Master's Thesis Defense - Targeting Inflammation Markers with Quantum Dots in vivo in DSS Model of Ulcerative Colitis
Date: December 20, 2005
Time: 4:00 PM
Location: LeBow Engineering Center, Room: 231
Advisor: Elisabeth Papazoglou, Ph.D.
Inflammatory Bowel Disease is one of the most debilitative chronic diseases affecting nearly 1.5 million people. At present, there is no efficient and reliable method to quantify the degree of inflammation – the most important clinical correlate of IBD. The quantification of Myeloperoxidase (MPO), a lysosomal enzyme which is an excellent biomarker of inflammation in autoimmune and inflammatory diseases requires tedious extraction techniques and often yields inconsistent results.
The objective of this project was to image and quantitatively measure the concentration of MPO conjugated with Quantum Dots (QDs) in the lamina propria of mice colon with experimentally induced colitis. QDs are novel nanometer size fluorescent markers, with distinct advantages of high quantum yield and excellent photostability making them great tools for dynamic monitoring of disease progression. MPO is an important indicator of neutrophils and reactive oxygen species present in acute inflammation. Antibodies specific to MPO were conjugated to Quantum Dots and tested in vivo in acute inflammation and in the Dextran Sulfate (DSS) model for colitis. The resulting fluorescence intensity was then used as a measure of concentration of MPO and in turn inflammation. Experiments were performed to test the efficiency and specificity of these antibody-bound QDs. Inflammation was induced in the colon of Swiss Webster mice by feeding 4% DSS in tap water. The colon was exposed to QD conjugates, washed, excised, and frozen. Histological slides (15 ?M thickness) were prepared and imaged with a Leica confocal microscope. The experimental procedure was repeated on different days of DSS feed.
The images showed the presence of QDs complexing with MPO in the areas of inflammation. QDs were absent in control colon tissue devoid of inflammation. The results show that QD bioconjugates specific for MPO can be designed and use to characterize inflammation. The fluorescent images obtained from animals showed increasing fluorescence intensity as the days of DSS feed increases suggesting a relation between inflammation and fluorescence intensity. Subsequent quantification of images showed a very good correlation (R= 0.96) between fluorescence intensity and disease severity. The project also attempted to target multiple biomarkers simultaneously using different color QDs. The biomarkers targeted include proinflammatory cytokines IL1? and TNF? along with MPO. Fluorescent images showed colocalization of all the three markers in both acute as well as chronic inflammation in accordance with the observations made earlier in the same model.
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