Plasma interleukin-1 alpha and beta, tumor necrosis factor-alpha, and lipopolysaccharide concentrations during pulmonary exacerbations of cystic fibrosis

Corticosteroid use and increased CXCR2 levels on leukocytes are associated with lumacaftor/ivacaftor discontinuation in cystic fibrosis patients homozygous for the F508del CFTR mutation

Cystic fibrosis (CF) is the most common life-shortening genetic disease and is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Several current therapies aim at improving availability and/or function of the mutant CFTR proteins. The combination therapeutic lumacaftor/ivacaftor (Orkambi, luma/iva) partially corrects folding and potentiates CFTR function impaired by the F508del mutation. Despite the potential for clinical benefit, a substantial number of patients discontinue treatment due to intolerable adverse effects. The aim of the present study is to identify differences between individuals who continued treatment and those who discontinued due to adverse respiratory effects to potentially inform treatment decisions. Clinical data from the year prior to treatment initiation were analyzed from 82 patients homozygous for the F508del mutation treated at the Colorado Adult CF Program. Blood samples were collected from 30 of these subjects before initiation of treatment to examine expression of circulating leukocyte surface antigens and cytokines. Clinical and demographic characteristics were analyzed along with inflammatory markers to determine biomarkers of drug discontinuation. The use of oral prednisone and/or nasal budesonide in the year prior to luma/iva initiation was more prevalent in CF subjects who did not tolerate luma/iva (82% vs. 43%). Increased age, but not gender or initial lung function, was associated with higher probability of discontinuing treatment due to side effects overall. Worse lung function (lower ppFEV₁, ppFEF_25-75 ≤ 60%) was associated with higher incidence of discontinuing treatment due to pulmonary adverse effects. In a nested cohort of patients, increased surface levels of CXCR2 on CD14+CD16- monocytes were associated with discontinuation. Overall, the patients who tolerated luma/iva were distinguishable from those who did not tolerate the drug based on clinical and cellular markers obtained prior to treatment initiation.

Heparin derivatives for the targeting of multiple activities in the inflammatory response

An attractive strategy for ameliorating symptoms arising from the multi-faceted processes of excessive and/or continual inflammation would be to identify compounds able to interfere with multiple effectors of inflammation. The well-tolerated pharmaceutical, heparin, is capable of acting through several proteins in the inflammatory cascade, but its use is prevented by strong anticoagulant activity. Derivatives of heparin involving the periodate cleavage of 2,3 vicinal diols in non-sulfated uronate residues (glycol-split) and replacement of N-sulphamido- with N-acetamido- groups in glucosamine residues, capable of inhibiting neutrophil elastase activity in vitro, while exhibiting attenuated anticoagulant properties, have been identified and characterised. These also interact with two other important modulators of the inflammatory response, IL-8 and TNF-alpha. It is therefore feasible in principle to modulate several activities, while minimising anticoagulant side effects, providing a platform from which improved anti-inflammatory agents might be developed.

Systematic review of blood biomarkers in cystic fibrosis pulmonary exacerbations

BACKGROUND

Biomarkers reflective of disease activity in cystic fibrosis (CF) have the potential to improve patient care, particularly during CF pulmonary exacerbations (CFPEs). Although blood-based biomarkers have been studied in CFPE for nearly 3 decades, none have been integrated into routine clinical practice. To facilitate progress in this area, we performed a systematic review evaluating blood-based biomarkers during CFPE.

METHODS

MEDLINE, EMBASE, and CENTRAL were searched to identify relevant studies published from January 1995 to August 2012. We included all full-text studies examining systemic (blood-based) biomarkers to aid in the diagnosis of CFPE, predict outcomes of CFPE, and/or monitor the response to CFPE treatment.

RESULTS

Seventy-eight unique blood-based biomarkers have been studied to date, mainly inflammatory cytokines, acute phase reactants, and markers of oxidative stress. C-reactive protein (CRP) consistently correlated with disease activity, with a statistically significant increase from stable to exacerbation state in five of six studies, and changes in response to CFPE treatment, with a statistically significant decrease from the beginning to the end of CFPE treatment in 18 of 20 studies. Other promising biomarkers of CFPE disease activity include neutrophil elastase antiproteinase complex, IL-6, myeloperoxidase (MPO), lactoferrin, and calprotectin.

CONCLUSIONS

Although there are several blood-based biomarkers with evidence for application within the CFPE setting, CRP has been the most widely studied biomarker demonstrating the potential for clinical usefulness. Further validation studies and clinical trials are required to determine whether blood-based biomarkers can be used to ultimately improve health outcomes in the setting of a CFPE.

Endotoxin neutralization as a biomonitor for inflammatory bowel disease

Gram-negative bacterial endotoxin is a potent immunostimulant implicated in the development and/or progression of a variety of diseases. The mammalian immune system has both innate and adaptive immune responses to neutralize endotoxin. In this study, a system was developed to monitor bacterial exposure by measuring the extent and nature of endotoxin neutralization in plasma. In control patients, females had higher levels of endotoxin neutralization than males, mirroring clinical outcomes from bacterial infection and sepsis. In addition to the total amount of neutralization, we used inactivation techniques to elucidate the nature of this activity and develop a system to compare early and late immune responses. Using this method to monitor patients with inflammatory bowel disease, we found a more robust total response that relies more on long-term, adaptive components of the immune system and less on early, innate components. Our results indicate that endotoxin neutralization is a valuable method to discern inflammatory bowel disease patients from a control population. Additionally, the nature of neutralization may be valuable in monitoring disease severity and/or the role of medication.

Effects of treatment in the levels of circulating cytokines and growth factors in cystic fibrosis and dialyzed patients by multi-analytical determination with a biochip array platform

Chronic inflammatory diseases need non-invasive sensitive, reliable and predictive clinical biomarkers for diagnosis and monitoring therapy. Since inflammation is a complex phenomenon, simultaneous evaluation of different analytes in the same sample may help in defining this complexity and in developing specific anti-inflammatory intervention strategies. In this study, we used a biochip array system capable of measuring 12 cytokines and growth factors (IL-2, IL-4, IL-6, IL-8, IL-10, IL-1 α, IL-1 β, IFN-γ, TNF-α, MCP-1, VEGF, and EGF) in three groups: 97 control subjects; 24 cystic fibrosis (CF) patients before and during the antibiotic treatment (6 and 15days) for acute pulmonary exacerbation as well as 15days after the withdrawal of therapy; 22 children and young adults on chronic hemodialysis (HD) at the beginning and at the end of a standard HD session. CF patients in acute exacerbation displayed higher IL-2, IL-6, VEGF and MCP-1 levels than the control subjects. IL-6 significantly decreased during therapy (P<0.01) but not 15days after the withdrawal of therapy. IL-8 and EGF levels were significantly lower after 15days from the interruption of therapy (P<0.05 and P<0.01 respectively). Regression analysis showed that IL-4 and IL-6 correlated with the amelioration of the respiratory function during therapy. Patients on HD displayed higher IL-6 but lower IL-2, IL-4, IL-8, IFN-γ and EGF levels than control subjects. Serum levels of IL-8, IL-10 and IFN-γ were significantly higher at the end of the HD session (P<0.05 for all three). A biochip array allowed to define a pattern of cytokines/growth factors associated with an acute exacerbation in CF patients and IL-4 and IL-6 as predictors of response to therapy. In younger HD patients, we identified a biomarker pattern which is different from that of older patients. Finally, further studies are warranted to examine the role of these biomarkers in the pathogenesis of complications in HD patients.

Innate immunity in cystic fibrosis lung disease

Chronic lung disease determines the morbidity and mortality of cystic fibrosis (CF) patients. The pulmonary immune response in CF is characterized by an early and non-resolving activation of the innate immune system, which is dysregulated at several levels. Here we provide a comprehensive overview of innate immunity in CF lung disease, involving (i) epithelial dysfunction, (ii) pathogen sensing, (iii) leukocyte recruitment, (iv) phagocyte impairment, (v) mechanisms linking innate and adaptive immunity and (iv) the potential clinical relevance. Dissecting the complex network of innate immune regulation and associated pro-inflammatory cascades in CF lung disease may pave the way for novel immune-targeted therapies in CF and other chronic infective lung diseases.

Potential of anti-inflammatory treatment for cystic fibrosis lung disease

Cystic fibrosis (CF) is the most common life-shortening genetic disorder in Caucasians. With improved diagnosis and treatment, survival has steadily increased. Unfortunately, the overwhelming majority of patients still die from respiratory failure caused by structural damage resulting from airway obstruction, recurrent infection, and inflammation. Here, we discuss the role of inflammation and the development of anti-inflammatory therapies to treat CF lung disease. The inflammatory host response is the least addressed component of CF airway disease at this time. Current challenges in both preclinical and clinical investigation make the identification of suitable anti-inflammatory drugs more difficult. Despite this, many researchers are making significant progress toward this goal and the CF research community has reason to believe that new therapies will emerge from these efforts.

Sputum biomarkers of inflammation in cystic fibrosis lung disease

Pulmonary biomarkers are being used more frequently to monitor disease activity and evaluate response to treatment in individuals with cystic fibrosis (CF). This article summarizes the current state of knowledge of biomarkers of inflammation relevant to CF lung disease, and the tools to measure inflammation, with specific emphasis on sputum. Sputum is a rich, noninvasive source of biomarkers of inflammation and infection. Sputum induction, through the inhalation of hypertonic saline, has expanded the possibilities for monitoring airway inflammation and infection, especially in individuals who do not routinely expectorate sputum. We critically examine the existing data supporting the validity of sputum biomarkers in CF, with an eye toward their application as surrogate endpoints or outcome measures in CF clinical trials. Further validation studies are needed regarding the variability of inflammatory biomarker measurements, and to evaluate how these biomarkers relate to disease severity, and to longitudinal changes in lung function and other clinical endpoints. We highlight the need to incorporate sputum collection, by induction if necessary, and measurement of sputum biomarkers into routine CF clinical care. In the future, pulmonary biomarkers will likely be useful in predicting disease progression, indicating the onset and resolution of a pulmonary exacerbation, and assessing response to current therapies or candidate therapeutics.

Inflammatory markers of lung disease in adult patients with cystic fibrosis

BACKGROUND

Progressive pulmonary disease associated with chronic bacterial infection and inflammation is the major cause of morbidity and mortality in cystic fibrosis (CF) patients. Identifying markers of inflammation that correlate with lung injury may be useful in monitoring disease progression and response to therapy. We hypothesized that levels of serum biomarkers would correlate with clinical course of CF as defined by pulmonary function testing (FEV1).

OBJECTIVE

To determine whether biomarkers of systemic inflammation correlate with lung function in adults with CF.

METHODS

Retrospective cross-sectional analysis of 63 individuals > or = 30 years of age diagnosed with CF in childhood and followed at Children's Hospital, Boston. We collected data on demographics, CFTR genotype, percent predicted forced expiratory volume in 1 sec (FEV1), C-reactive protein (CRP), serum IgE nd IgG, alpha1-antitrypsin, total white blood cell and neutrophil counts, and percent neutrophils. We used univariate analyses and multivariate linear regression modeling to examine whether markers of systemic inflammation varied with FEV1 (% predicted).

RESULTS

In two-covariate models including CRP and one other marker, CRP (P < 0.001) and IgG (P = 0.02) were significantly associated with FEV1 (% predicted). In the CRP and IgG model, percent predicted FEV1 decreased by 4.91% (P < 0.0001) for each twofold increase in CRP and by 1.56% (P = 0.02) for each 100 mg/dl increase in IgG. Results were unchanged by adjustment for number of DF 508 CFTR alleles. There was no association between any other marker and FEV1 (% predicted) after adjusting for CRP.

CONCLUSION

Severity of lung disease in long surviving adult CF patients is correlated with CRP and IgG levels. Our findings relating CRP and IgG levels and lung function provide a foundation for subsequent longitudinal studies and consideration of novel disease mechanisms and outcome measurements.

Proteomic Analysis of Sputum from Adults and Children with Cystic Fibrosis and from Control Subjects

RATIONALE

Recurrent pulmonary exacerbations are associated with progressive lung disease in cystic fibrosis (CF). Current definitions of an exacerbation, although not precisely defined, include new/worsening symptoms, declining lung function, and/or changing radiologic appearance. Early diagnosis of exacerbations by rapid noninvasive means should expedite therapeutic intervention, thereby minimizing lung damage.

OBJECTIVES

To identify biomarkers of lung exacerbation for point-of-care monitoring of CF lung disease progression.

METHODS

Saline-induced sputum was collected from adults with CF with an exacerbation and requiring hospitalization (FEV(1) < 60%), a subset of these adults at hospital discharge, children with stable CF and preserved lung function (FEV(1) > 70%), and control subjects (FEV(1) > 80%). Sputum was arrayed by two-dimensional electrophoresis and differentially expressed proteins were identified by proteomic analysis.

MEASUREMENTS AND MAIN RESULTS

Sputum profiles from adults with CF with an exacerbation were characterized by extensive proteolytic degradation and influx of inflammation-related proteins, with some adults with CF approaching a "healthy" protein profile after hospitalization. Two children with CF showed profiles and biomarker expression resembling those of adults with an exacerbation. Levels of differentially expressed myeloperoxidase, cleaved alpha(1)-antitrypsin, IgG degradation, interleukin-8, and total protein concentration, together with their correlation to FEV(1), were statistically significant. Statistical correlation analyses indicated that changes in myeloperoxidase expression and IgG degradation were the strongest predictors of FEV(1).

CONCLUSIONS

We identified extensive protein degradation and differentially expressed proteins as biomarkers of inflammation relating to pulmonary exacerbations. Prediction of exacerbation onset and more precise evaluation of the extent of resolution with treatment could be achieved by including biomarkers in standard assessment.

Nutrition in patients with cystic fibrosis: a European Consensus

This document is the result of an European Consensus conference which took place in Artimino, Tuscany, Italy, in March 2001 involving 33 experts on nutrition in patients with cystic fibrosis, organised by the European Cystic Fibrosis Society, and sponsored by Axcan-Scandipharm, Baxter, Dr Falk Pharma, Fresenius, Nutricia, SHS International, Solvay Pharmaceuticals (major sponsor). The purpose of the conference was to develop a consensus document on nutrition in patients with cystic fibrosis based on current evidence.

Duration of effect of intravenous antibiotics on spirometry and sputum cytokines in children with cystic fibrosis

Intravenous (IV) antibiotics are a mainstay of therapy in children with cystic fibrosis. It is unclear, however, over what period associated improvements in pulmonary function are maintained, and to what extent the underlying inflammatory process is impeded in children admitted for a course of IV antibiotics. This was a prospective, interventional study of 14 children (median age, 14 years; interquartile range, 10-14) with cystic fibrosis who were regular sputum producers and who required admission for a 2-week course of IV antibiotics. Children performed spirometry and provided a sputum sample prior to starting IV antibiotics and then weekly for 6 weeks, the first 2 weeks of which IV antibiotics were given. Sputum IL-8, TNF-alpha, IL-6, IL-10, MIP1-alpha, and elastase were measured. Seven children were asked to repeat the protocol in a subsequent exacerbation to assess similarities in response to therapy. Significant improvements were seen in forced expired volume in 1 sec (FEV(1)) in association with IV antibiotics (27% relative improvement in predicted from baseline to end of week 1, median FEV(1) 41.3% increasing to 52.2%), but this continued only 1 week following cessation of antibiotics. Although IL-8 demonstrated a trend for reduction in association with antibiotics, no significant profile was demonstrated for any of the cytokines assessed. IL-10 was detectable in 64% of samples (all <100 pg/ml). In children with two episodes assessed, although there was a close correlation of FEV(1) and FVC between exacerbations (before antibiotics), no significant correlation was seen for IL-8, TNF-alpha, or IL-10 measured in both sets of samples at any sample point (indeed, a discordant response was seen between sample points in the two exacerbations). Although FEV(1) temporarily improves in response to admission for IV antibiotics, no such response is seen in sputum cytokine values. In addition, assessment of cytokines in subsequent exacerbations does not show a similar pattern of response to treatment.

Relationship between nutritional status and lung function in cystic fibrosis: cross sectional and longitudinal analyses from the German CF quality assurance (CFQA) project

BACKGROUND

The German cystic fibrosis (CF) quality assurance (CFQA) project is a patient registry for CF which was founded in 1995. Relevant clinical and laboratory data, respiratory function test results, complications, and CF treatments are entered into the database once a year for each patient. Using the database, a study was undertaken to elucidate the relationship between nutrition and lung function in a large patient cohort by cross sectional and longitudinal analysis.

METHODS

A cohort of 3298 patients above 2 years of age was analysed. Patients were grouped according to the presence or absence of malnutrition (wasting and/or stunting). Cross sectional and longitudinal analyses over 2 and 3 years including mixed model analyses were performed.

RESULTS

The prevalence of abnormal weight for height (<90% predicted) increased with age from 19% in children aged <6 years to 38% in adults with CF. Patients with malnutrition had significantly lower mean values of vital capacity, arterial oxygen tension (PO(2)), and forced expiratory volume in 1 second (FEV(1)) and higher serum IgG (p<0.05). Pseudomonas aeruginosa infection was also associated with decreased pulmonary function. Malnourished adolescents aged 12-18 years experienced a serious decline in FEV(1) of about 20% predicted, whereas mean FEV(1) values remained stable at above 80% predicted in adolescents of normal weight. Longitudinal follow up showed that malnourished patients of all ages and those with P aeruginosa infection had significantly worse lung function than their normally nourished counterparts and a greater yearly loss of FEV(1) % predicted. During 1 year of observation adolescents who experienced a >5% predicted decrease in weight for height had a concomitant mean loss of FEV(1) of 16.5% predicted during that year, whereas patients who gained relative weight had a parallel increase in FEV(1) of 2.1% predicted.

CONCLUSIONS

These data emphasise the close relationship between nutrition, lung function, and clinical course in CF. Normal body weight and absence of P aeruginosa infection was associated with better preservation of lung function.

Resting energy expenditure in young patients with cystic fibrosis receiving antibiotic therapy for acute respiratory exacerbations

BACKGROUND

patients with cystic fibrosis commonly have severe malnutrition and growth retardation. Among possible causes of these manifestations are low caloric intake, loss of nutrients and increased resting energy expenditure. This study was designed to assess the influence of antibiotic therapy for infectious exacerbations on resting energy expenditure in young patients with cystic fibrosis.

METHODS

We studied 17 patients with cystic fibrosis (mean age, 13.6 years). All were hospitalized to receive intravenous antibiotic therapy (mean duration, 2 weeks) for acute respiratory exacerbations. At the beginning of therapy and after it ended, all patients underwent blood chemical tests, anthropometrical measures, determination of body composition by bioelectrical impedance, spirometry, and indirect calorimetry.

RESULTS

Antibiotic therapy led to a significant improvement in biochemical, spirometric variables and in estimated calorimetry measurements expressed in relation to fat-free mass. These findings suggest that infective exacerbations are among the causes of increased resting energy expenditure in young patients with cystic fibrosis.

CONCLUSIONS

Indirect calorimetry may prove useful in the diagnosis of infective exacerbations and in monitoring the effect of antibiotic therapy in patients with cystic fibrosis.

Rethinking cystic fibrosis pathology: the critical role of abnormal reduced glutathione (GSH) transport caused by CFTR mutation

Though the cause of cystic fibrosis (CF) pathology is understood to be the mutation of the CFTR protein, it has been difficult to trace the exact mechanisms by which the pathology arises and progresses from the mutation. Recent research findings have noted that the CFTR channel is not only permeant to chloride anions, but other, larger organic anions, including reduced glutathione (GSH). This explains the longstanding finding of extracellular GSH deficit and dramatically reduced extracellular GSH:GSSG (glutathione disulfide) ratio found to be chronic and progressive in CF patients. Given the vital role of GSH as an antioxidant, a mucolytic, and a regulator of inflammation, immune response, and cell viability via its redox status in the human body, it is reasonable to hypothesize that this condition plays some role in the pathogenesis of CF. This hypothesis is advanced by comparing the literature on pathological phenomena associated with GSH deficiency to the literature documenting CF pathology, with striking similarities noted. Several puzzling hallmarks of CF pathology, including reduced exhaled NO, exaggerated inflammation with decreased immunocompetence, increased mucus viscoelasticity, and lack of appropriate apoptosis by infected epithelial cells, are better understood when abnormal GSH transport from epithelia (those without anion channels redundant to the CFTR at the apical surface) is added as an additional explanatory factor. Such epithelia should have normal levels of total glutathione (though perhaps with diminished GSH:GSSG ratio in the cytosol), but impaired GSH transport due to CFTR mutation should lead to progressive extracellular deficit of both total glutathione and GSH, and, hypothetically, GSH:GSSG ratio alteration or even total glutathione deficit in cells with redundant anion channels, such as leukocytes, lymphocytes, erythrocytes, and hepatocytes. Therapeutic implications, including alternative methods of GSH augmentation, are discussed.

Interlobar differences in bronchoalveolar lavage fluid from children with cystic fibrosis

Bronchoalveolar lavage (BAL) performed in specialist centres has improved the understanding of infant cystic fibrosis (CF) lung disease. As most researchers sample from a single lobe, it was determined whether BAL results could be generalized to other lung segments. Thirty-three CF children, aged 1.5-57 months, underwent in random order sequential BAL of their right middle and lingula lobes. Specimens from each lobe had separate quantitative bacteriology, cytology and cytokine analysis. Bacterial counts > or = 1 x 10(5) colony forming units (cfu) x mL(-1) were observed in nine (27%) subjects, including six involving only the right middle lobe. These six children had similar inflammatory indices in their right middle and lingula lobes, and interleukin (IL)-8 concentrations in the latter were significantly higher than that observed within the lingula lobes of the 24 CF children with bacterial counts < 1 x 10(5) cfu x mL(-1). Lingula neutrophil and IL-8 levels correlated best with right middle lobe bacteria numbers. This observational study in cystic fibrosis children suggests that while inflammation is detected in both lungs, bacterial distribution may be more inhomogeneous. Bronchoalveolar lavage microbiological findings from a single lobe may therefore, not be generalized to other lung segments. When performing bronchoalveolar lavage in cystic fibrosis children, it is important to sample from multiple sites.

Matrilysin expression and function in airway epithelium

We report that matrilysin, a matrix metalloproteinase, is constitutively expressed in the epithelium of peribronchial glands and conducting airways in normal lung. Matrilysin expression was increased in airway epithelial cells and was induced in alveolar type II cells in cystic fibrosis. Other metalloproteinases (collagenase-1, stromelysin-1, and 92-kD gelatinase) were not produced by normal or injured lung epithelium. These observations suggest that matrilysin functions in injury-mediated responses of the lung. Indeed, matrilysin expression was increased in migrating airway epithelial cells in wounded human and mouse trachea. In human tissue, epithelial migration was reduced by > 80% by a hydroxamate inhibitor, and in mouse tissue, reepithelialization in trachea from matrilysin-null mice was essentially blocked. In vivo observations and cell culture studies demonstrated that matrilysin was secreted lumenally by lung epithelium, but upon activation or while migrating over wounds, some matrilysin was released basally. The constitutive production of matrilysin in conducting airways, its upregulation after injury, its induction by alveolar epithelium, and its release into both lumenal and matrix compartments suggest that this metalloproteinase serves multiple functions in intact and injured lung, one of which is to facilitate reepithelialization.

Acute pulmonary exacerbation is not associated with increased energy expenditure in children with cystic fibrosis

OBJECTIVE

The objective of this study was to document alterations in resting energy expenditure (REE), energy intake, and body composition that occur during admission for management of a pulmonary exacerbation in children with cystic fibrosis.

STUDY DESIGN

A prospective study of 14 children with cystic fibrosis (8 male, 12.5 +/- 3.3 years) was conducted throughout a 14-day hospitalization and again 3 weeks after discharge. Repeated measures analysis of variance was used to examine the change in variables across time.

RESULTS

Significant increases were documented from days 1 to 14 in weight (37.1 +/- 13.1 kg to 38.4 +/- 13.5 kg) and pulmonary function (forced expiratory volume in 1 second: 67.6% +/- 19.8% to 78.5% +/- 24.5%). Energy intake was not different between hospitalization and follow-up and averaged 175% of the Recommended Dietary Allowance. REE on day 1 was elevated (122% +/- 11% predicted); however, when expressed with fat free mass as a covariate, no significant changes were noted in REE throughout the eight measurements.

CONCLUSIONS

These data suggest that an acute pulmonary exacerbation is not associated with an increase above a subject's baseline REE in children with cystic fibrosis with mild to moderate lung disease. Management of an acute pulmonary exacerbation should be associated with sustained improvement in pulmonary function and nutritional status; in contrast, weight loss or failure to improve pulmonary function should be seen as atypical.

Aerosolized antibiotics in mechanically ventilated patients: delivery and response

OBJECTIVES

To determine whether aerosolized antibiotics can be delivered efficiently to the lower respiratory tract in mechanically ventilated patients and to define possible clinical responses to these agents.

DESIGN

Prospective serial study with cases as their own control.

SETTING

A 10-bed respiratory care unit for patients with chronic respiratory failure in a tertiary university hospital.

PATIENTS

Ventilator dependent patients who are otherwise medically stable. All subjects had a tracheostomy in place, were colonized with gram-negative organisms, and produced purulent secretions which could be sampled daily.

INTERVENTIONS

Six patients received nine courses of nebulized therapy, which consisted of treatments every 8 hrs of gentamicin (80 mg) or amikacin (400 mg) for 14 to 21 days.

MEASUREMENTS AND MAIN RESULTS

Doses to the lung were measured using radiolabeled aerosols and antibiotic concentrations in sputum. The response was assessed by a) changes in the volume of respiratory secretions; b) effect on bacterial cultures; and c) changes in the inflammatory cells and mediators of inflammation of the respiratory secretions (interleukin-1beta [IL-1beta], tumor necrosis factor-alpha [TNF-alpha], soluble intercellular adhesion molecule-1 [sICAM-1], and human leukocyte elastase). On average, patients inhaled 35.4 +/- 5.08% (SD) of the initial drug placed in the nebulizer (neb-charge). Of this neb-charge, 9.50 +/- 2.78% was found on the respirator tubing and tracheostomy tube and 21.9 +/- 7.15% was actually deposited in the lungs. The remainder of the neb-charge was sequestered in the nebulizer or exhaled. Trough sputum concentrations averaged 4.3 +/- 3.2 microg/mL/mg neb-charge (range 234 to 520 microg/mL) and increased to 16.6 +/- 8.1 microg/mL/mg neb-charge (range 1005 to 5839 microg/mL) immediately after therapy (p = .011). Serum concentrations were undetectable in most determinations except for a single patient who was in renal failure (8.7 microg/mL amikacin). Treatment caused a significant reduction in the volume of secretions (p = .002). Weekly cultures revealed eradication of Pseudomonas species, Serratia marcescens, and Enterobacter aerogenes in most of the trials. Before antibiotic treatment, concentrations of IL-1beta were higher than those reported in acute respiratory distress syndrome. Throughout the duration of the study, IL-1beta correlated significantly with the absolute number of macrophages, neutrophils, and lymphocytes, respectively (r2 = .55, p = .002; r2 = .50, p < .0004, r2 = .36, p = .005). TNF-alpha concentrations correlated with lymphocytes and neutrophils, respectively (r2 =.27, p = .013, r2 = .21, p = .033). sICAM-1 concentrations increased two-fold (p < .001) during treatment and then returned to baseline. The volume of secretions was related to neutrophil and IL-1beta concentrations, respectively (r2 = .25, p = .008, r2= .35, p = .006).

CONCLUSIONS

Nebulizer delivery of aerosolized aminoglycosides is efficient and predictable. In our clinical model, aerosolized antibiotics can make a significant impact on respiratory secretions. Their efficacy in treatment of critically ill patients remains to be determined.