Inflammasome activation and IL-1β/IL-18 processing are influenced by distinct pathways in microglia

Richa Hanamsagar, Victor Torres, Tammy L Kielian

Research output: Contribution to journalArticle

80 Citations (Scopus)

Abstract

Microglia are important innate immune effectors against invading CNS pathogens, such as Staphylococcus aureus (S. aureus), a common etiological agent of brain abscesses typified by widespread inflammation and necrosis. The NLRP3 inflammasome is a protein complex involved in IL-1β and IL-18 processing following exposure to both pathogen- and danger-associated molecular patterns. Although previous studies from our laboratory have established that IL-1β is a major cytokine product of S. aureus-activated microglia and is pivotal for eliciting protective anti-bacterial immunity during brain abscess development, the molecular machinery responsible for cytokine release remains to be determined. Therefore, the functional role of the NLRP3 inflammasome and its adaptor protein apoptosis-associated speck-like protein (ASC) in eliciting IL-1β and IL-18 release was examined in primary microglia. Interestingly, we found that IL-1β, but not IL-18 production, was significantly attenuated in both NLRP3 and ASC knockout microglia following exposure to live S. aureus. NLRP3 inflammasome activation was partially dependent on autocrine/paracrine ATP release and α- and γ-hemolysins produced by live bacteria. A cathepsin B inhibitor attenuated IL-β release from NLRP3 and ASC knockout microglia, demonstrating the existence of alternative inflammasome-independent mechanisms for IL-1β processing. In contrast, microglial IL-18 secretion occurred independently of cathepsin B and inflammasome action. Collectively, these results demonstrate that microglial IL-1β processing is regulated by multiple pathways and diverges from mechanisms utilized for IL-18 cleavage. Understanding the molecular events that regulate IL-1β production is important for modulating this potent proinflammatory cytokine during CNS disease.

Original languageEnglish (US)
Pages (from-to)736-748
Number of pages13
JournalJournal of Neurochemistry
Volume119
Issue number4
DOIs
StatePublished - Nov 1 2011

Fingerprint

Inflammasomes
Interleukin-18
Microglia
Interleukin-1
Chemical activation
Processing
Staphylococcus aureus
Cathepsin B
Brain Abscess
Pathogens
Cytokines
Proteins
Brain
Hemolysin Proteins
Central Nervous System Diseases
Machinery
Immunity
Bacteria
Necrosis
Adenosine Triphosphate

Keywords

  • IL-18
  • IL-1β
  • NLRP3
  • P2X R
  • inflammasome
  • microglia

ASJC Scopus subject areas

  • Biochemistry
  • Cellular and Molecular Neuroscience

Cite this

Inflammasome activation and IL-1β/IL-18 processing are influenced by distinct pathways in microglia. / Hanamsagar, Richa; Torres, Victor; Kielian, Tammy L.

In: Journal of Neurochemistry, Vol. 119, No. 4, 01.11.2011, p. 736-748.

Research output: Contribution to journalArticle

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