Galectina-3 : seu papel na alergia ocular e potencial uso como biomarcador
Arquivos
Data
2017-03-31
Autores
Andrade, Frans Eberth Costa 
Orientadores
Gil, Cristiane Damas
Tipo
Dissertação de mestrado
Título da Revista
ISSN da Revista
Título de Volume
Resumo
A galectina-3 (Gal-3) é uma proteína ligante de beta-galactosídeos que atua na regulação da resposta inflamatória. No entanto, seu mecanismo de ação na alergia não está bem estabelecido. Objetivo: Avaliar a Gal-3 como possível biomarcador na ceratoconjuntivite alérgica em pacientes. Além disso, avaliar o papel dessa proteína na inflamação alérgica ocular utilizando modelo de conjuntivite alérgica (CA) induzida por ovalbumina (OVA) em camundongos selvagens (WT) e nocautes para Gal-3 (Gal-3-/-). Métodos: Células epiteliais da conjuntiva bulbar de pacientes controles e com CA severa, tratados ou não, foram coletadas por citologia de impressão para realização de imunocitoquímica. Para a realização do modelo experimental, nos dias 0 e 7, camundongos BALB/c machos WT e Gal-3-/- receberam injeção subcutânea de OVA (5 μg), e nos dias 14, 15 e 16, foram desafiados com 250 μg de OVA por instilação no saco conjuntival. Parte dos animais WT sensibilizados com OVA foram pré-tratados nos dias 14 a 16 com tacrolimus a 0,03% ou com dexametasona (1 mg/kg). Os animais controles receberam apenas salina. Resultados: O aumento da expressão de Gal-3 detectada no epitélio conjuntival de pacientes com ceratoconjuntivite alérgica foi modulado negativamente pelos tratamentos farmacológicos acompanhados de corticosteroide. Esses achados foram corroborados no modelo animal de CA que mostrou altos níveis de Gal-3 nas conjuntivas palpebrais, efeito revertido pela ação de dexametasona e tacrolimus. Após 24 horas do último desafio com OVA, os níveis de IgE total e anti-OVA aumentaram significantemente no sangue dos animais WT e Gal-3-/- sensibilizados por OVA em comparação aos controles, confirmando a eficácia do modelo de CA. A falta endógena de Gal-3 exacerbou a resposta inflamatória local, aumentando o influxo de eosinófilos e ativação de mastócitos. Além disso, os animais Gal-3-/- sensibilizados e desafiados pela OVA apresentaram aumento da expressão da protease 6 de mastócitos nos olhos e dos níveis de eotaxina, IL-4, IL-13 e IFN-γ no fluido lacrimal, em comparação aos animais WT com CA. Conclusão: A ausência de Gal-3 associada com o aumento da resposta inflamatória alérgica evidencia a participação dessa lectina na patogênese da alergia ocular e como relevante alvo terapêutico.
Galectin-3 (Gal-3) is a beta-galactosidase binding protein that regulates the inflammatory response. However, its mechanism of action in allergy is not well established. Aim: To evaluate Gal-3 as a possible biomarker in allergic keratoconjunctivitis in patients. In addition, to evaluate the role of this protein in ocular allergic inflammation using ovalbumin-induced allergic conjunctivitis (AC) in wild (WT) and Gal-3 null (Gal-3-/-) mice. Methods: Epithelial cells of the bulbar conjunctiva from control and with severe AC patients, treated or not, were collected by impression cytology for immunocytochemistry. To perform the experimental model, on days 0 and 7, male BALB/c WT and Gal-3-/- mice received subcutaneous injection of OVA (5 μg), and on days 14, 15 and 16 were challenged with 250 μg of OVA by instillation in the conjunctival sac. Some sensitized WT animals were pretreated on days 14 to 16 with 0.03% tacrolimus or dexamethasone (1 mg/kg). Control animals received only saline. Results: The increased Gal-3 expression detected in the conjunctival epithelium of patients with allergic keratoconjunctivitis was negatively modulated by pharmacological treatments with corticosteroids. These findings were corroborated in the AC animal model which showed high levels of Gal- 3 in the palpebral conjunctiva, an effect reverted by the action of dexamethasone and tacrolimus. After 24 hours of the last OVA challenge, total and anti-OVA IgE levels increased significantly in the blood of OVA-sensitized WT and Gal-3-/- mice compared to controls, supporting the efficacy of the AC model. The endogenous lack of Gal-3 exacerbated the local inflammatory response, increasing the influx of eosinophils and activation of mast cells. Additionally, Gal-3-/- OVA-sensitized and challenged animals exhibited increased mast cell protease 6 expression in the eyes and eotaxin, IL-4, IL- 13 and IFN-γ levels in lacrimal fluid, compared to WT animals with AC. Conclusion: The absence of Gal-3 associated with increased allergic inflammatory response demonstrates the participation of this lectin in the pathogenesis of ocular allergy and as a relevant therapeutic target.
Galectin-3 (Gal-3) is a beta-galactosidase binding protein that regulates the inflammatory response. However, its mechanism of action in allergy is not well established. Aim: To evaluate Gal-3 as a possible biomarker in allergic keratoconjunctivitis in patients. In addition, to evaluate the role of this protein in ocular allergic inflammation using ovalbumin-induced allergic conjunctivitis (AC) in wild (WT) and Gal-3 null (Gal-3-/-) mice. Methods: Epithelial cells of the bulbar conjunctiva from control and with severe AC patients, treated or not, were collected by impression cytology for immunocytochemistry. To perform the experimental model, on days 0 and 7, male BALB/c WT and Gal-3-/- mice received subcutaneous injection of OVA (5 μg), and on days 14, 15 and 16 were challenged with 250 μg of OVA by instillation in the conjunctival sac. Some sensitized WT animals were pretreated on days 14 to 16 with 0.03% tacrolimus or dexamethasone (1 mg/kg). Control animals received only saline. Results: The increased Gal-3 expression detected in the conjunctival epithelium of patients with allergic keratoconjunctivitis was negatively modulated by pharmacological treatments with corticosteroids. These findings were corroborated in the AC animal model which showed high levels of Gal- 3 in the palpebral conjunctiva, an effect reverted by the action of dexamethasone and tacrolimus. After 24 hours of the last OVA challenge, total and anti-OVA IgE levels increased significantly in the blood of OVA-sensitized WT and Gal-3-/- mice compared to controls, supporting the efficacy of the AC model. The endogenous lack of Gal-3 exacerbated the local inflammatory response, increasing the influx of eosinophils and activation of mast cells. Additionally, Gal-3-/- OVA-sensitized and challenged animals exhibited increased mast cell protease 6 expression in the eyes and eotaxin, IL-4, IL- 13 and IFN-γ levels in lacrimal fluid, compared to WT animals with AC. Conclusion: The absence of Gal-3 associated with increased allergic inflammatory response demonstrates the participation of this lectin in the pathogenesis of ocular allergy and as a relevant therapeutic target.