Abstract
Purpose :
The ocular surface is a functional unit that is clinically inflamed in total limbal stem cell deficiency (TLSCD); the tear film reflects this level of inflammation. We aim to determine the tear cytokines most highly expressed in eyes with TLSCD.
Methods :
Consecutive patients with unilateral TLSCD undergoing ALSCT (n=23) and 11 healthy individuals (controls) were analysed. Tears samples were collected from both eyes at 2 timepoints within 3 months of ALSCT and 4 timepoints post-ALSCT (1, 3, 6, 12 months), using Schirmer’s strips. Tears were extracted from the strips by centrifuging in an extraction buffer (MSD, USA) and were then tested on an ELISA-based array of 10 inflammatory cytokines (V-Plex Assay, MSD) per sample. Cytokines chosen for analysis were determined by a previous experiment analysing inflammation in corneal pannus tissue from the same patients.
Results :
TNFα (p=0.003 in fellow eye, p<0.001 in TLSCD eye), IL1β (p<0.001 both eyes), IL2 (p<0.001 both eyes), IL4 (p<0.001 both eyes), IL6 (p=0.006 fellow eye, p<0.001 TLSCD) and IL8 (p<0.001 both eyes) were significantly elevated pre-op in both eyes of patients with unilateral TLSCD compared with controls. At 12 months, TNFα and IL1β return to similar levels to controls; IL2, IL4, IL6 and IL8 remain elevated in both eyes. There was no significant difference between patients who originally had unilateral or bilateral injuries. There was no correlation between cytokine levels and duration of injury (p>0.05). There was no significant difference between eyes of unilateral TLSCD patients pre-op except for IL2 (p=0.02) and IL6 (p=0.004), which were only elevated in the TLSCD eye. TNFα (p<0.001), IL1β (p=0.04), IL6 (p<0.001), IL8 (p<0.001), IL10 (p=0.02), IL12p70 (p=0.02) and IL13 (p=0.02) were significantly elevated at 1 month post-ALSCT, compared to pre-op in TLSCD eyes versus fellow eyes; however this difference between eyes disappears, returning to pre-op levels by 6 months post-op.
Conclusions :
Tear cytokine levels are elevated in both eyes of patients with unilateral TLSCD, reflecting a subclinical involvement of tears in the contralateral clinically and histologically unaffected eye and showing bilateral inflammatory changes in these patients (sympathetic immune response). TNFα and IL1β return to similar levels to controls following ALSCT. Further work is required to explain these findings.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.