1 beta IL-8, MCP-2, MIP-1 beta, IP-10 and a newly discovered cytokine, IL-34. Involvement of S2 in cytokine and chemokine dysregulation may contribute to disease development by optimizing the host cell environment to promote viral dissemination and replication. Microarray analyses revealed an interesting set of differentially expressed genes upon EIAV infection. Genes affected by EIAV were involved in the immune response, transcription, translation, cell cycle and cell survival. Finally, we used the yeast two-hybrid system to identify S2 host cellular interacting proteins. We identified osteosarcoma amplified 9 (OS-9) and proteasome 26S ATPase subunit 3 (PSMC3) proteins as interacting partners of S2. Additional evidence is needed to demonstrate the physiological relevance of these interactions in vivo. In summary, the results from this study contribute towards our understanding of the role S2 in disease expression and allow the formulation of new hypotheses as to the potential mechanisms of action of S2 during EIAV infection.