Publications by authors named "Gökhan M Mutlu"

144 Publications

Single-cell metabolic imaging reveals a SLC2A3-dependent glycolytic burst in motile endothelial cells.

Nat Metab 2021 May 24;3(5):714-727. Epub 2021 May 24.

Department of Medicine, Biological Sciences Division, The University of Chicago, Chicago, IL, USA.

Single-cell motility is spatially heterogeneous and driven by metabolic energy. Directly linking cell motility to cell metabolism is technically challenging but biologically important. Here, we use single-cell metabolic imaging to measure glycolysis in individual endothelial cells with genetically encoded biosensors capable of deciphering metabolic heterogeneity at subcellular resolution. We show that cellular glycolysis fuels endothelial activation, migration and contraction and that sites of high lactate production colocalize with active cytoskeletal remodelling within an endothelial cell. Mechanistically, RhoA induces endothelial glycolysis for the phosphorylation of cofilin and myosin light chain in order to reorganize the cytoskeleton and thus control cell motility; RhoA activation triggers a glycolytic burst through the translocation of the glucose transporter SLC2A3/GLUT3 to fuel the cellular contractile machinery, as demonstrated across multiple endothelial cell types. Our data indicate that Rho-GTPase signalling coordinates energy metabolism with cytoskeleton remodelling to regulate endothelial cell motility.
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http://dx.doi.org/10.1038/s42255-021-00390-yDOI Listing
May 2021

More to Explore: Further Definition of Risk Factors for COPD - Differential Gender Difference, Modest Elevation in PM., and e-Cigarette Use.

Front Physiol 2021 5;12:669152. Epub 2021 May 5.

Division of Molecular Medicine, Department of Anesthesiology, Division of Cardiology, Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, United States.

Chronic obstructive pulmonary disease (COPD) is a severe respiratory disease with high morbidity and mortality, representing the third leading cause of death worldwide. Traditional risk factors for COPD include aging, genetic predisposition, cigarette smoking, exposure to environmental pollutes, occupational exposure, and individual or parental respiratory disease history. In addition, latest studies have revealed novel and emerging risk factors. In this review, differential gender difference as a factor for COPD development at different territories is discussed for the first time. First, women seem to have more COPD, while more women die of COPD or have more severe COPD, in Western societies. This seems different from the impression that COPD dominants in men, which is true in Eastern societies. It might be related to higher rate of cigarette smoking in women in developed countries (i.e., 12.0% of women in United States smoke vs. 2.2% in China). Nonetheless, women in Eastern societies are exposed to more biomass usage. Second, modest elevation in PM. levels at >∼21.4-32.7 μg/m, previously considered "cleaner air," is associated with incidence of COPD, indicating that more stringent goals should be set for the reduction of PM. levels to prevent COPD development. Last but not least, e-cigarette use, which has become an epidemic especially among adolescents as officially declared by the United States government, has severe adverse effects that may cause development of COPD early in life. Built upon an overview of the established risk factors for COPD primarily focusing on cigarette smoking and environmental pollutions, the present review further discusses novel concepts, mechanisms, and solutions evolved around the emerging risk factors for COPD discussed above, understanding of which would likely enable better intervention of this devastating disease.
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http://dx.doi.org/10.3389/fphys.2021.669152DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8131967PMC
May 2021

The role of metabolic reprogramming and de novo amino acid synthesis in collagen protein production by myofibroblasts: implications for organ fibrosis and cancer.

Amino Acids 2021 May 8. Epub 2021 May 8.

Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, 5841 S. Maryland Avenue, MC6026, Chicago, IL, 60637, USA.

Fibrosis is a pathologic condition resulting from aberrant wound healing responses that lead to excessive accumulation of extracellular matrix components, distortion of organ architecture, and loss of organ function. Fibrotic disease can affect every organ system; moreover, fibrosis is an important microenvironmental component of many cancers, including pancreatic, cervical, and hepatocellular cancers. Fibrosis is also an independent risk factor for cancer. Taken together, organ fibrosis contributes to up to 45% of all deaths worldwide. There are no approved therapies that halt or reverse fibrotic disease, highlighting the great need for novel therapeutic targets. At the heart of almost all fibrotic disease is the TGF-β-mediated differentiation of fibroblasts into myofibroblasts, the primary cell type responsible for the production of collagen and other matrix proteins and distortion of tissue architecture. Recent advances, particularly in the field of lung fibrosis, have highlighted the role that metabolic reprogramming plays in the pathogenic phenotype of myofibroblasts, particularly the induction of de novo amino acid synthesis pathways that are required to support collagen matrix production by these cells. In this review, we will discuss the metabolic changes associated with myofibroblast differentiation, focusing on the de novo production of glycine and proline, two amino acids which compose over half of the primary structure of collagen protein. We will also discuss the important role that synthesis of these amino acids plays in regulating cellular redox balance and epigenetic state.
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http://dx.doi.org/10.1007/s00726-021-02996-8DOI Listing
May 2021

Update in Critical Care 2020.

Am J Respir Crit Care Med 2021 May;203(9):1088-1098

Institut National de la Santé et de la Recherche Médicale, Poitiers, France; and.

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http://dx.doi.org/10.1164/rccm.202102-0336UPDOI Listing
May 2021

The lung microenvironment shapes a dysfunctional response of alveolar macrophages in aging.

J Clin Invest 2021 Feb;131(4)

Department of Medicine, Division of Pulmonary and Critical Care Medicine, Northwestern University, Chicago, Illinois, USA.

Alveolar macrophages orchestrate the response to viral infections. Age-related changes in these cells may underlie the differential severity of pneumonia in older patients. We performed an integrated analysis of single-cell RNA-Seq data that revealed homogenous age-related changes in the alveolar macrophage transcriptome in humans and mice. Using genetic lineage tracing with sequential injury, heterochronic adoptive transfer, and parabiosis, we found that the lung microenvironment drove an age-related resistance of alveolar macrophages to proliferation that persisted during influenza A viral infection. Ligand-receptor pair analysis localized these changes to the extracellular matrix, where hyaluronan was increased in aged animals and altered the proliferative response of bone marrow-derived macrophages to granulocyte macrophage colony-stimulating factor (GM-CSF). Our findings suggest that strategies targeting the aging lung microenvironment will be necessary to restore alveolar macrophage function in aging.
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http://dx.doi.org/10.1172/JCI140299DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919859PMC
February 2021

SARS-CoV-2 infection reduces Krüppel-Like Factor 2 in human lung autopsy.

bioRxiv 2021 Jan 18. Epub 2021 Jan 18.

Acute respiratory distress syndrome (ARDS) occurred in ~12% of hospitalized COVID-19 patients in a recent New York City cohort. Pulmonary endothelial dysfunction, characterized by increased expression of inflammatory genes and increased monolayer permeability, is a major component of ARDS. Vascular leak results in parenchymal accumulation of leukocytes, protein, and extravascular water, leading to pulmonary edema, ischemia, and activation of coagulation associated with COVID-19. Endothelial inflammation further contributes to uncontrolled cytokine storm in ARDS. We have recently demonstrated that Kruppel-like factor 2 (KLF2), a transcription factor which promotes endothelial quiescence and monolayer integrity, is significantly reduced in experimental models of ARDS. Lung inflammation and high-tidal volume ventilation result in reduced KLF2, leading to pulmonary endothelial dysfunction and acute lung injury. Mechanistically, we found that KLF2 is a potent transcriptional activator of Rap guanine nucleotide exchange factor 3 (RAPGEF3) which orchestrates and maintains vascular integrity. Moreover, KLF2 regulates multiple genome-wide association study (GWAS)-implicated ARDS genes. Whether lung KLF2 is regulated by SARS-CoV-2 infection is unknown. Here we report that endothelial KLF2 is significantly reduced in human lung autopsies from COVID-19 patients, which supports that ARDS due to SARS-CoV-2 is a vascular phenotype possibly attributed to KLF2 down-regulation. We provide additional data demonstrating that KLF2 is down-regulated in SARS-CoV infection in mice.
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http://dx.doi.org/10.1101/2021.01.15.426691DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7814823PMC
January 2021

Metabolic requirements of pulmonary fibrosis: role of fibroblast metabolism.

FEBS J 2021 Jan 3. Epub 2021 Jan 3.

Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, IL, USA.

Fibrosis is a pathologic condition characterized by excessive deposition of extracellular matrix and chronic scaring that can affect every organ system. Organ fibrosis is associated with significant morbidity and mortality, contributing to as many as 45% of all deaths in the developed world. In the lung, many chronic lung diseases may lead to fibrosis, the most devastating being idiopathic pulmonary fibrosis (IPF), which affects approximately 3 million people worldwide and has a median survival of 3.8 years. Currently approved therapies for IPF do not significantly extend lifespan, and thus, there is pressing need for novel therapeutic strategies to treat IPF and other fibrotic diseases. At the heart of pulmonary fibrosis are myofibroblasts, contractile cells with characteristics of both fibroblasts and smooth muscle cells, which are the primary cell type responsible for matrix deposition in fibrotic diseases. Much work has centered around targeting the extracellular growth factors and intracellular signaling regulators of myofibroblast differentiation. Recently, metabolic changes associated with myofibroblast differentiation have come to the fore as targetable mechanisms required for myofibroblast function. In this review, we will discuss the metabolic changes associated with myofibroblast differentiation, as well as the mechanisms by which these changes promote myofibroblast function. We will then discuss the potential for this new knowledge to lead to the development of novel therapies for IPF and other fibrotic diseases.
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http://dx.doi.org/10.1111/febs.15693DOI Listing
January 2021

IL-6 Inhibition in Critically Ill COVID-19 Patients Is Associated With Increased Secondary Infections.

Front Med (Lausanne) 2020 28;7:583897. Epub 2020 Oct 28.

Department of Medicine, University of Chicago, Chicago, IL, United States.

Anti-inflammatory therapies such as IL-6 inhibition have been proposed for COVID-19 in a vacuum of evidence-based treatment. However, abrogating the inflammatory response in infectious diseases may impair a desired host response and pre-dispose to secondary infections. We retrospectively reviewed the medical record of critically ill COVID-19 patients during an 8-week span and compared the prevalence of secondary infection and outcomes in patients who did and did not receive tocilizumab. Additionally, we included representative histopathologic post-mortem findings from several COVID-19 cases that underwent autopsy at our institution. One hundred eleven patients were identified, of which 54 had received tocilizumab while 57 had not. Receiving tocilizumab was associated with a higher risk of secondary bacterial (48.1 vs. 28.1%; = 0.029 and fungal (5.6 vs. 0%; = 0.112) infections. Consistent with higher number of infections, patients who received tocilizumab had higher mortality (35.2 vs. 19.3%; = 0.020). Seven cases underwent autopsy. In three cases who received tocilizumab, there was evidence of pneumonia on pathology. Of the four cases that had not been given tocilizumab, two showed evidence of aspiration pneumonia and two exhibited diffuse alveolar damage. Experimental therapies are currently being applied to COVID-19 outside of clinical trials. Anti-inflammatory therapies such as anti-IL-6 therapy have the potential to impair viral clearance, pre-dispose to secondary infection, and cause harm. We seek to raise physician awareness of these issues and highlight the need to better understand the immune response in COVID-19.
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http://dx.doi.org/10.3389/fmed.2020.583897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7655919PMC
October 2020

IL6 inhibition in critically ill COVID-19 patients is associated with increased secondary infections.

medRxiv 2020 Sep 12. Epub 2020 Sep 12.

Background: Anti-inflammatory therapies such as IL-6 inhibition have been proposed for COVID-19 in a vacuum of evidence-based treatment. However, abrogating the inflammatory response in infectious diseases may impair a desired host response and predispose to secondary infections.

Methods: We retrospectively reviewed the medical record of critically ill COVID-19 patients during an 8-week span and compared the prevalence of secondary infection and outcomes in patients who did and did not receive tocilizumab. Additionally, we included representative histopathologic post-mortem findings from several COVID-19 cases that underwent autopsy at our institution.

Results: 111 patients were identified, of which 54 had received tocilizumab while 57 had not. Receiving tocilizumab was associated with a higher risk of secondary bacterial (48.1% vs. 28.1%, p=0.029 and fungal (5.6% vs. 0%, p=0.112) infections. Consistent with higher number of infections, patients who received tocilizumab had higher mortality (35.2% vs. 19.3%, p=0.020). Seven cases underwent autopsy. In 3 cases who received tocilizumab, there was evidence of pneumonia on pathology. Of the 4 cases that had not been given tocilizumab, 2 showed evidence of aspiration pneumonia and 2 exhibited diffuse alveolar damage.

Conclusions: Experimental therapies are currently being applied to COVID-19 outside of clinical trials. Anti-inflammatory therapies such as anti-IL-6 therapy have the potential to impair viral clearance, predispose to secondary infection, and cause harm. We seek to raise physician awareness of these issues and highlight the need to better understand the immune response in COVID-19.
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http://dx.doi.org/10.1101/2020.05.15.20103531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7491533PMC
September 2020

Late onset infectious complications and safety of tocilizumab in the management of COVID-19.

J Med Virol 2021 03 21;93(3):1459-1464. Epub 2020 Aug 21.

Department of Medicine, Section of Infectious Diseases and Global Health, University of Chicago Medicine, Chicago, Illinois.

Background: Tocilizumab (TCZ) has been used in the management of COVID-19-related cytokine release syndrome (CRS). Concerns exist regarding the risk of infections and drug-related toxicities. We sought to evaluate the incidence of these TCZ complications among COVID-19 patients.

Methods: All adult inpatients with COVID-19 between 1 March and 25 April 2020 that received TCZ were included. We compared the rate of late-onset infections (>48 hours following admission) to a control group matched according to intensive care unit admission and mechanical ventilation requirement. Post-TCZ toxicities evaluated included: elevated liver function tests (LFTs), GI perforation, diverticulitis, neutropenia, hypertension, allergic reactions, and infusion-related reactions.

Results: Seventy-four patients were included in each group. Seventeen infections in the TCZ group (23%) and 6 (8%) infections in the control group occurred >48 hours after admission (P = .013). Most infections were bacterial with pneumonia being the most common manifestation. Among patients receiving TCZ, LFT elevations were observed in 51%, neutropenia in 1.4%, and hypertension in 8%. The mortality rate among those that received TCZ was greater than the control (39% versus 23%, P = .03).

Conclusion: Late onset infections were significantly more common among those receiving TCZ. Combining infections and TCZ-related toxicities, 61% of patients had a possible post-TCZ complication. While awaiting clinical trial results to establish the efficacy of TCZ for COVID-19 related CRS, the potential for infections and TCZ related toxicities should be carefully weighed when considering use.
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http://dx.doi.org/10.1002/jmv.26429DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7436682PMC
March 2021

TGF-β Promotes Metabolic Reprogramming in Lung Fibroblasts via mTORC1-dependent ATF4 Activation.

Am J Respir Cell Mol Biol 2020 11;63(5):601-612

Section of Pulmonary and Critical Care Medicine, Department of Medicine, The University of Chicago, Chicago, Illinois.

Idiopathic pulmonary fibrosis is a fatal interstitial lung disease characterized by the TGF-β (transforming growth factor-β)-dependent differentiation of lung fibroblasts into myofibroblasts, which leads to excessive deposition of collagen proteins and progressive scarring. We have previously shown that synthesis of collagen by myofibroblasts requires synthesis of glycine, the most abundant amino acid found in collagen protein. TGF-β upregulates the expression of the enzymes of the serine-glycine synthesis pathway in lung fibroblasts; however, the transcriptional and signaling regulators of this pathway remain incompletely understood. Here, we demonstrate that TGF-β promotes accumulation of ATF4 (activating transcription factor 4), which is required for increased expression of the serine-glycine synthesis pathway enzymes in response to TGF-β. We found that induction of the integrated stress response (ISR) contributes to TGF-β-induced ATF4 activity; however, the primary driver of ATF4 downstream of TGF-β is activation of mTORC1 (mTOR Complex 1). TGF-β activates the PI3K-Akt-mTOR pathway, and inhibition of PI3K prevents activation of downstream signaling and induction of ATF4. Using a panel of mTOR inhibitors, we found that ATF4 activation is dependent on mTORC1, independent of mTORC2. Rapamycin, which incompletely and allosterically inhibits mTORC1, had no effect on TGF-β-mediated induction of ATF4; however, Rapalink-1, which specifically targets the kinase domain of mTORC1, completely inhibited ATF4 induction and metabolic reprogramming downstream of TGF-β. Our results provide insight into the mechanisms of metabolic reprogramming in myofibroblasts and clarify contradictory published findings on the role of mTOR inhibition in myofibroblast differentiation.
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http://dx.doi.org/10.1165/rcmb.2020-0143OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7605163PMC
November 2020

Ultrasensitive digital quantification of cytokines and bacteria predicts septic shock outcomes.

Nat Commun 2020 05 25;11(1):2607. Epub 2020 May 25.

Pritzker School of Molecular Engineering, The University of Chicago, Chicago, IL, 60637, USA.

Quantification of pathogen and host biomarkers is essential for the diagnosis, monitoring, and treatment of infectious diseases. Here, we demonstrate sensitive and rapid quantification of bacterial load and cytokines from human biological samples to generate actionable hypotheses. Our digital assay measures IL-6 and TNF-α proteins, gram-negative (GN) and gram-positive (GP) bacterial DNA, and the antibiotic-resistance gene bla with femtomolar sensitivity. We use our method to characterize bronchoalveolar lavage fluid from patients with asthma, and find elevated GN bacteria and IL-6 levels compared to healthy subjects. We then analyze plasma from patients with septic shock and find that increasing levels of IL-6 and bla are associated with mortality, while decreasing IL-6 levels are associated with recovery. Surprisingly, lower GN bacteria levels are associated with higher probability of death. Applying decision-tree analysis to our measurements, we are able to predict mortality and rate of recovery from septic shock with over 90% accuracy.
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http://dx.doi.org/10.1038/s41467-020-16124-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7248118PMC
May 2020

The Airway Epithelial Response to Air Pollution: It's Not Just Inflammation.

Am J Respir Cell Mol Biol 2020 08;63(2):139-140

Department of MedicineThe University of ChicagoChicago, Illinois.

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http://dx.doi.org/10.1165/rcmb.2020-0116EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7397764PMC
August 2020

Endogenous itaconate is not required for particulate matter-induced NRF2 expression or inflammatory response.

Elife 2020 04 7;9. Epub 2020 Apr 7.

Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, United States.

Particulate matter (PM) air pollution causes cardiopulmonary mortality via macrophage-driven lung inflammation; however, the mechanisms are incompletely understood. RNA-sequencing demonstrated () as one of the top genes induced by PM in macrophages. encodes a mitochondrial enzyme that produces itaconate, which has been shown to exert anti-inflammatory effects via NRF2 after LPS. Here, we demonstrate that PM induces Acod1 and itaconate, which reduced mitochondrial respiration via complex II inhibition. Using mice, we found that Acod1/endogenous itaconate does not affect PM-induced inflammation or NRF2 activation in macrophages in vitro or in vivo. In contrast, exogenous cell permeable itaconate, 4-octyl itaconate (OI) attenuated PM-induced inflammation in macrophages. OI was sufficient to activate NRF2 in macrophages; however, NRF2 was not required for the anti-inflammatory effects of OI. We conclude that the effects of itaconate production on inflammation are stimulus-dependent, and that there are important differences between endogenous and exogenously-applied itaconate.
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http://dx.doi.org/10.7554/eLife.54877DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7185992PMC
April 2020

Suppression of Superoxide-Hydrogen Peroxide Production at Site IQ of Mitochondrial Complex I Attenuates Myocardial Stunning and Improves Postcardiac Arrest Outcomes.

Crit Care Med 2020 02;48(2):e133-e140

Section of Emergency Medicine, Department of Medicine, University of Chicago, Chicago, IL.

Objectives: Cardiogenic shock following cardiopulmonary resuscitation for sudden cardiac arrest is common, occurring even in the absence of acute coronary artery occlusion, and contributes to high rates of postcardiopulmonary resuscitation mortality. The pathophysiology of this shock is unclear, and effective therapies for improving clinical outcomes are lacking.

Design: Laboratory investigation.

Setting: University laboratory.

Subjects: C57BL/6 adult female mice.

Interventions: Anesthetized and ventilated adult female C57BL/6 wild-type mice underwent a 4, 8, 12, or 16-minute potassium chloride-induced cardiac arrest followed by 90 seconds of cardiopulmonary resuscitation. Mice were then blindly randomized to a single IV injection of vehicle (phosphate-buffered saline) or suppressor of site IQ electron leak, an inhibitor of superoxide production by complex I of the mitochondrial electron transport chain. Suppressor of site IQ electron leak and vehicle were administered during cardiopulmonary resuscitation.

Measurements And Main Results: Using a murine model of asystolic cardiac arrest, we discovered that duration of cardiac arrest prior to cardiopulmonary resuscitation determined postresuscitation success rates, degree of neurologic injury, and severity of myocardial dysfunction. Post-cardiopulmonary resuscitation cardiac dysfunction was not associated with myocardial necrosis, apoptosis, inflammation, or mitochondrial permeability transition pore opening. Furthermore, left ventricular function recovered within 72 hours of cardiopulmonary resuscitation, indicative of myocardial stunning. Postcardiopulmonary resuscitation, the myocardium exhibited increased reactive oxygen species and evidence of mitochondrial injury, specifically reperfusion-induced reactive oxygen species generation at electron transport chain complex I. Suppressor of site IQ electron leak, which inhibits complex I-dependent reactive oxygen species generation by suppression of site IQ electron leak, decreased myocardial reactive oxygen species generation and improved postcardiopulmonary resuscitation myocardial function, neurologic outcomes, and survival.

Conclusions: The severity of cardiogenic shock following asystolic cardiac arrest is dependent on the length of cardiac arrest prior to cardiopulmonary resuscitation and is mediated by myocardial stunning resulting from mitochondrial electron transport chain complex I dysfunction. A novel pharmacologic agent targeting this mechanism, suppressor of site IQ electron leak, represents a potential, practical therapy for improving sudden cardiac arrest resuscitation outcomes.
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http://dx.doi.org/10.1097/CCM.0000000000004095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6964871PMC
February 2020

FGFR2 Is Required for AEC2 Homeostasis and Survival after Bleomycin-induced Lung Injury.

Am J Respir Cell Mol Biol 2020 05;62(5):608-621

Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois; and.

Alveolar epithelial cell (AEC) injury is central to the pathogenesis of pulmonary fibrosis. Epithelial FGF (fibroblast growth factor) signaling is essential for recovery from hyperoxia- and influenza-induced lung injury, and treatment with FGFs is protective in experimental lung injury. The cell types involved in the protective effect of FGFs are not known. We hypothesized that FGF signaling in type II AECs (AEC2s) is critical in bleomycin-induced lung injury and fibrosis. To test this hypothesis, we generated mice with tamoxifen-inducible deletion of FGFR1-3 (fibroblast growth factor receptors 1, 2, and 3) in surfactant protein C-positive (SPC) AEC2s (SPC triple conditional knockout [SPC-TCKO]). In the absence of injury, SPC-TCKO mice had fewer AEC2s, decreased (surfactant protein C gene) expression, increased alveolar diameter, and increased collagen deposition. After intratracheal bleomycin administration, SPC-TCKO mice had increased mortality, lung edema, and BAL total protein, and flow cytometry and immunofluorescence revealed a loss of AEC2s. To reduce mortality of SPC-TCKO mice to less than 50%, a 25-fold dose reduction of bleomycin was required. Surviving bleomycin-injured SPC-TCKO mice had increased collagen deposition, fibrosis, and ACTA2 expression and decreased epithelial gene expression. Inducible inactivation of individual or revealed that , but not , was responsible for the increased mortality and lung injury after bleomycin administration. In conclusion, AEC2-specific FGFR2 is critical for survival in response to bleomycin-induced lung injury. These data also suggest that a population of SPC AEC2s require FGFR2 signaling for maintenance in the adult lung. Preventing epithelial FGFR inhibition and/or activating FGFRs in alveolar epithelium may therefore represent a novel approach to treating lung injury and reducing fibrosis.
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http://dx.doi.org/10.1165/rcmb.2019-0079OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7193788PMC
May 2020

Tissue-Resident Alveolar Macrophages Do Not Rely on Glycolysis for LPS-induced Inflammation.

Am J Respir Cell Mol Biol 2020 02;62(2):243-255

Department of Medicine, Section of Pulmonary and Critical Care Medicine, The University of Chicago, Chicago, Illinois.

Macrophage effector function is dynamic in nature and largely dependent on not only the type of immunological challenge but also the tissue-specific environment and developmental origin of a given macrophage population. Recent research has highlighted the importance of glycolytic metabolism in the regulation of effector function as a common feature associated with macrophage activation. Yet, most research has used macrophage cell lines and bone marrow-derived macrophages, which do not account for the diversity of macrophage populations and the role of tissue specificity in macrophage immunometabolism. Tissue-resident alveolar macrophages (TR-AMs) reside in an environment characterized by remarkably low glucose concentrations, making glycolysis-linked immunometabolism an inefficient and unlikely means of immune activation. In this study, we show that TR-AMs rely on oxidative phosphorylation to meet their energy demands and maintain extremely low levels of glycolysis under steady-state conditions. Unlike bone marrow-derived macrophages, TR-AMs did not experience enhanced glycolysis in response to LPS, and glycolytic inhibition had no effect on their proinflammatory cytokine production. Hypoxia-inducible factor 1α stabilization promoted glycolysis in TR-AMs and shifted energy production away from oxidative metabolism at baseline, but it was not sufficient for TR-AMs to mount further increases in glycolysis or enhance immune function in response to LPS. Importantly, we confirmed these findings in an influenza model in which infiltrating macrophages had significantly higher glycolytic and proinflammatory gene expression than TR-AMs. These findings demonstrate that glycolysis is dispensable for macrophage effector function in TR-AM and highlight the importance of macrophage tissue origin (tissue resident vs. recruited) in immunometabolism.
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http://dx.doi.org/10.1165/rcmb.2019-0244OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6993551PMC
February 2020

Anti-fibrotic effects of tannic acid through regulation of a sustained TGF-beta receptor signaling.

Respir Res 2019 Jul 29;20(1):168. Epub 2019 Jul 29.

Department of Medicine, Section of Pulmonary and Critical Care Medicine, the University of Chicago, 5841 S. Maryland Ave, MC6076, Chicago, IL, 60637, USA.

Background: Pulmonary fibrosis is a progressive disease characterized by structural distortion of the lungs. Transforming growth factor-beta (TGF-beta) is a key cytokine implicated in the pathogenesis of pulmonary fibrosis. TGF-beta-induced myofibroblast differentiation characterized by expression of smooth muscle alpha-actin and extracellular matrix proteins is a key process in pathogenesis of fibrotic disease. Tannic acid is a natural polyphenol with diverse applications. In this study, we investigated the effect of tannic acid on myofibroblast differentiation and pulmonary fibrosis in cultured cells and in bleomycin model of the disease.

Methods: Primary cultured human lung fibroblasts (HLF) were used. The relative levels of proteins were determined by Western blotting. HLF contraction was measured by traction microscopy. Bleomycin-induced pulmonary fibrosis in mice was used as the disease model.

Results: Tannic acid inhibited TGF-beta-induced expression of collagen-1 and smooth muscle alpha-actin (SMA) as well as force generation by HLF. Tannic acid did not affect initial phosphorylation of Smad2 in response to TGF-beta, but significantly inhibited sustained Smad2 phosphorylation, which we recently described to be critical for TGF-beta-induced myofibroblast differentiation. Accordingly, tannic acid inhibited Smad-dependent gene transcription in response to TGF-beta, as assessed using luciferase reporter for the activity of Smad-binding elements. Finally, in mouse model of bleomycin-induced pulmonary fibrosis, therapeutic application of tannic acid resulted in a significant reduction of lung fibrosis, decrease in collagen-1 content and of Smad2 phosphorylation in the lungs.

Conclusions: This study demonstrates the anti-fibrotic effect of tannic acid in vitro and in vivo through a regulation of sustained Smad2 phosphorylation.
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http://dx.doi.org/10.1186/s12931-019-1141-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6664561PMC
July 2019

Air Pollution, Asthma, and Sleep Apnea: New Epidemiological Links?

Ann Am Thorac Soc 2019 Mar;16(3):307-308

2Department of Pulmonary Medicine, Koc University School of Medicine, Istanbul, Turkey.

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http://dx.doi.org/10.1513/AnnalsATS.201812-924EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7051530PMC
March 2019

Glutamine Metabolism Is Required for Collagen Protein Synthesis in Lung Fibroblasts.

Am J Respir Cell Mol Biol 2019 11;61(5):597-606

Section of Pulmonary and Critical Care Medicine, Department of Medicine, University of Chicago, Chicago, Illinois; and.

Idiopathic pulmonary fibrosis (IPF) is characterized by the transforming growth factor (TGF)-β-dependent differentiation of lung fibroblasts into myofibroblasts, leading to excessive deposition of extracellular matrix proteins, which distort lung architecture and function. Metabolic reprogramming in myofibroblasts is emerging as an important mechanism in the pathogenesis of IPF, and recent evidence suggests that glutamine metabolism is required in myofibroblasts, although the exact role of glutamine in myofibroblasts is unclear. In the present study, we demonstrate that glutamine and its conversion to glutamate by glutaminase are required for TGF-β-induced collagen protein production in lung fibroblasts. We found that metabolism of glutamate to α-ketoglutarate by glutamate dehydrogenase or the glutamate-pyruvate or glutamate-oxaloacetate transaminases is not required for collagen protein production. Instead, we discovered that the glutamate-consuming enzymes phosphoserine aminotransferase 1 (PSAT1) and aldehyde dehydrogenase 18A1 (ALDH18A1)/Δ-pyrroline-5-carboxylate synthetase (P5CS) are required for collagen protein production by lung fibroblasts. PSAT1 is required for glycine production, whereas ALDH18A1/P5CS is required for proline production. Consistent with this, we found that TGF-β treatment increased cellular concentrations of glycine and proline in lung fibroblasts. Our results suggest that glutamine metabolism is required to promote amino acid biosynthesis and not to provide intermediates such as α-ketoglutarate for oxidation in mitochondria. In support of this, we found that inhibition of glutaminolysis has no effect on cellular oxygen consumption and that knockdown of oxoglutarate dehydrogenase has no effect on the ability of fibroblasts to produce collagen protein. Our results suggest that amino acid biosynthesis pathways may represent novel therapeutic targets for treatment of fibrotic diseases, including IPF.
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http://dx.doi.org/10.1165/rcmb.2019-0008OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6827066PMC
November 2019

Update in Chronic Obstructive Pulmonary Disease 2018.

Am J Respir Crit Care Med 2019 06;199(12):1462-1470

3 Division of Pulmonary, Allergy, and Critical Care Medicine, The University of Alabama at Birmingham, Birmingham, Alabama.

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http://dx.doi.org/10.1164/rccm.201902-0374UPDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835078PMC
June 2019

A metabolic strategy to reverse fibrosis?

Nat Metab 2019 Jan;1(1):12-13

Department of Medicine, Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, IL, USA.

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http://dx.doi.org/10.1038/s42255-018-0013-8DOI Listing
January 2019

Single-Cell Transcriptomic Analysis of Human Lung Provides Insights into the Pathobiology of Pulmonary Fibrosis.

Am J Respir Crit Care Med 2019 06;199(12):1517-1536

4 Section of Pulmonary and Critical Care Medicine, University of Chicago, Chicago, Illinois; and.

The contributions of diverse cell populations in the human lung to pulmonary fibrosis pathogenesis are poorly understood. Single-cell RNA sequencing can reveal changes within individual cell populations during pulmonary fibrosis that are important for disease pathogenesis. To determine whether single-cell RNA sequencing can reveal disease-related heterogeneity within alveolar macrophages, epithelial cells, or other cell types in lung tissue from subjects with pulmonary fibrosis compared with control subjects. We performed single-cell RNA sequencing on lung tissue obtained from eight transplant donors and eight recipients with pulmonary fibrosis and on one bronchoscopic cryobiospy sample from a patient with idiopathic pulmonary fibrosis. We validated these data using RNA hybridization, immunohistochemistry, and bulk RNA-sequencing on flow-sorted cells from 22 additional subjects. We identified a distinct, novel population of profibrotic alveolar macrophages exclusively in patients with fibrosis. Within epithelial cells, the expression of genes involved in Wnt secretion and response was restricted to nonoverlapping cells. We identified rare cell populations including airway stem cells and senescent cells emerging during pulmonary fibrosis. We developed a web-based tool to explore these data. We generated a single-cell atlas of pulmonary fibrosis. Using this atlas, we demonstrated heterogeneity within alveolar macrophages and epithelial cells from subjects with pulmonary fibrosis. These results support the feasibility of discovery-based approaches using next-generation sequencing technologies to identify signaling pathways for targeting in the development of personalized therapies for patients with pulmonary fibrosis.
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http://dx.doi.org/10.1164/rccm.201712-2410OCDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6580683PMC
June 2019

Influenza A Virus Infection Induces Muscle Wasting via IL-6 Regulation of the E3 Ubiquitin Ligase Atrogin-1.

J Immunol 2019 01 7;202(2):484-493. Epub 2018 Dec 7.

Division of Pulmonary and Critical Care Medicine, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611;

Muscle dysfunction is common in patients with adult respiratory distress syndrome and is associated with morbidity that can persist for years after discharge. In a mouse model of severe influenza A pneumonia, we found the proinflammatory cytokine IL-6 was necessary for the development of muscle dysfunction. Treatment with a Food and Drug Administration-approved Ab antagonist to the IL-6R (tocilizumab) attenuated the severity of influenza A-induced muscle dysfunction. In cultured myotubes, IL-6 promoted muscle degradation via JAK/STAT, FOXO3a, and atrogin-1 upregulation. Consistent with these findings, and mice had attenuated muscle dysfunction following influenza infection. Our data suggest that inflammatory endocrine signals originating from the injured lung activate signaling pathways in the muscle that induce dysfunction. Inhibiting these pathways may limit morbidity in patients with influenza A pneumonia and adult respiratory distress syndrome.
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http://dx.doi.org/10.4049/jimmunol.1701433DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6324970PMC
January 2019

Particulate Matter Air Pollution: Effects on the Cardiovascular System.

Front Endocrinol (Lausanne) 2018 16;9:680. Epub 2018 Nov 16.

Section of Pulmonary and Critical Care Medicine, Department of Medicine, The University of Chicago, Chicago, IL, United States.

Air pollution is a complex mixture of gaseous and particulate components, each of which has detrimental effects on human health. While the composition of air pollution varies greatly depending on the source, studies from across the world have consistently shown that air pollution is an important modifiable risk factor for significantly increased morbidity and mortality. Moreover, clinical studies have generally shown a greater impact of particulate matter (PM) air pollution on health than the gaseous components. PM has wide-ranging deleterious effects on human health, particularly on the cardiovascular system. Both acute and chronic exposure to PM air pollution is associated with increased risk of death from cardiovascular diseases including ischemic heart disease, heart failure, and ischemic/thrombotic stroke. Particulate matter has also been shown to be an important endocrine disrupter, contributing to the development of metabolic diseases such as obesity and diabetes mellitus, which themselves are risk factors for cardiovascular disease. While the epidemiological evidence for the deleterious effects of PM air pollution on health is increasingly accepted, newer studies are shedding light on the mechanisms by which PM exerts its toxic effects. A greater understanding of how PM exerts toxic effects on human health is required in order to prevent and minimize the deleterious health effects of this ubiquitous environmental hazard. Air pollution is a growing public health problem and mortality due to air pollution is expected to double by 2050. Here, we review the epidemiological evidence for the cardiovascular effects of PM exposure and discuss current understanding about the biological mechanisms, by which PM exerts toxic effects on cardiovascular system to induce cardiovascular disease.
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http://dx.doi.org/10.3389/fendo.2018.00680DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6250783PMC
November 2018

Metformin Targets Mitochondrial Electron Transport to Reduce Air-Pollution-Induced Thrombosis.

Cell Metab 2019 02 11;29(2):335-347.e5. Epub 2018 Oct 11.

Department of Medicine and Pulmonary and Critical Care Medicine, Northwestern University, 240 E Huron Street, M300, Chicago, IL 60611, USA.

Urban particulate matter air pollution induces the release of pro-inflammatory cytokines including interleukin-6 (IL-6) from alveolar macrophages, resulting in an increase in thrombosis. Here, we report that metformin provides protection in this murine model. Treatment of mice with metformin or exposure of murine or human alveolar macrophages to metformin prevented the particulate matter-induced generation of complex III mitochondrial reactive oxygen species, which were necessary for the opening of calcium release-activated channels (CRAC) and release of IL-6. Targeted genetic deletion of electron transport or CRAC channels in alveolar macrophages in mice prevented particulate matter-induced acceleration of arterial thrombosis. These findings suggest metformin as a potential therapy to prevent some of the premature deaths attributable to air pollution exposure worldwide.
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http://dx.doi.org/10.1016/j.cmet.2018.09.019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6365216PMC
February 2019

Alveolar Epithelial Cells Burn Fat to Survive Acute Lung Injury.

Am J Respir Cell Mol Biol 2019 02;60(2):135-136

1 Section of Pulmonary and Critical Care Medicine University of Chicago Chicago, Illinois.

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http://dx.doi.org/10.1165/rcmb.2018-0300EDDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835041PMC
February 2019