title: Gene expression profiling of suppressor mechanisms in tuberculosis.
abstract: Mycobacterium tuberculosis (M.tb) infects 8 million and kills 2.2 million people each year worldwide. M.tb modulates the immune response of the infected individual. Empirically, suppressor carbohydrates (SC) produced by CD8+ T cells in response to M.tb were found to induce a T helper 2 response rather than a protective T helper 1 response in human mononuclear (MN) cells. This study (1) identifies the genes that modulate the T helper response, (2) describes their function, and (3) postulates a detailed model for the M.tb infection mechanism. MN cells from five healthy donors were pulsed with SC and gene expression profiles of 18,861 genes were assessed in a micro-array experiment. Twenty-eight genes were found to be increased and 60 genes were decreased (FDR=1%, fold change>1.4) in response to SC. MIP3 alpha and platelet factor 4 (v1) are both significantly enriched (p< or =0.001) in the GO category "chemokine activity". Repressed genes were significantly (p< or =0.001) over-represented in the GO terms "response to pathogenic bacteria", "inflammatory response", "coagulation" and "apoptosis". Indeed, SC significantly reduced numbers of Annexin V/CD4+ cells, while inducing hypoproliferation in CD4+ and non-adherent lymphocytes. This may indicate that M.tb renders a portion of the CD4+ T cell population unresponsive. Furthermore, validating QRT-PCR analysis suggests that monocytes provide an immuno-modulatory signal to CD4+ T cells in M.tb infection. These observations will allow development of new therapeutic interventions to restore the desired T helper 1 response.
authors: Department of Immunology, School of Pathology, National Health Laboratory Service & University of the Witwatersrand, 1 Hospital Street, Hospital Hill, Johannesburg, South Africa. mieneke.smit@nhls.ac.za <mieneke.smit@nhls.ac.za>
authors: Mieneke G A
authors: MG
authors: Smit van Dixhoorn
authors: Riffat
authors: R
authors: Munir
authors: Garth
authors: G
authors: Sussman
authors: Robert
authors: R
authors: Stad
authors: Muus
authors: M
authors: de Haan
authors: Tessa
authors: T
authors: van der Hoeven
authors: Han
authors: H
authors: Rauwerda
authors: Timo M
authors: TM
authors: Breit
authors: Gerhard G
authors: GG
authors: Thallinger
authors: Ahmed A
authors: AA
authors: Wadee
mesh_terms: D017209:Apoptosis; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D020869:Gene Expression Profiling; D006801:Humans; D066298:In Vitro Techniques; D009000:Monocytes / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000502:physiology*; D013491:Suppressor Factors, Immunologic / Q000378:metabolism*; D014397:Tuberculosis, Pulmonary / Q000276:immunology / Q000378:metabolism*
chemical_list: D013491:Suppressor Factors, Immunologic