Inflammatory Mediators in Tracheal Aspirates of Preterm Infants Participating in a Randomized Trial of Permissive Hypercapnia.

BACKGROUND: Ventilator-induced lung injury is considered to be a main factor in the pathogenesis of bronchopulmonary dysplasia (BPD). Optimizing ventilator strategies may reduce respiratory morbidities in preterm infants. Permissive hypercapnia has been suggested to attenuate lung injury. We aimed to determine if a higher PCO2 target range results in less lung injury compared to the control target range and possibly reduces pro-inflammatory cytokines and acid sphingomyelinase (ASM) in tracheal aspirates (TA), which has not been addressed before. METHODS: During a multicenter trial of permissive hypercapnia in extremely low birthweight infants (PHELBI), preterm infants (birthweight 400-1,000 g, gestational age 23 0/7-28 6/7 weeks) requiring mechanical ventilation within 24 h of birth were randomly assigned to a high PCO2 target or a control group. The high target group aimed at PCO2 values of 55-65, 60-70, and 65-75 mmHg and the control group at PCO2 values of 40-50, 45-55 and 50-60 mmHg on postnatal days 1-3, 4-6, and 7-14, respectively. TA was analyzed for pro-inflammatory cytokines from postnatal day 2-21. BPD was determined at a postmenstrual age of 36 weeks ± 2 days. MAIN FINDINGS: Levels of inflammatory cytokines and ASM were similar in both groups: interleukin (IL)-6 (p = 0.14), IL-8 (p = 0.43), IL-10 (p = 0.24), IL-1ß (p = 0.11), macrophage inflammatory protein 1α (p = 0.44), albumin (p = 0.41), neuropeptide Y (p = 0.52), leukotriene B4 (p = 0.11), transforming growth factor-ß1 (p = 0.68), nitrite (p = 0.15), and ASM (p = 0.94). Furthermore, most inflammatory mediators were strongly affected by the age of the infants and increased from postnatal day 2 to 21. BPD or death was observed in 14 out of 62 infants, who were distributed evenly between both groups. CONCLUSION: The results suggest that high PCO2 target levels did not result in lower pulmonary inflammatory activity and thus reflect clinical results. This indicates that high PCO2 target ranges are not effective in reducing ventilator-induced lung injury in preterm infants, as compared to control targets. TRIAL REGISTRATION: ISRCTN56143743.

Inflammatory Mediators in Tracheal Aspirates of Preterm Infants Participating in a Randomized Trial of Inhaled Nitric Oxide.

BACKGROUND: Ventilated preterm infants frequently develop bronchopulmonary dysplasia (BPD) which is associated with elevated inflammatory mediators in their tracheal aspirates (TA). In animal models of BPD, inhaled nitric oxide (iNO) has been shown to reduce lung inflammation, but data for human preterm infants is missing. METHODS: Within a European multicenter trial of NO inhalation for preterm infants to prevent BPD (EUNO), TA was collected to determine the effects of iNO on pulmonary inflammation. TA was collected from 43 premature infants randomly assigned to receive either iNO or placebo gas (birth weight 530-1230 g, median 800 g, gestational age 24 to 28 2/7 weeks, median 26 weeks). Interleukin (IL)-1ß, IL-6, IL-8, transforming growth factor (TGF)-ß1, interferon γ-induced protein 10 (IP-10), macrophage inflammatory protein (MIP)-1α, acid sphingomyelinase (ASM), neuropeptide Y and leukotriene B4 were measured in serial TA samples from postnatal day 2 to 14. Furthermore, TA levels of nitrotyrosine and nitrite were determined under iNO therapy. RESULTS: The TA levels of IP-10, IL-6, IL-8, MIP-1α, IL-1ß, ASM and albumin increased with advancing postnatal age in critically ill preterm infants, whereas nitrotyrosine TA levels declined in both, iNO-treated and placebo-treated infants. The iNO treatment generally increased nitrite TA levels, whereas nitrotyrosine TA levels were not affected by iNO treatment. Furthermore, iNO treatment transiently reduced early inflammatory and fibrotic markers associated with BPD development including TGF-ß1, IP-10 and IL-8, but induced a delayed increase of ASM TA levels. CONCLUSION: Treatment with iNO may have played a role in reducing several inflammatory and fibrotic mediators in TA of preterm infants compared to placebo-treated infants. However, survival without BPD was not affected in the main EUNO trial. TRIAL REGISTRATION: NCT00551642.

Non-specific immunological effects of selected routine childhood immunisations: systematic review.

OBJECTIVE:  To identify and characterise non-specific immunological effects after routine childhood vaccines against BCG, measles, diphtheria, pertussis, and tetanus. DESIGN:  Systematic review of randomised controlled trials, cohort studies, and case-control studies. DATA SOURCES:  Embase, PubMed, Cochrane library, and Trip searched between 1947 and January 2014. Publications submitted by a panel of experts in the specialty were also included. ELIGIBILITY CRITERIA FOR SELECTING STUDIES:  All human studies reporting non-specific immunological effects after vaccination with standard childhood immunisations. Studies using recombinant vaccines, no vaccine at all, or reporting only vaccine specific outcomes were excluded. The primary aim was to systematically identify, assemble, and review all available studies and data on the possible non-specific or heterologous immunological effects of BCG; measles; mumps, measles, and rubella (MMR); diphtheria; tetanus; and pertussis vaccines. RESULTS:  The initial search yielded 11 168 references; 77 manuscripts met the inclusion criteria for data analysis. In most included studies (48%) BCG was the vaccine intervention. The final time point of outcome measurement was primarily performed (70%) between one and 12 months after vaccination. There was a high risk of bias in the included studies, with no single study rated low risk across all assessment criteria. A total of 143 different immunological variables were reported, which, in conjunction with differences in measurement units and summary statistics, created a high number of combinations thus precluding any meta-analysis. Studies that compared BCG vaccinated with unvaccinated groups showed a trend towards increased IFN-γ production in vitro in the vaccinated groups. Increases were also observed for IFN-γ measured after BCG vaccination in response to in vitro stimulation with microbial antigens from Candida albicans, tetanus toxoid, Staphylococcus aureas, lipopolysaccharide, and hepatitis B. Cohort studies of measles vaccination showed an increase in lymphoproliferation to microbial antigens from tetanus toxoid and C albicans Increases in immunogenicity to heterologous antigens were noted after diphtheria-tetanus (herpes simplex virus and polio antibody titres) and diphtheria-tetanus-pertussis (pneumococcus serotype 14 and polio neutralising responses) vaccination. CONCLUSIONS:  The papers reporting non-specific immunological effects had heterogeneous study designs and could not be conventionally meta-analysed, providing a low level of evidence quality. Some studies, such as BCG vaccine studies examining in vitro IFN-γ responses and measles vaccine studies examining lymphoproliferation to microbial antigen stimulation, showed a consistent direction of effect suggestive of non-specific immunological effects. The quality of the evidence, however, does not provide confidence in the nature, magnitude, or timing of non-specific immunological effects after vaccination with BCG, diphtheria, pertussis, tetanus, or measles containing vaccines nor the clinical importance of the findings.

Impact of rotavirus vaccination in Germany: rotavirus surveillance, hospitalization, side effects and comparison of vaccines.

BACKGROUND: Although rotavirus (RV) vaccination was licensed in 2006, it was not included into the officially recommended German childhood vaccination schedule until 2013. Local differences in health policies in the past led to large differences in vaccination coverage rate among the federal states of Germany. This enables an ecologic study of RV vaccine effectiveness. METHODS: We performed a population-based retrospective analysis of RV vaccination use, RV notification and hospitalization among 0 to 5-year-old children in Germany during 2006 to 2011/2012. We compared effectiveness of the 2 RV vaccines, Rotateq and Rotarix, in an ambulatory setting and analyzed potential side effects. RESULTS: We observed a significant reduction in RV notifications since introduction of RV vaccination. In areas attaining vaccine coverage of 64%, RV-related hospital admissions of 0 and 1-year-old children decreased by 60% compared with 19% reduction in the low vaccination coverage area. Decrease in RV-related hospitalizations of 0 and 1-year-old children was specific and significantly associated with vaccination coverage of the individual federal state (P < 0.0001, r = -0.68). There was no overall increase in intussusception rate or Kawasaki disease-related hospital admissions since introduction of RV vaccination. The 2 licensed RV vaccines had similar effectiveness in the ambulatory setting. CONCLUSIONS: Postmarketing data suggest that RV vaccination is efficient in reducing RV-related hospitalizations. There is no apparent difference in effectiveness for Rotarix and Rotateq.

Interplay between nuclear factor erythroid 2-related factor 2 and amphiregulin during mechanical ventilation.

Mechanical ventilation (MV) elicits complex and clinically relevant cellular responses in the lungs. The current study was designed to define the role of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), a major regulator of the cellular antioxidant defense system, in the pulmonary response to MV. Nrf2 activity was quantified in ventilated isolated perfused mouse lungs (IPL). Regulation of amphiregulin (AREG) was investigated in BEAS-2B cells with inactivated Nrf2 or Keap1, the inhibitor of Nrf2, using a luciferase vector with AREG promoter. AREG-dependent Nrf2 activity was examined in BEAS-2B cells, murine precision-cut lung slices (PCLS), and IPL. Finally, Nrf2 knockout and wild-type mice were ventilated to investigate the interplay between Nrf2 and AREG during MV in vivo. Lung functions and inflammatory parameters were measured. Nrf2 was activated in a ventilation-dependent manner. The knockdown of Nrf2 and Keap1 via short hairpin RNA in BEAS-2B cells and an EMSA with lung tissue revealed that AREG is regulated by Nrf2. Conversely, AREG application induced a significant Nrf2 activation in BEAS-2B cells, PCLS, and IPL. The signal transduction of ventilation-induced Nrf2 activation was shown to be p38 MAP kinase-dependent. In vivo ventilation experiments indicated that AREG is regulated by Nrf2 during MV. We conclude that Areg expression is regulated by Nrf2. During high-pressure ventilation, Nrf2 becomes activated and induces AREG, leading to a positive feedback loop between Nrf2 and AREG, which involves the p38 MAPK and results in the expression of cytoprotective genes.

IKK NBD peptide inhibits LPS induced pulmonary inflammation and alters sphingolipid metabolism in a murine model.

Airway epithelial NF-κB is a key regulator of host defence in bacterial infections and has recently evolved as a target for therapeutical approaches. Evidence is accumulating that ceramide, generated by acid sphingomyelinase (aSMase), and sphingosine-1-phosphate (S1-P) are important mediators in host defence as well as in pathologic processes of acute lung injury. Little is known about the regulatory mechanisms of pulmonary sphingolipid metabolism in bacterial infections of the lung. The objective of this study was to evaluate the influence of NF-κB on sphingolipid metabolism in Pseudomonas aeruginosa LPS-induced pulmonary inflammation. In a murine acute lung injury model with intranasal Pseudomonas aeruginosa LPS we investigated TNF-α, KC (murine IL-8), IL-6, MCP-1 and neutrophilic infiltration next to aSMase activity and ceramide and S1-P lung tissue concentrations. Airway epithelial NF-κB was inhibited by topically applied IKK NBD, a cell penetrating NEMO binding peptide. This treatment resulted in significantly reduced inflammation and suppression of aSMase activity along with decreased ceramide and S1-P tissue concentrations down to levels observed in healthy animals. In conclusion our results confirm that changes in sphingolipid metabolim due to Pseudomonas aeruginosa LPS inhalation are regulated by NF-κB translocation. This confirms the critical role of airway epithelial NF-κB pathway for the inflammatory response to bacterial pathogens and underlines the impact of sphingolipids in inflammatory host defence mechanisms.

Models and mechanisms of acute lung injury caused by direct insults.

Acute lung injury (ALI) and its more severe form acute respiratory distress syndrome (ARDS) are life-threatening diseases that are characterized by acute onset, pulmonary inflammation, oedema due to increased vascular permeability and severe hypoxemia. Clinically, ARDS can be divided into ARDS due to direct causes such as pneumonia, aspiration or injurious ventilation, and due to extrapulmonary indirect causes such as sepsis, severe burns or pancreatitis. In order to identify potential therapeutic targets, we asked here whether common molecular mechanisms can be identified that are relevant in different models of the direct form of ALI/ARDS. To this end, we reviewed three widely used models: (a) one based on a biological insult, i.e. instillation of bacterial endotoxins; (b) one based on a chemical insult, i.e. instillation of acid; and (c) one based on a mechanical insult, i.e. injurious ventilation. Studies were included only if the mediator or mechanism of interest was studied in at least two of the three animal models listed above. As endpoints, we selected neutrophil sequestration, permeability, hypoxemia (physiological dysfunction) and survival. Our analysis showed that most studies have focused on mechanisms of pulmonary neutrophil sequestration and models with moderate forms of oedema. The underlying mechanisms that involve canonical inflammatory pathways such as MAP kinases, CXCR2 chemokines, PAF, leukotrienes, adhesions molecules (CD18, ICAM-1) and elastase have been defined relatively well. Further mechanisms including TNF, DARC, HMGB1, PARP, GADD45 and collagenase are under investigation. Such mechanisms that are shared between the three ALI models may represent viable therapeutic targets. However, only few studies have linked these pathways to hypoxemia, the most important clinical aspect of ALI/ARDS. Since moderate oedema does not necessarily lead to hypoxemia, we suggest that the clinical relevance of experimental studies can be further improved by putting greater emphasis on gas exchange.

Angiotensin II stimulates H⁺-ATPase activity in intercalated cells from isolated mouse connecting tubules and cortical collecting ducts.

Intercalated cells in the collecting duct system express V-type H(+)-ATPases which participate in acid extrusion, bicarbonate secretion, and chloride absorption depending on the specific subtype. The activity of H(+)-ATPases is regulated by acid-base status and several hormones, including angiotensin II and aldosterone. Angiotensin II stimulates chloride absorption mediated by pendrin in type B intercalated cells and this process is energized by the activity of H(+)-ATPases. Moreover, angiotensin II stimulates bicarbonate secretion by the connecting tubule (CNT) and early cortical collecting duct (CCD). In the present study we examined the effect of angiotensin II (10 nM) on H(+)-ATPase activity and localization in isolated mouse connecting tubules and cortical collecting ducts. Angiotensin II stimulated Na(+)-independent intracellular pH recovery about 2-3 fold, and this was abolished by the specific H(+)-ATPase inhibitor concanamycin. The effect of angiotensin II was mediated through type 1 angiotensin II receptors (AT(1)-receptors) because it could be blocked by saralasin. Stimulation of H(+)-ATPase activity required an intact microtubular network--it was completely inhibited by colchicine. Immunocytochemistry of isolated CNT/CCDs incubated in vitro with angiotensin II suggests enhanced membrane associated staining of H(+)-ATPases in pendrin expressing intercalated cells. In summary, angiotensin II stimulates H(+)-ATPases in CNT/CCD intercalated cells, and may contribute to the regulation of chloride absorption and bicarbonate secretion in this nephron segment.

Rotavirus vaccination in Germany: analysis of nationwide surveillance data 2006 to 2010.

BACKGROUND: Efficacy of rotavirus (RV) vaccination is difficult to assess outside of controlled clinical trials. In countries with low-to-moderate RV vaccination coverage, annual variation in RV outbreak might have a stronger influence on morbidity than RV vaccination. METHODS: We analyzed German RV surveillance data from 2006 to 2010 in the 16 federal states of Germany. To overcome the bias of annual variation of RV infections, we analyzed the effects of RV vaccination in Germany by comparing vaccination rate with morbidity as indicated by notification data. RESULTS: RV vaccination coverage in 0- to 1-year-old children in Germany increased from 3% in 2007 to 26% in 2010. The vaccination coverage varied highly between different federal states of Germany (2007, 1%-14%; 2008, 4%-35%, 2009, 8%-52%; and 2010, 17%-64%). There was a significant correlation between RV vaccination coverage and reduction in morbidity (r = -0.66, P = 0.0054) in 0- to <2-year-old children. The proportion of children vaccinated by one of the 2 vaccines, Rotarix and RotaTeq, was similar. Although we found a temporal delay of the epidemic RV seasons 2008 to 2010, those changes remained within the naturally occurring range. CONCLUSIONS: The overall RV vaccination coverage in Germany is still low as compared with other countries with vaccination-supporting policies. Initial data suggest an efficacy of the vaccination.

Ventilation-induced lung injury.

Mechanical ventilation (MV) is, by definition, the application of external forces to the lungs. Depending on their magnitude, these forces can cause a continuum of pathophysiological alterations ranging from the stimulation of inflammation to the disruption of cell-cell contacts and cell membranes. These side effects of MV are particularly relevant for patients with inhomogeneously injured lungs such as in acute lung injury (ALI). These patients require supraphysiological ventilation pressures to guarantee even the most modest gas exchange. In this situation, ventilation causes additional strain by overdistension of the yet non-injured region, and additional stress that forms because of the interdependence between intact and atelectatic areas. Cells are equipped with elaborate mechanotransduction machineries that respond to strain and stress by the activation of inflammation and repair mechanisms. Inflammation is the fundamental response of the host to external assaults, be they of mechanical or of microbial origin and can, if excessive, injure the parenchymal tissue leading to ALI. Here, we will discuss the forces generated by MV and how they may injure the lungs mechanically and through inflammation. We will give an overview of the mechanotransduction and how it leads to inflammation and review studies demonstrating that ventilator-induced lung injury can be prevented by blocking pathways of mechanotransduction or inflammation.

Dimenhydrinate in children with infectious gastroenteritis: a prospective, RCT.

OBJECTIVE: Vomiting is a common symptom in children with infectious gastroenteritis. It contributes to fluid loss and is a limiting factor for oral rehydration therapy. Dimenhydrinate has traditionally been used for children with gastroenteritis in countries such as Canada and Germany. We investigated the efficacy and safety of dimenhydrinate in children with acute gastroenteritis. METHODS: We performed a prospective, randomized, placebo-controlled, multicenter trial. We randomly assigned 243 children with presumed gastroenteritis and vomiting to rectal dimenhydrinate or placebo. Children with no or mild dehydration were included. All children received oral rehydration therapy. Primary outcome was defined as weight gain within 18 to 24 hours after randomization. Secondary outcomes were number of vomiting episodes, fluid intake, parents' assessment of well-being, number of diarrheal episodes, and admission rate to hospital. We recorded potential adverse effects. RESULTS: Change of weight did not differ between children who received dimenhydrinate or placebo. The mean number of vomiting episodes between randomization and follow-up visit was 0.64 in the dimenhydrinate group and 1.36 in the placebo group. In total, 69.6% of the children in the dimenhydrinate group versus 47.4% in the placebo group were free of vomiting between randomization and the follow-up visit. Hospital admission rate, fluid intake, general well-being of the children, and potential adverse effects, including the number of diarrhea episodes, were similar in both groups. CONCLUSIONS: Dimenhydrinate reduces the frequency of vomiting in children with mild dehydration; however, the overall benefit is low, because it does not improve oral rehydration and clinical outcome.

Antiemetic medications in children with presumed infectious gastroenteritis--pharmacoepidemiology in Europe and Northern America.

OBJECTIVE: To investigate the prescription pattern of antiemetic medications in 0- to 9-year-old children with infectious gastroenteritis in several industrialized countries during 2005. STUDY DESIGN: We retrospectively retrieved data from 4 national and international databases (IMS MIDAS, IMS disease analyzer, WIdO databases). RESULTS: Between 2% and 23% of children with gastroenteritis (International Classification of Diseases code A08.X or A09) received prescriptions for antiemetic medications (United States, 23%; 95% CI, 15-31; Germany, 17%; 95% CI, 15-20; France, 17%; 95% CI, 14-19; Spain, 15%; 95% CI, 10-19; Italy, 11%; 95% CI, 7-16; Canada, 3%; 95% CI, 0-16; United Kingdom, 2%; 95% CI, 1-2). The antihistamines dimenhydrinate and diphenhydramine were most frequently used in Germany and Canada, whereas promethazine was prescribed preferentially in the United States. In France, Spain, and Italy, the dopamine receptor antagonist domperidone was preferred as antiemetic treatment. Ondansetron was used in a minor proportion of antiemetic prescriptions (Germany, Canada, Spain, and Italy, 0%; United States, 3%; United Kingdom, 6%). CONCLUSION: Antiemetic drugs are frequently used in children with gastroenteritis. In different industrialized countries, prescription of antiemetic medication varies considerably. Ondansetron, the only drug with evidence-based antiemetic efficacy, plays a minor role among antiemetic prescriptions.

Pulmonary cytokine responses during mechanical ventilation of noninjured lungs with and without end-expiratory pressure.

BACKGROUND: Positive end-expiratory pressure (PEEP) during mechanical ventilation may impose different degrees of stress on healthy lungs. On the assumption that stress is reflected by cytokine production, we performed a translational study investigating the effect of PEEP on bronchoalveolar and systemic mediator levels in isolated perfused mouse lungs (IPL) and in patients with healthy lungs. METHODS: (Part I) IPL were ventilated with end-expiratory pressures of 0, 3, 6, or 10 cm H2O and end-inspiratory pressure (EIP) levels of 10 or 25 cm H2O. Interleukin (IL)-6 and macrophage inflammatory protein-2 concentrations in the venous effluate were monitored. (Part II) Patients (nonsmokers) scheduled for elective otorhinolaryngology surgery (duration>90 min) were randomized to receive either ventilation with zero end-expiratory pressure or PEEP (10 cm H2O). Mediators in bronchoalveolar lavage, nuclear factor kappaB, (NF-kappaB)-activation in alveolar macrophages and circulating systemic mediators were monitored. Control patients underwent bronchoalveolar lavage after intubation. RESULTS: In the IPL, mediator concentrations increased with increasing end-expiratory pressure at an EIP of 10 cm H2O, but decreased at 25 cm H2O EIP. In patients, bronchoalveolar IL-6, monocyte chemoattractant protein-1, and granulocyte monocyte-colony stimulating factor were increased by ventilation regardless of the PEEP level. IL-6 and IL-8 levels were moderately increased by PEEP but not zero end-expiratory pressure. Nuclear factor kappaB DNA binding activity in alveolar macrophages and systemic mediator levels did not change. CONCLUSIONS: On the basis of the premise that cytokine levels may indicate mechanical stress, our findings indicate that even low tidal volume ventilation causes some stress. PEEP is beneficial at high inspiratory pressure, but imposes moderate stress at low inspiratory pressure.

Improved pulmonary function by acid sphingomyelinase inhibition in a newborn piglet lavage model.

RATIONALE: In acute inflammatory lung disease in newborn infants, exogenous surfactant only transiently improves lung function. We hypothesized that the transient nature of this protection is in part explained by elevated acid sphingomyelinase (a-SMase) activity that may inactivate surfactant and promote proinflammatory responses. OBJECTIVES: We investigated the intermediate-term effects (>12 h) of a-SMase inhibition in a neonatal piglet model of repeated airway lavage by the intratracheal use of the a-SMase inhibitor imipramine, together with exogenous surfactant as a carrier substance. METHODS: After surfactant washout and induction of pulmonary inflammation, lung function was monitored over 24 hours of mechanical ventilation and followed by ex vivo analyses. In addition, we studied the effect of lipopolysaccharide inhalation in a-SMase-deficient mice at 48 hours. MEASUREMENTS AND MAIN RESULTS: Surfactant washout increased both pulmonary a-SMase activity and ceramide content; this was attenuated by surfactant and prevented in the surfactant plus imipramine group. Compared with surfactant alone, Pa(O(2)), dynamic compliance, and extravascular lung water were improved in the final 12 hours in the surfactant plus imipramine group. At 24 hours, lavage fluid leukocyte counts and IL-8 concentrations decreased, and physical surfactant film properties improved. In the mouse model at 48 hours, a-SMase-deficient mice showed reduced pulmonary ceramide levels and attenuated leukocyte influx into the alveolar space. CONCLUSIONS: We conclude that stabilization of exogenous surfactant by adding imipramine to create a "fortified surfactant preparation" improves lung function in a clinically relevant piglet model, and that this effect can be attributed to the inhibition of a-SMase as evidenced in the mouse model.

Surfactant "fortification" by topical inhibition of nuclear factor-kappaB activity in a newborn piglet lavage model.

OBJECTIVE: In acute respiratory distress syndrome of term newborn infants, surfactant replacement may be effective because endogenous surfactant is decreased and structurally changed. Inflammation is central to acute respiratory distress syndrome, and hence, attenuation of proinflammatory transcription factor nuclear factor (NF)-[kappa]B activation in the lung might prevent secondary loss of surfactant function. In this study, we tested the hypothesis that the topical use of a NF-[kappa]B inhibitor (I[kappa]B kinase-NF-[kappa]B essential modulator binding domain [IKK-NBD] peptide), together with surfactant as a carrier substance, improves surfactant function by attenuation of pulmonary inflammation during 24 hrs of mechanical ventilation in a neonatal piglet model of acute respiratory distress syndrome by repeated airway lavage. DESIGN: Prospective, randomized, controlled study. SETTING: Research laboratory of a university children's hospital. SUBJECTS: A total of 24 anesthetized, mechanically ventilated newborn piglets. INTERVENTIONS: After 20 +/- 6 (mean +/- sd) lavages to induce lung failure and inflammation, a porcine surfactant (100 mg/kg) with (S+IKK) or without (S) 1.25 mg of IKK-NBD peptide, or an air bolus (control) was administered into the airways. Lung function was monitored throughout 24 hrs of mechanical ventilation and completed by ex vivo analyses. MEASUREMENTS AND MAIN RESULTS: Pao2 (S+IKK, 125 +/- 16 mm Hg; S, 105 +/- 33; control, 61 +/- 20), ventilation efficiency index, functional residual capacity, compliance of the respiratory system, and extravascular lung water (S+IKK, 24 +/- 2 mL/kg; S, 30 +/- 7; control, 34 +/- 8) were all significantly improved in S+IKK piglets after 24 hrs. Decreased leukocyte concentrations in bronchoalveolar lavage (S+IKK, 152 +/- 94 cells/microL; S, 202 +/- 100; control, 276 +/- 57) were observed together with reduced acid sphingomyelinase activity, lowered ceramide concentrations, improved surfactant function (minimum surface tension: S+IKK, 10.8 +/- 6.1 mN/m; S, 13.2 +/- 3.9; control, 20.9 +/- 8.5), and decreased NF-[kappa]B activation in lung tissue. CONCLUSION: Supplementation of exogenous surfactant with a NF-[kappa]B inhibitor to create a "fortified" surfactant improves gas exchange, lung function, and pulmonary edema during 24 hrs of mechanical ventilation, without a secondary functional relapse. Inhibition of NF-[kappa]B suppressed acid sphingomyelinase activity and ceramide generation, indicating a novel proinflammatory link of NF-[kappa]B.

Disparate innate immune responses to persistent and acute Chlamydia pneumoniae infection in chronic obstructive pulmonary disease.

RATIONALE: Chlamydia pneumoniae (Cpn) infection may play a role in the pathogenesis of chronic obstructive pulmonary disease (COPD). Few data are available comparing persistent and acute infection of this pathogen in the human respiratory tract. OBJECTIVES: To study Cpn-induced innate immune responses in lung tissue from patients with COPD and control subjects ex vivo and in vitro. METHODS: Cpn detection was done by nested polymerase chain reaction, in situ hybridization, and immunohistochemistry ex vivo in unstimulated tissue and in vitro using an acute Cpn infection model. As main endpoints for the assessment of early cellular responses, nuclear factor (NF)-kappaB activation and CXC chemokine ligand (CXCL)-8 expression were evaluated. The role of Toll-like receptors (TLRs) as recognition molecules in Cpn-induced innate responses was tested by blocking experiments. MEASUREMENTS AND MAIN RESULTS: Fifteen percent of patients with COPD were chronically infected with Cpn in contrast to 0% of control subjects (p < 0.05). There were no differences in CXCL-8 and NF-kappaB expression between infected and noninfected COPD tissue ex vivo. In contrast, acute in vitro infection induced an intense innate immune response including up-regulation of TLR2. Blocking experiments demonstrated the predominant role of TLR2 in induction of the early immune response, whereas no influence on chlamydial infection rates was observed. CONCLUSIONS: Acute in vitro infection of human lung tissue with Cpn elicited a marked innate response via TLR2, whereas chronic chlamydial infection in patients with COPD was not associated with enhanced cellular activation. These findings suggest different roles of Cpn during acute and chronic stages of pulmonary infection.

Pulmonary responses to overventilation in late multiple organ failure.

BACKGROUND: Patients with multiple organ failure (MOF) require mechanical ventilation for several days. The enormous significance of the ventilation strategy for the outcome of these patients is well appreciated. However, most studies have focused on the onset and the early phase of MOF. It was the aim of the current study to investigate the effect of ventilation in the course of MOF. METHODS: Using a model where mice develop MOF 7-14 days after intraperitoneal injection of zymosan, the authors analyzed lung functions, signaling pathways, and mediator release in response to protective ventilation (end-expiratory pressure -3 cm H2O; end-inspiratory pressure -10 cm H2O) and overventilation (-22.5 cm H2O) in isolated lungs ex vivo. RESULTS: On day 7, pulmonary compliance, pulmonary resistance, and tidal volume were normal, but vascular resistance was elevated compared with untreated animals. During ex vivo ventilation, these lungs showed enhanced nuclear factor-kappaB activation, Akt kinase phosphorylation, and cytokine release, and this was further aggravated by overventilation. After 14 days, zymosan-treated animals were characterized by pulmonary hypertension, reduced tidal volume, elevated pulmonary resistance, and increased mediator production. However, in these lungs, neither nuclear factor-kappaB activation nor cytokine production where enhanced by overventilation. CONCLUSIONS: The zymosan model is characterized by pulmonary inflammation, diminished lung functions, and chronic hypertension. Mechanical ventilation with high distending pressures further augmented cytokine production in this chronic model of MOF only if it significantly augmented tidal volume. The authors speculate that these findings may be explained on the basis of different degrees of lung stretch.

Mechanical ventilation strategies and inflammatory responses to cardiac surgery: a prospective randomized clinical trial.

OBJECTIVE: To examine whether postoperative mechanical ventilation with lower tidal volumes (V(T)) has protective effects on inflammatory responses induced by cardiopulmonary bypass (CPB) surgery in smokers and nonsmokers. DESIGN AND SETTING: Prospective, randomized, controlled clinical trial in the intensive care unit of a university hospital. PATIENTS AND PARTICIPANTS: We examined 44 patients (22 smokers, 22 nonsmokers) immediately after uncomplicated CPB surgery. INTERVENTIONS: Ventilation was applied for 6 h with either V(T) of either 6 or 12 ml/kg ideal body weight. MEASUREMENTS AND RESULTS: The time course of serum tumor necrosis factor (TNF) alpha, interleukin (IL) 6, and IL-8 determined 0, 2, 4, and 6 h after randomization did not differ significantly between the ventilatory strategies. By contrast, in bronchoalveolar lavage fluids sampled after 6 h only TNF-alpha levels were significantly higher in the high V(T) group than the low V(T) group (50+/-111 pg/ml vs. 1+/-7 pg/ml). IL-6 and IL-8 concentrations did not differ between groups. Subgroup analysis of patients with serum TNF-alpha level higher than 0 pg/ml after surgery revealed lower TNF-alpha serum levels during lower V(T) ventilation. All observed effects were small, independent of patients' history of smoking, and were not correlated with duration of ventilation and ICU stay. CONCLUSIONS: Ventilation with lower V(T) had no or only minor effect on systemic and pulmonary inflammatory responses in patients with healthy lungs after uncomplicated CPB surgery. Our data do not suggest a clinical benefit of using low V(T) ventilation in these selected patients.

Ceramide alters endothelial cell permeability by a nonapoptotic mechanism.

Ceramide is a lipid second messenger that was recently identified as mediator of pulmonary edema in vivo. Here, we investigated the effect of ceramide on the permeability of confluent endothelial cell monolayers. In monolayers of bovine pulmonary artery and human microvascular pulmonary endothelial cells, incubation with C6-ceramide for 3 h elevated permeability in a concentration-dependent manner, whereas dihydroceramide was without effect. After 3 h of incubation with ceramide, we found no signs of necrosis (release of lactate dehydrogenase, loss of thiazylyl blue reduction) or apoptosis (ssDNA, caspase-8 activity). The increased endothelial permeability in response to ceramide was attenuated by the Ser/Thr protein kinase inhibitors K252a, K252b and H-7, as well as by the phosphatidylinositol-specific phospholipase C inhibitor L108. Since in some systems sphingosine-1-phosphate (S1P) acts antagonistic to ceramide, the effect of S1P was studied. S1P transiently increased endothelial cell resistance, whether it was given together with ceramide or 90 min thereafter. These data provide a novel example of the antagonism between S1P and ceramide. Our findings further suggest that ceramide alters vascular permeability by activation of pathways dependent on unidentified phospholipase C and Ser/Thr kinase isoenzymes.

Pharmacological interventions in ventilator-induced lung injury.

During mechanical ventilation the lungs are exposed to substantial physical forces. This is particularly true for patients with acute lung injury, where the applied pressures are two to three times higher than those present during normal breathing. The resultant overdistension activates specific mechanotransduction pathways, many of which activate inflammation pathways that might lead to (further) acute lung injury. In this article, we review evidence suggesting that pharmacological strategies can interfere with ventilator-induced lung injury at different stages of the inflammatory cascade: blockade of transcription factors, neutralization of chemokines, cytokines and neuropeptides, and inhibition of proteases. These findings provide rationale for the use of anti-inflammatory therapies to treat the side-effects of mechanical ventilation.