Restimulation-induced T-cell death through NTB-A/SAP signaling pathway is impaired in tuberculosis patients with depressed immune responses

Immunol Cell Biol. 2017 Sep;95(8):716-728. doi: 10.1038/icb.2017.42. Epub 2017 May 26.

Abstract

Production of IFN-γ contributes to host defense against Mycobacterium tuberculosis (Mtb) infection. We previously demonstrated that Signaling lymphocytic activation molecule-associated protein (SAP) expression on cells from tuberculosis (TB) patients was inversely correlated with IFN-γ production. Here we first investigated the role of NK, T- and B-cell antigen (NTB-A)/SAP pathway in the regulation of Th1 response against Mtb. Upon antigen stimulation, NTB-A phosphorylation rapidly increases and afterwards modulates IFN-γ and IL-17 secretion. To sustain a healthy immune system, controlled expansion and contraction of lymphocytes, both during and after an adaptive immune response, is essential. Besides, restimulation-induced cell death (RICD) results in an essential homeostatic mechanism for precluding excess T-cell accumulation and associated immunopathology during the course of certain infections. Accordingly, we found that the NTB-A/SAP pathway was required for RICD during active tuberculosis. In low responder (LR) TB patients, impaired RICD was associated with diminished FASL levels, IL-2 production and CD25high expression after cell-restimulation. Interestingly, we next observed that SAP mediated the recruitment of the Src-related kinase FYNT, only in T cells from LR TB patients that were resistant to RICD. Together, we showed that the NTB-A/SAP pathway regulates T-cell activation and RICD during human TB. Moreover, the NTB-A/SAP/FYNT axis promotes polarization to an unfavorable Th2-phenotype.

MeSH terms

  • Adult
  • Cell Death
  • Cell Differentiation
  • Cells, Cultured
  • Female
  • Homeostasis
  • Humans
  • Immunity
  • Immunosuppression Therapy
  • Interferon-gamma / metabolism
  • Interleukin-17 / metabolism
  • Lymphocyte Activation
  • Male
  • Mycobacterium tuberculosis / immunology*
  • Neoplasm Proteins / metabolism
  • Protein-Tyrosine Kinases / metabolism
  • Signal Transduction
  • Signaling Lymphocytic Activation Molecule Family / metabolism*
  • Th2 Cells / immunology*
  • Tuberculosis / immunology*

Substances

  • Interleukin-17
  • Neoplasm Proteins
  • SLAMF6 protein, human
  • Signaling Lymphocytic Activation Molecule Family
  • Interferon-gamma
  • Protein-Tyrosine Kinases
  • FRK protein, human