title: TLR expression, phagocytosis and oxidative burst in healthy and septic newborns in response to Gram-negative and Gram-positive rods.
abstract: The objective was to investigate whether phagocytes from healthy and septic newborns have a developmental deficiency in their capacity to recognize, phagocytize and generate hydrogen peroxide (H2O2) in response to Escherichia coli and Staphylococcus aureus. TLR expression and phagocytic ability of neutrophils and monocytes from 44 healthy preterm and term neonates, from 13 newborns with late-onset sepsis and from 24 healthy adults were determined using flow cytometry, and H2O2 production was measured by dihydrorhodamine test. TLR-2 and TLR-4 expressions were similar among the groups. The phagocytic ability of monocytes and neutrophils exposed to E. coli and S. aureus in healthy and septic neonates was significantly reduced compared to that of adults. Monocytes from septic newborns exposed to E. coli had higher H2O2 production than those of the other groups. The oxidative burst of monocytes exposed to S. aureus was reduced in preterm newborns compared with term ones and those with sepsis, and no differences were found in the oxidative burst of neutrophils. Even with the ability to recognize bacteria, a decreased clearance of pathogens can cause an imbalance in the immune response, which could lead to a predisposition to sepsis. Once established, the increased production of cytokines and ROS in an attempt to control the infection as well as the lack of full phagocytic activity leads to persistence of the pathogen and a state of constant inflammation.
authors.affiliation: Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil; Laboratory of Medical Investigation (LIM-36), Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil. Electronic address: analucia.slessa@gmail.com.
authors.forename: Ana Lúcia
authors.initials: AL
authors.lastname: Silveira-Lessa
authors.affiliation: Laboratory of Medical Investigation (LIM-36), Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Camila
authors.initials: C
authors.lastname: Quinello
authors.affiliation: Laboratory of Medical Investigation (LIM-36), Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Laila
authors.initials: L
authors.lastname: Lima
authors.affiliation: Neonatal Intensive Care Unit, Instituto da Criança, Hospital das Clínicas, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Ana Carolina Costa
authors.initials: ACC
authors.lastname: Redondo
authors.affiliation: Neonatal Intensive Care Unit, Instituto da Criança, Hospital das Clínicas, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Maria Esther Jurfest Rivero
authors.initials: MEJR
authors.lastname: Ceccon
authors.affiliation: Laboratory of Medical Investigation (LIM-36), Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Magda
authors.initials: M
authors.lastname: Carneiro-Sampaio
authors.affiliation: Laboratory of Medical Investigation (LIM-36), Department of Pediatrics, Medical School, University of São Paulo, São Paulo, Brazil.
authors.forename: Patricia
authors.initials: P
authors.lastname: Palmeira
mesh_terms: D000328:Adult; D002478:Cells, Cultured; D004926:Escherichia coli / Q000502:physiology*; D004927:Escherichia coli Infections / Q000276:immunology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007231:Infant, Newborn; D009000:Monocytes / Q000382:microbiology / Q000502:physiology*; D009504:Neutrophils / Q000276:immunology / Q000382:microbiology / Q000502:physiology*; D010587:Phagocytosis; D016897:Respiratory Burst; D018805:Sepsis / Q000276:immunology*; D013203:Staphylococcal Infections / Q000276:immunology*; D013211:Staphylococcus aureus / Q000502:physiology*; D051195:Toll-Like Receptor 2 / Q000235:genetics / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism*
chemical_list: C495342:TLR2 protein, human; C495345:TLR4 protein, human; D051195:Toll-Like Receptor 2; D051197:Toll-Like Receptor 4; D006861:Hydrogen Peroxide
keywords: Escherichia coli; Phagocytes; Preterm newborns; Septicemia; Staphylococcus aureus