Diquafosol tetrasodium elicits total cholesterol release from rabbit meibomian gland cells via P2Y2 purinergic receptor signalling

Abstract

Diquafosol tetrasodium (DQS), a purinergic P2Y2 receptor agonist, stimulates secretion of both water and mucins from the conjunctiva into tears. Hence, DQS-containing eye drops have been approved as a therapeutic option for dry eye disease in some Asian countries, including Japan. Recent clinical reports state that instilling DQS-containing eye drops significantly increases the lipid layer thickness in tears. Therefore, we examined this compound’s direct actions on holocrine lipid-secreting meibomian gland cells and their function. Isolated meibomian gland cells (meibocytes) were procured from rabbits and cultivated in serum-free culture medium. Differentiated meibocytes with pioglitazone were used for the subsequent experiments. Intracellular Ca2+ signalling of the cells was dramatically elevated with DQS addition in a dose-dependent manner. This DQS-induced elevation was almost completely cancelled by the coexistence of the selective P2Y2 receptor antagonist AR-C118925XX. DQS treatment also facilitated total cholesterol (TC) release from cells into the medium. This effect of DQS on TC was suppressed significantly by the intracellular Ca2+ chelator BAPTA-AM as well as by AR-C118925XX. DNA fragmentation analysis revealed that DQS may have enhanced the apoptotic DNA fragmentation caused spontaneously by cells. Thus, DQS could stimulate meibocytes to release lipids through the P2Y2 receptor and possibly facilitate holocrine cell maturation.

Efficacy of Artificial Tears Based on an Extract of Artemia salina Containing Dinucleotides in a Rabbit Dry Eye Model

“…To our knowledge, only the previous study of our research performed in healthy rabbits evaluated tear break-up time after a treatment containing dinucleotides, where there were no changes with the extract of 4% Artemia salina [ 30 ]. On the other hand, different studies demonstrated that the activation of the P2Y 2 receptor by topical instillation of Up 4 U stimulates the production of mucins and lipids in the Goblet cells and Meibomian glands, respectively [ 15 , 16 , 34 , 35 ]. Considering that mucins and lipids are the responsible components for tear film stability [ 36 ], the possibility that the artificial tears with Artemia salina improves this stability in future clinical studies should not be discarded based on the hypothesis that the Gp4G present in the crustacean could act as an agonist of P2Y 2 receptor.…”

“…On the ocular surface, P2Y 2 receptor has been described in the cornea, conjunctiva, and lacrimal gland [ 10 ]. The activation of P2Y 2 receptor via topical instillation of diadenosine tetraphosphate (Ap 4 A) and diuridine tetraphosphate (Up 4 U) demonstrated its capability to stimulate aqueous [ 11 , 12 , 13 , 14 ], mucinous [ 15 ], and lipidic [ 16 ] components of tears, as well as to accelerate corneal re-epithelization [ 15 , 17 , 18 ]. Additionally, the instillation of these compounds increases the corneal permeability [ 19 , 20 ] and the levels of both lysozyme [ 21 ] and lactoferrin [ 22 ] in tears.…”

Ocular Surface Ion-Channels Are Closely Related to Dry Eye: Key Research Focus on Innovative Drugs for Dry Eye

“…It has achieved positive results in basic and clinical research in the field of DE. The diquafosol tetrasodium (DQS) was found to stimulate meibocytes to release lipids through the P2Y2 receptor and possibly facilitate holocrine secretion in isolated rabbit Meibomian gland cells ( 96 ). Diquafosol significantly reduced the levels of reactive oxygen species, apoptosis, and inflammation in corneal cells caused by DE in in vivo and in vitro DE models ( 97 ).…”

Combination therapy with 3% diquafosol tetrasodium ophthalmic solution and sodium hyaluronate: an effective therapy for patients with dry eye after femtosecond laser-assisted in situ keratomileusis

“…As recently reported, 3% diquafosol tetrasodium ophthalmic solution (Diquas ® , DQS), a P2Y2 receptor agonist that acts on goblet cells, corneal and conjunctival epithelium, and meibomian glands, can promote tear fluid, mucin, and lipid secretion and help epithelium repair ( 12 , 13 ). Several clinical trials have shown that DQS significantly reduces corneal and conjunctival staining, prolongs tear breakup time (TBUT), increases Schirmer test score and improves subjective symptoms in patients with dry eye ( 14 – 17 ).…”