Diminished phagocytosis-induced cell death (PICD) in neonatal monocytes upon infection with Escherichia coli.
An imbalance in apoptosis or survival of immune cells plays an essential role in the pathophysiology of sepsis. Phagocytosis-induced cell death (PICD) is a common result of the pathogen-host cell interaction mediated by reactive oxygen species (ROS). Neonatal sepsis is frequently characterized by hyperinflammation. Cord blood monocytes (CBMO) are equivalent to monocytes of adults [peripheral blood monocytes (PBMO)], both in terms of phagocytosis and killing of Escherichia coli. We investigated whether CBMO are less sensitive toward PICD compared with PBMO. Monocytes were infected with green fluorescent protein (GFP)-labeled E. coli. Phagocytic activity, cell-count, Annexin V staining, hypoploid DNA content, CD95 and CD95L expression, and caspase-8 and -9 activities were analyzed by flow cytometry, ROS production by chemiluminescence, and CD95L mRNA expression by reverse-transcriptase polymerase chain reaction. With equal phagocytic activity and ROS production, PBMO cell count was decreased by 82 +/- 6% versus 28 +/- 8% for CBMO after infection. Annexin V binding was enhanced fivefold on PBMO; 56 +/- 15% of PBMO showed a hypodiploid DNA content compared with 9 +/- 6% of CBMO. Caspases CD95L and CD95L mRNA were up-regulated in PBMO. Our results indicate that CBMO are less sensitive toward E. coli-mediated PICD than PBMO. Modifying monocyte apoptosis may be a target for future interventions in sepsis.
Department of Neonatology, University Children's Hospital, Tuebingen, 72076, Germany.
Christian
C
Gille
Anja
A
Leiber
Bärbel
B
Spring
Volkhard A J
VA
Kempf
Juergen
J
Loeffler
Christian F
CF
Poets
Thorsten W
TW
Orlikowsky
D000328:Adult; D017304:Annexin A5 / Q000378:metabolism; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D002478:Cells, Cultured; D004247:DNA / Q000378:metabolism; D004789:Enzyme Activation; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D004927:Escherichia coli Infections / Q000201:enzymology / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D053222:Fas Ligand Protein / Q000235:genetics / Q000378:metabolism; D005312:Fetal Blood / Q000166:cytology; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D008562:Membrane Glycoproteins / Q000378:metabolism; D009000:Monocytes / Q000201:enzymology / Q000276:immunology / Q000378:metabolism / Q000382:microbiology / Q000473:pathology*; D010587:Phagocytosis; D012333:RNA, Messenger / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D043562:Receptors, G-Protein-Coupled; D013997:Time Factors
C095004:ADGRE5 protein, human; D017304:Annexin A5; D015703:Antigens, CD; D053222:Fas Ligand Protein; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D043562:Receptors, G-Protein-Coupled; D049452:Green Fluorescent Proteins; D004247:DNA; C505530:CASP8 protein, human; D053181:Caspase 8; D053453:Caspase 9