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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - GUTWORM (Unravelling host intestine-parasite interactions that define immune responses to whipworms)

Teaser

Summary

Trichuriasis is a major Neglected Tropical Disease affecting hundreds of millions of people, mainly children, from low- and middle-income countries. This disease is characterized by abdominal pain, diarrhea and anemia and it is linked to physical and intellectual growth retardation. Trichuriasis is caused by infection with whipworms (Trichuris trichiura), which occurs upon ingestion of eggs of these parasites present on food or water. In the gut, the eggs hatch, liberating larvae that then burrow through the gut lining (epithelium) and cause inflammation. The interactions of whipworms with the gut epithelium and immune cells are thought to be crucial in determining if the parasite is expelled or if it remains in the gut causing a chronic disease. However, up to now, the details of these interactions are not understood, hampering the development of therapies to treat or vaccines to prevent whipworm infections. The ultimate goal of my research project is to investigate and understand these interactions in detail. To achieve this, I use T. muris, a mouse model of T. trichuira infection in humans. This research project has three key aims. First, to identify new parasite and host genes that could interplay and modulate immune responses. Second, to characterize the role of host genes in whipworm infection and immunity. Finally, upon identification of key genes regulating gut epithelium and immune responses to whipworms, to explore in great depth the mechanism of action of those genes and their effect on the parasite.

Work performed

During the first stage of my project, I focused on the identification novel genes of both the host and the parasite potentially involved on the interplay of whipworms with both gut epithelium and immune cells. To do this, I reviewed the literature and data on susceptibility to intestinal inflammation challenges of existing mutant mouse lines. In addition, I performed transcriptomic and imaging experiments studying the very first events after whipworm infection of mice (3 hours, one and 3 days). These studies revealed early interactions of the larvae with goblet cells, a specific epithelial cell type that produces mucus. They also revealed the expression of whipworm proteases and protease inhibitors that are potentially required for mucus degradation, suggesting the interaction with goblet cells is critical for the invasion and colonization of the gut.
In the second stage of the fellowship, new mutant mouse lines were generated for novel host genes identified as part of work by the Wellcome Trust-funded Infection and Immunity Immunophenotyping (3i) Consortium. I evaluated the role of these host genes on the development of immune responses to whipworms and their expulsion by infecting 300 mutant mouse lines with a high dose of T. muris. Through this screen, I identified 10 genes conferring either enhanced resistance or susceptibility to whipworms, namely Adal, Fam160a1, Klk5, Wac, Irak1, IL-27, Arpc1b, and the members of the IL-10 receptor family, Il-10, Il-10ra and Il-10rb.
Through the last phase of my project, I focused on experiments to deeply investigate the role on immunity to whipworm infections of different members of the IL-10 receptor family. Specifically, I found that IL-10 signaling, but not the related cytokines IL-22 or IL-28, promotes intestinal colonization resistance against opportunistic pathogens and controls immunopathology during whipworm infection. In addition, to further understand the early interactions of whipworms with the gut epithelium, I am: 1) attempting to generate mutant whipworms to study the function of parasite genes during early infection; 2) doing proteomics and mucus degradation experiments with whipworm larvae; and 3) performing gene expression analysis of single gut epithelial cells to investigate the initiation of the host responses to whipworm infection. Finally, as an alternative model and to replace the use of mice for these studies, I developed a novel in vitro model using mouse and human miniature (mini)-guts and inject them with mouse and human whipworm larvae. Mini-guts are 3D cell clusters generated from gut tissue that have similar characteristics and function to the gut. Using this new model, I am currently using microscopy and transcriptomic technologies to better understand the processes of invasion and establishment of the larvae inside the epithelium.
To disseminate the results of this research project, during the length of this fellowship, I presented my findings on international scientific conferences and internal seminars and retreats at the Sanger Institute and the 3i consortium, resulting in both a poster and a presentation prize. Moreover, all sequencing data obtained in this study has been made accessible prior to publication through the European Nucleotide Archive (www.ebi.ac.uk/ena/) and WormBase Parasite (parasite.wormbase.org/). The results of the challenge of mutant mouse strains are also publically available at www.immunophenotype.org. In addition, mutant mouse lines produced during this project are available upon request (www.sanger.ac.uk/mouseportal/). Finally, I am currently preparing manuscripts describing the main findings of this project, which will soon be submitted to peer-reviewed journals.

Final results

The project is reaching far beyond the generation of state-of-the-art fundamental data, with resources and innovative techniques to understand host-whipworms interactions that will support future efforts to control these parasites by the development of vaccines and discovery of new drugs. The knowledge, methodologies to study host-parasite interactions and analytical approaches developed here will be applicable to research on other parasitic worms. Moreover, resulting knowledge of the parasite-gut epithelium interplay could be exploited to understand other intestinal inflammatory diseases that have many similarities with trichuriasis and for which infection with intestinal parasitic worms is being used as therapeutic treatment.
Through dissemination and public engagement (PE) actions around the broad context of the work, this project is having a societal impact. In collaboration with the Sanger Institute PE team, I am implementing two PE actions that target the general public of developed and developing countries. The first one, the Genome Decoders project, involves up to 1000 A-level students (16-18 years old) in the curation of a new version of the genome of T. trichiura. The project will run for one year and was launched with a single day event attended by 200 teachers and students. Amongst many outreach activities on the day (including seminars and hands-on parasitology sessions), I was interviewed and subsequently appeared on BBC Radio 4. My second major PE activity called Worm Hunters, will target 120 primary school children from a town in Colombia with high prevalence of Trichuris infection in February 2018. I have collaborated with the PE team to create a comic and classroom activities to accompany a deworming study that I have initiated. These PE actions increase the awareness trichuriasis, promote knowledge of whipworm infections to improve sanitation practices that will prevent its transmission, and finally, they involve children and teenagers in scientific activities to inspire them to become future researchers.