NOD1 and NOD2 expression and function in very preterm infant mononuclear cells

Aim: To evaluate mononuclear cell expression and function of the cytosolic nucleotide-binding oligomerization domain-containing receptors, NOD1 and NOD2, in very preterm and full-term infants. Methods: NOD1 and NOD2 gene and protein expression in very preterm infants, term infants and healthy adult, cord and peripheral blood mononuclear cells (C/PBMC) were quantified using qPCR and flow cytometry. Cytokine responses of purified infant and adult monocytes to NOD1- and NOD2-specific agonists were assessed using a multiplex immunoassay (Bioplex). Results: NOD1 and NOD2 were expressed by a range of infant and adult mononuclear cell types, including T- and B cells, with highest expression in classical (CD14++CD16-) and intermediate (CD14++CD16+) monocytes. NOD1 and NOD2 expression levels by monocytes from very preterm infant were similar to those in term infants or adults. Monocyte production of TNFα, IL-6 and IL-1β induced by activation of NOD1 and NOD2 was similar between very preterm infants, term infants and adults. Conclusion: Monocyte expression and function of NOD1 and NOD2 in very preterm infants are intact and comparable/equivalent to term infants and adults. Functional deficiencies in monocyte NOD signalling pathways are unlikely to contribute to the increased susceptibility to bacterial sepsis in preterm infants.