Glucocorticoid receptor activation during human microglial differentiation leads to genomic instability and senescence

Early life stress, prenatal exposure to glucocorticoids (GCs), confers a higher risk of psychiatric and neurodevelopmental disorders in children. Increasingly, the importance of microglia in these disorders has been recognised. Studies on GCs exposure during microglial development have been limited, and there are few, if any, human studies. We established an in vitro model of ELS by continuous pre-expoure of human iPS-microglia to GCs during primitive haematopoiesis (the critical stage of iPS-microglial differentiation) and then examined how this exposure affected the microglial phenotype as they differentiated and matured to microglia. The iPS-microglia predominately expressed glucocorticoid receptors over mineralocorticoid receptors, and the GR-α splice variant. Chronic GCs exposure during primitive haematopoiesis was able to recapitulate in vivo ELS effects. Thus pre-exposure to prolonged GCs resulted in increased type I interferon signalling, the presence of Cyclic GMP-AMP synthase-positive (cGAS) micronuclei, and cellular senescence in the matured iPS-microglia. The findings from this in vitro ELS model have ramifications for the responses of microglia in the pathogenesis of GC-mediated ELS-associated disorders such as schizophrenia, attention-deficit hyperactivity disorder and autistic spectrum disorder. ### Competing Interest Statement The authors have declared no competing interest.