Modulation of pro- and anti-inflammatory cytokine production in very preterm infants

BACKGROUND: In premature infants, outcome of infection-associated complications is heterogeneous despite advances in antibiotic treatment and diagnosis. Information on the immune response in preterm infants is limited. Immune modulatory strategies require detailed analysis of mediators and their kinetics.OBJECTIVE: To determine the kinetics of IL-1beta, TNFalpha, IL-6, IL-8, IL-10, gammaINF and G-CSF in preterm and term infants in an ex vivo cord blood culture (CBC) endotoxin model. DESIGN AND METHODS: Cord blood of 25 infants was obtained immediately after birth from the fetal side of the placenta and incubated in culture medium (RPMI 1640) in the presence or absence of 500 pg/ml lipopolysaccharide (LPS) for 48h. TNFalpha, IL-1beta, IL-6 and IL-8 were measured by sequential immunometric assay (IMMULITE, DPC Biermann, Germany); IL-10 (Milenia Biotec, Bad Nauheim, Germany), gammaINF (Diaclone, Besancon, France) and G-CSF (R & D Systems, Wiesbaden, Germany) were determined by ELISA in supernatants at 0, 4, 8, 12, 24 and 48h. Infants were stratified into three gestational age groups (< or =32 weeks, 33-36 weeks, > or =37 weeks). Variations between the groups were first analyzed for significance by Kruskal-Wallis test and pairs were compared by Mann-Whitney-U test. Effects of gestational age, leucocyte count, hematocrit and frequency of antenatal steroid exposure were tested by linear regression analysis. To correct a possible impact of variable, WBC count, cytokine levels were adjusted according to individual leucocyte numbers. RESULTS: LPS-stimulated maximum levels of IL-6, IL-1beta,TNFalpha and G-CSF in CBC were significantly lower in very preterm infants compared to more advanced gestational age groups. After adjusting the cytokine levels for 10(5) leucocytes, a significant effect of gestational age on IL-6 and G-CSF production (p<0.05) was detected. A non-significant trend towards reduced cytokine levels was observed following multiple antenatal steroid exposures. IL-10:TNFalpha ratio increased in very preterm neonates when compared with the advanced gestational age, although the increase was not significant. CONCLUSIONS: Pro-inflammatory cytokine activity in CBC correlates with gestational age, whereas IL-10 does not. Although ex vivo synthesis of IL-1beta, TNFalpha, IL-6, G-CSF in CBC depends in part on leucocyte numbers, IL-6 and G-CSF synthesis appeared to be related to immaturity. Non-significant effects of multiple antenatal steroid exposure and increased IL-10:TNFalpha ratio in preterm neonates, observed in a small sample size, warrant further investigation.     

不同分娩方式对晚期早产儿肠道菌群的影响

目的 探讨不同分娩方式对晚期早产儿肠道菌群定植的影响。方法 以胎龄（周）为340/7～366/7的15例晚期早产儿为研究对象,根据分娩方式分为自然分娩组（n=8）和剖宫产组（n=7）。收集早产儿出生后3 d、7 d、14 d的粪便标本,应用高通量测序技术对细菌16S rRNA可变区中的V4区进行测序,分析肠道菌群多样性及组成结构。结果 （1）自然分娩组晚期早产儿粪便标本菌群多样性指数逐渐上升,剖宫产组的多样性指数较平稳,两组相比差异无统计学意义;（2）45份粪便标本中共检测出10个菌门,均以变形菌门、厚壁菌门、放线菌门和拟杆菌门为优势菌门,两组晚期早产儿生后变形菌门、拟杆菌门所占比例逐渐降低,厚壁菌门、放线菌门呈增多趋势。两组相比,剖宫产组7 d、14 d时拟杆菌门的相对丰度显著低于自然分娩组（Z=‒2.896,P=0.004;Z=‒2.120,P=0.040）,变形菌门相对丰度仅在7 d时显著高于自然分娩组（Z=‒2.190,P=0.030）;（3）两组研究对象中,除自然分娩组14 d时以双歧杆菌属为优势菌属外,余下均以肠杆菌属为优势菌属。相比于自然分娩组,在7 d时剖宫产组拟杆菌属所占比例显著降低（Z=‒2.806,P=0.005）,肠杆菌属所占比例显著升高（Z=‒2.199,P=0.030）。结论 剖宫产能显著影响婴儿早期肠道菌群的定植,降低肠道中早期拟杆菌的水平。     

The association between proinflammatory cytokine polymorphisms and cerebral palsy in very preterm infants

Cerebral palsy (CP) is a nonprogressive motor disorder caused by white matter damage in the developing brain and is often accompanied with cognitive and sensory disabilities. The risk of CP is higher among infants born preterm than in more mature infants. Intrauterine infection/inflammation, activation of the cytokine network and elevated levels of proinflammatory cytokines in neonatal blood or in amniotic fluid to which the preterm infant is exposed, has been identified as the most common cause of preterm delivery, periventricular leukomalacia (PVL) and CP. The aim of our study was to evaluate the possible association of four TNFα promoter single nucleotide polymorphisms (SNPs) (-1031 T/C, -857 C/T, -308 G/A and -238 G/A), two IL1β SNPs (-511 C/T and +3954 C/T) and one IL6 (-174 C/G) polymorphism with susceptibility to CP in very preterm infants. Statistically significant association between TNFα -1031 T/C high expression genotypes (TC and CC) (OR, 2.339; p=0.016) as well as between TNFα -1031 C high expression allele (OR, 2.065; p=0.013) and risk of CP was observed. In addition, statistically significant association was found between TNFα TC, CC, GG, GG -1031/-857/-308/-238 genotypes combination (OR, 3.286; p=0.034) and risk of CP. Statistically significant association between IL1β TT, CC -511/+3954 genotypes combination and risk of CP (OR, 4.000; p=0.027) was also found. In CP patients with cystic PVL (cPVL) statistically significant association was found between TNFα -1031 T/C high expression genotypes (TC and CC) (OR, 2.361; p=0.038), IL1β -511 C/T high expression genotype TT (OR, 3.215; p=0.030) as well as IL1β -511 T high expression allele (OR, 1.956; p=0.019) and risk of CP. Statistically significant association was also found in patients with cPVL between TNFα TC, CC, GG, GG -1031/-857/-308/-238 genotypes combination (OR, 4.107; p=0.024), as well as IL1β TT, CC -511/+3954 genotypes combination (OR, 7.333; p=0.005) and risk of CP. Our results suggest the role of TNFα and IL1β polymorphisms which have previously been associated with higher circulating levels of these cytokines in genetic susceptibility to white matter damage and consequently CP in very preterm infants.     

益生菌制剂治疗极低出生体重儿喂养不耐受的临床研究

目的探讨益生菌制剂对极低出生体重儿（very low birth weight infant,VLBW）喂养不耐受的影响。方法将56例极低出生体重儿随机分成治疗组和对照组,每组28例。2组均予静脉营养及早产儿配方奶喂哺,治疗组在早产儿配方奶喂哺时添加益生菌制剂,每次0．5g,3次／d,2组同时记录恢复出生体重时间、达全胃肠喂养时间及黄疽消退时间。结果治疗组恢复出生体重时间、达全胃肠喂养时间均显著短于对照组（P〈0．01）,治疗组黄疸消退时间也明显缩短（P〈0．05）。微生态制剂治疗过程中无不良反应发生。结论益生菌制剂可改善极低出生体重儿喂养不耐受,促进患儿体重增长,缩短达到全胃肠喂养时间,值得推广应用。     

Cord blood glutathione depletion in preterm infants: correlation with maternal cysteine depletion

Background

Depletion of blood glutathione (GSH), a key antioxidant, is known to occur in preterm infants.

Objective

Our aim was to determine: 1) whether GSH depletion is present at the time of birth; and 2) whether it is associated with insufficient availability of cysteine (cys), the limiting GSH precursor, or a decreased capacity to synthesize GSH.

Methodology

Sixteen mothers delivering very low birth weight infants (VLBW), and 16 mothers delivering healthy, full term neonates were enrolled. Immediately after birth, erythrocytes from umbilical vein, umbilical artery, and maternal blood were obtained to assess GSH [GSH] and cysteine [cys] concentrations, and the GSH synthesis rate was determined from the incorporation of labeled cysteine into GSH in isolated erythrocytes ex vivo, measured using gas chromatography mass spectrometry.

Principal Findings

Compared with mothers delivering at full term, mothers delivering prematurely had markedly lower erythrocyte [GSH] and [cys] and these were significantly depressed in VLBW infants, compared with term neonates. A strong correlation was found between maternal and fetal GSH and cysteine levels. The capacity to synthesize GSH was as high in VLBW as in term infants.

Conclusion

The current data demonstrate that: 1) GSH depletion is present at the time of birth in VLBW infants; 2) As VLBW neonates possess a fully active capacity to synthesize glutathione, the depletion may arise from inadequate cysteine availability, potentially due to maternal depletion. Further studies would be needed to determine whether maternal-fetal cysteine transfer is decreased in preterm infants, and, if so, whether cysteine supplementation of mothers at risk of delivering prematurely would strengthen antioxidant defense in preterm neonates.     

联合应用BB-12和LGG对极低出生体重早产儿胃肠功能的影响

目的 探讨口服双歧杆菌(BB-12)和鼠李糖乳杆菌(LGG)混合的益生菌制剂对极低出生体重早产儿胃肠功能的影响并评估其安全性.方法 对97例极低出生体重早产儿的临床资料进行回顾性分析.益生菌组45例,对照组52例;益生菌组口服BB-12和LGG的混合益生菌制剂,余治疗同对照组.结果 益生菌组静脉营养、外周置入中心静脉导管(PICC)及鼻饲时间明显长于对照组,合并症例数明显高于对照组(P＜0.05),而坏死性小肠结肠炎(NEC)发病率(6.7％)较对照组(23.1％)明显下降(P＜0.05),且3例NEC(Ⅲ级)均发生在对照组.益生菌组胆汁酸、碱性磷酸酶明显低于对照组(P＜0.05),体重增长速度较对照组有增加趋势;而两组喂养不耐受及胃肠外营养相关性胆汁淤积发病率差异无统计学意义(P＞0.05).益生菌组无益生菌相关败血症、脑膜炎、腹泻、皮疹等不良反应.结论 口服BB-12和LGG混合的益生菌制剂可改善极低出生体重早产儿胃肠功能且相对安全.     

COX-1 and COX-2 polymorphisms in susceptibility to cerebral palsy in very preterm infants

Cerebral palsy (CP) is a nonprogressive motor disorder caused by white matter damage in the developing brain. Recent epidemiological and clinical data suggest intrauterine infection/inflammation as the most common cause of preterm delivery and neonatal complications, including CP. Cyclooxygenases are key enzymes in the conversion of arachidonic acid to prostaglandins. The COX family consists of two isoforms, COX-1 and COX-2. In the brain, COX-2 is constitutively expressed at high levels on pyramidal neurons, while COX-1 is predominantly expressed by microglia and can be upregulated in pathological conditions, such as infection, ischemia and traumatic brain injury. Single nucleotide polymorphisms in the COX-1 and COX-2 gene could have profound effects on COX-1 and COX-2 expression and, directly or indirectly, influence the pathogenesis, development and severity of CP. In this study we investigated the association between single nucleotide polymorphisms of the COX-1 and COX-2 gene and susceptibility to cerebral palsy in very preterm infants. The results of our study showed the association between COX-1 high expression genotype (?842 AA) and COX-1 high expression allele ?842A and risk of CP in infants with cystic periventricular leucomalacia (cPVL). Our results support an important role of COX-1 enzyme on microglial activation during neuroinflammation resulting in huge neuroinflammatory response and the proinflammatory mediator overproduction, with the serious white matter damage and CP development as a consequence.     

肥胖孕妇肠道菌群与子代肥胖的相关性

妊娠期肥胖发生率在世界范围内呈上升趋势,成为影响人类健康的公共卫生问题。肥胖母亲肠道菌群失调导致婴儿早期定植菌群异常,而婴儿早期菌群定植情况与其日后生长发育密切相关,容易导致成年后出现肥胖、胰岛素抵抗、代谢综合征等疾病。因此针对肥胖孕妇肠道菌群分析,以及婴儿肠道菌群及生长发育的分析,对于孕妇孕期管理、健康宣教提高国民整体身体素质具有重要意义。     

1H-NMR-based metabolic profiling of maternal and umbilical cord blood indicates altered materno-foetal nutrient exchange in preterm infants

Background

Adequate foetal growth is primarily determined by nutrient availability, which is dependent on placental nutrient transport and foetal metabolism. We have used ¹H nuclear magnetic resonance (NMR) spectroscopy to probe the metabolic adaptations associated with premature birth.

Methodology

The metabolic profile in ¹H NMR spectra of plasma taken immediately after birth from umbilical vein, umbilical artery and maternal blood were recorded for mothers delivering very-low-birth-weight (VLBW) or normo-ponderal full-term (FT) neonates.

Principal Findings

Clear distinctions between maternal and cord plasma of all samples were observed by principal component analysis (PCA). Levels of amino acids, glucose, and albumin-lysyl in cord plasma exceeded those in maternal plasma, whereas lipoproteins (notably low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) and lipid levels were lower in cord plasma from both VLBW and FT neonates. The metabolic signature of mothers delivering VLBW infants included decreased levels of acetate and increased levels of lipids, pyruvate, glutamine, valine and threonine. Decreased levels of lipoproteins glucose, pyruvate and albumin-lysyl and increased levels of glutamine were characteristic of cord blood (both arterial and venous) from VLBW infants, along with a decrease in levels of several amino acids in arterial cord blood.

Conclusion

These results show that, because of its characteristics and simple non-invasive mode of collection, cord plasma is particularly suited for metabolomic analysis even in VLBW infants and provides new insights into the materno-foetal nutrient exchange in preterm infants.     

Are preterm black infants larger than preterm white infants, or are they more misclassified?

In birth certificate data for Massachusetts resident births from 1978 to 1982, 12-27% of births purportedly under 31 weeks of gestation were probably misclassified, i.e. had birthweight greater than or equal to 2500 g. Correcting for maldistribution of births removed 34% and 23%, respectively, of black and white births with reported gestational ages less than 36 weeks but with implausible weights. Percentages of unknown and incomplete reports of last menstrual period were also significantly higher for blacks. After adjustment, preterm black infants weighed less than whites at each gestational age. The proportion of infants less than 2500 g born at term (greater than or equal to 37 weeks gestation) was higher (although not significantly) among blacks. These findings are consistent with hypotheses that low socioeconomic status negatively affects the rate of intrauterine growth.     

Umbilical artery tone in maternal obesity

Background  

The increasing prevalence of obesity constitutes a major health problem in obstetrics with implications for feto-maternal growth and wellbeing. This study investigated and compared the contractile properties of umbilical arteries excised from obese women, with those excised from women with a normal body mass index (BMI).     

Glucose regulation in preterm newborn infants

After birth, continuous transplacental transfer of glucose is interrupted. Neonates have to provide brain and vital organs with sufficient glucose. In term newborn infants, this is accomplished through well-coordinated hormonal and metabolic adaptive changes. During the first week of life, preterm infants are at high risk of abnormal glucose homeostasis. They are at risk of hypoglycemia due to limited glycogen and fat stores that should have occurred in the third trimester. Continuous glucose infusion is always required soon after birth to maintain the glucose level. However, under such conditions, many preterm infants develop hyperglycemia. Defective islet beta-cell processing of proinsulin is likely related to hyperglycemia. There is also evidence that preterm infants are partially resistant to insulin. By contrast with adults, hepatic glucose production is not suppressed during parenteral glucose infusion. Exogenous insulin infusion partially reduces endogenous glucose production in preterm newborn infants. This treatment is efficient and safe when used with caution. More research is needed to understand the specificity of glucose homeostasis in preterm infants and to evaluate the long-term consequences of metabolic and nutritional support during early life.     

Maternal fatness and viability of preterm infants

To investigate the effect of maternal fatness on the mortality of infants born preterm up to the corrected age of 18 months 795 mother-infant pairs were studied. Maternal fatness was defined by Quetelet''s index (weight/(height²)) and all infants weighed less than 1850 g at birth. In 771 mother-infant pairs maternal age, complications of pregnancy, mode of delivery, parity, social class, and the baby''s sex and gestation were analysed by a logistic regression model for associations with infant mortality (but deaths from severe congenital abnormalities and those occurring during the first 48 hours after birth were excluded). In a subgroup of 284 mother-infant pairs all infant deaths except those from severe congenital abnormalities were analysed in association with the infant''s birth weight and gestation and the mother''s height and weight; this second analysis included another 24 infants who had died within 48 hours after birth. In the first analysis mortality overall was 7% (55/771), rising from 4% (71/173) in thin mothers (Quetelet''s index <20) to 15% (6/40) in mothers with grades II and III obesity (Quetelet''s index >30). After adjusting for major demographic and antenatal factors, including serious complications of pregnancy, maternal fatness was second in importance only to length of gestation in predicting death of infants born preterm. In the second analysis mortality overall was 15% (44/284), rising from 9% (5/53) in thin mothers to 47% (8/17) in mothers with grades II and III obesity. In both analyses the relative risk of death by 18 months post-term was nearly four times greater in infants born to obese mothers than in those born to thin mothers. In addition, maternal fatness was associated with reduced birth weight, whereas it is associated with macrosomia in term infants.These data differ fundamentally from those reported in full term babies of obese mothers. It is speculated that the altered metabolic milieu in obesity may reduce the ability of the fetus to adapt to extrauterine life if it is born preterm.