Secretory-IgA binding to intestinal microbiota attenuates inflammatory reactions as the intestinal barrier of preterm infants matures

Previous work has shown that Secretory-IgA (SIgA) binding to the intestinal microbiota is variable and may regulate host inflammatory bowel responses. Nevertheless, the impact of the SIgA functional binding to the microbiota remains largely unknown in preterm infants whose immature epithelial barriers make them particularly susceptible to inflammation. Here, we investigated SIgA binding to intestinal microbiota isolated from stools of preterm infants <33 weeks gestation with various levels of intestinal permeability. We found that SIgA binding to intestinal microbiota attenuates inflammatory reactions in preterm infants. We also observed a significant correlation between SIgA affinity to the microbiota and the infant's intestinal barrier maturation. Still, SIgA affinity was not associated with developing host defenses, such as the production of mucus and inflammatory calprotectin protein, but it depended on the microbiota shifts as the intestinal barrier matures. In conclusion, we reported an association between the SIgA functional binding to the microbiota and the maturity of the preterm infant's intestinal barrier, indicating that the pattern of SIgA coating is altered as the intestinal barrier matures.

Renal versus cerebral saturation trajectories: the perinatal transition in preterm neonates

BACKGROUND

The aim of this study was to develop reference renal saturation (rSrO₂) curves in premature infants, depict how they differ from cerebral saturation (rScO₂) curves, and evaluate the effect of blood pressure on these values using near-infrared spectroscopy (NIRS).

METHODS

This is a prospective cohort study of 57 inborn infants <12 h and <30 weeks gestation. rScO₂, rSrO₂, fractional tissue oxygen extraction (FTOE), and mean arterial blood pressure (MAP) were continuously monitored every 30 s for 96 h. Quantile regression was used to establish nomograms, and mean saturation values were evaluated for different MAP ranges.

RESULTS

Median rSrO₂ at the start of monitoring was ~10% higher than rScO₂. rSrO₂ showed a significant decline over time while rScO₂ peaked at 26 h. FTOE demonstrated a similar but inverse trend to their saturation counterparts. rScO₂ declined as MAP increased, while rSrO2 showed a peak and decline as MAP increased.

CONCLUSIONS

We provide rSrO₂ reference curves for the first 4 days of life, which differ in their trajectory from rScO₂ and from what has previously been reported for rSrO₂ in the full-term population. In addition, we observed a peak and decline in renal saturation with increasing MAP, suggesting a renovascular response to blood pressure changes.

IMPACT

This article depicts reference renal saturation curves during the perinatal transition in preterm infants. We show how renal saturation compares to cerebral saturation trends over time. We describe a peak and decline in renal saturation with increasing MAP, suggesting a renovascular response to blood pressure changes.

Mice Expressing Cosegregating Single Nucleotide Polymorphisms (D298G and N397I) in TLR4 Have Enhanced Responses to House Dust Mite Allergen

Asthma is a common and ubiquitous chronic respiratory disease that is associated with airway inflammation and hyperreactivity resulting in airway obstruction. It is now accepted that asthma is controlled by a combination of host genetics and environment in a rather complex fashion; however, the link between sensing of the environment and development and exacerbation of allergic lung inflammation is unclear. Human populations expressing cosegregating D299G and T399I polymorphisms in the TLR4 gene are associated with a decreased risk for asthma in adults along with hyporesponsiveness to inhaled LPS, the TLR4 ligand. However, these data do not account for other human genetic or environmental factors. Using a novel mouse strain that expresses homologous human TLR4 polymorphisms (TLR4-single nucleotide polymorphism [SNP]), we directly tested the effect of these TLR4 polymorphisms on in vivo responses to allergens using two models of induction. We report that intact TLR4 is required for allergic inflammation when using the OVA and LPS model of induction, as cellular and pathological benchmarks were diminished in both TLR4-SNP and TLR4-deficent mice. However, in the more clinically relevant model using house dust mite extract for induction, responses were enhanced in the TLR4-SNP mice, as evidenced by greater levels of eosinophilic inflammation, Th2 cytokine production, and house dust mite-specific IgG1 production compared with wild-type mice; however, mucus production and airway hyperreactivity were not affected. These results suggest that the TLR4 polymorphic variants (genes) interact differently with the allergic stimulation (environment).

Altered Gut Microbiome and Fecal Immune Phenotype in Early Preterm Infants With Leaky Gut

Intestinal barrier immaturity, or "leaky gut", is the proximate cause of susceptibility to necrotizing enterocolitis in preterm neonates. Exacerbated intestinal immune responses, gut microbiota dysbiosis, and heightened barrier injury are considered primary triggers of aberrant intestinal maturation in early life. Inordinate host immunity contributes to this process, but the precise elements remain largely uncharacterized, leaving a significant knowledge gap in the biological underpinnings of gut maturation. In this study, we investigated the fecal cytokine profile and gut microbiota in a cohort of 40 early preterm infants <33-weeks-gestation to identify immune markers of intestinal barrier maturation. Three distinct microbiota types were demonstrated to be differentially associated with intestinal permeability (IP), maternal breast milk feeding, and immunological profiles. The Staphylococcus epidermidis- and Enterobacteriaceae-predominant microbiota types were associated with an elevated IP, reduced breast milk feeding, and less defined fecal cytokine profile. On the other hand, a lower IP was associated with increased levels of fecal IL-1α/β and a microbiota type that included a wide array of anaerobes with expanded fermentative capacity. Our study demonstrated the critical role of both immunological and microbiological factors in the early development of intestinal barrier that collectively shape the intestinal microenvironment influencing gut homeostasis and postnatal intestinal maturation in early preterm newborns.

Assessment of Neonatal Intensive Care Unit Sound Exposure Using a Smartphone Application

OBJECTIVE

This study aimed to determine the impact of neonatal intensive care unit (NICU) design and environmental factors on neonatal sound exposures. We hypothesized that monitoring with a smartphone application would identify modifiable environmental factors in different NICU design formats.

STUDY DESIGN

Minimum, maximum, and peak decibel (dB) recordings were obtained using the Decibel X phone app, and the presence of noise sources was recorded in each patient space at three NICUs over a 6-month period (December 2017 to May 2018). Data were analyzed by Student's t-test and ANOVA with Bonferroni correction. Data were collected at the University of Maryland Medical Center single family room (SFR) level IV and St. Agnes Healthcare hybrid pod/single family room level III NICU, Baltimore, MD and at Prince George's Hospital Center open-pod design Level III NICU, Cheverly, MD.

RESULTS

All recordings in the three NICUs exceeded the American Academy of Pediatrics (AAP) recommended <45 dB level. The maximum and peak dB were highest in the open pod format level III NICU. Conversations/music alone and combined with other factors contributed to increased sound exposure. Sound exposure varied by day/night shift, with higher day exposures at the level III hybrid and open pod NICUs and higher night exposures at the level IV SFR NICU.

CONCLUSION

Although sound exposure varied by NICU design, all recordings exceeded the AAP recommendation due, in part, to potentially modifiable environmental factors. A smartphone application may be useful for auditing NICU sound exposure in quality improvements efforts to minimize environmental sound exposure.

KEY POINTS

· Smartphone application was used to assess NICU sound exposure.. · All cases of sound exposure exceed recommendations.. · A smartphone application was used to identify modifiable factors..

Impact of red blood cell transfusions on intestinal barrier function in preterm infants

OBJECTIVE

To determine the relationships of red blood cell (RBC) transfusion and enteral feeding to changes in intestinal permeability (IP) measured by the relative intestinal uptake of lactulose (La) and rhamnose (Rh) in preterm infants <33 wk gestation.

DESIGN/METHODS

Infants 240-326wk gestation received La/Rh solution enterally on study days 1, 8 and 15.Urinary La/Rh ratio was measured by HPLC. Hematocrit preceding transfusion, total RBC transfusion volume, volume/kg, and feeding status during each study interval (birth-d1; d1-d8, and d8-d15) were determined.

RESULTS

Of the seventeen (40.5%) subjects who received≥1 transfusion during the study period, 12 (70.6%) infants were <28 wk gestation and 5 (29.4%) infants were≥28 wk gestation, p < 0.0001. Lower pre-transfusion hematocrit was observed in intervals preceding high IP (La/Rh > 0.05) than in intervals preceding low IP (La/Rh≤0.05) measurements (33 vs 35.8, p = 0.1051). RBC transfusions occurred more frequently in intervals preceding high IP than in intervals preceding low IP (26.8%; vs 8.3%, p = 0.0275) with 5-fold higher total RBC volume and volume/kg in intervals preceding any time point with high IP. RBC transfusion during an interval was associated with a three-fold increased risk of high IP (aOR 2.7; 95% C.I 0.564-12.814; p = 0.2143). Exclusive breast milk exposure and post-menstrual age reduced the risk for high IP following RBC transfusion.

CONCLUSIONS

Both RBC transfusion number and volume was associated with subsequent high IP measurements in preterm infants <33 weeks gestation and potentially may contribute to impairment of the preterm intestinal barrier.

Cerebral autoregulation in premature infants during the first 96 hours of life and relationship to adverse outcomes

OBJECTIVE

To test the hypothesis that impaired cerebral autoregulation (ICA) increases the susceptibility of premature infants to adverse outcomes, we determined the relationship of ICA and cerebral reactivity (CR) measured in the first 96 hours of life to the outcome of grade 3 or 4 intraventricular haemorrhage (IVH) and/or death within 1 month.

SETTING

Single-centre level IV neonatal intensive care unit.

PATIENTS

Neonates 24-29 weeks' gestation less than 12 hours old with invasive blood pressure monitoring.

DESIGN

Cerebral saturations and mean arterial blood pressure were recorded every 30 s for 96 hours. For each 10 min epoch, the correlation coefficient (r) was calculated for mean arterial blood pressure versus cerebral saturations. The epoch was considered to have ICA if r>0.5 and CR if r<0.

RESULTS

Sixty-one subjects were included. During the first 96 hours, ICA occurred 17.6% and CR occurred 41% of recorded time. In those without adverse outcomes, ICA decreased and CR increased by postnatal day (p<0.05). Adjusted for birth weight and gestational age, those with IVH and those who died spent more time with ICA and less time with CR (p<0.05) over the entire recording period. Those with IVH had 1.5-fold increase in time with ICA on day 2 (p=0.021), and decrease in time with CR on day 3 (p=0.036). Compared with survivors, non-survivors spent more time with ICA on days 3 and 4 (p<0.005), and less with CR on day 3 (p=0.032).

CONCLUSION

ICA and CR vary by postnatal day and these patterns are associated with adverse outcomes.

Microbial Biomarkers of Intestinal Barrier Maturation in Preterm Infants

Intestinal barrier immaturity, or "leaky gut," is the proximate cause of susceptibility to necrotizing enterocolitis in preterm neonates. However, the impact of intestinal microbiota development on intestinal mucosal barrier maturation has not been evaluated in this population. In this study, we investigated a longitudinally sampled cohort of 38 preterm infants < 33 weeks gestation monitored for intestinal permeability (IP) and fecal microbiota during the first 2 weeks of life. Rapid decrease in IP indicating intestinal barrier function maturation correlated with significant increase in community diversity. In particular, members of the Clostridiales and Bifidobacterium were highly transcriptionally active, and progressively increasing abundance in Clostridiales was significantly associated with decreased intestinal permeability. Further, neonatal factors previously identified to promote intestinal barrier maturation, including early exclusive breastmilk feeding and shorter duration antibiotic exposure, associate with the early colonization of the intestinal microbiota by members of the Clostridiales, which altogether are associated with improved intestinal barrier function in preterm infants.

Intestinal Barrier Maturation in Very Low Birthweight Infants: Relationship to Feeding and Antibiotic Exposure

OBJECTIVE

To test the hypothesis that feeding and antibiotic exposures affect intestinal barrier maturation in preterm infants, we serially measured intestinal permeability (IP) biomarkers in infants <33 weeks gestation (gestational age [GA]) during the first 2 weeks of life.

STUDY DESIGN

Eligible infants <33 weeks GA were enrolled within 4 days of birth in a prospective study of IP biomarkers (NCT01756040). Study participants received the nonmetabolized sugars lactulose/rhamnose enterally on study days 1, 8, and 15 and lactulose/rhamnose were measured in urine by high-performance liquid chromatography. Serum zonulin and fecal alpha-1-anti-trypsin, 2 other IP markers, were measured by semiquantitative Western blot and ELISA, respectively.

RESULTS

In a cohort of 43 subjects, the lactulose/rhamnose ratio was increased on day 1 and decreased over 2 weeks, but remained higher in infants born at ≤28 weeks of gestation compared with IP in infants born at >28 weeks of gestation. Exclusive breastmilk feeding was associated with more rapid maturation in intestinal barrier function. A cluster analysis of 35 subjects who had urine samples from all time points revealed 3 IP patterns (cluster 1, normal maturation: n = 20 [57%]); cluster 2, decreased IP during the first week and subsequent substantial increase: n = 5 [14%]); and cluster 3, delayed maturation: n = 10 [29%]). There were trends toward more prolonged antibiotic exposure (P = .092) and delayed initiation of feeding ≥4 days (P = .064) in infants with abnormal IP patterns.

CONCLUSIONS

Intestinal barrier maturation in preterm infants is GA and postnatal age dependent, and is influenced by feeding with a maturational effect of breastmilk feeding and possibly by antibiotic exposures.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01756040.

Enhanced allergic responsiveness after early childhood infection with respiratory viruses: Are long-lived alternatively activated macrophages the missing link?

Early childhood infection with respiratory viruses, including human rhinovirus, respiratory syncytial virus (RSV) and influenza, is associated with an increased risk of allergic asthma and severe exacerbation of ongoing disease. Despite the long recognition of this relationship, the mechanism linking viral infection and later susceptibility to allergic lung inflammation is still poorly understood. We discuss the literature and provide new evidence demonstrating that these viruses induce the alternative activation of macrophages. Alternatively activated macrophages (AAM) induced by RSV or influenza infection persisted in the lungs of mice up to 90 days after initial viral infection. Several studies suggest that AAM contribute to allergic inflammatory responses, although their mechanism of action is unclear. In this commentary, we propose that virus-induced AAM provide a link between viral infection and enhanced responses to inhaled allergens.

The Objective Use of Pulse Oximetry to Predict Respiratory Support Transition in Preterm Infants: An Observational Pilot Study

BACKGROUND

Preterm infants often require some form of respiratory support with supplemental oxygen and are monitored by continuous pulse oximetry (SpO2 ). The study objective was to determine whether the histogram distribution of SpO2 over a 24-h period will predict readiness for weaning respiratory support in preterm infants. We hypothesize that infants with ≥15% of time spent with SpO2 <86% before transitioning from CPAP or high-flow nasal cannula (HFNC) to low-flow nasal cannula, oxyhood, or room air are more likely to fail transitioning.

METHODS

The SpO2 histograms were downloaded daily for 31 infants, 24-32 weeks gestational age, before transition from CPAP or HFNC to low-flow nasal cannula, oxyhood, or room air. The SpO2 histogram downloads were continued for each infant for 1 week after transition or when the infant reached 36 weeks postmenstrual age or when SpO2 monitoring was discontinued. Failure was defined as an increase in respiratory support within 72 h of transitioning. We compared the percentage of time for each SpO2 quintile for the 24-h periods before and immediately following CPAP/HFNC transitioning between groups.

RESULTS

Twenty-four subjects transitioned successfully, but 7 subjects failed. Two of 7 subjects (28.6%) who failed transition experienced SpO2 <86% ≥15% of the time pretransition compared with none in the success group (P = .045). The failure group experienced SpO2 <86% 10.7 ± 11.9% of time pre-wean compared with 3.3 ± 4.7% of time in the success group (P = .02). In contrast, infants who were successfully weaned tended to experience a greater percentage of time with SpO2 >95% compared with the failure group, both pre-wean (54.3 ± 36.1% vs. 33 ± 27.7%, P = .16) and post-wean (52 ± 35.4% vs. 27.4 ± 27.7%, P = .10).

CONCLUSIONS

These data suggest that pulse oximetry histograms may be useful in assessing CPAP/HFNC support transition readiness.

Antenatal factors modulate hearing screen failure risk in preterm infants

OBJECTIVE

The objective of this study was to characterise the effects of antenatal inflammatory factors and maternal therapies on neonatal hearing screen outcomes in very low birthweight infants.

METHODS

We conducted a retrospective study of a cohort of infants <33 weeks' gestational age and <1501 g birth weight prospectively enrolled between 1999 and 2003 for whom placental pathology, cord blood interleukin (IL) 6, IL-1ß, tumour necrosis factor-α and neonatal hearing screen results were available.

RESULTS

Of 289 infants with documented hearing screen results, 244 (84%) passed and 45 (16%) failed the hearing screen (unilateral, N=25 (56%); bilateral, N=20 (44%)). In the final logistic model, the fetal inflammatory response syndrome defined as the presence of fetal vasculitis and/or cord serum IL-6>18.2 pg/mL was the factor with greatest risk for hearing screen failure (OR 3.62, 95% CI 1.38 to 9.5). A patent ductus arteriosus treated with indomethacin significantly increased the risk (OR 3.3, 95% CI 1.3 to 8.26), while combined maternal steroid and magnesium sulfate exposure (0.37, 95% CI 0.11 to 0.81) reduced the risk for hearing screen failure.

CONCLUSIONS

Intrauterine infection with a fetal inflammatory response is a risk factor for neonatal hearing loss while maternal therapies significantly reduced the risk of neonatal hearing loss in very low birthweight infants.

Glucose monitoring in neonates: need for accurate and non-invasive methods

Neonatal hypoglycaemia can lead to devastating consequences. Thus, constant, accurate and safe glucose monitoring is imperative in neonatal care. However, point-of-care (POC) devices for glucose testing currently used for neonates were originally designed for adults and do not address issues specific to neonates. This review will address currently available monitoring options and describe new methodologies for non-invasive glucose monitoring in newborns.

Detection of trace glucose on the surface of a semipermeable membrane using a fluorescently labeled glucose-binding protein: a promising approach to noninvasive glucose monitoring

BACKGROUND

Our motivation for this study was to develop a noninvasive glucose sensor for low birth weight neonates. We hypothesized that the underdeveloped skin of neonates will allow for the diffusion of glucose to the surface where it can be sampled noninvasively. On further study, we found that measurable amounts of glucose can also be collected on the skin of adults.

METHOD

Cellulose acetate dialysis membrane was used as surrogate for preterm neonatal skin. Glucose on the surface was collected by saline-moistened swabs and analyzed with glucose-binding protein (GBP). The saline-moistened swab was also tested in the neonatal intensive care unit. Saline was directly applied on adult skin and collected for analysis with two methods: GBP and high-performance anion-exchange chromatography (HPAEC).

RESULTS

The amount of glucose on the membrane surface was found (1) to accumulate with time but gradually level off, (2) to be proportional to the swab dwell time, and (3) the concentration of the glucose solution on the opposite side of the membrane. The swab, however, failed to absorb glucose on neonatal skin. On direct application of saline onto adult skin, we were able to measure by HPAEC and GBP the amount of glucose collected on the surface. Blood glucose appears to track transdermal glucose levels.

CONCLUSIONS

We were able to measure trace amounts of glucose on the skin surface that appear to follow blood glucose levels. The present results show modest correlation with blood glucose. Nonetheless, this method may present a noninvasive alternative to tracking glucose trends.

Molecular methods for the detection of Mycoplasma and ureaplasma infections in humans: a paper from the 2011 William Beaumont Hospital Symposium on molecular pathology

Mycoplasma and Ureaplasma species are well-known human pathogens responsible for a broad array of inflammatory conditions involving the respiratory and urogenital tracts of neonates, children, and adults. Greater attention is being given to these organisms in diagnostic microbiology, largely as a result of improved methods for their laboratory detection, made possible by powerful molecular-based techniques that can be used for primary detection in clinical specimens. For slow-growing species, such as Mycoplasma pneumoniae and Mycoplasma genitalium, molecular-based detection is the only practical means for rapid microbiological diagnosis. Most molecular-based methods used for detection and characterization of conventional bacteria have been applied to these organisms. A complete genome sequence is available for one or more strains of all of the important human pathogens in the Mycoplasma and Ureaplasma genera. Information gained from genome analyses and improvements in efficiency of DNA sequencing are expected to significantly advance the field of molecular detection and genotyping during the next few years. This review provides a summary and critical review of methods suitable for detection and characterization of mycoplasmas and ureaplasmas of humans, with emphasis on molecular genotypic techniques.

IL-18R1 and IL-18RAP SNPs may be associated with bronchopulmonary dysplasia in African-American infants

INTRODUCTION

The genetic contribution to the development of bronchopulmonary dysplasia (BPD) in prematurely born infants is substantial, but information related to the specific genes involved is lacking.

RESULTS

Genotype analysis revealed, after multiple comparisons correction, two significant single-nucleotide polymorphism (SNPs), rs3771150 (IL-18RAP) and rs3771171 (IL-18R1), in African Americans (AAs) with BPD (vs. AAs without BPD; q < 0.05). No associations with Caucasian (CA) BPD, AA or CA respiratory distress syndrome (RDS), or prematurity in either AAs or CAs were identified with these SNPs. Respective frequencies were 0.098 and 0.093 in infants without BPD and 0.38 for each SNP in infants with BPD. In the replication set (82 cases; 102 controls), the P values were 0.012 for rs3771150 and 0.07 for rs3771171. Combining P values using Fisher's method, overall P values were 8.31 × 10(-7) for rs3771150 and 6.33 × 10(-6) for rs3771171.

DISCUSSION

We conclude that IL-18RAP and IL-18R1 SNPs identify AA infants at risk for BPD. These genes may contribute to AA BPD pathogenesis via inflammatory-mediated processes and require further study.

METHODS

We conducted a case-control SNP association study of candidate genes (n = 601) or 6,324 SNPs in 1,091 prematurely born infants with gestational age <35 weeks, with or without neonatal lung disease including BPD. BPD was defined as a need for oxygen at 28 days.

NICU admission hypothermia, chorioamnionitis, and cytokines

OBJECTIVE

To determine whether neonatal intensive care unit (NICU) admission hypothermia is associated with an intrauterine inflammatory response.

METHODS

We analyzed a cohort of 309 very low birthweight infants to determine relationships between admission hypothermia, chorioamnionitis, and serum and cerebrospinal fluid (CSF) interleukin (IL)-1β, IL-6, and tumor necrosis factor-α.

RESULTS

Admission hypothermia <36°C occurred in 72% of patients <26 weeks and 44% of patients ≥26 weeks gestational age. NICU admission hypothermia was not associated with histologic chorioamnionitis or with elevated serum cytokine concentrations. CSF IL-6 concentrations ≥6.3 pg/mL were associated with admission hypothermia in infants <26 weeks' gestation. Clinical chorioamnionitis was associated with a lower risk of admission hypothermia, while cesarean section delivery was associated with increased risk.

CONCLUSIONS

NICU admission hypothermia is common among preterm infants and is not associated with the fetal inflammatory response syndrome. Hypothermia is less common in the setting of clinical chorioamnionitis and more common in cesarean section deliveries, identifying two groups in whom extra attention to appropriate thermoregulation is warranted.

Role of TLR signaling in Francisella tularensis-LPS-induced, antibody-mediated protection against Francisella tularensis challenge

Immunization with Ft-LPS provokes an antigen-specific, B-1a cell-derived antibody response that protects WT mice against an otherwise lethal challenge with Ft LVS. However, this same regimen offers limited protection to TLR2(-/-) mice, despite production of WT levels of anti-Ft-LPS antibodies. As Ft-LPS exhibits no TLR2 agonist activity, and macrophage-induced cytokine production in response to Ft LVS is overwhelmingly TLR2-dependent, we hypothesized that treatment of TLR2(-/-) mice with an alternative, MyD88-dependent TLR agonist would compensate for reduced recognition of Ft LVS in TLR2(-/-) mice and thereby, restore Ft-LPS-mediated protection. Administration of the nontoxic TLR4 agonist, synthetic Escherichia coli MPL, at the time of Ft-LPS immunization or Ft LVS challenge, fully protected TLR2(-/-) mice, whereas treatment of WT or TLR2(-/-) mice with MPL alone conferred partial protection. The TLR5 agonist, flagellin, also synergized with Ft-LPS to protect TLR2(-/-) mice from lethal Ft LVS challenge. In contrast to Ft LVS, Ft-LPS pretreatment failed to protect mice against i.n. challenge with Ft Schu S4, whereas MPL, administered in the absence or presence of Ft-LPS, conferred significant, albeit partial, protection. MPL treatment of macrophages increased the uptake of Ft LVS and decreased intracellular bacterial survival while shifting the macrophage-differentiation phenotype from "alternatively activated" to "classically activated". Collectively, our data suggest that optimal, Ft-LPS-mediated protection against Ft LVS infection requires two discrete events, i.e., production of Ft-LPS-specific antibody, as well as TLR-mediated macrophage activation, to fully control Francisella infection.

Pharmacokinetics, safety, and biologic effects of azithromycin in extremely preterm infants at risk for ureaplasma colonization and bronchopulmonary dysplasia

Ureaplasma spp. respiratory tract colonization is a significant risk factor for bronchopulmonary dysplasia (BPD), a chronic lung disorder in preterm infants. As an initial step preparatory to future clinical trials to evaluate the clinical efficacy of azithromycin to prevent BPD, the authors characterized the pharmacokinetics, safety, and biological effects of a single intravenous dose of azithromycin (10 mg/kg) in preterm neonates (n = 12) 24 to 28 weeks gestation at risk for Ureaplasma infection and BPD. A 2-compartment structural model with the clearance and volume of peripheral compartment (V2) allometrically scaled on body weight (WT) best described the pharmacokinetics of azithromycin in preterm neonates. The estimated parameters were clearance [0.18 L/h × WT(kg)(0.75)], intercompartmental clearance [1.0 L/h], volume of distribution of central compartment [0.93 L], and V2 [14.2 L × WT(kg)]. There were no serious adverse events attributed to azithromycin. A single dose of azithromycin did not suppress inflammatory cytokines or myeloperoxidase activity in tracheal aspirates. These results demonstrated the safety of azithromycin and developed a pharmacokinetic model that is useful for future simulation-based clinical trials for eradicating Ureaplasma and preventing BPD in preterm neonates.

Ureaplasma species: role in diseases of prematurity

There is accumulating epidemiologic and experimental evidence that intrauterine or postnatal infection with Ureaplasma species is a significant risk factor for adverse pregnancy outcomes and complications of extreme preterm birth such as bronchopulmonary dysplasia and intraventricular hemorrhage. In a cohort of very low birth weight infants, Ureaplasma spp were detected by culture or polymerase chain reaction in respiratory secretions, blood, or cerebrospinal fluid of almost half of the subjects, suggesting that this organism is the most common pathogen affecting this population. This review summarizes the evidence supporting the hypothesis that Ureaplasma-mediated inflammation in different compartments (intrauterine, lung, blood, or brain) during a common developmental window of vulnerability contributes to preterm labor and lung and brain injury. Appropriate methods for detecting these fastidious organisms and potential strategies to prevent or ameliorate the effects of Ureaplasma infection are discussed.

Surfactant protein-A enhances ureaplasmacidal activity in vitro

BACKGROUND

Persistent respiratory tract colonization with Ureaplasma spp. in preterm infants is a significant risk factor for the development of the chronic lung disorder, bronchopulmonary dysplasia (BPD). Surfactant protein-A (SP-A), a lung collectin critical for bacterial clearance and regulating inflammation, is deficient in the preterm lung. In an experimental Ureaplasma-pneumonia model, infected SP-A deficient mice exhibited delayed bacterial clearance and an exaggerated inflammatory response compared to infected wild-type mice. The objective was to analyze the role of SP-A in Ureaplasma clearance in vitro.

SUBJECTS AND METHODS

We analyzed SP-A binding to Ureaplasma isolates and SP-A-mediated ureaplasmal phagocytosis and killing by cultured RAW 264.7 macrophages.

RESULTS

Calcium-dependent SP-A binding was similar among Ureaplasma isolates tested. Pre-incubation of RAW 264.7 cells with SP-A (10-50 μg/ml) enhanced phagocytosis of fluorescein-isothiocyanate (FITC)-labeled Ureaplasma. Surfactant protein-A also increased ureaplasmacidal activity of RAW 264.7 cells by 2.1-fold over 4 h. Pre-incubation of RAW 264.7 cells with 10 μg/ml SP-A reduced lipopolysaccharide (LPS) (100 ng/ml) and Ureaplasma (10(6) color changing units/ml)-stimulated release of tumor necrosis factor-α (TNF-α) by 46% and 43%, respectively, but did not affect transforming growth factor β(1) (TGFβ(1)) release.

CONCLUSIONS

These in vitro data confirm that SP-A is important in host defense to perinatally-acquired Ureaplasma infection.

Surfactant protein-A limits Ureaplasma-mediated lung inflammation in a murine pneumonia model

Ureaplasma respiratory tract colonization stimulates prolonged, dysregulated inflammation in the lungs of preterm infants, contributing to bronchopulmonary dysplasia (BPD) pathogenesis. Surfactant protein-A (SP-A), a lung collectin critical for bacterial clearance and regulating inflammation, is deficient in the preterm lung. To analyze the role of SP-A in modulating Ureaplasma-mediated lung inflammation, SP-A deficient (SP-A-/-) and WT mice were inoculated intratracheally with a mouse-adapted U. parvum isolate and indices of inflammation were sequentially assessed up to 28 d postinoculation. Compared with infected WT and noninfected controls, Ureaplasma-infected SP-A-/- mice exhibited an exaggerated inflammatory response evidenced by rapid influx of neutrophils and macrophages into the lung, and higher bronchoalveolar lavage TNF-alpha, mouse analogue of human growth-related protein alpha (KC), and monocyte chemotactic factor (MCP-1) concentrations. However, nitrite generation in response to Ureaplasma infection was blunted at 24 h and Ureaplasma clearance was delayed in SP-A-/- mice compared with WT mice. Coadministration of human SP-A with the Ureaplasma inoculum to SP-A-/- mice reduced the inflammatory response, but did not improve the bacterial clearance rate. SP-A deficiency may contribute to the prolonged inflammatory response in the Ureaplasma-infected preterm lung, but other factors may contribute to the impaired Ureaplasma clearance.

Infant neurodevelopment following fetal growth restriction: relationship with antepartum surveillance parameters

OBJECTIVES

To evaluate the relationship between fetal Doppler parameters, biophysical profile score (BPP) and neurodevelopmental delay at 2 years of corrected age in infants who had been growth-restricted in utero.

METHODS

This was a prospective observational study including 113 pregnancies complicated by intrauterine growth restriction (IUGR) (abdominal circumference<5th percentile and elevated umbilical artery (UA) pulsatility index). The relationships of UA, middle cerebral artery and ductus venosus (DV) Doppler features, BPP, birth acidemia (artery pH<7.0+/or base deficit>12), gestational age at delivery, birth weight and neonatal morbidity (i.e. bronchopulmonary dysplasia, >Grade 2 intraventricular hemorrhage, or necrotizing enterocolitis) with a 2-year neurodevelopmental delay were evaluated. Best Beginnings Developmental Screen, Bayley Scale of Infant Development II (BSID) and Clinical Adaptive/Clinical Linguistic Auditory Milestone Stage were used. BSID<70, cerebral palsy, abnormal tone, hearing loss and/or blindness defined neurodevelopmental delay.

RESULTS

Seventy-two of the 113 pregnancies completed assessment; there were 10 stillbirths, 19 neonatal deaths, three infant deaths and nine pregnancies with no follow-up. Twenty fetuses (27.8%) had UA reversed end-diastolic velocity (REDV), 34 (47.2%) abnormal DV Doppler features and 31 (43.1%) an abnormal BPP. Median gestational age at delivery and birth weight were 30.4 weeks and 933 g, respectively. Twelve infants had acidemia and 28 neonatal morbidity. There were 38 (52.8%) infants with neurodevelopmental delay, including 37 (51.4%) with abnormal tone, 20 (27.8%) with speech delay, 23 (31.9%) with an abnormal neurological examination, eight (11.1%) with a hearing deficit and six (8.3%) with cerebral palsy. Gestational age at delivery was associated with cerebral palsy (r2=0.52, P<0.0001; 92% sensitivity and 83% specificity for delivery at <27 weeks). UA-REDV was associated with global delay (r2=0.31, P=0.006) and birth weight with neurodevelopmental delay (r2=0.54, P<0.0001; 82% sensitivity and 64% specificity for BW<922 g).

CONCLUSIONS

Although UA-REDV is an independent contributor to poor neurodevelopment in IUGR no such effect could be demonstrated for abnormal venous Doppler findings or BPP. Gestational age and birth weight remain the predominant factors for poor neurodevelopment in growth-restricted infants.

Antenatal Ureaplasma urealyticum respiratory tract infection stimulates proinflammatory, profibrotic responses in the preterm baboon lung

Chronic inflammation and fibrosis are hallmarks of lung pathology of newborn Ureaplasma infection. We hypothesized that antenatally acquired Ureaplasma stimulates a chronic inflammatory, profibrotic immune response that contributes to lung injury, altered developmental signaling, and fibrosis. Lung specimens from 125-d gestation baboon newborns ventilated for 14 d that were either infected antenatally with Ureaplasma serovar 1 or noninfected, and 125-d and 140-d gestational controls were obtained from the Baboon BPD Resource Center (San Antonio, TX). Trichrome stain to assess fibrosis and immunohistochemistry for alpha-smooth muscle actin (alpha-SMA) and transforming growth factor beta1 (TGFbeta1) were performed. Lung homogenates were analyzed by enzyme-linked immunosorbent assay (ELISA) for cytokines [tumor necrosis factor alpha (TNFalpha), interleukin (IL)-1beta, TGFbeta1, oncostatin M (OSM), IL-10, and interferon gamma (IFNgamma)] and the chemokine MCP-1 and by Western blot for Smad2, Smad3, and Smad7. Compared with noninfected ventilated and gestational controls, Ureaplasma-infected lungs demonstrated more extensive fibrosis, increased alpha-SMA and TGFbeta1 immunostaining, and higher concentrations of active TGFbeta1, IL-1beta, and OSM, but no difference in IL-10 levels. There was a trend toward higher Smad2/Smad7 and Smad3/Smad7 ratios in Ureaplasma lung homogenates, consistent with up-regulation of TGFbeta1 signaling. Collectively, these data suggest that a prolonged proinflammatory response initiated by intrauterine Ureaplasma infection contributes to early fibrosis and altered developmental signaling in the immature lung.

Inflammatory markers in intrauterine and fetal blood and cerebrospinal fluid compartments are associated with adverse pulmonary and neurologic outcomes in preterm infants

Recent evidence strongly implicates the inflammatory response to intrauterine infection in the pathogenesis of neonatal brain and lung injury. We hypothesized that lung and brain injury in preterm infants occurs during a common developmental window of vulnerability as the result of an inflammatory response in different compartments. To determine whether inflammatory markers in these compartments are associated with bronchopulmonary dysplasia (BPD) or cranial ultrasound (CUS) abnormalities in infants <33 wk gestation age (GA) and <1501 g birth weight, we analyzed placental pathology and serum and cerebrospinal fluid (CSF) IL-6, IL-1beta, and tumor necrosis factor-alpha (TNF-alpha) concentrations in 276 infants. Logistic regressions were performed stratified by GA. Histologic chorioamnionitis was significantly associated with BPD in infants </=28 wk GA (OR 3.6, p = 0.027). Maternal stage of chorioamnionitis significantly correlated with severity of BPD. Presence of a fetal inflammatory response indicated by fetal vasculitis or elevated cytokines was not associated with the development of BPD. Serum IL-6 >/=17 pg/mL was associated with an abnormal CUS in infants >28 wk GA (OR 3.36, p = 0.023) but not </=28 wk GA. CSF concentrations of IL-6 >/=6.5 pg/mL and TNF-alpha >/=3 pg/mL were associated with abnormal CUS in infants </=28 wk GA (IL-6 OR 3.0; TNF-alpha OR 3.5; p < 0.05 each case) but not >/=28 wk GA. These data suggest that in infants </=28 wks GA, BPD may be initiated by inflammatory mediators in amniotic fluid, but brain injury may involve variations in the systemic inflammatory response.

Hypothermia prolongs activation of NF-kappaB and augments generation of inflammatory cytokines

While moderate hypothermia is protective against ischemic cardiac and brain injury, it is associated with much higher mortality in patients with sepsis. We previously showed that in vitro exposure to moderate hypothermia (32 degrees C) delays the induction and prolongs the duration of TNF-alpha and IL-1beta secretion by lipopolysaccharide (LPS)-stimulated human mononuclear phagocytes. In the present study, we extended these observations by showing that moderate hypothermia exerts effects on TNF-alpha and IL-1beta generation in the human THP-1 monocyte cell line that are similar to those that we previously found in primary cultured monocytes; that hypothermia causes comparable changes in cytokine generation stimulated by zymosan, toxic shock syndrome toxin-1, and LPS; and that hypothermia causes similar changes in TNF-alpha and IL-1beta mRNA accumulation. TNF-alpha mRNA half-life, determined after transcriptional arrest with actinomycin D, was not significantly prolonged by lowering incubation temperature from 37 to 32 degrees C, suggesting that hypothermia modifies TNF-alpha gene transcription. This finding was further supported by reporter gene studies showing a threefold increase in activity of the human TNF-alpha promoter at 32 vs. 37 degrees C. Electrophoretic mobility shift assay revealed that hypothermia prolonged NF-kappaBeta activation, identifying a potential role for this transcription factor in mediating the effects of hypothermia on TNF-alpha and IL-1beta production. Delayed reexpression of the inhibitor IkappaBalpha, shown by Northern blotting and immunoblotting, may account in part for the prolonged NF-kappaBeta activation at 32 degrees C. Augmentation of NF-kappaBeta-dependent gene expression during prolonged exposure to hypothermia may be a common mechanism leading to increased lethality in sepsis, late-onset systemic inflammatory response syndrome after accidental hypothermia, and neuroprotection after ischemia.

Characterization of a murine model of Ureaplasma urealyticum pneumonia

Ureaplasma urealyticum respiratory tract colonization in preterm infants has been associated with a high incidence of pneumonia and the development of bronchopulmonary dysplasia. However, study of this human pathogen has been hampered by the absence of animal models. We have developed the first juvenile mouse model of Ureaplasma pneumonia and characterized the histopathology during the month following inoculation. C3H/HeN mice were inoculated intratracheally with a mouse-adapted clinical Ureaplasma isolate (biovar 2) or sham inoculated with 10B broth. Culture of lung homogenates and PCR of DNA from bronchoalveolar lavage fluid (BAL) confirmed the presence of Ureaplasma in 100% of inoculated animals at 1 day, 60% at 2 days, 50% at 3 days, and 25% at 7 and 14 days. Ureaplasma was undetectable 28 days postinoculation. There were marked changes in BAL and interstitial-cell composition with increased number of polymorphonuclear leukocytes 1 to 2 days and 14 days postinoculation and macrophages at 2 and 14 days postinoculation. The Ureaplasma infection caused a persistent focal loss of airway ciliated epithelium and a mild increase in interstitial cellularity. There were no differences in BAL protein concentration during the first 28 days, suggesting that pulmonary vascular endothelial barrier integrity remained intact. Comparison of BAL cytokine and chemokine concentrations revealed low levels of tumor necrosis factor alpha (TNF-alpha) at 3 days and monocyte chemoattractant protein 1 at 7 days in Ureaplasma-infected mice but a trend toward increased TNF-alpha at 14 days and increased granulocyte-macrophage colony-stimulating factor and interleukin-10 at 28 days. These data suggest that Ureaplasma alone may cause limited inflammation and minimal tissue injury in the early phase of infection but may promote a mild chronic inflammatory response in the later phase of infection (days 14 to 28), similar to the process that occurs in human newborns.

Discrepancy in pathologic diagnosis of placental lesions

CONTEXT

Placentas are routinely examined by surgical pathologists, but peer review of placental diagnosis is rarely performed.

OBJECTIVE

To determine the frequency of discrepant placental diagnosis between general surgical pathologists and a pediatric pathologist.

DESIGN

One hundred fourteen placentas from infants with intrauterine growth restriction (IUGR) and 170 placentas from infants appropriate for gestational age (AGA) were reviewed for 10 lesion types using standardized criteria. The review diagnosis was compared with original reports.

RESULTS

The review identified 333 lesions, 168 in the IUGR group and 165 in AGA group. Discrepant diagnosis occurred in 137 lesions (41.1%). There was no significant difference in the frequency of discrepant diagnosis between the IUGR (44.7%) and AGA groups (37.6%) (P >.05). Most discrepancies (92.7%) were due to underdiagnosis (identified on review but not mentioned in original diagnosis), but a few (7.3%) were due to misdiagnosis (mentioned in original report but disagreed on review). The common underdiagnoses with their corresponding rates were as follows: hemorrhagic endovasculitis (84.6%), fetal thrombotic vasculopathy (75%), massive perivillous fibrin deposition (68.4%), maternal floor infarction (66.7%), retroplacental hemorrhage (60.6%), intervillous thrombus (57.1%), decidual angiopathy (33.3%), placental infarction (25.4%), acute chorioamnionitis (22.7%), and chronic villitis (21.7%). Misdiagnosis was found in 10 cases: 5 cases of infarction (review diagnosis was perivillous fibrin deposits in 4, intervillous thrombus in 1), 3 cases of acute chorioamnionitis, and 2 cases of decidual angiopathy. Among the 8 general surgical pathologists involved, the frequency of discrepant diagnosis ranged from 31.5% to 58.6% (P >.05). The intraobserver discrepancy rate for the reviewer was 4.8%, significantly lower than the discrepancy rate for the 8 general surgical pathologists.

CONCLUSION

It is common for general surgical pathologists not to recognize placental lesions, which may have clinical significance. Awareness of this deficiency, standardization of diagnostic criteria, and increased knowledge in placental pathology may improve the quality of diagnosis in this area.

Antenatal prediction of intraventricular hemorrhage in fetal growth restriction: what is the role of Doppler?

OBJECTIVE

To evaluate relationships between neonatal intraventricular hemorrhage and altered brain blood flow in preterm growth-restricted fetuses.

METHODS

One hundred and thirteen growth-restricted fetuses (birth weight < 10th centile and umbilical artery pulsatility index > two standard deviations above gestational age mean) which delivered prematurely (< 34.0 weeks) were studied. Three expressions of altered brain blood flow were defined: 'brain sparing'= middle cerebral artery pulsatility index > two standard deviations below the gestational age mean, 'centralization' = ratio of middle cerebral artery/umbilical artery pulsatility indices (cerebroplacental ratio) > two standard deviations below the gestational age mean, and 'redistribution' = absent or reversed umbilical artery end-diastolic velocity. Intraventricular hemorrhage was graded after Papile (I-IV) by cranial ultrasound performed within 7 days of delivery.

RESULTS

Sixty-seven (59.3%) fetuses had brain sparing, 84 (74.3%) had centralization and 51 (45.1%) had redistribution. Fifteen (13.3%) neonates had intraventricular hemorrhage and were more likely to have a biophysical profile < 6, earlier delivery for fetal indications, lower cord artery pH, HCO3, hemoglobin, and platelets, a 10-min Apgar score < 7 and high perinatal mortality (5/15; 33.3%). No associations between intraventricular hemorrhage and brain sparing or centralization were identified. However, neonates with intraventricular hemorrhage had significantly higher umbilical artery pulsatility index deviations from the gestational age mean and a relative risk of 4.9-fold for intraventricular hemorrhage with redistribution (95% confidence interval, 1.5-16.3; P < 0.005). Multiple logistic regression revealed significant associations between intraventricular hemorrhage and a low 10-min Apgar score (r = 0.30, P < 0.005) and low hemoglobin (r = 0.28), gestational age at delivery (r = 0.25) and birth-weight centiles (r = 0.23) (P < 0.05). No Doppler parameter was identified as an independent contributor to intraventricular hemorrhage.

CONCLUSION

While loss of umbilical artery end-diastolic velocity early in gestation significantly increases the risk for neonatal intraventricular hemorrhage, prematurity and difficult transition to extrauterine life remain the most important determinants of intraventricular hemorrhage.

Lung pathology in premature infants with Ureaplasma urealyticum infection

Respiratory tract colonization with Ureaplasma urealyticum in preterm infants has been associated with a higher incidence of pneumonia, severe respiratory failure, bronchopulmonary dysplasia (BPD), and death. In this report, we characterize the lung pathology and expression of tumor necrosis factor-alpha (TNF-alpha) associated with U. urealyticum pneumonia in very low-birth weight infants (VLBW; < or =1500 g). Lung pathology of archived autopsy specimens was retrospectively reviewed in three groups of VLBW infants: 5 gestational controls who died from nonpulmonary causes, 13 infants with pneumonia who were culture and/or PCR negative for U. urealyticum, and 5 infants with pulmonary disease and positive for U. urealyticum by tracheal aspirate and/or lung tissue culture or polymerase chain reaction (PCR). Presence and extent of alveolar macrophages and neutrophils, as well as interstitial lymphocytic infiltration and fibrosis were evaluated. PCR was performed on formalin-fixed, paraffin-embedded lung sections. Additional sections were immunostained for TNF-alpha. The peripheral total white blood cell counts and absolute neutrophil counts were three-fold higher in infants with U. urealyticum pneumonia than cell counts in infants infected with other organisms. There was a trend toward a predominance of neutrophils in alveoli of non- Ureaplasma pneumonia infants, but a trend toward a predominance of alveolar macrophages in U. urealyticum-infected infants. The most striking finding was the presence of increased interstitial fibrosis in all Ureaplasma-infected infants. TNF-alpha immunoreactive cell density was very low in the gestational controls, but increased in both pneumonia groups. We conclude that persistent lung U. urealyticum infection may contribute to chronic inflammation and early fibrosis in the preterm lung.

Ureaplasma urealyticum modulates endotoxin-induced cytokine release by human monocytes derived from preterm and term newborns and adults

We previously observed that Ureaplasma urealyticum respiratory tract colonization in infants with a birth weight of < or =1,250 g was associated with increases in the tracheal aspirate proinflammatory cytokines tumor necrosis factor alpha (TNF-alpha) and interleukin-8 (IL-8) relative to the counterregulatory cytokine IL-6 during the first week of life (A. M. Patterson, V. Taciak, J. Lovchik, R. E. Fox, A. B. Campbell, and R. M. Viscardi, Pediatr. Infect. Dis. J. 17:321-328, 1998). We hypothesized that U. urealyticum alters the host immune response in the presence of a coinflammatory stimulus (e.g., bacterial infection or hyperoxia) by shifting the balance of cytokine expression towards the proinflammatory cytokines. To test this hypothesis, we compared the release of TNF-alpha, IL-8, IL-6, and IL-10 in vitro by unstimulated and U. urealyticum (with or without lipopolysaccharide [LPS])-stimulated human monocytes from adult peripheral blood and from term and preterm cord blood. U. urealyticum alone and in combination with LPS induced concentration- and development-dependent changes in cytokine release. In vitro inoculation with low-inoculum U. urealyticum (10(3) color-changing units [CCU]) (i) partially blocked the LPS-stimulated IL-6 release by all cells and reduced LPS-stimulated IL-10 release by preterm cells, (ii) stimulated TNF-alpha and IL-8 release by preterm cells, and (iii) augmented LPS-stimulated TNF-alpha release in all cells. In preterm cells, high-inoculum U. urealyticum (10(6) CCU) (i) stimulated TNF-alpha and IL-8, but not IL-6 or IL-10, release and (ii) augmented LPS-stimulated TNF-alpha and IL-8 release. High-inoculum U. urealyticum (i) stimulated release of all four cytokines in term cells and IL-8 release in adult cells and (ii) augmented LPS-induced TNF-alpha, IL-10, and IL-8 release in term cells but did not significantly affect LPS-induced cytokine release in adult cells. We speculate that U. urealyticum enhances the proinflammatory response to a second infection by blocking expression of counterregulatory cytokines (IL-6 and IL-10), predisposing the preterm infant to prolonged and dysregulated inflammation, lung injury, and impaired clearance of secondary infections.

Placental lesion multiplicity: risk factor for IUGR and neonatal cranial ultrasound abnormalities

OBJECTIVE

To determine whether placental lesions are risk factors for neurologic morbidities in intrauterine growth restricted (IUGR) infants, we compared the incidence of cranial ultrasound (CUS) abnormalities and the number and type of placental lesions in IUGR cases and gestational age-matched appropriate for gestational age (AGA) controls.

STUDY DESIGN

Retrospective case-control study of 94 singleton IUGR and 145 AGA infants. Medical records, CUS reports, and placental histology were reviewed. Analyses included chi2, t-test, analysis of variance and logistic regressions to identify those variables significantly associated with IUGR and those associated with CUS abnormalities.

RESULTS

The incidence of CUS abnormalities was 1.7-fold higher in IUGR cases (50%) than controls (29.7%) (p<0.05). A total placental lesion score of > or =3 was associated with an increased risk for IUGR (OR 14.18, 3.41-58.99; p<0.001) and increased risk for CUS abnormality (OR 12.571, 3.33-47.416; p<0.05). In a logistic regression model only > or =2 placental lesions, IUGR and gestational age <30 weeks were significant independent predictors of CUS abnormalities.

CONCLUSIONS

The severity of placental abnormalities expressed as the cumulative number of placental lesions is a significant risk factor for IUGR and perinatal brain injury. These results suggest that abnormal uteroplacental or fetoplacental blood flow may adversely affect intrauterine growth and increase the risk for brain injury.

Fetal androgen exposure inhibits fetal rat lung fibroblast lipid uptake and release

Fetal lung fibroblasts provide lipid substrate for type II cell surfactant phospholipid synthesis. This process is developmental and glucocorticoid dependent. Previous studies in our laboratory demonstrating sex differences in several aspects of lung maturation suggest that these differences may be due to effects of fetal androgens. Based on these studies, we hypothesized that fetal lung fibroblast triglyceride metabolism is determined by opposing effects of fetal androgens and glucocorticoids. To model the effects of androgens on fetal lung fibroblast triglyceride metabolism, pregnant rats were treated with dihydrotestosterone (DHT) 1 mg/kg/day from the days 15 to 20 of gestation, and changes in triglyceride content of freshly isolated fetal rat lung fibroblasts (FRLF) and rates of uptake and prostaglandin E2 (PGE2)-mediated release by cultured FRLF in response to glucocorticoids in the presence or absence of DHT in vitro were measured. During lung development, the triglyceride content and rate of uptake of female-derived FRLF increased 3.5- and 4.8-fold, respectively, between days 18 and 20 of gestation. From days 19 to 22, male FRLF trigyclyceride content and rate of uptake were lower than the content and uptake by female FRLF. Maternal DHT treatment inhibited the normal developmental increase in fibroblast triglyceride content and rate of uptake between days 19 and 22 by both male and female FRLF. In the absence of maternal DHT, in vitro dexamethasone stimulated triglyceride uptake 3-fold by day 21 in FRLF. This effect was blocked by maternal pretreatment with DHT. Maternal DHT exposure prevented stimulation of triglyceride release by PGE2. Although in vitro dexamethasone stimulated triglyceride release by maternal DHT-exposed fibroblasts, it did not enhance the response to PGE2. These data suggest that in utero exposure to androgens (1) delay the developmental increase in triglyceride content and (2) oppose the effects of glucocorticoid on cultured FRLF triglyceride uptake and PGE2-mediated release.

Effects of hypothermia and hyperthermia on cytokine production by cultured human mononuclear phagocytes from adults and newborns

We have shown previously that febrile range temperatures modify cytokine production by adult macrophages. In this study, we compared the effects of moderate hyperthermia and hypothermia on the kinetics of lipopolysaccharide (LPS)-induced cytokine expression in monocytes and macrophages of newborns and adults. During culture at 40 degrees C, the initial rates of tumor necrosis factor-alpha (TNF-alpha) and interleukin-1 beta (IL-1 beta) secretion were preserved, but the duration of secretion was shorter than the duration at 37 degrees C. TNF-alpha and IL1-beta concentrations in 24-h 40 degrees C culture supernatants were reduced 18%-50%. IL-6 concentration in 24-h 40 degrees C cultures was reduced 26%-29% in all cells except adult macrophages. At 32 degrees C, changes in early (2 h) and sustained (24 h) cytokine expression were reversed compared with those caused by hyperthermia. Culturing adult macrophages at 32 degrees C blunted early secretion of TNF-alpha and IL-6 by 69% and 65%, respectively, and increased TNF-alpha concentration at 24 h by 48% compared with levels at 37 degrees C. In adult monocytes cultured at 32 degrees C, early IL-6 and IL-1 beta secretion was decreased 64% and 51%, respectively. We speculate that the burst/suppression cytokine profile at febrile temperatures might enhance early activation of host defenses and prevent prolonged exposure to potentially cytotoxic cytokines. Hypothermia, on the other hand, may worsen outcome in infections by delaying and prolonging cytokine production.

Inhibition of tumor necrosis factor-alpha transcription in macrophages exposed to febrile range temperature. A possible role for heat shock factor-1 as a negative transcriptional regulator

We previously reported that expression of tumor necrosis factor-alpha (TNFalpha) was attenuated in macrophages exposed to febrile range temperatures. In this study, we analyzed the influence of temperature on TNFalpha transcription in the Raw 264.7 macrophage cell line during incubation at 37 and 39.5 degrees C. The initial activation of TNFalpha transcription in response to endotoxin (LPS) was comparable in the 37 and 39.5 degrees C cell cultures, peaking within 10 min of LPS stimulation. However, the duration of transcriptional activation was markedly reduced in the 39.5 degrees C cells (30-60 min) compared with the 37 degrees C cells (2-4 h). Deletion mapping of the TNFalpha gene revealed that the proximal 85-nucleotide promoter sequence and the 5'-untranslated region were sufficient for temperature sensitivity. This sequence contains six heat shock response element (HRE) half-sites but no complete HREs. Electrophoretic mobility shift and immunoblot assays demonstrated that nuclear transclocation of heat shock factor (HSF) and its activation to a DNA-binding form occurred in the 39.5 degrees C cells in the absence of heat shock protein-70 gene activation. The proximal TNFalpha promoter/5'-untranslated region sequence competed for HSF binding to a classic HRE. Overexpression of HSF-1 reduced activity of the TNFalpha promoter. These data suggest that partial activation of HSF-1 during exposure to febrile, sub-heat shock temperatures may block TNFalpha transcription by binding to its proximal promoter or 5'-untranslated region.

Febrile core temperature is essential for optimal host defense in bacterial peritonitis

Fever, a nonspecific acute-phase response, has been associated with improved survival and shortened disease duration in infections, but the mechanisms of these beneficial responses are poorly understood. We previously reported that increasing core temperature of bacterial endotoxin (LPS)-challenged mice to the normal febrile range modified expression of tumor necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), and IL-6, three cytokines critical to mounting an initial defense against microbial pathogens, but survival was not improved in the warmer animals. We speculated that our inability to show a survival benefit of optimized cytokine expression in the warmer animals reflected our use of LPS, a nonreplicating agonist, rather than an infection with viable pathogens. The objective of this study was to determine if increasing murine core temperature altered cytokine expression and improved survival in an experimental bacterial peritonitis model. We showed that housing mice at 35.5 degrees C rather than 23 degrees C increased core temperature from 36.5 to 37.5 degrees C to 39.2 to 39.7 degrees C, suppressed plasma TNF-alpha expression for the initial 48 h, delayed gamma interferon expression, improved survival, and reduced the bacterial load in mice infected with Klebsiella pneumoniae peritonitis. We showed that the reduced bacterial load was not caused by a direct effect on bacterial proliferation and probably reflected enhanced host defense. These data suggest that the increase in core temperature that occurs during bacterial infections is essential for optimal antimicrobial host defense.

Developmental changes in phosphatidylinositol transfer protein concentration and phospholipid transfer activities in rat type II cells

The phospholipid transfer proteins (PLTPs) are cytosolic proteins that have been characterized by their ability to facilitate the transfer of phospholipids between membranes in vitro. The goals of this study were to determine whether PITP alpha concentration and phospholipid transfer activities are enriched in type II cells compared with whole lung and to determine the developmental changes in PITP alpha concentration and phospholipid transfer activities during late gestation and newborn period. The concentration of PITP alpha in type II cell cytosol measured by enzyme-linked immunosorbent assay (ELISA) increased during late fetal gestation to 2.2-fold adult levels and declined 41% during the first postnatal day. However, compared to whole adult lung cytosol, type II cell cytosol was not significantly enriched with PITP alpha. Phospholipid transfer activities were determined by a vesicle-rat lung membrane transfer assay. In adult lung, transfer activities for all the phospholipids were enriched in adult type II cell cytosol compared to whole lung cytosol (phosphatidylglycerol [PG], 12.5-fold; phosphatidylinositol [PI], 9.2-fold; phosphatidylcholine [PC], 6.5-fold; and phosphatidylethanolamine [PE], 6.6-fold; P < .05 in each case). The rate of phospholipid transfer in type II cell cytosol increased during late fetal gestation to levels 4.9 (PG), 3.7 (PI), and 2.8 (PC) times greater than adult levels. In cytosol from cells from different stages, the order of transfer rate was PG > PI > PC > PE. PITP alpha immunodepletion of adult type II cytosol did not significantly affect phospholipid transfer activities, suggesting that other PLTPs are responsible for the majority of the observed transfer activities in these cells. Developmental increases in PITP alpha concentration and other PLTPs parallel developmental changes in type II cell surfactant phospholipid metabolism, suggesting a possible role of these transfer proteins in the unique function of the type II cell.

Ureaplasma urealyticum respiratory tract colonization is associated with an increase in interleukin 1-beta and tumor necrosis factor alpha relative to interleukin 6 in tracheal aspirates of preterm infants

OBJECTIVE

To determine whether Ureaplasma urealyticum respiratory tract colonization in very low birth weight infants during the first week of life is associated with changes in tracheal aspirate concentrations of the cytokines interleukin 1-beta (IL-1-beta), tumor necrosis factor alpha (TNF-alpha) and IL-6.

METHODS

Infants with birth weights < or =1250 g were prospectively enrolled. Samples were obtained from the endotracheal tube or nasopharynx on Day 1 and again between Days 7 and 10 for U. urealyticum culture. The concentrations of IL-1-beta, TNF-alpha and IL-6 were measured in tracheal aspirate samples by enzyme-linked immunosorbent assay.

RESULTS

There were 18 positive cultures for U. urealyticum from 15 of 96 infants (15.6%). IL-1-beta in tracheal aspirates expressed as concentration per volume or as a ratio of IL-1-beta to IL-6 were 7- and 14.9-fold higher, respectively, in Ureaplasma-positive infants than in Ureaplasma-negative infants (P < 0.05). The TNF-alpha/IL-6 ratio was 18.9 and 15.5 times higher in the Ureaplasma-positive aspirates than in the Ure aplasma-negative aspirates on Day 1 and Days 7 to 10 (P < 0.05). Concentrations of IL-1-beta and TNF-alpha were significantly correlated on Day 1 and Days 7 to 10. Although there was no clinical association demonstrated between U. urealyticum colonization and the development of bronchopulmonary dysplasia (BPD) in this study, infants who developed BPD had significantly higher IL-1-beta concentrations and ratios of IL-1-beta to IL-6 in Day 1 aspirates than infants who did not develop BPD. Conclusions. Isolation of U. urealyticum from the respiratory tract is associated with increased IL-1-beta concentrations and IL-1-beta-IL-6 ratios on Day 1 and increased TNF-alpha-IL-6 ratios on Days 1 and 7 to 10 in tracheal aspirates of colonized infants. Infants who developed BPD had higher IL-1-beta concentrations and IL-1-beta-IL-6 ratios, suggesting that these may be early markers of lung inflammation.

Parent perceptions of an NICU follow-up clinic

PURPOSE

To learn how parents perceived their experiences during a visit to an academic center's NICU follow-up clinic and what they would change about the clinic if given the opportunity.

DESIGN

A qualitative study utilizing artifact collection, participant observation, and semistructured interviews.

SAMPLE

Seven families that went to the clinic.

MAIN OUTCOME VARIABLE

What parents did and did not like about the clinic and what they would change about the clinic.

RESULTS

Parent concerns included lack of information about the clinic prior to the first appointment, length of wait prior to seeing the physician, preference for more appropriate toys for use during the wait, desire for additional explanations during the exam process, uncertainty about the effects of prematurity on their child's development, and need for more developmental and parenting information.

Oleic acid stimulates rapid translocation of cholinephosphate cytidylyltransferase in type II cells

Activity of cholinephosphate cytidylyltransferase, the rate-limiting enzyme in phosphatidylcholine synthesis, increases rapidly in the lung after birth predominantly due to an increase in membrane-associated activity. Although there is strong evidence that enzyme translocation is a major regulatory mechanism in other cells, this mechanism has not been conclusively demonstrated in intact alveolar type II cells. In this study, we show that oleic acid stimulates rapid translocation of cytidylyltransferase activity and protein from cytosol to microsomes in both primary cultured fetal and adult type II cells and MLE12 cells, a cell line derived from murine distal respiratory epithelial cells. Shifts in subcellular distribution occurred within 5 min of exposure to 200 microM oleic acid. The magnitude of the increases in microsomal enzyme activity and immunoreactive protein levels was several-fold greater in d21 fetal cells than adult type II cells. Oleic acid-induced translocation was confirmed in in vitro translocation experiments. After incubating MLE12 cell postmitochondrial supernatants at 37 degrees C with oleic acid and separation of enzyme isoforms on glycerol density gradients, enzyme activity was decreased in gradient fractions corresponding to both cytosolic isoforms and microsomal activity increased 7.9-fold compared to the distribution of enzyme activity in postmitochondrial supernatants incubated at 4 degrees C without oleic acid. The increase in microsomal activity was associated with an increased incorporation of [14C]oleic acid in the membrane free fatty acid fraction. Developmental changes in type II cell membrane lipid composition may induce the rapid translocation/activation of cytidylyltransferase in the lung after birth.

Cromolyn sodium prophylaxis inhibits pulmonary proinflammatory cytokines in infants at high risk for bronchopulmonary dysplasia

An imbalance of proinflammatory cytokines such as TNF-alpha, IL-1 beta, and the neutrophil chemotactic factor IL-8 and inhibitors (e.g., soluble TNF receptors and IL-1ra) in the lung during the first week of life may contribute to prolonged pulmonary inflammation and fibrosis in bronchopulmonary dysplasia (BPD). Disodium cromoglycate (DSCG) has anti-inflammatory effects in asthma, a disease with many similarities with BPD. In a prospective, randomized, blinded study, we examined whether early DSCG therapy inhibits proinflammatory cytokines in infants at risk for BPD. Twenty-six infants who were identified as high risk (> or = 75% probability) for oxygen-dependency at 28 d by a 12-h predictive score and survived 48 h were randomized to nebulized DSCG 20 mg (n = 13) or 2 cc NS (control, n = 13) every 6 h from Day 3 to Day 28. Lung lavage was collected on Day 3 (pre-study) and Day 7 and analyzed for cell count and differential and TNF-alpha, sTNFR1, sTNFR2, IL-1 beta, IL-1ra, and IL-8 concentrations. The groups' pre-study lavage cytokine concentrations were similar, but TNF-alpha and IL-8 concentrations were 3.6- and 4.9-fold lower in the DSCG group on Day 7 compared with levels in the control group. Soluble TNF receptors were unaffected by DSCG. There was a trend towards lower IL-1 beta levels in DSCG-treated infants on Day 7, but IL-1ra levels were unaffected by DSCG therapy. Three control subjects, but no DSCG-treated infants, died during the study period (p = 0.07). There were no significant differences between survivors of the two groups for oxygen-dependency at 28 d (100% control subjects; 85% DSCG). These results suggest that nebulized DSCG may exert an anti-inflammatory effect in the lungs of infants < or = 1,000 g at risk for BPD.

Inflammatory cytokine mRNAs in surgical specimens of necrotizing enterocolitis and normal newborn intestine

Coagulation necrosis, inflammation, and hemorrhage are pathologic hallmarks of necrotizing enterocolitis (NEC). Because cytokines are peptides that mediate inflammatory cell recruitment and amplify the immune response, several of the inflammatory cytokines have been implicated in NEC. We hypothesized that mRNA levels for the interrelated cytokines interleukin-1 beta (IL-1 beta), tumor necrosis factor-alpha (TNF-alpha), IL-6, and the neutrophil chemotactic factor IL-8 would be increased in NEC and would be associated with the presence of inflammation. In this study, we determined the relative levels and localization of mRNA for these cytokines in surgical pathology archival intestinal tissue from 29 premature infants with acute NEC and 15 control infants with congenital intestinal malformations using a novel quantitative in situ hybridization technique. Compared with controls, there were higher IL-1 beta mRNA levels in full-thickness sections and higher TNF-alpha mRNA levels in full-thickness and mucosa sections of acute NEC samples, suggesting a potential role for these cytokines in the pathogenesis of local inflammation in NEC. IL-6 and IL-8 mRNA levels were similar in samples of control and acute NEC cases. Analysis of covariance including all subjects showed that the presence of acute inflammation was associated with increased IL-1 beta mRNA levels in mucosa (P = .035) and increased IL-8 in full-thickness sections (P = .005) and mucosa (P = .01). In four of five NEC cases in which intestinal specimens were available from reanastomosis surgery, cytokine mRNA levels decreased to low or undetectable levels. These data suggest that the inflammatory cytokines are involved in neutrophil recruitment and augmentation of the inflammatory response in neonatal intestine.

Potential role of interleukin-1 in the development of bronchopulmonary dysplasia

Increased activities of inflammatory mediators unopposed by their inhibitors contribute to chronic lung injury and impaired healing in BPD. The deleterious effects of IL-1 beta, a cytokine involved in inflammation and host defense, are blocked by IL-1 receptor antagonist (IL-1Ra). We proposed that an imbalance of IL-1 beta and its inhibitors may contribute to the development of BPD. To determine the relative antigen concentrations of IL-1 beta and IL-1Ra and functional IL-1 activity in lung lavage of infants at risk for BPD, lung lavage was serially obtained from 1 to 28 days from 17 infants with evolving BPD, 13 infants with self-limited RDS, and 6 controls ventilated for nonpulmonary reasons. Overall, there was a high correlation between IL-1 beta antigen concentration and IL-1 activity (r = 0.82, p = 0.0001). There were no significant differences among the groups for lung lavage variables on day 1. However, in infants who developed BPD, IL-1 beta antigen concentration and IL-1 activity increased 16- and 61-fold, respectively, during the first week. IL-1Ra remained relatively unchanged during the first month. IL-1 beta/IL-1Ra antigen ratio was significantly higher on days 5 (median 0.024) and 7 (median 0.025) compared with day 1 (median 0.004), p < 0.05. These results suggest that a relative imbalance of IL-1 beta and IL-1Ra may contribute to prolonged inflammation in BPD.

Role of fatty acids in lung development

The role of maternal dietary fat in the regulation of fetal and newborn lung surfactant lipid synthesis has not been completely elucidated. Dietary fat can modulate cell membrane phospholipid fatty acid composition, resulting in altered membrane fluidity and affecting cellular functions, including binding to hormone receptors and the binding and activity of membrane-associated enzymes. Two examples are discussed that support the hypothesis that exogenous fatty acids modulate phospholipid synthesis in the lung. In the first example, long-chain unsaturated fatty acids were found to inhibit glucocorticoid receptor binding in L2 cells, suggesting that fatty acids may affect steroid responsiveness during different developmental stages of the lung. In the second example, a relationship was established between changes in membrane lipid composition during lung development and the activity of cholinephosphate cytidylyltransferase, the rate-limiting enzyme in phosphatidylcholine synthesis. The effects demonstrated in these in vitro studies will need to be confirmed by dietary studies of pregnant animals.

Increased activity of interleukin-6 but not tumor necrosis factor-alpha in lung lavage of premature infants is associated with the development of bronchopulmonary dysplasia

Although considerable evidence suggests that bronchopulmonary dysplasia (BPD) is the result of prolonged inflammation and impaired healing of the immature lung, the mediators that regulate inflammation in neonatal lung injury have not been completely elucidated. We examined whether the cytokines IL-6 and tumor necrosis factor-alpha (TNF) interact to modulate a cascade of cell-cell signaling events involved in inflammation contributing to the development of BPD. To determine the relative activities of these cytokines in neonatal lung injury, lung lavage samples were serially obtained from 1 to 28 d from 11 infants with self-limited respiratory distress syndrome (RDS), 19 infants with evolving BPD, and 10 control infants ventilated for nonpulmonary reasons. On the first day of life, there were no differences in antigenic IL-6 concentrations in lavage fluids among the BPD, RDS, and control groups, but IL-6 activity determined by the 7TD1 proliferation assay was 15-fold and 6.6-fold higher in lung lavage of infants who developed BPD compared with activities in lavage from control and RDS infants, respectively (control, 49.4 +/- 17.6; RDS, 117.3 +/- 59.6; BPD, 779.5 +/- 212.6 x 10(3) hybridoma units/L, mean +/- SEM, p = 0.02). This suggests that pathways for inactivating or inhibiting IL-6 that may be present in the lungs of RDS and control infants may be deficient in BPD infants. IL-6 activity remained elevated in lavage of BPD infants for the first 2 wk and declined to low levels by d 28.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential effects of hyperthermia on macrophage interleukin-6 and tumor necrosis factor-alpha expression

The pyrogenic cytokines tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) appear in the circulation during infections and injuries, but TNF-alpha and IL-6 are regulated differently in macrophages. We compared the effects of elevated temperatures within the usual febrile range on the expression of TNF-alpha and IL-6 in vitro in lipopolysaccharide (LPS)-stimulated human macrophages derived from peripheral blood monocytes (HuMoM phi). During an 18-h incubation at 37 degrees C with 5 ng/ml LPS, these cells released 5,030 +/- 1,460 pg TNF-alpha/10(6) cells (means +/- SE) and 1,380 +/- 280 pg IL-6/10(6) cells. In LPS-stimulated HuMoM phi incubated at 40 degrees C, TNF-alpha release was almost completely inhibited (76 +/- 76 pg TNF-alpha/10(6) cells; P < 0.01 compared with LPS-stimulated HuMoM phi at 37 degrees C), but release of IL-6 was preserved (1,600 +/- 780 pg IL-6/10(6) cells). Western and Northern analyses showed that levels of TNF-alpha mRNA and cell-associated and secreted TNF-alpha protein were decreased, but IL-6 expression was unchanged at 40 degrees C in LPS-stimulated macrophages. Incubating HuMoM phi at 40 degrees did not alter their viability after 18 h but induced a 75-fold increase in levels of the inducible heat-shock protein 72 (HSP-72) mRNA in the face of a 56% inhibition in total protein synthesis. Our results show that IL-6 expression persisted at incubation temperatures in the upper end of the physiological range that induced heat shock and attenuated the expression of functionally active TNF-alpha in LPS-stimulated HuMoM phi.