Caracterização imunomodulatória de proteases cisteínicas obtidas do látex de Calotropis procera em culturas de macrófagos

Abstract

Calotropis procera, is a medicinal plant known in Pernambuco as “silk-cotton”. Is laticífer plant belonging to the family Apocynaceae broadly found in the Brazilian Northeast. Current literature data show that proteins obtained from its latex harbour anti-inflammatory action. In the present study, a protein fraction obtained by ion-exchange chromatography named LPPII, which is rich in cysteine proteases, had its immunmodulatory activity evaluated in cultures of peritoneal macrophages infected by Salmonella enterica Sor. Typhimurium. Macrophages were obtained from the peritoneal cavity of Swiss mice using RPMI culture medium containing antibiotics. The cells obtained were adjusted to 1 x 106 cell/mL and incubated at 37° C and 5% CO2, in cell culture plates, and the adherent macrophages used in the assays. The bacterial quantification assays were performed in a preventive manner, where the macrophages were treated with LPPII (1 μg/ mL or 10 μg/ mL) or LPPII+IAA (10 μg / mL) (inactivated with iodoacetamide) followed by infection with S. Typhimurium (1 x 108 CFU / mL), and in a curative manner, where macrophages were first infected with S. typhimurium (1 x 108 CFU / mL) followed by treatment with LPPII (1 μg/ mL or 10 μg/ mL) or LPPII+IAA (10 μg/ ml). The cell viability assay was performed curatively with macrophages infected with S. Typhimurium (1 x 108 CFU / ml). For IL1β, TNF, IL-6, iNOS and TLR-4 cytokine gene expression assays, macrophages were only treated with LPPII (1 μg/ mL or 10 μg/ mL) or LP+IAA (10 μg / mL), or bacterial LPS stimulation, followed by curative or preventative treatments with LPPII (1 μg/ mL or 10 μg/ mL) or LP+IAA (10 μg/ mL). The results show that macrophages infected with a S. Typhimurium C5 and treated with LPPII in a preventative or curative manner, reduced the number of viable bacteria in the intracellular environment. In this case, macrophages treated preventively with LPPII 10 μg/ mL, showed a significant decrease (p <0.05) in the amount of intracellular bacteria when compared to the control, macrophages without LPPII treatment. In the curative form, significant decrease of intracellular S. Typhimurium was observed in LPPII1μg/ mL-treated macrophages compared to control cells, without LPPII treatment. On the other hand, the groups treated with LPPII+IAA had a greater number of intracellular bacteria, suggesting the action of cysteine proteases on the observed antimicrobial effect. Curative treatment with LPPII also increased the viability of infected macrophages relative to the untreated control groups. Thus, groups treated with LPPII1μg/ mL obtained viability 14.74% greater than the control group without treatment, whereas macrophages treated with LPPII10μg/ mL obtained 24.11%. Groups of macrophages stimulated with LPS and then treated with LPPII had a reduction in the gene expression of the inflammatory cytokines TNF, IL1-β and IL-6, in addition to Toll-like receptor 4. Taken together, we found that LPPII obtained from latex of C. procera presents biomolecules with immunomodulatory activity beneficial to the control of S. Typhimurium infections.