Pulmonology
Abstract
BACKGROUND. Pulmonary arterial hypertension (PAH) is a deadly disease of the small pulmonary vasculature with an increased prevalence of insulin resistance (IR). Insulin regulates both glucose and lipid homeostasis. We sought to quantify glucose- and lipid-related IR in human PAH, testing the hypothesis that lipoprotein indices are more sensitive indices of IR in PAH. METHODS. Oral glucose tolerance testing in PAH patients and triglyceride-matched (TG-matched) controls and proteomic, metabolomics, and lipoprotein analyses were performed in PAH and controls. Results were validated in an external cohort and in explanted human PAH lungs. RESULTS. PAH patients were similarly glucose intolerant or IR by glucose homeostasis metrics compared with control patients when matched for the metabolic syndrome. Using the insulin-sensitive lipoprotein index, TG/HDL ratio, PAH patients were more commonly IR than controls. Proteomic and metabolomic analysis demonstrated separation between PAH and controls, driven by differences in lipid species. We observed a significant increase in long-chain acylcarnitines, phosphatidylcholines, insulin metabolism–related proteins, and in oxidized LDL receptor 1 (OLR1) in PAH plasma in both a discovery and validation cohort. PAH patients had higher lipoprotein axis–related IR and lipoprotein-based inflammation scores compared with controls. PAH patient lung tissue showed enhanced OLR1 immunostaining within plexiform lesions and oxidized LDL accumulation within macrophages. CONCLUSIONS. IR in PAH is characterized by alterations in lipid and lipoprotein homeostasis axes, manifest by elevated TG/HDL ratio, and elevated circulating medium- and long-chain acylcarnitines and lipoproteins. Oxidized LDL and its receptor OLR1 may play a role in a proinflammatory phenotype in PAH. FUNDING. NIH DK096994, HL060906, UL1 RR024975-01, UL1 TR000445-06, DK020593, P01 HL108800-01A1, and UL1 TR002243; American Heart Association 13FTF16070002.
Authors
Anna R. Hemnes, J. Matthew Luther, Christopher J. Rhodes, Jason P. Burgess, James Carlson, Run Fan, Joshua P. Fessel, Niki Fortune, Robert E. Gerszten, Stephen J. Halliday, Rezzan Hekmat, Luke Howard, John H. Newman, Kevin D. Niswender, Meredith E. Pugh, Ivan M. Robbins, Quanhu Sheng, Cyndya A. Shibao, Yu Shyr, Susan Sumner, Megha Talati, John Wharton, Martin R. Wilkins, Fei Ye, Chang Yu, James West, Evan L. Brittain
Abstract
Acute lung injury (ALI) is characterized by exuberant proinflammatory responses and mitochondrial dysfunction. However, the link between mitochondrial dysfunction and inflammation in ALI is not well understood. In this report, we demonstrate a critical role for the mitochondrial NAD+-dependent deacetylase, sirtuin-3 (SIRT3), in regulating macrophage mitochondrial bioenergetics, ROS formation, and proinflammatory responses. We found that SIRT3 expression was significantly diminished in lungs of mice subjected to LPS-induced ALI. SIRT3-deficient mice (SIRT3–/–) develop more severe ALI compared with wild-type controls (SIRT3+/+). Macrophages obtained from SIRT3–/– mice show significant alterations in mitochondrial bioenergetic and redox homeostasis, in association with a proinflammatory phenotype characterized by NLRP3 inflammasome activation. The SIRT3 activator viniferin restored macrophage bioenergetic function in LPS-treated macrophages. Viniferin also reduced NLRP3 activation and the production of proinflammatory cytokines, effects that were absent in SIRT3–/– macrophages. In-vivo administration of viniferin reduced production of inflammatory mediators TNF-α, MIP-2, IL-6, IL-1β, and HMGB1, and diminished neutrophil influx and severity of endotoxin-mediated ALI; this protective effect of vinferin was abolished in SIRT3–/– mice. Taken together, our results show that the induction/activation of SIRT3 may serve as a new therapeutic strategy in ALI by modulating cellular bioenergetics, controlling inflammatory responses, and reducing the severity of lung injury.
Authors
Deepali Kurundkar, Ashish R. Kurundkar, Nathaniel B. Bone, Eugene J. Becker Jr., Wanqu Liu, Balu Chacko, Victor Darley-Usmar, Jaroslaw W. Zmijewski, Victor J. Thannickal
Abstract
Mucus produced by submucosal glands is a key component of respiratory mucociliary transport (MCT). When it emerges from submucosal gland ducts, mucus forms long strands on the airway surface. However, the function of those strands is uncertain. To test the hypothesis that mucus strands facilitate transport of large particles, we studied newborn pigs. In ex vivo experiments, interconnected mucus strands moved over the airway surface, attached to immobile spheres, and initiated their movement by pulling them. Stimulating submucosal gland secretion with methacholine increased the percentage of spheres that moved and shortened the delay until mucus strands began moving spheres. To disrupt mucus strands, we applied reducing agents tris-(2-carboxyethyl)phosphine and dithiothreitol. They decreased the fraction of moving spheres and delayed initiation of movement for spheres that did move. We obtained similar in vivo results with CT-based tracking of microdisks in spontaneously breathing pigs. Methacholine increased the percentage of microdisks moving and reduced the delay until they were propelled up airways. Aerosolized tris-(2-carboxyethyl)phosphine prevented those effects. Once particles started moving, reducing agents did not alter their speed either ex vivo or in vivo. These findings indicate that submucosal glands produce mucus in the form of strands and that the strands initiate movement of large particles, facilitating their removal from airways.
Authors
Anthony J. Fischer, Maria I. Pino-Argumedo, Brieanna M. Hilkin, Cullen R. Shanrock, Nicholas D. Gansemer, Anna L. Chaly, Keyan Zarei, Patrick D. Allen, Lynda S. Ostedgaard, Eric A. Hoffman, David A. Stoltz, Michael J. Welsh, Mahmoud H. Abou Alaiwa
Abstract
Ricin toxin (RT) ranks at the top of the list of bioweapons of concern to civilian and military personnel alike, due to its high potential for morbidity and mortality after inhalation. In nonhuman primates, aerosolized ricin triggers severe acute respiratory distress characterized by perivascular and alveolar edema, neutrophilic infiltration, and severe necrotizing bronchiolitis and alveolitis. There are currently no approved countermeasures for ricin intoxication. Here, we report the therapeutic potential of a humanized mAb against an immunodominant epitope on ricin’s enzymatic A chain (RTA). Rhesus macaques that received i.v. huPB10 4 hours after a lethal dose of ricin aerosol exposure survived toxin challenge, whereas control animals succumbed to ricin intoxication within 30 hours. Antibody intervention at 12 hours resulted in the survival of 1 of 5 monkeys. Changes in proinflammatory cytokine, chemokine, and growth factor profiles in bronchial alveolar lavage fluids before and after toxin challenge successfully clustered animals by treatment group and survival, indicating a relationship between local tissue damage and experimental outcome. This study represents the first demonstration, to our knowledge, in nonhuman primates that the lethal effects of inhalational ricin exposure can be negated by a drug candidate, and it opens up a path forward for product development.
Authors
Chad J. Roy, Dylan J. Ehrbar, Natasha Bohorova, Ognian Bohorov, Do Kim, Michael Pauly, Kevin Whaley, Yinghui Rong, Fernando J. Torres-Velez, Ellen S. Vitetta, Peter J. Didier, Lara Doyle-Meyers, Larry Zeitlin, Nicholas J. Mantis
Abstract
Obesity hypoventilation syndrome (OHS) is a serious disorder characterized by daytime hypercapnia, disordered breathing, and a reduction in chemosensitivity. Vertical sleeve gastrectomy (VSG), a bariatric surgical procedure resulting in weight loss and weight-independent improvements in glucose metabolism, has been observed to substantially improve sleep-disordered breathing. However, it is unclear if the ventilatory effects of VSG are secondary to weight loss or the marked change in metabolic physiology. Using preclinical mouse models, we found that VSG leads to an improvement in the hypercapnic ventilatory response (HCVR) and reductions in circulating leptin levels independent of reductions in body mass, fat mass, and caloric intake. In the absence of leptin, VSG continues to improve body mass, fat mass, and glucose tolerance in ob/ob mice but no longer affects HCVR. However, the HCVR of ob/ob mice can be returned to wild-type levels with leptin treatment. These data demonstrate that VSG improves chemosensitivity and ventilatory drive via a leptin-dependent mechanism. Clinically, these data downgrade the relative contribution of physical, mechanical load in the pathogenesis of OHS, and instead point to physiological components of obesity, including alterations in leptin signaling, as key drivers in OHS.
Authors
Deanna M. Arble, Alan R. Schwartz, Vsevolod Y. Polotsky, Darleen A. Sandoval, Randy J. Seeley
Abstract
The extracellular matrix (ECM) in idiopathic pulmonary fibrosis (IPF) drives fibrosis progression; however, the ECM composition of the fibroblastic focus (the hallmark lesion in IPF) and adjacent regions remains incompletely defined. Herein, we serially sectioned IPF lung specimens constructed into tissue microarrays and immunostained for ECM components reported to be deregulated in IPF. Immunostained sections were imaged, anatomically aligned, and 3D reconstructed. The myofibroblast core of the fibroblastic focus (defined by collagen I, α-smooth muscle actin, and procollagen I immunoreactivity) was associated with collagens III, IV, V, and VI; fibronectin; hyaluronan; and versican immunoreactivity. Hyaluronan immunoreactivity was also present at the fibroblastic focus perimeter and at sites where early lesions appear to be forming. Fibrinogen immunoreactivity was often observed at regions of damaged epithelium lining the airspace and the perimeter of the myofibroblast core but was absent from the myofibroblast core itself. The ECM components of the fibroblastic focus were distributed in a characteristic and reproducible manner in multiple patients. This information can inform the development of high-fidelity model systems to dissect mechanisms by which the IPF ECM drives fibrosis progression.
Authors
Jeremy Herrera, Colleen Forster, Thomas Pengo, Angeles Montero, Joe Swift, Martin A. Schwartz, Craig A. Henke, Peter B. Bitterman
Abstract
Pulmonary fibrosis (PF) is an intractable disorder with a poor prognosis. Although lung fibroblasts play a central role in PF, the key regulatory molecules involved in this process remain unknown. To address this issue, we performed a time-course transcriptome analysis on lung fibroblasts of bleomycin- and silica-treated murine lungs. We found gene modules whose expression kinetics were associated with the progression of PF and human idiopathic PF (IPF). Upstream analysis of a transcriptome network helped in identifying 55 hub transcription factors that were highly connected with PF-associated gene modules. Of these hubs, the expression of Srebf1 decreased in line with progression of PF and human IPF, suggesting its suppressive role in fibroblast activation. Consistently, adoptive transfer and genetic modification studies revealed that the hub transcription factor SREBP-1c suppressed PF-associated gene expression changes in lung fibroblasts and PF pathology in vivo. Moreover, therapeutic pharmacological activation of LXR, an SREBP-1c activator, suppressed the Srebf1-dependent activation of fibroblasts and progression of PF. Thus, SREBP-1c acts as a protective hub of lung fibroblast activation in PF. Collectively, the findings of the current study may prove to be valuable in the development of effective therapeutic strategies for PF.
Authors
Shigeyuki Shichino, Satoshi Ueha, Shinichi Hashimoto, Mikiya Otsuji, Jun Abe, Tatsuya Tsukui, Shungo Deshimaru, Takuya Nakajima, Mizuha Kosugi-Kanaya, Francis H.W. Shand, Yutaka Inagaki, Hitoshi Shimano, Kouji Matsushima
Abstract
Matrix metalloproteinase-9 (MMP-9) cleaves various proteins to regulate inflammatory and injury responses. However, MMP-9’s activities during influenza A viral (IAV) infections are incompletely understood. Herein, plasma MMP-9 levels were increased in patients with pandemic H1N1 and seasonal IAV infections. MMP-9 lung levels were increased and localized to airway epithelial cells and leukocytes in H1N1-infected WT murine lungs. H1N1-infected Mmp-9–/– mice had lower mortality rates, reduced weight loss, lower lung viral titers, and reduced lung injury, along with lower E-cadherin shedding in bronchoalveolar lavage fluid (BALF) samples than WT mice. H1N1-infected Mmp-9–/– mice had an altered immune response to IAV with lower BALF PMN and macrophage counts, higher Th1-like CD4+ and CD8+ T cell subsets, lower T regulatory cell counts, reduced lung type I interferon levels, and higher lung interferon-γ levels. Mmp-9 bone marrow–chimera studies revealed that Mmp-9 deficiency in lung parenchymal cells protected mice from IAV-induced mortality. H1N1-infected Mmp-9–/– lung epithelial cells had lower viral titers than H1N1-infected WT cells in vitro. Thus, H1N1-infected Mmp-9–/– mice are protected from IAV-induced lung disease due to a more effective adaptive immune response to IAV and reduced epithelial barrier injury due partly to reduced E-cadherin shedding. Thus, we believe that MMP-9 is a novel therapeutic target for IAV infections.
Authors
Joselyn Rojas-Quintero, Xiaoyun Wang, Jennifer Tipper, Patrick R. Burkett, Joaquin Zuñiga, Amit R. Ashtekar, Francesca Polverino, Amit Rout, Ilyas Yambayev, Carmen Hernández, Luis Jimenez, Gustavo Ramírez, Kevin S. Harrod, Caroline A. Owen
Abstract
Although responses to EGFR tyrosine kinase inhibitors (EGFR-TKIs) are initially positive, 30%–40% of patients with EGFR-mutant tumors do not respond well to EGFR-TKIs, and most lung cancer patients harboring EGFR mutations experience relapse with resistance. Therefore, it is necessary to identify not only the mechanisms underlying EGFR-TKI resistance, but also potentially novel therapeutic targets and/or predictive biomarkers for EGFR-mutant lung adenocarcinoma. We found that the GPI-anchored protein semaphorin 7A (SEMA7A) is highly induced by the EGFR pathway, via mTOR signaling, and that expression levels of SEMA7A in human lung adenocarcinoma specimens were correlated with mTOR activation. Investigations using cell culture and animal models demonstrated that loss or overexpression of SEMA7A made cells less or more resistant to EGFR-TKIs, respectively. The resistance was due to the inhibition of apoptosis by aberrant activation of ERK. The ERK signal was suppressed by knockdown of integrin β1 (ITGB1). Furthermore, in patients with EGFR mutant tumors, higher SEMA7A expression in clinical samples predicted poorer response to EGFR-TKI treatment. Collectively, these data show that the SEMA7A–ITGB1 axis plays pivotal roles in EGFR-TKI resistance mediated by ERK activation and apoptosis inhibition. Moreover, our results reveal the potential utility of SEMA7A not only as a predictive biomarker, but also as a potentially novel therapeutic target in EGFR-mutant lung adenocarcinoma.
Authors
Yuhei Kinehara, Izumi Nagatomo, Shohei Koyama, Daisuke Ito, Satoshi Nojima, Ryota Kurebayashi, Yoshimitsu Nakanishi, Yasuhiko Suga, Yu Nishijima-Futami, Akio Osa, Takeshi Nakatani, Yasuhiro Kato, Masayuki Nishide, Yoshitomo Hayama, Masayoshi Higashiguchi, Osamu Morimura, Kotaro Miyake, Sujin Kang, Toshiyuki Minami, Haruhiko Hirata, Kota Iwahori, Takayuki Takimoto, Hyota Takamatsu, Yoshito Takeda, Naoki Hosen, Shigenori Hoshino, Yasushi Shintani, Meinoshin Okumura, Toru Kumagai, Kazumi Nishino, Fumio Imamura, Shin-ichi Nakatsuka, Takashi Kijima, Hiroshi Kida, Atsushi Kumanogoh
Abstract
BACKGROUND. The ability to restore cystic fibrosis transmembrane regulator (CFTR) function with effective small molecule modulators in patients with cystic fibrosis provides an opportunity to study relationships between CFTR ion channel function, organ level physiology, and clinical outcomes. METHODS. We performed a multisite, prospective, observational study of ivacaftor, prescribed in patients with the G551D-CFTR mutation. Measurements of lung mucociliary clearance (MCC) were performed before and after treatment initiation (1 and 3 months), in parallel with clinical outcome measures. RESULTS. Marked acceleration in whole lung, central lung, and peripheral lung MCC was observed 1 month after beginning ivacaftor and was sustained at 3 months. Improvements in MCC correlated with improvements in forced expiratory volume in the first second (FEV1) but not sweat chloride or symptom scores. CONCLUSIONS. Restoration of CFTR activity with ivacaftor led to significant improvements in MCC. This physiologic assessment provides a means to characterize future CFTR modulator therapies and may help to predict improvements in lung function. TRIAL REGISTRATION. ClinicialTrials.gov, NCT01521338. FUNDING. CFF Therapeutics (GOAL11K1).
Authors
Scott H. Donaldson, Beth L. Laube, Timothy E. Corcoran, Pradeep Bhambhvani, Kirby Zeman, Agathe Ceppe, Pamela L. Zeitlin, Peter J. Mogayzel Jr., Michael Boyle, Landon W. Locke, Michael M. Myerburg, Joseph M. Pilewski, Brian Flanagan, Steven M. Rowe, William D. Bennett
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