HIF Prolyl Hydroxylase Inhibitors for COVID-19 Treatment: Pros and Cons

Expression and Regulation of Hypoxia-Inducible Factor Signalling in Acute Lung Inflammation

Hypoxia-inducible factors (HIFs) are central regulators of gene expression in response to oxygen deprivation, a common feature in critical illnesses. The significant burden that critical illnesses place on global healthcare systems highlights the need for a deeper understanding of underlying mechanisms and the development of innovative treatment strategies. Among critical illnesses, impaired lung function is frequently linked to hypoxic conditions. This review focuses on the expression and regulation of HIF signalling in experimental models of acute lung injury (ALI) and clinical studies in critically ill patients with acute respiratory distress syndrome (ARDS). We explore the potential dual role of HIF signalling in acute lung inflammation. Furthermore, its role in key biological processes and its potential prognostic significance in clinical scenarios are discussed. Finally, we explore recent pharmacological advancements targeting HIF signalling, which have emerged as promising alternatives to existing therapeutic approaches, potentially enabling more effective management strategies.

Intertwined regulators: hypoxia pathway proteins, microRNAs, and phosphodiesterases in the control of steroidogenesis

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

The significance of ferroptosis in renal diseases and its therapeutic potential

Kidney diseases are significant global public health concern, with increasing prevalence and substantial economic impact. Developing novel therapeutic approaches are essential for delaying disease progression and improving patient quality of life. Cell death signifying the termination of cellular life, could facilitate appropriate bodily development and internal homeostasis. Recently, regulated cell death (RCD) forms such as ferroptosis, characterized by iron-dependent lipid peroxidation, has garnered attention in diverse renal diseases and other pathological conditions. This review offers a comprehensive examination of ferroptosis, encompassing an analysis of the involvement of iron and lipid metabolism, the System Xc - /glutathione/glutathione peroxidase 4 signaling, and additional associated pathways. Meanwhile, the review delves into the potential of targeting ferroptosis as a therapeutic approach in the management of acute kidney injury (AKI), chronic kidney disease (CKD), diabetic nephropathy, and renal tumors. Furthermore, it emphasizes the significance of ferroptosis in the transition from AKI to CKD and further accentuates the potential for repurposing drug and utilizing traditional medicine in targeting ferroptosis-related pathways for clinical applications. The integrated review provides valuable insights into the role of ferroptosis in kidney diseases and highlights the potential for targeting ferroptosis as a therapeutic strategy.

Review of COVID-19 Therapeutics by Mechanism: From Discovery to Approval

The global research and pharmaceutical community rapidly mobilized to develop treatments for coronavirus disease 2019 (COVID-19). Existing treatments have been repurposed and new drugs have emerged. Here we summarize mechanisms and clinical trials of COVID-19 therapeutics approved or in development. Two reviewers, working independently, reviewed published data for approved COVID-19 vaccines and drugs, as well as developmental pipelines, using databases from the following organizations: United States Food and Drug Administration (US-FDA), European Medicines Agency (EMA), Japanese Pharmaceutical and Medical Devices Agency (PMDA), and ClinicalTrials.gov. In all, 387 drugs were found for initial review. After removing unrelated trials and drugs, 66 drugs were selected, including 17 approved drugs and 49 drugs under development. These drugs were classified into six categories: 1) drugs targeting the viral life cycle 2) Anti-severe acute respiratory syndrome coronavirus 2 Monoclonal Antibodies, 3) immunomodulators, 4) anti-coagulants, 5) COVID-19-induced neuropathy drugs, and 6) other therapeutics. Among the 49 drugs under development are the following: 6 drugs targeting the viral life cycle, 12 immunosuppression drugs, 2 immunostimulants, 2 HIF-PHD targeting drugs, 3 GM-CSF targeting drugs, 5 anti-coagulants, 2 COVID-19-induced neuropathy drugs, and 17 others. This review provides insight into mechanisms of action, properties, and indications for COVID-19 medications.

Long-term treatment of chronic kidney disease patients with anemia using hypoxia-inducible factor prolyl hydroxylase inhibitors: potential concerns

Hypoxia-inducible factor prolyl hydroxylase inhibitors (HIF-PHIs) have been approved in several countries as a supplement or even an alternative to the clinical treatment of anemia in patients with chronic kidney disease (CKD). Activation of HIF by HIF-PHIs effectively increases hemoglobin (Hb) level in CKD patients by inducing multiple HIF downstream signaling pathways. This indicates that HIF-PHIs have effects beyond erythropoietin, while their potential benefits and risks should be necessarily assessed. Multiple clinical trials have largely demonstrated the efficacy and safety of HIF-PHIs in the short-term treatment of anemia. However, in terms of long-term administration, especially over 1 year, the benefits and risks of HIF-PHIs still need to be assessed. Particular attention should be paid to the risk of kidney disease progression, cardiovascular events, retinal diseases, and tumor risk. This review aims to summarize the current potential risks and benefits of HIF-PHIs in CKD patients with anemia and further discuss the mechanism of action and pharmacological properties of HIF-PHIs, in order to provide direction and theoretical support for future studies.

Role of succinate in airway epithelial cell regulation following traumatic lung injury

Lung contusion and gastric aspiration (LC and GA) are major risk factors for developing acute respiratory distress following trauma. Hypoxia from lung injury is mainly regulated by hypoxia-inducible factor 1α (HIF-1α). Published data from our group indicate that HIF-1α regulation in airway epithelial cells (AEC) drives the acute inflammatory response following LC and GA. Metabolomic profiling and metabolic flux of Type II AEC following LC revealed marked increases in glycolytic and TCA intermediates in vivo and in vitro that were HIF-1α dependent. GLUT-1/4 expression was also increased in HIF-1α+/+ mice, suggesting that increased glucose entry may contribute to increased intermediates. Importantly, lactate incubation in vitro on Type II cells did not significantly increase the inflammatory byproduct IL-1β. Contrastingly, succinate had a direct proinflammatory effect on human small AEC by IL-1β generation in vitro. This effect was reversed by dimethylmalonate, suggesting an important role for succinate dehydrogenase in mediating HIF-1α effects. We confirmed the presence of the only known receptor for succinate binding, SUCNR1, on Type II AEC. These results support the hypothesis that succinate drives HIF-1α-mediated airway inflammation following LC. This is the first report to our knowledge of direct proinflammatory activation of succinate in nonimmune cells such as Type II AEC in direct lung injury models.

Targeting 2-Oxoglutarate-Dependent Dioxygenases Promotes Metabolic Reprogramming That Protects against Lethal SARS-CoV-2 Infection in the K18-hACE2 Transgenic Mouse Model

Dysregulation of host metabolism is a feature of lethal SARS-CoV-2 infection. Perturbations in α-ketoglutarate levels can elicit metabolic reprogramming through 2-oxoglutarate-dependent dioxygenases (2-ODDGs), leading to stabilization of the transcription factor HIF-1α. HIF1-α activation has been reported to promote antiviral mechanisms against SARS-CoV-2 through direct regulation of ACE2 expression (a receptor required for viral entry). However, given the numerous pathways HIF-1α serves to regulate it is possible that there are other undefined metabolic mechanisms contributing to the pathogenesis of SARS-CoV-2 independent of ACE2 downregulation. In this study, we used in vitro and in vivo models in which HIF-1α modulation of ACE2 expression was negated, allowing for isolated characterization of the host metabolic response within SARS-CoV-2 disease pathogenesis. We demonstrated that SARS-CoV-2 infection limited stabilization of HIF-1α and associated mitochondrial metabolic reprogramming by maintaining activity of the 2-ODDG prolyl hydroxylases. Inhibition of 2-ODDGs with dimethyloxalylglycine promoted HIF-1α stabilization following SARS-CoV-2 infection, and significantly increased survival among SARS-CoV-2-infected mice compared with vehicle controls. However, unlike previous reports, the mechanism by which activation of HIF-1α responses contributed to survival was not through impairment of viral replication. Rather, dimethyloxalylglycine treatment facilitated direct effects on host metabolism including increased glycolysis and resolution of dysregulated pools of metabolites, which correlated with reduced morbidity. Taken together, these data identify (to our knowledge) a novel function of α-ketoglutarate-sensing platforms, including those responsible for HIF-1α stabilization, in the resolution of SARS-CoV-2 infection and support targeting these metabolic nodes as a viable therapeutic strategy to limit disease severity during infection.

Ferroptosis and multi-organ complications in COVID-19: mechanisms and potential therapies

COVID-19 is an infectious disease caused by SARS-CoV-2, with respiratory symptoms as primary manifestations. It can progress to severe illness, leading to respiratory failure and multiple organ dysfunction. Recovered patients may experience persistent neurological, respiratory, or cardiovascular symptoms. Mitigating the multi-organ complications of COVID-19 has been highlighted as a crucial part of fighting the epidemic. Ferroptosis is a type of cell death linked to altered iron metabolism, glutathione depletion, glutathione peroxidase 4 (GPX4) inactivation, and increased oxidative stress. Cell death can prevent virus replication, but uncontrolled cell death can also harm the body. COVID-19 patients with multi-organ complications often exhibit factors related to ferroptosis, suggesting a possible connection. Ferroptosis inhibitors can resist SARS-CoV-2 infection from damaging vital organs and potentially reduce COVID-19 complications. In this paper, we outline the molecular mechanisms of ferroptosis and, based on this, discuss multi-organ complications in COVID-19, then explore the potential of ferroptosis inhibitors as a supplementary intervention for COVID-19. This paper will provide a reference for the possible treatment of SARS-CoV-2 infected disease to reduce the severity of COVID-19 and its subsequent impact.

Hypoxia-Inducible Factor 1α and Its Role in Lung Injury: Adaptive or Maladaptive

Hypoxia-inducible factors (HIFs) are transcription factors critical for the adaptive response to hypoxia. There is also an essential link between hypoxia and inflammation, and HIFs have been implicated in the dysregulated immune response to various insults. Despite the prevalence of hypoxia in tissue trauma, especially involving the lungs, there remains a dearth of studies investigating the role of HIFs in clinically relevant injury models. Here, we summarize the effects of HIF-1α on the vasculature, metabolism, inflammation, and apoptosis in the lungs and review the role of HIFs in direct lung injuries, including lung contusion, acid aspiration, pneumonia, and COVID-19. We present data that implicates HIF-1α in the context of arguments both in favor and against its role as adaptive or injurious in the propagation of the acute inflammatory response in lung injuries. Finally, we discuss the potential for pharmacological modulation of HIFs as a new class of therapeutics in the modern intensive care unit.

A comparative study of COVID-19 transcriptional signatures between clinical samples and preclinical cell models in the search for disease master regulators and drug repositioning candidates

Coronavirus disease 2019 (COVID-19) is an acute viral disease with millions of cases worldwide. Although the number of daily new cases and deaths has been dropping, there is still a need for therapeutic alternatives to deal with severe cases. A promising strategy to prospect new therapeutic candidates is to investigate the regulatory mechanisms involved in COVID-19 progression using integrated transcriptomics approaches. In this work, we aimed to identify COVID-19 Master Regulators (MRs) using a series of publicly available gene expression datasets of lung tissue from patients which developed the severe form of the disease. We were able to identify a set of six potential COVID-19 MRs related to its severe form, namely TAL1, TEAD4, EPAS1, ATOH8, ERG, and ARNTL2. In addition, using the Connectivity Map drug repositioning approach, we identified 52 different drugs which could be used to revert the disease signature, thus being candidates for the design of novel clinical treatments. Furthermore, we compared the identified signature and drugs with the ones obtained from the analysis of nasopharyngeal swab samples from infected patients and preclinical cell models. This comparison showed significant similarities between them, although also revealing some limitations on the overlap between clinical and preclinical data in COVID-19, highlighting the need for careful selection of the best model for each disease stage.

Regulation of cells of the arterial wall by hypoxia and its role in the development of atherosclerosis

The cell's response to hypoxia depends on stabilization of the hypoxia-inducible factor 1 complex and transactivation of nuclear factor kappa-B (NF-κB). HIF target gene transcription in cells resident to atherosclerotic lesions adjoins a complex interplay of cytokines and mediators of inflammation affecting cholesterol uptake, migration, and inflammation. Maladaptive activation of the HIF-pathway and transactivation of nuclear factor kappa-B causes monocytes to invade early atherosclerotic lesions, maintaining inflammation and aggravating a low-oxygen environment. Meanwhile HIF-dependent upregulation of the ATP-binding cassette transporter ABCA1 causes attenuation of cholesterol efflux and ultimately macrophages becoming foam cells. Hypoxia facilitates neovascularization by upregulation of vascular endothelial growth factor (VEGF) secreted by endothelial cells and vascular smooth muscle cells lining the arterial wall destabilizing the plaque. HIF-knockout animal models and inhibitor studies were able to show beneficial effects on atherogenesis by counteracting the HIF-pathway in the cell wall. In this review the authors elaborate on the up-to-date literature on regulation of cells of the arterial wall through activation of HIF-1α and its effect on atherosclerotic plaque formation.

Hypoxia-Inducible Factor 1 and Preeclampsia: A New Perspective

PURPOSE OF REVIEW

Preeclampsia (PE) is a serious and distinct type of pregnancy-induced hypertension, with an incidence of 2-8% worldwide. PE is defined as pregnancy-related hypertension with proteinuria and peripheral edema after 20 weeks of gestation. Hypoxic placenta triggers the release of inflammatory and humoral substances into maternal circulation, leading to induction of oxidative stress, lipid peroxidation, endothelial dysfunction, and peripheral vasoconstriction. The objective of the present narrative review was to find the association between PE and hypoxia-inducible factor 1 (HIF-1) in pregnant women from a new perspective.

RECENT FINDINGS

HIF-1 is the key transcription factor that regulates cellular responses to hypoxia and low oxygen tension. HIF-1α is involved in the differentiation and growth of the placenta mainly in the first and second trimesters. During normal gestation, HIF-1α responds to the alterations in oxygen tension, cytokine, and angiogenic factors release. HIF-1α is considered a key biomarker of placental function and vascularization during pregnancy. HIF-1α plays a crucial role in the pathogenesis of PE through activation of anti-angiogenic and inhibition of proangiogenic factors. As well, HIF-1α increases the expression of the p38MAPK and NLRP3 inflammasomes, which promote placental inflammation and dysfunction. HIF-1α acts as a potential link between inflammatory signaling pathways and the development of PE.

Metabolomic Profiling and Molecular Networking of Nudibranch-Associated Streptomyces sp. SCSIO 001680

Antibiotic-resistant bacteria are the primary source of one of the growing public health problems that requires global attention, indicating an urgent need for new antibiotics. Marine ecosystems are characterized by high biodiversity and are considered one of the essential sources of bioactive chemical compounds. Bacterial associates of marine invertebrates are commonly a source of active medicinal and natural products and are important sources for drug discovery. Hence, marine invertebrate-associated microbiomes are a fruitful resource for excavating novel genes and bioactive compounds. In a previous study, we isolated Streptomyces sp. SCSIO 001680, coded as strain 63, from the Red Sea nudibranch Chromodoris quadricolor, which exhibited antimicrobial and antitumor activity. In addition, this isolate harbors several natural product biosynthetic gene clusters, suggesting it has the potential to produce bioactive natural products. The present study aimed to investigate the metabolic profile of the isolated Streptomyces sp. SCSIO 001680 (strain 63) and to predict their potential role in the host’s survival. The crude metabolic extracts of strain 63 cultivated in two different media were characterized by ultra-high-performance liquid chromatography and high-resolution mass spectrometry. The metabolomics approach provided us with characteristic chemical fingerprints of the cellular processes and the relative abundance of specific compounds. The Global Products Social Molecular Networking database was used to identify the metabolites. While 434 metabolites were detected in the extracts, only a few compounds were identified based on the standards and the public spectral libraries, including desferrioxamines, marineosin A, and bisucaberin, halichoblelide, alternarin A, pachastrelloside A, streptodepsipeptide P1 1B, didemnaketal F, and alexandrolide. This finding suggests that this strain harbors several novel compounds. In addition, the metabolism of the microbiome of marine invertebrates remains poorly represented. Thus, our data constitute a valuable complement to the study of metabolism in the host microbiome.

Hypoxia signaling in human health and diseases: implications and prospects for therapeutics

Molecular oxygen (O₂) is essential for most biological reactions in mammalian cells. When the intracellular oxygen content decreases, it is called hypoxia. The process of hypoxia is linked to several biological processes, including pathogenic microbe infection, metabolic adaptation, cancer, acute and chronic diseases, and other stress responses. The mechanism underlying cells respond to oxygen changes to mediate subsequent signal response is the central question during hypoxia. Hypoxia-inducible factors (HIFs) sense hypoxia to regulate the expressions of a series of downstream genes expression, which participate in multiple processes including cell metabolism, cell growth/death, cell proliferation, glycolysis, immune response, microbe infection, tumorigenesis, and metastasis. Importantly, hypoxia signaling also interacts with other cellular pathways, such as phosphoinositide 3-kinase (PI3K)-mammalian target of rapamycin (mTOR) signaling, nuclear factor kappa-B (NF-κB) pathway, extracellular signal-regulated kinases (ERK) signaling, and endoplasmic reticulum (ER) stress. This paper systematically reviews the mechanisms of hypoxia signaling activation, the control of HIF signaling, and the function of HIF signaling in human health and diseases. In addition, the therapeutic targets involved in HIF signaling to balance health and diseases are summarized and highlighted, which would provide novel strategies for the design and development of therapeutic drugs.

Deferiprone: A Forty-Year-Old Multi-Targeting Drug with Possible Activity against COVID-19 and Diseases of Similar Symptomatology

The need for preparing new strategies for the design of emergency drug therapies against COVID-19 and similar diseases in the future is rather urgent, considering the high rate of morbidity and especially mortality associated with COVID-19, which so far has exceeded 18 million lives. Such strategies could be conceived by targeting the causes and also the serious toxic side effects of the diseases, as well as associated biochemical and physiological pathways. Deferiprone (L1) is an EMA- and FDA-approved drug used worldwide for the treatment of iron overload and also other conditions where there are no effective treatments. The multi-potent effects and high safety record of L1 in iron loaded and non-iron loaded categories of patients suggests that L1 could be developed as a “magic bullet” drug against COVID-19 and diseases of similar symptomatology. The mode of action of L1 includes antiviral, antimicrobial, antioxidant, anti-hypoxic and anti-ferroptotic effects, iron buffering interactions with transferrin, iron mobilizing effects from ferritin, macrophages and other cells involved in the immune response and hyperinflammation, as well as many other therapeutic interventions. Similarly, several pharmacological and other characteristics of L1, including extensive tissue distribution and low cost of production, increase the prospect of worldwide availability, as well as many other therapeutic approach strategies involving drug combinations, adjuvant therapies and disease prevention.

Induction of Hypoxic Response in Caco-2 Cells Promote the Expression of Genes Involved in SARS-CoV-2 Endocytosis and Transcytosis

In the present manuscript we analyzed the influence of hypoxic response in Caco-2 cells on the expression of genes and miRNAs involved in the mechanisms of intracellular transport of SARS-CoV-2 viral particles, especially endocytosis and transcytosis. With the use of RNA sequencing of Caco-2 cells treated with hypoxia-inducing oxyquinoline derivative, we showed two-fold increase in the expression of the main SARS-CoV-2 receptor ACE2. Expression of the non-canonical receptor TFRC was also elevated. We also observed a significant increase in the expression levels of genes from the low-density lipoprotein (LDL) receptor family, which play a crucial role in the transcytosis: LDLR, LRP1, LRP4, and LRP5. Upregulation of LDLR was coupled with the downregulation of hsa-miR-148a-3p, which can directly bind to LDLR mRNA. Thus, the hypoxic response in Caco-2 cells includes upregulation of genes involved in the mechanisms of endocytosis and transcytosis of SARS-CoV-2 viral particles.

Interplay between hypoxia and inflammation contributes to the progression and severity of respiratory viral diseases

History of pandemics is dominated by viral infections and specifically respiratory viral diseases like influenza and COVID-19. Lower respiratory tract infection is the fourth leading cause of death worldwide. Crosstalk between resultant inflammation and hypoxic microenvironment may impair ventilatory response of lungs. This reduces arterial partial pressure of oxygen, termed as hypoxemia, which is observed in a section of patients with respiratory virus infections including SARS-CoV-2 (COVID-19). In this review, we describe the interplay between inflammation and hypoxic microenvironment in respiratory viral infection and its contribution to disease pathogenesis.

Hypoxia reduces cell attachment of SARS-CoV-2 spike protein by modulating the expression of ACE2, neuropilin-1, syndecan-1 and cellular heparan sulfate

A main clinical parameter of COVID-19 pathophysiology is hypoxia. Here we show that hypoxia decreases the attachment of the receptor-binding domain (RBD) and the S1 subunit (S1) of the spike protein of SARS-CoV-2 to epithelial cells. In Vero E6 cells, hypoxia reduces the protein levels of ACE2 and neuropilin-1 (NRP1), which might in part explain the observed reduction of the infection rate. In addition, hypoxia inhibits the binding of the spike to NCI-H460 human lung epithelial cells by decreasing the cell surface levels of heparan sulfate (HS), a known attachment receptor of SARS-CoV-2. This interaction is also reduced by lactoferrin, a glycoprotein that blocks HS moieties on the cell surface. The expression of syndecan-1, an HS-containing proteoglycan expressed in lung, is inhibited by hypoxia on a HIF-1α-dependent manner. Hypoxia or deletion of syndecan-1 results in reduced binding of the RBD to host cells. Our study indicates that hypoxia acts to prevent SARS-CoV-2 infection, suggesting that the hypoxia signalling pathway might offer therapeutic opportunities for the treatment of COVID-19.