Elevated Senescence Markers in Developing Trisomy 21 Human Lungs

Human chromosomal anomalies, notably trisomies, disrupt gene expression, leading to diverse cellular and organ phenotypes. Increased cellular senescence (SEN) and oxidative stress in trisomies have gained recent attention. We assessed SEN, SEN-associated secretory phenotype (SASP), and oxidative stress on trisomy 13 (T13), T18, and T21 human fetal lung tissues and isolated primary human fetal lung fibroblasts. Telomerase-associated foci staining showed DNA damage primarily within T21 and T18 lungs. These results were confirmed by real-time quantitative PCR showing an increase of the SEN marker <i>CDKN2B</i> and SASP markers <i>IL-6</i> and <i>CXCL8</i>. In contrast, lung tissues from T13 showed an upregulation of <i>CDKN2A</i>, whereas no significant changes in SASP marker genes were observed. γ-H2AX (H2A histone family member X) was upregulated in each genotype, particularly in T21. Isolated fibroblasts demonstrated a strong association between T21 and several SEN markers. An increase of γ-H2AX-positive cells were observed in fibroblasts from T21, T18, and T13, but only T21 exhibited an increase in P21 expression. Only T21 fibroblasts displayed a significant increase in reactive oxygen species levels, as indicated by MitoSOX and CellROX. This study provides the first evidence of a link between SEN and trisomy anomalies during prenatal human lung development, particularly in T21.