Circulating HLA-DR+CD4+ effector memory T cells resistant to CCR5 and PD-L1 mediated suppression compromise regulatory T cell function in tuberculosis

PLoS Pathog. 2018 Sep 19;14(9):e1007289. doi: 10.1371/journal.ppat.1007289. eCollection 2018 Sep.

Abstract

Chronic T cell activation is a hallmark of pulmonary tuberculosis (PTB). The mechanisms underpinning this important phenomenon are however, poorly elucidated, though known to rely on control of T effector cells (Teff) by regulatory T cells (Treg). Our studies show that circulating natural Treg cells in adults with PTB preserve their suppressive potential but Teff cells from such subjects are resistant to Treg-mediated suppression. We found this to be due to expansion of an activated Teff subset identified by Human Leukocyte Antigen (HLA)-DR expression. Sensitivity to suppression was restored to control levels by depletion of this subset. Comparative transcriptome analysis of Teff cells that contain HLA-DR+ cells versus the fraction depleted of this population identified putative resistance mechanisms linked to IFNG, IL17A, IL22, PD-L1 and β-chemokines CCL3L3, CCL4 expression. Antibody blocking experiments confirmed HLA-DR+ Teff cells, but not the fraction depleted of HLA-DR+ effectors, to be resistant to Treg suppression mediated via CCR5 and PD-L1 associated pathways. In the presence of HLA-DR+ Teff cells, activation of NFκB downstream of CCR5 and PD-L1 was perturbed. In addition, HLA-DR+ Teff cells expressed significantly higher levels of Th1/Th17 cytokines that may regulate Treg function through a reciprocal counter-balancing relationship. Taken together, our study provides novel insight on how activated HLA-DR+CD4+ T cells may contribute to disease associated inflammation by compromising Treg-mediated suppression in PTB.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • B7-H1 Antigen / antagonists & inhibitors
  • B7-H1 Antigen / metabolism*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD4-Positive T-Lymphocytes / microbiology
  • Cytokines / genetics
  • Cytokines / metabolism
  • Female
  • HLA-DR Antigens / metabolism
  • Host-Pathogen Interactions / immunology
  • Humans
  • Immune Tolerance
  • Immunologic Memory
  • Latent Tuberculosis / immunology
  • Latent Tuberculosis / microbiology
  • Lymphocyte Activation
  • Male
  • Middle Aged
  • Mycobacterium tuberculosis / immunology
  • Mycobacterium tuberculosis / pathogenicity
  • Receptors, CCR5 / metabolism*
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / microbiology
  • Tuberculosis, Pulmonary / genetics
  • Tuberculosis, Pulmonary / immunology*
  • Tuberculosis, Pulmonary / microbiology
  • Up-Regulation

Substances

  • B7-H1 Antigen
  • CCR5 protein, human
  • CD274 protein, human
  • Cytokines
  • HLA-DR Antigens
  • Receptors, CCR5

Grants and funding

This study was supported by a Centre of Excellence grant to AV from the Department of Biotechnology, Govt. of India (No BT/PR10394/MED/29/1128/2016). We acknowledge additional funding for sample collection and analysis by EC HORIZON2020 TBVAC2020 and EC FP7 EURIPRED (FP7-INFRA-2012 Grant Agreement No. 312661) to AV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.