Role of NLRC3 in modulating inflammatory responses in neonates.

Abstract

Objective: This study sought to investigate the role and molecular mechanisms of nucleotide-binding oligomerization domain (NOD)-like receptor family caspase activation and recruitment domain (CARD)-containing 3 (NLRC3) in the inflammatory responses of neonates, thereby developing new clinical insights into the occurrence and prevention of neonatal infections.

Methods: Peripheral blood samples were collected from full-term infants (n = 49) and preterm infants (n = 41) without any signs of intrauterine infection, as well as from healthy non-pregnant adults (n = 45). A real-time polymerase chain reaction was used to assess the expression levels of NLRC3 and NOD-containing protein 1 (NOD1) in the isolated mononuclear cells. Whole blood from the adults, full-term infants, and preterm infants was stimulated for four hours with a mixture of herpes simplex virus type 60 DNA (HSV-60 DNA) and lipopolysaccharides (LPS) or LPS alone or blank medium. An enzyme-linked immunosorbent assay was employed to measure the tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), and interleukin 1 beta (IL-1β) levels in the supernatant.

Results: The gene expression levels of NLRC3 were significantly lower in the full-term and preterm infants than in the adults, with the preterm infants showing notably lower levels when compared with the full-term infants. A positive correlation was found between the NLRC3 and NOD1 expression levels in the neonates (both full-term and preterm), indicating lower NLRC3 expression to be associated with lower NOD1 expression. After LPS stimulation, the production of TNF-α, IL-6, and IL-1β in the whole blood of the preterm and full-term infants was significantly lower than in that of the adults. Moreover, stimulation with a combination of LPS and HSV-60 DNA resulted in similar TNF-α, IL-6, and IL-1β production across the blood samples from preterm infants, full-term infants, and adults. When compared with LPS stimulation alone, the LPS and HSV-60 DNA mixture significantly reduced the release of TNF-α, IL-6, and IL-1β in the adults. In the neonates, however, only the release of TNF-α was significantly reduced, as no notable difference was observed in the IL-6 and IL-1β levels.

Conclusion: The reduced expression and functional impairment of NOD-like receptors, such as NLRC3 and NOD1, in neonates, may contribute to their heightened susceptibility to severe infections. This finding indicates new avenues for the prevention and treatment of neonatal infections.