Methylated cytosine is an important regulator of gene activity, and interfaces between environmental and genetic effects (epigenetics). Understanding how environmental factors modify the epigenome is regarded as fundamental to the successful treatment of disease. Recent research suggests that reactive oxygen species can facilitate changes in genomic patterns of methylated cytosine. During pathogenic infection, Streptoccocus pneumoniae excretes large amounts of hydrogen peroxide, which is thought to promote invasion. Our research investigates if inflammation and aging can modify the epigenome and alter gene activity in response to oxidative stress. We will initially develop a model system to investigate oxidative impacts on the epigenome and we will validate these results using immune cells isolated from individuals who have recently experienced chronic infection from Streptoccocus pneumoniae. The results will provide mechanistic insights into the process of bacterial invasion and will aid in the development of biomarkers for the diagnosis and treatment of pneumonia.