Healing of Primary and Recurrent Mouse Ocular Herpetic Disease Following Topical Ocular Treatment with an Engineered Fibroblast Growth Factor-1 (FGF-1) is Associated with Increased Frequency and Function of Corneal Anti-Inflammatory M2 Macrophages

Abstract

Herpes simplex virus 1 (HSV-1) infects the cornea and caused blinding ocular disease. In the present study, we evaluated whether and how a novel engineered version of fibroblast growth factor-1 (FGF-1), designated as TTHX1114, would reduce the severity of HSV-1-induced primary and recurrent ocular herpes in the mouse model. The efficacy of TTHX1114 against corneal keratopathy was assessed in B6 mice following corneal infection with HSV-1, strain McKrae. Starting day one post infection (PI), mice received TTHX1114 for 14 days. The severity of primary stromal keratitis and blepharitis were monitored up to 28 days PI. Inflammatory cell infiltrating infected corneas were characterized up to day 21 PI. The severity of recurrent herpetic disease was quantified in latently infected B6 mice up to 30 days post-UVB corneal exposure. The effect of TTHX1114 on M1 and M2 macrophage polarization was determined in vivo in mice and in vitro on primary human monocytes-derived macrophages. Compared to HSV-1 infected non-treated mice, the infected and TTHX1114 treated mice exhibited a significant reduction of primary and recurrent stromal keratitis and blepharitis, without affecting virus corneal replication. The therapeutic effect of TTHX1114 was associated with a significant decrease in the frequency of M1 macrophages infiltrating the cornea, which expressed significantly lower levels of pro-inflammatory cytokines and chemokines. This polarization toward M2 phenotype was confirmed in vitro on human primary macrophages. This pre-clinical finding suggests use of this engineered FGF-1 as a novel immunotherapeutic regimen to reduce primary and recurrent HSV-1-induced corneal disease in the clinic. IMPORTANCEHerpes Simplex Virus type 1 (HSV-1) is a prevalent human pathogen that infects the cornea causing potentially blinding herpetic disease. The present study is the first to demonstrate a reduction of primary and recurrent corneal herpetic disease in mice following engineered FGF-1 (TTHX1114) treatment. This was associated with a decrease of pro-inflammatory M1 macrophages and an increase of anti-inflammatory M2 macrophages infiltrating the corneas of HSV-1 infected mice. The finding in mice were confirmed in humans by showing that in vitro FGF-1 treatment skewed the polarization of primary monocyte-derived macrophages into the anti-inflammatory M2 phenotype. Moreover, FGF-1 treatment appeared to reduce production of anti-inflammatory mediators. This pre-clinical finding support this engineered FGF-1 as a novel immunotherapeutic regimen to reduce primary and recurrent corneal herpetic disease in the clinic.