Expression of hypoxia-inducible factor 1: mechanisms and consequences

Vascular endothelial growth factors in airway allergic diseases: pathophysiological functions and therapeutic prospects

INTRODUCTION

Vascular endothelial growth factors (VEGFs) play a crucial role in regulating physiological angiogenesis and homeostasis during growth and development. Recent advancements in our knowledge of VEGFs have revealed their complex role in coordinating vascular homeostasis and pathological role in various airway allergic reactions and structural remodeling, especially in allergic asthma and allergic rhinitis (AR), which has become more apparent.

AREAS COVERED

After an extensive search of PubMed and Web of Science databases, our review covered articles published from 1989 to 2024. The purpose of this review was to review previous studies on VEGFs involved in inflammatory progression and tissue remodeling in airway allergic diseases, to summarize the relevant pathways. This article further reviews that VEGFs and their receptors can also be potential targets for treating airway allergic diseases.

EXPERT OPINION

The prevalence of airway allergic diseases is increasing, which has caused a serious economic burden. VEGFs and their receptors have been recognized as potential targets for therapeutic interventions, which have been effectively applied in the treatment of tumors and other diseases. Fully elucidating the involvement of VEGFs in the disease process will help us understand their mechanisms of action and develop targeted therapies for allergic diseases.

Recent Update of Natural Compounds as HIF-1α Inhibitors in Colorectal Carcinoma

Hypoxia-inducible factor (HIF)-1 is a transcription factor that regulates the expression of target genes associated with oxygen homeostasis under hypoxic conditions, thereby contributing to tumor development and progression. Accumulating evidence has demonstrated that HIF-1α mediates different biological processes, including tumor angiogenesis, metastasis, metabolism, and immune evasion. Thus, overexpression of HIF-1α is strongly associated with poor prognosis in cancer patients. Natural compounds are important sources of anticancer drugs and studies have emphasized the decisive role of these mediators in modulating HIF-1α. Therefore, the pharmacological targeting of HIF-1α has emerged as a novel cancer therapeutic approach in recent years. The novelty of this review is that it summarizes natural products targeting HIF-1α in colorectal cancer that have not been presented earlier. We studied research publications related to the HIF-1α domain in cancer from 2010 to 2024. However, our main focus was to identify a better targeted approach for colorectal carcinoma management. Our review described HIF-1α role in tumor progression, summarizes the natural compounds employed as HIF-1α inhibitors, and discusses their potential in the development of natural compounds as HIF-1α inhibitors for colorectal cancer treatment.

Cancer-intrinsic Cxcl5 orchestrates a global metabolic reprogramming for resistance to oxidative cell death in 3D

Pancreatic ductal adenocarcinoma is characterized by a three-dimensional (3D) tumor microenvironment devoid of oxygen and nutrients but enriched in extracellular matrix, which acts as a physical and chemical barrier. In 3D, cancer cells reprogram their metabolic pathways in ways that help them survive hostile conditions. However, little is known about the metabolic phenotypes of cancer cells in 3D and the intrinsic cues that modulate them. We found that Cxcl5 deletion restricted pancreatic tumor growth in a 3D spheroid-in-Matrigel culture system without affecting cancer cell growth in 2D culture. Cxcl5 deletion impaired 3D-specific global metabolic reprogramming, resistance to hypoxia-induced cell death, and upregulation of Hif1α and Myc. Overexpression of Hif1α and Myc, however, effectively restored 3D culture-induced metabolic reconfiguration, growth, redox homeostasis, and mitochondrial function in Cxcl5-/- cells, reducing ferroptosis. We also found that pancreatic cancer patients with higher expression of hypoxia and metabolism-related genes whose expression is well-correlated with CXCL5 generally have poorer prognosis. Together, our findings identify an unanticipated role of Cxcl5 in orchestrating the cancer metabolic reprogramming in 3D culture that is required for energy and biomass maintenance and that restricts oxidative cell death. Thus, our results provide a rationale for targeting CXCL5 as a promising therapeutic strategy.

Role of glycogen in cardiac metabolic stress

Metabolic stress in the myocardium arises from a diverse array of acute and chronic pathophysiological contexts. Glycogen mishandling is a key feature of metabolic stress, while maladaptation in energy-stress situations confers functional deficits. Cardiac glycogen serves as a pivotal reserve for myocardial energy, which is classically described as an energy source and contributes to glucose homeostasis during hypoxia or ischemia. Despite extensive research activity, how glycogen metabolism affects cardiovascular disease remains unclear. In this review, we focus on its regulation across myocardial energy metabolism in response to stress, and its role in metabolism, immunity, and autophagy. We further summarize the cardiovascular-related drugs regulating glycogen metabolism. In this way, we provide current knowledge for the understanding of glycogen metabolism in the myocardium.

Synergistic effect of Hypoxic Conditioning and Cell-Tethering Colloidal Gels enhanced Productivity of MSC Paracrine Factors and Accelerated Vessel Regeneration

Microporous hydrogels have been widely used for delivering therapeutic cells. However, several critical issues, such as the lack of control over the harsh environment they are subjected to under pathological conditions and rapid egression of cells from the hydrogels, have produced limited therapeutic outcomes. To address these critical challenges, cell-tethering and hypoxic conditioning colloidal hydrogels containing mesenchymal stem cells (MSCs) are introduced to increase the productivity of paracrine factors locally and in a long-term manner. Cell-tethering colloidal hydrogels that are composed of tyramine-conjugated gelatin prevent cells from egressing through on-cell oxidative phenolic crosslinks while providing mechanical stimulation and interconnected microporous networks to allow for host-implant interactions. Oxygenating microparticles encapsulated in tyramine-conjugated colloidal microgels continuously generated oxygen for 2 weeks with rapid diffusion, resulting in maintaining a mild hypoxic condition while MSCs consumed oxygen under severe hypoxia. Synergistically, local retention of MSCs within the mild hypoxic-conditioned and mechanically robust colloidal hydrogels significantly increased the secretion of various angiogenic cytokines and chemokines. The oxygenating colloidal hydrogels induced anti-inflammatory responses, reduced cellular apoptosis, and promoted numerous large blood vessels in vivo. Finally, mice injected with the MSC-tethered oxygenating colloidal hydrogels significantly improved blood flow restoration and muscle regeneration in a hindlimb ischemia (HLI) model.

The Physiological Functions and Therapeutic Potential of Hypoxia-Inducible Factor-1α in Vascular Calcification

HIF-1α plays a crucial regulatory role in vascular calcification (VC), primarily influencing the osteogenic differentiation of VSMCs through oxygen-sensing mechanisms. Under hypoxic conditions, the stability of HIF-1α increases, avoiding PHD and VHL protein-mediated degradation, which promotes its accumulation in cells and then activates gene expressions related to calcification. Additionally, HIF-1α modulates the metabolic state of VSMCs by regulating the pathways that govern the switch between glycolysis and oxidative phosphorylation, thereby further advancing the calcification process. The interaction between HIF-1α and other signaling pathways, such as nuclear factor-κB, Notch, and Wnt/β-catenin, creates a complex regulatory network that serves as a critical driving force in VC. Therefore, a deeper understanding of the role and regulatory mechanism of the HIF-1α signaling during the development and progression of VC is of great significance, as it is not only a key molecular marker for understanding the pathological mechanisms of VC but also represents a promising target for future anti-calcification therapies.

Cardio-oncological dialogue: Understanding the mechanistic correlation between heart failure and cancer

AIMS

This review aims to elucidate the bidirectional relationship between heart failure and cancer by identifying their common and reciprocal risk factors. It seeks to provide a comprehensive understanding of the mechanistic interactions between these two conditions, supported by evidence from preclinical and clinical investigations.

MATERIALS AND METHODS

A thorough review of peer-reviewed articles was conducted to identify all possible interactions between cancer and heart failure. Multiple search engines were utilized with queries incorporating terms such as cardio-oncology, heart failure, cancer, risk factors, and mechanistic interactions. Selected studies were analysed to identify shared risk factors and to explore the mechanistic junctions that link the two diseases.

KEY FINDINGS

The review identified several common risk factors, including, inflammation, smoking, obesity, clonal haematopoiesis of indeterminate potential, and reduced exercise potential. The pathophysiological mechanisms linking heart failure with cancer include metabolic reprogramming in cancer, cancer-induced thrombosis, cardiac metastasis, paraneoplastic syndrome, cancer-associated cachexia, and anorexia. Additionally, it was found that cancer therapies, such as anthracyclines and radiation, can induce cardiotoxicity, leading to heart failure. The pathophysiological mechanisms that contribute to cancer in heart failure patients were identified as neurohormonal activation, state of hypoxia, secretion of Cardiokines, heart failure medication, innate immune reprograming & cardiac remodelling and coronary atherosclerotic disease.

SIGNIFICANCE

By highlighting the interconnected nature of heart failure and cancer, this review promotes a cardio-oncologic discourse, encouraging cardiologists and oncologists to consider these diseases as interrelated rather than separate entities. This perspective can lead to the development of novel therapeutic strategies and improve patient management by addressing the dual disease burden. Future research should focus on exploring the translational potential of existing drugs and developing new interventions to target the shared characteristics of heart failure and cancer.

EGCG enhances antitumor effect of apatinib in nonsmall cell lung cancer by targeting VEGF signaling to inhibit glycolysis

Nonsmall cell lung cancer (NSCLC), one of the most aggressive malignancies globally, is characterized by poor prognosis and limited life expectancy. Epigallocatechin-3-gallate (EGCG), a natural polyphenol found in green tea, has emerged as a promising anticancer agent due to its potent antitumor properties. However, the role and the underlying mechanisms of EGCG in NSCLC remain poorly understood. Hence, this research aimed to explore the effect of EGCG on the antitumor effect of apatinib in NSCLC through vascular endothelial growth factor (VEGF)-regulated glycolysis. Cell Counting Kit-8 (CCK-8), 5-ethynyl-2'-deoxyuridine staining, wound healing, transwell, terminal deoxynucleotidyl transferase dUTP nick-end labeling, and flow cytometry assays were carried out to evaluate the proliferation, migration, invasion, and apoptosis of H1299 cells, respectively. Furthermore, western blot analysis was used to detect the expressions of VEGF, p-vascular endothelial growth factor receptor-2, hypoxia-inducible factor 1α, neuropilin-1, phosphorylated-phosphatidylinositol 3-kinase, and phosphorylated-AKT. The transfection efficiency of H1299 cells with VEGF overexpression plasmid was also assessed by western blot analysis. Glycolysis was analyzed by estimating extracellular acidification rate, lactate concentration, glucose uptake, and the expressions of lactate dehydrogenase A, pyruvate kinase M2, and hexokinase 2. The results demonstrated that VEGF activated glycolysis in NSCLC cells. EGCG alone and apatinib alone or in combination inhibited cell viability, proliferation, invasion, migration, and glycolysis whereas promoted apoptosis in NSCLC cells. EGCG regulated glycolysis levels in NSCLC through VEGF overexpression, and enhanced the antitumor effect of apatinib in NSCLC through VEGF-regulated glycolysis. Taken together, EGCG strengthened the protective effects of apatinib in NSCLC through glycolysis mediated by VEGF.

Targeting hypoxia-inducible factor 1 alpha augments synergistic effects of chemo/immunotherapy via modulating tumor microenvironment in a breast cancer mouse model

Introduction

The immunosuppressive context of the tumor microenvironment (TME) is a significant hurdle in breast cancer (BC) treatment. Combinational therapies targeting cancer core signaling pathways involved in the induction of TME immunosuppressive milieu have emerged as a potent strategy to overcome immunosuppression in TME and enhance patient therapeutic outcomes. This study presents compelling evidence that targeting hypoxia-inducible-factor-1 alpha (Hif-1α) alongside chemotherapy and immune-inducing factors leads to substantial anticancer effects through modulation of TME.

Methods

Chitosan (Cs)/Hif-1alpha siRNA nano-complex was synthesized by siRNA adsorption methods. Nanoparticles were fully characterized using dynamic light scattering and scanning electron microscope. Cs/Hif-1α siRNA cytotoxicity was measured by MTT assay. The anticancer effects of the combinational therapy were assessed in BALB/c bearing 4T1 tumors. qPCR and western blotting were applied to assess the expression of some key genes and proteins involved in the induction of immunosuppression in TME.

Results

Hif-1α siRNA was successfully loaded in chitosan nanoparticles. Hif-1α siRNA nanocomplexes significantly inhibited the expression of Hif-1α. Triple combination therapy (Paclitaxel (Ptx) + Imiquimod (Imq) + Cs/Hif-1α siRNA) inhibited tumor growth and downregulated cancer progression genes while upregulating cellular-immune-related cytokines. Mice without Cs/Hif-1α siRNA treatments revealed fewer cancer inhibitory effects and more TME immunosuppressive factors. These results suggest that the inhibition of Hif-1α effects synergize with Ptx and Imq to inhibit cancer progression more significantly than other combinational treatments.

Conclusion

Combining Hif-1α siRNA with Ptx and Imq is promising as a multimodality treatment. It has the potential to attenuate TME inhibitory effects and significantly enhance the immune system's ability to combat tumor cell growth, offering an inspiration of hope in the fight against BC.

Application of Pro-angiogenic Biomaterials in Myocardial Infarction

Biomaterials have potential applications in the treatment of myocardial infarction (MI). These biomaterials have the ability to mechanically support the ventricular wall and to modulate the inflammatory, metabolic, and local electrophysiological microenvironment. In addition, they can play an equally important role in promoting angiogenesis, which is the primary prerequisite for the treatment of MI. A variety of biomaterials are known to exert pro-angiogenic effects, but the pro-angiogenic mechanisms and functions of different biomaterials are complex and diverse, and have not yet been systematically described. This review will focus on the pro-angiogenesis of biomaterials and systematically describe the mechanisms and functions of different biomaterials in promoting angiogenesis in MI.

Molecular mechanisms of human overgrowth and use of omics in its diagnostics: chances and challenges

Overgrowth disorders comprise a group of entities with a variable phenotypic spectrum ranging from tall stature to isolated or lateralized overgrowth of body parts and or organs. Depending on the underlying physiological pathway affected by pathogenic genetic alterations, overgrowth syndromes are associated with a broad spectrum of neoplasia predisposition, (cardio) vascular and neurodevelopmental anomalies, and dysmorphisms. Pathologic overgrowth may be of prenatal or postnatal onset. It either results from an increased number of cells (intrinsic cellular hyperplasia), hypertrophy of the normal number of cells, an increase in interstitial spaces, or from a combination of all of these. The underlying molecular causes comprise a growing number of genetic alterations affecting skeletal growth and Growth-relevant signaling cascades as major effectors, and they can affect the whole body or parts of it (mosaicism). Furthermore, epigenetic modifications play a critical role in the manifestation of some overgrowth diseases. The diagnosis of overgrowth syndromes as the prerequisite of a personalized clinical management can be challenging, due to their clinical and molecular heterogeneity. Physicians should consider molecular genetic testing as a first diagnostic step in overgrowth syndromes. In particular, the urgent need for a precise diagnosis in tumor predisposition syndromes has to be taken into account as the basis for an early monitoring and therapy. With the (future) implementation of next-generation sequencing approaches and further omic technologies, clinical diagnoses can not only be verified, but they also confirm the clinical and molecular spectrum of overgrowth disorders, including unexpected findings and identification of atypical cases. However, the limitations of the applied assays have to be considered, for each of the disorders of interest, the spectrum of possible types of genomic variants has to be considered as they might require different methodological strategies. Additionally, the integration of artificial intelligence (AI) in diagnostic workflows significantly contribute to the phenotype-driven selection and interpretation of molecular and physiological data.

The prostate-specific membrane antigen holds potential as a vascular target for endogenous radiotherapy with [177Lu]Lu-PSMA-I&T for triple-negative breast cancer

INTRODUCTION

Overexpression of prostate-specific membrane antigen (PSMA) on the vasculature of triple-negative breast cancer (TNBC) presents a promising avenue for targeted endogenous radiotherapy with [177Lu]Lu-PSMA-I&T. This study aimed to assess and compare the therapeutic efficacy of a single dose with a fractionated dose of [177Lu]Lu-PSMA-I&T in an orthotopic model of TNBC.

METHODS

Rj:NMRI-Foxn1nu/nu mice were used as recipients of MDA-MB-231 xenografts. The single dose group was treated with 1 × 60 ± 5 MBq dose of [177Lu]Lu-PSMA-I&T, while the fractionated dose group received 4 × a 15 ± 2 MBq dose of [177Lu]Lu-PSMA-I&T at 7 day intervals. The control group received 0.9% NaCl. Tumor progression was monitored using [18F]FDG-PET/CT. Ex vivo analysis encompassed immunostaining, TUNEL staining, H&E staining, microautoradiography, and autoradiography.

RESULTS

Tumor volumes were significantly smaller in the single dose (p < 0.001) and fractionated dose (p < 0.001) groups. Tumor growth inhibition rates were 38% (single dose) and 30% (fractionated dose). Median survival was notably prolonged in the treated groups compared to the control groups (31d, 28d and 19d for single dose, fractionated dose and control, respectively). [177Lu]Lu-PSMA-I&T decreased the size of viable tumor areas. We further demonstrated, that [177Lu]Lu-PSMA-I&T binds specifically to the tumor-associated vasculature.

CONCLUSION

This study highlights the potential of [177Lu]Lu-PSMA-I&T for endogenous radiotherapy of TNBC.

Metformin Reduces Bone Resorption in Apical Periodontitis Through Regulation of Osteoblast and Osteoclast Differentiation

INTRODUCTION

We have previously demonstrated that auxiliary metformin therapy promotes healing of apical periodontitis. Here we aimed to investigate the effects of metformin on osteoblast differentiation and osteoclast formation in cultured cells and rat apical periodontitis.

METHODS

Murine pre-osteoblasts MC3T3-E1 and macrophages RAW264.7 were cultured under hypoxia (2% oxygen) or normoxia (21% oxygen) and stimulated with receptor activator of nuclear factor-κB ligand (RANKL) when indicated. Metformin was added to the cultures to evaluate its anti-hypoxic effects. Expressions of osteoblast differentiation regulator runt-related transcription factor 2 (RUNX2), RANKL, and osteoclast marker tartrate-resistant acid phosphatase (TRAP) were assessed by Western blot. Apical periodontitis was induced in mandibular first molars of 10 Sprague-Dawley rats. Root canal therapy with or without metformin supplement was performed. Periapical bone resorption was measured by micro-computed tomography. Immunohistochemistry was used to examine RUNX2, RANKL, and TRAP expressions.

RESULTS

Hypoxia suppressed RUNX2 expression and enhanced RANKL synthesis in pre-osteoblasts. TRAP production increased in macrophages after hypoxia and/or RANKL stimulation. Metformin reversed hypoxia-induced RUNX2 suppression and RANKL synthesis in pre-osteoblasts. Metformin also inhibited hypoxia and RANKL-enhanced TRAP synthesis in macrophages. Intracanal metformin diminished bone loss in rat apical periodontitis. Comparing with vehicle control, cells lining bone surfaces in metformin-treated lesions had significantly stronger expression of RUNX2 and decreased synthesis of RANKL and TRAP.

CONCLUSIONS

Alleviation of bone resorption by intracanal metformin was associated with enhanced osteoblast differentiation and diminished osteoclast formation in rat apical periodontitis. Our results endorsed the role of metformin as an effective medicament for inflammatory bone diseases.

Intraneural vascularity of the median, ulnar and common peroneal nerve: Microvascular ultrasound and pathophysiological implications

Objectives

Changes in the microvascular environment are considered crucial in the pathogenesis of compression neuropathies. Several studies have demonstrated elevated intraneural vascularity in severe neuropathy compared with healthy subjects, where intraneural vascularity is considered predominantly undetectable. The aim of this study was to assess and quantify intraneural vasculature by superb microvascular imaging (SMI) in healthy volunteers in the median, ulnar and common peroneal nerve.

Methods

Intraneural vascularity was quantified in 26 healthy volunteers (312 segments overall) by SMI sonography using a 22-MHz linear transducer. Individual nerve segment vascularity was compared with the mean vascularity using one-way ANOVA and Kruskal-Wallis tests, respectively. Vendor-provided quantification and manual vessel count were compared by linear regression analysis.

Results

Intraneural vascularity was detectable in all nerve segments (100.0%). Vessel density was highest in the median nerve at the wrist (1.54 ± 0.44/mm2, P < 0.0001) and lowest in the sulcal ulnar nerve (0.90 ± 0.34/mm2, P < 0.0001). Vendor-provided automated quantification severely overestimated vascular content compared with manual quantification.

Conclusion

Superb microvascular imaging can facilitate the visualisation of nerve vascularity and even detect local variations in vessel density. The pathophysiological implications for peripheral neuropathies, especially compression neuropathies, warrant further investigation, but the absence of visible intraneural vasculature as a negative finding in the diagnostic of compression neuropathies should be interpreted with caution, as the intraneural vascularity may lie beyond the 18 MHz resolution power of a transducer.

Hif1α/Dhrs3a Pathway Participates in Lipid Droplet Accumulation via Retinol and Ppar-γ in Fish Hepatocytes

Excessive hepatic lipid accumulation is a common phenomenon in cultured fish; however, its underlying mechanisms are poorly understood. Lipid droplet (LD)-related proteins play vital roles in LD accumulation. Herein, using a zebrafish liver cell line (ZFL), we show that LD accumulation is accompanied by differential expression of seven LD-annotated genes, among which the expression of dehydrogenase/reductase (SDR family) member 3 a/b (dhrs3a/b) increased synchronously. RNAi-mediated knockdown of dhrs3a delayed LD accumulation and downregulated the mRNA expression of peroxisome proliferator-activated receptor gamma (pparg) in cells incubated with fatty acids. Notably, Dhrs3 catalyzed retinene to retinol, the content of which increased in LD-enriched cells. The addition of exogenous retinyl acetate maintained LD accumulation only in cells incubated in a lipid-rich medium. Correspondingly, exogenous retinyl acetate significantly increased pparg mRNA expression levels and altered the lipidome of the cells by increasing the phosphatidylcholine and triacylglycerol contents and decreasing the cardiolipin, phosphatidylinositol, and phosphatidylserine contents. Administration of LW6, an hypoxia-inducible factor 1α (HIF1α) inhibitor, reduced the size and number of LDs in ZFL cells and attenuated hif1αa, hif1αb, dhrs3a, and pparg mRNA expression levels. We propose that the Hif-1α/Dhrs3a pathway participates in LD accumulation in hepatocytes, which induces retinol formation and the Ppar-γ pathway.

Hypoxia inducible factor-1α (HIF-1α) as an early predictor of acute hydrogen cyanamide (Dormex) poisoning

Hydrogen cyanamide (Dormex) is a plant growth regulator that is classified as a highly toxic poison. There are no definite investigations to help in its diagnosis and follow-up. This study aimed to investigate the role of hypoxia-inducible factor-1α (HIF-1α) in the diagnosis, prediction, and follow-up of Dormex-intoxicated patients. Sixty subjects were equally divided into two groups: group A, the control group, and group B, the Dormex group. Clinical and laboratory evaluations, including arterial blood gases (ABG), prothrombin concentration (PC), the international normalized ratio (INR), a complete blood count (CBC), and HIF-1α, were done on admission. CBC and HIF-1α were repeated for group B 24 and 48 h after admission to track abnormalities. Group B also had brain computed tomography (CT). Patients with abnormal CT scans were referred for brain magnetic resonance imaging (MRI). Significant differences in levels of HB, WBCs, and platelets were also detected in group B up to 48 h after admission, as white blood cells (WBCs) rose with time and hemoglobin (HB) and platelets diminished. The results described a highly significant difference in HIF-1α between the groups, and it depended on the clinical condition; therefore, it can be used in the prediction and follow-up of patients up to 24 h after admission.

The Neuroprotective Activities of the Novel Multi-Target Iron-Chelators in Models of Alzheimer's Disease, Amyotrophic Lateral Sclerosis and Aging

The concept of chelation therapy as a valuable therapeutic approach in neurological disorders led us to develop multi-target, non-toxic, lipophilic, brain-permeable compounds with iron chelation and anti-apoptotic properties for neurodegenerative diseases, such as Parkinson's disease (PD), Alzheimer's disease (AD), age-related dementia and amyotrophic lateral sclerosis (ALS). Herein, we reviewed our two most effective such compounds, M30 and HLA20, based on a multimodal drug design paradigm. The compounds have been tested for their mechanisms of action using animal and cellular models such as APP/PS1 AD transgenic (Tg) mice, G93A-SOD1 mutant ALS Tg mice, C57BL/6 mice, Neuroblastoma × Spinal Cord-34 (NSC-34) hybrid cells, a battery of behavior tests, and various immunohistochemical and biochemical techniques. These novel iron chelators exhibit neuroprotective activities by attenuating relevant neurodegenerative pathology, promoting positive behavior changes, and up-regulating neuroprotective signaling pathways. Taken together, these results suggest that our multifunctional iron-chelating compounds can upregulate several neuroprotective-adaptive mechanisms and pro-survival signaling pathways in the brain and might function as ideal drugs for neurodegenerative disorders, such as PD, AD, ALS, and aging-related cognitive decline, in which oxidative stress and iron-mediated toxicity and dysregulation of iron homeostasis have been implicated.

Neurotrophins in the Neuropathophysiology, Course, and Complications of Obstructive Sleep Apnea-A Narrative Review

Obstructive sleep apnea (OSA) is a disorder characterized by chronic intermittent hypoxia and sleep fragmentation due to recurring airway collapse during sleep. It is highly prevalent in modern societies, and due to its pleiotropic influence on the organism and numerous sequelae, it burdens patients and physicians. Neurotrophins (NTs), proteins that modulate the functioning and development of the central nervous system, such as brain-derived neurotrophic factor (BDNF), have been associated with OSA, primarily due to their probable involvement in offsetting the decline in cognitive functions which accompanies OSA. However, NTs influence multiple aspects of biological functioning, such as immunity. Thus, extensive evaluation of their role in OSA might enlighten the mechanism behind some of its elusive features, such as the increased risk of developing an immune-mediated disease or the association of OSA with cardiovascular diseases. In this review, we examine the interactions between NTs and OSA and discuss their contribution to OSA pathophysiology, complications, as well as comorbidities.

The immunolocalization of HIF-2α, GLUT1 and CAIX in porcine oviduct during the estrous cycle

Oxygen (O₂ ) rates in the oviduct are essential to human and animal reproduction. These rates are regulated by the activity of hypoxia markers such as the hypoxia-inducible factors (HIFs), the glucose transporters (GLUT), and the carbonic anhydrase (CA). In the porcine model, scarce studies have been reported regarding these markers and their effects in reproduction are unknown. The objective was to characterize the immunolocalization of HIF-2α, GLUT1, and CAIX in porcine oviducts throughout the estrous cycle. Oviducts (ampulla and isthmus) of adult sows (n = 45) were collected for histological and immunohistochemical analysis with HIF-2α, GLUT1, and CAIX markers. The percentage of immunopositive area was quantified, and the differences among phases of the estrous cycle were analyzed (folicular, early luteal, and late luteal). The three markers showed epithelial presence mainly. Significantly lower expression of HIF-2α was found in the luteal phases, especially in the isthmus. GLUT1 expression did not change throughout the estrous cycle, but differences were found between the ampulla and isthmus. CAIX expression showed the highest, with a significant downward trend throughout estrous cycle. The ubiquitous expression of hypoxia markers shows the porcine oviduct physiology in relation to O₂ . The differential expression of HIF-2α, GLUT1, and CAIX in different subcompartments of the oviduct throughout the estrous cycle contributes to improve the knowledge of the cell physiology of the oviduct, which can be useful in fertilization studies.

Role of Metabolism in Adoptive T Cell Therapy: Strategies and Challenges

Significance: Immune cell therapy involves the administration of immune cells into patients, and it has emerged as one of the most common type of immunotherapy for cancer treatment. Knowledge on the biology and metabolism of the adoptively transferred immune cells and the metabolic requirements of different cell types in the tumor is fundamental for the development of immune cell therapy with higher efficacy. Recent Advances: Adoptive T cell therapy has been shown to be effective in limited types of cancer. Different types and generations of adoptive T cell therapies have evolved in the recent decade. This review covers the basic principles and development of these therapies in cancer treatment. Critical Issues: Our review provides an overview on the basic concepts on T cell metabolism and highlights the metabolic requirements of T and adoptively transferred T cells. Future Directions: Integrating the knowledge just cited will facilitate the development of strategies to maximize the expansion of adoptively transferred T cells ex vivo and in vivo and to promote their durability and antitumor effects. Antioxid. Redox Signal. 37, 1303-1324.

Mitochondrial Regulation of the Hypoxia-Inducible Factor in the Development of Pulmonary Hypertension

Pulmonary hypertension (PH) is a severe progressive lung disorder characterized by pulmonary vasoconstriction and vascular remodeling, culminating in right-sided heart failure and increased mortality. Data from animal models and human subjects demonstrated that hypoxia-inducible factor (HIF)-related signaling is essential in the progression of PH. This review summarizes the regulatory pathways and mechanisms of HIF-mediated signaling, emphasizing the role of mitochondria in HIF regulation and PH pathogenesis. We also try to determine the potential to therapeutically target the components of the HIF system for the management of PH.

Regulation and Role of Neuron-Derived Hemoglobin in the Mouse Hippocampus

Hemoglobin (Hb) is the oxygen transport protein in erythrocytes. In blood, Hb is a tetramer consisting of two Hb-alpha (Hb-α) chains and two Hb-beta (Hb-β) chains. A number of studies have also shown that Hb-α is also expressed in neurons in both the rodent and human brain. In the current study, we examined for age-related regulation of neuronal Hb-α and hypoxia in the hippocampus and cerebral cortex of intact male and female mice. In addition, to confirm the role and functions of neuronal Hb-α, we also utilized lentivirus CRISPR interference-based Hb-α knockdown (Hb-α CRISPRi KD) in the non-ischemic and ischemic mouse hippocampus and examined the effect on neuronal oxygenation, as well as induction of hypoxia-inducible factor-1α (HIF-1α) and its downstream pro-apoptotic factors, PUMA and NOXA, and on neuronal survival and neurodegeneration. The results of the study revealed an age-related decrease in neuronal Hb-α levels and correlated increase in hypoxia in the hippocampus and cortex of intact male and female mice. Sex differences were observed with males having higher neuronal Hb-α levels than females in all brain regions at all ages. In vivo Hb-α CRISPRi KD in the mouse hippocampus resulted in increased hypoxia and elevated levels of HIF-1α, PUMA and NOXA in the non-ischemic and ischemic mouse hippocampus, effects that were correlated with a significant decrease in neuronal survival and increased neurodegeneration. As a whole, these findings indicate that neuronal Hb-α decreases with age in mice and has an important role in regulating neuronal oxygenation and neuroprotection.

Regulation of Transactivation at C-TAD Domain of HIF-1α by Factor-Inhibiting HIF-1α (FIH-1): A Potential Target for Therapeutic Intervention in Cancer

Hypoxia-inducible factor-1alpha (HIF-1α) is a major transcription factor that adapts to low oxygen homeostasis and regulates the expression of several hypoxic genes, which aid in cancer survival and development. It has recently piqued the interest of translational researchers in the disciplines of cancer sciences. Hypoxia triggers an ample adaptive mechanism mediated via the HIF-1α transcriptional domain. Anaerobic glycolysis, angiogenesis, metastasis, and mitophagy are adaptive mechanisms that support tumor survival by promoting oxygen supply and regulating oxygen demand in hypoxic tumor cells. Throughout this pathway, the factor-inhibiting HIF-1α is a negative regulator of HIF-1α leading to its hydroxylation at the C-TAD domain of HIF-1α under normoxia. Thus, hydroxylated HIF-1α is unable to proceed with the transcriptional events due to interference in binding of C-TAD and CBP/p300. From this review, we can hypothesize that remodeling of FIH-1 activity is a unique mechanism that decreases the transcriptional activity of HIF-1α and, as a result, all of its hypoxic consequences. Hence, this review manuscript details the depth of knowledge of FIH-1 on hypoxia-associated cellular and molecular events, a potential strategy for targeting hypoxia-induced malignancies.

Targeted Drug/Gene/Photodynamic Therapy via a Stimuli-Responsive Dendritic-Polymer-Based Nanococktail for Treatment of EGFR-TKI-Resistant Non-Small-Cell Lung Cancer

Yes-associated protein (YAP) has been identified as a key driver for epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI) resistance. Inhibition of YAP expression could be a potential therapeutic option for treating non-small-cell lung cancer (NSCLC). Herein, a nanococktail therapeutic strategy is proposed by employing amphiphilic and block-dendritic-polymer-based nanoparticles (NPs) for targeted co-delivery of EGFR-TKI gefitinib (Gef) and YAP-siRNA to achieve a targeted drug/gene/photodynamic therapy. The resulting NPs are effectively internalized into Gef-resistant NSCLC cells, successfully escape from late endosomes/lysosomes, and responsively release Gef and YAP-siRNA in an intracellular reductive environment. They preferentially accumulate at the tumor site after intravenous injection in both cell-line-derived xenograft (CDX) and patient-derived xenograft (PDX) models of Gef-resistant NSCLC, resulting in potent antitumor efficacy without distinct toxicity after laser irradiation. Mechanism studies reveal that the cocktail therapy could block the EGFR signaling pathway with Gef, inhibit activation of the EGFR bypass signaling pathway via YAP-siRNA, and induce tumor cell apoptosis through photodynamic therapy (PDT). Furthermore, this combination nanomedicine can sensitize PDT and impair glycolysis by downregulating HIF-1α. These results suggest that this stimuli-responsive dendritic-polymer-based nanococktail therapy may provide a promising approach for the treatment of EGFR-TKI resistant NSCLC.

A New Hypothetical Concept in Metabolic Understanding of Cardiac Fibrosis: Glycolysis Combined with TGF-β and KLF5 Signaling

The accumulation of fibrosis in cardiac tissues is one of the leading causes of heart failure. The principal cellular effectors in cardiac fibrosis are activated fibroblasts and myofibroblasts, which serve as the primary source of matrix proteins. TGF-β signaling pathways play a prominent role in cardiac fibrosis. The control of TGF-β by KLF5 in cardiac fibrosis has been demonstrated for modulating cardiovascular remodeling. Since the expression of KLF5 is reduced, the accumulation of fibrosis diminishes. Because the molecular mechanism of fibrosis is still being explored, there are currently few options for effectively reducing or reversing it. Studying metabolic alterations is considered an essential process that supports the explanation of fibrosis in a variety of organs and especially the glycolysis alteration in the heart. However, the interplay among the main factors involved in fibrosis pathogenesis, namely TGF-β, KLF5, and the metabolic process in glycolysis, is still indistinct. In this review, we explain what we know about cardiac fibroblasts and how they could help with heart repair. Moreover, we hypothesize and summarize the knowledge trend on the molecular mechanism of TGF-β, KLF5, the role of the glycolysis pathway in fibrosis, and present the future therapy of cardiac fibrosis. These studies may target therapies that could become important strategies for fibrosis reduction in the future.

The Signature of Moderate Perinatal Hypoxia on Cortical Organization and Behavior: Altered PNN-Parvalbumin Interneuron Connectivity of the Cingulate Circuitries

This study was designed in a rat model to determine the hallmarks of possible permanent behavioral and structural brain alterations after a single moderate hypoxic insult. Eighty-two Wistar Han (RccHan: WIST) rats were randomly subjected to hypoxia (pO2 73 mmHg/2 h) or normoxia at the first postnatal day. The substantially increased blood lactate, a significantly decreased cytochrome-C-oxygenase expression in the brain, and depleted subventricular zone suggested a high vulnerability of subset of cell populations to oxidative stress and consequent tissue response even after a single, moderate, hypoxic event. The results of behavioral tests (open-field, hole-board, social-choice, and T-maze) applied at the 30–45th and 70–85th postnatal days revealed significant hyperactivity and a slower pace of learning in rats subjected to perinatal hypoxia. At 3.5 months after hypoxic insult, the histochemical examination demonstrated a significantly increased number of specific extracellular matrix—perineuronal nets and increased parvalbumin expression in a subpopulation of interneurons in the medial and retrosplenial cingulate cortex of these animals. Conclusively, moderate perinatal hypoxia in rats causes a long-lasting reorganization of the connectivity in the cingulate cortex and consequent alterations of related behavioral and cognitive abilities. This non-invasive hypoxia model in the rat successfully and complementarily models the moderate perinatal hypoxic injury in fetuses and prematurely born human babies and may enhance future research into new diagnostic and therapeutic strategies for perinatal medicine.

Enhanced Ca2+ Entry Sustains the Activation of Akt in Glucose Deprived SH-SY5Y Cells

The two crucial cellular insults that take place during cerebral ischemia are the loss of oxygen and loss of glucose, which can both activate a cascade of events leading to neuronal death. In addition, the toxic overactivation of neuronal excitatory receptors, leading to Ca²⁺ overload, may contribute to ischemic neuronal injury. Brain ischemia can be simulated in vitro by oxygen/glucose deprivation, which can be reversible by the re-establishment of physiological conditions. Accordingly, we examined the effects of glucose deprivation on the PI3K/Akt survival signaling pathway and its crosstalk with HIF-1α and Ca²⁺ homeostasis in SH-SY5Y human neuroblastoma cells. It was found that glucose withdrawal decreased HIF-1α protein levels even in the presence of the ischemia-mimicking CoCl_2. On the contrary, and despite neuronal death, we identified a strong activation of the master pro-survival kinase Akt, a finding that was also confirmed by the increased phosphorylation of GSK3, a direct target of p-Akt. Remarkably, the elevated Ca²⁺ influx recorded was found to promptly trigger the activation of Akt, while a re-addition of glucose resulted in rapid restoration of both Ca²⁺ entry and p-Akt levels, highlighting the plasticity of neurons to respond to ischemic challenges and the important role of glucose homeostasis for multiple neurological disorders.

Overexpression of hypoxia-inducible factor 1α and excessive vascularization in the peri-implantation endometrium of infertile women with chronic endometritis

OBJECTIVE

Chronic endometritis (CE) contributes to impaired endometrial receptivity and is closely associated with poor in vitro fertilization (IVF) outcomes. However, the mechanisms underlying CE are unclear. Here, we investigated the role of the hypoxic microenvironment and endometrial vascularization in the peri-implantation endometrium of infertile women with CE.

METHODS

This retrospective study involved 15 fertile women and 77 infertile patients diagnosed with CE based on CD138+ ≥1/10 high-power fields (HPFs). The CE patients were divided into Group 1 (CD138+ 1-4/10 HPFs, 53 cases) and Group 2 (CD138+ ≥5/10 HPFs, 24 cases). The expression levels of hypoxia-inducible factor 1α (HIF1α), vascular endothelial growth factor A (VEGFA), and vascular endothelial growth factor receptor 2 (VEGFR2) in peri-implantation endometrium were assessed by qRT-PCR and western blot analyses. Spatial levels of HIF1α, VEGFA, and VEGFR2 in various endometrial compartments was determined using immunohistochemistry and H-score analysis. Microvascular density (MVD) was determined using CD34 staining and scored using Image J. Finally, we used qRT-PCR to assess changes in the expression of HIF1α, VEGFA, and VEGFR2 in CE patients after treatment with first-line antibiotics.

RESULTS

Relative to Group 1 and control group, during the implantation window, protein and mRNA levels of HIF1α, VEGFA, and VEGFR2 were markedly high in Group 2 (P<0.05). H-score analysis showed that HIF1α, VEGFA, and VEGFR2 in the luminal, glandular epithelium, and stromal compartments were markedly elevated in Group 2, comparing to control group and Group 1 (P<0.05). Moreover, markedly elevated MVD levels were observed in Group 2. Notably, the above indexes did not differ significantly in the control group versus Group 1. Treatment with antibiotics significantly suppressed the endometrial HIF1α and VEGFA levels in CE-cured patients.

CONCLUSIONS

Here, we for the first time report the upregulation of HIF1α, VEGFA, and VEGFR2, as well as excessive endometrial vascularization in the peri-implantation endometrium of CE patients. Our findings offer new insights into reduced endometrial receptivity in CE-associated infertility.

A review of the skeletal effects of exposure to high altitude and potential mechanisms for hypobaric hypoxia-induced bone loss

Mountaineering and exposure to high altitude result in physiological adaptations to the reduced inspiratory oxygen availability. Acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE) are well-described harmful effects of exposure to high altitude. Common to AMS, HAPE, and HACE are distinct clinical signs and symptoms of impaired function. However, several studies have suggested that high altitude might result in a substantial bone loss, which usually does not produce any apparent symptoms. This review aims to provide a comprehensive overview of, and map current knowledge of the skeletal effects of hypobaric hypoxia and high altitude. PubMed and Embase were searched from inception to September 6, 2021, to identify studies investigating the skeletal effects of exposure to hypobaric hypoxia and high altitude. Three hundred sixty titles and abstracts were screened, and 20 full-text articles were included (16 in vivo studies and four real-world human studies). In rodents, simulated high altitude up to 2900 m did not result in any adverse skeletal effects. In contrast, studies exposing animals to very high altitude (3500-5500 m) reported substantial reductions in BMD, cortical morphology, and bone strength, as well as deteriorated trabecular microstructure. Detrimental microstructural effects were also reported in rats exposed to simulated extreme altitude (6000 m). Finally, real-world human studies in mountaineers suggested high altitude exposure reduced bone mineral density (BMD) and that the harmful skeletal effects of hypobaric hypoxia were not entirely recovered after 12 months. In conclusion, in vivo and real-world studies demonstrated high altitude exposure results in adverse skeletal effects. The underlying mechanism for hypobaric hypoxia-induced bone loss is not elucidated.

Role of the Hypoxia-Inducible Factor Pathway in Normal and Osteoarthritic Meniscus and in Mice after Destabilization of the Medial Meniscus

OBJECTIVE

Meniscus injury and the hypoxia-inducible factor (HIF) pathway are independently linked to osteoarthritis pathogenesis, but the role of the meniscus HIF pathway remains unclear. We sought to identify and evaluate HIF pathway response in normal and osteoarthritic meniscus and to examine the effects of Epas1 (HIF-2α) insufficiency in mice on early osteoarthritis development.

METHODS

Normal and osteoarthritic human meniscus specimens were obtained and used for immunohistochemical evaluation and cell culture studies for the HIF pathway. Meniscus cells were treated with pro-inflammatory stimuli, including interleukins (IL)-1β, IL-6, transforming growth factor (TGF)-α, and fibronectin fragments (FnF). Target genes were also evaluated with HIF-1α and HIF-2α (Epas1) overexpression and knockdown. Wild-type (n = 36) and Epas1^+/- (n = 30) heterozygous mice underwent destabilization of the medial meniscus (DMM) surgery and were evaluated at 2 and 4 weeks postoperatively for osteoarthritis development using histology.

RESULTS

HIF-1α and HIF-2α immunostaining and gene expression did not differ between normal and osteoarthritic meniscus. While pro-inflammatory stimulation significantly increased both catabolic and anabolic gene expression in the meniscus, HIF-1α and Epas1 expression levels were not significantly altered. Epas1 overexpression significantly increased Col2a1 expression. Both wild-type and Epas1^+/- mice developed osteoarthritis following DMM surgery. There were no significant differences between genotypes at either time point.

CONCLUSION

The HIF pathway is likely not responsible for osteoarthritic changes in the human meniscus. Additionally, Epas1 insufficiency does not protect against osteoarthritis development in the mouse at early time points after DMM surgery. The HIF pathway may be more important for protection against catabolic stress.

Dynamic Oxygen Conditions Promote the Translocation of HIF-1α to the Nucleus in Mouse Blastocysts

Oxygen tension is one of the most critical factors for mammalian embryo development and its survival. The HIF protein is an essential transcription factor that activated under hypoxic conditions. In this study, we evaluated the effect of dynamic oxygen conditions on the expression of embryonic genes and translocation of hypoxia-inducible factor-1α (HIF-1α) in cultured mouse blastocysts. Two-pronuclear (2PN) zygotes harvested from ICR mice were subjected to either high oxygen (HO; 20%), low oxygen (LO; 5%), or dynamic oxygen (DO; 5% to 2%) conditions. In the DO group, PN zygotes were cultured in 5% O2 from days 1 to 3 and then in 2% O2 till day 5 after hCG injection. On day 5, the percentage of blastocysts in the cultured embryos from each group was estimated, and the embryos were also subjected to immunocytochemical and gene expression analysis. We found that the percentage of blastocysts was similar among the experimental groups; however, the percentage of hatching blastocysts in the DO and LO groups was significantly higher than that in the HO group. The total cell number of blastocysts in the DO group was significantly higher than that of both the HO and LO groups. Further, gene expression analysis revealed that the expression of genes related to the embryonic development was significantly higher in the DO group than that in the HO and LO groups. Interestingly, HIF-1α mRNA expression did not significantly differ; however, HIF-1α protein translocation from the cytoplasm to the nucleus was significantly higher in the DO group than in the HO and LO groups. Our study suggests that dynamic oxygen concentrations increase the developmental capacity in mouse preimplantation embryos through activation of the potent transcription factor HIF-1α.

New biomarkers from multiomics approaches: improving risk prediction of atrial fibrillation

Atrial fibrillation (AF) is a common cardiac arrhythmia leading to many adverse outcomes and increased mortality. Yet the molecular mechanisms underlying AF remain largely unknown. Recent advances in high-throughput technologies make large-scale molecular profiling possible. In the past decade, multiomics studies of AF have identified a number of potential biomarkers of AF. In this review, we focus on the studies of multiomics profiles with AF risk. We summarize recent advances in the discovery of novel biomarkers for AF through multiomics studies. We also discuss limitations and future directions in risk assessment and discovery of therapeutic targets for AF.

Correlation of 18F-FDG/PET SUVmax, SUVmean, MTV, and TLG with HIF-1α in Patients with Colorectal Cancer

Objectives:

Post-hypoxia hypoxia-inducible factor (HIF)-1α activation plays a vital role in colorectal cancer (CRC) angiogenesis. Although glucose metabolism is induced in some cancer types via HIF-1α, the prognostic significance of HIF-1α in CRC and its correlation with ¹⁸fluorinefluorodeoxyglucose (¹⁸F-FDG) uptake in positron emission tomography (PET) remain controversial. This study aims to investigate the association between ¹⁸F-FDG/PET parameters and HIF-1α expression in CRC.

Methods:

Thirty-six histopathologically confirmed patients with CRC who had ¹⁸F-FDG/PET scans before surgery were enrolled in the study. The correlations between the maximum standardized uptake value (SUV_max), SUV_mean, metabolic tumor volume (MTV), total lesion glycolysis, HIF-1α overexpression, and histopathological features were evaluated.

Results:

The tumor location, tumor diameter, perineural invasion, lymphovascular invasion, T and N stage were not significantly correlated with HIF-1α overexpression. In contrast, the tumor differentiation was negatively correlated with HIF-1α expression (r=-0.332, p=0.048). None of the ¹⁸F-FDG/PET parameters was significantly correlated with HIF-1α overexpression. A significant relationship was found between tumor differentiation, tumor necrosis percentage, and MTV (p=0.030, p=0.020).

Conclusion:

The expected association between HIF-1α overexpression and ¹⁸F-FDG/PET parameters was not found in this study. However, there was a relationship between MTV, tumor differentiation, and tumor necrosis percentage. Hence, further studies are required to predict the pathological and prognostic courses of CRC using a diagnostic ¹⁸F-FDG/PET evaluation.

HIF-1 α may play a role in late pregnancy hypoxia-induced autism-like behaviors in offspring rats

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that can be caused by various factors. The present study aimed to determine whether prenatal hypoxia can lead to ASD and the role of hypoxia-inducible factor-1α (HIF-1α) in this process. We constructed a prenatal hypoxia model of pregnant rats by piping nitrogen and oxygen mixed gas, with an oxygen concentration of 10 ± 0.5 %, into the self-made hypoxia chamber. Rats were subjected to different extents of hypoxia treatments at different points during pregnancy. The results showed that hypoxia for 6 h on the 17th gestation day is most likely to lead to autistic behavior in offspring rats, including social deficits, repetitive behaviors, and impaired learning and memory. The mRNA expression level of TNF-α also increased in hypoxia-induced autism group and valproic acid (VPA) group. Western blotting analysis showed increased levels of hypoxia inducible factor 1 alpha (HIF-1α) and decreased levels of phosphatase and tensin homolog (PTEN) in the hypoxic-induced autism group. Meanwhile, N-methyl d-aspartate receptor subtype 2 (NR2A) and glutamate ionotropic receptor AMPA type subunit 2 (GluR2) were upregulated in the hypoxic-induced autism group. HIF-1α might play a role in hypoxia-caused autism-like behavior and its regulatory effect is likely to be achieved by regulating synaptic plasticity.

HIF-1 regulates energy metabolism of the Tibetan chicken brain during embryo development under hypoxia

The Tibetan chicken (Gallus gallus; TBC) is an indigenous breed found in the Qinghai-Tibet Plateau that are well adapted to a hypoxic environment. The energy metabolism of embryonic brains in TBCs under hypoxia has been little reported. This study investigated changes in energy metabolism of the TBC brain during embryo development under hypoxia. We found that TBCs exhibited a change of glycolysis and the tricarboxylic acid cycle during embryo development under hypoxia. Hypoxia-inducible factor (HIF)-1 was potentially involved in this by directly inducing overexpression of pyruvate dehydrogenase kinase 1 (PDK1) and the glycolytic genes hexokinase 1 (HK1) and lactate dehydrogenase A (LDHA) to increase glycolysis of TBCs to adapt to hypoxia. Although these may not be unique to TBCs, as we had also found similar results in Dwarf Laying Chickens, a lowland chicken breed, TBCs had a stronger regulating ability. In summary, our study revealed that HIF-1 induced energy metabolism changes in the TBC brain via upregulating expressions of PDK1 and other HIF-1 target genes like HK1 and LDHA to increase glycolysis for TBC hypoxic adaptations during embryo development. It indicates the potential application of TBC energy metabolism research for other animals living on the Qinghai-Tibet Plateau.

HIF-1α/BNIP3-Mediated Autophagy Contributes to the Luteinization of Granulosa Cells During the Formation of Corpus Luteum

During the luteinization after ovulation in mammalian ovary, the containing cells undergo an energy consuming function re-determination process to differentiate into luteal cells under avascular environment. Previous evidences have delineated the contribution of autophagy to the cell differentiation and the catabolic homeostasis in various types of mammalian cells, whereas few interest had been focused on the involvement of autophagy in the luteinization of granulosa cells during the formation of early corpus luteum. Herein, the present study investigated that expression and contribution of autophagy during granulosa cell luteinization and early luteal development through in vivo and in vitro experiments. The results clearly demonstrated that HIF-1α/BNIP3-mediated autophagy plays a vital role in the luteinization of granulosa cells during the early luteal formation in vivo and in vitro. In the neonatal corpus luteum, HIF-1α up-regulated BNIP3 expressions, which contributed to the autophagic initiation by disrupting beclin1 from Bcl-2/beclin1 complex and protected cells from apoptosis by curbing the skew of mitochondria balance under avascular niche. Notably, Inhibition of HIF-1α activity by echinomycin enhanced the levels of cytoplasmic cytochrome c and cell apoptosis in the nascent corpus luteum. These findings revealed that HIF-1α/BNIP3-mediated autophagy enabled the process of granulosa cell luteinization and protected the granulosa-lutein cells from further apoptosis under hypoxia niche. To our knowledge, the present study firstly clarified that HIF-1α/BNIP3-mediated autophagy contributes to the luteinization of granulosa cells during the formation of pregnant corpus luteum, which will help us further understanding the luteal biology and provide us new clues for the treatment of luteal insufficiency.

Neuroprotective Effect of Vascular Endothelial Growth Factor on Motoneurons of the Oculomotor System

Vascular endothelial growth factor (VEGF) was initially characterized as a potent angiogenic factor based on its activity on the vascular system. However, it is now well established that VEGF also plays a crucial role as a neuroprotective factor in the nervous system. A deficit of VEGF has been related to motoneuronal degeneration, such as that occurring in amyotrophic lateral sclerosis (ALS). Strikingly, motoneurons of the oculomotor system show lesser vulnerability to neurodegeneration in ALS compared to other motoneurons. These motoneurons presented higher amounts of VEGF and its receptor Flk-1 than other brainstem pools. That higher VEGF level could be due to an enhanced retrograde input from their target muscles, but it can also be produced by the motoneurons themselves and act in an autocrine way. By contrast, VEGF’s paracrine supply from the vicinity cells, such as glial cells, seems to represent a minor source of VEGF for brainstem motoneurons. In addition, ocular motoneurons experiment an increase in VEGF and Flk-1 level in response to axotomy, not observed in facial or hypoglossal motoneurons. Therefore, in this review, we summarize the differences in VEGF availability that could contribute to the higher resistance of extraocular motoneurons to injury and neurodegenerative diseases.

Regulation of Angiotensin-Converting Enzyme 2: A Potential Target to Prevent COVID-19?

The renin-angiotensin system (RAS) is crucially involved in the physiology and pathology of all organs in mammals. Angiotensin-converting enzyme 2 (ACE2), which is a homolog of ACE, acts as a negative regulator in the homeostasis of RAS. ACE2 has been proven to be the receptor of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which caused the coronavirus disease 2019 (COVID-19) pandemic. As SARS-CoV-2 enters the host cells through binding of viral spike protein with ACE2 in humans, the distribution and expression level of ACE2 may be critical for SARS-CoV-2 infection. Growing evidence shows the implication of ACE2 in pathological progression in tissue injury and several chronic conditions such as hypertension, diabetes, and cardiovascular disease; this suggests that ACE2 is essential in the progression and clinical prognosis of COVID-19 as well. Therefore, we summarized the expression and activity of ACE2 under various conditions and regulators. We further discussed its potential implication in susceptibility to COVID-19 and its potential for being a therapeutic target in COVID-19.

CD73 alleviates GSDMD-mediated microglia pyroptosis in spinal cord injury through PI3K/AKT/Foxo1 signaling

BACKGROUND

Neuroinflammation-induced secondary injury is an important cause of sustained progression of spinal cord injury. Inflammatory programmed cell death pyroptosis executed by the pore-forming protein gasdermin D (GSDMD) is an essential step of neuroinflammation. However, it is unclear whether CD73, a widely accepted immunosuppressive molecule, can inhibit pyroptosis via mediating GSDMD.

METHODS

C57BL/6J CD73 deficient mice and wild-type mice, Lipopolysaccharide (LPS)-induced primary microglia and BV2 cells were respectively used to illustrate the effect of CD73 on microglia pyroptosis in vivo and in vitro. A combination of molecular and histological methods was performed to assess pyroptosis and explore the mechanism both in vivo and in vitro.

RESULTS

We have shown molecular evidence for CD73 suppresses the activation of NLRP3 inflammasome complexes to reduce the maturation of GSDMD, leading to decreased pyroptosis in microglia. Further analysis reveals that adenosine-A2B adenosine receptor-PI3K-AKT-Foxo1 cascade is a possible mechanism of CD73 regulation. Importantly, we determine that CD73 inhibits the expression of GSDMD at the transcriptional level through Foxo1. What's more, we confirm the accumulation of HIF-1α promotes the overexpression of CD73 after spinal cord injury (SCI), and the increased CD73 in turn upregulates the expression of HIF-1α, eventually forming a positive feedback regulatory loop.

CONCLUSION

Our data reveal a novel function of CD73 on microglia pyroptosis, suggesting a unique therapeutic opportunity for mitigating the disease process in SCI.

Hypoxia-Inducible Factor (HIF): Fuel for Cancer Progression

Hypoxia is an integral part of the tumor microenvironment, caused primarily due to rapidly multiplying tumor cells and a lack of proper blood supply. Among the major hypoxic pathways, HIF-1 transcription factor activation is one of the widely investigated pathways in the hypoxic tumor microenvironment (TME). HIF-1 is known to activate several adaptive reactions in response to oxygen deficiency in tumor cells. HIF-1 has two subunits, HIF-1β (constitutive) and HIF-1α (inducible). The HIF-1α expression is largely regulated via various cytokines (through PI3K-ACT-mTOR signals), which involves the cascading of several growth factors and oncogenic cascades. These events lead to the loss of cellular tumor suppressant activity through changes in the level of oxygen via oxygen-dependent and oxygen-independent pathways. The significant and crucial role of HIF in cancer progression and its underlying mechanisms have gained much attention lately among the translational researchers in the fields of cancer and biological sciences, which have enabled them to correlate these mechanisms with various other disease modalities. In the present review, we have summarized the key findings related to the role of HIF in the progression of tumors.

Ensemble-based virtual screening in discovering potent inhibitors targeting Von Hippel-Lindau (VHL) E3 ubiquitin ligase

BACKGROUND

The Von Hippel-Lindau (VHL) E3 ubiquitin ligase, which mediates its substrate hypoxia-inducible factor 1α (HIF-1α) for ubiquitination and subsequent degradation, is an attractive drug target in various diseases, such as anemia, inflammation, neurodegeneration and cancer. Proteolysis targeting chimeras (PROTACs) containing a VHL ligand that can hijack the E3 ligase activity to degrade the target protein has also been studied in academic and in industry areas recently.

METHODS

Herein, by developing and optimizing the Bayesian Model, we report ensemble-based virtual screening as an effective strategy to discover potential VHL inhibitors from Specs database.

RESULTS

The virtual screening protocol was developed, ten representative molecules were obtained and five compounds were selected for subsequent binding mode analysis to be potent VHL inhibitors.

Solid Lipid Nanoparticles and Nanostructured Lipid Carriers as Smart Drug Delivery Systems in the Treatment of Glioblastoma Multiforme

Glioblastoma multiforme (GBM) is the most common and malignant type of brain tumor. In fact, tumor recurrence usually appears a few months after surgical resection and chemotherapy, mainly due to many factors that make GBM treatment a real challenge, such as tumor location, heterogeneity, presence of the blood-brain barrier (BBB), and others. Solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) represent the most promising carriers for therapeutics delivery into the central nervous system (CNS) owing to their inherent ability to cross the BBB. In this review, we present the main challenges in GBM treatment, a description of SLNs and NLCs and their valuable role as drug carriers in GBM treatment, and finally, a detailed description of all modification strategies that aim to change composition of SLNs and NLCs to enhance treatment outcomes. This includes modification of SLNs and NLCs to improve crossing the BBB, reduced GBM cell resistance, target GBM cells selectively minimizing side effects, and modification strategies to enhance SLNs and NLCs nose-to-brain delivery. Finally, future perspectives on their use are also be discussed, to provide insight about all strategies with SLNs and NLCs formulation that could result in drug delivery systems for GBM treatment with highly effective theraputic and minimum undesirable effects.

Endosome-triggered ion-releasing nanoparticles as therapeutics to enhance the angiogenic efficacy of human mesenchymal stem cells

Here, we report that Fe ions delivered into human mesenchymal stem cells (hMSCs) by bioreducible metal nanoparticles (NPs) enhance their angiogenic and cell-homing efficacy by controlling ion-triggered intracellular reactive oxygen species (ROS) and improve cell migration, while reducing cytotoxicity. Endosome-triggered iron-ion-releasing nanoparticles (ETIN) were designed to be low-pH responsive to take advantage of the low-pH conditions (4-5) of endosomes for in situ iron-ion release. Due to the different redox potentials of Fe and Au, only Fe could be ionized and released from our novel ETIN, while Au remained intact after ETIN endocytosis. Treatment with an optimal amount of ETIN led to a mild increase in intracellular ROS levels in hMSCs, which enhanced the expression of HIF-1α, a key trigger for angiogenic growth factor secretion from hMSCs. Treatmetn of hMSCs with ETIN significantly enhanced the expression of angiogenesis- and lesion-targeting-related genes and proteins. Transplantation of ETIN-treated hMSCs significantly enhanced angiogenesis and tissue regeneration in a wound-closing mouse model compared with those in untreated mice and mice that underwent conventional hMSC transplantation.

Chemical simulation of hypoxia in donor cells improves development of somatic cell nuclear transfer-derived embryos and increases abundance of transcripts related to glycolysis

To improve efficiency of somatic cell nuclear transfer (SCNT), it is necessary to modify differentiated donor cells to become more amendable for reprogramming by the oocyte cytoplasm. A key feature that distinguishes somatic/differentiated cells from embryonic/undifferentiated cells is cellular metabolism, with somatic cells using oxidative phosphorylation (OXPHOS) while embryonic cells utilize glycolysis. Inducing metabolic reprogramming in donor cells could improve SCNT efficiency by priming cells to become more embryonic in nature before SCNT hypoxia inducible factor 1-α (HIF1-α), a transcription factor that allows for cell survival in low oxygen, promotes a metabolic switch from OXPHOS to glycolysis. We hypothesized that chemically stabilizing HIF1-α in donor cells by use of the hypoxia mimetic, cobalt chloride (CoCl2 ), would promote this metabolic switch in donor cells and subsequently improve the development of SCNT embryos. Donor cell treatment with 100 µM CoCl2 for 24 hr preceding SCNT upregulated messenfer RNA abundance of glycolytic enzymes, improved SCNT development to the blastocyst stage and quality, and affected gene expression in the blastocysts. After transferring blastocysts created from CoCl2 -treated donor cells to surrogates, healthy cloned piglets were produced. Therefore, shifting metabolism toward glycolysis in donor cells by CoCl2 treatment is a simple, economical way of improving the in vitro efficiency of SCNT and is capable of producing live animals.

Tetrazoles as anticancer agents: A review on synthetic strategies, mechanism of action and SAR studies

Cancer is a leading cause of death worldwide. Even after the availability of numerous drugs and treatments in the market, scientists and researchers are focusing on new therapies because of their resistance and toxicity issues. The newly synthesized drug candidates are able to demonstrate in vitro activity but are unable to reach clinical trials due to their rapid metabolism and low bioavailability. Therefore there is an imperative requisite to expand novel anticancer negotiators with tremendous activity as well as in vivo efficacy. Tetrazole is a promising pharmacophore which is metabolically more stable and acts as a bioisosteric analogue for many functional groups. Tetrazole fragment is often castoff with other pharmacophores in the expansion of novel anticancer drugs. This is the first systematic review that emphasizes on contemporary strategies used for the inclusion of tetrazole moiety, mechanistic targets along with comprehensive structural activity relationship studies to provide perspective into the rational design of high-efficiency tetrazole-based anticancer drug candidates.

PPAR Beta/Delta and the Hallmarks of Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor family. Three different isoforms, PPAR alpha, PPAR beta/delta and PPAR gamma have been identified. They all form heterodimers with retinoic X receptors to activate or repress downstream target genes dependent on the presence/absence of ligands and coactivators or corepressors. PPARs differ in their tissue expression profile, ligands and specific agonists and antagonists. PPARs attract attention as potential therapeutic targets for a variety of diseases. PPAR alpha and gamma agonists are in clinical use for the treatment of dyslipidemias and diabetes. For both receptors, several clinical trials as potential therapeutic targets for cancer are ongoing. In contrast, PPAR beta/delta has been suggested as a therapeutic target for metabolic syndrome. However, potential risks in the settings of cancer are less clear. A variety of studies have investigated PPAR beta/delta expression or activation/inhibition in different cancer cell models in vitro, but the relevance for cancer growth in vivo is less well documented and controversial. In this review, we summarize critically the knowledge of PPAR beta/delta functions for the different hallmarks of cancer biological capabilities, which interplay to determine cancer growth.

Improvement of human pancreatic islet quality after co-culture with human adipose-derived stem cells

The aim of this study was to investigate whether co-culture of human islets with adipose-derived stem cells (ASCs) can improve islet quality and to evaluate which factors play a role in the protective effect of ASCs against islet dysfunction. Islets and ASCs were cultured in three experimental groups for 24 h, 48 h, and 72 h: 1) indirect co-culture of islets with ASC monolayer (Islets/ASCs); 2) islets alone; and 3) ASCs alone. Co-culture with ASCs improved islet viability and function in all culture time-points analyzed. VEGFA, HGF, IL6, IL8, IL10, CCL2, IL1B, and TNF protein levels were increased in supernatants of islet/ASC group compared to islets alone, mainly after 24 h. Moreover, VEGFA, IL6, CCL2, HIF1A, XIAP, CHOP, and NFKBIA genes were differentially expressed in islets from the co-culture condition compared to islets alone. In conclusion, co-culture of islets with ASCs promotes improvements in islet quality.

Inorganic Biomaterials for Regenerative Medicine

Regenerative medicine leverages the innate potential of the human body to efficiently repair and regenerate damaged tissues using engineered biomaterials. By designing responsive biomaterials with the appropriate biophysical and biochemical characteristics, cellular response can be modulated to direct tissue healing. Recently, inorganic biomaterials have been shown to regulate cellular responses including cell-cell and cell-matrix interactions. Moreover, ions released from these mineral-based biomaterials play a vital role in defining cell identity, as well as driving tissue-specific functions. The intrinsic properties of inorganic biomaterials, such as the release of bioactive ions (e.g., Ca, Mg, Sr, Si, B, Fe, Cu, Zn, Cr, Co, Mo, Mn, Au, Ag, V, Eu, and La), can be leveraged to induce phenotypic changes in cells or modulate the immune microenvironment to direct tissue healing and regeneration. Biophysical characteristics of biomaterials, such as topography, charge, size, electrostatic interactions, and stiffness can be modulated by addition of inorganic micro- and nanoparticles to polymeric networks have also been shown to play an important role in their biological response. In this Review, we discuss the recent emergence of inorganic biomaterials to harness the innate regenerative potential of the body. Specifically, we will discuss various biophysical or biochemical effects of inorganic-based materials in directing cellular response for regenerative medicine applications.

Tissue-Specific Peculiarities of Vibration-Induced Hypoxia in Rabbit Liver and Kidney

Activity of the energy production systems in rabbit liver and kidney under conditions of unfavorable vibration exposure was studied by the polarography method using a galvanic-type closed oxygen sensor. The rate of oxidation of endogenous substrates by mitochondria was determined by the tissue and was 5.2±0.6 and 8.13±1.4 (ng-atom O)×min^-1×mg^-1 protein for liver and kidney of intact animals, respectively. After 21 vibration sessions against the background of inhibition of NAD-dependent substrate oxidation in liver mitochondria, the rate metabolism of exogenous succinic acid increased by 44% and then decreased with prolongation of the effect, which indicated impaired function of the respiratory chain. Similar fluctuations of the parameters were revealed in kidney mitochondria, though their amplitude was lower. The study of bioenergetic mechanisms of hypoxia in various tissues makes it possible to determine the targets for the pharmacological action of antihypoxic drugs.

Hydrogel vehicles for sequential delivery of protein drugs to promote vascular regeneration

In recent years, as the mechanisms of vasculogenesis and angiogenesis have been uncovered, the functions of various pro-angiogenic growth factors (GFs) and cytokines have been identified. Therefore, therapeutic angiogenesis, by delivery of GFs, has been sought as a treatment for many vascular diseases. However, direct injection of these protein drugs has proven to have limited clinical success due to their short half-lives and systemic off-target effects. To overcome this, hydrogel carriers have been developed to conjugate single or multiple GFs with controllable, sustained, and localized delivery. However, these attempts have failed to account for the temporal complexity of natural angiogenic pathways, resulting in limited therapeutic effects. Recently, the emerging ideas of optimal sequential delivery of multiple GFs have been suggested to better mimic the biological processes and to enhance therapeutic angiogenesis. Incorporating sequential release into drug delivery platforms will likely promote the formation of neovasculature and generate vast therapeutic potential.