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Sharma S, Singh Y, Sandhir R, Singh S, Ganju L, Kumar B, Varshney R. Mitochondrial DNA mutations contribute to high altitude pulmonary edema via increased oxidative stress and metabolic reprogramming during hypobaric hypoxia. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148431. [PMID: 33862004 DOI: 10.1016/j.bbabio.2021.148431] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Revised: 03/27/2021] [Accepted: 04/07/2021] [Indexed: 10/21/2022]
Abstract
High altitude pulmonary edema (HAPE) is experienced by non-acclimatized sea level individuals on exposure to high altitude hypoxic conditions. Available evidence suggests that genetic factors and perturbed mitochondrial redox status may play an important role in HAPE pathophysiology. However, the precise mechanism has not been fully understood. In the present study, sequencing of mitochondrial DNA (mtDNA) from HAPE subjects and acclimatized controls was performed to identify pathogenic mutations and to determine their role in HAPE. Hypobaric hypoxia induced oxidative stress and metabolic alterations were also assessed in HAPE subjects. mtDNA copy number, mitochondrial oxidative phosphorylation (mtOXPHOS) activity, mitochondrial biogenesis were measured to determine mitochondrial functions. The data revealed that the mutations in Complex I genes affects the secondary structure of protein in HAPE subjects. Further, increased oxidative stress during hypobaric hypoxia, reduced mitochondrial biogenesis and mtOXPHOS activity induced metabolic reprogramming appears to contribute to mitochondrial dysfunctions in HAPE individuals. Haplogroup analysis suggests that mtDNA haplogroup H2a2a1 has potential contribution in the pathobiology of HAPE in lowlanders. This study also suggests contribution of altered mitochondrial functions in HAPE susceptibility.
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Affiliation(s)
- Swati Sharma
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India; Department of Biochemistry, Basic Medical Sciences Block II, Panjab University, Chandigarh 160014, India
| | - Yamini Singh
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India.
| | - Rajat Sandhir
- Department of Biochemistry, Basic Medical Sciences Block II, Panjab University, Chandigarh 160014, India
| | - Sayar Singh
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India
| | - Lilly Ganju
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India
| | - Bhuvnesh Kumar
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India
| | - Rajeev Varshney
- Defence Institute of Physiology and Allied Sciences (DIPAS), Defence R&D Organization (DRDO), Lucknow Road, Timarpur, Delhi 110054, India
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Tan J, Gao C, Wang C, Ma L, Hou X, Liu X, Li Z. Expression of Aquaporin-1 and Aquaporin-5 in a Rat Model of High-Altitude Pulmonary Edema and the Effect of Hyperbaric Oxygen Exposure. Dose Response 2020; 18:1559325820970821. [PMID: 33192205 PMCID: PMC7607770 DOI: 10.1177/1559325820970821] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 09/24/2020] [Accepted: 10/08/2020] [Indexed: 11/29/2022] Open
Abstract
Objective: To investigate the therapeutic roles of hyperbaric oxygen exposure on high-altitude pulmonary edema and to determine whether aquaporin-1 and aquaporin-5 were involved in the pathogenesis of HAPE in rats. Methods: Rats were divided into 5 groups: The control group, the HAPE group (HAPE model), the HBO group (hyperbaric oxygen exposure), the NBO group (normobaric oxygen exposure), and the NA group (normal air exposure). Western blot and real-time PCR were used to analyze the pulmonary expressions of AQP1 and AQP5. The wet-to-dry (W/D) weight ratio and the morphology of the lung were also examined. Results: The lung W/D weight ratio in the HAPE group was increased compared with the control group. The injury score in the HBO group was noticeably lower than that in the control group. The mRNA and proteins expressions of AQP1 and AQP5 were significantly downregulated in the HAPE group. Conclusions: Oxygen exposure alleviated high-altitude hypobaric hypoxia-induced lung injury in rats. Additionally, HBO therapy had significant advantage on interstitial HAPE.
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Affiliation(s)
- Jiewen Tan
- Department of Rehabilitation Medicine, XinHua College, Sun Yat-Sen University, Guangzhou, China
| | - Chunjin Gao
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Cong Wang
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Linlin Ma
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Xiaomin Hou
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Xuehua Liu
- Department of Hyperbaric Oxygen, Beijing Chao-Yang Hospital, Capital Medical University, Beijing, China
| | - Zhuo Li
- Department of Rehabilitation Medicine, XinHua College, Sun Yat-Sen University, Guangzhou, China
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Sonocomplexation as an effective tool to enhance the antitumorigenic effect of metformin: Preparation, in vitro characterization, molecular dynamic simulation & MiaPaCa-2 cell line hypoxia evaluation. J Drug Deliv Sci Technol 2020. [DOI: 10.1016/j.jddst.2020.101968] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Tsai SH, Huang PH, Tsai HY, Hsu YJ, Chen YW, Wang JC, Chen YH, Lin SJ. Roles of the hypoximir microRNA-424/322 in acute hypoxia and hypoxia-induced pulmonary vascular leakage. FASEB J 2019; 33:12565-12575. [PMID: 31461385 DOI: 10.1096/fj.201900564rr] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Acute mountain sickness (AMS) occurs in up to 25% of unacclimatized persons who ascend to 3000 m and can result in high-altitude pulmonary edema (HAPE). MicroRNAs (miRs) can regulate gene expression at the post-transcriptional level. Hypoxia selectively disrupts endothelial tight junction complexes through a hypoxia-inducible factor-1α (HIF-1α)-dependent mechanism. Though increased HIF-1α expression is associated with adaptation and protection from AMS development in the early stage of hypoxia, a downstream effector of HIF-1α, VEGF, can induce overzealous endothelial barrier dysfunction, increase vascular permeability, and ultimately result in HAPE and high-altitude cerebral edema. We hypothesized that the fine-tuning of downstream effectors by miRs is paramount for the preservation of endothelial barrier integrity and the prevention of vascular leakage. We found that several miRs were up-regulated in healthy volunteers who were subjected to a 3100-m height. By reviewing the literature and using online bioinformatics prediction software, we specifically selected miR-424 for further investigation because it can modulate both HIF-1α and VEGF. Hypoxia-induced miR-424 overexpression is HIF-1α dependent, and miR-424 stabilized HIF-1α, decreased VEGF expression, and promoted vascular endothelial cadherin phosphorylation. In addition, hypoxia resulted in endothelial barrier dysfunction with increased permeability; miR-424 thus attenuated hypoxia-induced endothelial cell senescence and apoptosis. miR-322 knockout mice were susceptible to hypoxia-induced pulmonary vascular leakage. miR-322 mimics improved hypoxia-induced pulmonary vascular leakage in vivo. We conclude that several miRs were up-regulated in healthy adult volunteers subjected to hypobaric hypoxemia. miR-424/322 could modulate the HIF-1α-VEGF axis and prevent hypoxia-induced pulmonary vascular leakage under hypoxic conditions.-Tsai, S.-H., Huang, P.-H., Tsai, H.-Y., Hsu, Y.-J., Chen, Y.-W., Wang, J.-C., Chen, Y.-H., Lin, S.-J. Roles of the hypoximir microRNA-424/322 in acute hypoxia and hypoxia-induced pulmonary vascular leakage.
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Affiliation(s)
- Shih-Hung Tsai
- Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.,Department of Physiology and Biophysics, Graduate Institute of Physiology, National Defense Medical Center, Taipei, Taiwan
| | - Po-Hsun Huang
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Department of Critical Care Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Hsiao-Ya Tsai
- Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yu-Juei Hsu
- Division of Nephrology, Department of Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Yen-Wen Chen
- Department of Chest Medicine, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Jen-Chun Wang
- Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.,Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Ying-Hsin Chen
- Department of Emergency Medicine, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan
| | - Shing-Jong Lin
- Institute of Clinical Medicine, National Yang-Ming University, Taipei, Taiwan.,Division of Cardiology, Department of Internal Medicine, Taipei Veterans General Hospital, Taipei, Taiwan.,Cardiovascular Research Center, National Yang-Ming University, Taipei, Taiwan.,Healthcare and Services Center, Taipei Veterans General Hospital, Taipei, Taiwan.,Taipei Heart Institute, Taipei Medical University, Taipei, Taiwan
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Khanna K, Mishra KP, Chanda S, Eslavath MR, Ganju L, Kumar B, Singh SB. Effects of Acute Exposure to Hypobaric Hypoxia on Mucosal Barrier Injury and the Gastrointestinal Immune Axis in Rats. High Alt Med Biol 2018; 20:35-44. [PMID: 30484710 DOI: 10.1089/ham.2018.0031] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
High altitude-induced gastrointestinal (GI) problems are potentially life-threatening. GI tract bleeding and inflammation are the major problems induced by hypobaric hypoxia (HH). In this study, effects of acute exposure to HH up to 14 days at 7620 m on GI immune function have been studied. To fulfill these objectives, Sprague-Dawley (SD) rats were divided into five groups namely Control and HH exposed (1, 3, 7, and 14 days). All groups except control were exposed to 7620 m of HH in an animal decompression chamber for the respective time intervals. Different degrees of intestinal mucosal damage in terms of increased mucosal permeability and disruption of intestinal villi were observed for different time intervals. HH exposure also upregulated secretory immunoglobulin A (sIgA) and proinflammatory cytokines in GI lavage along with proinflammatory markers such as toll-like receptor 4 (TLR4) and inducible nitric oxide synthase (iNOS). HH exposure of rats for 7 days significantly increased interleukin-17 (IL-17) and natural killer (NK) cell and dendritic cell populations compared with unexposed control rats. However, the number of naive T cells was significantly decreased in Peyer's patches. Our results connect HH to GI immune axis and highlight Th17 cells and proinflammatory molecules as potential therapeutic targets to counteract HH-induced GI dysfunction.
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Affiliation(s)
- Kunjan Khanna
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Kamla Prasad Mishra
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Sudipta Chanda
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Malleswara Rao Eslavath
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Lilly Ganju
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Bhuvnesh Kumar
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
| | - Shashi Bala Singh
- Defence Institute of Physiology & Allied Sciences (DIPAS) , Defence Research and Development Organisation (DRDO), New Delhi, India
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Gonzalez NC, Kuwahira I. Systemic Oxygen Transport with Rest, Exercise, and Hypoxia: A Comparison of Humans, Rats, and Mice. Compr Physiol 2018; 8:1537-1573. [PMID: 30215861 DOI: 10.1002/cphy.c170051] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The objective of this article is to compare and contrast the known characteristics of the systemic O2 transport of humans, rats, and mice at rest and during exercise in normoxia and hypoxia. This analysis should help understand when rodent O2 transport findings can-and cannot-be applied to human responses to similar conditions. The O2 -transport system was analyzed as composed of four linked conductances: ventilation, alveolo-capillary diffusion, circulatory convection, and tissue capillary-cell diffusion. While the mechanisms of O2 transport are similar in the three species, the quantitative differences are naturally large. There are abundant data on total O2 consumption and on ventilatory and pulmonary diffusive conductances under resting conditions in the three species; however, there is much less available information on pulmonary gas exchange, circulatory O2 convection, and tissue O2 diffusion in mice. The scarcity of data largely derives from the difficulty of obtaining blood samples in these small animals and highlights the need for additional research in this area. In spite of the large quantitative differences in absolute and mass-specific O2 flux, available evidence indicates that resting alveolar and arterial and venous blood PO2 values under normoxia are similar in the three species. Additionally, at least in rats, alveolar and arterial blood PO2 under hypoxia and exercise remain closer to the resting values than those observed in humans. This is achieved by a greater ventilatory response, coupled with a closer value of arterial to alveolar PO2 , suggesting a greater efficacy of gas exchange in the rats. © 2018 American Physiological Society. Compr Physiol 8:1537-1573, 2018.
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Affiliation(s)
- Norberto C Gonzalez
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Ichiro Kuwahira
- Department of Pulmonary Medicine, Tokai University School of Medicine, Tokai University Tokyo Hospital, Tokyo, Japan
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Jain K, Suryakumar G, Ganju L, Singh SB. Amelioration of ER stress by 4-phenylbutyric acid reduces chronic hypoxia induced cardiac damage and improves hypoxic tolerance through upregulation of HIF-1α. Vascul Pharmacol 2016; 83:36-46. [PMID: 27058435 DOI: 10.1016/j.vph.2016.03.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Revised: 02/27/2016] [Accepted: 03/12/2016] [Indexed: 12/14/2022]
Abstract
While endoplasmic reticulum (ER) stress has been observed in several human diseases, few studies have reported the involvement of ER stress in chronic hypoxia (CH) induced cardiac damage. Hypoxia, such as that prevalent at high altitude (HA), forms the underlying cause of several maladies including cardiovascular diseases. While the role of hypoxia inducible factor-1 (HIF-1α) in the adaptive responses to hypoxia is known, the role of the unfolded protein response (UPR) is only recently being explored in the HA pathophysiologies. The present study investigates the effect of ER stress modulation on CH mediated injury and the cardioprotective action of 4-phenylbutyric acid (PBA) in enhancing survival response under hypoxia. Here, we observed that exposure of rats, for 1, 7 and 14days CH to a simulated altitude of 7620m, led to cardiac hypertrophy and significant protein oxidation. This induced the activation of UPR signaling mechanisms, mediated by PERK, IRE1α and ATF6. By 14days, there was a marked upregulation of apoptosis, evident in increased CHOP and caspase-3/9 activity. PBA reduced CH induced right ventricular enlargement and apoptosis. Further, in contrast to tunicamycin, PBA considerably enhanced hypoxic tolerance. An elevation in the level of antioxidant enzymes, HIF-1α and its regulated proteins (HO-1, GLUT-1) was observed in the PBA administered animals, along with a concomitant suppression of UPR markers. Our study thus emphasizes upon the attenuation of ER stress by PBA as a mechanism to diminish CH induced cardiac injury and boost hypoxic survival, providing an insight into the novel relationship between the HIF-1α and UPR under hypoxia.
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Affiliation(s)
- Kanika Jain
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Geetha Suryakumar
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi 110 054, India.
| | - Lilly Ganju
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi 110 054, India
| | - Shashi Bala Singh
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Lucknow Road, Timarpur, Delhi 110 054, India
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Lisk C, Kominsky D, Ehrentraut S, Bonaventura J, Nuss R, Hassell K, Nozik-Grayck E, Irwin DC. Hemoglobin-induced endothelial cell permeability is controlled, in part, via a myeloid differentiation primary response gene-88-dependent signaling mechanism. Am J Respir Cell Mol Biol 2014; 49:619-26. [PMID: 23713977 DOI: 10.1165/rcmb.2012-0440oc] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The release of hemoglobin (Hb) with hemolysis causes vascular dysfunction. New evidence implicates Hb-induced NF-κB and hypoxia inducible factor (HIF) activation, which may be under the control of a Toll-like receptor (TLR)-signaling pathway. Nearly all TLR-signaling pathways activate the myeloid differentiation primary response gene-88 (MyD88) that regulates NF-κB. We hypothesized that the differing transition states of Hb influence endothelial cell permeability via NF-κB activation and HIF regulation through a MyD88-dependent pathway. In cultured human dermal microvascular endothelial cells (HMECs-1), we examined the effects of Hb in the ferrous (HbFe(2+)), ferric (HbFe(3+)), and ferryl (HbFe(4+)) transition states on NF-κB and HIF activity, HIF-1α and HIF-2α mRNA up-regulation, and monolayer permeability, in the presence or absence of TLR4, MyD88, NF-κB, or HIF inhibition, as well as superoxide dismutase (SOD) and catalase. Our data showed that cell-free Hb, in each transition state, induced NF-κB and HIF activity, up-regulated HIF-1α and HIF-2α mRNA, and increased HMEC-1 permeability. The blockade of either MyD88 or NF-κB, but not TLR4, attenuated Hb-induced HIF activity, the up-regulation HIF-1 and HIF-2α mRNA, and HMEC-1 permeability. The inhibition of HIF activity exerted less of an effect on Hb-induced monolayer permeability. Moreover, SOD and catalase attenuated NF-κB, HIF activity, and monolayer permeability. Our results demonstrate that Hb-induced NF-κB and HIF are regulated by two mechanisms, either MyD88 activation or Hb transition state-induced ROS formation, that influence HMEC-1 permeability.
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Affiliation(s)
- Christina Lisk
- 1 Cardiovascular Pulmonary Research Group, Division of Cardiology, Department of Medicine
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Abstract
Hypoxic pulmonary vasoconstriction (HPV) continues to fascinate cardiopulmonary physiologists and clinicians since its definitive description in 1946. Hypoxic vasoconstriction exists in all vertebrate gas exchanging organs. This fundamental response of the pulmonary vasculature in air breathing animals has relevance to successful fetal transition to air breathing at birth and as a mechanism of ventilation-perfusion matching in health and disease. It is a complex process intrinsic to the vascular smooth muscle, but with in vivo modulation by a host of factors including the vascular endothelium, erythrocytes, pulmonary innervation, circulating hormones and acid-base status to name only a few. This review will provide a broad overview of HPV and its mechansms and discuss the advantages and disadvantages of HPV in normal physiology, disease and high altitude.
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Affiliation(s)
- Erik R Swenson
- Department of Medicine, University of Washington, VA Puget Sound Health Care System, Seattle, WA 98108, USA.
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She J, Bi J, Tong L, Song Y, Bai C. New insights of aquaporin 5 in the pathogenesis of high altitude pulmonary edema. Diagn Pathol 2013; 8:193. [PMID: 24274330 PMCID: PMC3937216 DOI: 10.1186/1746-1596-8-193] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 10/26/2013] [Indexed: 11/28/2022] Open
Abstract
Background High altitude pulmonary edema (HAPE) affects individuals and is characterized by alveolar flooding with protein-rich edema as a consequence of blood-gas barrier disruption. In this study, we hypothesized that aquaporin 5 (AQP5) which is one kind of water channels may play a role in preservation of alveolar epithelial barrier integrity in high altitude pulmonary edema (HAPE). Methods Therefore, we established a model in Wildtype mice and AQP5 −/− mice were assingned to normoxic rest (NR), hypoxic rest (HR) and hypoxic exercise (HE) group. Mice were produced by training to walk at treadmill for exercising and chamber pressure was reduced to simulate climbing an altitude of 5000 m for 48 hours. Studies using BAL in HAPE mice to demonstrated that edema is caused leakage of albumin proteins and red cells across the alveolarcapillary barrier in the absence of any evidence of inflammation. Results In this study, the Lung wet/dry weight ratio and broncholalveolar lavage protein concentrations were slightly increased in HE AQP5 −/− mice compared to wildtype mice. And histologic evidence of hemorrhagic pulmonary edema was distinctly shown in HE group. The lung Evan’s blue permeability of HE group was showed slightly increased compare to the wildtype groups, and HR group was showed a medium situation from normal to HAPE development compared with NR and HE group. Conclusions Deletion of AQP5 slightly increased lung edema and lung injury compared to wildtype mice during HAPE development, which suggested that the AQP5 plays an important role in HAPE formation induced by high altitude simulation.
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Affiliation(s)
| | | | | | | | - Chunxue Bai
- Department of Pulmonary Medicine, Zhongshan Hospital, Fudan University, NO,180 Fenglin Road, Shanghai 200032, China.
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Abstract
High-altitude pulmonary edema (HAPE), a not uncommon form of acute altitude illness, can occur within days of ascent above 2500 to 3000 m. Although life-threatening, it is avoidable by slow ascent to permit acclimatization or with drug prophylaxis. The critical pathophysiology is an excessive rise in pulmonary vascular resistance or hypoxic pulmonary vasoconstriction (HPV) leading to increased microvascular pressures. The resultant hydrostatic stress causes dynamic changes in the permeability of the alveolar capillary barrier and mechanical injurious damage leading to leakage of large proteins and erythrocytes into the alveolar space in the absence of inflammation. Bronchoalveolar lavage and hemodynamic pressure measurements in humans confirm that elevated capillary pressure induces a high-permeability noninflammatory lung edema. Reduced nitric oxide availability and increased endothelin in hypoxia are the major determinants of excessive HPV in HAPE-susceptible individuals. Other hypoxia-dependent differences in ventilatory control, sympathetic nervous system activation, endothelial function, and alveolar epithelial active fluid reabsorption likely contribute additionally to HAPE susceptibility. Recent studies strongly suggest nonuniform regional hypoxic arteriolar vasoconstriction as an explanation for how HPV occurring predominantly at the arteriolar level causes leakage. In areas of high blood flow due to lesser HPV, edema develops due to pressures that exceed the dynamic and structural capacity of the alveolar capillary barrier to maintain normal fluid balance. This article will review the pathophysiology of the vasculature, alveolar epithelium, innervation, immune response, and genetics of the lung at high altitude, as well as therapeutic and prophylactic strategies to reduce the morbidity and mortality of HAPE.
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Affiliation(s)
- Erik R Swenson
- VA Puget Sound Health Care System, Department of Medicine, University of Washington, Seattle, Washington, USA.
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Jain K, Suryakumar G, Prasad R, Ganju L. Upregulation of cytoprotective defense mechanisms and hypoxia-responsive proteins imparts tolerance to acute hypobaric hypoxia. High Alt Med Biol 2013; 14:65-77. [PMID: 23537263 DOI: 10.1089/ham.2012.1064] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Exposure to high altitude is a well-known environmental stress with physiological and metabolic consequences, with the major stressor being hypobaric hypoxia. The disruption in cellular homeostasis elicits several acute and chronic adaptations designed to diminish the stress imposed by the hypoxic insult. Highly conserved cellular machinery protects the myocardium from damage under reduced oxygen tension. In the present study, adult Sprague-Dawley rats were exposed to an altitude of 9754 m in a decompression chamber and screened on the basis of the time taken for onset of gasping. The animals were grouped as susceptible (<10 min), normal (10-25 min), and tolerant (>25 min). Histologically, susceptible animals showed increased myocardial inflammation and infiltration and greater CK-MB activity. These animals showed a three-fold increase in reactive oxygen species levels and subsequent oxidative damage to proteins and lipids as compared to control unexposed group. In tolerant animals, the damage was minimal. The resistance to damage in these animals was possibly due to enhanced myocardial antioxidant enzymes, catalase and superoxide dismutase. A significantly higher expression of HIF-1α and its responsive genes, including EPO, HO-1, and GLUT1, was seen in tolerant animals, although VEGF expression was enhanced in the susceptible group. Cytoprotective chaperones, HSP70 and HSP90, were elevated in the tolerant animals. The differential expression of these hypoxia-responsive molecules may thus act as potential biochemical markers for screening and identifying individuals susceptible to environmental stress.
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Affiliation(s)
- Kanika Jain
- Cellular Biochemistry Division, Defence Institute of Physiology and Allied Sciences, Timarpur, Delhi, India
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Luo Y, Gao W, Chen Y, Liu F, Gao Y. Rare Mitochondrial DNA Polymorphisms are Associated with High Altitude Pulmonary Edema (HAPE) Susceptibility in Han Chinese. Wilderness Environ Med 2012; 23:128-32. [DOI: 10.1016/j.wem.2012.02.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Revised: 01/31/2012] [Accepted: 02/02/2012] [Indexed: 10/24/2022]
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Reducing pulmonary injury by hyperbaric oxygen preconditioning during simulated high altitude exposure in rats. ACTA ACUST UNITED AC 2012; 71:673-9. [PMID: 21248653 DOI: 10.1097/ta.0b013e3181f5b073] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Hyperbaric oxygen preconditioning (HBO₂P + HAE) has been found to be beneficial in preventing the occurrence of ischemic damage to brain, spinal cord, heart, and liver in several disease models. In addition, pulmonary inflammation and edema are associated with a marked reduction in the expression levels of both aquaporin (AQP) 1 and AQP5 in the lung. Here, the aims of this study are first to ascertain whether acute lung injury can be induced by simulated high altitude in rats and second to assess whether HBO2P + HAE is able to prevent the occurrence of the proposed high altitude-induced ALI. METHODS Rats were randomly divided into the following three groups: the normobaric air (NBA; 21% O₂ at 1 ATA) group, the HBO₂P + high altitude exposure (HAE) group, and the NBA + HAE group. In HBO₂P + HAE group, animals received 100% O₂ at 2.0 ATA for 1 hour per day, for five consecutive days. In HAE groups, animals were exposed to a simulated HAE of 6,000 m in a hypobaric chamber for 24 hours. Right after being taken out to the ambient, animals were anesthetized generally and killed and thoroughly exsanguinated before their lungs were excised en bloc. The lungs were used for both histologic and molecular evaluation and analysis. RESULTS In NBA + HAE group, the animals displayed higher scores of alveolar edema, neutrophil infiltration, and hemorrhage compared with those of NBA controls. In contrast, the levels of both AQP1 and AQP5 proteins and mRNA expression in the lung in the NBA + HAE group were significantly lower than those of NBA controls. However, the increased lung injury scores and the decreased levels of both AQP1 and AQP5 proteins and mRNA expression in the lung caused by HAE was significantly reduced by HBO₂P + HAE. CONCLUSIONS Our results suggest that high altitude pulmonary injury may be prevented by HBO2P + HAE in rats.
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Gomez-Arroyo J, Saleem SJ, Mizuno S, Syed AA, Bogaard HJ, Abbate A, Taraseviciene-Stewart L, Sung Y, Kraskauskas D, Farkas D, Conrad DH, Nicolls MR, Voelkel NF. A brief overview of mouse models of pulmonary arterial hypertension: problems and prospects. Am J Physiol Lung Cell Mol Physiol 2012; 302:L977-91. [PMID: 22307907 DOI: 10.1152/ajplung.00362.2011] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Many chronic pulmonary diseases are associated with pulmonary hypertension (PH) and pulmonary vascular remodeling, which is a term that continues to be used to describe a wide spectrum of vascular abnormalities. Pulmonary vascular structural changes frequently increase pulmonary vascular resistance, causing PH and right heart failure. Although rat models had been standard models of PH research, in more recent years the availability of genetically engineered mice has made this species attractive for many investigators. Here we review a large amount of data derived from experimental PH reports published since 1996. These studies using wild-type and genetically designed mice illustrate the challenges and opportunities provided by these models. Hemodynamic measurements are difficult to obtain in mice, and right heart failure has not been investigated in mice. Anatomical, cellular, and genetic differences distinguish mice and rats, and pharmacogenomics may explain the degree of PH and the particular mode of pulmonary vascular adaptation and also the response of the right ventricle.
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Affiliation(s)
- Jose Gomez-Arroyo
- Victoria Johnson Center for Obstructive Lung Disease Research, Virginia Commonwealth University, 1220 E. Broad St., Richmond, VA 23298, USA
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Sands M, Howell K, Costello CM, McLoughlin P. Placenta growth factor and vascular endothelial growth factor B expression in the hypoxic lung. Respir Res 2011; 12:17. [PMID: 21266048 PMCID: PMC3040134 DOI: 10.1186/1465-9921-12-17] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2010] [Accepted: 01/25/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Chronic alveolar hypoxia, due to residence at high altitude or chronic obstructive lung diseases, leads to pulmonary hypertension, which may be further complicated by right heart failure, increasing morbidity and mortality. In the non-diseased lung, angiogenesis occurs in chronic hypoxia and may act in a protective, adaptive manner. To date, little is known about the behaviour of individual vascular endothelial growth factor (VEGF) family ligands in hypoxia-induced pulmonary angiogenesis. The aim of this study was to examine the expression of placenta growth factor (PlGF) and VEGFB during the development of hypoxic pulmonary angiogenesis and their functional effects on the pulmonary endothelium. METHODS Male Sprague Dawley rats were exposed to conditions of normoxia (21% O2) or hypoxia (10% O2) for 1-21 days. Stereological analysis of vascular structure, real-time PCR analysis of vascular endothelial growth factor A (VEGFA), VEGFB, placenta growth factor (PlGF), VEGF receptor 1 (VEGFR1) and VEGFR2, immunohistochemistry and western blots were completed. The effects of VEGF ligands on human pulmonary microvascular endothelial cells were determined using a wound-healing assay. RESULTS Typical vascular remodelling and angiogenesis were observed in the hypoxic lung. PlGF and VEGFB mRNA expression were significantly increased in the hypoxic lung. Immunohistochemical analysis showed reduced expression of VEGFB protein in hypoxia although PlGF protein was unchanged. The expression of VEGFA mRNA and protein was unchanged. In vitro PlGF at high concentration mimicked the wound-healing actions of VEGFA on pulmonary microvascular endothelial monolayers. Low concentrations of PlGF potentiated the wound-healing actions of VEGFA while higher concentrations of PlGF were without this effect. VEGFB inhibited the wound-healing actions of VEGFA while VEGFB and PlGF together were mutually antagonistic. CONCLUSIONS VEGFB and PlGF can either inhibit or potentiate the actions of VEGFA, depending on their relative concentrations, which change in the hypoxic lung. Thus their actions in vivo depend on their specific concentrations within the microenvironment of the alveolar wall during the course of adaptation to pulmonary hypoxia.
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Affiliation(s)
- Michelle Sands
- School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Science, University College Dublin, Belfield, Dublin, Ireland
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Snow JB, Kanagy NL, Walker BR, Resta TC. Rat strain differences in pulmonary artery smooth muscle Ca(2+) entry following chronic hypoxia. Microcirculation 2009; 16:603-14. [PMID: 19626552 DOI: 10.1080/10739680903114268] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Effects of chronic hypoxia (CH) on store- and receptor-operated Ca(2+) entry (SOCE, ROCE) in pulmonary vascular smooth muscle (VSM) are controversial, although whether genetic variation explains such discrepancies in commonly studied rat strains is unclear. Since protein kinase C (PKC) can inhibit Ca(2+) permeable nonselective cation channels, we hypothesized that CH differentially alters PKC-dependent inhibition of SOCE and ROCE in pulmonary VSM from Sprague-Dawley and Wistar rats. To test this hypothesis, we examined SOCE and endothelin-1 (ET-1)-induced ROCE in endothelium-disrupted, pressurized pulmonary arteries from control and CH Sprague-Dawley and Wistar rats. Basal VSM Ca(2+) was elevated in CH Wistar, but not Sprague-Dawley, rats. Further, CH attenuated SOCE in VSM from Sprague-Dawley rats, while augmenting this response in Wistar rats. CH reduced ROCE in arteries from both strains. PKC inhibition restored SOCE in CH Sprague-Dawley arteries to control levels, while having no effect on SOCE in Wistar arteries or on ROCE in either strain. We conclude that effects of CH on pulmonary VSM SOCE are strain dependent, whereas inhibitory effects of CH on ROCE are strain independent. Further, PKC inhibits SOCE following CH in Sprague-Dawley, but not Wistar, rats but does not contribute to ET-1-induced ROCE in either strain.
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Affiliation(s)
- Jessica B Snow
- Vascular Physiology Group, Department of Cell Biology and Physiology, University of New Mexico Health Sciences Center, Albuquerque, New Mexico 87131-0001, USA.
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