Exploring possibilities for an alternative approach in experimental schistosomiasis mansoni: the peritoneal cavity of mice.

The schistosome oviposition and granuloma constitution in the peritoneal cavity of AKR/J mice were evaluated. Groups of mice intraperitoneally infected with cercariae of Schistosoma mansoni were weekly euthanized during the acute (56 to 84 days post-infection (DPI)) and chronic (147 to 175 DPI) phase of infection. Schistosome developmental stages obtained via peritoneal lavage and perfusion of the portal system were inspected, counted and fixed, and peritoneal granulomata were then processed for histology. The morphological characterization and quantitative analysis of peritoneal schistosome eggs and granulomata were for the first time performed, such as the demonstration of the viability of miracidia obtained there from. Eutopic and ectopic mature schistosomes and normal pattern of worm oviposition were observed in all periods studied. However, the size of schistosome eggs from peritoneal cavity was smaller than observed for eggs laid by female worms from the portal system. The numbers of S. mansoni eggs and/or granulomata recovered from the peritoneal cavity was higher in chronic than acute infection, while the mean diameter of peritoneal chronic granulomata was smaller than for peritoneal acute granulomata. The constitution and evolution of these cellular reactions at histology were similar to that of hepatic granuloma, and peritoneal granulomata were subject to the host immunomodulation. In addition to the standardization of this experimental approach, which allows the obtaining of free schistosomal granulomata from peritoneal cavity of AKR/J mice, the potential use of these granulomata in ex vivo and in vivo studies is discussed.