Immune response of mice infected with Schistosoma mansoni is modulated by antifibrotic treatment

Prophylactic effect of the anti-inflammatory drug diclofenac in experimental schistosomiasis mansoni

OBJECTIVES

This study was a trial to demonstrate the prophylactic effect of diclofenac, a widely used anti-inflammatory drug (diclofenac potassium, CAS-15307-81-0, Ciba Geigy, 334.2) in experimental schistosomiasis mansoni. Two different dose regimens were used to explore the effects upon worm load, tissue egg load, and hepatic granuloma size.

METHODS

In this study, a group of 50 Swiss albino mice was used. This group was divided into five subgroups: subgroup I constituted infected untreated control mice; subgroup II, infected mice given 0.5 mg diclofenac orally 24 h post infection, then sacrificed three weeks later; subgroup III, infected mice given 0.5 mg diclofenac orally six weeks post infection and sacrificed one week later; subgroup IV, infected mice administered 1mg diclofenac orally 24 h post infection and sacrificed three weeks later; and subgroup V, infected mice given 1mg of the drug orally six weeks post infection and sacrificed one week later.

RESULTS

Mice given the high dose regimen (1mg orally/mouse) 24 h post infection, then sacrificed three weeks later, demonstrated a significant reduction in the immature worms recovered, compared to the untreated controls. Animals receiving the high dose of the drug six weeks post infection, then sacrificed one week later, revealed a drop in the number of mature worms and in the tissue egg load (hepatic and intestinal), and the smallest hepatic granuloma measurement compared to the untreated controls. These findings were less conspicuous in animals given the low dose regimen.

CONCLUSION

Diclofenac could be used successfully as a preventive agent against schistosomiasis mansoni infection in endemic areas.

Impact of antifibrotic treatment of the course of Schistosoma mansoni infection in murine model

Administration of an antifibrotic agent as an adjunct to antihelmintic treatment with the objective of morbidity reduction was investigated in the murine schistosomiasis mansoni model. Antifibrotic, beta-aminopropionitrile treatment has a profound effect on the cellular matrix composition of the liver granuloma of Schistosoma mansoni infected mice when given alone, resulting in increase macrophage infiltration. These macrophages, in response to stimulation with soluble egg antigen or lipopolysaccharide produced elevated levels of nitric oxide but low levels of tumor necrosis factor alpha compared to untreated infected mice. This also correlated with reduced liver granuloma size. In spite of low numbers of eggs in the liver, mice receiving a combine treatment had a high level of resistance to a challenge infection compared with mice receiving only praziquantel. Those mice also exhibited a reduced lymphocyte proliferative response, similar to that of infected untreated mice. Antifibrotic treatment has an impact on the dynamic of the cellular nature of granulomas and impacts on the host immunity of infection.