Are you constantly checking your Twitter/Instagram/Reddit feeds for the newest memes and best cat videos to share for the most likes? Well, don’t spend too much time stressing over your social media status; especially if you are a rhesus macaque, because new research suggests your immune cells might take a major epigenetic hit if you’re too fixated on monkey business.
Lower social status is related to poor health outcomes, in humans and other animals, and dysregulation of the stress system is likely involved. For example, people with lower socioeconomic status are at higher risk of cardiovascular disease, and have higher resting levels of the stress hormone, cortisol.
A new study from the lab of Jenny Tung (Duke University, North Carolina) is the first to explore how social rank and exposure to stress impact gene expression and chromatin accessibility in immune system cells. By utilizing ATAC-seq to assay the accessible chromatin of peripheral blood mononuclear cells (PBMCs) from female macaques in a stable dominance hierarchy, they found that:
- Treating PBMCs with dexamethasone (Dex), an artificial stress hormone that mimics cortisol, alters the expression of over 70% of genes, as shown by RNA-seq, but it only alters 16% of open chromatin peaks
- Untreated PBMCs from low ranking animals differ from high ranking animals in the expression of 69 genes, and 159 ATAC-seq peaks
- Dex stress weakens the relationship between social status and gene expression, but it has no effect on the location of open chromatin peaks
- In the Dex- PBMCs, genes that are more expressed in high ranking animals, overlap with rank-associated open chromatin peaks, but this correlation disappears in the Dex+ condition
- The chromatin accessibility landscape of stressed PBMCs overlaps more with the profile of high-ranking animals.
- Conversely, genes that show rank-related expression are largely different from those that are expressed in response to Dex
TLDR: Immune cells of high-ranking and low-ranking animals have different patterns of chromatin accessibility, which suggests that chronic social stress primes the epigenome for the changes in expression that occur under acute stress.
Next time you need a break from cyber stalking your favorite internet celebrities, consider sharing this article, in December 2018’s issue of PNAS, with your followers.