Anisakiasis is a zoonotic disease caused by consumption of raw fish parasitized with Anisakis spp third stage larvae (L3). Despite Anisakis L3 cannot develop as adults in humans, they can still cause a complex disease with unspecific symptoms leading to acute or chronic forms. In fact, larval migration in the gastrointestinal tract, the excreted/secreted products and parasite extracellular vesicles (EVs) can progressively determine severe allergic manifestations, erosive, ulcerous lesions and granulomas. Recently, reports of tumors co-occurrence with Anisakis L3 are increasing. Although the question as to whether anisakiasis and carcinoma co-occurrence is accidental or not is not resolved, neoplasia and mucosal embedded larvae share a common site associated to chronic inflammation in all reported cases.
Despite the increasing public health awareness on anisakiasis, most of the mechanisms of infection, the role of host's immune response and its potential implications are still unknown. The aim of this study is to investigate the inflammatory pathway in in-vitro human epithelial colorectal adenocarcinoma cells (Caco-2) exposed to the live L3, the crude extract (CE) and the exosomes enriched fraction, as representative of the mechanical action of larval motility, the whole body of senescent larvae and the potential inflammation silencing due to EVs contents, respectively. In particular, the activation of inflammatory response key molecules (P38, JNK, ERK1/2, NF-kB), and the amounts of the pro-inflammatory cytokines (IL-6, IL-8) will be analyzed.
Helminths, multicellular worm parasites including nematodes, cestodes and trematodes, are able to establish long-lived chronic infections indicating successful manipulation of the host immune system. For anisakiasis, such concept is not entirely valid as humans are accidental hosts in which they cannot exhibit this masterclass ability, but they are still able to induce mild-to-severe reactions involving inflammatory and immune response.
Due to this complexity and that its clinical and public relevance has only recently been considered, there are few studies able to provide a complete picture of its pathogenetic cycle in humans, focusing on basic mechanisms and their potential role in chronic inflammation and tumorigenic processes.
This project has the aim to extend the knowledge in this field, exploiting three different pathogenic products of the parasite and their effects on human host. In addition, many parasitic nematodes cannot be easily cultured and existing in-vitro and in-vivo models do not sufficiently recount the human background and disease. The importance of the present project is the development of an appropriate in-vitro model to study Anisakis-host interaction opening the way to a series of researches on a wide array of nematodes of human health concern (i.e. Ascaris, Trichuris). In particular, this model will be used to study the role of different Anisakis-derived products on cellular inflammatory response unveiling the importance of parasite-human crosstalk.
The study of the intracellular response and how it can be affected by these products can add new notions both in the pathogenesis of anisakiasis and in the parasite communication with the host. In particular, exosomes are a new vehicle of communication recently discovered and on which only a few studies have been carried out on other parasites (Eichenberger et al. 2018 J extracell vesicles, 7, 1428004; Hansen et al. 2019 J extracell vesicles, 8, 1578116). Finally, deepening these inflammatory mechanisms could shed light into cellular signals potentially involved in tumor processes.