Comparison of mucin levels at the ocular surface of postmenopausal women with and without a history of dry eye.

Abstract

To determine if levels of the glycocalyx membrane mucins, MUC1 and MUC16, and the secreted goblet cell mucin MUC5AC are altered in conjunctival cells and tears of postmenopausal women presenting with a history of non-Sjögren dry eye and if mucin levels correlate with dry eye clinical diagnostic data. Eighty-four postmenopausal women with a history of non-Sjögren dry eye and 30 normal subjects were recruited for this study. Impression cytology samples were collected for mucin messenger RNA (mRNA) and protein analysis. Tears were collected for mucin protein assay. Quantitative polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay were used to quantitate MUC1, MUC16, and MUC5AC levels. Postmenopausal women with a history of dry eye displayed significantly increased MUC1 mRNA expression and cellular protein compared with normal subjects (P < 0.001 and P < 0.01, respectively). Similarly, cellular MUC16 protein levels were significantly higher (P < 0.001). Mucin levels were found to be correlated with the clinical characterization of the subjects, including staining and symptoms. Although cellular MUC5AC protein levels were increased in symptomatic subjects, the increase did not reach statistical significance. Elevation in MUC1 and MUC16 mRNA and/or protein levels in postmenopausal women with non-Sjögren dry eye with a history of dry eye may be a compensatory response to irritation and inflammation associated with the disease. Understanding the pattern of mucin expression associated with the dry eye pathology may clarify factors involved in the progression of the disease and enhance the development of targeted therapies.