Mast cells profiles and heterogeneity in lipopolysaccharide-induced uveitis model

Backgound: Uveitis is an important inflammation of the middle tunica of the eye which can lead to blindness. Mast cells (MCs) participate in the development of the inflammatory process by attracting other cell types. Methods: The MCs profile was evaluated in the endotoxin-induced uveitis model (EIU), in the acute (24 hours) and late (48 hours) phases of the inflammatory process. EIU was induced by inoculation of lipopolysaccharide, subcutaneously, into the paw of the rats. After 24 and 48 hours of the induction, the eyes were enucleated for paraffin inclusion and histopathological studies of MCs in the anterior chamber of the eye. MCs were morphologically evaluated using Toluidine blue dye, their histamine accumulation was analyzed by Alcian blue and Safranin-O method, and the presence of tryptase and chymase by immunohistochemistry. Results: The results showed larger amount of total and degranulated MCs, as well as Alcian blue and Safranin positive MCs in the acute phase of EIU, especially in the ciliary body. Few tryptase positive MCs were observed in acute and late phases of EIU, but numerous chymase positive MCs were found in the 24-hour group. Conclusions: The data highlight the MC modulation during EIU and indicate these cells closely linked to the inflammatory process in uveitis.