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.