Hyperoxia Induces Inflammation and Cytotoxicity in Human Adult Cardiac Myocytes

Abstract

Supplemental oxygen (O2) is used as adjunct therapy in anesthesia, emergency, and intensive care medicine. We hypothesized that excessive O2 levels (hyperoxia) can directly injure human adult cardiac myocytes (HACMs). HACMs obtained from the explanted hearts of transplantation patients were exposed to constant hyperoxia (95% O2), intermittent hyperoxia (alternating 10 min exposures to 5% and 95% O2), constant normoxia (21% O2), or constant mild hypoxia (5% O2) using a bioreactor. Changes in cell morphology, viability as assessed by lactate dehydrogenase (LDH) release and trypan blue (TB) staining, and secretion of vascular endothelial growth factor (VEGF), macrophage migration inhibitory factor (MIF), and various pro-inflammatory cytokines (interleukin, IL; chemokine C-X-C motif ligand, CXC; granulocyte-colony stimulating factor, G-CSF; intercellular adhesion molecule, ICAM; chemokine C-C motif ligand, CCL) were compared among treatment groups at baseline (0 h) and after 8, 24, and 72 h of treatment. Changes in HACM protein expression were determined by quantitative proteomic analysis after 48 h of exposure. Compared with constant normoxia and mild hypoxia, constant hyperoxia resulted in a higher TB-positive cell count, greater release of LDH, and elevated secretion of VEGF, MIF, IL-1β, IL-6, IL-8, CXCL-1, CXCL-10, G-CSF, ICAM-1, CCL-3, and CCL-5. Cellular inflammation and cytotoxicity gradually increased and was highest after 72 h of constant and intermittent hyperoxia. Quantitative proteomic analysis revealed that hypoxic and hyperoxic O2 exposure differently altered the expression levels of proteins involved in cell-cycle regulation, energy metabolism, and cell signaling. In conclusion, constant and intermittent hyperoxia induced inflammation and cytotoxicity in HACMs. Cell injury occurred earliest and was greatest after constant hyperoxia, but even relatively brief repeating hyperoxic episodes induced a substantial inflammatory response.

Feline Hypertrophic Cardiomyopathy: The Consequence of Cardiomyocyte-Initiated and Macrophage-Driven Remodeling Processes?

“…18 In humans it has been shown that compared to their normoxic counterparts, cardiomyocytes exposed to constant hypoxia have elevated secretion levels of inflammatory cytokines, including IL-1, IL-6, IL-8, as well as certain growth factors and chemokines. 15 The initial cause of myocardial damage in feline HCM that would trigger the observed remodeling processes is still unknown, but hypoxia appears likely considering the present findings. 4,12 So far unknown structural or functional myocardial alterations could result in latent myocardial hypoxia, leading to individual cardiomyocyte degeneration and death.…”

Oxygen Supplementation Ameliorates Tibial Development via Stimulating Vascularization in Tibetan Chickens at High Altitudes

“…indicated that alternating hypoxia/hyperoxia may induce a more reliable pro-angiogenic regulators up-regulation compared with normoxia 11 . Furthermore, several studies have been reported that high oxygen concentrations can modulate mRNA expression of several genes and related protein secretion including hypoxia inducible factor (HIF)-1α (a master oxygen sensitive transcriptional regulator), vascular endothelial growth factor-A (VEGFA), and interleukin (IL)-8 15 , 19 - 21 . Particularly VEGFA, VEGF receptor-1 (VEGFR1/Flt-1) and VEGFR2 (KDR/Flk-1) are the critical pro-angiogenic factor for vascular formation 11 , 22 , 23 .…”

Investigating Disturbances of Oxygen Homeostasis: From Cellular Mechanisms to the Clinical Practice

“…Several other factors contribute to the complex response of the cell to hyperoxia, i.e., STAT (signal transducers and activators of transcription protein)-subtypes, CEBP (ccat/enhancer binding protein), c-myc, Fra-1, junB and c-Fos. To better understand the tissues’ responses to hyperoxia, several recent studies investigated proteomic alterations in response to various degrees of hyperoxia ( Konsavage et al, 2013 ; Hinkelbein et al, 2015 ; Hafner et al, 2017b ). The complexity of the cellular proteome as well as the use of different experimental and analytical protocols necessarily leads to different results and conclusions in these studies.…”