Inflammasomes-dependent regulation of IL-1β secretion induced by the virulent Mycobacterium bovis Beijing strain in THP-1 macrophages

Antonie Van Leeuwenhoek. 2015 Jul;108(1):163-71. doi: 10.1007/s10482-015-0475-6. Epub 2015 May 16.

Abstract

Mycobacterium bovis is the causative agent of tuberculosis in cattle. Infection of macrophages with M. bovis leads to the activation of the "nucleotide binding and oligomerization, leucine-rich repeat and pyrin domains-containing protein 3" (NLRP3) and "absent in melanoma 2" (AIM2) inflammasomes, which in turn triggers release of the proinflammatory cytokine interleukin-1β (IL-1β) that contributes to bacterial clearance and plays a crucial role in the host defense. However, NLRP3 and AIM2 inflammasome activation is influenced by several factors and how IL-1β secretion by M. bovis-infected macrophages is regulated via the inflammasome pathway remains unclear. Here we found that IL-1β secretion and pro-IL-1β protein accumulation were inhibited in THP-1 macrophages upon exposure to the virulent M. bovis Beijing strain in the presence of high K(+) concentrations, cycloheximide (a protein synthesis inhibitor) and PR-619 (a deubiquitinating enzyme inhibitor). Scavenging reactive oxygen species (ROS) induced by N-acetylcysteine reduced IL-1β release independent of the mitochondrial permeability transition. Collectively, our results suggest that IL-1β secretion by M. bovis-infected THP-1 macrophages is reduced by high extracellular K(+) concentration, inhibition of new protein synthesis, deubiquitination, and ROS generation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cattle
  • Cell Line
  • Cycloheximide / metabolism
  • Humans
  • Inflammasomes / metabolism*
  • Interleukin-1beta / metabolism*
  • Macrophages / immunology*
  • Macrophages / microbiology*
  • Mycobacterium bovis / immunology*
  • Potassium / metabolism
  • Reactive Oxygen Species / metabolism

Substances

  • Inflammasomes
  • Interleukin-1beta
  • Reactive Oxygen Species
  • Cycloheximide
  • Potassium