Interleukin-17 limits hypoxia-inducible factor 1α and development of hypoxic granulomas during tuberculosis

JCI Insight. 2017 Oct 5;2(19):e92973. doi: 10.1172/jci.insight.92973.

Abstract

Mycobacterium tuberculosis (Mtb) is a global health threat, compounded by the emergence of drug-resistant strains. A hallmark of pulmonary tuberculosis (TB) is the formation of hypoxic necrotic granulomas, which upon disintegration, release infectious Mtb. Furthermore, hypoxic necrotic granulomas are associated with increased disease severity and provide a niche for drug-resistant Mtb. However, the host immune responses that promote the development of hypoxic TB granulomas are not well described. Using a necrotic Mtb mouse model, we show that loss of Mtb virulence factors, such as phenolic glycolipids, decreases the production of the proinflammatory cytokine IL-17 (also referred to as IL-17A). IL-17 production negatively regulates the development of hypoxic TB granulomas by limiting the expression of the transcription factor hypoxia-inducible factor 1α (HIF1α). In human TB patients, HIF1α mRNA expression is increased. Through genotyping and association analyses in human samples, we identified a link between the single nucleotide polymorphism rs2275913 in the IL-17 promoter (-197G/G), which is associated with decreased IL-17 production upon stimulation with Mtb cell wall. Together, our data highlight a potentially novel role for IL-17 in limiting the development of hypoxic necrotic granulomas and reducing disease severity in TB.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Animals
  • Cell Hypoxia / immunology
  • Female
  • Gene Expression Regulation / immunology
  • Granuloma / immunology*
  • Granuloma / microbiology
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / biosynthesis
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • Hypoxia-Inducible Factor 1, alpha Subunit / immunology*
  • Inflammation Mediators / metabolism
  • Interleukin-17 / biosynthesis
  • Interleukin-17 / immunology*
  • Male
  • Mice, Inbred Strains
  • Middle Aged
  • RNA, Messenger / genetics
  • Tuberculosis, Pulmonary / complications
  • Tuberculosis, Pulmonary / immunology*
  • Young Adult

Substances

  • Hypoxia-Inducible Factor 1, alpha Subunit
  • IL17A protein, human
  • Il17a protein, mouse
  • Inflammation Mediators
  • Interleukin-17
  • RNA, Messenger