PIPE

Probing the constituents of homeostasis There is no known cure for inflammatory bowel diseases and irritable bowel syndrome, conditions which affect millions of people across the world. Researchers in the PIPE project are investigating the physiology of the intestine, which could lay the foundations for the development of new, more effective therapies, as Doctor Nathalie Vergnolle explains.

The intestinal epithelium

is the first point of contact between the external world and the interior of the body, forming an important part of the mucosal layer. As the Principal Investigator of the PIPE project, Doctor Nathalie Vergnolle aims to investigate proteolytic homeostasis at mucosal surfaces, focusing specifically on the intestinal epithelium. “We’re looking at what kinds of proteases and inhibitors are produced and released by the intestinal epithelium, and under what circumstances,” she outlines.

Homeostasis needs to be maintained at the intestinal epithelium so that it can function effectively, which is an important aspect of Dr Vergnolle’s research. “A large part of our work involves determining what are the constituents of homeostasis on the protease side, and also on the inhibitor side,” she says.

This research holds important implications for the treatment of gastrointestinal diseases like inflammatory bowel diseases (IBD) or irritable bowel syndrome (IBS), chronic conditions that affect millions of people across the world. While the symptoms of IBD may be sporadic, and at times patients may experience remission, if left untreated it can have serious effects. “If we don’t prevent the recruitment of inflammatory cells it can get worse, to a point where it can even be fatal,” says Dr Vergnolle. “IBS is a low-grade inflammation pathology, which is mostly characterised by pain. It’s not a lethal disease, but it is extremely painful. There haven’t been many studies looking at IBS and how it develops as people age, so it’s difficult to say

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whether it gets worse over time. But patients with the condition suffer all their lives.”

A range of treatment options are available to mitigate the effects of these conditions, including immunosuppressants (for IBD), probiotics and antibiotics, while in some cases lifestyle changes such as dietary modifications might be recommended. While these measures may prove effective to a degree, Dr Vergnolle says current therapies have some significant limitations. “What is missing in existing therapeutic options is the ability to help repair tissues, and to help these tissues regain normal functioning,” she explains. The project will make an important contribution in these terms by developing a deeper understanding of the physiology of the intestine, which could help lay the foundations for the development of new therapies in future. “By understanding

how homeostasis is disrupted in those diseases, we could then understand how we could treat them more effectively,” says Dr Vergnolle.

Tissue samples The precise nature of homeostasis is likely to vary according to individual physiology, yet researchers have nevertheless still been able to gain more general insights through analysis of tissue samples from patients with IBD or IBS. Homeostasis can be broadly thought of as a kind of healthy equilibrium, and disrupting it can lead on to problems. “A broken equilibrium can mean that you have too many of some things, or not enough of others,” explains Dr Vergnolle.

By analysing and characterising tissue samples, researchers aim to learn more about proteolytic homeostasis. “We try to understand the role of the factors that are either up-regulated or

Figure 1: Proteolytic Homeostasis warrants the Control of Mucosal Functions.

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PIPE

Physiology of the Intestine: Proteases from the Epithelium

Project Objectives

The aim of the PIPE project is to: 1.) characterize the protease/anti-protease balance issued from intestinal epithelium, 2.) study the impact of intestinal epithelium-derived proteolytic machinery on epithelial physiological functions 3.) study the impact of intestinal epithelium-derived proteolytic factors on enteric nervous system activation It is hoped that the results of this study will lead to the identification of previously unknown actors in intestine physiology and pathophysiology, and of the neuro-epithelial crosstalks in the gut.

Figure 2: Ruptured Proteolytic Balance impairs Mucosal Functions.

Project Funding

Funded under: FP7-IDEAS-ERC • Overall budget: € 1 287 000

Contact Details

Nathalie Vergnolle Institut de Recherche en Santé Digestive Inserm - INRA - Univ Tlse3 - INP ENVT CHU Purpan - Place du Docteur Baylac CS 60039 31024 TOULOUSE Cedex 3 T: +33 6 78 44 13 61 E: nathalie.vergnolle@inserm.fr W: https://www.inserm.fr/rechercheinserm/portraits-chercheurs/laureats-erc/ nathalie-vergnolle-bacteries-alimentairespour-soigner-mici Nathalie Vergnolle Figure 3: The Intestinal Epithelium is a Major Source of Proteases and Inhibitors Controlling Mucosal Functions.

down-regulated, depending on what’s there and what’s absent, in patients suffering from IBD or IBS,” says Dr Vergnolle. “From this point, we can then look towards thinking about ways to interact with those factors, in order to gain new therapeutic options.”

Researchers also used cell lines and animal models of diseases over the course of the project, as Dr Vergnolle and her colleagues probed deeper into the underlying nature of proteolytic homeostasis and the specific factors which lead to disruption. Researchers have observed that stimulating the intestinal epithelium leads to the release of different kinds of proteases, and so disturbs proteolytic homeostasis. “It does that under different circumstances, for example by an inflammatory stimulus, or an infectious stimulus. Even stress hormones can induce this release of proteases, that might interfere with homeostasis,” outlines Dr Vergnolle. “This is essentially the foundation of the idea that a disturbed epithelium reacts to that disturbance by releasing different proteases and protease inhibitors.”

By investigating how the intestine reacts to the presence of these specific proteases and

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inhibitors, Dr Vergnolle hopes to learn more about the physiology and pathophysiology of gastrointestinal diseases. The next step would be to build on these foundations by proposing new therapeutic interventions. “This could be drugs. It could be specific inhibitors, or maybe antibodies that block protease activity,” says Dr Vergnolle. A number of potential targets have been identified over the course of the project, which could

therapeutic benefit for patients, while there are also many more possible targets that haven’t been thoroughly assessed yet. The wider goal in this research is to improve treatment of IBD and IBS. “With IBS, it’s currently more about managing the condition than treating it. Patients may have associated symptoms, like either diarrhoea or constipation. We can intervene in these circumstances and prevent diarrhoea

By understanding how proteolytic homeostasis is disrupted in inflammatory bowel diseases and irritable bowel syndrome, we could then understand how we could treat them more effectively. open up new therapeutic possibilities in future.

“We’ve defined some proteases that are new targets for drug development. Also, some of the inhibitors that we found were very helpful in terms of regaining a healthy situation in tissues,” continues Dr Vergnolle.

Researchers are investigating these different inhibitors and antibodies in great detail, and looking to assess whether they could have a

or constipation, but the pain symptoms have not really been addressed - that’s why we are investigating this area,” says Dr Vergnolle.

By building a deeper understanding of the physiology of the intestine, Dr Vergnolle hopes to lay the ground work for improved treatment in future. “From there we hope to have the ability to propose new, more effective therapeutic interventions,” she says.

EU Research

Dietary changes A lot of attention in the project has been focused on drug development, yet a deeper knowledge of intestine physiology would also help researchers assess the impact of diet, an important factor in both IBD and IBS. Dietary changes can mitigate the symptoms of both conditions, yet the picture in this area is not entirely clear. “Changing diet might be helpful in some cases, but this is something that we don’t fully understand.

There is no clear indication of the dietary changes that each individual patient should make,” explains Dr Vergnolle. One question Dr Vergnolle and her colleagues have been looking at is how proteolytic homeostasis is affected by dietary interventions. “Diet might change homeostasis, but we cannot say with complete confidence that it changes it in a particular way,” she continues.

This research could also hold broader relevance beyond the initial focus of the PIPE project. Mucosal surfaces within the body are often very much alike in the way they react to aggressions and damage, which could represent another avenue of

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investigation in future. “Similar events could take place at these other mucosal surfaces, like the lungs, bladder, or vagina, so similar targets might be found there. It’s difficult to say this with confidence right now though, because not enough research has been done on those other mucosal surfaces from a proteolytic homeostasis point of view,” outlines Dr Vergnolle. Disruption of proteolytic homeostasis might also have an effect on other pathologies. “We focused on inflammatory diseases and pain in the project – but there might also be some important effects on other pathologies, such as cancer, upon long-term disruption of the mucosal proteolytic homeostasis,” says Dr Vergnolle.

There are many possible avenues of research arising out of the project’s work, both in terms of developing new therapies to treat disease and more fundamental investigation into mucosal surfaces. For the moment though, Dr Vergnolle says the priority is to characterise the functions of all the different targets. “We will carry on investigating each of the targets that we have identified,” she says.

Nathalie Vergnolle, research director at INSERM, is since 1 January 2016 as head of the Research Institute for Digestive Health. She is also responsible for the team “Pathophysiology of the intestinal epithelium.”

Before conducting her research in Toulouse, Dr. Vergnolle spent 10 years at the University of Calgary (Canada) in the Department of Pharmacology. Her work has highlighted the role of several mediators involved in inflammation and pain. In collaboration with researchers from INRA and the Pasteur Institute, her team produced bacteria expressing a human protein, elafin that can protect the body from intestinal inflammation.

Her researchers have earned her international recognition and are supported at European, national and regional level. They have led to very active academic and private collaborations.

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