Oncostatin M (OSM) Contributes to Corneal Epitheliopathy in Tear Deficient Dry Eye Disease due to Chronic ocular Graft-Vs-Host Disease (oGVHD)

Abstract

Purpose : We investigated whether OSM, a Heparin binding protein, is associated with corneal epitheliopathy in oGVHD.

Methods : Ocular surface washings were collected in patients who had “definite” oGVHD or “none” oGVHD following allogeneic bone marrow transplant as well as in age matched healthy subjects, and analyzed for OSM levels using Luminex. Immunofluorescence for OSM was performed on mucocellular aggregrates and cytospin preparations of ocular surface washings. Neutrophil Extracellular Traps (NETs) with or without incubation with OSM neutralizing antibodies (OSM NAb) were applied to naïve murine corneas and epitheliopathy determined with fluorescence staining.

Results : Ocular surface washings of “definite” oGVHD patients had significantly higher levels of OSM as compared to “none” oGVHD patients and healthy subjects. OSM was present in significantly higher levels in supernatant of PMA stimulated neutrophils as compared to non-stimulated neutrophils and RPMI culture media suggesting NETs as the source of OSM. First, we investigated whether reducing OSM levels in naive NETs using OSM NAb abrogates NET-induced epitheliopathy in murine corneas. We applied naive NETs and OSM NAb incubated NETs to naïve murine corneas for five consecutive days. Significantly greater corneal fluorescein staining was observed at Day 5 following application of NETs (7.20 ± 0.97; p<0.05) as compared to OSM NAb incubated NETs (0.40 ± 0.24). At Day 5, corneas were excised and abundance of inflammatory cytokines (IL-1β, IL-6 and IP-10) were determined in lysates. Corneas exposed to NETs had significantly higher abundance of these inflammatory cytokines as compared and OSM NAb incubated NETs. Second, we investigated whether OSM recombinant protein can produce epitheliopathy similar to NETs and whether reducing OSM levels using OSM NAb abrogates that effect. Significantly greater corneal fluorescein staining was observed at Day 5 following application of OSM (8.75 ± 0.48; p<0.05) as compared to OSM incubated with OSM NAb (0.80 ± 0.37).

Conclusions : These interlocking experiments suggest that OSM is a molecular component of NETs and is present in abundance over the ocular surface of “definite” oGVHD patients. OSM is associated with corneal epitheliopathy and inflammation and may be a therapeutic target to reduce epitheliopathy.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.