Proteomics coupled with in vitro model to study the early crosstalk occurring between newly excysted juveniles of Fasciola hepatica and host intestinal cells

Abstract

Fasciolosis caused by the trematode Fasciola hepatica is a zoonotic neglected disease affecting animals and humans worldwide. Infection occurs upon ingestion of aquatic plants or water contaminated with metacercariae. These release the newly excysted juveniles (FhNEJ) in the host duodenum, where they establish contact with the epithelium and cross the intestinal barrier to reach the peritoneum within 2–3 h after infection. Juveniles crawl up the peritoneum towards the liver, and migrate through the hepatic tissue before reaching their definitive location inside the major biliary ducts, where they mature into adult worms. Fasciolosis is treated with triclabendazole, although resistant isolates of the parasite are increasingly being reported. This, together with the limited efficacy of the assayed vaccines against this infection, poses fasciolosis as a veterinary and human health problem of growing concern. In this context, the study of early host-parasite interactions is of paramount importance for the definition of new targets for the treatment and prevention of fasciolosis. Here, we develop a new in vitro model that replicates the first interaction between FhNEJ and mouse primary small intestinal epithelial cells (MPSIEC). FhNEJ and MPSIEC were co-incubated for 3 h and protein extracts (tegument and soma of FhNEJ and membrane and cytosol of MPSIEC) were subjected to quantitative SWATH-MS proteomics and compared to respective controls (MPSIEC and FhNEJ left alone for 3h in culture medium) to evaluate protein expression changes in both the parasite and the host. Results show that the interaction between FhNEJ and MPSIEC triggers a rapid protein expression change of FhNEJ in response to the host epithelial barrier, including cathepsins L3 and L4 and several immunoregulatory proteins. Regarding MPSIEC, stimulation with FhNEJ results in alterations in the protein profile related to immunomodulation and cell-cell interactions, together with a drastic reduction in the expression of proteins linked with ribosome function. The molecules identified in this model of early host-parasite interactions could help define new tools against fasciolosis. Author summary Fasciolosis caused by Fasciola hepatica poses a serious concern for animal and human health worldwide. Treatment and prevention of this disease is challenging due to the appearance of parasites that are resistant to the current treatment and the suboptimal efficacy of assayed vaccines. In this context, the importance of early interactions with the host for parasite migration and infection progression prompted us to develop and study new models of interaction between F. hepatica juveniles and their host. Here, an in vitro model coupled with a quantitative proteomics approach was developed to evaluate the changes in F. hepatica newly excysted juveniles right after their contact with intestinal epithelial cells, which represent the first line of host cells that the parasite encounters upon host infection. Additionally, this model has been used to decipher potential changes elicited by the parasite in the host intestine. A proteomic study of parasites and host cells upon co-incubation revealed specific changes in the repertoire of proteins from both host and parasite following their interaction. These proteins could be of importance for parasite migration and survival inside the host, and give new important insights to understand the host-parasite molecular crosstalk in early fasciolosis.