NOD2-RIP2 signaling alleviates microglial ROS damage and pyroptosis via ULK1-mediated autophagy during Streptococcus pneumonia infection

Neurosci Lett. 2022 Jul 13:783:136743. doi: 10.1016/j.neulet.2022.136743. Epub 2022 Jun 15.

Abstract

Meningitis occurs when S. pneumonia invade the blood-brain barrier, provoking inflammatory host response and neurological injury. Nucleotide-binding oligomerization domain 2 (NOD2) has been identified to promote microglial activation and autophagy during pneumococcal meningitis, but the mechanism remains unclear. In the present study, we investigated the passway of NOD2-mediated autophagy activation and the role of autophagy in inflammatory damage of murine microglia and mouse meningitis model. We demonstrated that autophagy was activated during S. pneumonia infection, and NOD2-RIP2 signaling was involved in the process. Treatment of microglia with GSK583, the RIP2 kinase inhibitor resulted in reduced autophagy-related protein and p-ULK1, indicating that RIP2 regulated autophagy in a kinase-dependent manner by phosphorylating ULK1. In addition, microglia with ULK1 knockdown exhibited enhanced production of ROS, leading to IL-1β and IL-18 release and cellular pyroptosis. Similar to the in vitro results, NOD2-RIP2 signaling induced autophagy in the brain in a mouse meningitis model. Moreover, ULK1 or RIP2 silencing significantly increased pyroptosis of brain and induced more inflammatory damage of pneumococcal meningitis mice. Taken together, our study demonstrate that NOD2-RIP2 signaling is involved in the activation of autophagy by promoting ULK1 phosphorylation, which alleviates microglial ROS damage and pyroptosis during S. pneumonia infection.

Keywords: Autophagy; Microglia; NOD2; Pyroptosis; RIP2; ULK1.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Autophagy
  • Meningitis, Pneumococcal* / metabolism
  • Mice
  • Microglia / metabolism
  • Nod2 Signaling Adaptor Protein / metabolism
  • Pneumonia* / metabolism
  • Pyroptosis
  • Reactive Oxygen Species / metabolism
  • Receptor-Interacting Protein Serine-Threonine Kinase 2 / metabolism
  • Streptococcus / metabolism

Substances

  • Nod2 Signaling Adaptor Protein
  • Reactive Oxygen Species
  • Receptor-Interacting Protein Serine-Threonine Kinase 2