Glucocorticosteroids Effects on Brain Development in the Preterm Infant: A Role for Microglia?

Prematurity, observed in 15 million births worldwide each year, is a clinical condition that is a major cause of neonatal mortality and morbidity in the short and long term. Preterm infants are at high risk of developing respiratory problems, sepsis, and other morbidities leading to neurodevelopmental impairment and neurobehavioral disorders. Perinatal glucocorticosteroids have been widely used for the prevention and treatment of adverse outcomes linked to prematurity. However, despite their short-term benefits due to their maturational properties, some clinical trials have shown an association between steroids exposure and abnormal brain development in infants born preterm. Neuroinflammation has emerged as a preeminent factor for brain injury in preterm infants, and the major role of microglia, the brain resident immune cells, has been recently highlighted. Considering the role of microglia in the modulation of brain development, the aim of this review is to summarize the effects of endogenous and exogenous glucocorticosteroids on brain development and discuss the possible role of microglia as the mediator of these effects.