Fatty acid oxidation of alternatively activated macrophages prevents foam cell formation, but Mycobacterium tuberculosis counteracts this process via HIF-1α activation

PLoS Pathog. 2020 Oct 1;16(10):e1008929. doi: 10.1371/journal.ppat.1008929. eCollection 2020 Oct.

Abstract

The ability of Mycobacterium tuberculosis (Mtb) to persist inside host cells relies on metabolic adaptation, like the accumulation of lipid bodies (LBs) in the so-called foamy macrophages (FM), which are favorable to Mtb. The activation state of macrophages is tightly associated to different metabolic pathways, such as lipid metabolism, but whether differentiation towards FM differs between the macrophage activation profiles remains unclear. Here, we aimed to elucidate whether distinct macrophage activation states exposed to a tuberculosis-associated microenvironment or directly infected with Mtb can form FM. We showed that the triggering of signal transducer and activator of transcription 6 (STAT6) in interleukin (IL)-4-activated human macrophages (M(IL-4)) prevents FM formation induced by pleural effusion from patients with tuberculosis. In these cells, LBs are disrupted by lipolysis, and the released fatty acids enter the β-oxidation (FAO) pathway fueling the generation of ATP in mitochondria. Accordingly, murine alveolar macrophages, which exhibit a predominant FAO metabolism, are less prone to become FM than bone marrow derived-macrophages. Interestingly, direct infection of M(IL-4) macrophages with Mtb results in the establishment of aerobic glycolytic pathway and FM formation, which could be prevented by FAO activation or inhibition of the hypoxia-inducible factor 1-alpha (HIF-1α)-induced glycolytic pathway. In conclusion, our results demonstrate that Mtb has a remarkable capacity to induce FM formation through the rewiring of metabolic pathways in human macrophages, including the STAT6-driven alternatively activated program. This study provides key insights into macrophage metabolism and pathogen subversion strategies.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Foam Cells / microbiology*
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism*
  • Lipid Droplets / metabolism
  • Lipid Metabolism*
  • Macrophage Activation / physiology
  • Macrophages / metabolism
  • Macrophages / microbiology*
  • Male
  • Mice, Inbred BALB C
  • Mycobacterium tuberculosis / pathogenicity*
  • Mycobacterium tuberculosis / physiology
  • Tuberculosis / microbiology

Substances

  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit

Grants and funding

This work was supported by the Argentinean National Agency of Promotion of Science and Technology (PICT-2015-0055 to MCS and PICT-2017-1317 to LB; https://www.argentina.gob.ar/ciencia/agencia/fondo-para-la-investigacion-cientifica-y-tecnologica-foncyt), the Argentinean National Council of Scientific and Technical Investigations (CONICET, PIP 112-2013-0100202 to MCS; https://convocatorias.conicet.gov.ar/proyectos-pip/), the Centre National de la Recherche Scientifique, and the Agence Nationale de Recherche sur le Sida et les Hépatites Virales (ANRS2014-049 to ON, ANRS2018-1 to CV and ANRS2020-01 to GLV and CV; http://www.agence-nationale-recherche.fr/). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.