Gene expression changes in conjunctival cells associated with contact lens wear and discomfort

This study aimed to analyze the differences in the expression of pain-related genes in conjunctival epithelial cells among symptomatic contact lens (CL) wearers (SCLWs), asymptomatic CL wearers (ACLWs), and non-CL wearers (non-CLWs). For this study, 60 participants (20 non-CLWs, 40 CLWs) were enrolled. The CLW group comprised 20 ACLWs and 20 SCLWs according to the Contact Lens Dry Eye Questionnaire short form©. Conjunctival cells were collected using impression cytology, and RNA was isolated and used to determine the expression levels of 85 human genes involved in neuropathic and inflammatory pain. The effects of CL wear and discomfort were evaluated using mixed-effects ANOVA with partially nested fixed-effects model. Gene set enrichment analysis was performed to assign biological meaning to sets of differentially expressed genes. Six genes (CD200, EDN1, GRIN1, PTGS1, P2RX7, and TNF) were significantly upregulated in CLWs compared to non-CLWs. Eleven genes (ADORA1, BDKRB1, CACNA1B, DBH, GRIN1, GRM1, HTR1A, PDYN, PTGS1, P2RX3, and TNF) were downregulated in SCLWs compared to ACLWs. These genes were mainly related to pain, synaptic transmission and signaling, ion transport, calcium transport and concentration, and cell-cell signaling. CL wear modified the expression of pain- and inflammation-related genes in conjunctival epithelial cells. These changes may be in part, along with other mechanisms, responsible for CL discomfort in SCLWs.