title: Constitutive activation of prosurvival signaling in alveolar mesenchymal cells isolated from patients with nonresolving acute respiratory distress syndrome.
abstract: Acute respiratory distress syndrome (ARDS) is a clinical syndrome characterized by stereotypic host inflammatory and repair cellular responses; however, mechanisms regulating the resolution of ARDS are poorly understood. Here, we report the isolation and characterization of a novel population of mesenchymal cells from the alveolar space of ARDS patients via fiber-optic bronchoscopy with bronchoalveolar lavage (BAL). BAL was performed on 17 patients during the course of ARDS. Immunofluorescence staining and multiparameter flow cytometric analysis defined a population of alveolar mesenchymal cells (AMCs) that are CD45-/prolyl-4-hydroxylase+/alpha-smooth muscle actin+/-. AMCs proliferated in ex vivo cell culture for multiple passages; early passage (3-5) cells were subsequently analyzed in 13 patients. AMCs isolated from patients with persistent or nonresolving ARDS (ARDS-NR, n = 4) demonstrate enhanced constitutive activation of prosurvival signaling pathways involving PKB/Akt, FKHR, and BCL-2 family proteins compared with AMCs from patients with resolving ARDS (ARDS-R, n = 9). Exogenous transforming growth factor-beta1 markedly induces PKB/Akt activation in AMCs from ARDS-R. ARDS-NR cells are more resistant to serum deprivation-induced apoptosis compared with ARDS-R. This study identifies a novel population of mesenchymal cells that can be isolated from the alveolar spaces of ARDS patients. AMCs in patients with ARDS-NR acquire an activational profile characterized by enhanced prosurvival signaling and an antiapoptotic phenotype. These findings support the concept that apoptosis of mesenchymal cells may be an essential component of normal repair and resolution of ARDS and suggest that dysregulation of this process may contribute to persistent ARDS.
authors.affiliation: Div. of Pulmonary and Critical Care Medicine, Univ. of Michigan Medical Center, 6301 MSRB III, 1150 W. Medical Center Dr., Ann Arbor, MI 48109, USA.
authors.forename: Jeffrey C
authors.initials: JC
authors.lastname: Horowitz
authors.forename: Zongbin
authors.initials: Z
authors.lastname: Cui
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Moore
authors.forename: Tamara R
authors.initials: TR
authors.lastname: Meier
authors.forename: Raju C
authors.initials: RC
authors.lastname: Reddy
authors.forename: Galen B
authors.initials: GB
authors.lastname: Toews
authors.forename: Theodore J
authors.initials: TJ
authors.lastname: Standiford
authors.forename: Victor J
authors.initials: VJ
authors.lastname: Thannickal
mesh_terms: D000199:Actins / Q000378:metabolism; D000328:Adult; D000368:Aged; D017209:Apoptosis; D001992:Bronchoalveolar Lavage Fluid / Q000166:cytology; D001999:Bronchoscopy; D049109:Cell Proliferation; D002470:Cell Survival / Q000502:physiology; D005260:Female; D005347:Fibroblasts / Q000378:metabolism; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000378:metabolism; D006801:Humans; D017493:Leukocyte Common Antigens / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011393:Procollagen-Proline Dioxygenase / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000378:metabolism / Q000473:pathology*; D012128:Respiratory Distress Syndrome / Q000378:metabolism* / Q000473:pathology; D015398:Signal Transduction / Q000502:physiology*
chemical_list: D000199:Actins; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D019253:Proto-Oncogene Proteins c-bcl-2; D011393:Procollagen-Proline Dioxygenase; D051057:Proto-Oncogene Proteins c-akt; D017493:Leukocyte Common Antigens