Apoptosis mediates neutrophil (PMN) phagocytosis and is influenced by cytokines and the Fas/Fas ligand pathway. To determine whether apoptosis of cord blood PMN differs from those of adults, cultured PMN were evaluated by morphological analysis, flow cytometry (TUNEL assay), and DNA gel electrophoresis. In addition, we studied the effect of anti-Fas IgM or cycloheximide on induction of PMN apoptosis. Spontaneous apoptosis (24 h) was less in cord blood PMN (mean ؎ SD; 29 ؎ 9 vs. adults, 56 ؎ 14%, P F 0.001). Treatment (6 h) with anti-Fas IgM induced less apoptosis in cord blood PMN (24 ؎ 6 vs. adults, 63 ؎ 7%, P F 0.001), as did treatment with cycloheximide (13 ؎ 10 vs. adults, 55 ؎ 16%, P F 0.01). These data suggest the pre-existence of proteins that inhibit apoptosis or the absence of those that promote apoptosis in cord blood PMN. J. Leukoc. Biol. 64: 331-336; 1998.

BackgroundThe preterm infant gut microbiota is vulnerable to different biotic and abiotic factors. Although the development of this microbiota has been extensively studied, the mobilome-i.e. the mobile genetic elements (MGEs) in the gut microbiota-has not been considered. Therefore, the aim of this study was to investigate the association of the mobilome with birth weight and hospital location in the preterm infant gut microbiota.MethodsThe data set consists of fecal samples from 62 preterm infants with and without necrotizing enterocolitis (NEC) from three different hospitals. We analyzed the gut microbiome by using 16S rRNA amplicon sequencing, shot-gun metagenome sequencing, and quantitative PCR. Predictive models and other data analyses were performed using MATLAB and QIIME.ResultSThe microbiota composition was significantly different between NEC-positive and NEC-negative infants and significantly different between hospitals. An operational taxanomic unit (OTU) showed strong positive and negative correlation with NEC and birth weight, respectively, whereas none showed significance for mode of delivery. Metagenome analyses revealed high levels of conjugative plasmids with MGEs and virulence genes. Results from quantitative PCR showed that the plasmid signature genes were significantly different between hospitals and in NEC-positive infants.ConclusionOur results point toward an association of the mobilome with hospital location in preterm infants.

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