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

Abstract

SummaryEarly 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.HighlightsHuman iPS-derived-microglia predominantly express glucocorticoid receptor NR3C1 compared with mineralocorticoid receptor NR3C2, and a predominant splice variant of the NR3C1 of GR-α.GC expression shows a differentiation-linked increment from iPSC to iPS-microglia.An early-life stress model was established by exposing iPSC to glucocorticoids during primitive haematopoiesis.RNA-seq analysis revealed that this early glucocorticoid exposure led to enhanced type I interferon inducible gene expression in the subsequent iPS-microglia.Furthermore, micronuclei formation and cellular senescence markers were upregulated in the iPSC-microglia, indicating genomic instability due to early chronic GC exposure.These findings have ramifications for the microglial responses in ELS linked neurodevelopmental disorders such as schizophrenia, attention-deficit hyperactivity disorder and autistic spectrum disorder.Graphical abstract