title: 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 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.
authors.affiliation: Department of Pediatrics, Kansai Medical University, Osaka, Japan. tsujis@hirakata.kmu.ac.jp
authors.forename: Shoji
authors.initials: S
authors.lastname: Tsuji
authors.forename: Anna
authors.initials: A
authors.lastname: Iharada
authors.forename: Takahisa
authors.initials: T
authors.lastname: Kimata
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Shimo
authors.forename: Masato
authors.initials: M
authors.lastname: Hirabayashi
authors.forename: Kazunari
authors.initials: K
authors.lastname: Kaneko
mesh_terms: D000328:Adult; D000375:Aging / Q000097:blood / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D002478:Cells, Cultured; D002648:Child; D002675:Child, Preschool; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006801:Humans; D007223:Infant; D008213:Lymphocyte Activation / Q000187:drug effects / Q000235:genetics; D008875:Middle Aged; D009504:Neutrophils / Q000187:drug effects* / Q000378:metabolism*; D009569:Nitric Oxide / Q000097:blood / Q000378:metabolism*; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D022621:Shiga Toxin / Q000276:immunology / Q000494:pharmacology*; D013268:Stimulation, Chemical
chemical_list: D009569:Nitric Oxide; D022621:Shiga Toxin; C496319:NOS2 protein, human; D052247:Nitric Oxide Synthase Type II