Defense Date

2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Microbiology & Immunology

First Advisor

Daniel Conrad

Abstract

Fullerenes are carbon nanospheres that can be solublized by the addition of polar chemical groups to the carbon cage, forming fullerene derivatives. One specifically derivatized fullerene compound, termed C70-Tetragylocolate (C70-TGA), has been shown to stabilize mast cell responses in vitro thus we hypothesized it may have an effect on mast cell-driven diseases such as asthma and systemic anaphylaxis. To observe the effects of C70-TGA on systemic anaphylaxis, mice were subjected to a model of passive systemic anaphylaxis. In this model, mice were injected with DNP-specific IgE 16 hours prior to challenge, then treated with C70-TGA. Immediately prior to DNP challenge, mice were subjected to a second injection of C70-TGA. Following DNP challenge, body temperature was recorded and blood was collected for quantitation of histamine levels. Treatment with C70-TGA significantly reduced body temperature drop associated with systemic anaphylaxis and serum histamine levels. To observe the effects of C70-TGA on chronic features of asthma in vivo, we utilized a heavily MC influenced model of asthma pathogenesis. Mice were sensitized by intraperitoneal (i.p.) injection of ovalbumin (OVA) in saline, challenged intranasally (i.n.) with OVA, and one of two treatment strategies was pursued. In one, C70-TGA was given i.n. throughout disease development. In the other, C70-TGA was given following an initial set of challenges to allow disease to develop prior to treatment; mice were then re-challenged with OVA to assess the effect on established disease. We found that C70-TGA treatment significantly reduced airway inflammation and eosinophilia and dramatically reduced bronchoconstriction in either model. Cytokines IL-4 and IL-5 and serum IgE levels are significantly reduced in C70-TGA treated animals. Interestingly, we also saw an increase in the anti-inflammatory eicosanoid 11, 12-epoxyeicosatreinoic acid (11,12-EET) in the BAL fluid, suggesting the involvement of this mediator in C70-TGA inhibition. Further experiments utilizing an inhibitor of 11,12-EET formation (6-(2-Propargyloxyphenyl)hexanoic acid) and a structural analog of 14,15-EET (14,15-EE-5(Z)-E) in vivo indicate that these mediators are closely associated with C70-TGA mediated inhibition as their inhibition reverses the anti-inflammatory effects of C70-TGA. Importantly, mice did not exhibit any acute toxicity following C70-TGA treatment and liver and kidney function were normal. Collectively, these results show that the fullerene C70 derivative C70-TGA is capable of dampening severe allergic responses including systemic anaphylaxis, airway inflammation, and bronchoconstriction. The mechanism of inhibition is through the upregulation of the anti-inflammatory EETs, which may dampen mast cell degranulation in vivo, thus contributing to the inhibitory effect of C70-TGA on allergic disease.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

May 2012

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