Hypertension is the number one cause of death worldwide. Low-grade inflammation has been identified as one of the mechanisms contributing to blood pressure elevation and remodeling of the vasculature in hypertension. Mechanisms involved in vascular inflammation and hypertension remain elusive. Vasoactive peptides such as endothelin-1 (ET-1) and angiotensin II (Ang II), oxidative stress and infiltration of immune cells are increased in cardiovascular tissues of hypertensive individuals. Since the vasculature is a major regulator of blood pressure levels, the hypothesis has been proposed that vascular inflammatory responses contribute to development of hypertension. / Objectives of this thesis were 1) to investigate the role of T cells in development of vascular inflammation observed in genetically hypertensive rats, 2) to identify vascular sources of reactive oxygen species production in mineralocorticoid-induced hypertension and 3) to study the effect of peroxisome proliferator-activated receptor (PPAR)-gamma activators on vascular pro-inflammatory signaling pathways in Ang II-induced hypertension. / The first study that is part of this thesis shows that the transfer of chromosome 2 from normotensive to hypertensive rats reduces plasma levels of pro-inflammatory cytokines, expression of adhesion molecules and infiltration of T cells in aorta as well as resulting in lower blood pressure levels. These effects are accompanied by increased regulatory T cell mediators. We discovered that regulatory T cells are regulated by chromosome 2 and may be responsible for reducing inflammatory responses in hypertensive rats. / The second study of this thesis demonstrates in DOCA-salt hypertensive rats that superoxide (·O2-) production originates in part from xanthine oxidase activity induced by the ET-1 system and from mitochondrial sources, particularly complex II of the respiratory chain. We thus have uncovered two sources of reactive oxygen species (ROS) that can stimulate inflammatory responses in hypertension, since vascular ·O 2- production in this model was shown to induce vascular inflammation. / The third study of the thesis shows that activators of PPAR-gamma reduce blood pressure levels and signaling pathways including Akt/PKB, SHIP2, ERK1/2, 4E-BP1 in aorta and resistance arteries in Ang II-induced hypertension. PPARy acts as an anti-inflammatory transcription factor, and the present study suggests that Ang II down-regulates PPAR-gamma activity to exert its pro-inflammatory effects. / In conclusion, by targeting inflammatory mediators, it may be possible to reduce blood pressure levels in hypertensive animals. This suggests that inflammatory responses may play a crucial role in development of high blood pressure.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.115884 |
| Date | January 2008 |
| Creators | Viel, Émilie, 1975- |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Division of Experimental Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 003132968, proquestno: AAINR66665, Theses scanned by UMI/ProQuest. |
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