Characterising the Immune Response in Herpes Keratitis

Abstract

Herpes Keratitis (HK) is a debilitating cornea infection that remains the leading cause of infectious blindness in developed countries. Caused primarily by herpes simplex virus type 1 (HSV-1), recurrent inflammation canlead to corneal scarring. This study aims to characterise the subsets of immune cells in human corneal tissue and compare between HK and non-diseased corneas. Understanding the immune interactions in human tissue is key to better management and future vaccine development. We examined the immune cells in human corneas with previous clinical history of HK, and compared to control corneas. By 24 colour flow cytometry, we discovered that CD4 and CD8 T cells in the epithelium and stroma of HK corneas were more activated than in control corneas. We also observed more activated neutrophils in HK corneas. Langerin+ dendritic cells (DCs) were also obvious and more similar to skin DCs, distinguishable from bona fide Langerhans cells. Complimentary imaging mass cytometry with 31 markers confirmed the presence of immune cells within the cornea and the limbal region seen by flow cytometry. Segmentation and clustering analysis showed a heterogenous population of CD11c+ DCs in the epithelium, CD4 and CD8 T cells present in the epithelium and stroma and revealed distinct spatial locations of macrophage populations in the stroma. Furthermore, to examine initial events in HSV-1 infection of the cornea, we adapted our anogenital mucosal explant model to porcine corneal tissue. We infected the corneas topically via high-density microneedle patches (HD-MAPs) dipped in HSV-1 and detected virus infection by RNAscope,. The punctures were consistent and extended into the stroma but HSV-1 was restricted to the corneal epithelium, involving basal and midlevel epithelial cells. Currently, we are adapting this model to human corneal explants to examine HSV-1-resident immune cell interactions. Such studies will help improve immunotherapy for HK and vaccine design to prevent it.