Extra-tissular Schistosoma mansoni egg granulomata in the peritoneal cavity of mice

Abstract

The presence of Schistosoma mansoni eggs surrounded by inflammatory cells were detected within the peritoneal cavity of experimentally infected mice. The histological and ultrastructural analysis revealed the predominantly macrophagic composition of these structures. The presence of epithelioid cells, macrophages in different stages of activation and the architectural pattern of the cells, characterize these structures as extra-tissular true granulomas. Granulomas much similar to those observed in the peritoneal cavity of infected mice were also detected after the intraperitoneal injection of viable eggs in non-infected mice. Collagen fibers were observed in between the inflammatory cells of granulomas obtained 10 weeks after infection and 48 hours after the injection of viable eggs into the peritoneal cavity. In later times of infection or injection the amount of collagen fibers increases resulting in a typical pattern of healed schistosoma egg granulomas. The possible influence of the immune response on the genesis of the granulomatous reaction as well as the influence of the vascularized connective tissue on this process is discussed.

Macrophage P2X7 Receptor Function Is Reduced during Schistosomiasis: Putative Role of TGF-β1

“…After egg deposition, the immune response switches to a Th2 profile that is involved in the formation of liver and colonic granulomas and fibrosis. The eggs are laid in mesenteric microcirculation and they may reach peritoneal cavity where the granulomas formed contain mainly macrophages [25]. Although granulomas are important to limit egg-derived potential cytotoxic products, macrophages isolated, for example, from hepatic granulomas, produce lipids mediators and free radicals that are potentially destructive to host tissues [26].…”

Immunological system and Schistosoma mansoni: co-evolutionary immunobiology. What is the eosinophil role in parasite-host relationship?

“…Interestingly, Santos et al (1992) have shown that schistosomal periovular granulomas in the intestines are smaller and contain less collagen than those in the liver. Due to saturation of the mucosal vessels during the infection, occurs a gradative deepening of the granulomas in the intestinal wall, decreasing the chance of the eggs to be excreted to the feces, favoring their dropping into the peritoneal cavity (Melro & Mariano 1987).…”

Encapsulated egg deposition pattern of Schistosoma japonicum in the peritoneal cavity of mice

“…In addition, following intraperitoneal or percutaneous infection, active miracidia have also been demonstrated in some encapsulated egg granulomas of S. mansoni from the washing sediments of the peritoneal cavity of mice (Fan & Pao, 1970). Melro & Mariano (1987) reported the presence of S. mansoni eggs surrounded by inflammatory cells within the peritoneal cavity of experimentally infected mice. The present experiments attempt to clarify the mechanism, development, deposition, abnormality and morphological characteristics of encapsulated egg granulomas of S. japonicum in the peritoneal cavity or on the intestinal wall of mice following intraperitoneal or percutaneous infection.…”