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Updated: May 2, 2026
Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1β in Human Monocyte-derived Dendritic Cells
Published on: May 22, 2014
The inflammasome recognizes cytosolic microbial and host DNA and triggers an innate immune response
Daniel A Muruve1, Virginie Pétrilli, Anne K Zaiss
1Department of Medicine, University of Calgary, Alberta T2N 4N1, Canada.
Abstract:
The innate immune system recognizes nucleic acids during infection and tissue damage. Whereas viral RNA is detected by endosomal toll-like receptors (TLR3, TLR7, TLR8) and cytoplasmic RIG-I and MDA5, endosomal TLR9 and cytoplasmic DAI bind DNA, resulting in the activation of nuclear factor-kappaB and interferon regulatory factor transcription factors. However, viruses also trigger pro-inflammatory responses, which remain poorly defined. Here we show that internalized adenoviral DNA induces maturation of pro-interleukin-1beta in macrophages, which is dependent on NALP3 and ASC, components of the innate cytosolic molecular complex termed the inflammasome. Correspondingly, NALP3- and ASC-deficient mice display reduced innate inflammatory responses to adenovirus particles. Inflammasome activation also occurs as a result of transfected cytosolic bacterial, viral and mammalian (host) DNA, but in this case sensing is dependent on ASC but not NALP3. The DNA-sensing pro-inflammatory pathway functions independently of TLRs and interferon regulatory factors. Thus, in addition to viral and bacterial components or danger signals in general, inflammasomes sense potentially dangerous cytoplasmic DNA, strengthening their central role in innate immunity.
Insights
The inflammasome, an innate immune complex, detects cytoplasmic DNA from viruses and bacteria. This sensing triggers pro-inflammatory responses, independent of Toll-like receptors, highlighting inflammasomes
Area of Science:
- Immunology
- Molecular Biology
- Infectious Disease
Background:
- The innate immune system detects pathogen-associated molecular patterns (PAMPs) like nucleic acids.
- Viral RNA and DNA are recognized by Toll-like receptors (TLRs) and cytoplasmic sensors.
- Pro-inflammatory responses to viruses, beyond TLR signaling, are not fully understood.
Purpose of the Study:
- To investigate the role of inflammasomes in sensing internalized adenoviral DNA.
- To elucidate the mechanisms of DNA-induced pro-inflammatory cytokine production.
Main Methods:
- Macrophage stimulation with internalized adenoviral DNA.
- Assessment of pro-interleukin-1beta maturation.
- Studies using NALP3- and ASC-deficient mice and cells.
- Analysis of transfected bacterial, viral, and host DNA.
Main Results:
- Internalized adenoviral DNA induces pro-interleukin-1beta maturation in macrophages via NALP3 and ASC.
- NALP3- and ASC-deficient mice show diminished innate inflammatory responses to adenoviruses.
- Cytosolic DNA sensing by inflammasomes is ASC-dependent but NALP3-independent for transfected DNA.
- This DNA-sensing pathway operates independently of TLRs and interferon regulatory factors.
Conclusions:
- Inflammasomes sense potentially dangerous cytoplasmic DNA, including viral and host DNA.
- This pathway contributes significantly to innate immune responses against viral infections.
- Inflammasomes play a crucial role in recognizing diverse danger signals beyond PAMPs.
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