Researchers have unlocked a means to modify the function of an enzyme crucial to fat production, a finding could lead to more effective treatments for childhood obesity and cancer.
While the research, published in the Proceedings of the National Academy of Sciences, was in fruit fly larvae, the ability to alter the rates of lipid metabolism could have significant implications for human health, said Hua Bai, an associate professor of genetics, development and cell biology at Iowa State University.
“We’ve identified what’s basically a metabolic switch. It’s like the accelerator on a car,” he said.
The initial aim was investigating how ageing was affected by fatty acid synthase, an enzyme that plays a role in de novo lipogenesis, which is the process of turning excess dietary carbohydrates into fat. Typically, levels of fatty acid synthase rise and fall based on an animal’s cellular needs and diet.
Surprisingly, the researchers noticed that early in a fruit fly’s development, de novo lipogenesis increases without an accompanying boost in the expression of fatty acid synthase. That suggested there must be some other factor at play, Bai said.
After proteins such as fatty acid synthase are created based on genetic code, their function can be altered by one of several different types of post-translational modification. Bai’s team found one of those processes, acetylation, affected one of the 2540 amino acids that combine to make fatty acid synthase, changing how effective it was at producing fat.
In addition to its role in obesity, elevated levels of de novo lipogenesis are linked to cancer, so controlling it through a single amino acid could lead to highly targeted treatments, Bai said.
“Fine tuning the acetylation levels of fatty acid synthase would be a much more precise treatment than blocking the entire protein,” he said.
Though the findings may be applicable to humans, any medical application in humans is years away, he said.
“The potential is high, but further testing is needed in other animals,” he said.
A newly published study in iScience sheds light on the biological underpinnings in sex differences in obesity-related disease, with researchers observing “striking” differences in the cells that build blood vessels in the fatty tissue of male versus female mice.
Men are more likely than women to develop conditions associated with obesity such as cardiovascular disease, insulin resistance and diabetes, says study leader Professor Tara Haas at York University.
“People have used rodent models to study obesity, and the diseases that are associated with obesity – like diabetes – but they’ve typically always studied male rodents, because females are resistant to developing the same kinds of diseases,” says Haas. “We were really interested in exploring that difference because, to us, it spoke of something really fascinating happening in females that protects them.”
In earlier work, Haas and her team saw that when mice become obese, females grow a lot of new blood vessels to supply the expanding fat tissue with oxygen and nutrients, whereas males grow a lot less. For this study, Haas and her co-authors focused on differences in the endothelial cells that make up the building blocks of these blood vessels in fat tissue.
The team used software to help sift through thousands of genes to zero in on the ones that would be associated with blood vessel growth. They discovered that processes associated with the proliferation of new blood vessels were high in the female mice, whereas the males had a high level of processes associated with inflammation.
“It was very striking the extent of inflammation-associated processes that were prevalent in the males,” Haas recalls. “Other studies have shown that when endothelial cells have that kind of inflammatory response, they’re very dysfunctional, and they don’t respond to stimuli properly.”
York PhD student Alexandra Pislaru, who works in Haas’ lab and is a co-first author of the study, participated in this project as part of her dissertation.
“It is exciting to observe the continuing resilience that female endothelial cells display even when stressed by a long-term high-fat diet,” Pislaru says. “The findings from our study can help researchers to get a better understanding of why obesity manifests differently in men and women.”
The researchers also examined the behaviour of the endothelial cells when they were taken out of the body and studied in petri dishes.
“Even when we take them out of the body where they don’t have the circulating sex hormones or other kinds of factors, male and female endothelial cells still behave very differently from each other,” Haas explains.
Female endothelial cells replicated faster, while male endothelial cells displayed greater sensitivity to an inflammatory stimulus. By comparing with previously published data sets, the researchers found endothelial cells from aged male mice also displayed a more inflammatory profile compared to female cells.
“You can’t make the assumption that both sexes are going to respond to the same series of events the same way,” says Haas. “This isn’t just an obesity related issue – I think it’s a much broader conceptual problem that also encompasses healthy aging. One implication of our findings is that there will be situations where the treatment that is ideal for men is not going to be ideal for women and vice-versa.”
While humans and mice have different genes that may be turned up or down, Haas believes the general findings would likely apply and is interested studying the same cells in humans in future research.
New clinical guidelines from the American Academy of Pediatrics (AAP) advise “immediate, intensive obesity treatment to each patient” upon diagnosis of childhood obesity. Published in the journal Pediatrics, these recommendations stands in marked contrast from other, previous guidelines.
The guidelines are summarised in key action statements, some of which recommend children ages 6 and up (and sometimes 2 to 5) with overweight or obesity to intensive health behaviour and lifestyle therapy.
In children 12 and older, the guidelines advise consideration of weight-loss pharmacotherapy. In case of severe obesity (BMI ≥35 or 120% of the 95th percentile for age and sex, whichever is lower) for adolescents 13 and older, clinicians should offer referrals for evaluation for metabolic and bariatric surgery.
Author Sarah Armstrong, MD, co-director of the Duke Center for Childhood Obesity Research told Medpage Today that “This is one of the most important messages that differentiates our current clinical practice guidelines from the prior recommendations, and that is to say 15 years of data have taught us that ‘watchful waiting’ only leads to greater increase in child BMI, accumulation of comorbidities, and more challenges in trying to reverse some of this.”
The guidelines also recommend regularly screening children ages 2 years and up for obesity, and comprehensively evaluating children and adolescents with overweight and obesity for related comorbidities.
Clinicians are also advised to treat children and adolescents for overweight/obesity and comorbidities concurrently, in line with principles of the chronic care model, using a non-stigmatising approach centred around the family.
The guidelines are based on a comprehensive evidence review of controlled and comparative effectiveness trials and high-quality longitudinal and epidemiologic studies. In a pair of accompanying technical reports, the authors give detailed descriptions of the evidence review behind the development of the guidelines.
A new study, published in the International Journal of Obesity, found that 3-year-old children were more likely to exhibit risk factors for future heart disease if their mother was clinically obese during pregnancy. A behavioural lifestyle intervention reduced this risk.
There is increasing evidence to suggest that obesity in pregnancy is associated with cardiometabolic dysfunction in children, and that serious cardiovascular disease may begin in the womb.
The UPBEAT trial, conducted at Guy’s and St Thomas’ NHS Foundation Trust, randomised women with obesity (a BMI of over 30 kg/m2) in early pregnancy to a diet and exercise intervention or to standard pregnancy care. The intervention included one-to-one counselling, restricting dietary intake of saturated fat, eating foods with a low glycaemic index such as vegetables and legumes, moderate and monitored physical activity and tools to record exercise. The intervention arm saw improvements in weight gain in pregnancy, physical activity, a healthier diet, and a healthier metabolic profile across pregnancy.
Follow-up of the children at age three showed that children of women with clinical obesity had evidence of cardiac remodelling, a risk factor for future cardiovascular disease. Changes included increased heart muscle thickness, elevated resting heart rate, evidence of early impairment to the heart’s relaxation function and increased sympathetic nerve activity compared to women of normal weight. The children of women who were allocated to the intervention arm were protected from these early changes in heart structure and function.
Study lead Dr Paul Taylor, from King’s College London, said: “Maternal obesity appears to adversely impact the developing foetal nervous system and foetal heart development which is apparent up to 3 years-of-age. A complex lifestyle intervention in pregnancy was associated with protection against cardiac remodelling in infants. We can hypothesise that these changes to the heart and its function will get worse over time, putting the child at increased risk of cardiovascular disease in the future.”
The study suggests that maternal obesity may have a lasting impact on the child’s cardiovascular health. Promoting dietary changes and physical activity during pregnancy may reduce this risk.
Metabolites are the substances made and used during the body’s metabolic processes – or, as a new discovery out of Scripps Research and its drug development arm, Calibr, indicates, they could also be potent molecules for treating severe diseases.
In a study published in the journal Metabolites, the researchers used novel drug discovery technologies to uncover a metabolite that converts white adipocytes (‘bad’ fat cells) to brown adipocytes (‘good’ fat cells). This discovery suggests a pathway to treating metabolic disorders such as obesity, type 2 diabetes and cardiovascular disease. This creative drug discovery method could also identify countless other potential therapeutics.
“The reason many types of molecules don’t go to market is because of toxicity,” said co-senior author Gary Siuzdak, PhD. “With our technology, we can pull out endogenous metabolites – meaning the ones that the body makes on its own – that can have the same impact as a drug with less side effects. The potential of this approach is even evidenced by the FDA’s recent approval of Relyvrio, the combination of two endogenous metabolites for the treatment of amyotrophic lateral sclerosis (ALS).”
Metabolic diseases are often caused by an imbalance in energy homeostasis. This is why certain therapeutic approaches have centred around converting white adipocytes into brown adipocytes. White adipocytes store excess energy and can eventually result in metabolic diseases like obesity, while brown adipocytes dissolve this stored energy into heat – ultimately increasing the body’s energy expenditure and helping bring balance.
To uncover a therapy that could stimulate the production of brown adipocytes, the researchers searched through Calibr’s ReFRAME drug-repurposing collection – a library of 14 000 known drug compounds that have been approved by the FDA for other diseases or have been extensively tested for human safety. Using high-throughput screening – an automated drug discovery method for searching through large pools of information –the scientists scanned ReFRAME for a drug with these specific capabilities.
This is how they uncovered zafirlukast, an FDA-approved drug used for treating asthma. Through a set of cell culture experiments, they found zafirlukast could turn adipocyte precursor cells (known as preadipocytes) into predominantly brown adipocytes, as well as convert white adipocytes into brown adipocytes.
Unfortunately, zafirlukast is toxic at higher doses, and it wasn’t entirely clear how zafirlukast was converting the adipocytes. This is when the researchers partnered with Dr Siuzdak and his team of metabolite experts.
“We needed to use additional tools to break down the chemicals in zafirlukast’s mechanism,” explained Kristen Johnson, PhD, co-senior author of the paper. “Framed another way, could we find a metabolite that was providing the same functional effect that zafirlukast was, but without the side effects?”
Dr Siuzdak and his team designed a novel set of experiments, known as drug-initiated activity metabolomics (DIAM) screening, to help answer Johnson’s question. DIAM uses technologies such as liquid chromatography (a tool that separates components in a mixture) and mass spectrometry (an analytical technique that separates particles by weight and charge) to pool through thousands of molecules and identify specific metabolites. In this case, the researchers were searching through adipose tissue for metabolites that could lead to brown adipocyte cell production.
After reducing 30 000 metabolic features to just 17 metabolites, they came upon myristoylglycine – an endogenous metabolite that prompted the creation of brown adipocytes, without harming the cell. Of the thousands of metabolic features measured in the analysis, only myristoylglycine had this special characteristic, even among nearly structurally identical metabolites.
“Identifying myristoylglycine among the thousands of other molecules speaks to the power of Siuzdak’s approach and these technologies,” added Dr Johnson. “Our findings illustrate what happens when an analytical chemistry team and a drug discovery group closely collaborate with each other.”
While popular diets discourage midnight snacking, few studies have examined the simultaneous effects of late eating on the weight gain trifecta regulation of calorie intake, the number of calories burnt, and molecular changes in fat tissue. Now, a new study published in Cell Metabolism has found that timing of food intake significantly impacts energy expenditure, appetite, and molecular pathways in adipose tissue.
“We wanted to test the mechanisms that may explain why late eating increases obesity risk,” explained senior author Frank A. J. L. Scheer, PhD, Director of the Medical Chronobiology Program in the Brigham’s Division of Sleep and Circadian Disorders. “Previous research by us and others had shown that late eating is associated with increased obesity risk, increased body fat, and impaired weight loss success. We wanted to understand why.”
“In this study, we asked, ‘Does the time that we eat matter when everything else is kept consistent?'” said first author Nina Vujovic, PhD, a researcher in the Medical Chronobiology Program in the Brigham’s Division of Sleep and Circadian Disorders. “And we found that eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat.”
Vujovic, Scheer and their team studied 16 patients with a body mass index (BMI) in the overweight or obese range. Each participant completed two laboratory protocols: one with a strictly scheduled early meal schedule, and the other with the exact same meals, each scheduled about four hours later in the day. In the last two to three weeks before starting each of the in-laboratory protocols, participants maintained fixed sleep and wake schedules, and in the final three days before entering the laboratory, they strictly followed identical diets and meal schedules at home. In the lab, participants regularly documented their hunger and appetite, provided frequent small blood samples throughout the day, and had their body temperature and energy expenditure measured. To measure how eating time affected molecular pathways involved in adipogenesis, or how the body stores fat, investigators collected biopsies of adipose tissue from a subset of participants during laboratory testing in both the early and late eating protocols, to enable comparison of gene expression patterns/levels between these two eating conditions.
Results revealed that eating later had profound effects on hunger and appetite-regulating hormones leptin and ghrelin, which influence our drive to eat. Specifically, levels of the hormone leptin, which signals satiety, were decreased across the 24 hours in the late eating condition compared to the early eating conditions. When participants ate later, they also burned calories at a slower rate and exhibited adipose tissue gene expression towards increased adipogenesis and decreased lipolysis, which promote fat growth. Notably, these findings convey converging physiological and molecular mechanisms underlying the correlation between late eating and increased obesity risk.
Vujovic explained that these findings are not only consistent with a large body of research suggesting that eating later increases risk of developing obesity, but they shed new light on how this might occur. By using a randomised crossover study, and tightly controlling for behavioural and environmental factors such as physical activity, posture, sleep, and light exposure, investigators were able to detect changes the different control systems involved in energy balance, a marker of how our bodies use the food we consume.
Future studies will include more female participants. Despite only five female participants, the study was set up to control for menstrual phase, reducing confounding but making recruiting women more difficult. Going forward, Scheer and Vujovic are also interested in better understanding the effects of the relationship between meal time and bedtime on energy balance.
“This study shows the impact of late versus early eating. Here, we isolated these effects by controlling for confounding variables like caloric intake, physical activity, sleep, and light exposure, but in real life, many of these factors may themselves be influenced by meal timing,” said Scheer. “In larger scale studies, where tight control of all these factors is not feasible, we must at least consider how other behavioural and environmental variables alter these biological pathways underlying obesity risk. “
A world-first study published in the journal Diabetes, Obesity and Metabolism, has uncovered an association between metabolism and dementia-related brain measures, providing valuable insights about the disease.
Analysing UK Biobank data from 26 239 people, University of South Australia researchers found that those with obesity related to liver stress, or to inflammation and kidney stress, had the most adverse brain findings.
The study measured associations of six diverse metabolic profiles and 39 cardiometabolic markers, using MRI brain scan measures of brain volume, brain lesions, and iron accumulation, to identify early risk factors for dementia.
Participants with metabolic profiles associated with obesity were more likely to have adverse MRI profiles showing lower hippocampal and grey matter volumes, greater burden of brain lesions, and higher accumulation of iron.
UniSA researcher, Dr Amanda Lumsden, says the research adds a new layer of understanding to brain health.
“Dementia is a debilitating disease that affects more than 55 million people worldwide,” Dr Lumsden said.
“Understanding metabolic factors and profiles associated with dementia-related brain changes can help identify early risk factors for dementia.
“In this research, we found that adverse neuroimaging patterns were more prevalent among people who had metabolic types related to obesity.
“These people also had the highest Basal Metabolic Rate (BMR) -how much energy your body requires when resting in order to support its basic functions — but curiously, BMR seemed to contribute to adverse brain markers over and above the effects of obesity.”
Senior investigator Professor Elina Hyppönen said that the finding presents a new avenue for understanding brain health.
“This study indicates that metabolic profiles are associated with aspects of brain health. We also found associations with many individual biomarkers which may provide clues into the processes leading to dementia,” said Prof Hyppönen.
“The human body is complex, and more work is now needed to find out exactly why and how these associations arise.”
A recent study has found that children born to women with gestational diabetes and obesity may have twice the risk of developing attention-deficit/hyperactivity disorder (ADHD) compared to those born to mothers without obesity. The findings, published in the Journal of Clinical Endocrinology & Metabolism, also found found that in women with a healthy weight gain during pregnancy, this risk increase was not seen.
ADHD is a growing problem. According to data from 2016-2019, 6 million children aged 3–17 years have received an ADHD. Maternal obesity is a major risk factor for ADHD in children, and roughly 30% of women have obesity at their first doctor’s visit during pregnancy, rising to 47% in women with gestational diabetes. Excessive weight gain during pregnancy in this population is a risk factor for children developing ADHD.
“Our study found pregnant women with obesity and gestational diabetes had children with long-term mental health disorders such as ADHD,” said Verónica Perea, MD, PhD, of the Hospital Universitari Mutua Terrassa in Barcelona. “We did not find this association when these women gained a healthy amount of weight during pregnancy.”
Studying 1036 children born to women with gestational diabetes, the researchers found that 13% of these children were diagnosed with ADHD. When compared to mothers without obesity, the researchers found children of women with gestational diabetes and obesity were twice as likely to have ADHD compared to those born to mothers without obesity.
Notably, this association was only seen in women with gestational diabetes, obesity and excessive weight gain during pregnancy. There was no increased risk of ADHD in children of women with gestational diabetes and obesity if the amount of weight these women gained during pregnancy was within the normal range.
“It’s important for clinicians to counsel their patients on the importance of healthy weight gain during pregnancy,” Perea said.
A new Australian and New Zealand Journal of Public Health study has found that Australian children who were born via caesarean section (C-section) have a greater risk of cardiovascular disease (CVD) and obesity. These findings have prompted a call to limit the increasingly popular practice.
According to a Lancet review, C-sections are already known to have a number of negative outcomes, with evidence higher rates of maternal mortality and morbidity than after vaginal birth. C-sections are further associated with an increased risk of uterine rupture, abnormal placentation, ectopic pregnancy, stillbirth, and preterm birth. Short-term risks of C-section include altered immune development, an increased likelihood of allergy, atopy, and asthma, and reduced gut microbiome diversity. Associations of C-section with greater incidence of late childhood obesity and asthma are frequently reported.
Researchers used data from the Longitudinal Study of Australian Children to analyse the health outcomes of children delivered by C-section.
“C-section births have risen across the world with a disproportionately higher rate in developed countries. In Australia, the C-section birth rate has increased from 18.5% in 1990 to 36% in 2019 and nearly half of Australian babies are projected to be caesarean born by 2045,” said study author Dr Tahmina Begum.
A relationship was discovered between C-section births and certain cardiovascular disease (CVD) risk factors in children.
“Four out of six individual CVD risk components and the composite index of the five CVD risk components showed a positive association with C-section birth. Our study also provided a direct relationship between C-section and increased overweight and obesity among children at 10–12 years of age,” said Dr Fatima.
A biologically plausible link involved the gut microbiome, she said. “There’s an altered microbial load from C-section birth as compared to vaginal birth. This altered microbial ecosystem hampers the ‘gut-brain axis’ and releases some pathogenic toxins that cause metabolic damage.”
Other possible causes included foetal stress from physiological or pharmacological induction of labour during a C-section. She said the study provides important insights into health care policy and the strategic direction towards chronic disease risk reduction.
“Growing rates of C-sections conducted for non-clinical reasons is a major public health concern that calls for a reduction in the rate of unnecessary C-sections and their associated human and economic costs,” said Dr Begum.
A 3D map of the islets in the human pancreas. Source: Wikimedia
Oregon State University researchers have used a new analytical method to shed light on an enduring mystery in type 2 diabetes: why some obese patients develop diabetes and others don’t. The reason is down to a genetic pathway linking diet and gut microbiota to macrophages and white adipose tissue. Their findings appear in the Journal of Experimental Medicine.
Type 2 diabetes is frequently associated with obesity. Ins some patients, that means insulin resistance. Later stages of the disease sees the pancreas producing insufficient insulin to maintain normal glucose levels.
In either case, hyperglycaemia is the result, which, if left untreated, impairs many major organs, sometimes to disabling or life-threatening degrees. Overweight status is a key risk factor for type 2 diabetes, often a result of eating too much fat and sugar in combination with low physical activity.
Associate Professors Andrey Morgun and Natalia Shulzhenko of OSU and Giorgio Trinchieri of the National Cancer Institute developed a novel analytical technique, multi-organ network analysis, to explore the mechanisms behind early-stage systemic insulin resistance.
The scientists sought to learn which organs, biological pathways and genes are playing roles.
The findings showed that a particular type of gut microbe leads to white adipose tissue containing macrophage cells associated with insulin resistance.
“Our experiments and analysis predict that a high-fat/high-sugar diet primarily acts in white adipose tissue by driving microbiota-related damage to the energy synthesis process, leading to systemic insulin resistance,” said Morgun. “Treatments that modify a patient’s microbiota in ways that target insulin resistance in adipose tissue macrophage cells could be a new therapeutic strategy for type 2 diabetes.”
The human gut microbiome is incredibly complex, comprising more than 10 trillion microbial cells from about 1000 different bacterial species.
Associate Profs Morgun and Shulzhenko, in earlier research developed a computational method, transkingdom network analysis, that predicts specific types of bacteria controlling the expression of mammalian genes connected to specific medical conditions such as diabetes.
“Type 2 diabetes is a global pandemic, and the number of diagnoses is expected to keep increasing over the next 10 years,” Associate Prof Shulzhenko said. “The so-called ‘western diet’ – high in saturated fats and refined sugars – is one of the primary factors. But gut bacteria have an important role to play in mediating the effects of diet.”
In the new study, the scientists made use of transkingdom network analysis and multi-organ network analysis. Mouse experiments examined the intestine, liver, muscle and white adipose tissue, and the molecular signature (gene expression) of white adipose tissue macrophages in obese human patients.
“Diabetes induced by the western diet is characterised by microbiota-dependent mitochondrial damage,” Associate Prof Morgun said. “Adipose tissue has a predominant role in systemic insulin resistance, and we characterised the gene expression program and the key master regulator of adipose tissue macrophage that are associated with insulin resistance. We discovered that the Oscillibacter microbe, enriched by a western diet, causes an increase of the insulin-resistant adipose tissue macrophage.”
The researchers add, however, that Oscillibacter is likely not the only microbial regulator for expression for the genetic pathway they discovered, while clearly instrumental, is probably not the only important pathway, depending on which gut microbes are present.
“We previously showed that Romboutsia ilealis worsens glucose tolerance by inhibiting insulin levels, which may be relevant to more advanced stages of type 2 diabetes,” Shulzhenko said.
