RESUMO
The filarial parasite Setaria digitata is unique in having two ubiquinones, Q(6) and Q(8), in the adult stage, in place of one, namely Q(10), in the host. However, the microfilariae (mf) as well as the electron transfer complexes from adult mitochondria have been recently shown to contain only Q(6). The second ubiquinone Q(8) is present only in the adult and absent in the mf. Though both Q(6) and Q(8) are present in the adult stage in the ratio 65:35, there is an enrichment of Q(8) in the excretory and secretory (ES) materials released into the incubation medium. The Q(6) level in the ES materials decreased further when the adult parasite was incubated in presence of diethylcarbamazine, a drug which inhibits the release of mf, indicating that the Q(6) detected in ES may be of mf origin. The preferential release of Q(8) into the external medium and its presence in the adult stage without any apparent role in the electron transport process strongly indicate an antioxidant role for the molecule. The inhibitory effect of Q(8) on lipid peroxidation and the presence of other components such as catalase and superoxide dismutase shown to be present in ES materials in earlier studies help the filarial parasite survive for longer periods by overcoming the oxidative reactions of the host generated against it.
Assuntos
Antioxidantes/metabolismo , Setaria (Nematoide)/metabolismo , Ubiquinona/metabolismo , Animais , Catalase/metabolismo , Bovinos , Cromatografia Líquida de Alta Pressão , Dietilcarbamazina/farmacologia , Transporte de Elétrons , Filaricidas/farmacologia , Hidroquinonas/metabolismo , Peroxidação de Lipídeos , Inibidores de Lipoxigenase/farmacologia , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Setaria (Nematoide)/citologia , Setaria (Nematoide)/efeitos dos fármacos , Superóxido Dismutase/metabolismo , Substâncias Reativas com Ácido Tiobarbitúrico/metabolismoRESUMO
ES materials released along with the release of mf showed immunosuppression as evidenced by a decrease in T lymphocyte levels in the immunised animals. Lipid fractions of the mf associated ES materials and protein fractions of the detergent soluble materials were found to cause suppression of immune response in the host. Further study revealed that the suppression associated with the lipid fractions is actually the end result and that mf associated ES materials is actually a mixture of immunosuppressive and immunopotentiating components and the release of the components is most likely regulated.
