Browsing by Author "Campden, Rhiannon I"
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- ItemOpen AccessA role for cathepsin Z in neuroinflammation provides mechanistic support for an epigenetic risk factor in multiple sclerosis(2017-05-10) Allan, Euan R O; Campden, Rhiannon I; Ewanchuk, Benjamin W; Tailor, Pankaj; Balce, Dale R; McKenna, Neil T; Greene, Catherine J; Warren, Amy L; Reinheckel, Thomas; Yates, Robin MAbstract Background Hypomethylation of the cathepsin Z locus has been proposed as an epigenetic risk factor for multiple sclerosis (MS). Cathepsin Z is a unique lysosomal cysteine cathepsin expressed primarily by antigen presenting cells. While cathepsin Z expression has been associated with neuroinflammatory disorders, a role for cathepsin Z in mediating neuroinflammation has not been previously established. Methods Experimental autoimmune encephalomyelitis (EAE) was induced in both wildtype mice and mice deficient in cathepsin Z. The effects of cathepsin Z-deficiency on the processing and presentation of the autoantigen myelin oligodendrocyte glycoprotein, and on the production of IL-1β and IL-18 were determined in vitro from cells derived from wildtype and cathepsin Z-deficient mice. The effects of cathepsin Z-deficiency on CD4+ T cell activation, migration, and infiltration to the CNS were determined in vivo. Statistical analyses of parametric data were performed by one-way ANOVA followed by Tukey post-hoc tests, or by an unpaired Student’s t test. EAE clinical scoring was analyzed using the Mann–Whitney U test. Results We showed that mice deficient in cathepsin Z have reduced neuroinflammation and dramatically lowered circulating levels of IL-1β during EAE. Deficiency in cathepsin Z did not impact either the processing or the presentation of MOG, or MOG- specific CD4+ T cell activation and trafficking. Consistently, we found that cathepsin Z-deficiency reduced the efficiency of antigen presenting cells to secrete IL-1β, which in turn reduced the ability of mice to generate Th17 responses—critical steps in the pathogenesis of EAE and MS. Conclusion Together, these data support a novel role for cathepsin Z in the propagation of IL-1β-driven neuroinflammation.
- ItemOpen AccessRegulation of the NLRP3 Inflammasome by Cathepsin Z(2020-07-06) Campden, Rhiannon I; Yates, Robin M.; Hollenberg, Morley; Shi, Yan; Khrisendath, Chadee; Akkari, LeilaThe focus of this dissertation is on understanding how cathepsin Z is involved in the initiation of inflammation, and specifically, how cathepsin Z contributes to the production of interleukin (IL)-1? following NLRP3 inflammasome activation. IL-1? is a pro-inflammatory cytokine involved in the recruitment of immune cells and the polarization of TH17 cells. Activation of the NLRP3 inflammasome, which is a macromolecular complex composed of a receptor (NLRP3), an adaptor protein (ASC), and the protease caspase-1, leads to cleavage and release of IL-1?. Cathepsin Z contains dual functions as a C-terminal exopeptidase and an integrin-binding protein. Initially, we explored the involvement of cathepsin Z in the development of inflammation in a mouse model of multiple sclerosis, experimental autoimmune encephalomyelitis (EAE). We found that cathepsin Z is required for the recruitment of immune cells into the central nervous system (CNS). Here, we found cathepsin Z is involved in TH17 polarization due to reduced IL-1?, but not antigen processing, T cell activation nor T cell migration. This led us to investigate the mechanism through which cathepsin Z regulates IL-1? production. We found that extracellular cathepsin Z signals through the ?5 integrin following NLRP3 inflammasome activation. Furthermore, the function of cathepsin Z in this context was dependent on the integrin-binding domain of cathepsin Z and not its proteolytic activity. This reveals another mechanism of NLRP3 regulation through an endogenous extracellular protein that signals through integrins. Finally, we employed proteomic and degradomic approaches following NLRP3 inflammasome activation in the absence of NLRP3 to gain a deeper understanding of the proteins involved in NLRP3 inflammasome activation. In the absence of NLRP3, caspase-1 and IL-1? are degraded, while caspase-4 is stabilized. Further, ROS levels are lower following NLRP3 inflammasome activation with silica in the absence of NLRP3, and the expression of several mitochondrial proteins are deregulated, suggesting the importance of the mitochondria and ROS signalling in NLRP3 inflammasome activation. Collectively, this dissertation reveals a novel extracellular regulatory pathway of the NLRP3 inflammasome and further outlines the signalling function of cathepsin Z in inflammation. This dissertation also presents a dataset of proteins for investigation in NLRP3 inflammasome activation.