Chemokine Receptor CCR5 Expression in Conjunctival Epithelium of Patients With Dry Eye Syndrome

Abstract

Objective To characterize chemokine receptor CCR5 expression on the conjunctival epithelium in dry eye syndromes.

Methods Conjunctival impression cytology samples were obtained from normal subjects (n = 15) and patients with dry eye syndrome (n = 45). Cells were harvested from impression cytology samples, and flow cytometry was performed to quantitatively analyze the cell surface expression of chemokine receptor CCR5. Characterization of CCR5-positive cells was done by 2-color flow cytometry using fluorescein-conjugated anti-CCR5 and phycoerythrin-conjugated anti-CD45 antibodies (where CD45 is a marker for bone marrow–derived cells). To study CCR5 messenger RNA transcripts, real-time polymerase chain reaction was done on RNA isolated from the impression cytology samples of normal subjects (n = 5) and patients with dry eye syndrome (n = 14).

Results We found significant up-regulation in cell surface expression of CCR5 in patients with both aqueous tear–deficient and evaporative forms of dry eye syndrome (P<.001). The real-time polymerase chain reaction results (for messenger RNA) corroborated the flow cytometry data (for protein). The majority of the cells expressing CCR5 were non–bone marrow–derived resident epithelial cells of the conjunctiva.

Conclusion Our findings suggest that CCR5 up-regulation is significantly associated with dry eye syndrome–associated ocular surface disease.