Characterisation of a niche-specific excretory-secretory peroxiredoxin from the parasitic nematode Teladorsagia circumcincta

Investigation of Host-Microbe-Parasite Interactions in an In Vitro 3D Model of the Vertebrate Gut

In vitro models of the gut-microbiome axis are in high demand. Conventionally, intestinal monolayers grown on Transwell setups are used to test the effects of commensals/pathogens on the barrier integrity, both under homeostatic and pathophysiological conditions. While such models remain valuable for deepening the understanding of host-microbe interactions, often, they lack key biological components that mediate this intricate crosstalk. Here, a 3D in vitro model of the vertebrate intestinal epithelium, interfaced with immune cells surviving in culture for over 3 weeks, is developed and applied to proof-of-concept studies of host-microbe interactions. More specifically, the establishment of stable host-microbe cocultures is described and functional and morphological changes in the intestinal barrier induced by the presence of commensal bacteria are shown. Finally, evidence is provided that the 3D vertebrate gut models can be used as platforms to test host-microbe-parasite interactions. Exposure of gut-immune-bacteria cocultures to helminth "excretory/secretory products" induces in vivo-like up-/down-regulation of certain cytokines. These findings support the robustness of the modular in vitro cell systems for investigating the dynamics of host-microbe crosstalk and pave the way toward new approaches for systems biology studies of pathogens that cannot be maintained in vitro, including parasitic helminths.

Endogenous Fluorescent Proteins in the Mucus of an Intertidal Polychaeta: Clues for Biotechnology

The vast ocean holds many unexplored organisms with unique adaptive features that enable them to thrive in their environment. The secretion of fluorescent proteins is one of them, with reports on the presence of such compounds in marine annelids being scarce. The intertidal Eulalia sp. is an example. The worm secretes copious amounts of mucus, that when purified and concentrated extracts, yield strong fluorescence under UV light. Emission has two main maxima, at 400 nm and at 500 nm, with the latter responsible for the blue–greenish fluorescence. Combining proteomics and transcriptomics techniques, we identified ubiquitin, peroxiredoxin, and 14-3-3 protein as key elements in the mucus. Fluorescence was found to be mainly modulated by redox status and pH, being consistently upheld in extracts prepared in Tris-HCl buffer with reducing agent at pH 7 and excited at 330 nm. One of the proteins associated with the fluorescent signal was localized in secretory cells in the pharynx. The results indicate that the secretion of fluorescent proteinaceous complexes can be an important defense against UV for this dweller. Additionally, the internalization of fluorescent complexes by ovarian cancer cells and modulation of fluorescence of redox status bears important considerations for biotechnological application of mucus components as markers.

A Complex Proteomic Response of the Parasitic Nematode Anisakis simplex s.s. to Escherichia coliLipopolysaccharide

Helminths are masters at manipulating host's immune response. Especially, parasitic nematodes have evolved strategies that allow them to evade, suppress, or modulate host's immune response to persist and spread in the host's organism. While the immunomodulatory effects of nematodes on their hosts are studied with a great commitment, very little is known about nematodes' own immune system, immune response to their pathogens, and interactions between parasites and bacteria in the host's organism. To illustrate the response of the parasitic nematode Anisakis simplex s.s. during simulated interaction with Escherichia coli, different concentrations of lipopolysaccharide (LPS) were used, and the proteomic analysis with isobaric mass tags for relative and absolute quantification (tandem mass tag-based LC-MS/MS) was performed. In addition, gene expression and biochemical analyses of selected markers of oxidative stress were determined. The results revealed 1148 proteins in a group of which 115 were identified as differentially regulated proteins, for example, peroxiredoxin, thioredoxin, and macrophage migration inhibitory factor. Gene Ontology annotation and Reactome pathway analysis indicated that metabolic pathways related to catalytic activity, oxidation-reduction processes, antioxidant activity, response to stress, and innate immune system were the most common, in which differentially regulated proteins were involved. Further biochemical analyses let us confirm that the LPS induced the oxidative stress response, which plays a key role in the innate immunity of parasitic nematodes. Our findings, to our knowledge, indicate for the first time, the complexity of the interaction of parasitic nematode, A. simplex s.s. with bacterial LPS, which mimics the coexistence of helminth and gut bacteria in the host. The simulation of this crosstalk led us to conclude that the obtained results could be hugely valuable in the integrated systems biology approach to describe a relationship between parasite, host, and its commensal bacteria.

Prospects of Using High-Throughput Proteomics to Underpin the Discovery of Animal Host-Nematode Interactions

Parasitic nematodes impose a significant public health burden, and cause major economic losses to agriculture worldwide. Due to the widespread of anthelmintic resistance and lack of effective vaccines for most nematode species, there is an urgent need to discover novel therapeutic and vaccine targets, informed through an understanding of host-parasite interactions. Proteomics, underpinned by genomics, enables the global characterisation proteins expressed in a particular cell type, tissue and organism, and provides a key to insights at the host-parasite interface using advanced high-throughput mass spectrometry-based proteomic technologies. Here, we (i) review current mass-spectrometry-based proteomic methods, with an emphasis on a high-throughput 'bottom-up' approach; (ii) summarise recent progress in the proteomics of parasitic nematodes of animals, with a focus on molecules inferred to be involved in host-parasite interactions; and (iii) discuss future research directions that could enhance our knowledge and understanding of the molecular interplay between nematodes and host animals, in order to work toward new, improved methods for the treatment, diagnosis and control of nematodiases.

The Functional Parasitic Worm Secretome: Mapping the Place of Onchocerca volvulus Excretory Secretory Products

Nematodes constitute a very successful phylum, especially in terms of parasitism. Inside their mammalian hosts, parasitic nematodes mainly dwell in the digestive tract (geohelminths) or in the vascular system (filariae). One of their main characteristics is their long sojourn inside the body where they are accessible to the immune system. Several strategies are used by parasites in order to counteract the immune attacks. One of them is the expression of molecules interfering with the function of the immune system. Excretory-secretory products (ESPs) pertain to this category. This is, however, not their only biological function, as they seem also involved in other mechanisms such as pathogenicity or parasitic cycle (molting, for example). We will mainly focus on filariae ESPs with an emphasis on data available regarding Onchocerca volvulus, but we will also refer to a few relevant/illustrative examples related to other worm categories when necessary (geohelminth nematodes, trematodes or cestodes). We first present Onchocerca volvulus, mainly focusing on the aspects of this organism that seem relevant when it comes to ESPs: life cycle, manifestations of the sickness, immunosuppression, diagnosis and treatment. We then elaborate on the function and use of ESPs in these aspects.