T cells expressing multiple co-inhibitory molecules in acute malaria are not exhausted but exert a suppressive function in mice

Eur J Immunol. 2022 Feb;52(2):312-327. doi: 10.1002/eji.202149424. Epub 2021 Nov 25.

Abstract

Overwhelming activation of T cells in acute malaria is associated with severe outcomes. Thus, counter-regulation by anti-inflammatory mechanisms is indispensable for an optimal resolution of disease. Using Plasmodium berghei ANKA (PbA) infection of C57BL/6 mice, we performed a comprehensive analysis of co-inhibitory molecules expressed on CD4+ and CD8+ T cells using an unbiased cluster analysis approach. We identified similar T cell clusters co-expressing several co-inhibitory molecules like programmed cell death protein 1 (PD-1) and lymphocyte activation gene 3 (LAG-3) in the CD4+ and the CD8+ T cell compartment. Interestingly, despite expressing co-inhibitory molecules, which are associated with T cell exhaustion in chronic settings, these T cells were more functional compared to activated T cells that were negative for co-inhibitory molecules. However, T cells expressing high levels of PD-1 and LAG-3 also conferred suppressive capacity and thus resembled type I regulatory T cells. To our knowledge, this is the first description of malaria-induced CD8+ T cells with suppressive capacity. Importantly, we found an induction of T cells with a similar co-inhibitory rich phenotype in Plasmodium falciparum-infected patients. In conclusion, we demonstrate that malaria-induced T cells expressing co-inhibitory molecules are not exhausted, but acquire additional suppressive capacity, which might represent an immune regulatory pathway to prevent further activation of T cells during acute malaria.

Keywords: T cells; immune regulation; immunopathology; inhibitory receptors; malaria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Animals
  • Antigens, CD / immunology*
  • CD4-Positive T-Lymphocytes / immunology*
  • CD8-Positive T-Lymphocytes / immunology*
  • Female
  • Gene Expression Regulation / immunology*
  • Humans
  • Immune Tolerance*
  • Malaria, Falciparum / immunology*
  • Male
  • Mice
  • Mice, Inbred BALB C
  • Middle Aged
  • Plasmodium berghei / immunology*
  • Plasmodium falciparum / immunology*
  • Programmed Cell Death 1 Receptor / immunology*

Substances

  • Antigens, CD
  • CD223 antigen
  • PDCD1 protein, human
  • Pdcd1 protein, mouse
  • Programmed Cell Death 1 Receptor