1Maklad S, 2Kassem MA. and 3Sayed El- Ahl S.
1Microbiology and 3Parasitology Departments,
Faculty of Medicine for Girls and 2Histology Department, Faculty of
Medicine (Assiut), Al. Azhar University.
This study
was designed to investigate the influence of administration time of
praziquantel treatment on the fibrogenic cytokine responses of transforming
growth factor-b (TGF-b) and tumor necrosis factor-a (TNF-a) in Schistosoma
mansoni infected mice. The drug was administered to three different groups
of animals at week 6 or 8 or 12 post infection respectively. Liver tissue
sections were prepared and subjected to Haematoxylin & eosin and Masson's
trichrome staining for histopathological examination of granuloma formation and
collagen deposition. Cryosections were stained with in situ hybridization
technique for detection of mRNA expression of TGF-b and TNF-a by
granuloma cells. Praziquantel treatment elicited significant reduction of worm
burden, oogram pattern, granuloma numbers and size, and collagen deposition
especially when administered at 6 and 8 weeks post infection as compared with
infected non treated control mice, (P<0.001). In contrast, no significant
effect was observed when the drug was administered at week 12 post infection.
Marked reduction of the (mean ±SD) of
TGF-b expression was noticed on
drug administration at 6 weeks 11.4±4.0 % and
8 weeks 24.5±2.9 % post
infection as compared to controls (21.8±3.1 % and
33.7±5.1%) respectively. Similar
results were revealed with TNF-a, where
early administration of the drug induced marked reduction of TNF-a expression, being 26.1±7.7 %, 47.0 ±11.4 %
& 42.9±7.1 % at
6, 8 and 12 weeks post infection as compared to 47.0±11.4 %, 60.1±10.2 % and
52.0±5.2 % in the infected non
treated mice. In conclusion, administration of praziquantel treatment early after
infection may influence the subsequent fibrosis process through marked
reduction of worm burden, granuloma size and number and collagen deposition
most probably due to downregulation.