title: Secreted immunodominant Mycobacterium tuberculosis antigens are processed by the cytosolic pathway.
abstract: Exposure to Mycobacterium tuberculosis can result in lifelong but asymptomatic infection in most individuals. Although CD8(+) T cells are elicited at high frequencies over the course of infection in both humans and mice, how phagosomal M. tuberculosis Ags are processed and presented by MHC class I molecules is poorly understood. Broadly, both cytosolic and noncytosolic pathways have been described. We have previously characterized the presentation of three HLA-I epitopes from M. tuberculosis and shown that these Ags are processed in the cytosol, whereas others have demonstrated noncytosolic presentation of the 19-kDa lipoprotein as well as apoptotic bodies from M. tuberculosis-infected cells. In this paper, we now characterize the processing pathway in an additional six M. tuberculosis epitopes from four proteins in human dendritic cells. Addition of the endoplasmic reticulum-Golgi trafficking inhibitor, brefeldin A, resulted in complete abrogation of Ag processing consistent with cytosolic presentation. However, although addition of the proteasome inhibitor epoxomicin blocked the presentation of two epitopes, presentation of four epitopes was enhanced. To further examine the requirement for proteasomal processing of an epoxomicin-enhanced epitope, an in vitro proteasome digestion assay was established. We find that the proteasome does indeed generate the epitope and that epitope generation is enhanced in the presence of epoxomicin. To further confirm that both the epoxomicin-inhibited and epoxomicin-enhanced epitopes are processed cytosolically, we demonstrate that TAP transport and new protein synthesis are required for presentation. Taken together, these data demonstrate that immunodominant M. tuberculosis CD8(+) Ags are processed and presented using a cytosolic pathway.
authors.affiliation: Division of Infectious Diseases, Department of Pediatrics, Oregon Health and Science University, Portland, OR 97239, USA.
authors.forename: Jeff E
authors.initials: JE
authors.lastname: Grotzke
authors.forename: Anne C
authors.initials: AC
authors.lastname: Siler
authors.forename: Deborah A
authors.initials: DA
authors.lastname: Lewinsohn
authors.forename: David M
authors.initials: DM
authors.lastname: Lewinsohn
mesh_terms: D000818:Animals; D017951:Antigen Presentation / Q000276:immunology*; D000942:Antigens, Bacterial / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D003600:Cytosol / Q000276:immunology* / Q000378:metabolism; D003713:Dendritic Cells / Q000276:immunology / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000276:immunology / Q000378:metabolism; D018984:Epitopes, T-Lymphocyte / Q000276:immunology; D006056:Golgi Apparatus / Q000276:immunology / Q000378:metabolism; D006801:Humans; D016056:Immunodominant Epitopes / Q000276:immunology* / Q000378:metabolism; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D009169:Mycobacterium tuberculosis / Q000276:immunology; D046988:Proteasome Endopeptidase Complex / Q000276:immunology / Q000378:metabolism
chemical_list: D000942:Antigens, Bacterial; D018984:Epitopes, T-Lymphocyte; D016056:Immunodominant Epitopes; C072681:Mycobacterium tuberculosis antigens; D046988:Proteasome Endopeptidase Complex
references.citation: J Biol Chem. 1999 Feb 5;274(6):3363-71
references.pmid: 9920878
references.citation: Annu Rev Cell Dev Biol. 2004;20:367-94
references.pmid: 15473845
references.citation: Immunity. 2004 Aug;21(2):155-65
references.pmid: 15308097
references.citation: J Immunol. 1998 Jun 1;160(11):5448-54
references.pmid: 9605147
references.citation: J Immunol. 2006 Sep 15;177(6):3525-33
references.pmid: 16951311
references.citation: Science. 1998 Oct 2;282(5386):121-5
references.pmid: 9756476
references.citation: J Exp Med. 2001 Jul 2;194(1):1-12
references.pmid: 11435468
references.citation: Microbes Infect. 2005 Apr;7(4):776-88
references.pmid: 15823514
references.citation: Nature. 1999 Mar 4;398(6722):77-80
references.pmid: 10078533
references.citation: Cell. 2007 Jun 29;129(7):1287-98
references.pmid: 17604718
references.citation: PLoS Pathog. 2009 Apr;5(4):e1000374
references.pmid: 19360129
references.citation: Curr Top Microbiol Immunol. 2002;269:87-99
references.pmid: 12224518
references.citation: Traffic. 2000 Mar;1(3):235-47
references.pmid: 11208107
references.citation: PLoS Pathog. 2007 Sep 21;3(9):1240-9
references.pmid: 17892322
references.citation: J Immunol. 2007 Sep 15;179(6):3973-81
references.pmid: 17785835
references.citation: Science. 2004 Jun 18;304(5678):1800-4
references.pmid: 15155913
references.citation: Blood. 2003 Dec 15;102(13):4448-55
references.pmid: 12933572
references.citation: J Immunol. 2001 Aug 1;167(3):1274-82
references.pmid: 11466343
references.citation: J Bacteriol. 2007 Aug;189(16):6028-34
references.pmid: 17557817
references.citation: Immunity. 1996 Apr;4(4):349-55
references.pmid: 8612129
references.citation: Nat Immunol. 2008 Aug;9(8):937-44
references.pmid: 18587399
references.citation: Eur J Cell Biol. 2001 Jan;80(1):31-40
references.pmid: 11211933
references.citation: Nat Med. 2003 Aug;9(8):1039-46
references.pmid: 12872166
references.citation: Nat Immunol. 2003 Apr;4(4):375-9
references.pmid: 12598896
references.citation: Infect Immun. 2000 Dec;68(12):6997-7002
references.pmid: 11083824
references.citation: Immunity. 2006 Oct;25(4):607-17
references.pmid: 17027300
references.citation: J Immunol. 2006 Jul 1;177(1):437-42
references.pmid: 16785540
references.citation: Nature. 1993 Jan 28;361(6410):359-62
references.pmid: 7678924
references.citation: J Exp Med. 1994 Oct 1;180(4):1499-509
references.pmid: 7931080
references.citation: J Exp Med. 1998 May 18;187(10):1633-40
references.pmid: 9584141
references.citation: J Exp Med. 2009 Feb 16;206(2):399-410
references.pmid: 19153244
references.citation: Proc Natl Acad Sci U S A. 2005 Mar 15;102(11):4033-8
references.pmid: 15753315
references.citation: Infect Immun. 2008 Sep;76(9):4199-205
references.pmid: 18591224
references.citation: Annu Rev Immunol. 2001;19:93-129
references.pmid: 11244032
references.citation: J Immunol. 2001 Nov 15;167(10):5549-57
references.pmid: 11698425
references.citation: J Immunol. 2003 Sep 1;171(5):2242-50
references.pmid: 12928368
references.citation: Cell. 1994 May 20;77(4):525-35
references.pmid: 8187174
references.citation: J Immunol. 2001 Jan 1;166(1):447-57
references.pmid: 11123323
references.citation: J Immunol. 2006 Jul 15;177(2):983-90
references.pmid: 16818754
references.citation: J Biol Chem. 2006 Dec 29;281(52):39925-34
references.pmid: 17088258
references.citation: Proc Natl Acad Sci U S A. 2003 Oct 14;100(21):12420-5
references.pmid: 14557547
references.citation: J Immunol. 2000 Feb 15;164(4):2016-20
references.pmid: 10657653
references.citation: Infect Immun. 2005 Feb;73(2):703-11
references.pmid: 15664908
references.citation: J Virol. 2007 Nov;81(21):11925-36
references.pmid: 17699574
references.citation: Clin Exp Immunol. 2003 Oct;134(1):70-7
references.pmid: 12974757
references.citation: J Immunol. 2005 Dec 1;175(11):7474-83
references.pmid: 16301655
references.citation: Nat Immunol. 2004 Jul;5(7):670-7
references.pmid: 15224092
references.citation: Am J Respir Crit Care Med. 2003 Dec 1;168(11):1346-52
references.pmid: 12969871
references.citation: J Immunol. 2000 Jun 15;164(12):6147-57
references.pmid: 10843664
references.citation: J Exp Med. 2002 Dec 2;196(11):1473-81
references.pmid: 12461082
references.citation: Science. 1995 Jan 13;267(5195):243-6
references.pmid: 7809629
references.citation: J Immunol. 2001 Jan 1;166(1):439-46
references.pmid: 11123322