Kleinman, Adam Joseph
(2022)
SIV REACTIVATION FROM LATENCY IN VIRALLY SUPPRESSED MACAQUES USING THE HDACi ROMIDEPSIN AND CYCLOPHOSPHAMIDE.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
HIV persistence in latent reservoirs requires lifelong antiretroviral therapy (ART) but does not eradicate virus nor ameliorate all non-AIDS comorbidities, necessitating a cure. Here, we investigated multiple strategies to curb the reservoir and facilitate a functional cure of HIV. We thus studied the impact of cyclophosphamide (Cy) and romidepsin (RMD) on the SIV reservoir. Cy was used as a regulatory T cell (Treg) depleting agent and cytoreduction agent at low or high doses, respectively, to reduce the size of the latent reservoir in SIV-infected rhesus macaques (RMs). At low doses, Cy did not selectively deplete Tregs, nor result in SIV reactivation. At high doses, Cy resulted in substantial SIV reactivation, but when administered with ART, it did not reactivate virus and had unacceptable toxicity and morbidity. Thus, we showed that Cy is not feasible as an HIV cure therapeutic. We next characterized the effects of RMD in SIV-uninfected and infected RMs for the purpose of understanding the pharmacokinetics, immunological effects, and potential impact on the viral reservoir. We demonstrated that RMD retention was greater in the gut and LNs than in plasma. Further, RMD was associated with transient lymphopenia that was explained by apoptosis, downregulation of lymphocyte surface markers, upregulation of homing markers, and migration to the gut and LNs. We followed this study - with repeated RMD infusions in our RM model of functional cure. Repeated infusions reactivated virus, with reduced reactivation at subsequent infusions. Two animals did not yield detectable viremia after the second and third infusions and were thus administered CD8-depleting antibody. Remaining RMs received “double infusions” which were well tolerated, induced prolonged immune activation, and increased viral reactivation. Decreases in viral reactivation were associated with longitudinal increases in the SIV-specific immune response and decreases in cell-associated viral DNA. Further, one animal did not reactivate after CD8-depletion and viral outgrowth from CD4+ T cells showed a lack of replication-competent provirus at that time. However, tissue CD4+ T cells still contained replication-competent provirus. Thus, our results show that repeated RMD infusions can safely reduce the size of the latent reservoir in the context of a healthy immune response.
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Details
Item Type: |
University of Pittsburgh ETD
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Status: |
Unpublished |
Creators/Authors: |
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ETD Committee: |
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Date: |
1 January 2022 |
Date Type: |
Publication |
Defense Date: |
27 October 2021 |
Approval Date: |
1 January 2022 |
Submission Date: |
10 November 2021 |
Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
Number of Pages: |
216 |
Institution: |
University of Pittsburgh |
Schools and Programs: |
School of Medicine > Microbiology and Immunology |
Degree: |
PhD - Doctor of Philosophy |
Thesis Type: |
Doctoral Dissertation |
Refereed: |
Yes |
Uncontrolled Keywords: |
human immunodeficiency virus; hiv; simian immunodeficiency virus; siv; latency reactivation; latent reservoir; cure; romidepsin; cyclophosphamide; shock and kill; regulatory t cells; tregs; treg depletion |
Date Deposited: |
01 Jan 2022 20:36 |
Last Modified: |
01 Jan 2022 20:36 |
URI: |
http://d-scholarship.pitt.edu/id/eprint/41907 |
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