Project description:Background: Whereas cilia damage and reduced cilia beat frequency have been implicated as causative of reduced mucociliary clearance in smokers, theoretically mucociliary clearance could also be affected by cilia length. Based on models of mucociliary clearance predicting cilia length must exceed the 6 -7 μm airway surface fluid depth to generate force in the mucus layer, we hypothesized cilia height may be decreased in airway epithelium of normal smokers compared to nonsmokers. Methodology/Principal Findings: Cilia length in normal nonsmokers and smokers was evaluated in aldehyde-fixed, paraffin-embedded endobronchial biopsies, and air-dried and hydrated samples brushed from human airway epithelium via fiberoptic bronchoscopy. In 28 endobronchial biopsies, healthy smoker cilia length was reduced 15% compared to nonsmokers (p<0.05). In 47 air-dried samples of airway epithelial cells, smoker cilia length was reduced 13% compared to nonsmokers (p<0.0001). Analysis of the length of individual, detached cilia in 17 samples, smoker cilia length was reduced 9% compared to nonsmokers (p<0.05). Finally, in 16 fully hydrated, unfixed samples, smoker cilia length was reduced 7% compared to nonsmokers (p<0.05). Conclusions/significance: Models predict that a reduction in cilia length would reduce mucociliary clearance, suggesting that smoking-associated shorter airway epithelial cilia plays a significant role in the pathogenesis of smoking-induced lung disease.
Project description:Study Smoking and COPD are associated with decreased mucociliary clearance and healthy smokers have shorter cilia in the large airway than nonsmokers. Intraflagellar transport (IFT) is the process by which cilia are produced and maintained. We assessed expression of IFT-related genes in smokers and nonsmokers and evaluated cilia length in the large and small airway of nonsmokers, healthy smokers, and smokers with COPD. Methods Airway epithelium was obtained via bronchoscopic brushing. Affymetrix microarrays were used to evaluate IFT gene expression in 2 independent data sets from large and small airway. Cilia length was assessed by measuring 100 cilia (10 cilia on each of 10 cells) per subject. Results All 40 IFT genes were expressed in the human large and small airway epithelium. In the large airway, 10 IFT genes were down-regulated and 1 up-regulated in smokers. In the small airway, 11 genes were down-regulated and 3 up-regulated in smokers. A set of 8 IFT genes was down-regulated in both data sets. In the large and small airway epithelium, cilia were significantly shorter in healthy smokers than nonsmokers, and significantly shorter in COPD smokers than in both healthy smokers and nonsmokers. Answer to the Question These results support the concept that loss of cilia length contributes to defective mucociliary clearance in COPD, and that smoking-induced changes in expression of IFT genes may be one mechanism of abnormally short cilia in smokers. Strategies to normalize cilia length may be an important avenue for novel COPD therapies. Gene expression was assessed for 40 intraflagellar transport related genes in the LAE of nonsmokers (n=21) and healthy smokers (n=31) and the SAE of an independent group of nonsmokers (n=28) and healthy smokers (n=69). Cilia length was assessed in a total of 228 airway epithelium samples, including 120 LAE samples and 108 SAE samples; a subset of the 228 samples is represented among the 149 samples in this Series.
Project description:Study Smoking and COPD are associated with decreased mucociliary clearance and healthy smokers have shorter cilia in the large airway than nonsmokers. Intraflagellar transport (IFT) is the process by which cilia are produced and maintained. We assessed expression of IFT-related genes in smokers and nonsmokers and evaluated cilia length in the large and small airway of nonsmokers, healthy smokers, and smokers with COPD. Methods Airway epithelium was obtained via bronchoscopic brushing. Affymetrix microarrays were used to evaluate IFT gene expression in 2 independent data sets from large and small airway. Cilia length was assessed by measuring 100 cilia (10 cilia on each of 10 cells) per subject. Results All 40 IFT genes were expressed in the human large and small airway epithelium. In the large airway, 10 IFT genes were down-regulated and 1 up-regulated in smokers. In the small airway, 11 genes were down-regulated and 3 up-regulated in smokers. A set of 8 IFT genes was down-regulated in both data sets. In the large and small airway epithelium, cilia were significantly shorter in healthy smokers than nonsmokers, and significantly shorter in COPD smokers than in both healthy smokers and nonsmokers. Answer to the Question These results support the concept that loss of cilia length contributes to defective mucociliary clearance in COPD, and that smoking-induced changes in expression of IFT genes may be one mechanism of abnormally short cilia in smokers. Strategies to normalize cilia length may be an important avenue for novel COPD therapies.
Project description:Aging involves multiple biologically complex processes characterized by a decline in cellular homeostasis over time leading to a loss and impairment of physiological integrity and function. Specific cellular hallmarks of aging include abnormal gene expression patterns, shortened telomeres and associated biological dysfunction. Like all organs, the lung demonstrates both physiological and structural changes with age that result in a progressive decrease in lung function in healthy individuals. Cigarette smoking accelerates lung function decline over time, suggesting smoking accelerates aging of the lung. Based on this data, we hypothesized that cigarette smoking accelerates the aging of the small airway epithelium, the cells that take the initial brunt of inhaled toxins from the cigarette smoke and one of the primary sites of pathology associated with cigarette smoking. Using the sensitive molecular parameters of aging-related gene expression and telomere length, the aging process of the small airway epithelium was assessed in age matched healthy nonsmokers and healthy smokers with no physical manifestation of lung disease or abnormalities in lung function. Analysis of a 73 gene aging signature demonstrated that smoking significantly dysregulates 18 aging-related genes in the small airway epithelium. In an independent cohort of male subjects, smoking significantly reduced telomere length in the small airway epithelium of smokers by 14% compared to nonsmokers. These data provide biologic evidence that prior to the clinical manifestation of lung disease; smoking accelerates aging of the small airway epithelium.
Project description:Differential profiles from whole genome human expression arrays on monocytes obtained from peripheral blood in COPD was studied and compared with controls. Monocytes were isolated from Controls (Group 1) which included Control Smokers (Group 1A) and Control Never Smokers (Group 1B) and COPD (Group 2) which included COPD Smokers (Group 2A) and COPD ExSmokers (Group 2B). Differential transcriptomic expression associated with (i) Smoking, (ii) COPD, and (iii) cessation of smoking were identified.
Project description:Kynureninase is a member of a large family of catalytically diverse but structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes known as the aspartate aminotransferase superfamily or alpha-family. The Homo sapiens and other eukaryotic constitutive kynureninases preferentially catalyze the hydrolytic cleavage of 3-hydroxy-l-kynurenine to produce 3-hydroxyanthranilate and l-alanine, while l-kynurenine is the substrate of many prokaryotic inducible kynureninases. The human enzyme was cloned with an N-terminal hexahistidine tag, expressed, and purified from a bacterial expression system using Ni metal ion affinity chromatography. Kinetic characterization of the recombinant enzyme reveals classic Michaelis-Menten behavior, with a Km of 28.3 +/- 1.9 microM and a specific activity of 1.75 micromol min-1 mg-1 for 3-hydroxy-dl-kynurenine. Crystals of recombinant kynureninase that diffracted to 2.0 A were obtained, and the atomic structure of the PLP-bound holoenzyme was determined by molecular replacement using the Pseudomonas fluorescens kynureninase structure (PDB entry 1qz9) as the phasing model. A structural superposition with the P. fluorescens kynureninase revealed that these two structures resemble the "open" and "closed" conformations of aspartate aminotransferase. The comparison illustrates the dynamic nature of these proteins' small domains and reveals a role for Arg-434 similar to its role in other AAT alpha-family members. Docking of 3-hydroxy-l-kynurenine into the human kynureninase active site suggests that Asn-333 and His-102 are involved in substrate binding and molecular discrimination between inducible and constitutive kynureninase substrates.