Undetectable interleukin (IL)-10 and persistent IL-8 expression early in hyaline membrane disease: a possible developmental basis for the predisposition to chronic lung inflammation in preterm newborns

Structural basis of CXC chemokine receptor 1 ligand binding and activation

Neutrophil granulocytes play key roles in innate immunity and shaping adaptive immune responses. They are attracted by chemokines to sites of infection and tissue damage, where they kill and phagocytose bacteria. The chemokine CXCL8 (also known as interleukin-8, abbreviated IL-8) and its G-protein-coupled receptors CXCR1 and CXCR2 are crucial elements in this process, and also the development of many cancers. These GPCRs have therefore been the target of many drug development campaigns and structural studies. Here, we solve the structure of CXCR1 complexed with CXCL8 and cognate G-proteins using cryo-EM, showing the detailed interactions between the receptor, the chemokine and Gαi protein. Unlike the closely related CXCR2, CXCR1 strongly prefers to bind CXCL8 in its monomeric form. The model shows that steric clashes would form between dimeric CXCL8 and extracellular loop 2 (ECL2) of CXCR1. Consistently, transplanting ECL2 of CXCR2 onto CXCR1 abolishes the selectivity for the monomeric chemokine. Our model and functional analysis of various CXCR1 mutants will assist efforts in structure-based drug design targeting specific CXC chemokine receptor subtypes.

The fetal response to maternal inflammation is dependent upon maternal IL-6 in a murine model

BACKGROUND

The induction of maternal inflammation in mice leads to fetal injury that is believed to be IL-6 dependent. The fetal inflammatory response, defined by elevated fetal or amniotic fluid IL-6, has been described as a potential mechanism for subsequent fetal injury. The role of maternal IL-6 production and signaling in the fetal IL-6 response is currently unclear.

METHODS

Genetic and anti-IL-6 antibody strategies were used to systematically block the maternal IL-6 response during inflammation. Chorioamnionitis was induced using intraperitoneal injection of lipopolysaccharide (LPS) at mid gestation (E14.5) and late gestation (E18.5). This model was used in pregnant C57Bl/6 dams, IL6^-/- dams, C57Bl/6 dams treated with anti-IL-6 (blocks both classical and trans-signaling) or anti-gp130 antibodies (blocks trans-signaling only) and IL6^+/- dams. Six hours following LPS injection, maternal serum, placental tissue, amniotic fluid and fetal tissue or serum were collected. A bead-based multiplex assay was used to evaluate levels of IL-6, KC, IL-1β, TNF, IL-10, IL-22, IFN-γ, IL-13 and IL-17A.

RESULTS

Chorioamnionitis in C57Bl/6 dams was characterized by elevated maternal serum levels of IL-6, KC and IL-22 with litter loss during mid gestation. The fetal response to maternal inflammation in C57Bl/6 mice was primarily characterized by elevated levels of IL-6, KC and IL-22 in the placenta, amniotic fluid and fetus during both mid and late gestation. A global IL-6 knockout (IL6^-/-) eradicated the maternal, placental, amniotic fluid and fetal IL-6 response to LPS during mid and late gestation and improved litter survival, while minimally influencing the KC or IL-22 responses. Blocking maternal classical IL-6 signaling in C57Bl/6 dams at the time of LPS exposure diminished the maternal, placental, amniotic fluid and fetal IL-6 response during mid and late gestation, while blocking maternal IL-6 trans-signaling only affected fetal IL-6 expression. To evaluate whether maternal IL-6 was crossing the placenta and reaching the fetus, IL-6^+/- dams were utilized in the chorioamnionitis model. IL-6^+/- dams mounted a systemic inflammatory response following injection with LPS, characterized by elevated IL-6, KC and IL-22. IL-6^-/- pups born to IL6^+/- dams had decreased amniotic fluid levels of IL-6 and undetectable levels of fetal IL-6 compared to IL-6^+/+ littermate controls.

CONCLUSION

The fetal response to systemic maternal inflammation is dependent upon maternal IL-6 signaling, but maternal IL-6 is not crossing the placenta and reaching the fetus at detectable levels.

Imbalanced Inflammatory Responses in Preterm and Term Cord Blood Monocytes and Expansion of the CD14+CD16+ Subset upon Toll-like Receptor Stimulation

Developmentally regulated features of innate immunity are thought to place preterm and term infants at risk of infection and inflammation-related morbidity. Underlying mechanisms are incompletely understood. Differences in monocyte function including toll-like receptor (TLR) expression and signaling have been discussed. Some studies point to generally impaired TLR signaling, others to differences in individual pathways. In the present study, we assessed mRNA and protein expression of pro- and anti-inflammatory cytokines in preterm and term cord blood (CB) monocytes compared with adult controls stimulated ex vivo with Pam3CSK4, zymosan, polyinosinic:polycytidylic acid, lipopolysaccharide, flagellin, and CpG oligonucleotide, which activate the TLR1/2, TLR2/6, TLR3, TLR4, TLR5, and TLR9 pathways, respectively. In parallel, frequencies of monocyte subsets, stimulus-driven TLR expression, and phosphorylation of TLR-associated signaling molecules were analyzed. Independent of stimulus, pro-inflammatory responses of term CB monocytes equaled adult controls. The same held true for preterm CB monocytes-except for lower IL-1β levels. In contrast, CB monocytes released lower amounts of anti-inflammatory IL-10 and IL-1ra, resulting in higher ratios of pro-inflammatory to anti-inflammatory cytokines. Phosphorylation of p65, p38, and ERK1/2 correlated with adult controls. However, stimulated CB samples stood out with higher frequencies of intermediate monocytes (CD14⁺CD16⁺). Both pro-inflammatory net effect and expansion of the intermediate subset were most pronounced upon stimulation with Pam3CSK4 (TLR1/2), zymosan (TR2/6), and lipopolysaccharide (TLR4). Our data demonstrate robust pro-inflammatory and yet attenuated anti-inflammatory responses in preterm and term CB monocytes, along with imbalanced cytokine ratios. Intermediate monocytes, a subset ascribed pro-inflammatory features, might participate in this inflammatory state.

The Patent Ductus Arteriosus in Extremely Preterm Neonates Is More than a Hemodynamic Challenge: New Molecular Insights

Complications to preterm birth are numerous, including the presence of a patent ductus arteriosus (PDA). The biological understanding of the PDA is sparse and treatment remains controversial. Herein, we speculate whether the PDA is more than a cardiovascular imbalance, and may be a marker in response to immature core molecular and physiological processes driven by biological systems, such as inflammation. To achieve a new biological understanding of the PDA, we performed echocardiography and collected plasma samples on day 3 of life in 53 consecutively born neonates with a gestational age at birth below 28 completed weeks. The proteome of these samples was analyzed by mass spectrometry (nanoLC-MS/MS) and immunoassay of 17 cytokines and chemokines. We found differences in 21 proteins and 8 cytokines between neonates with a large PDA (>1.5 mm) compared to neonates without a PDA. Amongst others, we found increased levels of angiotensinogen, periostin, pro-inflammatory associations, including interleukin (IL)-1β and IL-8, and anti-inflammatory associations, including IL-1RA and IL-10. Levels of complement factors C8 and carboxypeptidases were decreased. Our findings associate the PDA with the renin-angiotensin-aldosterone system and immune- and complement systems, indicating that PDA goes beyond the persistence of a fetal circulatory connection of the great vessels.

Noninfectious influencers of early-onset sepsis biomarkers

Diagnostic tests for sepsis aim to either detect the infectious agent (such as microbiological cultures) or detect host markers that commonly change in response to an infection (such as C-reactive protein). The latter category of tests has advantages compared to culture-based methods, including a quick turnaround time and in some cases lower requirements for blood samples. They also provide information on the immune response of the host, a critical determinant of clinical outcome. However, they do not always differentiate nonspecific host inflammation from true infection and can inadvertently lead to antibiotic overuse. Multiple noninfectious conditions unique to neonates in the first days after birth can lead to inflammatory marker profiles that mimic those seen among infected infants. Our goal was to review noninfectious conditions and patient characteristics that alter host inflammatory markers commonly used for the diagnosis of early-onset sepsis. Recognizing these conditions can focus the use of biomarkers on patients most likely to benefit while avoiding scenarios that promote false positives. We highlight approaches that may improve biomarker performance and emphasize the need to use patient outcomes, in addition to conventional diagnostic performance analysis, to establish clinical utility.

Group B streptococci infection model shows decreased regulatory capacity of cord blood cells

BACKGROUND

Sepsis is one of the leading causes of morbidity and mortality in the neonatal period. Compared to adults, neonates are more susceptible to infections, especially to systemic infections with Group B Streptococcus (GBS). Furthermore, neonates show defects in terminating inflammation. The immunological causes for the increased susceptibility to infection and the prolonged inflammatory response are still incompletely understood.

METHODS

In the present study, we aimed to investigate the reaction of cord blood mononuclear cells (MNC) to stimulation with GBS in comparison to that of MNC from adult blood with focus on the proliferative response in an in vitro infection model with heat-inactivated GBS.

RESULTS

We demonstrate that after stimulation with GBS the proliferation of T cells from adult blood strongly decreased, while the proliferation of cord blood T cells remained unchanged. This effect could be traced back to a transformation of adult monocytes, but not cord blood monocytes, to a suppressive phenotype with increased expression of the co-inhibitory molecule programmed death ligand 1 (PD-L1).

CONCLUSIONS

These results point towards an increased inflammatory capacity of neonatal MNC after stimulation with GBS. Targeting the prolonged inflammatory response of neonatal immune cells may be a strategy to prevent complications of neonatal infections.

IMPACT

Neonatal sepsis often leads to post-inflammatory complications. Causes for sustained inflammation in neonates are incompletely understood. We show that cord blood T cells exhibited increased proliferative capacity after stimulation with group B streptococci (GBS) in comparison to adult T cells. Adult monocytes but not cord blood monocytes acquired suppressive activity and expressed increased levels of PD-L1 after GBS stimulation. Increased proliferative capacity of neonatal T cells and decreased suppressive activity of neonatal monocytes during GBS infection may contribute to prolonged inflammation and development of post-inflammatory diseases in newborns.

Exploring the Potential Mechanism of Chuanxiong Rhizoma Treatment for Migraine Based on Systems Pharmacology

Migraine is a disease whose aetiology and mechanism are not yet clear. Chuanxiong Rhizoma (CR) is employed in traditional Chinese medicine (TCM) to treat various disorders. CR is effective for migraine, but its active compounds, drug targets, and exact molecular mechanism remain unclear. In this study, we used the method of systems pharmacology to address the above issues. We first established the drug-compound-target-disease (D-C-T-D) network and protein-protein interaction (PPI) network related to the treatment of migraine with CR and then established gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. The results suggest that the treatment process may be related to the regulation of inflammation and neural activity. The docking results also revealed that PTGS2 and TRPV1 could directly bind to the active compounds that could regulate them. In addition, we found that CR affected 11 targets that were more highly expressed in the liver or heart but were the lowest in the whole brain. It also expounds the description of CR channel tropism in TCM theory from these angles. These findings not only indicate that CR can be developed as a potential effective drug for the treatment of migraine but also demonstrate the application of systems pharmacology in the discovery of herbal-based disease therapies.

Chronic Inflammatory Placental Lesions Correlate With Bronchopulmonary Dysplasia Severity in Extremely Preterm Infants

OBJECTIVE

Correlation of BPD with placental pathology is important for clarification of the multifactorial pathogenesis of BPD; however, previous reports have yielded varying results. We report placental findings in no/mild BPD compared to moderate/severe BPD, and with and without pulmonary hypertension (PH).

METHODS

Eligible infants were 23^0/7-27^6/7 weeks gestational age. BPD was defined by the need for oxygen at ≥28 days with severity based on need for respiratory support at ≥36 weeks. Acute and chronic inflammatory placental lesions and lesions of maternal and fetal vascular malperfusion were examined.

RESULTS

Of 246 eligible infants, 146 (59%) developed moderate/severe BPD. Thirty-four (23%) infants developed PH, all but 1 being in the moderate/severe BPD group. Chronic deciduitis (32% vs 16%, P = .003), chronic chorioamnionitis (23% vs 12%, P = .014), and ≥ 2 chronic inflammatory lesions (13% vs 3%, P = .007) were more frequent in the moderate/severe BPD group. Development of PH was associated with placental villous lesions of maternal vascular malperfusion (30% vs 15%, P = .047).

CONCLUSIONS

The association of chronic inflammatory placental lesions with BPD severity has not been previously reported. This supports the injury responsible for BPD as beginning before birth in some neonates, possibly related to cytokines associated with these chronic inflammatory lesions.

Perinatal inflammation relates to early respiratory morbidity and lung function at 12 years of age in children born very preterm

AIM

Very preterm birth may be associated with lung function impairment later in life. It is not known if this is caused by prematurity per se or by associated perinatal events, such as maternal-foetal inflammation and severity of early neonatal lung disease. We assessed these factors in a prospective cohort of very preterm infants followed from birth to middle school age.

METHODS

In 71 infants with a gestational age of median 27.4 (range 23.9-31.7) weeks, pro-inflammatory and modulatory cytokines were measured in umbilical cord blood and in arterial blood sampled at 6, 24 and 72 h after birth, and cumulated cytokine concentrations were calculated as area under the curve (AUC). At median 12.6 (range 12.3-13.5) years of age, pulmonary function testing was done in 53 children.

RESULTS

There was a positive correlation between days on mechanical ventilation and AUC for IL-6 (p = 0.001), IL-8 (p = 0.015) and IL-10 (p = 0.006). Infants with bronchopulmonary dysplasia (BPD; n = 32) had higher AUC for the cytokines IL-6, IL-8 and IL-10 than those without BPD (all p < 0.01). Higher levels of AUC for IL-6 at birth correlated with lower forced expiratory volume in 1 s (p = 0.030) and lower mean expiratory flow rate between 25 and 75% of forced vital capacity (p = 0.034).

CONCLUSION

Perinatal inflammation, assessed by circulating cytokines in the first three days of life, was associated with BPD and with airway obstruction at 12 years of age.

Novel biomarkers of bronchopulmonary dysplasia and bronchopulmonary dysplasia-associated pulmonary hypertension

OBJECTIVE

To quantify and compare levels of potential biomarkers in neonates with (i) Bronchopulmonary dysplasia (BPD); (ii) BPD-associated pulmonary hypertension (BPD-PH); (iii) PH without BPD; and (iv) neonates without lung disease at ~36 weeks postmenstrual age.

STUDY DESIGN

Multiple potential biomarkers were measured in plasma samples of 90 patients using a multi-spot enzyme-linked immunosorbent assay. Statistical tests done included one-way ANOVA to compare levels of biomarkers between different groups.

RESULTS

Higher levels of ICAM-1 were present in infants with BPD and correlated with its severity. Infants with BPD have significantly higher levels of ANG-2 and lower levels of ANG-1. Infants with PH have higher levels of: IL-6, IL-8, IL-10, and TNF-α. Infants with BPD-PH have significantly lower levels of MCP-1 and higher levels of IL-1β than infants with PH without BPD.

CONCLUSION

ICAM-1 may be used as a specific biomarker for diagnosis of BPD and its severity.

Preterm birth: Born too soon for the developing airway epithelium?

Birth prior to term interrupts the normal development of the respiratory system and consequently results in poor respiratory outcomes that persist throughout childhood. The mechanisms underpinning these poor respiratory outcomes are not well understood, but intrinsic abnormalities within the airway epithelium may be a contributing factor. Current evidence suggests that the airway epithelium is both structurally and functionally abnormal after preterm birth, with reports of epithelial thickening and goblet cell hyperplasia in addition to increased inflammation and apoptosis in the neonatal intensive care unit. However, studies focusing on the airway epithelium are limited and many questions remain unanswered; including whether abnormalities are a direct result of interrupted development, a consequence of exposure to inflammatory stimuli in the perinatal period or a combination of the two. In addition, the difficulty of accessing airway tissue has resulted in the majority of evidence being collected in the pre-surfactant era which may not reflect contemporary preterm birth. This review examines the consequences of preterm birth on the airway epithelium and explores the clinical relevance of currently available models whilst highlighting the need to develop a clinically relevant in vitro model to help further our understanding of the airway epithelium in preterm birth.

An underestimated pathogen: Staphylococcus epidermidis induces pro-inflammatory responses in human alveolar epithelial cells

OBJECTIVES

Conventionally regarded as a harmless skin commensal, Staphylococcus epidermidis accounts for the majority of neonatal late-onset sepsis and is shown to be associated with neonatal inflammatory morbidities, especially bronchopulmonary dysplasia. This study addressed the pro-inflammatory capacity of different S. epidermidis strains on human alveolar epithelial cells.

METHODS

A549 cell monolayers were stimulated by live bacteria of S. epidermidis RP62A strain (biofilm-positive) and ATCC 12228 strain (biofilm-negative) at a multiplicity of infection ratio of 10 for 24 h. LPS (100 ng/ml) and Pam3CSK4 (1 µg/ml) were used for comparisons. Cell viability was measured by MTT method. The mRNA and protein expression of inflammatory mediators and toll-like receptor (TLR)-2 were assessed using RT-PCR, immunoassays and immunofluorescence.

RESULTS

Both S. epidermidis strains induced expression of tumor necrosis factor (TNF)-α, IL-1β, interleukin (IL)-6, IL-8, monocyte chemoattractant protein (MCP)-1, interferon γ-induced protein 10 (IP-10) and intercellular adhesion molecule (ICAM)-1, but not IL-10. The stimulatory effect of RP62A exceeded that of LPS (p < 0.05). RP62A strain showed a trend towards higher induction of pro-inflammatory mediators than ATCC 12228 strain. The co-stimulation with RP62A strain decreased cell viability compared to control and TLR agonists (p < 0.05). RP62A but not ATCC 12228 stimulated mRNA and protein expression of TLR2.

CONCLUSIONS

S. epidermidis drives pro-inflammatory responses in lung epithelial cells in vitro. The pro-inflammatory capacity of S. epidermidis may differ between strains. Biofilm-positive S. epidermidis strain seems to induce more potent pulmonary pro-inflammation than biofilm-negative S. epidermidis strain.

Perinatal Ureaplasma Exposure Is Associated With Increased Risk of Late Onset Sepsis and Imbalanced Inflammation in Preterm Infants and May Add to Lung Injury

Background: Controversy remains concerning the impact of Ureaplasma on preterm neonatal morbidity.

Methods: Prospective single-center study in very low birth weight infants <30 weeks' gestation. Cord blood and initial nasopharyngeal swabs were screened for Ureaplasma parvum and U. urealyticum using culture technique and polymerase chain reaction. Neonatal outcomes were followed until death or discharge. Multi-analyte immunoassay provided cord blood levels of inflammatory markers. Using multivariate regression analyses, perinatal Ureaplasma exposure was evaluated as risk factor for the development of bronchopulmonary dysplasia (BPD), other neonatal morbidities until discharge and systemic inflammation at admission.

Results: 40/103 (39%) infants were positive for Ureaplasma in one or both specimens, with U. parvum being the predominant species. While exposure to Ureaplasma alone was not associated with BPD, we found an increased risk of BPD in Ureaplasma-positive infants ventilated ≥5 days (OR 1.64; 95% CI 0.12–22.98; p = 0.009). Presence of Ureaplasma was associated with a 7-fold risk of late onset sepsis (LOS) (95% CI 1.80–27.39; p = 0.014). Moreover, Ureaplasma-positive infants had higher I/T ratios (b 0.39; 95% CI 0.08–0.71; p = 0.014), increased levels of interleukin (IL)-17 (b 0.16; 95% CI 0.02–0.30; p = 0.025) and matrix metalloproteinase 8 (b 0.77; 95% CI 0.10–1.44; p = 0.020), decreased levels of IL-10 (b −0.77; 95% CI −1.58 to −0.01; p = 0.043) and increased ratios of Tumor necrosis factor-α, IL-8, and IL-17 to anti-inflammatory IL-10 (p = 0.003, p = 0.012, p < 0.001).

Conclusions: Positive Ureaplasma screening was not associated with BPD. However, exposure contributed to BPD in infants ventilated ≥5 days and conferred an increased risk of LOS and imbalanced inflammatory cytokine responses.

Club cell secretory protein (CC16) in gastric fluid at birth and subsequent lung disease in preterm infants

BACKGROUND

Club cell secretory protein (CC16) probably has a role in protecting the lung from inflammation.

AIM

To evaluate if low levels of CC16 in gastric fluid at birth, reflecting low levels of CC16 in the lung, would be associated with lung inflammation and respiratory morbidity.

METHODS

A study of 64 infants with mean gestational age 26.1 weeks. CC16 was analyzed in gastric fluid at birth. CC16, pro-inflammatory cytokines, and MMP-9 were analyzed in tracheal aspirate within 24 h from birth.

RESULTS

CC16 in gastric fluid increased with gestational age (P = 0.033). Lower concentrations of CC16 in gastric fluid at birth were associated with higher concentrations of IL-1β (P = 0.028), TNF-α (P = 0.034), and MMP-9 (P = 0.015) in tracheal aspirate. Infants who needed mechanical ventilation at 24 and 72 h of age had lower CC16 in gastric fluid than those not ventilated at these ages (P = 0.011 and P = 0.024, respectively). Lower CC16 in gastric fluid was associated with higher FiO₂ at 6 h (P = 0.009), higher PaCO₂ at 24 h (P = 0.03), more ventilator days (P = 0.012) and more days with supplemental oxygen (P = 0.03). Infants who had either died or were still treated with supplemental oxygen at 36 weeks postmenstrual age had lower CC16 in gastric fluid than infants with none of these outcomes (P = 0.049).

CONCLUSION

A low CC16 concentration in gastric fluid at birth was associated with increased inflammation in the trachea within the first 24 h of life and with more need for respiratory support in the neonatal period.

Ureaplasma Species Differentially Modulate Pro- and Anti-Inflammatory Cytokine Responses in Newborn and Adult Human Monocytes Pushing the State Toward Pro-Inflammation

Background:Ureaplasma species have been associated with chorioamnionitis and preterm birth and have been implicated in the pathogenesis of neonatal short and long-term morbidity. However, being mostly commensal bacteria, controversy remains on the pro-inflammatory capacity of Ureaplasma. Discussions are ongoing on the incidence and impact of prenatal, perinatal, and postnatal infection. The present study addressed the impact of Ureaplasma isolates on monocyte-driven inflammation. Methods: Cord blood monocytes of term neonates and adult monocytes, either native or LPS-primed, were cultured with Ureaplasma urealyticum (U. urealyticum) serovar 8 (Uu8) and Ureaplasma parvum serovar 3 (Up3). Using qRT-PCR, cytokine flow cytometry, and multi-analyte immunoassay, we assessed mRNA and protein expression of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-8, IL-12p40, IL-10, and IL-1 receptor antagonist (IL-1ra) as well as Toll-like receptor (TLR) 2 and TLR4. Results: Uu8 and Up3 induced mRNA expression and protein release of TNF-α, IL-1β and IL-8 in term neonatal and adult monocytes (p < 0.01 and p < 0.05). Intracellular protein expression of TNF-α, IL-1β and IL-8 in Ureaplasma-stimulated cells paralleled those results. Ureaplasma-induced cytokine levels did not significantly differ from LPS-mediated levels except for lower intracellular IL-1β in adult monocytes (Uu8: p < 0.05). Remarkably, ureaplasmas did not induce IL-12p40 response and promoted lower amounts of anti-inflammatory IL-10 and IL-1ra than LPS, provoking a cytokine imbalance more in favor of pro-inflammation (IL-1β/IL-10, IL-8/IL-10 and IL-8/IL-1ra: p < 0.01, vs. LPS). In contrast to LPS, both isolates induced TLR2 mRNA in neonatal and adult cells (p < 0.001 and p < 0.05) and suppressed TLR4 mRNA in adult monocytes (p < 0.05). Upon co-stimulation, Uu8 and Up3 inhibited LPS-induced intracellular IL-1β (p < 0.001 and p < 0.05) and IL-8 in adult monocytes (p < 0.01), while LPS-induced neonatal cytokines were maintained or aggravated (p < 0.05). Conclusion: Our data demonstrate a considerable pro-inflammatory capacity of Ureaplasma isolates in human monocytes. Stimulating pro-inflammatory cytokine responses while hardly inducing immunomodulatory and anti-inflammatory cytokines, ureaplasmas might push monocyte immune responses toward pro-inflammation. Inhibition of LPS-induced cytokines in adult monocytes in contrast to sustained inflammation in term neonatal monocytes indicates a differential modulation of host immune responses to a second stimulus. Modification of TLR2 and TLR4 expression may shape host susceptibility to inflammation.

Cytokine profiles at birth and the risk of developing severe respiratory distress and chronic lung disease

Background:

Neonates with the diagnosis of respiratory distress syndrome (RDS) were studied to investigate possible associations between cytokine levels at birth and developing severe RDS or chronic lung disease (CLD).

Materials and Methods:

This was a cross-sectional study on serum and bronchoalveolar lavage (BAL) samples collected within hours of birth from infants with moderate and severe RDS. Twenty infants with moderate RDS and 20 infants with severe RDS were studied. RDS was diagnosed on the basis of radiographic findings, respiratory distress, and an increasing oxygen requirement. RDS severity was graded based on the radiological findings and Downe's Score. CLD was diagnosed when infants were still on supplemented O₂ by at least 28 days of age. Levels of the cytokines interleukin (IL)-1β, IL-6, IL-8, IL-10, and tumor necrosis factor alpha were measured using enzyme-linked immunosorbent assay. “Statistical analysis was performed using the SPSS for Windows, (SPSS Inc., Chicago, IL, USA).”

Results:

Levels of the proinflammatory cytokines IL-8 and IL-1β were significantly higher in BAL of infants with severe RDS than those with moderate RDS (P = 0.007 and P = 0.02, respectively). IL-8 levels were also significantly higher in BAL and serum of infants who later progressed to CLD than in those who did not (P = 0.03 for both). The IL-8/IL-10 cytokine ratio was significantly higher in the BAL of severe RDS infants than in moderate RDS (P = 0.01) and in the serum of infants who progressed to CLD than in those who did not (P = 0.03).

Conclusion:

Levels of IL-8 and the IL-8/IL-10 ratio measured soon after birth were associated with severity of RDS as well as progression to CLD. Early measurement of cytokines levels and ratios may contribute to the prognosis and management of RDS and CLD.

Refining anti-inflammatory therapy strategies for bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is a severe lung disease of preterm infants, which is characterized by fewer, enlarged alveoli and increased inflammation. BPD has grave consequences for affected infants, but no effective and safe therapy exists. We previously showed that prophylactic treatment with interleukin‐1 receptor antagonist (IL‐1Ra) prevents murine BPD induced by perinatal inflammation and hyperoxia. Here, we used the same BPD model to assess whether an alternative anti‐inflammatory agent, protein C (PC), is as effective as IL‐1Ra against BPD. We also tested whether delayed administration or a higher dose of IL‐1Ra affects its ability to ameliorate BPD and investigated aspects of drug safety. Pups were reared in room air (21% O₂) or hyperoxia (65% or 85% O₂) and received daily injections with vehicle, 1200 IU/kg PC, 10 mg/kg IL‐1Ra (early or late onset) or 100 mg/kg IL‐1Ra. After 3 or 28 days, lung and brain histology were assessed and pulmonary cytokines were analysed using ELISA and cytokine arrays. We found that PC only moderately reduced the severe impact of BPD on lung structure (e.g. 18% increased alveolar number by PC versus 34% by IL‐1Ra); however, PC significantly reduced IL‐1β, IL‐1Ra, IL‐6 and macrophage inflammatory protein (MIP)‐2 by up to 89%. IL‐1Ra at 10 mg/kg prevented BPD more effectively than 100 mg/kg IL‐1Ra, but only if treatment commenced at day 1 of life. We conclude that prophylactic low‐dose IL‐1Ra and PC ameliorate BPD and have potential as the first remedy for one of the most devastating diseases preterm babies face.

Anti-inflammatory effects of the new generation synthetic surfactant CHF5633 on Ureaplasma-induced cytokine responses in human monocytes

BACKGROUND

Synthetic surfactants represent a promising alternative to animal-derived preparations in the treatment of neonatal respiratory distress syndrome. The synthetic surfactant CHF5633 has proven biophysical effectiveness and, moreover, demonstrated anti-inflammatory effects in LPS-stimulated monocytes. With ureaplasmas being relevant pathogens in preterm lung inflammation, the present study addressed immunomodulatory features on Ureaplasma-induced monocyte cytokine responses.

METHODS

Ureaplasma parvum-stimulated monocytes were exposed to CHF5633. TNF-α, IL-1β, IL-8, IL-10, TLR2 and TLR4 expression were analyzed using qPCR and flow cytometry.

RESULTS

CHF5633 did not induce pro-inflammation, and did not aggravate Ureaplasma-induced pro-inflammatory cytokine responses. It suppressed U. parvum-induced intracellular TNF-α (p < 0.05) and IL-1β (p < 0.05) in neonatal monocytes and inhibited Ureaplasma-induced TNF-α mRNA (p < 0.05), TNF-α protein (p < 0.001), and IL-1β (p = 0.05) in adult monocytes. Ureaplasma-modulated IL-8, IL-10, TLR2 and TLR4 were unaffected.

CONCLUSION

CHF5633 does neither act pro-apoptotic nor pro-inflammatory in native and Ureaplasma-infected monocytes. Suppression of Ureaplasma-induced TNF-α and IL-1β underlines anti-inflammatory features of CHF5633.

CD11b(+) Mononuclear Cells Mitigate Hyperoxia-Induced Lung Injury in Neonatal Mice

Bronchopulmonary dysplasia (BPD) is a common consequence of life-saving interventions for infants born with immature lungs. Resident tissue myeloid cells regulate lung pathology, but their role in BPD is poorly understood. To determine the role of lung interstitial myeloid cells in neonatal responses to lung injury, we exposed newborn mice to hyperoxia, a neonatal mouse lung injury model with features of human BPD. In newborn mice raised in normoxia, we identified a CD45(+) F4/80(+) CD11b(+), Ly6G(lo-int) CD71(+) population of cells in lungs of neonatal mice present in significantly greater percentages than in adult mice. In response to hyperoxia, surface marker and gene expression in whole lung macrophages/monocytes was biased to an alternatively activated phenotype. Partial depletion of these CD11b(+) mononuclear cells using CD11b-diphtheria toxin (DT) receptor transgenic mice resulted in 60% mortality by 40 hours of hyperoxia exposure with more severe lung injury, perivascular edema, and alveolar hemorrhage compared with DT-treated CD11b-DT receptor-negative controls, which displayed no mortality. These results identify an antiinflammatory population of CD11b(+) mononuclear cells that are protective in hyperoxia-induced neonatal lung injury in mice, and suggest that enhancing their beneficial functions may be a treatment strategy in infants at risk for BPD.

Systemic inflammation on postnatal days 21 and 28 and indicators of brain dysfunction 2years later among children born before the 28th week of gestation

BACKGROUND

Systemic inflammation during the first two postnatal weeks in extremely preterm newborns (<28weeks gestation) has been associated with an increased risk of neurodevelopmental dysfunctions. Little is known, however, about the relationship between systemic inflammation during the third and fourth postnatal weeks and subsequent development.

METHODS

We measured the concentrations of 16 inflammation-related proteins in blood spots collected on postnatal days 21 (N=749) and 28 (N=697) from infants born before the 28th week of gestation and assessed at age 2years. We then sought the developmental correlates of top quartile concentrations for gestational age and day the specimen was collected. Odds ratios and 95% confidence intervals were calculated from regular or multinomial logistic regression models (as appropriate).

RESULTS

Top quartile concentrations of CRP, IL-1β, IL-6, IL-6R, TNF-R2, IL-8, ICAM-1, and TSH on both days 21 and 28 were associated with ventriculomegaly (when in the NICU) and microcephaly at age 2years. Top quartile concentrations of CRP, SAA, IL-6, TNF-R2, IL-8, and ICAM-1 were associated with mental development index (MDI) of the Bayley-II<55, while top quartile concentrations of CRP, TNF-α (inversely), IL-8, and ICAM-1 were associated with psychomotor development index (PDI)<55 CONCLUSION: Extremely preterm newborns who had systemic inflammation during the third and fourth postnatal weeks were at increased risk of ventriculomegaly during the months after birth, and of microcephaly, and low Bayley Scale scores at 2years old.

Effects of the New Generation Synthetic Reconstituted Surfactant CHF5633 on Pro- and Anti-Inflammatory Cytokine Expression in Native and LPS-Stimulated Adult CD14+ Monocytes

Background

Surfactant replacement therapy is the standard of care for the prevention and treatment of neonatal respiratory distress syndrome. New generation synthetic surfactants represent a promising alternative to animal-derived surfactants. CHF5633, a new generation reconstituted synthetic surfactant containing SP-B and SP-C analogs and two synthetic phospholipids has demonstrated biophysical effectiveness in vitro and in vivo. While several surfactant preparations have previously been ascribed immunomodulatory capacities, in vitro data on immunomodulation by CHF5633 are limited, so far. Our study aimed to investigate pro- and anti-inflammatory effects of CHF5633 on native and LPS-stimulated human adult monocytes.

Methods

Highly purified adult CD14⁺ cells, either native or simultaneously stimulated with LPS, were exposed to CHF5633, its components, or poractant alfa (Curosurf^®). Subsequent expression of TNF-α, IL-1β, IL-8 and IL-10 mRNA was quantified by real-time quantitative PCR, corresponding intracellular cytokine synthesis was analyzed by flow cytometry. Potential effects on TLR2 and TLR4 mRNA and protein expression were monitored by qPCR and flow cytometry.

Results

Neither CHF5633 nor any of its components induced inflammation or apoptosis in native adult CD14⁺ monocytes. Moreover, LPS-induced pro-inflammatory responses were not aggravated by simultaneous exposure of monocytes to CHF5633 or its components. In LPS-stimulated monocytes, exposure to CHF5633 led to a significant decrease in TNF-α mRNA (0.57 ± 0.23-fold, p = 0.043 at 4h; 0.56 ± 0.27-fold, p = 0.042 at 14h). Reduction of LPS-induced IL-1β mRNA expression was not significant (0.73 ± 0.16, p = 0.17 at 4h). LPS-induced IL-8 and IL-10 mRNA and protein expression were unaffected by CHF5633. For all cytokines, the observed CHF5633 effects paralleled a Curosurf®-induced modulation of cytokine response. TLR2 and TLR4 mRNA and protein expression were not affected by CHF5633 and Curosurf®, neither in native nor in LPS-stimulated adult monocytes.

Conclusion

The new generation reconstituted synthetic surfactant CHF5633 was tested for potential immunomodulation on native and LPS-activated adult human monocytes. Our data confirm that CHF5633 does not exert unintended pro-inflammatory effects in both settings. On the contrary, CHF5633 significantly suppressed TNF-α mRNA expression in LPS-stimulated adult monocytes, indicating potential anti-inflammatory effects.

rIL-10 enhances IL-10 signalling proteins in foetal alveolar type II cells exposed to hyperoxia

Although the mechanisms by which hyperoxia promotes bronchopulmonary dysplasia are not fully defined, the inability to maintain optimal interleukin (IL)-10 levels in response to injury secondary to hyperoxia seems to play an important role. We previously defined that hyperoxia decreased IL-10 production and pre-treatment with recombinant IL-10 (rIL-10) protected these cells from injury. The objectives of these studies were to investigate the responses of IL-10 receptors (IL-10Rs) and IL-10 signalling proteins (IL-10SPs) in hyperoxic foetal alveolar type II cells (FATIICs) with and without rIL-10. FATIICs were isolated on embryonic day 19 and exposed to 65%-oxygen for 24 hrs. Cells in room air were used as controls. IL-10Rs protein and mRNA were analysed by ELISA and qRT-PCR, respectively. IL-10SPs were assessed by Western blot using phospho-specific antibodies. IL-10Rs protein and mRNA increased significantly in FATIICs during hyperoxia, but JAK1 and TYK2 phosphorylation showed the opposite pattern. To evaluate the impact of IL-8 (shown previously to be increased) and the role of IL-10Rs, IL-10SPs were reanalysed in IL-8-added normoxic cells and in the IL-10Rs' siRNA-treated hyperoxic cells. The IL-10Rs' siRNA-treated hyperoxic cells and IL-8-added normoxic cells showed the same pattern in IL10SPs with the hyproxic cells. And pre-treatment with rIL-10 prior to hyperoxia exposure increased phosphorylated IL-10SPs, compared to the rIL-10-untreated hyperoxic cells. These studies suggest that JAK1 and TYK2 were significantly suppressed during hyperoxia, where IL-8 may play a role, and rIL-10 may have an effect on reverting the suppressed JAK1 and TYK2 in FATIICs exposed to hyperoxia.

Systems approach to the study of brain damage in the very preterm newborn

Background: A systems approach to the study of brain damage in very preterm newborns has been lacking.

Methods: In this perspective piece, we offer encephalopathy of prematurity as an example of the complexity and interrelatedness of brain-damaging molecular processes that can be initiated inflammatory phenomena.

Results: Using three transcription factors, nuclear factor-kappa B (NF-κB), Notch-1, and nuclear factor erythroid 2 related factor 2 (NRF2), we show the inter-connectedness of signaling pathways activated by some antecedents of encephalopathy of prematurity.

Conclusions: We hope that as biomarkers of exposures and processes leading to brain damage in the most immature newborns become more readily available, those who apply a systems approach to the study of neuroscience can be persuaded to study the pathogenesis of brain disorders in the very preterm newborn.

Acute Neonatal Respiratory Failure

Acute respiratory failure requiring assisted ventilation is one of the most common reasons for admission to the neonatal intensive care unit. Respiratory failure is the inability to maintain either normal delivery of oxygen to the tissues or normal removal of carbon dioxide from the tissues. It occurs when there is an imbalance between the respiratory workload and ventilatory strength and endurance. Definitions are somewhat arbitrary but suggested laboratory criteria for respiratory failure include two or more of the following: PaCO₂ > 60 mmHg, PaO₂ < 50 mmHg or O₂ saturation <80 % with an FiO₂ of 1.0 and pH < 7.25 (Wen et al. 2004).

Systemic inflammation in the extremely low gestational age newborn following maternal genitourinary infections

PROBLEM

Gestational genitourinary infections are associated with lifelong disabilities, but it is unknown if neonatal inflammation is involved.

METHOD

Mothers of 914 infants born before 28th gestation week reported cervical/vaginal infection (CVI), and/or urine/bladder/kidney infection (UTI), or neither. Inflammation proteins measured in baby's blood on postnatal days 1, 7, and 14 were considered elevated if in the top quartile for gestational age. Logistic regression models adjusting for potential confounders assessed odds ratios.

RESULTS

Compared to mothers with neither UTI/CVI, those with CVI were more likely to have infants with elevated CRP, SAA, MPO, IL-1β, IL-6, IL-6R, TNF-α, RANTES, ICAM-3, E-selectin, and VEGF-R2 on day 1; those with UTI were more likely to have infants with elevated MPO, IL-6R, TNF-R1, TNF-R2, and RANTES on day 7. Placental anaerobes and genital mycoplasma were more common in pregnancies with CVI.

CONCLUSION

Gestational UTI/CVI should be targeted for preventing systemic inflammation in the very preterm newborn.

Oxidative stress and bronchopulmonary dysplasia

Bronchopulmonary dysplasia (BPD) is the major cause of pulmonary disease in infants. The pathophysiology and management of BPD changed with the improvement of neonatal intensive care unit (NICU) management and with the increase of survival rates. Despite the improvements made, BPD is still a public health concern, resulting in frequent hospitalizations with high rates of mortality, impaired weight and height growth, and neurodevelopmental disorders. Lung injury in the neonatal period has multiple etiologic factors - genetic, hemodynamic, metabolic, nutritional, mechanical, and infectious mechanisms - act in a cumulative and synergic way. Free radical (FR) generation is largely recognized as the major cause of lung damage. Oxidative stress (OS) is the final common endpoint for a complex convergence of events, some genetically determined and some triggered by in utero stressors. Inflammatory placental disorders and chorioamnionitis also play an important role due to the coexistence of inflammatory and oxidative lesions. In addition, the contribution of airway inflammation has been extensively studied. The link between inflammation and OS injury involves the direct activation of inflammatory cells, especially granulocytes, which potentiates the inflammatory reaction. Individualized interventions to support ventilation, minimize oxygen exposure, minimize apnea, and encourage growth should decrease both the frequency and severity of BPD. Future perspectives suggest supplementation with enzymatic and/or non-enzymatic antioxidants. The use of antioxidants in preterm newborns particularly exposed to OS and at risk for BPD represents a logical strategy to ameliorate FRs injury, but further studies are needed to support this hypothesis.

Anti-inflammatory actions of endogenous and exogenous interleukin-10 versus glucocorticoids on macrophage functions of the newly born

OBJECTIVE

To determine whether specific macrophage immune functions of the newly born are insensitive to the actions of therapeutic levels of dexamethasone (DEX), previously measured in infants with bronchopulmonary dysplasia (BPD), compared with betamethasone (BETA) and exogenous or endogenous interleukin-10 (IL-10).

STUDY DESIGN

Macrophages were differentiated from cord blood monocytes (N=18). A serial dose-response (around 10(-8 )M), in vitro study was used to examine the effect of DEX, BETA and IL-10, on proinflammatory (PI) cytokine release, phagocytosis and respiratory burst.

RESULT

Exogenous IL-10 (10(-8 )M) significantly (P<0.05) inhibited the endotoxin-stimulated release of IL-6, IL-8 and tumor necrosis factor by 63 to 82% with no significant effect by DEX and BETA. There was no inhibition by these three agents at 10(-8 )M on phagocytosis and respiratory burst. Inhibition of endogenous IL-10 with a monoclonal antibody significantly increased endotoxin-stimulated cytokine release by at least fourfold.

CONCLUSION

Macrophages were relatively insensitive to therapeutic levels of DEX and BETA with regard to PI cytokine release. This study provides rationale for translational and preclinical research using airway instillation of IL-10 for the treatment of BPD.

Urine protein biomarkers for the diagnosis and prognosis of necrotizing enterocolitis in infants

OBJECTIVES

To test the hypothesis that an exploratory proteomics analysis of urine proteins with subsequent development of validated urine biomarker panels would produce molecular classifiers for both the diagnosis and prognosis of infants with necrotizing enterocolitis (NEC).

STUDY DESIGN

Urine samples were collected from 119 premature infants (85 NEC, 17 sepsis, 17 control) at the time of initial clinical concern for disease. The urine from 59 infants was used for candidate biomarker discovery by liquid chromatography/mass spectrometry. The remaining 60 samples were subject to enzyme-linked immunosorbent assay for quantitative biomarker validation.

RESULTS

A panel of 7 biomarkers (alpha-2-macroglobulin-like protein 1, cluster of differentiation protein 14, cystatin 3, fibrinogen alpha chain, pigment epithelium-derived factor, retinol binding protein 4, and vasolin) was identified by liquid chromatography/mass spectrometry and subsequently validated by enzyme-linked immunosorbent assay. These proteins were consistently found to be either up- or down-regulated depending on the presence, absence, or severity of disease. Biomarker panel validation resulted in a receiver-operator characteristic area under the curve of 98.2% for NEC vs sepsis and an area under the curve of 98.4% for medical NEC vs surgical NEC.

CONCLUSIONS

We identified 7 urine proteins capable of providing highly accurate diagnostic and prognostic information for infants with suspected NEC. This work represents a novel approach to improving the efficiency with which we diagnose early NEC and identify those at risk for developing severe, or surgical, disease.

Interleukins for the paediatric pulmonologist

Interleukins are critical immune modulators and since their first description in 1977, there has been a steady increase in the recognition of their roles in many paediatric respiratory diseases. This basic and clinical knowledge is now maturing into both approved and investigational therapies aimed at blocking or modifying the interleukin response. The purpose of this review is to bring up to date what is known about interleukin function in paediatric pulmonology, focusing on nine important lung conditions. This is followed by summaries about 18 interleukins which have been associated with these paediatric pulmonary conditions. Throughout, emphasis is placed on where interventions have been tested. Over the next several years, it is likely that many more treatments based on interleukin biology and function will become available and understanding the basis for these therapies will allow the practicing paediatric pulmonologist to take appropriate advantage of them.

Intermittent or sustained systemic inflammation and the preterm brain

Exposure to perinatal infection and inflammation is associated with an increased risk for neonatal brain damage and developmental disabilities. In this integrated mechanism review, we discuss evidence in support of the contention that the preterm newborn is capable of intermittent or sustained systemic inflammation (ISSI), which appears to contribute more to adverse neurodevelopmental outcomes in preterm infants than does shorter duration inflammation.

Systemic hydrogen sulfide administration partially restores normal alveolarization in an experimental animal model of bronchopulmonary dysplasia

Arrested alveolarization is the pathological hallmark of bronchopulmonary dysplasia (BPD), a complication of premature birth. Here, the impact of systemic application of hydrogen sulfide (H2S) on postnatal alveolarization was assessed in a mouse BPD model. Exposure of newborn mice to 85% O2 for 10 days reduced the total lung alveoli number by 56% and increased alveolar septal wall thickness by 29%, as assessed by state-of-the-art stereological analysis. Systemic application of H2S via the slow-release H2S donor GYY4137 for 10 days resulted in pronounced improvement in lung alveolarization in pups breathing 85% O2, compared with vehicle-treated littermates. Although without impact on lung oxidative status, systemic H2S blunted leukocyte infiltration into alveolar air spaces provoked by hyperoxia, and restored normal lung interleukin 10 levels that were otherwise depressed by 85% O2. Treatment of primary mouse alveolar type II (ATII) cells with the rapid-release H2S donor NaHS had no impact on cell viability; however, NaHS promoted ATII cell migration. Although exposure of ATII cells to 85% O2 caused dramatic changes in mRNA expression, exposure to either GYY4137 or NaHS had no impact on ATII cell mRNA expression, as assessed by microarray, suggesting that the effects observed were independent of changes in gene expression. The impact of NaHS on ATII cell migration was attenuated by glibenclamide, implicating ion channels, and was accompanied by activation of Akt, hinting at two possible mechanisms of H2S action. These data support further investigation of H2S as a candidate interventional strategy to limit the arrested alveolarization associated with BPD.

Cyclooxygenase-2 in newborn hyperoxic lung injury

Supraphysiological O2 concentrations, mechanical ventilation, and inflammation significantly contribute to the development of bronchopulmonary dysplasia (BPD).Exposure of newborn mice to hyperoxia causes inflammation and impaired alveolarization similar to that seen in infants with BPD.Previously, we demonstrated that pulmonary cyclooxygenase-2 (COX-2) protein expression is increased in hyperoxia-exposed newborn mice.The present studies were designed to define the role of COX-2 in newborn hyperoxic lung injury.We tested the hypothesis that attenuation of COX-2 activity would reduce hyperoxia-induced inflammation and improve alveolarization.Newborn C3H/HeN micewere injected daily with vehicle, aspirin (nonselective COX-2 inhibitor), or celecoxib (selective COX-2 inhibitor) for the first 7 days of life.Additional studies utilized wild-type (C57Bl/6, COX-2(+/+)), heterozygous (COX-2(+/-)), and homozygous (COX-2(-/-)) transgenic mice.Micewere exposed to room air (21% O2) or hyperoxia (85% O2) for 14 days.Aspirin-injected and COX-2(-/-) pups had reduced levels of monocyte chemoattractant protein (MCP-1) in bronchoalveolar lavage fluid (BAL).Both aspirin and celecoxib treatment reduced macrophage numbers in the alveolar walls and air spaces.Aspirin and celecoxib treatment attenuated hyperoxia-induced COX activity, including altered levels of prostaglandin (PG)D2 metabolites.Decreased COX activity, however, did not prevent hyperoxia-induced lung developmental deficits.Our data suggest thatincreased COX-2 activity may contribute to proinflammatory responses, including macrophage chemotaxis, during exposure to hyperoxia.Modulation of COX-2 activity may be a useful therapeutic target to limit hyperoxia-induced inflammation in preterm infants at risk of developing BPD.

Autism spectrum disorder in children born preterm-role of exposure to perinatal inflammation

Autism Spectrum Disorder (ASD) is the collective term for neurodevelopmental disorders characterized by qualitative impairments in social interaction, communication, and a restricted range of activities and interests. Many countries, including Australia, have reported a dramatic increase in the number of diagnoses over the past three decades, with current prevalence of ASD at 1 in every 110 individuals (~1%). The potential role for an immune-mediated mechanism in ASD has been implicated by several studies, and some evidence suggests a potential link between prenatal infection-driven inflammation and subsequent development of ASD. Furthermore, a modest number of contemporary studies have reported a markedly increased prevalence of ASD in children born preterm, who are at highest risk of exposure to perinatal inflammation. However, the mechanisms that underpin the susceptibility to infection-driven inflammation during pregnancy and risk of preterm birth, and how these intersect with the subsequent development of ASD in the offspring, is not understood. This review aims to summarize and discuss the potential mechanisms and evidence for the role of prenatal infection on the central nervous system, and how it may increase the susceptibility for ASD pathogenesis in children born preterm.

Acute lung injury in preterm fetuses and neonates: mechanisms and molecular pathways

Acute lung injury (ALI) results in high morbidity and mortality among preterm neonates and efforts have therefore been devoted to both antenatal and postnatal prevention of the disease. ALI is the result of an inflammatory response which is triggered by a variety of different mechanisms. It mostly affects the fetal lung and, in particular, causes damage to the integrity of the lung's alveolar-capillary unit while weakening its cellular linings. Chemotactic activity and inflammatory products, such as proinflammatory cytokines TNF-α, IL-1, IL-6, IL-11, VEGF,TGF-α and TGF-β, provoke serious damage to the capillary endothelium and the alveolar epithelium, resulting in hyaline membrane formation and leakage of protein-rich edema fluid into the alveoli. Chorioamnionitis plays a major part in triggering fetal lung inflammation, while mechanical ventilation, the application of which is frequently necessary in preterm neonates, also causes ALI by inducing proinflammatory cytokines. Many different ventilation-strategies have been developed in order to reduce potential lung injury. Furthermore, tissue injury may occur as a result of injurious oxygen by-products (Reactive Oxygen Species, ROS), secondary to hyperoxia. Knowledge of the inflammatory pathways that connect intra-amniotic inflammation and ALI can lead to the formulation of novel interventional procedures. Future research should concentrate on the pathophysiology of ALI in preterm neonates and οn possible pharmaceutical interventions targeting prevention and/or resolution of ALI.

Reduced IL-10 production in fetal type II epithelial cells exposed to mechanical stretch is mediated via activation of IL-6-SOCS3 signaling pathway

An imbalance between pro-inflammatory and anti-inflammatory cytokines is a key factor in the lung injury of premature infants exposed to mechanical ventilation. Previous studies have shown that lung cells exposed to stretch produces reduced amounts of the anti-inflammatory cytokine IL-10. The objective of these studies was to analyze the signaling mechanisms responsible for the decreased IL-10 production in fetal type II cells exposed to mechanical stretch. Fetal mouse type II epithelial cells isolated at embryonic day 18 were exposed to 20% stretch to simulate lung injury. We show that IL-10 receptor gene expression increased with gestational age. Mechanical stretch decreased not only IL-10 receptor gene expression but also IL-10 secretion. In contrast, mechanical stretch increased release of IL-6. We then investigated IL-10 signaling pathway-associated proteins and found that in wild-type cells, mechanical stretch decreased activation of JAK1 and TYK2 and increased STAT3 and SOCS3 activation. However, opposite effects were found in cells isolated from IL-10 knockout mice. Reduction in IL-6 secretion by stretch was observed in cells isolated from IL-10 null mice. To support the idea that stretch-induced SOCS3 expression via IL-6 leads to reduced IL-10 expression, siRNA-mediated inhibition of SOCS3 restored IL-10 secretion in cells exposed to stretch and decreased IL-6 secretion. Taken together, these studies suggest that the inhibitory effect of mechanical stretch on IL-10 secretion is mediated via activation of IL-6-STAT3-SOCS3 signaling pathway. SOCS3 could be a therapeutic target to increase IL-10 production in lung cells exposed to mechanical injury.

Differential effect of exogenous interleukin-10 versus glucocorticoids on gene expression and pro-inflammatory cytokine release by polymorphonuclear leukocytes and monocytes of the newly born

Bronchopulmonary dysplasia (BPD) is one of the most common causes of mortality and morbidity in neonatal intensive care units. Persistent inflammation, with an abnormal influx of polymorphonuclear leukocytes (PMNs) followed by monocytes (MONOs), occurs early in the pathogenesis of BPD. Anti-inflammatory therapy with better efficacy and safety than dexamethasone (DEX) is needed. In the present study we determined cell-specific gene expression and cytokine release in response to glucocorticoids versus interleukin-10 (IL-10). Subsequently, we hypothesized that the insensitivity of MONOs to DEX was associated with a failure of the glucocorticoid receptor to translocate to the nucleus. PMNs and MONOs were isolated from umbilical cord blood at birth, and pretreated with PBS vehicle, IL-10 or glucocorticoids prior to endotoxin (LPS)-stimulation for 4 and 18h. Genome-wide gene expressions were determined by microarray and validated by RT-qPCR. Interleukin 8 release in cell culture supernatant was measured by ELISA. To examine the mechanism of monocyte insensitivity to glucocorticoids, nuclear translocation of the glucocorticoid receptor was determined by Western blots. MONOs had 6 times the number of genes changing expression with IL-10 compared to PMNs at 4h. DEX at the therapeutic level for neonates with BPD had no effect on gene expression in MONOs. The order of potency for inhibition of interleukin-8 release from MONOs was IL-10 >betamethasone >dexamethasone and hydrocortisone. Glucocorticoid potency in MONOs was directly related to glucocorticoid receptor translocation to nucleus. Gene expression profiling for IL-10 versus glucocorticoids indicates there may be major differences in therapeutic efficacy for BPD.

Gene expression profile of endotoxin-stimulated leukocytes of the term new born: control of cytokine gene expression by interleukin-10

Introduction

Increasing evidence now supports the association between the fetal inflammatory response syndrome (FIRS) with the pathogenesis of preterm labor, intraventricular hemorrhage and bronchopulmonary dysplasia. Polymorphonuclear leukocyte (PMNs) and mononuclear cell (MONOs) infiltration of the placenta is associated with these disorders. The aim of this study was to reveal cell-specific differences in gene expression and cytokine release in response to endotoxin that would elucidate inflammatory control mechanisms in the newly born.

Methods

PMNs and MONOs were separately isolated from the same cord blood sample. A genome-wide microarray screened for gene expression and related pathways at 4 h of LPS stimulation (n = 5). RT-qPCR and ELISA were performed for selected cytokines at 4 h and 18 h of LPS stimulation.

Results

Compared to PMNs, MONOs had a greater diversity and more robust gene expression that included pro-inflammatory (PI) cytokines, chemokines and growth factors at 4 h. Only MONOs had genes changing expression (all up regulated including interleukin-10) that were clustered in the JAK/STAT pathway. Pre-incubation with IL-10 antibody, for LPS-stimulated MONOs, led to up regulated PI and IL-10 gene expression and release of PI cytokines after 4 h.

Discussion

The present study suggests a dominant role of MONO gene expression in control of the fetal inflammatory response syndrome at 4 hrs of LPS stimulation. LPS-stimulated MONOs but not PMNs of the newborn have the ability to inhibit PI cytokine gene expression by latent IL-10 release.

Tracheal aspirate gene expression in preterm newborns and development of bronchopulmonary dysplasia

BACKGROUND

Bronchopulmonary dysplasia (BPD) occurs in association with prenatal conditions predisposing infants to inflammation and remodeling of the premature lungs. Because of the lack of useful biomarkers for BPD, the gene expression of tracheal aspirate fluid (TAF) cells in premature infants was analyzed.

METHODS

Of 148 consecutive patients, 26 preterm infants (gestational age <34 weeks) were enrolled, who underwent assisted ventilation at birth for respiratory failure. Patients with congenital disorders were excluded. Half of these infants developed BPD. Interleukin (IL)-10, interferon (IFN)-γ, transforming growth factor (TGF)-β1, and platelet-derived growth factor (PDGF)-B mRNA of TAF cells were quantified on real-time polymerase chain reaction.

RESULTS

IL-10 (P < 0.01) and IFN-γ (P= 0.03) but not TGF-β1 or PDGF-B mRNA levels at birth were higher in BPD than in non-BPD infants. IL-10 expression differentiated BPD with the highest sensitivity (92%) and specificity (77%). IL-10 levels correlated with TGF-β1 (P= 0.03) and IFN-γ (P= 0.01), but not with PDGF-B levels. When BPD infants were classified according to comorbidity (group 1, six patients who suffered respiratory distress syndrome [RDS] but not chorioamnionitis [CAM]; group 2, five patients who had CAM but not RDS), PDGF-B levels were higher in group 2 (P= 0.01). High IL-10 expression was selected as a risk factor for BPD in infants who had CAM but not RDS (P= 0.01), although prolonged oxygen therapy was the most sensitive indicator for BPD (P < 0.01) on multivariate analysis.

CONCLUSIONS

High IL-10 expression in TAF cells at birth could predict the evolution of BPD, but with less impact than oxygen requirement. PDGF might play a different role in the inflammatory process of premature lungs.

Respiratory support in meconium aspiration syndrome: a practical guide

Meconium aspiration syndrome (MAS) is a complex respiratory disease of the term and near-term neonate. Inhalation of meconium causes airway obstruction, atelectasis, epithelial injury, surfactant inhibition, and pulmonary hypertension, the chief clinical manifestations of which are hypoxaemia and poor lung compliance. Supplemental oxygen is the mainstay of therapy for MAS, with around one-third of infants requiring intubation and mechanical ventilation. For those ventilated, high ventilator pressures, as well as a relatively long inspiratory time and slow ventilator rate, may be necessary to achieve adequate oxygenation. High-frequency ventilation may offer a benefit in infants with refractory hypoxaemia and/or gas trapping. Inhaled nitric oxide is effective in those with pulmonary hypertension, and other adjunctive therapies, including surfactant administration and lung lavage, should be considered in selected cases. With judicious use of available modes of ventilation and adjunctive therapies, infants with even the most severe MAS can usually be supported through the disease, with an acceptably low risk of short- and long-term morbidities.

IL-10 inhibits inflammatory cytokines released by fetal mouse lung fibroblasts exposed to mechanical stretch

BACKGROUND

Mechanical ventilation plays an important role in the pathogenesis of bronchopulmonary dysplasia. However, the molecular mechanisms by which excessive stretch induces lung inflammation are not well characterized.

OBJECTIVES

In this study, we investigated in vitro the contribution of lung mesenchymal cells to the inflammatory response mediated by mechanical stretch and the potential protective role of IL-10.

METHODS

Fetal mouse lung fibroblasts isolated during the saccular stage of lung development were exposed to 20% cyclic stretch to simulate mechanical injury. The phenotype of cultured fibroblasts was investigated by red oil O and alpha-smooth muscle actin (α-SMA) staining. Cell necrosis, apoptosis, and inflammation were analyzed by lactate dehydrogenase release, cleaved caspase-3 activation and release of cytokines and chemokines into the supernatant, respectively.

RESULTS

First, we characterized the phenotype of the cultured fibroblasts and found an absence of red oil O staining and 100% positive staining for α-SMA, indicating that cultured fibroblasts were myofibroblasts. Mechanical stretch increased necrosis and apoptosis by two- and three-fold, compared to unstretched samples. Incubation of monolayers with IL-10 prior to stretch did not affect necrosis but significantly decreased apoptosis. Mechanical stretch increased release of pro-inflammatory cytokines and chemokines IL-1β, MCP-1, RANTES, IL-6, KC and TNF-α into the supernatant by 1.5- to 2.5-fold, and administration of IL-10 before stretch blocked that release.

CONCLUSIONS

Our data demonstrate that lung interstitial cells may play a significant role in the inflammatory cascade triggered by mechanical stretch. IL-10 protects fetal fibroblasts from injury secondary to stretch. Pediatr. Pulmonol. 2011; 46:640-649. © 2011 Wiley-Liss, Inc.

Correlation of urinary inflammatory and oxidative stress markers in very low birth weight infants with subsequent development of bronchopulmonary dysplasia

Currently, bronchopulmonary dysplasia (BPD) occurs almost exclusively in pre-term infants. In addition to prematurity, other factors like oxygen toxicity and inflammation can contribute to the pathogenesis. This study aimed to compare urinary inflammatory and oxidative stress markers between the no/mild BPD group and moderate/severe BPD group and between BPD cases with significant early lung disease like respiratory distress syndrome (RDS) ('classic' BPD) and with minimal early lung disease ('atypical' BPD). A total of 60 patients who were a gestational age < 30 weeks or a birth weight < 1250 g were included. Urine samples were obtained on the 1(st), 3(rd) and 7(th) day of life and measured the levels of leukotriene E(4) (LTE(4)) and 8-hydroxydeoxyguanosine (8-OHdG). The 8-OHdG values on the 3(rd) day showed significant correlation to duration of mechanical ventilation. The 8-OHdG levels on the 7(th) day were the independent risk factor for developing moderate/severe BPD. In 'classic' BPD, the 8-OHdG values on the 3(rd) day were higher than those of 'atypical' BPD. In 'atypical' BPD, the LTE(4) values on the 7(th) day were higher than the values in 'classic' BPD. These results suggest that oxidative DNA damage could be the crucial mechanism in the pathogenesis of current BPD and the ongoing inflammatory process could be an important mechanism in 'atypical' BPD.

Effect of recombinant IL-10 on cultured fetal rat alveolar type II cells exposed to 65%-hyperoxia

BACKGROUND

Hyperoxia plays an important role in the genesis of lung injury in preterm infants. Although alveolar type II cells are the main target of hyperoxic lung injury, the exact mechanisms whereby hyperoxia on fetal alveolar type II cells contributes to the genesis of lung injury are not fully defined, and there have been no specific measures for protection of fetal alveolar type II cells.

OBJECTIVE

The aim of this study was to investigate (a) cell death response and inflammatory response in fetal alveolar type II cells in the transitional period from canalicular to saccular stages during 65%-hyperoxia and (b) whether the injurious stimulus is promoted by creating an imbalance between pro- and anti-inflammatory cytokines and (c) whether treatment with an anti-inflammatory cytokine may be effective for protection of fetal alveolar type II cells from injury secondary to 65%-hyperoxia.

METHODS

Fetal alveolar type II cells were isolated on embryonic day 19 and exposed to 65%-oxygen for 24 h and 36 h. Cells in room air were used as controls. Cellular necrosis was assessed by lactate dehydrogenase-release and flow cytometry, and apoptosis was analyzed by TUNEL assay and flow cytometry, and cell proliferation was studied by BrdU incorporation. Release of cytokines including VEGF was analyzed by ELISA, and their gene expressions were investigated by qRT-PCR.

RESULTS

65%-hyperoxia increased cellular necrosis, whereas it decreased cell proliferation in a time-dependent manner compared to controls. 65%-hyperoxia stimulated IL-8-release in a time-dependent fashion, whereas the anti-inflammatory cytokine, IL-10, showed an opposite response. 65%-hyperoxia induced a significant decrease of VEGF-release compared to controls, and similar findings were observed on IL-8/IL-10/VEGF genes expression. Preincubation of recombinant IL-10 prior to 65%-hyperoxia decreased cellular necrosis and IL-8-release, and increased VEGF-release and cell proliferation significantly compared to hyperoxic cells without IL-10.

CONCLUSIONS

The present study provides an experimental evidence that IL-10 may play a potential role in protection of fetal alveolar type II cells from injury induced by 65%-hyperoxia.

Correlation between serum caffeine levels and changes in cytokine profile in a cohort of preterm infants

OBJECTIVE

To determine changes in cytokine levels associated with caffeine treatment in a cohort of preterm infants.

STUDY DESIGN

For this observational prospective study, we collected clinical data from 26 preterm infants (≤ 30 weeks gestational age). In addition to caffeine levels, cytokine profiles in peripheral blood (PB) and tracheal aspirates (TA) were determined with enzyme-linked immunosorbent assay at birth, before and after (at 24 hours and 1 week) initiation of caffeine. Non-parametric statistics were applied.

RESULTS

Included infants were 26.9 ± 1.7 weeks gestational age and weighed 985 ± 202 g. At birth, all cytokine concentrations were significantly greater in TA than PB. Serum caffeine levels were 11.1 μg/mL (interquartile range, 1.85) at approximately 24 hours post-load and 16.4 (8.7) μg/mL at 1 week on treatment. At approximately 24 hours post-load, interleukin (IL)-10 levels decreased by 47.5% (P = .01) in PB and 38.5% (P = .03) in TA, whereas other cytokine levels remained unchanged. At 1 week, caffeine levels were correlated (U-shaped) with changes in proinflammatory tumor necrosis factor-α (R(2) = 0.65; P = .0008), interleukin (IL)-1β (R(2) = 0.73; P = .0007), and IL-6 (R(2) = 0.59; P = .003), whereas inversely correlated (linear) with the anti-inflammatory IL-10 (R(2) = 0.64; P = .0008). Altogether, caffeine, at serum levels ≥ 20 μg/mL, was associated with a proinflammatory profile after 1 week of treatment.

CONCLUSIONS

Caffeine treatment for apnea of prematurity correlates with changes in cytokine profile. Caffeine levels ≥ 20 μg/mL are associated with a proinflammatory profile in our cohort of preterm infants.

Isolation of tracheal aspirate mesenchymal stromal cells predicts bronchopulmonary dysplasia

BACKGROUND

We have isolated mesenchymal stem cells (MSCs) from tracheal aspirates of premature infants with respiratory distress. Under the influence of transforming growth factor β, MSCs differentiate into α-smooth-muscle actin-expressing myofibroblasts. Myofibroblasts are increased in the lungs of patients with bronchopulmonary dysplasia (BPD), a chronic lung disease of prematurely born infants.

OBJECTIVE

We tested whether isolation of MSCs from tracheal aspirates of premature infants with respiratory distress during the first week of life correlates with BPD.

METHODS

Eighty-four infants born at a gestational age of <33 weeks and requiring mechanical ventilation were studied. Aspirates were collected during suctioning and centrifuged. Cell pellets were resuspended in culture medium and plated. Adherent cells were grown to confluence.

RESULTS

MSCs were isolated from the tracheal aspirates of 56 infants; 28 aspirate samples showed no MSCs. There was no statistical difference in gestational age or birth weight between the MSC and no-MSC groups. In the MSC group, 12 infants died and 25 developed BPD, as defined by a requirement for supplemental oxygen at 36 weeks' postmenstrual age. In the no-MSC group, 6 infants died and 1 developed BPD. Accounting for potential influences of gender, birth weight, gestational age, number of tracheal aspirate samples taken, and the duration of endotracheal intubation (up to 7 days), isolation of MSCs increased the adjusted odds ratio of BPD more than 21-fold (95% confidence interval: 1.82-265.85).

CONCLUSIONS

Isolation of tracheal aspirate MSCs predicts the development of BPD, which suggests that MSCs play an important role in the pathogenesis of this disease.