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newborn in incubator

A bronchopulmonary dysplasia primer to guide clinicians and researchers

newborn in incubator

Six months in the writing, the “Bronchopulmonary Dysplasia Primer” published recently by Nature Reviews will be the gold standard review on this topic for years to come.

The term bronchopulmonary dysplasia, or BPD, was first coined in 1967 to describe a chronic lung disease of preterm newborns after treatment with supplemental oxygen via mechanical ventilation in an effort to save their lives. Back then, infants had 50-50 odds of surviving.

In the intervening years, survival has improved and the characteristics of BPD have evolved. Now, BPD is the most common complication of preterm birth for infants born at fewer than 28 weeks’ gestation, as more and more newborns survive premature birth. Hence, the primer.

“The contributing authors are some of the biggest thinkers on this topic,” says Robin H. Steinhorn, M.D., senior vice president, Center for Hospital-Based Specialties, at Children’s National Hospital and author of the section about BPD diagnosis, screening and prevention. “This document will guide clinical education and investigators in the field of BPD. I anticipate this will be the definitive review article on the subject for the next several years.”

Gestational age and low birth weight remain the most potent predictors of BPD. Some 50,000 extremely low gestational age newborns are born each year in the U.S. About 35% will develop some degree of BPD, according to the primer authors.

These newborns are introduced to life outside the womb well before their lungs are ready. Indeed, the pulmonary surfactants needed for normal lung function – a complex mixture of phospholipids that reduce surface tension within the lungs – don’t differentiate until late in pregnancy. Infants who persistently need respiratory support after the 14th day of life are at the highest risk of being diagnosed with BPD at 36 weeks, the coauthors note.

A number of complicating factors can come into play, including maternal diet; fetal exposure to maternal smoking and infection; structural issues such as pre-eclampsia; acute injury from mechanical ventilation and supplemental oxygen; as well as the body’s halting efforts to repair injured, inflamed lung tissue.

“The good news is the number of the smallest and youngest preterm infants who survive extreme preterm birth has steadily increased. Neonatal intensive care units, like our award-winning NICU, now routinely care for babies born at 22 weeks’ gestation,” Dr. Steinhorn says.

Treatment strategies include:

  • Reducing exposure to intubation and ventilation.
  • Leveraging respiratory stimulants, like caffeine.
  • Postnatal steroid therapy.

“Children’s National Hospital is the only center in our immediate region that provides comprehensive care for infants and children with severe BPD,” Dr. Steinhorn adds. “As the population of vulnerable and fragile infants has grown, we have invested in the equipment and the personnel – including at the Hospital for Sick Children Pediatric Center (HSC) – to create a very safe and supportive environment that improves survival and quality of life.”

Some preterm infants spend their first 9 to 10 months of life at Children’s National, and their days are filled with concentrated physical, occupational and speech therapy, as well as music and play therapy to hasten their rehabilitation.

Once their medical condition stabilizes, they transition to HSC to focus more intently on rehabilitation.

“We see HSC as filling a very important role in their care. When our children graduate to HSC, they are going for ongoing care of their lung disease, but also their ongoing rehabilitation. At HSC, they focus on creating the most normal life that we can possibly create and, over time, that is a life free of ventilators and tracheostomy tubes.”

In addition to Dr. Steinhorn, BPD Primer co-authors include Bernard Thébaud, Children’s Hospital of Eastern Ontario; Kara N. Goss, University of Wisconsin-Madison; Matthew Laughon, The University of North Carolina at Chapel Hill; Jeffrey A. Whitsett and Alan H. Jobe, Cincinnati Children’s Hospital Medical Center; Steven H. Abman, Children’s Hospital Colorado;  Judy L. Aschner, Joseph M. Sanzari Children’s Hospital; Peter G. Davis, The Royal Women’s Hospital; Sharon A. McGrath- Morrow, Johns Hopkins University School of Medicine; and Roger F. Soll, University of Vermont.

Financial support for the research described in this post was provided by the National Institutes of Health under grant Nos. U01HL122642, U01HL134745, RO1HL68702, R01HL145679, U01HL12118-01 and K24 HL143283; the Australian National Health and Medical Research Council; the Canadian Institute for Health Research; Stem Cell Network and the Ontario Institute for Regenerative Medicine.

Andrea Gropman

$5M in federal funding to help patients with urea cycle disorders

Andrea Gropman

Andrea L. Gropman, M.D.: We have collected many years of longitudinal clinical data, but with this new funding now we can answer questions about these diseases that are meaningful on a day-to-day basis for patients with urea cycle disorders.

An international research consortium co-led by Andrea L. Gropman, M.D., at Children’s National Hospital has received $5 million in federal funding as part of an overall effort to better understand rare diseases and accelerate potential treatments to patients.

Urea cycle disorder, one such rare disease, is a hiccup in a series of biochemical reactions that transform nitrogen into a non-toxic compound, urea. The six enzymes and two carrier/transport molecules that accomplish this essential task reside primarily in the liver and, to a lesser degree, in other organs.

The majority of patients have the recessive form of the disorder, meaning it has skipped a generation. These kids inherit one copy of an abnormal gene from each parent, while the parents themselves were not affected, says Dr. Gropman, chief of the Division of Neurodevelopmental Pediatrics and Neurogenetics at Children’s National. Another more common version of the disease is carried on the X chromosome and affects boys more seriously that girls, given that boys have only one X chromosome.

Regardless of the type of urea cycle disorder, when the urea cycle breaks down, nitrogen converts into toxic ammonia that builds up in the body (hyperammonemia), particularly in the brain. As a result, the person may feel lethargic; if the ammonia in the bloodstream reaches the brain in high concentrations, the person can experience seizures, behavior changes and lapse into a coma.

Improvements in clinical care and the advent of effective medicines have transformed this once deadly disease into a more manageable chronic ailment.

“It’s gratifying that patients diagnosed with urea cycle disorder now are surviving, growing up, becoming young adults and starting families themselves. Twenty to 30 years ago, this never would have seemed conceivable,” Dr. Gropman says. “We have collected many years of longitudinal clinical data, but with this new funding now we can answer questions about these diseases that are meaningful on a day-to-day basis for patients with urea cycle disorders.”

In early October 2019, the National Institutes of Health (NIH) awarded the Urea Cycle Disorders Consortium for which Dr. Gropman is co-principal investigator a five-year grant. This is the fourth time that the international Consortium of physicians, scientists, neuropsychologists, nurses, genetic counselors and researchers has received NIH funding to study this group of conditions.

Dr. Gropman says the current urea cycle research program builds on a sturdy foundation built by previous principal investigators Mendel Tuchman, M.D., and Mark Batshaw, M.D., also funded by the NIH. While previous rounds of NIH funding powered research about patients’ long-term survival prospects and cognitive dysfunction, this next phase of research will explore patients’ long-term health.

Among the topics they will study:

Long-term organ damage. Magnetic resonance elastrography (MRE) is a state-of-the-art imaging technique that combines the sharp images from MRI with a visual map that shows body tissue stiffness. The research team will use MRE to look for early changes in the liver – before patients show any symptoms – that could be associated with long-term health impacts. Their aim is spot the earliest signs of potential liver dysfunction in order to intervene before the patient develops liver fibrosis.

Academic achievement. The research team will examine gaps in academic achievement for patients who appear to be underperforming to determine what is triggering the discrepancy between their potential and actual scholastics. If they uncover issues such as learning difficulties or mental health concerns like anxiety, there are opportunities to intervene to boost academic achievement.

“And if we find many of the patients meet the criteria for depression or anxiety disorders, there are potential opportunities to intervene.  It’s tricky: We need to balance their existing medications with any new ones to ensure that we don’t increase their hyperammonemia risk,” Dr. Gropman explains.

Neurologic complications. The researchers will tap continuous, bedside electroencephalogram, which measures the brain’s electrical activity, to detect silent seizures and otherwise undetectable changes in the brain in an effort to stave off epilepsy, a brain disorder that causes seizures.

“This is really the first time we will examine babies’ brains,” she adds. “Our previous imaging studies looked at kids and adults who were 6 years and older. Now, we’re lowering that age range down to infants. By tracking such images over time, the field has described the trajectory of what normal brain development should look like. We can use that as a background and comparison point.”

In the future, newborns may be screened for urea cycle disorder shortly after birth. Because it is not possible to diagnose it in the womb in cases where there is no family history, the team aims to better counsel families contemplating pregnancy about their possible risks.

Research described in this post was underwritten by the NIH through its Rare Diseases Clinical Research Network.

rabies virus illustration

Critters bugging! Test your infectious disease knowledge


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.

Zhe Han

$2M NIH grant for treating disease linked to APOL1

Zhe Han

Children’s researcher Zhe Han, Ph.D., has received a $2 million award from the National Institutes of Health (NIH) to study new approaches to treat kidney disease linked to inheriting Apolipoprotein L1 (APOL1) risk alleles. These risk alleles are particularly common among persons of recent African descent, and African Americans are disproportionately affected by the increased risk in kidney disease associated with these risk alleles.

Han, an associate professor in Children’s Center for Genetic Medicine Research, has established a leading research program that uses the fruit fly Drosophila as a model system to study how genetic mutations lead to disease.

Drosophila is a very basic model, but studies in the fly have led to major breakthroughs in understanding fundamental biological processes that underlie health and disease in humans,” Han says. “Since coming to Children’s National five years ago, I have focused a significant part of my research studying particular fly cells called nephrocytes that carry out many of the important roles of human kidney glomeruli, units within the kidney where blood is cleaned. Working together with clinician colleagues here, we have demonstrated that these Drosophila cells can be used to very efficiently study different types of renal disease caused by genetic mutations.”

The APOL1 risk alleles are genetic variants, termed G1 and G2, found almost exclusively in people of African ancestry and can lead to a four-fold higher risk of end-stage kidney disease, the last of five stages of chronic kidney disease. Exactly how inheriting these risk alleles increases the risk of kidney disease remains an unanswered question and the focus of considerable research activity. Han’s laboratory has developed a Drosophila model of APOL1-linked renal disease by producing the G1 and G2 forms of APOL1 specifically in nephrocytes. This led to defects in fly renal cells that strikingly overlap with disease-associated changes in experimental model and human kidney cells expressing APOL1 risk alleles.

The new NIH award will fund large-scale screening and functional testing to identify new treatment targets and new drugs to treat kidney disease linked to APOL1. Using a genetic screening approach, Han’s lab will identify nephrocyte “modifier” genes that interact with APOL1 proteins and counter the toxic effects of risk-associated G1 and G2 variants.

The team also will identify nephrocyte genes that are turned on or off in the presence of APOL1 risk alleles, and confirm that such “downstream” APOL1-regulated genes are similarly affected in experimental model and human kidney cells. The potential of the newly identified “modifier” and “downstream” genes to serve as targets of novel therapeutic interventions will be experimentally tested in fly nephrocytes in vivo and in cultured mammalian kidney cells.

Finally, the Drosophila model will be used as a drug screening platform for in vivo evaluation of positive “hits” from a cell-based APOL1 drug screening study in order to identify compounds that are most effective with the fewest side effects.

“These types of studies can be most efficiently performed in Drosophila,” Han adds.  “They take advantage of the speed and low cost of the fly model system and the amazing array of well-established, sophisticated genetic tools available for the fly. Using this model to elucidate human disease mechanisms and to identify new effective therapies has truly become my research passion.”