Entamoeba histolytica-Induced Caspase-4 Activation Regulates IL-1β Secretion Through Caspase-1

Quach, Jeanie

Entamoeba histolytica-Induced Caspase-4 Activation Regulates IL-1β Secretion Through Caspase-1

dc.contributor.advisor	Chadee, Kris C.
dc.contributor.author	Quach, Jeanie
dc.contributor.committeemember	McCafferty, Donna-Marie
dc.contributor.committeemember	Yates, Robin Michael
dc.date	2018-06
dc.date.accessioned	2018-05-01T17:33:06Z
dc.date.available	2018-05-01T17:33:06Z
dc.date.issued	2018-04-27
dc.description.abstract	Entamoeba histolytica (Eh) is the causative agent of amebiasis, one of the top four parasitic causes of mortality worldwide. In 90% of infected individuals, Eh harmlessly colonizes the large intestine and results in a non-invasive and asymptomatic infection. In the remaining 10% of infected individuals, the parasite breaches the intestinal barrier causing amebic colitis and in rare cases, it can cause extra-intestinal lesions, mainly liver abscesses. During invasion, Eh encounter macrophages in the lamina propria and this intricate host-parasite interaction is critical in eliciting a tissue damaging raging pro-inflammatory response. When Eh binds macrophages via the Gal-lectin, surface EhCP-A5 ligates α5β1 integrin to activate caspase-1 in a complex known as the NLRP3 inflammasome. In this study, we investigated the parasite requirements underlying macrophage caspase-4 and -1 activation and the role caspase-4 play in augmenting pro-inflammatory cytokine responses. Surprisingly, caspase-4 activation was similar to caspase-1 requiring live Eh attachment via the Gal-lectin, EhCP-A5 and cellular stresses such as K+ efflux and ROS. However, unlike caspase-1, caspase-4 activation was independent of ASC and NLRP3. Using CRISPR/Cas9 gene editing of caspase-4 and caspase-1 in human macrophages, we determined that caspase-1 and bioactive IL-1β release was highly dependent on caspase-4 activation in response to Eh. Formaldehyde cross-linking to stabilize protein-protein interactions in transfected COS-7 cells stimulated with Eh revealed that caspase-4 specifically interacted with caspase-1 in a protein complex that enhanced the cleavage of caspase-1 CARD domains to augment IL-1β release. The mouse ortholog caspase-11, displayed similar requirements for its activation, however, it was not involved in regulating caspase-1 activation in the same way as caspase-4. These findings reveal a novel role for human caspase-4 as a critical sensor molecule to amplify downstream pro-inflammatory responses when macrophage encounters live Eh.	en_US
dc.identifier.citation	Quach, J. (2018). Entamoeba histolytica-Induced Caspase-4 Activation Regulates IL-1β Secretion Through Caspase-1 (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31866	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/31866
dc.identifier.uri	http://hdl.handle.net/1880/106580
dc.language.iso	eng
dc.publisher.faculty	Cumming School of Medicine
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University 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.
dc.subject	Entamoeba histolytica
dc.subject	caspase-4
dc.subject	caspase-1
dc.subject	IL-1beta
dc.subject	inflammasome
dc.subject.classification	Microbiology	en_US
dc.subject.classification	Parasitology	en_US
dc.subject.classification	Immunology	en_US
dc.title	Entamoeba histolytica-Induced Caspase-4 Activation Regulates IL-1β Secretion Through Caspase-1
dc.type	doctoral thesis
thesis.degree.discipline	Microbiology & Infectious Diseases
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.item.requestcopy	true