Researchers at the University of Vienna develop gut-stable oxytocin analogues for targeted pain treatment of chronic abdominal pain
Photo by Andrea Piacquadio on Pexels
A research team at the University of Vienna, led by medicinal chemist Markus Muttenthaler, has developed a new class of oral peptide therapeutic leads for treating chronic abdominal pain. This groundbreaking innovation offers a safe, non-opioid-based solution for conditions such as irritable bowel syndrome (IBS) and inflammatory bowel diseases (IBD), which affect millions of people worldwide. The research results were published in Angewandte Chemie.
An innovative approach to pain management
Current medications used to treat chronic abdominal pain often rely on opioids. However, opioids can cause severe side effects such as addiction, nausea, and constipation. Additionally, they affect the central nervous system, often leading to fatigue and drowsiness, which impairs the quality of life of those affected. The addiction risk is particularly problematic and has contributed to the ongoing global opioid crisis. Therefore, there is an urgent need for alternatives that minimise these risks.
This new therapeutic approach targets oxytocin receptors in the gut, which, in addition to its role in social bonding, also affects pain perception. When the peptide hormone oxytocin binds to these receptors, it triggers a signal that reduces pain signals in the gut. The advantage of this approach is that the effect is gut-specific, thus having a lower risk of side effects due to its non-systemic, gut-restricted action.
Oxytocin itself cannot be taken orally because it is rapidly broken down in the gastrointestinal tract. However, Prof Muttenthaler’s team has successfully created oxytocin compounds that are fully gut-stable yet can still potently and selectively activate the oxytocin receptor. This means these newly developed oxytocin-like peptides can be taken orally, allowing for convenient treatment for patients. This approach is especially innovative since most peptide drugs (such as insulin, GLP1 analogues) need to be injected as they are also quickly degraded in the gut.
“Our research highlights the therapeutic potential of gut-specific peptides and offers a new, safe alternative to existing pain medications, particularly for those suffering from chronic gut disorders and abdominal pain,” explains Muttenthaler.
Next steps and future outlook
With support from the European Research Council, the scientists are now working to translate their research findings into practice. The goal is to bring these new peptides to market as an effective and safe treatment for chronic abdominal pain. Moreover, the general approach of oral, stable, and gut-specific peptide therapeutics could revolutionise the treatment of gastrointestinal diseases, as the therapeutic potential of peptides in this area has not yet been fully explored.
The team has already secured a patent for the developed drug leads and is now actively seeking investors and industrial partners to advance the drug leads towards the clinic.
An international study has found that genetic variations in human carbohydrate-active enzymes may affect how people with irritable bowel syndrome (IBS) respond to a carbohydrate-reduced diet.
The research, which is published in Clinical Gastroenterology & Hepatology, shows that IBS patients with genetic defects in carbohydrate digestion had a better response to certain dietary interventions. This could lead to tailored treatments for IBS, using genetic markers to predict which patients benefit from specific diets.
Irritable bowel syndrome (IBS) is a digestive disorder affecting up to 10% of the global population. It is characterised by abdominal pain, bloating, diarrhoea, or constipation. Despite its prevalence, treating IBS remains a challenge as symptoms and responses to dietary or pharmacological interventions vary significantly.
Patients often connect their symptoms to eating certain foods, especially carbohydrates, and dietary elimination or reduction has emerged as an effective treatment option, though not all patients experience the same benefits.
Nutrigenetics (the science investigating the combined action of our genes and nutrition on human health) has highlighted how changes in the DNA can affect the way we process food. A well-known example is lactose intolerance, where the loss of function in the lactase enzyme hinders the digestion of dairy products.
Now, this pioneering new study suggests that genetic variations in human carbohydrate-active enzymes (hCAZymes) may similarly affect how IBS patients respond to a carbohydrate-reduced (low-FODMAP) diet.
The team have now revealed that individuals with hypomorphic (defective) variants in hCAZyme genes are more likely to benefit from a carbohydrate-reduced diet.
The study, involving 250 IBS patients, compared two treatments: a diet low in fermentable carbohydrates (FODMAPs) and the antispasmodic medication otilonium bromide. Strikingly, of the 196 patients on the diet, those carrying defective hCAZyme genes showed marked improvement compared to non-carriers, and the effect was particularly pronounced in patients with diarrhoea-predominant IBS (IBS-D), who were six times more likely to respond to the diet. In contrast, this difference was not observed in patients receiving medication, underscoring the specificity of genetic predisposition in dietary treatment efficacy.
These findings suggest that genetic variations in hCAZyme enzymes, which play a key role in digesting carbohydrates, could become critical markers for designing personalised dietary treatments for IBS. The ability to predict which patients respond best to a carbohydrate-reduced diet has the potential to strongly impact IBS management, leading to better adherence and improved outcomes.
Study leader Dr D’Amato, Gastrointestinal Genetics Research group at CIC bioGUNE and the Department of Medicine and Surgery at LUM University in in Italy.
In the future, incorporating knowledge of hCAZyme genotype into clinical practice could enable clinicians to identify in advance which patients are most likely to benefit from specific dietary interventions. This would not only avoid unnecessary restrictive diets for those unlikely to benefit but also open the door to personalised medicine in IBS.
Dietary treatment is more effective than medications in irritable bowel syndrome (IBS), according to the results of a study conducted at the University of Gothenburg. With dietary adjustments, more than seven out of ten patients had significantly reduced symptoms.
Irritable bowel syndrome (IBS) is a common diagnosis that causes abdominal pain, gas and abdominal bloating, diarrhoea, and constipation, in various combinations and with varying degrees of severity.
Treatment often consists of dietary advice such as eating small and frequent meals and avoiding excessive intake of food triggers such as coffee, alcohol and fizzy drinks. Patients may also be given medications to improve specific symptoms, such as gas or constipation, diarrhoea, bloating or abdominal pain. Antidepressants are sometimes used to improve symptoms in IBS.
The current study, published in The Lancet Gastroenterology & Hepatology, compared three treatments: two dietary and one medication-based. The participants were adult patients with severe or moderate IBS symptoms at Sahlgrenska University Hospital in Gothenburg.
More symptom relief after dietary adjustment
The first group was given traditional IBS dietary advice, focusing on eating behaviour combined with low intake of fermentable carbohydrates (FODMAPs). These include products with lactose, legumes, onions, and grains, which ferment in the colon and can cause pain in IBS.
The second group received a dietary treatment low in carbohydrates and proportionally high in protein and fat. In the third group, the best possible medication was given based on the patient’s most troublesome IBS symptoms.
Each group included around 100 participants in four-week treatment periods. Treatment response was measure with an established IBS symptom scoring scale.
Of those who received traditional IBS dietary advice and low content of FODMAPs, 76% had significantly reduced symptoms. In the group receiving low carbohydrates and high protein and fat, the proportion was 71%, and in the medication group 58%.
All groups reported significantly better quality of life, less physical symptoms and less symptoms of anxiety and depression.
The importance of personalisation
At a six-month follow-up, when participants in the dietary groups had partially returned to their previous eating habits, a large proportion still had clinically significant symptom relief; 68% in the traditional dietary advice and low FODMAP group, and 60% in the low-carbohydrate diet group.
The study was led by Sanna Nybacka, Researcher and Dietician, Stine Störsrud, Associate Professor, and Magnus Simrén, Professor and Senior Consultant, all at Sahlgrenska Academy, University of Gothenburg.
“With this study, we can show that diet plays a central role in the treatment of IBS, but that there are several alternative treatments that are effective,” says Sanna Nybacka.
“We need more knowledge about how to best personalise the treatment of IBS in the future and we will further investigate whether there are certain factors that can predict whether individuals will respond better to different treatment options,” she concludes.
A cheap and widely available prescription drug can improve symptoms of irritable bowel syndrome in patients seen in GP surgeries, according to research findings published in The Lancet and presented today at UEG Week 2023.
Amitriptyline, a tricyclic which is commonly used at low doses for a range of health concerns, has been found to improve irritable bowel syndrome (IBS) symptoms too, according to the results of the ATLANTIS trial.
The study was conducted in primary care, with GPs prescribing the drug and patients managing their own dose based on the severity of their symptoms, using an adjustment document designed for the trial. Most people with IBS are seen and managed in primary care by their GP, which means that the results of this trial are likely to be applicable to many people with the condition.
Led by researchers at the Universities of Leeds, Southampton, and Bristol and funded by the National Institute for Health and Care Research (NIHR), the study showed that patients taking amitriptyline were almost twice as likely to report an overall improvement in symptoms as those taking a placebo.
Now the trial team is recommending that GPs support their patients with IBS to use amitriptyline to manage their symptoms – and has made the dose adjustment document available for clinicians and patients.
Co-chief Investigator Alexander Ford, Professor of Gastroenterology in the University of Leeds’s School of Medicine, said: “Amitriptyline is an effective treatment for IBS and is safe and well tolerated. This new rigorously conducted research indicates that general practitioners should support patients in primary care to try low-dose amitriptyline if their IBS symptoms haven’t improved with recommended first-line treatments.”
Most treatments for IBS, which affects around 1 in 20 people, only have a modest effect and people often have ongoing troublesome symptoms.
Amitriptyline was originally used at high doses to treat depression, but is now superseded by newer and better antidepressants.
Previous small trials of low-dose tricyclic antidepressants for IBS suggested a possible benefit in patients seen in hospital clinics, who often have more difficult to treat symptoms, but this new study is the first randomised controlled trial of low-dose amitriptyline versus a placebo tablet for IBS in primary care. It is also the largest trial of amitriptyline for IBS undertaken worldwide.
GPs already prescribe low-dose amitriptyline to treat chronic nerve and back pain, and to help prevent migraine attacks. NICE guidelines currently state that GPs could consider using a low dose tricyclic, like amitriptyline, for IBS but, until now, the evidence for a benefit has been uncertain.
Based on the results of the trial, which showed a clear benefit of amitriptyline, GPs can offer low-dose amitriptyline to people with IBS as part of shared decision making if symptoms don’t improve with first-line treatments.
Co-chief Investigator Hazel Everitt, Professor of Primary Care Research at the Primary Care Research Centre, University of Southampton, said: “Prior to ATLANTIS, GPs haven’t often prescribed amitriptyline for IBS as the research evidence was uncertain, but our new research provides good evidence of benefit.
“GPs already prescribe low-dose amitriptyline for other conditions, such as chronic pain and poor sleep, and when we interviewed GPs as part of this research, they were willing to prescribe it for IBS if the research evidence supported this. Participants were also keen to have another option to try to help their IBS symptoms and most were happy to self-adjust their dose depending on symptoms and side effects.’’
Some 463 people with IBS took part, recruited from 55 general practices across the UK.
Participants were put at random into two groups – those receiving amitriptyline and those receiving a placebo. Participants controlled how many tablets of the trial medication they took, receiving support via the patient dose adjustment document that was developed with patient representatives especially for this trial. This enabled participants to increase or decrease the number of tablets based on their IBS symptoms and any side effects experienced.
IBS scores were measured using the IBS-SSS scale. Amitriptyline participants scored a 99-point improvement compared with a 69-point improvement among placebo participants.
Participants taking amitriptyline reported a bigger improvement in their symptom scores after six months compared with those taking a placebo. Those taking amitriptyline were almost twice as likely as those taking a placebo to report an overall improvement in IBS symptoms, with amitriptyline performing better across a wide range of IBS symptom measures.
Researchers monitored participants’ anxiety or depression scores and found that they were not altered – suggesting that the beneficial effects of the medication were via the gut, not because of any effect as an antidepressant.
No safety concerns were identified and side effects in people on amitriptyline were mostly mild, such as a dry mouth in the morning.
Matthew Ridd, GP and Professor of Primary Health Care at the Centre for Academic Primary Care, University of Bristol, said: “Pragmatic trials like this are always challenging to do in primary care and the team worked hard to overcome the additional challenges of the Covid-19 pandemic. It’s fantastic that we’ve found that amitriptyline is an effective and safe option for patients with IBS to try.”
Amanda Farrin, Professor of Clinical Trials and Evaluation of Complex Interventions, who leads the Complex Intervention Division of the Leeds Clinical Trials Research Unit, said: “The participants in the ATLANTIS trial had moderate to severe symptoms and an average duration of IBS of 10 years. The fact that amitriptyline had such a big effect over a placebo is significant because it can help improve the quality of life of patients with this condition.”
Professor Andrew Farmer, Director NIHR’s Health Technology Assessment (HTA) Programme, said: “The results of this study are hugely encouraging. It shows that a drug already widely available to treat a number of other conditions appears to be safe and effective for people with IBS. The findings the research team have shared around the adjustment of dosages can be tremendously helpful to GPs in guiding them when treating patients.
“IBS affects a significant number of people in the UK and can have a debilitating effect on their day-to-day lives. This is another excellent example of how high-quality research can lead to positive changes in health and social care practice and treatments for the benefit of patients and healthcare professionals.”
People with irritable bowel syndrome (IBS) have lower bacterial diversity in the intestine than do healthy people, according to research appearing in Microbiology Spectrum. The investigators believe that theirs is the first analysis to find a clear association between IBS and reduced diversity in the microbiota of the gut. The an open-access journal of the American Society for Microbiology.
Normally, “More than 10 000 species of microorganism live in the human intestine,” said corresponding author Jung Ok Shim, MD, PhD, a professor at Korea University College of Medicine. Disruption of the microbiome of the human gastrointestinal tract can trigger IBS. Typically, IBS causes bloating, diarrhoea, and stomach pain or cramps.
Previous studies of gut bacteria in patients with IBS have been controversial, with inconsistent results, due to small sample size and lack of consistent analytical methods used among these studies, said Shim. The investigators combined their own dataset with 9 published, shared datasets, encompassing 576 IBS patients and 487 healthy controls, analysing them with a “unified data processing and analytical method.”
The researchers found that the gut bacterial community is less diverse in IBS patients than in healthy people, said Shim. Additionally, the abundance of 21 bacterial species differed between IBS patients and healthy controls. However, the findings were not statistically significant in the paediatric cohort due to small sample size.
The investigators proved that the disturbed gut bacterial community “is associated with IBS, though this does not mean that the relationship is causal,” said Shim. “Functional studies are needed to prove whether the change in gut micro-organisms contributes to development of IBS.”
Even though IBS is a common disorder, its pathogenesis remains unknown, and as yet there is no effective treatment strategy. “Based on the epidemiological studies of IBS patients, altered gut microbiota was proposed as one of the possible causes of IBS,” the researchers write. “Acute bacterial gastroenteritis can cause chronic, asymptomatic, low-grade intestinal wall inflammation sufficient to alter neuromuscular and epithelial cell function.”
Using a wearable device to record nerve activity, researchers in Japan have discovered that the sympathetic nervous system of patients with irritable bowel syndrome (IBS) activated a few minutes before defecation, and persisted for a few minutes afterwards. Their results are published in the journal PLoS ONE.
Irritable bowel syndrome (IBS) is a difficult disease to treat, characterised by chronic abdominal pain related to bowel movements, of which there are four types: diarrhoeal, constipation, mixed, and unclassifiable. Patients with IBS report a reduction in quality of life and experiences of social discomfort, as they are forced to restrict their activity, such as work or travel, because of the sudden and unpredictable need to use the toilet. While there have been studies of IBS-related abnormalities in the autonomic nervous system based on 24-hour electrocardiogram measurement, until now none of them examined changes in the autonomic nervous system during bowel movements.
Associate Professor Fumio Tanaka and his research group at the Osaka Metropolitan University Graduate School of Medicine recorded the autonomic nervous system activity of IBS patients and healthy subjects using a wearable device and tracked activities such as defecation and sleep. As a result, they found that unlike healthy subjects, the sympathetic nervous system of IBS patients was activated two minutes before defecation and persisted until 9 minutes after defecation. Furthermore, the activation of the sympathetic nervous system was found to be associated with greater abdominal pain and lower quality of life.
“This research is characterised by the fact that autonomic nervous system functions are measured using a clothing-type wearable device, and that lifestyle events such as defecation and abdominal symptoms are input simultaneously in real time, using a smartphone application originally developed by our group. As a result, autonomic nervous system activity during defecation was accurately evaluated. We hope that further research will improve the quality of life of IBS patients and help elucidate the pathophysiology,” Professor Tanaka concluded.
Beneficial gut bacteria. Credit: Darryl Leja, National Human Genome Research Institute, National Institutes of Health
People who respond well to the irritable bowel syndrome (IBS) dietary therapy of reduced fermentable carbs have an abundance of particular types of bacteria in their gut, reveals research published online in the journal Gut.
The composition of the gut microbiome is thought to have a major role in the development of IBS. Restricting fermentable carbs, found in many foods including wheat, onions, and milk, is usually recommended to ease symptoms, an approach known as the low FODMAP (fermentable oligo-, di-, mono-saccharides and polyols) diet. But why this diet works is not fully understood.
In a bid to fill this knowledge gap, the researchers analysed stool samples of 56 people with IBS and 56 people who lived with them, but without the condition, to identify the microbial profile and genes involved in converting food into active molecules while on their usual diet.
They then assessed the clinical response in 41 of these pairs after 4 weeks on the low FODMAP diet by reviewing their stool samples again.
Before adoption of the low FODMAP diet, analysis of the stool samples of those with IBS revealed two distinct microbial ‘signatures’, which the researchers referred to as ‘pathogenic-like’ (IBSP) and as ‘health-like’ (IBSH).
The pathogenic microbial signature was abundant in harmful Firmicutes sp, including known disease causing bacteria, such as C. difficile, C. sordellii and C. perfringens, but very low in beneficial Bacteroidetes species.
The lactic acid bacteria Streptococcus parasanguinis and Streptococcus timonensis that are usually found in the mouth were also abundant. And bacterial genes for amino acid and carbohydrate metabolism were overexpressed, which may explain the excess of some metabolites that are linked to IBS symptoms, say the researchers.
The healthy microbial signature of the other IBS patients was similar to that found in the comparison group (household members).
After 4 weeks on the low FODMAP diet, the microbiome of the comparison group and those with the healthy microbial profile stayed the same.
But the microbiome of those with the pathogenic profile became healthier, with an increase in Bacteroidetes, and a fall in Firmicutes species. And the bacterial genes involved in the metabolism of amino acids and carbs were no longer overexpressed.
In 3 out of 4 of IBS patients, symptoms improved. But the clinical response to the low FODMAP diet was greater in those with IBS and a pathogenic microbial signature than it was in those with IBS and a healthy microbial signature in their gut.
“The evidence associating diet, the microbiome and symptoms in [pathogenic IBS] is compelling, but studies following the introduction of candidate organisms into an animal model are needed to prove the relationship is causal,” the researchers cautioned.
Nevertheless, they suggest their findings could lead to a microbial signature to identify those who would respond best to a low FODMAP diet and better manage those who wouldn’t.
“If the bacteria represented in the [pathogenic] subtype are shown to play a pathogenic role in IBS, perhaps through their metabolic activity, this provides a target for new therapies and an intermediate [marker] by which to assess them,” they suggest.
In a linked editorial, Professor Peter Gibson and Dr Emma Halmos of Melbourne’s Monash University, describe the introduction and adoption of the FODMAP diet as “a major change in the management of patients with irritable bowel syndrome (IBS) towards integrated care.
But while “an effective symptomatic therapy, [it’s] one that carries risks associated with exacerbating disordered eating, challenging nutritional adequacy and putatively inducing dysbiotic gut microbiota,” they added.
They point out some limitations of the research, including that FODMAP intake was poorly assessed, fibre intake,which can also influence the microbiome wasn’t reported and patient drop-out reduced the power of the study.
Nevertheless, the authors concluded that “the beauty of [the study] is not in its definitive nature, but that it enables the creation of feasible innovative hypotheses that can be examined by focused studies. Perhaps the FODMAP diet is not just a symptomatic therapy.”
Researchers have pinpointed a localised biological mechanism behind irritable bowel syndrome (IBS), a chronic gastrointestinal condition where eating certain foods causes subsequent abdominal pain or discomfort.
Around 20% of people experience IBS, and diets such as gluten-free ones provide some relief. However, the exact cause was unknown, as the patients did not have allergic responses nor did they have coeliac disease, causing many physicians to dismiss it as psychological.A healthy immune system tolerates foods, and the first link is understanding how the tolerance is removed. Previous work showed that there was a link between mast cells and food, and that blocking histamine in people with IBS relieved the symptoms.
People with IBS often report their symptoms begin following a gastrointestinal infection, so the researchers reasoned that an infection associated with a particular type of food in the guy might sensitise the immune system to that food.The team fed mice with ovalbumin (an egg protein) and then infected them with a stomach bug. The mice were then fed ovalbumin again, and the researchers recorded elevated mast cell activation, histamine levels and digestive intolerance. In control mice who were fed with ovalbumin but who were not infected with the stomach bug, there was no response.
Breaking down the chain of events leading to the sensitisation, the researchers discovered that there was a localised immune response in the part of the guy infected by the bacteria, but did not produce the more generalised symptoms of a food allergy.
Lead author Prof Guy Boeckxstaens, a gastroenterologist at KU Leuven thinks this may point to a spectrum of food-related immune disorders. He said, “At one end of the spectrum, the immune response to a food antigen is very local, as in IBS. At the other end of the spectrum is food allergy, comprising a generalised condition of severe mast cell activation, with an impact on breathing, blood pressure, and so on.”
When researchers injected IBS-associated food antigens into the intestinal walls of IBS patients, they observed localised reactions similar to what they saw in the mice, and there were no reactions in healthy patients. Larger clinical trials will be needed to confirm these observations.
“This is further proof that the mechanism we have unraveled has clinical relevance,” Prof Guy Boeckxstaens said. “But knowing the mechanism that leads to mast cell activation is crucial, and will lead to novel therapies for these patients,” he goes on. “Mast cells release many more compounds and mediators than just histamine, so if you can block the activation of these cells, I believe you will have a much more efficient therapy.”
