Abstract
Parasite immune response against schistosomal antigens involves both the innate and adaptive immune response. Tregs have a suppressive effect and play a role on the parasite's immune evasion. This study aimed to evaluate active compounds of Allium sativum (AS) ethanol extract and the impact of AS extract alone or in combination with praziquantel on Tregs and anti-inflammatory cytokines TGF-beta and IL-10 in mice infected with S. mansoni. Phytochemical screening of AS bulbs for various active constituents and qualitative and quantitative analysis of the flavonoids and phenolic acids were done using HPLC. Measurement of splenocytes Treg cell phenotypes and anti-inflammatory cytokines TGF-beta and IL-10 was done by flow cytometric analysis. The data are expressed as mean +/- SD. Statistical significance was determined by one-way ANOVA utilizing the statistical package (SPSS version 17.0). HPLC of AS ethanol extract revealed presence of 22 and 18 compounds of flavonoids and phenolic acids, respectively. S. mansoni infection upregulated the Treg cells subsets (CD4, CD25, Foxp3) frequencies and the levels of TGF-beta and IL-10 anti-inflammatory cytokines when compared to healthy control. AS ethanol extract alone or combined with PZQ decreases the production of Treg cells from spleen in addition to the reduction in anti-inflammatory cytokines IL-10 and TGF-beta. This study recommends that the combination of AS ethanol extract and PZQ may play a role in maintaining the homeostasis of the immune system during schistosomiasis by decreasing Treg cells and anti-inflammatory cytokines IL-10 and TGF-beta production.