H1-Receptor Antagonist Olopatadine Inhibits MUC5AC Secretion by Conjunctival Goblet Cells.

The study examined the effect of H1-receptor antagonist olopatadine on the secretory function of cultured rat conjunctival goblet cells (CGC) assessed by enzyme-linked lectin assay employing UEA-I lectin. The level of mRNA for membrane-bound protein MUC16 in histaminestimulated CGC was assayed by reverse transcription PCR in the control and after preliminary application of olopatadine. The intracellular calcium concentration [Ca2+]i was measured by the calcium colorimetric method using GENMED kits. The effects of histamine and olopatadine on p-ERK level were assessed by Western blotting. Histamine up-regulated secretion of mucin MUC5AC and expression of membrane-bound protein MUC16 in CGC. In addition, it increased both [Ca2+]i and the level of phosphorylated ERK. These effects were diminished by preliminary application of olopatadine that probably acted via the ERK signaling pathway. Thus, olopatadine reduced [Ca2+]i and down-regulated ERK phosphorylation by binding to H1-receptors, thereby inhibiting secretion of mucin from histamine-stimulated CGC.