Hypoxia Inducible Factor Pathway and Physiological Adaptation: A Cell Survival Pathway?

Macrophage and osteosarcoma cell crosstalk is dependent on oxygen tension and 3D culture

Osteosarcoma (OS), the most common form of primary bone cancer in young adults, has had no improvements in clinical outcomes in 50 years. This highlights a critical need to advance mechanistic understanding of OS to further therapeutic discovery, which will only be possible with accurate models of the disease. Compared to traditional monolayer studies and preclinical models, in vitro models that better replicate the three-dimensional (3D) bone marrow microenvironment will facilitate methodical investigations of the events and factors that drive OS progression. Herein, we use fibrin-alginate interpenetrating network (FA IPN) hydrogels to model the hematological bone marrow environment. We interrogated the effects of oxygen tension, 3D culture, and macrophage phenotype on OS behavior and specifically examine the immunomodulatory crosstalk between OS and macrophages. We observe that OS is more sensitive to oxygen tension when cultured in 3D. Specifically, both highly and less metastatic OS exhibit decreased changes in DNA content over time in 3D, but then demonstrate diverging behaviors in heterotypic culture with macrophages. OS response to macrophages differs as a function of metastatic potential, where highly metastatic OS shows increased immunosuppression that varies with oxygen tension but relies on direct coculture conditions. To our knowledge, this is among the first work to report the effects of 3D culture on the interplay between OS and macrophages in a coculture microenvironment. Together, these data introduce FA IPNs as a promising platform for cancer research and emphasize the importance of novel models for the mechanistic study of OS.

L-Arginine and Nitric Oxide in Vascular Regulation-Experimental Findings in the Context of Blood Donation

This narrative review provides an analysis of the role of nitric oxide (NO) and its precursors, particularly L-arginine, in vascular regulation and health, with an emphasis on findings from our experimental research in animal models. NO serves as a critical mediator of vascular function, contributing to vasodilation, the regulation of blood flow, and the prevention of thrombosis. As a primary precursor of NO, L-arginine is essential for maintaining endothelial integrity, modulating mitochondrial function, and reducing oxidative damage. This review synthesises the data and contextualises these findings within the physiological challenges faced by blood donors, such as repeated blood donation and associated oxidative stress. It examines the effects of L-arginine supplementation on mitochondrial respiration, lipid peroxidation, and microsomal oxidation in different conditions, including differences in age, gender, and dietary interventions. The mechanisms by which L-arginine enhances NO production, improves vascular elasticity, and alleviates endothelial dysfunction caused by reduced NO bioavailability are also investigated. By integrating experimental findings with insights from the existing literature, this review provides a perspective on the potential of L-arginine supplementation to address the specific physiological needs of blood donors. It highlights the importance of personalised nutritional approaches in enhancing donor recovery and vascular resilience. In addition, this review assesses the wider implications of L-arginine supplementation in mitigating oxidative stress and preserving vascular function. The interplay between NO bioavailability, dietary factors, and physiological adaptation in blood donors is highlighted, along with the identification of current knowledge gaps and recommendations for future research. By presenting both original experimental evidence and a critical synthesis of the literature, this article highlights the therapeutic potential of NO precursors, particularly L-arginine, in promoting vascular health in the context of blood donation.

Could hypoxic conditioning augment the potential of mesenchymal stromal cell-derived extracellular vesicles as a treatment for type 1 diabetes?

Type1 Diabetes (T1D) is an autoimmune disorder characterised by the loss of pancreatic β-cells. This β cell loss occurs primarily through inflammatory pathways culminating in apoptosis. Mesenchymal stromal cells (MSCs) have been heavily studied for therapeutic applications due to their regenerative, anti-apoptotic, immunomodulatory, and anti-inflammatory properties. The therapeutic effects of MSCs are mediated through cell-to-cell contact, differentiation, and the release of paracrine factors, which include the release of extracellular vesicles (EVs). Culturing MSCs in hypoxia, a low oxygen tension state more analogous to their physiological environment, seems to increase the therapeutic efficacy of MSC cell therapy, enhancing their immunomodulatory, anti-inflammatory, and anti-fibrotic properties. This is also the case with MSC-derived EVs, which show altered properties based on the parent cell preconditioning. In this review, we examine the evidence supporting the potential application of hypoxic preconditioning in strengthening MSC-EVs for treating the inflammatory and apoptotic causes of β cell loss in T1D.

Glial Cell Reprogramming in Ischemic Stroke: A Review of Recent Advancements and Translational Challenges

Ischemic stroke, the second leading cause of death worldwide and the leading cause of long-term disabilities, presents a significant global health challenge, particularly in aging populations where the risk and severity of cerebrovascular events are significantly increased. The aftermath of stroke involves neuronal loss in the infarct core and reactive astrocyte proliferation, disrupting the neurovascular unit, especially in aged brains. Restoring the balance between neurons and non-neuronal cells within the perilesional area is crucial for post-stroke recovery. The aged post-stroke brain mounts a fulminant proliferative astroglial response, leading to gliotic scarring that prevents neural regeneration. While countless therapeutic techniques have been attempted for decades with limited success, alternative strategies aim to transform inhibitory gliotic tissue into an environment conducive to neuronal regeneration and axonal growth through genetic conversion of astrocytes into neurons. This concept gained momentum following discoveries that in vivo direct lineage reprogramming in the adult mammalian brain is a feasible strategy for reprogramming non-neuronal cells into neurons, circumventing the need for cell transplantation. Recent advancements in glial cell reprogramming, including transcription factor-based methods with factors like NeuroD1, Ascl1, and Neurogenin2, as well as small molecule-induced reprogramming and chemical induction, show promise in converting glial cells into functional neurons. These approaches leverage the brain's intrinsic plasticity for neuronal replacement and circuit restoration. However, applying these genetic conversion therapies in the aged, post-stroke brain faces significant challenges, such as the hostile inflammatory environment and compromised regenerative capacity. There is a critical need for safe and efficient delivery methods, including viral and non-viral vectors, to ensure targeted and sustained expression of reprogramming factors. Moreover, addressing the translational gap between preclinical successes and clinical applications is essential, emphasizing the necessity for robust stroke models that replicate human pathophysiology. Ethical considerations and biosafety concerns are critically evaluated, particularly regarding the long-term effects and potential risks of genetic reprogramming. By integrating recent research findings, this comprehensive review provides an in-depth understanding of the current landscape and future prospects of genetic conversion therapy for ischemic stroke rehabilitation, highlighting the potential to enhance personalized stroke management and regenerative strategies through innovative approaches.

Chemoresistance in Pancreatic Cancer: The Role of Adipose-Derived Mesenchymal Stem Cells and Key Resistance Genes

Drug resistance is a significant challenge in pancreatic ductal adenocarcinoma (PDAC), where stromal elements such as adipose-derived mesenchymal stem cells (ASCs) contribute to a chemoresistant tumor microenvironment (TME). This study explored the effects of oxaliplatin (OXP) and 5-fluorouracil (5-FU) on PDAC cells (Capan-1) and ASCs to investigate the mechanisms of chemoresistance. While OXP and 5-FU reduced Capan-1 viability in a dose- and time-dependent manner, ASCs demonstrated high resistance, maintaining > 90% viability even at cytotoxic doses. Transcriptomic analyses revealed OXP-induced transcriptional reprogramming in ASCs, with over 7000 differentially expressed genes, highlighting the pathways related to DNA damage response, cell cycle regulation, and stress-related signaling. In contrast, 5-FU elicited limited transcriptional changes, affecting only 192 genes. Cytokine proteome profiling revealed that OXP-treated ASCs significantly influenced the tumor microenvironment by promoting immune evasion (via IL-4, GM-CSF, IP-10, and GROα) and driving extracellular matrix remodeling (through EMMPRIN and DPPIV). In contrast, 5-FU induced comparatively weaker effects, primarily limited to hypoxia-related pathways. Although OXP reduced angiogenic factors, it paradoxically activated pro-survival pathways, thereby enhancing ASC-mediated tumor support. These findings underscore ASCs as modulators of chemoresistance via secretome alterations and stress adaptation. Therefore, future strategies should prioritize the precise targeting of tumor cells while also focusing on the development of personalized treatments to achieve durable therapeutic responses in PDAC.

Hypoxia-inducible Factor-1α Pathway in Cerebral Ischemia: From Molecular Mechanisms to Therapeutic Targets

INTRODUCTION

Ischemic injury to the brain can result in a variety of life-threatening conditions, mortality, or varying degrees of disability. Hypoxia-inducible factor 1α (HIF 1α), an oxygen- sensitive transcription factor that controls the adaptive metabolic response to hypoxia, is a critical constituent of cerebral ischemia. It participates in numerous processes, such as metabolism, proliferation, and angiogenesis, and plays a major role in cerebral ischemia.

METHODS

Through the use of a number of different search engines like Scopus, PubMed, Bentham, and Elsevier databases, a literature review was carried out for investigating the pharmacological modulation of HIF-1α pathways for the treatment of cerebral ischemia.

RESULTS

Various signalling pathways, such as Mitogen-activated protein kinase (MAPK), Janus kinase/ signal transducers and activators (JAK/STAT), Phosphoinositide-3-kinase (PI3-K), and cAMPresponse element binding protein (CREB) play a vital role in modulation of HIF-1α pathway, which helps in preventing the pathogenesis of cerebral ischemia.

CONCLUSION

The pharmacological modulation of the HIF-1α pathway via various molecular signalling pathways, such as PI3-K, MAPK, CREB, and JAK/STAT activators, offer a promising prospect for future interventions and treatment for cerebral ischemia.

Current Advances and Future Directions of Pluripotent Stem Cells-Derived Engineered Heart Tissue for Treatment of Cardiovascular Diseases

Cardiovascular diseases resulting from myocardial infarction (MI) remain a leading cause of death worldwide, imposing a substantial burden on global health systems. Current MI treatments, primarily pharmacological and surgical, do not regenerate lost myocardium, leaving patients at high risk for heart failure. Engineered heart tissue (EHT) offers a promising solution for MI and related cardiac conditions by replenishing myocardial loss. However, challenges like immune rejection, inadequate vascularization, limited mechanical strength, and incomplete tissue maturation hinder clinical application. The discovery of human-induced pluripotent stem cells (hiPSCs) has transformed the EHT field, enabling new bioengineering innovations. This review explores recent advancements and future directions in hiPSC-derived EHTs, focusing on innovative materials and fabrication methods like bioprinting and decellularization, and assessing their therapeutic potential through preclinical and clinical studies. Achieving functional integration of EHTs in the heart remains challenging due to the need for synchronized contraction, sufficient vascularization, and mechanical compatibility. Solutions such as genome editing, personalized medicine, and AI technologies offer promising strategies to address these translational barriers. Beyond MI, EHTs also show potential in treating ischemic cardiomyopathy, heart valve engineering, and drug screening, underscoring their promise in cardiovascular regenerative medicine.

Minocycline inhibits microglial activation in the CA1 hippocampal region and prevents long-term cognitive sequel after experimental cerebral malaria

Cerebral malaria is the worst complication of malaria infection, has a high mortality rate, and may cause different neurodysfunctions, including cognitive decline. Neuroinflammation is an important cause of cognitive damage in neurodegenerative diseases, and microglial cells can be activated in a disease-associated profile leading to tissue damage and neuronal death. Here, we demonstrated that treatment with minocycline reduced blood-brain barrier breakdown and modulated ICAM1 mRNA expression; reduced proinflammatory cytokines, such as TNF-α, IL-1β, IFN-γ, and IL-6; and prevented long-term cognitive decline in contextual and aversive memory tasks. Taken together, our data suggest that microglial cells are activated during experimental cerebral malaria, leading to neuroinflammatory events that end up in cognitive damage. In addition, pharmacological modulation of microglial activation, by drugs such as minocycline may be an important therapeutic strategy in the prevention of long-term memory impairment.

Decoding ferroptosis: transforming orthopedic disease management

As a mechanism of cell death, ferroptosis has gained popularity since 2012. The process is distinguished by iron toxicity and phospholipid accumulation, in contrast to autophagy, apoptosis, and other cell death mechanisms. It is implicated in the advancement of multiple diseases across the body. Researchers currently know that osteosarcoma, osteoporosis, and other orthopedic disorders are caused by NRF2, GPX4, and other ferroptosis star proteins. The effective relief of osteoarthritis symptoms from deterioration has been confirmed by clinical treatment with multiple ferroptosis inhibitors. At the same time, it should be reminded that the mechanisms involved in ferroptosis that regulate orthopedic diseases are not currently understood. In this manuscript, we present the discovery process of ferroptosis, the mechanisms involved in ferroptosis, and the role of ferroptosis in a variety of orthopedic diseases. We expect that this manuscript can provide a new perspective on clinical diagnosis and treatment of related diseases.

Long-term hypoxia-induced physiological response in turbot Scophthalmus maximus L

Hypoxia affects fish's survival, growth, and physiological metabolism processes. In this study, turbot plasma glucose and cortisol contents, hepatic glycolysis (hexokinase [HK], phosphofructokinase [PFK], pyruvate kinase [PK]) and lipolysis (fatty acid synthetase [FAS], lipoprotein lipase [LPL]) enzyme activities, anti-oxidant enzyme (superoxide dismutase [SOD], catalase [CAT], glutathione peroxidase [GSH-Px]) activities, malondialdehyde (MDA), lactate and glycogen contents, gill histological parameters (lamellar length [SLL], width [SLW], interlamellar distance [ID]), respiratory frequency (RF), the proportion of the secondary lamellae available for gas exchange (PAGE), and hifs (hif-1α, hif-2α, hif-3α) expression were determined during long-term hypoxia and reoxygenation. Results showed that long-term hypoxia (3.34 ± 0.17 mg L-1) significantly elevated plasma cortisol and glucose contents; increased hepatic HK, PK, PFK, FAS, and LPL activity; decreased hepatic glycogen, lactate contents, and lipid drop numbers; and caused changes of hepatocyte (vacuolation, pyknotic, and lytic nucleus) after treatment for 4 weeks. Hepatic SOD, CAT, GSH-Px activity, and MDA contents; lamellar perimeter, SLL, ID, RF, and PAGE; and hepatic hif-1α, hif-2α, and hif-3α manifested similar results. Meanwhile, hif-1α is significantly higher than hif-2α, and hif-3α. Interestingly, females and males demonstrated no sex dimorphism significantly different from the above parameters (except hepatic FAS, LPL activity, and lipid drop number) under hypoxia. The above parameters recovered to normal levels after reoxygenation treatment for 4 weeks. Thus, long-term hypoxia promotes turbot hepatic glycogenolysis and lipolysis, induces oxidative damage and stimulates hepatic antioxidant capacity, and alters gill morphology to satisfy insufficient energy demand and alleviate potential damage, while hif-1α plays critical roles in the above physiological process.

Insoluble HIFa protein aggregates by cadmium disrupt hypoxia-prolyl hydroxylase (PHD)-hypoxia inducible factor (HIFa) signaling in renal epithelial (NRK-52E) and interstitial (FAIK3-5) cells

The kidney is the main organ that senses changes in systemic O2 pressure by hypoxia-PHD-HIFa (HPH) signaling, resulting in adaptive target gene activation, including erythropoietin (EPO). The non-essential transition metal cadmium (Cd) is nephrotoxic and disrupts the renal HPH pathway, which may promote Cd-associated chronic renal disease (CKD). A deeper molecular understanding of Cd interference with renal HPH signaling is missing, and no data with renal cell lines are available. In rat kidney NRK-52E cells, which model the proximal tubule, and murine fibroblastoid atypical interstitial kidney (FAIK3-5) cells, which mimic renal EPO-producing cells, the chemical hypoxia mimetic dimethyloxalylglycine (DMOG; 1 mmol/l) or hypoxia (1% O2) activated HPH signaling. Cd2+ (2.5-20 µmol/l for ≤ 24 h) preferentially induced necrosis (trypan blue uptake) of FAIK3-5 cells at high Cd whereas NRK-52E cells specially developed apoptosis (PARP-1 cleavage) at all Cd concentrations. Cd (12.5 µmol/l) abolished HIFa stabilization and prevented upregulation of target genes (quantitative real-time polymerase chain reaction and immunoblotting) induced by DMOG or hypoxia in both cell lines, which was caused by the formation of insoluble HIFa aggregates. Strikingly, hypoxic preconditioning (1% O2 for 18 h) reduced apoptosis of FAIK3-5 and NRK-52E cells at low Cd concentrations and decreased insoluble HIFa proteins. Hence, drugs mimicking hypoxic preconditioning could reduce CKD induced by chronic low Cd exposure.

Hypoxia and collagen deposition in the kidneys infected with Acanthamoeba sp

Acanthamoeba spp. are facultative, opportunistic pathogens that are found in diverse environments. In the hosts, they lead to multi-organ disease. Recent studies reported that they may induce changes in the kidneys of hosts. The aim of the study was to determine the influence of Acanthamoeba sp. on hypoxia and collagen deposition in the kidneys of immunocompetent and immunosuppressed mice infected with Acanthamoeba sp. The results strongly suggest that Acanthamoeba sp. induces hypoxia in mice with normal and reduced immune response by increasing gene and/or protein expression of HIF1α as well as HIF2α. Additionally, the activation of these factors is probably induced via NOX2/ROS. Hypoxia promotes vessel formation, and we found that angiogenesis occurs in the kidneys of mice infected with the parasite regardless of their immunological status. The proangiogenic factors released in hypoxic conditions cause modulation and inflammation in the kidney cells, which in turn leads to collagen deposition via TGF-β. This work reveals mechanisms occurring in the hosts infected with Acanthamoeba sp., highlights as well as supports the relevance of pathophysiology in the kidneys in hosts with systematic acanthamoebiasis.

Role of HIF1A gene polymorphisms with serum uric acid and HIF-1α levels in monosodium urate crystal-induced arthritis

BACKGROUND

Gouty arthritis is a metabolic disease characterized by the deposition of monosodium urate crystals in the joints, which triggers the release of interleukin-1β (IL-β) by activating the NLRP3 inflammasome. Hypoxia-inducible factor-1α (HIF-1α) is a transcription factor involved in IL-β production and as a regulator of NLRP3.

OBJECTIVES

The aims were to analyze the association of HIF1A rs11549465, rs11549467, and rs2057482 variants in patients with gouty arthritis, and to evaluate the correlation between urate and HIF-1α levels according to the associated genotypes.

METHODS

Cases and controls were genotyped using TaqMan probes, and urate and HIF-1α levels were quantified. Data were analyzed using SPSS v21 software and P-values < 0.05 were considered statistically significant.

RESULTS

Urate and HIF-1α levels were higher in patients than in controls (P < 0.05). Under the three inheritance models (codominant, dominant, and recessive), the AA genotype of the rs11549467 variant was associated with gout risk (OR = 5.74, P = 0.009, OR = 3.33, P = 0.024, and OR = 9.09, P = 0.003, respectively). There were significant differences in the distribution of serum levels of both HIF-1α (P < 0.0001) and urate (P = 0.016) according to the genotypes of the rs11549467 variant.

CONCLUSION

These results suggest that the HIF1A rs11549467 variant may play a key role in the pathogenesis of gouty arthritis. Key Points • The pathogenesis of gouty arthritis involves the HIF1A gene. • In patients with gout, the AA genotype of the rs11549467 (HIF1A) variant is associated with increased serum levels of urate and HIF-1α. • HIF-1α is involved in the regulation of IL-1β and NLRP3.

Exploring hypoxia-induced ncRNAs as biomarkers and therapeutic targets in lung cancer

Lung cancer is a deadly disease, causing nearly 20 % of all cancer deaths globally. A key factor in lung cancer's development and resistance to treatment is hypoxia, a condition where tumor cells experience low oxygen levels. In this low-oxygen environment, special molecules called non-coding RNAs (ncRNAs) become critical players. NcRNAs, including lncRNAs, miRNAs, circRNAs, and siRNAs, control how genes function and how cells behave. Some ncRNAs, like HIF1A-AS2 and HOTAIR, are linked to the aggressive spread of lung cancer, making them potential targets for therapy. Others, like certain miRNAs, show promise as early detection tools due to their influence on tumor blood vessel formation and metabolism. This complex interplay between hypoxia and ncRNAs is crucial for understanding lung cancer. For example, circRNAs can control the activity of miRNAs, impacting how tumors respond to low oxygen. Additionally, siRNAs offer a potential strategy to overcome treatment resistance caused by hypoxia. By studying the intricate relationship between hypoxia and ncRNAs, scientists hope to uncover new biomarkers for lung cancer. This knowledge will pave the way for developing more effective and targeted treatments for this devastating disease.

Imidazoline receptors as a new therapeutic target in Huntington's disease: A preclinical overview

An autosomal dominant neurodegenerative disease called Huntington's disease (HD) is characterized by motor dysfunction, cognitive decline, and a variety of psychiatric symptoms due to the expansion of polyglutamine in the Huntingtin gene. The disease primarily affects the striatal neurons within the basal ganglia, leading to significant neuronal loss and associated symptoms such as chorea and dystonia. Current therapeutic approaches focus on symptom management without altering the disease's progression, highlighting a pressing need for novel treatment strategies. Recent studies have identified imidazoline receptors (IRs) as promising targets for neuroprotective and disease-modifying interventions in HD. IRs, particularly the I1 and I2 subtypes, are involved in critical physiological processes such as neurotransmission, neuronal excitability, and cell survival. Activation of these receptors has been shown to modulate neurotransmitter release and provide neuroprotective effects in preclinical models of neurodegeneration. This review discusses the potential of IR-targeted therapies to not only alleviate multiple symptoms of HD but also possibly slow the progression of the disease. We emphasize the necessity for ongoing research to further elucidate the role of IRs in HD and develop selective ligands that could lead to effective and safe treatments, thereby significantly improving patient outcomes and quality of life.

Hypoxia and ferroptosis

Ferroptosis is a novel, iron-dependent cell death characterized by the excessive accumulation of ferroptosis lipid peroxides ultimately leading to oxidative damage to the cell membrane. Iron, lipid, amino acid metabolism, and other signaling pathways all control ferroptosis. Numerous bodily tissues experience hypoxia under normal and pathological circumstances. Tissue cells can adjust to these changes by activating the hypoxia-inducible factor (HIF) signaling pathway and other mechanisms in response to the hypoxic environment. In recent years, there has been increasing evidence that hypoxia and ferroptosis are closely linked, and that hypoxia can regulate ferroptosis in specific cells and conditions through different pathways. In this paper, we review the possible positive and negative regulatory mechanisms of ferroptosis by hypoxia-inducible factors, as well as ferroptosis-associated ischemic diseases, with the intention of delivering novel therapeutic avenues for the defense and management of hypoxic illnesses linked to ferroptosis.

Extracellular matrix production and oxygen diffusion regulate chemotherapeutic response in osteosarcoma spheroids

BACKGROUND

Osteosarcoma (OS) survival rates and outcome have not improved in 50 years since the advent of modern chemotherapeutics. Thus, there is a critical need for an improved understanding of the tumor microenvironment to identify better therapies. Extracellular matrix (ECM) deposition and hypoxia are known to abrogate the efficacy of various chemical and cell-based therapeutics. Here, we aim to mechanistically investigate the combinatorial effects of hypoxia and matrix deposition with the use of OS spheroids.

METHODS

We use two murine OS cell lines with differential metastatic potential to form spheroids. We form spheroids of two sizes, use ascorbate-2-phosphate supplementation to enhance ECM deposition, and study cell response under standard (21% O2) and physiologic (5% O2) oxygen tensions. Finally, we examine chemotherapeutic responses to doxorubicin treatment.

RESULTS

ECM production and oxygen tension are key determinants of spheroid size through cell organization based on nutrient and oxygen distribution. Interestingly, highly metastatic OS is more susceptible to chemotherapeutics compared to less metastatic OS when matrix production increases. Together, these data suggest that dynamic interactions between ECM production and oxygen diffusion may result in distinct chemotherapeutic responses despite inherent tumor aggressiveness.

CONCLUSION

This work establishes OS spheroids as a valuable tool for early OS tumor formation investigation and holds potential for novel therapeutic target and prognostic indicator discovery.

Hypoxia related genes modulate in similar fashion in skin fibroblast cells of yak (Bos grunniens) adapted to high altitude and native cows (Bos indicus) adapted to tropical climate during hypoxia stress

The present study was conducted to understand transcriptional response of skin fibroblast of yak (Bos grunniens) and cows of Bos indicus origin to hypoxia stress. Six primary fibroblast cell lines derived from three individuals each of Ladakhi yak (Bos grunniens) and Sahiwal cows (Bos indicus) were exposed to low oxygen concentration for a period of 24 h, 48 h and 72 h. The expression of 10 important genes known to regulate hypoxia response such as HIF1A, VEGFA, EPAS1, ATP1A1, GLUT1, HMOX1, ECE1, TNF-A, GPx and SOD were evaluated in fibroblast cells of Ladakhi yak (LAY-Fb) and Sahiwal cows (SAC-Fb) during pre- and post-hypoxia stress. A panel of 10 reference genes (GAPDH, RPL4, EEF1A1, RPS9, HPRT1, UXT, RPS23, B2M, RPS15, ACTB) were also evaluated for their expression stability to perform accurate normalization. The expression of HIF1A was significantly (p < 0.05) induced in both LAY-Fb (2.29-fold) and SAC-Fb (2.07-fold) after 24 h of hypoxia stress. The angiogenic (VEGFA), metabolic (GLUT1) and antioxidant genes (SOD and GPx) were also induced after 24 h of hypoxia stress. However, EPAS1 and ATP1A1 induced significantly (p < 0.05) after 48 h whereas, ECE1 expression induced significantly (p < 0.05) at 72 h after exposure to hypoxia. The TNF-alpha which is a pro-inflammatory gene induced significantly (p < 0.05) at 24 h in SAC-Fb and at 72 h in LAY-Fb. The induction of hypoxia associated genes indicated the utility of skin derived fibroblast as cellular model to evaluate transcriptome signatures post hypoxia stress in populations adapted to diverse altitudes.

The protective effect and mechanism of piperazine ferulate in rats with 5/6 nephrectomy-caused chronic kidney disease

Chronic kidney disease (CKD) is a type of chronic disease in which multiple factors are responsible for the structural and functional disorders of the kidney. Piperazine ferulate (PF) has anti-platelet and anti-fibrotic effects, and its mechanism of action remains to be elucidated. This study aimed to investigate the protective effect of PF against CKD in rats and to determine its mechanism of action. Network pharmacology was used to predict potential PF action targets in the treatment of CKD and to further validate them. A rat model of CKD was established; blood was collected, etc., for the assessment of the renal function; renal pathologic damage was examined using hematoxylin and eosin (HE) staining and Masson staining; changes in the levels of TGF-β1 and α-SMA were determined with ELISA; EPOR, FN, and COL I expression were detected utilizing immunohistochemistry; and HIF-1α, HIF-2α, and EPO protein molecules were analyzed deploying western blotting. PF reduces Scr, BUN, and 24 h UP levels; decreases FN and COL I expression; and attenuates renal injury. Additionally, PF inhibited TGF-β1 and stimulated the production of HIF-1α and HIF-2α, which downregulated α-SMA and upregulated EPO. PF attenuated the progression of the CKD pathology, and the mechanism of its action is possibly associated with the promotion of HIF-1α/HIF-2α/EPO production and TGF-β1 reduction.

The Current State of Knowledge Regarding the Genetic Predisposition to Sports and Its Health Implications in the Context of the Redox Balance, Especially Antioxidant Capacity

The significance of physical activity in sports is self-evident. However, its importance is becoming increasingly apparent in the context of public health. The constant desire to improve health and performance suggests looking at genetic predispositions. The knowledge of genes related to physical performance can be utilized initially in the training of athletes to assign them to the appropriate sport. In the field of medicine, this knowledge may be more effectively utilized in the prevention and treatment of cardiometabolic diseases. Physical exertion engages the entire organism, and at a basic physiological level, the organism's responses are primarily related to oxidant and antioxidant reactions due to intensified cellular respiration. Therefore, the modifications involve the body adjusting to the stresses, especially oxidative stress. The consequence of regular exercise is primarily an increase in antioxidant capacity. Among the genes considered, those that promote oxidative processes dominate, as they are associated with energy production during exercise. What is missing, however, is a look at the other side of the coin, which, in this case, is antioxidant processes and the genes associated with them. It has been demonstrated that antioxidant genes associated with increased physical performance do not always result in increased antioxidant capacity. Nevertheless, it seems that maintaining the oxidant-antioxidant balance is the most important thing in this regard.

Mitochondrial metabolism regulation and epigenetics in hypoxia

The complex and dynamic interaction between cellular energy control and gene expression modulation is shown by the intersection between mitochondrial metabolism and epigenetics in hypoxic environments. Poor oxygen delivery to tissues, or hypoxia, is a basic physiological stressor that sets off a series of reactions in cells to adapt and endure oxygen-starved environments. Often called the "powerhouse of the cell," mitochondria are essential to cellular metabolism, especially regarding producing energy through oxidative phosphorylation. The cellular response to hypoxia entails a change in mitochondrial metabolism to improve survival, including epigenetic modifications that control gene expression without altering the underlying genome. By altering the expression of genes involved in angiogenesis, cell survival, and metabolism, these epigenetic modifications help cells adapt to hypoxia. The sophisticated interplay between mitochondrial metabolism and epigenetics in hypoxia is highlighted by several important points, which have been summarized in the current article. Deciphering the relationship between mitochondrial metabolism and epigenetics during hypoxia is essential to understanding the molecular processes that regulate cellular adaptation to reduced oxygen concentrations.

Transcriptional Responses of Different Brain Cell Types to Oxygen Decline

Brain hypoxia is associated with a wide range of physiological and clinical conditions. Although oxygen is an essential constituent of maintaining brain functions, our understanding of how specific brain cell types globally respond and adapt to decreasing oxygen conditions is incomplete. In this study, we exposed mouse primary neurons, astrocytes, and microglia to normoxia and two hypoxic conditions and obtained genome-wide transcriptional profiles of the treated cells. Analysis of differentially expressed genes under conditions of reduced oxygen revealed a canonical hypoxic response shared among different brain cell types. In addition, we observed a higher sensitivity of neurons to oxygen decline, and dissected cell type-specific biological processes affected by hypoxia. Importantly, this study establishes novel gene modules associated with brain cells responding to oxygen deprivation and reveals a state of profound stress incurred by hypoxia.

Crosstalk between hypoxia-inducible factor-1α and short-chain fatty acids in inflammatory bowel disease: key clues toward unraveling the mystery

The human intestinal tract constitutes a complex ecosystem, made up of countless gut microbiota, metabolites, and immune cells, with hypoxia being a fundamental environmental characteristic of this ecology. Under normal physiological conditions, a delicate balance exists among these complex "residents", with disruptions potentially leading to inflammatory bowel disease (IBD). The core pathology of IBD features a disrupted intestinal epithelial barrier, alongside evident immune and microecological disturbances. Central to these interconnected networks is hypoxia-inducible factor-1α (HIF-1α), which is a key regulator in gut cells for adapting to hypoxic conditions and maintaining gut homeostasis. Short-chain fatty acids (SCFAs), as pivotal gut metabolites, serve as vital mediators between the host and microbiota, and significantly influence intestinal ecosystem. Recent years have seen a surge in research on the roles and therapeutic potential of HIF-1α and SCFAs in IBD independently, yet reviews on HIF-1α-mediated SCFAs regulation of IBD under hypoxic conditions are scarce. This article summarizes evidence of the interplay and regulatory relationship between SCFAs and HIF-1α in IBD, pivotal for elucidating the disease's pathogenesis and offering promising therapeutic strategies.

High expression of B7-H3 on monocyte/macrophages in tumor microenvironment promotes lung cancer progression by inhibiting apoptosis

Monocyte/macrophages constitute a significant population of tumor-infiltrating immune cells and play a crucial role in tumor growth, invasion, and metastasis. B7-H3, has immune regulatory functions, however, it is unclear whether B7-H3 expressed on monocyte/macrophages plays a significance role in tumor progression. We found B7-H3 was high-expressed on monocyte/macrophages in tumor microenvironment compared with adjacent tissues in lung cancer, and its expression level was positively correlated with the number of monocyte/macrophages. Furthermore, the expression of B7-H3 was related to clinical stage and lymph node metastasis. Moreover, miR-29a-3p negatively regulated B7-H3, and the expression of B7-H3 on THP-1-derived macrophages was regulated by secreting exosomes containing miR-29a-3p. In addition, knockdown of B7-H3 promoted macrophage apoptosis under hypoxia. Mechanistically, B7-H3 enhanced the antiapoptotic ability of macrophage by up-regulating HIF-1ɑ via activating NF-κB. Taken together, these results imply that B7-H3 as a therapeutic target could hold promise for enhancing anti-tumor immune responses in individuals diagnosed with lung cancer.

Hypoxia and its effect on the cellular system

Eukaryotic cells utilize oxygen for different functions of cell organelles owing to cellular survival. A balanced oxygen homeostasis is an essential requirement to maintain the regulation of normal cellular systems. Any changes in the oxygen level are stressful and can alter the expression of different homeostasis regulatory genes and proteins. Lack of oxygen or hypoxia results in oxidative stress and formation of hypoxia inducible factors (HIF) and reactive oxygen species (ROS). Substantial cellular damages due to hypoxia have been reported to play a major role in various pathological conditions. There are different studies which demonstrated that the functions of cellular system are disrupted by hypoxia. Currently, study on cellular effects following hypoxia is an important field of research as it not only helps to decipher different signaling pathway modulation, but also helps to explore novel therapeutic strategies. On the basis of the beneficial effect of hypoxia preconditioning of cellular organelles, many therapeutic investigations are ongoing as a promising disease management strategy in near future. Hence, the present review discusses about the effects of hypoxia on different cellular organelles, mechanisms and their involvement in the progression of different diseases.

HIF2-α Expression in CML Patients Receiving Hydroxyurea Prior to Imatinib That Achieved Major Molecular Response (MMR) versus in Those Not Achieving MMR

Introduction

Currently, Imatinib (IM) which is a Tyrosine Kinase Inhibitor (TKI), is the main treatment for patients with chronic myeloid leukemia (CML). Major molecular response (MMR) is used as therapeutic response. Resistance to IM may be caused by hypoxia which is regulated by hypoxia inducible factor (HIF) 2-α. The role of HIF2-α is currently not researched extensively. This study aimed to analyse the differences in HIF-2α expression between chronic phase CML patients that achieved MMR and those that did not achieve MMR.

Methods

This study used a cross-sectional method which analysed secondary data from whole blood samples in chronic phase CML patients aged 18-60 years that received hydroxyurea (HU) before IM, aged 18-60 years, received IM therapy for more than 12 months, and were willing to participate in the study. The exclusion criteria for this study were patients who were receiving IM at a dose of more than 400 mg/day. HIF-2α protein expression was examined using the enzyme-linked immunosorbent assay (ELISA) method. Differences between HIF-2α protein expression in groups that achieved MMR versus not achieving MMR was analysed using the Mann-Whitney test.

Results

A total of 79 subjects were obtained. The median HIF-2α was 90.56 pg/mg protein (3.01-4628.74). There was no statistically significant difference in expression of HIF-2α in the group that reached MMR and did not reach MMR, namely 123.45 pg/mg protein and 89.25 pg/mg protein respectively (p 0.718).

Conclusion

This study found no statistically significant difference between HIF-2α expression level and MMR achievement of chronic phase CML patients who received HU before IM therapy.

Effect of Intermittent Hypobaric Hypoxia Exposure on HIF-1α, VEGF, and Angiogenesis in the Healing Process of Post-Tooth Extraction Sockets in Rats

OBJECTIVE

 The aim of this study was to investigate the effect of intermittent hypobaric hypoxia (IHH) exposure on the expression of hypoxia-induced factor-1α (HIF-1α) messenger RNA (mRNA), vascular endothelial growth factor-a (VEGF-a) mRNA, and angiogenesis after tooth extraction in rats.

MATERIALS AND METHODS

 On 45 male Sprague-Dawley rats were performed the removal of the maxillary left first molar, and then they were randomly divided into 9 groups, namely: 4 groups that were exposed to IHH for 30 minutes every day in the Hypobaric Chamber at an altitude of 18,000 feet, with 1 time hypobaric hypoxia (HH), 3 times HH, 5 times HH, and 7 times HH; 4 normoxia groups that were terminated on days 1, 3, 5, and 7 after tooth extraction; and the 1 control group. Real-time polymerase chain reaction measured the molecular changes in the socket tissue after tooth extraction in rats to evaluate the expression of HIF-1α mRNA and VEGF mRNA. Histological changes with hematoxylin and eosin staining were noted to evaluate the amount of angiogenesis in the socket after tooth extraction. Molecular and histological parameters were calculated at the end of each experiment on days 0, 1, 3, 5, and 7 after tooth extraction, which exhibited the improvement phase of the wound-healing process.

RESULTS

 Increases in the expression of HIF-1α mRNA, VEGF mRNA, and angiogenesis were found in the IHH group compared with the normoxia group and the control group. The expression of HIF-1α mRNA increased significantly (p < 0.05) in the group after one time HH exposure on day 1, then decreased in the IHH group (three times HH exposure, five times HH exposure, and seven times HH exposure) approaching the control group. The expression of VEGF mRNA and angiogenesis began to increase after one time HH exposure on day 1, and increased again after three times HH exposure on day 3, then increased even more after five times HH exposure on day 5, and increased very significantly (**p < 0.05) after seven times HH exposure on day 7. It showed that repeated or intermittent exposure to HH conditions induced a protective response that made cells adapt under hypoxia conditions.

CONCLUSION

 IHH exposure accelerates the socket healing of post-tooth extraction, which is proven by changes in HIF-1α mRNA expression and increase in VEGF mRNA expression as stimuli for angiogenesis in post-tooth extraction sockets under hypobaric hypoxic condition, which also stimulates the formation of new blood vessels, thereby increasing blood supply and accelerating wound healing.

Fetal monitoring technologies for the detection of intrapartum hypoxia - challenges and opportunities

Intrapartum fetal hypoxia is related to long-term morbidity and mortality of the fetus and the mother. Fetal surveillance is extremely important to minimize the adverse outcomes arising from fetal hypoxia during labour. Several methods have been used in current clinical practice to monitor fetal well-being. For instance, biophysical technologies including cardiotocography, ST-analysis adjunct to cardiotocography, and Doppler ultrasound are used for intrapartum fetal monitoring. However, these technologies result in a high false-positive rate and increased obstetric interventions during labour. Alternatively, biochemical-based technologies including fetal scalp blood sampling and fetal pulse oximetry are used to identify metabolic acidosis and oxygen deprivation resulting from fetal hypoxia. These technologies neither improve clinical outcomes nor reduce unnecessary interventions during labour. Also, there is a need to link the physiological changes during fetal hypoxia to fetal monitoring technologies. The objective of this article is to assess the clinical background of fetal hypoxia and to review existing monitoring technologies for the detection and monitoring of fetal hypoxia. A comprehensive review has been made to predict fetal hypoxia using computational and machine-learning algorithms. The detection of more specific biomarkers or new sensing technologies is also reviewed which may help in the enhancement of the reliability of continuous fetal monitoring and may result in the accurate detection of intrapartum fetal hypoxia.

Nanotechnology-mediated photodynamic therapy: Focus on overcoming tumor hypoxia

The oxygen level in the tumor is a critical marker that determines response to different treatments. Cancerous cells can adapt to hypoxia and low pH conditions within the tumor microenvironment (TME) to regulate tumor metabolism, proliferation, and promote tumor metastasis as well as angiogenesis, consequently leading to treatment failure and recurrence. In recent years, widespread attempts have been made to overcome tumor hypoxia through different methods, such as hyperbaric oxygen therapy (HBOT), hyperthermia, O2 carriers, artificial hemoglobin, oxygen generator hydrogels, and peroxide materials. While oxygen is found to be an essential agent to improve the treatment response of photodynamic therapy (PDT) and other cancer treatment modalities, the development of hypoxia within the tumor is highly associated with PDT failure. Recently, the use of nanoparticles has been a hot topic for researchers and exploited to overcome hypoxia through Oxygen-generating hydrogels, O2 nanocarriers, and O2 -generating nanoparticles. This review aimed to discuss the role of nanotechnology in tumor oxygenation and highlight the challenges, prospective, and recent advances in this area to improve PDT outcomes. This article is categorized under: Nanotechnology Approaches to Biology > Cells at the Nanoscale Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Exploration on anti-hypoxia properties of peptides: a review

Peptides are important components of human nutrition and health, and considered as safe, nontoxic, and easily absorbed potential drugs. Anti-hypoxia peptides are a kind of peptides that can prevent hypoxia or hypoxia damage. In this paper, the sources, preparations, and molecular mechanisms of anti-hypoxia peptides were systemically reviewed. The combination of bioinformatics, chemical synthesis, enzymatic hydrolysis, and microbial fermentation are recommended for efficient productions of anti-hypoxic peptides. The mechanisms of anti-hypoxic peptides include interference with glycolytic process and HIF-1α pathway, mitochondrial apoptosis, and inflammatory response. In addition, bioinformatics analysis, including virtual screening and molecular docking, provides an alternative or auxiliary method for exploring the potential anti-hypoxic activities and mechanisms of peptides. The potential challenges and prospects of anti-hypoxic peptides are also discussed. This paper can provide references for researchers in this field and promote further research and clinical applications of anti-hypoxic peptides in the future.

Genomic Variation, Population History, and Long-Term Genetic Adaptation to High Altitudes in Tibetan Partridge (Perdix hodgsoniae)

Species residing across elevational gradients display adaptations in response to environmental changes such as oxygen availability, ultraviolet radiation, and temperature. Here, we study genomic variation, gene expression, and long-term adaptation in Tibetan Partridge (Perdix hodgsoniae) populations residing across the elevational gradient of the Tibetan Plateau. We generated a high-quality draft genome and used it to carry out downstream population genomic and transcriptomic analysis. The P. hodgsoniae populations residing across various elevations were genetically distinct, and their phylogenetic clustering was consistent with their geographic distribution. We identified possible evidence of gene flow between populations residing in <3,000 and >4,200 m elevation that is consistent with known habitat expansion of high-altitude populations of P. hodgsoniae to a lower elevation. We identified a 60 kb haplotype encompassing the Estrogen Receptor 1 (ESR1) gene, showing strong genetic divergence between populations of P. hodgsoniae. We identified six single nucleotide polymorphisms within the ESR1 gene fixed for derived alleles in high-altitude populations that are strongly conserved across vertebrates. We also compared blood transcriptome profiles and identified differentially expressed genes (such as GAPDH, LDHA, and ALDOC) that correlated with differences in altitude among populations of P. hodgsoniae. These candidate genes from population genomics and transcriptomics analysis were enriched for neutrophil degranulation and glycolysis pathways, which are known to respond to hypoxia and hence may contribute to long-term adaptation to high altitudes in P. hodgsoniae. Our results highlight Tibetan Partridges as a useful model to study molecular mechanisms underlying long-term adaptation to high altitudes.

Allicin, an Emerging Treatment for Pulmonary Arterial Hypertension: An Experimental Study

We assessed whether allicin, through its antihypertensive and antioxidant effects, relieves vascular remodeling, endothelial function, and oxidative stress (OS), thereby improving experimental pulmonary arterial hypertension (PAH). Allicin (16 mg/kg) was administered to rats with PAH (monocrotaline 60 mg/kg). Allicin encouraged body weight gain and survival rate, and medial wall thickness and the right ventricle (RV) hypertrophy were prevented. Also, angiotensin II concentrations in the lung (0.37 ± 0.01 vs. 0.47 ± 0.06 pmoles/mL, allicin and control, respectively) and plasma (0.57 ± 0.05 vs. 0.75 ± 0.064, allicin and control respectively) and the expressions of angiotensin-converting enzyme II and angiotensin II type 1 receptor in lung tissue were maintained at normal control levels with allicin. In PAH rats treated with allicin, nitric oxide (NO) (31.72 ± 1.22 and 51.4 ± 3.45 pmoles/mL), tetrahydrobiopterin (8.43 ± 0.33 and 10.14 ± 0.70 pmoles/mL), cyclic guanosine monophosphate (5.54 ± 0.42 and 5.64 ± 0.73 pmoles/mL), and Ang-(1-7) (0.88 ± 0.23 and 0.83 ± 0.056 pmoles/mL) concentrations increased in lung tissue and plasma, respectively. In contrast, dihydrobiopterin increase was prevented in both lung tissue and plasma (5.75 ± 0.3 and 5.64 ± 0.73 pmoles/mL); meanwhile, phosphodiesterase-5 was maintained at normal levels in lung tissue. OS in PAH was prevented with allicin through the increased expression of Nrf2 in the lung. Allicin prevented the lung response to hypoxia, preventing the overexpression of HIF-1α and VEGF. Allicin attenuated the vascular remodeling and RV hypertrophy in PAH through its effects on NO-dependent vasodilation, modulation of RAS, and amelioration of OS. Also, these effects could be associated with the modulation of HIF-1α and improved lung oxygenation. The global effects of allicin contribute to preventing endothelial dysfunction, remodeling of the pulmonary arteries, and RV hypertrophy, preventing heart failure, thus favoring survival. Although human studies are needed, the data suggest that, alone or in combination therapy, allicin may be an alternative in treating PAH if we consider that, similarly to current treatments, it improves lung vasodilation and increase survival. Allicin may be considered an option when there is a lack of efficacy, and where drug intolerance is observed, to enhance the efficacy of drugs, or when more than one pathogenic mechanism must be addressed.

Mitochondria in hypoxic pulmonary hypertension, roles and the potential targets

Mitochondria are the centrol hub for cellular energy metabolisms. They regulate fuel metabolism by oxygen levels, participate in physiological signaling pathways, and act as oxygen sensors. Once oxygen deprived, the fuel utilizations can be switched from mitochondrial oxidative phosphorylation to glycolysis for ATP production. Notably, mitochondria can also adapt to hypoxia by making various functional and phenotypes changes to meet the demanding of oxygen levels. Hypoxic pulmonary hypertension is a life-threatening disease, but its exact pathgenesis mechanism is still unclear and there is no effective treatment available until now. Ample of evidence indicated that mitochondria play key factor in the development of hypoxic pulmonary hypertension. By hypoxia-inducible factors, multiple cells sense and transmit hypoxia signals, which then control the expression of various metabolic genes. This activation of hypoxia-inducible factors considered associations with crosstalk between hypoxia and altered mitochondrial metabolism, which plays an important role in the development of hypoxic pulmonary hypertension. Here, we review the molecular mechanisms of how hypoxia affects mitochondrial function, including mitochondrial biosynthesis, reactive oxygen homeostasis, and mitochondrial dynamics, to explore the potential of improving mitochondrial function as a strategy for treating hypoxic pulmonary hypertension.

Multifactorial Distress, the Warburg Effect, and Respiratory and pH Imbalance in Cancer Development

Oncogenes are thought to play an important role in aberrant regulation of growth factors, which is believed to be an initiation event of carcinogenesis. However, recent genetic and pharmacological studies have shown that the Warburg effect (WE) is needed for tumour growth. It refers to extensively studied aerobic glycolysis over the past decade, although its impact on cancer remains unclear. Meanwhile, a large body of evidence has indicated that oxidative stress (OS) is connected with the occurrence and progression of various forms of cancer. Psychosocial factors (PSF), such as chronic depression, sadness, stressful life experiences, stress-prone personality, and emotional distress or poor quality of life affect the immune system and contribute to cancer outcomes. Here, we examine the relationship between WE, OS, PSF, metal ions, other carcinogens, and the development of different cancers from the viewpoint of physiological and biochemical mechanisms.

Understanding human aging and the fundamental cell signaling link in age-related diseases: the middle-aging hypovascularity hypoxia hypothesis

Aging-related hypoxia, oxidative stress, and inflammation pathophysiology are closely associated with human age-related carcinogenesis and chronic diseases. However, the connection between hypoxia and hormonal cell signaling pathways is unclear, but such human age-related comorbid diseases do coincide with the middle-aging period of declining sex hormonal signaling. This scoping review evaluates the relevant interdisciplinary evidence to assess the systems biology of function, regulation, and homeostasis in order to discern and decipher the etiology of the connection between hypoxia and hormonal signaling in human age-related comorbid diseases. The hypothesis charts the accumulating evidence to support the development of a hypoxic milieu and oxidative stress-inflammation pathophysiology in middle-aged individuals, as well as the induction of amyloidosis, autophagy, and epithelial-to-mesenchymal transition in aging-related degeneration. Taken together, this new approach and strategy can provide the clarity of concepts and patterns to determine the causes of declining vascularity hemodynamics (blood flow) and physiological oxygenation perfusion (oxygen bioavailability) in relation to oxygen homeostasis and vascularity that cause hypoxia (hypovascularity hypoxia). The middle-aging hypovascularity hypoxia hypothesis could provide the mechanistic interface connecting the endocrine, nitric oxide, and oxygen homeostasis signaling that is closely linked to the progressive conditions of degenerative hypertrophy, atrophy, fibrosis, and neoplasm. An in-depth understanding of these intrinsic biological processes of the developing middle-aged hypoxia could provide potential new strategies for time-dependent therapies in maintaining healthspan for healthy lifestyle aging, medical cost savings, and health system sustainability.

Hypobaric Hypoxia Aggravates Renal Injury by Inducing the Formation of Neutrophil Extracellular Traps through the NF-κB Signaling Pathway

OBJECTIVE

The hypersensitivity of the kidney makes it susceptible to hypoxia injury. The involvement of neutrophil extracellular traps (NETs) in renal injury resulting from hypobaric hypoxia (HH) has not been reported. In this study, we aimed to investigate the expression of NETs in renal injury induced by HH and the possible underlying mechanism.

METHODS

A total of 24 SD male rats were divided into three groups (n=8 each): normal control group, hypoxia group and hypoxia+pyrrolidine dithiocarbamate (PDTC) group. Rats in hypoxia group and hypoxia+PDTC group were placed in animal chambers with HH which was caused by simulating the altitude at 7000 meters (oxygen partial pressure about 6.9 kPa) for 7 days. PDTC was administered at a dose of 100 mg/kg intraperitoneally once daily for 7 days. Pathological changes of the rat renal tissues were observed under a light microscope; the levels of serum creatinine (SCr), blood urea nitrogen (BUN), cell-free DNA (cf-DNA) and reactive oxygen species (ROS) were measured; the expression levels of myeloperoxidase (MPO), citrullinated histone H3 (cit-H3), B-cell lymphoma 2 (Bcl-2), Bax, nuclear factor kappa B (NF-κB) p65 and phospho-NF-κB p65 (p-NF-κB p65) in rat renal tissues were detected by qRT-qPCR and Western blotting; the localization of NF-κB p65 expression in rat renal tissues was observed by immunofluorescence staining and the expression changes of NETs in rat renal tissues were detected by multiplex fluorescence immunohistochemical staining.

RESULTS

After hypoxia, the expression of NF-κB protein in renal tissues was significantly increased, the levels of SCr, BUN, cf-DNA and ROS in serum were significantly increased, the formation of NETs in renal tissues was significantly increased, and a large number of tubular dilatation and lymphocyte infiltration were observed in renal tissues. When PDTC was used to inhibit NF-κB activation, NETs formation in renal tissue was significantly decreased, the expression level of Bcl-2 in renal tissues was significantly increased, the expression level of Bax was significantly decreased, and renal injury was significantly alleviated.

CONCLUSION

HH induces the formation of NETs through the NF-κB signaling pathway, and it promotes apoptosis and aggravates renal injury by decreasing Bcl-2 and increasing Bax expression.

Molecular and Functional Characteristics of Airway Epithelium under Chronic Hypoxia

Localized and chronic hypoxia of airway mucosa is a common feature of progressive respiratory diseases, including cystic fibrosis (CF). However, the impact of prolonged hypoxia on airway stem cell function and differentiated epithelium is not well elucidated. Acute hypoxia alters the transcription and translation of many genes, including the CF transmembrane conductance regulator (CFTR). CFTR-targeted therapies (modulators) have not been investigated in vitro under chronic hypoxic conditions found in CF airways in vivo. Nasal epithelial cells (hNECs) derived from eight CF and three non-CF participants were expanded and differentiated at the air-liquid interface (26-30 days) at ambient and 2% oxygen tension (hypoxia). Morphology, global proteomics (LC-MS/MS) and function (barrier integrity, cilia motility and ion transport) of basal stem cells and differentiated cultures were assessed. hNECs expanded at chronic hypoxia, demonstrating epithelial cobblestone morphology and a similar proliferation rate to hNECs expanded at normoxia. Hypoxia-inducible proteins and pathways in stem cells and differentiated cultures were identified. Despite the stem cells' plasticity and adaptation to chronic hypoxia, the differentiated epithelium was significantly thinner with reduced barrier integrity. Stem cell lineage commitment shifted to a more secretory epithelial phenotype. Motile cilia abundance, length, beat frequency and coordination were significantly negatively modulated. Chronic hypoxia reduces the activity of epithelial sodium and CFTR ion channels. CFTR modulator drug response was diminished. Our findings shed light on the molecular pathophysiology of hypoxia and its implications in CF. Targeting hypoxia can be a strategy to augment mucosal function and may provide a means to enhance the efficacy of CFTR modulators.

Ferroptosis Regulated by Hypoxia in Cells

Ferroptosis is an oxidative damage-related, iron-dependent regulated cell death with intracellular lipid peroxide accumulation, which is associated with many physiological and pathological processes. It exhibits unique features that are morphologically, biochemically, and immunologically distinct from other regulated cell death forms. Ferroptosis is regulated by iron metabolism, lipid metabolism, anti-oxidant defense systems, as well as various signal pathways. Hypoxia, which is found in a group of physiological and pathological conditions, can affect multiple cellular functions by activation of the hypoxia-inducible factor (HIF) signaling and other mechanisms. Emerging evidence demonstrated that hypoxia regulates ferroptosis in certain cell types and conditions. In this review, we summarize the basic mechanisms and regulations of ferroptosis and hypoxia, as well as the regulation of ferroptosis by hypoxia in physiological and pathological conditions, which may contribute to the numerous diseases therapies.

The vascular endothelial growth factor (VEGF) system as a key regulator of ovarian follicle angiogenesis and growth

The vascular endothelial growth factor-A (VEGFA) system is a complex set of proteins, with multiple isoforms and receptors, including both angiogenic (VEGFxxx, VEGFR2) and antiangiogenic members (VEGFxxxb, VEGFR1 and soluble forms of VEGFR). The members of the VEGF system affect the proliferation, survival, and migration of endothelial and nonendothelial cells and are involved in the regulation of follicular angiogenesis and development. The production of VEGF by secondary follicles stimulates preantral follicular development by directly affecting follicular cells and promoting the acquisition of the follicular vasculature and downstream antrum formation. Additionally, the pattern of expression of the components of the VEGF system may provide a proangiogenic milieu capable of triggering angiogenesis and stimulating follicular cells to promote antral follicle growth, whereas, during atresia, this milieu becomes antiangiogenic and blocks follicular development.

Effects of Intermittent Normobaric Hypoxia on Health-Related Outcomes in Healthy Older Adults: A Systematic Review

BACKGROUND

Aging is a degenerative process that is associated with an increased risk of diseases. Intermittent hypoxia has been investigated in reference to performance and health-related functions enhancement. This systematic review aimed to summarize the effect of either passive or active intermittent normobaric hypoxic interventions compared with normoxia on health-related outcomes in healthy older adults.

METHODS

Relevant studies were searched from PubMed and Web of Science databases in accordance with PRISMA guidelines (since their inceptions up until August 9, 2022) using the following inclusion criteria: (1) randomized controlled trials, clinical trials and pilot studies; (2) Studies involving humans aged > 50 years old and without any chronic diseases diagnosed; (3) interventions based on in vivo intermittent systemic normobaric hypoxia exposure; (4) articles focusing on the analysis of health-related outcomes (body composition, metabolic, bone, cardiovascular, functional fitness or quality of life). Cochrane Collaboration recommendations were used to assess the risk of bias.

RESULTS

From 509 articles initially found, 17 studies were included. All interventions were performed in moderate normobaric hypoxia, with three studies using passive exposure, and the others combining intermittent hypoxia with training protocols (i.e., using resistance-, whole body vibration- or aerobic-based exercise).

CONCLUSIONS

Computed results indicate a limited effect of passive/active intermittent hypoxia (ranging 4-24 weeks, 2-4 days/week, 16-120 min/session, 13-16% of fraction of inspired oxygen or 75-85% of peripheral oxygen saturation) compared to similar intervention in normoxia on body composition, functional fitness, cardiovascular and bone health in healthy older (50-75 years old) adults. Only in specific settings (i.e., intermediate- or long-term interventions with high intensity/volume training sessions repeated at least 3 days per week), may intermittent hypoxia elicit beneficial effects. Further research is needed to determine the dose-response of passive/active intermittent hypoxia in the elderly.

TRIAL REGISTRATION

SYSTEMATIC REVIEW REGISTRATION

PROSPERO 2022 CRD42022338648.

Acute hypoxia induced dysregulation of clock-controlled ovary functions

High altitudes or exposure to hypoxia leads to female reproductive disorders. Circadian clocks are intrinsic time-tracking systems that enable organisms to adapt to the Earth's 24-h light/dark cycle, which can be entrained by other environmental stimuli to regulate physiological and pathological responses. In this study, we focused on whether ovarian circadian clock proteins were involved in regulating female reproductive dysfunction under hypoxic conditions. Hypobaric hypoxia was found to induce a significantly prolonged estrous cycle in female mice, accompanied by follicular atresia, pituitary/ovarian hormone synthesis disorder, and decreased LHCGR expression in the ovaries. Under the same conditions, the levels of the ovarian circadian clock proteins, CLOCK and BMAL1, were suppressed, whereas E4BP4 levels were upregulated. Results from granulosa cells (GCs) further demonstrated that CLOCK: BMAL1 and E4BP4 function as transcriptional activators and repressors of LHCGR in ovarian GCs, respectively, whose responses were mediated by HIF1ɑ-dependent (E4BP4 upregulation) and ɑ-independent (CLOCK and BMAL1 downregulation) manners. The LHCGR agonist was shown to efficiently recover the impairment of ovulation-related gene (EREG and PGR) expression in GCs induced by hypoxia. We conclude that hypoxia exposure causes dysregulation of ovarian circadian clock protein (CLOCK, BMAL1, and E4BP4) expression, which mediates female reproductive dysfunction by impairing LHCGR-dependent signaling events. Adjusting the timing system or recovering the LHCGR level in the ovaries may be helpful in overcoming female reproductive disorders occurring in the highlands.

Studies on oxygen availability and the creation of natural and artificial oxygen gradients in gelatin-methacryloyl hydrogel 3D cell culture

Three-dimensional (3D) cultivation platforms allow the creation of cell models, which more closely resemble in vivo-like cell behavior. Therefore, 3D cell culture platforms have started to replace conventional two-dimensional (2D) cultivation techniques in many fields. Besides the advantages of 3D culture, there are also some challenges: cultivation in 3D often results in an inhomogeneous microenvironment and therefore unique cultivation conditions for each cell inside the construct. As a result, the analysis and precise control over the singular cell state is limited in 3D. In this work, we address these challenges by exploring ways to monitor oxygen concentrations in gelatin methacryloyl (GelMA) 3D hydrogel culture at the cellular level using hypoxia reporter cells and deep within the construct using a non-invasive optical oxygen sensing spot. We could show that the appearance of oxygen limitations is more prominent in softer GelMA-hydrogels, which enable better cell spreading. Beyond demonstrating novel or space-resolved techniques of visualizing oxygen availability in hydrogel constructs, we also describe a method to create a stable and controlled oxygen gradient throughout the construct using a 3D printed flow-through chamber.

Luteolin ameliorates hypoxia-induced pulmonary hypertension via regulating HIF-2α-Arg-NO axis and PI3K-AKT-eNOS-NO signaling pathway

BACKGROUND

Pulmonary hypertension (PH) is a devastating disease with poor prognosis and high mortality. Hypoxia induced pulmonary hypertension (HPH) is a persistent threat to human health, especially to people who live on high altitude plateau. Pulmonary vascular endothelial cell is involved in numerous pathophysiological processes, including in vasoconstriction, oxidative stress, cell growth and differentiation. Endothelial cells (ECs) are the first layer to be exposed to changed oxygen levels and hypoxia could lead to ECs dysfunction. Endothelial-derived nitric oxide (NO) is the most important bioactive molecule, which could regulate endothelial homeostasis. PH pathophysiology has been linked to the disruption of NO pathways.

PURPOSE

Luteolin is a kind of plant active ingredient with multiple pharmacological activities. The purpose of this study is to detect the effect of luteolin on HPH with in vivo, ex vivo and in vitro analyses and to further elucidate luteolin's pharmaceutical mechanism with NO related signaling pathway regulation.

METHODS

Hypobaric chamber was used to establish HPH animal model. Rats were intragastrically administrated luteolin for 28 days. Then hemodynamic indexes, histopathological changes, pulmonary artery endothelial function, NO content and arginase activity in lung tissue, NO related pathway proteins expression were measured to evaluate the effect of luteolin on HPH. PAECs were treated with 1% O₂ and incubated with or without luteolin. PAECs vitality, NO content in cells supernatant, and NO related pathway proteins expression were tested to reveal the protective mechanism of luteolin.

RESULTS

Luteolin decreased mean pulmonary hypertension of HPH rats, alleviated right ventricular and pulmonary vascular remodeling. Immunofluorescence staining (vWF), isolated perfused/ventilated rat lung experiment indicated that luteolin protected pulmonary vascular endothelial function of HPH rats. Luteolin increased NO content in PAECs supernatant while decreased NO level in lung tissues of HPH rats. Further, it was demonstrated that luteolin inhibited HIF-2α-Arg axis in PAECs and HPH rats. PI3K-AKT-eNOS signaling pathway was upregulated in PAECs, but which was downregulated in lung tissues of HPH rats. Pharmacological effect of luteolin was equivalent or better than sildenafil.

CONCLUSION

Luteolin ameliorated HPH in rats by protecting pulmonary vascular endothelial function via regulating HIF-2α-Arg-NO axis and PI3K-AKT-eNOS-NO signaling pathway. This study may provide a novel perspective and approach to alleviate the devastating disease of HPH.

Role of hypoxia preconditioning in therapeutic potential of mesenchymal stem-cell-derived extracellular vesicles

The use of mesenchymal stem-cells (MSC) in cell therapy has received considerable attention because of their properties. These properties include high expansion and differentiation in vitro, low immunogenicity, and modulation of biological processes, such as inflammation, angiogenesis and hematopoiesis. Curiously, the regenerative effect of MSC is partly due to their paracrine activity. This has prompted numerous studies, to investigate the therapeutic potential of their secretome in general, and specifically their extracellular vesicles (EV). The latter contain proteins, lipids, nucleic acids, and other metabolites, which can cause physiological changes when released into recipient cells. Interestingly, contents of EV can be modulated by preconditioning MSC under different culture conditions. Among them, exposure to hypoxia stands out; these cells respond by activating hypoxia-inducible factor (HIF) at low O₂ concentrations. HIF has direct and indirect pleiotropic effects, modulating expression of hundreds of genes involved in processes such as inflammation, migration, proliferation, differentiation, angiogenesis, metabolism, and cell apoptosis. Expression of these genes is reflected in the contents of secreted EV. Interestingly, numerous studies show that MSC-derived EV conditioned under hypoxia have a higher regenerative capacity than those obtained under normoxia. In this review, we show the implications of hypoxia responses in relation to tissue regeneration. In addition, hypoxia preconditioning of MSC is being evaluated as a very attractive strategy for isolation of EV, with a high potential for clinical use in regenerative medicine that can be applied to different pathologies.

HIF-1α enhances autophagy to alleviate apoptosis in marginal cells in the stria vascular in neonatal rats under hypoxia

In the cochlea, various factors, such as noise, aging, and inflammation, induce hypoxia, resulting in the up-regulation of hypoxia inducible factor-1α (HIF-1α). The role of HIF-1α in hypoxic marginal cells (MCs) of the stria vascularis is unknown. This study examined HIF-1α-mediated autophagy in MCs of neonatal rats and its mechanism of action. We found that an increase in HIF-1α expression was associated with autophagy and apoptosis. Treatment with PX478, a specific inhibitor of HIF-1α, decreased the HIF-1α level, and the degree of autophagy decreased in hypoxic and apoptotic MCs. By contrast, treatment with DMOG, an activator of HIF-1α, increased autophagy and decreased apoptosis. Both PX478 and DMOG had no effect on the apoptotic rate after treatment with 3-methyladenine, an inhibitor of autophagy, indicating that HIF-1α promoted autophagy to protect MCs from hypoxia-induced apoptosis. Lastly, we silenced Bnip3(Bcl-2/adenovirus E1B 19-kDa interacting protein) in MCs to identify the mechanism of action. Our results show that the HIF-1α-BNIP3 pathway mediates the anti-apoptotic effects through an increase in autophagy.

Lycopene improves testicular damage and sperm quality in experimentally induced varicocele: Relationship with apoptosis, hypoxia, and hyperthermia

Varicocele is considered the main reason for male infertility. Antioxidants are common drugs used to reduce the complications of varicocele in these patients. So, we investigated the effects of lycopene on sperm quality, testicular histology, and the expression of some genes in experimentally induced varicocele. Fifty adult male Wistar rats were divided into three groups: control (n = 12), sham (n = 5), and varicocele (n = 33) groups. After 2 months of induced varicocele, five rats were randomly sacrificed and induced varicocele was investigated in each group. Finally, 35 rats were divided into five groups: the control, varicocele, varicocele reserving solvent, and varicocele reserving lycopene (4 and 10 mg/kg) for 2 months. At the end of the experiment, sperm viability, membrane integrity, the expression of Bax, Bcl2, hypoxia (hypoxia‐inducible factor 1α [HIF1‐α]), heat‐shock protein (heat‐shock protein A2 [HSPA2]) genes, and the histology of testes were measured. The results showed a significant decrease in the sperm viability, membrane integrity, Johnson's score, and the expression of the Bcl2 gene in the varicocele group compared to the control group. Also, there was a significant increase in Bax, HSPA2, and HIF1‐α expressions in the varicocele group compared to the control group. Although the administration of lycopene (10 mg/kg) in rats with varicocele improved sperm viability and membrane integrity, Johnson's score, and Bax expression compared to the varicocele group. Our findings indicated that the administration of lycopene in the varicocele group improved sperm quality and testicular injury induced by varicocele via decreasing apoptosis.

Intermittent Hypoxia as a Therapeutic Tool to Improve Health Parameters in Older Adults

Aging is associated with metabolic alterations, and with a loss of strength, muscle and bone mass. Moderate intermittent hypoxia has been proposed as a new tool to enhance health-related function. The aim of this study was to evaluate the effect of moderate intermittent hypoxia exposures on parameters related to cardiovascular and bone health in older adults. A total of 38 healthy older adults (aged 65-75 years) were divided into two groups: control group (C), and hypoxia group (H) that was subjected to an intermittent hypoxia exposure (at simulated altitude of 2500 m asl) during a 24-week period (3 days/week). Body composition, blood pressure, metabolic parameters (Cholesterol, triglycerides and glucose), C-reactive protein (CRP), vascular cell adhesion molecule-1 (VCAM-1), interleukin 8 (IL-8), interleukin 10 (IL-10), N-terminal propeptide of type I procollagen (PINP) and beta C-terminal telopeptide of collagen bone formation (b-CTX) were analyzed before and after the intervention. A repeated measures analysis of variance was performed to evaluate between-group differences. The results showed that the hypoxia group achieved after the intervention a decrease in fat mass, CRP (pro-inflammatory biomarker) and b-CTX (bone resorption biomarker), as well as an increase in PINP (bone formation biomarker). In conclusion, the intermittent hypoxia might be a useful therapeutic tool to deal with problems associated with aging, such as the increase in body fat, the loss of bone mass or low-grade inflammation.

Hypoxia-induced HIF1α activation regulates small extracellular vesicle release in human embryonic kidney cells

Extracellular vesicles (EVs) are membrane enclosures released by eukaryotic cells that carry bioactive molecules and serve to modulate biological responses in recipient cells. Both increased EV release and altered EV composition are associated with the development and progression of many pathologies including cancer. Hypoxia, a feature of rapidly growing solid tumours, increases the release of EVs. However, the molecular mechanisms remain unknown. The hypoxia inducible factors (HIFs) are transcription factors that act as major regulators of the cellular adaptations to hypoxia. Here, we investigated the requirement of HIF pathway activation for EV release in Human Embryonic Kidney Cells (HEK293). Time course experiments showed that EV release increased concomitantly with sustained HIF1α and HIF2α activation following the onset of hypoxia. shRNA mediated knock-down of HIF1α but not HIF2α abrogated the effect of hypoxia on EV release, suggesting HIF1α is involved in this process. However, stabilization of HIF proteins in normoxic conditions through: (i) heterologous expression of oxygen insensitive HIF1α or HIF2α mutants in normoxic cells or (ii) chemical inhibition of the prolyl hydroxylase 2 (PHD2) repressor protein, did not increase EV release, suggesting HIF activation alone is not sufficient for this process. Our findings suggest HIF1α plays an important role in the regulation of EV release during hypoxia in HEK293 cells, however other hypoxia triggered mechanisms likely contribute as stabilization of HIF1α alone in normoxia is not sufficient for EV release.

Bioactivities and mechanisms of natural medicines in the management of pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a progressive and rare disease without obvious clinical symptoms that shares characteristics with pulmonary vascular remodeling. Right heart failure in the terminal phase of PAH seriously threatens the lives of patients. This review attempts to comprehensively outline the current state of knowledge on PAH its pathology, pathogenesis, natural medicines therapy, mechanisms and clinical studies to provide potential treatment strategies. Although PAH and pulmonary hypertension have similar pathological features, PAH exhibits significantly elevated pulmonary vascular resistance caused by vascular stenosis and occlusion. Currently, the pathogenesis of PAH is thought to involve multiple factors, primarily including genetic/epigenetic factors, vascular cellular dysregulation, metabolic dysfunction, even inflammation and immunization. Yet many issues regarding PAH need to be clarified, such as the "oestrogen paradox". About 25 kinds monomers derived from natural medicine have been verified to protect against to PAH via modulating BMPR2/Smad, HIF-1α, PI3K/Akt/mTOR and eNOS/NO/cGMP signalling pathways. Yet limited and single PAH animal models may not corroborate the efficacy of natural medicines, and those natural compounds how to regulate crucial genes, proteins and even microRNA and lncRNA still need to put great attention. Additionally, pharmacokinetic studies and safety evaluation of natural medicines for the treatment of PAH should be undertaken in future studies. Meanwhile, methods for validating the efficacy of natural drugs in multiple PAH animal models and precise clinical design are also urgently needed to promote advances in PAH.

Hypoxia Induces Saturated Fatty Acids Accumulation and Reduces Unsaturated Fatty Acids Independently of Reverse Tricarboxylic Acid Cycle in L6 Myotubes

Obstructive sleep apnea syndrome, characterized by repetitive episodes of tissue hypoxia, is associated with several metabolic impairments. Role of fatty acids and lipids attracts attention in its pathogenesis for their metabolic effects. Parallelly, hypoxia-induced activation of reverse tricarboxylic acid cycle (rTCA) with reductive glutamine metabolism provides precursor molecules for de novo lipogenesis. Gas-permeable cultureware was used to culture L6-myotubes in chronic hypoxia (12%, 4% and 1% O₂) with ¹³C labelled glutamine and inhibitors of glutamine uptake or rTCA-mediated lipogenesis. We investigated changes in lipidomic profile, ¹³C appearance in rTCA-related metabolites, gene and protein expression of rTCA-related proteins and glutamine transporters, glucose uptake and lactate production. Lipid content increased by 308% at 1% O_2, predominantly composed of saturated fatty acids, while triacylglyceroles containing unsaturated fatty acids and membrane lipids (phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositol) decreased by 20-70%. rTCA labelling of malate, citrate and 2-hydroxyglutarate increased by 4.7-fold, 2.2-fold and 1.9-fold in 1% O₂, respectively. ATP-dependent citrate lyase inhibition in 1% O₂ decreased lipid amount by 23% and increased intensity of triacylglyceroles containing unsaturated fatty acids by 56-80%. Lactate production increased with hypoxia. Glucose uptake dropped by 75% with progression of hypoxia from 4% to 1% O₂. Protein expression remained unchanged. Altogether, hypoxia modified cell metabolism leading to lipid composition alteration and rTCA activation.