Whole blood assay as a model for in vitro evaluation of inflammasome activation and subsequent caspase-mediated interleukin-1 beta release

• Published in: PloS one Vol. 14; no. 4; p. e0214999
• Main Authors: Tran, Thi Anh Thu, Grievink, Hendrika W, Lipinska, Katarzyna, Kluft, Cornelis, Burggraaf, Jacobus, Moerland, Matthijs, Tasev, Dimitar, Malone, Karen E
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.04.2019; Public Library of Science (PLoS)
• Subjects: Assaying; ATP; Biochemical assays; Biology and Life Sciences; Biomarkers; Blood; Blood analyzers; Blood cells; Blood tests; Caspase inhibitors; Caspase-1; Caspases; Caspases - immunology; Cell activation; Clinical trials; Cytokines; Flow cytometry; Fluorescence; Gene expression; Health aspects; Humans; IL-1β; Immunology; Inflammasomes; Inflammasomes - immunology; Inflammation; Inflammation - chemically induced; Inflammation - immunology; Inflammation - pathology; Interleukin 1; Interleukin 18; Interleukin-18 - immunology; Interleukin-1beta - immunology; Interleukins; Lipopolysaccharides; Lipopolysaccharides - toxicity; Medical research; Medicine and Health Sciences; Mitochondrial DNA; Mitogens; Models, Immunological; Monocytes; Monocytes - immunology; Monocytes - pathology; Neutrophils; Priming; Product development; Research and Analysis Methods; Signal Transduction - drug effects; Signal Transduction - immunology; Stimulation; United States > US; Netherlands
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0214999

Processing of pro-interleukin (IL)-1β and IL-18 is regulated by multiprotein complexes, known as inflammasomes. Inflammasome activation results in generation of bioactive IL-1β and IL-18, which can exert potent pro-inflammatory effects. Our aim was to develop a whole blood-based assay to study the inflammasome in vitro and that also can be used as an assay in clinical studies. We show whole blood is a suitable milieu to study inflammasome activation in primary human monocytes. We demonstrated that unprocessed human blood cells can be stimulated to activate the inflammasome by the addition of adenosine 5'-triphosphate (ATP) within a narrow timeframe following lipopolysaccharide (LPS) priming. Stimulation with LPS resulted in IL-1β release; however, addition of ATP is necessary for "full-blown" inflammasome stimulation resulting in high IL-1β and IL-18 release. Intracellular cytokine staining demonstrated monocytes are the major producers of IL-1β in human whole blood cultures, and this was associated with activation of caspase-1/4/5, as detected by a fluorescently labelled caspase-1/4/5 probe. By applying caspase inhibitors, we show that both the canonical inflammasome pathway (via caspase-1) as well as the non-canonical inflammasome pathway (via caspases-4 and 5) can be studied using this whole blood-based model.