title: Mitochondrial catalase overexpressed transgenic mice are protected against lung fibrosis in part via preventing alveolar epithelial cell mitochondrial DNA damage.
abstract: Alveolar epithelial cell (AEC) injury and mitochondrial dysfunction are important in the development of lung fibrosis. Our group has shown that in the asbestos exposed lung, the generation of mitochondrial reactive oxygen species (ROS) in AEC mediate mitochondrial DNA (mtDNA) damage and apoptosis which are necessary for lung fibrosis. These data suggest that mitochondrial-targeted antioxidants should ameliorate asbestos-induced lung.
  
  
  
  To determine whether transgenic mice that express mitochondrial-targeted catalase (MCAT) have reduced lung fibrosis following exposure to asbestos or bleomycin and, if so, whether this occurs in association with reduced AEC mtDNA damage and apoptosis.
  
  
  
  Crocidolite asbestos (100µg/50µL), TiO2(negative control), bleomycin (0.025 units/50µL), or PBS was instilled intratracheally in 8-10 week-old wild-type (WT - C57Bl/6J) or MCAT mice. The lungs were harvested at 21d. Lung fibrosis was quantified by collagen levels (Sircol) and lung fibrosis scores. AEC apoptosis was assessed by cleaved caspase-3 (CC-3)/Surfactant protein C (SFTPC) immunohistochemistry (IHC) and semi-quantitative analysis. AEC (primary AT2 cells from WT and MCAT mice and MLE-12 cells) mtDNA damage was assessed by a quantitative PCR-based assay, apoptosis was assessed by DNA fragmentation, and ROS production was assessed by a Mito-Sox assay.
  
  
  
  Compared to WT, crocidolite-exposed MCAT mice exhibit reduced pulmonary fibrosis as measured by lung collagen levels and lung fibrosis score. The protective effects in MCAT mice were accompanied by reduced AEC mtDNA damage and apoptosis. Similar findings were noted following bleomycin exposure. Euk-134, a mitochondrial SOD/catalase mimetic, attenuated MLE-12 cell DNA damage and apoptosis. Finally, compared to WT, asbestos-induced MCAT AT2 cell ROS production was reduced.
  
  
  
  Our finding that MCAT mice have reduced pulmonary fibrosis, AEC mtDNA damage and apoptosis following exposure to asbestos or bleomycin suggests an important role for AEC mitochondrial H2O2-induced mtDNA damage in promoting lung fibrosis. We reason that strategies aimed at limiting AEC mtDNA damage arising from excess mitochondrial H2O2production may be a novel therapeutic target for mitigating pulmonary fibrosis.
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Seok-Jo
authors.initials: SJ
authors.lastname: Kim
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Paul
authors.initials: P
authors.lastname: Cheresh
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Renea P
authors.initials: RP
authors.lastname: Jablonski
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Luisa
authors.initials: L
authors.lastname: Morales-Nebreda
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Cheng
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Erin
authors.initials: E
authors.lastname: Hogan
authors.affiliation: Department of Pathology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Anjana
authors.initials: A
authors.lastname: Yeldandi
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Monica
authors.initials: M
authors.lastname: Chi
authors.affiliation: Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Raul
authors.initials: R
authors.lastname: Piseaux
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Karen
authors.initials: K
authors.lastname: Ridge
authors.affiliation: Atlanta VA Medical Center, Decatur, GA, United States; Department of Medicine, Emory University, Atlanta, GA, United States.
authors.forename: C
authors.initials: C
authors.lastname: Michael Hart
authors.affiliation: Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: Navdeep
authors.initials: N
authors.lastname: Chandel
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States.
authors.forename: G R
authors.initials: GR
authors.lastname: Scott Budinger
authors.affiliation: Department of Medicine, Division of Pulmonary & Critical Care Medicine, Jesse Brown VA Medical Center, Chicago, IL, United States; Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, United States. Electronic address: d-kamp@northwestern.edu.
authors.forename: David W
authors.initials: DW
authors.lastname: Kamp
mesh_terms: D000280:Administration, Inhalation; D000818:Animals; D001194:Asbestos; D001761:Bleomycin; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D002374:Catalase / Q000235:genetics* / Q000378:metabolism; D003094:Collagen / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D015870:Gene Expression; D005786:Gene Expression Regulation; D036341:Intercellular Signaling Peptides and Proteins; D007442:Intubation, Intratracheal; D051379:Mice; D008822:Mice, Transgenic; D008928:Mitochondria / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D024101:Mitochondrial Proteins / Q000235:genetics* / Q000378:metabolism; D009942:Organometallic Compounds / Q000494:pharmacology; D010455:Peptides / Q000235:genetics / Q000378:metabolism; D011650:Pulmonary Alveoli / Q000187:drug effects* / Q000201:enzymology / Q000473:pathology; D011658:Pulmonary Fibrosis / Q000139:chemically induced / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D037721:Pulmonary Surfactant-Associated Protein C; D017382:Reactive Oxygen Species / Q000037:antagonists & inhibitors / Q000378:metabolism; D012459:Salicylates / Q000494:pharmacology; D019076:Transgenes
chemical_list: D004272:DNA, Mitochondrial; C433928:EUK-134; D036341:Intercellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D009942:Organometallic Compounds; D010455:Peptides; D037721:Pulmonary Surfactant-Associated Protein C; D017382:Reactive Oxygen Species; D012459:Salicylates; C489680:Sftpc protein, mouse; D001761:Bleomycin; D001194:Asbestos; D003094:Collagen; D002374:Catalase; C505409:Casp3 protein, mouse; D053148:Caspase 3