Production of Nitric Oxide Is Lower in Shiga Toxin-Stimulated Neutrophils of Infants Compared to Those of Children or Adults

Abstract

Hemolytic uremic syndrome (HUS) in infants is mainly caused by the Shiga toxin (Stx), which is produced by pathogenic Escherichia coli O157:H7. Infants are prone to develop HUS in comparison to older children and adults, but its underlying mechanism remains unknown. Recent observations suggest that reactive oxygen species (ROS) and reactive nitrogen species (RNS) including nitric oxide (NO) may be involved in the pathogenesis of HUS. We therefore measured NO production by neutrophils prepared from infants (6-27 months old), children (5.3-11 years old) or adults (25-47 years old). The NO production was measured by a flow cytometric analysis with a fluorescent indicator (expressed as mean fluorescence intensity), and mRNA expression of inducible NO synthase (iNOS) was analyzed by reverse transcriptionpolymerase chain reaction (RT-PCR). The amount of NO produced was significantly lower in Stx-stimulated neutrophils prepared from infants (45.8 ± 23.3) than that in those from children (120.5 ± 81.5) or adults (127.7 ± 45.8) (n = 10 each group, P < 0.05). The expression level of iNOS mRNA was lower in Stx-stimulated neutrophils of the infants than the level in those of children or adults. In conclusion, Stx increased NO production in neutrophils probably via iNOS. Importantly, the degree of the Stx-mediated increase in NO production was lower in neutrophils of infants compared to those of children or adults, which may explain the higher incidence of HUS in infants. These results suggest that NO may contribute to the cellular defense mechanisms against Stx.

Reversal of Sepsis‐Like Features of Neutrophils by Interleukin‐1 Blockade in Patients With Systemic‐Onset Juvenile Idiopathic Arthritis

“…The large differences in transcriptome between neutrophils from patients with active systemic‐onset JIA and neutrophils from healthy controls, in combination with the overlap with the transcriptome of other systemic inflammatory conditions, point toward the notion that there is a similar primed phenotype of neutrophils that cannot be attributed to differences in age or other confounding factors. This is supported by other studies that have shown no differences in neutrophil function between healthy children and adults .…”

Dietary choice affects Shiga toxin-producing Escherichia coli (STEC) O157:H7 colonization and disease

“…In two recent large outbreaks, women developed HUS in disproportionate numbers (9,13). Studies that address why children are more likely than adults to develop HUS suggest that a difference in complement activation (14,15), platelet activation (16), or in nitric oxide production (17) may explain the disparity.…”

Local anaesthetics upregulate nitric oxide generation in cord blood and adult human neutrophils

“…Similar results were reported by Tsui et al . 18 who found lower Shiga toxin-stimulated intracellular neutrophil NO generation accompanied by impaired NOS2 mRNA expression in infants compared with older children and adults. In line with their findings, in the present study unstimulated intracellular NO generation was comparable between CB and adult neutrophils, possibly due to low basal NO production 18 .…”

“…18 who found lower Shiga toxin-stimulated intracellular neutrophil NO generation accompanied by impaired NOS2 mRNA expression in infants compared with older children and adults. In line with their findings, in the present study unstimulated intracellular NO generation was comparable between CB and adult neutrophils, possibly due to low basal NO production 18 . As an alternative to the NOS-dependent mechanism, which, in adults, is responsible for approximately two-thirds of neutrophil NO production, another possible source of NO may be a non-enzymatic reaction between H 2 O 2 and arginine 9,19 .…”