P173 Course of the Th-1, Th-2 and Th-17 cytokines and of associated chemokines involved in the periparasitic recruitment of cells in echinococcus multilocularis infection

Abstract

Alveolar echinococcosis (AE) is characterized by the periparasitic infiltration of immune cells surrounding Echinococcus (E.) multilocularis vesicles in the liver, responsible for the pathological events which lead to clinical complications. Course of Th1- and Th2-related cytokine secretion has been described in the experimental model of AE; however, nothing is known about the involvement of IL-17 and chemokines although their crucial role in cell homing to inflammatory reaction sites is well known. Gene expression profiles were assessed using DNA microarray analysis, 1, 2, 3 and 6 months after injection of E. multilocularis metacestode in the liver of susceptible mice. Quantitative RT-PCR was used to describe the changes in the expression of 10 selected cytokine and chemokine genes from 2 days to 12 months. The periparasitic infiltration was studied after specific immunostaining of the liver sections and the presence of CD4 and CD8 cells and expression of IL-17 was quantified by calculating scores. Microarray analysis showed that CCL8, CCL12 and CCL17 were up-regulated 30-fold, 6-fold and 3-fold at 1 month, respectively. CXCL-9, a proinflammatory chemokine, was up-regulated 3-fold at 6 months. Among genes of cytokine receptors, only those for IL-1 (IL-R1 like) and IL-7 (at 1 month, 2.92 and 2.25-fold respectively), and IL-13 (IL-13 R α 1) and IL-17 (IL-17 R) were up-regulated (2.39 at 3 months and 2.90 at 6 months respectively). Real time RT-PCR data showed that Th1 immune response was predominant in the early stage, but shifted to Th2 in the middle/late stage. IL-17 mRNA increased from ∼2.41-fold at day2 to 6.58-fold at month6 with a maximum expression at month6. In the periparasitic infiltrate, positive immunostainings for IL-17 were observed from day8 to month12. IL-17 positive scores ranged from 0.13 to 4.80 and reached the peak point at month3. And IL-17 expression was highly correlated with CD4 (Spearman’s rho = 0.864), CD8(Spearman’s rho = 0.684) and CD4/8 ratio (Spearman’s rho = 0.524). Our data confirm that Th1 then Th1/Th2 profiles characterize the local immune response during E. multilocularis infection at the early and middle/late stages respectively; in addition the marked expression of IL-17 and chemokines suggest that they are involved in cell homing to inflammatory reaction sites around the parasite vesicles and to the impressive granulomatous reaction which is a hallmark of AE pathology.