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Updated: Jan 1, 2026
Activation and Measurement of NLRP3 Inflammasome Activity Using IL-1β in Human Monocyte-derived Dendritic Cells
Published on: May 22, 2014
Soluble Aβ oligomers and protofibrils induce NLRP3 inflammasome activation in microglia
Asta Lučiūnaitė1,2,3, Róisín M McManus2,3, Marija Jankunec4
1Institute of Biotechnology, Life Sciences Center, Vilnius University, Vilnius, Lithuania.
Abstract:
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder causing memory loss, language problems and behavioural disturbances. AD is associated with the accumulation of fibrillar amyloid-β (Aβ) and the formation of neurofibrillary tau tangles. Fibrillar Aβ itself represents a danger-associated molecular pattern, which is recognized by specific microglial receptors. One of the key players is formation of the NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome, whose activation has been demonstrated in AD patient brains and transgenic animal models of AD. Here, we investigated whether Aβ oligomers or protofibrils that represent lower molecular aggregates prior to Aβ deposition are able to activate the NLRP3 inflammasome and subsequent interleukin-1 beta (IL-1β) release by microglia. In our study, we used Aβ preparations of different sizes: small oligomers and protofibrils of which the structure was confirmed by atomic force microscopy. Primary microglial cells from C57BL/6 mice were treated with the respective Aβ preparations and NLRP3 inflammasome activation, represented by caspase-1 cleavage, IL-1β production, and apoptosis-associated speck-like protein containing a CARD speck formation was analysed. Both protofibrils and low molecular weight Aβ aggregates induced a significant increase in IL-1β release. Inflammasome activation was confirmed by apoptosis-associated speck-like protein containing a CARD speck formation and detection of active caspase-1. The NLRP3 inflammasome inhibitor MCC950 completely inhibited the Aβ-induced immune response. Our results show that the NLRP3 inflammasome is activated not only by fibrillar Aβ aggregates as reported before, but also by lower molecular weight Aβ oligomers and protofibrils, highlighting the possibility that microglial activation by these Aβ species may initiate innate immune responses in the central nervous system prior to the onset of Aβ deposition. Cover Image for this issue: https://doi.org/10.1111/jnc.14773.
Insights
Alzheimer's disease research reveals that amyloid-beta (Aβ) oligomers and protofibrils activate the NLRP3 inflammasome in microglia. This early microglial activation by Aβ species may initiate innate immune responses before plaque deposition.
Area of Science:
- Neuroscience
- Immunology
- Molecular Biology
Background:
- Alzheimer's disease (AD) is a neurodegenerative disorder linked to amyloid-beta (Aβ) accumulation and neurofibrillary tangles.
- Fibrillar Aβ activates microglial receptors, notably the NOD-, LRR- and pyrin domain-containing 3 (NLRP3) inflammasome, implicated in AD pathogenesis.
- Previous studies focused on fibrillar Aβ, leaving the role of smaller Aβ aggregates in inflammasome activation unclear.
Purpose of the Study:
- To investigate if amyloid-beta (Aβ) oligomers and protofibrils activate the NLRP3 inflammasome in microglia.
- To determine if these smaller Aβ aggregates trigger interleukin-1 beta (IL-1β) release.
- To understand the role of early Aβ species in initiating innate immune responses in the brain.
Main Methods:
- Primary microglial cells from C57BL/6 mice were treated with characterized Aβ oligomers and protofibrils.
- Analyzed NLRP3 inflammasome activation markers: caspase-1 cleavage, IL-1β production, and ASC speck formation.
- Utilized the NLRP3 inflammasome inhibitor MCC950 to assess its effect on Aβ-induced responses.
Main Results:
- Both Aβ protofibrils and low molecular weight Aβ aggregates significantly increased IL-1β release from microglia.
- Confirmed inflammasome activation through observed ASC speck formation and active caspase-1 detection.
- The NLRP3 inhibitor MCC950 completely blocked the Aβ-induced microglial immune response.
Conclusions:
- The NLRP3 inflammasome is activated by lower molecular weight Aβ oligomers and protofibrils, not just fibrillar forms.
- Microglial activation by these early Aβ species may initiate innate immune responses in the central nervous system.
- This finding suggests a potential mechanism for early neuroinflammation in Alzheimer's disease preceding significant Aβ deposition.
