Elimination of caspase-8 -sufficient and -deficient target cells by antigen-specific CD8+ T lymphocytes

• Grant number: 15/26396-3
• Support Opportunities: Scholarships in Brazil - Master
• Start date: April 01, 2016
• End date: January 31, 2018
• Field of knowledge: Biological Sciences - Immunology - Cellular Immunology
• Principal Investigator: João Gustavo Pessini Amarante Mendes
• Grantee: Isabella Suzuki Sampaio
• Host Institution: Instituto de Ciências Biomédicas (ICB). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The direct killing of target cells by cytotoxic T lymphocytes (CTLs) plays a major role in protective immunity to pathogens and tumor cells, which can be triggered by either the action of perforin and granzymes or FAS-FASL interactions. The Fas-FasL interaction leads to apoptosis through the formation of "death-inducing signaling complex" (DISC), which is composed by the cytoplasmic tail of Fas, the adaptor protein FADD and the apical pro-caspase-8. At the complex, caspase-8 become activated and transduce the apoptotic signal by cleaving the effector caspases-3, -6 and -7 and/or the Bcl-2 family member Bid. Importantly, deficiency in caspase-8 is associated with autoimmune lymphoproliferative syndrome (ALPS). Recently, it has been demonstrated a correlation between mutations in CASP8 in tumors from patients with high cytolytic activity, suggesting that deficiency in caspase-8 may represent a mechanism by which tumor cells evade the apoptotic signaling triggered by CTLs. We have been using recombinant human replication-deficient adenovirus 5 (hAd5) to study in vivo CTL-mediated immune response. To evaluate the elicited CTL response, immunized and non-immunized mice receive i.v. syngeneic splenocytes labeled with different fluorescent dyes and pulsed (target) or non-pulsed (control) with specific peptides, mixed in a 1:1 ratio. Specific target elimination is assessed after 18-24h by flow cytometry analysis of splenocytes. To interrogate the relative role of caspase-8 in the resistance of target cells to in vivo CTL killing, we will use caspase-8 sufficient and deficient splenocytes and cell lines as targets in our system. And to evaluate the relative contribution of different cell death pathway, we will immunize wild type, perforin-/- or FASL-deficient mice. In sum, our project should contribute to further understanding of the role of caspase-8 in the resistance of tumor cells to in vivo elimination by cytotoxic T lymphocytes. (AU)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

SAMPAIO, Isabella Suzuki. Antigen-specific elimination of caspase-8-deficient or sufficient target cells by CD8+ T lymphocytes. 2018. Master's Dissertation - Universidade de São Paulo (USP). Instituto de Ciências Biomédicas (ICB/SDI) São Paulo.