Identification of Cannabinoid Receptors in Cells of the Ocular.

AM SUBURO, V TORBIDONI, M IRIBARNE, V RETTORI, D SINHA, A BERRA.

Ft. Lauderdale, Florida, United States.

Congreso; Association for Research in Vision and Ophthalmology, Annual meeting, 2006,; 2006

Association for Research in Vision and Ophthalmology.

Purpose: Conjunctival epithelium is not only a mechanical barrier, but it is also an active participant in the regulation of allergic inflammation. An immunomodulatory role for the endocannabinoid system has been proposed and cannabinoid receptors, CB1 and CB2, seem to be involved in mucosal immunity. Therefore, we have evaluated the presence of these receptors in cells of the ocular surface. Methods: Eyes were enucleated from deeply anesthetized BALB–c mice and cryosections were obtained both after 4% paraformaldehyde perfusion or from fresh frozen material. A cell line derived from normal human conjunctiva (IOBA–NHC) was also used. Cryosections and monolayers seeded on glass coverslips were incubated with rabbit antibodies against CB–1 and CB–2. Specimens were developed using an immunoenzymatic procedure with nickel enhancement. Results: Strong immunostaining of the conjunctiva and cornea was obtained with two different antisera against CB–1 and two different antisera against CB–2. Immunoreactivities were uniformly distributed over the eye surface. Both CB–1 and CB–2 immunoreactivities were also observed in IOBA–NHC monolayers. A granulate distribution of immunoreactivity was observed, suggesting the presence of receptors in cytoplasmic vesicles and membrane domains. Conclusions: The two cannabinoid receptors, CB1 and CB2, were detected in corneal and conjunctival epithelia using antibodies directed to different epitopes of each receptor. They were also present in a human conjunctiva–derived cell line. Although further studies are required to evaluate the functionality of these receptors, it is postulated that CB–1 and CB–2 would be involved in epithelial maintenance and protection, including immunological control of the ocular surface.