Kinner, Lauren
(2017)
HEAT SHOCK PROTEIN GP96 DRIVES DICHOTOMOUS LYMPHOCYTE RESPONSES VIA DNA METHYLOME REMODELING AND STAT1 SIGNALING IN ANTIGEN PRESENTING CELLS.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
Immune responses primed by endogenous heat shock proteins (HSPs), specifically gp96, have been used for immunotherapy of cancer. Immunization with low doses of gp96 primes a response that is dominated by T helper type 1 (Th1) cells and cytotoxic T lymphocytes (CTLs), which allows for recognition and killing of tumor cells. However, increasing the dose of gp96 primes a response characterized by regulatory T (Treg) cells and immunosuppression. Although the T cell responses driving this dose dichotomy have been studied in multiple systems, innate mechanisms that control T cells in the context of gp96 immunization remains unknown. The antigen presenting cells (APCs) involved in this response are the main focus of Chapters 1 and 2 of this thesis. Here we show gp96 preferentially engages conventional and plasmacytoid dendritic cells (pDCs) under low and high doses respectively, through the HSP receptor CD91. We show that DNA methyltransferase 1 (DNMT1) is active in multiple APC population in response to gp96 stimulation, and that global DNA methylome and protein expression changes occur in these populations in response to in vivo immunization. Methylation-dependent upregulation of neuropilin-1 (Nrp1) on pDCs enables long term interactions with Treg cells that enhance their function in suppressing ongoing Th1 anti-tumor immunity. Our study defines a CD91-dependent mechanism through which gp96 controls dichotomous immune responses, relevant to the therapy of cancer and autoimmunity.
Additionally, we are interested in the signaling pathways initiated by gp96-CD91 interaction. Previous studies have shown that NF-B and p38 MAPK are activated in HSP-responsive macrophages, but the consequences of p38 activation were not investigated. Chapter 3 will focus on the downstream mediators of p38, specifically the transcription factor STAT1, and the cytokine expression and secretion that follows. We show that gp96-treated macrophages upregulate STAT1-dependent cytokines as a result of STAT1 phosphorylation. This event requires intact CD91 and p38 MAPK. Importantly, STAT1 target CXCL10 is upregulated in response to gp96 and is critical for APC-NK cell crosstalk. Given that NK cells are required for anti-tumor immunity elicited by gp96 immunization, we hypothesize that STAT1 activation in responding APCs is necessary for tumor rejection.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
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| ETD Committee: |
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| Date: |
5 July 2017 |
| Date Type: |
Publication |
| Defense Date: |
9 June 2017 |
| Approval Date: |
5 July 2017 |
| Submission Date: |
19 June 2017 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
155 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
School of Medicine > Immunology |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Antigen presenting cells, heat shock proteins, DNA methylation, STAT1 |
| Date Deposited: |
05 Jul 2017 19:47 |
| Last Modified: |
05 Jul 2017 19:47 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/32491 |
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