Impact of Hypoxia over Human Viral Infections and Key Cellular Processes

Hypoxia-inducible-factors differentially contribute to clinical disease and viral replication during RSV infection

Hypoxia-inducible-factors (HIF) are transcription factors that regulate cellular adaptation to hypoxic conditions, enabling cells to survive in low-oxygen environments. Viruses have evolved to activate this pathway to promote successful viral infection, therefore modulation of HIFs could represent a novel antiviral strategy. In previous in vitro studies, we found that respiratory syncytial virus (RSV), a leading cause of respiratory illness, stabilizes HIFs under normoxic conditions, with inhibition of HIF-1α resulting in reduced viral replication. Despite several HIF modulating compounds being tested/approved for use in other non-infectious models, little is known about their efficacy against respiratory viruses using relevant animal models. This study aimed to characterize the disease modulating properties and antiviral potential of HIF-1α (PX478) and HIF-2α (PT2385) inhibitors in RSV-infected BALB/c mice. We found that inhibition of HIF-1α worsen clinical disease parameters, while simultaneously improving lung inflammation and airway function. Additionally, blocking HIF-1α resulted in significantly reduced viral titer at early and peak time points of RSV replication. In contrast, inhibition of HIF-2α was associated with improved clinical parameters, with no changes in airway function, enhanced immune responses and reduced early and peak lung viral replication. Analysis of lung cells found significant modification in the T-cell compartment that correlated with changes in lung pathology and viral titers in response to each HIF inhibitor administration. This study underscores the differential roles of HIF proteins in RSV infection and highlights the need for further characterization of the compounds that are currently in use or under therapeutic consideration.

Biomolecular Dynamics of Nitric Oxide Metabolites and HIF1α in HPV Infection

INTRODUCTION

Viral infections cause oxygen deprivation, leading to hypoxia or anoxia in certain tissues. The limitation of mitochondrial respiration is one of the major events during hypoxia that induces alternative metabolic activities and increased levels of certain biomolecules such as nitric oxide (NO) metabolites. In this study, we aimed to investigate the role of NO metabolites and hypoxia in HPV infection.

MATERIALS AND METHODS

We included 36 patients with palmoplantar warts and 36 healthy subjects and performed serum determinations of NO metabolites (direct nitrite, total nitrite, nitrate, and 3-nitrotyrosine) and HIF1α, a marker of hypoxia.

RESULTS

We found elevated serum levels in NO metabolites and HIF1α, and decreased direct nitrite/nitrate ratios in patients with warts versus controls. Additionally, we identified statistically significant positive correlations between NO metabolites and HIF1α levels, except for 3-nitrotyrosine.

CONCLUSIONS

Our findings show that HPV infection causes hypoxia and alterations in NO metabolism and suggest a link between wart development and cellular stress. Our research could provide new insights for a comprehensive understanding of the pathogenesis of cutaneous HPV infections.

Interplay between lipid metabolism, lipid droplets and RNA virus replication

Lipids play essential roles in the cell as components of cellular membranes, signaling molecules, and energy storage sources. Lipid droplets are cellular organelles composed of neutral lipids, such as triglycerides and cholesterol esters, and are also considered as cellular energy reserves, yet new functions have been recently associated with these structures, such as regulators of oxidative stress and cellular lipotoxicity, as well as modulators of pathogen infection through immune regulation. Lipid metabolism and lipid droplets participate in the infection process of many RNA viruses and control their replication and assembly, among others. Here, we review and discuss the contribution of lipid metabolism and lipid droplets over the replication cycle of RNA viruses, altogether pointing out potentially new pharmacological antiviral targets associated with lipid metabolism.

Live Microscopy of Multicellular Spheroids with the Multimodal Near-Infrared Nanoparticles Reveals Differences in Oxygenation Gradients

Assessment of hypoxia, nutrients, metabolite gradients, and other hallmarks of the tumor microenvironment within 3D multicellular spheroid and organoid models represents a challenging analytical task. Here, we report red/near-infrared (NIR) emitting cell staining with O2-sensitive nanoparticles, which enable measurements of spheroid oxygenation on a conventional fluorescence microscope. Nanosensor probes, termed "MMIR" (multimodal infrared), incorporate an NIR O2-sensitive metalloporphyrin (PtTPTBPF) and deep red aza-BODIPY reference dyes within a biocompatible polymer shell, allowing for oxygen gradient quantification via fluorescence ratio and phosphorescence lifetime readouts. We optimized staining techniques and evaluated the nanosensor probe characteristics and cytotoxicity. Subsequently, we applied nanosensors to the live spheroid models based on HCT116, DPSCs, and SKOV3 cells, at rest, and treated with drugs affecting cell respiration. We found that the growth medium viscosity, spheroid size, and formation method influenced spheroid oxygenation. Some spheroids produced from HCT116 and dental pulp stem cells exhibited "inverted" oxygenation gradients, with higher core oxygen levels than the periphery. This contrasted with the frequently encountered "normal" gradient of hypoxia toward the core caused by diffusion. Further microscopy analysis of spheroids with an "inverted" gradient demonstrated metabolic stratification of cells within spheroids: thus, autofluorescence FLIM of NAD(P)H indicated the formation of a glycolytic core and localization of OxPhos-active cells at the periphery. Collectively, we demonstrate a strong potential of NIR-emitting ratiometric nanosensors for advanced microscopy studies targeting live and quantitative real-time monitoring of cell metabolism and hypoxia in complex 3D tissue models.

The Hybrid of Cu─TCPP@Mn3 O4 for Inflammation Relief by ROS Scavenging and O2 Production: An Efficient Strategy for Antiviral Therapy

Seasonal influenza still greatly threatens public health worldwide, leading to significant morbidity and mortality. Antiviral medications for influenza treatment are limited and accompanied by increased drug resistance. In severe influenza virus infection, hyperinflammation and hypoxia may be the significant threats associated with mortality, so the development of effective therapeutic methods to alleviate excessive inflammation while reducing viral damage is highly pursued. Here, a multifunctional MOF-based nanohybrid of Cu─TCPP@Mn3 O4 as a novel drug against influenza A virus infection (MOF = metal-organic framework; TCPP = tetrakis (4-carboxyphenyl) porphyrin) is designed. Cu─TCPP@Mn3 O4 exhibits potent inhibitory capability against influenza A virus infection in vitro and in vivo. The mechanism study reveals that Cu─TCPP@Mn3 O4 inhibits the virus entry by binding to the HA2 subunit of influenza A virus hemagglutinin. In addition, the nanoparticles of Mn3 O4 in Cu─TCPP@Mn3 O4 can scavenge intracellular ROS with O2 generation to downregulate inflammatory factors and effectively inhibit cytokines production. By reconstructing the antioxidant microenvironment, Cu─TCPP@Mn3 O4 features as a promising nanomedicine with anti-inflammatory and anti-viral synergistic effects.

Hepatitis B Virus-Encoded MicroRNA (HBV-miR-3) Inhibits FIH-1 Expression to Promote Tumor Angiogenesis in HBV-Related Hepatocellular Carcinoma

Introduction

Hepatocellular carcinoma (HCC) is a solid tumor with a rich blood supply, and anti-angiogenesis has important clinical significance. Hepatitis B Virus-Encoded MicroRNA 3 (HBV-miR-3) has recently been reported to be involved in HCC development. In this study, we aim to elucidate the role of HBV-miR-3 in promoting HBV-related HCC angiogenesis through Factor Inhibiting Hypoxia-inducible factor 1 (FIH-1).

Results

By analyzing HBV-related HCC tissue samples, we found that high expression of HBV-miR-3 was associated with poor overall survival and HBV-miR-3 expression was significantly correlated with VEGFR2 and FIH-1 expressions. In vitro, HBV-miR-3 agomir repressed FIH-1 expression and promoted HIF-1α/VEGFA signaling activation in HepG2 cells, resulting in increased HUVEC lumen formation in HepG2-HUVEC co-culture model. Conversely, HBV-miR-3 antagomir induced FIH-1 expression and inhibited HIF-1α/VEGFA signaling activation in HepG2.2.15 cells, resulting in decreased HUVEC lumen formation in HepG2.2.15-HUVEC co-culture model. The effect of HBV-miR-3 to HCC angiogenesis was also confirmed by a mouse tumor bearing model. We also confirmed that HBV-miR-3 repressed FIH-1 expression via targeting the 3'-UTR of FIH-1 mRNA by luciferase activity assay.

Conclusion

HBV-miR-3 was related to HCC patients' overall survival and it promoted angiogenesis by repressing FIH-1 expression. HBV-miR-3 may be a new marker for predicting prognosis and a novel target for anti-angiogenic treatment of HBV-related HCC.

Hypoxia modifies levels of the SARS-CoV-2 cell entry proteins, angiotensin-converting enzyme 2, and furin in fetal human brain endothelial cells

BACKGROUND

It is not known whether human fetal brain endothelial cells that form the blood-brain barrier express angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin, which are SARS-CoV-2 cell entry proteins. Moreover, it is unclear whether hypoxia, commonly observed during severe maternal COVID-19, can modify their level of expression. We hypothesized that human fetal brain endothelial cells isolated from early- and midpregnancy brain microvessels express angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin. Furthermore, we hypothesized that hypoxia modifies their expression levels in a gestational age- and time-of-exposure-dependent manner.

OBJECTIVE

This study aimed to investigate whether early- and midpregnancy human fetal brain endothelial cells express angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin SARS-CoV-2-associated cell entry proteins and to determine the effects of hypoxia on angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin expression levels in human fetal brain endothelial cells.

STUDY DESIGN

This was a prospective study where human fetal brain endothelial cells isolated from early-pregnancy (12.4±0.7 weeks of gestation) and midpregnancy (17.9±0.5 weeks of gestation) fetal brain microvessels (6 per group) were exposed to different oxygen tensions (20%, 5%, and 1% oxygen) for 6, 24, and 48 hours. Angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin messenger RNA and protein levels and localization were assessed using quantitative polymerase chain reaction, Western blot testing, and immunofluorescence.

RESULTS

Angiotensin-converting enzyme 2, transmembrane serine protease 2, and furin co-localize with the endothelial cell marker von Willebrand factor in human fetal brain endothelial cells isolated from early pregnancy and midpregnancy. In early pregnancy, TMPRSS2 messenger RNA expression was decreased by 5% oxygen compared with 20% oxygen after 6 hours of exposure (P<.05). In midpregnancy, 5% oxygen down-regulated ACE2 messenger RNA compared with 20% oxygen after 24 hours (P<.05). Furin messenger RNA expression was decreased under 5% and 1% oxygen compared with 20% oxygen (P<.05) after 24 hours. In midpregnancy, angiotensin-converting enzyme 2 protein levels were decreased under 5% and 1% oxygen (P<.001) after 24 hours. In contrast, furin protein levels were increased under 1% oxygen compared with 20% oxygen after 24 hours (P<.05). At 48 hours, 1% oxygen increased angiotensin-converting enzyme 2 protein levels compared with 20% oxygen (P<.01).

CONCLUSION

Hypoxia modifies the expression of selected SARS-CoV-2 cell entry proteins in human fetal brain endothelial cells in a gestational age- and time-of-exposure-dependent manner. As severe COVID-19 may lead to maternal hypoxia, an altered expression of these proteins in the developing human blood-brain barrier could potentially lead to altered SARS-CoV-2 brain invasion and neurologic sequelae in neonates born to pregnancies complicated by SARS-CoV-2 infection.

Contribution of carbohydrate-related metabolism in Herpesvirus infections

Human herpesviruses are enveloped viruses with double-stranded linear DNA genomes highly prevalent in the human population. These viruses are subdivided into three subfamilies, namely alphaherpesvirinae (herpes simplex virus type 1, HSV-1; herpes simplex virus type 2, HSV-2; and varicella-zoster virus, VZV), betaherpesvirinae (human cytomegalovirus, HCMV; human herpesvirus 6, HHV-6; and human herpesvirus 7, HHV-7) and gammaherpesvirinae (Epstein-Barr virus, EBV; and Kaposi's sarcoma-associated herpesvirus, KSHV). Besides encoding numerous molecular determinants to evade the host antiviral responses, these viruses also modulate cellular metabolic processes to promote their replication. Here, we review and discuss existing studies describing an interplay between carbohydrate metabolism and the replication cycle of herpesviruses, altogether highlighting potentially new molecular targets based on these interactions that could be used to block herpesvirus infections.

Immunomodulatory activity of manganese dioxide nanoparticles: Promising for novel vaccines and immunotherapeutics

Manganese (Mn), a nutrient inorganic trace element, is necessary for a variety of physiological processes of animal body due to their important roles in oxidative regulation effects and other aspects of activities. Moreover, manganese ion (Mn²⁺) has widely reported to be crucial for the regulations of different immunological responses, thus showing promising application as potential adjuvants and immunotherapeutics. Taking the advantages of Mn-based biological and immunological activities, Manganese dioxide nanoparticles (MnO₂ NPs) are a new type of inorganic nanomaterials with numerous advantages, including simple preparation, low cost, environmental friendliness, low toxicity, biodegradable metabolism and high bioavailability. MnO₂ NPs, as a kind of drug carrier, have also shown the ability to catalyze hydrogen peroxide (H₂O₂) to produce oxygen (O₂) under acidic conditions, which can enhance the efficacy of radiotherapy, chemotherapy and other therapeutics for tumor treatment by remodeling the tumor microenvironment. More importantly, MnO₂ NPs also play important roles in immune regulations both in innate and adaptive immunity. In this review, we summarize the biological activities of Manganese, followed by the introduction for the biological and medical functions and mechanisms of MnO₂ NPs. What's more, we emphatically discussed the immunological regulation effects and mechanisms of MnO₂ NPs, as well as their potentials to serve as adjuvants and immunomodulators, which might benefit the development of novel vaccines and immunotherapies for more effective disease control.

Interplay between Lipid Metabolism, Lipid Droplets, and DNA Virus Infections

Lipid droplets (LDs) are cellular organelles rich in neutral lipids such as triglycerides and cholesterol esters that are coated by a phospholipid monolayer and associated proteins. LDs are known to play important roles in the storage and availability of lipids in the cell and to serve as a source of energy reserve for the cell. However, these structures have also been related to oxidative stress, reticular stress responses, and reduced antigen presentation to T cells. Importantly, LDs are also known to modulate viral infection by participating in virus replication and assembly. Here, we review and discuss the interplay between neutral lipid metabolism and LDs in the replication cycle of different DNA viruses, identifying potentially new molecular targets for the treatment of viral infections.

Hypoxia triggers the outbreak of infectious spleen and kidney necrosis virus disease through viral hypoxia response elements

Hypoxia frequently occurs in aquatic environments, especially in aquaculture areas. However, research on the relationship between hypoxic aquatic environments with viral diseases outbreak is limited, and its underlying mechanisms remain elusive. Herein, we demonstrated that hypoxia directly triggers the outbreak of infectious spleen and kidney necrosis virus (ISKNV) disease. Hypoxia or activated hypoxia-inducible factor (HIF) pathway could remarkably increase the levels of viral genomic DNA, titers, and gene expression, indicating that ISKNV can response to hypoxia and HIF pathway. To reveal the mechanism of ISKNV respond to HIF pathway, we identified the viral hypoxia response elements (HREs) in ISKNV genome. Fifteen viral HREs were identified, and four related viral genes responded to the HIF pathway, in which the hre-orf077r promoter remarkably responded to the HIF pathway. The level of orf077r mRNA dramatically increased after the infected cells were treated with dimethyloxalylglycine (DMOG) or the infected cells/fish subjected to hypoxic conditions, and overexpressed orf077r could remarkably increase the ISKNV replication. These finding shows that hypoxic aquatic environments induce the expression of viral genes through the viral HREs to promote ISKNV replication, indicating that viral HREs might be important biomarkers for the evaluation of the sensitivity of aquatic animal viral response to hypoxia stress. Furthermore, the frequencies of viral HREs in 43 species aquatic viral genomes from 16 families were predicted and the results indicate that some aquatic animal viruses, such as Picornavirdea, Dicistronviridae, and Herpesviridae, may have a high risk to outbreak when the aquatic environment encounters hypoxic stress.