Doctoral Dissertations

Date of Award

5-2013

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Comparative and Experimental Medicine

Major Professor

Barry T Rouse

Committee Members

Timothy Sparer, Stephen Kennel, Seung Baek

Abstract

Herpes simplex virus (HSV) infection of the eye results in chronic immunopathological response in corneal stroma orchestrated by CD4 T cells. Due to its neurotrophic nature, HSV can also invade brain and leads to deadly encephalitis. HSV infection of the eyes leads to corneal neovascularization (CV), which is an important step in the pathogenesis of herpetic stromal keratitis (HSK), an important cause of human blindness. This study was undertaken to investigate the contribution of miRNAs and Robo4 signaling in HSK. The role of miR-132 and miR-155 was evaluated. In the first chapter, we review literature regarding the contribution of miRNAs in several human diseases and speculate about the role of those miRNAs in herpes viral latency and HSK. We also discuss involvement of Robo4 signaling in the context of pathological angiogenesis.

In the second chapter, we show that HSV infection of the eyes of mice leads to appearance of Robo4+ blood vessel endothelial cells in corneas but levels of Slit2 (a ligand for Robo4 receptor) were minimal. The provision of exogenous Slit2 protein reduced CV following HSV infection.

In the third chapter, we report the role of miR-132 in angiogenesis following ocular HSV infection. We observed VEGF and IL-17 driven upregulation of miR-132 during HSK. miR-132 was shown to augment VEGF induced angiogenic responses and blockade of miR-132 using antagomir nanoparticles reduced pathological angiogenesis in eyes after HSV infection.

In the fourth chapter, we analyzed the involvement of miR-155 after ocular infection with HSV. The mice unable to produce miR-155 were found to be highly susceptible to encephalitis after HSV infection with the majority of mice dyeing by day 9. We further show that virus replication in brain was responsible for death in miR-155 null mice. When T cell responses were measured, miR-155 knockout animals demonstrated attenuated CD4 and virus specific CD8 T cell immunity. Additionally, we also evaluated the role of miR-155 in HSK. miR-155KO survivors from herpes simplex encephalitis were relatively resistant to HSK. In conclusion, we demonstrated that the miR-155 is a regulator of herpes simplex encephalitis but it promotes inflammation during HSK.

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