Increased serum levels of interleukin 6 are associated with severe intraventricular haemorrhage in extremely premature infants

Intrauterine Inflammation and the Onset of Peri-Intraventricular Hemorrhage in Premature Infants

BACKGROUND

Peri-intraventricular hemorrhage (P/IVH) is a common neonatal morbidity among premature infants. The aim of the study was to examine the association between placental and/or fetal inflammation and the onset of P/IVH in premature infants.

METHODS

A prospective study included 125 infants with gestational age 23-29 weeks. Placentas were examined for the presence of chorioamnionitis and funisitis, cord blood was sampled for the measurement of cytokines (IL-6 and IL-8). Fetal inflammation was defined as levels of IL-6 higher than 7.6 pg/ml. P/IVH was defined as early if diagnosed within the 1st day after birth; thereafter P/IVH was defined as late.

RESULTS

Adjusted for the influence of gestational age, early-onset sepsis (OR 3.2, p = 0.045) and no or incomplete antenatal steroid course (OR 6.0, p = 0.001) significantly predicted early P/IVH. Funisitis (OR 1.6, p = 0.06) and fetal inflammation (OR 2.6, p = 0.06) were only partially associated with early hemorrhage. Contrary to that, respiratory distress syndrome (OR 3.4, p = 0.04), mechanical ventilation (OR 5.9, p = 0.008), low blood pressure (OR 3.5, p = 0.02), and vasopressors (OR 5.7, p = 0.002) were associated with late P/IVH. In multivariate analysis no or incomplete steroid course remained independent predictors for early and use of vasopressors for late P/IVH. The interaction of fetal inflammation and vaginal delivery with no or incomplete steroid course increased the risk of early P/IVH.

CONCLUSIONS

These results indicate different risk factors for early and late P/IVH. Neither funisitis nor fetal inflammation independently predicts the onset of P/IVH. However, the interaction of fetal inflammation and vaginal delivery with no or incomplete antenatal steroid course increase the risk of early but not also late P/IVH.

Histological chorioamnionitis and the risk of early intraventricular hemorrhage in infants born < or =28 weeks gestation

OBJECTIVE

To test the hypothesis that histological chorioamnionitis (CA) is not associated with increased risk of early onset intraventricular hemorrhage (IVH).

STUDY DESIGN

Clinical data were prospectively collected for 62 consecutive neonates born before 28 weeks of gestation. Placental histology for CA was performed by a pathologist unaware of the head ultrasound scan (HUS) results. The first HUS was obtained by 30 minutes of life. Follow-up HUS were performed before 24 hours and again at 48 to 72 postnatal hours of life. An IVH (grade I to IV) at less than 72 hours of life was deemed an early hemorrhage.

RESULTS

Nine of the 62 (14.5%) infants had early onset IVH. In all, 29 infants were born to women with histological evidence of CA; 33 infants did not have CA. Infants did not differ in birth weight, gestational age, sex, cord blood pH, 5-minute Apgar score of <7, cesarean delivery, prenatal use of steroids, administration of tocolytics, need for resuscitation, presence of pneumothorax, platelet count at birth, or use of surfactant. Early IVH rates (3/29 in CA vs 6/33 in non-CA) were similar (p=0.48). Two infants in each group with early IVH died before 2 weeks of age. Five additional infants from the CA group developed IVH at more than 72 postnatal hours of life (late onset IVH), and two of those infants progressed to develop periventricular leukomalacia (PVL). In contrast, only three non-CA infants had late IVH and none developed PVL. Logistic regression confirmed that no perinatal variables including CA were associated with early onset IVH.

CONCLUSION

Chorioamnionitis is not associated with increased risk of early IVH.

Management of preterm infants with intrauterine growth restriction

Preterm intrauterine growth restriction (IUGR) is strongly associated with increased mortality and morbidity. In the management of these infants, complications of preterm birth can be amplified by the effect of suboptimal fetal growth. It is important that pregnancies with IUGR are detected before birth, so that delivery can be arranged in a high-risk maternity unit with the appropriate neonatal staff in attendance. The provision of full support for resuscitation and stabilisation of these infants is crucial to the short-term and long-term health of these infants, who have suffered chronic hypoxia and malnutrition in utero. The long term outcome studies of these infants are retrospective and they include SGA infants. The effects of prematurity affect the outcome of IUGR infants. IUGR is associated with cerebral palsy in those delivered more than 32 weeks gestation. Infants less than 32 weeks of gestation may have poor developmental outcome if the head growth is affected, these infants may have associated cognitive and behavioural problems. Children who fail to grow by 2-4 years are at risk of long term growth problems. This paper outlines the acute and long-term management of these infants.

Circulating interferon-gamma and white matter brain damage in preterm infants

The fetal inflammatory response has been suggested as causal in neonatal morbidity. Serial levels of circulating cytokines were evaluated in 74 infants with a mean gestational age (GA) of 27.1 wk. Pro-inflammatory [tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), IL-1 beta, IL-2, IL-6, IL-8, IL-12] [corrected] and modulatory (IL-4, IL-10) cytokines were analyzed from cord blood, and at 6, 24 [corrected] and 72 h postnatal age. Measure of cytokine burden over time was assessed by calculating the area under curve (AUC) for analyzed levels (0-72 h). Premature rupture of membranes (PROM) was associated with higher levels of IL-2 at birth and at 6 h, of IFN-gamma at 6 and 24 h postnatal age and of TNF-alpha at 6 and 24 h. Levels of IFN-gamma at 6, 24, and 72 h were increased in infants developing white matter brain damage (WMD) compared with those without WMD. Infants with arterial hypotension requiring dopamine treatment had an increase in IL-6 with a peak at 6 h of age. Severe intraventricular hemorrhage (IVH) was associated with increase in AUC [(IL-6) and (IL-8), odds ratio (OR) 2.8 and 13.2 respectively], whereas white matter brain damage (WMD) [corrected] was associated with increase in AUC (IFN-gamma; OR, 26.0) [corrected] A fetal immune response with increased postnatal levels of IFN-gamma was associated with development of WMD. PROM was associated with a T-helper 1 cytokine response with increased levels of IFN-gamma. Type of inflammatory response appears of importance for subsequent morbidity.

The relationship of CSF and plasma cytokine levels to cerebral white matter injury in the premature newborn

Ischemia and systemic infection are implicated in the etiology of periventricular white matter injury, a major cause of adverse motor and cognitive outcome in preterm infants. Cytokines are signaling proteins that can be produced as part of the inflammatory response to both ischemia and infection. The aim of this study was to relate cerebrospinal fluid (CSF) concentrations of IL-6, IL-8, IL-10, tumor necrosis factor alpha (TNF-alpha), and interferon gamma (IFN-gamma) to magnetic resonance-defined white matter injury in preterm infants. Relationships between CSF and plasma cytokine concentrations were also examined. Preterm infants (<or=32 wk) and more mature infants from The Royal Women's Hospital, Melbourne, Australia, and Christchurch Women's Hospital, Christchurch, New Zealand, were eligible for study if they required a clinically indicated lumbar puncture. Plasma samples were obtained in a subgroup of Christchurch infants. Preterm infants underwent advanced quantitative volumetric magnetic resonance imaging using a 1.5-Tesla scanner at term equivalent. One hundred forty-six infants were enrolled and 190 CSF and 42 plasma samples obtained. There was no significant correlation between paired CSF and plasma concentrations for any cytokine. In comparing plasma and CSF concentrations, levels of IL-8 were significantly higher in CSF than plasma. Preterm infants with MRI-defined cerebral white matter injury had higher levels of IL-6, IL-10, and TNF-alpha in the CSF than infants without such injury. Plasma cytokine concentrations may not reflect CSF cytokine levels or inflammatory events within the brain. Elevated CSF levels of cytokines in infants with white matter injury suggest an altered inflammatory balance.

VWF-cleaving protease (ADAMTS13) in premature infants

BACKGROUND

Patients with thrombotic thrombocytopenic purpura (TTP) are deficient in von Willebrand factor (VWF)-cleaving protease, called ADAMTS13, and are prone to develop abnormal intravascular platelet aggregation leading to focal cerebral ischaemia. We speculated that low levels of ADAMTS13 are present in premature infants. This might result in platelet aggregation with subsequent ischaemia, vessel rupture and haemorrhage, and thus contribute to intraventricular haemorrhage and periventricular leucomalacia (IVH and PVL).

PATIENTS AND METHODS

Nine preterm infants with gestational ages 23.7 to 30.9 (median 25.7) wk, and 10 healthy term control infants with gestational ages 36.9 to 39 (median 37.9) wk were included. Blood was sampled from the umbilical cord at delivery, and levels of ADAMTS13, VWF antigen and VWF collagen binding activity were analysed.

RESULTS

The mean ADAMTS13 level in preterm infants was lower than in the term infants, but the difference between the groups was not statistically significant. However, in the preterm group there was a positive correlation between ADAMTS13 and both gestational age (r = 0.70, p = 0.035) and birthweight (r = 0.83, p = 0.005). Three preterm infants had ADAMTS13 of 18-20%. One of these developed a germinal matrix haemorrhage and PVL, and this infant had the lowest measured ADAMTS13 of all. The levels of VWF antigenand VWF collagen bindingactivity were higher in the preterm infants.

CONCLUSION

This pilot study showed that preterm infants have low levels of ADAMTS13. Enzyme substitution may be a therapeutic option if an association with IVH or PVL can be confirmed in larger patient groups.

Prematurity and intrauterine growth retardation--double jeopardy?

Premature infants born with IUGR are at a several-fold increased risk for mortality and major neonatal morbidities, including RDS, BPD, ROP, and NEC. These severe complications of prematurity are intensified by the effect of suboptimal fetal growth. The possible pathophysiologic processes initiated in utero and continuing after birth have been discussed. Recently reported data suggest that IUGR is a risk factor in programming for the later development of cardiovascular diseases, hypertension, and diabetes mellitus in adult life. Experimental research related to the pathophysiology and etiology of these conditions may enable appropriate intervention directed at reducing the excess risk associated with the short- and long-term mortality and morbidity among premature SGA infants.

Lung and Brain Damage in Preterm Newborns

The relationships among bronchopulmonary dysplasia (BPD), brain white matter damage (WMD) and cerebral palsy (CP) are far from simple. Apparently, BPD and WMD are not associated, while BPD and CP are. The most likely explanation for this paradox is that ultrasound imaging does not identify all the WMD that might lead to CP ('tip-of-the-iceberg effect'). We discuss further methodological inconsistencies, etiological peculiarities related to antenatal infection/inflammation, and intervention-related issues. In particular, we expand on the multiple-hit scenario in the etiology of BPD and offer support for the hypothesis that it is not lung disease, but factors associated with lung disease (e.g. postnatal steroid exposure) that increase the risk for developmental disability in childhood.

Modification of cord blood IL-6 production with IgM enriched human immunoglobulin in term and preterm infants

Pro-inflammatory cytokines contribute significantly to the morbidity of premature infants. IL-6 and IL-8 are involved in the pathogenesis of pulmonary and cerebral tissue injury. The effect of human immunoglobulin preparations on cytokine production in preterm infants has not been studied. We investigated the influence of immunoglobulin on LPS stimulated IL-6 and IL-8 production in cord blood of healthy preterm neonates. Ten non-infected preterm infants delivered by cesarean section and 5 healthy term neonates were included. In the preterm infants, significant IL-6 production was observed in the absence of immunoglobulin after 4 h [median 113 (39-725) pg/ml], 8 h [375 (234-1795) pg/ml] and 12 h [360 (248-2765) pg/ml] of LPS incubation. IL-6 concentrations were significantly lower after incubation with LPS+immunoglobulin after 4 h [median 38 (5-568) pg/ml; p=0.005], 8 h [178 (10-1830) pg/ml; p=0.001] and 12 h [182 (29-2530) pg/ml; p=0.002]. Cultures from term infants produced IL-6 levels approx. 4 times of those from premature infants unaffected by immunoglobulin. IL-8 production also correlated to gestational age and was not affected by immunoglobulin in both groups. Human immunoglobulin preparation may modify IL-6 production in cord blood cultures from premature infants.