Molecular mechanisms underlying NLRP3 inflammasome activation and IL-1β production in air pollution fine particulate matter (PM2.5)-primed macrophages

Abstract: Exposure to air pollution fine particulate matter (PM2.5) aggravates respiratory and cardiovascular diseases. It has been proposed that PM2.5 uptake by alveolar macrophages promotes local inflammation that ignites a systemic response, but precise underlying mechanisms remain unclear. Here, we demonstrate that PM2.5 phagocytosis leads to NLRP3 inflammasome activation and subsequent release of the pro-inflammatory master cytokine IL-1β. Inflammasome priming and assembly was time- and dose-dependent in inflammasome-reporter THP-1-ASC-GFP cells, and consistent across PM2.5 samples of variable chemical composition. While inflammasome activation was promoted by different PM2.5 surrogates, significant IL-1β release could only be observed after stimulation with transition-metal rich Residual Oil Fly Ash (ROFA) particles. This effect was confirmed in primary human monocyte-derived macrophages and murine bone marrow-derived macrophages (BMDMs), and by confocal imaging of inflammasome-reporter ASC-Citrine BMDMs. IL-1β release by ROFA was dependent on the NLRP3 inflammasome, as indicated by lack of IL-1β production in ROFA-exposed NLRP3-deficient (Nlrp3−/−) BMDMs, and by specific NLRP3 inhibition with the pharmacological compound MCC950. In addition, while ROFA promoted the upregulation of pro-inflammatory gene expression and cytokines release, MCC950 reduced TNF-α, IL-6, and CCL2 production. Furthermore, inhibition of TNF-α with a neutralizing antibody decreased IL-1β release in ROFA-exposed BMDMs. Using electron tomography, ROFA particles were observed inside intracellular vesicles and mitochondria, which showed signs of ultrastructural damage. Mechanistically, we identified lysosomal rupture, K+ efflux, and impaired mitochondrial function as important prerequisites for ROFA-mediated IL-1β release. Interestingly, specific inhibition of superoxide anion production (O2•-) from mitochondrial respiratory Complex I, but not III, blunted IL-1β release in ROFA-exposed BMDMs. Our findings unravel the mechanism by which PM2.5 promotes IL-1β release in macrophages and provide a novel link between innate immune response and exposure to air pollution PM2.5

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Environmental pollution. - 341 (2024) , 122997, ISSN: 1873-6424

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2023
• Creator: Caceres, Lourdes ; Abogunloko, Tijani ; Malchow, Sara ; Ehret, Fabienne ; Merz, Julian ; Li, Xiaowei ; Sol Mitre, Lucia ; Magnani, Natalia ; Tasat, Deborah ; Mwinyella, Timothy ; Füner, Lisa ; Suchanek, Dymphie ; Fischer, Larissa ; Gorka, Oliver ; Gißler, Mark Colin ; Hilgendorf, Ingo ; Stachon, Peter ; Rog-Zielinska, Eva Alicja ; Groß, Olaf ; Westermann, Dirk ; Evelson, Pablo ; Wolf, Dennis ; Marchini, Timoteo

Further information

• DOI: 10.1016/j.envpol.2023.122997
• URN: urn:nbn:de:bsz:25-freidok-2416651
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 15.08.2025, 7:27 AM CEST