Avaliação da atividade antiinflamatória e toxicidade aguda e sub-crônica de análogos de talidomida contendo diaminas e estrutura ftalimídica aberta

Abstract

Thalidomide exhibits anti-inflammatory and immunomodulatory effects, improving clinical symptoms in a variety of diseases, including erythema nodosum leprosum, Crohn disease, rheumatoid arthritis, cancer and other vascular and inflammatory diseases. In previous study from our laboratory it has been shown that thalidomide analogues containing diamines and open phthalimide structure, showed high inhibitory in vitro activity on key molecules such as TNF-a, IL-12, IFN-g, IL-6, CXCL9, CXCL10 and CD80. In contrast, some compounds induced an increase in IL-10 production. In this study, the anti-inflammatory activity of two thalidomide analogues (GI-16 and SC-15) were evaluated in vivo using the carrageenan-induced paw inflammation on BALB/c mouse and the LPS-induced lung inflammation in C57Bl/6 mice. In addition, the acute and sub-chronic toxicity of the compounds on Wistar rats were evaluated. The treatment with both GI-16 (10mg/kg and 50mg/kg) and SC-15 (50mg/kg) reduced significantly (53-77%) the paw oedema over 24h evoked by subplantar injection of 2% carrageenan. GI-16 (20mg/kg and 50mg/kg) and SC-15 (50mg/kg) greatly inhibited LPS-induced TNF-a (around 34%) and IL-6 (66- 89%) in lung homogenate. In contrast, thalidomide (50mg/kg) and SC-15 (50mg/kg) enhanced IL-10 (p<0,05). As expected, thalidomide and the reference drug, dexamethasone, caused significant inhibition of both carrageenan-induced oedema and of TNF-a and IL-6 production 24 h after intratracheal administration of LPS (200ug/ml). Histopathological analysis has shown that GI-16 treatment induced reduction in LPS–induced inflammation characterized by discrete capillary congestion. In contrast, animals treated with SC-15, showed moderate to intense inflammatory infiltrate, thickening of alveolar wall and vascular congestion at 20mg/kg, and reduced inflammation at 50mg/kg. Female and male Wistar rats administered with GI-16 and SC-15 (20mg/kg) did not develop any clinical signs of acute toxicity (single dose) or sub-chronic toxicity (every other day for 28 days) either immediately or during the posttreatment period. No mortality occurred in both, control and treated animals either immediately or during the treatment period. Body weight gain over time 10 was similar in all groups. There was not significant alteration in biochemical or hematological parameters. Sections of heart, liver and kidneys tissues of the studied rats showed no pathological alterations under light microscopy. These results strongly reinforce the anti-inflammatory effects of GI-16 and SC-15, which make them very attractive drug candidates to treat a broad range of inflammatory diseases.