Tag: 29/1/24

Categories : Metabolic DisordersTags :

A Single Gene Causes Mitochondria to ‘Fragment’ in Obesity

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These coloured streaks are mitochondrial networks within fat cells. Researchers from UC San Diego discovered that a high-fat diet dismantles mitochondria, resulting in weight gain. Credit: UC San Diego

While lifestyle factors like diet and exercise play a role in the development and progression of obesity, scientists have come to understand that obesity is also associated with intrinsic metabolic abnormalities. Now, researchers from University of California San Diego School of Medicine have shed new light on how obesity affects our mitochondria, the all-important energy-producing structures of our cells.

In a study published January 29, 2023 in Nature Metabolism, the researchers found that when mice were fed a high-fat diet, mitochondria within their fat cells broke apart into smaller mitochondria with reduced capacity for burning fat. Further, they discovered that this process is controlled by a single gene. By deleting this gene from the mice, they were able to protect them from excess weight gain, even when they ate the same high-fat diet as other mice.

“Caloric overload from overeating can lead to weight gain and also triggers a metabolic cascade that reduces energy burning, making obesity even worse,” said Alan Saltiel, PhD, professor in the Department of Medicine at UC San Diego School of Medicine. “The gene we identified is a critical part of that transition from healthy weight to obesity.”

Obesity occurs when the body accumulates too much fat, which is primarily stored in adipose tissue. Adipose tissue normally provides important mechanical benefits by cushioning vital organs and providing insulation. It also has important metabolic functions, such as releasing hormones and other cellular signaling molecules that instruct other tissues to burn or store energy.

In the case of caloric imbalances like obesity, the ability of fat cells to burn energy starts to fail, which is one reason why it can be difficult for people with obesity to lose weight. How these metabolic abnormalities start is among the biggest mysteries surrounding obesity.

To answer this question, the researchers fed mice a high-fat diet and measured the impact of this diet on their fat cells’ mitochondria, structures within cells that help burn fat. They discovered an unusual phenomenon. After consuming a high-fat diet, mitochondria in parts of the mice’s adipose tissue underwent fragmentation, splitting into many smaller, ineffective mitochondria that burned less fat.

In addition to discovering this metabolic effect, they also discovered that it is driven by the activity of single molecule, called RaIA. RaIA has many functions, including helping break down mitochondria when they malfunction. The new research suggests that when this molecule is overactive, it interferes with the normal functioning of mitochondria, triggering the metabolic issues associated with obesity.

“In essence, chronic activation of RaIA appears to play a critical role in suppressing energy expenditure in obese adipose tissue,” said Saltiel. “By understanding this mechanism, we’re one step closer to developing targeted therapies that could address weight gain and associated metabolic dysfunctions by increasing fat burning.”

By deleting the gene associated with RaIA, the researchers were able to protect the mice against diet-induced weight gain. Delving deeper into the biochemistry at play, the researchers found that some of the proteins affected by RaIA in mice are analogous to human proteins that are associated with obesity and insulin resistance, suggesting that similar mechanisms may be driving human obesity.

“The direct comparison between the fundamental biology we’ve discovered and real clinical outcomes underscores the relevance of the findings to humans and suggests we may be able to help treat or prevent obesity by targeting the RaIA pathway with new therapies,” said Saltiel “We’re only just beginning to understand the complex metabolism of this disease, but the future possibilities are exciting.”

Source: EurekAlert!

Categories : CancerTags :

Wait for Green: Why Immunotherapy Often Fails to Work

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Photo by National Cancer Institute on Unsplash

An international study has uncovered a mechanism by which cancer cells prevent the immune system from activating and attacking the cancerous invaders. The study, published in the peer-reviewed journal Cell Reports, sheds light on why immunotherapy treatments don’t work for all people or all diseases.

Certain types of cancers, such as colon, pancreatic, prostate and brain cancers, have stubbornly resisted immunotherapy.

And while breast, oesophageal and head and neck cancers often respond favourably, sometimes the treatments don’t work as planned.

Researchers still don’t understand exactly why, but the study, co-authored by University of Texas at Arlington scientists, may offer a clue.

“Immunotherapy is an incredibly promising new treatment avenue for cancer, but we still have work to do determining why it doesn’t work for all people or types of cancer,” said Jon Weidanz, UTA associate vice president for research and innovation.

He and Soroush Ghaffari, a UTA postdoctoral fellow, were co-authors of the study, along with colleagues at Leiden University in Leiden, Netherlands, and Karolinska University in Solna, Sweden.

The team determined that a key checkpoint in the immune system, called NKG2A, doesn’t engage with its specific binding molecule expressed in cancer cells until the appropriate signal is received.

“The team reasoned that monotherapy agents targeting the NKG2A receptor may not be effective without receiving an inflammatory trigger,” Ghaffari said.

“This might explain why drugs designed to bind to the NKG2A receptor to disrupt this immune checkpoint have been only effective when used in combination with other agents that can induce the necessary inflammatory signal.”

A second major finding of the study revealed how certain cancers can inhibit the immune system from activating its macrophages.

“These data give us a new molecular understanding of why some immunotherapies work and some don’t,” said Weidanz, who also is a professor kinesiology with an appointment in bioengineering and a member of the Multi-Interprofessional Center for Health Informatics.

“These results will help us identify and treat more cancers effectively with immunotherapy, helping more people live longer lives despite a cancer diagnosis.”

These findings have implications for immune system research and the development of more effective immunotherapy drugs, said Kate C. Miller, vice president of research and innovation at UTA.

“These are exciting new research results that have the potential to impact people living with cancer,” Miller said. “This is another great example of the calibre of biomedical research we’re performing both here at UTA and with our partners at other institutions.”

Source: University of Texas at Arlington

Categories : Diseases, Syndromes and Conditions Metabolic DisordersTags :

GLP-1 Agonists Associated with Reduced Risk of Liver Diseases

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By HualinXMN – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=133759262

GLP1 agonists such as Ozempic (semaglutide) are associated with a reduced risk of developing cirrhosis and liver cancer in people with type 2 diabetes and chronic liver disease, according to a nationwide study from Karolinska Institutet published in the journal Gut.

GLP1 agonists reduce blood sugar levels and are mainly used to treat type 2 diabetes. Since the drug also reduces appetite, it is now increasingly used to treat obesity and has become a popular weight-loss drug.

Reduced risk of liver damage

Results from early clinical trials also suggest that GLP1 agonists may reduce the risk of liver damage. Therefore, researchers at Karolinska Institutet included all people in Sweden with chronic liver disease and type 2 diabetes in a register-based study. They then compared the risk of severe liver damage in those who were treated with GLP1 agonists and those who were not. The results show that those who took the drug for a long period of time had a lower risk of later developing more severe forms of liver disease such as cirrhosis and liver cancer.

According to the researchers, this suggests that GLP1 agonists could be an effective treatment to avoid severe liver disease in people with concurrent type 2 diabetes.

“Fatty liver disease is estimated to affect up to one in five people in Sweden, many of whom have type 2 diabetes, and about one in twenty develop severe liver disease,” says first author Axel Wester, assistant professor at the Department of Medicine, Huddinge, Karolinska Institutet. “Our findings are interesting because there are currently no approved drugs to reduce this risk.”

Many of the people in the study stopped taking GLP1 agonists, resulting in a lack of protective effect. However, those who continued taking their medication over a ten-year period were half as likely to develop severe liver disease.

Clinical trials needed for confirmation

“The results need to be confirmed in clinical trials, but it will take many years for these studies to be completed,” says Axel Wester. “Therefore, we use existing registry data to try to say something about the effect of the drugs before that.”

A limitation of the method is that it is not possible to control for factors for which there is no data, such as blood tests to describe the severity of liver disease in more detail. However, the researchers have recently built a new database called HERALD where they have access to blood samples from patients in Region Stockholm.

“As a next step, we will investigate the effect of GLP1 agonists in this database,” says the study’s last author Hannes Hagström, consultant in hepatology at the Karolinska University Hospital and adjunct professor at the Department of Medicine, Huddinge, Karolinska Institutet. “If we get similar results, it would further strengthen the hypothesis that GLP1 agonists can be used to reduce the risk of severe liver disease.”

The research was mainly funded by Region Stockholm (CIMED), the Swedish Research Council and the Swedish Cancer Society. Hannes Hagström’s research group has received funding from Astra Zeneca, EchoSens, Gilead, Intercept, MSD, Novo Nordisk and Pfizer, although no industry-supported funding was obtained for this specific study.

Source: Karolinska Institutet

Categories : Exercise Obstetrics & GynaecologyTags :

Swimming in Cold Water Improves Menopause Symptoms

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Photo by Kampus Production

Researchers have found that swimming in cold water results in a significant improvement in menopause symptoms for women. The research, published in Post Reproductive Health, surveyed 1114 women, 785 of which were going through the menopause, to examine the effects of cold water swimming on their health and wellbeing.

The findings showed that menopausal women experienced a significant improvement in anxiety (as reported by 46.9% of the women), mood swings (34.5%), low mood (31.1%) and hot flushes (30.3%) as a result of cold water swimming.

In addition, a majority of women (63.3%) swam specifically to relieve their symptoms.

Some of the women quoted in the study said that they found the cold water to be “an immediate stress/ anxiety reliever” and described the activity as “healing.”

One 57-year-old woman stated: “Cold water is phenomenal. It has saved my life. In the water, I can do anything. All symptoms (physical and mental) disappear and I feel like me at my best.”

Senior author, Professor Joyce Harper (UCL EGA Institute for Women’s Health), said: “Cold water has previously been found to improve mood and reduce stress in outdoor swimmers, and ice baths have long been used to aid athletes’ muscle repair and recovery.

“Our study supports these claims, meanwhile the anecdotal evidence also highlights how the activity can be used by women to alleviate physical symptoms, such as hot flushes, aches and pains.

“More research still needs to be done into the frequency, duration, temperature and exposure needed to elicit a reduction in symptoms. However, we hope our findings may provide an alternative solution for women struggling with the menopause and encourage more women to take part in sports.”

Most of the women involved in the study were likely to swim in both summer and winter and wear swimming costumes, rather than wet suits.

Alongside aiding menopausal symptoms, the women said their main motivations for cold water swimming were being outside, improving mental health and exercising.

Professor Harper said: “The majority of women swim to relieve symptoms such as anxiety, mood swings and hot flushes. They felt that their symptoms were helped by the physical and mental effects of the cold water, which was more pronounced when it was colder.

“How often they swam, how long for and what they wore were also important. Those that swam for longer had more pronounced effects. The great thing about cold water swimming is it gets people exercising in nature, and often with friends, which can build a great community.”

The researchers also wanted to investigate whether cold water swimming improved women’s menstrual symptoms.

Of the 711 women who experienced menstrual symptoms, nearly half said that cold water swimming improved their anxiety (46.7%), and over a third said that it helped their mood swings (37.7%) and irritability (37.6%).

Yet despite the benefits of cold water swimming, the researchers were also keen to highlight that the sport comes with certain risks.

Professor Harper explained: “Caution must be taken when cold water swimming, as participants could put themselves at risk of hypothermia, cold water shock, cardiac rhythm disturbances or even drowning.

“Depending on where they are swimming, water quality standards may also vary. Raw sewage pollution is an increasingly common concern in UK rivers and seas. And, sadly, this can increase the likelihood of gastroenteritis and other infections.”

Study limitations

The study may contain some bias due to the survey only being taken by women who already cold water swim. And, as the survey was conducted online, it is likely that women were more likely to complete the survey if they noticed an association between menopause symptoms and cold water swimming.

Source: University College London

Categories : Neurodegenerative DiseasesTags :

Crafting a ‘Key’ to Cross the Blood-brain Boundary

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Source: Pixabay CC0

Researchers led by Michael Mitchell of the University of Pennsylvania are close to gaining access through the blood-brain barrier, a long-standing boundary in biology, by granting molecules a special ‘key’ to gain access.

Their findings, published in the journal Nano Letters, present a model that uses lipid nanoparticles (LNPs) to deliver mRNA, offering new hope for treating conditions like Alzheimer’s disease and seizures.

“Our model performed better at crossing the blood-brain barrier than others and helped us identify organ-specific particles that we later validated in future models,” says Mitchell, associate professor of bioengineering at Penn’s School of Engineering and Applied Science, and senior author on the study.

“It’s an exciting proof of concept that will no doubt inform novel approaches to treating conditions like traumatic brain injury, stroke, and Alzheimer’s.”

Search for the key

To develop the model, Emily Han, a PhD candidate and NSF Graduate Research Fellow in the Mitchell Lab and first author of the paper, explains that it started with a search for the right in vitro screening platform, saying, “I was combing through the literature, most of the platforms I found were limited to a regular 96-well plate, a two-dimensional array that can’t represent both the upper and lower parts of the blood-brain barrier, which correspond to the blood and brain, respectively.”

Han then explored high-throughput transwell systems with both compartments but found they didn’t account for mRNA transfection of the cells, revealing a gap in the development process.

This led her to create a platform capable of measuring mRNA transport from the blood compartment to the brain, as well as transfection of various brain cell types including endothelial cells and neurons.

“I spent months figuring out the optimal conditions for this new in vitro system, including which cell growth conditions and fluorescent reporters to use,” Han explains.

“Once robust, we screened our library of LNPs and tested them on animal models. Seeing the brains express protein as a result of the mRNA we delivered was thrilling and confirmed we were on the right track.”

The team’s platform is poised to significantly advance treatments for neurological disorders.

It’s currently tailored for testing a range of LNPs with brain-targeted peptides, antibodies, and various lipid compositions.

However, it could also deliver other therapeutic agents like siRNA, DNA, proteins, or small molecule drugs directly to the brain after intravenous administration.

What’s more, this approach isn’t limited to the blood-brain barrier as it shows promise for exploring treatments for pregnancy-related diseases by targeting the blood-placental barrier, and for retinal diseases focusing on the blood-retinal barrier.

Next Steps

The team is eager to use this platform to screen new designs and test their effectiveness in different animal models.

They are particularly interested in working with collaborators with advanced animal models of neurological disorders.

“We’re collaborating with researchers at Penn to establish brain disease models,” Han says.

“We’re examining how these LNPs impact mice with various brain conditions, ranging from glioblastoma to traumatic brain injuries. We hope to make inroads towards repairing the blood-brain barrier or target neurons damaged post-injury.”

Source: University of Pennsylvania