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“Telomerase-Based Therapy for Enhancing Immunity”. by Steven Fauce, Ph.D. Department of Pathology and Laboratory Medicine David Geffen School of Medicine UCLA Monday, April 14, 2008; 8:00 PM Los Angeles Gerontology Research Group. Cells of the Immune System. Cells of the Immune System.
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“Telomerase-Based Therapy for Enhancing Immunity” by Steven Fauce, Ph.D. Department of Pathology and Laboratory Medicine David Geffen School of Medicine UCLA Monday, April 14, 2008; 8:00 PM Los Angeles Gerontology Research Group
Cells of the Immune System CD4+ CD8+
Cells of the Immune System CD4+ CD8+
Repeated stimulation of T cells T antigen T T T Infected Cell T T T T T T T T T T T T T T T T T T T T T T senescence
Repeated stimulation of T cells T antigen T T T Infected Cell T T T T T T T T T T T T T T T T T T T T T T
Repeated stimulation of T cells T antigen T T T Infected Cell T T T T T T T T T T T T T T T T T T T T T T
Repeated stimulation of T cells T T T T Infected Cell Infected Cell T T T T T T T T T T T T T T T T T T T T T T
Repeated stimulation of T cells T T T T Infected Cell Infected Cell T T T T T T T T T T T T T T T T Infected Cell T T T T T T senescence
Replicative senescence • Irreversible state of growth arrest • Consequence of cell division • Normal human somatic cells • Altered function and gene expression • SHORTENED TELOMERES
Telomeres • repeated series of DNA at chromosome ends • essential for chromosomal stability • shortens during each cell division • signals replicative senescence
TELOMERASE counteracts this effect Present in germ cells, stem cells, and activated immune cells
TELOMERASE counteracts this effect Present in germ cells, stem cells, and activated immune cells
Telomere Length and Telomerase in Chronic Infection • Many similarities in the cells of the immune system of elderly and HIV+ • HIV-infection and AIDS has been described as premature and rapid “aging” of the immune system
Hypothesis Maintaining high levels of telomerase activity in CD8 T cells may allow for increased and prolonged function of the immune system during aging or chronic viral infection
hTERT Transduction CD8+ + IL-2 T APC T T APC T gag/pol/env T T gag/pol/env T T T T T hTERT T T T T T T T T puromycin
hTERT-transduced CD8+ cells Dagarag M, Evazyan T, Rao N, Effros RB.. J. Immunol. 2004; 173: 6303-11
Anti-viral function of hTERT-transduced CD8+ T cells Dagarag M, Ng H, Lubong R, Effros RB, Yang OO.. J. Virol. 2003; 77: 3077-83.
Problems with Gene Therapy • Logistics • Gene control and targeting issues • Gene must be long-lived and stable after integration
Problems with Gene Therapy • Logistics • Gene control and targeting issues • Gene must be long-lived and stable after integration • 2) Safety Issues • - DNA integration sites • - Possibly contribute to malignancy • - Toxicity • - Immune and inflammatory responses
Geron Corporation • Initial screen of natural sources to find extracts that could be considered for use in a wide range clinical therapies
Geron Corporation • Initial screen of natural sources to find extracts that could be considered for use in a wide range clinical therapies • Isolated compound (TAT2) that showed the ability to increase telomerase activity in skin cells