Production of nitric oxide is lower in Shiga toxin-stimulated neutrophils of infants compared to those of children or adults

Tohoku J Exp Med. 2012 Nov;228(3):247-52. doi: 10.1620/tjem.228.247.

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 transcription-polymerase 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aging / blood
  • Aging / genetics
  • Aging / immunology
  • Aging / metabolism
  • Cells, Cultured
  • Child
  • Child, Preschool
  • Gene Expression Regulation, Enzymologic / drug effects
  • Humans
  • Infant
  • Lymphocyte Activation / drug effects
  • Lymphocyte Activation / genetics
  • Middle Aged
  • Neutrophils / drug effects*
  • Neutrophils / metabolism*
  • Nitric Oxide / blood
  • Nitric Oxide / metabolism*
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism
  • Shiga Toxin / immunology
  • Shiga Toxin / pharmacology*
  • Stimulation, Chemical

Substances

  • Nitric Oxide
  • Shiga Toxin
  • NOS2 protein, human
  • Nitric Oxide Synthase Type II