Analysis of PD-1 expression in the monocyte subsets from non-septic and septic preterm neonates

• DOI: 10.1371/journal.pone.0186819
• Publication Date: 2017-10-19T18:13:35Z
• Authors: Magdalena Zasada; Marzena Lenart; Magdalena Rutkows...; Małgorzata Stec; Wojciech Durlak; Andrzej Grudzień; Agnieszka Krzeczk...; Nina Mól; Marta Pilch; Maciej Siedlar; Przemko Kwinta
• Keywords: Male; 0301 basic medicine; Science; Q; Programmed Cell Death 1 Receptor; R; Infant, Newborn; Length of Stay; Flow Cytometry; Infant, Newborn, Diseases; Monocytes; 3. Good health; 03 medical and health sciences; 13. Climate action; Case-Control Studies; Sepsis; Medicine; Humans; Female; Infant, Premature; Research Article

Programmed death-1 (PD-1) receptor system represents a part of recently reported immunoregulatory pathway. PD-1 is an immune checkpoint molecule, which plays an important role in downregulating the immune system proinflammatory activity. Until recently, PD-1 expression was not established on immune cells of the preterm infants. The study objectives were to confirm expression of the PD-1 receptors on the monocytes isolated from very low birth weight newborns (VLBW), and to analyze their expression during the first week of life and late-onset sepsis. Peripheral blood mononuclear cells were isolated from 76 VLBW patients without early-onset sepsis on their 5th day of life (DOL). PD-1 expression was determined on the monocyte subsets (classical, intermediate, non-classical) by flow cytometry. In case of late-onset sepsis (LOS), the same analysis was performed. Our results demonstrated that on the 5th DOL, PD-1 receptors were present in all the monocyte subsets. Children, whose mothers had received antenatal steroids, presented higher absolute numbers of non-classical monocytes with PD-1 expression. Infants born extremely preterm who later developed LOS, initially showed a lower percentage of PD-1 receptor-positive intermediate monocytes in comparison to neonates born very preterm. During LOS, we observed a rise in the percentage of classical monocytes with PD-1 expression. In case of septic shock or fatal outcome, there was a higher percentage and absolute count of intermediate monocytes with PD-1 expression in comparison to children without these complications. In conclusion, monocytes from VLBW children express PD-1 receptors. Antenatal steroid administration seems to induce PD-1 receptor expression in the non-classical monocytes. PD-1 might play a role in immunosuppressive phase of sepsis in the prematurely born children with septic shock and fatal outcome.