Epigenomic variability is associated with age‐specific naïve CD4 T cell response to activation in infants and adolescents. Issue 5 (1st March 2023) - Imran, Samira
Abstract: Childhood is a critical period of immune development. During this time, naïve CD4 (nCD4) T cells undergo programmed cell differentiation, mediated by epigenetic changes, in response to external stimuli leading to a baseline homeostatic state that may determine lifelong disease risk. However, the ontogeny of epigenetic signatures associated with CD4 T cell activation during key developmental periods are yet to be described. We investigated genome‐wide DNA methylation (DNAm) changes associated with nCD4 T activation following 72 h culture in media+anti‐CD3/CD28 beads in healthy infants (aged 12 months, n = 18) and adolescents (aged 10–15 years, n = 15). We integrated these data with transcriptomic and cytokine profiling from the same samples. nCD4 T cells from both age groups show similar extensive epigenetic reprogramming following activation, with the majority of genes involved in the T cell receptor signaling pathway associated with differential methylation. Additionally, we identified differentially methylated probes showing age‐specific responses, that is, responses in only infants or adolescents, including within a cluster of T cell receptor (TCR) genes. These encoded several TCR alpha joining (TRAJ), and TCR alpha variable (TRAV) genes. Cytokine data analysis following stimulation revealed enhanced release of IFN‐γ, IL‐2 and IL‐10, in nCD4 T cells from adolescents compared with infants. Overlapping differential methylation and cytokine responses identified four probes potentially underpinning these age‐specific responses. We show that DNAm in nCD4T cells in response to activation is dynamic in infancy and adolescence, with additional evidence for age‐specific effects potentially driving variation in cytokine responses between these ages. Abstract : This is the first study to show that nCD4 T cell DNA methylomes from infants and adolescents show age‐specific responses to activation, with specific probes responding in either age group, epigenetic reprogramming at several T cell receptor genes as well as at key immune pathways. These findings contribute to our understanding of the healthy nCD4 T cell response in critical age groups, and establish a baseline reference that may be screened for potential biomarkers in the context of disease.