Cattle co-infection of Echinococcus granulosus and Fasciola hepatica results in a different systemic cytokine profile than single parasite infection

Abstract

E.granulosusis a cestode that causes Cystic Echinococcosis (CE), a zoonotic disease with worldwide presence. The immune response generated by the host against the metacestode induces a permissive Th2 response, as opposed to pro-inflammatory Th1 response. In this view, mixed Th2 and regulatory responses allow parasite survival. Overall, larvalEchinococcusinfections induce strong regulatory responses.Fasciola hepatica, another common helminth parasite, represents a major infection in cattle. Co-infection with different parasite species in the same host, polyparasitism, is a common occurrence involvingE.granulosusandF.hepaticain cattle. 'While it is known that infection withF.hepaticaalso triggers a polarized Th2/Treg immune response, little is reported regarding effects on the systemic immune response of this example of polyparasitism.F.hepaticaalso triggers immune responses polarized to the Th2/ Treg spectrum. Serum samples from 107 animals were analyzed, and were divided according to their infection status andEchinococcalcysts fertility. Cytokines were measured utilizing a Milliplex Magnetic Bead Panel to detect IFN-gamma, IL-1, IL-2, IL-4, IL-6, IL-10, IL-12 and IL-18. Cattle infected only withF.hepaticahad the highest concentration of every cytokine analyzed, with both 4.24 and 3.34-fold increases in IL-10 and IL-4, respectively, compared to control animals, followed byE.granulosusandF.hepaticaco-infected animals with two-fold increase in IL-10 and IL-4, compared to control animals, suggesting thatE.granulosusco-infection dampens the cattle Th2/Treg immune response againstF.hepatica. When consideringEchinococcalcyst fertility and systemic cytokine concentrations, fertile cysts had higher IFN-gamma, IL-6 and IL-18 concentrations, while infertile cysts had higher IL-10 concentrations. These results show thatE.granulosusco-infection lowers Th1 and Th2 cytokine serological concentration when compared toF.hepaticainfection alone.E.granulosusinfections show no difference in IFN-gamma, IL-1, IL-2, IL-6 and IL-18 levels compared with control animals, highlighting the immune evasion mechanisms of this cestode.