Buccal DNA Methylation-Derived EpiScores are Associated with Neonatal Morbidity Burden in Infants born Very Preterm

Every human body carries a complex internal record of its history, written not just in the genes we inherit, but in the chemical tags that attach to our DNA as we grow. These tags, known as DNA methylation, act like switches that can turn genes on or off, changing how cells behave without altering the underlying genetic code itself. Because these switches respond to the environment, they can capture the biological impact of stress, illness, or injury long after the event has passed. For infants born very early, before thirty weeks of pregnancy, the first few months of life are often a gauntlet of serious medical challenges. These babies face a high risk of multiple complications, from breathing difficulties to infections, which place a heavy load on their developing systems. Understanding how this early adversity leaves a lasting mark on their biology is crucial, not only to grasp the immediate toll of prematurity but to see how these early experiences might shape health later in life.

A team of researchers set out to find a way to read this biological record in infants who had already survived the most critical phase of their hospital stay. They focused on a group of 537 babies born very preterm, all part of a larger study known as the NOVI cohort. Instead of looking at the blood, which is often difficult to collect from fragile newborns without causing further stress, the scientists gathered tiny samples of DNA from the inside of the babies' cheeks at the time they were discharged from the neonatal intensive care unit. From these samples, they calculated 111 different "EpiScores." These scores are essentially mathematical estimates of how much of specific proteins are circulating in the body, derived entirely from the pattern of DNA methylation tags found in the cheek cells. The researchers wanted to see if these scores could reveal the hidden biological cost of the multiple serious illnesses these infants had endured.

The team compared the EpiScores of babies who had experienced two or more serious neonatal morbidities against those who had experienced zero or just one. They were looking for a signal that the body's molecular machinery had been altered by the burden of multiple illnesses. The analysis revealed that eighteen of the protein estimates showed a statistical link to the number of health problems the infants faced. One particular estimate stood out with a high degree of confidence: a protein called Melanoma-derived growth regulatory protein, or MIA. The data suggested that higher levels of this protein, as predicted by the cheek DNA, were associated with a greater burden of neonatal illness. The researchers then checked whether these findings in cheek cells matched what would be seen in blood, using a separate set of paired samples from 21 individuals. They found that for many of the protein estimates, the signals were strong and consistent across both tissue types, confirming that the cheek samples were a reliable window into the body's systemic state.

The specific proteins that showed these associations pointed toward a body that had been working hard to manage inflammation, fight infection, and regulate metabolism and growth. The study suggests that the stress of surviving multiple serious conditions in the neonatal period leaves a detectable signature in the DNA methylation patterns of very preterm infants. This signature can be read from a simple cheek swab, offering a way to quantify the biological toll of early life adversity. While the findings are specific to this group of infants and the particular proteins measured, they demonstrate that the molecular aftermath of neonatal morbidity persists even after the immediate medical crises have resolved. The work provides a concrete method for linking the number of health challenges an infant faces to the underlying biological changes that remain, offering a new perspective on how early life stress is encoded in the human body.