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Role of angiostatin in neutrophil biology and acute lung injury

dc.contributor.advisorBaljit Singhen_US
dc.contributor.committeeMemberGeorge Mutwirien_US
dc.contributor.committeeMemberMaria Fernandesen_US
dc.contributor.committeeMemberJaswant Singhen_US
dc.contributor.committeeMemberMatthew Loewenen_US
dc.contributor.committeeMemberLixin Liuen_US
dc.creatorAulakh, Gurpreet Kauren_US 2011en_US
dc.description.abstractAcute lung injury is marked by profound neutrophil influx along with fluid accumulation that impairs lung function at the cost of high mortality (up to 40%). Neutrophils are activated and their constitutive apoptosis is inhibited during this phase in order to be competent phagocytes over the next few hours. Activated neutrophils release copious amounts of toxic mediators that cause tissue damage leading to impaired barrier function and finally, impaired lung function. Therefore, one of the critical needs is to identify molecules that regulate neutrophil migration and silence activated neutrophils to prevent exuberant tissue damage. Angiostatin is an anti-angiogenic molecule highly expressed in lavage fluid of patients with acute respiratory distress syndrome. Angiostatin has recently been shown to inhibit neutrophil infiltration in mice peritonitis. However, the role of angiostatin in modulating neutrophil physiology and lung inflammation remains unknown. I studied the role of angiostatin, an anti-angiogenic molecule, in neutrophil activation and recruitment in vivo and in vitro. Angiostatin was endocytosed only by activated neutrophils, inhibited neutrophil polarity in fMLP-activated neutrophils probably through integrin αVβ3, and inhibited MAPK signalling in LPS-activated neutrophils. Angiostatin suppressed formation of reactive oxygen species and activated caspase-3 in neutrophils in both pre-and post-LPS treatments. Finally, angiostatin reduced adhesion and emigration of neutrophils in post-capillary venules of TNFα-treated cremaster muscle. The next study was designed to investigate the role of angiostatin in acute lung injury. I used E. coli lipopolysaccharide induced acute lung injury mouse model to test the effects of angiostatin through analyses of bronchoalveolar lavage and lung tissues. In addition, I made novel use of synchrotron diffraction enhanced imaging of mouse lungs to assess lung area and contrast ratios over 9 hours as surrogates for lung inflammation. Subcutaneous treatment with angiostatin reduced neutrophil influx, protein accumulation, lung Gr1+ neutrophils and myeloperoxidase activity, phosphorylated p38 MAPK without affecting the levels of MIP-1α, IL-1β, KC and MCP-1 in lavage and lung homogenates. Diffraction enhanced imaging showed that angiostatin causes a time-dependent improvement in lung area and lung contrast ratios that reflect improvement in lung edema. Overall, the study shows that angiostatin is a novel inhibitor of acute lung injury in mice. Moreover, DEI offers a highly useful technique in evaluating dynamics of lung inflammation and to investigate the therapeutic impact of new drugs on lung inflammation. I conclude that angiostatin is a novel inhibitor of neutrophil migration, activation and acute lung injury.en_US
dc.subjectAcute Lung Injuryen_US
dc.subjectIntravital microscopyen_US
dc.subjectConfocal microscopyen_US
dc.subjectDiffraction enhanced imagingen_US
dc.titleRole of angiostatin in neutrophil biology and acute lung injuryen_US
dc.type.materialtexten_US Biomedical Sciencesen_US Biomedical Sciencesen_US of Saskatchewanen_US of Philosophy (Ph.D.)en_US


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