Hypoxia-induced Alterations Research Articles

PCSK9 as a new player in intermittent hypoxia-induced vascular alterations

PCSK9 as a new player in intermittent hypoxia-induced vascular alterations

Acute moderate normobaric hypoxia does not modify circulating thyroid hormone concentrations induced by 1 h of head-out cold-water immersion.

This study tested the hypothesis that acute moderate normobaric hypoxia augments circulating thyroid hormone concentrations during and following 1 h of cold head-out water immersion (HOWI), compared with when cold HOWI is completed during normobaric normoxia. In a randomized crossover single-blind design, 12 healthy adults (27 ± 2 yr, 2 women) completed 1 h of cold (22.0 ± 0.1°C) HOWI breathing either normobaric normoxia ([Formula: see text] = 0.21) or normobaric hypoxia ([Formula: see text] = 0.14). Free and total thyroxine (T3) and triiodothyronine (T4), and thyroid-stimulating hormone (TSH) concentrations were measured in venous blood samples obtained before (baseline), during (15-, 30-, and 60 min), and 15 min following HOWI (post-), and were corrected for changes in plasma volume. Arterial oxyhemoglobin saturation and core (rectal) temperature were measured continuously. Arterial oxyhemoglobin saturation was lower during hypoxia (90 ± 3%) compared with normoxia (98 ± 1%, P < 0.001). Core temperature fell from baseline (normoxia: 37.2 ± 0.4°C, hypoxia: 37.2 ± 0.4°C) to post-cold HOWI (normoxia: 36.4 ± 0.5°C, hypoxia: 36.3 ± 0.5°C, P < 0.001) in both conditions but did not change differently between conditions (condition × time: P = 0.552). Circulating TSH, total T3, free T4, total T3, and free T4 concentrations demonstrated significant main effects of time (all P ≤ 0.024), but these changes did not differ between normoxic and hypoxic conditions (condition × time: all P ≥ 0.163). These data indicate that acute moderate normobaric hypoxia does not modify the circulating thyroid hormone response during 1 h of cold HOWI.NEW & NOTEWORTHY Acute head-out cold (22°C) water immersion (HOWI) decreased core temperature and increased thermogenesis. This thermogenic response was paralleled by the activation of the hypothalamic-pituitary-thyroid axis, as evidenced by changes in thyroid hormones. However, cold HOWI in combination with moderate normobaric hypoxia did not modify the thermogenic nor the circulating thyroid hormone response. This finding suggests that hypoxia-induced alterations in thyroid hormone concentrations are unlikely to acutely contribute to adaptations resulting from repeated cold-water exposures.

Dual Strategy with Adipose-Derived Stem Cells and l-arginine Recovered Cavernosal Functions in a Rat Model of Radical Prostatectomy.

As standard therapy for prostate cancer, radical prostatectomy causes cavernous nerve (CN) injury and increases fibrosis and hypoxia-induced penile structural alterations. This study aimed to determine the potential beneficial effects of adipose-derived stem cells (ADSCs) and l-arginine alone or in combination on the penile erection in a rat model of erectile dysfunction caused by bilateral cavernous nerve transection (CNT). Male rats (n = 35) were randomized into five groups: Sham-operated; CNT (4-weeks); CNT plus ADSCs (1 × 106 cells by intracavernosal injection); CNT plus l-arginine (4 weeks, 10 mg/kg/day, oral); and ADSCs combined with l-arginine in CNT. In vivo erectile responses and in vitro relaxant responses were measured. Western blot and immunohistochemistry analyses were used to determine the expression and localization of endothelial nitric oxide synthase, neuronal nitric oxide synthase, transforming growth factor-beta 1, hypoxia-inducible factor-1 alpha (HIF-1α), and apoptosis markers (Bax and Bcl-2). The ratio of smooth muscle to collagen and nerve regeneration were calculated using Masson's trichrome and nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase staining. The combined treatment restored diminished erectile responses, endothelium-dependent acetylcholine, and electrical field stimulation-induced relaxation of the corpus cavernosum in rats with CNT, whereas either monotherapy produced only partial improvements. All treatment regimens restored increases in the protein expression of HIF-1 and Bax in rats with CNT. The decrease in smooth muscle mass and NADPH-diaphorase-positive nerve fibers was partially ameliorated by monotherapy, whereas combined therapy led to recovery. These findings indicate that combined treatment with ADSCs and l-arginine may restore erectile function in rats with CNT by inhibiting hypoxia-induced neurotoxicity and preserving endothelium function and smooth muscle content.

Modified Biejia Jianwan decoction restrains PD-L1-mediated immune evasion through the HIF-1α/STAT3/NF-κB signaling pathway

Ethnopharmacological relevanceModified Biejia Jianwan (M-BJJW), a Traditional Chinese Medicine (TCM) decoction, has exhibited great potential in treating hepatocellular carcinoma (HCC). However, its underlying functional mechanism still remains unknown. Aim of the studyThe study aimed to explore the anti-hepatocarcinogenic effects of M-BJJW, specifically its influence on PD-L1-mediated immune evasion in hypoxic conditions, and elucidate the related molecular mechanisms in HCC. Materials and methodsTo investigate the therapeutic efficacy and mechanisms underlying M-BJJW's effects on HCC, we employed a diethylnitrosamine (DEN)-induced rat model maintained for 120 days. Following model establishment, flow cytometry was utilized to assess the distribution of immune cell populations in peripheral blood, spleens, and tumor tissues after M-BJJW administration. Simultaneously, enzyme-linked immunosorbent assays (ELISA) were conducted to analyze cytokine profiles in serum samples. Immunohistochemistry was employed to determine the expression levels of crucial proteins within tumor tissues. Furthermore, HCC cells exposed to CoCl2 underwent Western blot analysis to validate the expression levels of HIF-1α, PD-L1, STAT3, and nuclear factor kappa B (NF-κB) p65. The modulatory effects of STAT3 and NF-κB p65 were investigated using specific inhibitors and activators in wild-type cell lines. High-performance liquid chromatography coupled with mass spectrometry (HPLC/MS) was utilized to identify the chemical constituents present in M-BJJW-medicated serum. The immunomodulatory properties and the anti-tumor activities of M-BJJW were evaluated by co-culturing with peripheral blood mononuclear cells (PBMC) and the CCK-8 assay. Additionally, we assessed M-BJJW's impact on hypoxia-induced alterations in HCC cell lines using immunofluorescence and Western blot assessments. ResultsM-BJJW exhibited substantial therapeutic advantages by effectively alleviating pathological deterioration within the HCC microenvironment. In the DEN-induced rat model, M-BJJW administration notably reduced tumor growth. Flow cytometry analyses revealed an increased proportion of Cytotoxic T lymphocytes (CTLs) accompanied by a simultaneous decrease in regulatory T cells (Tregs). ELISA data supported a marked decrease in pro-inflammatory cytokines, including interleukin-6 (IL-6), interleukin-10 (IL-10), and tumor necrosis factor α (TNF-α). Immunohistochemistry confirmed the suppressive effect of M-BJJW on the expression of HIF-1α and PD-L1. Notably, western blotting unveiled the role of HIF-1α in regulating PD-L1 expression via the STAT3 and NF-κB signaling pathways in HCC cell lines, which was validated using activators and inhibitors of STAT3 and NF-κB. The CCK-8 assay and co-culture techniques demonstrated the anti-tumor activity of M-BJJW. Immunofluorescence and western blotting further confirmed that M-BJJW-containing serum dose-dependently inhibited HIF-1α, PD-L1, p-STAT3, and p-p65 in hypoxic HCC cell lines. ConclusionsM-BJJW demonstrates significant therapeutic potential against HCC by influencing the hypoxic microenvironment, thereby regulating the immunosuppressive milieu. Specifically, M-BJJW modulates the HIF-1α/STAT3/NF-κB signaling pathway, leading to reduced PD-L1 expression and an elevated ratio of cytotoxic T lymphocytes (CTLs), while concurrently decreasing T regulatory cells (Tregs) and immunosuppressive factors. These synergistic effects aid in countering PD-L1-mediated immune evasion, presenting compelling pharmacological evidence supporting the clinical application of M-BJJW as a therapeutic approach for HCC.

Chronic hypoxia-induced alterations of the right ventricular myocardium are not aggravated by alimentary obesity in the mouse

Background and aimsObesity is a risk factor of cardiopulmonary disorders including left and right ventricular dysfunction and pulmonary hypertension (PH), and PH is associated with right ventricular (RV) hypertrophy and failure. Here, we tested the hypothesis that alterations of the RV capillary network under PH induced by chronic hypoxia are aggravated by alimentary obesity, thereby representing a predisposition for subsequent RV dysfunction. Methods and resultsMale, 6-week-old C57BL/6N mice were assigned to one of the following groups: control diet (CD), CD/hypoxia (CD-Hyp), high-fat diet (HFD), HFD/hypoxia (HFD-Hyp). Mice were fed CD or HFD for 30 weeks, CD-Hyp and HFD-Hyp mice were exposed to normobaric hypoxia (13 % O2) during the last 3 weeks of the experiments. Hearts were prepared for light and electron microscopy and right atria and RVs were analyzed by design-based stereology. HFD and hypoxia independently increased RV and cardiomyocyte volume. These changes were further enhanced in HFD-Hyp. The ratio between RV and body weights was similar in CD and HFD but enhanced in both hypoxia groups to a similar extent. The total length of capillaries was elevated in proportion with the RV hypertrophy, thus the area of myocardium supplied by an average capillary was similar in all groups. Similarly, the thickness of the capillary endothelium was not altered by HFD or hypoxia. ConclusionIn conclusion, in experimental PH capillaries of the RV myocardium showed similar adaptations in lean and obese mice. Thus, under chronic hypoxic conditions, obesity had no adverse effect on the capillarization of the right ventricle.

Tumor microenvironment-induced tumor cell plasticity: relationship with hypoxic stress and impact on tumor resistance.

The role of tumor interaction with stromal components during carcinogenesis is crucial for the design of efficient cancer treatment approaches. It is widely admitted that tumor hypoxic stress is associated with tumor aggressiveness and thus impacts susceptibility and resistance to different types of treatments. Notable biological processes that hypoxia functions in include its regulation of tumor heterogeneity and plasticity. While hypoxia has been reported as a major player in tumor survival and dissemination regulation, the significance of hypoxia inducible factors in cancer stem cell development remains poorly understood. Several reports indicate that the emergence of cancer stem cells in addition to their phenotype and function within a hypoxic tumor microenvironment impacts cancer progression. In this respect, evidence showed that cancer stem cells are key elements of intratumoral heterogeneity and more importantly are responsible for tumor relapse and escape to treatments. This paper briefly reviews our current knowledge of the interaction between tumor hypoxic stress and its role in stemness acquisition and maintenance. Our review extensively covers the influence of hypoxia on the formation and maintenance of cancer stem cells and discusses the potential of targeting hypoxia-induced alterations in the expression and function of the so far known stem cell markers in cancer therapy approaches. We believe that a better and integrated understanding of the effect of hypoxia on stemness during carcinogenesis might lead to new strategies for exploiting hypoxia-associated pathways and their targeting in the clinical setting in order to overcome resistance mechanisms. More importantly, at the present time, efforts are oriented towards the design of innovative therapeutical approaches that specifically target cancer stem cells.

Comparative Tandem Mass Tag-Based Quantitative Proteomics Analysis of Liver Against Chronic Hypoxia: Molecular Insights Into Metabolism in Rats.

Xu, Jin, Shenhan Gao, Mingyuan Xin, Wenjie Chen, Kaikun Wang, Wenjing Liu, Xinzong Yan, Sinan Peng, and Yanming Ren. Comparative tandem mass tag-based quantitative proteomics analysis of liver against chronic hypoxia: molecular insights into metabolism in rats. High Alt Med Biol. 24:49-58, 2023. Objective: Using a metabolomic approach, we uncovered key regulators in metabolism from tandem mass tag (TMT)-based proteomic analysis in animals chronically exposed to hypoxia. Methods: Sixteen Sprague-Dawley rats (n = 8 per group) were exposed to chronic normoxia or hypoxia (380 mmHg corresponding to a simulated altitude of 5,500 m) for 35 consecutive days. Hypoxia-induced alterations in metabolic pathways were analyzed from TMT-based proteomic analysis, complemented by western blot validation of key regulators. Results: We profiled biochemical parameters and serum lipids, found that serum alanine aminotransferase and blood glucose were not significantly changed due to chronic hypoxia. However, serum triglycerides, total cholesterol, high-density lipoprotein, and low-density lipoprotein (LDL) were significantly affected by chronic hypoxia. And the levels of LDL nearly doubled (p < 0.05) after hypoxia exposure for 35 days. Through Kyoto Encyclopedia of Genes and Genomes classification, we found several metabolic pathways were enriched, including lipid metabolism, cofactor and vitamin metabolism, amino acids metabolism, carbohydrate metabolism, and energy metabolism. To explore the potential functions of proteins in metabolic pathways that become a coordinated shift under chronic hypoxic conditions, Gene Ontology and pathway analysis were carried out on differentially expressed proteins. As the co-expression network shown in Figure, we identified the most significant differentially expressed proteins after chronic hypoxic changes in the livers of rats. Furthermore, we validated the gene expression profiles at the protein level using western blot. Results of western blot were in accordance with our quantitative polymerase chain reaction findings. The levels of fatty acid synthase and aquaporin 1 were significantly downregulated after 35 days and the levels of ATP citrate lyase, 2'-5'-oligoadenylate synthetase 1A, aldehyde dehydrogenase 2, and Ras-related protein Rap-1A were significantly upregulated after 35 days. Conclusions: Although this study cannot completely account for all the molecular mechanisms in rats, we provide a good analysis of protein expression and profiling of rats under chronic hypoxia conditions.

Roles of hypoxia in tumor progression and novel strategies for cancer treatment

The metabolic process of normal cells in general and of cancer cells in particular requires an important molecule—oxygen. In tumors, the oxygen level tends to decrease gradually from the outer layers to the central core, leading to a condition termed ``hypoxia.'' Changes in the oxygen level modify the signaling pathways and metabolic activities of cancer cells. Basically, tumor development is divided into three stages: initiation, promotion, and progression. Among them, the effects of hypoxia are most evident during tumor progression. In this review, we summarize previous findings on the mechanisms underlying hypoxia-induced alterations in the expression of genes and proteins associated with hypoxia-inducible factors (HIFs), which play a central role in the development of malignancy in many types of cancer. We also present the latest evidence on HIF-targeted cancer treatment that yields positive outcomes in vitro and in vivo.

Hypoxia-Induced Scleral HIF-2α Upregulation Contributes to Rises in MMP-2 Expression and Myopia Development in Mice.

PurposeScleral hypoxia is a key factor that induces hypoxia-inducible factor-1α (HIF-1α) upregulation, and this response contributes to myopia progression. Currently, we aim to determine if the different HIF subtypes, including HIF-1α and HIF-2α, mediate hypoxia-induced myopia development through promoting scleral MMP-2 expression and collagen degradation.MethodsOur study included: (1) time-course of scleral HIF-2α, MMP-2, and COL1α1 expression during form-deprivation myopia (FDM) development was determined in C57BL/6J mice. (2) The effect of silencing either HIF-1Α or HIF-2A on hypoxia-induced alterations in MMP-2 expression was analyzed in cultured human scleral fibroblasts (HSFs) under a hypoxic condition (i.e. 1% oxygen). (3) To knock-down either HIF-1α or HIF-2α expression in the sclera, we performed Sub-Tenon's capsule injection of an adeno-associated virus (AAV)8-packaged Cre overexpression vector (AAV8-Cre) in HIF-1αfl/fl or HIF-2αfl/fl mice. HIF-1α, HIF-2α, MMP-2, and COL1α1 expression were analyzed by Western blot or quantitative real-time PCR (qRT-PCR). In addition, the effects of scleral HIF-2α knock-down on normal refractive development and FDM development were evaluated.ResultsThe time-dependent increases in scleral HIF-2α mimicked the HIF-1α expression profiles as we previously described. Hypoxia significantly promoted MMP-2 expression in HSFs, and this upregulation was solely alleviated by HIF-2A rather than HIF-1A silencing. Scleral HIF-2α knockdown significantly inhibited form-deprivation (FD)-induced MMP-2 upregulation and declines in COL1α1 accumulation and myopia development. Although scleral HIF-1α knockdown also significantly suppressed FD-induced declines in COL1α1 accumulation, it did not abrogate scleral MMP-2 upregulation.ConclusionsHIF-2α rather than HIF-1α induces myopia development through upregulating MMP-2 and promoting collagen degradation in the sclera.

The Effect of Hypoxia-Induced Exosomes on Anti-Tumor Immunity and Its Implication for Immunotherapy

Hypoxia is a critical feature of solid tumors and is considered to be a key factor in promoting tumorigenesis and progression. Beyond inducing metabolic reprogramming of tumor cells to adapt to the hypoxia tumor microenvironment (TME), hypoxia can also promote tumor growth by affecting the secretion of exosomes. Exosomes are nano-sized (30-150 nm in diameter) extracellular vesicles that can carry numerous substances including lipids, proteins, nucleic acids, and metabolites. Notably, hypoxia-induced exosomes alterations not only exist in tumor cells, but also in various TME cells including stromal cells and immune cells. Besides promoting tumor invasion, angiogenesis, and drug resistance, the secretion of these altered exosomes has recently been found to negatively regulate anti-tumor immune responses. In this review, we focus on the hypoxia-induced changes in exosome secretion and found it can contributes to immune evasion and cancer progression by recruiting protumor immune cells into TME, as well as inhibiting antitumor immune cells. Next, we also describe the recent advances of exosomes in immunotherapy and future direction. In conclusion, ongoing discoveries in this field have brought new insights into hypoxia exosome-led immunosuppression, enabling the development of exosome-based therapeutics and elucidating their potential in immunotherapy.

Alterations of RNA Modification in Mouse Germ Cell-2 Spermatids Under Hypoxic Stress.

Hypoxia is a known stress factor in mammals and has been shown to potentially impair male fertility, which manifests as spermatogenic dysfunction and decreased semen quality. Studies have shown that RNA modifications, the novel post-transcriptional regulators, are involved in spermatogenesis, and hypoxia-induced alterations in RNA modification in testes and sperm cells may be associated with impaired spermatogenesis in mice. However, the molecular mechanisms via which RNA modifications influence spermatogenesis under hypoxic stress conditions are unclear. In this study, we generated a mouse Germ Cell-2 spermatid (GC-2spd) hypoxia model by culturing cells in a 1% O2 incubator for 48 h or treating them with CoCl2 for 24 h. The hypoxia treatment significantly inhibited proliferation and induced apoptosis in GC-2spd cells. The RNA modification signatures of total RNAs (2 types) and differentially sized RNA fragments (7 types of approximately 80 nt-sized tRNAs; 9 types of 17–50 nt-sized sncRNAs) were altered, and tRNA stability was partially affected. Moreover, the expression profiles of sncRNAs, such as microRNAs, tsRNAs, rsRNAs, and ysRNAs, were significantly regulated, and this might be related to the alterations in RNA modification and subsequent transcriptomic changes. We comprehensively analyzed alterations in RNA modification signatures in total RNAs, tRNAs (approximately 80 nt), and small RNAs (17–50 nt) as well as the expression profiles of sncRNAs and transcriptomes in hypoxia-treated GC-2spd cells; our data suggested that RNA modifications may be involved in cellular responses under hypoxic stress conditions and could provide a basis for a better understanding of the molecular mechanisms underlying male infertility.

Transcriptome sequencing reveals altered ciliogenesis under hypoxia in nasal epithelial cells from chronic rhinosinusitis with nasal polyps.

BackgroundHypoxia is considered a key factor in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the specific mechanism driving polypogenesis under hypoxic conditions is unclear. This study aimed to explore hypoxia‐induced alterations in the transcriptome of human nasal epithelial cells (HNECs) in vitro.MethodsHNECs derived from the tissue of patients with CRSwNP were established as air–liquid interface (ALI) cultures. Confluent cultures were kept submerged or treated with cobalt chloride (CoCl2) to induce hypoxia. Transcriptome analysis was used to identify key mRNAs involved in this process. Real‐time PCR (RT–PCR), Western blotting, and immunofluorescence were used to observe the effects of hypoxia on ciliogenesis.ResultsNumerous genes, biological processes and pathways were altered under submerged culture conditions or after CoCl2 treatment. Analysis of the results under both hypoxic conditions revealed that the transcriptional program responsible for ciliogenesis was significantly impaired. Downregulation of cilia‐related genes and inhibition of ciliated cell differentiation under hypoxia were confirmed by RT–PCR, Western blot and immunofluorescence analyses.ConclusionHypoxia impairs ciliogenesis and ciliary function in HNECs, which might play a role in the pathogenesis of CRSwNP.

Molecular Mechanisms Involved in Hypoxia-Induced Alterations in Bone Remodeling.

Bone is crucial for the support of muscles and the protection of vital organs, and as a reservoir of calcium and phosphorus. Bone is one of the most metabolically active tissues and is continuously renewed to adapt to the changes required for healthy functioning. To maintain normal cellular and physiological bone functions sufficient oxygen is required, as evidence has shown that hypoxia may influence bone health. In this scenario, this review aimed to analyze the molecular mechanisms involved in hypoxia-induced bone remodeling alterations and their possible clinical consequences. Hypoxia has been associated with reduced bone formation and reduced osteoblast matrix mineralization due to the hypoxia environment inhibiting osteoblast differentiation. A hypoxic environment is involved with increased osteoclastogenesis and increased bone resorptive capacity of the osteoclasts. Clinical studies, although with contradictory results, have shown that hypoxia can modify bone remodeling.

Hypoxia-induced alteration of RNA modifications in the mouse testis and sperm†.

Hypobaric hypoxia as an extreme environment in a plateau may have deleterious effects on human health. Studies have indicated that rush entry into a plateau may reduce male fertility and manifest in decreased sperm counts and weakened sperm motility. RNA modifications are sensitive to environmental changes and have recently emerged as novel post-transcriptional regulators in male spermatogenesis and intergenerational epigenetic inheritance. In the present study, we generated a mouse hypoxia model simulating the environment of 5500m in altitude for 35days, which led to compromised spermatogenesis, decreased sperm counts, and an increased sperm deformation rate. Using this hypoxia model, we further applied our recently developed high-throughput RNA modification quantification platform based on liquid chromatography with tandem mass spectrometry, which exhibited the capacity to simultaneously examine 25 types of RNA modifications. Our results revealed an altered sperm RNA modifications signature in the testis (6 types) and mature sperm (11 types) under the hypoxia model, with 4 types showing overlap (Am, Gm, m7G, and m22G). Our data first drew the signature of RNA modification profiles and comprehensively analyzed the alteration of RNA modification levels in mouse testis and sperm under a mouse hypoxia model. These data may be highly related to human conditions under a similar hypoxia environment.

Exploratory Metabolomic Analysis Based on Reversed-Phase Liquid Chromatography-Mass Spectrometry to Study an In Vitro Model of Hypoxia-Induced Metabolic Alterations in HK-2 Cells.

Oxygen deficiency in cells, tissues, and organs can not only prevent the proper development of biological functions but it can also lead to several diseases and disorders. In this sense, the kidney deserves special attention since hypoxia can be considered an important factor in the pathophysiology of both acute kidney injury and chronic kidney disease. To provide better knowledge to unveil the molecular mechanisms involved, new studies are necessary. In this sense, this work aims to study, for the first time, an in vitro model of hypoxia-induced metabolic alterations in human proximal tubular HK-2 cells because renal proximal tubules are particularly susceptible to hypoxia. Different groups of cells, cultivated under control and hypoxia conditions at 0.5, 5, 24, and 48 h, were investigated using untargeted metabolomic approaches based on reversed-phase liquid chromatography–mass spectrometry. Both intracellular and extracellular fluids were studied to obtain a large metabolite coverage. On the other hand, multivariate and univariate analyses were carried out to find the differences among the cell groups and to select the most relevant variables. The molecular features identified as affected metabolites were mainly amino acids and Amadori compounds. Insights about their biological relevance are also provided.

Cancer and COVID-19: A proposed mechanism with therapeutic interventions.

3135 Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a novel betacoronavirus that causes the respiratory illness coronavirus disease 2019 (COVID-19). COVID-19 ranges in severity from an asymptomatic viral infection to life-threatening cases of pneumonia, acute respiratory distress syndrome (ARDS), multi-organ damage and sepsis. Cancer patients are at an increased risk of severe SARS-CoV-2 infection due to their immunocompromised status. We propose a mechanism by which SARS-CoV-2 infection causes multiple organ damage through IL-6-mediated inflammation and hypoxia-induced cellular metabolic alterations leading to cell death. Hypoxia is also induced by malignancy due to alterations in metabolism, resulting in greater IL-6 secretion. Methods: To highlight the possible effect of active cancer on the likelihood of hypoxia in COVID-19, we analyzed the correlation between cancer status and the severity of COVID-19 from the COVID-19 and Cancer Consortium data registry. For cancer status, we looked at progressive cancer and remission of cancer only -- those being the two extremes of presence and absence of uncontrolled cancer. Similar to prior studies, the severity of COVID-19 was used as an indication of hypoxia. Results: We observed a 24% positive deviation between expected and actual number of patients with actively progressing cancer who had hypoxic COVID-19 (moderate to severe), and a 26.9% negative deviation between expected and actual number of patients with active cancer who had no hypoxia with COVID-19 (p&lt;0.0001). Conversely, for patients with cancer in remission, there was only a +5.8% and -5.1% deviation between expected and actual number of patients who did not have hypoxia and who had hypoxia, respectively. Conclusions: These results suggest that in the presence of poorly controlled malignancy, there is an increased likelihood of hypoxia in patients with COVID-19, thereby exacerbating downstream cytokine release syndrome and contributing to prolonged systemic inflammatory injury. Appreciating this pathway, future therapies can be developed to target the pathogenesis of both diseases and prevent progression, as seen with mesenchymal stem cells, which demonstrated a 91% overall survival and 100% survival in patients younger than 85 years old at one month after a single treatment.[Table: see text]

243 Adverse relationships between sleep apnea, white matter integrity and perfusion is attenuated in more physically fit older adults

Abstract Introduction White matter (WM) integrity declines with age and is sensitive to vascular risk modifiers, such as exercise. Sleep apnea is believed to contribute to cerebral white matter change via intermittent hypoxia-induced alterations to cerebral blood flow resulting in cerebrovascular shearing. Existing literature highlights the relationships between poor sleep and numerous adverse health outcomes, including risk for cardiovascular disease and dementia. Conversely, exercise seems to have a positive effect on both brain structure and function. Here we examine a potential interaction between sleep apnea severity and cardiorespiratory fitness (characterized by a gender-specific Non-Exercise CardioRespiratory Fitness Measure, NECRFM) as predictors of MRI measures of brain WM integrity and cerebral blood flow (CBF) in a sample of non-demented older adult participants of the Wisconsin Sleep Cohort (WSC). Methods Cross-sectional linear models using data from a subset of 124 WSC participants (50% female; mean age[range]=67.6 [49.6, 85.3]) examined the relationship between sleep apnea severity (apnea-hypopnea index, AHI) and cardiorespiratory fitness in predicting MRI-assessed total WM and lesion volumes, WM hyperintensities (WMHs; a marker of small vessel disease in the brain) and Arterial Spin Labeling (ASL) CBF, controlling for age, sex, BMI, education, and hypertension. Results Greater sleep apnea severity was associated more strongly with both total lesion and WMH loads in less fit compared to more fit persons (p’s&amp;lt;0.05) in the absence of significant differences in total WM volume. Regional perfusion revealed higher CBF in the angular gyrus, middle frontal cortex, and superior frontal gyrus and lower CBF in the anterior cingulate gyrus and the hippocampus of more fit compared to less fit persons (p’s&amp;lt; 0.05), in the absence of differences in mean global perfusion. Conclusion Overall, our results suggest that better general fitness may attenuate negative brain health outcomes related to poor sleep. We highlight an important relationship between brain health and modifiable behavioral factors, namely sleep and fitness, that have the potential to help maintain or improve brain integrity with age. Support (if any) This work was supported by United States National Institutes of Health grants R01AG062167, R01AG058680, R01HL62252, 1R01AG036838 and 1UL1RR025011.

Temperature Regulation during Cold Water Immersion is Modified by Normobaric Hypoxia

Purpose Indigenous diving populations and recreational breath-hold divers often develop hypoxia while diving in cold water. Hypoxia may delay the onset and reduce magnitude of shivering during cold exposure. It is unclear if these hypoxia-induced alterations in the control of shivering reduce total energy expenditure, a function of both shivering and non-shivering thermogenesis, and/or modify the ability to maintain core temperature during cold water immersion. Therefore, this study tested the hypothesis that normobaric hypoxia decreases total energy expenditure and results in a greater decrease in core temperature during one hour of head out cold water immersion. Methods In a randomized crossover design, 6 healthy adults (27 ± 2 y, 1 woman) completed one hour of head out cold (22°C) water immersion breathing either normobaric normoxia (FiO2 = 0.21) or normobaric hypoxia (FiO2 = 0.13). Data were collected for 10 minutes prior to water immersion (baseline) and during water immersion. Energy expenditure was estimated from oxygen consumption (V̇O2) and respiratory exchange ratio (RER) measured via indirect calorimetry. Arterial oxyhemoglobin saturation (SpO2) was estimated using pulse oximetry on the forehead. Rectal temperature was used to estimate core temperature. Brown adipose tissue activation was estimated by measuring bilateral supraclavicular skin temperature. In a subset of subjects (n = 2) skin temperature was measured bilaterally on the back over the trapezius muscle, to confirm the unique profile of changes in supraclavicular skin temperature. Data during cold water immersion were compared relative to the last two-minutes of baseline and integrated throughout water immersion (60 minutes). Data are presented as mean ± SD. Results During water immersion, SpO2 was lower in hypoxia (90 ± 3%) compared to normoxia (98 ± 2%, P < 0.01). Baseline rectal temperature was not different between hypoxia (37.3 ± 0.2°C) and normoxia (37.4 ± 0.2°C, P = 0.52). At the end of water immersion, rectal temperature in hypoxia (36.6 ± 0.4°C) was lower than in normoxia (36.9 ± 0.3°C, P < 0.01). No differences in the total increase above baseline during water immersion were observed in V̇O2 (Hypoxia: 28.3 ± 7.2L; Normoxia: 29.5 ± 6.8 L, P = 0.74) or energy expenditure (Hypoxia: 191 ± 69 KJ·min; Normoxia: 143 ± 81 KJ·min, P = 0.32) between trials. Supraclavicular skin temperature increased with water immersion (P < 0.01), while back skin temperature decreased (P = 0.02). No differences were observed in the total increase from baseline in supraclavicular skin temperature (Hypoxia: 66.6 ± 30.3°C·min; Normoxia: 66.1 ± 35.3°C·min, P = 0.54) or total decrease from baseline in back skin temperature (Hypoxia: -42.3 ± 30.8°C·min; Normoxia: -56.6 ± 7.9 °C·min, P = 0.14). Conclusions These preliminary findings support that, compared to normoxia, normobaric hypoxia promotes a greater reduction in core temperature during one hour of head out cold water immersion. The mechanism(s) underlying this observation remains unclear as no differences in energy expenditure and brown adipose tissue activation were observed, but alterations in cutaneous blood flow cannot be excluded.

Genetic deletion of p66shc and/or cyclophilin D results in decreased pulmonary vascular tone.

AimsThe pulmonary vascular tone and hypoxia-induced alterations of the pulmonary vasculature may be regulated by the mitochondrial membrane permeability transition pore (mPTP) that controls mitochondrial calcium load and apoptosis. We thus investigated, if the mitochondrial proteins p66shc and cyclophilin D (CypD) that regulate mPTP opening affect the pulmonary vascular tone.Methods and resultsMice deficient for p66shc (p66shc−/−), CypD (CypD−/−), or both proteins (p66shc/CypD−/−) exhibited decreased pulmonary vascular resistance (PVR) compared to wild-type mice determined in isolated lungs and in vivo. In contrast, systemic arterial pressure was only lower in CypD−/− mice. As cardiac function and pulmonary vascular remodelling did not differ between genotypes, we determined alterations of vascular contractility in isolated lungs and calcium handling in pulmonary arterial smooth muscle cells (PASMC) as underlying reason for decreased PVR. Potassium chloride (KCl)-induced pulmonary vasoconstriction and KCl-induced cytosolic calcium increase determined by Fura-2 were attenuated in all gene-deficient mice. In contrast, KCl-induced mitochondrial calcium increase determined by the genetically encoded Mito-Car-GECO and calcium retention capacity were increased only in CypD−/− and p66shc/CypD−/− mitochondria indicating that decreased mPTP opening affected KCl-induced intracellular calcium peaks in these cells. All mouse strains showed a similar pulmonary vascular response to chronic hypoxia, while acute hypoxic pulmonary vasoconstriction was decreased in gene-deficient mice indicating that CypD and p66shc regulate vascular contractility but not remodelling.ConclusionsWe conclude that p66shc specifically regulates the pulmonary vascular tone, while CypD also affects systemic pressure. However, only CypD acts via regulation of mPTP opening and mitochondrial calcium regulation.

Placental hypoxia-induced alterations in vascular function, morphology, and endothelial barrier integrity.

Preeclampsia (PE) is a pregnancy-related disorder characterized by hypertension and proteinuria that affects 3-10% of all pregnancies. Although its pathophysiology remains obscure, placental hypoxia-induced oxidative stress and alterations in vascular function, morphology, and endothelial barrier integrity are considered to play a key role in the development of preeclampsia. In this study, placental villous explants of noncomplicated placentae and BeWo cells were subjected to hypoxia. The effect of placental hypoxic-conditioned medium (HCM) on intraluminal-induced contraction and endothelial barrier integrity in chorionic arteries was investigated using pressure myography. The impact of BeWo cell HCM on endothelial cell viability, reactive oxygen species formation and inflammation was also determined. Alterations in arterial morphology and contractile responsiveness to the thromboxane A2 analog (U46619) after exposure to placental HCM were examined immunohistochemically and by wire myography, respectively. Intraluminal administration of placental HCM induced vasoconstriction and increased the endothelial permeability for KCl, which was concentration-dependently prevented by quercetin. Placental and BeWo cell HCMs decreased endothelial cell viability, increased the production of reactive oxygen species and enhanced the secretion of IL-6 and IL-8. The cross-sectional area of the arterial media was increased upon exposure to placental HCM, which was associated with increased vascular proliferation and contractile responsiveness to U46619, and all of these effects were prevented by the antioxidants quercetin and RRR-α-tocopherol. This study is the first to comprehensively demonstrate the link between factors secreted by placental cells in response to hypoxia and vascular abnormalities and paves the way for new diagnostic approaches and therapies to better protect the maternal vasculature during and after a preeclampsia-complicated pregnancy.