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Low dissolved oxygen (hypoxia) poses significant challenges to aquatic ecosystems, affecting the behavior, reproduction, and survival of aquatic organisms. Some fishes respond to hypoxia by changes in gene expression, which may be regulated by the hypoxia inducible factor (HIF) family of transcription factors. HIF abundance and activity depends upon the post-translational modification of the alpha protein subunit, although several studies indicate that HIFA mRNA abundance increases in tissues of fishes exposed to hypoxia. This study reviewed reports of laboratory exposures of adult ray-finned fishes to hypoxia and used generalized linear mixed effects models to examine the influence of HIFA gene, tissue sampled, and exposure conditions in explaining the diversity of responses seen in HIFA mRNA abundance. The frequency of hypoxia-induced increases in HIFA mRNA was poorly explained by gene, tissue, or the severity of the hypoxic exposure. Rather, the frequency of reported increases was strongly related to the extent to which studies adhered to guidelines for documenting quantitative real-time PCR methods: the frequency of hypoxia-induced increases in HIFA mRNA decreased sharply in studies with more thorough description of experimental design. Future research should (a) adhere to stringent reporting of experimental design, (b) address the relative paucity of data on HIF2A and HIF3A , and (c) determine levels of HIF alpha protein subunits. By following these recommendations, it is hoped that a more complete understanding will be gained of the role of the HIF family of transcription factors in the response of fish to hypoxia. [ABSTRACT FROM AUTHOR]

Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, characterized by the accumulation of amyloid-beta (Aβ) plaques and neuroinflammation. This study investigates the protective effects of noradrenaline (NA) on human microglial cells exposed to lipopolysaccharides (LPS) and Aβ aggregates—major contributors to inflammation and cellular damage in AD. The reduced Aβ aggregation in the HMC3 human microglial cells co-treated with Aβ and NA was confirmed by thioflavin T (ThT) assay, fluorescent ThT staining, and immunocytochemistry (ICC). The significantly increased viability of HMC3 cells after 48 h of incubation with NA at 50 µM, 25 µM, and 10 µM, exposed to IC50 LPS and IC50 Aβ, was confirmed by XTT and LDH assays. Moreover, we found that NA treatment at 25 μM and 50 μM concentrations in HMC3 cells exposed to IC50 LPS or IC50 Aβ results in an increased proliferation of HMC3 cells, their return to normal morphology, decreased levels of DNA damage, reduced caspase-3 activity, decreased expression of pro-apoptotic DDIT3 and BAX, and increased expression of anti-apoptotic BCL-2 genes and proteins, leading to enhanced cell survival, when compared to that of the HMC3 cells treated only with IC50 LPS or IC50 Aβ. Furthermore, we showed that NA induces the degradation of both extracellular and intracellular Aβ deposits and downregulates hypoxia-inducible factor 1α (HIF-1α), which is linked to impaired Aβ clearance and AD progression. These findings indicate that NA holds promise as a therapeutic target to address microglial dysfunction and potentially slow the progression of AD. Its neuroprotective effects, particularly in reducing inflammation and regulating microglial activity, warrant further investigation into its broader role in mitigating neuroinflammation and preserving microglial function in AD. [ABSTRACT FROM AUTHOR]

Roxadustat, an oral inhibitor of hypoxia-inducible factor prolyl hydroxylase domain enzymes, has been approved for the treatment of renal anemia. However, there is a lack of study on its pharmacokinetics in kidney transplant recipients (KTRs) with early posttransplant anemia (PTA). Therefore, the aim of this study is to elucidate the pharmacokinetic characteristics of roxadustat in KTRs with early PTA and optimize the dosing regimen. A population pharmacokinetic (PopPK) analysis was performed based on 72-hour full concentration-time profiles collected from 52 Chinese KTRs. Covariates influencing exposure were assessed using stepwise covariate modelling. Monte Carlo simulations were conducted to recommend the dosing regimen for patients with different levels of covariates. PopPK analysis showed that the concentration-time data can be fully described by a two-compartment model. Body weight (BW) and direct bilirubin (DBIL) levels significant affected the apparent clearance of roxadustat. Based on the established model and the estimated exposures of roxadustat by Monte Carlo simulations, a recommended dosing regimen for KTRs with early PTA at varying BW and DBIL levels were developed. Roxadustat at 100 mg three times weekly were suitable for the majority of KTRs with a DBIL level around 3 μmol/L and BW between 50 and 75 kg. The required dose may need to be increased with higher BW and lower DBIL levels, while decreased with lower BW and higher DBIL levels. It was the first PopPK analysis of roxadustat in KTRs with early PTA, which provide a research basis for optimizing the dosing regimen. [Display omitted] [ABSTRACT FROM AUTHOR]

To report the efficacy of the oral hypoxia-inducible factor 2α inhibitor belzutifan in participants with von Hippel-Lindau disease-associated retinal hemangioblastomas in the LITESPARK-004 study. Subgroup analysis of the phase 2, single-arm, open-label LITESPARK-004 study. Adults with 1 or more von Hippel-Lindau disease-associated measurable renal cell carcinoma tumors not requiring immediate surgical intervention were eligible. Participants received oral belzutifan 120 mg once daily until disease progression or unacceptable treatment-related toxicity. Efficacy of belzutifan in retinal hemangioblastomas was a secondary end point, measured as response (improved, stable, or progressed) by independent reading center-certified graders based on color fundus imaging performed every 12 weeks using the investigator's preferred imaging standards. Additional assessments, where available, included OCT and ultra-widefield fluorescein angiography. Among 61 participants in LITESPARK-004, 12 had 1 or more evaluable active retinal hemangioblastomas in 16 eyes at baseline per independent reading center. As of April 1, 2022, the median follow-up for participants with ocular von Hippel-Lindau disease at baseline was 37.3 months. All 16 eyes were graded as improved, with a response rate of 100.0% (95% confidence interval, 79.4%–100%). No new retinal hemangioblastomas or ocular disease progression were reported as of data cutoff date. Eight participants underwent additional multimodal eye assessments performed at the National Institutes of Health study site. Among this subgroup, 10 of 24 hemangioblastomas in 8 eyes of 6 participants measured 500 μm or more in greatest linear dimension at baseline and were analyzed further. All 10 hemangioblastomas had a mean area reduction of 15% or more by month 12 and of 30% or more by month 24. Belzutifan showed promising activity against ocular von Hippel-Lindau disease, including capacity to control retinal hemangioblastomas, with effects sustained for more than 2 years while treatment is ongoing. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factors (HIFs) play a pivotal role as master regulators of tumor survival and growth, controlling a wide array of cellular processes in response to hypoxic stress. Clinical data correlates upregulated HIF-1 and HIF-2 levels with an aggressive tumor phenotype and poor patient outcome. Despite extensive validation as a target in cancer, pharmaceutical targeting of HIFs, particularly the interaction between α and βsubunits that forms the active transcription factor, has proved challenging. Nonetheless, many indirect inhibitors of HIFs have been identified, targeting diverse parts of this pathway. Significant strides have also been made in the development of direct inhibitors of HIF-2, exemplified by the FDA approval of Belzutifan for the treatment of metastatic clear cell renal carcinoma. While efforts to target HIF-1 using various therapeutic modalities have shown promise, no clinical candidates have yet emerged. This review aims to provide insights into the intricate and extensive role played by HIFs in cancer, and the ongoing efforts to develop therapeutic agents against this target. [ABSTRACT FROM AUTHOR]

Background: Endometriosis, due to its ambiguous symptoms, still remains one of the most difficult female diseases to treat, with an average diagnosis time of 7–9 years. The changing level of hypoxia plays an important role in a healthy endometrium during menstruation and an elevated expression of the hypoxia-inducible factor 1-alpha (HIF-1α) has been demonstrated in ectopic endometria. HIF-1α mediates the induction of proangiogenic factors and the development of angiogenesis is a critical step in the establishment and pathogenesis of endometriosis. Although the inhibition of angiogenesis has been proposed as one of the actionable therapeutic modalities, vascular normalization and re-oxygenation may become a possible new approach for therapeutic intervention. Methods: Our goal was to investigate whether a selected murine model of endometriosis would be suitable for future studies on new methods for treating endometriosis. Non-invasive, high-resolution ultrasound-monitored observation was selected as the preclinical approach to obtain imaging of the presence and volume of the endometriotic-like lesions. The EF5 (2-(2-Nitro-1H-imidazol-1-yl)-N-(2,2,3,3,3-pentafluoropropyl)acetamide) compound that selectively binds to reduced proteins in hypoxic cells was used for hypoxia detection. The expression of Pten and other crucial genes linking endometriosis and hypoxia were also assessed. Results: Using EF5, a pentafluorinated derivative of the 2-nitroimidazole that is metabolically reduced by oxygen-inhibitable nitroreductase, we confirmed that hypoxia did develop in the selected model and was detected in uterine and ectopic endometriotic lesions. Moreover, the changes in oxygen tension also influenced the expression level of significant genes related to endometriosis, like Pten, Trp53, Hif1a, Epas1, and Vegfa. Their strong modulation evidenced here is indicative of model reliability. Using high-resolution ultrasound-based imaging, we present a non-invasive method of visualization that enables the detection and observation of lesion evolution throughout the duration of the experiment, which is fundamental for further preclinical studies and treatment evaluation. Conclusions: The selected model and method of visualization appear to be suitable for the study of new treatment strategies based on hypoxia alleviation and blood flow restoration. [ABSTRACT FROM AUTHOR]

Atherosclerosis (AS) poses a significant threat to human life and health. However, conventional antiatherogenic medications exhibit insufficient targeting precision and restricted therapeutic effectiveness. Moreover, during the progression of AS, macrophages undergo polarization toward the proinflammatory M1 phenotype and generate reactive oxygen species (ROS) to accelerate the occurrence of inflammatory storms, and ingest excess lipids to form foam cells by inhibiting cholesterol efflux. In our study, we developed a macrophage membrane-functionalized hollow mesoporous manganese dioxide nanomedicine (Col@HMnO2-MM). This nanomedicine has the ability to evade immune cell phagocytosis, enables prolonged circulation within the body, targets the inflammatory site of AS for effective drug release, and alleviates the inflammatory storm at the AS site by eliminating ROS. Furthermore, Col@HMnO2-MM has the ability to generate oxygen autonomously by breaking down surplus hydrogen peroxide generated at the inflammatory AS site, thereby reducing the hypoxic microenvironment of the plaque by downregulating hypoxia-inducible factor (HIF-1α), which in turn enhances cholesterol efflux to inhibit foam cell formation. In an APOE−/− mouse model, Col@HMnO2-MM significantly reduced inflammatory factor levels, lipid storage, and plaque formation without significant long-term toxicity. In summary, this synergistic treatment significantly improved the effectiveness of nanomedicine and may offer a novel strategy for precise AS therapy. [ABSTRACT FROM AUTHOR]

During inflammation, human neutrophils engage b2-integrins to migrate from the blood circulation to inflammatory sites with high cytokine but low oxygen concentrations. We tested the hypothesis that the inhibition of prolyl hydroxylase domain-containing enzymes (PHDs), cytokines, and b2-integrins cooperates in HIF pathway activation in neutrophils. Using either the PHD inhibitor roxadustat (ROX) (pseudohypoxia) or normobaric hypoxia to stabilize HIF, we observed HIF1a protein accumulation in adherent neutrophils. Several inflammatory mediators did not induce HIF1a protein but provided additive or even synergistic signals (e.g., GM-CSF) under pseudohypoxic and hypoxic conditions. Importantly, and in contrast to adherent neutrophils, HIF1a protein expression was not detected in strictly suspended neutrophils despite PHD enzyme inhibition and the presence of inflammatory mediators. Blocking b2- integrins in adherent and activating b2-integrins in suspension neutrophils established the indispensability of b2-integrins for increasing HIF1a protein. Using GM-CSF as an example, increased HIF1a mRNA transcription via JAK2- STAT3 was necessary but not sufficient for HIF1a protein upregulation. Importantly, we found that b2-integrins led to HIF1a mRNA translation through the phosphorylation of the essential translation initiation factors eIF4E and 4EBP1. Finally, pseudohypoxic and hypoxic conditions inducing HIF1a consistently delayed apoptosis in adherent neutrophils on fibronectin under low serum concentrations. Pharmacological HIF1a inhibition reversed delayed apoptosis, supporting the importance of this pathway for neutrophil survival under conditions mimicking extravascular sites. We describe a novel b2-integrincontrolled mechanism of HIF1a stabilization in human neutrophils. Conceivably, this mechanism restricts HIF1a activation in response to hypoxia and pharmacological PHD enzyme inhibitors to neutrophils migrating toward inflammatory sites. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factors (HIFs) are key transcriptional mediators of the hypoxic response and are implicated in oncogenesis. HIFα is regulated by a well-characterized, oxygen-dependent degradation pathway involving the von Hippel Lindau (VHL) tumor suppressor protein. However, comparatively little is known about HIFα regulation at the translational level, particularly under cellular stress. There is evidence that HIFα expression not only responds to changes in oxygen tension, but also nutrient availability. In this study, we monitored global translation rates, ATP levels and HIF1α synthesis rates in response to glucose starvation or glycolysis inhibition. We found that both global and HIF1α-specific translation rates decline under glucose deprivation that is concomitant with ATP reduction. These results are in contrast with previous reports showing preferential HIF1α synthesis despite global translation suppression under hypoxia and suggest that a glucose requirement in cellular metabolism is associated with HIF1α translation. [ABSTRACT FROM AUTHOR]

Background: Intracerebral hemorrhage (ICH) is a severe form of stroke characterized by high incidence and mortality rates. Currently, there is a significant lack of effective treatments aimed at improving clinical outcomes. Our research team has developed a three-dimensional (3D) biological scaffold that incorporates Bergenin, allowing for the sustained release of the compound. Methods: This 3D biological scaffold was fabricated using a combination of photoinitiator, GEMA, silk fibroin, and decellularized brain matrix (dECM) to encapsulate Bergenin through advanced 3D bioprinting techniques. The kinetics of drug release were evaluated through both in vivo and in vitro studies. A cerebral hemorrhage model was established, and a 3D biological scaffold containing Bergenin was transplanted in situ. Levels of inflammatory response, oxidative stress, and apoptosis were quantified. The neurological function of rats with cerebral hemorrhage was assessed on days 1, 3, and 5 using the turning test, forelimb placement test, Longa score, and Bederson score. Results: The 3D biological scaffold incorporating Bergenin significantly enhances the maintenance of drug concentration in the bloodstream, leading to a marked reduction in inflammatory markers such as IL-6, iNOS, and COX-2 levels in a cerebral hemorrhage model, primarily through the inhibition of the NF-κB pathway. Additionally, the scaffold effectively reduces the expression of hypoxia-inducible factor 1-alpha (HIF-1α) in primary cultured astrocytes, which in turn decreases the production of reactive oxygen species (ROS) and inhibits IL-6 production induced by hemin. Subsequent experiments reveal that the 3D biological scaffold containing Bergenin promotes the activation of the Nrf-2/HO-1 signaling pathway, both in vivo and in vitro, thereby preventing cell death. Moreover, the application of this 3D biological scaffold has been demonstrated to improve drug retention in the bloodstream. Conclusion: This strategy effectively mitigates inflammation, oxidative stress, and cell death in rats with cerebral hemorrhage by inhibiting the NF-κB pathway while concurrently activating the Nrf-2/HO-1 pathway. [ABSTRACT FROM AUTHOR]

Hepatocytes-like cells (HLC) derived from human induced pluripotent stem cells show great promise for cell-based liver therapies and disease modelling. However, their application is currently hindered by the low production yields of existing protocols. We aim to develop a bioprocess able to generate high numbers of HLC. We used stirred-tank bioreactors with a rational control of dissolved oxygen concentration (DO) for the optimization of HLC production as 3D aggregates. We evaluated the impact of controlling DO at physiological levels (4%O2) during hepatic progenitors' stage on cell proliferation and differentiation efficiency. Whole transcriptome analysis and biochemical assays were performed to provide a detailed characterization of HLC quality attributes. When DO was controlled at 4%O2 during the hepatic progenitors' stage, cells presented an upregulation of genes associated with hypoxia-inducible factor pathway and a downregulation of oxidative stress genes. This condition promoted higher HLC production (maximum cell concentration: 2 × 106 cell/mL) and improved differentiation efficiencies (80% Albumin-positive cells) when compared to the bioreactor operated under atmospheric oxygen levels (21%O2, 0.6 × 106 cell/mL, 43% Albumin positive cells). These HLC exhibited functional characteristics of hepatocytes: capacity to metabolize drugs, ability to synthesize hepatic metabolites, and inducible cytochrome P450 activity. Bioprocess robustness was confirmed with HLC derived from different donors, including a primary hyperoxaluria type 1 (PH1) patient. The generated PH1.HLC showed metabolic features of PH1 disease with higher secretion of oxalate compared with HLC generated from healthy individuals. This work reports a reproducible bioprocess, that shows the importance of controlling DO at physiological levels to increase HLC production, and the HLC capability to display PH1 disease features. [ABSTRACT FROM AUTHOR]

Peritoneal fibrosis has been linked to hypoxia-inducible factor 1-alpha (HIF-1α) as well as O-linked-N-acetylglucosaminylation (O-GlcNAcylation) in peritoneal dialysis (PD). Genistein, recognized for its HIF-1α inhibitory and antifibrotic effects, presents a potential intervention against peritoneal mesothelial-mesenchymal transition (MMT) as well as fibrosis in PD. This study employed human peritoneal mesothelial cells (HPMCs) together with adenine-induced chronic kidney disease (CKD) rats undergoing peritoneal dialysis to explore Genistein's role in high glucose-induced peritoneal MMT and fibrosis. Our findings reveal that Genistein exerts anti-MMT and anti-fibrotic effects by inhibiting HIF-1α in HPMCs under high glucose conditions. Genistein inhibited O-GlcNAcylation status of HIF-1α through the mTOR/O-GlcNAc transferase (OGT) pathway, promoting its ubiquitination as well as the subsequent proteasomal degradation. In adenine-induced CKD rats undergoing peritoneal dialysis, Genistein suppressed the mTOR/OGT expression and reduced the abundance of O-GlcNAcylation along with HIF-1α in the peritoneum. Additionally, Genistein protected against increased peritoneal thickness, fibrosis, and angiogenesis, while improving peritoneal function. Based on our results, it could be inferred that Genistein might inhibit the abundance of HIF-1α via the mTOR/OGT pathway, thereby ameliorating MMT as well as fibrosis in PD. [ABSTRACT FROM AUTHOR]

Simple Summary: This review examines the remarkable adaptations of high-altitude indigenous animals to hypoxic environments. It discusses the physiological and biochemical strategies employed by these animals to enhance O2 uptake and delivery, as well as to increase the efficiency of O2 utilization. Key adaptations in the pulmonary and cardiovascular systems, including increased lung volume, efficiency of blood–O2 exchange, and remodeling of pulmonary vasculature, are highlighted. Additionally, the review explores adaptations in O2-consuming tissues, focusing on enhanced mitochondrial function and altered metabolic pathways. The role of genetic factors, particularly the hypoxia-inducible factor (HIF) pathway, is emphasized, showcasing the convergence of evolution across different species. The manuscript concludes by emphasizing the importance of further research integrating various omics approaches and studying multiple tissues and organs to fully understand the complex mechanisms of high-altitude adaptation. Adaptation is one of the fundamental characteristics of life activities; humans and animals inhabiting high altitudes are well adapted to hypobaric hypoxic environments, and studies on the mechanisms of this adaptation emerged a hundred years ago. Based on these studies, this paper reviews the adaptive changes in hypoxia-sensitive tissues and organs, as well as at the molecular genetic level, such as pulmonary, cardiovascular, O2-consuming tissues, and the hemoglobin and HIF pathway, that occur in animals in response to the challenge of hypobaric hypoxia. High-altitude hypoxia adaptation may be due to the coordinated action of genetic variants in multiple genes and, as a result, adaptive changes in multiple tissues and organs at the physiological and biochemical levels. Unraveling their mechanisms of action can provide a reference for the prevention and treatment of multiple diseases caused by chronic hypoxia. [ABSTRACT FROM AUTHOR]

Background: Thyroid-associated ophthalmopathy (TAO) involves tissue expansion and inflammation, potentially causing a hypoxic microenvironment. Hypoxia-inducible factor (HIF)-1α is crucial in fibrosis and adipogenesis, which are observed in TAO progression. We investigated the effects of hypoxia on orbital fibroblasts (OFs) in TAO, focusing on the role of HIF-1α in TAO progression. Methods: OFs were isolated from TAO and non-TAO patients (as controls). In addition to HIF-1α, adipogenic differentiation markers including peroxisome proliferator-activated receptor γ (PPARγ) and CCAAT/enhancer binding protein (CEBP) were measured by Western blot, and phenotype changes were evaluated by Oil Red O staining under both normoxia and hypoxia. To elucidate the effect of HIF-1α inhibition, protein expression changes after HIF-1α inhibitor treatment were evaluated under normoxia and hypoxia. Results: TAO OFs exhibited significantly higher HIF-1α expression than non-TAO OFs, and the difference was more distinct under hypoxia than under normoxia. Oil Red O staining showed that adipogenic differentiation of TAO OFs was prominent under hypoxia. Hypoxic conditions increased the expression of adipogenic markers, namely PPARγ and CEBP, as well as HIF-1α in TAO OFs. Interleukin 6 levels also increased in response to hypoxia. The effect of hypoxia on adipogenesis was reduced at the protein level after HIF-1α inhibitor treatment, and this inhibitory effect was sustained even with IGF-1 stimulation in addition to hypoxia. Conclusion: Hypoxia induces tissue remodeling in TAO by stimulating adipogenesis through HIF-1α activation. These data could provide insights into new treatment strategies and the mechanisms of adipose tissue remodeling in TAO. [ABSTRACT FROM AUTHOR]

In hypoxic and pseudohypoxic rodent models of pulmonary hypertension (PH), hypoxia-inducible factor (HIF) inhibition attenuates disease initiation. However, HIF activation alone, due to genetic alterations or use of inhibitors of prolyl hydroxylase domain (PHD) enzymes, has not been definitively shown to cause PH in humans, indicating the involvement of other mechanisms. Given the association between endothelial cell dysfunction and PH, the effects of pseudohypoxia and its underlying pathways were investigated in primary human lung endothelial cells. PHD2 silencing or inhibition, while activating HIF2α, induced apoptosis-resistance and IFN/STAT activation in endothelial cells, independent of HIF signaling. Mechanistically, PHD2 deficiency activated AKT and ERK, inhibited JNK, and reduced AIP1 (ASK1-interacting protein 1), all independent of HIF2α. Like PHD2, AIP1 silencing affected these same kinase pathways and produced a similar dysfunctional endothelial cell phenotype, which was partially reversed by AKT inhibition. Consistent with these in vitro findings, AIP1 protein levels in lung endothelial cells were decreased in Tie2-Cre/Phd2 knockout mice compared with wild-type controls. Lung vascular endothelial cells from patients with pulmonary arterial hypertension (PAH) showed IFN/STAT activation. Lung tissue from both SU5416/hypoxia PAH rats and patients with PAH all showed AKT activation and dysregulated AIP1 expression. In conclusion, PHD2 deficiency in lung vascular endothelial cells drives an apoptosis-resistant and inflammatory phenotype, mediated by AKT activation and AIP1 loss independent of HIF signaling. Targeting these pathways, including PHD2, AKT, and AIP1, holds the potential for developing new treatments for endothelial dysfunction in PH. NEW & NOTEWORTHY: HIF activation alone does not conclusively lead to human PH, suggesting that HIF-independent signaling may also contribute to hypoxia-induced PH. This study demonstrated that PHD2 silencing-induced pseudohypoxia in human lung endothelial cells suppresses apoptosis and activates STAT, effects that persist despite HIF2α inhibition or knockdown and are attributed to AKT and ERK activation, JNK inhibition, and AIP1 loss. These findings align with observations in lung endothelial cells and tissues from PAH rodent models and patients. [ABSTRACT FROM AUTHOR]

The intestinal mucosa is a dynamic surface that facilitates interactions between the host and an outside world that includes trillions of microbes, collectively termed the microbiota. This fine balance is regulated by an energetically demanding physical and biochemical barrier that is formed by the intestinal epithelial cells. In addition, this homeostasis exists at an interface between the anaerobic colonic lumen and a highly oxygenated, vascularized lamina propria. The resultant oxygen gradient within the intestine establishes "physiologic hypoxia" as a central metabolic feature of the mucosa. Although oxygen is vital for energy production to meet cellular metabolism needs, the availability of oxygen has far-reaching influences beyond just energy provision. Recent studies have shown that the intestinal mucosa has purposefully adapted to use differential oxygen levels largely through the presence of short-chain fatty acids (SCFAs), particularly butyrate (BA). Intestinal epithelial cells use butyrate for a multitude of functions that promote mucosal homeostasis. In this review, we explore how the physiologic hypoxia profile interfaces with SCFAs to benefit host mucosal tissues. [ABSTRACT FROM AUTHOR]

Tissues often experience hypoxia at sites of inflammation due to malperfusion, massive immune cell recruitment, and increased oxygen consumption. Organisms adapt to these hypoxic conditions through the transcriptional activation of various genes. In fact, there is significant crosstalk between the transcriptional responses to hypoxia and inflammatory processes. This interaction, named inflammatory hypoxia, plays a crucial role in various diseases including malignancies, chronic inflammatory lung diseases, and sepsis. To further elucidate the crosstalk between hypoxia and inflammation in vivo and assess its potential for innovative therapies, our study aimed at investigating the impact of acute hypoxic conditions on inflammation-induced immune responses. To this end, we exposed healthy human subjects to hypoxia either before (hypoxia priming) or after a single intravenous (i.v.) injection of 0.4 ng/kg LPS. Our data show that hypoxia exposure prior to LPS injection (hypoxia priming) amplified the proinflammatory response. This was reflected by an increase in body temperature, plasma noradrenaline levels, and the production of proinflammatory cytokines (i.e., IL-6 and TNF-α), compared with LPS control conditions. These effects were not observed when participants were exposed to hypoxia after LPS administration, demonstrating that the interaction between hypoxia and inflammation highly depends on the timing of both stimuli. Our findings suggest that acute hypoxia (i.e., hypoxia priming) modulates transient inflammation, leading to an enhanced proinflammatory response in healthy human subjects. This highlights the need for further investigations to understand the pathology of various hypoxia-inducible factor (HIF)-associated inflammatory diseases and to develop suitable, innovative therapies. NEW & NOTEWORTHY: To our knowledge, this is the first in vivo study investigating the effects of hypoxia preceding (hypoxia priming) or following LPS administration on the endotoxin-induced inflammatory response in healthy human subjects. The data show that hypoxia priming amplified the proinflammatory response, reflected by an increased body temperature, increased plasma noradrenaline levels, and higher production of proinflammatory cytokines (i.e., IL-6 and TNF-α) compared with LPS control conditions. [ABSTRACT FROM AUTHOR]

To highlight the neurosurgical implications of the hypoxia-inducible factor-2α- targeting agent belzutifan in the management of both von-Hippel Lindau (VHL)-associated and sporadic hemangioblastomas (HBLs). The literature was queried for VHL, HBLs, and belzutifan. A summary of recent uses of belzutifan and currently ongoing clinical trials that are investigating the use of belzutifan in the treatment of HBLs is presented. VHL disease occurs as a result of germline mutations in the VHL tumor suppressor gene on chromosome 3p25-p26, leading to growth of benign and malignant tumors such as HBLs. The possibility of intermittent growth in HBLs indicates that it is important to avoid hasty surgical interventions. Belzutifan is the first nonsurgical food and drug administration-approved treatment for VHL disease-related tumors that may delay or circumvent the need for surgery or radiation therapy by inhibiting HIF-2α, an important component of cellular hypoxic response. There is limited real-world experience of belzutifan in patients with HBLs as a primary indication, though there are 2 phase II clinical trials investigating the use of belzutifan in the treatment of HBLs. There is limited experience regarding the use of belzutifan for CNS hemangioblastoma. While its application has been limited to a small group of clinical cases, it has exhibited significant efficacy in reducing the size and consequences of HBLs. Based on the promising outcomes observed in individual patient experiences and ongoing clinical trials, we infer that further exploration and integration of belzutifan into neurosurgical treatment plans for both sporadic and VHL-associated HBLs are warranted. [ABSTRACT FROM AUTHOR]

Anaemia is a common complication of chronic kidney disease (CKD) and is associated with poor long-term outcomes and quality of life. The use of supplemental iron, erythropoiesis-stimulating agents (ESAs) and blood transfusions has been the mainstay for treatment of anaemia in CKD for more than 3 decades. Despite available treatments, CKD patients with anaemia are undertreated and moderate–severe anaemia remains prevalent in the CKD population. Anaemia has consistently been associated with greater mortality, hospitalization, cardiovascular events and CKD progression in CKD patients, and the risk increases with anaemia severity. Hypoxia-inducible factor (HIF) prolyl hydroxylase (PH) inhibitors have a novel mechanism of action by mimicking the body's response to hypoxia and have emerged as an alternative to ESAs for treatment of anaemia in CKD. Their efficacy in correcting and maintaining haemoglobin has been demonstrated in >30 phase 3 clinical trials. Additionally, HIF activation results in various pleiotropic effects beyond erythropoiesis, with cholesterol reduction and improved iron homeostasis and potential anti-inflammatory effects. The long-term safety of these agents, particularly with respect to cardiovascular and thromboembolic events, and their possible effect on tumour growth needs to be fully elucidated. This article presents in detail the effects of HIF-PH inhibitors, describes their mechanisms of action and pharmacologic properties and discusses their place in the treatment of anaemia in CKD according to the available evidence. [ABSTRACT FROM AUTHOR]

Cisplatin is a widely used, highly effective chemotherapy drug that has a critical nephrotoxic side effect associated with acute kidney injury. Hypoxia pre-treatment is one of the methods used to reduce cisplatin-induced renal toxicity, but the exact cellular process associated with this protective effect is not clearly understood. Hypoxia-inducible factor 1 alpha (HIF-1α), the main transcription factor under hypoxia, may play a crucial role in this protective effect. To verify this, the degree of HIF-1α activation was investigated. Renal proximal tubular epithelial cells (HK-2) were treated with cisplatin following exposure to FG-4592 and CoCl2, prolyl hydroxylase domain (PHD) inhibitors that stabilize HIF-1α. Roxadustat (FG-4592) is a PHD inhibitor recently approved by the European medicines agency (EMA) for the treatment of anemia. Hypoxia pre-treatment with PHD inhibitors presented a protective effect against cisplatin-induced kidney injury. In addition, hypoxia pre-treatment relieved oxidative stress by hypoxia response genes sufficiently expressed under hypoxic pre-conditions. In conclusion, we investigated the correlation between the degree of HIF-1α pre-activation and the reduction in cisplatin-induced nephrotoxicity using PHD inhibitors. This study extends the applicability of PHD inhibitors as palliators of cisplatin-induced nephrotoxicity and provides valuable insights into overcoming the limitations of cisplatin use. [ABSTRACT FROM AUTHOR]

Sevoflurane is shown to curtail lung cancer (LC) development. Herein, this research sought to investigate the underlying mechanism of sevoflurane in regard to its repressive effects on LC. Expression levels of microRNA (miR)-153-3p, HIF1α, and KDM2B in LC tissues and cells were determined with qRT-PCR. Following sevoflurane pretreatment and/or ectopic expression and knockdown experiments, the malignant phenotypes, and levels of miR-153-3p, HIF1α, and KDM2B in LC A549 cells were detected using Transwell, scratch, EdU, CCK-8, Western blot, and qRT-PCR assays. Relationship between HIF1α and miR-153-3p was verified with a dual-luciferase reporter assay. The interaction between HIF1α and KDM2B was verified with a ChIP assay. LC tissues and cells presented low miR-153-3p expression and high HIF1α and KDM2B expression. Sevoflurane pretreatment, miR-153-3p upregulation, HIF1α downregulation, or KDM2B downregulation impeded the malignant phenotypes of A549 cells. Sevoflurane pretreatment augmented miR-153-3p expression, while miR-153-3p negatively targeted HIF1α. HIF1α bound to the KDM2B promoter to upregulate KDM2B. HIF1α or KDM2B overexpression counteracted the inhibitory effects of sevoflurane pretreatment on A549 cell malignant behaviors. Sevoflurane decreased HIF1α expression through upregulation of miR-153-3p, thereby reducing KDM2B transcription to restrict the malignant phenotypes of LC A549 cells. [ABSTRACT FROM AUTHOR]

Aim: The primary endothelial NADPH oxidase isoform 4 (NOX4) is notably induced during hypoxia, with emerging evidence suggesting its vasoprotective role through H2O2 production. Therefore, we aimed to elucidate NOX4′s significance in endothelial function under hypoxia. Methods: Human vessels, in addition to murine vessels from Nox4−/− mice, were explored. On a functional level, Mulvany myograph experiments were performed. To obtain mechanistical insights, human endothelial cells were cultured under hypoxia with inhibitors of hypoxia-inducible factors. Additionally, endothelial cells were cultured under combined hypoxia and laminar shear stress conditions. Results: In human occluded vessels, NOX4 expression strongly correlated with prostaglandin I2 synthase (PTGIS). Hypoxia significantly elevated NOX4 and PTGIS expression and activity in human endothelial cells. Inhibition of prolyl hydroxylase domain (PHD) enzymes, which stabilize hypoxia-inducible factors (HIFs), increased NOX4 and PTGIS expression even under normoxic conditions. NOX4 mRNA expression was reduced by HIF1a inhibition, while PTGIS mRNA expression was only affected by the inhibition of HIF2a under hypoxia. Endothelial function assessments revealed hypoxia-induced endothelial dysfunction in mesenteric arteries from wild-type mice. Mesenteric arteries from Nox4−/− mice exhibited an altered endothelial function under hypoxia, most prominent in the presence of cyclooxygenase inhibitor diclofenac to exclude the impact of prostacyclin. Restored protective laminar shear stress, as it might occur after thrombolysis, angioplasty, or stenting, attenuated the hypoxic response in endothelial cells, reducing HIF1a expression and its target NOX4 while enhancing eNOS expression. Conclusions: Hypoxia strongly induces NOX4 and PTGIS, with a close correlation between both factors in occluded, hypoxic human vessels. This relationship ensured endothelium-dependent vasodilation under hypoxic conditions. Protective laminar blood flow restores eNOS expression and mitigates the hypoxic response on NOX4 and PTGIS. [ABSTRACT FROM AUTHOR]

Mesenchymal stem/stromal cells (MSCs) have emerged as a promising tool in the field of regenerative medicine due to their unique therapeutic properties as they can differentiate into multiple cell types and exert paracrine effects. However, despite encouraging results obtained in preclinical studies, clinical trials have not achieved the same levels of efficacy. To improve the therapeutic properties of MSCs, several strategies have been explored. Therefore, in this review, the therapeutic properties of MSCs will be analyzed, and an update and overview of the most prominent approaches used to enhance their therapeutic capabilities will be provided. These approaches include using drugs, molecules, strategies based on biomaterials, and modification parameters in culture. The strategy described shows several common factors among those affected by these strategies that lead to an enhancement of the MSCs therapeutic properties such as the activation of the PI3K/AKT pathway and the increased expression of Heat Shock Proteins and Hypoxia-Inducible Factor. The combined effect of these elements shift MSCs towards a glycolytic state, suggesting this shift is essential for their enhancement. [ABSTRACT FROM AUTHOR]

Hypoxia-inducible factors (HIFs) are transcriptional factors that function as strong regulators of oxygen homeostasis and cellular metabolisms. The maintenance of cellular oxygen levels is critical as either insufficient or excessive oxygen affects development and physiologic and pathologic conditions. In the eye, retinas have a high metabolic demand for oxygen. Retinal ischemia can cause visual impairment in various sight-threating disorders including age-related macular degeneration, diabetic retinopathy, and some types of glaucoma. Therefore, understanding the potential roles of HIFs in the retina is highly important for managing disease development and progression. This review focuses on the physiologic and pathologic roles of HIFs as regulators of oxygen homeostasis and cellular metabolism in the retina, drawing on recent evidence. Our summary will promote comprehensive approaches to targeting HIFs for therapeutic purposes in retinal diseases. [ABSTRACT FROM AUTHOR]

The study of transcription factors that determine specialized neuronal functions has provided invaluable insights into the physiology of the nervous system. Peripheral chemoreceptors are neurone-like electrophysiologically excitable cells that link the oxygen concentration of arterial blood to the neuronal control of breathing. In the adult, this oxygen chemosensitivity is exemplified by type I cells of the carotid body, and recent work has revealed one isoform of the hypoxia-inducible transcription factor (HIF), HIF-2α, as having a nonredundant role in the development and function of that organ. Here, we show that activation of HIF-2α, including isolated overexpression of HIF-2α but not HIF-1α, is sufficient to induce oxygen chemosensitivity in adult adrenal medulla. This phenotypic change in the adrenal medulla was associated with retention of extra-adrenal paraganglioma-like tissues resembling the fetal organ of Zuckerkandl, which also manifests oxygen chemosensitivity. Acquisition of chemosensitivity was associated with changes in the adrenal medullary expression of gene classes that are ordinarily characteristic of the carotid body, including G protein regulators and atypical subunits of mitochondrial cytochrome oxidase. Overall, the findings suggest that, at least in certain tissues, HIF-2α acts as a phenotypic driver for cells that display oxygen chemosensitivity, thus linking 2 major oxygen-sensing systems. [ABSTRACT FROM AUTHOR]

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Prolyl-hydroxylation is an oxygen-dependent posttranslational modification (PTM) that is known to regulate fibril formation of collagenous proteins and modulate cellular expression of hypoxia-inducible factor (HIF) α subunits. However, our understanding of this important but relatively rare PTM has remained incomplete due to the lack of biophysical methodologies that can directly measure multiple prolyl-hydroxylation events within intrinsically disordered proteins. Here, we describe a real-time 13C-direct detection NMR-based assay for studying the hydroxylation of two evolutionarily conserved prolines (P402 and P564) simultaneously in the intrinsically disordered oxygen-dependent degradation domain of hypoxic-inducible factor 1α by exploiting the "proton-less" nature of prolines. We show unambiguously that P564 is rapidly hydroxylated in a time-resolved manner while P402 hydroxylation lags significantly behind that of P564. The differential hydroxylation rate was negligibly influenced by the binding affinity to prolyl-hydroxylase enzyme, but rather by the surrounding amino acid composition, particularly the conserved tyrosine residue at the +1 position to P564. These findings support the unanticipated notion that the evolutionarily conserved P402 seemingly has a minimal impact in normal oxygen-sensing pathway. [ABSTRACT FROM AUTHOR]

Metabolic imbalance leading to inflammatory hypoxia and stabilization of hypoxia-inducible transcription factors (HIFs) is a hallmark of inflammatory bowel diseases. We hypothesize that HIF could be stabilized in CD4+ T cells during intestinal inflammation and alter the functional responses of T cells via regulation of microRNAs. Our assays reveal markedly increased T cell-intrinsic hypoxia and stabilization of HIF protein during experimental colitis. microRNA screen in primary CD4+ T cells points us towards miR-29a and our subsequent studies identify a selective role for HIF-2α in CD4-cell-intrinsic induction of miR-29a during hypoxia. Mice with T cell-intrinsic HIF-2α deletion display elevated T-bet (target of miR-29a) levels and exacerbated intestinal inflammation. Mice with miR-29a deficiency in T cells show enhanced intestinal inflammation. T cell-intrinsic overexpression of HIF-2α or delivery of miR-29a mimetic dampen TH1-driven colitis. In this work, we show a previously unrecognized function for hypoxia-dependent induction of miR-29a in attenuating TH1-mediated inflammation. Inflammatory intestinal lesions are often hypoxic, which results in the stabilization and activation of hypoxia-inducible-factors (HIF). Here authors show that in a mouse model of colitis, HIF-2α is specifically stabilized in CD4+ type 1T helper (TH1) cells, leading to the upregulation of miR-29a expression and suppression of TH1 cell function, which pathway is potentially targetable for therapeutic purposes. [ABSTRACT FROM AUTHOR]

Proinflammatory hepatic macrophage activation plays a key role in the development of nonalcoholic steatohepatitis (NASH). This involves increased embryonic hepatic Kupffer cell (KC) death, facilitating the replacement of KCs with bone marrow–derived recruited hepatic macrophages (RHMs) that highly express proinflammatory genes. Moreover, phago/efferocytic activity of KCs is diminished in NASH, enhancing liver inflammation. However, the molecular mechanisms underlying these changes in KCs are not known. Here, we show that hypoxia-inducible factor 2α (HIF-2α) mediates NASH-associated decreased KC growth and efferocytosis by enhancing lysosomal stress. At the molecular level, HIF-2α stimulated mammalian target of rapamycin (mTOR)– and extracellular signal–regulated kinase-dependent inhibitory transcription factor EB (TFEB) phosphorylation, leading to decreased lysosomal and phagocytic gene expression. With increased metabolic stress and phago/efferocytic burden in NASH, these changes were sufficient to increase lysosomal stress, causing decreased efferocytosis and lysosomal cell death. Of interest, HIF-2α–dependent TFEB regulation only occurred in KCs but not RHMs. Instead, in RHMs, HIF-2α promoted mitochondrial reactive oxygen species production and proinflammatory activation by increasing ANT2 expression and mitochondrial permeability transition. Consequently, myeloid lineage–specific or KC-specific HIF-2α depletion or the inhibition of mTOR-dependent TFEB inhibition using antisense oligonucleotide treatment protected against the development of NASH in mice. Moreover, treatment with an HIF-2α–specific inhibitor reduced inflammatory and fibrogenic gene expression in human liver spheroids cultured under a NASH-like condition. Together, our results suggest that macrophage subtype–specific effects of HIF-2α collectively contribute to the proinflammatory activation of liver macrophages, leading to the development of NASH. Editor's summary: Abberant hepatic macrophage activity has been implicated in NASH development, but the mechanism of this immune dysregulation is unclear. Jeelani et al. show that a hypoxia-inducible factor, HIF-2α, promotes differential effects on macrophage subpopulations during NASH in obesity. HIF-2α suppressed the growth and function of endogenous liver macrophages (Kupffer cells) but increased the proinflammatory activation of the myeloid-derived macrophages that are subsequently recruited to the liver and that start to replace the Kupffer cells. HIF-2α–specific approaches in a murine NASH model and human organoids suggested that this disease biology may be therapeutically targetable. —Catherine Charneski [ABSTRACT FROM AUTHOR]

While adoptive cell therapy has shown success in hematological malignancies, its potential against solid tumors is hindered by an immunosuppressive tumor microenvironment (TME). In recent years, members of the hypoxia-inducible factor (HIF) family have gained recognition as important regulators of T-cell metabolism and function. The role of HIF signalling in activated CD8 T cell function in the context of adoptive cell transfer, however, has not been explored in full depth. Here we utilize CRISPR-Cas9 technology to delete prolyl hydroxylase domain-containing enzymes (PHD) 2 and 3, thereby stabilizing HIF-1 signalling, in CD8 T cells that have already undergone differentiation and activation, modelling the T cell phenotype utilized in clinical settings. We observe a significant boost in T-cell activation and effector functions following PHD2/3 deletion, which is dependent on HIF-1α, and is accompanied by an increased glycolytic flux. This improvement in CD8 T cell performance translates into an enhancement in tumor response to adoptive T cell therapy in mice, across various tumor models, even including those reported to be extremely resistant to immunotherapeutic interventions. These findings hold promise for advancing CD8 T-cell based therapies and overcoming the immune suppression barriers within challenging tumor microenvironments. The hypoxia inducible factor HIF-1α has been shown to regulate T cell metabolism and function. Here authors deleted the prolyl hydroxylase domain-containing enzymes PHD2 and 3, thereby stabilizing HIF-1α, in therapeutic CD8 T cells to achieve better functionality upon adoptive transfer to tumour-bearing mice. [ABSTRACT FROM AUTHOR]

The ubiquitination and proteasome-mediated degradation of Hypoxia Inducible Factors (HIFs) is central to metazoan oxygen-sensing, but the involvement of deubiquitinating enzymes (DUBs) in HIF signalling is less clear. Here, using a bespoke DUBs sgRNA library we conduct CRISPR/Cas9 mutagenesis screens to determine how DUBs are involved in HIF signalling. Alongside defining DUBs involved in HIF activation or suppression, we identify USP43 as a DUB required for efficient activation of a HIF response. USP43 is hypoxia regulated and selectively associates with the HIF-1α isoform, and while USP43 does not alter HIF-1α stability, it facilitates HIF-1 nuclear accumulation and binding to its target genes. Mechanistically, USP43 associates with 14-3-3 proteins in a hypoxia and phosphorylation dependent manner to increase the nuclear pool of HIF-1. Together, our results highlight the multifunctionality of DUBs, illustrating that they can provide important signalling functions alongside their catalytic roles. Synopsis: Hypoxia-inducible transcription Factors (HIFs) are central to the metazoan response to oxygen. This work reveals that USP43, a deubiquitinating enzyme (DUB), is required for activation of the HIF-1 response by facilitating HIF-1 nuclear accumulation. CRISPR/Cas9 mutagenesis screens uncover DUBs involved in HIF regulation and identify USP43 as a DUB required for activation of a HIF-1 response. USP43 associates with HIF-1α through the hypoxia-sensitive recruitment of 14-3-3 proteins and increases the nuclear accumulation of HIF-1α within minutes of hypoxia. USP43 is a catalytically active DUB, but its enzymatic activity is not essential for accumulation of HIF-1 on chromatin. The association of USP43 with 14-3-3 proteins and HIF-1 is dependent on hypoxia-induced serine phosphorylation of USP43. USP43 promotes HIF-1 nuclear accumulation by forming a complex with HIF-1alpha and 14-3-3 proteins in low oxygen. [ABSTRACT FROM AUTHOR]

Citrullination plays an essential role in various physiological or pathological processes, however, whether citrullination is involved in regulating tumour progression and the potential therapeutic significance have not been well explored. Here, we find that peptidyl arginine deiminase 4 (PADI4) directly interacts with and citrullinates hypoxia-inducible factor 1α (HIF-1α) at R698, promoting HIF-1α stabilization. Mechanistically, PADI4-mediated HIF-1αR698 citrullination blocks von Hippel-Lindau (VHL) binding, thereby antagonizing HIF-1α ubiquitination and subsequent proteasome degradation. We also show that citrullinated HIF-1αR698, HIF-1α and PADI4 are highly expressed in hepatocellular carcinoma (HCC) tumour tissues, suggesting a potential correlation between PADI4-mediated HIF-1αR698 citrullination and cancer development. Furthermore, we identify that dihydroergotamine mesylate (DHE) acts as an antagonist of PADI4, which ultimately suppresses tumour progression. Collectively, our results reveal citrullination as a posttranslational modification related to HIF-1α stability, and suggest that targeting PADI4-mediated HIF-1α citrullination is a promising therapeutic strategy for cancers with aberrant HIF-1α expression. Post-translational modifications on HIF-1α can regulate its stability and activity in tumoral processes. Here, the authors show that PADI4-mediated citrullination avoids HIF-1α degradation to promote hepatocellular carcinoma progression and this can be prevented by a PADI4 antagonist [ABSTRACT FROM AUTHOR]

Transcription factors are challenging to target with smallmolecule inhibitors due to their structural plasticity and lack of catalytic sites. Notable exceptions include naturally ligandregulated transcription factors, including our prior work with the hypoxia-inducible factor (HIF)-2 transcription factor, showing that small-molecule binding within an internal pocket of the HIF-2a Per-Aryl hydrocarbon Receptor Nuclear Translocator (ARNT)-Sim (PAS)-B domain can disrupt its interactions with its dimerization partner, ARNT. Here, we explore the feasibility of targeting small molecules to the analogous ARNT PAS-B domain itself, potentially opening a promising route to modulate several ARNT-mediated signaling pathways. Using solution NMR fragment screening, we previously identified several compounds that bind ARNT PAS-B and, in certain cases, antagonize ARNT association with the transforming acidic coiled-coil containing protein 3 transcriptional coactivator. However, these ligands have only modest binding affinities, complicating characterization of their binding sites. We address this challenge by combining NMR, molecular dynamics simulations, and ensemble docking to identify ligand-binding “hotspots” on and within the ARNT PAS-B domain. Our data indicate that the two ARNT/transforming acidic coiled-coil containing protein 3 inhibitors, KG548 and KG-655, bind to a b-sheet surface implicated in both HIF-2 dimerization and coactivator recruitment. Furthermore, while KG-548 binds exclusively to the b-sheet surface, KG-655 can additionally bind within a water-accessible internal cavity in ARNT PAS-B. Finally, KG-279, while not a coactivator inhibitor, exemplifies ligands that preferentially bind only to the internal cavity. All three ligands promoted ARNT PAS-B homodimerization, albeit to varying degrees. Taken together, our findings provide a comprehensive overview of ARNT PASB ligand-binding sites and may guide the development of more potent coactivator inhibitors for cellular and functional studies. [ABSTRACT FROM AUTHOR]

Background and Objective: Daprodustat is a first-in-class hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI) approved in the USA for treatment of anemia owing to chronic kidney disease (CKD) in dialysis-dependent adults and in Japan for treatment of CKD in dialysis- and non-dialysis dependent adults. This analysis characterized the population pharmacokinetics (PopPK) of daprodustat in adults with CKD and evaluated the influence of intrinsic and extrinsic factors. Methods: This PopPK analysis included data from one phase 2B and four phase 3 studies comprising 707 CKD subjects dose titrated to prespecified target hemoglobin levels with daprodustat doses ranging from 1 to 24 mg once daily and 2 to 48 mg given three times a week (TIW). Model development leveraged a previous phase 1/2 PopPK model. Stepwise covariate analysis included 20 extrinsic and intrinsic factors. Model evaluation used standard goodness-of-fit and visual predictive checks. Results: Daprodustat PopPK was adequately characterized using a three-compartment distribution model with first-order elimination. The absorption phase was described using five transit compartments. Oral clearance and volume of distribution was 24.6 L/h and 26.9 L, respectively. Body weight dependence (with fixed allometric coefficients) of clearance and volume terms was a statistically significant covariate. Concomitant use of clopidogrel (moderate CYP2C8 inhibitor) decreased oral clearance, resulting in higher area under the plasma concentration-time curve (AUC) ratio of 1.59 (90% CI: 1.39–1.82), subjects' dialysis status (non-dialysis versus dialysis) had an effect on absorption, with Cmax ratio of 1.19 (90% CI: 1.09–1.30). None of the other investigated intrinsic or extrinsic covariates, including concomitant administration with phosphate binders, oral iron and acid reducing agents resulted in a significant change in daprodustat systemic exposure. Conclusion: The PopPK of daprodustat in the CKD population with anemia was adequately characterized. Allometrically-scaled body weight on clearance and volume, dialysis status on absorption and clopidogrel on clearance were statistically significant covariates. [ABSTRACT FROM AUTHOR]

Low dissolved oxygen (hypoxia) is recognized as a major threat to aquatic ecosystems worldwide. Because oxygen is paramount for the energy metabolism of animals, understanding the functional and genetic drivers of whole-animal hypoxia tolerance is critical to predicting the impacts of aquatic hypoxia. In this study, we investigate the molecular evolution of key genes involved in the detection of and response to hypoxia in ray-finned fishes: the prolyl hydroxylase domain (PHD)–hypoxia-inducible factor (HIF) oxygen-sensing system, also known as the EGLN (egg-laying nine)– HIF oxygen-sensing system. We searched fish genomes for HIFA and EGLN genes, discovered new paralogs from both gene families, and analyzed protein-coding sites under positive selection. The physicochemical properties of these positively selected amino acid sites were summarized using linear discriminants for each gene. We employed phylogenetic generalized least squares to assess the relationship between these linear discriminants for each HIFA and EGLN and hypoxia tolerance as reflected by the critical oxygen tension (P crit) of the corresponding species. Our results demonstrate that P crit in ray-finned fishes correlates with the physicochemical variation of positively selected sites in specific HIFA and EGLN genes. For HIF2A , two linear discriminants captured more than 90% of the physicochemical variation of these sites and explained between 20% and 39% of the variation in P crit. Thus, variation in HIF2A among fishes may contribute to their capacity to cope with aquatic hypoxia, similar to its proposed role in conferring tolerance to high-altitude hypoxia in certain lineages of terrestrial vertebrates. [ABSTRACT FROM AUTHOR]

PHD1 is a member of the prolyl hydroxylase domain protein (PHD1–4) family, which plays a prominent role in the post-translational modification of its target proteins by hydroxylating proline residues. The best-characterized targets of PHD1 are hypoxia-inducible factor α (HIF-1α and HIF-2α), two master regulators of the hypoxia signaling pathway. In this study, we show that zebrafish phd1 positively regulates mavs-mediated antiviral innate immunity. Overexpression of phd1 enhances the cellular antiviral response. Consistently, zebrafish lacking phd1 are more susceptible to spring viremia of carp virus infection. Further assays indicate that phd1 interacts with mavs through the C-terminal transmembrane domain of mavs and promotes mavs aggregation. In addition, zebrafish phd1 attenuates K48-linked polyubiquitination of mavs, leading to stabilization of mavs. However, the enzymatic activity of phd1 is not required for phd1 to activate mavs. In conclusion, this study reveals a novel function of phd1 in the regulation of antiviral innate immunity. IMPORTANCE PHD1 is a key regulator of the hypoxia signaling pathway, but its role in antiviral innate immunity is largely unknown. In this study, we found that zebrafish phd1 enhances cellular antiviral responses in a hydroxylation-independent manner. Phd1 interacts with mavs through the C-terminal transmembrane domain of mavs and promotes mavs aggregation. In addition, phd1 attenuates K48-linked polyubiquitination of mavs, leading to stabilization of mavs. Zebrafish lacking phd1 are more susceptible to spring viremia of carp virus infection. These findings reveal a novel role for phd1 in the regulation of mavs-mediated antiviral innate immunity. [ABSTRACT FROM AUTHOR]

Articular cartilage receives nutrients and oxygen from the synovial fluid to maintain homeostasis. However, compared to tissues with abundant blood flow, articular cartilage is exposed to a hypoxic environment (i.e., physioxia) and has an enhanced hypoxic stress response. Hypoxia-inducible factors (HIFs) play a pivotal role in this physioxic environment. In normoxic conditions, HIFs are downregulated, whereas in physioxic conditions, they are upregulated. The HIF-α family comprises three members: HIF-1α, HIF-2α, and HIF-3α. Each member has a distinct function in articular cartilage. In osteoarthritis, which is primarily caused by degeneration of articular cartilage, HIF-1α is upregulated in chondrocytes and is believed to protect articular cartilage by acting anabolically on it. Conversely, in contrast to HIF-1α, HIF-2α exerts a catabolic influence on articular cartilage. It may therefore be possible to develop a new treatment for OA by controlling the expression of HIF-1α and HIF-2α with drugs or by altering the oxygen environment in the joints. [ABSTRACT FROM AUTHOR]

Simple Summary: Intermittent and chronic hypoxia are common and harmful to marine animals. The tiger puffer is a representative species of the family Tetraodontidae, which has only slit-like gill openings and is susceptible to hypoxia stress. Both intermittent and chronic hypoxia decrease the growth and visceral weight of tiger puffer but increase the feed conversion ratio and blood hemoglobin content. Chronic hypoxia but not intermittent hypoxia promoted protein synthesis and the glycolysis pathway. Intermittent hypoxia but not chronic hypoxia decreased lipid synthesis and monounsaturated fatty acids content but increased n-3 polyunsaturated fatty acids levels. These changes promoted the adaption of tiger puffer to intermittent and chronic hypoxia. Intermittent and chronic hypoxia are common stresses to marine fish, but the different responses of fish to intermittent and chronic hypoxia have not been well-known. In this study, tiger puffers were farmed in normoxia conditions (NO, 6.5 ± 0.5 mg/L), intermittent hypoxia (IH, 6.5 ± 0.5 mg/L in the day and 3.5 ± 0.5 mg/L in the night), or choric hypoxia (CH, 3.5 ± 0.5 mg/L) conditions for 4 weeks, after which the growth, nutrient metabolism and three hifα isoforms expression were measured. Both intermittent and chronic hypoxia decreased the fish growth and visceral weight but increased the feed conversion ratio and blood hemoglobin content. Chronic hypoxia but not intermittent hypoxia promoted protein synthesis and whole-fish protein content by activating mtor gene expression and promoted the glycolysis pathway by activating gene expression of hif1α and hif2α. Intermittent hypoxia but not chronic hypoxia decreased the hepatic lipid synthesis by inhibiting fasn and srebf1 gene expression. Meanwhile, intermittent hypoxia reduced the monounsaturated fatty acid content but increased the n-3 polyunsaturated fatty acids percentage. The results of this study clarified the adaptive mechanism of tiger puffer to intermittent and chronic hypoxia, which provides important information about mechanisms of hypoxia adaption in fish. [ABSTRACT FROM AUTHOR]

Hypoxia is relevant to several physiological and pathological processes and this also applies for the tooth. The adaptive response to lowering oxygen concentration is mediated by hypoxia-inducible factors (HIFs). Since HIFs were shown to participate in the promotion of angiogenesis, stem cell survival, odontoblast differentiation and dentin formation, they may play a beneficial role in the tooth reparative processes. Although some data were generated in vitro, little is known about the in vivo context of HIFs in tooth development. In order to contribute to this field, the mouse mandibular first molar was used as a model. The expression and in situ localisation of HIFs were examined at postnatal (P) days P0, P7, P14, using RT-PCR and immunostaining. The expression pattern of a broad spectrum of hypoxia-related genes was monitored by customised PCR Arrays. Metabolic aspects were evaluated by determination of the lactate level and mRNA expression of the mitochondrial marker Nd1. The results show constant high mRNA expression of Hif1a, increasing expression of Hif2a, and very low expression of Hif3a during early postnatal molar development. In the examined period the localisation of HIFs in the nuclei of odontoblasts and the subodontoblastic layer identified their presence during odontoblastic differentiation. Additionally, the lower lactate level and higher expression of mitochondrial Nd1 in advanced development points to decreasing glycolysis during differentiation. Postnatal nuclear localisation of HIFs indicates a hypoxic state in specific areas of dental pulp as oxygen demands depend on physiological events such as crown and root dentin mineralization. [ABSTRACT FROM AUTHOR]

Mammalian cells utilize glucose as a primary carbon source to produce energy for most cellular functions. However, the bioenergetic homeostasis of cells can be perturbed by environmental alterations, such as changes in oxygen levels which can be associated with bacterial infection. Reduction in oxygen availability leads to a state of hypoxia, inducing numerous cellular responses that aim to combat this stress. Importantly, hypoxia strongly augments cellular glycolysis in most cell types to compensate for the loss of aerobic respiration. Understanding how this host cell metabolic adaptation to hypoxia impacts the course of bacterial infection will identify new anti-microbial targets. This review will highlight developments in our understanding of glycolytic substrate channeling and spatiotemporal enzymatic organization in response to hypoxia, shedding light on the integral role of the hypoxia-inducible factor (HIF) during host–pathogen interactions. Furthermore, the ability of intracellular and extracellular bacteria (pathogens and commensals alike) to modulate host cellular glucose metabolism will be discussed. [ABSTRACT FROM AUTHOR]

Cellular responses to hypoxia are crucial in various physiological and pathophysiological contexts and have thus been extensively studied. This has led to a comprehensive understanding of the transcriptional response to hypoxia, which is regulated by hypoxia-inducible factors (HIFs). However, the detailed molecular mechanisms of HIF regulation in hypoxia remain incompletely understood. In particular, there is controversy surrounding the production of mitochondrial reactive oxygen species (ROS) in hypoxia and how this affects the stabilization and activity of HIFs. This review examines this controversy and attempts to shed light on its origin. We discuss the role of physioxia versus normoxia as baseline conditions that can affect the subsequent cellular response to hypoxia and highlight the paucity of data on pericellular oxygen levels in most experiments, leading to variable levels of hypoxia that might progress to anoxia over time. We analyze the different outcomes reported in isolated mitochondria, versus intact cells or whole organisms, and evaluate the reliability of various ROS-detecting tools. Finally, we examine the cell-type and context specificity of oxygen's various effects. We conclude that while recent evidence suggests that the effect of hypoxia on ROS production is highly dependent on the cell type and the duration of exposure, efforts should be made to conduct experiments under carefully controlled, physiological microenvironmental conditions in order to rule out potential artifacts and improve reproducibility in research. [ABSTRACT FROM AUTHOR]

Cells of the immune defence, especially leukocytes, often have to perform their function in tissue areas that are characterized by oxygen deficiency, so-called hypoxia. Physiological hypoxia significantly affects leukocyte function and controls the innate and adaptive immune response mainly through transcriptional gene regulation via the hypoxia-inducible factors (HIFs). Multiple pathogens including components of bacteria, such as lipopolysaccharides (LPS) trigger the activation of leukocytes. HIF pathway activation enables immune cells to adapt to both hypoxic environments in physiological and inflammatory settings and modulates immune cell responses through metabolism changes and crosstalk with other immune-relevant signalling pathways. To study the mutual influence of both processes in vivo, we used a human endotoxemia model, challenging participants with an intravenous LPS injection post or prior to a 4-h stay in a hypoxic chamber with normobaric hypoxia of 10.5% oxygen. We analysed changes in gene expression in whole blood cells and determined inflammatory markers to unveil the crosstalk between both processes. Our investigations showed differentially altered gene expression patterns of HIF and target genes upon in vivo treatment with LPS and hypoxia. Further, we found evidence for effects of hypoxic priming upon inflammation in combination with immunomodulatory effects in whole blood cells in vivo. Our work elucidates the complex interplay of hypoxic and inflammatory HIF regulation in human immune cells and offers new perspectives for further clinical research. [ABSTRACT FROM AUTHOR]

Oxygen sensing is of paramount importance for maintaining cellular and systemic homeostasis. In response to diminished oxygen levels, the hypoxia-inducible factors (HIFs) orchestrate various biological processes. These pivotal transcription factors have been identified as key regulators of several biological events. Notably, extensive research from our group and others has demonstrated that HIF1α exerts an inverse regulatory effect on steroidogenesis, leading to the suppression of crucial steroidogenic enzyme expression and a subsequent decrease in steroid levels. These steroid hormones occupy pivotal roles in governing a myriad of physiological processes. Substantial or prolonged fluctuations in steroid levels carry detrimental consequences across multiple organ systems and underlie various pathological conditions, including metabolic and immune disorders. MicroRNAs serve as potent mediators of multifaceted gene regulatory mechanisms, acting as influential epigenetic regulators that modulate a broad spectrum of gene expressions. Concomitantly, phosphodiesterases (PDEs) play a crucial role in governing signal transduction. PDEs meticulously manage intracellular levels of both cAMP and cGMP, along with their respective signaling pathways and downstream targets. Intriguingly, an intricate interplay seems to exist between hypoxia signaling, microRNAs, and PDEs in the regulation of steroidogenesis. This review highlights recent advances in our understanding of the role of microRNAs during hypoxia-driven processes, including steroidogenesis, as well as the possibilities that exist in the application of HIF prolyl hydroxylase (PHD) inhibitors for the modulation of steroidogenesis. [ABSTRACT FROM AUTHOR]

The autoimmune destruction of β-cells in type-1 diabetes (T1D) is a multifactorial and poorly understood phenomenon. A major contribution to this autoimmune attack is the generation of autoantigens triggered by β-cell dysfunction. Under hypoxia, cells shift to anaerobic glycolysis, regulated by hypoxia-inducible factor (HIF)-1α. This adaptation ensures energy production through increased glycolytic flux and decreased oxidative phosphorylation. Dysregulation of glycolysis contributes to β-cell dysfunction in diabetes. HIF-1α activation in β-cells impacts both in vivo and in vitro insulin secretion and systemic glucose levels. HIF-1α also modulates immune cell phenotype, potentially influencing autoimmune destruction of β-cells. Although more studies are needed, prolyl-hydroxylase inhibitors, which stabilize HIF-1α, show promise as T1D therapeutics by protecting β-cells against cellular stress. Type 1 diabetes (T1D) is a common autoimmune disease in which dysregulated glucose metabolism is a key feature. T1D is both poorly understood and in need of improved therapeutics. Hypoxia is frequently encountered in multiple tissues in T1D patients including the pancreas and sites of diabetic complications. Hypoxia-inducible factor (HIF)-1, a ubiquitous master regulator of the adaptive response to hypoxia, promotes glucose metabolism through transcriptional and non-transcriptional mechanisms and alters disease progression in multiple preclinical T1D models. However, how HIF-1 activation in β-cells of the pancreas and immune cells (two key cell types in T1D) ultimately affects disease progression remains controversial. We discuss recent advances in our understanding of the role of hypoxia/HIF-1-induced glycolysis in T1D and explore the possible use of drugs targeting this pathway as potential new therapeutics. [ABSTRACT FROM AUTHOR]

Trained immunity of monocytes, endothelial, and smooth muscle cells augments the cytokine response to secondary stimuli. Immune training is characterized by stabilization of hypoxia-inducible factor (HIF)-1α, mTOR activation, and aerobic glycolysis. Cardiac fibroblast (CF)-myofibroblast transition upon myocardial ischemia/reperfusion (I/R) features epigenetic and metabolic adaptations reminiscent of trained immunity. We assessed the impact of I/R on characteristics of immune training in human CF and mouse myocardium. I/R was simulated in vitro with transient metabolic inhibition. CF primed with simulated I/R or control buffer were 5 days later re-stimulated with Pam3CSK for 24 h. Mice underwent transient left anterior descending artery occlusion or sham operation with reperfusion for up to 5 days. HIF-regulated metabolic targets and cytokines were assessed by qPCR, immunoblot, and ELISA and glucose consumption, lactate release, and lactate dehydrogenase (LDH) by chromogenic assay. Simulated I/R increased HIF-1α stabilization, mTOR phosphorylation, glucose consumption, lactate production, and transcription of PFKB3 and F2RL3, a HIF-regulated target gene, in human CF. PGK1 and LDH mRNAs were suppressed. Intracellular LDH transiently increased after simulated I/R, and extracellular LDH showed sustained elevation. I/R priming increased abundance of pro-caspase-1, auto-cleaved active caspase-1, and the expression and secretion of interleukin (IL)-1β, but did not augment Pam3CSK-stimulated cytokine transcription or secretion. Myocardial I/R in vivo increased abundance of HIF-1 and the precursor and cleaved forms of caspase-1, caspase-11, and caspase-8, but not of LDH-A or phospho-mTOR. I/R partially reproduces features of immune training in human CF, specifically HIF-1α stabilization, aerobic glycolysis, mTOR phosphorylation, and PFKB3 transcription. I/R does not augment PGK1 or LDH expression or the cytokine response to Pam3CSK. Regulation of PAR4 and inflammasome caspases likely occurs independently of an immune training repertoire. Ischemia provokes only part of the immune training repertoire in cardiac fibroblasts. Trained immunity in myeloid and non-myeloid cells is triggered by certain infectious and sterile triggers like β-glucan or oxidized LDL, respectively. Key characteristics of immune training are as follows: stabilization of hypoxia-inducible factor (HIF)-1α, mTOR activation, transcriptional induction of lactate dehydrogenase (LDH), phosphoglycerate kinase (PGK)1 and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), increased glycolysis and lactate production, and enhanced cytokine response to a secondary stimulus such as the toll-like receptor agonist Pam3CSK4. Simulated ischemia/reperfusion (SI/R) reproduces some but not all of these features in human cardiac fibroblasts (CF) as indicated with asterisk (*). [ABSTRACT FROM AUTHOR]

The von Hippel-Lindau tumor suppressor protein (VHL), an E3 ubiquitin ligase, functions as a critical regulator of the oxygen-sensing pathway for targeting hypoxia-inducible factors. Recent evidence suggests that mammalian VHL may also be critical to the NF-κB signaling pathway, although the specific molecular mechanisms remain unclear. Herein, the roles of mandarin fish (Siniperca chuatsi) VHL (scVHL) in the NF-κB signaling pathway and mandarin fish ranavirus (MRV) replication were explored. The transcription of scVHL was induced by immune stimulation and MRV infection, indicating a potential role in innate immunity. Dual-luciferase reporter gene assays and reverse transcription quantitative PCR (RT-qPCR) results demonstrated that scVHL evoked and positively regulated the NF-κB signaling pathway. Treatment with NF-κB signaling pathway inhibitors indicated that the role of scVHL may be mediated through scIKKα, scIKKβ, scIκBα, or scp65. Co-immunoprecipitation (Co-IP) analysis identified scIκBα as a novel target protein of scVHL. Moreover, scVHL targeted scIκBα to catalyze the formation of K63-linked polyubiquitin chains to activate the NF-κB signaling pathway. Following MRV infection, NF-κB signaling remained activated, which, in turn, promoted MRV replication. These findings suggest that scVHL not only positively regulates NF-κB but also significantly enhances MRV replication. This study reveals a novel function of scVHL in NF-κB signaling and viral infection in fish. [ABSTRACT FROM AUTHOR]

BACKGROUND: LncRNA-TNFRSF13C, an important factor in B cell development and function, is expressed in periodontal tissues of patients with periodontitis, but the specific mechanism is still unclear. OBJECTIVE: To investigate the mechanism of lncRNA-TNFRSF13C regulating miR-1246 on hypoxia-inducible factor 1α in periodontal cells. METHODS: Human periodontal ligament cells (hPDLCs) were treated with lipopolysaccharide and divided into group A (hPDLCs cell lines without transfection), group B (hPDLCs cell lines transfected with TNFRSF13C NC-siRNA), group C (hPDLCs cell lines transfected with TNFRSF13C-siRNA), group D (hPDLCs cell line transfected with miR-1246 mimics), group E (hPDLCs cell line transfected with miR-1246 siRNA), group F (hPDLCs cell line transfected with TNFRSF13C- siRNA+miR-1246 mimics), and group G (hPDLCs cell line transfected with TNFRSF13C-siRNA+miR-1246 siRNA). The relative expression of lncRNA-TNFRSF13C and miR-1246 in each group was detected by qRT-PCR. Cell counting kit-8 assay was used to detect cell viability. Apoptosis was detected by flow cytometry. Expression of hypoxia-inducible factor 1α and vascular endothelial growth factor proteins was detected by western blot. The correlation between lncRNA- TNFRSF13C and miR-1246 was analyzed by Pearson, and the targeting relationship was analyzed by dual-luciferase reporter assay. RESULTS AND CONCLUSION: There was no significant difference in human periodontal ligament cell activity, apoptosis rate and protein indexes between groups A and B (P >0.05). Compared with group B, hPDLCS cell activity in group C was increased, and apoptosis rate and the expression of hypoxia-inducible factor 1α and vascular endothelial growth factor proteins were decreased (P < 0.05). Compared with group C, hPDLCS cell activity in group D was decreased, and apoptosis rate and the expression of hypoxia-inducible factor 1α and vascular endothelial growth factor proteins were increased (P < 0.05). Compared with group D, the cell activity of group E was increased (P < 0.05). The cell activity in group F was lower than that in group E, and the apoptosis rate was reduced in both groups E and F (P < 0.05). Compared with group F, the cell activity of group G was increased, and the apoptosis rate and the expression of hypoxia- inducible factor 1α and vascular endothelial growth factor were decreased (P < 0.05). LncRNA-TNFRSF13C was positively correlated with miR-1246 (P < 0.05). Compared with the TNFRSF13C-siRNA group, the fluorescence activity of miR-1246-wt in the TNFRSF13C-NC group was reduced (P > 0.05); compared with the miR-1246-NC group, the fluorescence activities of hypoxia-inducible factor 1α-wt and vascular endothelial growth factor-wt in the miR-1246 mimics group were increased (P < 0.05). To conclude, down-regulation of lncRNA-TNFRSF13C can promote the activity of periodontal cells treated with lipopolysaccharide, reduce apoptosis, and inhibit hypoxia-inducible factor 1α and vascular endothelial growth factor. The mechanism is related to the regulation of miR-1246 activity. [ABSTRACT FROM AUTHOR]

Glioblastoma multiforme (GBM) is an aggressive primary brain tumor characterized by extensive heterogeneity and vascular proliferation. Hypoxic conditions in the tissue microenvironment are considered a pivotal player leading tumor progression. Specifically, hypoxia is known to activate inducible factors, such as hypoxia-inducible factor 1alpha (HIF-1α), which in turn can stimulate tumor neo-angiogenesis through activation of various downward mediators, such as the vascular endothelial growth factor (VEGF). Here, we aimed to explore the role of HIF-1α/VEGF immunophenotypes alone and in combination with other prognostic markers or clinical and image analysis data, as potential biomarkers of GBM prognosis and treatment efficacy. We performed a systematic review (Medline/Embase, and Pubmed database search was completed by 16th of April 2024 by two independent teams; PRISMA 2020). We evaluated methods of immunoassays, cell viability, or animal or patient survival methods of the retrieved studies to assess unbiased data. We used inclusion criteria, such as the evaluation of GBM prognosis based on HIF-1α/VEGF expression, other biomarkers or clinical and imaging manifestations in GBM related to HIF-1α/VEGF expression, application of immunoassays for protein expression, and evaluation of the effectiveness of GBM therapeutic strategies based on HIF-1α/VEGF expression. We used exclusion criteria, such as data not reporting both HIF-1α and VEGF or prognosis. We included 50 studies investigating in total 1319 GBM human specimens, 18 different cell lines or GBM-derived stem cells, and 6 different animal models, to identify the association of HIF-1α/VEGF immunophenotypes, and with other prognostic factors, clinical and macroscopic data in GBM prognosis and therapeutic approaches. We found that increased HIF-1α/VEGF expression in GBM correlates with oncogenic factors, such as miR-210-3p, Oct4, AKT, COX-2, PDGF-C, PLDO3, M2 polarization, or ALK, leading to unfavorable survival. Reduced HIF-1α/VEGF expression correlates with FIH-1, ADNP, or STAT1 upregulation, as well as with clinical manifestations, like epileptogenicity, and a favorable prognosis of GBM. Based on our data, HIF-1α or VEGF immunophenotypes may be a useful tool to clarify MRI-PET imaging data distinguishing between GBM tumor progression and pseudoprogression. Finally, HIF-1α/VEGF immunophenotypes can reflect GBM treatment efficacy, including combined first-line treatment with histone deacetylase inhibitors, thimerosal, or an active metabolite of irinotecan, as well as STAT3 inhibitors alone, and resulting in a favorable tumor prognosis and patient survival. These data were supported by a combination of variable methods used to evaluate HIF-1α/VEGF immunophenotypes. Data limitations may include the use of less sensitive detection methods in some cases. Overall, our data support HIF-1α/VEGF's role as biomarkers of GBM prognosis and treatment efficacy. [ABSTRACT FROM AUTHOR]

Ascites syndrome (AS) in broiler chickens, also known as pulmonary arterial hypertension (PAH), is a significant disease in the poultry industry. It is a nutritional metabolic disease that is closely associated with hypoxia-inducible factors and rapid growth. The rise in pulmonary artery pressure is a crucial characteristic of AS and is instrumental in its development. Hypoxia-inducible factor 1α (HIF-1α) is an active subunit of a key transcription factor in the oxygen-sensing pathway. HIF-1α plays a vital role in oxygen homeostasis and the development of pulmonary hypertension. Studying the effects of HIF-1α on pulmonary hypertension in humans or mammals, as well as ascites in broilers, can help us understand the pathogenesis of AS. Therefore, this review aims to (1) summarize the mechanism of HIF-1α in the development of pulmonary hypertension, (2) provide theoretical significance in explaining the mechanism of HIF-1α in the development of pulmonary arterial hypertension (ascites syndrome) in broilers, and (3) establish the correlation between HIF-1α and pulmonary arterial hypertension (ascites syndrome) in broilers. HIGHLIGHTS: Explains the hypoxic mechanism of HIF-1α. Linking HIF-1α to pulmonary hypertension in broilers. Explains the role of microRNAs in pulmonary arterial hypertension in broilers. [ABSTRACT FROM AUTHOR]

Acute kidney injury (AKI) is associated with a high mortality rate. Pathologically, renal ischemia/reperfusion injury (RIRI) is one of the primary causes of AKI, and hypoxia-inducible factor (HIF)-1α may play a defensive role in RIRI. This study assessed the role of hypoxia-inducible factor 1α (HIF-1α)-mediated mitophagy in protection against RIRI in vitro and in vivo. The human tubular cell line HK-2 was used to assess hypoxia/reoxygenation (H/R)-induced mitophagy through different in vitro assays, including western blotting, immunofluorescence staining, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL), and reactive oxygen species (ROS) measurement. Additionally, a rat RIRI model was established for evaluation by renal histopathology, renal Doppler ultrasound, and transmission electron microscopy to confirm the in vitro data. The selective HIF-1α inhibitor LW6 reduced H/R-induced mitophagy but increased H/R-induced apoptosis and ROS production. Moreover, H/R treatment enhanced expression of the FUN14 domain-containing 1 (FUNDC1) protein. Additionally, FUNDC1 overexpression reversed the effects of LW6 on the altered expression of light chain 3 (LC3) BII and voltage-dependent anion channels as well as blocked the effects of HIF-1α inhibition in cells. Pretreatment of the rat RIRI model with roxadustat, a novel oral HIF-1α inhibitor, led to decreased renal injury and apoptosis in vivo. In conclusion, the HIF-1α/FUNDC1 signaling pathway mediates H/R-promoted renal tubular cell mitophagy, whereas inhibition of this signaling pathway protects cells from mitophagy, thus aggravating apoptosis, and ROS production. Accordingly, roxadustat may protect against RIRI-related AKI. [ABSTRACT FROM AUTHOR]