Efeito imunomodulador da saliva de Rhodnius prolixus na infecção intestinal crônica por Toxoplasma gondii em camundongos C57BL/6

Abstract

C57BL/6 mice when orally infected by T. gondii develop a massive inflammatory process that assembly to Crohn Disease. It constitutes a remarkable model to study inflammatory bowel diseases in animal models. At the moment, patients with Crohn disease deal with no accessible and effective treatment. However, the salivary constituents of hematophagous insects have been demonstrated to be a good immunomodulatory component, capable to reduce the exacerbated inflammatory process. At this study, we purpose to analyze the immunomodulatory effects of R. prolixus saliva, in an inflammatory bowel disease promoted by T. gondii. For this purpose, 3 experimental groups, containing 10 animals, were designed. The treatment was performed intraperitoneally. Control group was treated by 100μL of phosphate-buffered saline (PBS), and other ones were treated with 10μg or 30μg of salivary glandular extract (SGE), diluted in 100μL PBS. The treatment last 23 days and T. gondii infection was done by oral gavage on the second treatment day. The clinical scores and the weight were measured daily. The euthanasia was performed on the 23rd day of treatment and brain was collected for further cysts counts and the bowel was also collected for measuring the length. Blood and intestine fragments were collected for cytokines measurement by cytometric bead array. Our results show that SGE acted as a good immunomodulatory factor, bringing down the accentuated inflammatory process caused by T.gondii infection. Treatment with SGE in higher concentration decreased clinical scores of T. gondii infection. In addition, animals treated with the highest concentration of SGE lost less weight than the other two groups. The treatment provided to the grouped treated with 30μg, greater survive rates and less bowel shrinkage, although without statistical difference between the groups. The group treated with the highest SGE concentration showed significant increase of intestinal secretion of IL-10 in comparison with the group control. The cysts count indicated that no treated animals got more cysts than SGE treated ones. Thus, we conclude that the SGE acted as a good immunomodulatory factor, reducing many complications of the exacerbated immune process caused by T.gondii infection.