scholarly journals Microbiota Modulates Cardiac Transcriptional Responses to Intermittent Hypoxia and Hypercapnia

2021 ◽  
Vol 12 ◽  
Author(s):  
Dan Zhou ◽  
Jin Xue ◽  
Yukiko Miyamoto ◽  
Orit Poulsen ◽  
Lars Eckmann ◽  
...  
Keyword(s):  
Intermittent Hypoxia ◽  
Cardiovascular Response ◽  
Critical Role ◽  
Transcriptional Response ◽  
Mouse Heart ◽  
Transcriptional Responses ◽  
Germ Free ◽  
Cage System ◽  
Obstructive Sleep ◽  
The Impact

The microbiota plays a critical role in regulating organismal health and response to environmental stresses. Intermittent hypoxia and hypercapnia, a condition that represents the main hallmark of obstructive sleep apnea in humans, is known to induce significant alterations in the gut microbiome and metabolism, and promotes the progression of atherosclerosis in mouse models. To further understand the role of the microbiome in the cardiovascular response to intermittent hypoxia and hypercapnia, we developed a new rodent cage system that allows exposure of mice to controlled levels of O2 and CO2 under gnotobiotic conditions. Using this experimental setup, we determined the impact of the microbiome on the transcriptional response to intermittent hypoxia and hypercapnia in the left ventricle of the mouse heart. We identified significant changes in gene expression in both conventionally reared and germ-free mice. Following intermittent hypoxia and hypercapnia exposure, we detected 192 significant changes in conventionally reared mice (96 upregulated and 96 downregulated) and 161 significant changes (70 upregulated and 91 downregulated) in germ-free mice. Only 19 of these differentially expressed transcripts (∼10%) were common to conventionally reared and germ-free mice. Such distinct transcriptional responses imply that the host microbiota plays an important role in regulating the host transcriptional response to intermittent hypoxia and hypercapnia in the mouse heart.

scholarly journals Paracrine interactions between epithelial cells promote colon cancer growth

2020 ◽  
Author(s):  
Guillaume Jacquemin ◽  
Annabelle Wurmser ◽  
Mathilde Huyghe ◽  
Wenjie Sun ◽  
Meghan Perkins ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cancer Cells ◽  
Stromal Cells ◽  
Critical Role ◽  
Essential Factor ◽  
Transcriptional Responses ◽  
Tumour Formation ◽  
Different Types ◽  
The Impact

AbstractTumours are complex ecosystems composed of different types of cells that communicate and influence each other. While the critical role of stromal cells in affecting tumour growth is well established, the impact of mutant cancer cells on healthy surrounding tissues remains poorly defined. Here, we uncovered a paracrine mechanism by which intestinal cancer cells reactivate foetal and regenerative Yap-associated transcriptional programs in neighbouring wildtype epithelial cells, rendering them adapted to thrive in the tumour context. We identified the glycoprotein Thrombospondin-1 (Thbs1) as the essential factor that mediates non-cell autonomous morphological and transcriptional responses. Importantly, Thbs1 is associated with bad prognosis in several human cancers. This study reveals the Thbs1-YAP axis as the mechanistic link mediating paracrine interactions between epithelial cells, promoting tumour formation and progression.

Invited Review: Physiological consequences of intermittent hypoxia: systemic blood pressure

2001 ◽  
Vol 90 (4) ◽  
pp. 1600-1605 ◽  
Author(s):  
Eugene C. Fletcher
Keyword(s):  
Blood Pressure ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Intermittent Hypoxia ◽  
Cardiovascular Response ◽  
Acute Hypoxia ◽  
Renin Angiotensin System ◽  
Systemic Blood Pressure ◽  
Angiotensin Ii Receptor ◽  
Obstructive Sleep

One of the major manifestations of obstructive sleep apnea is profound and repeated hypoxia during sleep. Acute hypoxia leads to stimulation of the peripheral chemoreceptors, which in turn increases sympathetic outflow, acutely increasing blood pressure. The chronic effect of these repeated episodic or intermittent periods of hypoxia in humans is difficult to study because chronic cardiovascular changes may take many years to manifest. Rodents have been a tremendous source of information in short- and long-term studies of hypertension and other cardiovascular diseases. Recurrent short cycles of normoxia-hypoxia, when administered to rats for 35 days, allows examination of the chronic cardiovascular response to intermittent hypoxia patterned after the episodic desaturation seen in humans with sleep apnea. The result of this type of intermittent hypoxia in rats is a 10- to 14-mmHg increase in resting (unstimulated) mean blood pressure that lasts for several weeks after cessation of the daily cyclic hypoxia. Carotid body denervation, sympathetic nerve ablation, renal sympathectomy, adrenal medullectomy, and angiotensin II receptor blockade block the blood pressure increase. It appears that adrenergic and renin-angiotensin system overactivity contributes to the early chronic elevated blood pressure in rat intermittent hypoxia and perhaps to human hypertension associated with obstructive sleep apnea.

scholarly journals Intermittent Hypoxia Increases the Severity of Bleomycin-Induced Lung Injury in Mice

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Thomas Gille ◽  
Morgane Didier ◽  
Cécile Rotenberg ◽  
Eva Delbrel ◽  
Dominique Marchant ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Pulmonary Fibrosis ◽  
Pulmonary Edema ◽  
Cell Apoptosis ◽  
Lung Fibrosis ◽  
Intermittent Hypoxia ◽  
Chronic Intermittent Hypoxia ◽  
Obstructive Sleep ◽  
The Impact ◽  
Lung Oxidative Stress

Background. Severe obstructive sleep apnea (OSA) with chronic intermittent hypoxia (IH) is common in idiopathic pulmonary fibrosis (IPF). Here, we evaluated the impact of IH on bleomycin- (BLM-) induced pulmonary fibrosis in mice. Methods. C57BL/6J mice received intratracheal BLM or saline and were exposed to IH (40 cycles/hour; FiO2 nadir: 6%; 8 hours/day) or intermittent air (IA). In the four experimental groups, we evaluated (i) survival; (ii) alveolar inflammation, pulmonary edema, lung oxidative stress, and antioxidant enzymes; (iii) lung cell apoptosis; and (iv) pulmonary fibrosis. Results. Survival at day 21 was lower in the BLM-IH group (p<0.05). Pulmonary fibrosis was more severe at day 21 in BLM-IH mice, as assessed by lung collagen content (p=0.02) and histology. At day 4, BLM-IH mice developed a more severe neutrophilic alveolitis, (p<0.001). Lung oxidative stress was observed, and superoxide dismutase and glutathione peroxidase expression was decreased in BLM-IH mice (p<0.05 versus BLM-IA group). At day 8, pulmonary edema was observed and lung cell apoptosis was increased in the BLM-IH group. Conclusion. These results show that exposure to chronic IH increases mortality, lung inflammation, and lung fibrosis in BLM-treated mice. This study raises the question of the worsening impact of severe OSA in IPF patients.

scholarly journals Transcriptional Response to Intermittent Hypoxia in the Heart of Germ‐Free Mice

2019 ◽  
Vol 33 (S1) ◽  
Author(s):  
Dan Zhou ◽  
Iain Hartley ◽  
Orit Poulsen ◽  
Jin Xue ◽  
Gabriel G Haddad
Keyword(s):  
Intermittent Hypoxia ◽  
Transcriptional Response ◽  
Germ Free

scholarly journals Obstructive Sleep Apnea and Circulating Biomarkers of Oxidative Stress: A Cross-Sectional Study

Antioxidants ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 476
Author(s):  
Bernardo U. Peres ◽  
AJ Hirsch Allen ◽  
Aditi Shah ◽  
Nurit Fox ◽  
Ismail Laher ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiovascular Disease ◽  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Intermittent Hypoxia ◽  
Smoking History ◽  
Obstructive Sleep ◽  
History Of ◽  
Statin Usage ◽  
The Impact

Oxidative stress (OS) drives cardiometabolic diseases. Intermittent hypoxia consistently increases oxidative stress markers. Obstructive sleep apnea (OSA) patients experience intermittent hypoxia and an increased rate of cardiovascular disease, however, the impact of OSA on OS markers is not clear. The objective was to assess relationships between OSA severity and biomarker levels. Patients with suspected OSA referred for a polysomnogram (PSG) provided fasting blood sample. Plasma levels of 8-isoprostane, 8-hydroxydeoxyguanosine (8-OHdG), and superoxide dismutase (SOD) were measured. The relationship between OSA and OS was assessed both before and after controlling for confounders (age, sex, smoking history, history of cardiovascular disease, ethnicity, diabetes, statin usage, body mass index (BMI)). 402 patients were studied (68% male, mean age ± SD = 50.8 ± 11.8 years, apnea-hypopnea index (AHI) = 22.2 ± 21.6 events/hour, BMI = 31.62 ± 6.49 kg/m2). In a multivariable regression, the AHI significantly predicted 8-isoprostane levels (p = 0.0008) together with age and statin usage; AHI was not a predictor of 8-OHdG or SOD. Female sex (p < 0.0001) and no previous history of cardiovascular disease (p = 0.002) were associated with increased antioxidant capacity. Circulating 8-isoprostane levels may be a promising biomarker of the severity of oxidative stress in OSA patients. Prospective studies are needed to determine whether this biomarker is associated with long-term cardiometabolic complications in OSA.

scholarly journals Intermittent hypoxia and hypercapnia induces inhibitor of nuclear factor-κB kinase subunit β-dependent atherosclerosis in pulmonary arteries

2019 ◽  
Vol 317 (6) ◽  
pp. R763-R769 ◽  
Author(s):  
Toshihiro Imamura ◽  
Jin Xue ◽  
Orit Poulsen ◽  
Dan Zhou ◽  
Michael Karin ◽  
...  
Keyword(s):  
Intermittent Hypoxia ◽  
Early Stage ◽  
Critical Role ◽  
Pulmonary Arteries ◽  
Density Lipoprotein ◽  
Essential Element ◽  
Nuclear Factor Κb ◽  
Nuclear Factor ◽  
Double Knockout ◽  
Obstructive Sleep

Clinical studies have shown that obstructive sleep apnea (OSA) increases atherosclerosis risk. The inflammation, especially mediated by the macrophages via nuclear factor-κB (NF-κB), has been speculated to contribute to atherogenicity in OSA patients. Inhibitor of NF-κB kinase-β (IKKβ) is an essential element of the NF-κB pathway and is linked to atherosclerosis. We previously reported that atherosclerosis was accelerated in pulmonary artery (PA) but not in aorta when low-density lipoprotein receptor knockout ( Ldlr−/−) mice were exposed to intermittent hypoxia/hypercapnia (IHH), a surrogate for recurrent upper-airway obstruction. Therefore, we hypothesized that IKKβ-dependent NF-κB activation in monocytes and macrophages plays a role in IHH-induced PA atherosclerosis. To test this hypothesis, myeloid restricted IKKβ deletion ( IkkβΔMye) or control ( IkkβF/F) mice were crossed with Ldlr−/− mice to generate double-knockout mice. Then, the mice were exposed to IHH or room air (Air) on high-fat diet for 8 or 16 wk. Lesions of PA and aorta were examined in IkkβΔMye; Ldlr−/− and IkkβF/F; Ldlr−/− male mice under IHH vs. Air. The results revealed that IKKβ deletion abolished IHH-induced PA atherosclerosis after 8-wk exposure but not after 16-wk exposure (8 wk: IkkβF/F; Ldlr−/−, IHH 13.5 ± 1.4 vs. Air 5.7 ± 0.7%, P < 0.01; IkkβΔMye; Ldlr−/−, IHH 7.4 ± 1.9% vs. Air 4.6 ± 1.3%, P = 0.24). Both IKKβ deletion and IHH had no effects on atherosclerosis in the aorta. Our findings demonstrate that IKKβ-dependent NF-κB activity in myeloid-lineage cells plays a critical role in IHH-induced PA atherosclerosis at the early stage.

Yap is required for scar formation but not myocyte proliferation during heart regeneration in zebrafish

2018 ◽  
Vol 115 (3) ◽  
pp. 570-577 ◽  
Author(s):  
Michael A Flinn ◽  
Brooke E Jeffery ◽  
Caitlin C O’Meara ◽  
Brian A Link
Keyword(s):  
Heart Development ◽  
Critical Role ◽  
Scar Formation ◽  
Cardiac Cells ◽  
Mouse Heart ◽  
Heart Regeneration ◽  
Post Injury ◽  
Myocyte Proliferation ◽  
The Impact ◽  
Zebrafish Heart

Abstract Aims The Hippo signalling pathway regulates multiple cellular processes during organ development and maintenance by modulating activity of the transcriptional cofactor Yap. Core components of this pathway are required for neonatal mouse heart regeneration, however, investigations to date have typically focused on expression and activity in cardiomyocytes. Due to the regenerative capacity of zebrafish and the fact that global loss of Yap is not fully embryonic lethal in zebrafish, we leveraged a yap null mutant to investigate the impact of constitutive Yap deletion during zebrafish heart regeneration. Methods and results Following cryoinjury in adult hearts, myocyte proliferation was not decreased in yap mutants, contrary to expectations based on mouse data. Experiments in larval zebrafish (Danio rerio) revealed that deletion of either Yap or Taz had a modest effect on heart growth, reducing gross organ size, while their combined deletion was synergistic; thus, Yap and Taz share some overlapping roles in zebrafish heart development. Surprisingly, adult yap mutants exhibited decreased collagen composition at 7 days post-injury, suggesting a critical role for Yap in scar formation during heart regeneration. siRNA-mediated Yap knockdown in primary rat (Rattus norvegicus) cardiac cells revealed a fibroblast-specific role for Yap in controlling the expression of cytoskeletal and myofibroblast activation genes, as well as pro-inflammatory cyto/chemokines. Corroborating these RNAseq data, we observed increased macrophage infiltration in the scars of yap mutants at 7 days post-injury. Conclusion These results suggest that Yap deletion has minimal effect on myocyte proliferation in adults, but significantly influences scar formation and immune cell infiltration during zebrafish heart regeneration. Collectively, these data suggest an unexpected role for Yap in matrix formation and macrophage recruitment during heart regeneration.

scholarly journals Glucose and glutamine availability regulate HepG2 transcriptional responses to low oxygen

2018 ◽  
Vol 3 ◽  
pp. 126 ◽  
Author(s):  
Alvina G. Lai ◽  
Donall Forde ◽  
Wai Hoong Chang ◽  
Fang Yuan ◽  
Xiaodong Zhuang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mass Spectrometry ◽  
Transcriptional Response ◽  
Global Changes ◽  
Low Oxygen ◽  
Transcriptional Responses ◽  
Dna Hydroxymethylation ◽  
Modified Dna ◽  
The Impact

Background: Little is known about the impact of nutrients on cellular transcriptional responses, especially in face of environmental stressors such as oxygen deprivation. Hypoxia-inducible factors (HIF) coordinate the expression of genes essential for adaptation to oxygen-deprived environments. A second family of oxygen-sensing genes known as the alpha-ketoglutarate-dependent dioxygenases are also implicated in oxygen homeostasis and epigenetic regulation. The relationship between nutritional status and cellular response to hypoxia is understudied. In vitro cell culture systems frequently propagate cells in media that contains excess nutrients, and this may directly influence transcriptional response in hypoxia. Methods: We studied the effect of glucose and glutamine concentration on HepG2 hepatoma transcriptional response to low oxygen and expression of hypoxia inducible factor-1α (HIF-1α). Mass spectrometry confirmed low oxygen perturbation of dioxygenase transcripts resulted in changes in DNA methylation. Results: Under normoxic conditions, we observed a significant upregulation of both HIF-target genes and oxygen-dependent dioxygenases in HepG2 cells cultured with physiological levels of glucose or glutamine relative to regular DMEM media, demonstrating that excess glutamine/glucose can mask changes in gene expression. Under hypoxic conditions, CA9 was the most upregulated gene in physiological glutamine media while TETs and FTO dioxygenases were downregulated in physiological glucose. Hypoxic regulation of these transcripts did not associate with changes in HIF-1α protein expression. Downregulation of TETs suggests a potential for epigenetic modulation. Mass-spectrometry quantification of modified DNA bases confirmed our transcript data. Hypoxia resulted in decreased DNA hydroxymethylation, which correlated with TETs downregulation. Additionally, we observed that TET2 expression was significantly downregulated in patients with hepatocellular carcinoma, suggesting that tumour hypoxia may deregulate TET2 expression resulting in global changes in DNA hydroxymethylation.   Conclusion: Given the dramatic effects of nutrient availability on gene expression, future in vitro experiments should be aware of how excess levels of glutamine and glucose may perturb transcriptional responses.

Intermittent hypoxia reduces upper airway stability in lean but not obese Zucker rats

2007 ◽  
Vol 293 (1) ◽  
pp. R372-R378 ◽  
Author(s):  
Andrew D. Ray ◽  
Ulysses J. Magalang ◽  
Charles P. Michlin ◽  
Toshiyuki Ogasa ◽  
John A. Krasney ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Intermittent Hypoxia ◽  
Upper Airway ◽  
Zucker Rats ◽  
Obstructive Sleep ◽  
Obese Rats ◽  
Supramaximal Stimulation ◽  
Obese Zucker Rats ◽  
The Impact ◽  
Stimulation Of

Obstructive sleep apnea involves intermittent periods of airway occlusions that lead to repetitive oxygen desaturations. Exposure to chronic intermittent hypoxia (IH) in rats increases diurnal blood pressure and alters skeletal muscle physiology. The impact of IH on upper airway muscle function is unknown. We hypothesize that IH exposure increases upper airway collapsibility in rats due to alterations of the muscles surrounding the upper airway. Lean and obese rats were exposed to cyclic alterations in O2 levels (20.6%-5%) every 90 s, 8 h/day for 6 days/wk for 12 wk. Following the exposure period, arterial pressure was recorded via the tail artery in conscious unrestrained rats. Mean arterial pressure was increased in lean IH but not in obese IH-exposed Zucker rats ( P < 0.05). The pharyngeal pressure associated with airway collapse (Pcrit) was measured under anesthesia during baseline conditions and then during supramaximal stimulation of the hypoglossal nerve (cnXII). Baseline Pcrit was more positive (more collapsible) in lean but not obese rats following 12 wk of IH ( P < 0.05), while supramaximal stimulation of cnXII increased airway stability (decreased Pcrit) in both lean and obese Zucker rats following IH to levels that were similar to their respective room air controls. The in vitro peak tension and the expression of the individual myosin heavy chain isoforms from the upper airway muscles were unaltered following IH. We conclude that IH leads to increases in baseline collapsibility in lean Zucker rats exposed to IH by nonmyogenic mechanisms.

scholarly journals The impact of arousal state, sex, and sleep apnea on the magnitude of progressive augmentation and ventilatory long-term facilitation

2013 ◽  
Vol 114 (1) ◽  
pp. 52-65 ◽  
Author(s):  
Ziauddin Syed ◽  
Ho-Sheng Lin ◽  
Jason H. Mateika
Keyword(s):  
Sleep Apnea ◽  
Intermittent Hypoxia ◽  
Recovery Period ◽  
Apnea Hypopnea Index ◽  
Arousal State ◽  
Obstructive Sleep ◽  
End Tidal ◽  
Long Term Facilitation ◽  
The Impact

We examined the impact of arousal state, sex, and obstructive sleep apnea (OSA) on the magnitude of progressive augmentation of the hypoxic ventilatory response and ventilatory long-term facilitation (vLTF). We also examined whether exposure to intermittent hypoxia during sleep has an impact on the apnea-hypopnea index (AHI) in individuals with OSA. Ten men and seven women with OSA, along with ten healthy men and ten healthy women, were exposed to twelve 2-min episodes of hypoxia (end-tidal Po2: 50 Torr) in the presence of sustained hypercapnia (end-tidal Pco2: 3 Torr above baseline), followed by a 30-min recovery period during wakefulness and sleep. The OSA participants completed an additional sham study during sleep. The AHI during the first hour of sleep following the intermittent hypoxia and sham protocols were compared. Progressive augmentation was only evident during wakefulness and was enhanced in the OSA participants. vLTF was evident during wakefulness and sleep. When standardized to baseline, vLTF was greater during wakefulness and was enhanced in the OSA group (men: wakefulness 1.39 ± 0.08 vs. sleep 1.14 ± 0.03; women: wakefulness 1.35 ± 0.03 vs. sleep 1.16 ± 0.05 fraction of baseline; P ≤ 0.001) compared with control (men: wakefulness 1.19 ± 0.03 vs. sleep 1.09 ± 0.03; women: wakefulness 1.26 ± 0.05 vs. sleep 1.08 ± 0.04 fraction of baseline; P ≤ 0.001). The AHI following exposure to intermittent hypoxia was increased (intermittent hypoxia 72.8 ± 7.3 vs. sham 56.5 ± 7.0 events/h; P ≤ 0.01). Sex-related differences were not observed for the primary measures. We conclude that progressive augmentation is not evident, and the magnitude of vLTF is diminished during sleep compared with wakefulness in men and women. However, when present, the phenomena are enhanced in individuals with OSA. The AHI data indicate that, under the prevailing experimental conditions, vLTF did not serve to mitigate apnea severity.

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