Inflammation induced by phytomodulatory proteins from the latex of Calotropis procera (Asclepiadaceae) protects against Salmonella infection in a murine model of typhoid fever.

OBJECTIVE AND DESIGN

Laticifer proteins (LP) of Calotropis procera were fractionated by ion-exchange chromatography, and the influence of a sub-fraction (LP(PI)) on the inflammatory response of Swiss mice challenged by Salmonella enterica Ser. Typhimurium was investigated.

METHODS

Mice (n = 10) received LP(PI) (30 or 60 mg/kg) in a single inoculum by the intraperitoneal route 24 h before infection. To investigate the relevance of the proteolytic activity, three additional groups were included: the first one received heat-treated LP (30 mg/kg-30 min at 100 °C), the second received LP (30 mg/kg) inactivated by iodoacetamide, and a control group received only phosphate-buffered saline (PBS).

RESULTS

The survival rate reached 100 % in mice treated with LP(PI) and was also observed with the other treatment, whereas the PBS group died 1-3 days after infection. The neutrophil infiltration into the peritoneal cavity of pretreated mice was enhanced and accompanied by high bacterial clearance from the bloodstream. Tumor necrosis factor-alpha mRNA transcripts, but not interferon-gamma, were detected early in spleen cells of pretreated mice after infection; however, the nitric oxide contents in the bloodstream were decreased in comparison to the PBS group.

CONCLUSIONS

The inflammatory stimulus of C. procera proteins increased phagocytosis and balanced the nitric oxide release in the bloodstream, preventing septic shock induced by Salmonella infection.