Hymenolepis diminuta: Analysis of the expression of Toll-like receptor genes (TLR2 and TLR4) in the small and large intestines of rats. Part II

- TLR play a role in maintaining epithelial barrier function in response to parasites.
- The microbiota had only a minor impact on the expression of TLR2 and TLR4.
- TLR2 and TLR4 genes may play a role in the pathophysiology of hymenolepidosis.

Toll-like receptors in the gastrointestinal tract can influence intestinal homeostasis and play a role in the repair and restitution of intestinal epithelium following tissue damage. In our previous study a statistically significant increase in the level of TLR4 and TLR2 gene expression was observed in rats in early stages of hymenolepidosis. Moreover, the immunopositive cell number and the intensity of immunohistochemical staining (indicating the presence of TLRs within intestinal epithelial cells) increased over the infection period.In this paper, we determined changes in the expression of TLR2 and TLR4 and the number of anaerobic intestinal commensal bacteria in Hymenolepis diminuta infected rats. In the isolated jejunum of infected rats at 16 days post infection (dpi), the expression of TLR4 and TLR2 was significantly higher than uninfected rats. In the colon, a statistically significantly increased expression of TLR2 was observed from 16 to 40 dpi, and TLR4 from 16 to 60 dpi. The jejunum and colon of infected rats contained Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Enterococcus, Streptococcus, Staphylococcus, Bacillus, Lactobacillus) and Candida. The total number of intestinal bacteria was higher in H. diminuta infected rats, but the observed microbiota had only minor effects on the expression of TLR2 and TLR4.Toll-like receptors play a role in maintaining epithelial barrier function in response to enteric pathogens and parasites. In our study, the alteration of TLR2 and TLR4 expression in the infected rats indicates the potential role of the innate immune system in the pathomechanism of this infection.

The expression of TLR2 and TLR4 genes on the mRNA level in jejunum isolated from uninfected and Hymenolepis diminuta-infected rats. Small intestines were dissected from rats on 16, 25, 35, 40 and 60 dpi. Expression levels of both TLR genes were determined by RQ-PCR relative quantification analysis evaluated using a calibrator (cDNA mix from all samples). The quantify of TLR transcript in each sample was standardized to the amount of GAPDH cDNA as the internal control. The amounts of TLR2 and TLR4 mRNA are expressed as the multiplicity of these cDNA concentrations in the calibrator. Each sample was determined in triplicate. Data represent mean ± SD and are representative of groups of 7 animals in an experiment. ∗P < 0.05, compared with the control value derived from uninfected rats (Mann-Whitney U test).