Worm load and septal fibrosis of the liver in Capillaria hepatica-infected rats

Abstract

Inocula, varying from 15 to 1,000 embryonated Capillaria hepatica eggs, were administered to young adult rats by gastric tube, in an attempt to investigate the influence of worm load in the production of septal fibrosis of the liver. Low doses of 15, 30 or 50 eggs were sufficient to produce septal fibrosis, but it appeared with variable degrees of intensity and always with focal distribution. Septal fibrosis became diffuse, progressive with time, and already well developed 40 days after infection, when 100 eggs or more were administered. However, higher inocula (200, 500 and 1,000 eggs) did not intensify septal fibrosis, although the number of parasitic focal lesions proportionally augmented

Experimental hepatic fibrosis due to Capillaria hepatica infection (differential features presented by rats and mice)

“…But, the most peculiar aspect is the formation of septal fibrosis in rats infected with C. hepatica. It appears in 100% of the infected animals, and it is evident regardless the parasite load (Oliveira & Andrade 2001). Septal fibrosis extends from portal spaces, going toward neighboring portal spaces and central veins, finishing by involving the entire organ, thus creating a septate mosaic pattern (Ferreira & Andrade 1993, Souza et al 2000, 2001.…”

“…Besides the focal necro-inflammatory parasitic lesions, caused by groups of worms that usually die and disintegrate within the liver soon after egg lying, there also occurs the development of septal fibrosis throughout the liver, a change that appears in all infected rats (Oliveira & Andrade 2001). The model has permitted studies on pathogenesis (Santos et al 2001, Lemos et al 2003, on response to drugs (Souza et al 2000,2001) and on other aspects (Ferreira & Andrade 1993, Oliveira & Andrade 2001. However, the potential of the model is somewhat limited by the peculiarities connected with the experimental host -the rat -because of the difficulties related to the obtaining of commercial kits to study cytokines, chemokines, receptors, growth factors, cells and extra-cellular tissue markers, and so on.…”

Capillaria hepatica (Bancroft, 1893) (Nematoda) entre populações indígenas e mamíferos silvestres no noroeste do Estado do Mato Grosso, Brasil, 2000

“…Uma vez no ambiente, os ovos não embrionados necessitam de cerca de 28 dias, sob condições adequadas de temperatura e umidade, para se tornarem infectantes 11,12 (embrionados) .…”

Capillaria hepatica-induced hepatic fibrosis in rats: paradoxical effect of repeated infections

“…More details regarding the obtaining, preparation and counting of the inoculum are described elsewhere 8 10 16 . The amount of eggs in the inoculum varied in different experiments, but that has been demonstrated not to interfere with the results as far as septal fibrosis is concerned 12 .…”