The biological importance of selenium led to the development of pharmacologically active organoselenium compounds. Diphenyl diselenide (PhSe)2 is an organoselenium compound whose biological activities have been poorly described. Previously, we evaluated its antioxidant and anti-inflammatory properties in an in vitro model of inflammation. We found that (PhSe)2 was able to prevent the production of reactive oxygen species, nitric oxide, the expression of iNOS, the peroxynitrite modification of proteins (nitrotyrosine immunostaining) and the antigen presentation capacity of LPS stimulated macrophages (Mph). Next, we focused on studying the ability of (PhSe)2 to modulate the alternative activation of Mph, which encompasses an upregulation of anti-inflammatory mediators. We isolated peritoneal Mph and stimulated them with dexamethasone to induce the alternative activation phenotype. We observed that activated Mph presented higher expression of IL-10, which was downregulated by (PhSe)2. Then, we examined the surface expression of mannose receptor (CD206), and found that dexamethasone treatment augmented the expression of CD206, while (PhSe)2 was able to downregulate this molecule. Finally, preliminary results indicate that (PhSe)2 decreased the ratio of IL-10/IL-12 mRNA in dexamethasone treated Mph. These findings suggest that (PhSe)2 could be used to modulate the activation of Mph.
