Death In Cystic Fibrosis Patients Research Articles

HEPATIC STEATOSIS IN CYSTIC FIBROSIS. APROPOS OF A CASE

Cystic Fibrosis (CF) is a genetic disease characterized by dysfunction of the exocrine glands. Hepatic involvement is the leading non-pulmonary cause of death in CF patients. This paper aims to present the case of a schoolchild with hepatic alterations as the initial clinical manifestation of CF. 10-year-old male with a history of sibling death due to liver failure at three years of age, multiple respiratory symptoms in the first two years of life and hospitalization at 3 years of age due to bronchitis. The condition began one year before the assessment with growth arrest and in the last six months with two diarrheal episodes without mucus or blood. On physical examination, weight and height below p5 for age, icteric color, without hepatosplenomegaly, limbs with acropaquia (Image 1). Average bone age of 5-6 years, paraclinical tests with hypertransaminasemia, hypetriglyceridemia and decreased HDL (table 1), normal blood biometry, liver elastography with ARFI 2.1 m/s and liver biopsy with macro and microvesicular steatosis with moderate portoportal fibrosis (image 1-2). Negative approach for infectious hepatitis, Wilson´s disease. 1 alpha-antitrypsin deficiency and lysosomal acid lipase deficiency. Diagnosis of CF with sweat electrolytes of 105 mmol/L was made. Currently under follow-up by gastroenterology and pediatric pulmonology. CF is the most common autosomal recessive disease in the Caucasian population, with multi-organ involvement. Liver disease has a high incidence in the first 10 years of life with 2.5/100 patient-years. However, no CFTR gene mutation has been directly associated with the presence or severity of the liver disease. Clinical presentation varies from mild asymptomatic form to cirrhosis with the need for liver transplantation in these patients. The most common initial suspicion is hepatomegaly and transaminases alteration and laboratory studies and histology alteration. Hepatic fibroelastography represents an emerging method of study for diagnosis, as it represents one of the forms of confirmation of the criteria for liver disease associated with cystic fibrosis. Liver biopsy provides information on the predominant type of lesion (steatosis or focal cirrhosis) and the extent of portal fibrosis. However, it should be taken with caution because of the risk of underestimating the severity of the lesions. Although the liver disease in cystic fibrosis does not represent the initial manifestation, the evaluation and monitoring in these patients are important for prognosis and survival since it can progress to cirrhosis and liver failure. The authors declare that there is no conflict of interest.

Characterization of a novel mCH3 conjugated anti-PcrV scFv molecule

Pseudomonas aeruginosa (PA) is a leading cause of nosocomial infections and death in cystic fibrosis patients. The study was conducted to evaluate the physicochemical structure, biological activity and serum stability of a recombinant anti-PcrV single chain variable antibody fragment genetically attached to the mCH3cc domain. The stereochemical properties of scFv-mCH3 (YFL001) and scFv (YFL002) proteins as well as molecular interactions towards Pseudomonas aeruginosa PcrV were evaluated computationally. The subcloned fragments encoding YFL001 and YFL002 in pET28a were expressed within the E. coli BL21-DE3 strain. After Ni–NTA affinity chromatography, the biological activity of the proteins in inhibition of PA induced hemolysis as well as cellular cytotoxicity was assessed. In silico analysis revealed the satisfactory stereochemical quality of the models as well as common residues in their interface with PcrV. The structural differences of proteins through circular dichroism spectroscopy were confirmed by NMR analysis. Both proteins indicated inhibition of ExoU positive PA strains in hemolysis of red blood cells compared to ExoU negative strains as well as cytotoxicity effect on lung epithelial cells. The ELISA test showed the longer serum stability of the YFL001 molecule than YFL002. The results were encouraging to further evaluation of these two scFv molecules in animal models.

Cystic fibrosis-associated liver disease in children.

As improvements in nutritional and pulmonary care increase the life expectancy of cystic fibrosis (CF) patients, CF-associated liver disease (CFLD) is emerging as a cause of mortality. CFLD is the third leading cause of death in CF patients. We performed a search on PubMed and Google Scholar for published articles on CFLD. We reviewed the articles found in the literature search and gave priority to recent publications and studies with larger sample sizes. The prevalence of CFLD in the CF population is around 23% with a range of 2-62% and that prevalence increases linearly with age from 3.7% at age 5 to 32.2% at age 30. CFLD can present clinically in various ways such as hepatomegaly, variceal hemorrhage, persistent elevation of liver enzymes, and micro-gallbladder. Due to the focal nature of fibrosis in majority cases of CFLD, liver biopsies are sparsely performed for diagnosis or the marker of liver fibrosis. Although the mechanism of CFLD development is still unknown, many potential factors are reported. Some mutations of CFTR such as having a homozygous F508del mutation has been reported to increase the risk of developing CFLD and its severity. Having the SERPINA1 Z allele, a history of pancreatic insufficiency, a history meconium ileus, CF-related diabetes, or being male increases the risk of developing CFLD. Environmental factors do not appear to have significant effect on modulating CFLD development. Ursodeoxycholic acid is commonly used to treat or prevent CFLD, but the efficacy of this treatment is questionable.

Targeted Killing of Pseudomonas aeruginosa by Pyocin G Occurs via the Hemin Transporter Hur

Pseudomonas aeruginosa is a priority pathogen for the development of new antibiotics, particularly because multi-drug-resistant strains of this bacterium cause serious nosocomial infections and are the leading cause of death in cystic fibrosis patients. Pyocins, bacteriocins of P. aeruginosa, are potent and diverse protein antibiotics that are deployed during bacterial competition. Pyocins are produced by more than 90% of P. aeruginosa strains and may have utility as last resort antibiotics against this bacterium. In this study, we explore the antimicrobial activity of a newly discovered pyocin called pyocin G (PyoG). We demonstrate that PyoG has broad killing activity against a collection of clinical P. aeruginosa isolates and is active in a Galleria mellonella infection model. We go on to identify cell envelope proteins that are necessary for the import of PyoG and its killing activity. PyoG recognizes bacterial cells by binding to Hur, an outer-membrane TonB-dependent transporter. Both pyocin and Hur interact with TonB1, which in complex with ExbB–ExbD links the proton motive force generated across the inner membrane with energy-dependent pyocin translocation across the outer membrane. Inner-membrane translocation of PyoG is dependent on the conserved inner-membrane AAA+ ATPase/protease, FtsH. We also report a functional exploration of the PyoG receptor. We demonstrate that Hur can bind to hemin in vitro and that this interaction is blocked by PyoG, confirming the role of Hur in hemin acquisition.

Encapsulated Methionine γ-Lyase: Application in Enzyme Prodrug Therapy of Pseudomonas aeruginosa Infection.

Lung disease caused by Pseudomonas aeruginosa is the leading reason for death in cystic fibrosis patients. Therapeutic efficacy of the pharmacological pairs, the naked/encapsulated mutant form of Citrobacter freundii methionine γ-lyase and the substrates, sulfoxides of S-substituted l-cysteine, generating thiosulfinates, was evaluated on the murine model of experimental sepsis caused by the multidrug-resistant P. aeruginosa 203-2 strain. The pairs containing the naked enzyme and substrates did not have antibacterial activity. The treatment of mice with the pair encapsulated enzyme and S-methyl-l-cysteine sulfoxide, generating dimethyl thiosulfinate, led to a complete recovery of the animals of the model, with the infecting dose equal to LD50. The pair generating diallyl thiosulfinate (allicin) proved to be less effective. So, the substituents, attached to the thiosulfinate moiety, affect the antibacterial activity of thiosulfinates against P. aeruginosa.

Cystic Fibrosis Liver Disease: Know More.

Cystic fibrosis (CF) is a multisystem disease caused by mutations in the CF transmembrane conductance regulator (CFTR) gene. CFTR is expressed in the apical surface of cholangiocytes. Homozygous CFTR gene mutation results in viscous and acidic bile secretions secondary to deficient surface fluid and bicarbonate efflux. Viscous, inspissated bile causes ductular obstruction and hepatotoxicity from retained bile components, leading to fibrosis and ultimately cirrhosis, known as CF liver disease (CFLD). CFLD is the third leading cause of death in CF patients. CFLD manifestations can take many forms. They range from asymptomatic elevation of transaminases to cirrhosis and end-stage liver disease. CFLD is diagnosed after excluding other causes of chronic liver disease. To date, there is no effective therapy to prevent or treat CFLD. Management of CFLD emphasizes on optimizing nutritional status. Ursodeoxycholic acid is the only available treatment that may prevent progression of CFLD at present. All CF patients with CFLD need annual investigations and follow-up for early detection of the disease. Liver transplantation should be considered in patients with decompensated cirrhosis and portal hypertension, with acceptable long-term outcomes. Novel therapies of CFLD are promising. This review article aims to summarize the published literature on CFLD, its pathophysiology, clinical features and complications, and management including new therapeutic options.

Serum Phospholipid Fatty Acid Composition in Cystic Fibrosis Patients with and without Liver Cirrhosis

Background/Aims: Cystic fibrosis (CF) liver disease is the third most frequent cause of death in CF patients. Although it alters fatty acid (FA) metabolism, data concerning the profile of FA in CF patients with liver cirrhosis is lacking. This study aimed to assess the FA composition of serum phospholipids in CF patients with and without liver cirrhosis. Methods: The study comprised 25 CF patients with liver cirrhosis and 25 without it. We assessed Z-scores for body height and weight, lung function, exocrine pancreatic sufficiency and colonization with Pseudomonas aeruginosa. FAs' profile of serum glycerophospholipids was quantified by gas chromatography mass spectrometry. Results: In CF patients with liver cirrhosis, the levels of C16:0 were higher and the amounts of C20:2n-6, C20:3n-6, C20:4n-6, and all the n-3 polyunsaturated FAs (PUFAs) (C18:3n-3, C20:5n-3, C22:5n-3, C22:6n-3) were lower than those in CF subjects without liver cirrhosis. The n-6/n-3, C20:4n-6/C18:2n-6, total n-6/C18:2n-6, C20:5n-3/C18:3n-3 and total n-3/C18:3n-3 ratios did not differ between the 2 groups. Conclusions: Liver cirrhosis may associate with profound abnormalities in the composition of serum glycerophospholipids FAs in CF patients. None of the analyzed clinical factors could explain the greater prevalence of low levels of PUFAs in this CF subgroup.

Analysis of Pseudomonas aeruginosa PAO1 Biofilm Protein Profile After Exposure to n-Butanolic Cyclamen coum Extract Alone and in Combination with Ciprofloxacin.

Pseudomonas aeruginosa biofilm-related infections are the major cause of premature death in cystic fibrosis patients. Strategies to induce biofilm dispersal are of interest, because of their potential in preventing biofilm-related infections. Our previous work demonstrated that n-butanolic Cyclamen coum extract with ciprofloxacin could eliminate 1- and 3-day-old P. aeruginosa PAO1 biofilms. To gain new insights into the role of C. coum extract and its synergistic effect with ciprofloxacin in eliminating P. aeruginosa PAO1 biofilms, two-dimensional gel electrophoresis (2-DE) in combination with mass spectrometry-based protein identification were used. Changes in the bacterial protein expression were analyzed when 3-day-old biofilm cells were exposed to the C. coum extract alone and in combination with ciprofloxacin. Proteins involved in alginate biosynthesis, quorum sensing, adaptation/protection, carbohydrate and amino acid metabolism showed a weaker expression in the C. coum extract-ciprofloxacin-treated biofilm cells compared to those in the untreated cells. Interestingly, the proteome of C. coum extract-ciprofloxacin-treated biofilm revealed more resemblance to the planktonic phenotype than to the biofilm phenotype. It appears that saponin extract in combination with ciprofloxacin causes biofilm disruption due to several mechanisms such as motility induction, cell envelope integrity perturbation, stress protein expression reduction, and more importantly, signal transduction perturbation. In conclusion, exposure to a combination of biofilm dispersal such as saponin extract and antimicrobial agents may offer a novel strategy to control preestablished, persistent P. aeruginosa biofilms and biofilm-related infections.

Pulmonary Hypertension in Cystic Fibrosis with Advanced Lung Disease

The impact of pulmonary hypertension (PH) on survival in cystic fibrosis (CF) remains unclear. To determine the influence of PH on survival in the CF population. The United Network for Organ Sharing database was queried from 1987 to 2013 to identify first-time lung transplant candidates who were tracked from wait list entry date until death or censoring to determine influence of PH. Using right heart catheterization measurements, mild PH was defined as mean pulmonary artery pressure greater than or equal to 25 mm Hg and severe greater than or equal to 35 mm Hg. Of 2,781 CF patients, 2,100 were used for univariate analysis, 764 for Kaplan-Meier survival function, 687 for multivariate Cox models, and 576 and 132 for matching on the propensity of mild PH and severe PH, respectively. Univariate Cox analysis found significant differences in survival for mild PH (hazard ratio [HR], 1.747; 95% confidence interval [CI], 1.387-2.201; P < 0.001) and severe PH (HR, 2.299; 95% CI, 1.639-3.225; P < 0.001). Further assessment by multivariate Cox models identified significant risk for death associated with mild PH (HR, 1.757; 95% CI, 1.367-2.258; P < 0.001) and severe PH (HR, 2.284; 95% CI, 1.596-3.268; P < 0.001). Cox regression stratified on matched pairs of PH cases and control subjects confirmed the risk for death for mild PH (HR, 1.919; 95% CI, 1.290-2.85; P = 0.001) and severe PH (HR, 4.167; 95% CI, 1.709-10.157; P = 0.002). The manifestation of PH is associated with significantly increased risk for death in CF patients with advanced lung disease.

Esophageal Cancer in Patients With Cystic Fibrosis

Introduction: Incidence of gastrointestinal malignancies (GIM) is increased in patients with Cystic Fibrosis (CF), and development of GIM is further accelerated by immunosuppression. This is an issue of increasing concern for CF patients as their life expectancy has significantly increased over the recent decades and they often become recipients of solid organ transplants. We have previously published that initiation of screening colonoscopies at age 40 results in a high yield of advanced adenoma detection. However, CF patients are also at risk for other GIM, including esophageal cancer. We report two cases of esophageal cancer identified within the cohort of 95 CF patients age 40 and above and discuss the associated implications. Case 1: A 40-year-old male with history of CF s/p lung transplant presented for EGD to evaluate for odynophagia. He was found to have a large, partially obstructing esophageal tumor. Biopsies showed adenocarcinoma and staging revealed widely metastatic disease. He was started on palliative chemotherapy with initial response, but has unfortunately had disease progression resistant to additional chemotherapy. Case 2: A 52-year-old male with history of CF (not transplanted) presented for EGD to evaluate for dysphagia and weight loss. He was found to have a large, fungating mass in the middle third of the esophagus extending to the lesser curve of the stomach. Biopsy showed adenocarcinoma. Staging again revealed metastatic disease. The patient started on palliative chemotherapy but ultimately passed away from worsening disease. Although pulmonary complications are still the primary cause of death in CF patients, GIM are increasingly becoming important contributors to CF morbidity and mortality as this population ages. We have previously suggested earlier initiation of colorectal cancer screening in adult CF patients, especially since detection and removal of precursor polyp lesions has the potential of cancer prevention. Similarly, anecdotal data suggest that incidence of Barrett’s esophagus, the precursor lesion of esophageal adenocarcinoma, may be increased in CF. Identification of two advanced esophageal cancers within a relatively small patient cohort suggests that a more systematic evaluation of upper gastrointestinal tract screening standards may be warranted in CF. At the minimum these should be considered in the pre-transplant evaluation.

A novel anti-PcrV antibody providing enhanced protection against Pseudomonas aeruginosa in multiple animal infection models.

Pseudomonas aeruginosa is a major cause of hospital-acquired infections, particularly in mechanically ventilated patients, and it is the leading cause of death in cystic fibrosis patients. A key virulence factor associated with disease severity is the P. aeruginosa type III secretion system (T3SS), which injects bacterial toxins directly into the cytoplasm of host cells. The PcrV protein, located at the tip of the T3SS injectisome complex, is required for T3SS function and is a well-validated target in animal models of immunoprophylactic strategies targeting P. aeruginosa. In an effort to identify a highly potent and protective monoclonal antibody (MAb) that inhibits the T3SS, we generated and characterized a panel of novel anti-PcrV MAbs. Interestingly, some MAbs exhibiting potent inhibition of T3SS in vitro failed to provide protection in a mouse model of P. aeruginosa infection, suggesting that effective in vivo inhibition of T3SS with anti-PcrV MAbs is epitope dependent. V2L2MD, while not the most potent MAb as assessed by in vitro cytotoxicity inhibition assays, provided strong prophylactic protection in several murine infection models and a postinfection therapeutic model. V2L2MD mediated significantly (P < 0.0001) better in vivo protection than that provided by a comparator antibody, MAb166, a well-characterized anti-PcrV MAb and the progenitor of a clinical candidate, KB001-A. The results described here support further development of a V2L2MD-containing immunotherapeutic and may suggest even greater potential than was previously recognized for the prevention and treatment of P. aeruginosa infections in high-risk populations.

Impact of pulmonary hypertension on survival in patients with cystic fibrosis undergoing lung transplantation: An analysis of the UNOS registry

BackgroundPulmonary hypertension (PH) is a comorbidity reported in patients with cystic fibrosis (CF) with research limited to single-center studies. MethodsTo assess the impact of PH in patients with CF who received a lung transplant (LTx), the United Network for Organ Sharing was queried from 1987 to 2012, restricting analysis to transplant patients 6–55years old between 1/1/2005 and 7/6/2011. ResultsOf 23,951 lung transplants, 1177 met inclusion criteria with 831 having mean pulmonary artery pressure (mPAP) data available. For the entire cohort, mean age was 30.3 (SD=9.2, range 12–55), and mean mPAP was 26.5 (SD=7.8, range 5–66) mmHg. A total of 470 (57%) had PH defined as mPAP≥25mmHg. Comparing PH to non-PH groups, mean forced expiratory volume in one second (FEV1) was 24.4 (SD=13.8) vs. 26 (SD=13.9) % of predicted, mean supplemental oxygen requirement at rest was 4.5 (SD=4.1) vs. 3.7 (SD=3.0) liters per minute, and mean lung allocation score was 49 (SD=16) vs. 43 (SD=12), respectively. For the PH group, median survival was 84.4months compared to 67.1months for the non-PH group (log-rank p-value=0.326). The adjusted hazard ratio for PH vs. non-PH was 0.862 (95% CI: 0.653–1.138; p=0.293), thus indicating no statistically significant effect of PH on survival. ConclusionsA high prevalence of PH was found in CF patients prior to LTx. Based on our models despite PH being prevalent, there is no strong evidence suggesting that it significantly alters the risk of death in CF patients after LTx.

New Treatments for Emerging Cystic Fibrosis Pathogens other than Pseudomonas

The development of antimicrobial treatments for respiratory pathogens in cystic fibrosis (CF) has been an integral component to the increased survival of CF patients over the past fifty years. Despite significant treatment advances, however, respiratory failure secondary to chronic bacterial pulmonary infection remains the primary cause of death in CF patients. The purpose of this review is to discuss emerging pathogens (other than Pseudomonas) in CF by describing the characteristics of the organism, their clinical significance in CF, their mechanisms of antimicrobial resistance and the current treatment approaches including newer pharmaceutical modalities. This review will focus on the following pathogens: Burkholderia cepacia complex, Stenotrophomonas maltophilia, Achromobacter xylosoxidans, methicillin-resistant Staphylococcus aureus and nontuberculous mycobacteria The goal is to familiarize the reader with the challenges in treating pulmonary infections in CF caused by multi-drug resistant pathogens and to highlight some of the newer pharmaceutical treatments that are currently the focus of intense research.

Sustained inhibition of IL‐6 and IL‐8 expression by decoy ODN to NF‐κB delivered through respirable large porous particles in LPS‐stimulated cystic fibrosis bronchial cells

Cystic fibrosis (CF) is caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Neutrophil-dominated inflammation and chronic bacterial infection are still considered the primary cause of bronchioectasis, respiratory failure and consequent death in CF patients. Activation of nuclear factor (NF)-κB is responsible for overproduction of cytokines, such as interleukin (IL)-6 and IL-8, in airways of CF patients. Thus, decoy oligodeoxynucleotides against NF-κB (dec-ODN) may limit lung inflammation in CF. In the present study, we studied the effects of dec-ODN delivered through biodegradable and respirable poly(D,L-lactide-co-glycolide) large porous particles (LPP) on IL-6 and IL-8 mRNA expression as well as NF-κB/DNA binding activity in cystic fibrosis cells stimulated with lipopolysaccharide (LPS) from Pseudomonas aeruginosa. dec-ODN LPP were prepared by a modified double emulsion technique and characterized in terms of size, morphology, tapped density and dec-ODN loading. Human epithelial bronchial IB3-1 (CFTR-mutated) as well as S9 (CFTR-corrected) were stimulated with LPS from P. aeruginosa for 24 and 72 h in the absence or presence of naked dec-ODN or dec-ODN LPP. Stimulation of cells with LPS from P. aeruginosa caused an increase of IL-6 and IL-8 mRNA levels, which were significantly inhibited by dec-ODN LPP at 24 and 72 h, whereas naked dec-ODN inhibited those only at 24 h. Similar effects were exhibited by dec-ODN LPP or naked dec-ODN on NF-κB/DNA binding activity. Our observations indicate that respirable biodegradable dec-ODN LPP may represent a promising strategy for inhibiting NF-κB transcriptional activity and related gene expression and, thus, reduce lung chronic inflammation in CF patients.

Management of refractory Pseudomonas aeruginosa infection in cystic fibrosis

Cystic fibrosis (CF) is the most common life-limiting inherited disease in Caucasian populations. The main cause of death in CF patients is respiratory failure resulting from chronic pulmonary infection. Pseudomonas aeruginosa is the most prevalent organism in the airway colonization of CF patients, and its persistence in the airways has been related to greater morbidity with a more rapid deterioration in lung function. P. aeruginosa has enormous genetic and metabolic flexibility that allows it to adapt and persist within the airways of CF patients, and it has the ability to easily acquire antimicrobial resistance. For these reasons, the management of infections and chronic colonization by P. aeruginosa remains a challenge for physicians. This article reviews the current and future antibacterial chemotherapy options for respiratory pseudomonal infection in CF patients.

Prior diabetes mellitus is associated with increased morbidity in cystic fibrosis patients undergoing bilateral lung transplantation: an ‘orphan’ area? A retrospective case–control study

The aim of this study was to determine whether pre-existing diabetes mellitus increases the risk of rejection, infection and/or death in cystic fibrosis patients undergoing bilateral sequential single-lung transplantation. A retrospective audit of 25 consecutive patients with cystic fibrosis who underwent bilateral sequential single-lung transplantation between 1 January 2003 and 31 December 2005 at a tertiary referral hospital was carried out. Although 32% patients had diabetes diagnosed before lung transplantation, 92% had random blood glucose levels > or =11.1 mmol/L requiring insulin during admission. Patients with pre-existing diabetes had increased infection-related (3.9 vs 1.2, P= 0.01) and putative rejection-related (1.4 vs 0.5, P= 0.04) hospital admissions post-transplantation compared with those without diabetes pre-transplant. During the period of observation, four of eight patients with a prior diagnosis of diabetes died compared with none of 17 patients without prior diabetes (P= 0.0055). Almost all cystic fibrosis patients develop hyperglycaemia after lung transplantation, but patients with prior diabetes have more complication-related admissions to hospital and a higher mortality rate.

Central Role of Quorum Sensing in Regulating the Production of Pathogenicity Factors in PSeudomonas Aeruginosa

Pseudomonas aeruginosa is an important opportunistic human pathogen, causing various infections that are often very persistent. P. aeruginosa infections are the major cause of death in cystic fibrosis patients. Infections are difficult to treat since P. aeruginosa is resistant to most antibiotics and its antibiotic susceptibility is decreased when it is present in biofilms. P. aeruginosa produces many exoproducts (including toxins and hydrolytic enzymes) that are involved in virulence. Recent research has elucidated many mechanisms and pathways that regulate the production of these virulence factors. The regulation is extremely complex and many components are influenced by environmental conditions. Quorum sensing is a key regulatory system, which itself is affected by many other regulators. Targeting the regulation of pathogenicity factors provides a novel strategy for combating P. aeruginosa infections. Degradation of acyl homoserine lactones, the signaling molecules of the quorum-sensing system, is a promising therapeutic treatment option.

Pseudomonas aeruginosaprotease IV degrades surfactant proteins and inhibits surfactant host defense and biophysical functions

Pulmonary surfactant has two distinct functions within the lung: reduction of surface tension at the air-liquid interface and participation in innate host defense. Both functions are dependent on surfactant-associated proteins. Pseudomonas aeruginosa is primarily responsible for respiratory dysfunction and death in cystic fibrosis patients and is also a leading pathogen in nosocomial pneumonia. P. aeruginosa secretes a number of proteases that contribute to its virulence. We hypothesized that P. aeruginosa protease IV degrades surfactant proteins and results in a reduction in pulmonary surfactant host defense and biophysical functions. Protease IV was isolated from cultured supernatant of P. aeruginosa by gel chromatography. Incubation of cell-free bronchoalveolar lavage fluid with protease IV resulted in degradation of surfactant proteins (SP)-A, -D, and -B. SPs were degraded in a time- and dose-dependent fashion by protease IV, and degradation was inhibited by the trypsin-like serine protease inhibitor Nalpha-p-tosyl-L-lysine-chloromethyl ketone (TLCK). Degradation by protease IV inhibited SP-A- and SP-D-mediated bacterial aggregation and uptake by macrophages. Surfactant treated with protease IV was unable to reduce surface tension as effectively as untreated surfactant, and this effect was inhibited by TLCK. We speculate that protease IV may be an important contributing factor to the development and propagation of acute lung injury associated with P. aeruginosa via loss of surfactant function within the lung.

Cystic Fibrosis: End-Stage Care in Canada

To determine the circumstances in which individuals with cystic fibrosis (CF) die, the role of different caregivers, and the extent of palliative care for CF patients. Mailed survey of CF physicians. CF centers in Canada. All CF deaths in 1996 known to centers in Canada. The mean age (+/- SD) at death of the 45 individuals included in the study was 25.8 +/- 13.5 years. The major cause of death was respiratory (34 patients; 75.5%). Nutritional concerns were common. Lung transplantation was considered in 42 patients (93.2%), with 7 patients (17.1%) being entered on a list, but it was carried out in only 2 patients (4.4%). Autopsies were performed on only 10 patients (22.2%). Most patients died in hospital (37 patients; 82.2%), and 7 patients (15.6%) died in ICUs while receiving intermittent positive-pressure ventilation. Palliative care was never discussed in 10 patients (25%). In a further 16 patients (40%), it was not discussed until the last month before death. Respiratory disease remains the most common cause of death in CF patients. Lung transplantation is frequently considered, but most patients die without having had a transplant. Discussions on end-of-life care could be considered sooner.

Risk of Death in Cystic Fibrosis Patients With Severely Compromised Lung Function

Lung disease accounts for most of the mortality in patients with cystic fibrosis (CF). Lung transplantation is an option for patients severely impaired, being recommended when life expectancy is estimated to be <2 years. Our objectives were to evaluate in our patient population the validity of currently accepted criteria for low life expectancy and to identify other potentially useful criteria. Data were retrieved from CF patients followed up at our center who reached and kept an FEV1 <30% predicted. A life table was created and stratified according to characteristics believed to be of importance. In addition, the rate of decline in percent predicted FEV1 was analyzed. These characteristics were evaluated as predictors of risk of death. The median survival was 3.9 years (95% confidence interval, 2.88 to 4.12 years), with no significant differences according to gender, nutritional status, presence of diabetes, or decade in which the patient was cared for. Only by age was there a significant difference in the median survival (p<0.05). By proportional hazards regression, only the rate of decline in percent predicted FEV1 was a significant predictor of the risk of death, with a borderline effect from younger age (p=0.06). In our patient population, a cutoff value of FEV1 of < 30% predicted is not a reliable predictor of high risk of death within 2 years. The yearly rate of decline of percent predicted FEV1 is a better parameter to identify those patients at high risk for death.