Increased expression of the type 1 growth factor receptor family in the conjunctival epithelium of patients with keratoconjunctivitis sicca.

ABSTRACT

PURPOSE: To investigate the expression of type 1 growth factor receptors (epidermal growth factor receptor, ErbB2, and ErbB3) in the conjunctival epithelium of patients with keratoconjunctivitis sicca. METHODS: Immunofluorescent staining and Western blotting were performed to grade the level of expression of the epidermal growth factor receptor ErbB2, and ErbB3 in conjunctival epithelial impression cytologies taken from both eyes of seven normal subjects and 22 patients with keratoconjunctivitis sicca. RESULTS: Epidermal growth factor receptor staining was observed in a greater percentage of keratoconjunctivitis sicca than normal samples (P <.05). ErbB2 and ErB3 staining in the apical conjunctival epithelium was observed in both groups, but stronger ErbB2 and ErbB3 staining was noted in keratoconjunctivitis sicca conjunctival samples (P <.05). The relative levels of expression of these receptor proteins on immunoblots were consistent with immunofluorescent staining. On immunoblots, epidermal growth factor receptor protein was detected in 50% of keratoconjunctivitis sicca samples, but none of the normal samples (P <.025). The expression of ErbB2 and ErbB3 on immunoblots was also greater in the keratoconjunctivitis sicca samples (P <.05). Immunofluorescent staining scores for these receptors were correlated with conjunctival lissamine green staining scores (r =. 574, P <.01 for epidermal growth factor receptor; r =.620, P <.0025 for ErbB2; r =.502, P <.025 for ErbB3) and with corneal fluorescein staining (r =.409, P <.05 for ErbB2; r =.588, P <.005 for ErbB3). CONCLUSION: The expression of the type 1 growth factor receptors is significantly greater in the conjunctival epithelium of eyes with keratoconjunctivitis sicca than normal eyes. The increased expression of these receptors was positively correlated with ocular surface dye staining. The increased expression of these receptors may contribute to the abnormal growth and differentiation of the conjunctival epithelium that occurs in keratoconjunctivitis sicca.