Search Results (472)

Aged skeletal muscle satellite cells (MuSCs) exhibit impaired autophagy-related activity, reduced proliferative capacity, and compromised myogenic differentiation, which collectively contribute to defective muscle regeneration during aging. However, whether hypoxia-driven modulation of autophagy-related activity can improve aged MuSC function and the underlying molecular mechanisms remain incompletely understood. In this study, aged MuSCs were divided into three groups: normoxia, hypoxia, and hypoxia combined with an autophagy inhibitor. Aged MuSCs exhibited a decreased LC3B-II/LC3B-I ratio and Beclin-1 expression, together with elevated p62 levels, indicating altered autophagy-related activity. Hypoxic culture was associated with enhanced autophagy-related activity in aged MuSCs, accompanied by HIF-1α stabilization, BNIP3 upregulation, and reduced p62 accumulation. Functionally, hypoxia significantly promoted the proliferation and myogenic differentiation of aged MuSCs. Pharmacological inhibition of autophagy using 3-methyladenine, as well as BNIP3 suppression, markedly attenuated these hypoxia-induced functional improvements. Collectively, these findings suggest that hypoxia is associated with improved proliferative and myogenic capacities of aged MuSCs, potentially involving autophagy-related activity regulated by the HIF-1α/BNIP3 pathway. This study provides insight into the relationship between hypoxic signaling and autophagy in aged MuSCs and may inform future strategies aimed at improving muscle regeneration during aging. Full article

(1) Background: The naked mole-rat (Heterocephalus glaber) survives hypoxia–reoxygenation stresses by utilizing metabolic rate depression, achieved in part by downregulating nonessential genes and processes to conserve endogenous cellular resources and prevent buildup of toxic waste byproducts. Tight molecular control of protein degradation (specifically the ubiquitin–proteasome system) is a potent regulatory tool for maintaining muscle integrity during hypoxia, but how this system is regulated in the heart of hypoxia-tolerant species is poorly understood. (2) Methods: The protein expression levels of cullin-RING E3 ligases (specifically CRL4 architecture), deubiquitinating enzymes, and proteasomal activity were assayed in cardiac tissues from H. glaber exposed to 24 h of normoxia or hypoxia in vivo. (3) Results: Overall, the protein expression of E3 ligases decreased, whereas expression of deubiquitinating enzymes increased during hypoxia, all of which play roles in themes of oxidative stress, heightened DNA damage repair, and the HIF-1-VHL-NFκB axis. Proteasomal activity was elevated during hypoxia, which conceivably links to the oxidative stress theory of aging and longevity of H. glaber. (4) Conclusions: Taken together, our results expand current research into protein degradation and extreme environmental stress responses, with a specific focus on cardiac mechanisms related to oxidative stress resistance along the hypoxia-longevity axis. Full article

Aerobic exercise with eicosapentaenoic acid (EPA) may enhance cognition via cerebrovascular pathways. We tested whether mild hyperbaric oxygen (HBO; 1.41 atmospheres absolute [ATA], approximately 30% O₂) adds to gains in cognitive processing capacity (throughput) versus normobaric normoxia (1.0 ATA, approximately 21% [20.9%] O₂). Healthy young adults (n = 16) performed cycling exercise at 60–70% VO_2peak for 60 min, twice weekly, for 4 weeks per environment with a 1-week washout; EPA (2170 mg·day⁻¹) was taken during each 4-week training phase (total 8 weeks) and was paused during the washout. An EPA-only control (n = 8) was included for supplementary analysis. The primary outcome was throughput (correct·min⁻¹; T1–T4); secondary outcomes were interference indices (I1: stroop interference, I2: reverse-stroop interference). Effects were estimated using linear mixed models [environment, time, environment × time; AR(1), REML] and Hedges’ g_av; accuracy used generalized estimating equations. Throughput improved mainly with time (T1–T2 p < 0.001; T4 p = 0.017; T3 p = 0.055), with no environment or interaction effects. I1/I2 showed no significant change, and one task exhibited an accuracy ceiling. Under safe, feasible conditions (≤1.41 ATA), aerobic exercise improved processing capacity (throughput) independently of environmental oxygenation level. The absence of detectable additive effects should be interpreted cautiously under conservative settings. Full article

Organoids consisting of primary human cells, i.e., astrocytes, pericytes, and endothelial cells, form a functional blood–brain barrier (BBB) in vitro. The ability of FITC-dextran (70 kDa), calcium phosphate nanoparticles (100 nm), Escherichia coli bacteria (2 µm), and MS2 coliphages (27 nm, a model for viruses) to penetrate the BBB under normoxic and hypoxic conditions (2.5% oxygen) for up to 12 days was assessed by fluorescence microscopy and confocal laser scanning microscopy. All agents were fluorescently labeled to trace them inside the organoids. Under normoxia, FITC-dextran, calcium phosphate nanoparticles, E. coli bacteria and MS2 coliphages did not penetrate the BBB. However, oxygen deficiency (hypoxia) triggered the penetration of the BBB by FITC-dextran and E. coli cells. This was underscored by a strong hypoxic center inside the organoids that developed in the presence of E. coli bacteria. Full article

Neonatal piglet mortality remains a major challenge in hyper-prolific sow herds, particularly under tropical conditions where low ambient oxygen (18–21%) may exacerbate hypoxia during prolonged farrowing. This study evaluated whether restoring normoxia (21% O₂) immediately after birth improved piglet colostrum intake, blood glucose levels, and survival to 3 d. A total of 1837 piglets from 95 sows were weighed at birth and assigned by litter to exposure to either a normoxic chamber (FiO₂ = 0.21) or ambient-air control (FiO₂ = 0.16–0.18) for 15 min post-partum. Piglet colostrum intake, blood glucose content, and survival to 24-h and 3 d were analyzed using mixed-effects models. Compared with controls, oxygen-supplemented piglets showed higher postnatal oxygen saturation (94.2 ± 3.6 vs. 88.1 ± 3.5%), greater colostrum intake (348 ± 263 vs. 320 ± 233 g), higher blood glucose (97.7 ± 13.0 vs. 93.8 ± 13.1 mg/dL), and increased 3-day survival (86.1% vs. 80.8%; p < 0.01). The effect was most pronounced in piglets < 1.0 kg and >1.3 kg, reflecting improved recovery from transient hypoxia. Mean weaning weight increased by 0.3 kg, indicating sustained benefits in early growth. These findings demonstrate that short-term normoxic oxygen supplementation is a practical, cost-effective intervention that enhances growth, metabolic stability, and survival in neonatal piglets under tropical commercial farm conditions. Full article

Five novel platinum(II) complexes C1–C5 were synthesized in the reaction of the appropriate substituted 4-nitroisothiazoles with K₂PtCl₄ and characterized with elemental analysis, ESI MS spectrometry, NMR spectroscopy, and IR spectroscopy. Also, a new methyl 3-methyl-4-nitroisothiazole-5-carboxylate (L2) was obtained. The structures of trans complex C4 and the new isothiazole derivative L2 were additionally confirmed by X-ray diffraction (XRD) method. The cytotoxicity of the investigated complexes was examined in vitro on three human cancer cell lines (MCF-7 breast, ES-2 ovarian, and A549 lung adenocarcinomas) in both normoxic and hypoxic conditions. The tested complexes, except for the most polar cisC5, which appeared to be the least active, showed cytotoxic activity comparable to that of the reference cisplatin. cis-complex C1, transC2, and transC3 showed slightly better cytotoxic activity than cisplatin against the MCF-7 cell line. The complexes had the weakest effect on the A549 cell line. No differences in the cytotoxic activity of the complexes were observed between normoxic and hypoxic conditions, except for the A549 cell line, where all the complexes, except for C2, were inactive in hypoxia. However, most complexes, including the reference cisplatin, were equally toxic to healthy BALB/3T3 cells and cancer cells. The trans complex C2 (isomeric to cisC1) showed even greater toxicity to healthy cells than to MCF-7 and A549 cancer cells. Some complexes were tested for stability against glutathione (GSH) solution to gain additional information that may facilitate the explanation of the pharmacological activity of the tested compounds. Additionally, some theoretical calculations on the thermochemistry of the complexation process were performed using quantum density functional theory (DFT), which indicate that complexation should occur through the coordination of the platinum cation by the nitrogen rather than the sulfur atom of the isothiazole ring. Full article

Carbonic anhydrase 3 (CA3) exhibits low enzymatic activity compared to other CA isoforms but contains two surface-exposed cysteine residues that undergo glutathionylation under oxidative stress. Highly expressed in muscle tissue, CA3 has been implicated in cellular protection, particularly through interactions with Bcl2-Associated Athanogene 3 (BAG3), modulating autophagy, while CA3 overexpression decreased hypoxia-induced apoptosis in cardiomyocytes. In this study, we investigated the impact of CA3 overexpression on cellular pathways in HEK293T, MDA-MB-231, and SVCT cells using RNA sequencing and proteomics. Gene Set Enrichment Analysis (GSEA) in HEK293T cells revealed the down-regulation of pathways related to protein synthesis, RNA processing, Roundabout signalling, selenocysteine-metabolism, and suppression of neurodegenerative disease-associated pathways. Human breast epithelial cell lines under normoxia and hypoxia showed down-regulation of similar pathways, although notably, hypoxic conditions also suppressed interferon α/β signalling. Proteomic analysis in HEK293T cells using HaloTag pull-down experiments identified putative novel CA3 binding partners, including heat shock 70 kDa proteins 1 and 8, and ribosomal protein S2 (RPS2). RANBP2 protein was consistently up-regulated after CA3 overexpression, irrespective of the presence of CA3 surface-exposed cysteines and HaloTag orientation. These findings suggest that CA3 modulates key cellular processes beyond its enzymatic role, contributing to stress resilience through pathway-level regulation and protein interactions, potentially impacting autophagy and neurodegenerative disease. Full article

Background: This study explores the therapeutic potential of radiodynamic therapy (RDT), a combination of the photosensitizer 5-aminolevulinic acid (5-ALA) administration and X-ray irradiation, for high-grade glioma (HGG). The research aims to verify the RDT efficacy in both normoxic and hypoxic environments, examine its mechanisms, and assess its impact on the tumor micro-immune environment to address resistance to RDT. Methods: Glioma cell lines U87MG and U251MG were used in experiments in vitro. The cells were divided into four groups with or without 5-ALA and X-ray exposure. Results: Results demonstrated that RDT was effective under normoxia (20% O₂), increasing reactive oxygen species (ROS) production and significantly decreasing U87MG cell viability in a 5-ALA concentration-dependent manner at 2 Gy and 6 Gy. However, under hypoxic conditions (3% O₂) or long-term 3% O₂ exposure, the RDT effect was not significant compared to controls. The study also found that RDT under normoxia influenced immune reaction-related gene expression, while under hypoxia, it primarily affects genes related to epithelial–mesenchymal transition (EMT). Further analysis revealed that RDT reduces the secretion of soluble PD-L1, a marker of immune checkpoint inhibition, in a 20% O₂ environment. Additionally, RDT suppressed the vascular endothelial growth factor (VEGF), an angiogenesis marker, under 3% O₂ conditions. RDT also reduced the secretion of colony-stimulating factor -1 (CSF-1), a differentiation inhibitory marker for macrophages, in a 20% O₂ environment. Conclusion: In conclusion, this study provides evidence that RDT, combining 5-ALA and X-ray irradiation, has potential as a therapeutic strategy for HGG, especially under normoxic conditions. It may also offer benefits under hypoxia, particularly in inhibiting angiogenesis. The study also highlights the importance of understanding the role of oxygen levels in the efficacy of RDT and its potential impact on immune responses, angiogenesis, and macrophage differentiation in the tumor microenvironment. Further research is needed to fully elucidate the underlying mechanisms and optimize RDT for clinical application. Full article

Background: Hypoxia and ageing both involve impaired oxygen delivery, leading to oxidative damage, and endothelial cell (EC) dysfunction. In the presence of chronic hyperglycemia, these effects are amplified, accelerating EC senescence and vascular impairment. Methods: We assessed key mediators of inflammatory signalling and senescence, as well as transcriptional regulators responsive to oxidative stress in ECs exposed to high glucose (30.5 mmol/L) for 72 h under either normoxia (21% O₂) or prolonged (16 h) hypoxia (2% O₂) followed by 2 h of reoxygenation. Results: ECs exposed to high glucose and hypoxia developed a senescent phenotype, as indicated by increased expression of p21 and p16, and elevated β-galactosidase staining. Interestingly, hypoxia-induced senescence did not coincide with the classical senescence-associated secretory phenotype (SASP). Compared to normoxia, ECs exposed to hypoxia, particularly under high-glucose conditions, showed reduced NF-κB-driven proinflammatory secretome (MCP-1, IL-6, IL-8), downregulation of the NF-κB p50 subunit, and simultaneous upregulation of the angiogenic factor VEGF-A with downregulation of YAP-1, a key regulator of cell survival. Notably, we observed a strong upregulation of A20 and TNIP-3, two well-characterized negative regulators of NF-κB signalling. Conclusions: Hypoxia-induced senescence did not trigger a typical inflammatory SASP. Although ECs enter a senescent state, they activate an anti-inflammatory response, suppressing NF-κB signalling and increasing the expression of its inhibitors, A20 and TNIP-3. This may reflect a non-canonical senescence response whose functional significance remains to be determined. Full article

Background: In patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension (summarized as pulmonary vascular disease; PVD), it is unclear whether the brain is protected against acute hypoxia and whether acute pulmonary vascular dilatation by sildenafil would influence cerebral and muscle tissue oxygenation whilst breathing normoxia or hypoxia. Methods: Adult patients with PVD underwent right heart catheterization, while cerebral and muscular tissue oxygenation and tissue hemoglobin index were measured using near-infrared spectroscopy along with arterial and mixed-venous blood gases. Participants underwent a four-stage protocol in which they were blinded to breathing either normoxia (FiO₂ 0.21) or normobaric hypoxia (FiO₂ 0.15), both before and after a single oral dose of sildenafil (50 mg) according to a randomized, cross-over design. Results: In 22 PVD patients (9 women, age 54 ± 14 y) under hypoxia, mean cerebral tissue oxygenation decreased by −2% (95% CI −4 to 0%, p = 0.046), muscular tissue oxygenation by −1% (95% CI −3 to 0%, p = 0.011) and mean arterial partial pressure of oxygen by −2.3 kPa (95% CI −2.7 to −1.8 kPa, p < 0.0001). Sildenafil improved the cerebral tissue hemoglobin index under hypoxia compared to hypoxia without sildenafil by 0.12 (95% CI 0.00 to 0.23, p = 0.049), but not the muscular tissue hemoglobin index. Conclusions: In PVD patients, acute exposure to normobaric hypoxia leads to a reduction in arterial oxygenation as well as cerebral and muscular tissue oxygenation. Sildenafil improves cerebral blood flow but has no effect on arterial, cerebral or muscular oxygenation. Full article

Background: Exposure to hypoxia is widely used to enhance training adaptations, but its acute effects on cardiac function remain unclear. Exercise-induced cardiac fatigue (EICF), defined as transient impairments in left ventricular (LV) systolic and diastolic function, has been reported after endurance exercise. Whether moderate hypoxia influences EICF, particularly in athletes, is unknown. Methods: Twenty-four healthy men participated: 12 endurance-trained cyclists (T) and 12 untrained individuals (UT). Each completed two exhaustive cycling tests under normoxia (FiO₂ = 20.9%) and moderate normobaric hypoxia (FiO₂ = 14.4%; ~3000 m). Echocardiography was performed at rest and immediately post-exercise to assess LV systolic and diastolic function. Results: Exhaustive exercise reduced LV diastolic function in both groups, with no significant condition-related differences. Under normoxia, early peak filling velocity (Mitral E) decreased by 21.2% in UT and 23.2% in T, and under hypoxia, by 16.2% in UT and 14.9% in T. Global longitudinal strain (LV GLS) became less negative after exercise under normoxia (UT: +25.2%, T: +30.6%) and hypoxia (UT: +24.8%, T: +20.3%). Athletes exhibited slightly less post-exercise systolic impairment under hypoxia than normoxia, reflected by the maintenance of a more negative LV GLS (∆GLS: 6.87 ± 2.65% in normoxia vs. 4.55 ± 1.86% in hypoxia, p < 0.05). Conclusions: Moderate normobaric hypoxia (~3000 m) did not exacerbate EICF in either group. Athletes showed slightly less post-exercise systolic impairment under hypoxia. Moderate hypoxia may modify the cardiac response to exhaustive exercise, but studies with larger samples and direct preload assessment are needed. Full article

Background: Carboplatin is a first-line chemotherapy agent for patients with oral squamous cell carcinoma (OSCC), but chemoresistance significantly impacts treatment outcomes. This study evaluated the ability of thymoquinone, a natural metabolite found in food products, to modulate cytotoxicity, ROS, apoptosis, autophagy, and cancer stem cell markers in early- and late-stage OSCC cell models to identify mechanisms of chemoresistance and determine the influence of dietary metabolites on treatment outcomes. Methods: OECM-1 cells were treated with concentrations (1 mM to 1 pM) of thymoquinone, carboplatin, or their combination under normoxic and hypoxic conditions. HIF-1α levels were measured using ELISA, and cytotoxicity was assessed by the MTT assay. ROS, apoptosis, autophagy, and cell surface markers (CD44+, CD133+, CD147+) were evaluated. All experiments were repeated three times, and the data were analyzed using GraphPad Prism. Under hypoxia, HIF-1α increased 12-fold. Results: Carboplatin demonstrated reduced potency (110 μM) and efficacy (40%) compared to normoxia (82 μM, 88%), accompanied by increased apoptosis (75%) and decreased ROS (25%). Thymoquinone was more potent than carboplatin, further reducing ROS (50%), increasing apoptosis (95%), and downregulating autophagy, while the proportion of CD133+ expressing cells increased significantly (75%) in the hypoxic model. For the combined treatment across both models, thymoquinones’ efficacy remained high (>90%). Between models, no further change in any parameter was observed, except for apoptosis induction, which increased to 65% (normoxia) and 50% (hypoxia). Conclusions: Thymoquinones’ superior efficacy under hypoxic conditions demonstrates ROS-independent cytotoxic mechanisms; however, the enrichment of CD133+ cells raises essential questions about long-term therapeutic outcomes and the risks of tumor recurrence. Natural pharmaceutical metabolites can influence the tumor microenvironment, which is highly implicated in cancer therapeutics and cancer adaptation. Full article

Hypoxia is a major global health concern, particularly in premature infants and cancer, where it promotes intracellular calcium accumulation and cell death. The transient receptor potential vanilloid 1 (TRPV1) channel has been implicated in calcium dysregulation and oxidative stress under hypoxic conditions, while estrogen (17β-estradiol, E₂) is known to modulate TRPV1 activity and redox balance. This study aimed to investigate the impact of E₂ on TRPV1 expression, hypoxia-inducible factor-1α (HIF-1α), and calcium signaling in MCF-7 breast cancer cells (ERα-positive) and TRPV1-transfected CHO cells (ERα-negative). Four experimental groups were established: normoxia, E₂, hypoxia, and hypoxia + E₂. Hypoxia was induced by CoCl₂ (200 µM, 24 h), while E₂ treatment was applied at 10 nM for 24 h. Western blot analysis revealed that both TRPV1 and HIF-1α expression were upregulated under hypoxia but significantly reduced by E₂. Fura-2 fluorescence assays revealed that hypoxia increased cytosolic Ca²⁺ levels, whereas E₂ reversed this elevation. Moreover, TRPV1 activation by capsaicin induced marked Ca²⁺ influx under hypoxia, which was attenuated by E₂ treatment. These findings demonstrate that E₂ mitigates hypoxia-induced toxicity by modulating TRPV1-mediated Ca²⁺ signaling and HIF-1α expression, underscoring the protective role of E₂ and identifying TRPV1 as a potential therapeutic target in estrogen-responsive tumors. Full article

Exposure to hypoxia may cause lung injury characterized by hydrostatic pulmonary edema (PE), inflammation and oxidative stress. Norepinephrine (NE) infusion can also induce lung injury with similar pathogenetic characteristics. The main questions of this study were (i) whether NE infusion aggravates hypoxia-induced pulmonary injury; (ii) whether inflammation and oxidative stress deteriorate the hypoxic PE; and (iii) whether PE and inflammation recede after three days of normoxic recovery. Ninety-eight female rats were exposed for 72 h to normoxia or normobaric hypoxia and received infusions with NaCl or NE. Some of these animals were transferred to a three-day normoxic recovery period thereafter. We performed histological and immunohistochemical analyses of the lung, determined protein concentrations in pleural fluid (PF) and bronchoalveolar lavage fluid (BALF), and evaluated hemodynamic parameters. While inflammation and oxidative stress receded after 3 days of normoxic recovery, PE did not resolve. Increased protein concentrations in PF and BALF indicated that capillary stress failure increased even further during the normoxic recovery phase, particularly in animals that had previously received an NE infusion. These results highlight the fact that inflammation does not play a causal role in the development of hypoxic PE. Full article

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumour with limited treatment options and a poor prognosis. Hypoxia, a hallmark of solid tumours, contributes to therapeutic resistance and tumour progression. Gastrin-releasing peptide receptor (GRPR) is known to be overexpressed in SCLC; however, its regulation under hypoxic conditions is not well described. In this study, we demonstrate that hypoxia significantly enhances GRPR expression in SCLC cell lines, COR-L24 and DMS79, as confirmed by Western blot, immunofluorescence, and flow cytometric analysis of binding with fluorescein isothiocyanate–labelled bombesin (BBN-FITC), a known GRPR ligand. To exploit this upregulation, we synthesised a previously discovered butylated neuropeptide antagonist (BU peptide) using a new method of solid-phase peptide synthesis (SPPS) by Boc chemistry and evaluated its therapeutic potential. BU peptide exhibited potent, dose-dependent cytotoxicity in both cell lines, with significantly greater efficacy under hypoxic conditions compared to normoxia. Mechanistic studies revealed that BU peptide inhibits GRP–GRPR-mediated activation of the PI3K/Akt and MAPK/ERK signalling pathways, known to be key regulators of tumour cell survival and proliferation. Moreover, BU peptide induced robust caspase 3/7-mediated apoptosis, especially under hypoxic conditions. These findings suggest that GRPR is a hypoxia-inducible target in SCLC and demonstrate that a synthetically optimised BU peptide antagonist exerts selective efficacy against hypoxic tumour cells, outperforming conventional chemotherapy agents. These findings provide new mechanistic insights into SCLC and suggest translational potential to inform the development of future treatment strategies for this and other hypoxia-driven malignancies. Full article