HIF-1: mediator of physiological and pathophysiological responses to hypoxia

Co-expression of HIF1A with multi-drug transporters (P-GP, MRP1, and BCRP) in chemoresistant breast, colorectal, and ovarian cancer cells

Therapeutic resistance poses a significant challenge in treating most cancers and often leads to poor clinical outcomes and even treatment failure. One of the primary mechanisms that confer multidrug resistance phenotype to cancer cells is the hyperactivity of certain drug efflux transporters. P-GP, MRP1, and BCRP are the key ABC efflux pumps that collectively extrude a broad spectrum of chemotherapeutic drugs. Besides, HIF1A, a master transcription regulatory protein, is also associated with cancer development and therapeutic resistance. Thereby, this study aimed to delve into the mechanisms of drug resistance, specifically focusing on HIF1A-driven overexpression of ABC transporters. A total of 57 chemoresistant and 57 paired control tissue samples (breast, colorectal, and ovarian) from Bangladeshi cancer patients were analyzed to determine the co-expression level of ABC transporters and HIF1A. Molecular docking was also conducted to evaluate the interactions of HIF1A protein and hypoxia response element (HRE) sequences in the promoter regions transporter genes. This study revealed that HIF1A is significantly overexpressed in chemoresistant tissues, suggesting its pivotal role in chemoresistance mechanisms across malignancies and its potential as a target to overcome therapeutic resistance. The findings from this study also suggest a direct upregulation of ABCB1, ABCC1, and ABCG2 transcription by HIF1A in chemoresistant cancer cells by binding to the HRE sequence in the promoter regions. Thus, inhibition of these interactions of HIF1A appears to be a promising approach to reverse chemoresistance. The findings of this study can serve as a foundation for future research, resolving molecular intricacies to improve treatment outcomes in chemoresistant patients.

Deciphering the role of circular RNAs in cancer progression under hypoxic conditions

Hypoxia, characterized by reduced oxygen levels, plays a pivotal role in cancer progression, profoundly influencing tumor behavior and therapeutic responses. A hallmark of solid tumors, hypoxia drives significant metabolic adaptations in cancer cells, primarily mediated by hypoxia-inducible factor-1α (HIF-1α), a key transcription factor activated in low-oxygen conditions. This hypoxic environment promotes epithelial-mesenchymal transition (EMT), enhancing cancer cell migration, metastasis, and the development of cancer stem cell-like properties, which contribute to therapy resistance. Moreover, hypoxia modulates the expression of circular RNAs (circRNAs), leading to their accumulation in the tumor microenvironment. These hypoxia-responsive circRNAs regulate gene expression and cellular processes critical for cancer progression, making them promising candidates for diagnostic and prognostic biomarkers in various cancers. This review delves into the intricate interplay between hypoxic circRNAs, microRNAs, and RNA-binding proteins, emphasizing their role as molecular sponges that modulate gene expression and signaling pathways involved in cell proliferation, apoptosis, and metastasis. It also explores the relationship between circRNAs and the tumor microenvironment, particularly how hypoxia influences their expression and functional dynamics. Additionally, the review highlights the potential of circRNAs as diagnostic and prognostic tools, as well as their therapeutic applications in innovative cancer treatments. By consolidating current knowledge, this review underscores the critical role of circRNAs in cancer biology and paves the way for future research aimed at harnessing their unique properties for clinical advancements. Specifically, this review examines the biogenesis, expression patterns, and mechanistic actions of hypoxic circRNAs, focusing on their ability to act as molecular sponges for microRNAs and their interactions with RNA-binding proteins. These interactions impact key signaling pathways related to tumor growth, metastasis, and drug resistance, offering new insights into the complex regulatory networks governed by circRNAs under hypoxic stress.

Differential expression and correlation analysis of global transcriptome for obstructive sleep apnea hypopnea syndrome

In order to investigate the gene expression patterns and molecular regulatory mechanisms of obstructive sleep apnea hypopnea syndrome (OSAHS), the global transcriptome expression profiles of OSAHS patients and healthy people were analyzed using transcriptome sequencing technology. Differential expression of circular RNA, microRNA, long noncoding RNA, and messenger RNA was investigated between the two groups. To further explore the role of differentially expressed genes in OSAHS, we functionally annotated the differentially expressed genes using enrichment analysis of GO and KEGG pathways. Finally, the ceRNA regulatory network of OSAHS was constructed. And validate the differentially expressed mRNA through qRT-PCR analysis. The results showed that 349 circRNAs,552 lncRNAs,205 miRNAs, 502 mRNAs were differentially expressed in patients with OSAHS compared with the healthy population. Terms such as centrosome, positive regulation of execution phase of apoptosis, oxidoreductase activity, regulation of Th 17 cell differentiation and immune response, neutrophil mediated cytotoxicity were enriched in the GO list, suggesting a potential correlation with OSAHS. Pathway analysis showed that Ferroptosis, Herpes simplex virus 1 infection, Pathways in cancer, Hematopoietic cell lineage and other pathways play an important role in OSAHS. By constructing a ternary network, two circRNAs and four lncRNAs were screened as ceRNAs to compete with miRNAs in the co-expression network, and associated with OSAHS by regulating the function of mRNAs in the network. By constructing a quaternary network miR-8485 and miR-6089 were found to be the top two ranked miRNAs most closely associated with OSAHS. Both qRT-PCR and transcriptome sequencing analysis showed similar trends. This provides more theoretical basis for exploring the complex molecular mechanisms of global transcriptome in the development of OSAHS.

The potential of miR-29 in modulating tumor angiogenesis: a comprehensive review

MicroRNAs (miRNAs) are a class of short non-coding RNAs that play a crucial role in the post-transcriptional regulation of gene expression. They are associated with various biological processes related to tumors. Among the numerous miRNAs, miR-29 has garnered attention for its role in regulating tumor angiogenesis. In numerous human tumors, miR-29 has been demonstrated to negatively correlate with the capacity for angiogenesis and the degree of malignancy, as well as with the expression levels of pro-angiogenic factors such as vascular endothelial growth factor vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and matrix metalloproteinase (MMP)-2. Multiple studies, utilizing techniques like dual-luciferase reporter assays, have confirmed that miR-29 directly targets the 3'-untranslated region (UTR) of mRNAs for VEGF, PDGF, and MMP-2. Extensive investigations involving tumor cell lines and animal models have shown that the overexpression of miR-29, achieved through miRNA transfection or the introduction of miRNA mimics, effectively inhibits angiogenesis by upregulating these pro-angiogenic factors. Conversely, downregulation of miR-29 using specific inhibitors promotes angiogenesis. While small molecule inhibitors and antibodies targeting VEGF constitute a primary strategy in anti-angiogenesis therapies, miR-29's ability to target multiple pro-angiogenic molecules positions it as a promising candidate for future therapeutic interventions, especially with ongoing advancements in nucleic acid drug design and delivery systems.

Hematological Adaptations to Altitude Training in Female Water Polo Players: A Case Report of a World Championships Medal-Winning Team

BACKGROUND

The effective monitoring of athletes' adaptation is crucial to optimize the outcomes of altitude camps and minimize the risk of maladaptation to the hypoxic stress and intensive training. This case report assessed the hematological adaptations in 22 world-class female water polo players during a 16-day 'live high-train high' (LHTH) altitude camp (2320 m) and evaluated the differences between selected (n = 13) and non-selected (n = 9) players and between playing positions.

METHODS

Hematological parameters, including total hemoglobin mass (tHBmass) and blood volume, were measured before and after the camp. Resting heart rate, peripheral oxygen saturation, body mass, fatigue, and sleep were monitored daily.

RESULTS

Relative tHbmass increased PRE to POST (5.4 ± 5.1%, range -3.9-20.2), but blood volume did not change (p = 0.797). Erythrocyte count, hemoglobin concentration, hematocrit, and red cell distribution width increased PRE-POST (p < 0.001, ES = 1.21-2.69), while mean corpuscular volume and hemoglobin decreased (p < 0.001, ES = 0.51 and 0.72, respectively). No substantial differences were observed in the hematological parameters between selected and non-selected players. There was a large difference in the change in relative blood volume between centers (n = 4, PRE 74.1 ± 5.4, POST 69.7 ± 5.9 mL/kg; mean ± SD) and field players (n = 15, PRE 80.8 ± 10.6, POST 82.8 ± 6.8 mL/kg; adj p = 0.046, ES = 1.15) and between centers and goalkeepers (n = 3, PRE 89.7 ± 9.6, POST 82.0 ± 7.1 mL/kg; adj p = 0.046, ES = 1.62).

CONCLUSIONS

A 16-day LHTH camp can induce favorable hematological adaptations in world-class women's water polo players, without substantial differences between selected and non-selected players, and larger increases in field players.

Leukemia inhibitory factor in peripheral blood as a prognostic marker in breast cancer

PURPOSE

Analysis of gene expression profiles in peripheral blood cells has been explored as an approach for early detection of breast cancer. Thus, we aimed to evaluate the diagnostic and prognostic potential of LIF expression in the peripheral blood of women with breast cancer.

METHODS

A total of 121 women over 18 years of age with breast cancer and 80 healthy women were included. Peripheral blood samples were collected from patients at diagnosis and during chemotherapy treatment, as well as samples from healthy women for comparison. LIF expression was evaluated by qPCR.

RESULTS

LIF expression does not differ between patients and healthy women, ruling out its use as a liquid biopsy diagnostic tool for this disease. However, LIF expression increases during treatment in patients with positive progression and luminal tumor subtype, suggesting its potential as a prognostic marker. To reinforce this result, there was a negative correlation between LIF and HIF-1α and LIF and heparanase expression in blood, and LIF blood expression and a prognostic tumor score, all known markers associated with an unfavorable prognosis.

CONCLUSION

An increase in LIF expression in patients with negative disease progression suggests its potential as a therapeutic response indicator, particularly for those with the luminal tumor subtype. The negative correlation between LIF, HIF-1α, and heparanase provides new insights into LIF's role in breast cancer progression, with potential clinical implications for treatment monitoring. Elevated LIF expression in blood samples may reflect its interaction in tumorigenesis, immune regulation, and the tumor microenvironment.

Dynamic Regulation of HIF1α and Oxygen-Sensing Factors in Cyclic Bovine Corpus Luteum and During LPS Challenge

Understanding the corpus luteum (CL) and its role in cattle reproduction is crucial, particularly as it is a progesterone source for the establishment and maintenance of pregnancy. Reduced oxygen levels significantly impact these processes. This study investigated the effects of the luteal stage on the spatio-temporal gene expression patterns of HIF1α and oxygen-sensing factors, as well as the impact of lipopolysaccharide (LPS)-induced inflammation on these factors. Endothelial inflammatory responses were also addressed. The samples included CL collected at the early, mid, and late stages, as well as biopsies from mid-luteal stage cows treated either with saline (controls) or LPS. Samples collected in subsequent cycles assessed potential carryover effects. RT-PCR revealed upregulation of HIF1α, PHD1, PHD3, FIH, and VHL encoding genes in the mid-luteal stage. In situ hybridization revealed the compartmentalization of HIF1α and its regulators within the luteal and endothelial cells, suggesting their cell-specific roles. LPS treatment affected PHD1 and PHD3 expression, while increasing endothelial pro-inflammatory factors ICAM1 and NFκB, suggesting vascular inflammation and modulated oxygen sensing. These findings reveal new insights into the spatio-temporal expression of HIF1α-regulating factors in the CL, highlighting their potential role in controlling luteal function, detailing their cellular compartmentalization, and the effects of LPS-mediated inflammatory responses.

2-Oxoglutarate-dependent dioxygenases as oxygen sensors: their importance in health and disease

Since low oxygen conditions below physiological levels, hypoxia, are associated with various diseases, it is crucial to understand the molecular basis behind cellular response to hypoxia. Hypoxia-inducible factors (HIFs) have been revealed to primarily orchestrate the hypoxic response at the transcription level and have continuously attracted great attention over the past three decades. In addition to these hypoxia-responsive effector proteins, 2-oxoglutarate-dependent dioxygenase (2-OGDD) superfamily including prolyl-4-hydroxylase domain-containing proteins (PHDs) and factor inhibiting HIF-1 (FIH-1) has attracted even greater attention in recent years as factors that act as direct oxygen sensors due to their necessity of oxygen for the regulation of the expression and activity of the regulatory subunit of HIFs. Herein, we present a detailed classification of 2-OGDD superfamily proteins, such as Jumonji C-domain-containing histone demethylases, ten-eleven translocation enzymes, AlkB family of DNA/RNA demethylases and lysyl hydroxylases, and discuss their specific functions and associations with various diseases. By introducing the multifaceted roles of 2-OGDD superfamily proteins in the hypoxic response, this review aims to summarize the accumulated knowledge about the complex mechanisms governing cellular adaptation to hypoxia in various physiological and pathophysiological contexts.

BHLHE41, a transcriptional repressor involved in physiological processes and tumor development

BHLHE41 is a nuclear transcriptional repressor that belongs to the basic helix-loop-helix protein superfamily. BHLHE41 expression tends to be restricted to specific tissues and is regulated by environmental cues and biological events. BHLHE41 homodimerizes or heterodimerizes with various partners, influencing its transcription factor function. BHLHE41 is involved in the regulation of many physiological processes implicated in tissue/organ homeostasis, such as myogenesis, adipogenesis, circadian rhythms and DNA repair. At cellular level, BHLHE41 is involved in the regulation of mesenchymal stem cell properties, tissue-specific macrophage functions and lymphoid lineage physiology. In several cancer types, BHLHE41 modulates the expression of different transcriptional programs influencing cell cycle control, apoptosis, invasiveness, epithelial to mesenchymal transition and hypoxia response in the tumor environment. Depending on the cancer cell type, BHLHE41 can act as a tumor suppressor or an oncogene, and could be a target for innovative therapies. This review summarizes the available knowledge on BHLHE41 structure, biological functions, regulation and potential partners, as well as its role in physiological processes, and its implication in major cancer steps.

Advances in nanoparticle-based radiotherapy for cancer treatment

Radiotherapy has long been recognized as an effective conventional approach in both clinical and scientific research, primarily through mechanisms involving DNA destruction or the generation of reactive oxygen species to target tumors. However, significant challenges persist, including the unavoidable damage to normal tissues and the development of radiation resistance. As a result, nanotechnology-based radiotherapy has garnered considerable attention for its potential to enhance precision in irradiation, improve radiosensitization, and achieve therapeutic advancements. Importantly, radiotherapy alone frequently falls short of fully eradicating tumors. Consequently, to augment the efficacy of radiotherapy, it is often integrated with other therapeutic strategies. This review elucidates the mechanisms of radiotherapy sensitization based on diverse nanoparticles. Typically, radiotherapy is sensitized through augmenting reactive oxygen species production, targeted radiotherapy, hypoxia relief, enhancement of antitumor immune microenvironment, and G2/M cell cycle arrest. Moreover, the incorporation of nanoparticle-based anti-tumor strategies with radiotherapy markedly enhances the current state of radiotherapy. Additionally, a compilation of clinical trials utilizing nano-radioenhancers is presented. Finally, future prospects for clinical translation in this field are thoroughly examined.

Efficacy and Safety of Roxadustat for Anemia in Patients Receiving Chemotherapy for Nonmyeloid Malignancies: A Randomized, Open-Label, Active-Controlled Phase III Study

PURPOSE

We evaluated the efficacy and safety of roxadustat, a first-in-class hypoxia-inducible factor prolyl hydroxylase inhibitor, for chemotherapy-induced anemia (CIA) in patients with nonmyeloid malignancies receiving multicycle treatments of chemotherapy.

PATIENTS AND METHODS

In this open-label, noninferiority phase III study conducted at 44 sites in China, 159 participants age ≥18 years with CIA nonmyeloid malignancy and CIA were randomly assigned (1:1) to oral roxadustat or subcutaneous recombinant human erythropoietin-α (rHuEPO-α) three times a week for 12 weeks. Roxadustat starting dosages were 100, 120, and 150 mg three times a week for participants weighing 40-<50, 50-60, and >60 kg, respectively. rHuEPO-α starting dosage for all participants was 150 IU/kg three times a week. Both roxadustat and rHuEPO-α dosages could be modified. The primary end point was least-squares mean (LSM) change in hemoglobin (Hb) concentration from baseline to the concentration averaged over weeks 9-13.

RESULTS

Of the 159 participants randomly assigned, 140 were included in the per-protocol set (roxadustat, n = 78; rHuEPO-α, n = 62). The LSM (95% two-sided CI) change from baseline to weeks 9-13 in Hb concentration was 17.1 (13.58 to 20.71) g/L with roxadustat and 15.4 (11.34 to 19.50) g/L with rHuEPO-α (mean difference [95% CI], 1.7 [-3.39 to 6.84]). The lower bound of the one-sided 97.5% CI for the treatment difference (‒3.4 g/L) was greater than the predefined noninferiority margin of ‒6.6 g/L, establishing noninferiority. Noninferiority was supported by five of six key secondary end points. Rates of adverse events were generally comparable between treatments and consistent with previous findings.

CONCLUSION

Roxadustat was noninferior to rHuEPO-α in treating CIA in participants with nonmyeloid malignancies receiving multicycle treatments of myelosuppressive chemotherapy. The oral formulation of roxadustat may potentially increase compliance.

Mechanistic insights into gut microbe derived siderophores and PHD2 interactions with implications for HIF-1α stabilization

In oxygen-deprived conditions, cells respond by activating adaptive mechanisms to bolster their survival and protect tissue integrity. A key player in this process is the HIF-1α signaling cascade, meticulously regulated by Prolyl Hydroxylase Domain 2 (PHD2), which orchestrates cellular responses to varying oxygen levels. The primary aim of this investigation is to utilize gut siderophores as inhibitors of PHD2 in ischemic conditions. This study also helps in understanding the structural mechanisms by which gut microbiota regulate HIF-1α via PHD2 inhibition through the secretion of siderophores. We explore potential PHD2 inhibitors through in-silico approaches, specifically molecular docking, binding pose metadynamics, molecular dynamics simulations, and free energy calculations. We evaluated siderophores secreted by gut microbiota as candidate inhibitors for PHD2. Docking studies revealed that Salmochelin SX exhibits the highest binding affinity to PHD2 (- 9.527 kcal/mol), interacting with key residues such as ASP254, TYR310, ASP315, and ARG322. Despite its high affinity, binding pose metadynamics indicated instability for Salmochelin SX, whereas Staphyloferrin A demonstrated superior stability. Molecular dynamics simulations confirmed stable ligand interactions with PHD2, highlighting HIS313 and ASP315 as critical for inhibition. Principal Component Analysis (PCA) and Free Energy Landscape (FEL) analyses underscored conformational changes and binding stability, suggesting that these interactions may stabilize PHD2's active site and have potential therapeutic implications. Additionally, the study reveals how gut microbiota prevent gut dysbiosis through the stabilization of HIF-1α signaling by secreting siderophores.

A preliminary exploration of establishing a mice model of hypoxic training

Altitude training has been widely adopted. This study aimed to establish a mice model to determine the time point for achieving the best endurance at the lowland. C57BL/6 and BALB/c male mice were used to establish a mice model of hypoxic training with normoxic training mice, hypoxic mice, and normoxic mice as controls. All hypoxic mice were placed in a chamber filled with 16% O2 and N2, and hypoxic training mice were trained for two weeks. Then mice were removed from the chamber and tested at normoxic conditions weekly at the beginning of the experiment and the second, third, fourth, and sixth weeks. The tests for endurance ability include maximal aerobic speed (MAS), Rota-rod, and grip strength. In addition, the open field, visual cliff, and Y maze were used to test cognitive abilities. Body composition and lactic acid tolerance level were also measured. For BALB/c but not C57BL/6 mice were evaluated for effectively training. Based on the average MAS of all mice, mice successfully passed the training according to the procedure: the first week (32%MAS/10min, 48%MAS/10min, and 64%MAS/10min) and second week (40%MAS/10min, 56%MAS/10min, and 72%MAS/10min). Hypoxic training mice reached peak rotarod performance on the 7th day post-training (Test 3), with significant improvements compared to Test 1, 2, 4, and 5. At Test 3, their rotarod scores significantly differed from both H and N groups, and showing a trend towards difference from NT group. Meanwhile, hypoxic mice showed significant cognitive impairment, anxiety, depression, muscle loss, and fat gain compared with hypoxic training mice after hypoxia intervation. Two consecutive weeks of 16% O2 training followed by one week of reoxygenation may be the best for endurance competition. Thus, we think a mouse model for hypoxic training was built, with Rota-rod testing as a detection indicator. Moreover, hypoxic training may alleviate the damage of hypoxia to the body.

Liver Kinase B1 Protects Against Hypoxia-Induced Pulmonary Arterial Endothelial Cell Dysfunction via the AMP-Activated Protein Kinase Pathway

Pulmonary hypertension (PH) is a progressive disease characterized by vascular reHypoxiaing, endothelial cell dysfunction, and inflammation. Liver Kinase B1 (LKB1, also known as STK11) is a central regulator of cell polarity and energy homeostasis. However, its specific role and mechanism of action in PH remain unclear. Human pulmonary arterial endothelial cells (hPAECs) were cultured in vitro to establish PH cell Hypoxias under normoxic and hypoxic conditions. The expression of LKB1 was detected by reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) and western blotting, and its effect on hPAECs function was investigated by overexpression and inhibition of LKB1. Furthermore, cell proliferation was assessed using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay, apoptosis was measured by flow cytometry, inflammatory cytokine secretion was evaluated using enzyme-linked immunosorbent assay (ELISA), and the expression of AMP-activated protein kinase (AMPK) signaling pathway-related proteins was analyzed by western blotting. LKB1 expression was significantly reduced in hypoxia-treated hPAECs compared with that in normoxic controls, and LKB1 overexpression significantly ameliorated the hypoxia-induced decrease in cell proliferation and increase in apoptosis as well as inflammatory factor secretion. The AMPK agonist (GSK621) reversed the dysfunction caused by LKB1 inhibition, indicating that LKB1 regulates hPAECs function through the AMPK signaling pathway. LKB1 plays a protective role in PH by inhibiting hPAECs dysfunction via activation of the AMPK pathway.

Mechanisms and Therapeutic Strategies for Myocardial Ischemia-Reperfusion Injury in Diabetic States

In patients with myocardial infarction, one of the complications that may occur after revascularization is myocardial ischemia-reperfusion injury (IRI), characterized by a depleted myocardial oxygen supply and absence of blood flow recovery after reperfusion, leading to expansion of myocardial infarction, poor healing of myocardial infarction and reversal of left ventricular remodeling, and an increase in the risk for major adverse cardiovascular events such as heart failure, arrhythmia, and cardiac cell death. As a risk factor for cardiovascular disease, diabetes mellitus increases myocardial susceptibility to myocardial IRI through various mechanisms, increases acute myocardial infarction and myocardial IRI incidence, decreases myocardial responsiveness to protective strategies and efficacy of myocardial IRI protective methods, and increases diabetes mellitus mortality through myocardial infarction. This Review summarizes the mechanisms, existing therapeutic strategies, and potential therapeutic targets of myocardial IRI in diabetic states, which has very compelling clinical significance.

Bioactive Peptides in Greek Goat Colostrum: Relevance to Human Metabolism

Colostrum is essential for the survival and development of newborn mammals. This primary source of nourishment during the first days of infant life is rich in functional components conductive to the enhancement of neonate immunity and growth. Compared with mature milk, a higher protein and peptide content is observed in colostrum, whilst it is low in fat and carbohydrates. The functional properties of colostrum are closely linked to the release of bioactive peptides during the gastrointestinal digestion of colostrum proteins. Our study aimed to comprehensively analyze the whey proteome of colostrum from indigenous Greek goats and to examine the influence of bioactive peptides released during digestion on human metabolism. Colostrum and mature milk samples from healthy ewes were subjected to nanoLC-MS/MS analysis, revealing differentially expressed proteins. These proteins were functionally characterized and subjected to in silico digestion. Using machine learning models, we classified the peptide functional groups, while molecular docking assessed the binding affinity of the proposed angiotensin-converting enzyme (ACE)- and dipeptidyl peptidase IV (DPPIV)-inhibitory peptides to their target molecules. A total of 898 proteins were identified in colostrum, 40 of which were overexpressed compared with mature milk. The enzymatic cleavage of upregulated proteins by key gastrointestinal tract proteases and the downstream analysis of peptide sequences identified 117 peptides predicted (with >80% confidence) to impact metabolism, primarily through modulation of the renin-angiotensin system, insulin secretion, and redox pathways. This work advances our understanding of dietary bioactive peptides and their relevance to human metabolism, highlighting the potential health benefits of colostrum consumption.

Esketamine alleviates ferroptosis-mediated acute lung injury by modulating the HIF-1α/HO-1 pathway

BACKGROUND

Alveolar epithelial cell (AEC) ferroptosis contributes to the progression of acute lung injury (ALI). Esketamine (ESK) is a new clinical sedative, anesthetic, and analgesic drug that has attracted substantial attention in mental health research because of its antidepressant effects. However, the effects of ESK on ferroptosis-mediated ALI remain unclear.

OBJECTIVE

This study aimed to explore the protective effect of ESK on AEC ferroptosis in ALI and its potential molecular mechanism in vivo and in vitro.

METHODS

The antiferroptotic and anti-inflammatory effects of ESK were assessed in a mouse model of lipopolysaccharide (LPS)-induced ALI. In vitro, the epithelial cell lines MLE-12 and A549 were used to examine the underlying mechanism by which ESK regulates inflammation and ferroptosis.

RESULTS

ESK protected mice against LPS-induced ALI, significantly attenuated pathological changes in the lungs and decreased inflammation and ferroptosis. In vitro, ESK inhibited LPS-induced inflammation and ferroptosis in MLE-12 and A549 cells. Moreover, ferroptosis mediated inflammation in LPS-induced ALI in vivo and in vitro, and ESK decreased the LPS-induced inflammatory response by suppressing ferroptosis. ESK promoted the HIF-1α/HO-1 pathway in LPS-treated AECs and in the lung tissues of mice with LPS-induced ALI. Moreover, pretreatment with ESK and the HIF-1α stabilizer dimethyloxaloylglycine (DMOG) substantially attenuated lung injury and prevented changes in ferroptosis-related biochemical indicators, including glutathione (GSH) depletion, malondialdehyde (MDA) production and glutathione peroxidase 4 (GPX4) downregulation, in untreated LPS-induced mice but not in LPS-induced mice treated with the HO-1 inhibitor zinc protoporphyrin (ZNPP). Similar effects were observed in vitro in HO-1 siRNA-transfected A549 cells after LPS incubation but not in control siRNA-transfected cells.

CONCLUSION

ESK can inhibit ferroptosis-mediated lipid peroxidation by increasing the expression of HIF-1α/HO-1 pathway, highlighting the potential of ESK to treat LPS-induced ALI.

Effect of hypoxia-induced mIL15 expression on expansion and memory progenitor stem-like TILs in vitro

Introduction

The adoptive cell transfer of tumor-infiltrating lymphocytes (TILs) has proven clinically beneficial in patients with non-small cell lung cancer refractory to checkpoint blockade immunotherapy, which has prompted interest in TIL-adoptive cell transfer. The transgenic expression of IL15 can promote the expansion, survival, and function of T cells ex vivo and in vivo and enhance their anti-tumor activity. The effect of expressing mIL15 regulated by hypoxia in the tumor microenvironment on the expansion, survival, and stem-like properties of TILs has not been explored.

Methods

Using TILs expanded from the tumor tissues of lung cancer patients, TILs with or without mIL15 expression (TIL-mIL15 or UN-TIL) were generated by lentiviral transduction. To reflect the advantages of mTIL15, the cells were divided into groups with IL2 (TIL-mIL15+IL2) or without IL2 (TIL-mIL15-IL2).

Results

Compared to UN-TIL cells, mIL15 expression had a similar capacity for promoting TIL proliferation and maintaining cell viability. Our experimental findings indicate that, compared to UN-TIL and TIL-mIL15+IL2 cells, the expression of mIL15 in TIL-mIL15-IL2 cells promoted the formation of stem-like TILs (CD8+CD39-CD69-) and led to significant decreases in the proportion and absolute number of terminally differentiated TILs (CD8+CD39+CD69+). RNA-Seq data revealed that in TIL-mIL15-IL2 cells, the expression of genes related to T cell differentiation and effector function, including PRDM1, ID2, EOMES, IFNG, GZMB, and TNF, were significantly decreased, whereas the expression of the memory stem-like T cell marker TCF7 was significantly increased. Furthermore, compared to UN-TIL and TIL-mIL15+IL2 cells, TIL-mIL15-IL2 cells showed significantly lower expression levels of inhibitory receptors LAG3, TIGIT, and TIM3, which was consistent with the RNA-Seq results.

Discussion

This study demonstrates the superior persistence of TIL-mIL15-IL2 cells, which may serve as a novel treatment strategy for lung cancer patients.

Metabolic reprogramming and therapeutic resistance in primary and metastatic breast cancer

Metabolic alterations, a hallmark of cancer, enable tumor cells to adapt to their environment by modulating glucose, lipid, and amino acid metabolism, which fuels rapid growth and contributes to treatment resistance. In primary breast cancer, metabolic shifts such as the Warburg effect and enhanced lipid synthesis are closely linked to chemotherapy failure. Similarly, metastatic lesions often display distinct metabolic profiles that not only sustain tumor growth but also confer resistance to targeted therapies and immunotherapies. The review emphasizes two major aspects: the mechanisms driving metabolic resistance in both primary and metastatic breast cancer, and how the unique metabolic environments in metastatic sites further complicate treatment. By targeting distinct metabolic vulnerabilities at both the primary and metastatic stages, new strategies could improve the efficacy of existing therapies and provide better outcomes for breast cancer patients.

Chromosome-level genome assembly of the kiang (Equus kiang) illuminates genomic basis for its high-altitude adaptation

The kiang (Equus kiang) can only be observed in the Qinghai-Tibet Plateau (QTP). The kiang displayed excellent athletic performance in the high-altitude environment, which attracted wide interest in the investigation of the potential adaptive mechanisms to the extreme environment. Here, we assembled a chromosome-level genome of the kiang based on Hi-C sequencing technology. A total of 324.14 Gb clean data were generated, and the chromosome-level genome with 26 chromosomes (25 + X) and scaffold N50 of 101.77 Mb was obtained for the kiang. The genomic synteny analysis revealed large-scale chromosomal rearrangement during the evolution process of Equus species. Phylogenetic and divergence analyses revealed that the kiang was the sister branch to the ass and diverged from a common ancestor at approximately 13.5 Mya. The expanded gene families were mainly related to the hypoxia response, metabolism, and immunity. The kiang suffered a significant loss of olfaction-related genes, which might indicate decreased olfactory sensibility. Positively selected genes (PSGs) detected in the kiang were mainly associated with hypoxia response. Especially, there were two species-specific missense amino acid mutations in the PSG STAT3 annotated in the hypoxia-inducible factor 1 signal pathway, which may play an important role in the high-altitude adaptation of the kiang. Moreover, structure variations in the kiang genome were also identified, which possibly contributed to the high-altitude adaptation of the kiang. Comparative analysis revealed a lot of species-specific insertions and deletions in the kiang genome, such as PIK3CB and AKT with 3258 and 189 bp insertions in the intron region, respectively, possibly affecting the expression and regulation of hypoxia-related downstream pathways. This study provided valuable genomic resources, and our findings help a better understanding of the underlying adaptive strategies to the high-altitude environment in the kiang.

Hypoxia and aging: molecular mechanisms, diseases, and therapeutic targets

Aging is a complex biological process characterized by the gradual decline of cellular functions, increased susceptibility to diseases, and impaired stress responses. Hypoxia, defined as reduced oxygen availability, is a critical factor that influences aging through molecular pathways involving hypoxia-inducible factors (HIFs), oxidative stress, inflammation, and epigenetic modifications. This review explores the interconnected roles of hypoxia in aging, highlighting how hypoxic conditions exacerbate cellular damage, promote senescence, and contribute to age-related pathologies, including cardiovascular diseases, neurodegenerative disorders, cancer, metabolic dysfunctions, and pulmonary conditions. By examining the molecular mechanisms linking hypoxia to aging, we identify key pathways that serve as potential therapeutic targets. Emerging interventions such as HIF modulators, antioxidants, senolytics, and lifestyle modifications hold promise in mitigating the adverse effects of hypoxia on aging tissues. However, challenges such as the heterogeneity of aging, lack of reliable biomarkers, and safety concerns regarding hypoxia-targeted therapies remain. This review emphasizes the need for personalized approaches and advanced technologies to develop effective antiaging interventions. By integrating current knowledge, this review provides a comprehensive framework that underscores the importance of targeting hypoxia-induced pathways to enhance healthy aging and reduce the burden of age-related diseases.

Carbon monoxide supplementation: evaluating its potential to enhance altitude training effects and cycling performance in elite athletes

Altitude training is a cornerstone for endurance athletes for improving blood variables and performance, with optimal effects observed at ∼2,300-2,500 meters above sea level (m.a.s.l.). However, elite cyclists face challenges such as limited access to such altitudes, inadequate training facilities, and high expenses. To address these issues, a novel method involving daily exposure to carbon monoxide (CO) has been proposed to amplify altitude training adaptations at suboptimal altitudes. Thirty-one male cyclists were assigned to three groups: Live-High Train-High with CO inhalation (LHTHCO), Live-High Train-High (LHTH), and Live-Low Train-Low (LLTL). The LHTHCO group underwent CO inhalation twice daily in the afternoon/evening to elevate carboxyhemoglobin concentration to ∼10%. Hematological variables, in vivo muscle oxidative capacity, and physiological indicators of cycling performance were assessed before and after a 3-week altitude training camp at 2,100 m.a.s.l. LHTHCO demonstrated a larger increase in hemoglobin mass (Hbmass) compared to both LHTH and LLTL. Although there were no statistical differences between LHTHCO and LHTH in submaximal and maximal performance measures, LHTHCO displayed greater improvements in 1-min maximal power output during incremental testing (Wmax), power output at lactate threshold, and maximal oxygen consumption (V̇o2max) compared to LLTL. LHTH demonstrated a larger improvement than LLTL in Wmax and V̇o2max, with no group differences in Hbmass or submaximal measures. Muscle oxidative capacity did not differ between groups. These findings suggest that combining moderate-altitude training with daily CO inhalation promotes hematological adaptations more effectively than moderate altitude alone and enhances cycling performance metrics in cyclists more than sea-level training.NEW & NOTEWORTHY Three weeks of training at moderate altitude with exposure to low doses of CO can significantly enhance hematological adaptations in elite cyclists compared to moderate-altitude training alone. Cycling performance determinants improved more with CO inhalation at moderate altitude compared to sea-level training, whereas there were no differences in submaximal and maximal performance measures compared to moderate-altitude training alone. This study highlights the potential of CO supplementation as an effective adjunct to altitude training regimens.

Utility of hypoxic modalities for musculoskeletal injury rehabilitation in athletes: A narrative review of mechanisms and contemporary perspectives

Recent evidence suggests that different hypoxic modalities might accelerate the rehabilitation process in injured athletes. In this review, the application of hypoxia during rehabilitation from musculoskeletal injury is explored in relation to two principles: (1) facilitating the healing of damaged tissue, and (2) mitigating detraining and inducing training adaptations with a reduced training load. Key literature that explores the underlying mechanisms for these themes is presented, and considerations for practice and future research directions are outlined. For principle (1), passive intermittent hypoxic exposures might accelerate tissue healing through angiogenic and osteogenic mechanisms. Experimental evidence is largely derived from rodent research, so further work is warranted to establish whether clinically meaningful effects can be observed in humans, before optimal protocols are determined (duration, frequency, and hypoxic severity). Regarding principle (2), a hypoxia-related increase in the cardiometabolic stimulus imposed by low-load exercise is appealing for load-compromised athletes. As rehabilitation progresses, a variety of hypoxic modalities can be implemented to enhance adaptation to energy-systems and resistance-based training, and more efficiently return the athlete to competition readiness. While hypoxic modalities seem promising for accelerating musculoskeletal injury rehabilitation in humans, and are already being widely used in practice, a significant gap remains regarding their evidence-based application.

Chronic hypoxia for the adaptation of extracellular vesicle phenotype

Variations in oxygen level affect the phenotype of cells and extracellular vesicles (EVs). Depending on the metabolic oxygen demand of cells, hypoxic cell culture can produce conditions more like those found in vivo, and with appropriate oxygen levels, mimic hypoxic tumours. However, most previous experiments studying both EVs and the effects of hypoxia on cells use periods of 72 h or less of hypoxia. We hypothesised that this was insufficient time for adaptation to hypoxic conditions both for EVs and cells which may skew the results of such studies. In this study, the effects of acute (72 h) and chronic hypoxia (> 2 weeks) on the phenotype of HepG2 and PC3 cells and their EVs were examined. Cells could be cultured normally under chronic hypoxic conditions and cryopreserved and recovered. The effects of hypoxia on EV phenotype are slow to establish and dependent on cell line. In PC3 cells, the greatest change in phenotype and increase in EV production occurred only with chronic hypoxic culture. In HepG2 cells, the number of EVs produced was insensitive to hypoxic culture and the greatest changes in protein expression were observed after acute hypoxic culture. Nonetheless, biphasic changes in EV phenotype were detected in both cell types in response to either acute or chronic hypoxia. These results indicate that for cells which do not induce consumptive oxygen depletion, prolonged hypoxic culture is required for complete adaptation.

Targeting Hypoxia-Inducible Factor-1α in Pancreatic Cancer: siRNA Delivery Using Hyaluronic Acid-Displaying Nanoparticles

Background/Objectives: Conventional anticancer therapies often lack specificity, targeting both cancerous and normal cells, which reduces efficacy and leads to undesired off-target effects. An additional challenge is the presence of hypoxic regions in tumors, where the Hypoxia Inducible Factor (HIF) transcriptional system drives the expression of pro-survival and drug resistance genes, leading to radio- and chemo-resistance. This study aims to explore the efficacy of targeted nanoparticle (NP)-based small interfering RNA (siRNA) therapies in downregulating these genes to enhance treatment outcomes in pancreatic cancer, a tumor type characterized by high CD44 expression and hypoxia. Methods: We utilized hyaluronic acid (HA)-displaying nanoparticles composed of positively charged chitosan (CS) complexed with siRNA to target and knock down HIF-1α in pancreatic cancer cells. Two NP formulations were prepared using either low molecular weight (LMW) or high molecular weight (HMW) CS. These formulations were evaluated for their internalization by cells and their effectiveness in gene silencing, both in vitro and in vivo. Results: The study found that the molecular weight (MW) of CS influenced the interaction between HA and CD44, as well as the release of siRNA upon internalization. The LMW CS formulation shows faster uptake kinetics, while HMW CS is more effective in gene knockdown across different cell lines in vitro. In vivo, both were able to significantly knockdown HIF-1α and some of its downstream genes. Conclusions: The results suggest that HMW and LMW CS-based NPs exhibit distinct characteristics, showing that both MWs have potential for targeted pancreatic cancer therapy by influencing different aspects of delivery and gene silencing, particularly in the hypoxic tumor microenvironment.

Photonanozyme-Kras-ribosome combination treatment of non-small cell lung cancer after COVID-19

With the outbreak of the coronavirus disease 2019 (COVID-19), reductions in T-cell function and exhaustion have been observed in patients post-infection of COVID-19. T cells are key mediators of anti-infection and antitumor, and their exhaustion increases the risk of compromised immune function and elevated susceptibility to cancer. Non-small cell lung cancer (NSCLC) is the most common subtype of lung cancer with high incidence and mortality. Although the survival rate after standard treatment such as surgical treatment and chemotherapy has improved, the therapeutic effect is still limited due to drug resistance, side effects, and recurrence. Recent advances in molecular biology and immunology enable the development of highly targeted therapy and immunotherapy for cancer, which has driven cancer therapies into individualized treatments and gradually entered clinicians' views for treating NSCLC. Currently, with the development of photosensitizer materials, phototherapy has been gradually applied to the treatment of NSCLC. This review provides an overview of recent advancements and limitations in different treatment strategies for NSCLC under the background of COVID-19. We discuss the latest advances in phototherapy as a promising treatment method for NSCLC. After critically examining the successes, challenges, and prospects associated with these treatment modalities, their profound prospects were portrayed.

Endothelial Cell-Specific Prolyl Hydroxylase-2 Deficiency Augments Angiotensin II-Induced Arterial Stiffness and Cardiac Pericyte Recruitment in Mice

BACKGROUND

Endothelial prolyl hydroxylase-2 (PHD2) is essential for pulmonary remodeling and hypertension. In the present study, we investigated the role of endothelial PHD2 in angiotensin II-mediated arterial stiffness, pericyte recruitment, and cardiac fibrosis.

METHODS AND RESULTS

Chondroitin sulfate proteoglycan 4 tracing reporter chondroitin sulfate proteoglycan 4- red fluorescent protein (DsRed) transgenic mice were crossed with PHD2flox/flox (PHD2f/f) mice and endothelial-specific knockout of PHD2 (PHD2ECKO) mice. Transgenic PHD2f/f (TgPHD2f/f) mice and TgPHD2ECKO mice were infused with angiotensin II for 4 weeks. Arterial thickness, stiffness, and histological and immunofluorescence of pericytes and fibrosis were measured. Infusion of TgPHD2f/f mice with angiotensin II resulted in a time-dependent increase in pulse-wave velocity. Angiotensin II-induced pulse-wave velocity was further elevated in the TgPHD2ECKO mice. TgPHD2ECKO also reduced coronary flow reserve compared with TgPHD2f/f mice infused with angiotensin II. Mechanistically, knockout of endothelial PHD2 promoted aortic arginase activity and angiotensin II-induced aortic thickness together with increased transforming growth factor-β1 and ICAM-1/VCAM-1 expression in coronary arteries. TgPHD2f/f mice infused with angiotensin II for 4 weeks exhibited a significant increase in cardiac fibrosis and hypertrophy, which was further developed in the TgPHD2ECKO mice. Chondroitin sulfate proteoglycan 4 pericyte was traced by DsRed+ staining and angiotensin II infusion displayed a significant increase of DsRed+ pericytes in the heart, as well as a deficiency of endothelial PHD2, which further promoted angiotensin II-induced pericyte increase. DsRed+ pericytes were costained with fibroblast-specific protein 1 and α-smooth muscle actin for measuring pericyte-myofibroblast cell transition. The knockout of endothelial PHD2 increased the amount of DsRed+/fibroblast-specific protein 1+ and DsRed+/α-smooth muscle actin+ cells induced by angiotensin II infusion.

CONCLUSIONS

Knockout of endothelial PHD2 enhanced angiotensin II-induced cardiac fibrosis by mechanisms involving increasing arterial stiffness and pericyte-myofibroblast cell transitions.

Better maintenance of enzymatic capacity and higher levels of substrate transporter proteins in skeletal muscle of aging female mice

This study investigated sex-specific differences in high-energy phosphate, glycolytic, and mitochondrial enzyme activities and also metabolite transporter protein levels in the skeletal muscles of adult (5 months old), middle-aged (12 months old), and advanced-aged (24 months old) mice. While gastrocnemius glycogen content increased with age regardless of sex, gastrocnemius triglyceride levels increased only in advanced-aged female mice. Aging decreased creatine kinase and adenylate kinase activities in the plantaris muscle of both sexes and in the soleus muscle of male mice but not in female mice. Irrespective of sex, phosphofructokinase and lactate dehydrogenase (LDH) activities decreased in the plantaris and soleus muscles. Additionally, hexokinase activity in the plantaris muscle and LDH activity in the soleus muscle decreased to a greater extent in aged male mice compared with those in aged female mice. Mitochondrial enzyme activities increased in the plantaris muscle of aged female mice but did not change in male mice. The protein content of the glucose transporter 4 in the aged plantaris muscle and fatty acid translocase/cluster of differentiation 36 increased in the aged plantaris and soleus muscles of both sexes, with a significantly higher content in female mice. These findings suggest that females possess a better ability to maintain metabolic enzyme activity and higher levels of metabolite transport proteins in skeletal muscle during aging, despite alterations in lipid metabolism. Our data provide a basis for studying muscle metabolism in the context of age-dependent metabolic perturbations and diseases that affect females and males differently.

Promoting Articular Cartilage Regeneration through Microenvironmental Regulation

In recent years, as the aging population continues to grow, osteoarthritis (OA) has emerged as a leading cause of disability, with its incidence rising annually. Current treatments of OA include exercise and medications in the early stages and total joint replacement in the late stages. These approaches only relieve pain and reduce inflammation; however, they have significant side effects and high costs. Therefore, there is an urgent need to identify effective treatment methods that can delay the pathological progression of this condition. The changes in the articular cartilage microenvironment, which are complex and diverse, can aggravate the pathological progression into a vicious cycle, inhibiting the repair and regeneration of articular cartilage. Understanding these intricate changes in the microenvironment is crucial for devising effective treatment modalities. By searching relevant research articles and clinical trials in PubMed according to the keywords of articular cartilage, microenvironment, OA, mechanical force, hypoxia, cytokine, and cell senescence. This study first summarizes the factors affecting articular cartilage regeneration, then proposes corresponding treatment strategies, and finally points out the future research direction. We find that regulating the opening of mechanosensitive ion channels, regulating the expression of HIF-1, delivering growth factors, and clearing senescent cells can promote the formation of articular cartilage regeneration microenvironment. This study provides a new idea for the treatment of OA in the future, which can promote the regeneration of articular cartilage through the regulation of the microenvironment so as to achieve the purpose of treating OA.

Effects of Bosentan on Hypoxia, Inflammation and Oxidative Stress in Experimental Blunt Thoracic Trauma Model

Background and Objectives: In this study, we aimed to investigate the effects of bosentan, an endothelin receptor antagonist, on endothelin-1 (ET-1), hypoxia-inducible factor-1 (HIF-1), nuclear factor-kappa B (NF-κB), and tumor necrosis factor (TNF)-α as inflammation markers, pro-oxidant antioxidant balance (PAB), and total antioxidant capacity (TAC) levels as oxidative stress parameters in lung tissues of rats in an experimental model of pulmonary contusion (PC) induced by blunt thoracic trauma. Materials and Methods: Thirty-seven male Sprague-Dawley rats were divided into five groups. C: The control group (n = 6) consisted of unprocessed and untreated rats. PC3 (n = 8) underwent 3 days of PC. PC-B3 (n = 8) received 100 mg/kg bosentan and was given orally once a day for 3 days. The PC7 group (n = 7) underwent 7 days of PC, and PC-B7 (n = 8) received 100 mg/kg bosentan and was given orally once a day for 7 days. Results: ET-1, NF-κB, TNF-α, HIF-1α, and PAB levels were higher, while TAC activity was lower in all groups compared with the control (p < 0.05). There was no significant difference in ET-1 and TNF-α levels between the PC-B3 and PC-B7 groups and the control group (p < 0.05), while NF-κB, HIF-1α, and PAB levels were still higher in both the PC-B3 and PC-B7 groups than in the control group. Bosentan decreased ET-1, NF-κB, TNF-α, HIF-1α, and PAB and increased TAC levels in comparison to the nontreated groups (p < 0.05). Conclusions: Bosentan decreased the severity of oxidative stress in the lungs and reduced the inflammatory reaction in rats with PC induced by blunt thoracic trauma. This suggests that bosentan may have protective effects on lung injury mechanisms by reducing hypoxia, inflammation, and oxidative stress. If supported by similar studies, bosentan can be used in both pulmonary and emergency clinics to reduce ischemic complications, inflammation, and oxidative stress in some diseases that may be accompanied by ischemia.

Vascular smooth muscle cells exhibit elevated hypoxia-inducible Factor-1α expression in human blood vessel organoids, influencing osteogenic performance

Considering the importance of alternative methodologies to animal experimentation, we propose an organoid-based biological model for in vitro blood vessel generation, achieved through co-culturing endothelial and vascular smooth muscle cells (VSMCs). Initially, the organoids underwent comprehensive characterization, revealing VSMCs (α-SMA + cells) at the periphery and endothelial cells (CD31+ cells) at the core. Additionally, ephrin B2 and ephrin B4, genes implicated in arterial and venous formation respectively, were used to validate the obtained organoid. Moreover, the data indicates exclusive HIF-1α expression in VSMCs, identified through various methodologies. Subsequently, we tested the hypothesis that the generated blood vessels have the capacity to modulate the osteogenic phenotype, demonstrating the ability of HIF-1α to promote osteogenic signals, primarily by influencing Runx2 expression. Overall, this study underscores that the methodology employed to create blood vessel organoids establishes an experimental framework capable of producing a 3D culture model of both venous and arterial endothelial tissues. This model effectively guides morphogenesis from mesenchymal stem cells through paracrine signaling, ultimately leading to an osteogenic acquisition phenotype, with the dynamic involvement of HIF-1α.

Mechanisms of Postischemic Stroke Angiogenesis: A Multifaceted Approach

Ischemic stroke constitutes a significant global health care challenge, and a comprehensive understanding of its recovery mechanisms is imperative for the development of innovative therapeutic strategies. Angiogenesis, a pivotal element of ischemic tissue repair, facilitates the restoration of blood flow to damaged regions, thereby promoting neuronal regeneration and functional recovery. Nevertheless, the mechanisms underlying postischemic stroke angiogenesis remain incompletely elucidated. This review meticulously examines the constituents of the neurovascular unit, ion channels, molecular mediators, and signaling pathways implicated in angiogenesis following stroke. Furthermore, it delves into prospective therapeutic strategies informed by these factors. Our objective is to provide detailed and exhaustive information on the intricate mechanisms governing postischemic stroke angiogenesis, thus providing a robust scientific foundation for the advancement of novel neurorepair therapies.

Transcriptional landscape of a hypoxia response identifies cell-specific pathways for adaptation

How the HIF-1 (Hypoxia-Inducible) transcription factor drives and coordinates distinct responses to low oxygen across diverse cell types is poorly understood. We present a multi-tissue single-cell gene-expression atlas of the hypoxia response of the nematode Caenorhabditis elegans . This atlas highlights how cell-type-specific HIF-1 responses overlap and diverge among and within neuronal, intestinal, and muscle tissues. Using the atlas to guide functional analyses of candidate muscle-specific HIF-1 effectors, we discovered that HIF-1 activation drives downregulation of the tspo-1 ( TSPO, Translocator Protein) gene in vulval muscle cells to modulate a hypoxia-driven change in locomotion caused by contraction of body-wall muscle cells. We further showed that in human cardiomyocytes HIF-1 activation decreases levels of TSPO and thereby alters intracellular cholesterol transport and the mitochondrial network. We suggest that TSPO-1 is an evolutionarily conserved mediator of HIF-1-dependent modulation of muscle and conclude that our gene-expression atlas can help reveal how HIF-1 drives cell-specific adaptations to hypoxia.

Effect of hypoxia on the post-hatching growth of the body of the fry and the caudal fin of the Atlantic Salmon (Salmo salar)

Introduction

Hypoxia is a recurring problem in the fish farming industry. Currently, it is known that the exposure of fish and fry to a hypoxic environment induces important changes in their metabolism, compromising not only their development but also their reproduction and mortality rates. Our hypothesis is that hypoxia constitutes one of the etiological factors causing deformation of the body and caudal fin in this species, as well as affecting its growth.

Methods

We analyzed two hundred forty Salmo salar salmon fry, differentially cultured at 100% saturation (normoxia condition) and 60% (hypoxia condition) for 2, 4, 6, and 8 days, including a group under continuous hypoxia. We performed diaphanization and Alcian blue staining, along with standard histological techniques. The polyclonal anti-HIF-1a antibody was used as a marker of hypoxia in Salmo salar, and hypoxia in these fish was associated with the immunopositivity of this antibody.

Results and discussion

The results indicate that there is an association between exposure to hypoxia and the deformation of the body and fin, as well as an agreement between hypoxia and the total length of the fry and fin. Several months after the event occurred, we were able to find and describe angiogenesis, blood vessel disorganization, and vasodilation histologically. Finally, hypoxic cells in the fry (HIF-1a) could be recognized and confirmed as hypoxia sensors. All of this indicates that hypoxia not only affects the fry during the development phase of the event, but that its results can be evident much later and affect the fry throughout their entire ontogeny.

Venous valve hypoxia as a possible mechanism of deep vein thrombosis: a scoping review

INTRODUCTION

The pathogenesis of deep vein thrombosis (DVT) has been explained by an interplay between a changed blood composition, vein wall alteration, and blood flow abnormalities. A comprehensive investigation of these components of DVT pathogenesis has substantially promoted our understanding of thrombogenesis in the venous system. Meanwhile, the process of DVT initiation remains obscure. This systematic review aims to collect, analyze, and synthesize the published evidence to propose hypoxia as a possible trigger of DVT.

EVIDENCE ACQUISITION

An exhaustive literature search was conducted across multiple electronic databased including PubMed, EMBASE, Scopus, and Web of Science to identify studies pertinent to the research hypothesis. The search was aimed at exploring the connection between hypoxia, reoxygenation, and the initiation of deep vein thrombosis (DVT). The following key words were used: "deep vein thrombosis," "venous thrombosis," "venous thromboembolism," "hypoxia," "reoxygenation," "venous valve," and "venous endothelium." Reviews, case reports, editorials, and letters were excluded.

EVIDENCE SYNTHESIS

Based on the systematic search outcome, 156 original papers relevant to the issue were selected for detailed review. These studies encompassed a range of experimental and observational clinical research, focusing on various aspects of DVT, including the anatomical, physiological, and cellular bases of the disease. A number of studies suggested limitations in the traditional understanding of Virchow's triad as an acceptable explanation for DVT initiation. Emerging evidence points to more complex interactions and additional factors that may be critical in the early stages of thrombogenesis. The role of venous valves has been recognized but remains underappreciated, with several studies indicating that these sites may act as primary loci for thrombus formation. A collection of studies describes the effects of hypoxia on venous endothelial cells at the cellular and molecular levels. Hypoxia influences several pathways that regulate endothelial cell permeability, inflammatory response, and procoagulation activity, underpinning the endothelial dysfunction noted in DVT.

CONCLUSIONS

Hypoxia of the venous valve may serve as an independent hypothesis to outline the DVT triggering process. Further research projects in this field may discover new molecular pathways responsible for the disease and suggest new therapeutic targets.

The Role of Hyperbaric Oxygen Therapy in Neuroregeneration and Neuroprotection: A Review

Neurogenesis is a high energy-demanding process, which is why blood vessels are an active part of the neurogenic niche since they allow the much-needed oxygenation of progenitor cells. In this regard, although neglected for a long time, the "oxygen niche" should be considered an important intervenient in adult neurogenesis. One possible hypothesis for the failure of numerous neuroprotective trials is that they relied on compounds that target a highly specific neuroprotective pathway. This approach may be too limited, given the complexity of the processes that lead to cell death. Therefore, research should adopt a more multifactorial approach. Among the limited range of agents with multimodal neuromodulatory capabilities, hyperbaric oxygen therapy has demonstrated effectiveness in reducing secondary brain damage in various brain injury models. This therapy functions not only as a neuroprotective mechanism but also as a powerful neuroregenerative mechanism.

TNIK depletion induces inflammation and apoptosis in injured renal proximal tubule epithelial cells

In the aftermath of acute kidney injury (AKI), surviving proximal tubule epithelia repopulate injured tubules to promote repair. However, a portion of cells fail to repair [termed failed-repair proximal tubule cells (FR-PTCs)] and exert ongoing proinflammatory and profibrotic effects. To better understand the molecular drivers of the FR-PTC state, we reanalyzed a mouse ischemia-reperfusion injury single-nucleus RNA-sequencing (snRNA-seq) atlas to identify Traf2 and Nck interacting kinase (Tnik) to be exclusively expressed in FR-PTCs but not in healthy or acutely injured proximal tubules after AKI (2 and 6 wk) in mice. We confirmed expression of Tnik protein in injured mouse and human tissues by immunofluorescence. Then, to determine the functional role of Tnik in FR-PTCs, we depleted TNIK with siRNA in two human renal proximal tubule epithelial cell lines (primary and immortalized hRPTECs) and analyzed each by bulk RNA-sequencing. Pathway analysis revealed significant upregulation of inflammatory signaling pathways, whereas pathways associated with differentiated proximal tubules such as organic acid transport were significantly downregulated. TNIK gene knockdown drove reduced cell viability and increased apoptosis, including differentially expressed poly(ADP-ribose) polymerase (PARP) family members, cleaved PARP-1 fragments, and increased annexin V binding to phosphatidylserine. Together, these results indicate that Tnik upregulation in FR-PTCs acts in a compensatory fashion to suppress inflammation and promote proximal tubule epithelial cell survival after injury. Modulating TNIK activity may represent a prorepair therapeutic strategy after AKI.NEW & NOTEWORTHY The molecular drivers of successful and failed repair in the proximal tubule after acute kidney injury (AKI) are incompletely understood. We identified Traf2 and Nck interacting kinase (Tnik) to be exclusively expressed in failed-repair proximal tubule cells after AKI. We tested the effect of siTNIK depletion in two proximal tubule cell lines followed by bulk RNA-sequencing analysis. Our results indicate that TNIK acts to suppress inflammatory signaling and apoptosis in injured renal proximal tubule epithelial cells to promote cell survival.

The NFATc1/P2X7 receptor relationship in human intervertebral disc cells

A comprehensive understanding of the molecules that play key roles in the physiological and pathological homeostasis of the human intervertebral disc (IVD) remains challenging, as does the development of new therapeutic treatments. We recently found a positive correlation between IVD degeneration (IDD) and P2X7 receptor (P2X7R) expression increases both in the cytoplasm and in the nucleus. Using immunocytochemistry, reverse transcription PCR (RT-PCR), overexpression, and chromatin immunoprecipitation, we found that NFATc1 and hypoxia-inducible factor-1α (HIF-1α) are critical regulators of P2X7R. Both transcription factors are recruited at the promoter of the P2RX7 gene and involved in its positive and negative regulation, respectively. Furthermore, using the proximity ligation assay, we revealed that P2X7R and NFATc1 form a molecular complex and that P2X7R is closely associated with lamin A/C, a major component of the nuclear lamina. Collectively, our study identifies, for the first time, P2X7R and NFATc1 as markers of IVD degeneration and demonstrates that both NFATc1 and lamin A/C are interaction partners of P2X7R.

Molecular Mechanisms of Neuroprotection after the Intermittent Exposures of Hypercapnic Hypoxia

The review introduces the stages of formation and experimental confirmation of the hypothesis regarding the mutual potentiation of neuroprotective effects of hypoxia and hypercapnia during their combined influence (hypercapnic hypoxia). The main focus is on the mechanisms and signaling pathways involved in the formation of ischemic tolerance in the brain during intermittent hypercapnic hypoxia. Importantly, the combined effect of hypoxia and hypercapnia exerts a more pronounced neuroprotective effect compared to their separate application. Some signaling systems are associated with the predominance of the hypoxic stimulus (HIF-1α, A1 receptors), while others (NF-κB, antioxidant activity, inhibition of apoptosis, maintenance of selective blood-brain barrier permeability) are mainly modulated by hypercapnia. Most of the molecular and cellular mechanisms involved in the formation of brain tolerance to ischemia are due to the contribution of both excess carbon dioxide and oxygen deficiency (ATP-dependent potassium channels, chaperones, endoplasmic reticulum stress, mitochondrial metabolism reprogramming). Overall, experimental studies indicate the dominance of hypercapnia in the neuroprotective effect of its combined action with hypoxia. Recent clinical studies have demonstrated the effectiveness of hypercapnic-hypoxic training in the treatment of childhood cerebral palsy and diabetic polyneuropathy in children. Combining hypercapnic hypoxia with pharmacological modulators of neuro/cardio/cytoprotection signaling pathways is likely to be promising for translating experimental research into clinical medicine.

Development of a hypoxia-activated red-emission fluorescent probe for in vivo tumor microenvironment imaging and anti-tumor therapy

Hypoxia, a significant feature of the tumor microenvironment, is closely associated with tumor growth, metastasis, and drug resistance. In the field of tumor microenvironment analysis, accurately imaging and quantifying hypoxia - a critical factor associated with tumor progression, metastasis, and resistance to therapy - remains a significant challenge. Herein, a hypoxia-activated red-emission fluorescent probe, ODP, for in vivo imaging of hypoxia in the tumor microenvironment is presented. Among various imaging methods, optical imaging is particularly convenient due to its rapid response and high sensitivity. The ODP probe specifically targets nitroreductase (AzoR), an enzyme highly expressed in hypoxic cells, playing a vital role by catalyzing the cleavage of azo bonds. The optical properties of ODP exhibited excellent performance in terms of fluorescence enhancement, fluorescence lifetime (0.81 ns), and detection limit (0.86 µM) in response to SDT. Cell imaging experiments showed that ODP could effectively detect and image intracellular hypoxia and the imaging capability of ODP was studied under various conditions including cell migration, antioxidant treatment, and different incubation times. Through comprehensive in vitro and in vivo experiments, including cellular imaging and mouse tumor models, this work demonstrates the efficacy of ODP in accurately detecting and imaging hypoxia. Moreover, ODP's potential in inducing apoptosis in cancer cells offers a promising avenue for integrating diagnostic and therapeutic strategies in cancer treatment. This innovative approach not only contributes to the understanding and assessment of tumor hypoxia but also opens new possibilities for targeted cancer therapy.

The dance of macrophage death: the interplay between the inevitable and the microenvironment

Macrophages are highly plastic cells ubiquitous in various tissues, where they perform diverse functions. They participate in the response to pathogen invasion and inflammation resolution following the immune response, as well as the maintenance of homeostasis and proper tissue functions. Macrophages are generally considered long-lived cells with relatively strong resistance to numerous cytotoxic factors. On the other hand, their death seems to be one of the principal mechanisms by which macrophages perform their physiological functions or can contribute to the development of certain diseases. In this review, we scrutinize three distinct pro-inflammatory programmed cell death pathways - pyroptosis, necroptosis, and ferroptosis - occurring in macrophages under specific circumstances, and explain how these cells appear to undergo dynamic yet not always final changes before ultimately dying. We achieve that by examining the interconnectivity of these cell death types, which in macrophages seem to create a coordinated and flexible system responding to the microenvironment. Finally, we discuss the complexity and consequences of pyroptotic, necroptotic, and ferroptotic pathway induction in macrophages under two pathological conditions - atherosclerosis and cancer. We summarize damage-associated molecular patterns (DAMPs) along with other microenvironmental factors, macrophage polarization states, associated mechanisms as well as general outcomes, as such a comprehensive look at these correlations may point out the proper methodologies and potential therapeutic approaches.

Circadian Influences on Myocardial Ischemia-Reperfusion Injury and Heart Failure

The impact of circadian rhythms on cardiovascular function and disease development is well established, with numerous studies in genetically modified animals emphasizing the circadian molecular clock's significance in the pathogenesis and pathophysiology of myocardial ischemia and heart failure progression. However, translational preclinical studies targeting the heart's circadian biology are just now emerging and are leading to the development of a novel field of medicine termed circadian medicine. In this review, we explore circadian molecular mechanisms and novel therapies, including (1) intense light, (2) small molecules modulating the circadian mechanism, and (3) chronotherapies such as cardiovascular drugs and meal timings. These promise significant clinical translation in circadian medicine for cardiovascular disease. (4) Additionally, we address the differential functioning of the circadian mechanism in males versus females, emphasizing the consideration of biological sex, gender, and aging in circadian therapies for cardiovascular disease.

IFI16 Is Indispensable for Promoting HIF-1α-Mediated APOL1 Expression in Human Podocytes under Hypoxic Conditions

Genetic variants in the protein-coding regions of APOL1 are associated with an increased risk and progression of chronic kidney disease (CKD) in African Americans. Hypoxia exacerbates CKD progression by stabilizing HIF-1α, which induces APOL1 transcription in kidney podocytes. However, the contribution of additional mediators to regulating APOL1 expression under hypoxia in podocytes is unknown. Here, we report that a transient accumulation of HIF-1α in hypoxia is sufficient to upregulate APOL1 expression in podocytes through a cGAS/STING/IRF3-independent pathway. Notably, IFI16 ablation impedes hypoxia-driven APOL1 expression despite the nuclear accumulation of HIF-1α. Co-immunoprecipitation assays indicate no direct interaction between IFI16 and HIF-1α. Our studies identify hypoxia response elements (HREs) in the APOL1 gene enhancer/promoter region, showing increased HIF-1α binding to HREs located in the APOL1 gene enhancer. Luciferase reporter assays confirm the role of these HREs in transcriptional activation. Chromatin immunoprecipitation (ChIP)-qPCR assays demonstrate that IFI16 is not recruited to HREs, and IFI16 deletion reduces HIF-1α binding to APOL1 HREs. RT-qPCR analysis indicates that IFI16 selectively affects APOL1 expression, with a negligible impact on other hypoxia-responsive genes in podocytes. These findings highlight the unique contribution of IFI16 to hypoxia-driven APOL1 gene expression and suggest alternative IFI16-dependent mechanisms regulating APOL1 gene expression under hypoxic conditions.

Out of the core: the impact of focal ischemia in regions beyond the penumbra

The changes in the necrotic core and the penumbra following induction of focal ischemia have been the focus of attention for some time. However, evidence shows, that ischemic injury is not confined to the primarily affected structures and may influence the remote areas as well. Yet many studies fail to probe into the structures beyond the penumbra, and possibly do not even find any significant results due to their short-term design, as secondary damage occurs later. This slower reaction can be perceived as a therapeutic opportunity, in contrast to the ischemic core defined as irreversibly damaged tissue, where the window for salvation is comparatively short. The pathologies in remote structures occur relatively frequently and are clearly linked to the post-stroke neurological outcome. In order to develop efficient therapies, a deeper understanding of what exactly happens in the exo-focal regions is necessary. The mechanisms of glia contribution to the ischemic damage in core/penumbra are relatively well described and include impaired ion homeostasis, excessive cell swelling, glutamate excitotoxic mechanism, release of pro-inflammatory cytokines and phagocytosis or damage propagation via astrocytic syncytia. However, little is known about glia involvement in post-ischemic processes in remote areas. In this literature review, we discuss the definitions of the terms "ischemic core", "penumbra" and "remote areas." Furthermore, we present evidence showing the array of structural and functional changes in the more remote regions from the primary site of focal ischemia, with a special focus on glia and the extracellular matrix. The collected information is compared with the processes commonly occurring in the ischemic core or in the penumbra. Moreover, the possible causes of this phenomenon and the approaches for investigation are described, and finally, we evaluate the efficacy of therapies, which have been studied for their anti-ischemic effect in remote areas in recent years.

Aglycemia induces apoptosis under hypoxic conditions in A549 cells

Many of the cancer cells produce energy with accelerated glycolysis and perform lactic acid production even under normoxic conditions called the "Warburg effect". Metabolism can directly or indirectly regulate the apoptotic mechanism so that cancer cells take advantage of reprogrammed metabolism to avoid apoptosis. The aim of this study is to examine the mechanism of apoptosis by incubating human lung carcinoma cells (A549) under different metabolic conditions in hypoxia or normoxia environments. A549 cells were incubated in the normoxic or hypoxic condition that contained 5 mM glucose (Glc 5), 25 mM glucose (Glc 25), or 10 mM galactose (OXPHOS/aglycemic), and the mechanism of apoptosis was investigated. In the hypoxia condition, the rate of early apoptosis in aglycemic OXPHOS cells was increased (15.5% ±7.1). In addition, the activity of caspase-3 (6.1% ± 0.9), caspase-9 (30.4% ± 0.9), and cytochrome c expression level increased; however, the mitochondrial membrane potential (51.9% ± 0.4) was found to be decreased. Changing the amount of oxygen in glycolytic cells had no effect on apoptosis. However, it has been determined that apoptosis is stimulated under hypoxia conditions in aglycemic cells in which galactose is used instead of glucose. Considering that the majority of cancer cells are hypoxic, these data are important in determining targets in therapeutic intervention.

Transcriptomic analysis of the hypoxia-inducible factor 1α impact on the gene expression profile of chicken fibroblasts under hypoxia

Hypoxia-inducible factor 1 (HIF-1) is a transcriptional regulator that mediates cellular adaptive responses to hypoxia. Hypoxia-inducible factor 1α (HIF-1α) is involved in the development of ascites syndrome (AS) in broiler chickens. Therefore, studying the effect of HIF-1α on the cellular transcriptome under hypoxic conditions will help to better understand the mechanism of HIF-1α in the development of AS in broilers. In this study, we analyzed the gene expression profile of the chicken fibroblast cell line (DF-1) under hypoxic conditions by RNA-seq. Additionally, we constructed the HIF-1α knockdown DF-1 cell line by using the RNAi method and analyzed the gene expression profile under hypoxic conditions. The results showed that exposure to hypoxia for 48 h had a significant impact on the expression of genes in the DF-1 cell line, which related to cell proliferation, stress response, and apoptosis. In addition, after HIF-1α knockdown more differential expression genes appeared than in wild-type cells, and the expression of most hypoxia-related genes was either down-regulated or remained unchanged. Pathway analysis results showed that differentially expressed genes were mainly enriched in pathways related to cell proliferation, apoptosis, and oxidative phosphorylation. Our study obtained transcriptomic data from chicken fibroblasts at different hypoxic times and identified the potential regulatory network associated with HIF-1α. This data provides valuable support for understanding the transcriptional regulatory mechanism of HIF-1α in the development of AS in broilers.

Atorvastatin rescues pulmonary artery hypertension by inhibiting the AKT/ERK-dependent PDGF-BB/HIF-1α axis

BACKGROUND

The aim of this study is to explore the role of atorvastatin in rescuing pulmonary artery hypertension (PAH) by inhibiting the AKT/ERK-dependent PDGF-BB/HIF-1α axis.

METHODS

PAH model in rats was established by MCT induction, followed by Atorvastatin intervention. Pulmonary hemodynamic measurement and pulmonary morphological evaluation in rats were conducted. Human pulmonary artery smooth muscle cells (hPASMCs) were subjected to hypoxic exposure or PDGF-BB treatment, followed by atorvastatin induction. Relative levels of HIF-1α, p-ERK and p-Akt were detected. Viability and apoptosis were respectively determined by cell counting kit-8 (CCK-8) assay and flow cytometry.

RESULTS

Atorvastatin protected PAH-induced increases in RVSP and Fulton's index in rats. Meanwhile, it inhibited vascular remodeling following PAH by downregulating HIF-1α and PDGF-BB. Hypoxia or PDGF-BB treatment in hPASMCs resulted in upregulation of p-ERK and p-Akt, and viability increase, which were partially abolished by Atorvastatin intervention. In addition, atorvastatin triggered apoptosis in hypoxia or PDGF-BB-induced hPASMCs.

CONCLUSIONS

Atorvastatin inhibits the activation of HIF-1α and proliferative ability, and triggers apoptosis in hPASMCs exposed to hypoxia or PDGF-BB treatment through inactivating the AKT/ERK pathway.

Evolution of a novel regulatory mechanism of hypoxia inducible factor in hypoxia-tolerant electric fishes

Hypoxia is a significant source of metabolic stress that activates many cellular pathways involved in cellular differentiation, proliferation, and cell death. Hypoxia is also a major component in many human diseases and a known driver of many cancers. Despite the challenges posed by hypoxia, there are animals that display impressive capacity to withstand lethal levels of hypoxia for prolonged periods of time and thus offer a gateway to a more comprehensive understanding of the hypoxic response in vertebrates. The weakly electric fish genus Brachyhypopomus inhabits some of the most challenging aquatic ecosystems in the world, with some species experiencing seasonal anoxia, thus providing a unique system to study the cellular and molecular mechanisms of hypoxia tolerance. In this study, we use closely related species of Brachyhypopomus that display a range of hypoxia tolerances to probe for the underlying molecular mechanisms via hypoxia inducible factors (HIFs)-transcription factors known to coordinate the cellular response to hypoxia in vertebrates. We find that HIF1⍺ from hypoxia tolerant Brachyhypopomus species displays higher transactivation in response to hypoxia than that of intolerant species, when overexpressed in live cells. Moreover, we identified two SUMO-interacting motifs near the oxygen-dependent degradation and transactivation domains of the HIF1⍺ protein that appear to boost transactivation of HIF1, regardless of the genetic background. Together with computational analyses of selection, this shows that evolution of HIF1⍺ are likely to underlie adaptations to hypoxia tolerance in Brachyhypopomus electric fishes, with changes in two SUMO-interacting motifs facilitating the mechanism of this tolerance.

Factors Influencing Venous Remodeling in the Development of Varicose Veins of the Lower Limbs

One of the early symptoms of chronic venous disease (CVD) is varicose veins (VV) of the lower limbs. There are many etiological environmental factors influencing the development of chronic venous insufficiency (CVI), although genetic factors and family history of the disease play a key role. All these factors induce changes in the hemodynamic in the venous system of the lower limbs leading to blood stasis, hypoxia, inflammation, oxidative stress, proteolytic activity of matrix metalloproteinases (MMPs), changes in microcirculation and, consequently, the remodeling of the venous wall. The aim of this review is to present current knowledge on CVD, including the pathophysiology and mechanisms related to vein wall remodeling. Particular emphasis has been placed on describing the role of inflammation and oxidative stress and the involvement of extracellular hemoglobin as pathogenetic factors of VV. Additionally, active substances used in the treatment of VV were discussed.