Duchenne muscular dystrophy (DMD) is a fatal genetic disorder caused by mutations in the gene coding for dystrophin protein, which give rise to a dysfunctional protein in skeletal muscle. Dystrophic muscle progressively degenerates. In addition, necrotic muscle fibers undergo high levels of inflammation that in turn promote the pathology that is associated with this devastating disease. Therefore, treatments that 1) restore expression a functional dystrophin protein in dystrophic muscles, and 2) lower the ongoing inflammation in the necrotic muscle tissue, are both important in ameliorating DMD phenotype. Transfer of a functional dystrophin gene using a viral vector can help restore the missing dystrophin protein in dystrophic muscles. The host immune system, however, is a major barrier to successful vector-mediated dystrophin protein expression in a dystrophic host, as anti-dystrophin immune response leads to rejection of the protein. Here I show that temporal elimination of the host immune system by irradiation in the mdx mouse, a murine model of DMD, prior to vector-mediated dystrophin gene delivery, leads to a delayed and diminished host anti-dystrophin immune response. These findings are important for a better evaluation of anti-dystrophin immunity in a dystrophic host. In the case of lowering inflammation in dystrophic muscles, I investigated the effects of rapamycin, a potent immunosuppressant, on both dystrophic phenotype and dystrophin gene transfer in mdx mice. Treatment of adult mdx muscles with rapamycin lead to significantly lower levels of muscle fiber necrosis and reduced effector T cell infiltration in dystrophic muscles. These events correlated with a difference in activation of the mammalian target of rapamycin (mTOR) in the diaphragm muscle, but not the TA muscle, suggesting a differential regulation of mTOR activation in the two tissues. Rapamycin treatment, however, did not allow for a higher level of vector-mediated dystrophin protein expression in treated muscles. In general, these findings shed more light on the effects of manipulating the immune system in a dystrophic host in terms of both reducing the inflammation that is associated with DMD and reducing anti-dystrophin responses following gene therapy, suggesting that regulation of the immune system is essential in ameliorating DMD.
| Identifer | oai:union.ndltd.org:PITT/oai:PITTETD:etd-12092010-130005 |
| Date | 15 December 2010 |
| Creators | Eghtesad, Saman |
| Contributors | Penelope A. Morel, Ferruccio Glabiati, Paul D. Robbins, Paula R. Clemens, Robert M. O'Doherty |
| Publisher | University of Pittsburgh |
| Source Sets | University of Pittsburgh |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://etd.library.pitt.edu/ETD/available/etd-12092010-130005/ |
| Rights | restricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Pittsburgh or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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