CD44 and RHAMM hyaluronan receptors in human ocular surface inflammation.

BACKGROUND: CD44 and RHAMM hyaluronan (HA) receptors have been studied in several systemic diseases such as osteoarthritis and cancer. However, not too much is known about their role in ocular surface disorders. The purpose of this research was to determine if CD44 and RHAMM are implicated in human ocular surface inflammation. METHODS: Upper tarsal conjunctival epithelial samples from patients with active ocular surface inflammation (n = 17) and healthy controls (n = 14) were recovered by brush cytology. Patients were evaluated by an ophthalmologist and classified in different groups according to the etiology (immune atopic diseases or immune non-atopic diseases) and inflammation intensity (mild/moderate or severe). CD44, RHAMM, and p53 mRNAs were measured using real-time PCR. RESULTS: CD44, RHAMM, and p53 mRNAs were detected in all samples. In immune atopic diseases, higher levels of CD44 and RHAMM mRNAs were present, reaching a 300 % increase for RHAMM in severe inflammation (p < 0.001). In contrast, in immune non-atopic diseases, the HA receptors were downregulated. CD44 tended to decrease up to 30 % in severe patients (p = 0.06), and RHAMM decreased 40 % in severe inflammation (p = 0.021). CONCLUSIONS: RHAMM may be implicated in severe ocular surface inflammation affecting the upper tarsal conjunctiva.