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Larson-Casey JL, Saleem K, Surolia R, Pandey J, Mack M, Antony VB, Bodduluri S, Bhatt SP, Duncan SR, Carter AB. Correction: DX5/CD49b-Positive T Cells Are Not Synonymous with CD1d-Dependent NKT Cells. J Immunol 2024; 212:1393. [PMID: 38407351 DOI: 10.4049/jimmunol.2400069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
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Larson-Casey JL, Saleem K, Surolia R, Pandey J, Mack M, Antony VB, Bodduluri S, Bhatt SP, Duncan SR, Carter AB. Myeloid Heterogeneity Mediates Acute Exacerbations of Pulmonary Fibrosis. J Immunol 2023; 211:1714-1724. [PMID: 37782053 PMCID: PMC10843506 DOI: 10.4049/jimmunol.2300053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 09/15/2023] [Indexed: 10/03/2023]
Abstract
Epidemiological evidence indicates that exposure to particulate matter is linked to the development of idiopathic pulmonary fibrosis (IPF) and increases the incidence of acute exacerbations of IPF. In addition to accelerating the rate of lung function decline, exposure to fine particulate matter (particulate matter smaller than 2.5 μm [PM2.5]) is a risk factor for increased mortality in subjects with IPF. In this article, we show that exposure to PM2.5 mediates monocyte recruitment and fibrotic progression in mice with established fibrosis. In mice with established fibrosis, bronchoalveolar lavage cells showed monocyte/macrophage heterogeneity after exposure to PM2.5. These cells had a significant inflammatory and anti-inflammatory signature. The mixed heterogeneity of cells contributed to the proinflammatory and anti-inflammatory response. Although monocyte-derived macrophages were recruited to the lung in bleomycin-injured mice treated with PM2.5, recruitment of monocytes expressing Ly6Chi to the lung promoted progression of fibrosis, reduced lung aeration on computed tomography, and impacted lung compliance. Ly6Chi monocytes isolated from PM2.5-exposed fibrotic mice showed enhanced expression of proinflammatory markers compared with fibrotic mice exposed to vehicle. Moreover, IPF bronchoalveolar lavage cells treated ex vivo with PM2.5 showed an exaggerated inflammatory response. Targeting Ly6Chi monocyte recruitment inhibited fibrotic progression in mice. Moreover, the adoptive transfer of Ly6Chi monocytes exacerbated established fibrosis. These observations suggest that enhanced recruitment of Ly6Chi monocytes with a proinflammatory phenotype mediates acute exacerbations of pulmonary fibrosis, and targeting these cells may provide a potential novel therapeutic target to protect against acute exacerbations of IPF.
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Affiliation(s)
- Jennifer L. Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Komal Saleem
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Ranu Surolia
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jyotsana Pandey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Matthias Mack
- Department of Nephrology, University of Regensburg, Regensburg, Germany
| | - Veena B. Antony
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Sandeep Bodduluri
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
- UAB Lung Imaging Lab, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Surya P. Bhatt
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
- UAB Lung Imaging Lab, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Steven R. Duncan
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - A. Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Birmingham Veterans Administration Medical Center, Birmingham. AL, USA
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Larson-Casey JL, Liu S, Pyles JM, Lapi SE, Saleem K, Antony VB, Gonzalez ML, Crossman DK, Carter AB. Impaired PPARγ activation by cadmium exacerbates infection-induced lung injury. JCI Insight 2023; 8:e166608. [PMID: 36928191 PMCID: PMC10243824 DOI: 10.1172/jci.insight.166608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 03/15/2023] [Indexed: 03/18/2023] Open
Abstract
Emerging data indicate an association between environmental heavy metal exposure and lung disease, including lower respiratory tract infections (LRTIs). Here, we show by single-cell RNA sequencing an increase in Pparg gene expression in lung macrophages from mice exposed to cadmium and/or infected with Streptococcus pneumoniae. However, the heavy metal cadmium or infection mediated an inhibitory posttranslational modification of peroxisome proliferator-activated receptor γ (PPARγ) to exacerbate LRTIs. Cadmium and infection increased ERK activation to regulate PPARγ degradation in monocyte-derived macrophages. Mice harboring a conditional deletion of Pparg in monocyte-derived macrophages had more severe S. pneumoniae infection after cadmium exposure, showed greater lung injury, and had increased mortality. Inhibition of ERK activation with BVD-523 protected mice from lung injury after cadmium exposure or infection. Moreover, individuals residing in areas of high air cadmium levels had increased cadmium concentration in their bronchoalveolar lavage (BAL) fluid, increased barrier dysfunction, and showed PPARγ inhibition that was mediated, at least in part, by ERK activation in isolated BAL cells. These observations suggest that impaired activation of PPARγ in monocyte-derived macrophages exacerbates lung injury and the severity of LRTIs.
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Affiliation(s)
| | - Shanrun Liu
- Division of Clinical Immunology and Rheumatology, Department of Medicine
| | | | | | - Komal Saleem
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine
| | - Veena B. Antony
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine
| | | | - David K. Crossman
- Department of Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A. Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine
- Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA
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Pandey J, Larson-Casey JL, Patil MH, Joshi R, Jiang CS, Zhou Y, He C, Carter AB. NOX4-TIM23 interaction regulates NOX4 mitochondrial import and metabolic reprogramming. J Biol Chem 2023; 299:104695. [PMID: 37044213 PMCID: PMC10193017 DOI: 10.1016/j.jbc.2023.104695] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2022] [Revised: 03/14/2023] [Accepted: 04/03/2023] [Indexed: 04/14/2023] Open
Abstract
Pulmonary fibrosis is a progressive lung disease characterized by macrophage activation. Asbestos-induced expression of nicotinamide adenine dinucleotide phosphate hydrogen oxidase 4 (NOX4) in lung macrophages mediates fibrotic progression by the generation of mitochondrial reactive oxygen species (ROS), modulating mitochondrial biogenesis, and promoting apoptosis resistance; however, the mechanism(s) by which NOX4 localizes to mitochondria during fibrosis is not known. Here, we show that NOX4 localized to the mitochondrial matrix following asbestos exposure in lung macrophages via direct interaction with TIM23. TIM23 and NOX4 interaction was found in lung macrophages from human subjects with asbestosis, while it was absent in mice harboring a conditional deletion of NOX4 in lung macrophages. This interaction was localized to the proximal transmembrane region of NOX4. Mechanistically, TIM23 augmented NOX4-induced mitochondrial ROS and metabolic reprogramming to oxidative phosphorylation. Silencing TIM23 decreased mitochondrial ROS and oxidative phosphorylation. These observations highlight the important role of the mitochondrial translocase TIM23 interaction with NOX4. Moreover, this interaction is required for mitochondrial redox signaling and metabolic reprogramming in lung macrophages.
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Affiliation(s)
- Jyotsana Pandey
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Larson-Casey
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Mallikarjun H Patil
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Rutwij Joshi
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Chun-Sun Jiang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Yong Zhou
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Chao He
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A Brent Carter
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Department of Medicine, Birmingham VAMC, Birmingham, Alabama, USA.
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Rangarajan S, Locy ML, Chanda D, Kurundkar A, Kurundkar D, Larson-Casey JL, Londono P, Bagchi RA, Deskin B, Elajaili H, Nozik ES, Deshane JS, Zmijewski JW, Eickelberg O, Thannickal VJ. Mitochondrial uncoupling protein-2 reprograms metabolism to induce oxidative stress and myofibroblast senescence in age-associated lung fibrosis. Aging Cell 2022; 21:e13674. [PMID: 35934931 PMCID: PMC9470902 DOI: 10.1111/acel.13674] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 06/12/2022] [Accepted: 07/04/2022] [Indexed: 01/25/2023] Open
Abstract
Mitochondrial dysfunction has been associated with age-related diseases, including idiopathic pulmonary fibrosis (IPF). We provide evidence that implicates chronic elevation of the mitochondrial anion carrier protein, uncoupling protein-2 (UCP2), in increased generation of reactive oxygen species, altered redox state and cellular bioenergetics, impaired fatty acid oxidation, and induction of myofibroblast senescence. This pro-oxidant senescence reprogramming occurs in concert with conventional actions of UCP2 as an uncoupler of oxidative phosphorylation with dissipation of the mitochondrial membrane potential. UCP2 is highly expressed in human IPF lung myofibroblasts and in aged fibroblasts. In an aging murine model of lung fibrosis, the in vivo silencing of UCP2 induces fibrosis regression. These studies indicate a pro-fibrotic function of UCP2 in chronic lung disease and support its therapeutic targeting in age-related diseases associated with impaired tissue regeneration and organ fibrosis.
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Affiliation(s)
- Sunad Rangarajan
- Division of Pulmonary Sciences and Critical Care, Department of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Morgan L Locy
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Diptiman Chanda
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ashish Kurundkar
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Deepali Kurundkar
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Larson-Casey
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Pilar Londono
- Division of Pulmonary Sciences and Critical Care, Department of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Rushita A Bagchi
- Division of Cardiology, Department of Medicine, University of Colorado, Aurora, Colorado, USA
| | - Brian Deskin
- Division of Pulmonary and Critical Care, Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
| | - Hanan Elajaili
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado, Aurora, Colorado, USA
| | - Eva S Nozik
- Cardiovascular Pulmonary Research Laboratories and Pediatric Critical Care Medicine, Department of Pediatrics, University of Colorado, Aurora, Colorado, USA
| | - Jessy S Deshane
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jaroslaw W Zmijewski
- Division of Pulmonary and Critical Care, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Oliver Eickelberg
- Division of Pulmonary, Allergy and Critical Care, Department of Medicine, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Victor J Thannickal
- John W. Deming Department of Medicine, Tulane University School of Medicine, New Orleans, Louisiana, USA
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Gu L, Surolia R, Larson-Casey JL, He C, Davis D, Kang J, Antony VB, Carter AB. Targeting Cpt1a-Bcl-2 interaction modulates apoptosis resistance and fibrotic remodeling. Cell Death Differ 2022; 29:118-132. [PMID: 34413485 PMCID: PMC8738732 DOI: 10.1038/s41418-021-00840-w] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2020] [Revised: 07/14/2021] [Accepted: 07/19/2021] [Indexed: 02/07/2023] Open
Abstract
The mitochondrial calcium uniporter (MCU) regulates metabolic reprogramming in lung macrophages and the progression of pulmonary fibrosis. Fibrosis progression is associated with apoptosis resistance in lung macrophages; however, the mechanism(s) by which apoptosis resistance occurs is poorly understood. Here, we found a marked increase in mitochondrial B-cell lymphoma-2 (Bcl-2) in lung macrophages from subjects with idiopathic pulmonary fibrosis (IPF). Similar findings were seen in bleomycin-injured wild-type (WT) mice, whereas Bcl-2 was markedly decreased in mice expressing a dominant-negative mitochondrial calcium uniporter (DN-MCU). Carnitine palmitoyltransferase 1a (Cpt1a), the rate-limiting enzyme for fatty acid β-oxidation, directly interacted with Bcl-2 by binding to its BH3 domain, which anchored Bcl-2 in the mitochondria to attenuate apoptosis. This interaction was dependent on Cpt1a activity. Lung macrophages from IPF subjects had a direct correlation between CPT1A and Bcl-2, whereas the absence of binding induced apoptosis. The deletion of Bcl-2 in macrophages protected mice from developing pulmonary fibrosis. Moreover, mice had resolution when Bcl-2 was deleted or was inhibited with ABT-199 after fibrosis was established. These observations implicate an interplay between macrophage fatty acid β-oxidation, apoptosis resistance, and dysregulated fibrotic remodeling.
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Affiliation(s)
- Linlin Gu
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Ranu Surolia
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Jennifer L. Larson-Casey
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Chao He
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Dana Davis
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Jungsoon Kang
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - Veena B. Antony
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA
| | - A. Brent Carter
- grid.265892.20000000106344187Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL USA ,grid.280808.a0000 0004 0419 1326Birmingham VAMC, Birmingham, AL USA
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Larson-Casey JL, Carter AB. Does UCP2 Couple Hyperoxia to Lung Injury? Am J Respir Cell Mol Biol 2021; 66:250-251. [PMID: 34905723 PMCID: PMC8937246 DOI: 10.1165/rcmb.2021-0480ed] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
| | - A Brent Carter
- University of Alabama at Birmingham, Medicine, Birmingham, Alabama, United States;
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Larson-Casey JL, Gu L, Davis D, Cai GQ, Ding Q, He C, Carter AB. Post-translational regulation of PGC-1α modulates fibrotic repair. FASEB J 2021; 35:e21675. [PMID: 34038004 PMCID: PMC8252570 DOI: 10.1096/fj.202100339r] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Revised: 04/23/2021] [Accepted: 05/04/2021] [Indexed: 12/12/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease associated with mitochondrial oxidative stress. Mitochondrial reactive oxygen species (mtROS) are important for cell homeostasis by regulating mitochondrial dynamics. Here, we show that IPF BAL cells exhibited increased mitochondrial biogenesis that is, in part, due to increased nuclear expression of peroxisome proliferator-activated receptor-ɣ (PPARɣ) coactivator (PGC)-1α. Increased PPARGC1A mRNA expression directly correlated with reduced pulmonary function in IPF subjects. Oxidant-mediated activation of the p38 MAPK via Akt1 regulated PGC-1α activation to increase mitochondrial biogenesis in monocyte-derived macrophages. Demonstrating the importance of PGC-1α in fibrotic repair, mice harboring a conditional deletion of Ppargc1a in monocyte-derived macrophages or mice administered a chemical inhibitor of mitochondrial division had reduced biogenesis and increased apoptosis, and the mice were protected from pulmonary fibrosis. These observations suggest that Akt1-mediated regulation of PGC-1α maintains mitochondrial homeostasis in monocyte-derived macrophages to induce apoptosis resistance, which contributes to the pathogenesis of pulmonary fibrosis.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Linlin Gu
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Dana Davis
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Guo-Qiang Cai
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Qiang Ding
- Department of Anesthesiology and Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Chao He
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.,Birmingham Veterans Administration Medical Center, Birmingham, AL, USA
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Larson-Casey JL, Gu L, Kang J, Dhyani A, Carter AB. NOX4 regulates macrophage apoptosis resistance to induce fibrotic progression. J Biol Chem 2021; 297:100810. [PMID: 34023385 PMCID: PMC8214193 DOI: 10.1016/j.jbc.2021.100810] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 05/03/2021] [Accepted: 05/19/2021] [Indexed: 12/21/2022] Open
Abstract
Pulmonary fibrosis is a progressive lung disease often occurring secondary to environmental exposure. Asbestos exposure is an important environmental mediator of lung fibrosis and remains a significant cause of disease despite strict regulations to limit exposure. Lung macrophages play an integral role in the pathogenesis of fibrosis induced by asbestos (asbestosis), in part by generating reactive oxygen species (ROS) and promoting resistance to apoptosis. However, the mechanism by which macrophages acquire apoptosis resistance is not known. Here, we confirm that macrophages isolated from asbestosis subjects are resistant to apoptosis and show they are associated with enhanced mitochondrial content of NADPH oxidase 4 (NOX4), which generates mitochondrial ROS generation. Similar results were seen in chrysotile-exposed WT mice, while macrophages from Nox4-/- mice showed increased apoptosis. NOX4 regulated apoptosis resistance by activating Akt1-mediated Bcl-2-associated death phosphorylation. Demonstrating the importance of NOX4-mediated apoptosis resistance in fibrotic remodeling, mice harboring a conditional deletion of Nox4 in monocyte-derived macrophages exhibited increased apoptosis and were protected from pulmonary fibrosis. Moreover, resolution occurred when Nox4 was deleted in monocyte-derived macrophages in mice with established fibrosis. These observations suggest that NOX4 regulates apoptosis resistance in monocyte-derived macrophages and contributes to the pathogenesis of pulmonary fibrosis. Targeting NOX4-mediated apoptosis resistance in monocyte-derived macrophages may provide a novel therapeutic target to protect against the development and/or progression of pulmonary fibrosis.
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Affiliation(s)
- Jennifer L Larson-Casey
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Linlin Gu
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jungsoon Kang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ashish Dhyani
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A Brent Carter
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA.
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Che P, Wang M, Larson-Casey JL, Hu RH, Cheng Y, El Hamdaoui M, Zhao XK, Grytz R, Brent Carter A, Ding Q. A novel tree shrew model of pulmonary fibrosis. J Transl Med 2021; 101:116-124. [PMID: 32773774 DOI: 10.1038/s41374-020-00476-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/20/2020] [Accepted: 07/21/2020] [Indexed: 01/31/2023] Open
Abstract
Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic lung disease without effective therapy. Animal models effectively reproducing IPF disease features are needed to study the underlying molecular mechanisms. Tree shrews are genetically, anatomically, and metabolically closer to humans than rodents or dogs; therefore, the tree shrew model presents a unique opportunity for translational research in lung fibrosis. Here we demonstrate that tree shrews have in vivo and in vitro fibrotic responses induced by bleomycin and pro-fibrotic mediators. Bleomycin exposure induced lung fibrosis evidenced by histological and biochemical fibrotic changes. In primary tree shrew lung fibroblasts, transforming growth factor beta-1 (TGF-β1) induced myofibroblast differentiation, increased extracellular matrix (ECM) protein production, and focal adhesion kinase (FAK) activation. Tree shrew lung fibroblasts showed enhanced migration and increased matrix invasion in response to platelet derived growth factor BB (PDGF-BB). Inhibition of FAK significantly attenuated pro-fibrotic responses in lung fibroblasts. The data demonstrate that tree shrews have in vivo and in vitro fibrotic responses similar to that observed in IPF. The data, for the first time, support that the tree shrew model of lung fibrosis is a new and promising experimental animal model for studying the pathophysiology and therapeutics of lung fibrosis.
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Affiliation(s)
- Pulin Che
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Meimei Wang
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Rui-Han Hu
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, China
| | - Yiju Cheng
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Department of Respiratory Medicine, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, China
| | - Mustapha El Hamdaoui
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Xue-Ke Zhao
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA
- Department of Infectious Diseases, Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou Province, China
| | - Rafael Grytz
- Department of Ophthalmology and Visual Sciences, University of Alabama at Birmingham, Birmingham, AL, USA
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA.
- Birmingham VAMC, Birmingham, AL, USA.
| | - Qiang Ding
- Department of Anesthesiology & Perioperative Medicine, Division of Molecular and Translational Biomedicine, University of Alabama at Birmingham, Birmingham, AL, USA.
- Department of Anesthesiology & Perioperative Medicine, University of Alabama at Birmingham, 901 19th Street South, BMR II, Rm#336, Birmingham, AL, 35294, USA.
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Larson-Casey JL, Gu L, Fiehn O, Carter AB. Cadmium-mediated lung injury is exacerbated by the persistence of classically activated macrophages. J Biol Chem 2020; 295:15754-15766. [PMID: 32917723 DOI: 10.1074/jbc.ra120.013632] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 09/09/2020] [Indexed: 12/15/2022] Open
Abstract
Heavy metals released into the environment have a significant effect on respiratory health. Lung macrophages are important in mounting an inflammatory response to injury, but they are also involved in repair of injury. Macrophages develop mixed phenotypes in complex pathological conditions and polarize to a predominant phenotype depending on the duration and stage of injury and/or repair. Little is known about the reprogramming required for lung macrophages to switch between these divergent functions; therefore, understanding the mechanism(s) by which macrophages promote metabolic reprogramming to regulate lung injury is essential. Here, we show that lung macrophages polarize to a pro-inflammatory, classically activated phenotype after cadmium-mediated lung injury. Because metabolic adaptation provides energy for the diverse macrophage functions, these classically activated macrophages show metabolic reprogramming to glycolysis. RNA-Seq revealed up-regulation of glycolytic enzymes and transcription factors regulating glycolytic flux in lung macrophages from cadmium-exposed mice. Moreover, cadmium exposure promoted increased macrophage glycolytic function with enhanced extracellular acidification rate, glycolytic metabolites, and lactate excretion. These observations suggest that cadmium mediates the persistence of classically activated lung macrophages to exacerbate lung injury.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.
| | - Linlin Gu
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Oliver Fiehn
- National Institutes of Health West Coast Metabolomics Center, University of California Davis, Davis, California, USA
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA
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Larson-Casey JL, Vaid M, Gu L, He C, Cai GQ, Ding Q, Davis D, Berryhill TF, Wilson LS, Barnes S, Neighbors JD, Hohl RJ, Zimmerman KA, Yoder BK, Longhini ALF, Hanumanthu VS, Surolia R, Antony VB, Carter AB. Increased flux through the mevalonate pathway mediates fibrotic repair without injury. J Clin Invest 2020; 129:4962-4978. [PMID: 31609245 DOI: 10.1172/jci127959] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Accepted: 08/13/2019] [Indexed: 12/22/2022] Open
Abstract
Macrophages are important in mounting an innate immune response to injury as well as in repair of injury. Gene expression of Rho proteins is known to be increased in fibrotic models; however, the role of these proteins in idiopathic pulmonary fibrosis (IPF) is not known. Here, we show that BAL cells from patients with IPF have a profibrotic phenotype secondary to increased activation of the small GTPase Rac1. Rac1 activation requires a posttranslational modification, geranylgeranylation, of the C-terminal cysteine residue. We found that by supplying more substrate for geranylgeranylation, Rac1 activation was substantially increased, resulting in profibrotic polarization by increasing flux through the mevalonate pathway. The increased flux was secondary to greater levels of acetyl-CoA from metabolic reprogramming to β oxidation. The polarization mediated fibrotic repair in the absence of injury by enhancing macrophage/fibroblast signaling. These observations suggest that targeting the mevalonate pathway may abrogate the role of macrophages in dysregulated fibrotic repair.
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Affiliation(s)
| | - Mudit Vaid
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Linlin Gu
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Chao He
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Guo-Qiang Cai
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Qiang Ding
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Dana Davis
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Taylor F Berryhill
- Targeted Metabolomics and Proteomics Laboratory, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Landon S Wilson
- Targeted Metabolomics and Proteomics Laboratory, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Stephen Barnes
- Targeted Metabolomics and Proteomics Laboratory, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jeffrey D Neighbors
- Department of Medicine, and.,Department of Pharmacology, College of Medicine, Penn State University, Hershey, Pennsylvania, USA.,Penn State Cancer Institute, Hershey, Pennsylvania, USA
| | - Raymond J Hohl
- Department of Medicine, and.,Department of Pharmacology, College of Medicine, Penn State University, Hershey, Pennsylvania, USA.,Penn State Cancer Institute, Hershey, Pennsylvania, USA
| | | | - Bradley K Yoder
- Department of Cell, Developmental, and Integrative Biology, and
| | - Ana Leda F Longhini
- Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Vidya Sagar Hanumanthu
- Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ranu Surolia
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - Veena B Antony
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, and.,Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA
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Larson-Casey JL, He C, Carter AB. Mitochondrial quality control in pulmonary fibrosis. Redox Biol 2020; 33:101426. [PMID: 31928788 PMCID: PMC7251238 DOI: 10.1016/j.redox.2020.101426] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/19/2019] [Accepted: 01/03/2020] [Indexed: 12/11/2022] Open
Abstract
Mechanisms underlying the pathogenesis of pulmonary fibrosis remain incompletely understood. Emerging evidence suggests changes in mitochondrial quality control are a critical determinant in many lung diseases, including chronic obstructive pulmonary disease, asthma, pulmonary hypertension, acute lung injury, lung cancer, and in the susceptibility to pulmonary fibrosis. Once thought of as the kidney-bean shaped powerhouses of the cell, mitochondria are now known to form interconnected networks that rapidly and continuously change their size to meet cellular metabolic demands. Mitochondrial quality control modulates cell fate and homeostasis, and diminished mitochondrial quality control results in mitochondrial dysfunction, increased reactive oxygen species (ROS) production, reduced ATP production, and often induces intrinsic apoptosis. Here, we review the role of the mitochondria in alveolar epithelial cells, lung macrophages, and fibroblasts within the context of pulmonary fibrosis.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, United States
| | - Chao He
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, United States
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, 35294, United States; Birmingham VAMC, Birmingham, AL, 35294, United States.
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He C, Larson-Casey JL, Davis D, Hanumanthu VS, Longhini ALF, Thannickal VJ, Gu L, Carter AB. NOX4 modulates macrophage phenotype and mitochondrial biogenesis in asbestosis. JCI Insight 2019; 4:126551. [PMID: 31434799 DOI: 10.1172/jci.insight.126551] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 07/16/2019] [Indexed: 12/17/2022] Open
Abstract
Macrophage activation is implicated in the development of pulmonary fibrosis by generation of profibrotic molecules. Although NADPH oxidase 4 (NOX4) is known to contribute to pulmonary fibrosis, its effects on macrophage activation and mitochondrial redox signaling are unclear. Here, we show that NOX4 is crucial for lung macrophage profibrotic polarization and fibrotic repair after asbestos exposure. NOX4 was elevated in lung macrophages from subjects with asbestosis, and mice harboring a deletion of NOX4 in lung macrophages were protected from asbestos-induced fibrosis. NOX4 promoted lung macrophage profibrotic polarization and increased production of profibrotic molecules that induce collagen deposition. Mechanistically, NOX4 further augmented mitochondrial ROS production and induced mitochondrial biogenesis. Targeting redox signaling and mitochondrial biogenesis prevented the profibrotic polarization of lung macrophages by reducing the production of profibrotic molecules. These observations provide evidence that macrophage NOX4 is a potentially novel therapeutic target to halt the development of asbestos-induced pulmonary fibrosis.
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Affiliation(s)
- Chao He
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, and
| | | | - Dana Davis
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, and
| | - Vidya Sagar Hanumanthu
- Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Ana Leda F Longhini
- Division of Clinical Immunology and Rheumatology, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Victor J Thannickal
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, and.,Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA
| | - Linlin Gu
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, and
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy and Critical Care Medicine, and.,Birmingham Veterans Administration Medical Center, Birmingham, Alabama, USA
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Larson-Casey JL, Carter AB. Reply to Eapen et al.: Dysfunctional Immunity and Microbial Adhesion Molecules in Smoking-induced Pneumonia. Am J Respir Crit Care Med 2019; 199:251-252. [PMID: 30290120 DOI: 10.1164/rccm.201809-1727le] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Affiliation(s)
| | - A Brent Carter
- 1 University of Alabama at Birmingham Birmingham, Alabama and.,2 Birmingham Veterans Administration Medical Center Birmingham, Alabama
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Larson-Casey JL, Gu L, Jackson PL, Briles DE, Hale JY, Blalock JE, Wells JM, Deshane JS, Wang Y, Davis D, Antony VB, Massicano AVF, Lapi SE, Carter AB. Macrophage Rac2 Is Required to Reduce the Severity of Cigarette Smoke-induced Pneumonia. Am J Respir Crit Care Med 2018; 198:1288-1301. [PMID: 29897791 PMCID: PMC6290940 DOI: 10.1164/rccm.201712-2388oc] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 06/12/2018] [Indexed: 01/31/2023] Open
Abstract
RATIONALE Cigarette smoking is prevalent in the United States and is the leading cause of preventable diseases. A prominent complication of smoking is an increase in lower respiratory tract infections (LRTIs). Although LRTIs are known to be increased in subjects that smoke, the mechanism(s) by which this occurs is poorly understood. OBJECTIVES Determine how cigarette smoke (CS) reduces reactive oxygen species (ROS) production by the phagocytic NOX2 (NADPH oxidase 2), which is essential for innate immunity in lung macrophages. METHODS NOX2-derived ROS and Rac2 (Ras-related C3 botulinum toxin substrate 2) activity were determined in BAL cells from wild-type and Rac2-/- mice exposed to CS or cadmium and in BAL cells from subjects that smoke. Host defense to respiratory pathogens was analyzed in mice infected with Streptococcus pneumoniae. MEASUREMENTS AND MAIN RESULTS NOX2-derived ROS in BAL cells was reduced in mice exposed to CS via inhibition of the small GTPase Rac2. These mice had greater bacterial burden and increased mortality compared with air-exposed mice. BAL fluid from CS-exposed mice had increased levels of cadmium, which mediated the effect on Rac2. Similar observations were seen in human subjects that smoke. To support the importance of Rac2 in the macrophage immune response, overexpression of constitutively active Rac2 by lentiviral administration increased NOX2-derived ROS, decreased bacterial burden in lung tissue, and increased survival compared with CS-exposed control mice. CONCLUSIONS These observations suggest that therapies to maintain Rac2 activity in lung macrophages restore host defense against respiratory pathogens and diminish the prevalence of LRTIs in subjects that smoke.
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Affiliation(s)
| | - Linlin Gu
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | - Patricia L. Jackson
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
- Birmingham Veterans Administration Medical Center, Birmingham, Alabama
| | | | | | - J. Edwin Blalock
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | - J. Michael Wells
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
- Birmingham Veterans Administration Medical Center, Birmingham, Alabama
| | - Jessy S. Deshane
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | - Yong Wang
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | - Dana Davis
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | - Veena B. Antony
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
| | | | - Suzanne E. Lapi
- Department of Radiology, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - A. Brent Carter
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine
- Birmingham Veterans Administration Medical Center, Birmingham, Alabama
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He C, Larson-Casey JL, Gu L, Ryan AJ, Murthy S, Carter AB. Cu,Zn-Superoxide Dismutase-Mediated Redox Regulation of Jumonji Domain Containing 3 Modulates Macrophage Polarization and Pulmonary Fibrosis. Am J Respir Cell Mol Biol 2017; 55:58-71. [PMID: 26699812 DOI: 10.1165/rcmb.2015-0183oc] [Citation(s) in RCA: 42] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
M2 macrophages are implicated in the development of pulmonary fibrosis as they generate profibrotic signals. The polarization process, at least in part, is regulated by epigenetic modulation. Because Cu,Zn-superoxide dismutase-induced H2O2 can polarize macrophages to a profibrotic M2 phenotype, we hypothesized that modulation of the redox state of the cell is involved in the epigenetic modulation of the macrophage phenotype. In this study, we show that signal transducer and activator of transcription 6 (STAT6) regulates Jumonji domain containing (Jmjd) 3, a histone H3 lysine 27 demethylase, and mutation of a redox-sensitive cysteine in STAT6 attenuates jmjd3 expression. Moreover, Jmjd3 deficiency abrogates profibrotic M2 gene expression. Treatment with leflunomide, which reduces mitochondrial reactive oxygen species production and tyrosine phosphorylation, inhibits jmjd3 expression and M2 polarization, as well as development of a fibrotic phenotype. Taken together, these observations provide evidence that the redox regulation of Jmjd3 is a unique regulatory mechanism for Cu,Zn-superoxide dismutase-mediated profibrotic M2 polarization. Furthermore, leflunomide, which reduces reactive oxygen species production and tyrosine phosphorylation, may prove to be therapeutic in the treatment of asbestos-induced pulmonary fibrosis.
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Affiliation(s)
- Chao He
- Departments of 1Radiation Oncology and the Graduate Program in Free Radical and Radiation Biology
| | - Jennifer L Larson-Casey
- Departments of 1Radiation Oncology and the Graduate Program in Free Radical and Radiation Biology.,2 Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Linlin Gu
- 2 Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and
| | - Alan J Ryan
- 3 Internal Medicine, Carver College of Medicine, and
| | - Shubha Murthy
- 3 Internal Medicine, Carver College of Medicine, and
| | - A Brent Carter
- Departments of 1Radiation Oncology and the Graduate Program in Free Radical and Radiation Biology.,4 Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa.,5 Iowa City Veterans Administration Center, Iowa City, Iowa.,2 Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and.,6 Birmingham Veterans Administration Center, Birmingham, Alabama
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18
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Gu L, Larson-Casey JL, Carter AB. Macrophages utilize the mitochondrial calcium uniporter for profibrotic polarization. FASEB J 2017; 31:3072-3083. [PMID: 28351840 DOI: 10.1096/fj.201601371r] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 03/13/2017] [Indexed: 11/11/2022]
Abstract
Fibrosis in multiple organs, including the liver, kidney, and lung, often occurs secondary to environmental exposure. Asbestos exposure is one important environmental cause of lung fibrosis. The mechanisms that mediate fibrosis is not fully understood, although mitochondrial oxidative stress in alveolar macrophages is critical for fibrosis development. Mitochondrial Ca2+ levels can be associated with production of reactive oxygen species. Here, we show that patients with asbestosis have higher levels of mitochondrial Ca2+ compared with normal patients. The mitochondrial calcium uniporter (MCU) is a highly selective ion channel that transports Ca2+ into the mitochondrial matrix to modulate metabolism. Asbestos exposure increased mitochondrial Ca2+ influx in alveolar macrophages from wild-type, but not MCU+/-, mice. MCU expression polarized macrophages to a profibrotic phenotype after exposure to asbestos, and the profibrotic polarization was regulated by MCU-mediated ATP production. Profibrotic polarization was abrogated when MCU was absent or its activity was blocked. Of more importance, mice that were deficient in MCU were protected from pulmonary fibrosis. Regulation of mitochondrial Ca2+ suggests that MCU may play a pivotal role in the development of fibrosis and could potentially be a therapeutic target for pulmonary fibrosis.-Gu, L., Larson-Casey, J. L., Carter, A. B. Macrophages utilize the mitochondrial calcium uniporter for profibrotic polarization.
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Affiliation(s)
- Linlin Gu
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Larson-Casey
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A Brent Carter
- Division of Pulmonary, Allergy, and Critical Care Medicine, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA; .,Birmingham Veterans Affairs Medical Center, Birmingham, Alabama, USA
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Larson-Casey JL, Deshane JS, Ryan AJ, Thannickal VJ, Carter AB. Macrophage Akt1 Kinase-Mediated Mitophagy Modulates Apoptosis Resistance and Pulmonary Fibrosis. Immunity 2016; 44:582-596. [PMID: 26921108 DOI: 10.1016/j.immuni.2016.01.001] [Citation(s) in RCA: 250] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Revised: 11/17/2015] [Accepted: 01/04/2016] [Indexed: 12/11/2022]
Abstract
Idiopathic pulmonary fibrosis (IPF) is a devastating lung disorder with increasing incidence. Mitochondrial oxidative stress in alveolar macrophages is directly linked to pulmonary fibrosis. Mitophagy, the selective engulfment of dysfunctional mitochondria by autophagasomes, is important for cellular homeostasis and can be induced by mitochondrial oxidative stress. Here, we show Akt1 induced macrophage mitochondrial reactive oxygen species (ROS) and mitophagy. Mice harboring a conditional deletion of Akt1 in macrophages (Akt1(-/-)Lyz2-cre) and Park2(-/-) mice had impaired mitophagy and reduced active transforming growth factor-β1 (TGF-β1). Although Akt1 increased TGF-β1 expression, mitophagy inhibition in Akt1-overexpressing macrophages abrogated TGF-β1 expression and fibroblast differentiation. Importantly, conditional Akt1(-/-)Lyz2-cre mice and Park2(-/-) mice had increased macrophage apoptosis and were protected from pulmonary fibrosis. Moreover, IPF alveolar macrophages had evidence of increased mitophagy and displayed apoptosis resistance. These observations suggest that Akt1-mediated mitophagy contributes to alveolar macrophage apoptosis resistance and is required for pulmonary fibrosis development.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Jessy S Deshane
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA
| | - Alan J Ryan
- Department of Internal Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Victor J Thannickal
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Birmingham Veterans Administration Medical Center, Birmingham, AL 35294, USA
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL 35294, USA; Birmingham Veterans Administration Medical Center, Birmingham, AL 35294, USA.
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20
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Slusser-Nore A, Larson-Casey JL, Zhang R, Zhou XD, Somji S, Garrett SH, Sens DA, Dunlevy JR. SPARC Expression Is Selectively Suppressed in Tumor Initiating Urospheres Isolated from As+3- and Cd+2-Transformed Human Urothelial Cells (UROtsa) Stably Transfected with SPARC. PLoS One 2016; 11:e0147362. [PMID: 26783756 PMCID: PMC4718619 DOI: 10.1371/journal.pone.0147362] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Accepted: 01/04/2016] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND This laboratory previously analyzed the expression of SPARC in the parental UROtsa cells, their arsenite (As(+3)) and cadmium (Cd(+2))-transformed cell lines, and tumor transplants generated from the transformed cells. It was demonstrated that SPARC expression was down-regulated to background levels in Cd(+2)-and As(+3)-transformed UROtsa cells and tumor transplants compared to parental cells. In the present study, the transformed cell lines were stably transfected with a SPARC expression vector to determine the effect of SPARC expression on the ability of the cells to form tumors in immune-compromised mice. METHODS Real time PCR, western blotting, immunohistochemistry, and immunofluorescence were used to define the expression of SPARC in the As(+3)-and Cd(+2)-transformed cell lines, and urospheres isolated from these cell lines, following their stable transfection with an expression vector containing the SPARC open reading frame (ORF). Transplantation of the cultured cells into immune-compromised mice by subcutaneous injection was used to assess the effect of SPARC expression on tumors generated from the above cell lines and urospheres. RESULTS It was shown that the As(+3)-and Cd(+2)-transformed UROtsa cells could undergo stable transfection with a SPARC expression vector and that the transfected cells expressed both SPARC mRNA and secreted protein. Tumors formed from these SPARC-transfected cells were shown to have no expression of SPARC. Urospheres isolated from cultures of the SPARC-transfected As(+3)-and Cd(+2)-transformed cell lines were shown to have only background expression of SPARC. Urospheres from both the non-transfected and SPARC-transfected cell lines were tumorigenic and thus fit the definition for a population of tumor initiating cells. CONCLUSIONS Tumor initiating cells isolated from SPARC-transfected As(+3)-and Cd(+2)-transformed cell lines have an inherent mechanism to suppress the expression of SPARC mRNA.
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Affiliation(s)
- Andrea Slusser-Nore
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Jennifer L. Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy and Critical Medicine, the University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Ruowen Zhang
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Xu Dong Zhou
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Seema Somji
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Scott H. Garrett
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Donald A. Sens
- Department of Pathology, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
| | - Jane R. Dunlevy
- Department of Basic Sciences, School of Medicine and Health Sciences, University of North Dakota, Grand Forks, North Dakota, United States of America
- * E-mail:
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Abstract
Because transforming growth factor-β (TGF-β1) induces differentiation of fibroblasts to myofibroblasts, we developed a protocol to evaluate alveolar macrophage-derived TGF-β1 regulation of lung fibroblast differentiation (Larson-Casey et al., 2016). The protocol allows evaluating the ability of mouse bronchoalveolar lavage (BAL) fluid to alter fibroblast differentiation. Fibroblast differentiation was measured by the expression of α-smooth muscle actin (α-SMA). BACKGROUND Alveolar macrophages play an integral role in pulmonary fibrosis development by increasing the expression of TGF-β1 (He et al., 2011). Our prior data demonstrate that alveolar macrophages are a critical source of TGF-β1 as mice harboring a conditional deletion of TGF-β1 in macrophages were protected from pulmonary fibrosis (Larson-Casey et al., 2016). The expression of α-SMA is a defining feature of myofibroblasts, and TGF-β1 is a well-characterized pro-fibrotic mediator that induces transformation of fibroblasts to myofibroblasts both in vitro (Desmoulière et al., 1993) and in vivo (Sime et al., 1997). Prior studies exposed fibroblasts to recombinant TGF-β1 to show its effect on differentiation and function (Horowitz et al., 2007). Here we have developed a protocol for determining the ability of mouse BAL fluid to alter the differentiation of human lung fibroblasts to myofibroblasts, the cells that produce extracellular matrix proteins.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35294
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35294; Birmingham Veterans Administration Medical Center, Birmingham, AL, USA 35294
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Abstract
The production of reactive oxygen species, including H2O2, is a process that can be used in signaling, cell death, or immune response. To quantify oxidative stress in cells, a fluorescence technique has been modified from a previously described method to measure H2O2 release from cells (1-5). This assay takes advantage of H2O2-mediated oxidation of horseradish peroxidase (HRP) to Complex I, which, in turn, oxidizes p-hydroxyphenylacetic acid (pHPA) to a stable, fluorescent pHPA dimer (2,2'-dihydroxy-biphenyl-5,5' diacetate [(pHPA)2]). The H2O2-dependent HRP-mediated oxidation of pHPA is a sensitive and specific assay for quantifying H2O2 release from cells. This assay can measure H2O2 release from whole cells, mitochondria, or the NADPH oxidase.
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Affiliation(s)
- Jennifer L Larson-Casey
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35294
| | - A Brent Carter
- Department of Medicine, Division of Pulmonary, Allergy, and Critical Care Medicine, University of Alabama at Birmingham, Birmingham, AL, USA 35294; Birmingham Veterans Administration Medical Center, Birmingham, AL, USA 35294
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23
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Osborn-Heaford HL, Murthy S, Gu L, Larson-Casey JL, Ryan AJ, Shi L, Glogauer M, Neighbors JD, Hohl R, Carter AB. Targeting the isoprenoid pathway to abrogate progression of pulmonary fibrosis. Free Radic Biol Med 2015; 86:47-56. [PMID: 25958207 PMCID: PMC4554879 DOI: 10.1016/j.freeradbiomed.2015.04.031] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Revised: 04/07/2015] [Accepted: 04/27/2015] [Indexed: 11/22/2022]
Abstract
Fibrotic remodeling in lung injury is a major cause of morbidity. The mechanism that mediates the ongoing fibrosis is unclear, and there is no available treatment to abate the aberrant repair. Reactive oxygen species (ROS) have a critical role in inducing fibrosis by modulating extracellular matrix deposition. Specifically, mitochondrial hydrogen peroxide (H2O2) production by alveolar macrophages is directly linked to pulmonary fibrosis as inhibition of mitochondrial H2O2 attenuates the fibrotic response in mice. Prior studies indicate that the small GTP-binding protein, Rac1, directly mediates H2O2 generation in the mitochondrial intermembrane space. Geranylgeranylation of the C-terminal cysteine residue (Cys(189)) is required for Rac1 activation and mitochondrial import. We hypothesized that impairment of geranylgeranylation would limit mitochondrial oxidative stress and, thus, abrogate progression of pulmonary fibrosis. By targeting the isoprenoid pathway with a novel agent, digeranyl bisphosphonate (DGBP), which impairs geranylgeranylation, we demonstrate that Rac1 mitochondrial import, mitochondrial oxidative stress, and progression of the fibrotic response to lung injury are significantly attenuated. These observations reveal that targeting the isoprenoid pathway to alter Rac1 geranylgeranylation halts the progression of pulmonary fibrosis after lung injury.
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Affiliation(s)
| | | | - Linlin Gu
- Deparment of Medicine, University of Alabama at Birmingham, AL
| | - Jennifer L Larson-Casey
- Free Radical and Radiation Biology Program, University of Iowa
- Deparment of Medicine, University of Alabama at Birmingham, AL
| | - Alan J Ryan
- Department of Internal Medicine, University of Iowa
| | - Lei Shi
- Human Toxicology Program, University of Iowa
| | - Michael Glogauer
- Canadian Institutes of Health Research Group in Matrix Dynamics, University of Toronto, Toronto, Ontario, Canada
| | | | - Raymond Hohl
- Department of Internal Medicine, University of Iowa
- Department of Pharmacology, University of Iowa
| | - A Brent Carter
- Department of Internal Medicine, University of Iowa
- Free Radical and Radiation Biology Program, University of Iowa
- Human Toxicology Program, University of Iowa
- Deparment of Medicine, University of Alabama at Birmingham, AL
- Iowa City VA Healthcare System, Iowa City, IA
- Birmingham VAMC, Birmingham, AL
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Murthy S, Larson-Casey JL, Ryan AJ, He C, Kobzik L, Carter AB. Alternative activation of macrophages and pulmonary fibrosis are modulated by scavenger receptor, macrophage receptor with collagenous structure. FASEB J 2015; 29:3527-36. [PMID: 25953850 PMCID: PMC4511206 DOI: 10.1096/fj.15-271304] [Citation(s) in RCA: 82] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2015] [Accepted: 04/27/2015] [Indexed: 01/04/2023]
Abstract
Alternative activation of alveolar macrophages is linked to fibrosis following exposure to asbestos. The scavenger receptor, macrophage receptor with collagenous structure (MARCO), provides innate immune defense against inhaled particles and pathogens; however, a receptor for asbestos has not been identified. We hypothesized that MARCO acts as an initial signaling receptor for asbestos, polarizes macrophages to a profibrotic M2 phenotype, and is required for the development of asbestos-induced fibrosis. Compared with normal subjects, alveolar macrophages isolated from patients with asbestosis express higher amounts of MARCO and have greater profibrotic polarization. Arginase 1 (40-fold) and IL-10 (265-fold) were higher in patients. In vivo, the genetic deletion of MARCO attenuated the profibrotic environment and pulmonary fibrosis in mice exposed to chrysotile. Moreover, alveolar macrophages from MARCO(-/-) mice polarize to an M1 phenotype, whereas wild-type mice have higher Ym1 (>3.0-fold) and nearly 7-fold more active TGF-β1 in bronchoalveolar lavage (BAL) fluid (BALF). Arg(432) and Arg(434) in domain V of MARCO are required for the polarization of macrophages to a profibrotic phenotype as mutation of these residues reduced FIZZ1 expression (17-fold) compared with cells expressing MARCO. These observations demonstrate that a macrophage membrane protein regulates the fibrotic response to lung injury and suggest a novel target for therapeutic intervention.
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Affiliation(s)
- Shubha Murthy
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Jennifer L Larson-Casey
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Alan J Ryan
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Chao He
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - Lester Kobzik
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
| | - A Brent Carter
- *Department of Internal Medicine, Department of Radiation Oncology, and the Graduate Program in Free Radical and Radiation Biology, Carver College of Medicine, Iowa City, Iowa, USA; Harvard School of Public Health, Boston, Massachusetts, USA; Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa, USA; Iowa City Veterans Affairs Health Care System, Iowa City, Iowa, USA; and University of Alabama at Birmingham, Birmingham, Alabama, USA
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Ryan AJ, Larson-Casey JL, He C, Murthy S, Carter AB. Asbestos-induced disruption of calcium homeostasis induces endoplasmic reticulum stress in macrophages. J Biol Chem 2014; 289:33391-403. [PMID: 25324550 PMCID: PMC4246095 DOI: 10.1074/jbc.m114.579870] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2014] [Revised: 10/10/2014] [Indexed: 01/05/2023] Open
Abstract
Although the mechanisms for fibrosis development remain largely unknown, recent evidence indicates that endoplasmic reticulum (ER) stress and activation of the unfolded protein response (UPR) may act as an important fibrotic stimulus in diseased lungs. ER stress is observed in lungs of patients with idiopathic pulmonary fibrosis. In this study we evaluated if ER stress and the UPR was present in macrophages exposed to chrysotile asbestos and if ER stress in macrophages was associated with asbestos-induced pulmonary fibrosis. Macrophages exposed to chrysotile had elevated transcript levels of several ER stress genes. Macrophages loaded with the Ca(2+)-sensitive dye Fura2-AM showed that cytosolic Ca(2+) increased significantly within minutes after chrysotile exposure and remained elevated for a prolonged time. Chrysotile-induced increases in cytosolic Ca(2+) were partially inhibited by either anisomycin, an inhibitor of passive Ca(2+) leak from the ER, or 1,2-bis(2-aminophenoxyl)ethane-N,N,N',N'-tetraacetic acid (BAPTA-AM), an intracellular Ca(2+) chelator known to deplete ER Ca(2+) stores. Anisomycin inhibited X-box-binding protein 1 (XBP1) mRNA splicing and reduced immunoglobulin-binding protein (BiP) levels, whereas BAPTA-AM increased XBP1 splicing and BiP expression, suggesting that ER calcium depletion may be one factor contributing to ER stress in cells exposed to chrysotile. To evaluate ER stress in vivo, asbestos-exposed mice showed fibrosis development, and alveolar macrophages from fibrotic mice showed increased expression of BiP. Bronchoalveolar macrophages from asbestosis patients showed increased expression of several ER stress genes compared with normal subjects. These findings suggest that alveolar macrophages undergo ER stress, which is associated with fibrosis development.
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Affiliation(s)
| | - Jennifer L Larson-Casey
- Radiation Oncology and Program in Free Radical and Radiation Biology, Carver College of Medicine
| | - Chao He
- Radiation Oncology and Program in Free Radical and Radiation Biology, Carver College of Medicine
| | | | - A Brent Carter
- From the Departments of Internal Medicine, Radiation Oncology and Program in Free Radical and Radiation Biology, Carver College of Medicine, Human Toxicology, College of Public Health, University of Iowa, and Iowa City Veterans Administration Center, Iowa City, Iowa 52242
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Larson-Casey JL, Murthy S, Ryan AJ, Carter AB. Modulation of the mevalonate pathway by akt regulates macrophage survival and development of pulmonary fibrosis. J Biol Chem 2014; 289:36204-19. [PMID: 25378391 DOI: 10.1074/jbc.m114.593285] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Protein kinase B (Akt) is a key effector of multiple cellular processes, including cell survival. Akt, a serine/threonine kinase, is known to increase cell survival by regulation of the intrinsic pathway for apoptosis. In this study, we found that Akt modulated the mevalonate pathway, which is also linked to cell survival, by increasing Rho GTPase activation. Akt modulated the pathway by phosphorylating mevalonate diphosphate decarboxylase (MDD) at Ser(96). This phosphorylation in macrophages increased activation of Rac1, which enhanced macrophage survival because mutation of MDD (MDDS96A) induced apoptosis. Akt-mediated activation in macrophages was specific for Rac1 because Akt did not increase activity of other Rho GTP-binding proteins. The relationship between Akt and Rac1 was biologically relevant because Akt(+/-) mice had significantly less active Rac1 in alveolar macrophages, and macrophages from Akt(+/-) mice had an increase in active caspase-9 and -3. More importantly, Akt(+/-) mice were significantly protected from the development of pulmonary fibrosis, suggesting that macrophage survival is associated with the fibrotic phenotype. These observations for the first time suggest that Akt plays a critical role in the development and progression of pulmonary fibrosis by enhancing macrophage survival via modulation of the mevalonate pathway.
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Affiliation(s)
| | - Shubha Murthy
- the Department of Internal Medicine, Carver College of Medicine, and
| | - Alan J Ryan
- the Department of Internal Medicine, Carver College of Medicine, and
| | - A Brent Carter
- From the Department of Radiation Oncology and Program in Free Radical and Radiation Biology, the Department of Internal Medicine, Carver College of Medicine, and the Department of Human Toxicology, College of Public Health, University of Iowa, Iowa City, Iowa 52242 and the Iowa City Veterans Affairs Health Care System, Iowa City, Iowa 52242
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