Purpose
To assess high molecular weight (HMW) tear proteins, mucins, inflammatory proteins and contact lens wettability in contact lens wearers with dry eye in comparison to normal contact lens wearers.
Methods
The study was a cross-sectional study including 100 healthy, daily (non-overnight), experienced soft contact lens wearers (50 normal and 50 CLDE). Eligible subjects were classified into normal/ CLDE groups based on Contact Lens and Dry Eye Questionnaire scores, tear break up time (TBUT, normal ≥ 7 seconds, CLDE < 7 seconds) and difference between total and comfortable daily lens wear hours (normal < 2, CLDE ≥ 2).
Up to 5 µl unstimulated basal tear samples and wash samples from each eye were collected for lab analyses. HMW tear proteins and mucins in the ocular surface were studied using gel electrophoresis, liquid chromatography-mass spectrometry, Western blotting and periodic acid Schiff (PAS) staining. Tear inflammatory proteins were analyzed using quantibody arrays. Imaging interferometry was used to assess in vivo contact lens wettability.
Results
The CLDE group demonstrated higher grades of papillary conjunctivitis, conjunctival redness and folds (p < 0.0001 for all listed), blepharitis and meibomian gland dysfunction (p = 0.002), conjunctival and corneal staining (p = 0.002 and 0.005). The average TBUT was higher in the normal group (8.02 ± 1.03 and 4.15 ± 1.04 seconds, p < 0.0001). The in vivo contact lens wettability was found to be significantly lower in the CLDE group at all time points analyzed (p < 0.0001).
Two HMW tear bands were observed at 450 kDa and 300 kDa. The band area of the 450 kDa HMW band was significantly greater in CLDE samples (p = 0.003). LC-MS analyses of the HMW bands revealed immunoglobulin fragments, cytokeratins and common tear proteins. Several of these were unique or different in abundance between the subject groups.
Three MUC4 positive bands were observed at ~433, 271 and 52 kDa. Two MUC5AC bands were observed at ~460 and 250 kDa. MUC4/ MUC5AC band characteristics were not different between normal and CLDE samples. PAS-positive glycoprotein bands were observed at 440 kDa and 70 kDa; the latter was more intense in the normal group (p = 0.002).
Of the 50 tested inflammatory proteins, 21 were increased 2-fold or more in the CLDE group. These included IL-4, IL-7, IL-8, IL-12 p70, IL-13, IL-15, GRO, GCF (p < 0.005 for all listed), IL-1b (p=0.006) and IL-11 (p=0.008). EGFR, eotaxin, GCF, GRO, HB-EGF, IFNg, IL -1ra, IL-2, IL-5, IL-6, IL-6 sR, IL-12 p40, MCSF were also elevated in CLDE (p < 0.04).
Conclusions
Characterization of the HMW proteome and differences in immunoglobulins, cytokeratins and tear proteins detected between normal and CLDE subjects offer insight into the potential relevance of HMW proteins in CLDE pathophysiology.
MUC4 and MUC5AC were not different between normal contact lens wearers and those with CLDE. CLDE was also characterized by differences in the lower molecular weight glycoprotein band. Numerous inflammatory markers including a majority of interleukins were elevated in CLDE, indicating a significant role of inflammation in CLDE.