CCL20/MIP-3 alpha mRNA expression in the conjunctival epithelium of normal individuals and patients with vernal keratoconjunctivitis

BACKGROUND: CCL20, the single chemokine ligand for CCR6, contributes to recruiting CCR6-expressing memory B cells, memory T cells, Th17 cells and dendritic cells, and is involved in regulating immune responses, homeostasis, and inflammation in mucosal tissues. METHODS: CCL20 messenger RNA (mRNA) expression was analyzed in the conjunctival epithelium in an in vivo study of patients with vernal keratoconjunctivitis (VKC group) and healthy volunteers (control group) using impression cytology. In vitro analysis of CCL20 mRNA was performed using cultured conjunctival epithelial cells (CECs). Real-time polymerase chain reaction was used to assess IL-8 and eotaxin-2 mRNA expression for comparison with CCL20 mRNA expression. RESULTS: In the control group, CCL20 mRNA expression was present in all conjunctival locations. However, CCL20 mRNA expression was significantly higher in the upper palpebral conjunctiva in the severe VKC group than in the mild VKC and control groups (p < 0.05, Steel test). In vitro stimulation of CECs with lipopolysaccharide (LPS) significantly increased CCL20 expression in a concentration-dependent manner that was significantly correlated with expression of IL-8 (p < 0.001, Spearman’s rank correlation coefficient), but not eotaxin-2. CONCLUSION: We conclude that CCL 20 mRNA expression in the conjunctival epithelium plays a crucial role in regulating homeostasis at the ocular surface and in exacerbation of VKC.