OBJECTIVETo investigate the expression of TLR4/2 mRNA in neonatal cord blood mononuclear cells (MNC).

METHODSForty-six neonates without asphyxia and 40 neonates with asphyxia were divided into groups depending on the gestational age. In the neonates without asphyxia, there were 18 full term infants (the gestational age > or = 37 weeks), 16 preterm infants whose gestational age was > or = 32 weeks but < 37 weeks, and 12 preterm infants whose gestational age was < 32 weeks. In the neonates with asphyxia, 11 were full term infants, 15 were preterm infants whose gestational age was > or = 32 weeks but < 37 weeks and 14 were preterm infants at gestational age < 32 weeks. MNCs were separated and cultured with LPS (1 microg/ml) for 3 h. Cells were collected for analysis of gene expression of TLR4/2 by RT-PCR technique. Cell supernatants were taken to measure TNF-alpha production following the ELISA protocol. Fifteen healthy adults were enrolled into the control group. In addition, the Pearson correlation analyses were carried out between the levels of TLR4, TLR2 mRNA and the levels of TNF-alpha.

RESULTSIn the neonates without asphyxia, TLR4, TLR2 mRNA and TNF-alpha levels were 0.75 +/- 0.12, 0.63 +/- 0.08, 2502.6 +/- 273.1 ng/L, separately, in the full term infants, 0.37 +/- 0.04, 0.32 +/- 0.03, 1218.8 +/- 145.7 ng/L, separately, in the preterm infants whose gestational ages were > or = 32 weeks but < 37 weeks, and 0.26 +/- 0.03, 0.20 +/- 0.03, 811.8 +/- 105.2 ng/L separately, in the preterm infants whose gestational ages were < 32 weeks. In the neonates with asphyxia, TLR4, TLR2 mRNA and TNF-alpha levels were 0.58 +/- 0.07, 0.50 +/- 0.06, 1946.4 +/- 244.2 ng/L, separately, in the full term infants, 0.29 +/- 0.03, 0.26 +/- 0.03, 970.0 +/- 94.3 ng/L, separately, in the preterm infants whose gestational age was > or = 32 weeks but < 37 weeks, and 0.17 +/- 0.02, 0.14 +/- 0.02, 652.6 +/- 60.3 ng/L, separately, in the preterm infants whose gestational age was < 32 weeks. The levels of TLR4, TLR2 mRNA and TNF-alpha in the adults were 2.71 +/- 0.75, 2.61 +/- 0.33, 9270.1 +/- 1098.3 ng/L, separately. In the preterm infants and full term infants, the levels of TLR4, TLR2 mRNA and TNF-alpha were lower in comparison to the adults. The lower the gestational age, the lower the levels of TLR4, TLR2 mRNA and TNF-alpha. There were significant differences between the levels of TLR4, TLR2 mRNA and TNF-alpha of the neonates without asphyxia and those of the neonates with asphyxia. In the neonates with asphyxia, the levels of TLR4, TLR2 mRNA and TNF-alpha were lower than those in the neonates without asphyxia (P < 0.01). Whether the neonates were asphyxic or not, the levels of TLR4, TLR2 were paralleled with the levels of TNF-alpha.

CONCLUSIONSThe expression of TLRs in the neonates, especially in the preterm infants was lower than that in the adults, which probably contributes to the susceptibility of neonates to infections.