Tidal volume drives inflammation during mechanical ventilation for viral respiratory infection.

OBJECTIVE: Respiratory syncytial virus lower respiratory tract infection is the most frequent cause of respiratory insufficiency necessitating mechanical ventilation in infants during the winter season. Recently, we presented a new animal model to show that mechanical ventilation aggravates respiratory syncytial virus-induced pulmonary inflammation by distinct mechanisms. We now use this model to study whether low tidal volume mechanical ventilation causes less ventilator-induced lung injury in the presence of respiratory syncytial virus lower respiratory tract infection. DESIGN: Randomized controlled experimental study. SETTING: University Medical Center animal laboratory. SUBJECTS: Male BALB/c mice, 6-8 weeks old and weighing 20-28 g. INTERVENTIONS: Mice were inoculated with respiratory syncytial virus or mock virus on day 0 and ventilated on day 1 or 5 with high (12 mL/kg) or low (6 mL/kg) tidal volume for 5 hours. MEASUREMENTS AND MAIN RESULTS: Total and differential cell counts as well as cytokine concentrations were determined in bronchoalveolar lavage fluid. Compared with nonventilated respiratory syncytial virus-infected mice, high tidal volume ventilation of respiratory syncytial virus-infected mice on day 5 enhanced bronchoalveolar lavage fluid total cell count (0.35 vs 0.99 × 10e6/mL; p < 0.01), neutrophils (0.02 vs 0.17 × 10e6/mL; p < 0.01), interleukin-6 (58 vs 250 pg/mL; p < 0.01), and keratinocyte-derived chemokine (95 vs 335 pg/mL; p < 0.01) levels. In low tidal volume ventilation of respiratory syncytial virus-infected mice, no significant difference in cell counts or cytokine concentrations was observed compared with spontaneous breathing respiratory syncytial virus-infected controls on both days. CONCLUSIONS: Low tidal volume mechanical ventilation causes less ventilation-induced cellular and cytokine influx into the bronchoalveolar space during respiratory syncytial virus lower respiratory tract infection.

Expanding the spectrum of phenotypes associated with germline PIGA mutations: a child with developmental delay, accelerated linear growth, facial dysmorphisms, elevated alkaline phosphatase, and progressive CNS abnormalities.

Phosphatidyl inositol glycan (PIG) enzyme subclasses are involved in distinct steps of glycosyl phosphatidyl inositol anchor protein biosynthesis. Glycolsyl phosphatidyl inositol-anchored proteins have heterogeneous functions; they can function as enzymes, adhesion molecules, complement regulators and co-receptors in signal transduction pathways. Germline mutations in genes encoding different members of the PIG family result in diverse conditions with (severe) developmental delay, (neonatal) seizures, hypotonia, CNS abnormalities, growth abnormalities, and congenital abnormalities as hallmark features. The variability of clinical features resembles the typical diversity of other glycosylation pathway deficiencies such as the congenital disorders of glycosylation. Here, we report the first germline missense mutation in the PIGA gene associated with accelerated linear growth, obesity, central hypotonia, severe refractory epilepsy, cardiac anomalies, mild facial dysmorphic features, mildly elevated alkaline phosphatase levels, and CNS anomalies consisting of progressive cerebral atrophy, insufficient myelinization, and cortical MRI signal abnormalities. X-exome sequencing in the proband identified a c.278C>T (p.Pro93Leu) mutation in the PIGA gene. The mother and maternal grandmother were unaffected carriers and the mother showed 100% skewing of the X-chromosome harboring the mutation. These results together with the clinical similarity of the patient reported here and the previously reported patients with a germline nonsense mutation in PIGA support the determination that this mutation caused the phenotype in this family.

Mechanical ventilation drives inflammation in severe viral bronchiolitis.

INTRODUCTION: Respiratory insufficiency due to severe respiratory syncytial virus (RSV) infection is the most frequent cause of paediatric intensive care unit admission in infants during the winter season. Previous studies have shown increased levels of inflammatory mediators in airways of mechanically ventilated children compared to spontaneous breathing children with viral bronchiolitis. In this prospective observational multi-center study we aimed to investigate whether this increase was related to disease severity or caused by mechanical ventilation. MATERIALS AND METHODS: Nasopharyngeal aspirates were collected <1 hour before intubation and 24 hours later in RSV bronchiolitis patients with respiratory failure (n = 18) and non-ventilated RSV bronchiolitis controls (n = 18). Concentrations of the following cytokines were measured: interleukin (IL)-1α, IL-1ß, IL-6, monocyte chemotactic protein (MCP)-1 and macrophage inflammatory protein (MIP)-1α. RESULTS: Baseline cytokine levels were comparable between ventilated and non-ventilated infants. After 24 hours of mechanical ventilation mean cytokine levels, except for MIP-1α, were elevated compared to non-ventilated infected controls: IL-1α (159 versus 4 pg/ml, p<0.01), IL-1ß (1068 versus 99 pg/ml, p<0.01), IL-6 (2343 versus 958 pg/ml, p<0.05) and MCP-1 (174 versus 26 pg/ml, p<0.05). CONCLUSIONS: Using pre- and post-intubation observations, this study suggests that endotracheal intubation and subsequent mechanical ventilation cause a robust pulmonary inflammation in infants with RSV bronchiolitis.

Decreased expression of serum and microvascular vascular endothelial growth factor receptor-2 in meningococcal sepsis*.

OBJECTIVES: To determine the skin microvessel expression of vascular endothelial growth factor receptor 2 and serum-soluble vascular endothelial growth factor receptor 2 levels in children with meningococcal sepsis. DESIGN: Observational study. SETTING: Two tertiary academic children hospital PICUs. PATIENTS: Children with meningococcal sepsis. INTERVENTION: Skin biopsy and blood sample collection. MEASUREMENTS AND MAIN RESULTS: Determination of skin microvessel vascular endothelial growth factor receptor 2 expression in skin biopsies by immunohistochemistry and measurement of serum-soluble vascular endothelial growth factor receptor 2 by enzyme-linked immunosorbent assay. Percentage of vascular endothelial growth factor receptor 2-positive skin microvessels and the staining intensity were significantly lower in children with meningococcal sepsis (n = 10) compared to controls (7.6% ± 8.8% vs 44.6% ± 39.2%; p = 0.009 and 0.7% ± 0.7% vs 1.7% ± 1.1%; p = 0.033, respectively). In addition, circulating serum levels of soluble vascular endothelial growth factor receptor 2 were decreased in sepsis (8,148 ± 1,140 pg/mL vs 13,414 ± 2,692 pg/mL; p < 0.001). Serum-soluble vascular endothelial growth factor receptor 2 levels (n = 28) were inversely correlated with Pediatric Risk of Mortality III score (r = -0.43; p = 0.023) and more decreased in nonsurvivors compared to survivors (5,640 ± 1,940 pg/mL vs 7,378 ± 2,336 pg/mL; p = 0.037). CONCLUSIONS: Microvascular expression of vascular endothelial growth factor receptor 2 and serum-soluble vascular endothelial growth factor receptor 2 levels are decreased in children with sepsis. Serum-soluble vascular endothelial growth factor receptor 2 levels are inversely correlated with disease severity indicated by Pediatric Risk of Mortality III score and survival. Decreased vascular endothelial growth factor receptor 2 expression may hinder natural recovery from sepsis-associated microvascular injury and the effectiveness of therapeutic strategies targeting vascular endothelial growth factor-vascular endothelial growth factor receptor 2 signaling in sepsis patients.

Dexamethasone attenuates VEGF expression and inflammation but not barrier dysfunction in a murine model of ventilator-induced lung injury.

BACKGROUND: Ventilator-induced lung injury (VILI) is characterized by vascular leakage and inflammatory responses eventually leading to pulmonary dysfunction. Vascular endothelial growth factor (VEGF) has been proposed to be involved in the pathogenesis of VILI. This study examines the inhibitory effect of dexamethasone on VEGF expression, inflammation and alveolar-capillary barrier dysfunction in an established murine model of VILI. METHODS: Healthy male C57Bl/6 mice were anesthetized, tracheotomized and mechanically ventilated for 5 hours with an inspiratory pressure of 10 cmH2O ("lower" tidal volumes of ∼7.5 ml/kg; LVT) or 18 cmH2O ("higher" tidal volumes of ∼15 ml/kg; HVT). Dexamethasone was intravenously administered at the initiation of HVT-ventilation. Non-ventilated mice served as controls. Study endpoints included VEGF and inflammatory mediator expression in lung tissue, neutrophil and protein levels in bronchoalveolar lavage fluid, PaO2 to FiO2 ratios and lung wet to dry ratios. RESULTS: Particularly HVT-ventilation led to alveolar-capillary barrier dysfunction as reflected by reduced PaO2 to FiO2 ratios, elevated alveolar protein levels and increased lung wet to dry ratios. Moreover, VILI was associated with enhanced VEGF production, inflammatory mediator expression and neutrophil infiltration. Dexamethasone treatment inhibited VEGF and pro-inflammatory response in lungs of HVT-ventilated mice, without improving alveolar-capillary permeability, gas exchange and pulmonary edema formation. CONCLUSIONS: Dexamethasone treatment completely abolishes ventilator-induced VEGF expression and inflammation. However, dexamethasone does not protect against alveolar-capillary barrier dysfunction in an established murine model of VILI.

Clinical pharmacy interventions in paediatric electronic prescriptions.

OBJECTIVE: To examine the frequency, nature and determinants of clinical pharmacy interventions in paediatric electronic prescriptions. DESIGN: Prospective cohort with nested case-control study. SETTING: Tertiary children's hospital, The Netherlands. PATIENTS: Patients 0-18 years with at least one drug prescription admitted to hospital between 1 March 2004 and 1 January 2008, excluding patients receiving intensive care. INTERVENTIONS: Electronic medication prescriptions for paediatric inpatients were verified and if necessary interventions were made by the paediatric clinical pharmacy. Prescriptions requiring intervention (cases) were compared with prescriptions not requiring interventions (controls). MAIN OUTCOME MEASURES: Frequency of clinical pharmacy interventions, per 10 000 paediatric electronic prescriptions, and the determinants thereof. RESULTS: Interventions were made for 1577 (1.1%) of 138 449 prescriptions. 81% of the interventions concerned correction of a prescription that might have had adverse clinical consequences. Interventions in prescriptions for antibacterial agents for systemic use were made most often. Most corrections concerned wrong doses (45%). 1577 cases were compared with 1983 controls. The risk of interventions was higher for children aged 1 month to 2 years than for 12-18-year-olds (OR=1.97 (95% CI 1.63 to 2.38)). The risk for 'free-text' prescriptions was five times higher than for 'standardised structured template' prescriptions. No differences were found between day, evening and night shift prescriptions. Significantly more interventions were made in the oral dosage form (OR=1.63 (95% CI 1.41 to 1.88)) and administration route (OR=1.80 (95% CI 1.55 to 2.09)) than for other reasons. CONCLUSIONS: Paediatric prescribing errors occur frequently and are not completely prevented by electronic prescribing systems. This study provides information for improvements in electronic prescribing for paediatric patients. Incorporating tailored solutions, such as minimised free-text entry, certain obligatory fields and integrated dose checking and indications, can improve the quality and efficiency of electronic prescribing in paediatrics.

Host response to mechanical ventilation for viral respiratory tract infection.

Respiratory syncytial virus (RSV) bronchiolitis causes severe respiratory tract infection in infants, frequently necessitating mechanical ventilatory support. However, life-saving, mechanical ventilation aggravates lung inflammation. We set up a model to dissect the host molecular response to mechanical ventilation in RSV infection. Furthermore, the response to induced hypercapnic acidosis, reported to dampen the inflammatory response to mechanical ventilation in non-infectious models, was assessed. BALB/c mice were inoculated with RSV or mock-suspension and ventilated for 5 h on day 5 post inoculation. Mechanical ventilation of infected mice resulted in enhanced cellular influx and increased concentrations of pro-inflammatory cytokines in the bronchoalveolar space. Microarray analysis showed that enhanced inflammation was associated with a molecular signature of a stress response to mechanical ventilation with little effect on the virus-induced innate immune response. Hypercapnic acidosis during mechanical ventilation of infected mice did not change host transcript profiles. We conclude that mechanical ventilation during RSV infection adds a robust but distinct molecular stress response to virus-induced innate immunity activation, emphasising the importance of lung-protective mechanical ventilation strategies. Induced hypercapnic acidosis has no major effect on host transcription profiles during mechanical ventilation for RSV infection, suggesting that this is a safe approach to minimise ventilator-induced lung injury.

FOXP3+ CD4+ Tregs lose suppressive potential but remain anergic during transient inflammation in human.

Tregs are crucial in controlling inflammation. Although the transcription factor FOXP3 is the most applicable phenotype marker of Tregs, it does not indisputably characterize suppressive function during T-cell activation in vitro. A question that remains is: what is the functionality of FOXP3(+) T cells during inflammation in vivo? We studied FOXP3(+) T cells in a human model of acute inflammation due to cardiac surgery. Twenty-five children who underwent cardiac surgery for correction of a septum defect were included. Following surgery, we observed a transient systemic inflammatory response accompanied by an increased proportion of CD25(bright) T cells with sustained Treg phenotype. During this transient immune activation, both the percentage of CD4(+) FOXP3(+) cells and the level of expression of FOXP3 in the CD4(+) CD25(bright) CD127(low) population increased. While Tregs remained present during systemic inflammation and continued to be anergic, the capacity to suppress effector T cells was reduced. The reduced suppressive state of Tregs could be induced in vitro by plasma obtained during the peak of inflammation after surgery. These data show that inflammation inhibits Treg function through soluble factors present in plasma. These results underscore the functional role of FOXP3(+) Tregs during inflammation in vivo.

Angiopoietin-1 treatment reduces inflammation but does not prevent ventilator-induced lung injury.

BACKGROUND: Loss of integrity of the epithelial and endothelial barriers is thought to be a prominent feature of ventilator-induced lung injury (VILI). Based on its function in vascular integrity, we hypothesize that the angiopoietin (Ang)-Tie2 system plays a role in the development of VILI. The present study was designed to examine the effects of mechanical ventilation on the Ang-Tie2 system in lung tissue. Moreover, we evaluated whether treatment with Ang-1, a Tie2 receptor agonist, protects against inflammation, vascular leakage and impaired gas exchange induced by mechanical ventilation. METHODS: Mice were anesthetized, tracheotomized and mechanically ventilated for 5 hours with either an inspiratory pressure of 10 cmH2O ('low' tidal volume ∼7.5 ml/kg; LVT) or 18 cmH2O ('high' tidal volume ∼15 ml/kg; HVT). At initiation of HVT-ventilation, recombinant human Ang-1 was intravenously administered (1 or 4 µg per animal). Non-ventilated mice served as controls. RESULTS: HVT-ventilation influenced the Ang-Tie2 system in lungs of healthy mice since Ang-1, Ang-2 and Tie2 mRNA were decreased. Treatment with Ang-1 increased Akt-phosphorylation indicating Tie2 signaling. Ang-1 treatment reduced infiltration of granulocytes and expression of keratinocyte-derived chemokine (KC), macrophage inflammatory protein (MIP)-2, monocyte chemotactic protein (MCP)-1 and interleukin (IL)-1ß caused by HVT-ventilation. Importantly, Ang-1 treatment did not prevent vascular leakage and impaired gas exchange in HVT-ventilated mice despite inhibition of inflammation, vascular endothelial growth factor (VEGF) and Ang-2 expression. CONCLUSIONS: Ang-1 treatment downregulates pulmonary inflammation, VEGF and Ang-2 expression but does not protect against vascular leakage and impaired gas exchange induced by HVT-ventilation.