Fat Cells

Cellular signals may increase atherosclerosis risk

Fat Cells

Fat cells from obese patients have the ability to send signals that can accelerate biological processes leading to atherosclerosis.

Obesity has been linked to a variety of adverse health conditions, including Type 2 diabetes, cancer, heart attack and stroke – conditions that may begin as early as childhood in patients whose obesity also begins early. While this much is known, it has been unclear how extra fat mass might lead to these chronic health conditions.

New research from Children’s National Health System scientists might help answer this question. In findings presented at the 2017 annual meeting of the Pediatric Academic Societies, the research team shows that exosomes – nanosized chemical messages that cells send to each other to regulate protein production – isolated from very obese teenage patients behave very differently from those derived from lean patients and could be key players in heightening the risk of developing atherosclerosis. This hardening of the arteries can, in turn, increase the risk of heart disease and stroke in adulthood.

A research team led by Robert J. Freishtat, M.D., M.P.H., chief of emergency medicine at Children’s National, is exploring possible links between extra belly fat and obesity-related diseases, such as atherosclerosis, a buildup of plaque in arteries that can harden and restrict blood flow. More precise knowledge of the mechanisms by which obesity ratchets up heart risks holds the promise of helping the next generation of kids avoid experiencing chronic disease.

The working theory is that exosomes derived from belly fat from obese patients have the distinct ability to accelerate biological processes leading to atherosclerosis.

The research team isolated exosomes from five obese teenagers and compared them to five sex-matched lean adolescents. It turns out that exosomes derived from fat pick up their marching orders from microRNA content likely to target cholesterol efflux genes, which help reduce cholesterol buildup in cells.

The research team looked at differences in cholesterol efflux gene expression in THP-1 macrophages. Uptake of low-density lipoprotein cholesterol, “bad” cholesterol, was 92 percent higher than in those exposed to exosomes from obese patients compared with their lean counterparts. Exposure to obese exosomes also reduced cholesterol efflux.

“Atherogenic properties of fat-cell derived exosomes from obese patients differ markedly from the non-atherogenic profile of exosomes from lean patients. It is especially concerning that we see biological clues of heightened risk in teenagers, and the finding underscores how the seeds for atherosclerosis can be planted very early in life,” Dr. Freishtat says.

The presentation is the latest finding from a research team that, over years of work, is unraveling the mechanisms of cellular signaling by fat cells.  By closely examining very obese children – who have the most severe cardiometabolic disease – the team identified strong molecular signals of disease risk that they can search for in leaner patients who may be at risk for disease years from now.

“We know that morbidly obese patients have cardiovascular issues,” explains Dr. Freishtat. “An unanswered question is for patients with no clinical symptoms who are a little overweight. Can we look at them and say whether they are at risk for developing atherosclerosis, insulin resistance or Type 2 diabetes five or 10 years down the line? That’s the whole rationale for doing this work.”

The critical issue is what exosomes are up to. Dr. Freishtat says in lean people, they’re active and are very important in maintaining stable metabolism and homeostatic processes.

“When a person becomes obese, however, exosomes evolve,” he says. “They no longer support insulin signaling, which is helpful, and drive processes in the reverse direction, repressing insulin signaling – which can be harmful,” he adds.

Ultimately, the research team aims to revolutionize how chronic diseases like Type 2 diabetes are diagnosed. For far too long, clinicians have relied on symptoms like high glucose levels and excess urination to diagnose diabetes.

“By the time you have symptoms, it’s too late,” says Dr. Freishtat. “In many cases, damage has been done by relentless exposure to high sugar levels. The biological processes that underlie the Type 2 diabetes process began five, 10, 15 years earlier. If we can detect it earlier, before symptoms arise, intervention is going to have a more significant impact on improving and extending patients’ lives.”

Teen Girl drawing a heart on an iPad

Illuminating cardiometabolic risk in Down syndrome

Teen Girl drawing a heart on an iPad

A leading researcher at Children’s National says researchers should look closely at the increased risks of obesity and thyroid disease common in patients with Down Syndrome, and determine how these long term comorbidities relate to cardiovascular and metabolic (cardiometabolic) risk, body image, and quality of life.

Over the last several decades, physicians’ improved ability to treat the common comorbidities of Down syndrome, such as congenital heart disease, has dramatically prolonged survival. Today, more than 400,000 people across the country are living with Down syndrome, and life expectancy has increased to 60 years.

New strategies to manage care for patients with Down syndrome must include preventive, evidence-based approaches to address the unique needs of these patients, according to Sheela N. Magge, M.D., M.S.C.E., Director of Research in the Division of Endocrinology and Diabetes at Children’s. She says that these efforts should include looking more closely at the increased risks of obesity and thyroid disease common in this population, and determining how these long term comorbidities relate to cardiovascular and metabolic (cardiometabolic) risk, body image, and quality of life.

An NIH-funded study from Children’s National and the Children’s Hospital of Philadelphia (CHOP), led by Dr. Magge and her colleague from CHOP, Dr. Andrea Kelly, seeks to better understand how the body composition of patients with Down syndrome impacts their likelihood for developing diabetes and obesity-related cardiovascular risks long term.

“We know that individuals with Down syndrome are at increased risk for obesity, but what hasn’t been clear is whether or not they also have the same cardiometabolic risk associated with obesity that we know holds true for other populations,” says Dr. Magge. “In this previously under-studied population, the common assumption based on very limited studies from the 1970’s was that individuals with Down syndrome were protected from the diabetes and cardiovascular risks that can develop in other overweight people. However, more recent epidemiologic studies contradict those early findings.”

The study has enrolled 150 Down syndrome patients and almost 100 controls to date, and the team is currently beginning to analyze the data. Dr. Magge believes that the findings from this study will help to provide new, research-driven evidence to inform the long term clinical management of obesity and cardiometabolic risk in adolescents with Down syndrome.

She concludes, “The goal is for our research to provide the foundation that will advance prevention and treatment strategies for this understudied group, so that individuals with Down syndrome not only have a longer life expectancy, but also a healthier and better quality of life.”

Eric Vilain, M.D., Ph.D.

Eric Vilain to lead genetic medicine research

Eric Vilain

Eric Vilain, M.D., Ph.D., emphasizes the idea of health and disease as a compound process that will transform children’s health and impact a patient throughout life.

Eric Vilain, M.D., Ph.D., an internationally renowned geneticist well known for groundbreaking studies of gender based biology, will soon lead the Center for Genetic Medicine Research at Children’s National Health System.

Dr. Vilain joins Children’s National from the University of California, Los Angeles (UCLA) where he serves as Professor of Human Genetics, Pediatrics and Urology, Chief of Medical Genetics, and attending physician in the Department of Pediatrics.

As the Director of the Center for Genetic Medicine Research, Dr. Vilain will emphasize the idea of health and disease as a compound process, which he believes “can transform children’s health and help the treatment and prevention of illness, not only in childhood, but throughout a patient’s life.”

The Center for Genetic Medicine Research currently houses a highly interdisciplinary faculty of over 50 scientists and physician investigators and brings together a variety of clinical and scientific disciplines to coordinate scientific and clinical investigations simultaneously from multiple angles. The Center also provides access to the leading edge innovative technologies in genomics, microscopy, proteomics, bioinformatics, pre-clinical drug trials, and multi-site clinical trial networks for faculty within the Children’s Research Institute, the academic arm of Children’s National.

Dr. Vilain’s current laboratory focuses on the genetics of sexual development and sex differences – specifically the molecular mechanisms of gonad development and the genetic variants of brain sexual differentiation. His research also explores the biological bases of sex variations in predisposition to disease. His work crosses several disciplines (genetics, neuroscience, psychology) leading to findings with major societal implications. In addition to scientific investigation, Dr. Vilain created a clinic devoted to caring for patients with a wide array of genetic and endocrine issues, particularly those with variations of sexual development.

He brings nearly 30 years of expertise with him to Children’s National. He has authored seminal articles regarding the field of sexual development, and his research program has continuously been funded by the National Institutes of Health (NIH). Dr. Vilain is a Fellow of the American College of Medical Genetics and a member of numerous professional committees. The recipient of numerous awards, he has been recognized by organizations ranging from the NIH to the Doris Duke Charitable Foundation, March of Dimes, and the Society for Pediatric Research. He has served as an advisor to the International Olympic Committee Medical Commission since 2011 and has been a member of the Board of Scientific Counselors of the National Institute of Child Health and Human Development since 2015.

Mark Batshaw, M.D., Executive Vice President, Physician-in-Chief, and Chief Academic Officer at Children’s National says, “Dr. Vilain’s vision and expertise in the study and use of precision medicine approaches, and the development of novel treatments for diseases of childhood, will lead to drastically different and improved outcomes for some of the most devastating diseases, such as cancer.”

“I am honored to join the world-renowned team at Children’s National, and look forward to continuing to find new, innovative ways to research, diagnose and treat rare and common disorders,” Dr. Vilain adds.

Diabetes telemedicine program launches study survey and retrospective chart review

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Telemedicine isn’t new. And diabetes telemedicine isn’t new either. But the Diabetes Program at Children’s National Health System is doing more than just providing education and support groups via telemedicine. The largest pediatric diabetes program in the Mid-Atlantic region is evaluating just how successful its telemedicine program is with a six-month survey and retrospective chart review. “This is our opportunity to prove [the success] not anecdotally but with evidence,” says Colleen Meehan, M.D., M.P.H., a third-year resident at Children’s and one of the co-investigators for the project.

According to published literature, the Children’s National cohort is one of the largest of any other diabetes telemedicine program and extends the time period of care.

History of the program

Around the world, there isn’t enough endocrinology care, says Fran Cogen, M.D., C.D.E. Dr. Cogen and others at Children’s National have recognized the need right in their region—and worldwide—to deliver specialty care to patients who live too far from Washington, DC.

Many of the patients Dr. Cogen sees at Children’s National live on Maryland’s Eastern Shore, including the island of Tangiers, and in Delaware. That’s a two-and-a-half-hour drive over the Chesapeake Bay Bridge and an obstacle to scheduling follow-up appointments. To solve this issue, Children’s National partnered with Peninsula Regional Medical Center, in Salisbury, Md., three years ago to improve patients’ quality of life while getting them the care they needed.

How the program works

A nurse practitioner at Peninsula Regional sees patients for blood glucose checks and more frequently. Once a month, or depending on the severity of the diabetes, Dr. Cogen will observe—on a large TV screen from Children’s National—physical examinations, and then review insulin regimens and dosing, download the glucose meters in real time, discuss concerns, and develop treatment plans. There’s diabetes-specific software that patients can see at Peninsula Regional.

What the study can reveal

A 2014 pilot survey showed caregivers had great satisfaction with the program. Now, the team wants to formally study caregiver satisfaction and patient quality of life, as measured by a validated diabetes-specific Pediatric Quality of Life survey. With the largest cohort in diabetes telemedicine (75, type 1), it will also look at frequency of blood glucose monitoring, HbA1c, incidence of ER visits and hospitalizations for DKA or hypoglycemia, and percentage of missed clinic appointments. The team believes that this will show the diabetes telemedicine program is as effective as traditional face-to-face visits.

Other specialties at Children’s National are planning to provide telemedicine services, and some already do. The Diabetes Telemedicine Program is looking to expand coverage in Delaware, Maryland, and Virginia, to other rural areas that lack pediatric endocrinology or diabetes specialists.

“We can deliver quality care and develop a personal relationship without actually being physically present in the exam room,” Dr. Cogen says.

Robert J. Freishtat

A game changer for detecting complications from obesity

Robert J. Freishtat

The work that Children’s National Health System physician-scientist Robert J. Freishtat, M.D., M.P.H., and colleagues are doing could soon be a game changer when it comes to early intervention and prevention of obesity-related illnesses.

They already knew there’s a direct relationship between the amount of visceral adipose, or belly fat, a person has and development of some of the most common and life-threatening complications of obesity, including cardiovascular disease and the insulin resistance that leads to diabetes. What remained unclear, until recently, were the precise mechanisms for how the increase in belly fat triggers the onset of additional disease.

Dr. Freishtat, senior author of “Adipocyte-Derived Exosomal miRNAs: A Novel Mechanism for Obesity-Related Disease,” published by Pediatric Research, studies the adipocytes, or fat cells, of visceral adipose in both lean and obese patients to understand exactly how these fat cells can and do wreak havoc — not just locally but throughout the body. Cells leverage exosomes to communicate among themselves, but in overweight patients those cellular communications can go awry.

“As the body’s visceral fat grows, somewhere on the path to obesity the fat cells change and begin to release different exosomes than lean adipose cells do. These new messages disrupt some important processes that eventually prevent the body from effectively dealing with sugar and cholesterol,” says Dr. Freishtat, chief of Emergency Medicine at Children’s National, and associate professor of Pediatrics, Emergency Medicine, and Integrative Systems Biology at the George Washington University.

Dr. Freishtat describes exosomes as “biological tweets”— short messages shed by all cells that allow for intercellular communication and alter gene expression. In the case of the adipocytes that exist in large quantities of visceral fat, these “tweets” actually cause the downregulation of proteins impacting two key signaling pathways — TGF-β and Wnt/β-catenin — associated with controlling chronic inflammation and fibrotic disease throughout the body. These signaling changes make morbidly obese patients more vulnerable to systemwide issues, such as cholesterol accumulation and changes to how the liver processes fat.

Details of the study

The study authors surgically collected fat tissue from lean and obese female patients aged 11 to 19 and used modified bead-based flow cytometry to separate, identify, and compare the exosomal RNA shed by the fat cells in both lean and obese samples. To confirm the unique impact of the obese adipose exosomes on gene expression, the research team then exposed lung cells in vivo to the exosomes shed by both lean and obese adipose. They measured the impact of exposure and uptake on a single receptor type — activin receptor type-2B — known to have a major influence on the TGF-β pathway. The exosomes from obese adipose caused the receptor to slow down, leading to significant changes in the function of the TGF-β pathway.

The team continues to explore how the exosomes shed from excess amounts of visceral adipose spread throughout the body and how the function of organs such as the liver, the heart, and the brain are impacted by the migrating fat cells.

A Look into the future

Successfully identifying and isolating these exosomes also has opened the door to developing a test to detect them, an idea that may permit even earlier intervention to delay or prevent the onset of obesity-related illnesses.

“It is entirely plausible, and is on its way to happening very soon, that someone could walk into their physician’s office for a routine physical and, via a urine test, find out that they are on the road to some dangerous additional side effects of significant weight gain,” says Dr. Freishtat. “That type of early detection could really be a game changer for the millions of Americans who are on track to developing heart, liver, and other diseases resulting from morbid obesity.”