Category: Gastrointestinal

Inflammatory Bowel Disease may Increase Risk of Heart Failure

Irritable bowel syndrome. Credit: Scientific Animations CC4.0

Inflammatory bowel disease (IBD) is associated with a slightly increased risk of heart failure up to 20 years after diagnosis, according to a comprehensive registry study from Karolinska Institutet published in the European Heart Journal.

The researchers analysed the risk of heart failure in over 80 000 patients with inflammatory bowel disease, that is, Crohn’s disease, ulcerative colitis or unclassified IBD, compared with 400 000 people from the general population, as part of the ESPRESSO study.

The results show that people with IBD have a 19% increased risk of developing heart failure up to 20 years after diagnosis. This corresponds to one extra heart failure case per 130 IBD patients in those 20 years, and the risk increase was seen regardless of the type of IBD. The highest risk of heart failure was seen in older patients, people with lower education and people with pre-existing cardiovascular-related disease at IBD diagnosis.

Contribute to new guidelines

“Both healthcare providers and patients should be aware of this increased risk, and it’s important that cardiovascular health is properly monitored,” says the study’s first author Jiangwei Sun, researcher at the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet. “We hope the results will raise the awareness of health workers as to the increased risk of heart failure in individuals with IBD and contribute to new guidelines for cardiovascular disease management in IBD patients.”

Comparing siblings with and without ABD, the risk increase was slightly lower, 10%, suggesting that genetics and early environmental factors shared within families may play a role. 

“We don’t know if there is a causal relationship, but we will continue to explore genetic factors and the role of IBD medications and disease activities on the risk of heart failure,” says the study’s senior author Professor Jonas F. Ludvigsson from the Department of Medical Epidemiology and Biostatistics, Karolinska Institutet.

Source: Karolinska Institutet

Bitter Compounds Increase Stomach Acidity – But How?

Photo by Mike Kenneally on Unsplash

In the stomach, so-called parietal cells are responsible for acid production. They react not only to the body’s own messenger molecules, but also to bitter-tasting food constituents such as caffeine. In a study published in the Journal of Agricultural and Food Chemistry, researchers tested bitter compounds on a human gastric cell line. Their results help to clarify the molecular regulatory mechanisms by which bitter substances influence gastric acid production.

It is known that taste receptors for bitter substances are not only found on the tongue, but also on the surface of other tissues and cells. These include the parietal cells of the stomach, which secrete protons into the stomach – ie, produce gastric acid. Recent studies have already shown that the bitter taste receptors found in parietal cells are involved in the regulation of gastric acid release. However, the underlying molecular signaling pathways are not yet fully understood.

Gastric cells as a test system

To further clarify the molecular interaction between bitter substances, bitter taste receptors, and gastric acid production, a research team led by Veronika Somoza, Director of the Leibniz Institute in Freising, has carried out a study on a cellular test system. This involves human parietal HGT-1 cells, which are able to secrete protons and, like taste cells, have bitter taste receptors.

Veronika Somoza’s team initially developed a working hypothesis based on the results of previous studies and the findings on signal transduction pathways in taste cells. According to this hypothesis, bitter tasting food constituents stimulate bitter taste receptors that are embedded in the cell membrane. This releases calcium ions inside the cells, leading to ion channel opening. This, in turn, allows sodium ions to flow into the gastric cells from the outside, ultimately contributing to the release of protons.

Hypothesis confirmed

First author Phil Richter explains: “We have successfully tested this mechanism with the two bitter substances caffeine and l-arginine. As expected from previous results, both food constituents were shown to stimulate gastric cell proton secretion in our test system.” The PhD student adds: “For the first time, we were able to demonstrate that the transient receptor potential channelsM4 and M5 are involved in the signaling cascade not only in taste cells but also in gastric cells and ensure an influx of sodium ions into the cells.”

Senior Scientist Gaby Andersen says: “By using knock-out experiments, in which we specifically switched off one type of bitter taste receptor in the cells, we were also able to show for the first time that there is a link between bitter taste receptors and the activation of the ion channels.” The scientist emphasizes that the results not only contribute to a better understanding of the role of taste receptors in the stomach but would also show that HGT-1 cells could be suitable as a replacement model for taste cells.

The research team agrees that the results will provide new insights into the regulation of gastric acid production and thus lead to innovative approaches in treating gastric diseases in the long term. However, further studies are needed to deepen knowledge of the molecular regulatory mechanisms and intracellular signaling pathways.

Source: Leibniz-Institut für Lebensmittel-Systembiologie an der TU München

Intermittent Fasting Protects against Liver Inflammation and Liver Cancer

Photo by jamie he

Fatty liver disease often leads to chronic liver inflammation and can even result in liver cancer. Scientists from the German Cancer Research Center (DKFZ) and the University of Tübingen have now shown in mice* that intermittent fasting on a five days on, two days off schedule can halt this development.

In mice with pre-existing liver inflammation, this fasting regime reduces the development of liver cancer . The researchers also identified two proteins in liver cells that are jointly responsible for the protective effect of fasting. An existing drug can partially mimic this effect.

The most common chronic liver condition is non-alcoholic fatty liver disease. If left untreated, it can lead to liver inflammation (metabolic dysfunction-associated steatohepatitis, MASH), liver cirrhosis and even liver cancer. Fatty liver disease is largely considered to be a direct consequence of obesity.

“The vicious circle of an unhealthy diet, obesity, liver inflammation and liver cancer is associated with major restrictions and suffering for those affected and also represents a considerable burden on healthcare systems,” says Mathias Heikenwälder, DKFZ and University of Tübingen. “We have therefore investigated whether simple dietary changes can specifically interrupt this fatal process.”

Intermittent fasting has already been shown in several studies to be an effective means of reducing weight and alleviating certain metabolic disorders. Heikenwälder’s team has now tested in mice whether this approach can also protect the liver from fatty degeneration and chronic inflammation. Their results are published in Cell Metabolism.

Resistance to liver inflammation is independent of calorie intake

The animals were fed with a high-sugar and high-fat diet corresponding to the typical Western diet. One group of mice had constant access to the food. As expected, these animals gained weight and body fat and developed chronic liver inflammation.

The mice in the other group were given nothing to eat on two days a week (5:2 intermittent fasting, or 5:2 IF for short), but were allowed to eat as much as they wished on the other days. Despite the high-calorie diet, these animals did not put on weight, showed fewer signs of liver disease and had lower levels of biomarkers that indicate liver damage. In short, they were resistant to the development of MASH.

Interestingly, resistance to the development of a fatty liver was independent of the total calorie intake, as the animals immediately made up for the lost rations after the end of the fasting periods.

When experimenting with different variants of intermittent fasting, it was found that several parameters determine protection against liver inflammation: The number and duration of fasting cycles play a role, as does the start of the fasting phase. A 5:2 dietary pattern works better than 6:1; 24-hour fasting phases better than 12-hour ones. A particularly unhealthy diet requires more frequent dieting cycles.

Heikenwälder’s team now wanted to find out the molecular background of the response to fasting. To this end, the researchers compared protein composition, metabolic pathways and gene activity in the liver of fasting and non-fasting mice. Two main players responsible for the protective fasting response emerged: the transcription factor PPARα and the enzyme PCK1. The two molecular players work together to increase the breakdown of fatty acids and gluconeogenesis and inhibit the build-up of fats.

“The fasting cycles lead to profound metabolic changes, which together act as beneficial detoxification mechanisms and help to combat MASH,” says Heikenwälder, summarizing the molecular details.

The fact that these correlations are not just a mouse phenomenon was shown when tissue samples from MASH patients were examined: Here, too, the researchers found the same molecular pattern with reduced PPAR α and PCK1. Are PPAR α and PCK1 actually responsible for the beneficial effects of fasting? When both proteins were genetically switched off simultaneously in the liver cells of the mice, intermittent fasting was unable to prevent either chronic inflammation or fibrosis.

The drug pemafibrate mimics the effects of PPARα in the cell. Can the substance also mimic the protective effect of fasting? The researchers investigated this question in mice. Pemafibrate induced some of the favourable metabolic changes that were observed with 5:2 fasting. However, it was only able to partially mimic the protective effects of fasting. “This is hardly surprising, as we can only influence one of the two key players with pemafibrate. Unfortunately, a drug that mimics the effects of PCK1 is not yet available,” explains Mathias Heikenwälder.

Intermittent fasting as liver therapy

While Heikenwälder and his team initially focused on the effects of intermittent fasting on MASH prevention, then investigated whether the 5:2 diet could also alleviate existing chronic liver inflammation.

To this end, the team examined mice that had developed MASH after months of being fed a high-sugar, high-fat diet. After a further four months of 5:2 intermittent fasting (on the same diet), these animals were compared with the non-fasting control group. The fasting mice had better blood values, less fatty liver and liver inflammation and above all: they developed less liver cancer and had fewer cancer foci in the liver.

“This shows us that 5:2 intermittent fasting has great potential – both in the prevention of MASH and liver cancer, as well as in the treatment of established chronic liver inflammation,” summarises principal investigator Heikenwälder. “The promising results justify studies in patients to find out whether intermittent fasting protects against chronic liver inflammation as well as in the mouse model.”

The 5:2 fasting regimen is popular. It is considered comparatively easy to integrate into everyday life, as the fasting days can be tailored to personal needs and no specific foods are prohibited. “Nevertheless, there will always be people who can’t stick to a strict diet in the long term,” says Heikenwälder. “That’s why we want to continue to investigate which combinations of drugs we can use to fully mimic the protective effects of fasting.”

Source: German Cancer Research Center (Deutsches Krebsforschungszentrum, DKFZ)

Acid-lowering Meds Linked to Greater Risk of Migraines

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People who take acid-reducing drugs may have a higher risk of migraine and other severe headache than people who do not take these medications, a new study has shown. The acid-reducing drugs include proton pump inhibitors such as omeprazole and esomeprazole, histamine H2-receptor antagonists, or H2 blockers, such as cimetidine and famotidine, and antacid supplements.

The study, study published in Neurology®Clinical Practice, an official journal of the American Academy of Neurology, does not prove causation; only an association.

In acid reflux, stomach acid flows into the oesophagus, usually after a meal or when lying down, causing heartburn and ulcers. People with frequent acid reflux may develop gastroesophageal reflux disease, or GORD, which can lead to cancer of the oesophagus.

“Given the wide usage of acid-reducing drugs and these potential implications with migraine, these results warrant further investigation,” said study author Margaret Slavin, PhD, RDN, of the University of Maryland in College Park. “These drugs are often considered to be overprescribed, and new research has shown other risks tied to long-term use of proton pump inhibitors, such as an increased risk of dementia.”

For the study, researchers looked at data on 11,818 people who provided information on use of acid-reducing drugs and whether they had migraine or severe headache in the past three months.

A total of 25% of participants taking proton pump inhibitors had migraine or severe headache, compared to 19% of those who were not taking the drugs. A total of 25% of those taking H2 blockers had severe headache, compared to 20% of those who were not taking those drugs. And 22% of those taking antacid supplements had severe headache, compared to 20% of those not taking antacids.

When researchers adjusted for other factors that could affect the risk of migraine, such as age, sex and use of caffeine and alcohol, they found that people taking proton pump inhibitors were 70% more likely to have migraine than people not taking proton pump inhibitors. Those taking H2 blockers were 40% more likely and those taking antacid supplements were 30% more likely.

“It’s important to note that many people do need acid-reducing medications to manage acid reflux or other conditions, and people with migraine or severe headache who are taking these drugs or supplements should talk with their doctors about whether they should continue,” Slavin said.

Slavin noted that the study looked only at prescription drugs. Some of the drugs became available for over-the-counter use at non-prescription strength during the study period, but use of these over-the-counter drugs was not included in this study.

Other studies have shown that people with gastrointestinal conditions may be more likely to have migraine, but Slavin said that relationship is not likely to fully explain the tie between acid-reducing drugs and migraine found in the study.

A limitation of the study is that a small number of people were taking the drugs, especially the H2 blockers.

Source: American Academy of Neurology

Dietary Intervention Trumps Drugs for IBS Treatment

Irritable bowel syndrome. Credit: Scientific Animations CC4.0

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.

Source: University of Gothenburg

Deprescribing Efforts Shows that PPI Risks are Less than Expected

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Whether it’s costs, safety risks or “pill fatigue” they’re trying to reduce, many health systems and clinics have started working on ways to encourage deprescribing of medications that patients may not need. Now, a new study published in the BMJ shows the potential promise, and pitfalls, of a massive effort to reduce overuse of proton pump inhibitors (PPIs), widely prescribed for heartburn.

The findings also reveal that some of the feared risks from PPIs may be overblown.

The U.S. study tracks the impact of an intervention that imposed limits on PPI prescription size and refills for patients without a documented reason to be on the medication, discontinued old prescriptions, and provided education to patients and clinicians on alternatives.

The effort was carried out in one region of the Veterans Health Administration system, called VISN 17, and involved a quarter of a million patients, making it one of the largest ever studies on deprescribing.

Key findings

In all, the intervention led to a massive reduction in PPI use: a nearly 30% reduction in prescriptions of PPIs compared to other VA regions.

But the drive to reduce potentially unnecessary PPI use had one unintended consequence: a drop in prescribing to veterans who actually have an ongoing need to take PPIs because their other medicines carry a high risk of gastrointestinal bleeding. Strong evidence shows that PPIs are effective for preventing gastrointestinal bleeding and they are recommended in clinical guidelines.

Reassuringly, no matter the reason for taking PPIs, the deprescribing effort didn’t lead to increases in health care visits with gastrointestinal diagnoses. Nor did it lead to increases in gastrointestinal bleeding in patients at high risk, which suggests that the deprescribing initiative itself was safe.

Interestingly, the rate of purported negative PPI effects, such as kidney disease, stroke, heart attack or pneumonia, didn’t go down in VISN17 relative to the other regions. Hip fractures, another risk linked with PPIs in past studies, only went down by a small percentage.

This supports evidence from other high-quality studies that suggest PPIs may be a marker of patients at risk for certain adverse outcomes, but that the drugs are unlikely to be the cause.

For this reason, the main benefits to deprescribing PPIs have more to do with cost and hassle of taking more pills than clinical risk reduction.

More about the study

The new VA-funded study uses data from multiple years before and after VISN 17 implemented its PPI deprescribing program for most veterans living in Texas, and parts of New Mexico and Oklahoma.

It was led by a multi-institutional team that includes investigators from University of Michigan and the VA Center for Clinical Management Research (CCMR) in Ann Arbor; the University of Pennsylvania and the VA Center for Health Equity Research and Promotion (CHERP) in Philadelphia; and the Yale School of Medicine and VA Center for Pain Research, Informatics, Multi-morbidities, and Education (PRIME).

“This intervention worked so well because it was involuntary to some degree – refills could no longer be on autopilot for patients without a clear indication for the medication,” says Jacob Kurlander, MD, MS, first author of the study and a gastroenterologist at Michigan Medicine, U-M’s academic medical center, and the Lieutenant Colonel Charles S. Kettles VA Ann Arbor Medical Center. “At the same time, what we saw is that is that patients who benefit from PPIs for bleeding prevention – which is sometimes overlooked by doctors – got swept up in this effort, too.”

This signals that deprescribing efforts need to take even more care to ensure providers don’t allow a patient who has a need for the drug to inadvertently go off it, Kurlander said.

“Our findings also suggest that PPIs may not be as harmful as some have feared,” he adds.

Before the VISN 17 program started, about 26% of veterans across the country who got their primary care from a VA provider were prescribed a PPI in a six-month period.

By the end of the study period in 2019, only about 15% of veterans in VISN 17 had a PPI prescription, compared with about 22% of those in the other regions.

This means PPI prescribing dropped by 30% within VISN 17, and that there was more than a 7% absolute reduction in PPI use between VISN 17 and other regions by the end of the study period.

The researchers even connected veterans’ VA records with their Medicare data in case they received care outside the VA, and also used information from death certificates to look for causes of cardiovascular-related death. There were no differences between VISN 17 and the other regions.

Bacteria Subtype Linked to Growth in up to 50% of Human Colorectal Cancers

Human colon cancer cells. Credit: National Cancer Institute

Researchers at Fred Hutchinson Cancer Center have found that a specific subtype of a microbe commonly found in the mouth is able to travel to the gut and grow within colorectal cancer tumours. This microbe is also a culprit for driving cancer progression and leads to poorer patient outcomes after cancer treatment.

The findings, published in Nature, could help improve therapeutic approaches and early screening methods for colorectal cancer, which is the second most common cause of cancer deaths in adults in the U.S. according to the American Cancer Society.

Examining colorectal cancer tumours removed from 200 patients, the Fred Hutch team measured levels of Fusobacterium nucleatum, a bacterium known to infect tumours. In about 50% of the cases, they found that only a specific subtype of the bacterium was elevated in the tumour tissue compared to healthy tissue.

The researchers also found this microbe in higher numbers within stool samples of colorectal cancer patients compared with stool samples from healthy people.

“We’ve consistently seen that patients with colorectal tumours containing Fusobacterium nucleatum have poor survival and poorer prognosis compared with patients without the microbe,” explained Susan Bullman, PhD, Fred Hutch cancer microbiome researcher and co-corresponding study author. “Now we’re finding that a specific subtype of this microbe is responsible for tumour growth. It suggests therapeutics and screening that target this subgroup within the microbiota would help people who are at a higher risk for more aggressive colorectal cancer.”

In the study, Bullman and co-corresponding author Christopher D. Johnston, PhD, Fred Hutch molecular microbiologist, along with the study’s first author Martha Zepeda-Rivera, PhD, a Washington Research Foundation Fellow and Staff Scientist in the Johnston Lab, wanted to discover how the microbe moves from its typical environment of the mouth to a distant site in the lower gut and how it contributes to cancer growth.

First they found a surprise that could be important for future treatments. The predominant group of Fusobacterium nucleatum in colorectal cancer tumours, thought to be a single subspecies, is actually composed of two distinct lineages known as “clades.”

“This discovery was similar to stumbling upon the Rosetta Stone in terms of genetics,” Johnston explained. “We have bacterial strains that are so phylogenetically close that we thought of them as the same thing, but now we see an enormous difference between their relative abundance in tumours versus the oral cavity.”

By separating out the genetic differences between these clades, the researchers found that the tumour-infiltrating Fna C2 type had acquired distinct genetic traits suggesting it could travel from the mouth through the stomach, withstand stomach acid and then grow in the lower gastrointestinal tract. The analysis revealed 195 genetic differences between the clades.

Then, comparing tumour tissue with healthy tissue from patients with colorectal cancer, the researchers found that only the subtype Fna C2 is significantly enriched in colorectal tumour tissue and is responsible for colorectal cancer growth.

Further molecular analyses of two patient cohorts, including over 200 colorectal tumours, revealed the presence of this Fna C2 lineage in approximately 50% of cases.

The researchers also found in hundreds of stool samples from people with and without colorectal cancer that Fna C2 levels were consistently higher in colorectal cancer.

“We have pinpointed the exact bacterial lineage that is associated with colorectal cancer, and that knowledge is critical for developing effective preventive and treatment methods,” Johnston said.

Source: Fred Hutchinson Cancer Center

Certain Gut Bacteria Linked to Reduced Cardiovascular Disease Risk

Gut Microbiome. Credit Darryl Leja National Human Genome Research Institute National Institutes Of Health

Changes in the gut microbiome have been implicated in a range of diseases including type 2 diabetes, obesity, and inflammatory bowel disease. Now, a team of researchers has found that microbes in the gut may affect cardiovascular disease as well. In a study published in Cell, the team has identified specific species of bacteria that consume cholesterol in the gut and may help lower cholesterol and heart disease risk in people.

Researchers at the Broad Institute of MIT and Harvard along with Massachusetts General Hospital analysed metabolites and microbial genomes from more than 1400 participants in the Framingham Heart Study, a decades-long project focused on risk factors for cardiovascular disease.

The team discovered that bacteria called Oscillibacter take up and metabolise cholesterol from their surroundings, and that people carrying higher levels of the microbe in their gut had lower levels of cholesterol. They also identified the mechanism the bacteria likely use to break down cholesterol. The results suggest that interventions that manipulate the microbiome in specific ways could one day help decrease cholesterol in people. The findings also lay the groundwork for more targeted investigations of how changes to the microbiome affect health and disease.

“Our research integrates findings from human subjects with experimental validation to ensure we achieve actionable mechanistic insight that will serve as starting points to improve cardiovascular health,” said Xavier, who is a core institute member and a professor at Harvard Medical School and Massachusetts General Hospital.

Postdoctoral researcher Chenhao Li and research scientist Martin Stražar, both in Xavier’s lab, were co-first authors on the study.

Cholesterol cues

In the past decade, other researchers have uncovered links between composition of the gut microbiome and elements of cardiovascular disease, such as a person’s triglycerides and blood sugar levels after a meal. But scientists haven’t been able to target those connections with therapies in part because they lack a complete understanding of metabolic pathways in the gut.

In the new study, the Broad team gained a more complete and detailed picture of the impact of gut microbes on metabolism. They combined shotgun metagenomic sequencing, which profiles all of the microbial DNA in a sample, with metabolomics, which measures the levels of hundreds of known and thousands of unknown metabolites. They used these tools to study stool samples from the Framingham Heart Study.

“The project outcomes underline the importance of high-quality, curated patient data,” Stražar said. “That allowed us to note effects that are really subtle and hard to measure and directly follow up on them.”

More than 16 000 associations between microbes and metabolic traits were found, one of them particularly strong: People with several species of bacteria from the Oscillibacter genus had lower cholesterol levels than those who lacked the bacteria. The researchers found that species in the Oscillibacter genus were surprisingly abundant in the gut, representing on average 1 in every 100 bacteria.

The researchers then wanted to figure out the biochemical pathway the microbes use to break down cholesterol. To do this, they first needed to grow the organism in the lab. Fortunately, the lab has spent years collecting bacteria from stool samples to create a unique library that also included Oscillibacter.

After successfully growing the bacteria, the team used mass spectrometry to identify the most likely byproducts of cholesterol metabolism in the bacteria. This allowed them to determine the pathways the bacteria uses to lower cholesterol levels. They found that the bacteria converted cholesterol into intermediate products that can then be broken down by other bacteria and excreted from the body. Next, the team used machine-learning models to identify the candidate enzymes responsible for this biochemical conversion, and then detected those enzymes and cholesterol breakdown products specifically in certain Oscillibacter in the lab.

The team found another gut bacterial species, Eubacterium coprostanoligenes, that also contributes to decreased cholesterol levels. This species carries a gene that the scientists had previously shown is involved in cholesterol metabolism. In the new work, the team discovered that Eubacterium might have a synergistic effect with Oscillibacter on cholesterol levels, which suggests that new experiments that study combinations of bacterial species could help shed light on how different microbial communities interact to affect human health.

Microbial messages

The human gut microbiome remains mostly unmapped, but the team believes they have paved the way for the discovery of other similar metabolic pathways impacted by gut microbes, which could be targeted therapeutically.

“There are many clinical studies trying to do faecal microbiome transfer studies without much understanding of how the microbes interact with each other and the gut,” Li said. “Hopefully stepping back by focusing on one particular bug or gene first, we’ll get a systematic understanding of gut ecology and come up with better therapeutic strategies like targeting one or a few bugs.”

“Because of the large number of genes of unknown function in the gut microbiome, there are gaps in our ability to predict metabolic functions,” Li added. “Our work highlights the possibility that additional sterol metabolism pathways may be modified by gut microbes. There are potentially a lot of new discoveries to be made that will bring us closer to a mechanistic understanding of how microbes interact with the host.”

Source: Broad Institute of MIT and Harvard

Common Respiratory Viruses Trigger Most Cases of Intussusception in Children

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Viral infections trigger more cases of intussusception in young children than previously thought, according to a new study. The research, led by Murdoch Children’s Research Institute (MCRI) and published in Clinical Infectious Diseases, found that during the COVID lockdowns, hospital admissions for intussusception, a medical emergency involving obstruction of the intestine, among young children significantly decreased.

For the study, 12 years of data was analysed across Victoria, NSW and Queensland. A total of 5589 intussusception cases were recorded between January, 2010 and April, 2022. Of those, 3179 were children under the age of two.

During the lockdown periods, Victoria and NSW experienced a decline in hospital admissions for intussusception among children under two by 62.7% and 40.1%, respectively. The rate of intussusception cases has now returned to normal levels.

MCRI and Monash University researcher Dr Ben Townley said the magnitude of the decline supported that common respiratory diseases such as colds, the flu and respiratory syncytial virus (RSV), were behind a significant proportion of intussusception cases.

“Reductions in intussusception hospital admissions were seen in all age groups, however most occurred in children less than two years of age,” he said.

“Intussusception is the leading cause of acute bowel obstruction in infants and young children and without prompt diagnosis and management, can be fatal.

“Countries with prolonged COVID lockdowns and suppression strategies saw reductions in common respiratory viruses, which influenced the drop in intussusception admissions.”

Victoria experienced the greatest lockdown duration, with Melbourne having six lockdown periods, for a total of 263 days. Greater Sydney had 159 days and Brisbane had 18 days in lockdown.

MCRI Professor Jim Buttery said the decrease in intussusception cases was greater than expected given previous research into the causes of the condition.

“Our analysis found commons viruses play a larger role than previously recognised in triggering intussusception,” he said.

Professor Buttery said the findings raised the possibility that emerging vaccines like the new RSV vaccines may help prevent intussusception.

“When a new vaccine against common childhood respiratory viruses is introduced, we may find there are some unexpected benefits, like protecting more children from intussusception,” he said.

Researchers from Sydney Children’s Hospital Network, University of Melbourne and Queensland Health also contributed to the findings.

Source: Murdoch Childrens Research Institute

Probing the Gut’s Ability to Change Size According to Nutrient Intake

Source: CC0

The gut has considerable plasticity among animals, shrinking as much 50% in cases of fasting such as hibernating and able to rapidly return to normal size on refeeding. Now, scientists from the University of Copenhagen used fruit flies to investigate the signalling mechanisms and cellular changes that regulate this rapidly renewable tissue, which could reveal insights into diseases such as colorectal cancer. Their results are published in Nature Communications.

“Taking advantage of the broad genetic toolbox available in the fruit fly, we have investigated the mechanisms underpinning nutrient-dependent gut resizing,” says Dr Ditte S. Andersen.

The results show that nutrient deprivation results in an accumulation of progenitor cells that fail to differentiate into the mature cells causing the gut to shrink.

Upon refeeding these stalled progenitor cells readily differentiate into mature cells to promote regrowth of the gut.

Ditte S. Andersen continues: “We have identified activins as critical regulators of this process. In nutrient restrictive conditions, activin signalling is strongly repressed, while it is reactivated and required for progenitor maturation and gut resizing in response to refeeding. Activin-dependent resizing of the gut is physiologically important as inhibition of activin signalling reduces survival of flies to intermittent fasting.”

Regulators of organ plasticity are essential for host adaptation to an ever-changing environment, however, the same signals are often deregulated in cancers. Indeed, mutations affecting activin signalling are frequent in cancer cells in a variety of tissues. This study provides a starting point for investigating the link between aberrant activin signalling and the development of colorectal cancers and sets the stage for exploring the efficiency of anti-activin therapeutic strategies in treating colorectal cancers.

Source: University of Copenhangen