Validity of markers of dilution in small volume lung lavage

The alveolar fibroproliferative response in moderate to severe COVID-19-related acute respiratory distress syndrome and 1-yr follow-up

COVID-19-related acute respiratory distress syndrome (ARDS) can lead to long-term pulmonary fibrotic lesions. Alveolar fibroproliferative response (FPR) is a key factor in the development of pulmonary fibrosis. N-terminal peptide of procollagen III (NT-PCP-III) is a validated biomarker for activated FPR in ARDS. This study aimed to assess the association between dynamic changes in alveolar FPR and long-term outcomes, as well as mortality in COVID-19 ARDS patients. We conducted a prospective cohort study of 154 COVID-19 ARDS patients. We collected bronchoalveolar lavage (BAL) and blood samples for measurement of 17 pulmonary fibrosis biomarkers, including NT-PCP-III. We assessed pulmonary function and chest computed tomography (CT) at 3 and 12 mo after hospital discharge. We performed joint modeling to assess the association between longitudinal changes in biomarker levels and mortality at day 90 after starting mechanical ventilation. 154 patients with 284 BAL samples were analyzed. Of all patients, 40% survived to day 90, of whom 54 completed the follow-up procedure. A longitudinal increase in NT-PCP-III was associated with increased mortality (HR 2.89, 95% CI: 2.55-3.28; P < 0.001). Forced vital capacity and diffusion for carbon monoxide were impaired at 3 mo but improved significantly at one year after hospital discharge (P = 0.03 and P = 0.004, respectively). There was no strong evidence linking alveolar FPR during hospitalization and signs of pulmonary fibrosis in pulmonary function or chest CT images during 1-yr follow-up. In COVID-19 ARDS patients, alveolar FPR during hospitalization was associated with higher mortality but not with the presence of long-term fibrotic lung sequelae within survivors.NEW & NOTEWORTHY This is the first prospective study on the longitudinal alveolar fibroproliferative response in COVID-19 ARDS and its relationship with mortality and long-term follow-up. We used the largest cohort of COVID-19 ARDS patients who had consecutive bronchoalveolar lavages and measured 17 pulmonary fibroproliferative biomarkers. We found that a higher fibroproliferative response during admission was associated with increased mortality, but not correlated with long-term fibrotic lung sequelae in survivors.

Persistent alveolar inflammatory response in critically ill patients with COVID-19 is associated with mortality

INTRODUCTION

Patients with COVID-19-related acute respiratory distress syndrome (ARDS) show limited systemic hyperinflammation, but immunomodulatory treatments are effective. Little is known about the inflammatory response in the lungs and if this could be targeted using high-dose steroids (HDS). We aimed to characterise the alveolar immune response in patients with COVID-19-related ARDS, to determine its association with mortality, and to explore the association between HDS treatment and the alveolar immune response.

METHODS

In this observational cohort study, a comprehensive panel of 63 biomarkers was measured in repeated bronchoalveolar lavage (BAL) fluid and plasma samples of patients with COVID-19 ARDS. Differences in alveolar-plasma concentrations were determined to characterise the alveolar inflammatory response. Joint modelling was performed to assess the longitudinal changes in alveolar biomarker concentrations, and the association between changes in alveolar biomarker concentrations and mortality. Changes in alveolar biomarker concentrations were compared between HDS-treated and matched untreated patients.

RESULTS

284 BAL fluid and paired plasma samples of 154 patients with COVID-19 were analysed. 13 biomarkers indicative of innate immune activation showed alveolar rather than systemic inflammation. A longitudinal increase in the alveolar concentration of several innate immune markers, including CC motif ligand (CCL)20 and CXC motif ligand (CXCL)1, was associated with increased mortality. Treatment with HDS was associated with a subsequent decrease in alveolar CCL20 and CXCL1 levels.

CONCLUSIONS

Patients with COVID-19-related ARDS showed an alveolar inflammatory state related to the innate host response, which was associated with a higher mortality. HDS treatment was associated with decreasing alveolar concentrations of CCL20 and CXCL1.

Alveolar Biomarker Profiles in Subphenotypes of the Acute Respiratory Distress Syndrome

OBJECTIVES

We sought to determine whether hyperinflammatory acute respiratory distress syndrome (ARDS) and hypoinflammatory ARDS, which have been associated with differences in plasma biomarkers and mortality risk, also display differences in bronchoalveolar lavage (BALF) biomarker profiles. We then described the relationship between hyperinflammatory ARDS and hypoinflammatory ARDS to novel subphenotypes derived using BALF biomarkers.

DESIGN

Secondary analysis of a randomized control trial testing omega-3 fatty acids for the treatment of ARDS.

SETTING

Five North American intensive care units.

PATIENTS

Adults (n = 88) on invasive mechanical ventilation within 48 hours of ARDS onset.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We classified 57 patients as hypoinflammatory and 31 patients as hyperinflammatory using a previously validated logistic regression model. Of 14 BALF biomarkers analyzed, interleukin-6 and granulocyte colony stimulating factor were higher among patients with hyperinflammatory ARDS compared with hypoinflammatory ARDS, though the differences were not robust to multiple hypothesis testing. We then performed a de novo latent class analysis of the 14 BALF biomarkers to identify two classes well separated by alveolar profiles. Class 2 (n = 63) displayed significantly higher interleukin-6, von Willebrand factor, soluble programmed cell death receptor-1, % neutrophils, and other biomarkers of inflammation compared with class 1 (n = 25). These BALF-derived classes had minimal overlap with the plasma-derived hyperinflammatory and hypoinflammatory classes, and the majority of both plasma-derived classes were in BALF-derived class 2 and characterized by high BALF biomarkers. Additionally, the BALF-derived classes were associated with clinical severity of pulmonary disease, with class 2 exhibiting lower Pao2 to Fio2 and distinct ventilatory parameters, unlike the plasma-derived classes, which were only related to nonpulmonary organ dysfunction.

CONCLUSIONS

Hyperinflammatory and hypoinflammatory ARDS subphenotypes did not display significant differences in alveolar biologic profiles. Identifying ARDS subgroups using BALF measurements is a unique approach that complements information obtained from plasma, with potential to inform enrichment strategies in trials of lung-targeted therapies.

Chorioamnionitis alters lung surfactant lipidome in newborns with respiratory distress syndrome

BACKGROUND

Chorioamnionitis is associated with preterm delivery and morbidities; its role in lung disease is controversial. The aim of this study is to assess the effect of chorioamnionitis on metabolite and lipid profiles of epithelial lining fluid in preterm newborns with respiratory distress syndrome (RDS).

METHODS

The study involved 30 newborns with RDS, born from mothers with or without histological chorioamnionitis (HCA): HCA+, N = 10; HCA-, N = 20. Patients had a gestational age ≤30 weeks; the groups were matched for age and birth weights. Tracheal aspirates were collected within 24 h after birth and analyzed using liquid chromatography/mass spectrometry-based untargeted lipidomics.

RESULTS

According to Mann-Whitney U tests, 570 metabolite features had statistically significantly higher or lower concentrations (p < 0.05) in tracheal aspirates of HCA+ compared to HCA-, and 241 metabolite features were putatively annotated and classified. The most relevant changes involved higher levels of glycerophospholipids (fold change 2.42-17.69) and sphingolipids, with lower concentration of all annotated sphingomyelins in HCA+ (fold change 0.01-0.50).

CONCLUSIONS

Untargeted lipidomics of tracheal aspirates suggested the production of lipid mediators in the context of an ongoing inflammatory status in HCA+ babies. However, the effect of chorioamnionitis on epithelial lining fluid composition deserves further investigations on a larger group of infants.

IMPACT

Our lipidomics investigation on tracheal aspirates of preterm newborns at birth suggested that exposure to maternal histological chorioamnionitis may cause changes in epithelial lining fluid composition. This is the first description of epithelial lining fluid lipidomic profiles in preterm infants with and without exposition to chorioamnionitis. These results could provide novel link between placental membrane inflammation and newborns' respiratory outcome.

Simulated biological fluids - a systematic review of their biological relevance and use in relation to inhalation toxicology of particles and fibres

The use of simulated biological fluids (SBFs) is a promising in vitro technique to better understand the release mechanisms and possible in vivo behaviour of materials, including fibres, metal-containing particles and nanomaterials. Applications of SBFs in dissolution tests allow a measure of material biopersistence or, conversely, bioaccessibility that in turn can provide a useful inference of a materials biodistribution, its acute and long-term toxicity, as well as its pathogenicity. Given the wide range of SBFs reported in the literature, a review was conducted, with a focus on fluids used to replicate environments that may be encountered upon material inhalation, including extracellular and intracellular compartments. The review aims to identify when a fluid design can replicate realistic biological conditions, demonstrate operation validation, and/or provide robustness and reproducibility. The studies examined highlight simulated lung fluids (SLFs) that have been shown to suitably replicate physiological conditions, and identify specific components that play a pivotal role in dissolution mechanisms and biological activity; including organic molecules, redox-active species and chelating agents. Material dissolution was not always driven by pH, and likewise not only driven by SLF composition; specific materials and formulations correspond to specific dissolution mechanisms. It is recommended that SLF developments focus on biological predictivity and if not practical, on better biological mimicry, as such an approach ensures results are more likely to reflect in vivo behaviour regardless of the material under investigation.

Alveolar compartmentalization of inflammatory and immune cell biomarkers in pneumonia-related ARDS

Background

Biomarkers of disease severity might help individualizing the management of patients with the acute respiratory distress syndrome (ARDS). Whether the alveolar compartmentalization of biomarkers has a clinical significance in patients with pneumonia-related ARDS is unknown. This study aimed at assessing the interrelation of ARDS/sepsis biomarkers in the alveolar and blood compartments and explored their association with clinical outcomes.

Methods

Immunocompetent patients with pneumonia-related ARDS admitted between 2014 and 2018 were included in a prospective monocentric study. Bronchoalveolar lavage (BAL) fluid and blood samples were obtained within 48 h of admission. Twenty-two biomarkers were quantified in BAL fluid and serum. HLA-DR⁺ monocytes and CD8⁺ PD-1⁺ lymphocytes were quantified using flow cytometry. The primary clinical endpoint of the study was hospital mortality. Patients undergoing a bronchoscopy as part of routine care were included as controls.

Results

Seventy ARDS patients were included. Hospital mortality was 21.4%. The BAL fluid-to-serum ratio of IL-8 was 20 times higher in ARDS patients than in controls (p < 0.0001). ARDS patients with shock had lower BAL fluid-to-serum ratio of IL-1Ra (p = 0.026), IL-6 (p = 0.002), IP-10/CXCL10 (p = 0.024) and IL-10 (p = 0.023) than others. The BAL fluid-to-serum ratio of IL-1Ra was more elevated in hospital survivors than decedents (p = 0.006), even after adjusting for SOFA and driving pressure (p = 0.036). There was no significant association between alveolar or alveolar/blood monocytic HLA-DR or CD8⁺ lymphocytes PD-1 expression and hospital mortality.

Conclusions

IL-8 was the most compartmentalized cytokine and lower BAL fluid-to-serum concentration ratios of IL-1Ra were associated with hospital mortality in patients with pneumonia-associated ARDS.

Local complement activation is associated with primary graft dysfunction after lung transplantation

BACKGROUND

The complement system plays a key role in host defense but is activated by ischemia/reperfusion injury (IRI). Primary graft dysfunction (PGD) is a form of acute lung injury occurring predominantly due to IRI, which worsens survival after lung transplantation (LTx). Local complement activation is associated with acute lung injury, but whether it is more reflective of allograft injury compared with systemic activation remains unclear. We proposed that local complement activation would help identify those who develop PGD after LTx. We also aimed to identify which complement activation pathways are associated with PGD.

METHODS

We performed a multicenter cohort study at the University of Pennsylvania and Washington University School of Medicine. Bronchoalveolar lavage (BAL) and plasma specimens were obtained from recipients within 24 hours after LTx. PGD was scored based on the consensus definition. Complement activation products and components of each arm of the complement cascade were measured using ELISA.

RESULTS

In both cohorts, sC4d and sC5b-9 levels were increased in BAL of subjects with PGD compared with those without PGD. Subjects with PGD also had higher C1q, C2, C4, and C4b, compared with subjects without PGD, suggesting classical and lectin pathway involvement. Ba levels were higher in subjects with PGD, suggesting alternative pathway activation. Among lectin pathway–specific components, MBL and FCN-3 had a moderate-to-strong correlation with the terminal complement complex in the BAL but not in the plasma.

CONCLUSION

Complement activation fragments are detected in the BAL within 24 hours after LTx. Components of all 3 pathways are locally increased in subjects with PGD. Our findings create a precedent for investigating complement-targeted therapeutics to mitigate PGD.

FUNDING

This research was supported by the NIH, American Lung Association, Children’s Discovery Institute, Robert Wood Johnson Foundation, Cystic Fibrosis Foundation, Barnes-Jewish Hospital Foundation, Danish Heart Foundation, Danish Research Foundation of Independent Research, Svend Andersen Research Foundation, and Novo Nordisk Research Foundation.

Substantial differences between local and systemic complement activation in lung transplant recipients who develop primary graft dysfunction are identified in two independent cohorts.

Aspiration and Inspiration: Using Bronchoalveolar Lavage for Toxicity Assessment

Bronchoalveolar lavage (BAL) is a simple procedure that is used to investigate drug efficacy or lung toxicity. It is sensitive to lung changes and less invasive than histological evaluation. It can be performed repeatedly at interim time points or as a terminal procedure. Airborne contaminants and purposely inhaled compounds, resident and inflammatory cells, as well as different cellular soluble products can be harvested in bronchoalveolar fluid (BALF) and measured. Bronchoalveolar lavage can also be an important tool to understand drug exposure and its metabolism in the lung, although it should be rigorously performed and interpreted with caution, especially in the context of regulated toxicology studies. This review focuses on the methods and uses of BAL in animal research, primarily in the pharmaceutical industry, as well as for the assessment of drugs, pollutants, and chemical lung toxicity. Methods of collecting and analyzing BALF and parameters affecting variability are discussed in detail. Improved automated methods for cell counting and analysis of the inflammatory cellular differential using hematology analyzers, common markers of lung injury, and new methodologies are described. Correlation between BALF and histological evaluation should not be considered as repetitive but as complementary assessments in the context of efficacy and toxicity studies.

Increased Hematopoietic Extracellular RNAs and Vesicles in the Lung during Allergic Airway Responses

Extracellular RNAs (exRNAs) can be released by numerous cell types in vitro, are often protected within vesicles, and can modify recipient cell function. To determine how the composition and cellular sources of exRNAs and the extracellular vesicles (EVs) that carry them change in vivo during tissue inflammation, we analyzed bronchoalveolar lavage fluid (BALF) from mice before and after lung allergen challenge. In the lung, extracellular microRNAs (ex-miRNAs) had a composition that was highly correlated with airway-lining epithelium. Using cell type-specific membrane tagging and single vesicle flow, we also found that 80% of detected vesicles were of epithelial origin. After the induction of allergic airway inflammation, miRNAs selectively expressed by immune cells, including miR-223 and miR-142a, increased and hematopoietic-cell-derived EVs also increased >2-fold. These data demonstrate that infiltrating immune cells release ex-miRNAs and EVs in inflamed tissues to alter the local extracellular environment.

Intrapulmonary concentrations of meropenem administered by continuous infusion in critically ill patients with nosocomial pneumonia: a randomized pharmacokinetic trial

Background

Optimal antimicrobial drug exposure in the lung is required for successful treatment outcomes for nosocomial pneumonia. Little is known about the intrapulmonary pharmacokinetics (PK) of meropenem when administered by continuous infusion (CI). The aim of this study was to evaluate the PK of two dosages of meropenem (3 g vs 6 g/day by CI) in the plasma and epithelial lining fluid (ELF) in critically ill patients with nosocomial pneumonia.

Methods

Thirty-one patients (81% male, median (IQR) age 72 (22) years) were enrolled in a prospective, randomized, clinical trial. Sixteen patients received 1 g/8 h and 15 2 g/8 h by CI (8 h infusion). Plasma and ELF meropenem concentrations were modeled using a population methodology, and Monte Carlo simulations were performed to estimate the probability of attaining (PTA) a free ELF concentration of 50% of time above MIC (50% fT>MIC), which results in logarithmic killing and the suppression of resistance in experimental models of pneumonia.

Results

The median (IQR) of meropenem AUC_0–24 h in the plasma and ELF was 287.6 (190.2) and 84.1 (78.8) mg h/L in the 1 g/8 h group vs 448.1 (231.8) and 163.0 (201.8) mg h/L in the 2 g/8 h group, respectively. The penetration ratio was approximately 30% and was comparable between the dosage groups. In the Monte Carlo simulations, only the highest approved dose of meropenem of 2 g/8 h by CI allowed to achieve an optimal PTA for all isolates with a MIC < 4 mg/L.

Conclusions

An increase in the dose of meropenem administered by CI achieved a higher exposure in the plasma and ELF. The use of the highest licensed dose of 6 g/day may be necessary to achieve an optimal coverage in ELF for all susceptible isolates (MIC ≤ 2 mg/L) in patients with conserved renal function. An alternative therapy should be considered when the presence of microorganisms with a MIC greater than 2 mg/L is suspected.

Trial registration

The trial was registered in the European Union Drug Regulating Authorities Clinical Trials Database (EudraCT-no. 2016-002796-10). Registered on 27 December 2016.

Randomized, Double-Blind, Placebo-Controlled, Single-Ascending-Dose Study of the Penetration of a Monoclonal Antibody Combination (ASN100) Targeting Staphylococcus aureus Cytotoxins in the Lung Epithelial Lining Fluid of Healthy Volunteers

ASN100 is a novel antibody combination of two fully human IgG1(κ) monoclonal antibodies (MAbs), ASN-1 and ASN-2, which neutralize six Staphylococcus aureus cytotoxins, alpha-hemolysin (Hla) and five bicomponent leukocidins. We assessed the safety, tolerability, and serum and lung pharmacokinetics of ASN100 in a randomized, double-blind, placebo-controlled single-dose-escalation first-in-human study.

ASN100 is a novel antibody combination of two fully human IgG1(κ) monoclonal antibodies (MAbs), ASN-1 and ASN-2, which neutralize six Staphylococcus aureus cytotoxins, alpha-hemolysin (Hla) and five bicomponent leukocidins. We assessed the safety, tolerability, and serum and lung pharmacokinetics of ASN100 in a randomized, double-blind, placebo-controlled single-dose-escalation first-in-human study. Fifty-two healthy volunteers were enrolled and randomized to receive either ASN-1, ASN-2, a combination of both MAbs (ASN100), or a corresponding placebo. Thirty-two subjects in the double-blind dose escalation portion of the study received ASN-1 or ASN-2 at a 200-, 600-, 1,800-, or 4,000-mg dose, or placebo. Eight subjects received both MAbs simultaneously in a 1:1 ratio (ASN100) at 3,600 or 8,000 mg, or they received placebos. Twelve additional subjects received open-label ASN100 at 3,600 or 8,000 mg to assess the pharmacokinetics of ASN-1 and ASN-2 in epithelial lining fluid (ELF) by bronchoalveolar lavage fluid sampling. Subjects were monitored for 98 days (double-blind cohorts) or 30 days (open-label cohorts) for safety assessment. No dose-limiting toxicities were observed, and all adverse events were mild and transient, with only two adverse events considered possibly related to the investigational product. ASN100 exhibited linear serum pharmacokinetics with a half-life of approximately 3 weeks and showed detectable penetration into the ELF. No treatment-emergent anti-drug antibody responses were detected. The toxin neutralizing potency of ASN100 in human serum was confirmed up to 58 days postdosing. The favorable safety profile, ELF penetration, and maintained functional activity in serum supported the further clinical development of ASN100.

Comparison of piperacillin exposure in the lungs of critically ill patients and healthy volunteers

Background

Severe infections of the respiratory tracts of critically ill patients are common and associated with excess morbidity and mortality. Piperacillin is commonly used to treat pulmonary infections in critically ill patients. Adequate antibiotic concentration in the epithelial lining fluid (ELF) of the lung is essential for successful treatment of pulmonary infection.

Objectives

To compare piperacillin pharmacokinetics/pharmacodynamics in the serum and ELF of healthy volunteers and critically ill patients.

Methods

Piperacillin concentrations in the serum and ELF of healthy volunteers and critically ill patients were compared using population methodologies.

Results

Median piperacillin exposure was significantly higher in the serum and the ELF of critically ill patients compared with healthy volunteers. The IQR for serum piperacillin exposure in critically ill patients was six times greater than for healthy volunteers. The IQR for piperacillin exposure in the ELF of critically ill patients was four times greater than for healthy volunteers. The median pulmonary piperacillin penetration ratio was 0.31 in healthy volunteers and 0.54 in critically ill patients.

Conclusions

Greater variability in serum and ELF piperacillin concentrations is observed in critically ill patients compared with healthy adult subjects and must be considered in the development of dosage regimens. Pulmonary penetration of antimicrobial agents should be studied in critically ill patients, as well as healthy volunteers, during drug development to ensure appropriate dosing of patients with pneumonia.

Preventing lung pathology and mortality in rabbit Staphylococcus aureus pneumonia models with cytotoxin-neutralizing monoclonal IgGs penetrating the epithelial lining fluid

Staphylococcus aureus pneumonia is associated with high mortality irrespective of antibiotic susceptibility. Both MRSA and MSSA strains produce powerful cytotoxins: alpha-hemolysin(Hla) and up to five leukocidins - LukSF-PV, HlgAB, HlgCB, LukED and LukGH (LukAB) - to evade host innate defense mechanisms. Neutralizing cytotoxins has been shown to provide survival benefit in rabbit S. aureus pneumonia models. We studied the mechanisms of protection of ASN100, a combination of two human monoclonal antibodies (mAbs), ASN-1 and ASN-2, that together neutralize Hla and the five leukocidins, in rabbit MRSA and MSSA pneumonia models. Upon prophylactic passive immunization, ASN100 displayed dose-dependent increase in survival and was fully protective against all S. aureus strains tested at 5 or 20 mg/kg doses. Macroscopic and microscopic lung pathology, edema rate, and bacterial burden were evaluated 12 hours post infection and reduced by ASN100. Pharmacokinetic analysis of ASN100 in bronchoalveolar-lavage fluid from uninfected animals detected efficient penetration to lung epithelial lining fluid reaching peak levels between 24 and 48 hours post dosing that were comparable to the mAb concentration measured in serum. These data confirm that the ASN100 mAbs neutralize the powerful cytotoxins of S. aureus in the lung and prevent damage to the mucosal barrier and innate immune cells.

Effect of age on the pharmacokinetics and distribution of tulathromycin in interstitial and pulmonary epithelial lining fluid in healthy calves

OBJECTIVE To compare the plasma pharmacokinetics of tulathromycin between 3-week-old (preweaned) and 6-month-old (weaned) calves and to characterize the distribution of tulathromcyin into pulmonary epithelial lining fluid (PELF) and interstitial fluid (ISF) of preweaned and weaned calves following SC administration of a single dose (2.5 mg/kg). ANIMALS 8 healthy 3-week-old and 8 healthy 6-month-old Holstein steers. PROCEDURES A jugular catheter and SC ultrafiltration probe were aseptically placed in the neck of each calf before tulathromycin administration. Blood, ISF, and bronchoalveolar lavage fluid samples were collected at predetermined times before and after tulathromycin administration for quantification of drug concentration. A urea dilution method was used to estimate tulathromycin concentration in PELF from that in bronchoalveolar lavage fluid. Tulathromycin-plasma protein binding was determined by in vitro methods. Plasma pharmacokinetics were determined by a 2-compartment model. Pharmacokinetic parameters and drug concentrations were compared between preweaned and weaned calves. RESULTS Clearance and volume of distribution per fraction of tulathromycin absorbed were significantly greater for weaned calves than preweaned calves. Tulathromycin-plasma protein binding was significantly greater for weaned calves than preweaned calves. Maximum PELF tulathromycin concentration was significantly greater than the maximum plasma and maximum ISF tulathromycin concentrations in both groups. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that age affected multiple pharmacokinetic parameters of tulathromycin, likely owing to physiologic changes as calves mature from preruminants to ruminants. Knowledge of those changes may be useful in the development of studies to evaluate potential dose adjustments during treatment of calves with respiratory tract disease.

Surfactant Components and Tracheal Aspirate Inflammatory Markers in Preterm Infants with Respiratory Distress Syndrome

In 93 preterm infants ≤32 weeks of gestational age and 12 control infants, epithelial lining fluid disaturated-phosphatidylcholine, surfactant protein A and B, albumin, and myeloperoxidase activity were assessed after intubation and before exogenous surfactant administration. We found that disaturated-phosphatidylcholine, surfactant protein B, and myeloperoxidase were significantly higher in preterms with chorioamnionitis.

Gene Expression Signatures Point to a Male Sex-Specific Lung Mesenchymal Cell PDGF Receptor Signaling Defect in Infants Developing Bronchopulmonary Dysplasia

Male sex is a risk factor for development of bronchopulmonary dysplasia (BPD), a common chronic lung disease following preterm birth. We previously found that tracheal aspirate mesenchymal stromal cells (MSCs) from premature infants developing BPD show reduced expression of PDGFRα, which is required for normal lung development. We hypothesized that MSCs from male infants developing BPD exhibit a pathologic gene expression profile deficient in PDGFR and its downstream effectors, thereby favoring delayed lung development. In a discovery cohort of 6 male and 7 female premature infants, we analyzed the tracheal aspirate MSCs transcriptome. A unique gene signature distinguished MSCs from male infants developing BPD from all other MSCs. Genes involved in lung development, PDGF signaling and extracellular matrix remodeling were differentially expressed. We sought to confirm these findings in a second cohort of 13 male and 12 female premature infants. mRNA expression of PDGFRA, FGF7, WNT2, SPRY1, MMP3 and FOXF2 were significantly lower in MSCs from male infants developing BPD. In female infants developing BPD, tracheal aspirate levels of proinflammatory CCL2 and profibrotic Galectin-1 were higher compared to male infants developing BPD and female not developing BPD. Our findings support a notion for sex-specific differences in the mechanisms of BPD development.

Increased Levels of IGF-1 and Beta2-Microglobulin in Epithelial Lining Fluid of Preterm Newborns Developing Chronic Lung Disease: Effects of rhG-CSF

Insulin-like growth factor-1 (IGF-1) is involved in regulating the TH-l/TH-2 balance, favoring the development of the TH-2 compartment which enhances fibrosis, one of the main characteristics of Chronic Lung Disease (CLD) in premature newborns. Limited data is available concerning a possible association between early epithelial lining fluid (ELF) concentrations of IGF-1 (total and free forms), IGF-binding protein-3 (IGFBP-3), b2-microglobulin (B2M) and subsequent development of CLD in preterm neonates. If neutropenic, preterm neonates are frequently treated with recombinant human Granulocyte Colony Stimulating Factor (rhG-CSF). The objective of the study was to correlate ELF concentrations of IGF-1 and B2M during the first week of life both in non-neutropenic and in rhG-CSF-treated neutropenic preterm neonates, with subsequent development in CLD. Thirty preterm neonates with Respiratory Distress Syndrome (6 with neutropenia) were studied. Eleven out of 24 non-neutropenic preterm infants (46%) and all of the six neutropenic subjects (100%) developed CLD. With the exception of first day values, there was a clear similarity in the behaviors of assayed molecules between non-neutropenic and neutropenic patients developing CLD. Non-neutropenic patients without CLD showed significantly lower values of free IGF-1 and B2M both on days 1 and 3. Total IGF-I and cell counts were different only on the 3rd day. Conclusions: 1) the mechanisms leading to CLD might be mediated by high levels of IGF-family molecules soon after birth 2) B2M could be a marker of increased bronchoalveolar lavage fluid cellularity with potential inflammatory properties 3) G-CSF treatment induces an increased synthesis of IGF-1 molecules by cells recruited in the lung, with possible enhancement of the fibrogenic mechanisms.

Unique Lipid Signatures of Extracellular Vesicles from the Airways of Asthmatics

Asthma is a chronic inflammatory disease process involving the conductive airways of the human lung. The dysregulated inflammatory response in this disease process may involve multiple cell-cell interactions mediated by signaling molecules, including lipid mediators. Extracellular vesicles (EVs) are lipid membrane particles that are now recognized as critical mediators of cell-cell communication. Here, we compared the lipid composition and presence of specific lipid mediators in airway EVs purified from the bronchoalveolar lavage (BAL) fluid of healthy controls and asthmatic subjects with and without second-hand smoke (SHS) exposure. Airway exosome concentrations were increased in asthmatics, and correlated with blood eosinophilia and serum IgE levels. Frequencies of HLA-DR⁺ and CD54⁺ exosomes were also significantly higher in asthmatics. Lipidomics analysis revealed that phosphatidylglycerol, ceramide-phosphates, and ceramides were significantly reduced in exosomes from asthmatics compared to the non-exposed control groups. Sphingomyelin 34:1 was more abundant in exosomes of SHS-exposed asthmatics compared to healthy controls. Our results suggest that chronic airway inflammation may be driven by alterations in the composition of lipid mediators within airway EVs of human subjects with asthma.

Bronchopulmonary pharmacokinetics of (R)-salbutamol and (S)-salbutamol enantiomers in pulmonary epithelial lining fluid and lung tissue of horses

AIMS

Salbutamol is usually administered as a racemic mixture but little is known about the enantioselectivity of salbutamol pharmacokinetics in the lung. This study was designed to investigate enantiomer concentrations in lung tissue after inhaled dosing.

METHODS

Horses (n = 12) received racemic salbutamol 1000 μg via inhalation. Enantioselective ultra performance liquid chromatography-tandem mass spectrometry was used to determine salbutamol concentrations in pulmonary epithelial lining fluid (PELF) sampled 2, 5, 10 and 15 min after administration, in central lung (endoscopic bronchial biopsy) and peripheral lung (percutaneous pulmonary biopsy) tissues (at 20 and 25 min respectively), and in plasma samples.

RESULTS

Mean ± 95% confidence interval (CI) yield of PELF was 57 ± 10 mg. Initial mean ± 95%CI (R)- and (S)-salbutamol PELF concentrations were 389 ± 189 ng g^-1 and 378 ± 177 ng g^-1 respectively, and both reduced approximately 50% by 15 min. Mean ± 95%CI central lung levels of drug were higher than peripheral lung tissue for both (R)-salbutamol (875 ± 945 vs. 49.5 ± 12 ng g^-1 ) and (S)-salbutamol (877 ± 955 vs. 50.9 ± 12 ng g^-1 ) respectively. There was no evidence of enantioselectivity in PELF or central lung but minor (~2%) enantioselectivity was observed in the peripheral lung. Enantioselectivity was clearly evident in plasma with (S):(R) ratio of 1.25 and 1.14 for both area under the concentration-time curve (0-25 min) and C_max respectively.

CONCLUSIONS

PELF sampling in horses offers sufficient yield allowing direct detection of drug and, combined with tissue sampling, is a valuable model to investigate bronchopulmonary pharmacokinetics. Salbutamol did not demonstrate enantioselectivity in PELF or central lung tissue uptake following acute dosing, however, enantioselective plasma concentrations were demonstrated, with minor enantioselectivity in the peripheral lung.

The Relationship Between Airway Antioxidant Levels, Alcohol Use Disorders, and Cigarette Smoking

BACKGROUND

Alcohol use disorders (AUDs) and cigarette smoking are associated with pulmonary oxidative stress, likely related to antioxidant depletion. Pulmonary oxidative stress may adversely affect innate immunity, leading to increased pneumonia susceptibility and severity, including development of the acute respiratory distress syndrome. In people with AUDs, most of whom smoke, antioxidant therapy can potentially restore immune cell function and attenuate pneumonia development. Challenges to human investigations of antioxidant therapies include an inability to identify pulmonary oxidative stress noninvasively and the optimal route to deliver pulmonary antioxidants. We sought to determine whether bronchoalveolar lavage (BAL) measures of thiol antioxidants from a 50-ml upper airway aliquot approximated those in the alveolar space and to determine whether AUDs and/or smoking affected these relationships.

METHODS

Healthy human subjects with and without AUDs, including smokers and nonsmokers, underwent BAL. Samples obtained after the first 50-ml normal saline aliquot were analyzed as representing bronchial airways; subsequent 50-ml aliquots were analyzed as representative of the alveolar space. Reduced and oxidized (GSSG) glutathione, cysteine (Cys), and its oxidized species, cystine, along with mixed disulfides (MDs) were quantified using high-performance liquid chromatography. The percent of total thiols present in their oxidized forms, and thiol redox potentials, were calculated.

RESULTS

Positive correlations between upper and lower BAL fluid thiol species were observed that were most robust for GSSG (ρ = 0.85), Cys (ρ = 0.83), and MDs (ρ = 0.69), but poor for thiol redox potential measures. In contrast to nonsmokers (either with or without AUDs), in subjects with AUDs who smoked, upper BAL fluid %GSSG, Cys, and MD measures were relatively increased compared to lower.

CONCLUSIONS

A small volume BAL procedure may be suitable to assess intrapulmonary oxidative stress related to thiol depletion. Factors including AUDs and smoking may disproportionately increase upper airways oxidative stress that could be relevant for therapeutic interventions.

Tracheal Aspirate Levels of the Matricellular Protein SPARC Predict Development of Bronchopulmonary Dysplasia

Background

Isolation of tracheal aspirate mesenchymal stromal cells (MSCs) from premature infants has been associated with increased risk of bronchopulmonary dysplasia (BPD). MSCs show high levels of mRNAs encoding matricellular proteins, non-structural extracellular proteins that regulate cell-matrix interactions and participate in tissue remodeling. We hypothesized that lung matricellular protein expression predicts BPD development.

Methods

We collected tracheal aspirates and MSCs from mechanically-ventilated premature infants during the first week of life. Tracheal aspirate and MSC-conditioned media were analyzed for seven matricellular proteins including SPARC (for Secreted Protein, Acidic, Rich in Cysteine, also called osteonectin) and normalized to secretory component of IgA. A multiple logistic regression model was used to determine whether tracheal aspirate matricellular protein levels were independent predictors of BPD or death, controlling for gestational age (GA) and birth weight (BW).

Results

We collected aspirates from 89 babies (38 developed BPD, 16 died before 36 wks post-conceptual age). MSC-conditioned media showed no differences in matricellular protein abundance between cells from patients developing BPD and cells from patients who did not. However, SPARC levels were higher in tracheal aspirates from babies with an outcome of BPD or death (p<0.01). Further, our logistic model showed that tracheal aspirate SPARC (p<0.02) was an independent predictor of BPD/death. SPARC deposition was increased in the lungs of patients with BPD.

Conclusions

In mechanically-ventilated premature infants, tracheal aspirate SPARC levels predicted development of BPD or death. Further study is needed to determine the value of SPARC as a biomarker or therapeutic target in BPD.

A pharmacometric pulmonary model predicting the extent and rate of distribution from plasma to epithelial lining fluid and alveolar cells--using rifampicin as an example

Purpose

The purpose of the study was to develop a drug-unspecific approach to pharmacometric modeling for predicting the rate and extent of distribution from plasma to epithelial lining fluid (ELF) and alveolar cells (AC) for data emanating from studies involving bronchoalveolar lavage (BAL) sampling, using rifampicin (RIF) as an example.

Methods

Data consisting of RIF plasma concentrations sampled at approximately 2 and 4 h postdose and ELF and AC concentrations quantified from one BAL sample, taken at approximately 4 h postdose, in 40 adult subjects without tuberculosis was used as an example for model development.

Results

This study emphasized the usage of drug-specific plasma pharmacokinetics (PK) for a correct characterization of plasma to pulmonary distribution. As such, RIF PK was described using absorption transit compartments and a one compartment distribution model coupled with an enzyme turn-over model. The ELF and AC distribution model consisted of characterization of the rate of distribution of drug from plasma to ELF and AC by two distribution rate constant, k_ELF and k_AC, respectively. The extent of distribution to ELF and AC was described by unbound ELF/plasma concentration ratio (R_{ELF/unbound-plasma}) and unbound AC/plasma concentration ratio (R_{AC/unbound-plasma}) which typical values were predicted to be 1.28 and 5.5, respectively.

Conclusions

The model together with a drug-specific plasma PK description provides a tool for handling data from both single and multiple BAL sampling designs and directly predicts the rate and extent of distribution from plasma to ELF and AC. The model can be further used to investigate design aspects of optimized BAL studies.

Surfactant protein B and A concentrations are increased in neonatal pneumonia

BACKGROUND

Term newborns with pneumonia show a reduced pulmonary compliance due to multiple and ill-defined factors. Surfactant proteins' (SPs) changes could have a role in the reduced compliance but the matter is still unsettled. The aim of this study was to clarify the meaning of SPs changes during pneumonia in term newborns.

METHODS

In 28 term ventilated newborns, 13 with pneumonia and 15 with no lung disease, we measured SP-B, SP-A, disaturated-phosphatidylcholine (DSPC), and total phospholipids (PL) concentrations in tracheal aspirates at intubation and close to extubation. We also measured DSPC kinetics using (U-(13)C-PA)dipalmitoyl-phosphatidylcholine.

RESULTS

At baseline, SP-B, expressed as % of PL, was significantly different between the groups, being 3.5-fold higher in pneumonia than controls. Conversely, SP-A did not vary between the groups. At extubation, SP-B and SP-A concentrations had decreased significantly in newborns with pneumonia, while there was no significant change in controls. DSPC t1/2 was significantly shorter in the pneumonia group (11.8 (5.5-19.8) h vs. 26.6 (19.3-63.6) h, P = 0.011).

CONCLUSION

In term newborns with pneumonia, SP-B increases with respect to PL, and DSPC is turned over at a faster rate. Disease's resolution is associated with the restoration of the normal ratio between SP-B and PL.

In vivo effect of pneumonia on surfactant disaturated-phosphatidylcholine kinetics in newborn infants

Background

Bacterial pneumonia in newborns often leads to surfactant deficiency or dysfunction, as surfactant is inactivated or its production/turnover impaired. No data are available in vivo in humans on the mechanism of surfactant depletion in neonatal pneumonia. We studied the kinetics of surfactant's major component, disaturated-phosphatidylcholine (DSPC), in neonatal pneumonia, and we compared our findings with those obtained from control newborn lungs.

Methods

We studied thirty-one term or near-term newborns (gestational age 39.7±1.7 weeks, birth weight 3185±529 g) requiring mechanical ventilation. Fifteen newborns had pneumonia, while 16 newborns were on mechanical ventilation but had no lung disease. Infants received an intratracheal dose of ¹³C labeled dipalmitoyl-phosphatidylcholine at the study start. We measured the amount and the isotopic enrichment of DSPC-palmitate from serial tracheal aspirates by gas chromatography and gas chromatography-mass spectrometry, respectively, and we calculated the DSPC half-life (HL) and pool size (PS) from the isotopic enrichment curves of surfactant DSPC-palmitate.

Results

The mean DSPC amount obtained from all tracheal aspirates did not differ between the two groups. DSPC HL was 12.7 (6.5–20.2) h and 25.6 (17.9–60.6) h in infants with pneumonia compared with control infants (p = 0.003). DSPC PS was 14.1 (6.6–30.9) mg/kg in infants with pneumonia and 34.1 (25.6–65.0) mg/kg in controls, p = 0.042. Myeloperoxidase (MPO) activity, as a marker of lung inflammation, was 1322 (531–2821) mU/ml of Epithelial Lining Fluid (ELF) and 371(174–1080) mU/ml ELF in infants with pneumonia and in controls, p = 0.047. In infants with pneumonia, DSPC PS and HL significantly and inversely correlated with mean Oxygenation Index (OI) during the study (DSPC PS vs. OI R = −0.710, p = 0.004 and HL vs. OI R = −0.525, p = 0.044, respectively).

Conclusions

We demonstrated for the first time in vivo in humans that DSPC HL and PS were markedly impaired in neonatal pneumonia and that they inversely correlated with the degree of respiratory failure.

Pulmonary penetration of piperacillin and tazobactam in critically ill patients

Pulmonary infections in critically ill patients are common and are associated with high morbidity and mortality. Piperacillin–tazobactam is a frequently used therapy in critically ill patients with pulmonary infection. Antibiotic concentrations in the lung reflect target‐site antibiotic concentrations in patients with pneumonia. The aim of this study was to assess the plasma and intrapulmonary pharmacokinetics (PK) of piperacillin–tazobactam in critically ill patients administered standard piperacillin–tazobactam regimens. A population PK model was developed to describe plasma and intrapulmonary piperacillin and tazobactam concentrations. The probability of piperacillin exposures reaching pharmacodynamic end points and the impact of pulmonary permeability on piperacillin and tazobactam pulmonary penetration was explored. The median piperacillin and tazobactam pulmonary penetration ratios were 49.3 and 121.2%, respectively. Pulmonary piperacillin and tazobactam concentrations were unpredictable and negatively correlated with pulmonary permeability. Current piperacillin–tazobactam regimens may be insufficient to treat pneumonia caused by piperacillin–tazobactam–susceptible organisms in some critically ill patients.

Clinical Pharmacology & Therapeutics (2014); 96 4, 438–448. doi:10.1038/clpt.2014.131

DNA and inflammatory mediators in bronchoalveolar lavage fluid from children with acute inhalational injuries

The aim of this study was to assess the feasibility of using serial bronchoalveolar lavage fluids (BALFs) to characterize the course of cell damage and inflammation in the airways of pediatric patients with acute burn or inhalation injury. This was a prospective, longitudinal, descriptive pilot study conducted at the Burn and Pediatric Intensive Care Units in a tertiary care medical center. Six consecutively intubated and mechanically ventilated pediatric patients with acute inhalational injuries were studied. Serial BALF specimens from clinically indicated bronchoscopies were used to measure DNA and cytokine levels. BALF DNA levels for the six pediatric burn subjects were the highest within the first 72 hours after burn injury and declined thereafter. At the early stages after injury, BALF DNA levels (median [min, max] 3789 [1170, 11,917] ng/ml) were similar to those in adult burn patients and pediatric cystic fibrosis or bronchiectasis patients and was higher than those in pediatric recurrent pneumonia patients. BALF DNA levels in children and adults with inhalation injury correlated significantly with BALF interleukin-6, interleukin-8, and transforming growth factor-β1 levels. The patient with the most severe early visible airway mucosal damage and soot pattern at bronchoscopy, as well as the most extensive burns, also had the highest average early BALF DNA level (11,917 ng/ml) and the longest ventilator course and hospital stay. Procedures were well tolerated. In children with acute burn and inhalational injury, airway cellular damage and inflammation (reflected in high BALF DNA levels) appear to peak during the first 72 hours after burn or inhalation injury followed by a slow decline. Serial analysis of factors in airway secretions is feasible and has the potential to reveal important pathophyisiologic pathways and therapeutic targets for the treatment of acute inhalational injuries.

Airway angiopoietin-2 in ventilated very preterm infants: association with prenatal factors and neonatal outcome

OBJECTIVE

Pulmonary angiogenesis is a prerequisite for lung development. Angiopoietin-2 (Ang2) destabilizes endothelial cells through its endothelial receptor TIE-2, enabling vascular sprouting. Ang1 stabilizes new blood vessels. Soluble TIE-2 (sTIE-2) modulates these effects. We hypothesized that histological funisitis is associated with alterations of Ang2 in airways and of the systemic angiopoietin-TIE-2 homeostasis in very low birth weight (VLBW) infants, contributing to pulmonary morbidity and mortality.

METHODS

We measured Ang2 in tracheobronchial aspirate fluid (TAF) of 42 VLBW <30 weeks of gestation from day 1 through 15 and Ang1, Ang2, and sTIE-2 in umbilical cord serum of 28 infants by enzyme-linked immunosorbent assay. Histological examination distinguished three groups: funisitis, chorioamnionitis, and controls.

RESULTS

Funisitis was associated with lower Ang2 values in TAF but not with changes of Ang1, Ang2, and sTIE-2 in umbilical cord serum. Infants who developed bronchopulmonary dysplasia (BPD) or died had a persistently decreased ratio of previously measured Ang1 to Ang2 in TAF on days 1-5 and increased cord serum concentrations of sTIE-2. Moderate BPD/death was associated with an increase of Ang2 in TAF on day 10 and decreased Ang1/Ang2 ratio from day 3-15. Small for gestational age (SGA) infants had increased Ang2 in TAF on day 1-7 and a lower Ang1/Ang2 ratio on days 5-7.

CONCLUSIONS

The predominance of Ang2 in airway fluid of infants with BPD/death and SGA infants suggests a link between disrupted placental and fetal pulmonary angiogenesis. Histological funisitis with reduced Ang2 in TAF was of minor relevance for outcome in our cohort.

Quantification of amikacin in bronchial epithelial lining fluid in neonates

Amikacin efficacy is based on peak concentrations and the possibility of reaching therapeutic levels at the infection site. This study aimed to describe amikacin concentrations in the epithelial lining fluid (ELF) through bronchoalveolar lavage (BAL) in newborns. BAL fluid was collected in ventilated neonates treated with intravenous (i.v.) amikacin. Clinical characteristics, amikacin therapeutic drug monitoring serum concentrations, and the concentrations of urea in plasma were extracted from the individual patient files. Amikacin and urea BAL fluid concentrations were determined using liquid chromatography with pulsed electrochemical detection (LC-PED) and capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D), respectively. ELF amikacin concentrations were converted from BAL fluid concentrations through quantification of dilution (urea in plasma/urea in BAL fluid) during the BAL procedure. Twenty-two observations in 17 neonates (postmenstrual age, 31.9 [range, 25.1 to 41] weeks; postnatal age, 3.5 [range, 2 to 37] days) were collected. Median trough and peak amikacin serum concentrations were 2.1 (range, 1 to 7.1) mg/liter and 39.1 (range, 24.1 to 73.2) mg/liter; the median urea plasma concentration was 30 (8 to 90) mg/dl. The median amikacin concentration in ELF was 6.5 mg/liter, the minimum measured concentration was 1.5 mg/liter, and the maximum (peak) was 23 mg/liter. The highest measured ELF concentration was reached between 6 and 14.5 h after i.v. amikacin administration, and an estimated terminal elimination half-life was 8 to 10 h. The median and highest (peak) ELF amikacin concentrations observed in our study population were, respectively, 6.5 and 23 mg/liter. Despite the frequent use of amikacin in neonatal (pulmonary) infections, this is the first report of amikacin quantification in ELF in newborns.

Disaturated-phosphatidylcholine and surfactant protein-B turnover in human acute lung injury and in control patients

Background

Patients with Adult Respiratory Distress Syndrome (ARDS) and Acute Lung Injury (ALI) have low concentrations of disaturated-phosphatidylcholine and surfactant protein-B in bronchoalveolar lavage fluid. No information is available on their turnover.

Objectives

To analyze disaturated-phosphatidylcholine and surfactant protein-B turnover in patients with ARDS/ALI and in human adults with normal lungs (controls).

Methods

²H₂O as precursor of disaturated-phosphatidylcholine-palmitate and 1¹³C-Leucine as precursor of surfactant protein-B were administered intravenously to 12 patients with ARDS/ALI and to 8 controls. Disaturated-phosphatidylcholine and surfactant protein-B were isolated from serial tracheal aspirates, and their fractional synthetic rate was derived from the ²H and ¹³C enrichment curves, obtained by gas chromatography mass spectrometry. Disaturated-phosphatidylcholine, surfactant protein-B, and protein concentrations in tracheal aspirates were also measured.

Results

1) Surfactant protein-B turned over at faster rate than disaturated-phosphatidylcholine both in ARDS/ALI patients and in controls. 2) In patients with ARDS/ALI the fractional synthesis rate of disaturated-phosphatidylcholine was 3.1 times higher than in controls (p < 0.01), while the fractional synthesis rate of surfactant protein-B was not different. 3) In ARDS/ALI patients the concentrations of disaturated-phosphatidylcholine and surfactant protein-B in tracheal aspirates were markedly and significantly reduced (17% and 40% of the control values respectively).

Conclusions

1) Disaturated-phosphatidylcholine and surfactant protein-B have a different turnover both in healthy and diseased lungs. 2) In ARDS/ALI the synthesis of these two surfactant components may be differently regulated.

Ureia como marcador de diluição em amostras de lavado traqueobrônquico de potros com rodococose

No estudo das infecções e dos mecanismos inflamatórios do trato respiratório posterior, a diluição desconhecida de amostras de lavados traqueobrônquicos leva a um grave problema na interpretação das concentrações de várias substâncias. Foi investigada a amplitude da diluição em uma situação clínica verdadeira, com o objetivo de determinar a validez do uso da dosagem da ureia em lavados traqueobrônquicos para correção da diluição. As amostras do estudo consistiram em lavados traqueobrônquicos obtidos de sete potros com infecção por Rhodococcus equi. Foi realizada a contagem celular total e diferencial e comprado com o quadro clínico e a recuperação bacteriana de todas as amostras. Os fatores de diluição dos lavados variaram entre 14,3 e 130 (média 59,7). O uso da ureia como marcador de diluição melhorou a exatidão na determinação da concentração total de células nos lavados. Estes resultados sugerem que a prática de mensurar substâncias em lavado traqueobrônquico sem correção da diluição possa induzir a falsas conclusões.

Correlation of levels of alpha-defensins determined by HPLC-ESI-MS in bronchoalveolar lavage fluid with the diagnosis of pneumonia in premature neonates

The presence of alpha-defensins in bronchoalveolar lavage fluid (BALF) was investigated in a cohort of preterm newborns with gestational age (GA) < or =30 wk. Specimens were collected during the first week of life from 24 preterm neonates mechanically ventilated. The studied population was divided into two groups: pneumonia group of nine neonates suffering from pulmonary infection (GA: 26.1 +/- 2.1 wk; birth weight: 787.4 +/- 309.9 g), with or without associated bloodstream infection, and nonpneumonia group of 15 neonates (GA: 27.7 +/- 2.0 wk; birth weight: 1019.0 +/- 319.8 g). BALF culture was positive for CONS (n = 5), Staphylococcus aureus (n = 1), and Candida spp (n = 3). BALF samples were analyzed by HPLC-electrospray Ionization-mass spectrometer. The alpha-defensins 1-4 concentration, absolute and differential white cells count were measured. Relative amounts of alpha-defensins 1-4 and the absolute number of neutrophils were found significantly higher in the pneumonia group with respect to the nonpneumonia group (p < 0.05). Moreover, positive significant correlations between the number of neutrophils and the alpha-defensins 1-3 levels were observed. In conclusion, our data show that preterm newborns, also at the lower GA, are able to produce alpha-defensins, underlining that their innate defense system is already active before the at-term delivery date.

Evaluation of biomarkers in bronchoalveolar lavage fluid for discrimination between asthma and chronic bronchitis in cats

OBJECTIVE

To compare concentrations of interleukin (IL)-4, interferon (IFN)-gamma, tumor necrosis factor (TNF)-alpha and total nitric oxide (NO) metabolites in bronchoalveolar lavage fluid (BALF) for discrimination between asthma and chronic bronchitis in cats.

ANIMALS

97 cats.

PROCEDURES

Cats screened with cytologic examination of BALF included 13 client-owned cats with naturally developing asthma, 8 client-owned cats with chronic bronchitis, 23 research cats with experimentally induced asthma, 33 research cats with experimentally induced nonseptic suppurative inflammation of the airways, and 20 healthy control cats. Banked unconcentrated BALF supernatant samples were assayed for concentrations of IL-4, IFN-gamma, TNF-alpha, and total NO metabolites.

RESULTS

Concentrations of IL-4 and IFN-gamma in BALF were less than the limits of detection for most cats, precluding statistical analysis. No significant differences were detected among groups for TNF-alpha concentrations. Concentrations of total NO metabolites were significantly higher in cats with clinical chronic bronchitis, compared with research cats with nonseptic suppurative inflammation or research cats with asthma.

CONCLUSIONS AND CLINICAL RELEVANCE

There were no significant differences in tested biomarkers between cats with asthma and healthy control cats. None of the measured cytokines or NO metabolites were useful for discriminating between cats with naturally developing asthma and those with chronic bronchitis.

Cellular and cytokine changes in the alveolar environment among immunocompromised patients during Pneumocystis jirovecii infection

Limited data exist on the cytokine and cellular changes in the alveolar environment in immunocompromised patients during Pneumocystis jirovecii infection. A cellular and a cytokine analysis were performed on bronchoalveolar lavage (BAL) samples from three groups of patients, i.e., an initial study group of 64 immunocompromised P. jirovecii-positive individuals and two control groups of P. jirovecii-negative patients who had been or not immunosuppressed (65 patients). The results were related to alveolar dilution as determined by urea measurement. Compared with non-infected groups, P. jirovecii-infected patients had a lower level of alveolar macrophages (AM), particularly those with high burdens of P. jirovecii. Alveolar macrophages over-expressed the Dectin-1 receptor, which was largely implicated in P. jirovecii clearance. The alveolar CD8+T and CD4+T lymphocyte counts were increased and an inverse correlation was observed between the alveolar CD4+ cell count and the P. jirovecii burden. Although the alveolar IL-6 level was considerably increased, alveolar IL-17, IL-10, TNF-α, TGF-β concentrations of P. jirovecii patients were not different from the control groups. Changes in the pulmonary environment were also highlighted during P. jirovecii colonization. Our study suggests that there is a correlation between the P. jirovecii burden in the alveolus (from colonization to a high P. jirovecii burden), and the degree of impairment of the alveolar immune response.

Bronchoalveolar lavage fluid peptidomics suggests a possible matrix metalloproteinase-3 role in bronchopulmonary dysplasia

BACKGROUND

Bronchoalveolar lavage fluid (BALF) is an important diagnostic source to investigate molecular changes occurring in lung disorders. The objective of this study was to assess and compare the peptidomic profiles of BALF from premature neonates with and without bronchopulmonary dysplasia (BPD).

METHODS

Samples were obtained on the 3rd day of life from 34 neonates with gestational age <or=32 weeks. Two pools of samples from patients with and without BPD were analyzed by high performance liquid chromatography. Several differentially expressed peptides were collected and sequenced. Moreover, samples from single donors were analyzed by liquid chromatography-electrospray ionization mass spectrometry to define the molecular mass values of various peptides and to quantify their expression. Levels of some matrix metalloproteinases and their tissue inhibitors were also determined in single samples.

RESULTS

Neonates of the BPD group (N = 16) showed significantly lower mean gestational age and birth weight with respect to the no-BPD group (N = 18; P < 0.0001). Levels of six peptides were significantly higher in BPD patients (P < 0.05). Two of them were identified as the albumin fragments 1-21 (2,428 Da) and 399-406 (956 Da). Levels of matrix metalloproteinase-3 (MMP-3) enzyme probably involved in albumin fragment generation were also significantly higher in the BPD group compared to the no-BPD group (P < 0.05), whereas the levels of tissue inhibitor of metalloproteinases-1 were significantly lower (P < 0.05). Levels of albumin fragments and MMP-3 showed a significant correlation (P < 0.05).

CONCLUSIONS

This study shows that proteomic techniques can be applied to investigate the involvement of proteolytic enzymes on the airways of mechanically ventilated premature infants.

Plasma and pulmonary fluid endothelin in horses with seasonal recurrent airway obstruction

BACKGROUND

Summer pasture-associated recurrent airway obstruction (SPA-RAO), a seasonal airway obstructive disease of horses, is characterized by clinical exacerbation after exposure to pasture during warm months of the year. Endothelin (ET)-1, potent bronchoconstrictor, mitogen, secretagogue, and proinflammatory mediator, has been implicated in the pathogenesis of asthma and equine heaves.

HYPOTHESIS

Immunoreactive ET-1 concentrations increase during clinical exacerbation and return to basal values during periods of disease remission.

ANIMALS

Twelve horses, 6 affected with SPA-RAO and 6 nonaffected.

METHODS

Prospective, observational study. Bronchoalveolar lavage fluid (BALF), arterial and venous plasma samples, and clinical variables were obtained from affected horses during clinical exacerbation and remission. Samples and data of nonaffected horses were collected during the summer and winter on dates similar to affected horses. Immunoreactive ET-1 was determined using a commercial ELISA.

RESULTS

The median and range ET-1 concentrations (pg/ml) in arterial (1.3, 0.7-1.8) and venous (1.3, 1.2-1.7) plasma and in BALF (0.3, 0.2-0.4), and pulmonary epithelial lining fluid (PELF) (25.5, 21-50) were greater in affected horses during clinical exacerbation compared with remission (P < .01). The concentrations of immunoreactive ET-1 were greater in affected horses during clinical exacerbation compared with nonaffected horses (P < .05).

CONCLUSIONS AND CLINICAL IMPORTANCE

During clinical exacerbation of SPA-RAO, ET-1 is increased in circulation and pulmonary secretions. Intervention with ET receptor antagonists should provide further information on the role of ET-1 in SPA-RAO.

Comparison of the pharmacodynamics of biapenem in bronchial epithelial lining fluid in healthy volunteers given half-hour and three-hour intravenous infusions

The time above the MIC (T>MIC) is the pharmacokinetic/pharmacodynamic (PK/PD) parameter that correlates with the therapeutic efficacy of beta-lactam antibiotics. A prolonged infusion can provide plasma drug concentrations that remain above the MIC for a long period. The objective of this study was to compare the PK/PD parameters in bronchial epithelial lining fluid (ELF) of biapenem given as 0.5-h and 3-h infusions by using bronchoscopic microsampling (BMS). Six healthy adult volunteers received 0.5-h and 3-h infusions of 0.3 g of biapenem with a washout interval. BMS was performed repeatedly from 0.5 to 24 h after biapenem administration in order to determine the pharmacokinetics in bronchial ELF. The subjects received intravenous biapenem with the same regimens again and then underwent bronchoalveolar lavage (BAL) at the end of infusion in order to determine the concentration of the drug in alveolar ELF. The percentages (means +/- standard deviations) of T>MIC in bronchial ELF at MICs from 0.25 to 4 microg/ml ranged from zero to 34.6% +/- 5.2% after the 0.5-h infusion and from 5.1% +/- 5.6% to 52.2% +/- 17.0% after the 3-h infusion. The percentage of T>MIC in bronchial ELF after the 3-h infusion tended to be higher than that after the 0.5-h infusion. The concentrations of the drug in alveolar ELF after 0.5-h and 3-h infusions were 3.5 +/- 1.2 microg/ml and 1.3 +/- 0.3 microg/ml, respectively. The present results support the use of prolonged infusions of beta-lactam antibiotics and may provide critical information for successful treatment of lower respiratory tract infections based on PK/PD parameters in bronchial ELF.

Altered pulmonary interleukin-6 signaling in preterm infants developing bronchopulmonary dysplasia

Interleukin (IL)-6 signaling depends on the soluble IL-6 receptor (sIL-6R) and the soluble glycoprotein 130 (sgp130). To investigate the impact of IL-6 signaling on the pathogenesis of bronchopulmonary dysplasia of prematurity (BPD), IL-6, sIL-6R, and sgp130 were measured by enzyme-linked immunosorbent assay (ELISA) technique in tracheal aspirates of mechanically ventilated preterm infants. Infants developing BPD showed increased concentrations of IL-6, sIL-6R, and sgp-130 in their first week of life. These infants also had significantly higher molar ratios for IL-6/sIL-6R and IL-6/sgp130. The authors conclude that altered interleukin-6 signaling via the soluble receptors sIL-6R and sgp130 may play an important role in pulmonary inflammation of preterm infants.

Bacterial ventilator-associated pneumonia: bronchoalveolar lavage results are not influenced by dilution

OBJECTIVE

This study was designed to determine if bronchoalveolar lavage (BAL) quantitative culture results can be used confidently for the diagnosis of bacterial ventilator-associated pneumonia (VAP) without taking dilution into account.

DESIGN

Prospective observational cohort study.

SETTING

A 12-bed medical ICU in a teaching hospital.

PATIENTS

A total of 241 BAL (three 50-mL aliquots) were performed in 127 patients presenting a suspicion of VAP.

INTERVENTIONS

All consecutive adults who were ventilated more than 48 h were included if VAP was clinically suspected. A dilution factor, k, was developed according to the formula: dilution factor k = concentration of urea in plasma/concentration of urea in lavage fluid recovered. Using this dilution factor, the quantitative bacterial counts were interpreted accordingly with a corrected positive threshold at 10(5) colony forming unit (CFU) mL(-1).

MEASUREMENTS AND RESULTS

Eighty-nine BAL with at least one micro-organism > or = 10(4) CFU mL(-1) were identified (37%). In 176 BAL (73%), k ranged from 10 to 100. Median k was 24.4 (9.7-40.2) in VAP group and 24.6 (13.1-57.8) in patients without pneumonia (NS). Among the 25 BAL with micro-organism counts of 10(4) CFU mL(-1), 3 had a dilution factor lower than 10, resulting in corrected counts below the threshold of 10(5) CFU mL(-1). Two out of 15 patients with micro-organism counts of 10(3) CFU mL(-1) had corrected micro-organism counts of 10(5) CFU mL(-1). Finally, only five BAL (2.1%) were misclassified when the dilution correction factor was applied.

CONCLUSIONS

Using urea as dilution factor, we showed that BAL dilution variations did not alter the interpretation of BAL quantitative bacterial culture when administrating three aliquots of 50 mL of saline.

Effect of hypertonic saline pre-treatment on ischemia-reperfusion lung injury in pig

BACKGROUND

Hypertonic saline may be administered in the setting of lung transplantation but may affect the development of ischemia-reperfusion lung injury. This study investigated the effects of the pre-treatment by intravenous hypertonic saline in a pig model of single lung ischemia-reperfusion.

METHODS

Forty-three pigs (34 +/- 4 kg) under mechanical ventilation were randomly assigned to a left lung ischemia-reperfusion alone or preceded by 4-ml/kg 7.5% hypertonic saline, 33-ml/kg normal saline, or by the infusion of the vasodilator nicardipine. Animals without ischemia served as controls. After euthanasia, the left lung was sampled for histologic analysis and measurement of lung water and alveolar-capillary permeability.

RESULTS

Ischemia-reperfusion resulted in high-permeability pulmonary edema, hypoxemia, and increased interleukin-6 serum level. Hypertonic saline pre-treatment worsened pulmonary edema of the left lung (6.6 +/- 0.7 vs 4.8 +/- 0.8 ml/kg of body weight, p < 0.05) and resulted in a higher ratio of the protein level in the alveolar fluid to the serum protein level (0.41 +/- 0.04 vs 0.21 +/- 0.09, p < 0.05) and in a higher histologic damage score (11 [range, 9-11.75] vs 6.5 [range, 4.5-7.5], p < 0.05) without promoting pulmonary or systemic inflammation. Lung injury was affected neither by normal saline nor by nicardipine pre-treatment. Nicardipine did not influence the deleterious effect of hypertonic saline.

CONCLUSIONS

Pre-treatment by intravenous hypertonic saline worsened ischemia-reperfusion lung injury independently of its effects on the cardiac index or pulmonary circulation but probably through a direct effect of hyperosmolarity on endothelial permeability.

Alveolar concentrations of piperacillin/tazobactam administered in continuous infusion to patients with ventilator-associated pneumonia

OBJECTIVES

To determine the steady-state serum and alveolar concentrations of piperacillin/tazobactam administered in continuous infusion to critically ill patients with ventilator-associated pneumonia and various degrees of renal failure.

DESIGN

Prospective comparative study.

SETTING

An intensive care unit and research ward in a university hospital.

PATIENTS

Forty patients with microbiologically documented ventilator-associated pneumonia.

INTERVENTIONS

Patients were randomized to receive piperacillin/tazobactam daily continuous infusions of 12/1.5 g or 16/2 g after a loading dose of 4/0.5 g. The serum and alveolar piperacillin/tazobactam concentrations were determined at steady-state with high performance liquid chromatography.

MEASUREMENTS AND MAIN RESULTS

The median (interquartile) serum and alveolar piperacillin concentrations were respectively 25.3 mg/L (23.1-32.6) and 12.7 mg/L (6.7-18.0) for 12/1.5 g/day, and 38.9 mg/L (32.9-59.6) and 19.1 mg/L (14.0-21.5), respectively, for 16/2 g/day in patients with no/mild renal failure. In patients with moderate/advance renal failure, the median (interquartile) serum and alveolar piperacillin concentrations were 102.4 mg/L (97.4-112.6) and 44.1 mg/L (33.4-48.3), respectively, for 12/1.5 g/day, and 135.3 mg/L (119.5-146.2) and 54.9 mg/L (45.2-110.3), respectively, for 16/2 g/day. Our results show great variability in piperacillin/tazobactam concentrations, with an alveolar percentage penetration of 40-50% for piperacillin and 65-85% for tazobactam and a negative association between serum or alveolar concentrations and creatinine clearance.

CONCLUSIONS

A target piperacillin serum concentration of at least 35-40 mg/L is probably required to provide alveolar concentrations exceeding the susceptibility breakpoint for gram-negative bacteria (16 mg/L) during ventilator-associated pneumonia. In patients with no/mild renal failure, a continuous daily dose of piperacillin/tazobactam 16/2 g allows reaching this target concentration, which might be not observed with 12/1.5 g/day. In patients with moderate/advanced renal failure, both dosages achieve serum concentrations far above the 35-40 mg/L threshold, suggesting that in that case, therapeutic drug monitoring should be performed in order to adjust the daily dose.

Dexamethasone therapy in preterm infants developing bronchopulmonary dysplasia: effect on pulmonary surfactant disaturated-phosphatidylcholine kinetics

The role of corticosteroid in severe bronchopulmonary dyplasia (BPD) is still debated. Scanty data are available on the corticosteroids effect on surfactant metabolism. Our objective was to compare surfactant kinetics in preterm infants with developing BPD, before and after dexamethasone (DEXA) treatment. Twenty-eight studies were performed in 14 preterm infants (birth weight 786 +/- 192 g, gestational age 26 +/- 1 wk) on high ventilatory setting, before (age 22 +/- 11 d) and after (age 33 +/- 11 d) DEXA. C-labeled dipalmitoyl-phosphatidylcholine (DPPC) was administered endotrachelly to trace pulmonary surfactant. Surfactant disaturated-phosphatidylcholine (DSPC) kinetics and pools were calculated from DSPC C-enrichment curves of serial tracheal aspirates and bi-compartmental analysis. Total protein and myeloperoxidase (MPO) activity in tracheal aspirates were also measured and expressed per ml of Epithelial Lining Fluid (ELF). After DEXA, DSPC alveolar pool increased significantly from 8.2 +/- 7.6 to 10.6 +/- 11.3 mg/kg (p = 0.039), total proteins and MPO were reduced from 8.8 +/- 8.6 to 3.1 +/- 2.1 mg/ml ELF (p = 0.046) and from 1822 +/- 1224 to 1261 +/- 987 mU/mlELF (p = 0.028) respectively. In conclusion, DEXA treatment in mechanically ventilated preterm infants with severe respiratory failure and at high risk of developing BPD, significantly reduced inflammatory markers and increased alveolar surfactant DSPC pool.

Different expression ratio of S100A8/A9 and S100A12 in acute and chronic lung diseases

Calgranulins are a family of powerful chemoattractants, which have been implicated as biomarkers in inflammatory diseases. To determine how different respiratory diseases affect the expression of calgranulins, we measured the expression of S100A8/A9 and S100A12 in bronchoalveolar lavage fluid (BALF) of acute respiratory distress syndrome (ARDS) patients and healthy volunteers by ELISA. Analysis of calgranulin expression revealed a high level of S100A12 in the lavages of patients suffering from ARDS compared to controls (p<0.001). Based on the hypothesis that the increased expression of S100A12 relative to the S100A8/A9 heterodimer was a characteristic of respiratory diseases with neutrophilic inflammation, we measured calgranulin expression in BALF of cystic fibrosis (CF) patients. Despite similarly elevated levels of S100A8/A9, S100A12 was significantly higher in ARDS compared to CF BALF (p<0.001). The differential expression of calgranulins was unique for inflammatory markers, as an array of cytokines did not differ between CF and ARDS patients. Since ARDS is an acute event and CF a chronic inflammation with acute exacerbations, we compared calgranulin expression in sputum obtained from CF and patients with chronic obstructive lung disease (COPD). Levels of S100A12 and S100A8/9 were elevated in CF sputum compared to COPD sputum, but the ratio of S100A12 to S100A8/A9 was similar in COPD and CF and reflected more closely than seen in healthy controls. The results indicate that the regulation of human calgranulin expression and the ratio of S100A8/A9 to S100A12 may provide important insights in the mechanism of respiratory inflammation.

Continuous monitoring of the bronchial epithelial lining fluid by microdialysis

Background

Contents of the epithelial lining fluid (ELF) of the bronchi are of central interest in lung diseases, acute lung injury and pharmacology. The most commonly used technique broncheoalveolar lavage is invasive and may cause lung injury. Microdialysis (MD) is a method for continuous sampling of extracellular molecules in the immediate surroundings of the catheter. Urea is used as an endogenous marker of dilution in samples collected from the ELF. The aim of this study was to evaluate bronchial MD as a continuous monitor of the ELF.

Methods

Microdialysis catheters were introduced into the right main stem bronchus and into the right subclavian artery of five anesthetized and normoventilated pigs. The flowrate was 2 μl/min and the sampling interval was 60 minutes. Lactate and fluorescein-isothiocyanate-dextran 4 kDa (FD-4) infusions were performed to obtain two levels of steady-state concentrations in blood. Accuracy was defined as [bronchial-MD] divided by [arterial-MD] in percent. Data presented as mean ± 95 percent confidence interval.

Results

The accuracy of bronchial MD was calculated with and without correction by the arteriobronchial urea gradient. The arteriobronchial lactate gradient was 1.2 ± 0.1 and FD-4 gradient was 4.0 ± 1.2. Accuracy of bronchial MD with a continuous lactate infusion was mean 25.5% (range 5.7–59.6%) with a coefficient of variation (CV) of 62.6%. With correction by the arteriobronchial urea gradient accuracy was mean 79.0% (57.3–108.1%) with a CV of 17.0%.

Conclusion

Urea as a marker of catheter functioning enhances bronchial MD and makes it useful for monitoring substantial changes in the composition of the ELF.