1
|
Ganouna-Cohen G, Khadangi F, Marcouiller F, Bossé Y, Joseph V. Additive effects of orchiectomy and intermittent hypoxia on lung mechanics and inflammation in C57BL/6J male mice. Exp Physiol 2021; 107:68-81. [PMID: 34761830 DOI: 10.1113/ep090050] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Accepted: 11/05/2021] [Indexed: 01/01/2023]
Abstract
NEW FINDINGS What is the central question of this study? Does endogenous testosterone modulate the consequences of intermittent hypoxia (IH) in the lungs of male mice? What is the main finding and its importance? Orchiectomized mice exposed to IH develop a pattern that is similar to emphysema or obstructive lung disease with elevated lung volumes, low pulmonary elastance during a methacholine challenge test and high counts of lymphocytes in bronchoalveolar lavages. Since low testosterone levels and other respiratory diseases are common in sleep apnoea, there is a clear clinical relevance to these results. ABSTRACT We tested the hypothesis that low testosterone levels modulate the pulmonary responses to intermittent hypoxia (IH; used as a model of sleep apnoea (SA)) in male mice. We used intact (SHAM) or orchiectomized (ORX) mice exposed to IH for 14 days (12 h/day, 10 cycles/h, 6% oxygen) or to normoxia (Nx). We first measured ventilation and metabolic rates in freely behaving mice (whole-body plethysmography) and then respiratory mechanics in tracheotomized mice (flexiVent). We assessed the respiratory system resistance and elastance (Ers ), Newtonian resistance (resistance of the large airways), tissue damping and tissue elastance (H) under baseline conditions and during a methacholine challenge test. We also measured the quasi-static compliance and inspiratory capacity with partial pressure-volume loops. Finally, inflammatory cells were counted in the broncho-alveolar lavage (BAL) and we measured lung volume by water displacement. ORX-IH mice had higher tidal volume, inspiratory capacity and lung volume compared to the other groups, but showed signs of low efficiency of O2 exchange rate relative to minute ventilation. During the methacholine challenge, orchiectomy decreased the values of most mechanical parameters and IH reduced Ers and H leading to very low values in ORX-IH mice. Finally, the total number of cells and the number of lymphocytes in BAL were both increased by IH in ORX mice. Since reduced lung elasticity, low O2 extraction, increased lung volumes and inflammation are signs of emphysematous lung disease, we conclude that testosterone might prevent lung emphysema during IH exposures.
Collapse
Affiliation(s)
- Gauthier Ganouna-Cohen
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie du Québec, Université Laval, Québec, QC, Canada
| | - Fatemeh Khadangi
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie du Québec, Université Laval, Québec, QC, Canada
| | - François Marcouiller
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie du Québec, Université Laval, Québec, QC, Canada
| | - Ynuk Bossé
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie du Québec, Université Laval, Québec, QC, Canada
| | - Vincent Joseph
- Centre de Recherche de l'Institut Universitaire de Cardiologie et de Pneumologie du Québec, Université Laval, Québec, QC, Canada
| |
Collapse
|
2
|
Wu G, Lee YY, Gulla EM, Potter A, Kitzmiller J, Ruben MD, Salomonis N, Whitsett JA, Francey LJ, Hogenesch JB, Smith DF. Short-term exposure to intermittent hypoxia leads to changes in gene expression seen in chronic pulmonary disease. eLife 2021; 10:63003. [PMID: 33599610 PMCID: PMC7909952 DOI: 10.7554/elife.63003] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 02/17/2021] [Indexed: 12/16/2022] Open
Abstract
Obstructive sleep apnea (OSA) results from episodes of airway collapse and intermittent hypoxia (IH) and is associated with a host of health complications. Although the lung is the first organ to sense changes in oxygen levels, little is known about the consequences of IH to the lung hypoxia-inducible factor-responsive pathways. We hypothesized that exposure to IH would lead to cell-specific up- and downregulation of diverse expression pathways. We identified changes in circadian and immune pathways in lungs from mice exposed to IH. Among all cell types, endothelial cells showed the most prominent transcriptional changes. Upregulated genes in myofibroblast cells were enriched for genes associated with pulmonary hypertension and included targets of several drugs currently used to treat chronic pulmonary diseases. A better understanding of the pathophysiologic mechanisms underlying diseases associated with OSA could improve our therapeutic approaches, directing therapies to the most relevant cells and molecular pathways.
Collapse
Affiliation(s)
- Gang Wu
- Divisions of Human Genetics and Immunobiology, Center for Circadian Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Yin Yeng Lee
- Divisions of Human Genetics and Immunobiology, Center for Circadian Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States.,Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, United States
| | - Evelyn M Gulla
- Division of Pediatric Otolaryngology - Head and Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Andrew Potter
- Division of Developmental Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Joseph Kitzmiller
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Marc D Ruben
- Divisions of Human Genetics and Immunobiology, Center for Circadian Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Nathan Salomonis
- Department of Pharmacology and Systems Physiology, University of Cincinnati College of Medicine, Cincinnati, United States.,Division of Biomedical Informatics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Jeffery A Whitsett
- Division of Pulmonary Biology, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - Lauren J Francey
- Divisions of Human Genetics and Immunobiology, Center for Circadian Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - John B Hogenesch
- Divisions of Human Genetics and Immunobiology, Center for Circadian Medicine, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, United States
| | - David F Smith
- Division of Pediatric Otolaryngology - Head and Neck Surgery, Cincinnati Children's Hospital Medical Center, Cincinnati, United States.,Division of Pulmonary Medicine and the Sleep Center, Cincinnati Children's Hospital Medical Center, Cincinnati, United States.,The Center for Circadian Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, United States.,Department of Otolaryngology-Head and Neck Surgery, University of Cincinnati College of Medicine, Cincinnati, United States
| |
Collapse
|
3
|
Kang HH, Kim IK, Yeo CD, Kim SW, Lee HY, Im JH, Kwon HY, Lee SH. The Effects of Chronic Intermittent Hypoxia in Bleomycin-Induced Lung Injury on Pulmonary Fibrosis via Regulating the NF-κB/Nrf2 Signaling Pathway. Tuberc Respir Dis (Seoul) 2020; 83:S63-S74. [PMID: 33027868 PMCID: PMC7837382 DOI: 10.4046/trd.2020.0112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Accepted: 10/08/2020] [Indexed: 12/15/2022] Open
Abstract
Background Obstructive sleep apnea (OSA) is associated with pulmonary fibrosis. Chronic intermittent hypoxia (CIH) is considered to be a surrogate of OSA. However, its exact role in pulmonary fibrosis remains uncertain. Therefore, we investigated the mechanism underlying CIH-induced pulmonary fibrosis and the role of the anti-fibrotic agent in bleomycin (BLE) induced lung injury. Methods Mice were divided into eight groups: the normoxia (NOR), CIH, NOR plus BLE, CIH plus BLE, NOR plus pirfenidone (PF), CIH plus PF, NOR plus BLE and PF, and CIH plus BLE and PF groups. BLE was administered intratracheally on day 14 following CIH or NOR exposure. Subsequently, the mice were exposed to CIH or NOR for an additional 4 weeks. PF was administered orally on day 5 after BLE instillation once daily for 3 weeks. Results In the BLE-treated groups, CIH-induced more collagen deposition in lung tissues than NOR, and significantly increased hydroxyproline and transforming growth factor-β expression. The CIH and BLE-treated groups showed increased lung inflammation compared to NOR or CIH groups. Following CIH with BLE treatment, nuclear factor-κB (NF-κB) protein expression was significantly increased, whereas nuclear factor-erythroid-related factor 2 (Nrf2) and heme oxygenase-1 protein levels were decreased. After PF treatment, NF-κB and Kelch-like ECH-associated protein 1 expression were suppressed, and Nrf2 expression was increased. Conclusion CIH accelerated lung fibrosis in BLE-induced lung injury in mice, potentially by regulating the NF-κB/Nrf2 signaling pathway. Our results implicate PF as a potential therapeutic agent for treating pulmonary fibrosis in individuals with OSA and idiopathic pulmonary fibrosis.
Collapse
Affiliation(s)
- Hyeon Hui Kang
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Ulsan University Hospital, University of Ulsan College of Medicine, Ulsan, Korea
| | - In Kyoung Kim
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Cancer Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Chang Dong Yeo
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sei Won Kim
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hea Yon Lee
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Jeong Hyeon Im
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hee Young Kwon
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sang Haak Lee
- Division of Pulmonary, Critical Care and Sleep Medicine, Department of Internal Medicine, Eunpyeong St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Cancer Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea
| |
Collapse
|
4
|
Kuma YI, Hosomichi J, Maeda H, Oishi S, Usumi-Fujita R, Shimizu Y, Kaneko S, Suzuki JI, Yoshida KI, Ono T. Intermittent hypoxia induces turbinate mucosal hypertrophy via upregulating the gene expression related to inflammation and EMT in rats. Sleep Breath 2020; 25:677-684. [PMID: 32766939 DOI: 10.1007/s11325-020-02162-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 07/02/2020] [Accepted: 08/01/2020] [Indexed: 12/12/2022]
Abstract
PURPOSE Chronic intermittent hypoxia (IH) plays a pivotal role in the consequences of obstructive sleep apnea (OSA). It has been demonstrated that IH impairs nasomaxillary complex growth to reduce nasal airway cavity size in rodent models. Although turbinate dysfunction with inflammatory mucosal hypertrophy is related to OSA, the role of IH in turbinate hypertrophy with inflammation-driven fibrosis is unknown. Here, we aimed to clarify the pathogenesis of inflammatory mucosal hypertrophy and epithelial-mesenchymal transition (EMT) in the nasal turbinate under IH. METHODS Seven-week-old male Sprague-Dawley rats were exposed to IH (4% O2 to 21% O2 with 0% CO2) at a rate of 20 cycles/h. RESULTS Hypertrophy of the turbinate mucosa occurred after 3 weeks, with the turbinate mucosa of the experimental group becoming significantly thicker than in the control group. Immunostaining showed that IH increased the expression of TGFβ and N-cadherin and decreased E-cadherin expression in the turbinate mucosa. Quantitative PCR analysis demonstrated that IH enhanced the expression of not only the inflammatory markers Tnf-a, Il-1b, and Nos2 but also the EMT markers Tgf-b1, Col1a1, and Postn. CONCLUSIONS Collectively, these results suggest that IH induced turbinate hypertrophy via upregulation of gene expression related to inflammation and EMT in the nasal mucosa.
Collapse
Affiliation(s)
- Yo-Ichiro Kuma
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| | - Jun Hosomichi
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan.
| | - Hideyuki Maeda
- Department of Forensic Medicine, Graduate School of Medicine, Tokyo Medical University, Tokyo, 160-8402, Japan
| | - Shuji Oishi
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| | - Risa Usumi-Fujita
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| | - Yasuhiro Shimizu
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| | - Sawa Kaneko
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| | - Jun-Ichi Suzuki
- Department of Advanced Clinical Science and Therapeutics, Graduate School of Medicine, The University of Tokyo, Tokyo, 113-8655, Japan
| | - Ken-Ichi Yoshida
- Department of Forensic Medicine, Graduate School of Medicine, Tokyo Medical University, Tokyo, 160-8402, Japan
| | - Takashi Ono
- Department of Orthodontic Science, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, 113-8549, Japan
| |
Collapse
|
5
|
Krishnan S, Stearman RS, Zeng L, Fisher A, Mickler EA, Rodriguez BH, Simpson ER, Cook T, Slaven JE, Ivan M, Geraci MW, Lahm T, Tepper RS. Transcriptomic modifications in developmental cardiopulmonary adaptations to chronic hypoxia using a murine model of simulated high-altitude exposure. Am J Physiol Lung Cell Mol Physiol 2020; 319:L456-L470. [PMID: 32639867 DOI: 10.1152/ajplung.00487.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mechanisms driving adaptive developmental responses to chronic high-altitude (HA) exposure are incompletely known. We developed a novel rat model mimicking the human condition of cardiopulmonary adaptation to HA starting at conception and spanning the in utero and postnatal timeframe. We assessed lung growth and cardiopulmonary structure and function and performed transcriptome analyses to identify mechanisms facilitating developmental adaptations to chronic hypoxia. To generate the model, breeding pairs of Sprague-Dawley rats were exposed to hypobaric hypoxia (equivalent to 9,000 ft elevation). Mating, pregnancy, and delivery occurred in hypoxic conditions. Six weeks postpartum, structural and functional data were collected in the offspring. RNA-Seq was performed on right ventricle (RV) and lung tissue. Age-matched breeding pairs and offspring under room air (RA) conditions served as controls. Hypoxic rats exhibited significantly lower body weights and higher hematocrit levels, alveolar volumes, pulmonary diffusion capacities, RV mass, and RV systolic pressure, as well as increased pulmonary artery remodeling. RNA-Seq analyses revealed multiple differentially expressed genes in lungs and RVs from hypoxic rats. Although there was considerable similarity between hypoxic lungs and RVs compared with RA controls, several upstream regulators unique to lung or RV were identified. We noted a pattern of immune downregulation and regulation patterns of immune and hormonal mediators similar to the genome from patients with pulmonary arterial hypertension. In summary, we developed a novel murine model of chronic hypoxia exposure that demonstrates functional and structural phenotypes similar to human adaptation. We identified transcriptomic alterations that suggest potential mechanisms for adaptation to chronic HA.
Collapse
Affiliation(s)
- Sheila Krishnan
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Robert S Stearman
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Lily Zeng
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Amanda Fisher
- Department of Anesthesiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Elizabeth A Mickler
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Brooke H Rodriguez
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Edward R Simpson
- Department of BioHealth Informatics, School of Informatics and Computing, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana.,Center for Computational Biology and Bioinformatics, Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Todd Cook
- Indiana Center for Vascular Biology and Medicine, Indianapolis, Indiana
| | - James E Slaven
- Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Medicine, Division of Hematology and Oncology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Mircea Ivan
- Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana
| | - Mark W Geraci
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Tim Lahm
- Department of Medicine, Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Indiana University School of Medicine, Indianapolis, Indiana.,Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, Indiana.,Richard L. Roudebush Veterans Affairs Medical Center, Indianapolis, Indiana
| | - Robert S Tepper
- Department of Pediatrics, Indiana University School of Medicine, Indianapolis, Indiana
| |
Collapse
|
6
|
Shi Z, Xu L, Xie H, Ouyang R, Ke Y, Zhou R, Yung WH. Attenuation of intermittent hypoxia-induced apoptosis and fibrosis in pulmonary tissues via suppression of ER stress activation. BMC Pulm Med 2020; 20:92. [PMID: 32299413 PMCID: PMC7161195 DOI: 10.1186/s12890-020-1123-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2019] [Accepted: 03/25/2020] [Indexed: 12/21/2022] Open
Abstract
Background Obstructive sleep apnea (OSA) is associated with pulmonary fibrosis and endothelial apoptosis in pulmonary tissues. Chronic intermittent hypoxia (IH) is considered to be the primary player in OSA, but the mechanisms underlying its effect on pulmonary tissues are unknown. Endoplasmic reticulum (ER) stress induced by IH treatment plays an important role in accelerating the process of fibrosis and induction of apoptosis. Methods Mice were placed in IH chambers for 4 weeks with an oscillating oxygen (O2) concentration between 5 and 21%, cycling every 90s for 8 h daily. Mice were randomly divided into four groups: control group (normal oxygen), tauroursodeoxycholic acid (TUDCA) group (normal oxygen intraperitoneally injected with TUDCA), IH group and IH + TUDCA group. After 4 weeks, the proteins in three branch signaling pathways of ER stress, including protein kinase RNA (PKR)-like/Pancreatic ER kinase (PERK), activating transcription factor 6 (ATF-6) and inositol-requiring enzyme 1 (IRE-1), were evaluated. The cleaved caspase-3, caspase-12 and TUNNEL staining was assessed. Furthermore, the expression of transforming growth factor-β1 (TGF-β1) and thrombospondin-1(TSP-1), two extracellular matrix proteins that play critical role in fibrosis, were examined. Finally, Masson’s trichrome staining was performed to detect the expression of collagen. Results After 4 weeks of IH treatment, the expressions of two ER stress markers, glucose regulated protein-78 (Grp78) and transcription factor C/EBP homologous protein (CHOP) were increased which was prevented by administration of the ER stress attenuator, TUDCA. The expressions of PERK, but not those of ATF-6 and IRE-1, were increased. The effects of IH were accompanied by an increased number of apoptotic cells and increased expressions of cleaved caspase-3 and caspase-12 in pulmonary tissues. In addition, histological examination suggested the presence of fibrosis after chronic IH treatment, indicated by increased expression of collagen, which was associated with the up-regulation of TGF-β1 and TSP-1 that are known to promote fibrosis. Similarly, TUDCA could reduce the extent of fibrotic area and the expression levels of these proteins. Conclusions It reveals the roles of ER stress, especially the PERK pathway, in IH induced apoptosis and fibrosis in pulmonary tissues that might underlie the pulmonary complications observed in OSA.
Collapse
Affiliation(s)
- Zhihui Shi
- Department of Respiratory and Critical Care Medicine, The Second Xiangya Hospital, Central-South University, Changsha, China.,Research Unit of Respiratory Disease, Central-South University, Changsha, China.,School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China
| | - Linhao Xu
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China.,Department of Cardiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Hui Xie
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China
| | - Ruoyun Ouyang
- Department of Respiratory and Critical Care Medicine, The Second Xiangya Hospital, Central-South University, Changsha, China.,Research Unit of Respiratory Disease, Central-South University, Changsha, China
| | - Ya Ke
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China
| | - Rui Zhou
- Department of Respiratory and Critical Care Medicine, The Second Xiangya Hospital, Central-South University, Changsha, China. .,Research Unit of Respiratory Disease, Central-South University, Changsha, China.
| | - Wing-Ho Yung
- School of Biomedical Sciences, Faculty of Medicine, The Chinese University of Hong Kong, Shatin, Hong Kong, SAR, China.
| |
Collapse
|
7
|
Dane DM, Cao K, Lu H, Yilmaz C, Dolan J, Thaler CD, Ravikumar P, Hammond KA, Hsia CCW. Acclimatization of low altitude-bred deer mice ( Peromyscus maniculatus) to high altitude. J Appl Physiol (1985) 2018; 125:1411-1423. [PMID: 30091664 DOI: 10.1152/japplphysiol.01036.2017] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
A colony of deer mice subspecies ( Peromyscus maniculatus sonoriensis) native to high altitude (HA) has been maintained at sea level for 18-20 generations and remains genetically unchanged. To determine if these animals retain responsiveness to hypoxia, one group (9-11 wk old) was acclimated to HA (3,800 m) for 8 wk. Age-matched control animals were acclimated to a lower altitude (LA; 252 m). Maximal O2 uptake (V̇o2max) was measured at the respective altitudes. On a separate day, lung volume, diffusing capacity for carbon monoxide (DLCO), and pulmonary blood flow were measured under anesthesia using a rebreathing technique at two inspired O2 tensions. The HA-acclimated deer mice maintained a normal V̇o2max relative to LA baseline. Compared with LA control mice, antemortem lung volume was larger in HA mice in a manner dependent on alveolar O2 tension. Systemic hematocrit, pulmonary blood flow, and standardized DLCO did not differ significantly between groups. HA mice showed a higher postmortem alveolar-capillary hematocrit, larger alveolar ducts, and smaller distal conducting structures. In HA mice, absolute volumes of alveolar type I epithelia and endothelia were higher whereas that of interstitia was lower than in LA mice. These structural changes occurred without a net increase in whole-lung septal tissue-capillary volumes or surface areas. Thus, deer mice bred and raised to adulthood at LA retain phenotypic plasticity and adapt to HA without a decrement in V̇o2max via structural (enlarged airspaces, alveolar septal remodeling) and nonstructural (lung expansion under hypoxia) mechanisms and without an increase in systemic hematocrit or compensatory lung growth. NEW & NOTEWORTHY Deer mice ( Peromyscus maniculatus) are robust and very active mammals that are found across the North American continent. They are also highly adaptable to extreme environments. When introduced to high altitude they retain remarkable adaptive ability to the low-oxygen environment via lung expansion and remodeling of existing lung structure, thereby maintaining normal aerobic capacity without generating more red blood cells or additional lung tissue.
Collapse
Affiliation(s)
- D Merrill Dane
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Khoa Cao
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Hua Lu
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Cuneyt Yilmaz
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Jamie Dolan
- Department of Evolution, Ecology and Organismal Biology, University of California at Riverside , Riverside, California
| | - Catherine D Thaler
- Department of Evolution, Ecology and Organismal Biology, University of California at Riverside , Riverside, California
| | - Priya Ravikumar
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Kimberly A Hammond
- Department of Evolution, Ecology and Organismal Biology, University of California at Riverside , Riverside, California
| | - Connie C W Hsia
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas
| |
Collapse
|
8
|
Intermittent Hypoxia and Unsaturated Aldehydes: Effects on Oral Epithelial Wound Healing. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 1023:47-54. [PMID: 28681187 DOI: 10.1007/5584_2017_68] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/09/2022]
Abstract
Obstructive sleep apnea (OSA) is a highly prevalent sleep breathing disorder characterized by intermittent hypoxia (IH), leading to blood hypoxemia, hypercapnia, and sleep fragmentation. Studies on the effects of OSA on oral epithelial tissue healing are limited. Smoking is considered a risk factor for OSA through the exposure to chemically active toxins, present in the smoke. Acrolein is the most chemically active unsaturated aldehyde, impairing a variety of biological processes. The aim of this study was to determine the effect of IH on oral epithelial tissue healing, with and without acrolein. HaCaT cells were wounded by a cross-scratch made in the cell cultures, considered as time zero. Then, cells were exposed to 28 IH cycles (5-20% oxygen) during 12 h using the BioSpherix OxyCycler-C42 system. Control cells were maintained in normoxic conditions or in sustained hypoxia (SH) (5% oxygen) for the same durations, after which all cells were maintained for additional 12 h in normoxia. The migrating abilities of cells were measured after 24 h by calculating the percent of the residual cross-scratch area. In parallel experiments, 25 μM acrolein were added to each treatment. We found that the scratch closure was the slowest under IH. After 24 h, the residual scratch area in the IH treated cells was 29.5 ± 13.4% of the initial area, while in normoxia and SH it was 9.2 ± 5.8% and 10.3 ± 11.3%, respectively (p < 0.01 for both vs. IH). Adding acrolein further attenuated the migratory ability in IH as compared to normoxia and SH. We conclude that IH delays the healing process of oral epithelial tissue by slowing the cells' migratory abilities. The healing might be further attenuated by chemically active unsaturated aldehydes such as acrolein.
Collapse
|
9
|
Intermittent Hypoxia Contributes to the Lung Damage by Increased Oxidative Stress, Inflammation, and Disbalance in Protease/Antiprotease System. Lung 2016; 194:1015-1020. [PMID: 27738828 DOI: 10.1007/s00408-016-9946-4] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Accepted: 09/18/2016] [Indexed: 12/16/2022]
Abstract
INTRODUCTION Intermittent hypoxia as a surrogate of obstructive sleep apnea is associated with different cardiovascular complications. However, the effects of intermittent hypoxia on the lung tissue are less known. Therefore, the aim of our present study was to investigate if intermittent hypoxia may influence oxidative stress, inflammation, and protease/antiprotease system in the lung. Additionally, potential protective properties of anti-inflammatory and anti-oxidative drugs have been evaluated. METHODS 32 mice were divided into four groups: (1) intermittent hypoxia, (2) intermittent hypoxia with infliximab, (3) intermittent hypoxia with L-glutathione, and (4) normoxia. After 4 weeks, lungs and blood were collected. Levels of reactive oxygen species in the lung were calculated by L-O12-enhanced chemiluminescence. CD68-positive lung macrophages were detected by immunofluorescence. Concentrations of elastase and desmosine in lung and of alpha-1-antitrypsin in blood were calculated by means of enzyme-linked immunosorbent assay. RESULTS Compared to a control, intermittent hypoxia augmented the release of free oxygen radicals, expression of CD68+ macrophages, and concentration of elastase in the lung tissue. Despite increased blood levels of protective alpha-1-antitrypsin, concentrations of desmosine-degradation product of elastin were higher versus control. The application of anti-inflammatory infliximab und anti-oxidative L-glutathione prevented at least partly the above-observed hypoxia-associated changes. CONCLUSIONS Intermittent hypoxia contributes to the lung damage by increased oxidative stress, inflammation, and disbalance in protease/antiprotease system. Infliximab and L-glutathione may prevent adverse hypoxia-induced lung alternations.
Collapse
|
10
|
Goss KN, Tepper RS, Lahm T, Ahlfeld SK. Increased Cardiac Output and Preserved Gas Exchange Despite Decreased Alveolar Surface Area in Rats Exposed to Neonatal Hyperoxia and Adult Hypoxia. Am J Respir Cell Mol Biol 2016; 53:902-6. [PMID: 26623969 DOI: 10.1165/rcmb.2015-0100le] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Kara N Goss
- 1 University of Wisconsin School of Medicine and Public Health Madison, Wisconsin
| | - Robert S Tepper
- 2 Indiana University School of Medicine Indianapolis, Indiana
| | - Tim Lahm
- 2 Indiana University School of Medicine Indianapolis, Indiana.,3 Richard L Roudebush VA Medical Center Indianapolis, Indiana
| | | |
Collapse
|
11
|
Variation of reproductive hormone profile in male patients with obstructive sleep apnea: a meta-analysis. Sleep Biol Rhythms 2015. [DOI: 10.1007/s41105-015-0041-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
12
|
Orgeig S, Morrison JL, Daniels CB. Evolution, Development, and Function of the Pulmonary Surfactant System in Normal and Perturbed Environments. Compr Physiol 2015; 6:363-422. [PMID: 26756637 DOI: 10.1002/cphy.c150003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Surfactant lipids and proteins form a surface active film at the air-liquid interface of internal gas exchange organs, including swim bladders and lungs. The system is uniquely positioned to meet both the physical challenges associated with a dynamically changing internal air-liquid interface, and the environmental challenges associated with the foreign pathogens and particles to which the internal surface is exposed. Lungs range from simple, transparent, bag-like units to complex, multilobed, compartmentalized structures. Despite this anatomical variability, the surfactant system is remarkably conserved. Here, we discuss the evolutionary origin of the surfactant system, which likely predates lungs. We describe the evolution of surfactant structure and function in invertebrates and vertebrates. We focus on changes in lipid and protein composition and surfactant function from its antiadhesive and innate immune to its alveolar stability and structural integrity functions. We discuss the biochemical, hormonal, autonomic, and mechanical factors that regulate normal surfactant secretion in mature animals. We present an analysis of the ontogeny of surfactant development among the vertebrates and the contribution of different regulatory mechanisms that control this development. We also discuss environmental (oxygen), hormonal and biochemical (glucocorticoids and glucose) and pollutant (maternal smoking, alcohol, and common "recreational" drugs) effects that impact surfactant development. On the adult surfactant system, we focus on environmental variables including temperature, pressure, and hypoxia that have shaped its evolution and we discuss the resultant biochemical, biophysical, and cellular adaptations. Finally, we discuss the effect of major modern gaseous and particulate pollutants on the lung and surfactant system.
Collapse
Affiliation(s)
- Sandra Orgeig
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Janna L Morrison
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| | - Christopher B Daniels
- School of Pharmacy & Medical Sciences and Sansom Institute for Health Research, University of South Australia, Adelaide, Australia
| |
Collapse
|
13
|
Relationship between surfactant proteins B and C and obstructive sleep apnea: is serum SP-B concentration a potential biomarker of obstructive sleep apnea? Sleep Breath 2015; 20:25-31. [DOI: 10.1007/s11325-015-1179-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2015] [Revised: 03/25/2015] [Accepted: 04/06/2015] [Indexed: 11/26/2022]
|
14
|
Yilmaz C, Ravikumar P, Gyawali D, Iyer R, Unger RH, Hsia CCW. Alveolar-capillary adaptation to chronic hypoxia in the fatty lung. Acta Physiol (Oxf) 2015; 213:933-46. [PMID: 25363080 DOI: 10.1111/apha.12419] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/17/2014] [Accepted: 10/26/2014] [Indexed: 12/18/2022]
Abstract
AIM Obese diabetic (ZDF fa/fa) rats with genetic leptin resistance suffer chronic lipotoxicity associated with age-related lung restriction and abnormal alveolar ultrastructure. We hypothesized that these abnormalities impair adaptation to ambient hypoxia. METHODS Male fa/fa and lean (+/+) ZDF rats (4-months old) were exposed to 21 or 13% O2 for 3 weeks. Lung function was measured under anaesthesia. Lung tissue was assayed for DNA damage and ultrastructure measured by morphometry. RESULTS In normoxia, lung volume, compliance and diffusing capacity were lower, while blood flow was higher in fa/fa than +/+ rats. In hypoxia, fa/fa animals lost more weight, circulating hematocrit rose higher, and lung volume failed to increase compared to +/+. In fa/fa, the hypoxia-induced increase in post-mortem lung volume was attenuated (19%) vs. +/+ (39%). Alveolar ducts were 35% smaller in normoxia but enlarged twofold more in hypoxia compared to +/+. Hypoxia induced broad increases (90-100%) in the volumes and surface areas of alveolar septal components in +/+ lungs; these increases were moderately attenuated in fa/fa lungs (58-75%), especially that of type II epithelium volume (16 vs. 61% in +/+). In fa/fa compared to +/+ lungs, oxidative DNA damage was greater with increased hypoxia induced efflux of alveolar macrophages. Harmonic mean thickness of the diffusion barrier was higher, indicating higher structural resistance to gas transfer. CONCLUSION Chronic lipotoxicity impaired hypoxia-induced lung expansion and compensatory alveolar growth with disproportionate effect on resident alveolar progenitor cells. The moderate structural impairment was offset by physiological adaptation primarily via a higher hematocrit.
Collapse
Affiliation(s)
- C. Yilmaz
- Pulmonary and Critical Care Medicine; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| | - P. Ravikumar
- Pulmonary and Critical Care Medicine; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| | - D. Gyawali
- Pulmonary and Critical Care Medicine; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| | - R. Iyer
- Pulmonary and Critical Care Medicine; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| | - R. H. Unger
- Touchstone Diabetes Center; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| | - C. C. W. Hsia
- Pulmonary and Critical Care Medicine; Department of Internal Medicine; University of Texas Southwestern Medical Center; Dallas TX USA
| |
Collapse
|
15
|
Abstract
Obstructive sleep apnea (OSA) is a common disorder associated with cardiovascular disease (CVD). One theory to explain this relationship proposes that OSA can induce systemic inflammation, thereby inducing CVD. This theory is based on the premise that obesity is a pro-inflammatory state, and that physiological derangements during sleep in subjects with OSA further aggravate inflammation. In support of this theory, some clinical studies have shown elevated inflammatory biomarkers in OSA subjects, or improvement in these markers following treatment of OSA. However, the data are inconsistent and often confounded by the effects of comorbid obesity. Animal models of OSA have been developed, which involve exposure of rodents or cells to intermittent hypoxia, a hallmark feature of OSA. Several of these experiments demonstrate that intermittent hypoxia can stimulate inflammatory pathways and lead to cardiovascular or metabolic pathology. In this review, we review relationships between OSA and inflammation, with particular attention to studies published within the last year.
Collapse
Affiliation(s)
- Dileep Unnikrishnan
- Pulmonary and Critical Care Medicine, Johns Hopkins University School of Medicine, 5501 Hopkins Bayview Circle, Rm 5B.81, Baltimore, MD, 21224, USA
| | | | | |
Collapse
|
16
|
Broytman O, Braun RK, Morgan BJ, Pegelow DF, Hsu PN, Mei LS, Koya AK, Eldridge M, Teodorescu M. Effects of Chronic Intermittent Hypoxia on Allergen-Induced Airway Inflammation in Rats. Am J Respir Cell Mol Biol 2015; 52:162-70. [DOI: 10.1165/rcmb.2014-0213oc] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
17
|
Liang S, Li N, Heizhati M, Yao X, Abdireim A, Wang Y, Abulikemu Z, Zhang D, Chang G, Kong J, Zhou L, Hong J, Ying T, Zhang Y. What do changes in concentrations of serum surfactant proteins A and D in OSA mean? Sleep Breath 2015; 19:955-62. [DOI: 10.1007/s11325-014-1106-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 12/16/2014] [Accepted: 12/21/2014] [Indexed: 02/02/2023]
|
18
|
Persistent structural adaptation in the lungs of guinea pigs raised at high altitude. Respir Physiol Neurobiol 2014; 208:37-44. [PMID: 25534146 DOI: 10.1016/j.resp.2014.12.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/18/2014] [Accepted: 12/15/2014] [Indexed: 11/20/2022]
Abstract
Laboratory guinea pigs raised at high altitude (HA, 3800 m) for up to 6 mo exhibit enhanced alveolar growth and remodeling (Hsia et al., 2005. Resp. Physiol. Neurobiol. 147, 105-115). To determine whether initial HA-induced structural enhancement persists following return to intermediate altitude (IA), we raised weanling guinea pigs at (a) HA for 11-12 mo, (b) IA (1200 m) for 11-12 mo, and (c) HA for 4 mo followed by IA for 7-8 mo (HA-to-IA). Morphometric analysis was performed under light and electron microscopy. Body weight and lung volume were similar among groups. Prolonged HA residence increased alveolar epithelium and interstitium volumes while reducing alveolar-capillary blood volume. The HA-induced gains in type-1 epithelium volume and alveolar surface area were no longer present following return to IA whereas volume increases in type-2 epithelium and interstitium and the reduction in alveolar duct volume persisted. Results demonstrate persistent augmentation of some but not all aspects of lung structure throughout prolonged HA residence, with partial reversibility following re-acclimatization to IA.
Collapse
|
19
|
Lim DC, Brady DC, Po P, Chuang LP, Marcondes L, Kim EY, Keenan BT, Guo X, Maislin G, Galante RJ, Pack AI. Simulating obstructive sleep apnea patients' oxygenation characteristics into a mouse model of cyclical intermittent hypoxia. J Appl Physiol (1985) 2014; 118:544-57. [PMID: 25429097 DOI: 10.1152/japplphysiol.00629.2014] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Mouse models of cyclical intermittent hypoxia (CIH) are used to study the consequences of both hypoxia and oxidative stress in obstructive sleep apnea (OSA). Whether or not a mouse model of CIH that simulates OSA patients' oxygenation characteristics would translate into improved patient care remains unanswered. First we identified oxygenation characteristics using the desaturation and resaturation time in 47 OSA subjects from the Molecular Signatures of Obstructive Sleep Apnea Cohort (MSOSA). We observe that a cycle of intermittent hypoxia is not sinusoidal; specifically, desaturation time increases in an almost linear relationship to the degree of hypoxia (nadir), whereas resaturation time is somewhat constant (∼15 s), irrespective of the nadir. Second, we modified the Hycon mouse model of CIH to accommodate a 15-s resaturation time. Using this modified CIH model, we explored whether a short resaturation schedule (15 s), which includes the characteristics of OSA patients, had a different effect on levels of oxidative stress (i.e., urinary 8,12-iso-iPF2α-VI levels) compared with sham and a long resaturation schedule (90 s), a schedule that is not uncommon in rodent models of CIH. Results suggest that shorter resaturation time may result in a higher level of 8,12-iso-iPF2α-VI compared with long resaturation or sham conditions. Therefore, simulating the rodent model of CIH to reflect this and other OSA patients' oxygenation characteristics may be worthy of consideration to better understand the effects of hypoxia, oxidative stress, and their interactions.
Collapse
Affiliation(s)
- Diane C Lim
- Division of Sleep Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania;
| | - Daniel C Brady
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Pengse Po
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Li Pang Chuang
- Department of Thoracic Medicine and Department of Sleep Center, Chang Gung Memorial Hospital, Taipei, Taiwan and Graduate Institute of Clinical Medical Sciences, Chang Gung University, Tauyan, Taiwan; and
| | | | - Emily Y Kim
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Brendan T Keenan
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Xiaofeng Guo
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Greg Maislin
- Division of Sleep Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Raymond J Galante
- Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Allan I Pack
- Division of Sleep Medicine, Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Center for Sleep and Circadian Neurobiology, University of Pennsylvania, Philadelphia, Pennsylvania
| |
Collapse
|
20
|
Yang W, Hu B, Wu W, Batra S, Blackburn MR, Alcorn JL, Fallon MB, Zhang J. Alveolar type II epithelial cell dysfunction in rat experimental hepatopulmonary syndrome (HPS). PLoS One 2014; 9:e113451. [PMID: 25419825 PMCID: PMC4242631 DOI: 10.1371/journal.pone.0113451] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2014] [Accepted: 10/24/2014] [Indexed: 12/18/2022] Open
Abstract
The hepatopulmonary syndrome (HPS) develops when pulmonary vasodilatation leads to abnormal gas exchange. However, in human HPS, restrictive ventilatory defects are also observed supporting that the alveolar epithelial compartment may also be affected. Alveolar type II epithelial cells (AT2) play a critical role in maintaining the alveolar compartment by producing four surfactant proteins (SPs, SP-A, SP-B, SP-C and SP-D) which also facilitate alveolar repair following injury. However, no studies have evaluated the alveolar epithelial compartment in experimental HPS. In this study, we evaluated the alveolar epithelial compartment and particularly AT2 cells in experimental HPS induced by common bile duct ligation (CBDL). We found a significant reduction in pulmonary SP production associated with increased apoptosis in AT2 cells after CBDL relative to controls. Lung morphology showed decreased mean alveolar chord length and lung volumes in CBDL animals that were not seen in control models supporting a selective reduction of alveolar airspace. Furthermore, we found that administration of TNF-α, the bile acid, chenodeoxycholic acid, and FXR nuclear receptor activation (GW4064) induced apoptosis and impaired SP-B and SP-C production in alveolar epithelial cells in vitro. These results imply that AT2 cell dysfunction occurs in experimental HPS and is associated with alterations in the alveolar epithelial compartment. Our findings support a novel contributing mechanism in experimental HPS that may be relevant to humans and a potential therapeutic target.
Collapse
Affiliation(s)
- Wenli Yang
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Bingqian Hu
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Wei Wu
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Sachin Batra
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Michael R. Blackburn
- Department of Biochemistry and Molecular Biology, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Joseph L. Alcorn
- Division of Neonatology, Department of Pediatrics, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Michael B. Fallon
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
| | - Junlan Zhang
- Division of Gastroenterology, Hepatology and Nutrition, Department of Internal Medicine, The University of Texas Health Science Center at Houston, Houston, TX, United States of America
- * E-mail:
| |
Collapse
|
21
|
Nagai H, Kuwahira I, Schwenke DO, Tsuchimochi H, Nara A, Inagaki T, Ogura S, Fujii Y, Umetani K, Shimosawa T, Yoshida KI, Pearson JT, Uemura K, Shirai M. β2-Adrenergic receptor-dependent attenuation of hypoxic pulmonary vasoconstriction prevents progression of pulmonary arterial hypertension in intermittent hypoxic rats. PLoS One 2014; 9:e110693. [PMID: 25350545 PMCID: PMC4211686 DOI: 10.1371/journal.pone.0110693] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2014] [Accepted: 09/15/2014] [Indexed: 11/19/2022] Open
Abstract
In sleep apnea syndrome (SAS), intermittent hypoxia (IH) induces repeated episodes of hypoxic pulmonary vasoconstriction (HPV) during sleep, which presumably contribute to pulmonary arterial hypertension (PAH). However, the prevalence of PAH was low and severity is mostly mild in SAS patients, and mild or no right ventricular hypertrophy (RVH) was reported in IH-exposed animals. The question then arises as to why PAH is not a universal finding in SAS if repeated hypoxia of sufficient duration causes cycling HPV. In the present study, rats underwent IH at a rate of 3 min cycles of 4-21% O2 for 8 h/d for 6 w. Assessment of diameter changes in small pulmonary arteries in response to acute hypoxia and drugs were performed using synchrotron radiation microangiography on anesthetized rats. In IH-rats, neither PAH nor RVH was observed and HPV was strongly reversed. Nadolol (a hydrophilic β(1, 2)-blocker) augmented the attenuated HPV to almost the same level as that in N-rats, but atenolol (a hydrophilic β1-blocker) had no effect on the HPV in IH. These β-blockers had almost no effect on the HPV in N-rats. Chronic administration of nadolol during 6 weeks of IH exposure induced PAH and RVH in IH-rats, but did not in N-rats. Meanwhile, atenolol had no effect on morphometric and hemodynamic changes in N and IH-rats. Protein expression of the β1-adrenergic receptor (AR) was down-regulated while that of β2AR was preserved in pulmonary arteries of IH-rats. Phosphorylation of p85 (chief component of phosphoinositide 3-kinase (PI3K)), protein kinase B (Akt), and endothelial nitric oxide synthase (eNOS) were abrogated by chronic administration of nadolol in the lung tissue of IH-rats. We conclude that IH-derived activation of β2AR in the pulmonary arteries attenuates the HPV, thereby preventing progression of IH-induced PAH. This protective effect may depend on the β2AR-Gi mediated PI3K/Akt/eNOS signaling pathway.
Collapse
Affiliation(s)
- Hisashi Nagai
- Department of Forensic Medicine, Tokyo Medical and Dental University, Tokyo, Japan
- Department of Forensic Medicine, The University of Tokyo, Tokyo, Japan
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
- * E-mail:
| | - Ichiro Kuwahira
- Department of Pulmonary Medicine, Tokai University Tokyo Hospital, Tokyo, Japan
| | - Daryl O. Schwenke
- Department of Physiology-Heart Otago, University of Otago, Dunedin, New Zealand
| | - Hirotsugu Tsuchimochi
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Akina Nara
- Department of Forensic Medicine, The University of Tokyo, Tokyo, Japan
| | - Tadakatsu Inagaki
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Sayoko Ogura
- Department of Forensic Medicine, The University of Tokyo, Tokyo, Japan
- Division of Laboratory Medicine, Department of Pathology and Microbiology, Faculty of Medicine, Nihon University School of Medicine, Tokyo, Japan
| | - Yutaka Fujii
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| | - Keiji Umetani
- Japan Synchrotron Radiation Research Institute, Hyogo, Japan
| | - Tatsuo Shimosawa
- Department of Clinical Laboratory Medicine, The University of Tokyo, Tokyo, Japan
| | - Ken-ichi Yoshida
- Department of Forensic Medicine, The University of Tokyo, Tokyo, Japan
- Department of Forensic Medicine, Tokyo Medical University, Tokyo, Japan
| | - James T. Pearson
- Monash Biomedical Imaging Facility and Department of Physiology, Monash University, Melbourne, Clayton, Victoria, Australia
- Australian Synchrotron, Clayton, Victoria, Australia
| | - Koichi Uemura
- Department of Forensic Medicine, Tokyo Medical and Dental University, Tokyo, Japan
| | - Mikiyasu Shirai
- Department of Cardiac Physiology, National Cerebral and Cardiovascular Center Research Institute, Osaka, Japan
| |
Collapse
|
22
|
Shin MK, Yao Q, Jun JC, Bevans-Fonti S, Yoo DY, Han W, Mesarwi O, Richardson R, Fu YY, Pasricha PJ, Schwartz AR, Shirahata M, Polotsky VY. Carotid body denervation prevents fasting hyperglycemia during chronic intermittent hypoxia. J Appl Physiol (1985) 2014; 117:765-76. [PMID: 25103977 DOI: 10.1152/japplphysiol.01133.2013] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Obstructive sleep apnea causes chronic intermittent hypoxia (IH) and is associated with impaired glucose metabolism, but mechanisms are unknown. Carotid bodies orchestrate physiological responses to hypoxemia by activating the sympathetic nervous system. Therefore, we hypothesized that carotid body denervation would abolish glucose intolerance and insulin resistance induced by chronic IH. Male C57BL/6J mice underwent carotid sinus nerve dissection (CSND) or sham surgery and then were exposed to IH or intermittent air (IA) for 4 or 6 wk. Hypoxia was administered by decreasing a fraction of inspired oxygen from 20.9% to 6.5% once per minute, during the 12-h light phase (9 a.m.-9 p.m.). As expected, denervated mice exhibited blunted hypoxic ventilatory responses. In sham-operated mice, IH increased fasting blood glucose, baseline hepatic glucose output (HGO), and expression of a rate-liming hepatic enzyme of gluconeogenesis phosphoenolpyruvate carboxykinase (PEPCK), whereas the whole body glucose flux during hyperinsulinemic euglycemic clamp was not changed. IH did not affect glucose tolerance after adjustment for fasting hyperglycemia in the intraperitoneal glucose tolerance test. CSND prevented IH-induced fasting hyperglycemia and increases in baseline HGO and liver PEPCK expression. CSND trended to augment the insulin-stimulated glucose flux and enhanced liver Akt phosphorylation at both hypoxic and normoxic conditions. IH increased serum epinephrine levels and liver sympathetic innervation, and both increases were abolished by CSND. We conclude that chronic IH induces fasting hyperglycemia increasing baseline HGO via the CSN sympathetic output from carotid body chemoreceptors, but does not significantly impair whole body insulin sensitivity.
Collapse
Affiliation(s)
- Mi-Kyung Shin
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Qiaoling Yao
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Jonathan C Jun
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Shannon Bevans-Fonti
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Doo-Young Yoo
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Woobum Han
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Omar Mesarwi
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ria Richardson
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Ya-Yuan Fu
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Pankaj J Pasricha
- Division of Gastroenterology and Hepatology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland; and
| | - Alan R Schwartz
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland
| | - Machiko Shirahata
- Department of Environmental Health Sciences, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Vsevolod Y Polotsky
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland;
| |
Collapse
|
23
|
Peng X, Li HX, Shao HJ, Li GW, Sun J, Xi YH, Li HZ, Wang XY, Wang LN, Bai SZ, Zhang WH, Zhang L, Yang GD, Wu LY, Wang R, Xu CQ. Involvement of calcium-sensing receptors in hypoxia-induced vascular remodeling and pulmonary hypertension by promoting phenotypic modulation of small pulmonary arteries. Mol Cell Biochem 2014; 396:87-98. [DOI: 10.1007/s11010-014-2145-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Accepted: 07/11/2014] [Indexed: 12/19/2022]
|
24
|
Lim DC, Pack AI. Obstructive sleep apnea and cognitive impairment: addressing the blood-brain barrier. Sleep Med Rev 2014; 18:35-48. [PMID: 23541562 PMCID: PMC3758447 DOI: 10.1016/j.smrv.2012.12.003] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Revised: 12/21/2012] [Accepted: 12/24/2012] [Indexed: 12/14/2022]
Abstract
Increasing data support a connection between obstructive sleep apnea (OSA) and cognitive impairment but a causal link has yet to be established. Although neuronal loss has been linked to cognitive impairment, emerging theories propose that changes in synaptic plasticity can cause cognitive impairment. Studies demonstrate that disruption to the blood-brain barrier (BBB), which is uniquely structured to tightly maintain homeostasis inside the brain, leads to changes in the brain's microenvironment and affects synaptic plasticity. Cyclical intermittent hypoxia is a stressor that could disrupt the BBB via molecular responses already known to occur in either OSA patients or animal models of intermittent hypoxia. However, we do not yet know if or how intermittent hypoxia can cause cognitive impairment by mechanisms operating at the BBB. Therefore, we propose that initially, adaptive homeostatic responses at the BBB occur in response to increased oxygen and nutrient demand, specifically through regulation of influx and efflux BBB transporters that alter microvessel permeability. We further hypothesize that although these responses are initially adaptive, these changes in BBB transporters can have long-term consequences that disrupt the brain's microenvironment and alter synaptic plasticity leading to cognitive impairment.
Collapse
Affiliation(s)
- Diane C Lim
- Department of Medicine, Division of Sleep Medicine, and Center for Sleep and Circadian Neurobiology, University of Pennsylvania, 125 South 31st Street, Suite 2100, Philadelphia, PA 19104, USA.
| | - Allan I Pack
- Department of Medicine, Division of Sleep Medicine, and Center for Sleep and Circadian Neurobiology, University of Pennsylvania, 125 South 31st Street, Suite 2100, Philadelphia, PA 19104, USA.
| |
Collapse
|
25
|
Jones RC, Capen DE. Alveolar oxygen tension and angio-architecture of the distal adult lung. Ultrastruct Pathol 2013; 37:395-407. [PMID: 24144043 DOI: 10.3109/01913123.2013.831156] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
The present study demonstrates the fine structure of pulmonary capillaries first injured and then undergoing growth in response to a change in the ambient alveolar oxygen tension. Breathing a high fraction of inspired oxygen (FiO2 0.75) triggers restriction by endothelial cell injury and effacement leading to segment narrowing and shortening and segment loss as demonstrated by a fall in density. Subsequently, breathing a relatively low fraction (FiO2 0.21) triggers capillary assembly (angiogenesis), which reverses the changes. The data underscore the structural reprogramming (reduction and restoration) of pulmonary capillaries in response to significant shifts in oxygen tension.
Collapse
Affiliation(s)
- Rosemary C Jones
- Department of Anesthesia, Critical Care and Pain Medicine, Massachusetts General Hospital and
| | | |
Collapse
|
26
|
Huang J, Li Z, Yao X, Li Y, Reng X, Li J, Wang W, Gao J, Wang C, Tankersley CG, Huang K. Altered Th1/Th2 commitment contributes to lung senescence in CXCR3-deficient mice. Exp Gerontol 2013; 48:717-26. [PMID: 23583952 DOI: 10.1016/j.exger.2013.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Revised: 03/28/2013] [Accepted: 04/03/2013] [Indexed: 01/08/2023]
Abstract
Aging is an inevitable process associated with immune imbalance, which is characterized by a progressive functional decline in major organs, including lung. However, effects of altered Th1/Th2 commitment on lung senescence are largely unknown. To examine effects of altered Th1/Th2 balance on lung aging, we measured proportions of Th1 and Th2 cells and expression of cytokines, chemokines, collagen deposition and other relevant physiological and pathological parameters in 2- and 20-months-old (mo) CXCR3-deficient (CXCR3(-/-)) C57BL/6J mice compared with wild-type (WT) mice. There was a significant weight-loss observed in 20-mo CXCR3(-/-) mice compared with the same aged WT group. Although lung function and structure changed with age in both groups, central airway resistance (Rn), tissue elastance (H) and damping (G) were significantly lower in 20-mo CXCR3(-/-) mice than those of WT mice. In contrast, the whole lung volume (V(L)), the mean linear intercept length of alveolar (L(m)), and the total lung collagen content were significantly elevated in 20-mo CXCR3(-/-) mice. With aging, the lungs of WT mice had typical Th1-type status (increased population of Th1 cells and concentrations of cytokine IFN-γ and CXCR3 ligands) while CXCR3(-/-) mice showed Th2-type polarization (decreased proportion of Th1 cells and concentrations of CXCR3 ligands but increased level of IL-4). Our data suggest that Immunosenescence is associated with lung aging, and that altered Th1/Th2 imbalance favors Th2 predominance in CXCR3(-/-) mice, which contributes to the process of accelerated lung aging in this model.
Collapse
Affiliation(s)
- Junmin Huang
- Beijing Key Laboratory of Respiratory and Pulmonary Circulation Disorders, PR China
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Yao Q, Shin MK, Jun JC, Hernandez KL, Aggarwal NR, Mock JR, Gay J, Drager LF, Polotsky VY. Effect of chronic intermittent hypoxia on triglyceride uptake in different tissues. J Lipid Res 2013; 54:1058-65. [PMID: 23386706 PMCID: PMC3605982 DOI: 10.1194/jlr.m034272] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Revised: 01/22/2013] [Indexed: 11/20/2022] Open
Abstract
Chronic intermittent hypoxia (CIH) inhibits plasma lipoprotein clearance and adipose lipoprotein lipase (LPL) activity in association with upregulation of an LPL inhibitor angiopoietin-like protein 4 (Angptl4). We hypothesize that CIH inhibits triglyceride (TG) uptake via Angptl4 and that an anti-Angptl4-neutralizing antibody would abolish the effects of CIH. Male C57BL/6J mice were exposed to four weeks of CIH or intermittent air (IA) while treated with Ab (30 mg/kg ip once a week). TG clearance was assessed by [H(3)]triolein administration retroorbitally. CIH delayed TG clearance and suppressed TG uptake and LPL activity in all white adipose tissue depots, brown adipose tissue, and lungs, whereas heart, liver, and spleen were not affected. CD146+ CD11b- pulmonary microvascular endothelial cells were responsible for TG uptake in the lungs and its inhibition by CIH. Antibody to Angptl4 decreased plasma TG levels and increased TG clearance and uptake into adipose tissue and lungs in both control and CIH mice to a similar extent, but did not reverse the effects of CIH. The antibody reversed the effects of CIH on LPL in adipose tissue and lungs. In conclusion, CIH inactivates LPL by upregulating Angptl4, but inhibition of TG uptake occurs predominantly via an Angptl4/LPL-independent mechanism.
Collapse
Affiliation(s)
- Qiaoling Yao
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| | - Mi-Kyung Shin
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| | - Jonathan C. Jun
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| | | | - Neil R. Aggarwal
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| | - Jason R. Mock
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| | - Jason Gay
- Lexicon Pharmaceuticals Inc., The Woodlands, TX 77381
| | - Luciano F. Drager
- Heart Institute (InCor), University of São Paulo Medical School, 5403-904, São Paulo, Brazil
| | - Vsevolod Y. Polotsky
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21224
| |
Collapse
|
28
|
Mirrakhimov AE, Polotsky VY. Obstructive sleep apnea and non-alcoholic Fatty liver disease: is the liver another target? Front Neurol 2012; 3:149. [PMID: 23087670 PMCID: PMC3473309 DOI: 10.3389/fneur.2012.00149] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Accepted: 10/01/2012] [Indexed: 12/15/2022] Open
Abstract
Obstructive sleep apnea (OSA) is recurrent obstruction of the upper airway during sleep leading to intermittent hypoxia (IH). OSA has been associated with all components of the metabolic syndrome as well as with non-alcoholic fatty liver disease (NAFLD). NAFLD is a common condition ranging in severity from uncomplicated hepatic steatosis to steatohepatitis (NASH), liver fibrosis, and cirrhosis. The gold standard for the diagnosis and staging of NAFLD is liver biopsy. Obesity and insulin resistance lead to liver steatosis, but the causes of the progression to NASH are not known. Emerging evidence suggests that OSA may play a role in the progression of hepatic steatosis and the development of NASH. Several cross-sectional studies showed that the severity of IH in patients with OSA predicted the severity of NAFLD on liver biopsy. However, neither prospective nor interventional studies with continuous positive airway pressure treatment have been performed. Studies in a mouse model showed that IH causes triglyceride accumulation in the liver and liver injury as well as hepatic inflammation. The mouse model provided insight in the pathogenesis of liver injury showing that (1) IH accelerates the progression of hepatic steatosis by inducing adipose tissue lipolysis and increasing free fatty acids (FFA) flux into the liver; (2) IH up-regulates lipid biosynthetic pathways in the liver; (3) IH induces oxidative stress in the liver; (4) IH up-regulates hypoxia inducible factor 1 alpha and possibly HIF-2 alpha, which may increase hepatic steatosis and induce liver inflammation and fibrosis. However, the role of FFA and different transcription factors in the pathogenesis of IH-induced NAFLD is yet to be established. Thus, multiple lines of evidence suggest that IH of OSA may contribute to the progression of NAFLD but definitive clinical studies and experiments in the mouse model have yet to be done.
Collapse
|
29
|
Reinke C, Bevans-Fonti S, Drager LF, Shin MK, Polotsky VY. Effects of different acute hypoxic regimens on tissue oxygen profiles and metabolic outcomes. J Appl Physiol (1985) 2011; 111:881-90. [PMID: 21737828 DOI: 10.1152/japplphysiol.00492.2011] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Obstructive sleep apnea (OSA) causes intermittent hypoxia (IH) during sleep. Both obesity and OSA are associated with insulin resistance and systemic inflammation, which may be attributable to tissue hypoxia. We hypothesized that a pattern of hypoxic exposure determines both oxygen profiles in peripheral tissues and systemic metabolic outcomes, and that obesity has a modifying effect. Lean and obese C57BL6 mice were exposed to 12 h of intermittent hypoxia 60 times/h (IH60) [inspired O₂ fraction (Fi(O₂)) 21-5%, 60/h], IH 12 times/h (Fi(O₂) 5% for 15 s, 12/h), sustained hypoxia (SH; Fi(O₂) 10%), or normoxia while fasting. Tissue oxygen partial pressure (Pti(O₂)) in liver, skeletal muscle and epididymal fat, plasma leptin, adiponectin, insulin, blood glucose, and adipose tumor necrosis factor-α (TNF-α) were measured. In lean mice, IH60 caused oxygen swings in the liver, whereas fluctuations of Pti(O₂) were attenuated in muscle and abolished in fat. In obese mice, baseline liver Pti(O₂) was lower than in lean mice, whereas muscle and fat Pti(O₂) did not differ. During IH, Pti(O₂) was similar in obese and lean mice. All hypoxic regimens caused insulin resistance. In lean mice, hypoxia significantly increased leptin, especially during SH (44-fold); IH60, but not SH, induced a 2.5- to 3-fold increase in TNF-α secretion by fat. Obesity was associated with striking increases in leptin and TNF-α, which overwhelmed effects of hypoxia. In conclusion, IH60 led to oxygen fluctuations in liver and muscle and steady hypoxia in fat. IH and SH induced insulin resistance, but inflammation was increased only by IH60 in lean mice. Obesity caused severe inflammation, which was not augmented by acute hypoxic regimens.
Collapse
Affiliation(s)
- Christian Reinke
- Dept. of Internal Medicine, Division of Pulmonary Diseases, Univ. Hospital Giessen and Marburg GmbH, 35043 Marburg, Germany.
| | | | | | | | | |
Collapse
|