Detection of astrocyte epigenetic memory in in vitro systems, experimental autoimmune encephalomyelitis and multiple sclerosis samples

We recently described astrocyte pro-inflammatory epigenetic memory based on multiple complementary in vivo and in vitro studies, and the analysis of multiple sclerosis samples. Based on bioinformatic analyses, O’Dea and Liddelow argued that the astrocyte epigenetic memory we described is the result of contamination with immune cells, particularly myeloid cells. We rebut O’Dea and Liddelow arguments as follows: (1) We show substantial purity of astrocytes analyzed in in vivo and in vitro systems; (2) We recapitulate astrocyte memory responses using five independent pure astrocyte in vitro systems, and show its dependency on the histone acetyl transferase p300; and (3) Using the Liddelow lab bioinformatic pipeline to implement purity and cell-quality criteria, we detect astrocyte epigenetic memory in five independent scRNA-seq experimental autoimmune encephalomyelitis (EAE) and multiple sclerosis (MS) astrocyte datasets. These additional analyses and studies provide further support for the existence of astrocyte pro-inflammatory epigenetic memory.