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Deepak Shukla, Alex Agelidis, Satvik Hadigal; Heparanase is a Host-Encoded Virulence Factor for Herpes Simplex Virus Ocular Infection. Invest. Ophthalmol. Vis. Sci. 201657(12):.
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© ARVO (1962-2015); The Authors (2016-present)
Ocular herpes simplex virus type-1 (HSV-1) infection is often accompanied by chronic inflammation and neovascularization. Very little understanding exists on intrinsic cellular factors that contribute directly to the development of corneal disease. Our study demonstrates a novel role for heparanse as a host encoded virulence factor that directly controls the emergence of corneal disease symptoms.
Multiple HSV-1 infection models including human corneal epithelial (HCE) cells, cultured human and porcine corneas, and murine corneal infection were used for the study. Flow cytometry, fluorescence microscopy, ELISA, and confocal fluorescence microscopy were used for monitoring and quantitative assessment of changes in the levels of heparanase, several cytokines and pro-angiogenic growth factors. Murine corneas (with or without fluorescein staining) were examined for tissue damage using slit lamp biomicroscope and scored using a four point scale. Quantitative RT PCR (qRT-PCR) was used for mRNA quantification and immunoblotting was used to assess viral protein levels.
Here we demonstrate that upon HSV-1 infection of the murine corneas heparanse expression is upregulated and the enzyme can be found relocated to the nucleus of infected cells. As a direct result of heparanse upregulation, the levels of many different cytokines and growth factors including Interferon alpha and beta, TNF-alpha, IL-6, IL-8, RANTES, and VEGF go up. The upregulation of cytokine expression in corneal cells can be achieved without HSV-1 infection by overexpressing an active form of heparanse in cells but not by the full-length proenzyme. Transgenic overexpression of heparanase in murine corneas results in exacerbation of HSV disease and disease symptoms. Reverse is seen by downregulation of heparanse by shRNA transfection in the murine corneas.
Overall, our findings implicate heparanse as a novel cellular regulator and a virulence factor for corneal disease development upon HSV-1 infection. Our work establishes the existence of a unique intrinsic host factor that directly contributes to the inflammation and neovascularization seen during HSV-1 infection of the cornea. It also identifies a novel druggable pathway for ocular herpes management.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.
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