Hypoxia Group Research Articles

Ssc-miR-141 Attenuates Hypoxia-Induced Alveolar Type II Epithelial Cell Injury in Tibetan Pigs by Targeting PDCD4.

The Tibetan pig is an endemic economic animal in the plateau region of China, and has a unique adaptation mechanism to the plateau hypoxic environment. Research into microRNAs (miRNAs) involved in the mechanism underlying hypoxia adaptation of Tibetan pig is very limited. Therefore, we isolated alveolar type II epithelial (ATII) cells from the lungs of the Tibetan pig, cultured them in normoxia/hypoxia (21% O2; 2% O2) for 48 h, and performed high-throughput sequencing analysis. We identified a hypoxic stress-related ssc-miR-141 and predicted its target genes. The target genes of ssc-miR-141 were mainly enriched in mitogen-activated protein kinase (MAPK), autophagy-animal, and Ras signaling pathways. Further, we confirmed that PDCD4 may serve as the target gene of ssc-miR-141. Real-time quantitative polymerase chain reaction (RT-qPCR) analysis was performed to confirm the expression levels of ssc-miR-141 and PDCD4, and a dual-luciferase gene reporter system was used to verify the targeted linkage of ssc-miR-141 to PDCD4. The results showed that the expression level of ssc-miR-141 in the hypoxia group was higher than that in the normoxia group, while the expression level of PDCD4 tended to show the opposite trend and significantly decreased under hypoxia. These findings suggest that ssc-miR-141 is associated with hypoxia adaptation and provide a new insight into the role of miRNAs from ATII cells of Tibetan pig in hypoxia adaptation.

Preventive effects of antenatal CDP-choline in a rat model of neonatal hyperoxia-induced lung injury.

Antenatal steroid administration to pregnant women at risk of prematurity provides pulmonary maturation in infants, while it has limited effects on incidence of bronchopulmonary dysplasia (BPD), the clinical expression of hyperoxia-induced lung injury (HILI). Cytidine-5'-diphosphate choline (CDP-choline) was shown to alleviate HILI when administered to newborn rats. Therefore, we investigated effects of maternal administration of CDP-choline, alone or in combination with betamethasone, on lung maturation in neonatal rats subjected to HILI immediately after birth. Pregnant rats were randomly assigned to one of the four treatments: saline (1 mL/kg), CDP-choline (300 mg/kg), betamethasone (0.4 mg/kg), or CDP-choline plus betamethasone (combination therapy). From postnatal day 1 to 11, pups born to mothers in the same treatment group were pooled and randomly assigned to either normoxia or hyperoxia group. Biochemical an d histopathological effects of CDP-choline on neonatal lung tissue were evaluated. Antenatal CDP-choline treatment increased levels of phosphatidylcholine and total lung phospholipids, decreased apoptosis, and improved alveolarization. The outcomes were further improved with combination therapy compared to the administration of CDP-choline or betamethasone alone. These results demonstrate that antenatal CDP-choline treatment provides benefit in experimental HILI either alone or more intensively when administered along with a steroid, suggesting a possible utility for CDP-choline against BPD.

Contrast Enhanced Ultrasonography of Kidney in Chronic Intermittent Hypoxia Rat Model.

The objective of our study was to assess the ability of contrast-enhanced ultrasound (CEUS) in evaluating renal microperfusion in an animal model. Twenty Sprague-Dawley rats were subdivided into two groups: the normal and chronic intermittent hypoxia (CIH) groups. In the CIH model, 10 Sprague-Dawley rats were exposed to CIH for 8 weeks to mimic obstructive sleep apnea (OSA). The CEUS parameters of the renal cortex and medulla were obtained and compared between groups. The pathological changes of the kidney tissues were examined by histological staining such as hematoxylin and eosin (H&E) and Masson's trichrome. CIH caused morphological damage to kidneys. In the cortex, the peak intensity (PI) (P=.009) was significantly lower and time to peak (Ttop) (P=.019) was significantly prolonged in the CIH group compared with the controls. The area under ascending curve (WiAUC) in the medulla and cortex were both significantly lower in the CIH group than those in the control group (P both <.05). CEUS parameters (including PI and WiAUC of the cortex and WiAUC of the medulla) were negatively correlated with serum creatinine (P all <.05). In the medulla, the area under descending curve (WoAUC) was positively correlated with serum creatinine (P=.027), PI was negatively correlated with uric acid (P=.034). CEUS parameters (including Ttop, PI, WoAUC, and WiAUC) reflect renal microvascular changes in CIH. CEUS could be a safe and accurate imaging method to assess renal microvascular damage in CIH rats.

High Keratin Secretion of T47D Cell under Hypoxic Condition

BACKGROUND: Hypoxia adaptation in cancer cells is mediated by hypoxia inducible factor (HIF)-1 that induces the expression of various proteins. Up to date, the analysis of T47D breast cancer cells-secreted protein is still limited. The aim of this study was to compare the protein profile secreted by T47D breast cancer cells under hypoxic and to normoxic conditions and identify the proteins as candidate for hypoxia marker proteins in T47D breast cancer cells.METHODS: T47D breast cancer cells were cultured under standard conditions. Cells were subcultured in normoxic and hypoxic conditions. The normoxic group was incubated with 20% oxygen and the hypoxic groups were incubated in a hypoxic chamber with 0.5% and 5% oxygen for 6, 24, and 48 hours in serum free medium. Proteins in the culture media were isolated and precipitated. Protein concentrations released by the cells were then measured by bicinchoninic assay (BCA). Protein bands were visualized by the sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) method. The bands that had differences between the hypoxic and normoxic groups were further analyzed by liquid chromatography-mass spectrophotometer (LC-MS).RESULTS: Hypoxic groups showed higher secretory protein than normoxic group. Protein bands were found in the 0.5% hypoxic group with a size of 50-75 kDa. Secretory proteins identified by LC-MS were keratin 1, 2, 9, and 10.CONCLUSION: The T47D cell line under 0.5% hypoxic treatment showed higher secretory proteins that identified as keratin 1, 2, 9, and 10.KEYWORDS: hypoxia, secretory protein, liquid chromatography-mass spectrophotometer

IL-17D affects the chemokines and chemokine receptors of intestinal epithelial cells under hyperoxia.

IL-17D is a new member of the IL-17 family. Currently, it is believed that IL-17D can directly act on immune cells or may indirectly modulate immune responses by regulating cytokine expression. Herein, we hypothesized that IL-17D regulates the expression of chemokines in intestinal epithelial cells, in turn modulating the immune response within intestinal mucosa under hyperoxia. To explore this notion, newborn rats were divided into a hyperoxia group (85% O2) and control group (21% O2). Small intestinal tissues were obtained from neonatal rats at 3, 7, 10, and 14days. Similarly, intestinal epithelial cells were treated by hyperoxia (85% O2) as the hyperoxia group or were incubated under normal oxygen (21% O2) as the control group. Finally, intestinal epithelial cells subjected to hyperoxia were treated with recombinant IL-17D and IL-17D antibodies for 24, 48, and 72h. Immunohistochemistry, western blot, and reverse transcription-quantitative polymerase chain reaction were used to detect the expression levels of chemokines and chemokine receptors in intestinal tissues of newborn rats and intestinal epithelial cells. We found that hyperoxia affected chemokine expression both in vivo and in vitro. Under hyperoxia, IL-17D promoted the expression of CCL2, CCL25, CCL28, and CCR9 in intestinal epithelial cells while downregulating CCR2, CCR5, CCL5, and CCL20. Our findings provide a basis for further study on the effects of hyperoxia-induced intestinal inflammation and intestinal injury.

Endurance exercise under short-duration intermittent hypoxia promotes endurance performance via improving muscle metabolic properties in mice.

This study was designed to (1) investigate the effects of acute exercise under intermittent hypoxia on muscle mRNA and protein levels, and (2) clarify the mechanisms by which exercise under intermittent hypoxia improves endurance capacity. Experiment-1: Male mice were subjected to either acute endurance exercise, exercise under hypoxia (14% O2 ), exercise under intermittent hypoxia (Int, three cycles of room air [10min] and 14% O2 [15 min]). At 3h after exercise under intermittent hypoxia, sirtuin-6 mRNA levels and nuclear prolyl hydroxylases-2 protein levels were significantly upregulated in white gastrocnemius muscle in the Int group. Experiment-2: Mice were assigned to sedentary control (Sed), normoxic exercise-trained (ET), hypoxic exercise-trained (HYP) or exercise-trained under intermittent hypoxia (INT) groups. Exercise capacity was significantly greater in the INT group than in the ET and HYP group. Activity levels of citrate synthase were significantly greater in the INT group than in the HYP group in soleus (SOL) and red gastrocnemius muscles. In SOL, nuclear N-terminal PGC1α levels were considerably increased by the INT training (95% confidence interval [CI]: 1.09-1.79). The INT significantly increased pyruvate dehydrogenase complex activity levels in left ventricle (LV). Monocarboxylate transporter-4 protein levels were significantly increased after the INT training in LV. Capillary-to-fiber ratio values were significantly increased in SOL and were substantially increased in LV (CI: 1.10-1.22) after the INT training. These results suggest that exercise training under intermittent hypoxia represents a beneficial strategy for increasing endurance performance via improving metabolic properties and capillary profiles in several hind-leg muscles and the heart.

Hypoxia Increases the Proliferative and Metastatic Ability of Canine Mammary Tumor Cells via Up-regulation of TSG-6.

HIF1α-induced hypoxia is a major characteristic of solid tumors that plays an important role in cancer growth, metastasis, and chronic inflammation. Tumor necrosis factor (TNF) stimulated gene (TSG)-6 is a strong regulator of anti-inflammatory pathways, but its role in cancer cells remains unclear. We hypothesized that hypoxia up-regulates TSG-6, thereby increasing the metastatic and growth potential of cancer cells. Primary and metastatic canine mammary gland tumor (MGT) cell lines (CIPp and CIPm), were transfected with TSG-6 specific siRNA and treated with cobalt chloride (CoCl2) for 48 h to chemically induce a hypoxia environment. The expression of hypoxia-inducible factor-1-alpha (HIF1α) was evaluated by RT-qPCR and western blot analysis. The metastatic ability of cancer cells and cell cycle distribution were assessed with extracellular matrix invasion assays and flow cytometry. HIF1α up-regulation, induced by CoCl2, was significantly inhibited in the TSG-6-knockdown group in both canine MGT cell lines. The change in the expression levels of HIF1α corresponded to the change of invading cells in the TSG-6-knockdown group. TSG-6-knockdown in the hypoxia group showed decreased proliferation, associated with G2/M phase arrest. HIF1α expression in hypoxic condition is regulated by TSG-6 expression in canine MGT. TSG-6-knockdown causes down-regulation of HIF1α, thereby reducing the metastatic and proliferative abilities of cancer cells. TSG-6 in canine MGT has a potential as a therapeutic target in anti-cancer therapy.

The danger of hyperoxia on the rat kidneys: is tadalafil a real shield?

Continuous oxygen therapy to compensate for decreased oxygen saturation in the blood is a life-saving treatment used in case lung involvement. Excess oxygen delivery was reported to be a common situation, in which about 50% of the patients showed hyperoxemia and 4% in severe hyperoxemia. In this work, we investigated the effects of hyperoxia on the rat kidneys and whether tadalafil has an effect to reduce this damage. Three groups of 8 male rats each weighing 300-350g were formed. The groups were divided into the control group, hyperoxia group, and hyperoxia and tadalafil administered group for 10 days. At the end of the 10th day, blood and kidney samples were taken for biochemical analysis (SOD and NO levels) and histopathological examination. While our findings showed that SOD levels were significantly different among the control and experimental groups and within the experimental groups, no statistical difference was found in terms of NO levels among the groups (Table 1). While the glomerular and tubular injury was higher in the Hyperoxia group and the Hyperoxia + Tadalafil group than in the control group (p < 0.001), as a result of the rate of severe glomerular and tubular injury in the hyperoxia group, was 62.5% and 43.8% and in the group given tadalafil was 43.8% and 31.3%, respectively (Table 2). Exposure to hyperoxia condition causes renal glomerular and tubular damage, and tadalafil does not show a protective effect on this damage according to this study's dose and exposure time.

High-Altitude Hypoxia Exposure Induces Iron Overload and Ferroptosis in Adipose Tissue.

High altitude (HA) has become one of the most challenging environments featuring hypobaric hypoxia, which seriously threatens public health, hence its gradual attraction of public attention over the past decade. The purpose of this study is to investigate the effect of HA hypoxia on iron levels, redox state, inflammation, and ferroptosis in adipose tissue. Here, 40 mice were randomly divided into two groups: the sea-level group and HA hypoxia group (altitude of 5000 m, treatment for 4 weeks). Total iron contents, ferrous iron contents, ROS generation, lipid peroxidation, the oxidative enzyme system, proinflammatory factor secretion, and ferroptosis-related biomarkers were examined, respectively. According to the results, HA exposure increases total iron and ferrous iron levels in both WAT and BAT. Meanwhile, ROS release, MDA, 4-HNE elevation, GSH depletion, as well as the decrease in SOD, CAT, and GSH-Px activities further evidenced a phenotype of redox imbalance in adipose tissue during HA exposure. Additionally, the secretion of inflammatory factors was also significantly enhanced in HA mice. Moreover, the remarkably changed expression of ferroptosis-related markers suggested that HA exposure increased ferroptosis sensitivity in adipose tissue. Overall, this study reveals that HA exposure is capable of inducing adipose tissue redox imbalance, inflammatory response, and ferroptosis, driven in part by changes in iron overload, which is expected to provide novel preventive targets for HA-related illness.

Combined transcriptome and proteome analysis of yak PASMCs under hypoxic and normoxic conditions.

Yaks are animals that have lived in plateau environments for generations. Yaks can adapt to the hypoxic plateau environment and also pass this adaptability on to the next generation. The lungs are the most important respiratory organs for mammals to adapt to their environment. Pulmonary artery smooth muscle cells play an important role in vascular remodeling under hypoxia, but the genetic mechanism underpinning the yak's ability to adapt to challenging plateau conditions is still unknown. A tandem mass tag (TMT) proteomics study together with an RNA-seq transcriptome analysis were carried out on pulmonary artery smooth muscle cells (PASMCs) that had been grown for 72 hours in both normoxic (20% O2) and hypoxic (1% O2) environments. RNA and TP (total protein) were collected from the hypoxic and normoxic groups for RNA-seq transcriptome sequencing and TMT marker protein quantification, and RT-qPCR validation was performed. A total of 17,711 genes and 6,859 proteins were identified. Further, 5,969 differentially expressed genes (DEGs) and 531 differentially expressed proteins (DEPs) were identified in the comparison group, including 2,924 and 186 upregulated genes and proteins and 3,045 and 345 down-regulated genes and proteins, respectively. The transcriptomic and proteomic analyses revealed that 109 DEGs and DEPs were highly positively correlated, with 77 genes showing the same expression trend. Nine overlapping genes were identified in the HIF-1 signaling pathway, glycolysis / gluconeogenesis, central carbon metabolism in cancer, PPAR signaling pathway, AMPK signaling pathway, and cholesterol metabolism (PGAM1, PGK1, TPI1, HMOX1, IGF1R, OLR1, SCD, FABP4 and LDLR), suggesting that these differentially expressed genes and protein functional classifications are related to the hypoxia-adaptive pathways. Overall, our study offers abundant data for further analysis of the molecular mechanisms in yak PASMCs and their adaptability to different oxygen concentrations.

ACUTE REPEATED WINGATE STYLE HIIT EXERCISE IN HYPOXIC CONDITIONS DOES NOT ALTER OXIDATIVE STATUS IN UNTRAINED MEN

Both high-intensity interval training and training in hypoxic conditions have gained popularity in recent years due to their cardiorespiratory and metabolic benefits. Recent studies focus on the combined effects of both factors in detail. But there is still a scientific gap in the literature on the effects caused and its magnitude in response to this type of training. Therefore, this study aims to investigate the acute effects of Repeated Wingate Style HIIT applied in hypoxic and normoxic conditions on oxidant and antioxidant indicators of recreationally active men. Sixteen participants were randomly assigned to normoxic or hypoxic groups and then they were completed a wingate style 30s*4rps*4 min (sprint time * repeats * recover between sprints) HIIT on normoxic and hypoxic conditions (2500m, FiO2: 0.130) in the normobaric environment. The normality assumption calculated using a Shapiro-Wilk test to ensure the normal distribution of the quantitative for all data (p &lt; 0.05). To analyze differences in baseline data between groups an Independent Sample t-test was performed. The Two-way analysis of variance was used in repeated measurements to reveal the effects of training under hypoxia and normoxia conditions (time, time × group interactions) oxidant and antioxidants. The activities of blood oxidant and antioxidant did not change significantly after training in the hypoxic and normoxic group. As a result, repeated Wingate style HIIT applied in hypoxic and normoxic conditions, did not change both MDA (p=0.79), which is an indicator of oxidant stress, and SOD (p=0.46), CAT (p=0.26), and GSHPX (p=0.17), which are general indicators of antioxidant defense.

Malondialdehyde and carbonyl levels in skeletal muscle tissues after intermittent hypobaric hypoxia exposures

Background: Hypobaric hypoxia is a state of decreased oxygen pressure at high altitudes that can lead to hypoxia and oxidative stress as a result. Skeletal muscle is one of the important organs that can be affected by oxidative stress and cause contractile dysfunction.&#x0D; Objective: This study aimed to evaluate the impact of intermittent hypobaric hypoxia on oxidative stress markers in rat skeletal muscle, by measuring malondialdehyde (MDA) and carbonyl levels.&#x0D; Methods: Twenty-five Wistar rats were allocated into five groups, including one control group and four hypoxic groups (I-IV). The hypoxic groups were exposed to an altitude of 25,000 feet for 5 minutes using hypobaric chamber in once (I), twice (II), three (III), and four (IV) times, with a 7-day interval period between exposures. The control group remained in normobaric conditions throughout the study. MDA levels were measured by thiobarbituric acid (TBA) test, while carbonyl levels were measured using 2,4-dinitrophenylhydrazine (DNPH) reagent.&#x0D; Results: The MDA level was significantly increased in group I compared to the control group (p=0.008). There were decreasing MDA levels in groups II, III, and IV compared to group I. The carbonyl level was significantly higher in group I than the control group (p=0.000), with an even higher level observed in group II. Although the carbonyl levels tended to decrease in groups III and IV, they still remained higher than those of the control group.&#x0D; Conclusion: Exposure to hypobaric hypoxia leads to an increase in MDA and carbonyl levels in the skeletal muscles, indicating an elevation of oxidative stress levels. However, the subsequent intermittent hypobaric hypoxia exposure resulted in a reduction in these levels, implying that skeletal muscles may adapt to hypoxic conditions.

An Emerging Prognosis Prediction Model for Multiple Myeloma: Hypoxia-Immune Related Microenvironmental Gene Signature

Background: Multiple myeloma (MM) is a hematologic malignancy characterized by clonal proliferation of malignant plasma cells. Hypoxia and the immune microenvironment play vital roles in the carcinogenicity and evolution of MM. In this study, we attempted to construct a microenvironmental gene marker associated with hypoxia immunity for effective prognostic prediction and risk stratification. Methods: MM-related datasets (GSE136324, GSE47552 and GSE136337) were downloaded from Gene Expression Omnibus (GEO). A Kaplan-Meier (K-M) survival curve was applied to excavate survival differences among different hypoxia clusters, and the hypoxia state was divided into high hypoxia and low hypoxia groups according to the prognosis. The expression data algorithm was used to estimate the immune score of each MM patient. Based on the optimal truncation immune score value, MM patients were divided into high and low immune score subgroups. The R packages were applied to identify the risk differentially expressed genes (DEGs) and protective DEGs. Univariate Cox and Least Absolute Shrinkage and Selection Operator (LASSO) regression analyses were applied to identify prognosis-related genes. Receiver Operating Characteristic curves and K-M survival curves were applied to verify the validity and agility of the prognostic signature. The cell type identification by estimating relative subsets of RNA transcripts algorithm was applied to analyze immune cell infiltration. Quantitative real-time PCR was used to test the signature in vitro. Cell proliferation was measured by a CCK-8 assay. The levels of apoptotic rate were analyzed by the flow cytometer. Cell migration and invasion ability were estimated by Transwell membranes and Matrigel. NOD/SCID mice were divided into four groups: normoxia control (CTL), normoxia shDDIT4 (CTL+shDDIT4), intermittent hypoxia control (IH), and IH shDDIT4 (IH+shDDIT4). CTL had an oxygen concentration of 21% while IH had a nadir of 6%~8%. Results: A total of 867 MM samples were classified according to hypoxia status and immune score and were classified into Hypoxia.low/Immune.high, Hypoxia.high/Immune, lowand mixed groups. K-M survival analysis showed patients in the Hypoxia.low/Immune.high group had a better prognosis than others. Overlapping the three groups of risk DEGs and protective DEGs. There were 472 protective DEGs and 205 risk DEGs with supporting evidence from hypoxia, immune and combing hypoxia/ immune groups. In GSE47522, 2633 DEGs were screened between normal and MM. 81 key hypoxia-immune-related genes were overlapped by the Venn diagram between MM and normal DEGs, protective DEGs and risk DEGs. Using GSE136324 as a training cohort, a univariate Cox regression analysis was performed on 81 key genes. We identified 44 hypoxia-immune-related prognostic DEGs statistically related to the overall survival time of MM patients. Then, an 8-gene signature (including CHRDL1, DDIT4, DNTT, FAM133A, MYB, PRR15, QTRT1, and ZNF275) was identified using the LASSO regression algorithm. MM patients were divided into high-risk and low-risk groups based on a threshold of the median risk score in the prognostic value of the 8-gene signature. K-M curves suggested that the MM patients in the low-risk group showed a statistically longer overall survival than those in the high-risk group. The AUC of 1 year in the training cohort was greater than 0.7. Univariate and multivariate Cox regression analyses showed that the risk score could be an independent prognostic risk factor. Moreover, we revealed that the proportions of 17 types of immune cells were significantly different between the two risk groups, . In the high-risk group, PD-L1 expression levels were higher than in the low-risk group. Finally, we found knockout of DDIT4 inhibited tumor formation in vitro under hypoxia. Further, the survival rate of the IH+shDDIT4 group was higher than that of the IH group. Moreover, both tumor volume and tumor weight in the IH+shDDIT4 group were reduced. Conclusions: We established a hypoxia-immune related prognostic signature. It could predict the prognosis of MM well and was related to the tumor microenvironment of MM. The downregulation of DDIT4 inhibited tumor formation and development in vitro and vivo under hypoxia. Meanwhile, our results suggest that the immune checkpoint inhibitors, PD-L1 inhibitors, may be helpful in the treatment of high-risk patients.

Photoinduced Carbene for Effective Photodynamic Therapy Against Hypoxic Cancer Cells

Photoinduced Carbene for Effective Photodynamic Therapy Against Hypoxic Cancer Cells

Comparison of hypoxia-induced pulmonary hypertension rat models caused by different hypoxia protocols

Background and aim: Pulmonary hypertension (PH) is a serious and even fatal disorder with limited treatment strategies. The hypoxia-induced pulmonary hypertension (HPH) rat model is commonly used in this field. While the HPH rat model has strong predictability and repeatability, the model is a chronic model, making it time-consuming, costly, and complicated and limiting the progress of the experiments. Currently, there is no uniform international standard for the HPH model. Our study aimed to find a relatively effective and efficient HPH modeling protocol. Methods: We established HPH rat models with different total hypoxia periods and different daily hypoxia times, and assessed different hypoxia modeling modes in multiple dimensions, such as haemodynamics, right ventricular (RV) hypertrophy, pulmonary arterial remodeling, muscularization, inflammation, and collagen deposition. Results: Longer daily hypoxia time resulted in higher mean pulmonary arterial pressure (mPAP)/right ventricular systolic pressure (RVSP) and more obvious RV hypertrophy, as well as more severe pulmonary arterial remodeling and muscularization, regardless of the total period of hypoxia (3- or 4-week). Moreover, pulmonary perivascular macrophages and collagen deposition showed daily hypoxia time-dependent increases, both in 3- and 4-week hypoxia groups. Conclusion: Our findings showed that the 3-week continuous hypoxia mode was a relatively efficient way to reduce the time needed to induce significant disease phenotypes, which offered methodological evidence for future studies in building HPH models.

The Neuroprotective Effects of Administration of Methylprednisolone in Cardiopulmonary Resuscitation in Experimental Cardiac Arrest Model.

Although advances in diagnosis and treatment of cardiac arrest (CA) could improve neurological outcomes after cardiopulmonary resuscitation (CPR), survival rate and neurological outcome after CA and CPR remain poor. This study aimed to investigate the effect of epinephrine (EP) alone and EP in combination with methylprednisolone (MP) (EP + MP) on some the apoptotic and anti-apoptotic genes and proteins levels expression of the cerebral cortex as well as neuronal death in a CA rat model. Forty-five male Sprague Dawley rats were randomly divided into three groups including the hypoxic CA + EP, hypoxic CA + EP + MP, and sham groups using a simple randomization procedure. In both hypoxic CA groups, CA was induced by asphyxia and immediately after confirmation of CA, the treatment strategies including chest compression or cardiac massage simultaneously with ventilation, and administration of EP alone (20mg/kg, every 3min) and EP (20mg/kg, every 3min) + 30 (mg/kg) of MP were done. The sham group only received anesthetic drugs without CA. Some neurological outcomes were investigated using histopathological, immunohistochemical, molecular, and terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick-end labeling (TUNEL) assays at 5 and 48h post-CPR. The data obtained showed the highest up-regulation of apoptotic genes and proteins expression, the lowest expression of anti-apoptotic gene and protein expression, the most DNA fragmentation and histopathological changes belonged to the EP group on 48h post-CPR. While mild and intermediate histopathological changes, DNA fragmentation and apoptotic activity was detected in theEP alone and EP + MP groups at 5h and 48h post-CPR, respectively. As a novel finding, the present study showed that EP + MP protects neurons from death provoked/induced by hypoxia and reperfusion injury in an experimental model of CA through up and down-regulation of pro- (caspases 3 and 8) and anti-apoptotic (BCL2) molecules, respectively.

Caffeine reduces oxidative stress to protect against hyperoxia-induced lung injury via the adenosine A2A receptor/cAMP/PKA/Src/ERK1/2/p38MAPK pathway

ABSTRACT Objectives: Caffeine has been shown to reduce the incidence of bronchopulmonary dysplasia (BPD). To investigate the protective mechanism of caffeine in a hyperoxia-based cell model of BPD in vitro. Methods: Type II alveolar epithelial cells (AECs II) were isolated and randomly divided into 6 groups: the normal, hyperoxia, caffeine (50 μM caffeine), antagonist (5 μM ZM241385), agonist (5 μM CGS21680), and DMSO groups. Transfection with siRNA against adenosine A2A receptor (siA2AR) was performed in AECs II. Results: Caffeine alone or in combination with adenosine A2A receptor (A2AR) antagonist inhibited apoptosis, promoted proliferation and reduced oxidative stress (OS). The cyclic adenosine monophosphate (cAMP), protein kinase A (PKA) mRNA, A2AR mRNA and the protein levels of A2AR, phospho-Src, phospho-ERK1/2, phospho-P38 and cleaved caspase-3 were decreased in the caffeine and antagonist groups compared with that in the hyperoxia group. However, the effects of caffeine above were weakened by the A2AR agonist. Knockdown of A2AR showed similar results to caffeine. Discussion: Caffeine can reduce apoptosis, promote proliferation, and alleviate OS in hyperoxia-induced AECs II injury by inhibiting the A2AR/cAMP/PKA/Src/ERK1/2/p38MAPK signaling pathway. A2AR may serve as a promising therapeutic target for BPD in prematurity.

Iron metabolism disorder regulated by BMP signaling in hypoxic pulmonary hypertension

Backgrounds and aimsUnexplained iron deficiency is associated with poorer survival in patients with pulmonary hypertension (PH). Bone morphogenetic protein (BMP) signaling and BMP protein type II receptor (BMPR2) expression are important in the pathogenesis of PH. BMP6 in hepatocytes is a central transcriptional regulator of the iron hormone hepcidin that controls systemic iron balance. This study aimed to investigate the effects of BMP signaling on iron metabolism and its implication in hypoxia-induced PH. Methods and resultsPH was induced in Sprague–Dawley Rats under hypoxia for 4 weeks. Compared with the control group, right ventricular systolic pressure and right ventricle hypertrophy index were both markedly increased, and serum iron level was significantly decreased with iron metabolic disorder in the hypoxia group. In cultured human pulmonary artery endothelial cells (HPAECs), hypoxia increased oxidative stress and apoptosis, which were reversed by supplementation with Fe agent. Meanwhile, iron chelator deferoxamine triggered oxidative stress and apoptosis in HPAECs, and treatment with antioxidant alleviated iron-deficiency-induced apoptosis by reducing reactive oxygen species production. Expression of hepcidin, BMP6 and hypoxia-inducible factor (HIF)-1α were significantly upregulated, while expression of BMPR2 was downregulated in hepatocytes in the hypoxia group, both in vivo and in vitro. Expression of hepcidin and HIF-1α were significantly increased by BMP6, while pretreatment with siRNA-BMPR2 augmented the enhanced expression of hepcidin and HIF-1α induced by BMP6. ConclusionsIron deficiency promoted oxidative stress and apoptosis in HPAECs in hypoxia-induced PH, and enhanced expression of hepcidin regulated by BMP6/BMPR2 signaling may contribute to iron metabolic disorder.

Effectiveness, implementation, and monitoring variables of intermittent hypoxic bicycle training in patients recovered from COVID-19: The AEROBICOVID study.

Hypoxic exposure is safely associated with exercise for many pathological conditions, providing additional effects on health outcomes. COVID-19 is a new disease, so the physiological repercussions caused by exercise in affected patients and the safety of exposure to hypoxia in these conditions are still unknown. Due to the effects of the disease on the respiratory system and following the sequence of AEROBICOVID research work, this study aimed to evaluate the effectiveness, tolerance and acute safety of 24 bicycle training sessions performed under intermittent hypoxic conditions through analysis of peripheral oxyhemoglobin saturation (SpO2), heart rate (HR), rate of perceived exertion (RPE), blood lactate concentration ([La-]) and symptoms of acute mountain sickness in patients recovered from COVID-19. Participants were allocated to three training groups: the normoxia group (GN) remained in normoxia (inspired fraction of O2 (FiO2) of ∼20.9%, a city with 526m altitude) for the entire session; the recovery hypoxia group (GHR) was exposed to hypoxia (FiO2 ∼13.5%, corresponding to 3,000m altitude) all the time except during the effort; the hypoxia group (GH) trained in hypoxia (FiO2 ∼13.5%) throughout the session. The altitude simulation effectively reduced SpO2 mean with significant differences between groups GN, GHR, and GH, being 96.9(1.6), 95.1(3.1), and 87.7(6.5), respectively. Additionally, the proposed exercise and hypoxic stimulus was well-tolerated, since 93% of participants showed no or moderate acute mountain sickness symptoms; maintained nearly 80% of sets at target heart rate; and most frequently reporting session intensity as an RPE of "3" (moderate). The internal load calculation, analyzed through training impulse (TRIMP), calculated using HR [TRIMPHR = HR * training volume (min)] and RPE [TRIMPRPE = RPE * training volume (min)], showed no significant difference between groups. The current strategy effectively promoted the altitude simulation and monitoring variables, being well-tolerated and safely acute exposure, as the low Lake Louise scores and the stable HR, SpO2, and RPE values showed during the sessions.

Resveratrol attenuates cardiac function impairment in plateau hypobaric hypoxia rats

Objective: To study the protective effects of resveratrol (RSV) on cardiac function in rats with high altitude hypobaric hypoxia and its mechanisms. Methods: Thirty-six rats were randomly divided into control group, hypobaric hypoxia group (HH) and hypobaric hypoxia + RSV group (HH+RSV) according to the random number, 12 rats in each group. Rats in the HH and HH+RSV groups were subjected to chronic long-term high altitude hypobaric hypoxia intervention for 8 weeks in a hypobaric chamber at a simulated altitude of 6 000 m for 20 h / d. The rats of HH + RSV were fed with RSV at a dose of 400 mg/(kg·d). The rats were tested once a week for body weight and twice a week for food intake. Before execution, the rats were tested by blood cell analyzer for routine blood parameters and echocardiogram for cardiac function parameters in each group. The routine blood indexes of each group were measured by blood cell analyzer, the cardiac function indexes of each group were measured by echocardiography, myocardial hypertrophy was evaluated by HE staining, myocardial tissue reactive oxygen levels were evaluated by dihydroethidium (DHE) staining. Oxidative stress was evaluated by serum and myocardial tissue total antioxidant capacity (T-AOC), superoxide dismutase activity (SOD) and malondialdehyde (MDA) content. Results: Compared with the C group, the body mass and food intake of rats were decreased significantly (P＜0.05) in HH group, while compared with the C group, RSV had no significant effects on the body mass and food intake of rats in the HH+RSV group (P＞0.05). Compared with the C group, the levels of erythrocytes and hemoglobin of rats in the HH group were increased significantly (P＜0.05), while the platelet concentration was decreased significantly(P＜0.05); compared with the HH group, the erythrocyte and hemoglobin levels were decreased significantly (P＜0.05) and platelet concentration was increased significantly(P＜0.05) in rats of the HH+RSV group. Compared with the C group, the cardiac coefficient, myocardial fiber diameter and thickness were significantly increased in the HH group (P＜0.05); compared with the HH group, the cardiac coefficient and myocardial fiber thickness were significantly decreased in the HH+RSV group (P＜0.05). Echocardiographic analysis showed a significant increase in ventricular wall thickness (P＜0.05) and a significant decrease in ejection fraction and cardiac output (P＜0.05) in the HH group compared with the C group, and a significant decrease in ventricular wall thickness and a significant improvement in cardiac function (P＜0.05) in the HH+RSV group compared with the HH group. The results of DHE staining showed that myocardial tissue reactive oxygen levels were increased significantly in the HH group compared with the C group (P＜0.05); myocardial tissue reactive oxygen levels were significantly restored in the HH+RSV group compared with the HH group (P＜0.05). The oxidative/antioxidant results showed that the serum and myocardial T-AOC and SOD activities were decreased significantly (P＜0.05) and the MDA level was increased significantly (P＜0.05) in the HH group compared with the C group; the serum and myocardial T-AOC and SOD activities were increased significantly (P＜0.05) and the MDA level was decreased significantly(P＜0.05) in the HH+RSV group compared with the HH group. Conclusion: Long-term plateau hypobaric hypoxia exposure leads to myocardial hypertrophy and reduced cardiac function in rats. Resveratrol intervention significantly improves myocardial hypertrophy and cardiac function in rats caused by altitude hypobaric hypoxia exposure, which is closely related to reducing of reactive oxygen species and improving myocardial oxidative stress levels.