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

A Ahmed, V Adiga, S Nayak, JAJ Uday Kumar… - PLoS …, 2018 - journals.plos.org
PLoS pathogens, 2018journals.plos.org
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 …
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.
PLOS