RESUMO
The intra-erythrocytic protozoan Babesia bovis is an economically important pathogen that causes an acute and often fatal infection in adult cattle. Babesiosis limitation depends on the early activation of macrophages, essential cells of the host innate immunity, which can generate an inflammatory response mediated by cytokines and nitric oxide (NO). Herein, we demonstrate in bovine macrophages that lipids from B. bovis attenuated R1A strain (LA) produced a stronger NO release, an early TNFα mRNA induction and 2-fold higher IL-12p35 mRNA levels compared to the lipids of virulent S2P strain (LV). Neither LA nor LV induced anti-inflammatory IL-10. Regarding signalling pathways, we here report that LA induced a significant phosphorylation of p38 and extracellular signal-regulated kinases 1 and 2 (ERK1/2) whereas LV only induced a reduced activation of ERK1/2. Besides, NF-κB was activated by LA and LV, but LA produced an early degradation of the inhibitor IκB. Interestingly, LV and the majority of its lipid fractions, exerted a significant inhibition of concanavalin A-induced peripheral blood mononuclear cell proliferation with respect to LA and its corresponding lipid fractions. In addition, we determined that animals infected with R1A developed a higher increase in IgM anti-phosphatidylcholine than those inoculated with S2P. Collectively, S2P lipids generated a decreased inflammatory response contributing to the evasion of innate immunity. Moreover, since R1A lipids induced a pro-inflammatory profile, we propose these molecules as good candidates for immunoprophylactic strategies against babesiosis.
Assuntos
Babesia bovis/imunologia , Babesiose/veterinária , Interações Hospedeiro-Parasita/imunologia , Lipídeos/imunologia , Macrófagos/imunologia , Transdução de Sinais , Animais , Anti-Inflamatórios/farmacologia , Anticorpos Antifosfolipídeos/sangue , Babesia bovis/química , Babesia bovis/patogenicidade , Babesiose/imunologia , Babesiose/parasitologia , Bovinos , Doenças dos Bovinos/imunologia , Doenças dos Bovinos/parasitologia , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Citocinas/metabolismo , Leucócitos Mononucleares/citologia , Lipídeos/farmacologia , Macrófagos/efeitos dos fármacos , Macrófagos/parasitologiaRESUMO
Babesia bovis is an intraerythrocytic apicomplexan protozoa of cattle that causes an acute infection with parasite persistence. Babesiosis limitation depends on macrophages, essential effector cells of the host innate defense, which generate inflammatory cytokines and nitric oxide. Herein, we report quantitative differences in the lipid composition of merozoites from two B. bovis strains with polar behaviour: attenuated R1A and virulent S2P. Accordingly, we observed a distinct inflammatory response induced by the total lipids of R1A (L(A)) and S2P (L(V)) in murine peritoneal macrophages. L(A) and particularly its fractions phosphatidic acid and phosphatidylserine+phosphatidylinositol (PS+PI), produced a strong activation of these cells with lipid body formation, cyclooxygenase-2 expression and pro-inflammatory TNFalpha, IL-6 and KC secretion. Although L(V) did not activate these cells, the corresponding PS+PI fraction induced TNFalpha, IL-6 and KC release. Therefore, these facts might be suggesting the presence of an inhibitor in L(V). Furthermore, the employment of wild type and toll like receptor 2 knockout (TLR2KO) mice allowed us to demonstrate that macrophage activation by the stimulating lipid fractions was mediated through TLR2. Interestingly, only L(A) activated the extracellular signal-regulated kinases 1 and 2 (ERK1/2). Inhibitory studies employing UO126, indicated that the ERK pathway was required for TNFalpha, IL-6 and KC release. In conclusion, the absence of inflammatory response observed with the lipids of S2P virulent strain could constitute an evasion mechanism of the innate immune response enabling parasite establishment in the host.
Assuntos
Babesia bovis/imunologia , Babesia bovis/patogenicidade , Lipídeos/farmacologia , Ativação de Macrófagos/efeitos dos fármacos , Receptor 2 Toll-Like/imunologia , Animais , Babesia bovis/efeitos dos fármacos , Ciclo-Oxigenase 2/metabolismo , Citocinas/metabolismo , Dinoprostona/biossíntese , Indução Enzimática/efeitos dos fármacos , MAP Quinases Reguladas por Sinal Extracelular/metabolismo , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Macrófagos/efeitos dos fármacos , Macrófagos/enzimologia , Macrófagos/metabolismo , Macrófagos/parasitologia , Merozoítos/efeitos dos fármacos , Merozoítos/imunologia , Camundongos , Camundongos Endogâmicos C57BL , Virulência/efeitos dos fármacosRESUMO
Infection with a myotropic Trypanosoma cruzi clone induces maternal fertility failure. In the current work, we evaluated whether reduction of maternal parasitaemia before mating has beneficial effects on pregnancy outcome. Female mice were subjected to benznidazole (Bz) treatment after infection. On day 30 of therapy, mating was assessed and pregnancy outcome was determined on day 14 of gestation. Fetal resorptions diminished in T. cruzi-infected Bz-treated mice compared with T. cruzi-infected untreated mice. This was in agreement with the reduction in the blood/solid tissue parasite load and with the percentage of necrotic foci in placental samples from T. cruzi-infected Bz-treated females. To study eventual changes in the immune homeostasis of T. cruzi-infected Bz-treated mice, activation of the immune system was evaluated at the end of Bz therapy and before mating. We found specific IgG1 reduction resulting in a predominance of specific IgG2a, reduced numbers of CD69+ CD4+ cells and diminished frequency and numbers of CD44+ T cells. Concanavalin A-stimulated splenocytes from T. cruzi-infected Bz-treated mice produced higher amounts of IFN-gamma than T. cruzi-infected untreated mice. These results indicate that reduction of maternal parasite load improves pregnancy outcome. These findings correlate with a favourable modulation of the immune response.