Abstract
Purpose: :
We previously reported that PGE2 levels were elevated and PGD2 levels were decreased in tears of DE patients compared with normal controls. In this study we investigated the expression levels of prostaglandins (PGs) and their synthesizing activities in DE induced mice.
Methods: :
DE was induced in the mice by placing them in a controlled environment chamber. To achieve maximum ocular surface dryness, in addition to the controlled environment chamber, the mice were given subcutaneous injections of scopolamine hydrobromide. During the DE induction, the mice were sacrificed at 3 days and 7 days after induction. The lids, eyeballs, and lacrimal glands were collected. Half of the tissue was used for immunohistostaining, and the other half for qRT-PCR. We used COX-1, COX-2, PGES and PGDS antibodies for IHC, and quantified levels of m-RNA of these PG synthesizing enzymes.
Results: :
COX-2 mRNA levels were significantly higher in ocular surface tissue (including the cornea and conjunctiva) and lacrimal glands. PGES mRNA was significantly higher in ocular surface tissue, whereas PGDS mRNA was decreased. IHC staining showed that COX-2 expression was elevated in DE mouse lacrimal glands, meibomian glands, cornea and conjunctivas compared with normal controls. PGES expression was found in periductal infiltrated cells of the lacrimal gland and conjunctival epithelium. PGDS expression was decreased in the meibomian glands and increased in focal conjunctival epithelium.
Conclusions: :
Our data shows that changes in PG levels in tears of DE patients were supported by changes of PG synthesizing activities measured in dry eye induced mouse model. This suggests that PGE2, a known nociceptive regulating molecule, could be a new therapeutic target for DE disease.
Keywords: ocular irritants • immunohistochemistry • pathobiology