Search tips
Search criteria

Results 1-8 (8)

Clipboard (0)

Select a Filter Below

Year of Publication
Document Types
1.  Survival of patients with cystic fibrosis on ECMO: analysis of the Extracorporeal Life Support Organization Registry 
Progressive respiratory failure is a common cause of death in patients with cystic fibrosis (CF). Although this may be related to the disease process itself, acute infectious problems may lead to respiratory failure requiring mechanical ventilation. Given the progressive nature of the disorder, some have suggested that the use of extracorporeal membrane oxygenation (ECMO) is contraindicated. The current study retrospectively reviewed the Extracorporeal Life Support Organization (ELSO) Registry to evaluate the outcomes following the use of ECMO in patients with CF. A total of 73 ECMO runs were identified in CF patients. There were 33 who received VV ECMO, 32 on VA ECMO, and 8 who received combined VA and VA ECMO. The overall survival rate for the cohort was 52% (38 of 73 patients). There was no difference in survival when comparing VA and VV ECMO. We noted an increasing trend for VV ECMO for this patient population over this time period. These data further support the need for a prospective study to evaluate outcomes following ECMO in this population with standardization of care across multiple centers.
PMCID: PMC4073758  PMID: 24995097
Cystic fibrosis; extracorporeal membrane oxygenation; survival; venoarterial; venovenous
2.  IFN-γ Stimulates Autophagy-Mediated Clearance of Burkholderia cenocepacia in Human Cystic Fibrosis Macrophages 
PLoS ONE  2014;9(5):e96681.
Burkholderia cenocepacia is a virulent pathogen that causes significant morbidity and mortality in patients with cystic fibrosis (CF), survives intracellularly in macrophages, and uniquely causes systemic infections in CF. Autophagy is a physiologic process that involves engulfing non-functional organelles and proteins and delivering them for lysosomal degradation, but also plays a role in eliminating intracellular pathogens, including B. cenocepacia. Autophagy is defective in CF but can be stimulated in murine CF models leading to increased clearance of B. cenocepacia, but little is known about autophagy stimulation in human CF macrophages. IFN-γ activates macrophages and increases antigen presentation while also inducing autophagy in macrophages. We therefore, hypothesized that treatment with IFN-γ would increase autophagy and macrophage activation in patients with CF. Peripheral blood monocyte derived macrophages (MDMs) were obtained from CF and non-CF donors and subsequently infected with B. cenocepacia. Basal serum levels of IFN-γ were similar between CF and non-CF patients, however after B. cenocepacia infection there is deficient IFN-γ production in CF MDMs. IFN-γ treated CF MDMs demonstrate increased co-localization with the autophagy molecule p62, increased autophagosome formation, and increased trafficking to lysosomes compared to untreated CF MDMs. Electron microscopy confirmed IFN-γ promotes double membrane vacuole formation around bacteria in CF MDMs, while only single membrane vacuoles form in untreated CF cells. Bacterial burden is significantly reduced in autophagy stimulated CF MDMs, comparable to non-CF levels. IL-1β production is decreased in CF MDMs after IFN-γ treatment. Together, these results demonstrate that IFN-γ promotes autophagy-mediated clearance of B. cenocepacia in human CF macrophages.
PMCID: PMC4010498  PMID: 24798083
3.  Respiratory syncytial virus: current and emerging treatment options 
Respiratory syncytial virus (RSV) is an important respiratory pathogen in infants and children worldwide. Although RSV typically causes mild upper respiratory infections, it frequently causes severe morbidity and mortality, especially in premature infants and children with other chronic diseases. Treatment of RSV is limited by a lack of effective antiviral treatments; however, ribavirin has been used in complicated cases, along with the addition of intravenous immune globulin in specific patients. Vaccination strategies for RSV prevention are heavily studied, but only palivizumab (Synagis®) has been approved for use in the United States in very select patient populations. Research is ongoing in developing additional vaccines, along with alternative therapies that may help prevent or decrease the severity of RSV infections in infants and children. To date, we have not seen a decrement in RSV morbidity and mortality with our current options; therefore, there is a clear need for novel RSV preventative and therapeutic strategies. In this review, we discuss the current and evolving trends in RSV treatment for infants and children.
PMCID: PMC4008286  PMID: 24812523
bronchiolitis; lower respiratory tract infection; respiratory syncytial virus; probiotics; vitamin D
4.  Cationic Antimicrobial Peptides Promote Microbial Mutagenesis and Pathoadaptation in Chronic Infections 
PLoS Pathogens  2014;10(4):e1004083.
Acquisition of adaptive mutations is essential for microbial persistence during chronic infections. This is particularly evident during chronic Pseudomonas aeruginosa lung infections in cystic fibrosis (CF) patients. Thus far, mutagenesis has been attributed to the generation of reactive species by polymorphonucleocytes (PMN) and antibiotic treatment. However, our current studies of mutagenesis leading to P. aeruginosa mucoid conversion have revealed a potential new mutagen. Our findings confirmed the current view that reactive oxygen species can promote mucoidy in vitro, but revealed PMNs are proficient at inducing mucoid conversion in the absence of an oxidative burst. This led to the discovery that cationic antimicrobial peptides can be mutagenic and promote mucoidy. Of specific interest was the human cathelicidin LL-37, canonically known to disrupt bacterial membranes leading to cell death. An alternative role was revealed at sub-inhibitory concentrations, where LL-37 was found to induce mutations within the mucA gene encoding a negative regulator of mucoidy and to promote rifampin resistance in both P. aeruginosa and Escherichia coli. The mechanism of mutagenesis was found to be dependent upon sub-inhibitory concentrations of LL-37 entering the bacterial cytosol and binding to DNA. LL-37/DNA interactions then promote translesion DNA synthesis by the polymerase DinB, whose error-prone replication potentiates the mutations. A model of LL-37 bound to DNA was generated, which reveals amino termini α-helices of dimerized LL-37 bind the major groove of DNA, with numerous DNA contacts made by LL-37 basic residues. This demonstrates a mutagenic role for antimicrobials previously thought to be insusceptible to resistance by mutation, highlighting a need to further investigate their role in evolution and pathoadaptation in chronic infections.
Author Summary
Antimicrobial peptides (AMPs) are produced by the mammalian immune system to fight invading pathogens. The best understood function of AMPs is to interact with the membranes of microbes, thereby disrupting and killing cells. However, the amount of AMP available during chronic bacterial infections may not be sufficient to kill pathogens (sub-inhibitory). In this study, we found that at sub-inhibitory levels, AMPs promote mutations in bacterial DNA, a function not previously attributed to them. In particular, we found that in the bacteria Pseudomonas aeruginosa, one AMP called LL-37 can promote mutations, which enable the bacteria to overproduce a protective sugar coating, a process called mucoid conversion. P. aeruginosa mucoid conversion is a major risk factor for those suffering from cystic fibrosis (CF), the most common lethal, heritable disease in the US. We found that LL-37 is able to produce these mutations by penetrating the bacterial cell and binding to the bacterial DNA. DNA binding disrupts normal DNA replication and allows mutations to occur. Furthermore, we observed LL-37 induced mutagenesis in processes apart from mucoid conversion, in both P. aeruginosa and E. coli. This suggests that AMP-induced mutagenesis may be important for a broad range of chronic diseases and pathogens.
PMCID: PMC3999168  PMID: 24763694
5.  Inpatient Healthcare Trends Among Adult Cystic Fibrosis Patients in the U.S 
Pediatric pulmonology  2011;47(3):245-251.
Adult cystic fibrosis (CF) patients are an expanding cohort that is taken care of in a variety of hospital settings including adult centers located within pediatric institutions. This study compared costs and discharge rates among adult CF patient hospitalizations in terms of location of hospitalization.
The 2007 Nationwide Inpatient Sample was utilized to identify adult CF patient admission data on patients aged 18–44. Data were separated into pediatric and adult facilities based on percentage discharge rate for patients >18. Primary outcomes measures were length of stay (LOS) and total hospital charges. Secondary predictors were geographic, primary payer, and co-morbidity effects on LOS and total hospital charges.
LOS was higher for adult CF patient admissions in pediatric facilities compared to adult facilities by a mean of 2.5 days. Mean total hospital charges were not significantly different. Adult hospitals in the Western U.S. had a mean total charge more than $50,000 greater than any region in the U.S. Self-pay patients had significantly fewer hospital days and charges across all hospital types. Adult facilities had 7% more CF patients discharged home with home healthcare use. Depressed CF patients had longer LOS by 1.5 days regardless of facility type.
LOS for adult CF inpatient admissions was significantly lower in adult facilities compared to pediatric facilities without a significant difference in hospital charges and is influenced by geographic hospital location. Depressed patients had longer lengths of stay regardless of facility type. Self-insured adult CF patients have a significant reduction in LOS and hospital charges when compared to all other payers regardless of hospital type.
PMCID: PMC3805019  PMID: 21901854
healthcare utilization; socioeconomic factors; geographic factors
Cystic Fibrosis (CF) is accompanied with heightened inflammation worsened by drug resistant Burkholderia cenocepacia. Human CF macrophage responses to B. cenocepacia are poorly characterized and variable in the literature. Therefore, we examined human macrophage responses to the epidemic B. cenocepacia J2315 strain in order to identify novel anti-inflammatory targets. Peripheral blood monocyte derived macrophages were obtained from 23 CF and 27 non-CF donors. Macrophages were infected with B. cenocepacia J2315 and analyzed for cytokines, cytotoxicity, and microscopy. CF macrophages demonstrated significant increases in IL-1β, IL-10, MCP-1, and IFN-γ production in comparison to non-CF controls. CF patients on prednisone exhibited globally diminished cytokines compared to controls and other CF patients. CF macrophages also displayed increased bacterial burden and cell death. In conclusion, CF macrophages demonstrate exaggerated IL-1β, IL-10, MCP-1, and IFN-γ production and cell death during B. cenocepacia infection. Treatment with corticosteroids acutely suppressed cytokine responses.
PMCID: PMC3408781  PMID: 22728038
cystic fibrosis; burkholderia; macrophage; IL-1β; corticosteroids
7.  Elevated high-sensitivity C-reactive protein in preterm infants with pulmonary colonization with Ureaplasma 
Journal of Thoracic Disease  2013;5(3):223-227.
A link between pulmonary Ureaplasma spp. colonization in premature infants and bronchopulmonary dysplasia (BPD) exists and could possibly contribute to systemic inflammation.
A prospective cohort study was performed from July 2006 to July 2007 where very low birth weight (VLBW) premature infants were screened at birth. Serum and tracheal aspirate samples were collected during the first 28 days of life that represented the early high-sensitivity C-reactive protein (hs-CRP) group, and follow-up samples obtained between 28-42 days of life were the late hs-CRP group. An Enzyme-linked immunosorbent assay (ELISA) for hs-CRP was performed on serum samples while tracheal aspirates underwent polymerase chain reaction (PCR) analysis for Ureaplasma spp.
A total of 65 patients were screened. 30 patients completed full analysis, 15 died before early and late hs-CRP samples could be obtained, and 20 had incomplete data due to early discharge or transfer. There was no significant difference between all early and late hs-CRP group levels (mg/L), median [interquartile range] 1.019 [0.242, 5.844] vs. 0.773 [0.143, 8.954] (P=0.3958); however, there was a significant difference when comparing Ureaplasma spp. positivity vs. negativity between both groups, median 2.223 [0.398, 7.099] vs. 0.675 [0.219, 4.038] (P=0.0131) for the early group and median 2.335 [0.359, 14.91] vs. 0.2155 [0.122, 2.296] (P=0.03) for the late group, respectively.
VLBW premature infants colonized with Ureaplasma spp. have an elevated hs-CRP, suggestive of a chronic low-grade systemic inflammatory response.
PMCID: PMC3698281  PMID: 23825751
High-sensitivity C-reactive protein (hs-CRP); Ureaplasma; preterm infant; bronchopulmonary dysplasia (BPD)
8.  Autophagy stimulation by rapamycin suppresses lung inflammation and infection by Burkholderia cenocepacia in a model of cystic fibrosis 
Autophagy  2011;7(11):1359-1370.
Cystic fibrosis (CF) is the most common inherited lethal disease in Caucasians which results in multiorgan dysfunction. However, 85% of the deaths are due to pulmonary infections. Infection by Burkholderia cenocepacia (B. cepacia) is a particularly lethal threat to CF patients because it causes severe and persistent lung inflammation and is resistant to nearly all available antibiotics. In CFTR ΔF508 (ΔF508) mouse macrophages, B. cepacia persists in vacuoles that do not fuse with the lysosomes and mediates increased production of IL-1β. It is believed that intracellular bacterial survival contributes to the persistence of the bacterium. Here we show for the first time that in wild-type but not in ΔF508 macrophages, many B. cepacia reside in autophagosomes that fuse with lysosomes at later stages of infection. Accordingly, association and intracellular survival of B. cepacia are higher in CFTR-ΔF508 macrophages than in WT macrophages. An autophagosome is a compartment that engulfs nonfunctional organelles and parts of the cytoplasm then delivers them to the lysosome for degradation to produce nutrients during periods of starvation or stress. Furthermore, we show that B. cepacia downregulates autophagy genes in WT and ΔF508 macrophages. However, autophagy dysfunction is more pronounced in ΔF508 macrophages since they already have compromised autophagy activity. We demonstrate that the autophagystimulating agent, rapamycin markedly decreases B. cepacia infection in vitro by enhancing the clearance of B. cepacia via induced autophagy. In vivo, rapamycin decreases bacterial burden in the lungs of CF mice and drastically reduces signs of lung inflammation. Together, our studies reveal that if efficiently activated, autophagy can control B. cepacia infection and ameliorate the associated inflammation. Therefore, autophagy is a novel target for new drug development for CF patients to control B. cepacia infection and accompanying inflammation.
PMCID: PMC3359483  PMID: 21997369
autophagy; rapamycin; cystic fibrosis; host-pathogen interaction; Burkholderia cenocepacia; inflammation; macrophages

Results 1-8 (8)