Impact of toll-like receptor 4 stimulation on human neonatal neutrophil spontaneous migration, transcriptomics, and cytokine production

Neonates rely on their innate immune system, and neutrophils in particular, to recognize and combat life-threatening bacterial infections. pretreatment with lipopolysaccharide (lps), a toll-like receptor (tlr) 4 agonist, improves survival to polymicrobial sepsis in neonatal mice by enhancing neutrophil recruitment. to understand the response of human neonatal neutrophils to tlr4 stimulation, ex vivo spontaneous neutrophil migration, neutrophil transcriptomics, and cytokine production in the presence and absence of lps were measured directly from whole blood of adults, term neonates, and preterm neonates. spontaneous neutrophil migration was measured on novel microfluidic devices with time-lapse imaging for 10 h. genome-wide neutrophil transcriptomics and plasma cytokine concentrations were also determined. preterm neonates had significantly fewer spontaneously migrating neutrophils at baseline, and both term and preterm neonates had decreased neutrophil velocity, compared to adults. in the presence of lps stimulation, the number of spontaneously migrating neutrophils was reduced in preterm neonates compared to term neonates and adults. neutrophil velocity was not significantly different among groups with lps stimulation. preterm neonates upregulated expression of genes associated with the recruitment and response of neutrophils following lps stimulation, but failed to upregulate the expression of genes associated with antimicrobial and antiviral responses. plasma levels of il-1β, il-6, il-8, mip-1α, and tnf-α increased in response to lps stimulation in all groups, but il-10 was increased only in term and preterm neonates. in conclusion, age-specific changes in spontaneous neutrophil migration counts are not affected by lps despite changes in gene expression and cytokine production.