Characteristics of granuloma formation and liver fibrosis in murine schistosomiasis mekongi: a morphological comparison between Schistosoma mekongi and S. japonicum infection

Abstract

A histopathological study was performed to clarify the characteristics of granuloma formation and liver fibrosis in Schistosoma mekongi infection in comparison with S. japonicum infection. Mice were exposed to S. mekongi (Laotian strain) and S. japonicum (Japanese strain) cercariae, and were dissected at 6, 8, 12, 16, and 20 weeks post-exposure. In the liver, granulomas in S. mekongi infection were cellular, initially organized with foam cells, and continuously appeared in the intralobular area, while granulomas in S. japonicum infection were fibrous and did not continuously appear in the intralobular area. Portal fibrosis was not seen in S. mekongi infection, but was commonly seen in S. japonicum infection in the later weeks. Granulomas in the small intestine were seen mainly in the submucosa with foam cells in S. mekongi infection and without foam cells in S. japonicum infection. The lung granulomas contained mainly histiocytes in both S. mekongi and S. japonicum infection. The absence of portal fibrosis in S. mekongi infection allows schistosome eggs to infiltrate into the intralobular area continuously, which can be what lies behind the ultrasonographic differences; the echogenic network pattern as was seen in S. japonicum infection, has not been noted in S. mekongi infection.

A Novel Mouse Model of Schistosoma haematobium Egg-Induced Immunopathology

“…Through this strategy fibrosis in different organ systems may be compared to identify shared and organ-specific mechanisms and potential therapeutic targets. Prior work by others has definitively demonstrated that schistosome egg-induced lung, liver, and intestinal granuloma development is greatly schistosome species-dependent, with differences among S. haematobium, S. japonicum, S. mekongi , and S. mansoni [62], [63]. In addition, others have reported that hepatic- and lung-associated, S. mansoni egg granulomata develop in a highly organ-specific fashion [64].…”

The combined treatment of praziquantel with osteopontin immunoneutralization reduces liver damage inSchistosoma japonicum-infected mice

“…The granuloma dimension undoubtedly reflects the intensity of granulomatous responses that directly determine the degree of fibrosis since fibrosis is originally a tissue-repairing process to previous inflammatory injury (Shimada et al . 2010). The percentage of collagen, usually detected with Masson trichrome staining or Sirius red staining, is a common index to assess the extent of collagen deposition (Fornari et al .…”

The chronic enteropathogenic disease schistosomiasis

“…It was thought that the absence of portal fibrosis in S. mekongi infection allowed the eggs to infiltrate the interlobular areas continuously, which may have accounted for the absence of echogenic pattern on ultrasonographic evaluation (a feature noted with S. japonicum species). 35 On the other hand, in another study, the intensity of liver fibrosis among patients with S. mekongi infection was assessed by liver biopsy. Liver biopsies revealed complete disorganization of hepatic architecture with fibrous enlargement of portal tracts and some portal-portal bridging fibrosis, but there was no cirrhosis.…”