Healing of Ocular Herpetic Disease Following Treatment With an Engineered FGF-1 Is Associated With Increased 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 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 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.

Canonical fibroblast growth factors in viral infection

“…The therapeutic outcome of engineered FGF1 was associated with significant decrease in the frequency of MFs infiltrating the cornea and polarization of the inflammatory response towards the M2 phenotype, and to lower levels of pro‐inflammatory factors released by M1 cells, thus ascribing the effect of FGF‐1 to the nature of the inflammatory cells infiltrating HSV1‐ lesions, rather than to inhibition of viral replication. These findings were confirmed ex vivo on human primary MFs 61 . In agreement with these results, systemic FGF1 treatment was found to significantly ameliorate LPS‐induced histopathological inflammatory cell infiltration and proinflammatory cytokine levels in B6 mice.…”

“…These findings were confirmed ex vivo on human primary MFs. 61 In agreement with these results, systemic FGF1 treatment was found to significantly ameliorate LPS-induced histopathological inflammatory cell infiltration and proinflammatory cytokine levels in B6 mice. In addition, FGF1 pretreatment significantly reduced LPS-induced inflammation.…”

New developments in the biology of fibroblast growth factors

“…In a mouse model, antibody neutralization of FGF2, but not other angiogenic factors, suppressed pathological neovascularization that occurred after resolution of the infection (Gurung et al, 2018). Treatment with a stabilized FGF1 (TTHX1114) concurrent with the primary infection was beneficial and showed reduction in recurrent stromal keratitis and blepharitis, without affecting viral replication (Dhanushkodi et al, 2021). Thus, FGF signaling has time sensitive effects on the pathogenesis of corneal HSV‐1 infection.…”

Osteopontin contributes to virus resistance associated with type I IFN expression, activation of downstream ifn-inducible effector genes, and CCR2+CD115+CD206+ macrophage infiltration following ocular HSV-1 infection of mice

“…Whereas there was no significant difference between the two groups, two subpopulations of macrophages were found to be significantly reduced in the cornea of OPN KO mice; CD115 + CD206 + CCR2 + CD183 - F4/80 + CX 3 CR1 + and CD115 + CD206 + CCR2 + CD183 + F4/80 + CX 3 CR1 + macrophages. In the past and more recently, macrophages that reside or are recruited to the cornea following HSV-1 infection have been broadly defined in terms of the expression of CD11b, F4/80, Ly6C, Ly6G, and/or CD206 or indirectly through genetic manipulation of genes that skew development toward an M1 vs M2 functional phenotype ( 13 , 85 , 86 ). We reasoned further identification of subpopulations of macrophages may identify specific cell types associated with the corneal pathology observed in the WT but not OPN KO mice and not defined by “M1” vs “M2” status as monocytes/macrophages have a high degree of plasticity ( 87 ).…”