O3305: Argon Inhalation Promotes Intestinal and Hepatic Recovery during Experimental Neonatal Sepsis

Background: Neonatal sepsis is a systemic inflammatory infection considered one of the most life-threatening clinical conditions among neonates, particularly in the preterm population. Despite major advances in neonatal intensive care, sepsis remains a leading cause of morbidity and mortality. The systemic infection induces liver and intestinal inflammation via Toll-like receptor (TLR) 4 proinflammatory signaling. It has been recently shown that argon inhalation reduces the systemic inflammatory response during sepsis. Additionally, argon is proposed to modulate this TLR4 signaling pathway. Therefore, this study aims to determine the underlying mechanism of action of argon inhalation during sepsis-related liver and intestinal injury.

Methods: Sepsis was induced in C57BL/6 pup mice on postnatal day (P) 9 by intraperitoneal injection of lipopolysaccharide [20mg/kg]. The study groups included non-septic controls (n=6), sepsis (n=6), and sepsis with argon inhalation (n=6). Argon (70% argon, 30% oxygen) was administered via inhalation to septic pups for 6 hours in a sealed chamber housed within a temperature-controlled incubator. After 6 hours, liver, distal ileum and distal colon were harvested for mRNA expression analysis by RT-qPCR and protein expression analysis by western blotting.

Results: Septic mice had increased mRNA expression of TLR4 and its downstream adaptor protein MyD88 in the liver and intestine (p < 0.05). However, argon inhalation reversed the mRNA expression of these two genes. In addition, protein expression analysis by western blot showed a significant decrease of TLR4 (Fig. 1a-c), the ratio of the phosphorylated IKBa kinase to total IKBa (Fig. 1d-f) and the nuclear transcription factor NF-KB (Fig. 1g-i) in the liver and intestine of septic mice receiving argon compared to septic mice alone.

Conclusion: We demonstrated that argon stimulates liver and intestinal recovery from sepsis by reducing inflammation via modulation of the TLR4/NF-KB signaling pathway. As mechanical ventilation is common among septic neonates and the use of an inhalational therapy already exists in the clinical setting for other conditions, the implementation of argon is practical. Additionally, argon is shown to be safe, cost effective and easily accessible. Ultimately, our discovery indicates that argon can become a viable therapeutic option for neonatal sepsis and its remarkable benefits can modify the management of this serious condition.