Liver morphology with enphasis on bile ducts changes and survival analysis in mice submitted to multiple Schistosoma mansoni infections and chemotherapy

Numa tentativa de estar o mais próximo possível a pacientes infectados e tratados nas áreas endêmicas de esquistosomose (S. mansoni) e também para obter um período mais longo de seguimento, camundongos foram repetidamente infectado com um número baixo de cercarias. Dados de sobrevivência e variáveis histológicas tais como granuloma esquistosomótico, alteraçöes portais, necrose hepatocelular, regeneraçäo hepática, pigmento esquistosomótico, fibrose periductal e principalmente, alteraçöes dos ductos biliares foram analisados nos animais infectados tratados e näo tratados. Aa terapêutica por oxamniquina ns animais repetidamente infectados prolonga a sobrevivência de maneira singificante (Chi-quadrado 9,24, p = 0,0024), portanto confirmando resultados anteriores com um modelo semelhante mas com um período mais curto de seguimento. Ainda, a mortalidadade decresce rapidamente depois do tratamento, sugerindo uma abrupta reduçäo na gravidade das lesöes hepáticas. O fígado foi anida estudados sob o ponto de vista morfológico imunohistoquímico. Fibrose portal, com um quadro que lembra a fibrose humana do tipo Symmers está presente na fase tardia da infecçäo. As alteraçöes de ductos biliares säo muito próximas daquelas descritas na esquistosomose manônica humana. Antígeno esquistomótico foi observado e, uma célula isolada do revestimento alterado de ductos biliares. A patogênese das alteraçöes ductais e sua possível relaçäo com a infecçäo parasitária e/ou seus antígenos foi discutida

Liver morphology with emphasis on bile ducts changes and survival analysis in mice submitted to multiple Schistosoma mansoni infections and chemotherapy.

In an attempt to be as close as possible to the infected and treated patients of the endemic areas of schistosomiasis (S. mansoni) and in order to achieve a long period of follow-up, mice were repeatedly infected with a low number of cercariae. Survival data and histological variables such as schistosomal granuloma, portal changes, hepatocellular necrosis, hepatocellular regeneration, schistosomotic pigment, periductal fibrosis and chiefly bile ducts changes were analysed in the infected treated and non treated mice. Oxamniquine chemotherapy in repeatedly infected mice prolonged survival significantly when compared to non-treated animals (chi-square 9.24, p = 0.0024), thus confirming previous results with a similar experimental model but with a shorter term follow-up. Furthermore, mortality decreased rapidly after treatment suggesting an abrupt reduction in the severity of hepatic lesions. A morphological and immunohistochemical study of the liver was carried out. Portal fibrosis, with a pattern resembling human Symmers fibrosis was present at a late phase in the infected animals. Bile duct lesions were quite close to those described in human Mansonian schistosomiasis. Schistosomal antigen was observed in one isolated altered bile duct cell. The pathogenesis of the bile duct changes and its relation to the parasite infection and/or their antigens are discussed.

Schistosomiasis mansoni: immunodiagnosis aspects and search for an immunological marker related to therapeutic efficacy.

The recent findings on immunodiagnosis of schistosomiasis mansoni have shown that purified Schistosoma mansoni antigens do not provide maximum positivity. Therefore, the authors suggest the use of semi-purified antigens for diagnostic purposes. So far, no serological marker for cured patients as shown by negative stool examination was found. However, a tendency of IgG antibody titre decrease was observed, when egg antigen was used.

Effects of chemotherapy on mice submitted to multiple Schistosoma mansoni infections. A controlled randomized prospective study.

In an attempt to reproduce experimentally as close a possible the conditions found in endemic areas of mansonian schistosomiasis, a controlled trial in mice submitted to weakly infections with cercariae of S. mansoni was performed. One group (I) was not treated, the other (II) was treated with a single oral doses (100 mg/kg) of oxamniquine at the 13th week. After treatment infections were maintained bi-weekly. Mortality was significantly higher in group I (p less than 0.0001). A comparative morphological and immunoenzymatic study of the liver in the two groups was also carried out, showing a tendency to smaller granulomas and to more efficient antigen restriction in the treated group.