RESUMO
Schistosomiasis caused by S. mansoni continues to be the most common fibrotic disease resulting from inflammation and deposition of scar tissue around parasite eggs trapped in the liver. Because of the hepatic importance and its ability to regenerate, treating liver fibrosis is of vital significance. Silymarin, a flavinoid complex of Silybum marianum from a plant of the family Asteracea, has received much attention as a potential anti-fibrotic and hepatoprotective agent. To investigate the effect of combining silymarin with praziquantel [PZQ] in the treatment of liver fibrosis in mice infected with S. mansoni. The study was carried out on 120 mice; 96 of which were infected with 100 S. mansoni cercariae and the rest served as non infected controls. Mice were classified into 5 groups, 24 each. G1: Normal control; G2: Infected untreated control; G3: Infected and treated with PZQ, started 6 weeks post infection [PI]; G4: Infected and treated with silymarin, started 4 weeks PI and G5: Infected and treated with silymarin, 4 weeks PI followed by PZQ 6 weeks PI Eight mice from each group were sacrificed on the 10[th], 14[th] and 18[th] week PI. Parasitological, histopathological and biochemical parameters that reflect the disease severity and morbidity were studied. Deposition of extra-cellular matrix [ECM] was determined by estimation of trans-4 hydroxy-L-proline [Hyp] in hepatic cells. PZQ alone showed a significantly high reduction in the mean egg count/gm stool, liver and intestines and was associated with significant increase in the percentage of dead eggs all over the period of the experiment. Silymarin administered alone resulted in slight improvement of parasitological parameters. All the treated groups revealed significant decrease in granuloma diameter especially those after 18[th] week PI Groups treated with silymarin or when combined with PZQ revealed the highest decrease in granuloma diameter at all periods of sacrifice. All treated groups revealed a significant decrease in the Hyp hepatic content. However, the groups treated with silymarin alone or combined with PZQ revealed the most significant decrease in Hyp levels at all periods of sacrifice.The best results obtained, with most of the parameters studied, were in the groups of mice treated with silymarin in combination with PZQ. The use of silymarin combined with PZQ did not affect the chemotherapeutic effect of the latter, and can be safely used with PZQ in patients infected with S. mansoni. Co-administration of silymarin with PZQ reduced the granulomatous inflammatory reactions in the acute and chronic stages of infection. It also had the ability to attenuate liver fibrosis induced by S. mansoni infection. Silymarin can be safely used as an adjuvant with PZQ in the treatment of schistosomiasis mansoni