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Marva Moxey-Mims in her office at Children's National.

Kidney disease outcomes differ between severely obese kids vs. adults after bariatric surgery

Marva Moxey-Mims in her office at Children's National.

“We know that bariatric surgery improves markers of kidney health in severely obese adults and adolescents,” says Marva Moxey-Mims, M.D. “This research helps to elucidate possible differences in kidney disease outcomes between children and adults post-surgery.”

Adolescents with Type 2 diabetes experienced more hyperfiltration and earlier attenuation of their elevated urine albumin-to-creatinine ratio (UACR) after gastric bypass surgery compared with adults. This finding contrasts with adolescents or adults who did not have diabetes prior to surgery, according to research presented Nov. 8, 2019, during the American Society of Nephrology’s Kidney Week 2019, the world’s largest gathering of kidney researchers.

“Findings from this work support a recent policy statement by the American Academy of Pediatrics (AAP) that advocates for increasing severely obese youths’ access to bariatric surgery,” says Marva Moxey-Mims, M.D., Chief of the Division of Nephrology at Children’s National Hospital and a study co-author.  “We know that bariatric surgery improves markers of kidney health in severely obese adults and adolescents. This research helps to elucidate possible differences in kidney disease outcomes between children and adults post-surgery.”

According to the AAP, the prevalence of severe obesity in youth aged 12 to 19 has nearly doubled since 1999. Now, 4.5 million U.S. children are affected by severe obesity, defined as having a body mass index ≥35 or ≥120% of the 95th percentile for age and sex.

In a Roux-en-Y gastric bypass, the surgeon staples the stomach to make it smaller, so people eat less. Then, they attach the lower part of the small intestine in a way that bypasses most of the stomach so the body takes in fewer calories.

The multi-institutional study team examined the health effects of such gastric bypass surgeries by comparing 161 adolescents with 396 adults enrolled in related studies. They compared their estimated glomerular filtration rates by serum creatinine and cystatin C. UACR was also compared at various time periods, up till five years after surgery.

Across the board, adolescents had higher UACR – a key marker for chronic kidney disease – than adults. However, for kids who had Type 2 diabetes prior to surgery, the prevalence of elevated UACR levels dip from 29% pre-surgery to 6% one year post-surgery. By contrast, adults who had diabetes prior to surgery and elevated UACR did not see a significant reduction in UACR until five years post-surgery.

While hyperfiltration prevalence was similar in study participants who did not have Type 2 diabetes, adolescents who had Type 2 diabetes prior to surgery had an increased prevalence of hyperfiltration for the duration of the study period.

Financial support for research described in this post was provided by the National Institute of Diabetes and Digestive and Kidney Diseases.

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ASN Kidney Week 2019 presentation

Five-year kidney outcomes of bariatric surgery in adolescents compared with adults
Friday, Nov. 8, 2019, 10 a.m. to noon (EST)
Petter Bjornstad, University of Colorado School of Medicine; Todd Jenkins, Edward Nehus and Mark Mitsnefes, all of Cincinnati Children’s Hospital; Marva M. Moxey-Mims, Children’s National Hospital; and Thomas H. Inge, Children’s Hospital Colorado.

Cholesterol plaque in artery

Looking for atherosclerosis’ root cause

Cholesterol plaque in artery

A multi-institutional team led by research faculty at Children’s National in Washington, D.C., finds that extracellular vesicles derived from kids’ fat can play a pivotal role in ratcheting up risk for atherosclerotic cardiovascular disease well before any worrisome symptoms become visible.

According to the Centers for Disease Control and Prevention, about one in five U.S. kids aged 6 to 19 is obese, boosting their risk for a variety of other health problems now and later in life.

One of these is atherosclerosis, a term that translates literally as hardening of the arteries. Atherosclerosis causes blood vessels that carry oxygen-rich blood throughout the body to become inflamed. White blood cells called macrophages settle in the vessel wall, which becomes overloaded with cholesterol. A plaque forms that restricts blood flow. But it remains a mystery how fat cells residing in one place in the body can trigger mayhem in cells and tissues located far away.

Small, lipid-lined sacs called extracellular vesicles (EVs), released by cells into the bloodstream, are likely troublemakers since they enable intercellular communication. Now, a multi-institutional team led by research faculty at Children’s National in Washington, D.C., finds that EVs derived from kids’ fat can play a pivotal role in ratcheting up risk for atherosclerotic cardiovascular disease well before any worrisome symptoms become visible. What’s more, the team showed that EVs found in the body’s fat stores can disrupt disposal of cholesterol in a variety of kids, from lean to obese, the team reports online July 22, 2019, in the Journal of Translational Medicine.

“We found that seven specific small sequences of RNA (microRNA) carried within the extracellular vesicles from human fat tissue impaired the ability of white blood cells called macrophages to eliminate cholesterol,” says Robert J. Freishtat, M.D., MPH, senior scientist at the Center for Genetic Medicine Research at Children’s National and the study’s senior author. “Fat isn’t just tissue. It can be thought of as a metabolic organ capable of communicating with types of cells that predispose someone to develop atherosclerotic cardiovascular disease, the leading cause of death around the world.”

Research scientists and clinicians from Children’s National, the George Washington University, NYU Winthrop Hospital and the National Heart, Lung and Blood Institute collaborated to examine the relationship between the content of EVs and their effect on macrophage behavior. Their collaborative effort builds on previous research that found microRNA derived from fat cells becomes pathologically altered by obesity, a phenomenon reversed by weight-loss surgery.

Because heart disease can have its roots in adolescence, they enrolled 93 kids aged 12 to 19 with a range of body mass indices (BMIs), including the “lean” group, 15 youth whose BMI was lower than 22 and the “obese” group, 78 youths whose BMI was in the 99th percentile for their age. Their median age was 17. Seventy-one were young women. They collected visceral adipose tissue during abdominal surgeries and visited each other’s respective labs to perform the experiments.

“We were surprised to find that EVs could hobble the macrophage cholesterol outflow system in adolescents of any weight,” says Matthew D. Barberio, Ph.D., the study’s lead author, a former Children’s National scientist who now is an assistant professor at the George Washington University’s Milken Institute School of Public Health. “It’s still an open question whether young people who are healthy can tolerate obesity—or whether there are specific differences in fat tissue composition that up kids’ risk for heart disease.”

The team plans to build on the current findings to safeguard kids and adults against future cardiovascular risk.

“This study was a huge multi-disciplinary undertaking,” adds Allison B. Reiss, M.D., of NYU Winthrop Hospital and the study’s corresponding author. “Ultimately, we hope to learn which properties belonging to adipose tissue EVs make them friendly or unfriendly to the heart, and we hope that gaining that knowledge will help us decrease morbidity and mortality from heart disease across the lifespan.”

In addition to Dr. Freishtat, additional study co-authors include Samuel B. Epstein, Madeleine Goldberg, Sarah C. Ferrante, and Evan P. Nadler, M.D., director of the Bariatric Surgery Program, all of Children’s National’s Center for Genetic Medicine Research; Lead Author, Matthew D. Barberio, of Millken Institute School of Public Health at the George Washington University; Lora J. Kasselman, Heather A. Renna, Joshua DeLeon, Iryna Voloshyna, Ashley Barlev, Michael Salama and Allison B. Reiss, all of NYU Winthrop Hospital; and Martin P. Playford and Nehal Mehta, of the National Heart, Lung and Blood Institute.

Financial support for research described in this post was provided by the National Institutes of Health National Center for Advancing Translational Sciences under award number UL1TR000075, the National Heart, Lung and Blood Institute under award number Z1AHL-06193-4, the American Heart Association under award number 17POST33670787, the Clark Charitable Foundation, the Elizabeth Daniel Research Fund, and Robert Buescher.

Janelle Vaughns

Few prescribing options exist for obese kids

Janelle Vaughns

“We are making progress in expanding the number of medicines with pediatric labeling, but we need to do more concerning providing dosing guidelines for children with obesity,” says Janelle D. Vaughns, M.D., director of bariatric anesthesia at Children’s National and the lead study author.

Despite years of study and numerous public health interventions, overweight and obesity continue to grow in the U.S. Currently, more than two-thirds of adults have these issues, according to data from the Centers for Disease Control and Prevention. Children and adolescents also are being affected at an increasing rate: About one in five is obese. Obesity and overweight have been linked with a bevy of health problems, including Type 2 diabetes, high blood pressure, coronary heart disease and stroke.

Additionally, because obesity increases the percentage of fat tissue in relation to lean tissue and enlarges kidney size, it can affect how readily the body takes up, metabolizes and excretes medicines.

This latter issue can be particularly problematic in children, a population for whom relatively few drug studies exist. Now, a study team that includes Children’s National Health System researchers suggests that, despite the U.S. Congress providing incentives to drug manufacturers to encourage the study of medications in children, few approved drugs include safe dosing information for obese kids.

The study, performed in conjunction with the Food and Drug Administration’s (FDA) Center for Drug Evaluation and Research, surveyed pediatric medical and clinical pharmacology reviews under the FDA Amendments Act of 2007 and the FDA Safety and Innovation Act of 2012. The researchers used search terms related to weight and size to determine the current incorporation of obesity as a covariate in pediatric drug development.

Of the 89 product labels identified, none provided dosing information related to obesity. The effect of body mass index on drug pharmacokinetics was mentioned in only four labels, according to the study “Obesity and Pediatric Drug Development,” published online Jan. 19, 2018, in The Journal of Clinical Pharmacology.

“We are making progress in expanding the number of medicines with pediatric labeling, but we need to do more concerning providing dosing guidelines for children with obesity,” says Janelle D. Vaughns, M.D., director of bariatric anesthesia at Children’s National and the lead study author. “Moving forward, regulators, clinicians and the pharmaceutical industry should consider enrolling more obese patients in pediatric clinical trials to facilitate the safe and effective use of the next generation of medicines by obese children and adolescents.”

Study co-authors include Children’s Gastroenterologist Laurie Conklin, M.D., and Children’s Division Chief of Clinical Pharmacology Johannes N. van den Anker, M.D., Ph.D.; Ying Long, Pharm.D., University of Southern California; Panli Zheng, Pharm.D., University of North Carolina at Chapel Hill; Fahim Faruque, Pharm.D., University of Maryland; and Dionna Green, M.D., and Gilbert Burckart, Pharm.D., both of the FDA.

Research reported in this news release was supported by the Eunice Kennedy Shriver National Institute of Child Health and Human Development of the National Institutes of Health under award number 5T32HD087969.