Abstract
Purpose :
To present the NOD2 adjuvant-induction of caspase/NFκβ-mediated acute cell death (characterized by polymeric DNA fragmentation) in tears and conjunctival tissue coincidental with bilateral conjunctivitis.
Methods :
Bilateral tear samples and conjunctival tissue were collected from rabbits following topical muramyl dipeptide (MDP) application 1X104 50% tissue culture cytotoxic doses. Tear and conjunctival tissue were collected at 5-6 h post monocular topical MDP application (1-2 h post onset of conjunctivitis in the ipsilateral eye) were air-dried on glass slides and fixed in cold 70% ethanol. Conjunctival tissue were fixed in cold 70% ethanol and embedded in paraffin. Utilizing immunofluorescent antibody (IFA) technique, caspase-3, NF-κβ, 8-OHdG (marker for oxidized DNA) and IgG positive cells were detected in tear fluid and conjunctival tissue sections.
Results :
The onset of conjunctivitis, activation of caspase-3, detection polymeric DNA fragments and increased leukocytic infiltrate in acute ipsilateral tears was as previously reported (IOVS Abstract 2007-A-5226). H&E staining of the contralateral and ipsilateral air-dried tear fluid and fixed conjunctival tissue sections revealed numerous PMN and leukocytes in the ipsilateral inflamed eye. IFA staining of the bilateral tear samples revealed 8-OHdG positive PMN as well as caspase-3 positive leukocytes and sluffed conjunctival cells. IFA of the bilateral conjunctival tissues revealed a marked increase in 8-OHdG PMN and IgG positive leukocyte in the ipsilateral eye. Moreover, active caspase-3 positive, NFκβ-positive conjunctival epithelial cells were detected in the ipsilateral eye.
Conclusions :
The onset of conjunctivitis in rabbits post topical application of MDP was associated with detection of active caspase-3/NF-κβ-positive cells in ipsilateral tear and conjunctiva. The results support targeting of NOD pathway activation in conjunctival epithelia to modulate the initiation stage of peptidoglycan-induced conjunctivitis.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.