ABSTRACT
Cystic fibrosis is a genetic disorder characterized by recurrent airway infections, inflammation, impaired mucociliary clearance and progressive decline in lung function. The disease may start in the small airways; however, this is difficult to prove due to limited accessibility of the small airways with the current single photon mucociliary clearance assay. Here, we developed a dynamic positron emission tomography assay with high spatial and temporal resolution. We tested that mucociliary clearance is abnormal in the small airways of newborn cystic fibrosis pigs. Clearance of [68Ga] tagged macro-aggregated albumin from small airways started immediately after delivery and continued for the duration of the study. Initial clearance was fast but slowed down few minutes after delivery. Cystic fibrosis pig small airways cleared significantly less than non-CF pig small airways (non-CF 25.1±3.1% vs. CF 14.6±0.1%). Stimulation of the cystic fibrosis airways with the purinergic secretagogue UTP further impaired clearance (non-CF with UTP 20.9±0.3% vs. CF with UTP 13.0±1.8%). None of the cystic fibrosis pig treated with UTP (N = 6) cleared more than 20% of the delivered dose. These data indicate that mucociliary clearance in the small airways is fast and can easily be missed if the assay is not sensitive enough. The data also indicate that mucociliary clearance is impaired in the small airways of cystic fibrosis pigs. This defect is exacerbated by stimulation of mucus secretions with purinergic agonists.
ABSTRACT
Neuroestrogens locally synthesized in the brain are known to play a role in sexual behaviors. However, the question of whether neuroestrogens are involved in the regulation of the gonadotropin-releasing hormone (GnRH) release is just emerging. Because previous studies in this lab indicate that neuroestradiol is also important for the pulsatile release as well as the surge release of GnRH in female rhesus monkeys, in the present study, we examined whether neuroestradiol plays a role in the estrogen-induced LH surge in orchidectomized (ORX) male rhesus monkeys. Unlike in rodents, it is known that a high dose of estrogen treatment can result in the LH surge in ORX male rhesus monkeys. Results that the administration of the aromatase inhibitor, letrozole, failed to attenuate the estrogen-induced LH surge, suggest that unlike in ovariectomized females, neuroestrogens do not play a role in the LH surge experimentally induced by the exogenous estrogen treatment in ORX male monkeys.
ABSTRACT
The 5/6 nephrectomy rat remnant kidney model is commonly used to study chronic kidney disease (CKD). This model requires the removal of one whole kidney and two-thirds of the other kidney. The two most common ways of producing the remnant kidney are surgical resection of poles, known as the polectomy model, or ligation of superior and inferior segmental renal arteries, resulting in pole infarction. These models have much in common, but also major phenotypic differences, and thus respectively model unique aspects of human CKD. The purpose of this review is to summarize phenotypic similarities and differences between these two models and their relation to human CKD while emphasizing their vascular phenotype. In this article, we review studies that have evaluated arterial blood pressure, the renin-angiotensin-aldosterone-system, autoregulation, nitric oxide, single-nephron physiology, angiogenic and antiangiogenic factors, and capillary rarefaction in these two models. In terms of phenotypic similarities, both models spontaneously develop hallmarks of human CKD including uremia, fibrosis, capillary rarefaction, and progressive renal function decline. They both undergo whole organ hypertrophy, hyperfiltration of functional nephrons, reduced renal expression of vascular endothelial growth factor, increased renal expression of antiangiogenic thrombospondin-1, impaired renal autoregulation, and abnormal vascular nitric oxide physiology. In terms of key phenotypic differences, the infarction model develops rapid-onset, moderate to severe systemic hypertension and the polectomy model develops early normotension followed by mild to moderate hypertension. Rats subjected to the infarction model have a markedly more active renin-angiotensin-aldosterone system. Comparison of these two models facilitates understanding of how they can be used for studying CKD pathophysiology.
Subject(s)
Hypertension , Microvascular Rarefaction , Renal Insufficiency, Chronic , Animals , Disease Models, Animal , Female , Humans , Infarction , Kidney/surgery , Male , Nephrectomy/methods , Nitric Oxide , Rats , Vascular Endothelial Growth Factor AABSTRACT
Rationale: Although it is clear that cystic fibrosis (CF) airway disease begins at a very young age, the early and subsequent steps in disease pathogenesis and the relative contribution of infection, mucus, and inflammation are not well understood. Objectives: As one approach to assessing the early contribution of infection, we tested the hypothesis that early and continuous antibiotics would decrease the airway bacterial burden. We believed that, if they do, this might reveal aspects of the disease that are more or less sensitive to decreasing infection. Methods: Three groups of pigs were studied from birth until â¼3 weeks of age: 1) wild-type, 2) CF, and 3) CF pigs treated continuously with broad-spectrum antibiotics from birth until study completion. Disease was assessed with chest computed tomography, histopathology, microbiology, and BAL. Measurements and Main Results: Disease was present by 3 weeks of age in CF pigs. Continuous antibiotics from birth improved chest computed tomography imaging abnormalities and airway mucus accumulation but not airway inflammation in the CF pig model. However, reducing bacterial infection did not improve two disease features already present at birth in CF pigs: air trapping and submucosal gland duct plugging. In the CF sinuses, antibiotics did not prevent the development of infection or disease or the number of bacteria but did alter the bacterial species. Conclusions: These findings suggest that CF airway disease begins immediately after birth and that early and continuous antibiotics impact some, but not all, aspects of CF lung disease development.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Cystic Fibrosis/drug therapy , Cystic Fibrosis/microbiology , Lung/drug effects , Respiratory Mucosa/drug effects , Animals , Anti-Bacterial Agents/therapeutic use , Bacteria/isolation & purification , Bronchoalveolar Lavage Fluid/microbiology , Cystic Fibrosis/diagnostic imaging , Cystic Fibrosis/pathology , Lung/diagnostic imaging , Lung/microbiology , Lung/pathology , Multidetector Computed Tomography , Respiratory Mucosa/microbiology , Respiratory Mucosa/pathology , SwineABSTRACT
AIM: Patients suffering from acute lung injury (ALI) are at high risk of developing cardiac arrhythmias. We hypothesized that stellate ganglia (SG) neural inflammation contributes to ALI-induced arrhythmia. METHODS: We created an ALI rat model using a single tracheal instillation of bleomycin (2.5 mg/kg), with saline as a sham control. We recorded ECGs by implanted radiotelemetry in male bleomycin and sham rats treated with and without oral minocycline (20 mg/kg/d), an anti-inflammatory drug that inhibits microglia/macrophage activation. The SG neuronal excitability was assessed by electrophysiology experiments. RESULTS: ECG data showed that bleomycin-exposed rats exhibited significantly more spontaneous premature ventricular contractions (PVCs) from 1- to 3-week post-induction compared with sham rats, which was mitigated by chronic oral administration of minocycline. The bleomycin-exposed rats displayed a robust increase in both the number of Iba1-positive macrophages and protein expression of interferon regulatory factor 8 in the SG starting as early at 1-week post-exposure and lasted for at least 4 weeks, which was largely attenuated by minocycline. Heart rate variability analysis indicated autonomic imbalance during the first 2-week post-bleomycin, which was significantly attenuated by minocycline. Electrical stimulation of the decentralized SG triggered more PVCs in bleomycin-exposed rats than sham and bleomycin + minocycline rats. Patch-clamp data demonstrated enhanced SG neuronal excitability in the bleomycin-exposed rats, which was attenuated by minocycline. Co-culture of lipopolysaccharide (LPS)-pretreated macrophages with normal SG neurons enhanced SG neuronal excitability. CONCLUSION: Macrophage activation in the SG contributes to arrhythmogenesis in bleomycin-induced ALI in male rats.
Subject(s)
Lung Injury , Animals , Arrhythmias, Cardiac/chemically induced , Bleomycin/toxicity , Humans , Lung , Macrophage Activation , Male , Microglia , Rats , Stellate GanglionABSTRACT
BACKGROUND: The 5/6 nephrectomy (5/6Nx) rat model recapitulates many elements of human CKD. Within weeks of surgery, 5/6Nx rats spontaneously exhibit proximal tubular damage, including the production of very large extracellular vesicles and brush border shedding. We hypothesized that production and elimination of these structures, termed large renal tubular extracellular vesicles (LRT-EVs), into the urine represents a pathologic mechanism by which essential tubule proteins are lost. METHODS: LRT-EVs were isolated from 5/6Nx rat urine 10 weeks after surgery. LRT-EV diameters were measured. LRT-EV proteomic analysis was performed by tandem mass spectrometry. Data are available via the ProteomeXchange Consortium with identifier PXD019207. Kidney tissue pathology was evaluated by trichrome staining, TUNEL staining, and immunohistochemistry. RESULTS: LRT-EV size and a lack of TUNEL staining in 5/6Nx rats suggest LRT-EVs to be distinct from exosomes, microvesicles, and apoptotic bodies. LRT-EVs contained many proximal tubule proteins that, upon disruption, are known to contribute to CKD pathologic hallmarks. Select proteins included aquaporin 1, 16 members of the solute carrier family, basolateral Na+/K+-ATPase subunit ATP1A1, megalin, cubilin, and sodium-glucose cotransporters (SLC5A1 and SLC5A2). Histologic analysis confirmed the presence of apical membrane proteins in LRT-EVs and brush border loss in 5/6Nx rats. CONCLUSIONS: This study provides comprehensive proteomic analysis of a previously unreported category of extracellular vesicles associated with chronic renal stress. Because LRT-EVs contain proteins responsible for essential renal functions known to be compromised in CKD, their formation and excretion may represent an underappreciated pathogenic mechanism.
Subject(s)
Exosomes , Extracellular Vesicles , Renal Insufficiency, Chronic , Animals , Extracellular Vesicles/chemistry , Kidney/metabolism , Proteomics , Rats , Renal Insufficiency, Chronic/metabolismABSTRACT
Excessive sympathoexcitation characterizes the chronic heart failure (CHF) state. An exaggerated cardiac sympathetic afferent reflex (CSAR) contributes to this sympathoexcitation. Prior studies have demonstrated that the CSAR to capsaicin [transient receptor potential (TRP) vanilloid 1 agonist] is exaggerated in CHF animal models. We recently discovered that capsaicin application to the lung visceral pleura in anesthetized, vagotomized, open-chested rats increases mean arterial pressure (MAP), heart rate (HR), and renal sympathetic nerve activity (RSNA). We named this response the pulmonary spinal afferent reflex (PSAR). Due to the similarities between TRP vanilloid 1 and TRP ankyrin 1 (TRPA1) channels as well as the excessive sympathoexcitation of CHF, we hypothesized that stimulation of the CSAR and PSAR with a specific TRPA1 agonist would result in an augmented response in CHF rats (coronary ligation model) compared with sham control rats. In response to a TRPA1 agonist, both CSAR and PSAR in sham rats resulted in biphasic changes in MAP and increases in HR and RSNA 10-12 wk postmyocardial infarction (post-MI). These effects were blunted in CHF rats. Assessment of TRPA1 expression levels in cardiopulmonary spinal afferents by immunofluorescence, quantitative RT-PCR, and Western blot analysis 10-12 wk post-MI all indicates reduced expression in CHF rats but no reduction at earlier time points. TRPA1 protein was reduced in a dorsal root ganglia cell culture model of inflammation and simulated tissue ischemia, raising the possibility that the in vivo reduction of TRPA1 expression was, in part, caused by CHF-related tissue ischemia and inflammation. These data provide evidence that reflex responses to cardiopulmonary spinal afferent TRPA1 stimulation may be attenuated in CHF rather than enhanced. NEW & NOTEWORTHY Excessive sympathoexcitation characterizes chronic heart failure (CHF). The contribution of transient receptor potential ankyrin 1 (TRPA1) channel-mediated reflexes to this sympathoexcitation is unknown. We found that application of TRPA1 agonist to the heart and lung surface resulted in increased heart rate and sympathetic output and a biphasic change in mean arterial pressure in control rats. These effects were attenuated in CHF rats, decreasing the likelihood that TRPA1 channels contribute to cardiopulmonary afferent sensitization in CHF.
Subject(s)
Afferent Pathways/physiopathology , Heart Failure/physiopathology , Heart/innervation , Heart/physiopathology , Lung/innervation , Lung/physiopathology , Sympathetic Nervous System/physiopathology , TRPA1 Cation Channel/agonists , Animals , Arterial Pressure , Chronic Disease , Ganglia, Spinal/metabolism , Heart Rate , Hemodynamics , Myocardial Infarction/physiopathology , Rats , Rats, Sprague-Dawley , Reflex/drug effectsABSTRACT
Loss of cystic fibrosis transmembrane conductance regulator (CFTR) function causes cystic fibrosis (CF), predisposing the lungs to chronic infection and inflammation. In young infants with CF, structural airway defects are increasingly recognized before the onset of significant lung disease, which suggests a developmental origin and a possible role in lung disease pathogenesis. The role(s) of CFTR in lung development is unclear and developmental studies in humans with CF are not feasible. Young CF pigs have structural airway changes and develop spontaneous postnatal lung disease similar to humans; therefore, we studied lung development in the pig model (non-CF and CF). CF trachea and proximal airways had structural lesions detectable as early as pseudoglandular development. At this early developmental stage, budding CF airways had smaller, hypo-distended lumens compared to non-CF airways. Non-CF lung explants exhibited airway lumen distension in response to forskolin/IBMX as well as to fibroblast growth factor (FGF)-10, consistent with CFTR-dependent anion transport/secretion, but this was lacking in CF airways. We studied primary pig airway epithelial cell cultures and found that FGF10 increased cellular proliferation (non-CF and CF) and CFTR expression/function (in non-CF only). In pseudoglandular stage lung tissue, CFTR protein was exclusively localized to the leading edges of budding airways in non-CF (but not CF) lungs. This discreet microanatomic localization of CFTR is consistent with the site, during branching morphogenesis, where airway epithelia are responsive to FGF10 regulation. In summary, our results suggest that the CF proximal airway defects originate during branching morphogenesis and that the lack of CFTR-dependent anion transport/liquid secretion likely contributes to these hypo-distended airways.
Subject(s)
Cystic Fibrosis Transmembrane Conductance Regulator/physiology , Lung/embryology , Animals , Cells, Cultured , Cyclic AMP/physiology , Cystic Fibrosis Transmembrane Conductance Regulator/analysis , Female , Fibroblast Growth Factor 10/physiology , Humans , Morphogenesis , Swine , Trachea/abnormalitiesABSTRACT
OBJECTIVES: To determine the feasibility of using a cystic fibrosis transmembrane conductance regulator potentiator, ivacaftor (VX-770/Kalydeco, Vertex Pharmaceuticals, Boston, MA), as a therapeutic strategy for treating pulmonary edema. DESIGN: Prospective laboratory animal investigation. SETTING: Animal research laboratory. SUBJECTS: Newborn and 3 days to 1 week old pigs. INTERVENTIONS: Hydrostatic pulmonary edema was induced in pigs by acute volume overload. Ivacaftor was nebulized into the lung immediately after volume overload. Grams of water per grams of dry lung tissue were determined in the lungs harvested 1 hour after volume overload. MEASUREMENTS AND MAIN RESULTS: Ivacaftor significantly improved alveolar liquid clearance in isolated pig lung lobes ex vivo and reduced edema in a volume overload in vivo pig model of hydrostatic pulmonary edema. To model hydrostatic pressure-induced edema in vitro, we developed a method of applied pressure to the basolateral surface of alveolar epithelia. Elevated hydrostatic pressure resulted in decreased cystic fibrosis transmembrane conductance regulator activity and liquid absorption, an effect which was partially reversed by cystic fibrosis transmembrane conductance regulator potentiation with ivacaftor. CONCLUSIONS: Cystic fibrosis transmembrane conductance regulator potentiation by ivacaftor is a novel therapeutic approach for pulmonary edema.
Subject(s)
Aminophenols/pharmacology , Chloride Channel Agonists/pharmacology , Cystic Fibrosis Transmembrane Conductance Regulator/agonists , Pulmonary Edema/drug therapy , Quinolones/pharmacology , Administration, Inhalation , Alveolar Epithelial Cells/drug effects , Aminophenols/administration & dosage , Animals , Chloride Channel Agonists/administration & dosage , Disease Models, Animal , Prospective Studies , Quinolones/administration & dosage , SwineABSTRACT
Abnormal airway smooth muscle function can contribute to cystic fibrosis (CF) airway disease. We previously found that airway smooth muscle from newborn CF pigs had increased basal tone, an increased bronchodilator response, and abnormal calcium handling. Since CF pigs lack airway infection and inflammation at birth, these findings suggest intrinsic airway smooth muscle dysfunction in CF. In this study, we tested the hypothesis that CFTR loss in airway smooth muscle would produce a distinct set of changes in the airway smooth muscle transcriptome that we could use to develop novel therapeutic targets. Total RNA sequencing of newborn wild-type and CF airway smooth muscle revealed changes in muscle contraction-related genes, ontologies, and pathways. Using connectivity mapping, we identified several small molecules that elicit transcriptional signatures opposite of CF airway smooth muscle, including NVP-TAE684, an inhibitor of proline-rich tyrosine kinase 2 (PYK2). In CF airway smooth muscle tissue, PYK2 phosphorylation was increased and PYK2 inhibition decreased smooth muscle contraction. In vivo NVP-TAE684 treatment of wild-type mice reduced methacholine-induced airway smooth muscle contraction. These findings suggest that studies in the newborn CF pig may provide an important approach to enhance our understanding of airway smooth muscle biology and for discovery of novel airway smooth muscle therapeutics for CF and other diseases of airway hyperreactivity.
Subject(s)
Bronchi/metabolism , Cystic Fibrosis/genetics , Focal Adhesion Kinase 2/metabolism , Muscle, Smooth/metabolism , Transcriptome , Animals , Animals, Newborn , Bronchi/enzymology , Bronchi/physiopathology , Cystic Fibrosis/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Gene Expression , Muscle, Smooth/enzymology , Muscle, Smooth/physiopathology , Myosin Light Chains/metabolism , Phosphorylation , RNA, Messenger/genetics , Respiratory Hypersensitivity , SwineABSTRACT
Mutations in the gene encoding the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) anion channel cause CF. The leading cause of death in the CF population is lung disease. Increasing evidence suggests that in utero airway development is CFTR-dependent and that developmental abnormalities may contribute to CF lung disease. However, relatively little is known about postnatal CF airway growth, largely because such studies are limited in humans. Therefore, we examined airway growth and lung volume in a porcine model of CF. We hypothesized that CF pigs would have abnormal postnatal airway growth. To test this hypothesis, we performed CT-based airway and lung volume measurements in 3-wk-old non-CF and CF pigs. We found that 3-wk-old CF pigs had tracheas of reduced caliber and irregular shape. Their bronchial lumens were reduced in size proximally but not distally, were irregularly shaped, and had reduced distensibility. Our data suggest that lack of CFTR results in aberrant postnatal airway growth and development, which could contribute to CF lung disease pathogenesis.NEW & NOTEWORTHY This CT scan-based study of airway morphometry in the cystic fibrosis (CF) postnatal period is unique, as analogous studies in humans are greatly limited for ethical and technical reasons. Findings such as reduced airway lumen area and irregular caliber suggest that airway growth and development are CF transmembrane conductance regulator-dependent and that airway growth defects may contribute to CF lung disease pathogenesis.
Subject(s)
Bronchi/diagnostic imaging , Bronchi/growth & development , Cystic Fibrosis/diagnostic imaging , Trachea/drug effects , Trachea/growth & development , Animals , Animals, Genetically Modified , Animals, Newborn , Cystic Fibrosis/genetics , Cystic Fibrosis Transmembrane Conductance Regulator/deficiency , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Lung/diagnostic imaging , Lung/growth & development , SwineABSTRACT
RATIONALE: Previous work indicates that ivacaftor improves cystic fibrosis transmembrane conductance regulator (CFTR) activity and lung function in people with cystic fibrosis and G551D-CFTR mutations but does not reduce density of bacteria or markers of inflammation in the airway. These findings raise the possibility that infection and inflammation may progress independently of CFTR activity once cystic fibrosis lung disease is established. OBJECTIVES: To better understand the relationship between CFTR activity, airway microbiology and inflammation, and lung function in subjects with cystic fibrosis and chronic airway infections. METHODS: We studied 12 subjects with G551D-CFTR mutations and chronic airway infections before and after ivacaftor. We measured lung function, sputum bacterial content, and inflammation, and obtained chest computed tomography scans. MEASUREMENTS AND MAIN RESULTS: Ivacaftor produced rapid decreases in sputum Pseudomonas aeruginosa density that began within 48 hours and continued in the first year of treatment. However, no subject eradicated their infecting P. aeruginosa strain, and after the first year P. aeruginosa densities rebounded. Sputum total bacterial concentrations also decreased, but less than P. aeruginosa. Sputum inflammatory measures decreased significantly in the first week of treatment and continued to decline over 2 years. Computed tomography scans obtained before and 1 year after ivacaftor treatment revealed that ivacaftor decreased airway mucous plugging. CONCLUSIONS: Ivacaftor caused marked reductions in sputum P. aeruginosa density and airway inflammation and produced modest improvements in radiographic lung disease in subjects with G551D-CFTR mutations. However, P. aeruginosa airway infection persisted. Thus, measures that control infection may be required to realize the full benefits of CFTR-targeting treatments.
Subject(s)
Aminophenols/therapeutic use , Cystic Fibrosis Transmembrane Conductance Regulator/drug effects , Cystic Fibrosis/drug therapy , Inflammation/prevention & control , Quinolones/therapeutic use , Respiratory Tract Infections/prevention & control , Adult , Chloride Channel Agonists/therapeutic use , Cystic Fibrosis/diagnostic imaging , Cystic Fibrosis/metabolism , Cystic Fibrosis Transmembrane Conductance Regulator/metabolism , Female , Humans , Inflammation/metabolism , Lung/diagnostic imaging , Lung/metabolism , Male , Respiratory Tract Infections/metabolism , Sputum/drug effects , Sputum/metabolism , Tomography, X-Ray ComputedABSTRACT
Mounier-Kuhn syndrome is a rare clinical disorder characterized by tracheobronchial dilation and recurrent lower respiratory tract infections. While the etiology of the disease remains unknown, histopathological analysis of Mounier-Kuhn airways demonstrates that the disease is, in part, characterized by cellular changes in airway smooth muscle.
ABSTRACT
Neurons innervating the airways contribute to airway hyperreactivity (AHR), a hallmark feature of asthma. Several observations suggested that acid-sensing ion channels (ASICs), neuronal cation channels activated by protons, might contribute to AHR. For example, ASICs are found in vagal sensory neurons that innervate airways, and asthmatic airways can become acidic. Moreover, airway acidification activates ASIC currents and depolarizes neurons innervating airways. We found ASIC1a protein in vagal ganglia neurons, but not airway epithelium or smooth muscle. We induced AHR by sensitizing mice to ovalbumin and found that ASIC1a-/- mice failed to exhibit AHR despite a robust inflammatory response. Loss of ASIC1a also decreased bronchoalveolar lavage fluid levels of substance P, a sensory neuropeptide secreted from vagal sensory neurons that contributes to AHR. These findings suggest that ASIC1a is an important mediator of AHR and raise the possibility that inhibiting ASIC channels might be beneficial in asthma.
Subject(s)
Acid Sensing Ion Channels/metabolism , Respiratory Hypersensitivity/metabolism , Respiratory System/metabolism , Animals , Asthma/metabolism , Bronchoalveolar Lavage Fluid/chemistry , Inflammation/metabolism , Male , Mice , Mice, Inbred C57BL , Nerve Tissue Proteins/metabolism , Sensory Receptor Cells/metabolism , Substance P/metabolism , Vagus Nerve/metabolismABSTRACT
BACKGROUND: Airflow obstruction is common in cystic fibrosis (CF), yet the underlying pathogenesis remains incompletely understood. People with CF often exhibit airway hyperresponsiveness, CF transmembrane conductance regulator (CFTR) is present in airway smooth muscle (ASM), and ASM from newborn CF pigs has increased contractile tone, suggesting that loss of CFTR causes a primary defect in ASM function. We hypothesized that restoring CFTR activity would decrease smooth muscle tone in people with CF. METHODS: To increase or potentiate CFTR function, we administered ivacaftor to 12 adults with CF with the G551D-CFTR mutation; ivacaftor stimulates G551D-CFTR function. We studied people before and immediately after initiation of ivacaftor (48 hours) to minimize secondary consequences of CFTR restoration. We tested smooth muscle function by investigating spirometry, airway distensibility, and vascular tone. RESULTS: Ivacaftor rapidly restored CFTR function, indicated by reduced sweat chloride concentration. Airflow obstruction and air trapping also improved. Airway distensibility increased in airways less than 4.5 mm but not in larger-sized airways. To assess smooth muscle function in a tissue outside the lung, we measured vascular pulse wave velocity (PWV) and augmentation index, which both decreased following CFTR potentiation. Finally, change in distensibility of <4.5-mm airways correlated with changes in PWV. CONCLUSIONS: Acute CFTR potentiation provided a unique opportunity to investigate CFTR-dependent mechanisms of CF pathogenesis. The rapid effects of ivacaftor on airway distensibility and vascular tone suggest that CFTR dysfunction may directly cause increased smooth muscle tone in people with CF and that ivacaftor may relax smooth muscle. FUNDING: This work was funded in part from an unrestricted grant from the Vertex Investigator-Initiated Studies Program.
ABSTRACT
OBJECTIVES/HYPOTHESIS: Tracheal cartilage ring structural abnormalities have been reported in cystic fibrosis (CF) mice and pigs. Whether similar findings are present in humans with CF is unknown. We hypothesized that tracheal cartilage ring shape and size would be different in people with CF. STUDY DESIGN: Tracheal cartilage ring size and shape were measured in adults with (n = 21) and without CF (n = 18). METHODS: Ultrasonography was used in human subjects to noninvasively assess tracheal cartilage ring structure in both the sagittal and the transverse planes. Tracheal cartilage ring thickness was also determined from histological sections obtained from newborn non-CF and CF pigs. These values were compared with human data. RESULTS: Human CF tracheas had a greater width and were less circular in shape compared to non-CF subjects. CF tracheal cartilage rings had a greater midline cross-sectional area and were thicker compared to non-CF rings. Maximal tracheal cartilage ring thickness was also greater in both newborn CF pigs and human adults with CF, compared to non-CF controls. CONCLUSIONS: Our findings demonstrate that structural differences exist in tracheal cartilage rings in adults with CF. Comparison with newborn CF pig data suggests that some of these changes may be congenital in nature. LEVEL OF EVIDENCE: 3b
Subject(s)
Cartilage/pathology , Cystic Fibrosis/pathology , Trachea/pathology , Adolescent , Adult , Animals , Female , Humans , Male , Swine , Young AdultABSTRACT
Mucociliary transport (MCT) is an innate defense mechanism that removes particulates, noxious material, and microorganisms from the lung. Several airway diseases exhibit abnormal MCT, including asthma, chronic bronchitis, and cystic fibrosis. However, it remains uncertain whether MCT abnormalities contribute to the genesis of disease or whether they are secondary manifestations that may fuel disease progression. Limitations of current MCT assays and of current animal models of human disease have hindered progress in addressing these questions. Therefore, we developed an in vivo assay of MCT, and here we describe its use in newborn wild-type pigs. We studied pigs because they share many physiological, biochemical, and anatomical features with humans and can model several human diseases. We used X-ray multidetector-row-computed tomography to track movement of individual particles in the large airways of newborn pigs. Multidetector-row-computed tomography imaging provided high spatial and temporal resolution and registration of particle position to airway anatomy. We discovered that cilia orientation directs particles to the ventral tracheal surface. We also observed substantial heterogeneity in the rate of individual particle movement, and we speculate that variations in mucus properties may be responsible. The increased granularity of MCT data provided by this assay may provide an opportunity to better understand host defense mechanisms and the pathogenesis of airway disease.
Subject(s)
Mucociliary Clearance/physiology , Trachea/physiology , Animals , Animals, Newborn , SwineABSTRACT
The pathogenesis of cystic fibrosis (CF) airway disease is not well understood. A porcine CF model was recently generated, and these animals develop lung disease similar to humans with CF. At birth, before infection and inflammation, CF pigs have airways that are irregularly shaped and have a reduced caliber compared to non-CF pigs. We hypothesized that these airway structural abnormalities affect airflow patterns and particle distribution. To test this hypothesis we used computational fluid dynamics (CFD) on airway geometries obtained by computed tomography of newborn non-CF and CF pigs. For the same flow rate, newborn CF pig airways exhibited higher air velocity and resistance compared to non-CF. Moreover we found that, at the carina bifurcation, particles greater than 5-µm preferably distributed to the right CF lung despite almost equal airflow ventilation in non-CF and CF. CFD modeling also predicted that deposition efficiency was greater in CF compared to non-CF for 5- and 10-µm particles. These differences were most significant in the airways included in the geometry supplying the right caudal, right accessory, left caudal, and left cranial lobes. The irregular particle distribution and increased deposition in newborn CF pig airways suggest that early airway structural abnormalities might contribute to CF disease pathogenesis.
Subject(s)
Cystic Fibrosis/physiopathology , Lung/pathology , Lung/physiopathology , Animals , Animals, Genetically Modified , Animals, Newborn , Cystic Fibrosis/diagnostic imaging , Cystic Fibrosis Transmembrane Conductance Regulator/genetics , Hydrodynamics , Lung/diagnostic imaging , Pulmonary Ventilation , Swine , Tomography, X-Ray ComputedABSTRACT
BACKGROUND: Tracheomalacia (TM) occurs in approximately 1 in 2,100 children. Because the trachea develops abnormally in animal models of cystic fibrosis (CF), we hypothesized this may also occur in children with CF, increasing their risk of TM. PURPOSE: To examine the prevalence and clinical consequences of TM in children with CF. METHODS: We studied children with CF born between 1995 and 2012. TM was defined as dynamic collapse of the trachea, and the severity was recorded as described in the chart. The effect of TM on patient outcomes, including FEV1 , CT changes, and acquisition of CF pathogens, was assessed using a longitudinal patient dataset. RESULTS: Eighty-nine percent of children with CF had at least one bronchoscopy (n = 97/109). Fifteen percent of these children had TM described in any bronchoscopy report (n = 15/97). Of the patients with TM, eight had meconium ileus (P = 0.003) and all were pancreatic insufficient. Pseudomonas aeruginosa infection occurred 1.3 years earlier among children with TM (P = 0.01). Starting FEV1 values by age 8 were diminished by over 18% of predicted for patients with TM. Life-threatening episodes of airway obstruction occurred in 3 of 15 patients with CF and TM, including one leading to death. Gender, prematurity, and hepatic disease were not associated with TM. No difference was observed in the frequency of bronchiectasis. CONCLUSIONS: TM is significantly more common in infants and children with CF than in the general population and is associated with airway obstruction and earlier Pseudomonas acquisition.