Physalin B inhibits Trypanosoma cruzi infection in the gut of Rhodnius prolixus by affecting the immune system and microbiota

Abstract

Physalin B is a natural secosteroidal, extracted from the Solanaceae plant, Physalis angulata, and it presents immune-modulator effects on the bloodsucking bug, Rhodnius prolixus. In this work, R. prolixus was treated with physalin B at a concentration of 1 mg/ml of blood meal (oral application), or 20 ng/insect (applied topically) or 57 ng/cm(2) of filter paper (contact treatment), and infected with Trypanosoma cruzi Dm28c clone (2×10(6) epimastigotes/insect). The three types of applications significantly decreased the number of T. cruzi Dm28c in the gut comparing with the non-treated infected insects (controls). All groups of infected insects treated with physalin B had higher numbers of bacterial microbiota in the gut than the non-treated controls infected with T. cruzi. We observed that the infected physalin B insects with topical and contact treatments had a lower antibacterial activity in the gut when compared with control infected insects. Furthermore, infected insects with the physalin B oral treatment produced higher levels of nitrite and nitrate in the gut than control infected insects. These results demonstrate that physalin B decreases the T. cruzi transmission by inhibiting the parasite development in the insect vector R. prolixus. Herein the importance of physalin B modulation on the immune system and microbiota population in terms of parasite development and transmission are discussed.

Triflumuron Effects on the Physiology and Reproduction ofRhodnius prolixusAdult Females

“…This could be a result of TFM excretion or detoxification. It has been shown that gut microbes have an important role in the detoxification of ingested xenobiotics [63], and it has been described that, after a blood meal, there is a huge increase in the bacterial population in R. prolixus gut contents [64, 65]. However, our data suggest that oral treatment does not affect diuresis (Figures 1 and 2), so the elimination of TFM in urine after oral treatment should also be considered.…”

Immune modulation enables a specialist insect to benefit from antibacterial withanolides in its host plant

“…Since withanolides possess antibacterial properties1926, they potentially affect the composition of larval gut microbiota. For example, in Rhodnius prolixus, a blood-sucking bug and an important vector of the Chagas disease, withanolide treatment resulted in higher numbers of bacterial microbiota but also in a lower antibacterial activity45. The fact that we found an increase in the relative weight gain in H. subflexa larvae feeding on diet containing withanolides suggests that withanolides have a nutritional or digestive microbial-driven effect, which reached its full potential at a concentration of 100 μg of withanolides in our experiments (Fig.…”

Physalins B and F,seco-steroids isolated fromPhysalis angulataL., strongly inhibit proliferation, ultrastructure and infectivity ofTrypanosoma cruzi

“…Additionally, Castro and co-workers corroborated these findings, showing that physalin B inhibits T. cruzi development in the gut of triatomines (Castro et al . 2009, 2012). However, the anti- T. cruzi activity of physalins against the infective forms in humans (bloodstream trypomastigotes and amastigotes) have not been described.…”

“…2008; Castro et al . 2009, 2012). The findings suggest physalins are useful compounds for vector-borne transmission control.…”