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Gustavo Nino

New method may facilitate childhood respiratory research

Gustavo Nino

“The use of CRC is a potentially powerful translational approach to shed light on the molecular mechanisms that control airway epithelial immune responses in infants and young children. This novel approach enables us to study the origins of respiratory disease and its chronic progression through childhood and beyond,” observes Gustavo Nino, M.D., a Children’s pulmonologist and study senior author.

A new method perfected by a team at Children’s National Health System may help expand research into pulmonary conditions experienced by infants and children, an understudied but clinically important age group. The study describing the new technique was published in the December 2017 print edition of Pediatric Allergy and Immunology.

Using conditionally reprogrammed cells (CRCs), a technique that enables indefinite proliferation of cells in the lab, the team was able to produce cell cultures that have a number of advantages over standard cultures and that may make it easier and more efficient to conduct research into pediatric respiratory immune responses.

The epithelial cells that line human airways are crucial in controlling immune responses to viruses, allergens and other environmental factors. The function and dysfunction of these airway epithelial cells (AECs) play a key role in asthma, cystic fibrosis and other pulmonary conditions, many of which begin in early life.

To generate enough of these cells for research, scientists culture AECs from primary nasal and bronchial cell samples. Cells derived from adults have fueled research leading to new therapies and the discovery of key biomarkers. But little comparable research has been conducted in infants. Airway sampling in premature infants has not been reported, likely to due to airway size limitations and underlying comorbidities. Similarly, sampling in infants is limited by the need for bronchoscopy and sedation.

“A major barrier has been the lack of a good system to culture epithelial cells, since airway sampling in infants and children is a challenge,” says co-lead author, Geovanny F. Perez, M.D., co-director of Children’s Severe Bronchopulmonary Dysplasia Program. “We needed a better way to culture cells in this age group.”

While primary AECs do not survive long in the lab, that hurdle was recently overcome by a process that generates CRCs from the primary AECs of adults, making it possible to quickly generate cell cultures from specimens.

In this study, the Children’s team adapted that approach, producing CRCs from primary AECs of neonates and infants. The CRC induction successfully enabled AEC cultures from infants born prematurely and from bronchial specimens of young children.

Geovanny Perez

“A major barrier has been the lack of a good system to culture epithelial cells, since airway sampling in infants and children is a challenge,” says co-lead author, Geovanny F. Perez, M.D., co-director of Children’s Severe Bronchopulmonary Dysplasia Program. “We needed a better way to culture cells in this age group.”

“We found that the CRCs have longer cell life and greater proliferation ability than standard cultures of epithelial cells. They preserved their original characteristics even after multiple experiments. And, they presented an innate immune response similar to that seen in primary human epithelial cells during viral respiratory responses in children,” says Dr. Perez.

“The use of CRC is a potentially powerful translational approach to shed light on the molecular mechanisms that control airway epithelial immune responses in infants and young children. This novel approach enables us to study the origins of respiratory disease and its chronic progression through childhood and beyond,” observes Gustavo Nino, M.D., a Children’s pulmonologist and study senior author.

The authors note that further studies are needed to define more precisely the differences and similarities in the immune responses of CRC and non-CRC derived from primary AEC. However, they conclude that CRC represents a new, effective method to study AEC innate immune responses in infants.

In addition to Drs. Perez and Nino, Children’s Center for Genetic Medicine Research co-authors include Co-Lead Author S. Wolf; Lana Mukharesh; Natalia Isaza Brando, M.D.; Diego Preciado, M.D., Ph.D.; Robert J. Freishtat, M.D., M.P.H.; Dinesh Pillai, M.D.; and M. C. Rose.

Financial support for this research was provided by the National Institute of Allergy and Infectious Diseases under grant number R21AI130502; Eunice Kennedy Shriver National Institute of Child Health and Human Development under grant number HD001399; National Heart, Lung and Blood Institute under grant number HL090020; and National Center for Advancing Translational Sciences under grant number UL1TR000075.

chromosome

X-linked genes help explain why boys of all ages face higher respiratory risk

chromosome

A multi-institution research team that includes Children’s National Health System attempted to characterize gender-based epigenomic signatures in the human airway early in children’s lives with a special attention to defining DNA methylation patterns of the X chromosome.

Human airways already demonstrate gender-based differences in DNA methylation signatures at birth, providing an early hint of which infants may be predisposed to develop respiratory disorders like asthma later in life, a research team reports in a paper published online April 3, 2018, in Scientific Reports.

It’s clear that boys and young men are more likely to develop neonatal respiratory distress syndrome, bronchopulmonary dysplasia, viral bronchiolitis, pneumonia, croup and childhood asthma. Unlike boys, girls have an additional copy of the X chromosome, which is enriched with immune-related genes, some of which play key roles in the development of respiratory conditions. Methylation prevents excessive gene activity in X-linked genes, however much remains unknown about how this process influences infants’ risk of developing airway diseases.

A multi-institution research team that includes Children’s National Health System attempted to characterize gender-based epigenomic signatures in the human airway early in children’s lives with a special attention to defining DNA methylation patterns of the X chromosome.

“It’s clear as we round in the neonatal intensive care unit that baby boys remain hospitalized longer than girls and that respiratory ailments are quite common. Our work provides new insights about gender differences in airway disease risk that are pre-determined by genetics,” says Gustavo Nino, M.D., a Children’s pulmonologist and the study’s senior author.

“Characterizing early airway methylation signatures holds the promise of clarifying the nature of gender-based disparities in respiratory disorders and could usher in more personalized diagnostic and therapeutic approaches.”

The research team enrolled 12 newborns and infants in the study and obtained their nasal wash samples. Six of the infants were born preterm, and six were born full term. The researchers developed a robust gender classification algorithm to generate DNA methylation signals. The machine learning algorithm identified X-linked genes with significant differences in methylation patterns in boys, compared with girls.

As a comparison group, they retrieved pediatric nasal airway epithelial cultures from a study that looked at genomic DNA methylation patterns and gene expression in 36 children with persistent atopic asthma compared with 36 heathy children.

The team went on to classify X-linked genes that had significant gender-based X methylation and those genes whose X methylation was variable.

“These results confirm that the X chromosome contains crucial information about gender-related genetic differences in different airway tissues,” Dr. Nino says. “More detailed knowledge of the genetic basis for gender differences in the respiratory system may help to predict, prevent and treat respiratory disorders that can affect patients over their entire lifetimes.”

In addition to Dr. Nino, study co-authors include Lead Author Cesar L. Nino, bioinformatics scientist, Pontificia Universidad Javeriana; Geovanny F. Perez, M.D., co-director of Children’s Severe Bronchopulmonary Dysplasia Program; Natalia Isaza Brando, M.D., Children’s neonatology attending; Maria J. Gutierrez, Johns Hopkins University School of Medicine; and Jose L. Gomez, Yale University School of Medicine.

Financial support for this research was provided by the National Institutes of Health under award numbers
AI130502-01A1, HL090020, HL125474-03, HD001399, UL1TR000075 and KL2TR000076.