RESUMO
Neospora caninum infection is an important cause of neuromuscular disease in dogs and abortion in cattle, leading to significant economic losses in beef and dairy industries. The protective immunity against apicomplexan parasites, specifically Toxoplasma gondii and N. caninum, is typically achieved by inducing an IL-12-driven Th1 immune response. IL-12 stimulates IFN-γ production, which activates Inducible Nitric Oxide Synthase (iNOS) and promotes consequent Nitric Oxide (NO) synthesis, classically described as one of the main effector mechanisms for parasite elimination. Here, we aimed to evaluate the role played by iNOS during N. caninum infection. Our results show that N. caninum infection in C57BL/6 wild type (WT) mice induce NO production in vivo and in vitro. In agreement, iNOS deficient mice, as well as WT mice treated with iNOS inhibitor aminoguanidine, succumbed during acute infection with a dose lethal to 50 % of the WT mice, and presented significant increase in parasite load when submitted to sub-lethal infection protocols. Interestingly, the lack of control of parasite proliferation observed in iNOS-/- mice was associated with notable CNS inflammation and increased production of the main systemic proinflammatory cytokines (IL-12, IFN-γ, IL-6, TNF and IL-17A). Taken together, our findings show that iNOS plays an important role in restricting N. caninum replication, while also modulates the inflammatory process induced by the infection.
Assuntos
Coccidiose/enzimologia , Neospora/imunologia , Óxido Nítrico Sintase Tipo II/fisiologia , Animais , Coccidiose/parasitologia , Coccidiose/patologia , Interferon gama/análise , Subunidade p40 da Interleucina-12/análise , Macrófagos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Óxido Nítrico/metabolismo , Óxido Nítrico Sintase Tipo II/deficiênciaRESUMO
Interspecific interactions between Nippostrongylus brasiliensis and Eimeria nieschulzi were studied by measuring fecal lysophospholipase (LYPH) activity and relative numbers of peripheral eosinophils in rats singly or concurrently infected with one or both parasite species. Three groups of 10 rats each were inoculated with 2 X 10(3) N. brasiliensis L3 larvae and/or 5 X 10(5) E. nieschulzi sporulated oocysts. Groups 1 and 2 were infected with E. nieschulzi or N. brasiliensis, respectively. Group 3 rats were infected first with N. brasiliensis, followed on day 8 postinoculation (PI) with E. nieschulzi. Each rat served as its own control. Results revealed LYPH levels rose steadily in Group 2 rats, reaching significant peaks on days 10 and 12 PI before decreasing to control levels. Lysophospholipase activity in Groups 1 and 3, however, did not differ from control values. Group 2 rats also demonstrated peripheral eosinophilia, with peak values occurring on days 10, 12, 14, and 16 PI, while rats in Groups 1 and 3 exhibited no eosinophilia. These results demonstrate that E. nieschulzi suppressed intestinal LYPH activity and relative peripheral eosinophilia and demonstrate that a host's immune response to a single parasite may be significantly altered when a second parasite species is present.
Assuntos
Coccidiose/complicações , Eosinofilia/etiologia , Eosinófilos/enzimologia , Lisofosfolipase/metabolismo , Infecções por Nematoides/complicações , Fosfolipases/metabolismo , Animais , Coccidiose/sangue , Coccidiose/enzimologia , Fezes/enzimologia , Lisofosfolipase/sangue , Masculino , Infecções por Nematoides/sangue , Infecções por Nematoides/enzimologia , Nippostrongylus , Ratos , Organismos Livres de Patógenos EspecíficosRESUMO
Results suggest that malabsorption of amino acids which occurs during Eimeria nieschulzi and Nippostrongylus brasiliensis infections in rats is not due to impairment by intestinal inflammation of gamma-glutamyl transpeptidase activity.