O fígado neonatal como reservatório de neutrófilos

Abstract

The neonatal immune response is a topic of importance and influence in therapeutics that may be applied during this critical period of development. Understanding it can foster significant progress in the care and prevention of diseases in neonates. In this study, using Intravital Confocal Microscopy, we were able to describe a considerable population of granulocytes located in the hepatic parenchyma of fetuses and neonatal mice. Through immunophenotyping, changes were identified mainly in granulocytes during the neonatal period. By employing Intravital Confocal Microscopy in liver tissues from the animal model from birth to adulthood, we observed a very significant presence of Ly6G+ cells in this tissue microenvironment up to the second week of life. With CyTOF, these cells were characterized as neutrophils – which was confirmed by morphology and immunohistochemistry techniques. In this sense, even the fetal liver was perceived as a site for this population of neutrophils around the second gestational week, raising questions about their origin and establishment. Generally, these cells are predominantly located in the extravascular space and exhibit very specific behaviors during the analyzed periods: these hepatic neutrophils form cellular clusters in fetuses and neonates, which persist for the first few days of life, and have limited migratory capacity that seems to be counterbalanced by increased release of reactive oxygen species in neonates under stimulation when compared to any other phase of the animal model. This work uniquely describes a population of neutrophils present in the fetal and neonatal liver, with spatial and functional characteristics very distinct from those observed in the adult phase.