Abstract
Purpose :
Plasmacytoid dendritic cells (pDCs), are specialized cells of the immune system that reside in the cornea. Herein, we evaluate the role of resident corneal pDCs in mediating clinical keratitis during asymptomatic primary herpes simplex virus (HSV)-1 keratitis
Methods :
Corneal HSV-1 infection was induced by inoculation of either 10^3 (low-dose) or 10^5 (high-dose) PFU/eye of HSV-1 strain McKrae in scarified corneas in BDCA-2-DTR Tg mice, prior to pDCs depletion by subconjunctival (s.conj.) diphtheria toxin (DT) injections. Clinical corneal opacity was scored on a 0-4 scale. Corneas and trigeminal ganglia (TG) were excised for viral glycoprotein B mRNA quantification by qRT-PCR. Adoptive transfer of pDCs were performed with 10^4 sorted pDCs transferred to debrided corneas by using fibrin sealant 24h before HSV-1 infection in sham and pDC-depleted corneas
Results :
At 3 days post-inoculation (dpi) with low-dose challenge, clinical assessment of corneas of sham- and pDC-depleted mice revealed a marked difference in corneal opacification (0.3 vs. 1.5, p=0.009) respectively, while at high-dose opacity was more severe in pDC-depleted corneas (0.8 vs. 2.4, p<0.001). At 5 dpi, corneal opacity was apparent in all pDC-depleted mice, but only in 25% of sham-depleted controls (0.7 vs 2.7, p=0.004), presenting clinically with less severe keratitis and reduced viral mRNA in the corneal stroma (1.2 vs. 5.2, p=0.036), and in the TG compared to pDC-depleted mice (6.6 vs. 717.0, p=0.015). A 6.6-time fold increased gB RNA in TG in low-dose HSV-1 infected corneas was noticed. Next, adoptive transfer of pDCs was performed in pDC-depleted mice prior to HSV-1 infection in order to restore a resident corneal pDC population. At 3 dpi, corneas with repopulated pDCs showed a lower clinical severity compared to pDC-depleted corneas (0.5 vs. 1.5, p=0.037)
Conclusions :
Our data shows that resident corneal pDCs prevent clinical manifestations in primary HSV-1 infection of the cornea, by controlling HSV-1 replication and spread to the TG. The results further suggest that HSV-1 can travel to TG despite lack of corneal clinical manifestation . Restoring resident corneal pDCs by adoptive transfer improves clinical severity in HSV-1 infected mice, suggesting a pivotal role of pDCs in the clinical outcomes during primary HSV-1 infection
This is a 2020 ARVO Annual Meeting abstract.