The Impact of IL-36γ Treatment on HSV-2 Replication and Immune Cell Recruitment in the Female Reproductive Tract

Herpes simplex virus 2 (HSV-2) is one of the most common sexually transmitted infections (STI), affecting over 267 million women worldwide. HSV-2 causes a chronic, latent infection that increases the risk for acquisition with other STI, including HIV. Currently, there is no vaccine against HSV-2 and novel anti-viral treatments are needed. IL-36γ is a newly characterized cytokine that has been shown to play a role in inflammation and be upregulated in response to microbial infection and tissue damage. We have shown that IL-36γ is expressed in the female reproductive tract (FRT) and is upregulated by HSV-2 infection in vitro and in vivo. IL-36γ in turn induces production of proinflammatory cytokines and chemokines in human vaginal epithelial cells (VEC) that can aid in immune cell recruitment. We hypothesize that IL-36γ is a key regulator of mucosal inflammation in the FRT and functions to limit HSV-2 infection. We have demonstrated that IL-36γ treatment prior to infection protects against HSV-2 replication, disease severity, and promotes survival in a lethal mouse model. Thus, the objective of this study is to understand the mechanisms whereby IL-36γ inhibits HSV-2 replication. To understand the impact of IL-36γ on the HSV-2 lifecycle, we pretreated VEC with IL-36γ and evaluated viral titer during virus attachment and entry, replication, and cell-to-cell spread by plaque assay. Pretreatment with IL-36γ 4h prior to infection did not significantly reduce viral titers in VEC monolayers relative to untreated groups. This suggesting that IL-36γ may play a more significant role in immune cell recruitment during HSV-2 infection. To test this, FRT tissue samples from HSV-2 infected IL-36γ -/- and WT mice were analyzed by histochemistry to characterize immune cell recruitment. No clear pattern was determined for tissue samples in which cell clusters were observed and cell type within recruited clusters was unable to be identified at the current magnification. As these projects continue, the data will aid in elucidating the mechanism and level to which IL-36γ impacts HSV-2 infection in human VEC and FRT models.