UVM Theses and Dissertations
Format:
Print
Author:
Paveglio, Sara
Dept./Program:
Cell and Molecular Biology Program
Year:
2009
Degree:
Ph. D.
Abstract:
Allergic asthma is a disease with growing worldwide prevalence, the reasons for which are not fully understood. Due to the increase in prevalence, the cost of treatment is on the rise. Currently there are several treatments available which are targeted at various aspects of the disease, but in many individuals these therapies not affective. Corticosteroids remain the mainstay treatment, but have several side-effects. For these reasons better treatments are necessary.
The activities of CD4 T cells have been implicated as the driving force behind the features associated with asthma. In this dissertation the research performed focused on reducing the activities of these cells through the use of two proteins, indoleamine 2,3- dioxygenase (IDO) and a tick salivary protein, Salpl5. IDO exerts its effects through the metabolism of tryptophan, an essential as well as the least abundant amino acid. This metabolism results in cell death through two mechanisms. Due to the inability to incorporate tryptophan into proteins cells cannot proliferate. Moreover, the downstream catabolites of tryptophan metabolism are toxic to cells and have been demonstrated to induce apoptosis of cells. CD4⁺ T cells have been shown to be sensitive to the effects of IDO in several experimental models.
We created a triple transgenic mouse in which ID0 was overexpressed only within the non-ciliated airway epithelial cells of the lung. These mice have reduced lymphocytes within their bronchoalveolar lavage fluid following allergic sensitization to Aspergillus fumigatus. Furthermore, upon ex vivo restimulation of splenic CD4 T cells, these cells secrete less of the Th2 cytokines IL-4, IL-5 and IL-13 each of which have been associated with features of allergic asthma. These studies demonstrate that localized overexpression of ID0 has the ability to reduce features of allergic airway disease through the inhibition of the activities of effector CD4⁺ T cells.
The tick salivary protein Salpl5 binds to the D1 and D2 domains of the CD4 molecule on CD4 T cells resulting in the inhibition of downstream signaling which results in significantly reduced secretion of IL-2, a cytokine known to induce the proliferation of T cells. We have demonstrated that Salpl5 has the ability to reduce all features of allergic asthma when administered to mice at sensitization in a model of allergic asthma in which mice are sensitized with the Th2-skewing adjuvant ImjectAlum in conjunction with the antigen ovalbumin. Therefore, upon inhibition of the activities of CD4⁺ T cells at the onset of disease all features of allergic asthma can be reduced including BAL eosinophilia, Th2 cytokine secretion from effector CD4⁺ T cells, serum immunoglobulin levels of antigen-specific IgG₁ and IgE as well as airway hyperresponsiveness.
The activities of CD4 T cells have been implicated as the driving force behind the features associated with asthma. In this dissertation the research performed focused on reducing the activities of these cells through the use of two proteins, indoleamine 2,3- dioxygenase (IDO) and a tick salivary protein, Salpl5. IDO exerts its effects through the metabolism of tryptophan, an essential as well as the least abundant amino acid. This metabolism results in cell death through two mechanisms. Due to the inability to incorporate tryptophan into proteins cells cannot proliferate. Moreover, the downstream catabolites of tryptophan metabolism are toxic to cells and have been demonstrated to induce apoptosis of cells. CD4⁺ T cells have been shown to be sensitive to the effects of IDO in several experimental models.
We created a triple transgenic mouse in which ID0 was overexpressed only within the non-ciliated airway epithelial cells of the lung. These mice have reduced lymphocytes within their bronchoalveolar lavage fluid following allergic sensitization to Aspergillus fumigatus. Furthermore, upon ex vivo restimulation of splenic CD4 T cells, these cells secrete less of the Th2 cytokines IL-4, IL-5 and IL-13 each of which have been associated with features of allergic asthma. These studies demonstrate that localized overexpression of ID0 has the ability to reduce features of allergic airway disease through the inhibition of the activities of effector CD4⁺ T cells.
The tick salivary protein Salpl5 binds to the D1 and D2 domains of the CD4 molecule on CD4 T cells resulting in the inhibition of downstream signaling which results in significantly reduced secretion of IL-2, a cytokine known to induce the proliferation of T cells. We have demonstrated that Salpl5 has the ability to reduce all features of allergic asthma when administered to mice at sensitization in a model of allergic asthma in which mice are sensitized with the Th2-skewing adjuvant ImjectAlum in conjunction with the antigen ovalbumin. Therefore, upon inhibition of the activities of CD4⁺ T cells at the onset of disease all features of allergic asthma can be reduced including BAL eosinophilia, Th2 cytokine secretion from effector CD4⁺ T cells, serum immunoglobulin levels of antigen-specific IgG₁ and IgE as well as airway hyperresponsiveness.