The updated biology of hypoxia-inducible factor

Oral squamous cell carcinoma: Insights into cellular heterogeneity, drug resistance, and evolutionary trajectories

Oral squamous cell carcinoma (OSCC) can lead to metastasis and high mortality rates known for its aggressive and invasive properties. Currently, primary treatment options of surgical resection, chemotherapy and radiotherapy have many therapeutic limitations for OSCC patients due to its dynamic evolutionary pathways and the development of resistance to conventional therapies. Moreover, previous studies fail to emphasize the roles of cellular heterogeneity, drug resistance, and evolutionary trajectories in OSCC. This review explores the intricate tumor microenvironment landscape of OSCC, focusing on the cellular heterogeneity, drug resistance, and evolutionary trajectories as well as genetic, epigenetic, and environmental risk factors contributing to the OSCC progression. Tumor heterogeneity arises from environmental exposures (e.g., tobacco, HPV infection, dietary carcinogens) that drive clonal evolution, creating subpopulations of cells with distinct mutational profiles and therapeutic vulnerabilities. Recent advances in in the precision medicine and combination therapy of OSCC paves the way for innovative therapeutic strategies, such as targeting molecular subclones through real-time monitoring and leveraging computational models to predict treatment response. By recognizing tumor heterogeneity as both a driver of therapeutic resistance and a therapeutic target, precision medicine frameworks can integrate environmental risk factor data, molecular profiling, and early detection tools to optimize outcomes. This review underscores the necessity for a multidisciplinary approach to understand and combat the complexity of OSCC, proposing directions for future research to enhance diagnosis and treatment efficacy.

Association among lean mass, gut microbiome alterations and bone mineral density in high-altitude

BACKGROUND

Body composition, particularly lean body mass, plays a pivotal role in skeletal health and has been increasingly linked to the gut microbiota (GM). However, evidence from vulnerable high-altitude populations remains scarce.

OBJECTIVE

This study aimed to evaluate the association between body composition and bone mineral density (BMD) at high altitudes and explore the potential role of GM.

METHODS

A total of 820 Tibetan participants were recruited. BMD at the lumbar spine (L1-L4) and total hip was measured using dual-energy X-ray absorptiometry (DXA). Multivariate linear regression was applied to evaluate the associations between body composition indices and BMD. Participants were stratified into low lean mass index (LLMI) and high lean mass index (HLMI) subgroups using restricted cubic splines (RCS) and body mass index. Stool samples from a subset of participants (n = 383) were analyzed to determine the relative abundances of KEGG Orthology groups.

RESULTS

LMI was positively associated with hip BMD at high altitude [β (95 % CI) = 0.005 (0.003,0.007), P < 0.05], whereas no significant association was observed with spine BMD. This correlation varied significantly by altitude (Pinter< 0.05). A similar positive relationship was observed between microbial diversity (Shannon index) and hip_BMD [hip: β (95 % CI) = 0.605 (0.165, 1.044), P < 0.05]. Compared to the HLMI group, LLMI participants exhibited greater microbial diversity (P < 0.05), higher Faecalibacteriums abundance, and lower levels of Prevotella copri (P< 0.05). Functional metagenomic analysis identified differential enrichment of microbial pathways, including riboflavin metabolism, terpenoid backbone biosynthesis, alanine, aspartate, and glutamate metabolism (P < 0.05).

CONCLUSION

These findings highlight the correlation between LMI and hip BMD among high-altitude Tibetan adults, offering a potential mechanism for the interplay between GM profiles and bone health in high-altitude populations.

The Distinct Role of HIF-1α and HIF-2α in Hypoxia and Angiogenesis

Hypoxia results in a wide range of adaptive physiological responses, including metabolic reprogramming, erythropoiesis, and angiogenesis. The response to hypoxia at the cellular level is mainly regulated by hypoxia-inducible factors (HIFs): HIF1α and HIF2α isoforms. Although structurally similar and overlapping gene targets, both isoforms can exhibit distinct expression patterns and functions in some conditions of hypoxia. The interaction between these isoforms, known as the "HIF switch", determines their coordinated function under varying oxygen levels and exposure time. In angiogenesis, HIF-1α is rapidly stabilized under acute hypoxia, prompting a metabolic shift from oxidative phosphorylation to glycolysis and initiating angiogenesis by activating endothelial cells and extracellular matrix remodeling. Conversely, HIF-2α regulates cell responses to chronic hypoxia by sustaining genes critical for vascular remodeling and maturation. The current review highlights the different roles and regulatory mechanisms of HIF-1α and HIF-2α isoforms, focusing on their involvement in cell metabolism and the multi-step process of angiogenesis. Tuning the specific targeting of HIF isoforms and finding the right therapeutic window is essential to obtaining the best therapeutic effect in diseases such as cancer and vascular ischemic diseases.

Hypoxia Disrupts Sex-Specific Physiology and Gene Expression Leading to Decreased Fitness in the Estuarine Sea Anemone Nematostella vectensis

Coastal seawater hypoxia is increasing in temperate estuaries under global climate change, yet it is unknown how low oxygen conditions affect most estuarine species. We found that hypoxia has increased since the 1990s in an estuary hosting the sea anemone Nematostella vectensis (Jacques Cousteau National Estuarine Research Reserve, New Jersey, USA). Adult N. vectensis bred from anemones collected in this estuary exposed to three consecutive nights of hypoxia (dissolved oxygen = 0.5-1.5 mg L-1 for ~12 h night-1) during gametogenesis displayed decreased aerobic respiration rates and biomass, indicating metabolic disruption. Physiological declines were correlated with changes in the expression of genes related to oxygen-dependent metabolic processes, many of which are targets of hypoxia-inducible factor 1α (HIF1α), demonstrating the activity of this transcription factor for the first time in this early-diverging metazoan. The upregulation of genes involved in the unfolded protein response and endoplasmic reticulum and Golgi apparatus homeostasis suggested that misfolded proteins contributed to disrupted physiology. Notably, these responses were more pronounced in females, demonstrating sex-specific sensitivity that was also observed in reproductive outcomes, with declines in female but not male fecundity following hypoxia exposure. However, sperm from exposed males had higher mitochondrial membrane potential, indicating altered spermatogenesis. Further, crosses performed with gametes from hypoxia-exposed adults yielded strikingly low developmental success (~2%), yet larvae that did develop displayed similar respiration rates and accelerated settlement compared to controls. Overall, hypoxia depressed fitness in N. vectensis by over 95%, suggesting that even stress-tolerant estuarine species may be threatened by coastal deoxygenation.

Metformin ameliorates osteoporosis by enhancing bone angiogenesis via the YAP1/TAZ-HIF1α axis

BACKGROUND

Osteoporosis, resulting from an imbalance between osteoclast-mediated bone resorption and osteoblast-mediated bone formation, affects millions globally. Recent studies have identified type H vessels (CD31hiEMCNhi) as a specialized subset of bone blood vessels that positively regulate bone formation. This study aims to investigate the effects of metformin on bone mass, strength, and angiogenesis in osteoporotic mice, and to elucidate the underlying molecular mechanisms, particularly focusing on the YAP1/TAZ-HIF1α axis.

METHODS

Osteoporotic mice were administered metformin, and bone mass and strength were measured. In vivo and in vitro angiogenesis assays were performed under hypoxic conditions. Expression levels of YAP1/TAZ and HIF1α were assessed in femoral metaphysis and hypoxia-cultured human microvascular endothelial cells (HMECs). Small interfering RNA was used to interfere with HIF1α or YAP1/TAZ expression in hypoxia-cultured HMECs. Additionally, we employed AAV-mediated overexpression of YAP1/TAZ in vivo to determine whether elevated YAP1/TAZ levels alter metformin's effects on bone mass and angiogenesis.

RESULTS

Metformin significantly enhanced bone mass and strength in osteoporotic mice. It also promoted angiogenesis under hypoxia conditions both in vivo and in vitro. Metformin reduced YAP1/TAZ expression while increasing HIF1α expression in both the femoral metaphysis of osteoporotic mice and hypoxia-cultured HMECs. Interference with HIF1α or YAP1/TAZ confirmed that metformin enhances HIF1α and its target genes primarily by inhibiting YAP1/TAZ. Furthermore, overexpression of YAP1/TAZ partially reversed the bone-protective effect of metformin, leading to reduced HIF1α levels and diminished type H vessel formation.

CONCLUSION

Our findings suggest that metformin holds promise as a therapeutic agent for osteoporosis by enhancing type H vessel formation through the inhibition of the YAP1/TAZ-HIF1α axis.

The Roles and Molecular Mechanisms of HIF-1α in Pulpitis

Pulpitis is characterized by inflammation within dental pulp tissue, primarily triggered by bacterial infection. Hypoxia-inducible factor-1α (HIF-1α), a key transcriptional regulator, is stabilized under the hypoxic conditions associated with pulpitis. This review examines the roles and molecular mechanisms of HIF-1α in the pathogenesis and progression of pulpitis. Hypoxia in pulpitis prevents the degradation of HIF-1α, leading to its elevated expression. Furthermore, lipopolysaccharide from invading bacteria upregulates HIF-1α transcription through nuclear factor kappa B and mitogen-activated protein kinase pathways. HIF-1α regulates immunity and pulp remodeling in a stage-dependent manner by controlling various cytokines. During the inflammation stage, HIF-1α promotes recruitment of neutrophils and enhances their bactericidal effects by facilitating neutrophil extracellular trap release and M1 macrophage polarization. Concurrently, HIF-1α contributes to programmed cell death by increasing mitophagy. In the proliferation stage, HIF-1α stimulates immune responses involving T cells and dendritic cells. In the remodeling stage, HIF-1α supports angiogenesis and pulp-dentin regeneration. However, excessive pulpitis-induced hypoxia may disrupt vascular dynamics within the pulp chamber. This disruption highlights a critical threshold for HIF-1α, beyond which its effects might accelerate pulp necrosis. Overall, HIF-1α plays a central role in regulating immunity and tissue remodeling during pulpitis. A comprehensive understanding of the physiological and pathological roles of HIF-1α is essential for the advancement of effective strategies to manage irreversible pulpitis.

Are hypoxia-related proteins associated with the invasiveness of glandular odontogenic cysts? A multicenter study

OBJECTIVE

The study aimed to investigate the expression of hypoxia markers associated with invadopodia in glandular odontogenic cysts and to explore an association between this expression with the aggressive biological behaviour of this odontogenic cyst.

DESIGN

Immunohistochemistry was employed to assess the expression of hypoxia-inducible factor 1 alpha (HIF-1α), notch homologous protein of the neurogenic locus 1 (NOTCH-1), disintegrin and metalloproteinase-12 (ADAM-12), and heparin-binding epidermal growth factor (HB-EGF) in 17 samples of glandular odontogenic cysts, 10 samples of calcifying odontogenic cysts, and 10 samples of dental follicles.

RESULTS

The glandular odontogenic cyst samples exhibited increased expression of HIF-1α, NOTCH-1, ADAM-12 and HBEGF proteins compared with calcifying odontogenic cyst and dental follicle samples. HIF-1α demonstrated localization primarily within the nuclei of cystic epithelial cells of the glandular odontogenic cyst. NOTCH-1 and ADAM-12 exhibited expression in the cytoplasm and nuclei of epithelial and mucous cells of the glandular odontogenic cyst, of whereas HB-EGF was predominantly expressed in the cytoplasm. Weak labeling of these proteins was observed in the odontogenic epithelium of the calcifying odontogenic cyst and dental follicle samples.

CONCLUSIONS

The hypoxia-related signaling proteins are overexpressed in glandular odontogenic cyst when compared with calcifying odontogenic cyst and dental follicle. The reported aggressiveness of glandular odontogenic cyst can be partially explained by the expression of these proteins.

Recent updates on cold adaptation in population and laboratory studies, including cross-adaptation with nonthermal factors

This review aims to update our understanding of human cold adaptation. First, an overview of the thermoregulatory response to cold is provided, with some recent updates in human brown adipose tissue (BAT). Variation in BAT activity and multiorgan contributions to cold-induced thermogenesis were introduced. We found that individuals with less BAT activity rely more on shivering to compensate for less non-shivering thermogenesis (NST). The mechanisms of cold-induced vasoconstriction are summarized, including the role of arteriovenous anastomoses, adrenergic neural function, and inhibition of the nitric oxide vasodilator pathway. In addition, cold-induced vasodilation (CIVD) during cold immersion of the distal extremities is summarized with some recent updates in physiological mechanism. Furthermore, the cold shock response at the onset of cold immersion is introduced. Next, categorization of cold acclimatization/acclimation into habituation of shivering and metabolic and insulative adaptation are provided, with some recent updates. Especially, the rediscovery of human BAT has clarified metabolic acclimation, where increased NST replace shivering. Then, a greater CIVD response in populations in cold regions has been reported, whereas recent laboratory studies suggest no increase in CIVD after repeated cold exposure. To prevent cold injuries, individuals should not rely on habituation through repeated cold exposure. In addition, habituation to the cold shock response after repeated cold water immersion could help reduce the number of drownings. Furthermore, cross-adaptation between cold and nonthermal factors in the thermoregulatory response is summarized. Recent studies explored the relationship between exercise training and BAT activity, although this remains unresolved, depending on the exercise intensity and environmental conditions. The effects of exercise with cold exposure on the thermoregulatory response to cold are summarized in studies including divers working in cold water. We investigated the effect of exercise training in cold water, which resulted in increased muscle deoxygenation during submaximal exercise and greater anerobic power. Moreover, the effects of a hypoxic environment on cold adaptation are summarized. Elevated basal metabolism and higher distal skin temperature in highlanders could improve their cold tolerance. Finally, factors affecting cold adaptation are discussed. The type of cold adaptation may depend on the specific thermoregulatory responses repeated during the adaptation process.

A novel lineage-tracing tool reveals that hypoxic tumor cells drive tumor relapse after radiotherapy

PURPOSE

Tumor hypoxia imposes a main obstacle to the efficacy of anti-cancer therapy. Understanding the cellular dynamics of individual hypoxic cells before, during and post-treatment has been hampered by the technical inability to identify and trace these cells over time.

METHODS AND MATERIALS

Here, we present a novel lineage-tracing reporter for hypoxic cells based on the conditional expression of a HIF1a-CreERT2-UnaG biosensor that can visualize hypoxic cells in a time-dependent manner and trace the fate of hypoxic cells over time. We combine this system with multiphoton microscopy, flow cytometry, and immunofluorescence to characterize the role of hypoxic cells in tumor relapse after irradiation in H1299 tumor spheroids and in vivo xenografts.

RESULTS

We validate the reporter in monolayer cultures and we show that tagged cells colocalize in spheroids and human tumor xenografts with the hypoxic marker pimonidazole. We found that irradiation of H1299-HIFcreUnaG spheroids leads to preferential outgrowth of cells from the hypoxic core. Similarly, in xenografts tumors, although initially UnaG-positive-cells coincide with pimonidazole-positive tumor areas and they are merely quiescent, upon irradiation UnaG-positive cells enrich in regrowing tumors and are mainly proliferative.

CONCLUSIONS

Collectively, our data provide clear evidence that the hypoxic cells drive tumor relapse after irradiation.

Understanding the molecular mechanism responsible for developing therapeutic radiation-induced radioresistance of rectal cancer and improving the clinical outcomes of radiotherapy - A review

Rectal cancer accounts for the second highest cancer-related mortality, which is predominant in Western civilizations. The treatment for rectal cancers includes surgery, radiotherapy, chemotherapy, and immunotherapy. Radiotherapy, specifically external beam radiation therapy, is the most common way to treat rectal cancer because radiation not only limits cancer progression but also significantly reduces the risk of local recurrence. However, therapeutic radiation-induced radioresistance to rectal cancer cells and toxicity to normal tissues are major drawbacks. Therefore, understanding the mechanistic basis of developing radioresistance during and after radiation therapy would provide crucial insight to improve clinical outcomes of radiation therapy for rectal cancer patients. Studies by various groups have shown that radiotherapy-mediated changes in the tumor microenvironment play a crucial role in developing radioresistance. Therapeutic radiation-induced hypoxia and functional alterations in the stromal cells, specifically tumor-associated macrophage (TAM) and cancer-associated fibroblasts (CAF), play a crucial role in developing radioresistance. In addition, signaling pathways, such as - the PI3K/AKT pathway, Wnt/β-catenin signaling, and the hippo pathway, modulate the radiation responsiveness of cancer cells. Different radiosensitizers, such as small molecules, microRNA, nanomaterials, and natural and chemical sensitizers, are being used to increase the effectiveness of radiotherapy. This review highlights the mechanism responsible for developing radioresistance of rectal cancer following radiotherapy and potential strategies to enhance the effectiveness of radiotherapy for better management of rectal cancer.

Decoding the role of HIF-1α in immunoregulation in Litopenaeus vannamei under hypoxic stress

Hypoxia poses a significant challenge to aquatic organisms, especially Litopenaeus vannamei (L. vannamei), which play a vital role in the global aquaculture industry. Hypoxia-inducible factor 1α (HIF-1α) is a pivotal regulator of the organism's adaptation to hypoxic conditions. To understand of how HIF-1α affects the immunity of L. vannamei under hypoxic conditions, we conducted a thorough study involving various approaches. These included observing tissue morphology, analyzing the expression of immune-related genes, assessing the activities of immune-related enzymes, and exploring immune-related pathways. Our study revealed that RNA interference (RNAi)-mediated knockdown of HIF-1α markedly reduced HIF-1α expression in the gill (75-95 %), whereas the reduction ranged from 2 to 43 % in the hepatopancreas. Knockdown of HIF-1α resulted in increased damage to both gill and hepatopancreatic tissues in hypoxic conditions. Additionally, immune-related genes, including Astakine (AST), Hemocyanin (HC), and Ferritin (FT), as well as immune-related enzymes such as Acid Phosphatase (ACP), Alkaline Phosphatase (AKP), and Phenoloxidase (PO), exhibited intricate regulatory patterns in response to hypoxia stress following the knockdown of HIF-1α. Transcriptome analysis revealed that HIF-1α knockdown significantly impacts multiple signaling pathways, including the JAK-STAT signaling pathway, Th17 cell differentiation pathways, PI3K-Akt signaling pathway, ErbB signaling pathway, MAPK signaling pathway, chemokine signaling pathway, ribosomal pathways, apoptosis, lysosomes and arachidonic acid metabolism. These alterations disrupt the organism's immune balance and interfere with normal metabolic processes, potentially leading to various immune-related diseases. We speculate that the weakened immune response resulting from HIF-1 inhibition is due to the reduced metabolic capacity, and the existence of a direct regulatory relationship between them requires further exploration. This study greatly advances our understanding of the vital role that HIF-1α plays in regulating immune responses in shrimp under hypoxic conditions, thereby deepening our comprehension of this critical biological mechanism.

A nature-inspired HIF stabilizer derived from a highland-adaptation insertion of plateau pika Epas1 protein

Hypoxia-inducible factors (HIFs) play pivotal roles in numerous diseases and high-altitude adaptation, and HIF stabilizers have emerged as valuable therapeutic tools. In our prior investigation, we identified a highland-adaptation 24-amino-acid insertion within the Epas1 protein. This insertion enhances the protein stability of Epas1, and mice engineered with this insertion display enhanced resilience to hypoxic conditions. In the current study, we delved into the biochemical mechanisms underlying the protein-stabilizing effects of this insertion. Our findings unveiled that the last 11 amino acids within this insertion adopt a helical conformation and interact with the α-domain of the von Hippel-Lindau tumor suppressor protein (pVHL), thereby disrupting the Eloc-pVHL interaction and impeding the ubiquitination of Epas1. Utilizing a synthesized peptide, E14-24, we demonstrated its favorable membrane permeability and ability to stabilize endogenous HIF-α proteins, inducing the expression of hypoxia-responsive element (HRE) genes. Furthermore, the administration of E14-24 to mice subjected to hypoxic conditions mitigated body weight loss, suggesting its potential to enhance hypoxia adaptation.

Metabolic theory of preeclampsia: implications for maternal cardiovascular health

Preeclampsia (PE) is a multisystemic disorder of pregnancy that not only causes perinatal mortality and morbidity but also has a long-term toll on the maternal and fetal cardiovascular system. Women diagnosed with PE are at greater risk for the subsequent development of hypertension, ischemic heart disease, cardiomyopathy, cerebral edema, seizures, and end-stage renal disease. Although PE is considered heterogeneous, inefficient extravillous trophoblast (EVT) migration leading to deficient spiral artery remodeling and increased uteroplacental vascular resistance is the likely initiation of the disease. The principal pathophysiology is placental hypoxia, causing subsequent oxidative stress, leading to mitochondrial dysfunction, mitophagy, and immunological imbalance. The damage imposed on the placenta in turn results in the "stress response" categorized by the dysfunctional release of vasoactive components including oxidative stressors, proinflammatory factors, and cytokines into the maternal circulation. These bioactive factors have deleterious effects on systemic endothelial cells and coagulation leading to generalized vascular dysfunction and hypercoagulability. A better understanding of these metabolic factors may lead to novel therapeutic approaches to prevent and treat this multisystemic disorder. In this review, we connect the hypoxic-oxidative stress and inflammation involved in the pathophysiology of PE to the resulting persistent cardiovascular complications in patients with preeclampsia.

Facile One Pot Synthesis of Hybrid Core-Shell Silica-Based Sensors for Live Imaging of Dissolved Oxygen and Hypoxia Mapping in 3D Cell Models

Fluorescence imaging allows for noninvasively visualizing and measuring key physiological parameters like pH and dissolved oxygen. In our work, we created two ratiometric fluorescent microsensors designed for accurately tracking dissolved oxygen levels in 3D cell cultures. We developed a simple and cost-effective method to produce hybrid core-shell silica microparticles that are biocompatible and versatile. These sensors incorporate oxygen-sensitive probes (Ru(dpp) or PtOEP) and reference dyes (RBITC or A647 NHS-Ester). SEM analysis confirmed the efficient loading and distribution of the sensing dye on the outer shell. Fluorimetric and CLSM tests demonstrated the sensors' reversibility and high sensitivity to oxygen, even when integrated into 3D scaffolds. Aging and bleaching experiments validated the stability of our hybrid core-shell silica microsensors for 3D monitoring. The Ru(dpp)-RBITC microparticles showed the most promising performance, especially in a pancreatic cancer model using alginate microgels. By employing computational segmentation, we generated 3D oxygen maps during live cell imaging, revealing oxygen gradients in the extracellular matrix and indicating a significant decrease in oxygen level characteristics of solid tumors. Notably, after 12 h, the oxygen concentration dropped to a hypoxic level of PO2 2.7 ± 0.1%.

Genetic Signatures of Positive Selection in Human Populations Adapted to High Altitude in Papua New Guinea

Papua New Guinea (PNG) hosts distinct environments mainly represented by the ecoregions of the Highlands and Lowlands that display increased altitude and a predominance of pathogens, respectively. Since its initial peopling approximately 50,000 years ago, inhabitants of these ecoregions might have differentially adapted to the environmental pressures exerted by each of them. However, the genetic basis of adaptation in populations from these areas remains understudied. Here, we investigated signals of positive selection in 62 highlanders and 43 lowlanders across 14 locations in the main island of PNG using whole-genome genotype data from the Oceanian Genome Variation Project (OGVP) and searched for signals of positive selection through population differentiation and haplotype-based selection scans. Additionally, we performed archaic ancestry estimation to detect selection signals in highlanders within introgressed regions of the genome. Among highland populations we identified candidate genes representing known biomarkers for mountain sickness (SAA4, SAA1, PRDX1, LDHA) as well as candidate genes of the Notch signaling pathway (PSEN1, NUMB, RBPJ, MAML3), a novel proposed pathway for high altitude adaptation in multiple organisms. We also identified candidate genes involved in oxidative stress, inflammation, and angiogenesis, processes inducible by hypoxia, as well as in components of the eye lens and the immune response. In contrast, candidate genes in the lowlands are mainly related to the immune response (HLA-DQB1, HLA-DQA2, TAAR6, TAAR9, TAAR8, RNASE4, RNASE6, ANG). Moreover, we find two candidate regions to be also enriched with archaic introgressed segments, suggesting that archaic admixture has played a role in the local adaptation of PNG populations.

Inflammation Triggers Chondrocyte Ferroptosis in TMJOA via HIF-1α/TFRC

Inflammation and loss of articular cartilage are considered the major cause of temporomandibular joint osteoarthritis (TMJOA), a painful condition of the temporomandibular joint (TMJ). To determine the cause of TMJ osteoarthritis in these patients, synovial fluid of TMJOA patients was compared prior to and after hyaluronic lavage, revealing substantially elevated levels of interleukin (IL) 1β, reactive oxidative stress (ROS), and an overload of Fe3+ and Fe2+ prior to lavage, indicative of ferroptosis as a mode of chondrocyte cell death. To ask whether prolonged inflammatory conditions resulted in ferroptosis-like transformation in vitro, we subjected TMJ chondrocytes to IL-1β treatment, resulting in a shift in messenger RNA sequencing gene ontologies related to iron homeostasis and oxidative stress-related cell death. Exposure to rat unilateral anterior crossbite conditions resulted in reduced COL2A1 expression, fewer chondrocytes, glutathione peroxidase 4 (GPX4) downregulation, and 4-hydroxynonenal (4-HNE) upregulation, an effect that was reversed after intra-articular injections of the ferroptosis inhibitor ferrostatin 1 (Fer-1). Our study demonstrated that ferroptosis conditions affected mitochondrial structure and function, while the inhibitor Fer-1 restored mitochondrial structure and the inhibition of hypoxia-inducible factor 1α (HIF-1α) or the transferrin receptor 1 (TFRC) rescued IL-1β-induced loss of mitochondrial membrane potential. Inhibition of HIF-1α downregulated IL-1β-induced TFRC expression, while inhibition of TFRC did not downregulate IL-1β-induced HIF-1α expression in chondrocytes. Moreover, inhibition of HIF-1α or TFRC downregulated the IL-1β-induced MMP13 expression in chondrocytes, while inhibition of HIF-1α or TFRC rescued IL-1β-inhibited COL2A1 expression in chondrocytes. Furthermore, upregulation of TFRC promoted Fe2+ entry into chondrocytes, inducing the Fenton reaction and lipid peroxidation, which in turn caused ferroptosis, a disruption in chondrocyte functions, and an exacerbation of condylar cartilage degeneration. Together, these findings illustrate the far-reaching effects of chondrocyte ferroptosis in TMJOA as a mechanism causing chondrocyte death through iron overload, oxidative stress, and articular cartilage degeneration and a potential major cause of TMJOA.

Discovery of novel direct small-molecule inhibitors targeting HIF-2α using structure-based virtual screening, molecular dynamics simulation, and MM-GBSA calculations

Hypoxia-inducible factors (HIFs) are the main regulatory factors implicated in the adaptation of cancer cells to hypoxic stress, which has provoked much interest as an attractive target for the design of promising chemotherapeutic agents. Since indirect HIF inhibitors (HIFIs) lead to the occurrence of various side effects, the need of the hour is to develop direct HIFIs, physically interacting with important functional domains within the HIF protein structure. Accordingly, in the present study, it was attempted to develop an exhaustive structure-based virtual screening (VS) process coupled with molecular docking, molecular dynamic (MD) simulation, and MM-GBSA calculations for the identification of novel direct inhibitors against the HIF-2α subunit. For this purpose, a focused library of over 200,000 compounds from the NCI database was used for VS against the PAS-B domain of the target protein, HIF-2α. This domain was suggested to be a possible ligand-binding site, which is characterized by a large internal hydrophobic cavity, unique to the HIF-2α subunit. The top-ranked compounds, NSC106416, NSC217021, NSC217026, NSC215639, and NSC277811 with the best docking scores were taken up for the subsequent in silico ADME properties and PAINS filtration. The selected drug-like hits were employed for carrying out MD simulation which was followed by MM-GBSA calculations to retrieve the candidates showing the highest in silico binding affinity towards the PAS-B domain of HIF-2α. The analysis of results indicated that all molecules, except the NSC277811, fulfilled necessary drug-likeness properties. Four selected drug-like candidates, NSC106416, NSC217021, NSC217026, and NSC215639 were found to expose the stability profiles within the cavity located inside the PAS-B domain of HIF-2α over simulation time. Finally, the results of the MM-GBSA rescoring method were indicative of the highest binding affinity of NSC217026 for the binding site of the HIF-2α PAS-B domain among selected final hits. Consequently, the hit NSC217026 could serve as a promising scaffold for further optimization toward the design of direct HIF-2α inhibitors for cancer therapy.

Differential impact of sex on regulation of skeletal muscle mitochondrial function and protein homeostasis by hypoxia-inducible factor-1α in normoxia

Hypoxia-inducible factor (HIF)-1α is continuously synthesized and degraded in normoxia. During hypoxia, HIF1α stabilization restricts cellular/mitochondrial oxygen utilization. Cellular stressors can stabilize HIF1α even during normoxia. However, less is known about HIF1α function(s) and sex-specific effects during normoxia in the basal state. Since skeletal muscle is the largest protein store in mammals and protein homeostasis has high energy demands, we determined HIF1α function at baseline during normoxia in skeletal muscle. Untargeted multiomics data analyses were followed by experimental validation in differentiated murine myotubes with loss/gain of function and skeletal muscle from mice without/with post-natal muscle-specific Hif1a deletion (Hif1amsd). Mitochondrial oxygen consumption studies using substrate, uncoupler, inhibitor, titration protocols; targeted metabolite quantification by gas chromatography-mass spectrometry; and post-mitotic senescence markers using biochemical assays were performed. Multiomics analyses showed enrichment in mitochondrial and cell cycle regulatory pathways in Hif1a deleted cells/tissue. Experimentally, mitochondrial oxidative functions and ATP content were higher with less mitochondrial free radical generation with Hif1a deletion. Deletion of Hif1a also resulted in higher concentrations of TCA cycle intermediates and HIF2α proteins in myotubes. Overall responses to Hif1amsd were similar in male and female mice, but changes in complex II function, maximum respiration, Sirt3 and HIF1β protein expression and muscle fibre diameter were sex-dependent. Adaptive responses to hypoxia are mediated by stabilization of constantly synthesized HIF1α. Despite rapid degradation, the presence of HIF1α during normoxia contributes to lower mitochondrial oxidative efficiency and greater post-mitotic senescence in skeletal muscle. In vivo responses to HIF1α in skeletal muscle were differentially impacted by sex. KEY POINTS: Hypoxia-inducible factor -1α (HIF1α), a critical transcription factor, undergoes continuous synthesis and proteolysis, enabling rapid adaptive responses to hypoxia by reducing mitochondrial oxygen consumption. In mammals, skeletal muscle is the largest protein store which is determined by a balance between protein synthesis and breakdown and is sensitive to mitochondrial oxidative function. To investigate the functional consequences of transient HIF1α expression during normoxia in the basal state, myotubes and skeletal muscle from male and female mice with HIF1α knockout were studied using complementary multiomics, biochemical and metabolite assays. HIF1α knockout altered the electron transport chain, mitochondrial oxidative function, signalling molecules for protein homeostasis, and post-mitotic senescence markers, some of which were differentially impacted by sex. The cost of rapid adaptive responses mediated by HIF1α is lower mitochondrial oxidative efficiency and post-mitotic senescence during normoxia.

Prognostic biomarker HIF1α and its correlation with immune infiltration in gliomas

Certain glioma subtypes, such as glioblastoma multiforme or low-grade glioma, are common malignant intracranial tumors with high rates of relapse and malignant progression even after standard therapy. The overall survival (OS) is poor in patients with gliomas; hence, effective prognostic prediction is crucial. Herein, the present study aimed to explore the potential role of hypoxia-inducible factor 1 subunit alpha (HIF1α) in gliomas and investigate the association between HIF1α and infiltrating immune cells in gliomas. Data from The Cancer Genome Atlas were evaluated via RNA sequencing, clinicopathological, immunological checkpoint, immune infiltration and functional enrichment analyses. Validation of protein abundance was performed using paraffin-embedded samples from patients with glioma. A nomogram model was created to forecast the OS rates at 1, 3 and 5 years after cancer diagnosis. The association between OS and HIF1α expression was estimated using Kaplan-Meier survival analysis and the log-rank test. Finally, HIF1α expression was validated using western blotting, reverse transcription-quantitative PCR, Cell Counting Kit-8 and Transwell assays. The results demonstrated that HIF1α expression was significantly upregulated in gliomas compared with normal human brain glial cells. Immunohistochemistry staining demonstrated differential expression of the HIF1α protein. Moreover, glioma cell viability and migration were inhibited via HIF1α downregulation. HIF1α impacted DNA replication, cell cycling, DNA repair and the immune microenvironment in glioma. HIF1α expression was also positively associated with several types of immune cells and immunological checkpoints and with neutrophils, plasmacytoid dendritic cells and CD56bright cells. The Kaplan-Meier survival analyses further demonstrated a strong association between high HIF1α expression and poor prognosis in patients with glioma. Analysis of the receiver operating characteristic curves demonstrated that HIF1α expression accurately differentiated paired normal brain cells from tumor tissues. Collectively, these findings suggested the potential for HIF1α to be used as a novel prognostic indicator for patients with glioma and that OS prediction models may help in the future to develop effective follow-up and treatment strategies for these patients.

Multiplex Immunofluorescence Staining Protocol for the Dual Imaging of Hypoxia-Inducible Factors 1 and 2 on Formalin-Fixed Paraffin-Embedded Samples

Hypoxia is a common condition in rapidly proliferating tumors and occurs when oxygen delivery to the tissue is scarce. It is a prevalent feature in ~90% of solid tumors. The family of HIF (hypoxia-inducible factor) proteins-HIF1α and HIF2α-are the main transcription factors that regulate the response to hypoxia. These transcription factors regulate numerous downstream gene targets that promote the aggressiveness of tumors and therefore have been linked to worse prognosis in patients. This makes them a potential biomarker to be tested in the clinical setting to predict patient outcomes. However, HIFs have been notoriously challenging to immunolabel, in part due to their fast turnover under normal oxygen conditions. In this work, we developed a multiplexed immunofluorescence (mIF) staining protocol for the simultaneous detection of HIF1α and HIF2α in the same formalin-fixed paraffin-embedded (FFPE) tissue section.

Belzutifan, HIF-2α Inhibitor, and Clear Cell Renal Cell Carcinoma With Somatic Von-Hippel-Lindau Loss-of-Function Mutation

The Von-Hippel-Lindau (VHL) gene, acting as a tumor suppressor, plays a crucial role in the tumorigenesis of clear cell renal cell carcinoma (ccRCC). Approximately 90% of individuals with advanced ccRCC exhibit somatic mutations in the VHL gene. Belzutifan, orally administered small-molecule inhibitor of hypoxia-induced factor-2α, has demonstrated promising efficacy in solid tumors associated with germline loss-of-function mutations in VHL, including ccRCC. However, its impact on cases with somatic or sporadic VHL mutations remains unclear. Here, we present 2 cases where belzutifan monotherapy was employed in patients with advanced ccRCC and somatic loss-of-function mutations in VHL. Both patients exhibited a swift and sustained response, underscoring the potential role of belzutifan as a viable option in second or subsequent lines of therapy for individuals with somatic VHL mutations. Despite both patients experiencing a pulmonary crisis with respiratory compromise, their rapid response to belzutifan further emphasizes its potential utility in cases involving pulmonary or visceral crises. This report contributes valuable insights into the treatment landscape for advanced ccRCC with somatic VHL mutations.

HIF-1α signaling: Essential roles in tumorigenesis and implications in targeted therapies

The hypoxic microenvironment is an essential characteristic of most malignant tumors. Notably, hypoxia-inducible factor-1 alpha (HIF-1α) is a key regulatory factor of cellular adaptation to hypoxia, and many critical pathways are correlated with the biological activity of organisms via HIF-1α. In the intra-tumoral hypoxic environment, HIF-1α is highly expressed and contributes to the malignant progression of tumors, which in turn results in a poor prognosis in patients. Recently, it has been indicated that HIF-1α involves in various critical processes of life events and tumor development via regulating the expression of HIF-1α target genes, such as cell proliferation and apoptosis, angiogenesis, glucose metabolism, immune response, therapeutic resistance, etc. Apart from solid tumors, accumulating evidence has revealed that HIF-1α is also closely associated with the development and progression of hematological malignancies, such as leukemia, lymphoma, and multiple myeloma. Targeted inhibition of HIF-1α can facilitate an increased sensitivity of patients with malignancies to relevant therapeutic agents. In the review, we elaborated on the basic structure and biological functions of HIF-1α and summarized their current role in various malignancies. It is expected that they will have future potential for targeted therapy.

Hypoxia inducible factor 1-alpha in the pathogenesis of abdominal aortic aneurysms in vivo: A narrative review

Abdominal aortic aneurysms (AAAs) are relatively common, primarily among older men, and, in the case of rupture, are associated with high mortality. Although procedure-related morbidity and mortality have improved with the advent of endovascular repair, noninvasive treatment and improved assessment of AAA rupture risk should still be sought. Several cellular pathways seem contributory to the histopathologic changes that drive AAA growth and rupture. Hypoxia inducible factor 1-alpha (HIF-1α) is an oxygen-sensitive protein that accumulates in the cytoplasm under hypoxic conditions and regulates a wide array of downstream effectors to hypoxia. Examining the potential role of HIF-1α in the pathogenesis of AAAs is alluring, because local hypoxia is known to be present in the AAA vessel wall. A systematic scoping review was performed to review the current evidence regarding the role of HIF-1α in AAA disease in vivo. After screening, 17 studies were included in the analysis. Experimental animal studies and human studies show increased HIF-1α activity in AAA tissue compared with healthy aorta and a correlation of HIF-1α activity with key histopathologic features of AAA disease. In vivo HIF-1α inhibition in animals protects against AAA development and growth. One study reveals a positive correlation between HIF-1α-activating genetic polymorphisms and the risk of AAA disease in humans. The main findings suggest a causal role of HIF-1α in the pathogenesis of AAAs in vivo. Further research into the HIF-1α pathway in AAA disease might reveal clinically applicable pharmacologic targets or biomarkers relevant in the treatment and monitoring of AAA disease.

Dynamic changes in transcriptome during orthodontic tooth movement

OBJECTIVES

The objective of this study was to determine global changes in gene expression with next generation sequencing (NGS) in order to assess the biological effects of orthodontic tooth movement (OTM) on alveolar bone in a rat model.

MATERIALS AND METHODS

Thirty-five Wistar rats (age 14 weeks) were used in the study. The OTM was performed using closed coil Nickel-Titanium spring to apply a mesial force on maxillary first molars of 8-10 g. Three hours, 1, 3, 7 and 14 days after the placement of the appliance, rats were killed at each time point respectively. The alveolar bone, around left maxillary first molar, were excised on compression side. The samples were immediately frozen in liquid nitrogen for subsequent RNA extraction. Total RNA samples were prepared for mRNA sequencing using the Illumina kit. RNA-Seq reads were aligned to the rat genomes using the STAR Aligner and bioinformatic analysis was performed.

RESULTS

A total of 18 192 genes were determined. Day 1 has the highest number of differentially expressed genes (DEGs) observed with more upregulated than downregulated genes. A total of 2719 DEGs were identified to use as input for the algorithm. Six distinct clusters of temporal patterns were observed representing proteins that were differentially regulated indicating different expression kinetics. Principal component analysis (PCA) showed distinct clustering by time points and days 3, 7 and 14 share similar gene expression pattern.

CONCLUSIONS

Distinct gene expression pattern was observed at different time points studied. Hypoxia, inflammation and bone remodelling pathways are major mechanisms behind OTM.

Long-term HIF-1α stabilization reduces respiration, promotes mitophagy, and results in retinal cell death

Ocular hypertension during glaucoma can lead to hypoxia, activation of the HIF transcription factors, and a metabolic shift toward glycolysis. This study aims to test whether chronic HIF activation and the attendant metabolic reprogramming can initiate glaucoma-associated pathology independently of ocular hypertension. HIF-1α stabilization was induced in mice for 2 and 4 weeks by inhibiting prolyl hydroxylases using the small molecule Roxadustat. HIF-1α stabilization and the expression of its downstream bioenergetic targets were investigated in the retina by immunofluorescence, capillary electrophoresis, and biochemical enzyme activity assays. Roxadustat dosing resulted in significant stabilization of HIF-1α in the retina by 4 weeks, and upregulation in glycolysis-associated proteins (GLUT3, PDK-1) and enzyme activity in both neurons and glia. Accordingly, succinate dehydrogenase, mitochondrial marker MTCO1, and citrate synthase activity were significantly decreased at 4 weeks, while mitophagy was significantly increased. TUNEL assay showed significant apoptosis of cells in the retina, and PERG amplitude was significantly decreased with 4 weeks of HIF-1α stabilization. A significant increase in AMPK activation and glial hypertrophy, concomitant with decreases in retinal ganglion cell function and inner retina cell death suggests that chronic HIF-1α stabilization alone is detrimental to retina metabolic homeostasis and cellular survival.

The cross-talk between macrophages and tumor cells as a target for cancer treatment

Macrophages represent an important component of the innate immune system. Under physiological conditions, macrophages, which are essential phagocytes, maintain a proinflammatory response and repair damaged tissue. However, these processes are often impaired upon tumorigenesis, in which tumor-associated macrophages (TAMs) protect and support the growth, proliferation, and invasion of tumor cells and promote suppression of antitumor immunity. TAM abundance is closely associated with poor outcome of cancer, with impediment of chemotherapy effectiveness and ultimately a dismal therapy response and inferior overall survival. Thus, cross-talk between cancer cells and TAMs is an important target for immune checkpoint therapies and metabolic interventions, spurring interest in it as a therapeutic vulnerability for both hematological cancers and solid tumors. Furthermore, targeting of this cross-talk has emerged as a promising strategy for cancer treatment with the antibody against CD47 protein, a critical macrophage checkpoint recognized as the "don't eat me" signal, as well as other metabolism-focused strategies. Therapies targeting CD47 constitute an important milestone in the advancement of anticancer research and have had promising effects on not only phagocytosis activation but also innate and adaptive immune system activation, effectively counteracting tumor cells' evasion of therapy as shown in the context of myeloid cancers. Targeting of CD47 signaling is only one of several possibilities to reverse the immunosuppressive and tumor-protective tumor environment with the aim of enhancing the antitumor response. Several preclinical studies identified signaling pathways that regulate the recruitment, polarization, or metabolism of TAMs. In this review, we summarize the current understanding of the role of macrophages in cancer progression and the mechanisms by which they communicate with tumor cells. Additionally, we dissect various therapeutic strategies developed to target macrophage-tumor cell cross-talk, including modulation of macrophage polarization, blockade of signaling pathways, and disruption of physical interactions between leukemia cells and macrophages. Finally, we highlight the challenges associated with tumor hypoxia and acidosis as barriers to effective cancer therapy and discuss opportunities for future research in this field.

Isolated ACTH deficiency: an uncommon cause of hyperferritinaemia

Isolated adrenocorticotropic hormone deficiency (IAD) is a rare disorder but not a known cause of hyperferritinaemia. We here report a man with IAD who presented with mild anaemia and unexpected hyperferritinaemia (serum ferritin, 1796 µg/L). He had high serum hepcidin and relatively low erythropoietin levels for his anaemia, with hepcidin and ferritin levels reducing with hydrocortisone supplementation. We speculate that low glucocorticoid levels might suppress erythropoiesis and anti-inflammatory activity, resulting in a higher hepcidin level and hyperferritinaemia. The possibility of adrenal insufficiency including IAD should be considered as a differential diagnosis in patients with unexplained hyperferritinaemia.

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.

Mining gene expression data for rational identification of novel drug targets and vaccine candidates against the cattle tick, Rhipicephalus microplus

Control of complex parasites via vaccination remains challenging, with the current combination of vaccines and small drugs remaining the choice for an integrated control strategy. Studies conducted to date, are providing evidence that multicomponent vaccines will be needed for the development of protective vaccines against endo- and ectoparasites, though multicomponent vaccines require an in-depth understanding of parasite biology which remains insufficient for ticks. With the rapid development and spread of acaricide resistance in ticks, new targets for acaricide development also remains to be identified, along with novel targets that can be exploited for the design of lead compounds. In this study, we analysed the differential gene expression of Rhipicephalus microplus ticks that were fed on cattle vaccinated with a multi-component vaccine (Bm86 and 3 putative Bm86-binding proteins). The data was scrutinised for the identification of vaccine targets, small drug targets and novel pathways that can be evaluated in future studies. Limitations associated with targeting novel proteins for vaccine and/or drug design is also discussed and placed into the context of challenges arising when targeting large protein families and intracellular localised proteins. Lastly, this study provide insight into how Bm86-based vaccines may reduce successful uptake and digestion of the bloodmeal and overall tick fecundity.

Oral squamous cell carcinomas: state of the field and emerging directions

Oral squamous cell carcinoma (OSCC) develops on the mucosal epithelium of the oral cavity. It accounts for approximately 90% of oral malignancies and impairs appearance, pronunciation, swallowing, and flavor perception. In 2020, 377,713 OSCC cases were reported globally. According to the Global Cancer Observatory (GCO), the incidence of OSCC will rise by approximately 40% by 2040, accompanied by a growth in mortality. Persistent exposure to various risk factors, including tobacco, alcohol, betel quid (BQ), and human papillomavirus (HPV), will lead to the development of oral potentially malignant disorders (OPMDs), which are oral mucosal lesions with an increased risk of developing into OSCC. Complex and multifactorial, the oncogenesis process involves genetic alteration, epigenetic modification, and a dysregulated tumor microenvironment. Although various therapeutic interventions, such as chemotherapy, radiation, immunotherapy, and nanomedicine, have been proposed to prevent or treat OSCC and OPMDs, understanding the mechanism of malignancies will facilitate the identification of therapeutic and prognostic factors, thereby improving the efficacy of treatment for OSCC patients. This review summarizes the mechanisms involved in OSCC. Moreover, the current therapeutic interventions and prognostic methods for OSCC and OPMDs are discussed to facilitate comprehension and provide several prospective outlooks for the fields.

An updated meta-analysis on the efficacy and safety of hypoxia-inducible factor prolyl hydroxylase inhibitor treatment of anemia in nondialysis-dependent chronic kidney disease

BACKGROUND

Renal anemia, a common complication and threat factor of chronic kidney disease (CKD), has long been treated with injectable erythropoietin-stimulating agents (ESAs). As concerns regarding cardiovascular safety and erythropoietin resistance to ESAs have emerged, alternative therapies are urgently needed. Hypoxia-inducible factor prolyl hydroxylase inhibitor (HIF-PHI), an oral agent, has been proven to be effective in improving renal anemia. However, the effects of HIF-PHIs on nondialysis-dependent CKD (NDD-CKD) have yet to be supported by updated meta-analyses.

METHODS

A meta-analysis of clinical randomized controlled trials (RCTs) on HIF-PHI treatment of NDD-CKD patients based on PubMed, EMBASE, and Cochrane databases as of July 16th, 2023, was conducted. The primary outcomes were the level of hemoglobin (Hb) postintervention and the ratio of Hb responses. Most of the analysis was conducted via RevMan 5.3 software using a random-effects model. Stata (version 15.0) was used to analyze the publication bias.

RESULTS

Twenty-two studies with a total of 7178 subjects in the HIF-PHI group, 3501 subjects in the ESA group and 2533 subjects in the placebo group were enrolled. HIF-PHIs increased the level of Hb and improved iron metabolism but were not inferior to ESAs in terms of safety.

CONCLUSIONS

HIF-PHIs may be a convenient and safe alternative to ESAs in patients with NDD-CKD and anemia.

Sestrin-2 and hypoxia-ınducible factor-1 alpha levels in major depressive disorder and its subtypes

BACKGROUND

The objective of this study is to measure the levels of sestrin-2 (SESN2) and hypoxia-inducible factor-1 alpha (HIF-1α), which can be determinants in the relevant physiopathology and etiology, assessment of the clinical severity, and identification of new treatment targets in major depressive disorder (MDD) and its subtypes.

METHODS

A total of 230 volunteers, including 153 patients diagnosed with MDD according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and 77 healthy controls, were included in the study. Of the MDD patients included in the study, 40 had melancholic features, 40 had anxious distress features, 38 had atypical features, and the remaining 35 had psychotic features. All participants were administered the Beck's Depression Inventory (BDI) and Clinical Global Impressions-Severity (CGI-S) scale. Serum SESN2 and HIF-1α levels of the participants were measured using the enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

The HIF-1α and SESN2 values of the patient group were found to be significantly lower than those of the control group (p < 0.05). The HIF-1α and SESN2 values were significantly lower in patients with melancholic, anxious distress, and atypical features compared to the control group (p < 0.05). The HIF-1α and SESN2 levels did not differ significantly between patients with psychotic features and the control group (p > 0.05).

CONCLUSION

The findings of the study suggested that knowledge of SESN2 and HIF-1α levels may contribute to the explanation of the etiology of MDD, objective assessment of the severity of the disease, and identification of new treatment targets.

A novel HIF2A mutation causes dyslipidemia and promotes hepatic lipid accumulation

Hypoxia-inducible factor-2α (HIF-2α) is a transcription factor responsible for regulating genes related to angiogenesis and metabolism. This study aims to explore the effect of a previously unreported mutation c.C2473T (p.R825S) in the C-terminal transactivation domain (CTAD) of HIF-2α that we detected in tissue of patients with liver disease. We sequenced available liver and matched blood samples obtained during partial liver resection or liver transplantation performed for clinical indications including hepatocellular carcinoma and liver failure. In tandem, we constructed cell lines and a transgenic mouse model bearing the corresponding identified mutation in HIF-2α from which we extracted primary hepatocytes. Lipid accumulation was evaluated in these cells and liver tissue from the mouse model using Oil Red O staining and biochemical measurements. We identified a mutation in the CTAD of HIF-2α (c.C2473T; p.R825S) in 5 of 356 liver samples obtained from patients with hepatopathy and dyslipidemia. We found that introduction of this mutation into the mouse model led to an elevated triglyceride level, lipid droplet accumulation in liver of the mutant mice and in their extracted primary hepatocytes, and increased transcription of genes related to hepatic fatty acid transport and synthesis in the mutant compared to the control groups. In mutant mice and cells, the protein levels of nuclear HIF-2α and its target perilipin-2 (PLIN2), a lipid droplet-related gene, were also elevated. Decreased lipophagy was observed in mutant groups. Our study defines a subpopulation of dyslipidemia that is caused by this HIF-2α mutation. This may have implications for personalized treatment.

Genome-Wide Analysis of Hypoxia-Inducible Factor Binding Reveals Targets Implicated in Impaired Human Placental Syncytiotrophoblast Formation under Low Oxygen

Preeclampsia (PE) is a common and serious complication of pregnancy with no cure except premature delivery. The root cause of PE is improper development of the placenta-the temporary organ supporting fetal growth and development. Continuous formation of the multinucleated syncytiotrophoblast (STB) layer via differentiation and fusion of cytotrophoblasts (CTBs) is vital for healthy placentation and is impaired in preeclamptic pregnancies. In PE, there is reduced/intermittent placental perfusion, likely resulting in a persistently low O2 environment. Low O2 inhibits differentiation and fusion of CTBs into STB and may thus contribute to PE pathogenesis; however, the underlying mechanisms are unknown. Because low O2 activates a transcription factor complex in cells known as the hypoxia-inducible factor (HIF), the objective of this study was to investigate whether HIF signaling inhibits STB formation by regulating genes required for this process. Culture of primary CTBs, the CTB-like cell line BeWo, and human trophoblast stem cells under low O2 reduced cell fusion and differentiation into STB. Knockdown of aryl hydrocarbon receptor nuclear translocator (a key component of the HIF complex) in BeWo cells restored syncytialization and expression of STB-associated genes under different O2 levels. Chromatin immunoprecipitation sequencing facilitated the identification of global aryl hydrocarbon receptor nuclear translocator/HIF binding sites, including several near genes implicated in STB development, such as ERVH48-1 and BHLHE40, providing new insights into mechanisms underlying pregnancy diseases linked to poor placental O2 supply.

HIF-1α regulates osteoclastogenesis and alveolar bone resorption in periodontitis via ANGPTL4

OBJECTIVE

The mechanism of alveolar bone resorption caused by periodontitis is not fully understood. We sought to investigate whether microenvironmental changes of local hypoxia are involved in these processes.

METHODS

In this study, periodontitis models of control mice and knockout of Hypoxia Induced Factor 1α (HIF-1α) harboring Cathepsin K (CTSK) Cre mice were constructed to study the effect of osteoclasts affected by hypoxic environment on alveolar bone resorption. RAW264.7 cells were subsequently induced by CoCl₂ to observe the effects of HIF-1α and Angiopoietin-like Protein 4 (ANGPTL4) on osteoblast differentiation and fusion.

RESULTS

The degree of alveolar bone resorption in the periodontitis tissues was lesser in mice with conditional knockout of HIF-1α in osteoclasts than in wild-type mice. We also observed that HIF-1α conditional knockout mice had fewer osteoclasts on the alveolar bone surface than control mice. HIF-1α increases the expression of ANGPTL4 and promotes the differentiation of RAW264.7 cells into osteoblasts and cell fusion under chemically simulated hypoxic conditions.

CONCLUSION

HIF-1α regulates osteoclastogenesis and participates in bone resorption in periodontitis through ANGPTL4.

Pathophysiological mechanisms and therapeutic approaches in obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) is a common breathing disorder in sleep in which the airways narrow or collapse during sleep, causing obstructive sleep apnea. The prevalence of OSAS continues to rise worldwide, particularly in middle-aged and elderly individuals. The mechanism of upper airway collapse is incompletely understood but is associated with several factors, including obesity, craniofacial changes, altered muscle function in the upper airway, pharyngeal neuropathy, and fluid shifts to the neck. The main characteristics of OSAS are recurrent pauses in respiration, which lead to intermittent hypoxia (IH) and hypercapnia, accompanied by blood oxygen desaturation and arousal during sleep, which sharply increases the risk of several diseases. This paper first briefly describes the epidemiology, incidence, and pathophysiological mechanisms of OSAS. Next, the alterations in relevant signaling pathways induced by IH are systematically reviewed and discussed. For example, IH can induce gut microbiota (GM) dysbiosis, impair the intestinal barrier, and alter intestinal metabolites. These mechanisms ultimately lead to secondary oxidative stress, systemic inflammation, and sympathetic activation. We then summarize the effects of IH on disease pathogenesis, including cardiocerebrovascular disorders, neurological disorders, metabolic diseases, cancer, reproductive disorders, and COVID-19. Finally, different therapeutic strategies for OSAS caused by different causes are proposed. Multidisciplinary approaches and shared decision-making are necessary for the successful treatment of OSAS in the future, but more randomized controlled trials are needed for further evaluation to define what treatments are best for specific OSAS patients.

Molecular Autopsy in Asphyxia Deaths: Diagnostic Perspectives of miRNAs in the Evaluation of Hypoxia Response

The forensic investigation of asphyxia deaths still poses a challenge due to the need to demonstrate vital exposure to hypoxic insult according to high levels of evidence. The pulmonary effects of hypoxia are complex and the understanding of the mechanisms underlying the acute pneumotoxicity induced by hypoxia is still incomplete. Redox imbalance has been suggested as the protagonist of the main acute changes in pulmonary function in the hypoxic context. The development of knowledge in biochemistry and molecular biology has allowed research in forensic pathology to identify some markers useful in immunohistochemical diagnostics of asphyxia deaths. Several studies have highlighted the diagnostic potential of markers belonging to the HIF-1α and NF-kB pathways. The central role of some highly specific microRNAs has recently been recognized in the complex molecular mechanisms involved in the hypoxia response; thus, several research activities are currently aimed at identifying miRNAs involved in the regulation of oxygen homeostasis (hypoxamiR). The aim of the manuscript is to identify, the miRNAs involved in the early stages of the cellular response to hypoxia, in order to characterize the possible implications in the forensic field of the determination of expression profiles. At present, more than 60 miRNAs involved in the hypoxia response with different expression profiles (upregulation and downregulation) have been identified. Despite the multiple and different effects on reprogramming following the hypoxic insult, the evaluation of the diagnostic implications of hypoxamiRs in the forensic field presupposes a specific treatment of the influences on HIF-1α regulation, cell cycle progression, DNA repair, and apoptosis.

Hypoxia-Inducible Factor-Prolyl-Hydroxylase and Sodium-Glucose Cotransporter 2 Inhibitors for Low-Risk Myelodysplastic Syndrome-Related Anemia in Patients with Chronic Kidney Disease: A Report of Three Cases

Although daprodustat, a hypoxia-inducible factor prolyl hydroxylase inhibitor, and dapagliflozin, a sodium-glucose cotransporter 2 inhibitor, have been approved for the treatment of renal anemia in Japan, their efficacy and safety for patients aged 80 years or older with low-risk myelodysplastic syndrome (MDS)-related anemia have not been demonstrated. Our case series comprised two men and one woman aged >80 years with low-risk MDS-related anemia and diabetic mellitus (DM)-related chronic kidney disease who were dependent on red blood cell transfusions and in whom erythropoiesis-stimulating agents had been insufficient. All three patients received daprodustat and additional dapagliflozin achieved red blood cell transfusion independence and were followed up for >6 months. Daily oral daprodustat was well tolerated. There were no fatalities or progression to acute myeloid leukemia during the >6-month follow-up after daprodustat initiation. On the basis of these outcomes, we consider 24 mg of daprodustat combined with 10 mg of dapagliflozin daily an effective form of treatment for low-risk MDS-related anemia. Further studies are required to clarify the synergistic effects of daprodustat and dapagliflozin, which correct chronic kidney disease-related anemia by promoting endogenous erythropoietin production and normalizing iron metabolism to manage low-risk MDS in the long term.

The involvement of hypoxia inducible factor-1α on the proportion of three types of haemocytes in Chinese mitten crab under hypoxia stress

Hypoxia triggers diverse cell physiological processes, and the hypoxia inducible factors (HIFs) are a family of heterodimeric transcription factors that function as master regulators to respond to hypoxia in different cells. However, the knowledge about the hypoxic responses especially cell alteration mediated by HIFs under hypoxia stress is still limited in crustaceans. In the present study, a hypoxia-inducible factor-1α (HIF-1α) gene was identified (designed as EsHIF-1α). The relative mRNA expression level of EsHIF-1α was highest in hyalinocytes and lowest in granulocytes among three types of haemocytes in crabs. Hypoxia could significantly increase the EsHIF-1α protein expression level in haemocytes. Meanwhile, the proportion of hyalinocytes began to increase from 3 h post hypoxia treatment, and reached the highest level at 24 h. However, the opposite variation in proportion of granulocytes was observed under hypoxia stress. Further investigation showed that the inhibition of EsHIF-1α induced by KC7F2 (HIF-1α inhibitor) could lead to the significant decrease in the proportion of hyalinocytes under hypoxia stress, and also resulted in an increase of granulocytes proportion. While, after EsHIF-1α was activated by IOX4 (HIF-1α activator), the proportion of hyalinocytes was significantly up-regulated and the proportion of granulocytes was significantly down-regulated under post hypoxia treatment. These results collectively suggested that EsHIF-1α was involved in the regulation of proportion of three types of haemocytes induced by hypoxia stress, which provided vital insight into the understanding of the crosstalk between hypoxia and cell development in invertebrates.

Effects of long-term tubular HIF-2α overexpression on progressive renal fibrosis in a chronic kidney disease model

Renal fibrosis is the final manifestation of chronic kidney disease (CKD) regardless of etiology. Hypoxia-inducible factor-2 alpha (HIF-2α) is an important regulator of chronic hypoxia, and the late-stage renal tubular HIF-2α activation exerts protective effects against renal fibrosis. However, its specific role in progressive renal fibrosis remains unclear. Here, we investigated the effects of the long-term tubular activation of HIF-2α on renal function and fibrosis, using in vivo and in vitro models of renal fibrosis. Progressive renal fibrosis was induced in renal tubular epithelial cells (TECs) of tetracycline-controlled HIF-2α transgenic (Tg) mice and wild-type (WT) controls through a 6-week adenine diet. Tg mice were maintained on doxycycline (DOX) for the diet period to induce Tg HIF-2α expression. Primary TECs isolated from Tg mice were treated with DOX (5 μg/ml), transforming growth factor-β1 (TGF-β1) (10 ng/ml), and a combination of both for 24, 48, and 72 hr. Blood was collected to analyze creatinine (Cr) and blood urea nitrogen (BUN) levels. Pathological changes in the kidney tissues were observed using hematoxylin and eosin, Masson's trichrome, and Sirius Red staining. Meanwhile, the expression of fibronectin, E-cadherin and α-smooth muscle actin (α-SMA) and the phosphorylation of p38 mitogenactivated protein kinase (MAPK) was observed using western blotting. Our data showed that serum Cr and BUN levels were significantly lower in Tg mice than in WT mice following the adenine diet. Moreover, the protein levels of fibronectin and E-cadherin and the phosphorylation of p38 MAPK were markedly reduced in the kidneys of adenine-fed Tg mice. These results were accompanied by attenuated fibrosis in Tg mice following adenine administration. Consistent with these findings, HIF-2α overexpression significantly decreased the expression of fibronectin in TECs, whereas an increase in α-SMA protein levels was observed after TGF-β1 stimulation for 72 hr. Taken together, these results indicate that long-term HIF-2α activation in CKD may inhibit the progression of renal fibrosis and improve renal function, suggesting that long-term renal HIF-2α activation may be used as a novel therapeutic strategy for the treatment of CKD. [BMB Reports 2023; 56(3): 196-201].

Iron chelation alleviates multiple pathophysiological pathways in a rat model of cardiac pressure overload

Iron dysmetabolism affects a great proportion of heart failure patients, while chronic hypertension is one of the most common risk factors for heart failure and death in industrialized countries. Serum data from reduced ejection fraction heart failure patients show a relative or absolute iron deficiency, whereas cellular myocardial analyses field equivocal data. An observed increase in organellar iron deposits was incriminated to cause reactive oxygen species formation, lipid peroxidation, and cell death. Therefore, we studied the effects of iron chelation on a rat model of cardiac hypertrophy. Suprarenal abdominal aortic constriction was achieved surgically, with a period of nine weeks to accommodate the development of chronic pressure overload. Next, deferiprone (100 mg/kg/day), a lipid-permeable iron chelator, was administered for two weeks. Pressure overload resulted in increased inflammation, fibrotic remodeling, lipid peroxidation, left ventricular hypertrophy and mitochondrial iron derangements. Deferiprone reduced cardiac inflammation, lipid peroxidation, mitochondrial iron levels, and hypertrophy, without affecting circulating iron levels or ejection fraction. In conclusion, metallic molecules may pose ambivalent effects within the cardiovascular system, with beneficial effects of iron redistribution, chiefly in the mitochondria.

NAD+ supplementation improves mAb productivity in CHO cells via a glucose metabolic shift

Aerobic glycolysis and its by-product lactate accumulation are usually associated with adverse culture phenotypes such as poor cell viability and productivity. Due to the lack of knowledge on underlying mechanisms and accompanying biological processes, the regulation of aerobic glycolysis has been an ongoing challenge in culture process development for therapeutic protein productivity. Nicotinamide adenine dinucleotide (NAD⁺ ), a coenzyme and co-substrate in energy metabolism, promotes the conversion of inefficient glycolysis into an efficient oxidative phosphorylation (OXPHOS) pathway. However, the effect of NAD⁺ on Chinese hamster ovary (CHO) cells for biopharmaceutical production has not been reported yet. In this work, we aimed to elucidate the influence of NAD⁺ on cell culture performance by examining metabolic shifts and mAb productivity. The supplementation of NAD⁺ increased the intracellular concentration of NAD⁺ and promoted SIRT3 expression. Antibody titer and the specific productivity in the growth phase were improved by up to 1.82- and 1.88-fold, respectively, with marginal restrictions on cell growth. NAD⁺ significantly reduced the accumulation of reactive oxygen species (ROS) and the lactate yield from glucose, determined by lactate accumulation versus glucose consumption (Y_LAC/GLC ). In contrast, OXPHOS capacity and amino acid consumption rate increased substantially. Collectively, these results suggest that NAD⁺ contributes to improving therapeutic protein productivity in bioprocessing via inducing an energy metabolic shift.

Bovine blood derived macrophages are unable to control Coxiella burnetii replication under hypoxic conditions

Background

Coxiella burnetii is a zoonotic pathogen, infecting humans, livestock, pets, birds and ticks. Domestic ruminants such as cattle, sheep, and goats are the main reservoir and major cause of human infection. Infected ruminants are usually asymptomatic, while in humans infection can cause significant disease. Human and bovine macrophages differ in their permissiveness for C. burnetii strains from different host species and of various genotypes and their subsequent host cell response, but the underlying mechanism(s) at the cellular level are unknown.

Methods

C. burnetii infected primary human and bovine macrophages under normoxic and hypoxic conditions were analyzed for (i) bacterial replication by CFU counts and immunofluorescence; (ii) immune regulators by westernblot and qRT-PCR; cytokines by ELISA; and metabolites by gas chromatography-mass spectrometry (GC-MS).

Results

Here, we confirmed that peripheral blood-derived human macrophages prevent C. burnetii replication under oxygen-limiting conditions. In contrast, oxygen content had no influence on C. burnetii replication in bovine peripheral blood-derived macrophages. In hypoxic infected bovine macrophages, STAT3 is activated, even though HIF1α is stabilized, which otherwise prevents STAT3 activation in human macrophages. In addition, the TNFα mRNA level is higher in hypoxic than normoxic human macrophages, which correlates with increased secretion of TNFα and control of C. burnetii replication. In contrast, oxygen limitation does not impact TNFα mRNA levels in C. burnetii-infected bovine macrophages and secretion of TNFα is blocked. As TNFα is also involved in the control of C. burnetii replication in bovine macrophages, this cytokine is important for cell autonomous control and its absence is partially responsible for the ability of C. burnetii to replicate in hypoxic bovine macrophages. Further unveiling the molecular basis of macrophage-mediated control of C. burnetii replication might be the first step towards the development of host directed intervention measures to mitigate the health burden of this zoonotic agent.

Hypoxia-Driven Changes in a Human Intestinal Organoid Model and the Protective Effects of Hydrolyzed Whey

Many whey proteins, peptides and protein-derived amino acids have been suggested to improve gut health through their anti-oxidant, anti-microbial, barrier-protective and immune-modulating effects. Interestingly, although the degree of hydrolysis influences peptide composition and, thereby, biological function, this important aspect is often overlooked. In the current study, we aimed to investigate the effects of whey protein fractions with different degrees of enzymatic hydrolysis on the intestinal epithelium in health and disease with a novel 2D human intestinal organoid (HIO) monolayer model. In addition, we aimed to assess the anti-microbial activity and immune effects of the whey protein fractions. Human intestinal organoids were cultured from adult small intestines, and a model enabling apical administration of nutritional components during hypoxia-induced intestinal inflammation and normoxia (control) in crypt-like and villus-like HIO was established. Subsequently, the potential beneficial effects of whey protein isolate (WPI) and two whey protein hydrolysates with a 27.7% degree of hydrolysis (DH28) and a 50.9% degree of hydrolysis (DH51) were assessed. In addition, possible immune modulatory effects on human peripheral immune cells and anti-microbial activity on four microbial strains of the whey protein fractions were investigated. Exposure to DH28 prevented paracellular barrier loss of crypt-like HIO following hypoxia-induced intestinal inflammation with a concomitant decrease in hypoxia inducible factor 1 alpha (HIF1α) mRNA expression. WPI increased Treg numbers and Treg expression of cluster of differentiation 25 (CD25) and CD69 and reduced CD4+ T cell proliferation, whereas no anti-microbial effects were observed. The observed biological effects were differentially mediated by diverse whey protein fractions, indicating that (degree of) hydrolysis influences their biological effects. Moreover, these new insights may provide opportunities to improve immune tolerance and promote intestinal health.

Severinia buxifolia-isolated acridones inhibit lung cancer invasion and decrease HIFα protein synthesis involving 5'UTR-mediated translation inhibition

BACKGROUND

Lung cancer is one of the most common cancers worldwide and is by far the leading cause of cancer death attributed to its rapid metastasis and poor prognosis. Given that hypoxia-inducible factors (HIFs) are associated with cancer metastasis, discovering agents to inhibit HIF-mediated invasive cancer is highly desired.

PURPOSE

This study aimed to investigate the natural acridone compounds isolated from Severinia buxifolia for the potential to delay hypoxia-induced lung cancer invasiveness by HIF inhibition.

METHODS

Using a hypoxia-responsive element (HRE) luciferase reporter, cell migration and invasion assays, real-time PCR, Western blot, and DNA recombinant clones, compound effect on HIF activity, cancer metastasis, HIF-1α mRNA transcription, HIFs protein stability, and HIF-1α translation were observed under hypoxia conditions.

RESULTS

Atalaphyllidine (Sbs-A) and atalaphyllinine (Sbs-B) were found to show the most potent effects on HIF transcriptional activity and HIF-1α protein expression in NSCLC cell line A549, although Sbs-A and Sbs-B might not attribute decreasing HIF-1α mRNA expression to potent inhibition of HIF activity. HIF-1α protein stability was not affected by Sbs-A; also, prolyl hydroxylase and proteasome inhibitors could not reverse the inhibitory effect from compounds. Furthermore, 3 - 10 μM low concentrations of Sbs-A inhibited HIF target gene expression, gelatin zymography activity, and A549 cancer invasion. Ultimately, Sbs-A inhibited HIF-1α 5'UTR-mediated translation independent of oxygen concentration, underlying the mechanism of compounds inhibiting HIF-1α protein expression.

CONCLUSION

Our study proposed Severinia buxifolia-isolated acridone compounds inhibited 5'-mRNA HIFA-mediated translation and provided evidence supporting the ability of acridone compounds in targeting HIFα for delayed lung cancer metastasis.

Updated perspective of EPAS1 and the role in pulmonary hypertension

Pulmonary hypertension (PH) is a group of syndromes characterized by irreversible vascular remodeling and persistent elevation of pulmonary vascular resistance and pressure, leading to ultimately right heart failure and even death. Current therapeutic strategies mainly focus on symptoms alleviation by stimulating pulmonary vessel dilation. Unfortunately, the mechanism and interventional management of vascular remodeling are still yet unrevealed. Hypoxia plays a central role in the pathogenesis of PH and numerous studies have shown the relationship between PH and hypoxia-inducible factors family. EPAS1, known as hypoxia-inducible factor-2 alpha (HIF-2α), functions as a transcription factor participating in various cellular pathways. However, the detailed mechanism of EPAS1 has not been fully and systematically described. This article exhibited a comprehensive summary of EPAS1 including the molecular structure, biological function and regulatory network in PH and other relevant cardiovascular diseases, and furthermore, provided theoretical reference for the potential novel target for future PH intervention.

The Normobaric Oxygen Paradox-Hyperoxic Hypoxic Paradox: A Novel Expedient Strategy in Hematopoiesis Clinical Issues

Hypoxia, even at non-lethal levels, is one of the most stressful events for all aerobic organisms as it significantly affects a wide spectrum of physiological functions and energy production. Aerobic organisms activate countless molecular responses directed to respond at cellular, tissue, organ, and whole-body levels to cope with oxygen shortage allowing survival, including enhanced neo-angiogenesis and systemic oxygen delivery. The benefits of hypoxia may be evoked without its detrimental consequences by exploiting the so-called normobaric oxygen paradox. The intermittent shift between hyperoxic-normoxic exposure, in addition to being safe and feasible, has been shown to enhance erythropoietin production and raise hemoglobin levels with numerous different potential applications in many fields of therapy as a new strategy for surgical preconditioning aimed at frail patients and prevention of postoperative anemia. This narrative review summarizes the physiological processes behind the proposed normobaric oxygen paradox, focusing on the latest scientific evidence and the potential applications for this strategy. Future possibilities for hyperoxic-normoxic exposure therapy include implementation as a synergistic strategy to improve a patient's pre-surgical condition, a stimulating treatment in critically ill patients, preconditioning of athletes during physical preparation, and, in combination with surgery and conventional chemotherapy, to improve patients' outcomes and quality of life.

Response to roxadustat in a patient undergoing long-term dialysis and allergic to erythropoiesis-stimulating agents: A case report

BACKGROUND

Hypoxia-inducible factor prolyl hydroxylase inhibitor is a new class of drugs for treating renal anemia. It is a second-generation hypoxia-inducible factor prolyl hydroxylase-2 (PHD2) inhibitor. Roxadustat can effectively increase hemoglobin in patients with dialysis-dependent chronic kidney disease, with an adverse events profile comparable to that of epoetin alfa. We administered roxadustat to a maintenance hemodialysis patient who was allergic to erythropoiesis-stimulating agents (ESAs) and depended on blood transfusion for five years. After applying Roxadustat, the patient’s anemia improved significantly.

CASE SUMMARY

A 77-year-old Chinese man had type 2 diabetes for 16 years, underwent maintenance hemodialysis for five years, and had fatigue for five years. Laboratory tests showed severe anemia (hemoglobin concentration of 42 g/L). The patient was administered a subcutaneous injection of ESAs before dialysis. He suffered an allergic shock immediately and fainted. His blood pressure dropped to undetectable levels. He was not administered ESAs henceforth. The patient was prescribed iron supplements and received blood transfusions occasionally for five years. His hemoglobin concentration ranged from 42-68 g/L. After taking six weeks of oral roxadustat three times weekly (100 mg TIW), the patient’s hemoglobin concentration increased significantly, and his symptoms decreased. We adjusted the doses of roxadustat, and the hemoglobin concentration was maintained between 97 and 126 g/L.

CONCLUSION

Oral roxadustat is effective in treating anemia in maintenance hemodialysis patients who cannot be administered ESAs.

Role of the Hypoxic-Secretome in Seed and Soil Metastatic Preparation

During tumor growth, the delivery of oxygen to cells is impaired due to aberrant or absent vasculature. This causes an adaptative response that activates the expression of genes that control several essential processes, such as glycolysis, neovascularization, immune suppression, and the cancer stemness phenotype, leading to increased metastasis and resistance to therapy. Hypoxic tumor cells also respond to an altered hypoxic microenvironment by secreting vesicles, factors, cytokines and nucleic acids that modify not only the immediate microenvironment but also organs at distant sites, allowing or facilitating the attachment and growth of tumor cells and contributing to metastasis. Hypoxia induces the release of molecules of different biochemical natures, either secreted or inside extracellular vesicles, and both tumor cells and stromal cells are involved in this process. The mechanisms by which these signals that can modify the premetastatic niche are sent from the primary tumor site include changes in the extracellular matrix, recruitment and activation of different stromal cells and immune or nonimmune cells, metabolic reprogramming, and molecular signaling network rewiring. In this review, we will discuss how hypoxia might alter the premetastatic niche through different signaling molecules.

Effects of hypoxia and reoxygenation on mitochondrial functions and transcriptional profiles of isolated brain and muscle porcine cells

Oxygen fluctuations might occur in mammalian tissues under physiological (e.g. at high altitudes) or pathological (e.g. ischemia-reperfusion) conditions. Mitochondria are the key target and potential amplifiers of hypoxia-reoxygenation (H-R) stress. Understanding the mitochondrial responses to H-R stress is important for identifying adaptive mechanisms and potential therapeutic solutions for pathologies associated with oxygen fluctuations. We explored metabolic response to H-R stress in two tissue types (muscle and brain) with different degrees of hypoxia tolerance in a domestic pig Sus scrofa focusing on the cellular responses independent of the systemic regulatory mechanisms. Isolated cells from the skeletal muscle (masseter) and brain (thalamus) were exposed to acute short-term (15 min) hypoxia followed by reoxygenation. The mitochondrial oxygen consumption, reactive oxygen species (ROS) production rates and transcriptional profiles of hypoxia-responsive mRNA and miRNA were determined. Mitochondria of the porcine brain cells showed a decrease in the resting respiration and ATP synthesis capacity whereas the mitochondria from the muscle cells showed robust respiration and less susceptibility to H-R stress. ROS production was not affected by the short-term H-R stress in the brain or muscle cells. Transcriptionally, prolyl hydroxylase domain protein EGLN3 was upregulated during hypoxia and suppressed during reoxygenation in porcine muscle cells. The decline in EGLN3 mRNA during reoxygenation was accompanied by an upregulation of hypoxia-inducible factor subunit α (HIF1A) transcripts in the muscle cells. However, in the brain cells, HIF1A mRNA levels were suppressed during reoxygenation. Other functionally important transcripts and miRNAs involved in antioxidant response, apoptosis, inflammation, and substrate oxidation were also differentially expressed between the muscle and brain cells. Suppression of miRNA levels during acute intermittent hypoxia was stronger in the brain cells affecting ~ 55% of all studied miRNA transcripts than in the muscle cells (~ 25% of miRNA) signifying transcriptional derepression of the respective mRNA targets. Our study provides insights into the potential molecular and physiological mechanisms contributing to different hypoxia sensitivity of the studied tissues and can serve as a starting point to better understand the biological processes associated with hypoxia stress, e.g. during ischemia and reperfusion.