title: Experimental evidence of age-related adaptive changes in human acinar airways.
abstract: The progressive decline of lung function with aging is associated with changes in lung structure at all levels, from conducting airways to acinar airways (alveolar ducts and sacs). While information on conducting airways is becoming available from computed tomography, in vivo information on the acinar airways is not conventionally available, even though acini occupy 95% of lung volume and serve as major gas exchange units of the lung. The objectives of this study are to measure morphometric parameters of lung acinar airways in living adult humans over a broad range of ages by using an innovative MRI-based technique, in vivo lung morphometry with hyperpolarized (3)He gas, and to determine the influence of age-related differences in acinar airway morphometry on lung function. Pulmonary function tests and MRI with hyperpolarized (3)He gas were performed on 24 healthy nonsmokers aged 19-71 years. The most significant age-related difference across this population was a 27% loss of alveolar depth, h, leading to a 46% increased acinar airway lumen radius, hence, decreased resistance to acinar air transport. Importantly, the data show a negative correlation between h and the pulmonary function measures forced expiratory volume in 1 s and forced vital capacity. In vivo lung morphometry provides unique information on age-related changes in lung microstructure and their influence on lung function. We hypothesize that the observed reduction of alveolar depth in subjects with advanced aging represents a remodeling process that might be a compensatory mechanism, without which the pulmonary functional decline due to other biological factors with advancing age would be significantly larger.
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri;
authors.forename: James D
authors.initials: JD
authors.lastname: Quirk
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri;
authors.forename: Alexander L
authors.initials: AL
authors.lastname: Sukstanskii
authors.affiliation: Center for Pulmonary Imaging Research, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Department of Physics, Washington University, St. Louis, Missouri;
authors.forename: Jason C
authors.initials: JC
authors.lastname: Woods
authors.affiliation: Department of Internal Medicine, Division of Medical Education, Washington University School of Medicine, St. Louis, Missouri; and.
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Lutey
authors.affiliation: Department of Physics, Washington University, St. Louis, Missouri;
authors.forename: Mark S
authors.initials: MS
authors.lastname: Conradi
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri;
authors.forename: David S
authors.initials: DS
authors.lastname: Gierada
authors.affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Roger D
authors.initials: RD
authors.lastname: Yusen
authors.affiliation: Department of Internal Medicine, Division of Pulmonary and Critical Care Medicine, Washington University School of Medicine, St. Louis, Missouri.
authors.forename: Mario
authors.initials: M
authors.lastname: Castro
authors.affiliation: Mallinckrodt Institute of Radiology, Washington University School of Medicine, St. Louis, Missouri; yablonskiyd@wustl.edu.
authors.forename: Dmitriy A
authors.initials: DA
authors.lastname: Yablonskiy
mesh_terms: D061354:Acinar Cells / Q000502:physiology*; D000222:Adaptation, Physiological / Q000502:physiology*; D000328:Adult; D000368:Aged; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D005260:Female; D006371:Helium; D006801:Humans; D008168:Lung / Q000502:physiology*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D006371:Helium
keywords: MRI; airway remodeling; alveolar ducts and sacs; hyperpolarized gas; in vivo lung morphometry