Bousman, ChadGreenway, StevenVaziri, Nazanin2024-08-012024-08-012024-07-29Vaziri, N. (2024). In vitro modeling of clozapine-induced myocarditis to elucidate mechanism and identify potential therapeutics (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.https://hdl.handle.net/1880/119305Schizophrenia is a common and devastating psychiatric disorder. A significant proportion (30-60%) of patients show incomplete recovery from their symptoms despite treatment and are classified as “treatment-resistant.” Clozapine is the only approved pharmacotherapy for treatment-resistant schizophrenia. However, the widespread utilization of clozapine is constrained due to the potential for severe adverse effects, including myocarditis. Multiple mechanisms have been suggested to account for the cardiotoxic effects of clozapine, yet these investigations have not used cells derived from clozapine treated patients and the precise mechanism of clozapine-induced myocarditis remains unknown. For this study, cardiomyocytes that were derived from induced pluripotent stem cells (iPSC-CMs) generated from four patients with treatment-resistant schizophrenia with (n = 2) and without (n = 2) a history of clozapine-induced myocarditis were used to test the hypothesis that that clozapine increases mitochondrial ROS production and mitochondrial fragmentation that then leads to activation of the NLRP3 inflammasome pathway which induces myocarditis. We found that treatment of cardiomyocytes with a physiologically relevant dose (2.8 μM) of clozapine for 24 hours: (1) induced cardiomyocyte contractile dysfunction, increased cytotoxicity, and apoptosis, (2) induced oxidative stress by elevating the level of reactive oxygen species and increasing mitochondrial fragmentation, and (3) elevated levels of proinflammatory cytokines and activated the NLRP3 inflammasome. These effects were more pronounced in iPSC-CMs from individuals with a history of clozapine-induced myocarditis. Pharmacological protection of mitochondria with elamipretide and blockade of inflammasome signalling with ustekinumab attenuated these clozapine-induced cardiotoxic effects. Collectively, these results suggest that a mitochondria- and NLRP3 inflammasome-mediated mechanism is responsible for the development of myocarditis associated with clozapine and support further evaluation of therapeutics that target mitochondria and NLRP3 signaling.enUniversity of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.Biophysics--Medicaldoctoral thesis