Babesia bovis:lipids from virulent S2P and attenuated R1A strains trigger differential signalling and inflammatory responses in bovine macrophages

Abstract

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.

Involvement of TLR6 in the induction of COX-2, PGE 2 and IL-10 in macrophages by lipids from virulent S2P and attenuated R1A Babesia bovis strains

“…In our laboratory, we demonstrated quantitative differences in the lipid composition of two B. bovis strains with polar pathogenic effect, attenuated R1A and virulent S2P (Gimenez et al, 2010). Moreover, we determined a differential effect of total lipids from R1A (L A ) and S2P (L V ): L A induced a strong activation of bovine macrophages, whereas L V did not (Gimenez et al, 2012). In addition, similar results were obtained using murine peritoneal macrophages, although mice are not natural hosts of B. bovis.…”

Lipids From Trypanosoma cruzi Amastigotes of RA and K98 Strains Generate a Pro-inflammatory Response via TLR2/6

“…Macrophages (5 × 10 5 /well) were plated in 96-well plates and stimulated with 50 μg/ml of the different lipid extracts or 0.5% EtOH (vehicle) as negative control or 100 ng/ml LPS as positive control, in the presence of 600 pg/ml IFN-γ, for 48 h at 37°C, 5% CO 2 . NO levels were determined in cell supernatants as nitrite production using the Griess reaction and absorbance at 540 nm (Gimenez et al, 2013 ).…”

Vaccines against bovine babesiosis: where we are now and possible roads ahead

“…Vaccine formulations based on different antigen expression systems and immunomodulators can be composed to elicit host immune effectors to achieve desired protection levels. Immunomodulators, like parasite DNA and/or lipids, that have been shown to elicit innate immune responses involved in the resolution of clinical babesiosis, may be included in vaccine formulations as adjuvants (Brown et al 1998, 1999 b ; Shoda et al 2000, 2001; Gimenez et al 2010, 2013). Furthermore, multi-adjuvanted vaccines could simultaneously trigger several signalling pathways, eliciting robust immune protection, as has been proposed for other diseases (Mount et al 2013).…”

“…It has also been hypothesized that lipid composition could be a virulence determinant since lipids extracted from virulent B. bovis merozoites elicited a stronger pro-inflammatory response in mice and bovines than those of an attenuated strain, possibly allowing immune evasion of the latter (Gimenez et al 2010(Gimenez et al , 2013.…”