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preterm baby

Validating a better way to stratify BPD risk in vulnerable newborns

preterm baby

Factoring in the total number of days that extremely preterm infants require supplemental oxygen and tracking this metric for weeks longer than usual improves clinicians’ ability to predict respiratory outcomes according to bronchopulmonary dysplasia severity.

Factoring in the total number of days that extremely preterm infants require supplemental oxygen and tracking this metric for weeks longer than usual improves clinicians’ ability to predict respiratory outcomes according to bronchopulmonary dysplasia (BPD) severity, a research team led by Children’s National Hospital writes in Scientific Reports. What’s more, the researchers defined a brand-new category (level IV) for newborns who receive supplemental oxygen more than 120 days as a reliable way to predict which infants are at the highest risk of returning to the hospital due to respiratory distress after discharge.

About 1 in 10 U.S. infants is born preterm, before 37 weeks gestation, according to the Centers for Disease Control and Prevention. That includes extremely preterm infants who weigh about 1 lb. at birth. These very low birthweight newborns have paper thin skin, frail hearts and lungs that are not yet mature enough to deliver oxygen throughout the body as needed. Thanks to advances in neocritical care, an increasing number of them survive prematurity, and many develop BPD, a chronic lung disease characterized by abnormal development of the lungs and pulmonary vasculature.

“About half of the babies born prematurely will come back to the hospital within the first year of life with a respiratory infection. The key is identifying them and, potentially, preventing complications in this high-risk population,” says Gustavo Nino, M.D., a Children’s National pulmonologist and the study’s lead author.

For decades, the most common way to stratify BPD risk in these vulnerable newborns has been to see if they require supplemental oxygen at 36 weeks corrected gestational age.

“The problem with this classification is it doesn’t take into account the very premature babies who are on oxygen for much longer than other babies. So, we asked the question: Can we continue risk stratification beyond 36 weeks in order to identify a subset of babies who are at much higher risk of complications,” Dr. Nino says.

The longitudinal cohort study enrolled 188 infants born extremely preterm who were admitted to the neonatal intensive care unit (NICU) at Children’s National and tracked their data for at least 12 months after discharge. The team used a multidimensional approach that tracked duration of supplemental oxygen during the newborns’ NICU stay as well as scoring lung imaging as an independent marker of BPD severity. To validate the findings, these U.S.-born newborns were matched with 130 infants who were born preterm and hospitalized at two NICUs located in Bogotá, Colombia.

“Babies who are born very preterm and require oxygen beyond 120 days should have expanded ventilation of the lungs and cardiovascular pulmonary system before going home,” he notes. “We need to identify these newborns and optimize their management before they are discharged.”

And, the babies with level IV BPD risk need a different type of evaluation because the complications they experience – including pulmonary hypertension – place them at the highest risk of developing sleep apnea and severe respiratory infection, especially during the first year of life.

“The earlier we identify them, the better their outcome is likely to be,” Dr. Nino says. “We really need to change the risk stratification so we don’t call them all ‘severe’ and treat them the same when there is a subset of newborns who clearly are at a much higher risk for experiencing respiratory complications after hospital discharge.”

In addition to Dr. Nino, Children’s National study co-authors include Awais Mansoor, Ph.D., staff scientist at the Sheikh Zayed Institute for Pediatric Surgical Innovation (SZI); Geovanny F. Perez, M.D., pediatric pulmonologist; Maria Arroyo, M.D., pulmonologist; Xilei Xu Chen, M.D., postdoctoral fellow; Jered Weinstock, pediatric pulmonary fellow; Kyle Salka, MS, research technician; Mariam Said, M.D., neonatologist, and Marius George Linguraru, DPhil, MA, MSc, SZI principal investigator and senior author. Additional co-authors include Ranniery Acuña-Cordero, Universidad Militar Nueva Granada, Bogotá, Colombia; and Monica P. Sossa-Briceño and Carlos E. Rodríguez-Martínez, both of Universidad Nacional de Colombia.

Funding for research described in this post was provided by the National Institutes of Health (NIH) under award Nos. HL145669, AI130502 and HL141237. In addition, the NIH has awarded Dr. Nino an RO1 grant to continue this research.

Dr. Anna Penn uses a microscope

New model mimics persistent interneuron loss seen in prematurity

Dr. Anna Penn uses a microscope

Children’s research-clinicians created a novel preclinical model that mimics the persistent interneuron loss seen in preterm human infants, identifying interneuron subtypes that could become future therapeutic targets to prevent or lessen neurodevelopmental risks.

Research-clinicians at Children’s National Health System have created a novel preclinical model that mimics the persistent interneuron loss seen in preterm human infants, identifying interneuron subtypes that could become future therapeutic targets to prevent or lessen neurodevelopmental risks, the team reports Jan. 31, 2019, in eNeuro. The open access journal for Society for Neuroscience recognized the team’s paper as its “featured” article.

In the prefrontal cortex (PFC) of infants born preterm, there are decreased somatostatin and calbindin interneurons seen in upper cortical layers in infants who survived for a few months after preterm birth. This neuronal damage was mimicked in an experimental model of preterm brain injury in the PFC, but only when the newborn experimental models had first experienced a combination of prenatal maternal immune activation and postnatal chronic sublethal hypoxia. Neither neuronal insult on its own produced the pattern of interneuron loss in the upper cortical layers observed in humans, the research team finds.

“These combined insults lead to long-term neurobehavioral deficits that mimic what we see in human infants who are born extremely preterm,” says Anna Penn, M.D., Ph.D., a neonatologist in the Division of Neonatology and the Fetal Medicine Institute and a developmental neuroscientist at Children’s National Health System, and senior study author. “Future success in preventing neuronal damage in newborns relies on having accurate experimental models of preterm brain injury and well-defined outcome measures that can be examined in young infants and experimental models of the same developmental stage.”

According to the Centers for Disease Control and Prevention 1 in 10 infants is born preterm, before the 37th week of pregnancy. Many of these preterm births result from infection or inflammation in utero. After delivery, many infants experience other health challenges, like respiratory failure. These multi-hits can exacerbate brain damage.

Prematurity is associated with significantly increased risk of neurobehavioral pathologies, including autism spectrum disorder and schizophrenia. In both psychiatric disorders, the prefrontal cortex inhibitory circuit is disrupted due to alterations of gamma-aminobutyric acid (GABA) interneurons in a brain region involved in working memory and social cognition.

Cortical interneurons are created and migrate late in pregnancy and early infancy. That timing leaves them particularly vulnerable to insults, such as preterm birth.

In order to investigate the effects of perinatal insults on GABAergic interneuron development, the Children’s research team, led by Helene Lacaille, Ph.D., in Dr. Penn’s laboratory, subjected the new preterm encephalopathy experimental model to a battery of neurobehavioral tests, including working memory, cognitive flexibility and social cognition.

“This translational study, which examined the prefrontal cortex in age-matched term and preterm babies supports our hypothesis that specific cellular alterations seen in preterm encephalopathy can be linked with a heightened risk of children experiencing neuropsychiatric disorders later in life,” Dr. Penn adds. “Specific interneuron subtypes may provide specific therapeutic targets for medicines that hold the promise of preventing or lessening these neurodevelopmental risks.”

In addition to Dr. Penn and Lead Author Lacaille, Children’s co-authors include Claire-Marie Vacher; Dana Bakalar, Jiaqi J. O’Reilly and Jacquelyn Salzbank, all of Children’s Center for Neuroscience Research.

Financial support for research described in this post was provided by the National Institutes of Health under award R01HD092593, District of Columbia Intellectual Developmental Disabilities Research Center under award U54HD090257, Cerebral Palsy Alliance Research Foundation, Children’s National Board of Visitors, Children’s Research Institute and Fetal Medicine Institute.