title: Helminth infections coincident with active pulmonary tuberculosis inhibit mono- and multifunctional CD4+ and CD8+ T cell responses in a process dependent on IL-10.
abstract: Tissue invasive helminth infections and tuberculosis (TB) are co-endemic in many parts of the world and can trigger immune responses that might antagonize each other. We have previously shown that helminth infections modulate the Th1 and Th17 responses to mycobacterial-antigens in latent TB. To determine whether helminth infections modulate antigen-specific and non-specific immune responses in active pulmonary TB, we examined CD4(+) and CD8(+) T cell responses as well as the systemic (plasma) cytokine levels in individuals with pulmonary TB with or without two distinct helminth infections-Wuchereria bancrofti and Strongyloides stercoralis infection. By analyzing the frequencies of Th1 and Th17 CD4(+) and CD8(+) T cells and their component subsets (including multifunctional cells), we report a significant diminution in the mycobacterial-specific frequencies of mono- and multi-functional CD4(+) Th1 and (to a lesser extent) Th17 cells when concomitant filarial or Strongyloides infection occurs. The impairment in CD4(+) and CD8(+) T cell cytokine responses was antigen-specific as polyclonal activated T cell frequencies were equivalent irrespective of helminth infection status. This diminution in T cell responses was also reflected in diminished circulating levels of Th1 (IFN-γ, TNF-α and IL-2)- and Th17 (IL-17A and IL-17F)-associated cytokines. Finally, we demonstrate that for the filarial co-infections at least, this diminished frequency of multifunctional CD4(+) T cell responses was partially dependent on IL-10 as IL-10 blockade significantly increased the frequencies of CD4(+) Th1 cells. Thus, co-existent helminth infection is associated with an IL-10 mediated (for filarial infection) profound inhibition of antigen-specific CD4(+) T cell responses as well as protective systemic cytokine responses in active pulmonary TB.
authors.affiliation: ICER Department, National Institutes of Health-NIRT-International Center for Excellence in Research, Chennai, India.
authors.forename: Parakkal Jovvian
authors.initials: PJ
authors.lastname: George
authors.affiliation: ICER Department, National Institutes of Health-NIRT-International Center for Excellence in Research, Chennai, India.
authors.forename: Rajamanickam
authors.initials: R
authors.lastname: Anuradha
authors.affiliation: ICER Department, National Institutes of Health-NIRT-International Center for Excellence in Research, Chennai, India.
authors.forename: Nathella Pavan
authors.initials: NP
authors.lastname: Kumar
authors.affiliation: Department of Thoracic Medicine Government Stanley Medical Hospital, Chennai, India.
authors.forename: Rathinam
authors.initials: R
authors.lastname: Sridhar
authors.affiliation: Department of Clinical Research, National Institute for Research in Tuberculosis, Chennai, India.
authors.forename: Vaithilingam V
authors.initials: VV
authors.lastname: Banurekha
authors.affiliation: Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Nutman
authors.affiliation: ICER Department, National Institutes of Health-NIRT-International Center for Excellence in Research, Chennai, India; Laboratory of Parasitic Diseases, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland, United States of America.
authors.forename: Subash
authors.initials: S
authors.lastname: Babu
mesh_terms: D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology*; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology*; D016207:Cytokines / Q000378:metabolism; D006373:Helminthiasis / Q000276:immunology*; D006376:Helminths / Q000276:immunology*; D006801:Humans; D007371:Interferon-gamma / Q000378:metabolism; D016753:Interleukin-10 / Q000276:immunology*; D008213:Lymphocyte Activation / Q000276:immunology; D009169:Mycobacterium tuberculosis / Q000276:immunology*; D018417:Th1 Cells / Q000276:immunology; D058504:Th17 Cells / Q000276:immunology; D014397:Tuberculosis, Pulmonary / Q000276:immunology*
chemical_list: D016207:Cytokines; D016753:Interleukin-10; D007371:Interferon-gamma