title: Cell-intrinsic transforming growth factor-beta signaling mediates virus-specific CD8+ T cell deletion and viral persistence in vivo.
abstract: Although deficient CD8(+) T cell responses have long been associated with chronic viral infections, the underlying mechanisms are still unclear. Here we report that sustained transforming growth factor-beta (TGF-beta) expression and phosphorylation of its signaling mediator, Smad-2, were distinctive features of virus-specific CD8(+) T cells during chronic versus acute viral infections in vivo. The result was TGF-beta-dependent apoptosis of virus-specific CD8(+) T cells that related to upregulation of the proapoptotic protein Bim during chronic infection. Moreover, selective attenuation of TGF-beta signaling in T cells increased the numbers and multiple functions of antiviral CD8(+) T cells and enabled rapid eradication of the persistence-prone virus and memory generation. Finally, we found that cell-intrinsic TGF-beta signaling was responsible for virus-specific-CD8(+) T cell apoptosis and decreased numbers but was not necessary for their functional exhaustion. Our findings reveal persisting TGF-beta-Smad signaling as a hallmark and key regulator of CD8(+) T cell responses during chronic viral infections in vivo.
authors: Division of Biological Sciences, University of California San Diego, La Jolla, CA 92093-0322, USA.
authors: Roberto
authors: R
authors: Tinoco
authors: Victor
authors: V
authors: Alcalde
authors: Yating
authors: Y
authors: Yang
authors: Karsten
authors: K
authors: Sauer
authors: Elina I
authors: EI
authors: Zuniga
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017209:Apoptosis / Q000276:immunology; D051017:Apoptosis Regulatory Proteins / Q000276:immunology* / Q000378:metabolism; D001117:Arenaviridae Infections / Q000276:immunology* / Q000821:virology; D000072224:Bcl-2-Like Protein 11; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D008212:Lymphocyte Depletion; D008217:Lymphocytic choriomeningitis virus / Q000276:immunology; D008565:Membrane Proteins / Q000276:immunology* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D010766:Phosphorylation / Q000276:immunology; D011518:Proto-Oncogene Proteins / Q000276:immunology* / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology; D051899:Smad2 Protein / Q000276:immunology* / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000276:immunology* / Q000378:metabolism
chemical_list: D051017:Apoptosis Regulatory Proteins; D000072224:Bcl-2-Like Protein 11; C000606776:Bcl2l11 protein, mouse; D008565:Membrane Proteins; D011518:Proto-Oncogene Proteins; D051899:Smad2 Protein; C497783:Smad2 protein, mouse; D016212:Transforming Growth Factor beta