Adjuvant and immunostimulatory effects of a D-galactose-binding lectin from Synadenium carinatum latex (ScLL) in the mouse model of vaccination against neosporosis

Abstract

Vaccination is an important control measure for neosporosis that is caused by a coccidian parasite, Neospora caninum, leading to abortion and reproductive disorders in cattle and serious economic impacts worldwide. A D-galactose-binding lectin from Synadenium carinatum latex (ScLL) was recently described by our group with potential immunostimulatory and adjuvant effects in the leishmaniasis model. In this study, we evaluated the adjuvant effect of ScLL in immunization of mice against neosporosis. First, we investigated in vitro cytokine production by dendritic cells stimulated with Neospora lysate antigen (NLA), ScLL or both. Each treatment induced TNF-α, IL-6, IL-10 and IL-12 production in a dose-dependent manner, with synergistic effect of NLA plus ScLL. Next, four groups of C57BL/6 mice were immunized with NLA + ScLL, NLA, ScLL or PBS. The kinetics of antibody response showed a predominance of IgG and IgG1 for NLA + ScLL group, whereas IgG2a response was similar between NLA + ScLL and NLA groups. Ex vivo cytokine production by mouse spleen cells showed the highest IFN-γ/IL-10 ratio in the presence of NLA stimulation for mice immunized with NLA + ScLL and the lowest for those immunized with ScLL alone. After parasite challenge, mice immunized with NLA + ScLL or ScLL alone presented higher survival rates (70-80%) and lower brain parasite burden as compared to PBS group, but with no significant changes in morbidity and inflammation scores. In conclusion, ScLL combined with NLA was able to change the cytokine profile induced by the antigen or lectin alone for a Th1-biased immune response, resulting in high protection of mice challenged with the parasite, but with low degree of inflammation. Both features may be important to prevent congenital neosporosis, since protection and low inflammatory response are necessary events to guide towards a successful pregnancy.

Lectins from Synadenium carinatum (ScLL) and Artocarpus heterophyllus (ArtinM) Are Able to Induce Beneficial Immunomodulatory Effects in a Murine Model for Treatment of Toxoplasma gondii Infection

“…Previous in vitro and in vivo studies showed ScLL and ArtinM can be safely administered on murine models (Panunto-Castelo et al, 2001; Afonso-Cardoso et al, 2007; Cardoso et al, 2012). Furthermore, in vivo models demonstrated that ScLL presents no cytotoxic activity against J774 cells or peritoneal murine macrophages (Souza et al, 2005).…”

“…Also, the possibility to occur parasite drug resistance is an additional drawback to treat this disease based only on chemotherapy (Hui et al, 2015). Due the immunostimulatory effect of plant lectins, studies have been developed to implement of vaccination protocols using new agents to stimulate the immune system, as ScLL and ArtinM lectins extracted from plants (Cardoso et al, 2011, 2012; Souza et al, 2013). However, there is no previous study analyzing the therapeutic use of ScLL and ArtinM against T. gondii infection.…”

“…T. gondii control requires a fine-tuning induction of pro-inflammatory and anti-inflammatory cytokines, such as IL-12, IFN-γ, and IL-10 (Gazzinelli et al, 1991, 1996), but the tachyzoite stage of the parasite is able to subvert the immune response, being able, for instance, to blockade NF-κB nuclear translocation and actively interfere in the IL-12 production (Yarovinsky, 2014; Kim et al, 2016). Previous studies have been shown the ability of ScLL and ArtinM to induce the production of cytokines, when used as immunological adjuvants in vaccination protocols (Cardoso et al, 2011, 2012). In fact, when these lectins are used in murine models, they lead to the production of Th1, as well as Th2 cytokines, and these effects are important to avoid the deleterious consequences of unbalanced inflammatory cytokine production (Cardoso et al, 2011, 2012).…”

“…One group was treated with sulfadiazine (250 mg diluted in 400 mL of drinking water given to the animals for 6 days), whereas four groups were treated for 6 days, at 1-day intervals, intraperitoneally, according with the following preparations: 50 μg of ScLL; 50 μg of ScLL plus 1 μg of ArtinM; 1 μg ArtinM; or PBS only. These lectin concentrations were chosen based on previous studies (Cardoso et al, 2011, 2012). Thirty days after infection the surviving animals were euthanized and their brains collected to determine the rates of parasitism burden.…”

Effect of lectin (ScLL) on fibroblasts stimulated with LPS - an in vitro study

“…16 Despite its anti-inflammatory activity, 13,15,16 ScLL has not been evaluated in the oral cavity until the present time. The purpose of the present study was to investigate the effect of ScLL, stimulated with Porphyromonas gingivalis lipopolysaccharides (LPS), on the viability, proliferation and release of IL-10 in gingival fibroblasts.…”