The immune system is a remarkably intricate network with incredible capabilities. It can protect the body from a variety of pathogenic invaders and kill harmful cells that could cause cancer. Additionally, it has the capacity to recall those encounters with pathogens, preparing the immune system to react more swiftly and forcefully against the offender if they occur again. More information about how the immune system memory is produced at the molecular level has now been discovered by scientists. The results were published in Science Immunology.
Immune cells can identify antigens on the surface of the pathogen when they are exposed to an invader. In this study, immune cells known as naive cells that had never been exposed to an antigen were compared to memory cells, which had come into contact with an antibiotic. The goal of the study was to pinpoint the epigenetic variations between these cell types, which are variations in DNA that can affect gene expression but do not change the genome’s order. These variations include structural changes or chemical tags. Epigenetic changes may help to explain why naive cells are relatively slow and memory cells can react so quickly.
The researchers found that naive cells and memory cells had very different epigenetic characteristics at work. While naive cells lacked this signature, memory cells had an epigenetic signature that could cause the rapid expression of important genes. The epigenetic modifications in memory cells made these crucial genes and transcription factors known as AP-1 easier to access by cellular machinery.
Additionally, memory cells were found to have very different three-dimensional positions of DNA in the nucleus than naive cells. The same regulatory sequences known as enhancers keep together and control genes that are essential to the early immune response. Due to a unique arrangement of DNA in the nucleus that naive cells lack, these genes are all physically grouped together in memory cells and are ready to be activated.
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The body reacts abnormally and excessively to environmental stimuli when someone has asthma. In order to determine whether any of these epigenetic characteristics were altered in a condition where the immune system is not functioning properly, the investigators also examined immune cells from asthma patients. In fact, this demonstrated that the cells from these patients were overactive in genes associated with a quick, strong immune response.
This study emphasizes the significance of epigenetic factors on immunity, though scientists still have a lot to learn about how they affect the immune response.
Sources: Science Immunology, Josep Carreras Leukaemia Research Institute