Assessment of the intestinal immune response in Giardia duodenalis experimentally infected rats using quantitative real-time PCR

Background: Giardia duodenalis is a well-known intestinal parasite. The host immune response needs much effort to be clarified.Objective: Evaluation of the transcriptional level of a panel of cytokines in intestinal tissue and assessing the correlation between these levels and cyst count.Material and Methods: An experimental G. duodenalis infection was conducted in a rat model composed of twenty-five laboratory-bred, parasite-free male albino rats, divided into 10 for control group and 15 for infected group. Samples from intestinal tissues were collected to investigate interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin-4 (IL-4) and interleukin-10 (IL-10) using quantitative real-time (qRT)-PCR.Results: The gene expression levels of IFN-γ showed up-regulation on day 7 post-infection (p.i) and reached the peak on day 14 p.i which coincided with the peak of the cyst output. The peak of the expression level of TNF-α, IL-4, and IL-10 was on day 7 p.i. The correlation between cyst count and relative gene expression of pro-inflammatory cytokines showed a strong positive correlation. IL-10 relative gene expression level was moderately correlated, while IL-4 relative gene expression level was weakly correlated.Conclusion: Results indicate that this infection triggers a mixed type of immune response with predominant participation of the pro-inflammatory cytokines. The balance between the pro-inflammatory and the anti-inflammatory cytokines is important in defining infection outcome.