Lipopolysaccharide-induced expression of Th1/Th2 cytokines in whole neonatal cord and adult blood: role of nuclear factor-kappa B and p38 MAPK.

BACKGROUND

Sepsis continues to be a leading cause of morbidity and mortality in newborns.

OBJECTIVE

As both nuclear factor-kappa B (NF-κB) and p38 mitogen-activated protein kinase (MAPK) appear to be critical mediators in inflammatory response, we studied the effects of lipopolysaccharide (LPS) on expression and function of NF-κB and p38 MAPK in whole neonatal cord and adult blood.

METHODS

Th1/Th2 cytokine concentrations and phosphorylation of NF-κB and p38 MAPK were determined by flow-cytometric analysis.

RESULTS

Tumor necrosis factor-alpha (TNF-α), IL-6, and IL-10 concentrations were significantly elevated in supernatants of neonatal and adult blood after LPS stimulation for 4 h. IFN-γ, IL-4, and IL-2 showed no significant alterations. Furthermore, TNF-α concentrations were significantly higher in adult compared to neonatal blood after LPS stimulation. Stimulation with LPS resulted in significantly decreased activation of p38 MAPK in neonatal blood, whereas NF-κB showed no difference. Following inhibition of p38 MAPK with the specific inhibitor SB-202190, levels of TNF-α and IL-6 significantly decreased in neonatal and adult blood, whereas pharmacological inhibition of NF-κB with SC-514 showed no significant effect on cytokine expression.

CONCLUSIONS

We conclude that p38 MAPK phosphorylation is crucially involved in LPS activation and could explain the differences in early cytokine response between neonatal and adult blood.