Study of expression of antiinflammatory protein galectin-1 and its mechanism of action in an experimental model of allergic Conjunctivitis

Abstract

Allergic conjunctivitis (AC) is an immune complex disease involving mast cell degranulation in the conjunctiva and the release of inflammatory mediators and cytokines that cause the infiltration of inflammatory cells in this tissue. This inflammation is the main contributing factor to many ocular disorders and may lead to decreased visual acuity and even blindness. Generally, in the treatment of intraocular inflammation, glucocorticoids are administered and their side effects stimulate the search for new therapeutic strategies. Among the anti-inflammatory mediators highlights the endogenous protein galectin-1 (Gal-1) capable of controlling the process f transmigration of leukocytes, cytokine release, and degranulation of mast cells, contributing to the homeostasis of the inflammatory reaction. However, the expression of Gal-1 in normal and inflamed ocular tissues has been little studied. Using an experimental model of AC, we will study the expression and mechanism of action of endogenous Gal-1 in ocular tissues of mice. Animals will be immunized (days 0 and 7) s.c. with ovalbumin (OVA; 5 µg) and on days 14, 15, and 16, they will receive direct instillation into the conjunctival sac of OVA (250 µg) in 10 µl of PBS. Another group of sensitized animals will be pretreated i.p. on days 14-16 with Gal-1 recombinant protein (rGal-1; 0.3 µg per animal) or dexamethasone (0.5 mg/kg), diluted in 0.1 mL of PBS. The Control group will receive only PBS. After 4 and 24 hours of the last challenge with OVA, animals will be anesthetized, underwent cardiac puncture to collect blood, and, subsequently, killed by cervical dislocation for enucleation of the eyes and the dissection of spleen and lymph nodes. The studies will be conducted through: histopathological and quantitative analysis of inflammatory cells in ocular tissues and blood; levels of IgE and cytokines IL-10 and IFN-³ in the blood; and immunohistochemistry and Western blotting to detect the endogenous expression of Gal-1 in homogenates of ocular tissues, spleen, and lymph nodes. The results may indicate the mechanism of action of Gal-1 in ocular allergic inflammatory processes and provide new therapeutic options.(AU)