Repeated infections with Schistosoma mansoni and liver fibrosis in undernourished mice.
The mouse model of schistosomal periportal fibrosis (Symmers' "pipestem" fibrosis), that develops in 30-50% of the infected animals, is not reproduced in undernourished mice. Host nutritional status is likely to be a variable that may influence the outcome and progression of infection, since it interferes with the dynamics of connective tissue changes occurring in chronic hepatic schistosomiasis. Re-infections increase the occurrence of periportal liver fibrosis in well-nourished animals, but it is not known how undernourished mice would behave being repeatedly re-infected. So, 21-day-old male albino Swiss mice were individually exposed to 30 cercariae (percutaneous route) of the BH strain of Schistosoma mansoni, 4 weeks after being on a low-protein diet. Control animals were fed on a commercial balanced chow for mice. The nutritional status was evaluated by body weight gain and measurement of food intake. Mice were divided into four groups: A1 (undernourished, single infected), A2 (well-nourished, single infected), B1 (undernourished, re-infected), B2 (well-nourished, re-infected). The primary infection was performed 4 weeks after ingesting the respective diet. Re-infections started 45 days later, with exposure to 15 cercariae, at 15 day intervals. Mice were sacrificed 18 weeks after the primary exposure. The livers were submitted to morphological (gross and microscopic pathology), morphometric (percentage of fibrosis; granuloma size; volume and numerical densities) by using semi-automatic morphometry, and biochemical (quantification of collagen as hydroxyproline) studies. Worm burdens and hepatic egg counting were also recorded. Values for body weight gains were always lower in undernourished mice, the effects of re-infection being minimal on this regard. Liver and spleen weights were higher in well-nourished mice (either single infected or re-infected) and mainly related to the type of ingested diet. A greater number of re-infected well-nourished mice developed periportal fibrosis, but undernourished re-infected animals did not reproduce this lesion. The percentage of fibrosis and hepatic collagen content were higher in well-nourished mice, but differences between single infected and re-infected groups were not statistically significant.
Coutinho
Eridan M
EM
Laboratory of Immunopathology, Department of Immunology, Aggeu Magalhães Research Center, Oswaldo Cruz Foundation, Av. Moraes Rego s/n, Cidade Universitária, Recife, PE, CEP 50670-420, Brazil. eridan@cpqam.fiocruz.br
Silva
Fabiana L
FL
Barros
Andreia F
AF
Araújo
Roni E
RE
Oliveira
Sheilla A
SA
Luna
Carlos F
CF
Barbosa
Aryon A
AA
Andrade
Zilton A
ZA
D000818:Animals; D001835:Body Weight; D006651:Histocytochemistry; D006908:Hydroxyprogesterones / Q000378:metabolism; D008099:Liver / Q000469:parasitology; D008103:Liver Cirrhosis / Q000378:metabolism / Q000469:parasitology*; D008297:Male; D051379:Mice; D009929:Organ Size; D010270:Parasite Egg Count; D011502:Protein-Energy Malnutrition / Q000378:metabolism / Q000469:parasitology*; D012550:Schistosoma mansoni / Q000254:growth & development*; D012555:Schistosomiasis mansoni / Q000378:metabolism / Q000469:parasitology*; D013154:Spleen / Q000469:parasitology
D006908:Hydroxyprogesterones