NADPH oxidases: an overview from structure to innate immunity-associated pathologies

G6PD deficiency mediated impairment of iNOS and lysosomal acidification affecting phagocytotic clearance in microglia in response to SARS-CoV-2

The glucose-6-phosphate dehydrogenase (G6PD) deficiency is X-linked and is the most common enzymatic deficiency disorder globally. It is a crucial enzyme for the pentose phosphate pathway and produces NADPH, which plays a vital role in regulating the oxidative stress of many cell types. The deficiency of G6PD primarily causes hemolytic anemia under oxidative stress triggered by food, drugs, or infection. G6PD-deficient patients infected with SARS-CoV-2 showed an increase in hemolysis and thrombosis. Patients also exhibited prolonged COVID-19 symptoms, ventilation support, neurological impacts, and high mortality. However, the mechanism of COVID-19 severity in G6PD deficient patients and its neurological manifestation is still ambiguous. Here, using a CRISPR-edited G6PD deficient human microglia cell culture model, we observed a significant reduction in NADPH level and an increase in basal reactive oxygen species (ROS) in microglia. Interestingly, the deficiency of the G6PD-NAPDH axis impairs induced nitric oxide synthase (iNOS) mediated nitric oxide (NO) production, which plays a fundamental role in inhibiting viral replication. Surprisingly, we also observed that the deficiency of the G6PD-NADPH axis reduced lysosomal acidification and free radical production, further abrogating the lysosomal clearance of viral particles. Thus, impairment of NO production, lysosomal functions, and redox dysregulation in G6PD deficient microglia altered innate immune response, promoting the severity of SARS-CoV-2 pathogenesis.

Mechanisms of doxorubicin-induced cardiac inflammation and fibrosis; therapeutic targets and approaches

Doxorubicin plays a pivotal role in the treatment of various malignancies. Despite its efficacy, the cardiotoxicity associated with doxorubicin limits its clinical utility. The cardiotoxic nature of doxorubicin is attributed to several mechanisms, including its interference with mitochondrial function, the generation of reactive oxygen species (ROS), and the subsequent damage to cardiomyocyte DNA, proteins, and lipids. Furthermore, doxorubicin disrupts the homeostasis of cardiac-specific transcription factors and signaling pathways, exacerbating cardiac dysfunction. Oxidative stress, cell death, and other severe changes, such as mitochondrial dysfunction, activation of pro-oxidant enzymes, the renin-angiotensin system (RAS), endoplasmic reticulum (ER) stress, and infiltration of immune cells in the heart after treatment with doxorubicin, may cause inflammatory and fibrotic responses. Fibrosis and inflammation can lead to a range of disorders in the heart, resulting in potential cardiac dysfunction and disease. Various adjuvants have shown potential in preclinical studies to mitigate these challenges associated with cardiac inflammation and fibrosis. Antioxidants, plant-based products, specific inhibitors, and cardioprotective drugs may be recommended to alleviate cardiotoxicity. This review explores the complex mechanisms of doxorubicin-induced heart inflammation and fibrosis, identifies possible cellular and molecular targets, and investigates potential substances that could help reduce these harmful effects.

The complex interplay between ferroptosis and atherosclerosis

Atherosclerosis, characterized by the accumulation of plaque within the arterial walls, is an intricate cardiovascular disease that often results in severe health issues. Recent studies have emphasized the importance of ferroptosis, a controlled type of cell death dependent on iron, as a critical factor in this disease state. Ferroptosis, distinguished by its reliance on iron and the accumulation of lipid hydroperoxides, offers a unique insight into the pathology of atherosclerotic lesions. This summary encapsulates the current knowledge of the intricate role ferroptosis plays in the onset and progression of atherosclerosis. It explores the molecular processes through which lipid peroxidation and iron metabolism contribute to the development of atheromatous plaques and evaluates the possibility of utilizing ferroptosis as a novel treatment approach for atherosclerosis. By illuminating the intricate relationship between ferroptosis-related processes and atherosclerosis, this review paves the way for future clinical applications and personalized medicine approaches aimed at alleviating the effects of atherosclerosis.

NADPH oxidase 4 (NOX4) as a biomarker and therapeutic target in neurodegenerative diseases

Diseases like Alzheimer's and Parkinson's diseases are defined by inflammation and the damage neurons undergo due to oxidative stress. A primary reactive oxygen species contributor in the central nervous system, NADPH oxidase 4, is viewed as a potential therapeutic touchstone and indicative marker for these ailments. This in-depth review brings to light distinct features of NADPH oxidase 4, responsible for generating superoxide and hydrogen peroxide, emphasizing its pivotal role in activating glial cells, inciting inflammation, and disturbing neuronal functions. Significantly, malfunctioning astrocytes, forming the majority in the central nervous system, play a part in advancing neurodegenerative diseases, due to their reactive oxygen species and inflammatory factor secretion. Our study reveals that aiming at NADPH oxidase 4 within astrocytes could be a viable treatment pathway to reduce oxidative damage and halt neurodegenerative processes. Adjusting NADPH oxidase 4 activity might influence the neuroinflammatory cytokine levels, including myeloperoxidase and osteopontin, offering better prospects for conditions like Alzheimer's disease and Parkinson's disease. This review sheds light on the role of NADPH oxidase 4 in neural degeneration, emphasizing its drug target potential, and paving the path for novel treatment approaches to combat these severe conditions.

Homeostatic regulation of NAD(H) and NADP(H) in cells

Nicotinamide adenine dinucleotide (NAD+)/reduced NAD+ (NADH) and nicotinamide adenine dinucleotide phosphate (NADP+)/reduced NADP+ (NADPH) are essential metabolites involved in multiple metabolic pathways and cellular processes. NAD+ and NADH redox couple plays a vital role in catabolic redox reactions, while NADPH is crucial for cellular anabolism and antioxidant responses. Maintaining NAD(H) and NADP(H) homeostasis is crucial for normal physiological activity and is tightly regulated through various mechanisms, such as biosynthesis, consumption, recycling, and conversion between NAD(H) and NADP(H). The conversions between NAD(H) and NADP(H) are controlled by NAD kinases (NADKs) and NADP(H) phosphatases [specifically, metazoan SpoT homolog-1 (MESH1) and nocturnin (NOCT)]. NADKs facilitate the synthesis of NADP+ from NAD+, while MESH1 and NOCT convert NADP(H) into NAD(H). In this review, we summarize the physiological roles of NAD(H) and NADP(H) and discuss the regulatory mechanisms governing NAD(H) and NADP(H) homeostasis in three key aspects: the transcriptional and posttranslational regulation of NADKs, the role of MESH1 and NOCT in maintaining NAD(H) and NADP(H) homeostasis, and the influence of the circadian clock on NAD(H) and NADP(H) homeostasis. In conclusion, NADKs, MESH1, and NOCT are integral to various cellular processes, regulating NAD(H) and NADP(H) homeostasis. Dysregulation of these enzymes results in various human diseases, such as cancers and metabolic disorders. Hence, strategies aiming to restore NAD(H) and NADP(H) homeostasis hold promise as novel therapeutic approaches for these diseases.

Crosstalk between ROS-inflammatory gene expression axis in the progression of lung disorders

A significant number of deaths and disabilities worldwide are brought on by inflammatory lung diseases. Many inflammatory lung disorders, including chronic respiratory emphysema, resistant asthma, resistance to steroids, and coronavirus-infected lung infections, have severe variants for which there are no viable treatments; as a result, new treatment alternatives are needed. Here, we emphasize how oxidative imbalance contributes to the emergence of provocative lung problems that are challenging to treat. Endogenic antioxidant systems are not enough to avert free radical-mediated damage due to the induced overproduction of ROS. Pro-inflammatory mediators are then produced due to intracellular signaling events, which can harm the tissue and worsen the inflammatory response. Overproduction of ROS causes oxidative stress, which causes lung damage and various disease conditions. Invasive microorganisms or hazardous substances that are inhaled repeatedly can cause an excessive amount of ROS to be produced. By starting signal transduction pathways, increased ROS generation during inflammation may cause recurrent DNA damage and apoptosis and activate proto-oncogenes. This review provides information about new targets for conducting research in related domains or target factors to prevent, control, or treat such inflammatory oxidative stress-induced inflammatory lung disorders.

Regulation of NLRPs by reactive oxygen species: A story of crosstalk

The nucleotide oligomerization domain (NOD)-like receptors containing pyrin (NLRP) family of cytosolic pattern-recognition receptors play an integral role in host defense following exposure to a diverse set of pathogenic and sterile threats. The canonical event following ligand recognition is the formation of a heterooligomeric signaling complex termed the inflammasome that produces pro-inflammatory cytokines. Dysregulation of this process is associated with many autoimmune, cardiovascular, metabolic, and neurodegenerative diseases. Despite the range of activating stimuli which affect varied cell types, recent literature makes evident that reactive oxygen species (ROS) are integral to the initiation and propagation of inflammasome signaling. Notably, ROS production and inflammasome activation act in a positive feedback loop to promote this potent immune response. While NLRP3 is by far the most extensively studied NLRP, there is also sufficient literature to make these conclusions for other NLRPs family members. In all cases, a knowledge gap exists regarding the molecular targets and effects of ROS. Future research to define these targets and to parse the order and timing of ROS-mediated NLRP activation will provide meaningful insights into inflammasome biology. This will create novel therapeutic opportunities for the numerous illnesses that are impacted by inflammasome activity.

The KEAP1/PGAM5/AIFM1-Mediated oxeiptosis pathway in Alzheimer's disease

BACKGROUND

Alzheimer's Disease (AD) is a neurodegenerative disease with mitochondrial dysfunction and oxidative stress. Oxeiptosis is a cell death pathway sensitive to reactive oxygen species (ROS). This study investigates the role of oxeiptosis pathway and mitochondrial damage in AD.

METHODS

An AD model was developed in C57BL/6 mice by injecting Aβ1-42 oligomers into the brain. Cognitive function was tested using the Morris water maze. Exposure of HT22 mouse hippocampal neurons to H2O2 induces oxidative stress. Protein levels of KEAP1, PGAM5 and AIFM1 were analyzed by western blot, and mitochondrial damage was observed with electron microscopy. Cell survival rates were using the CCK8 assay and flow cytometry after knocking down KEAP1, PGAM5 and AIFM1.

RESULTS

The protein concentrations of KEAP1, PGAM5 and AIFM1 were found to be elevated in the hippocampal tissues of AD mice compared to control group, accompanied by mitochondrial damage in the hippocampal neurons of the AD group. Similarly, in the HT22 oxidative stress model, there was an increase in the protein levels of KEAP1, PGAM5 and AIFM1, along with observed mitochondrial damage. Following individual and combined knockdown of KEAP1, PGAM5 and AIFM1, cell survival rates under oxidative stress conditions were higher compared to H2O2 group, with no significant difference in cell survival rates among the knockdown groups.

CONCLUSION

This research underscores the critical role of the KEAP1/PGAM5/AIFM1-mediated oxeiptosis pathway in neuronal cell death, offering insights into potential therapeutic targets for mitigating neurodegeneration in AD.

Advancements in rheumatoid arthritis therapy: a journey from conventional therapy to precision medicine via nanoparticles targeting immune cells

Rheumatoid arthritis (RA) is a progressive autoimmune disease that mainly affects the inner lining of the synovial joints and leads to chronic inflammation. While RA is not known as lethal, recent research indicates that it may be a silent killer because of its strong association with an increased risk of chronic lung and heart diseases. Patients develop these systemic consequences due to the regular uptake of heavy drugs such as disease-modifying antirheumatic medications (DMARDs), glucocorticoids (GCs), nonsteroidal anti-inflammatory medicines (NSAIDs), etc. Nevertheless, a number of these medications have off-target effects, which might cause adverse toxicity, and have started to become resistant in patients as well. Therefore, alternative and promising therapeutic techniques must be explored and adopted, such as post-translational modification inhibitors (like protein arginine deiminase inhibitors), RNA interference by siRNA, epigenetic drugs, peptide therapy, etc., specifically in macrophages, neutrophils, Treg cells and dendritic cells (DCs). As the target cells are specific, ensuring targeted delivery is also equally important, which can be achieved with the advent of nanotechnology. Furthermore, these nanocarriers have fewer off-site side effects, enable drug combinations, and allow for lower drug dosages. Among the nanoparticles that can be used for targeting, there are both inorganic and organic nanomaterials such as solid-lipid nanoparticles, liposomes, hydrogels, dendrimers, and biomimetics that have been discussed. This review highlights contemporary therapy options targeting macrophages, neutrophils, Treg cells, and DCs and explores the application of diverse nanotechnological techniques to enhance precision RA therapies.

Permissive lung neutrophils facilitate tuberculosis immunopathogenesis in male phagocyte NADPH oxidase-deficient mice

NADPH oxidase 2 (NOX2) is an enzyme responsible for generating reactive oxygen species, primarily found in phagocytes. Chronic Granulomatous Disease (CGD), along with bacterial infections such as Mycobacterium tuberculosis (Mtb), is a representative NOX2-deficient X-linked disease characterized by uncontrolled inflammation. However, the precise roles of host-derived factors that induce infection-mediated hyperinflammation in NOX2-deficient condition remain incompletely understood. To address this, we compared Mtb-induced pathogenesis in Nox2-/- and wild type (WT) mice in a sex-dependent manner. Among age- and sex-matched mice subjected to Mtb infection, male Nox2-/- mice exhibited a notable increase in bacterial burden and lung inflammation. This was characterized by significantly elevated pro-inflammatory cytokines such as G-CSF, TNF-α, IL-1α, IL-1β, and IL-6, excessive neutrophil infiltration, and reduced pulmonary lymphocyte levels as tuberculosis (TB) progressed. Notably, lungs of male Nox2-/- mice were predominantly populated with CD11bintLy6GintCXCR2loCD62Llo immature neutrophils which featured mycobacterial permissiveness. By diminishing total lung neutrophils or reducing immature neutrophils, TB immunopathogenesis was notably abrogated in male Nox2-/- mice. Ultimately, we identified G-CSF as the pivotal trigger that exacerbates the generation of immature permissive neutrophils, leading to TB immunopathogenesis in male Nox2-/- mice. In contrast, neutralizing IL-1α and IL-1β, which are previously known factors responsible for TB pathogenesis in Nox2-/- mice, aggravated TB immunopathogenesis. Our study revealed that G-CSF-driven immature and permissive pulmonary neutrophils are the primary cause of TB immunopathogenesis and lung hyperinflammation in male Nox2-/- mice. This highlights the importance of quantitative and qualitative control of pulmonary neutrophils to alleviate TB progression in a phagocyte oxidase-deficient condition.

Neutrophil extracellular traps in cancer

Neutrophil extracellular traps (NETs), which consist of chromatin DNA studded with granule proteins, are released by neutrophils in response to both infectious and sterile inflammation. Beyond the canonical role in defense against pathogens, the extrusion of NETs also contributes to the initiation, metastasis, and therapeutic response of malignant diseases. Recently, NETs have been implicated in the development and therapeutic responses of various types of tumors. Although extensive work regarding inflammation in tumors has been reported, a comprehensive summary of how these web-like extracellular structures initiate and propagate tumor progression under the specific microenvironment is lacking. In this review, we demonstrate the initiators and related signaling pathways that trigger NETs formation in cancers. Additionally, this review will outline the current molecular mechanisms and regulatory networks of NETs during dormant cancer cells awakening, circulating tumor cells (CTCs) extravasation, and metastatic recurrence of cancer. This is followed by a perspective on the current and potential clinical potential of NETs as therapeutic targets in the treatment of both local and metastatic disease, including the improvement of the efficacy of existing therapies.

Role of PE/PPE proteins of Mycobacterium tuberculosis in triad of host mitochondria, oxidative stress and cell death

The PE and PPE family proteins of Mycobacterium tuberculosis (Mtb) is exclusively found in pathogenic Mycobacterium species, comprising approximately 8-10 % of the Mtb genome. These emerging virulent factors have been observed to play pivotal roles in Mtb pathogenesis and immune evasion through various strategies. These immunogenic proteins are known to modulate the host immune response and cell-death pathways by targeting the powerhouse of the cell, the mitochondria to support Mtb survival. In this article, we are focused on how PE/PPE family proteins target host mitochondria to induce mitochondrial perturbations, modulate the levels of cellular ROS (Reactive oxygen species) and control cell death pathways. We observed that the time of expression of these proteins at different stages of infection is crucial for elucidating their impact on the cell death pathways and eventually on the outcome of infection. This article focuses on understanding the contributions of the PE/PPE proteins by unravelling the triad of host mitochondria, oxidative stress and cell death pathways that facilitate the Mtb persistence. Understanding the role of these proteins in host cellular pathways and the intricate mechanisms paves the way for the development of novel therapeutic strategies to combat TB infections.

Role of biomarkers and molecular signaling pathways in acute lung injury

BACKGROUND

Acute lung injury (ALI) is caused by bacterial, fungal, and viral infections. When pathogens invade the lungs, the immune system responds by producing cytokines, chemokines, and interferons to promote the infiltration of phagocytic cells, which are essential for pathogen clearance. Their excess production causes an overactive immune response and a pathological hyper-inflammatory state, which leads to ALI. Until now, there is no particular pharmaceutical treatment available for ALI despite known inflammatory mediators like neutrophil extracellular traps (NETs) and reactive oxygen species (ROS).

OBJECTIVES

Therefore, the primary objective of this review is to provide the clear overview on the mechanisms controlling NETs, ROS formation, and other relevant processes during the pathogenesis of ALI. In addition, we have discussed the significance of epithelial and endothelial damage indicators and several molecular signaling pathways associated with ALI.

METHODS

The literature review was done from Web of Science, Scopus, PubMed, and Google Scholar for ALI, NETs, ROS, inflammation, biomarkers, Toll- and nucleotide-binding oligomerization domain (NOD)-like receptors, alveolar damage, pro-inflammatory cytokines, and epithelial/endothelial damage alone or in combination.

RESULTS

This review summarized the main clinical signs of ALI, including the regulation and distinct function of epithelial and endothelial biomarkers, NETs, ROS, and pattern recognition receptors (PRRs).

CONCLUSION

However, no particular drugs including vaccine for ALI has been established. Furthermore, there is a lack of validated diagnostic tools and a poor predictive rationality of current therapeutic biomarkers. Hence, extensive and precise research is required to speed up the process of drug testing and development by the application of artificial intelligence technologies, structure-based drug design, in-silico approaches, and drug repurposing.

EGFR-MEK1/2 cascade negatively regulates bactericidal function of bone marrow macrophages in mice with Staphylococcus aureus osteomyelitis

The ability of Staphylococcus aureus (S. aureus) to survive within macrophages is a critical strategy for immune evasion, contributing to the pathogenesis and progression of osteomyelitis. However, the underlying mechanisms remain poorly characterized. This study discovered that inhibiting the MEK1/2 pathway reduced bacterial load and mitigated bone destruction in a mouse model of S. aureus osteomyelitis. Histological staining revealed increased phosphorylated MEK1/2 levels in bone marrow macrophages surrounding abscess in the mouse model of S. aureus osteomyelitis. Activation of MEK1/2 pathway and its roles in impairing macrophage bactericidal function were confirmed in primary mouse bone marrow-derived macrophages (BMDMs). Transcriptome analysis and in vitro experiments demonstrated that S. aureus activates the MEK1/2 pathway through EGFR signaling. Moreover, we found that excessive activation of EGFR-MEK1/2 cascade downregulates mitochondrial reactive oxygen species (mtROS) levels by suppressing Chek2 expression, thereby impairing macrophage bactericidal function. Furthermore, pharmacological inhibition of EGFR signaling prevented upregulation of phosphorylated MEK1/2 and restored Chek2 expression in macrophages, significantly enhancing S. aureus clearance and improving bone microstructure in vivo. These findings highlight the critical role of the EGFR-MEK1/2 cascade in host immune defense against S. aureus, suggesting that S. aureus may reduce mtROS levels by overactivating the EGFR-MEK1/2 cascade, thereby suppressing macrophage bactericidal function. Therefore, combining EGFR-MEK1/2 pathway blockade with antibiotics could represent an effective therapeutic approach for the treatment of S. aureus osteomyelitis.

High-Altitude Medicinal Plants as Promising Source of Phytochemical Antioxidants to Combat Lifestyle-Associated Oxidative Stress-Induced Disorders

Oxidative stress, driven by reactive oxygen, nitrogen, and sulphur species (ROS, RNS, RSS), poses a significant threat to cellular integrity and human health. Generated during mitochondrial respiration, inflammation, UV exposure and pollution, these species damage cells and contribute to pathologies like cardiovascular issues, neurodegeneration, cancer, and metabolic syndromes. Lifestyle factors exert a substantial influence on oxidative stress levels, with mitochondria emerging as pivotal players in ROS generation and cellular equilibrium. Phytochemicals, abundant in plants, such as carotenoids, ascorbic acid, tocopherols and polyphenols, offer diverse antioxidant mechanisms. They scavenge free radicals, chelate metal ions, and modulate cellular signalling pathways to mitigate oxidative damage. Furthermore, plants thriving in high-altitude regions are adapted to extreme conditions, and synthesize secondary metabolites, like flavonoids and phenolic compounds in bulk quantities, which act to form a robust antioxidant defence against oxidative stress, including UV radiation and temperature fluctuations. These plants are promising sources for drug development, offering innovative strategies by which to manage oxidative stress-related ailments and enhance human health. Understanding and harnessing the antioxidant potential of phytochemicals from high-altitude plants represent crucial steps in combating oxidative stress-induced disorders and promoting overall wellbeing. This study offers a comprehensive summary of the production and physio-pathological aspects of lifestyle-induced oxidative stress disorders and explores the potential of phytochemicals as promising antioxidants. Additionally, it presents an appraisal of high-altitude medicinal plants as significant sources of antioxidants, highlighting their potential for drug development and the creation of innovative antioxidant therapeutic approaches.

Dissemination of pathogenic bacteria is reinforced by a MARTX toxin effector duet

Multiple bacterial genera take advantage of the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin to invade host cells. Secretion of the MARTX toxin by Vibrio vulnificus, a deadly opportunistic pathogen that causes primary septicemia, the precursor of sepsis, is a major driver of infection; however, the molecular mechanism via which the toxin contributes to septicemia remains unclear. Here, we report the crystal and cryo-electron microscopy (EM) structures of a toxin effector duet comprising the domain of unknown function in the first position (DUF1)/Rho inactivation domain (RID) complexed with human targets. These structures reveal how the duet is used by bacteria as a potent weapon. The data show that DUF1 acts as a RID-dependent transforming NADase domain (RDTND) that disrupts NAD+ homeostasis by hijacking calmodulin. The cryo-EM structure of the RDTND-RID duet complexed with calmodulin and Rac1, together with immunological analyses in vitro and in mice, provide mechanistic insight into how V. vulnificus uses the duet to suppress ROS generation by depleting NAD(P)+ and modifying Rac1 in a mutually-reinforcing manner that ultimately paralyzes first line immune responses, promotes dissemination of invaders, and induces sepsis. These data may allow development of tools or strategies to combat MARTX toxin-related human diseases.

Neuronal GPCR NMUR-1 regulates energy homeostasis in response to pathogen infection

A key question in current immunology is how the innate immune system generates high levels of specificity. Our previous study in Caenorhabditis elegans revealed that NMUR-1, a neuronal G protein-coupled receptor homologous to mammalian receptors for the neuropeptide neuromedin U (NMU), regulates distinct innate immune responses to different bacterial pathogens. Here, by using quantitative proteomics and functional assays, we discovered that NMUR-1 regulates F1FO ATP synthase and ATP production in response to pathogen infection, and that such regulation contributes to NMUR-1-mediated specificity of innate immunity. We further demonstrated that ATP biosynthesis and its contribution to defense is neurally controlled by the NMUR-1 ligand CAPA-1 and its expressing neurons ASG. These findings indicate that NMUR-1 neural signaling regulates the specificity of innate immunity by controlling energy homeostasis as part of defense against pathogens. Our study provides mechanistic insights into the emerging roles of NMU signaling in immunity across animal phyla.

Manganese uptake by MtsABC contributes to the pathogenesis of human pathogen group A streptococcus by resisting host nutritional immune defenses

The interplay between host nutritional immune mechanisms and bacterial nutrient uptake systems has a major impact on the disease outcome. The host immune factor calprotectin (CP) limits the availability of essential transition metals, such as manganese (Mn) and zinc (Zn), to control the growth of invading pathogens. We previously demonstrated that the competition between CP and the human pathogen group A streptococcus (GAS) for Zn impacts GAS pathogenesis. However, the contribution of Mn sequestration by CP in GAS infection control and the role of GAS Mn acquisition systems in overcoming host-imposed Mn limitation remain unknown. Using a combination of in vitro and in vivo studies, we show that GAS-encoded mtsABC is a Mn uptake system that aids bacterial evasion of CP-imposed Mn scarcity and promotes GAS virulence. Mn deficiency caused by either the inactivation of mtsC or CP also impaired the protective function of GAS-encoded Mn-dependent superoxide dismutase. Our ex vivo studies using human saliva show that saliva is a Mn-scant body fluid, and Mn acquisition by MtsABC is critical for GAS survival in human saliva. Finally, animal infection studies using wild-type (WT) and CP-/- mice showed that MtsABC is critical for GAS virulence in WT mice but dispensable in mice lacking CP, indicating the direct interplay between MtsABC and CP in vivo. Together, our studies elucidate the role of the Mn import system in GAS evasion of host-imposed metal sequestration and underscore the translational potential of MtsABC as a therapeutic or prophylactic target.

Neuroimmune modulating and energy supporting nanozyme-mimic scaffold synergistically promotes axon regeneration after spinal cord injury

Spinal cord injury (SCI) represents a profound central nervous system affliction, resulting in irreversibly compromised daily activities and disabilities. SCI involves excessive inflammatory responses, which are characterized by the existence of high levels of proinflammatory M1 macrophages, and neuronal mitochondrial energy deficit, exacerbating secondary damage and impeding axon regeneration. This study delves into the mechanistic intricacies of SCI, offering insights from the perspectives of neuroimmune regulation and mitochondrial function, leading to a pro-fibrotic macrophage phenotype and energy-supplying deficit. To address these challenges, we developed a smart scaffold incorporating enzyme mimicry nanoparticle-ceriumoxide (COPs) into nanofibers (NS@COP), which aims to pioneer a targeted neuroimmune repair strategy, rescuing CGRP receptor on macrophage and concurrently remodeling mitochondrial function. Our findings indicate that the integrated COPs restore the responsiveness of pro-inflammatory macrophages to calcitonin gene-related peptide (CGRP) signal by up-regulating receptor activity modifying protein 1 (RAMP1), a vital component of the CGRP receptor. This promotes macrophage fate commitment to an anti-inflammatory pro-resolution M2 phenotype, then alleviating glial scar formation. In addition, NS@COP implantation also protected neuronal mitochondrial function. Collectively, our results suggest that the strategy of integrating nanozyme COP nanoparticles into a nanofiber scaffold provides a promising therapeutic candidate for spinal cord trauma via rational regulation of neuroimmune communication and mitochondrial function.

Intracellular Streptococcus pneumoniae develops enhanced fluoroquinolone persistence during influenza A coinfection

Streptococcus pneumoniae is a major pathogen responsible for severe complications in patients with prior influenza A virus (IAV) infection. We have previously demonstrated that S. pneumoniae exhibits increased intracellular survival within IAV-infected cells. Fluoroquinolones (FQs) are widely used to treat pneumococcal infections. However, our prior work has shown that S. pneumoniae can develop intracellular FQ persistence, a phenomenon triggered by oxidative stress within host cells. This persistence allows the bacteria to withstand high FQ concentrations. In this study, we show that IAV infection enhances pneumococcal FQ persistence during intracellular survival within pneumocytes, macrophages, and neutrophils. This enhancement is partly due to increased oxidative stress induced by the viral infection. We find that this phenotype is particularly pronounced in autophagy-proficient host cells, potentially resulting from IAV-induced blockage of autophagosome-lysosome fusion. Moreover, we identified several S. pneumoniae genes involved in oxidative stress response that contribute to FQ persistence, including sodA (superoxide dismutase), clpL (chaperone), nrdH (glutaredoxin), and psaB (Mn+2 transporter component). Our findings reveal a novel mechanism of antibiotic persistence promoted by viral infection within host cells. This underscores the importance of considering this phenomenon when using FQs to treat pneumococcal infections, especially in patients with concurrent influenza A infection.

Unravelling the Phytochemical Composition and Antioxidant Potential of Different Parts of Rumex vesicarius L.: A RP-HPLC-MS-MS/MS, Chemometrics, and Molecular Docking-Based Comparative Study

Rumex vesicarius L. Polygonaceae is a wildly grown plant in Egypt, North Africa, and Asia with wide traditional uses. Several studies reported its biological activities and richness in phytochemicals. This research addresses a comprehensive metabolic profiling of the flowers, leaves, stems, and roots via RP-HPLC-QTOF-MS and MS/MS with chemometrics. A total of 60 metabolites were observed and grouped into phenolic acids, flavonoids, phenols, terpenes, amino acids, fatty acids, organic acids, and sugars. Principal component analysis and hierarchal cluster analysis showed the segregation of different parts. Moreover, the antioxidant capacity was determined via several methods and agreed with the previous results. Additionally, an in silico approach of molecular docking of the predominant bioactive metabolites was employed against two antioxidant targets, NADPH oxidase and human peroxiredoxin 5 enzyme (PDB ID: 2CDU and 1HD2) receptors, alongside ADME predictions. The molecular modelling revealed that most of the approached molecules were specifically binding with the tested enzymes, achieving high binding affinities. The results confirmed that R. vesicarius stems and roots are rich sources of bioactive antioxidant components. To our knowledge, this is the first comprehensive metabolic profiling of R. vesicarius giving a prospect of its relevance in the development of new naturally based antioxidants.

Synthesis of New Chroman-4-one Based 1,2,3-Triazole Analogues as Antioxidant and Anti-Inflammatory Agents

A library of new chroman-4-one based 1,2,3-triazole analogues were synthesized involving a series of condensation, cyclization, Suzuki coupling and copper catalysed click chemistry protocols. The newly synthesized compounds 8a-l were screened for their invitro antioxidant and anti-inflammatory activities by employing Ascorbic acid and Diclofenac as reference drugs respectively. The compound without any substituent on benzyl ring (8a), compound with -Cl substituent in para position of benzyl ring (8i), and compound with ethoxy substituent in para position of benzyl ring (8k) exhibited potent antioxidant and anti-inflammatory activities with higher percentage of inhibition. To understand their binding affinities, molecular docking study of these three compounds performed against NADPH oxidase with presented outstanding docking scores and promising binding interactions like H-bond and hydrophobic.

Neuroprotective effects of naltrexone in a mouse model of post-traumatic seizures

Traumatic Brain Injury (TBI) induces neuroinflammatory response that can initiate epileptogenesis, which develops into epilepsy. Recently, we identified anti-convulsive effects of naltrexone, a mu-opioid receptor (MOR) antagonist, used to treat drug addiction. While blocking opioid receptors can reduce inflammation, it is unclear if post-TBI seizures can be prevented by blocking MORs. Here, we tested if naltrexone prevents neuroinflammation and/or seizures post-TBI. TBI was induced by a modified Marmarou Weight-Drop (WD) method on 4-week-old C57BL/6J male mice. Mice were placed in two groups: non-telemetry assessing the acute effects or in telemetry monitoring for interictal events and spontaneous seizures both following TBI and naltrexone. Molecular, histological and neuroimaging techniques were used to evaluate neuroinflammation, neurodegeneration and fiber track integrity at 8 days and 3 months post-TBI. Peripheral immune responses were assessed through serum chemokine/cytokine measurements. Our results show an increase in MOR expression, nitro-oxidative stress, mRNA expression of inflammatory cytokines, microgliosis, neurodegeneration, and white matter damage in the neocortex of TBI mice. Video-EEG revealed increased interictal events in TBI mice, with 71% mice developing post-traumatic seizures (PTS). Naltrexone treatment ameliorated neuroinflammation, neurodegeneration, reduced interictal events and prevented seizures in all TBI mice, which makes naltrexone a promising candidate against PTS, TBI-associated neuroinflammation and epileptogenesis in a WD model of TBI.

Mitochondrial Reactive Oxygen Species in Infection and Immunity

Reactive oxygen species (ROS) contain at least one oxygen atom and one or more unpaired electrons and include singlet oxygen, superoxide anion radical, hydroxyl radical, hydroperoxyl radical, and free nitrogen radicals. Intracellular ROS can be formed as a consequence of several factors, including ultra-violet (UV) radiation, electron leakage during aerobic respiration, inflammatory responses mediated by macrophages, and other external stimuli or stress. The enhanced production of ROS is termed oxidative stress and this leads to cellular damage, such as protein carbonylation, lipid peroxidation, deoxyribonucleic acid (DNA) damage, and base modifications. This damage may manifest in various pathological states, including ageing, cancer, neurological diseases, and metabolic disorders like diabetes. On the other hand, the optimum levels of ROS have been implicated in the regulation of many important physiological processes. For example, the ROS generated in the mitochondria (mitochondrial ROS or mt-ROS), as a byproduct of the electron transport chain (ETC), participate in a plethora of physiological functions, which include ageing, cell growth, cell proliferation, and immune response and regulation. In this current review, we will focus on the mechanisms by which mt-ROS regulate different pathways of host immune responses in the context of infection by bacteria, protozoan parasites, viruses, and fungi. We will also discuss how these pathogens, in turn, modulate mt-ROS to evade host immunity. We will conclude by briefly giving an overview of the potential therapeutic approaches involving mt-ROS in infectious diseases.

A nox2/cybb zebrafish mutant with defective myeloid cell reactive oxygen species production displays normal initial neutrophil recruitment to sterile tail injuries

Reactive oxygen species are important effectors and modifiers of the acute inflammatory response, recruiting phagocytes including neutrophils to sites of tissue injury. In turn, phagocytes such as neutrophils are both consumers and producers of reactive oxygen species. Phagocytes including neutrophils generate reactive oxygen species in an oxidative burst through the activity of a multimeric phagocytic nicotinamide adenine dinucleotide phosphate oxidase complex. Mutations in the NOX2/CYBB (previously gp91phox) nicotinamide adenine dinucleotide phosphate oxidase subunit are the commonest cause of chronic granulomatous disease, a disease characterized by infection susceptibility and an inflammatory phenotype. To model chronic granulomatous disease, we made a nox2/cybb zebrafish (Danio rerio) mutant and demonstrated it to have severely impaired myeloid cell reactive oxygen species production. Reduced early survival of nox2 mutant embryos indicated an essential requirement for nox2 during early development. In nox2/cybb zebrafish mutants, the dynamics of initial neutrophil recruitment to both mild and severe surgical tailfin wounds was normal, suggesting that excessive neutrophil recruitment at the initiation of inflammation is not the primary cause of the "sterile" inflammatory phenotype of chronic granulomatous disease patients. This nox2 zebrafish mutant adds to existing in vivo models for studying reactive oxygen species function in myeloid cells including neutrophils in development and disease.

Redox regulation of macrophages

Redox signaling, a mode of signal transduction that involves the transfer of electrons from a nucleophilic to electrophilic molecule, has emerged as an essential regulator of inflammatory macrophages. Redox reactions are driven by reactive oxygen/nitrogen species (ROS and RNS) and redox-sensitive metabolites such as fumarate and itaconate, which can post-translationally modify specific cysteine residues in target proteins. In the past decade our understanding of how ROS, RNS, and redox-sensitive metabolites control macrophage function has expanded dramatically. In this review, we discuss the latest evidence of how ROS, RNS, and metabolites regulate macrophage function and how this is dysregulated with disease. We highlight the key tools to assess redox signaling and important questions that remain.

A novel glycoglycerolipid from Holotrichia diomphalia Bates: Structure characteristics and protective effect against DNA damage

A lipidated polysaccharide, HDPS-2II, was isolated from the dried larva of Holotrichia diomphalia, which is used in traditional Chinese medicine. The molecular weight of HDPS-2II was 5.9 kDa, which contained a polysaccharide backbone of →4)-β-Manp-(1 → 4,6)-β-Manp-(1 → [6)-α-Glcp-(1]n → 6)-α-Glcp→ with the side chain α-Glcp-(6 → 1)-α-Glcp-(6 → linked to the C-4 of β-1,4,6-Manp and four types of lipid chains including 4-(4-methyl-2-(methylamino)pentanamido)pentanoic acid, 5-(3-(tert-butyl)phenoxy)hexan-2-ol, N-(3-methyl-5-oxopentan-2-yl)palmitamide, and N-(5-amino-3-methyl-5-oxopentan-2-yl)stearamide. The lipid chains were linked to C-1 of terminal α-1,6-Glcp in carbohydrate chain through diacyl-glycerol. HDPS-2II exhibited DNA protective effects and antioxidative activity on H2O2- or adriamycin (ADM)-induced Chinese hamster lung cells. Furthermore, HDPS-2II significantly ameliorated chromosome aberrations and the accumulation of reactive oxygen species (ROS), reduced γ-H2AX signaling and the expressions of NADPH oxidase (NOX)2, NOX4, P22phox, and P47phox in ADM-induced cardiomyocytes. Mechanistically, HDPS-2II suppressed ADM-induced up-regulation of NOX2 and NOX4 in cardiomyocytes, but not in NOX2 or NOX4 knocked-down cardiomyocytes, indicating that HDPS-2II could relieve intracellular DNA damage by regulating NOX2/NOX4 signaling. These findings demonstrate that HDPS-2II is a new potential DNA protective agent.

Large enrichments in fatty acid 2H/1H ratios distinguish respiration from aerobic fermentation in yeast Saccharomyces cerevisiae

Shifts in the hydrogen stable isotopic composition (2H/1H ratio) of lipids relative to water (lipid/water 2H-fractionation) at natural abundances reflect different sources of the central cellular reductant, NADPH, in bacteria. Here, we demonstrate that lipid/water 2H-fractionation (2εfattyacid/water) can also constrain the relative importance of key NADPH pathways in eukaryotes. We used the metabolically flexible yeast Saccharomyces cerevisiae, a microbial model for respiratory and fermentative metabolism in industry and medicine, to investigate 2εfattyacid/water. In chemostats, fatty acids from glycerol-respiring cells were >550‰ 2H-enriched compared to those from cells aerobically fermenting sugars via overflow metabolism, a hallmark feature in cancer. Faster growth decreased 2H/1H ratios, particularly in glycerol-respiring cells by 200‰. Variations in the activities and kinetic isotope effects among NADP+-reducing enzymes indicate cytosolic NADPH supply as the primary control on 2εfattyacid/water. Contributions of cytosolic isocitrate dehydrogenase (cIDH) to NAPDH production drive large 2H-enrichments with substrate metabolism (cIDH is absent during fermentation but contributes up to 20 percent NAPDH during respiration) and slower growth on glycerol (11 percent more NADPH from cIDH). Shifts in NADPH demand associated with cellular lipid abundance explain smaller 2εfattyacid/water variations (<30‰) with growth rate during fermentation. Consistent with these results, tests of murine liver cells had 2H-enriched lipids from slower-growing, healthy respiring cells relative to fast-growing, fermenting hepatocellular carcinoma. Our findings point to the broad potential of lipid 2H/1H ratios as a passive natural tracker of eukaryotic metabolism with applications to distinguish health and disease, complementing studies that rely on complex isotope-tracer addition methods.

An investigation into the HIF-dependent intestinal barrier protective mechanism of Qingchang Wenzhong decoction in ulcerative colitis management

ETHNOPHARMACOLOGICAL RELEVANCE

Ulcerative colitis (UC) is a chronic, non-specific inflammatory disease affecting the colon and rectum with an etiology that remains elusive. Traditional Chinese medicine (TCM) has been widely used on long-term UC treatment to better maintain the efficacy than traditional aminosalicylic acid or glucocorticosteroids and to ease financial burden of patients. Qingchang Wenzhong Decoction (QCWZD) is a modern TCM decoction with established clinical efficacy but the mechanism of its protection on intestinal barrier function remains unclear.

AIM OF THE STUDY

Current findings highlight that the activation of the hypoxia inducible factor (HIF) pathway can facilitate the repair of intestinal epithelium barrier. This study is to investigate the protective effects of QCWZD and its HIF-targeted ingredients on hypoxia-dependent intestinal barrier.

METHODS

The mice model of UC was induced by dextran sulfate sodium (DSS). Disease activity index (DAI) and histopathology scores and colon length were used to measure the severity of colitis. The DAO activity in serum and protein expression of tight junction (TJ) proteins were detected to explore the function of intestinal barrier. The protein levels of HIF-1α and its downstream gene heme oxygenase-1 (HO-1) were measured as well. HIF-targeted active ingredients in QCWZD were selected by network pharmacology and molecular docking. Protective effects of six constituents on HIF-related anti-oxidative and barrier protective pathway were evaluated by lipopolysaccharide (LPS)-induced HT29 and RAW264.7 cells, through the measurement of the production of ROS and mRNA level of pro-inflammatory cytokines. HIF-1α knockdown was carried out to explore the correlation of protection effects with HIF-related pathway of the active ingredients.

RESULTS

QCWZD effectively alleviated colitis induced by DSS and demonstrated a protective effect on intestinal barrier function by upregulating HIF-related pathways. Six specific ingredients in QCWZD, targeting HIF, successfully reduced the production of cellular ROS and proinflammatory cytokines in LPS-induced cells. It is noteworthy that the barrier protection provided by these molecules is intricately linked with the HIF-related pathway.

CONCLUSIONS

This study elucidates the HIF-related molecular mechanism of QCWZD in protecting the function of the epithelial barrier. Six compounds targeting the activation of the HIF-dependent pathway were demonstrated to unveil a novel therapeutic approach for managing UC.

Glucose and trehalose metabolism through the cyclic pentose phosphate pathway shapes pathogen resistance and host protection in Drosophila

Activation of immune cells requires the remodeling of cell metabolism in order to support immune function. We study these metabolic changes through the infection of Drosophila larvae by parasitoid wasp. The parasitoid egg is neutralized by differentiating lamellocytes, which encapsulate the egg. A melanization cascade is initiated, producing toxic molecules to destroy the egg while the capsule also protects the host from the toxic reaction. We combined transcriptomics and metabolomics, including 13C-labeled glucose and trehalose tracing, as well as genetic manipulation of sugar metabolism to study changes in metabolism, specifically in Drosophila hemocytes. We found that hemocytes increase the expression of several carbohydrate transporters and accordingly uptake more sugar during infection. These carbohydrates are metabolized by increased glycolysis, associated with lactate production, and cyclic pentose phosphate pathway (PPP), in which glucose-6-phosphate is re-oxidized to maximize NADPH yield. Oxidative PPP is required for lamellocyte differentiation and resistance, as is systemic trehalose metabolism. In addition, fully differentiated lamellocytes use a cytoplasmic form of trehalase to cleave trehalose to glucose and fuel cyclic PPP. Intracellular trehalose metabolism is not required for lamellocyte differentiation, but its down-regulation elevates levels of reactive oxygen species, associated with increased resistance and reduced fitness. Our results suggest that sugar metabolism, and specifically cyclic PPP, within immune cells is important not only to fight infection but also to protect the host from its own immune response and for ensuring fitness of the survivor.

Several lines of antioxidant defense against oxidative stress: antioxidant enzymes, nanomaterials with multiple enzyme-mimicking activities, and low-molecular-weight antioxidants

Reactive oxygen species (ROS) and reactive nitrogen species (RNS) are well recognized for playing a dual role, since they can be either deleterious or beneficial to biological systems. An imbalance between ROS production and elimination is termed oxidative stress, a critical factor and common denominator of many chronic diseases such as cancer, cardiovascular diseases, metabolic diseases, neurological disorders (Alzheimer's and Parkinson's diseases), and other disorders. To counteract the harmful effects of ROS, organisms have evolved a complex, three-line antioxidant defense system. The first-line defense mechanism is the most efficient and involves antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). This line of defense plays an irreplaceable role in the dismutation of superoxide radicals (O2•-) and hydrogen peroxide (H2O2). The removal of superoxide radicals by SOD prevents the formation of the much more damaging peroxynitrite ONOO- (O2•-  + NO• → ONOO-) and maintains the physiologically relevant level of nitric oxide (NO•), an important molecule in neurotransmission, inflammation, and vasodilation. The second-line antioxidant defense pathway involves exogenous diet-derived small-molecule antioxidants. The third-line antioxidant defense is ensured by the repair or removal of oxidized proteins and other biomolecules by a variety of enzyme systems. This review briefly discusses the endogenous (mitochondria, NADPH, xanthine oxidase (XO), Fenton reaction) and exogenous (e.g., smoking, radiation, drugs, pollution) sources of ROS (superoxide radical, hydrogen peroxide, hydroxyl radical, peroxyl radical, hypochlorous acid, peroxynitrite). Attention has been given to the first-line antioxidant defense system provided by SOD, CAT, and GPx. The chemical and molecular mechanisms of antioxidant enzymes, enzyme-related diseases (cancer, cardiovascular, lung, metabolic, and neurological diseases), and the role of enzymes (e.g., GPx4) in cellular processes such as ferroptosis are discussed. Potential therapeutic applications of enzyme mimics and recent progress in metal-based (copper, iron, cobalt, molybdenum, cerium) and nonmetal (carbon)-based nanomaterials with enzyme-like activities (nanozymes) are also discussed. Moreover, attention has been given to the mechanisms of action of low-molecular-weight antioxidants (vitamin C (ascorbate), vitamin E (alpha-tocopherol), carotenoids (e.g., β-carotene, lycopene, lutein), flavonoids (e.g., quercetin, anthocyanins, epicatechin), and glutathione (GSH)), the activation of transcription factors such as Nrf2, and the protection against chronic diseases. Given that there is a discrepancy between preclinical and clinical studies, approaches that may result in greater pharmacological and clinical success of low-molecular-weight antioxidant therapies are also subject to discussion.

Helicobacter pylori secretary Proteins-Induced oxidative stress and its role in NLRP3 inflammasome activation

Helicobacter pylori-associated stomach infection is a leading cause of gastric ulcer and related cancer. H. pylori modulates the functions of infiltrated immune cells to survive the killing by reactive oxygen and nitrogen species (ROS and RNS) produced by these cells. Uncontrolled immune responses further produce excess ROS and RNS which lead to mucosal damage. The persistent oxidative stress is a major cause of gastric cancer. H. pylori regulates nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs), nitric oxide synthase 2 (NOS2), and polyamines to control ROS and RNS release through lesser-known mechanisms. ROS and RNS produced by these pathways differentiate macrophages and T cells from protective to inflammatory phenotype. Pathogens-associated molecular patterns (PAMPs) induced ROS activates nuclear oligomerization domain (NOD), leucine rich repeats (LRR) and pyrin domain-containing protein 3 (NLRP3) inflammasome for the release of pro-inflammatory cytokines. This study evaluates the role of H. pylori secreted concentrated proteins (HPSCP) related oxidative stress role in NLRP3 inflammasome activation and macrophage differentiation. To perceive the role of ROS/RNS, THP-1 and AGS cells were treated with 10 μM diphenyleneiodonium (DPI), 50 μM salicyl hydroxamic acid (SHX), 5 μM Carbonyl cyanide-4-(trifluoromethoxy) phenylhydrazone (FCCP), which are specific inhibitors of NADPH oxidase (NOX), Myeloperoxidase (MPO), and mitochondrial oxidative phosphorylation respectively. Cells were also treated with 10 μM of NOS2 inhibitor l-NMMA and 10 μM of N-acetyl cysteine (NAC), a free radical scavenger·H2O2 (100 μM) treated and untreated cells were used as positive controls and negative control respectively. The expression of gp91phox (NOX2), NOS2, NLRP3, CD86 and CD163 was analyzed through fluorescent microscopy. THP-1 macrophages growth was unaffected whereas the gastric epithelial AGS cells proliferated in response to higher concentration of HPSCP. ROS and myeloperoxidase (MPO) level increased in THP-1 cells and nitric oxide (NO) and lipid peroxidation significantly decreased in AGS cells. gp91phox expression was unchanged, whereas NOS2 and NLRP3 downregulated in response to HPSCP, but increased after inhibition of NO, ROS and MPO in THP-1 cells. HPSCP upregulated the expression of M1 and M2 macrophage markers, CD86 and CD163 respectively, which was decreased after the inhibition of ROS. This study concludes that there are multiple pathways which are generating ROS during H. pylori infection which further regulates other cellular processes. NO is closely associated with MPO and inhibition of NLRP3 inflammasome. The low levels of NO and MPO regulates gastrointestinal tract homeostasis and overcomes the inflammatory response of NLRP3. The ROS also plays crucial role in macrophage polarization hence alter the immune responses duing H. pylori pathogenesis.

Mycobacterium tuberculosis protein PPE15 (Rv1039c) possesses eukaryote-like SH3 domain that interferes with NADPH Oxidase assembly and Reactive Oxygen Species production

Inhibition of Reactive Oxygen Species (ROS) is one of the strategies that Mycobacterium tuberculosis (Mtb) employs as its defence mechanism. In this study, the role of PPE15 (Rv1039c), a late-stage protein, has been investigated in modulating the cellular ROS. We discovered PPE15 to be a secretory protein that downregulates ROS generation in THP1 macrophages. Our in-silico analysis revealed the presence of a eukaryote-like SH3 (SH3e) domain in PPE15. The predicted SH3e-domain of PPE15 was found to interact with cytosolic components of NADPH Oxidase (NOX), p67phox and p47phox through molecular docking. In-vitro experiments using THP1 macrophages showed a diminished NADP/NADPH ratio, indicating reduced NOX activity. We also observed increased levels of p67phox and p47phox in the cytoplasmic fraction of PPE15 treated macrophages as compared to the plasma membrane fraction. To understand the role of the SH3e-domain in ROS modulation, this domain was deleted from the full-length PPE15 (PPE15-/-SH3). We observed an increase in cellular ROS and NADP/NADPH ratio in response to PPE15-/-SH3 protein. The interaction of PPE15-/-SH3 with p67phox or p47phox was also reduced in the cytoplasm, indicating migration of NOX subunits to the plasma membrane. Additionally, M. smegmatis expressing PPE15 was observed to be resistant to oxidative stress with significant intracellular survival in THP1 macrophages as compared to M. smegmatis expressing PPE15-/-SH3. These observations suggest that the SH3e-domain of PPE15 interferes with ROS generation by sequestering NOX components that inhibit NOX assembly at the cell membrane. Therefore, PPE15 acts like a molecular mimic of SH3-domain carrying eukaryotic proteins that can be employed by Mtb at late stages of infection for its survival. These findings give us new insights about the pathogen evading strategy of Mtb which may help in improving the therapeutics for TB treatment.

Lonicerin promotes wound healing in diabetic rats by enhancing blood vessel regeneration through Sirt1-mediated autophagy

Among the numerous complications of diabetes mellitus, diabetic wounds seriously affect patients' quality of life and result in considerable psychological distress. Promoting blood vessel regeneration in wounds is a crucial step in wound healing. Lonicerin (LCR), a bioactive compound found in plants of the Lonicera japonica species and other honeysuckle plants, exhibits anti-inflammatory and antioxidant activities, and it recently has been found to alleviate ulcerative colitis by enhancing autophagy. In this study we investigated the efficacy of LCR in treatment of diabetic wounds and the underlying mechanisms. By comparing the single-cell transcriptomic data from healing and non-healing states in diabetic foot ulcers (DFU) of 5 patients, we found that autophagy and SIRT signaling activation played a crucial role in mitigating inflammation and oxidative stress, and promoting cell survival in wound healing processes. In TBHP-treated human umbilical vein endothelial cells (HUVECs), we showed that LCR alleviated cell apoptosis, and enhanced the cell viability, migration and angiogenesis. Furthermore, we demonstrated that LCR treatment dose-dependently promoted autophagy in TBHP-treated HUVECs by upregulating Sirt1 expression, and exerted its anti-apoptotic effect through the Sirt1-autophagy axis. Knockdown of Sirt1 significantly decreased the level of autophagy, and mitigated the anti-apoptotic effect of LCR. In a STZ-induced diabetic rat model, administration of LCR significantly promoted wound healing, which was significantly attenuated by Sirt1 knockdown. This study highlights the potential of LCR as a therapeutic agent for the treatment of diabetic wounds and provides insights into the molecular mechanisms underlying its effects.

Oxidative Stress Induced by Cortisol in Human Platelets

Hypercortisolism is known to affect platelet function. However, few studies have approached the effect of exogenous cortisol on human platelets, and the results obtained are conflicting and unconvincing. In this study, the effect of exogenous cortisol on several parameters indicative of oxidative status in human platelets has been analysed. We have found that cortisol stimulates ROS production, superoxide anion formation, and lipid peroxidation, with these parameters being in strict correlation. In addition, cortisol decreases GSH and membrane SH-group content, evidencing that the hormone potentiates oxidative stress, depleting platelet antioxidant defence. The involvement of src, syk, PI3K, and AKT enzymes in oxidative mechanisms induced by cortisol is shown. The main sources of ROS in cells can include uncontrolled increase of NADPH oxidase activity and uncoupled aerobic respiration during oxidative phosphorylation. Both mechanisms seem to be involved in ROS formation induced by cortisol, as the NADPH oxidase 1 inhibitor 2(trifluoromethyl)phenothiazine, and rotenone and antimycin A, complex I and III inhibitor, respectively, significantly reduce oxidative stress. On the contrary, the NADPH oxidase inhibitor gp91ds-tat, malate and NaCN, complex II and IV inhibitor, respectively, have a minor effect. It is likely that, in human platelets, oxidative stress induced by cortisol can be associated with venous and arterial thrombosis, greatly contributing to cardiovascular diseases.

Empagliflozin attenuates radiation-induced hematopoietic damage via NOX-4/ROS/p38 pathway

PURPOSE

Damage to the hematopoietic system and functional inhibition are severe consequences of radiation exposure. In this study, we have investigated the effect of empagliflozin on radiation-induced hematopoietic damage, with the aim of providing new preventive approach to such injuries.

METHODS AND MATERIALS

Mice were given 4 Gy total body irradiation (TBI) 1 h after the oral administration of empagliflozin, followed by the continuous administration of the same dose of empagliflozin for 6d, and then sacrificed on the 10th day after irradiation. The reactive oxygen species (ROS) levels in hematopoietic cells and their regulatory mechanisms were also been investigated. Colony forming unit granulocyte macrophage assay and bone marrow transplantation assays were performed to detect the function of the bone marrow cells.

KEY FINDINGS

Empagliflozin increased the cell viability, reduced ROS levels, and attenuated apoptosis in vitro after the bone marrow cells were exposed to 1 Gy radiation. Empagliflozin significantly attenuated ionizing radiation injuries to the hematopoietic system, increased the peripheral blood cell count, and enhanced the proportion and function of hematopoietic stem cells in mice exposed to 4 Gy TBI. These effects may be related to the NOX-4/ROS/p38 pathway-mediated suppression of MAPK in hematopoietic stem cells. Empagliflozin also influenced the expression of Nrf-2 and increased glutathione peroxidase activity, thereby promoting the clearance of reactive oxygen species. Furthermore, empagliflozin mitigated metabolic abnormalities by inhibiting the mammalian target of rapamycin.

SIGNIFICANCE

Our study has demonstrated that empagliflozin can reduce radiation-induced injury in hematopoietic stem cells. This finding suggests that empagliflozin is a promising novel agent for preventing radiation-induced damage to the hematopoietic system.

ROS signaling in innate immunity via oxidative protein modifications

The innate immune response represents the first-line of defense against invading pathogens. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have been implicated in various aspects of innate immune function, which involves respiratory bursts and inflammasome activation. These reactive species widely distributed within the cellular environment are short-lived intermediates that play a vital role in cellular signaling and proliferation and are likely to depend on their subcellular site of formation. NADPH oxidase complex of phagocytes is known to generate superoxide anion radical (O2 •-) that functions as a precursor for antimicrobial hydrogen peroxide (H2O2) production, and H2O2 is utilized by myeloperoxidase (MPO) to generate hypochlorous acid (HOCl) that mediates pathogen killing. H2O2 modulates the expression of redox-responsive transcriptional factors, namely NF-kB, NRF2, and HIF-1, thereby mediating redox-based epigenetic modification. Survival and function of immune cells are under redox control and depend on intracellular and extracellular levels of ROS/RNS. The current review focuses on redox factors involved in the activation of immune response and the role of ROS in oxidative modification of proteins in macrophage polarization and neutrophil function.

Implications for neutrophils in cardiac arrhythmias

Cardiac arrhythmias commonly occur as a result of aberrant electrical impulse formation or conduction in the myocardium. Frequently discussed triggers include underlying heart diseases such as myocardial ischemia, electrolyte imbalances, or genetic anomalies of ion channels involved in the tightly regulated cardiac action potential. Recently, the role of innate immune cells in the onset of arrhythmic events has been highlighted in numerous studies, correlating leukocyte expansion in the myocardium to increased arrhythmic burden. Here, we aim to call attention to the role of neutrophils in the pathogenesis of cardiac arrhythmias and their expansion during myocardial ischemia and infectious disease manifestation. In addition, we will elucidate molecular mechanisms associated with neutrophil activation and discuss their involvement as direct mediators of arrhythmogenicity.

The Association Between Oxidative Stress and the Progression of Heart Failure: A Systematic Review

Chronic heart failure (CHF) is a progressive multifactorial condition where the role of oxidative stress may have implications in the pathogenesis of the disease. Despite growing interest among researchers and clinicians, the limited, unorganized, and divergent findings regarding the association between oxidative stress and the progression of heart failure (HF) have prompted us to conduct this study. Drawing upon the evolving nature of this research domain, this study is one of the first of its kind to present a systematic and comprehensive overview of the existing evidence regarding the role of oxidative stress production in the progression of HF. This study systematically reviews peer-reviewed empirical studies published in English, particularly focusing on the association between oxidative stress and the progression of HF. Parameters, such as publication year, study design, population demographics (size, age, and gender), types of HF, and characterization of markers in the existing studies, were reviewed. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) procedure, a thorough search was conducted on PubMed, Cochrane, Embase, and Sage databases, without any restrictions on the publication dates of articles, which yielded a total of 1,808 records on the association of oxidative stress production with clinical outcomes in HF patients. The analysis of the content of 17 articles offered a robust observation of this phenomenon, providing insights into the levels of oxidative stress, antioxidant markers, and the enzymes involved in the production of reactive oxygen species (ROS), and their association with the progression and severity of HF. The findings highlighted various knowledge gaps and future research priorities are recommended in the areas of interest and unexplored areas.

Excessive hypercholesterolemia in pregnancy impairs rat uterine artery function via activation of Toll-like receptor 4

Hypercholesterolemia in pregnancy is a physiological process required for normal fetal development. In contrast, excessive pregnancy-specific hypercholesterolemia increases the risk of complications, such as preeclampsia. However, the underlying mechanisms are unclear. Toll-like receptor 4 (TLR4) is a membrane receptor modulated by high cholesterol levels, leading to endothelial dysfunction; but whether excessive hypercholesterolemia in pregnancy activates TLR4 is not known. We hypothesized that a high cholesterol diet (HCD) during pregnancy increases TLR4 activity in uterine arteries, leading to uterine artery dysfunction. Sprague Dawley rats were fed a control diet (n=12) or HCD (n=12) during pregnancy (gestational day 6-20). Vascular function was assessed in main uterine arteries using wire myography (vasodilation to methacholine and vasoconstriction to phenylephrine; with and without inhibitors for mechanistic pathways) and pressure myography (biomechanical properties). Exposure to a HCD during pregnancy increased maternal blood pressure, induced proteinuria, and reduced the fetal-to-placental weight ratio for both sexes. Excessive hypercholesterolemia in pregnancy also impaired vasodilation to methacholine in uterine arteries, whereby at higher doses, methacholine caused vasoconstriction instead of vasodilation in only the HCD group, which was prevented by inhibition of TLR4 or prostaglandin H synthase 1. Endothelial nitric oxide synthase expression and nitric oxide levels were reduced in HCD compared with control dams. Vasoconstriction to phenylephrine and biomechanical properties were similar between groups. In summary, excessive hypercholesterolemia in pregnancy impairs uterine artery function, with TLR4 activation as a key mechanism. Thus, TLR4 may be a target for therapy development to prevent adverse perinatal outcomes in complicated pregnancies.

Superoxide, nitric oxide and peroxynitrite production by macrophages under different physiological oxygen tensions

Macrophages count on two O2-consuming enzymes to form reactive radical species: NAPDH oxidase 2 (Nox2) and nitric oxide synthase 2 (inducible isoform, iNOS) that produce superoxide radical (O2•-) and nitric oxide (•NO), respectively. If formed simultaneously, the diffusion-controlled reaction of O2•- and •NO yields peroxynitrite, a potent cytotoxic oxidant. In human tissues and cells, the oxygen partial pressure (pO2) normally ranges within 2-14 %, with a typical average pO2 value for most tissues ca. 5 %. Given that O2 is a substrate for both Nox2 and iNOS, its tissue and cellular concentration can affect O2•- and •NO production. Also, O2 is a modulator of the macrophage adaptative response and may influence iNOS expression in a hypoxia inducible factor 1-α (HIF1α-)-dependent manner. However, most of the reported experiments in cellula, analyzing the formation and effects of O2•- and •NO during macrophage activation and cytotoxicity towards pathogens, have been performed in cells exposed to atmospheric air supplemented with 5 % CO2; under these conditions, most cells are exposed to supraphysiologic oxygen tensions (ca. 20 % O2) which are far from the physiological pO2. Here, the role of O2 as substrate in the oxidative response of J774A.1 macrophages was explored upon exposure to different pO2 and O2•- and •NO formation rates were measured, obtaining a KM of 26 and 42 μM O2 for Nox2 and iNOS, respectively. Consequently, peroxynitrite formation was influenced by pO2, reaching a maximum at ≥ 10 % O2, but even at levels as low as 2 % O2, a substantial formation rate of this oxidant was detected. Indeed, the cytotoxic capacity of immunostimulated macrophages against the intracellular parasite T. cruzi was significant, even at low pO2 values, confirming the role of peroxynitrite as a potent oxidizing cytotoxin within a wide range of physiological oxygen tensions.

Exposure to the plasticizer diisopentyl phthalate can cause Vero cell line death

Phthalates are synthetic plasticizers present in the daily lives of humans, as part of the composition of different products, such as food packaging, water bottles, and toys. These compounds can migrate from plastic materials to the environment changing biological systems. Although diisopentyl phthalate (DiPeP) is largely used in Brazil, there is a lack of information on the possible toxic effects of this compound. This research aims to evaluate the toxicity of DiPeP in the Vero renal cells. These cells were exposed to the 1-1000 μM of DiPeP for 24 and 72 h and subsequently, the cytotoxicity, apoptosis and necrosis-inducing potential, and antioxidant system (SOD, GPx, and GST) were investigated. DiPeP neither caused cytotoxicity nor altered SOD and GPx activity, although GST has been increased at 100 or 1 μM (24 and 72 h, respectively). However, cell death by apoptosis and necrosis was observed. These results indicate that DiPeP caused cell death by a non-oxidative stress-mediated mechanism, which shows the relevance of investigate other process in further researches.

Macrophages inhibit extracellular hyphal growth of A. fumigatus through Rac2 GTPase signaling

Macrophages act as a first line of defense against pathogens. Against Aspergillus fumigatus, a fungus with pathogenic potential in immunocompromised patients, macrophages can phagocytose fungal spores and inhibit spore germination to prevent the development of tissue-invasive hyphae. However, the cellular pathways that macrophages use to accomplish these tasks and any roles macrophages have later in infection against invasive forms of fungi are still not fully known. Rac-family Rho GTPases are signaling hubs for multiple cellular functions in leukocytes, including cell migration, phagocytosis, reactive oxygen species (ROS) generation, and transcriptional activation. We therefore aimed to further characterize the function of macrophages against A. fumigatus in an in vivo vertebrate infection model by live imaging of the macrophage behavior in A. fumigatus-infected rac2 mutant zebrafish larvae. While Rac2-deficient zebrafish larvae are susceptible to A. fumigatus infection, Rac2 deficiency does not impair macrophage migration to the infection site, interaction with and phagocytosis of spores, spore trafficking to acidified compartments, or spore killing. However, we reveal a role for Rac2 in macrophage-mediated inhibition of spore germination and control of invasive hyphae. Re-expression of Rac2 under a macrophage-specific promoter rescues the survival of A. fumigatus-infected rac2 mutant larvae through increased control of germination and hyphal growth. Altogether, we describe a new role for macrophages against extracellular hyphal growth of A. fumigatus and report that the function of the Rac2 Rho GTPase in macrophages is required for this function.

Monogenic Disorders of ROS Production and the Primary Anti-Oxidative Defense

Oxidative stress, characterized by an imbalance between the production of reactive oxygen species (ROS) and the cellular anti-oxidant defense mechanisms, plays a critical role in the pathogenesis of various human diseases. Redox metabolism, comprising a network of enzymes and genes, serves as a crucial regulator of ROS levels and maintains cellular homeostasis. This review provides an overview of the most important human genes encoding for proteins involved in ROS generation, ROS detoxification, and production of reduced nicotinamide adenine dinucleotide phosphate (NADPH), and the genetic disorders that lead to dysregulation of these vital processes. Insights gained from studies on inherited monogenic metabolic diseases provide valuable basic understanding of redox metabolism and signaling, and they also help to unravel the underlying pathomechanisms that contribute to prevalent chronic disorders like cardiovascular disease, neurodegeneration, and cancer.

NADPH Oxidase 3: Beyond the Inner Ear

Reactive oxygen species (ROS) were formerly known as mere byproducts of metabolism with damaging effects on cellular structures. The discovery and description of NADPH oxidases (Nox) as a whole enzyme family that only produce this harmful group of molecules was surprising. After intensive research, seven Nox isoforms were discovered, described and extensively studied. Among them, the NADPH oxidase 3 is the perhaps most underrated Nox isoform, since it was firstly discovered in the inner ear. This stigma of Nox3 as "being only expressed in the inner ear" was also used by me several times. Therefore, the question arose whether this sentence is still valid or even usable. To this end, this review solely focuses on Nox3 and summarizes its discovery, the structural components, the activating and regulating factors, the expression in cells, tissues and organs, as well as the beneficial and detrimental effects of Nox3-mediated ROS production on body functions. Furthermore, the involvement of Nox3-derived ROS in diseases progression and, accordingly, as a potential target for disease treatment, will be discussed.

Atorvastatin's Therapeutic Potential in Atherosclerosis: Inhibiting TGF-β-Induced Proteoglycan Glycosaminoglycan Chain Elongation through ROS-ERK1/2-Smad2L Signaling Pathway Modulation in Vascular Smooth Muscle Cells

OBJECTIVE

According to the response-to-retention hypothesis, the inception of atherosclerosis is attributed to the deposition and retention of lipoprotein in the arterial intima, facilitated by altered proteoglycans with hyperelongated glycosaminoglycan (GAG) chains. Recent studies have elucidated a signaling pathway whereby transforming growth factor-β (TGF-β) promotes the expression of genes linked to proteoglycan GAG chain elongation (CHSY1 and CHST11) via reactive oxygen species (ROS) and the downstream phosphorylation of ERK1/2 and Smad2L. Atorvastatin is known to exhibit pleiotropic effects, including antioxidant and anti-inflammatory. The purpose of the present research was to ascertain the influence of atorvastatin on TGF-β-stimulated expression of CHSY1 and CHST11 and associated signaling pathways using an in vitro model.

MATERIALS AND METHODS

In this experimental study, vascular smooth muscle cells (VSMCs) were pre-incubated with atorvastatin (0.1-10 μM) prior to being stimulated with TGF-β (2 ng/ml). The experiment aimed to evaluate the phosphorylation levels of Smad2C, Smad2L, ERK1/2, the NOX p47phox subunit, ROS production, and the mRNA expression of CHST11 and CHSY1.

RESULTS

Our research results indicated that atorvastatin inhibited TGF-β-stimulated CHSY1 and CHST11 mRNA expression. Further experiments showed that atorvastatin diminished TGF-β-stimulated ROS production and weakened TGF-β-stimulated phosphorylation of p47phox, ERK1/2, and Smad2L; however, we observed no effect on the TGF-β- Smad2C pathway.

CONCLUSION

These data suggest that atorvastatin demonstrates anti-atherogenic properties through the modulation of the ROS-ERK1/2-Smad2L signaling pathway. This provides valuable insight into the potential mechanisms by which atorvastatin exerts its pleiotropic effects against atherosclerosis.

Mitochondrial Regulation of Macrophages in Innate Immunity and Diverse Roles of Macrophages During Cochlear Inflammation

Macrophages are essential components of the innate immune system and constitute a non-specific first line of host defense against pathogens and inflammation. Mitochondria regulate macrophage activation and innate immune responses in various inflammatory diseases, including cochlear inflammation. The distribution, number, and morphological characteristics of cochlear macrophages change significantly across different inner ear regions under various pathological conditions, including noise exposure, ototoxicity, and age-related degeneration. However, the exact mechanism underlying the role of mitochondria in macrophages in auditory function remains unclear. Here, we summarize the major factors and mitochondrial signaling pathways (e.g., metabolism, mitochondrial reactive oxygen species, mitochondrial DNA, and the inflammasome) that influence macrophage activation in the innate immune response. In particular, we focus on the properties of cochlear macrophages, activated signaling pathways, and the secretion of inflammatory cytokines after acoustic injury. We hope this review will provide new perspectives and a basis for future research on cochlear inflammation.

The secreted feruloyl esterase of Verticillium dahliae modulates host immunity via degradation of GhDFR

Feruloyl esterase (ferulic acid esterase, FAE) is an essential component of many biological processes in both eukaryotes and prokaryotes. This research aimed to investigate the role of FAE and its regulation mechanism in plant immunity. We identified a secreted feruloyl esterase VdFAE from the hemibiotrophic plant pathogen Verticillium dahliae. VdFAE acted as an important virulence factor during V. dahliae infection, and triggered plant defence responses, including cell death in Nicotiana benthamiana. Deletion of VdFAE led to a decrease in the degradation of ethyl ferulate. VdFAE interacted with Gossypium hirsutum protein dihydroflavanol 4-reductase (GhDFR), a positive regulator in plant innate immunity, and promoted the degradation of GhDFR. Furthermore, silencing of GhDFR led to reduced resistance of cotton plants against V. dahliae. The results suggested a fungal virulence strategy in which a fungal pathogen secretes FAE to interact with host DFR and interfere with plant immunity, thereby promoting infection.

3'-Sialyllactose protects against LPS-induced endothelial dysfunction by inhibiting superoxide-mediated ERK1/2/STAT1 activation and HMGB1/RAGE axis

AIM

Endothelial hyperpermeability is an early stage of endothelial dysfunction associated with the progression and development of atherosclerosis. 3'-Sialyllactose (3'-SL) is the most abundant compound in human milk oligosaccharides, and it has the potential to regulate endothelial dysfunction. This study investigated the beneficial effects of 3'-SL on lipopolysaccharide (LPS)-induced endothelial dysfunction in vitro and in vivo.

MAIN METHODS

We established LPS-induced endothelial dysfunction models in both cultured bovine aortic endothelial cells (BAECs) and mouse models to determine the effects of 3'-SL. Western blotting, qRT-PCR analysis, immunofluorescence staining, and en face staining were employed to clarify underlying mechanisms. Superoxide production was measured by 2',7'-dichlorofluorescin diacetate, and dihydroethidium staining.

KEY FINDINGS

LPS significantly decreased cell viability, whereas 3'-SL treatment mitigated these effects via inhibiting ERK1/2 activation. Mechanistically, 3'-SL ameliorated LPS-induced ROS accumulation leading to ERK1/2 activation-mediated STAT1 phosphorylation and subsequent inhibition of downstream transcriptional target genes, including VCAM-1, TNF-α, IL-1β, and MCP-1. Interestingly, LPS-induced ERK1/2/STAT1 activation leads to the HMGB1 release from the nucleus into the extracellular space, where it binds to RAGE, while 3'-SL suppressed EC hyperpermeability by suppressing the HMGB1/RAGE axis. This interaction also led to VE-cadherin endothelial junction disassembly and endothelial cell monolayer disruption through ERK1/2/STAT1 modulation. In mouse endothelium, en face staining revealed that 3'-SL abolished LPS-stimulated ROS production and VCAM-1 overexpression.

SIGNIFICANCE

Our findings suggest that 3'-SL inhibits LPS-induced endothelial hyperpermeability by suppressing superoxide-mediated ERK1/2/STAT1 activation and HMGB1/RAGE axis. Therefore, 3'-SL may be a potential therapeutic agent for preventing the progression of atherosclerosis.

Neutrophils in Physiology and Pathology

Infections, cardiovascular disease, and cancer are major causes of disease and death worldwide. Neutrophils are inescapably associated with each of these health concerns, by either protecting from, instigating, or aggravating their impact on the host. However, each of these disorders has a very different etiology, and understanding how neutrophils contribute to each of them requires understanding the intricacies of this immune cell type, including their immune and nonimmune contributions to physiology and pathology. Here, we review some of these intricacies, from basic concepts in neutrophil biology, such as their production and acquisition of functional diversity, to the variety of mechanisms by which they contribute to preventing or aggravating infections, cardiovascular events, and cancer. We also review poorly explored aspects of how neutrophils promote health by favoring tissue repair and discuss how discoveries about their basic biology inform the development of new therapeutic strategies.