Particulate matter of 2.5 μm or less in diameter disturbs the balance of TH17/regulatory T cells by targeting glutamate oxaloacetate transaminase 1 and hypoxia-inducible factor 1α in an asthma model

J Allergy Clin Immunol. 2020 Jan;145(1):402-414. doi: 10.1016/j.jaci.2019.10.008. Epub 2019 Oct 21.

Abstract

Background: Epidemiologic evidence suggests that exposure to particulate matter of 2.5 μm or less in diameter (PM2.5) aggravates asthma.

Objective: We sought to investigate the underlying mechanisms between PM2.5 exposure and asthma severity.

Methods: The relationship between PM2.5 exposure and asthma severity was investigated in an asthma model with CD4+ T cell-specific aryl hydrocarbon receptor (AhR)-null mice. Effects of PM2.5 and polycyclic aromatic hydrocarbons (PAHs) on differentiation of TH17/regulatory T (Treg) cells were investigated by using flow cytometry and quantitative RT-PCR. Mechanisms were investigated by using mRNA sequencing, chromatin immunoprecipitation, bisulfite sequencing, and glycolysis rates.

Results: PM2.5 impaired differentiation of Treg cells, promoted differentiation of TH17 cells, and aggravated asthma in an AhR-dependent manner. PM2.5 and one of its prominent PAHs, indeno[1,2,3-cd]pyrene (IP), promoted differentiation of TH17 cells by upregulating hypoxia-inducible factor 1α expression and enhancing glycolysis through AhRs. Exposure to PM2.5 and IP enhanced glutamate oxaloacetate transaminase 1 (Got1) expression through AhRs and accumulation of 2-hydroxyglutarate, which inhibited ten-eleven translocation methylcytosine dioxygenase 2 activity, resulting in hypermethylation in the forkhead box P3 locus and impaired differentiation of Treg cells. A GOT1 inhibitor, (aminooxy)acetic acid, ameliorated asthma by shifting differentiation of TH17 cells to Treg cells. Similar regulatory effects of exposure to PM2.5 or IP on TH17/Treg cell imbalance were noted in human T cells, and in a case-control design PAH exposure appeared to be a potential risk factor for asthma.

Conclusions: The AhR-hypoxia-inducible factor 1α and AhR-GOT1 molecular pathways mediate pulmonary responses on exposure to PM2.5 through their ability to disturb the balance of TH17/Treg cells.

Keywords: Asthma; DNA methylation; T-cell differentiation; aryl hydrocarbon receptors; glycolysis; particulate matter of 2.5 μm or less in diameter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aspartate Aminotransferase, Cytoplasmic / genetics
  • Aspartate Aminotransferase, Cytoplasmic / immunology*
  • Asthma / chemically induced
  • Asthma / genetics
  • Asthma / immunology*
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Disease Models, Animal
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / immunology*
  • Mice
  • Mice, Mutant Strains
  • Particle Size
  • Particulate Matter / toxicity*
  • Receptors, Aryl Hydrocarbon / genetics
  • Receptors, Aryl Hydrocarbon / immunology
  • T-Lymphocytes, Regulatory / immunology*
  • T-Lymphocytes, Regulatory / pathology
  • Th17 Cells / immunology*
  • Th17 Cells / pathology

Substances

  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Particulate Matter
  • Receptors, Aryl Hydrocarbon
  • Aspartate Aminotransferase, Cytoplasmic
  • Got1 protein, mouse