Mycobacteria induce TPL-2 mediated IL-10 in IL-4-generated alternatively activated macrophages

PLoS One. 2017 Jun 28;12(6):e0179701. doi: 10.1371/journal.pone.0179701. eCollection 2017.

Abstract

IL-4 drives expansion of Th2 cells that cause generation of alternatively activated macrophages (AAMs). Filarial infections are established early in life, induce increased IL-4 production are co-endemic with tuberculosis (TB). We sought to understand, therefore, how mycobacteria are handled in the context of IL-4-induced AAM. Comparing IL-4 generated in vitro monocyte derived human AAMs to LPS and IFN-γ generated classically macrophages (CAMs), both infected with mycobacteria (BCG), we demonstrated increased early BCG uptake and increased IL-10 production in AAMs compared to CAMs. We further demonstrated that increased IL-10 production is mediated by upregulation of tumor progression locus 2 (TPL-2), an upstream activator of extracellular signal related kinases (ERKs) in AAMs but not in CAMs, both at the transcript as well as the protein level. Pharmacologic inhibition of TPL-2 significantly diminished IL-10 production only in BCG-infected AAMs. Finally, we validated our findings in an in vivo C57Bl/6 model of filarial infection, where an exaggerated Th2 induced lung-specific alternative activation led to TPL-2 and IL-10 upregulation on subsequent TB infection. These data show that in response to mycobacterial infection, IL-4 generated AAMs in chronic filarial infections have impaired immune responses to TB infection by increasing IL-10 production in a TPL-2 mediated manner.

MeSH terms

  • Animals
  • Cytokines / metabolism
  • Humans
  • Interleukin-10 / metabolism*
  • Interleukin-4 / metabolism*
  • MAP Kinase Kinase Kinases / metabolism*
  • Macrophage Activation / physiology*
  • Macrophages / metabolism*
  • Mice
  • Monocytes / metabolism*
  • Mycobacterium*
  • Proto-Oncogene Proteins / metabolism*
  • Signal Transduction

Substances

  • Cytokines
  • Proto-Oncogene Proteins
  • Interleukin-10
  • Interleukin-4
  • MAP Kinase Kinase Kinases
  • MAP3K8 protein, human

Grants and funding

This research was supported [in part] by the Division of Intramural Research Program of the National Institute of Allergy and Infectious Diseases, National Institutes of Health. The funder had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.