title: Mannose-Capped Lipoarabinomannan from Mycobacterium tuberculosis Induces CD4+ T Cell Anergy via GRAIL.
abstract: Mycobacterium tuberculosis cell wall glycolipid, lipoarabinomannan, can inhibit CD4(+) T cell activation by downregulating the phosphorylation of key proximal TCR signaling molecules: Lck, CD3ζ, ZAP70, and LAT. Inhibition of proximal TCR signaling can result in T cell anergy, in which T cells are inactivated following an Ag encounter, yet remain viable and hyporesponsive. We tested whether mannose-capped lipoarabinomannan (LAM)-induced inhibition of CD4(+) T cell activation resulted in CD4(+) T cell anergy. The presence of LAM during primary stimulation of P25 TCR-transgenic murine CD4(+) T cells with M. tuberculosis Ag85B peptide resulted in decreased proliferation and IL-2 production. P25 TCR-transgenic CD4(+) T cells primed in the presence of LAM also exhibited decreased response upon restimulation with Ag85B. The T cell anergic state persisted after the removal of LAM. Hyporesponsiveness to restimulation was not due to apoptosis, generation of Foxp3-positive regulatory T cells, or inhibitory cytokines. Acquisition of the anergic phenotype correlated with upregulation of gene related to anergy in lymphocytes (GRAIL) protein in CD4(+) T cells. Inhibition of human CD4(+) T cell activation by LAM also was associated with increased GRAIL expression. Small interfering RNA-mediated knockdown of GRAIL before LAM treatment abrogated LAM-induced hyporesponsiveness. In addition, exogenous IL-2 reversed defective proliferation by downregulating GRAIL expression. These results demonstrate that LAM upregulates GRAIL to induce anergy in Ag-reactive CD4(+) T cells. Induction of CD4(+) T cell anergy by LAM may represent one mechanism by which M. tuberculosis evades T cell recognition.
authors.affiliation: Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH 44106; Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and Department of Pathology, Case Western Reserve University, Cleveland, OH 44106.
authors.forename: Obondo J
authors.initials: OJ
authors.lastname: Sande
authors.affiliation: Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH 44106; Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and.
authors.forename: Ahmad F
authors.initials: AF
authors.lastname: Karim
authors.affiliation: Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and.
authors.forename: Qing
authors.initials: Q
authors.lastname: Li
authors.affiliation: Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH 44106; Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and.
authors.forename: Xuedong
authors.initials: X
authors.lastname: Ding
authors.affiliation: Department of Pathology, Case Western Reserve University, Cleveland, OH 44106.
authors.forename: Clifford V
authors.initials: CV
authors.lastname: Harding
authors.affiliation: Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH 44106; Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and.
authors.forename: Roxana E
authors.initials: RE
authors.lastname: Rojas
authors.affiliation: Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH 44106; Department of Molecular Biology and Microbiology, Case Western Reserve University, Cleveland, OH 44106; and Department of Pathology, Case Western Reserve University, Cleveland, OH 44106 whb@cwru.edu.
authors.forename: W Henry
authors.identifier: http://orcid.org/0000-0001-5760-9595
authors.initials: WH
authors.lastname: Boom
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D002478:Cells, Cultured; D000090266:Chromobox Protein Homolog 5; D017635:Clonal Anergy / Q000276:immunology*; D005260:Female; D005434:Flow Cytometry; D055785:Gene Knockdown Techniques; D006801:Humans; D057131:Immune Evasion / Q000276:immunology*; D008070:Lipopolysaccharides / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D008358:Mannose / Q000276:immunology; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D018613:Microscopy, Confocal; D009169:Mycobacterium tuberculosis / Q000276:immunology; D034741:RNA, Small Interfering; D014376:Tuberculosis / Q000276:immunology*; D044767:Ubiquitin-Protein Ligases / Q000276:immunology*
chemical_list: C000715594:CBX5 protein, human; D008070:Lipopolysaccharides; D034741:RNA, Small Interfering; C050016:lipoarabinomannan; D000090266:Chromobox Protein Homolog 5; C520250:RNF128 protein, human; D044767:Ubiquitin-Protein Ligases; D008358:Mannose