Effects of Wharton's jelly-derived mesenchymal stem cells on neonatal neutrophils.

BACKGROUND: Mesenchymal stem cells (MSCs) have been proposed as autologous therapy for inflammatory diseases in neonates. MSCs from umbilical cord Wharton's jelly (WJ-MSCs) are accessible, with high proliferative capacity. The effects of WJ-MSCs on neutrophil activity in neonates are not known. We compared the effects of WJ-MSCs on apoptosis and the expression of inflammatory, oxidant, and antioxidant mediators in adult and neonatal neutrophils. METHODS: WJ-MSCs were isolated, and their purity and function were confirmed by flow cytometry. Neutrophils were isolated from cord and adult blood by density centrifugation. The effects of neutrophil/WJ-MSC co-culture on apoptosis and gene and protein expression were measured. RESULTS: WJ-MSCs suppressed neutrophil apoptosis in a dose-dependent manner. WJ-MSCs decreased gene expression of NADPH oxidase-1 in both adult and neonatal neutrophils, but decreased heme oxygenase-1 and vascular endothelial growth factor and increased catalase and cyclooxygenase-2 in the presence of lipopolysaccharide only in adult cells. Similarly, generation of interleukin-8 was suppressed in adult but not neonatal neutrophils. Thus, WJ-MSCs dampened oxidative, vascular, and inflammatory activity by adult neutrophils, but neonatal neutrophils were less responsive. Conversely, Toll-like receptor-4, and cyclooxygenase-2 were upregulated in WJ-MSCs only in the presence of adult neutrophils, suggesting an inflammatory MSC phenotype that is not induced by neonatal neutrophils. CONCLUSION: Whereas WJ-MSCs altered gene expression in adult neutrophils in ways suggesting anti-inflammatory and antioxidant effects, these responses were attenuated in neonatal cells. In contrast, inflammatory gene expression in WJ-MSCs was increased in the presence of adult but not neonatal neutrophils. These effects should be considered in clinical trial design before WJ-MSC-based therapy is used in infants.

Effects of maternal exposure to phthalates and bisphenol A during pregnancy on gestational age.

OBJECTIVE: Phthalates and bisphenol A (BPA) are ubiquitous environmental toxicants, present in high concentrations in numerous consumer products. We hypothesized that maternal exposure to phthalates and BPA in pregnancy is associated with shortened gestation. METHODS: Urinary phthalate and BPA metabolites from 72 pregnant women were measured at the last obstetric clinic visit prior to delivery. Using linear regression models, we estimated the change in gestational age associated with each interquartile range (IQR) increase in phthalate and BPA metabolite concentration. RESULTS: IQR increases in urinary mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and BPA concentrations were associated with 4.2 and 1.1 d decreases in gestation, respectively. When stratified by gender, these alterations were found only in male infants. CONCLUSIONS: We conclude that MEHHP and BPA (free + glucuronide) are associated with reductions in gestation, with effects observed only in males. Our findings are consistent with the idea that these agents induce gender-specific alterations in signaling via PPAR-γ transcription factor, androgen precursors and/or inflammatory mediators during the initiation of labor.

Effects of bilirubin on neutrophil responses in newborn infants.

BACKGROUND: Newborns are susceptible to inflammatory diseases due to defects in clearing activated immune cells from tissues. Therefore, mechanisms have likely evolved to protect neonates from leukocyte-mediated cytotoxicity. Bilirubin has antioxidant activity, and it is possible that it also exerts effects on cellular immune responses in jaundiced infants. OBJECTIVES: We hypothesize that bilirubin increases expression of antioxidant genes and decreases production of inflammatory proteins in neonatal neutrophils. METHODS: Neutrophils were isolated from umbilical cord blood, and from adults for comparison, and treated with bilirubin (10-300 µmol/l, equivalent to unbound bilirubin 3-40 nmol/l), in the presence or absence of lipopolysaccharide (LPS). Expression of genes for antioxidant enzymes [superoxide dismutase (SOD), heme-oxygenase-1 (HO-1)] and heme-dependent enzymes involved in inflammation [NADPH oxidase-1 (NOX-1), cyclooxygenase-2 (COX-2)] was measured by PCR. Inflammatory cytokines were measured by bead array analysis using flow cytometry. RESULTS: We found that LPS induced production of interleukin (IL)-8, IL-1ß, and macrophage inhibitory protein-1ß (MIP-1ß). Bilirubin increased basal production of IL-8 and IL-1ß, but downregulated LPS-induced generation of IL-8 and MIP-1ß. It also upregulated SOD and HO-1 gene expression. We observed an unexpected bilirubin-induced increase in gene expression of NOX-1 in LPS-activated cells, and of COX-2 in both resting and activated cells. CONCLUSIONS: These findings suggest that bilirubin suppresses inflammation and increases antioxidant enzyme generation in activated neonatal neutrophils. The unexpected increases in NOX-1 and COX-2 expression may represent an early response, with physiologic effects mitigated by increased antioxidant activity. Further studies will be needed to define levels of bilirubin that optimize its protective effects, while minimizing potential inflammatory toxicity.

Decreased anti-inflammatory responses to vitamin D in neonatal neutrophils.

Neutrophil activity is prolonged in newborns, suggesting decreased exposure and/or responses to immunosuppressive modulators, such as 1,25-hydroxyvitamin D(3) (1,25-vit D(3)). We hypothesized that 1,25-vit D(3) suppresses neutrophil activation and that this response is impaired in newborns. Consistent with this, 1,25-vit D(3) decreased LPS-induced expression of macrophage inflammatory protein-1ß and VEGF in adult, but not neonatal, neutrophils. Expression of vitamin D receptor (VDR) and 25-hydroxyvitamin D(3)-1α-hydroxylase was reduced in neonatal, relative to adult neutrophils. Moreover, 1,25-vit D(3) induced VDR gene expression in activated adult, but not neonatal, neutrophils. 1,25-vit D(3) also suppressed expression of cyclooxygenase-2 and induced expression of 5-lipoxygenase in LPS-exposed adult neutrophils, while neonatal cells were not affected. 1,25-vit D(3) had no effect on respiratory burst in either adult or neonatal cells. Anti-inflammatory activity of vitamin D is impaired in neonatal neutrophils, and this may be due to decreased expression of VDR and 1α-hydroxylase. Insensitivity to 1,25-vit D(3) may contribute to chronic inflammation in neonates.