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Updated: Jul 3, 2026
Detection of Inflammasome Activation and Pyroptotic Cell Death in Murine Bone Marrow-derived Macrophages
Published on: May 21, 2018
Monosodium urate crystals induce lytic macrophage death partially dependent on both pyroptosis and necroptosis
Zhijun Geng1, Di Wu1, Yajing Hou1
1State Key Laboratory of Pharmaceutical Biotechnology, MOE Key Laboratory of Model Animals for Disease Study, Jiangsu Key Laboratory of Molecular Medicine, Model Animal Research Center, National Resource Center for Mutant Mice of China, Nanjing Drum Tower Hospital, School of Medicine, Nanjing University, Nanjing, 210061, China.
Objectives:
Macrophage lytic death induced by monosodium urate (MSU) crystals is critical for gout initiation, but its mechanisms remain unclear. MSU activates the NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome and canonical pyroptosis; this study aimed to define the cell death pathways mediating MSU crystal-induced macrophage death.
Method:
We assessed canonical inflammasome activation (apoptosis-associated speck-like protein containing a CARD (ASC) speck, caspase-1, gasdermin D (GSDMD), interleukin-1β (IL-1β)) in macrophages. Using genetically deficient macrophages (GSDMD⁻/⁻, NLRP3⁻/⁻, and caspase-1⁻/⁻) and pharmacological inhibitors, we evaluated lytic death and in vivo inflammation. We also checked caspase-3/gasdermin E (GSDME) pyroptosis, necroptosis, ferroptosis, and ROS.
Results:
MSU crystals strongly activated canonical inflammasome signaling, as evidenced by ASC speck formation, caspase-1 activation, GSDMD cleavage, and IL-1β secretion. However, genetic ablation of GSDMD, NLRP3, or caspase-1 did not prevent MSU crystal-induced macrophage lytic death. Similarly, deficiency of GSDMD or NLRP3 did not alleviate inflammation in mouse models of gout. MSU crystals did not trigger caspase-3/GSDME-dependent pyroptosis. While necroptosis contributed to cell death when canonical pyroptosis was blocked, inhibiting necroptosis alone was insufficient to abolish MSU crystal-induced lysis. Combined inhibition of caspases and necroptosis moderately, but significantly, reduced lytic death, whereas additional blockade of ferroptosis or reactive oxygen species (ROS) did not further enhance this protective effect.
Conclusions:
MSU crystal-induced macrophage lytic death represent a complex cell death program that is not exclusively dependent on canonical pyroptosis or necroptosis. These findings uncover a previously unrecognized mechanism of MSU-mediated cytotoxicity and offer novel insights into the molecular pathogenesis of gout. Key Points • Monosodium urate (MSU) crystals trigger macrophage lytic cell death via synergistic canonical pyroptosis and necroptosis, instead of a single cell death pathway. GSDME-dependent pyroptosis, ferroptosis, and ROS are not pivotal drivers of this process. • Combined inhibition of canonical pyroptosis and necroptosis partially reduces MSU crystal-induced macrophage death.
Insights
Monosodium urate (MSU) crystals induce macrophage lytic death through a complex program involving both canonical pyroptosis and necroptosis, not solely one pathway. This finding offers new insights into gout pathogenesis.
Area of Science:
- Immunology
- Cell Biology
- Pathogenesis of Gout
Background:
- Macrophage lytic death is crucial for gout initiation.
- Monosodium urate (MSU) crystals activate the NLRP3 inflammasome and canonical pyroptosis.
- The precise cell death mechanisms mediating MSU crystal-induced macrophage death are not fully understood.
Purpose of the Study:
- To define the specific cell death pathways involved in MSU crystal-induced macrophage death.
- To investigate the roles of canonical pyroptosis and necroptosis in this process.
- To explore the contribution of other cell death modalities like GSDME-dependent pyroptosis, ferroptosis, and ROS.
Main Methods:
- Assessed canonical inflammasome activation (ASC speck, caspase-1, GSDMD, IL-1β) in macrophages.
- Utilized genetically deficient macrophages (GSDMD⁻/⁻, NLRP3⁻/⁻, caspase-1⁻/⁻) and pharmacological inhibitors.
- Evaluated lytic death, in vivo inflammation, and other cell death pathways (caspase-3/GSDME pyroptosis, necroptosis, ferroptosis, ROS).
Main Results:
- MSU crystals robustly activated canonical inflammasome signaling.
- Genetic ablation of GSDMD, NLRP3, or caspase-1 did not prevent MSU crystal-induced macrophage lytic death.
- Necroptosis contributed to cell death when canonical pyroptosis was blocked, and combined inhibition of caspases and necroptosis partially reduced lytic death, but ferroptosis or ROS inhibition did not further enhance protection.
Conclusions:
- MSU crystal-induced macrophage lytic death is a complex program, not solely dependent on canonical pyroptosis or necroptosis.
- This process involves synergistic canonical pyroptosis and necroptosis.
- Findings reveal a novel mechanism of MSU-mediated cytotoxicity, advancing understanding of gout pathogenesis.
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