Abstract
Purpose :
Plasmacytoid dendritic cells (pDCs) represent a highly functional subset of bone marrow-derived cells that play a key role in anti-viral and other inflammatory responses. Here we investigate the mechanisms by which corneal pDCs modulate the inflammation
Methods :
Corneal inflammation was induced by inoculation of herpes simplex virus (HSV)-1 or after suture placement in BDCA-2-DTR mice, in which local pDCs were depleted by subconjunctival (s.cj.) injections of diphtheria toxin (DT). Corneal opacity was scored (0-4 scale) and immune cells analyzed by immunofluorescence staining (IF) or flow cytometry (FC) for CD45 (pan-leukocyte marker), Gr-1 (neutrophils) and F4-80 (macrophages). TGF-β1 was quantified by RT-qPCR and ELISA in inflamed corneas. TGF-β1 in naïve corneal pDCs was compared to non-pDC CD45+ cells by FC and TGF-β1 mRNA was assessed by single cell qRT-PCR of sorted corneal pDCs. S.cj. corneal TGF-β1 blockade was performed and opacity and immune cell infiltration were determined. Local adoptive transfer (LAT) of sorted pDCs was performed to debrided corneas by using fibrin sealant 24h before HSV-1 infection
Results :
We observed an increased corneal opacity after pDC-depletion at day 3 after HSV-1 infection (p=0.04) and at day 7 in sutured corneas (p<0.01). Increased influx of CD45+, Gr-1+, and F4-80+ cells was noted compared to sham (PBS) controls (p<0.05). TGF-β1 mRNA and protein decreased (p<0.05) after pDC depletion in inflamed corneas compared to sham. Corneal FC showed TGF-β1 production in naïve pDCs compared to non-pDCs CD45+cells (60% vs 6%). TGF-β1 mRNA in sorted corneal pDCs was upregulated in activated pDCs compared to naïve pDCs (p<0.01). Corneal TGF-β1 blockade in HSV-1 infection showed increased opacity(p=0.04) and influx of CD45+cells (2.2-fold), Gr-1+cells (4.4-fold) and F4-80+ cells (6.0-fold) compared to sham by IF. Sutured corneas showed an increase opacity (p=0.04) and influx of CD45+cells (8% to 13%), Gr-1+cells (27% to 38%) and F4-80+cells (23% to 33%) by FC. LAT of pDCs prior to HSV-1 infection showed improvement in corneal opacity (1.5 vs. 0.5, p<0.01) and increased TGF-β1 mRNA (2.8 fold, p=0.01) in HSV-1 infected corneas compared to sham (sealant only) controls
Conclusions :
Our data shows that corneal pDCs regulate corneal inflammation in a TGF-β1-mediated fashion. Adoptive transfer of pDCs may serve as a novel anti-inflammatory cell-based therapeutic approach
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.