Spectrum and mechanisms of inflammasome activation by chitosan.
Chitosan, the deacetylated derivative of chitin, can be found in the cell wall of some fungi and is used in translational applications. We have shown that highly purified preparations of chitosan, but not chitin, activate the NOD-like receptor family, pyrin domain containing 3 (NLRP3) inflammasome in primed mouse bone marrow-derived macrophages (BMMΦ), inducing a robust IL-1β response. In this article, we further define specific cell types that are activated and delineate mechanisms of activation. BMMΦ differentiated to promote a classically activated (M1) phenotype released more IL-1β in response to chitosan than intermediate or alternatively activated macrophages (M2). Chitosan, but not chitin, induced a robust IL-1β response in mouse dendritic cells, peritoneal macrophages, and human PBMCs. Three mechanisms for NLRP3 inflammasome activation may contribute: K(+) efflux, reactive oxygen species, and lysosomal destabilization. The contributions of these mechanisms were tested using a K(+) efflux inhibitor, high extracellular potassium, a mitochondrial reactive oxygen species inhibitor, lysosomal acidification inhibitors, and a cathepsin B inhibitor. These studies revealed that each of these pathways participated in optimal NLRP3 inflammasome activation by chitosan. Finally, neither chitosan nor chitin stimulated significant release from unprimed BMMΦ of any of 22 cytokines and chemokines assayed. This study has the following conclusions: 1) chitosan, but not chitin, stimulates IL-1β release from multiple murine and human cell types; 2) multiple nonredundant mechanisms appear to participate in inflammasome activation by chitosan; and 3) chitin and chitosan are relatively weak stimulators of inflammatory mediators from unprimed BMMΦ. These data have implications for understanding the nature of the immune response to microbes and biomaterials that contain chitin and chitosan.
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; and.
Chelsea L
CL
Bueter
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; and.
Chrono K
CK
Lee
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; and.
Jennifer P
JP
Wang
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01605.
Gary R
GR
Ostroff
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; and.
Charles A
CA
Specht
Department of Medicine, University of Massachusetts Medical School, Worcester, MA 01605; and stuart.levitz@umassmed.edu.
Stuart M
SM
Levitz
D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000276:immunology*; D002352:Carrier Proteins / Q000235:genetics / Q000276:immunology; D048271:Chitosan / Q000494:pharmacology*; D006490:Hemostatics / Q000494:pharmacology*; D006801:Humans; D058847:Inflammasomes / Q000235:genetics / Q000276:immunology; D053583:Interleukin-1beta / Q000235:genetics / Q000276:immunology; D008264:Macrophages / Q000166:cytology / Q000276:immunology*; D051379:Mice; D018345:Mice, Knockout; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; D017382:Reactive Oxygen Species / Q000276:immunology
D002352:Carrier Proteins; D006490:Hemostatics; C508585:IL1B protein, human; D058847:Inflammasomes; D053583:Interleukin-1beta; D000071199:NLR Family, Pyrin Domain-Containing 3 Protein; C453881:NLRP3 protein, human; C492716:Nlrp3 protein, mouse; D017382:Reactive Oxygen Species; D048271:Chitosan