Reactive Oxygen Species Production Research Articles

Subfamily C7 Raf-like kinases MRK1, RAF26, and RAF39 regulate immune homeostasis and stomatal opening in Arabidopsis thaliana.

The calcium-dependent protein kinase CPK28 regulates several stress pathways in multiple plant species. Here, we aimed to discover CPK28-associated proteins in Arabidopsis thaliana. We used affinity-based proteomics and identified several potential CPK28 binding partners, including the C7 Raf-like kinases MRK1, RAF26, and RAF39. We used biochemistry, genetics, and physiological assays to gain insight into their function. We define redundant roles for these kinases in stomatal opening, immune-triggered reactive oxygen species (ROS) production, and resistance to a bacterial pathogen. We report that CPK28 associates with and trans-phosphorylates RAF26 and RAF39, and that MRK1, RAF26, and RAF39 are active kinases that localize to endomembranes. Although Raf-like kinases share some features with mitogen-activated protein kinase kinase kinases (MKKKs), we found that MRK1, RAF26, and RAF39 are unable to trans-phosphorylate any of the 10 Arabidopsis mitogen-activated protein kinase kinases (MKKs). Overall, our study suggests that C7 Raf-like kinases associate with and are phosphorylated by CPK28, function redundantly in stomatal opening and immunity, and possess substrate specificities distinct from canonical MKKKs.

A cocktail of Cu2+- and Zn2+-peptoid-based chelators can stop ROS formation for Alzheimer's disease therapy.

The formation of reactive oxygen species (ROS) in the brain is a major cause of neuropathologic degradation associated with Alzheimer's Disease (AD). It has been suggested that the copper (Cu)-amyloid-β (Aβ) peptide complex can lead to ROS formation in the brain. An external chelator for Cu that can extract Cu from the CuAβ complex should inhibit the formation of ROS, making Cu chelation an excellent therapeutic approach for AD. Such a chelator should possess high selectivity for Cu over zinc (Zn), which is also present within the synaptic cleft. However, such selectivity is generally hard to achieve in one molecule due to the similarities in the binding preferences of these two metal ions. As an alternative to monotherapy (where Cu extraction is performed using a single chelator), herein we describe a variation of combination therapy - a novel cocktail approach, which is based on the co-administration of two structurally different peptidomimetic chelators, aiming to target both Cu2+ and Zn2+ ions simultaneously but independently from each other. Based on rigorous spectroscopic experiments, we demonstrate that our peptidomimetic cocktail allows, for the first time, the complete and immediate inhibition of ROS production by the CuAβ complex in the presence of Zn2+. In addition, we further demonstrate the high stability of the cocktail under simulated physiological conditions and its resistance to proteolytic degradation by trypsin and report the water/n-octanol partition coefficient, initially assessing the blood-brain barrier (BBB) permeability potential of the chelators.

Ginsenoside Rg3 Improved Age-Related Macular Degeneration Through Inhibiting ROS-Mediated Mitochondrion-Dependent Apoptosis In Vivo and In Vitro.

Age-related macular degeneration (AMD) is marked by a progressive loss of central vision and is the third leading cause of irreversible blindness worldwide. The exact mechanisms driving the progression of this macular degenerative condition remain elusive, and as of now, there are no available preventative measures for dry AMD. According to ancient records, ginseng affects the eyes by brightening them and enhancing wisdom. Modern pharmacological research shows that the active ingredients in ginseng, ginsenosides, may be used to prevent or improve eye diseases that threaten vision. Some articles have reported that ginsenoside Rg3 can treat diabetic retinopathy in mice, but no reports exist on its effects and mechanisms in AMD. Therefore, the role and mechanism of ginsenoside Rg3 in AMD warrant further study. This study aims to investigate the effects of Rg3 on AMD and its underlying molecular mechanisms. We established a mouse model of AMD to examine the impact of ginsenoside Rg3 on NaIO3-induced apoptosis in the retina and to explore the related intrinsic mechanisms. The in vivo results indicated that ginsenoside Rg3 prevents NaIO3-induced apoptosis in retinal pigment epithelial cells by inhibiting reactive oxygen species production and preventing the reduction in mitochondrial membrane potential. Additionally, we assessed the levels of protein expression within the apoptosis pathway. Ginsenoside Rg3 decreased the expression of Bax, cleaved caspase-3, and cleaved caspase-9 proteins. Additionally, it increased the expression of Bcl-2 by decreasing P-JNK levels. Moreover, our in vivo results showed that ginsenoside Rg3 enhanced retinal structure, increased the relative thickness of the retina, and decreased the extent of disorganization in both the inner and outer nuclear layers. Ginsenoside Rg3 may safeguard the retina against NaIO3-induced cell apoptosis by attenuating reactive-oxygen-species-mediated mitochondrial dysfunction, in which the JNK signaling pathway is also involved. These findings suggest that ginsenoside Rg3 has the potential to prevent or attenuate the progression of AMD and other retinal pathologies associated with NaIO3-mediated apoptosis.

Antioxidant effect and inhibitory effect on nitric oxide production of sea mustard fractions from Busan, Korea

We investigated the chemical characteristics and nitric oxide (NO) production and antioxidant effects of sea mustard (Undaria pinnatifida) fractions obtained from Taejongdae in Busan, Korea. Dried sea mustard was extracted using different solvents, and antioxidant effects was evaluated based on the radical scavenging and DNA oxidation assays and the effect on reactive oxygen species (ROS) production. Total phenolic content was significantly higher in the 85% aq. MeOH fraction than that in the other factions. The 85% aq. MeOH fraction was more effective in scavenging free radicals than other fractions, as assessed by 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2.2'-azino-bis (3-ethylbenothiazoline-6-sulfonic acid) diammonium salt radical cation (ABTS) assays (P<0.05). All sea mustard fractions decreased H2O2-induced cellular ROS production compared to the control (P<0.05), however, the 85% aq. MeOH fraction exhibited the greatest inhibitory effect on ROS production among all fractions. Moreover, the 85% aq. MeOH fraction significantly inhibited genomic DNA oxidation. In addition, we measured NO levels to determine the potential anti-inflammatory effects of fractions from sea mustard and observed the highest level of activity in case of the 85% aq. MeOH fraction. These results indicated that the antioxidant effects of sea mustard are associated with its higher phenol content. This study proposes that processed food products supplemented with sea mustard can be developed into functional foods to promote the health of the local populations.

Metabolic dysfunction-associated steatotic liver disease-induced changes in the antioxidant system: a review.

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a heterogeneous condition characterized by liver steatosis, inflammation, consequent fibrosis, and cirrhosis. Chronic impairment of lipid metabolism is closely related to oxidative stress, leading to cellular lipotoxicity, mitochondrial dysfunction, and endoplasmic reticulum stress. The detrimental effect of oxidative stress is usually accompanied by changes in antioxidant defense mechanisms, with the alterations in antioxidant enzymes expression/activities during MASLD development and progression reported in many clinical and experimental studies. This review will provide a comprehensive overview of the present research on MASLD-induced changes in the catalytic activity and expression of the main antioxidant enzymes (superoxide dismutases, catalase, glutathione peroxidases, glutathione S-transferases, glutathione reductase, NAD(P)H:quinone oxidoreductase) and in the level of non-enzymatic antioxidant glutathione. Furthermore, an overview of the therapeutic effects of vitamin E on antioxidant enzymes during the progression of MASLD will be presented. Generally, at the beginning of MASLD development, the expression/activity of antioxidant enzymes usually increases to protect organisms against the increased production of reactive oxygen species. However, in advanced stage of MASLD, the expression/activity of several antioxidants generally decreases due to damage to hepatic and extrahepatic cells, which further exacerbates the damage. Although the results obtained in patients, in various experimental animal or cell models have been inconsistent, taken together the importance of antioxidant enzymes in MASLD development and progression has been clearly shown.

Enhancing Radiation-induced Reactive Oxygen Species Generation Through Mitochondrial Transplantation in Human Glioblastoma.

Glioblastoma (GBM) is the most aggressive primary brain malignancy in adults, with high recurrence rates and resistance to standard therapies. This study explores mitochondrial transplantation as a novel method to enhance the radiobiological effect (RBE) of ionizing radiation (IR) by increasing mitochondrial density in GBM cells, potentially boosting reactive oxygen species (ROS) production and promoting radiation-induced cell death. Using cell-penetrating peptides (CPPs), mitochondria were transplanted into GBM cell lines U3020 and U3035. Transplanted mitochondria were successfully incorporated into recipient cells, increasing mitochondrial density significantly. Mitochondrial chimeric cells demonstrated enhanced ROS generation post-irradiation, as evidenced by increased electron paramagnetic resonance (EPR) signal intensity and fluorescent ROS assays. The transplanted mitochondria retained functionality and viability for up to 14 days, with mitochondrial DNA (mtDNA) sequencing confirming high transfection and retention rates. Notably, mitochondrial transplantation was feasible in radiation-resistant GBM cells, suggesting potential clinical applicability. These findings support mitochondrial transplantation as a promising strategy to overcome therapeutic resistance in GBM by amplifying ROS-mediated cytotoxicity, warranting further investigation into its efficacy and mechanisms in vivo .

Maternal exposure to nanopolystyrene induces neurotoxicity in offspring through P53-mediated ferritinophagy and ferroptosis in the rat hippocampus

There are increasing concerns regarding the rapid expansion of polystyrene nanoplastics (PS-NPs), which could impact human health. Previous studies have shown that nanoplastics can be transferred from mothers to offspring through the placenta and breast milk, resulting in cognitive deficits in offspring. However, the neurotoxic effects of maternal exposure on offspring and its mechanisms remain unclear. In this study, PS-NPs (50 nm) were gavaged to female rats throughout gestation and lactation to establish an offspring exposure model to study the neurotoxicity and behavioral changes caused by PS-NPs on offspring. Neonatal rat hippocampal neuronal cells were used to investigate the pathways through which NPs induce neurodevelopmental toxicity in offspring rats, using iron inhibitors, autophagy inhibitors, reactive oxygen species (ROS) scroungers, P53 inhibitors, and NCOA4 inhibitors. We found that low PS-NPs dosages can cause ferroptosis in the hippocampus of the offspring, resulting in a decline in the cognitive, learning, and memory abilities of the offspring. PS-NPs induced NOCA4-mediated ferritinophagy and promoted ferroptosis by inciting ROS production to activate P53-mediated ferritinophagy. Furthermore, the levels of the antioxidant factors glutathione peroxidase 4 (GPX4) and glutathione (GSH), responsible for ferroptosis, were reduced. In summary, this study revealed that consumption of PS-NPs during gestation and lactation can cause ferroptosis and damage the hippocampus of offspring. Our results can serve as a basis for further research into the neurodevelopmental effects of nanoplastics in offspring.Graphical

Reactive oxygen species-responsive nano gel as a carrier, combined with photothermal therapy and photodynamic therapy for the treatment of brucellosis.

Brucellosis is an intracellular infectious disease that is primarily treated with antibacterial therapy. However, most antibacterial drugs struggle to penetrate the cell membrane and may be excluded or inactivated within the cell. In a recent study, researchers developed a nanogel coated with polydopamine (PDA) that responds to reactive oxygen species (ROS) and has enhanced adhesion properties. This nanogel encapsulates photosensitized zinc phthalocyanine (ZnPc) and an antibacterial drug, and is further modified with folic acid (FA) for active targeting. The resulting ROS-responsive nanogel, termed PDA@PMAA@ZnPc@DH-FA, can reach temperatures up to 50°C under near-infrared light, leading to a 72.1% improvement in drug release through increased ROS production. Cell staining confirmed a cell survival rate above 75%, with a low hemolysis rate of only 4.633%, indicating excellent biocompatibility. Furthermore, the study's results showed that the nanogel exhibited stronger killing effects against Brucella compared to administering the drug alone. Under near-infrared irradiation, the nanogel achieved a bacteriostatic rate of 99.8%. The combined approach of photothermal therapy and photodynamic therapy offers valuable insights for treating Brucella.

Accelerated Wound Healing of Tetrahedral-Framework Nucleic Acid Nanozymes with High Penetration and Antioxidant Capacity.

The wound repair process usually leads to a non-functioning mass of fibrotic tissue because of the oxidative imbalance of deep tissue layers. However, how to improve the penetration of active ingredients into deeper layers and regulate oxidative imbalances to create a regenerative microenvironment still remains a challenge. In this study, we designed a novel tetrahedral-framework nucleic acid (tFNA) nanozyme that could penetrate the skin/mucosa barrier as deep as 450 μm within 24 h. We also demonstrated the protective role of tFNAs on the mitochondrial structural and functional integrity and inhibition of reactive oxygen species production to repair oxidative imbalances through ERK1/2-Nrf2-HO-1 during repair processes. It was found that the proliferative state and the migration ability of postburn cells in vitro were accelerated, and the early closure of wounds in vivo was significantly promoted. This study therefore provides a promising strategy to efficiently regulate the oxidative imbalances in the deep layers of the skin during wound healing.

Balance of Antioxidants vs. Oxidants in Perinatal Asphyxia

Perinatal asphyxia refers to an acute event of cerebral ischemia and hypoxia during the perinatal period, leading to various degrees of brain injury. The mechanisms involved in perinatal asphyxia include the production of reactive oxygen species (ROS), accumulation of intracellular calcium, lipid peroxidation, excitatory amino acid receptor overactivation, energy failure, and caspase-mediated cell death. Both primary and secondary neuronal damage are caused by the overproduction of ROS following a hypoxic/ischemic event. ROS can react with nearly any type of molecule, including lipids, proteins, polysaccharides, and DNA. Neonates who suffer from perinatal asphyxia are prone to oxidative stress, which is characterized by a disruption in the oxidant/antioxidant balance, favoring oxidants over the intracellular and extracellular antioxidant scavenging mechanisms. Current research has focused on developing treatment strategies that potentially improve the endogenous antioxidant neuroprotective mechanisms or minimize injury resulting from hypoxia/ischemia. In this narrative review, we aim to present evidence regarding the contribution of oxidant/antioxidant balance to the pathogenesis and progression of perinatal asphyxia. Also, we aim to explore the role of potential antioxidant therapies as promising treatment strategies for perinatal asphyxia, especially as an adjunct to therapeutic hypothermia in infants with perinatal asphyxia. The current literature on antioxidant treatments in newborns is limited; however, allopurinol, melatonin, and erythropoietin have shown some positive effects in clinical trials. Inhibitors of nitric oxide synthase, N-acetylcysteine, and docosahexaenoic acid have shown promising neuroprotective effects in preclinical studies. Finally, nanotherapeutics could potentially modulate oxidative stress in hypoxemic/ischemic brain injury by targeted medication delivery. Future research on neuroprotectants and their processes is warranted to develop innovative treatments for hypoxia/ischemia in clinical practice.

Immunomodulatory hydrogel patches loaded with curcumin and tannic acid assembled nanoparticles for radiation dermatitis repair and radioprotection

Radiation dermatitis, as a major side effect of radiotherapy, is a form of skin injury linked to the production of reactive oxygen species (ROS). Development of functional patches with excellent ROS scavenging ability and biosafety is crucial for radioactive dermatitis repair. Herein, we present a nanohybrid hydrogel patch composed with natural-derived substances. The patch possesses dual functionalities of chemically scavenging ROS and physically absorbing radiation, thereby alleviating radiation damage. Curcumin@tannic acid (Cur@TA) nanoparticles are synthesized through spontaneous coordination of TA and iron ions (Fe3+), enabling the encapsulation of Cur. The nanoparticles are then loaded into gelatin methacryloyl (GelMA) hydrogel patches, which endow the hydrogel with tissue adhesion as well as photothermal properties. Simultaneously, the patch exhibits powerful ROS scavenging capability and promotes M2 polarization of macrophages. Additionally, the high-water content of the GelMA hydrogel enables physical absorption of low-energy X-rays, providing radiation shielding. Based on these characteristics, we have demonstrated the augmented therapeutic efficacy of the hydrogel patch loaded with Cur@TA nanoparticles in the mouse model of radiation dermatitis. Our findings introduce a novel therapeutic approach for radiation protection and treatment, with potential clinical applications.

Induced Resistance in Fruit and Vegetable Enhancing Host Defence to Curve Post-harvest Diseases

Induced resistance (IR) is an emerging, environmentally friendly strategy to manage post-harvest diseases in fruits and vegetables by enhancing the plant’s innate immune system. This approach leverages the plant's natural defense mechanisms, including the activation of defense-related enzymes like chitinases, glucanases, and peroxidases, accumulation of secondary metabolites such as phytoalexins and phenolics, and the strengthening of cell walls to prevent pathogen invasion. Additionally, the production of reactive oxygen species (ROS) plays a crucial role in both signaling and direct pathogen inhibition. Despite its potential, the effectiveness of IR varies across different crops and pathogens, and its success is heavily influenced by environmental factors, such as humidity, temperature, and light. There are also concerns regarding possible trade-offs, such as reduced yield or changes in fruit quality due to the diversion of energy towards defense responses. However, the integration of IR with other disease management strategies, including the use of biological control agents and conventional fungicides, has shown promising results in reducing post-harvest losses. Case studies in fruits like apples, tomatoes, and citrus, as well as vegetables like potatoes and peppers, demonstrate the practical applications of IR in commercial agriculture. Advances in genetic engineering are opening new pathways for enhancing IR by manipulating key genes involved in defense pathways, while new formulations and precision agriculture technologies offer greater control and efficiency in IR applications. These innovations, along with optimized post-harvest handling and storage practices, hold the potential to make IR a more reliable and sustainable solution for managing post-harvest diseases. However, ongoing research is necessary to address the variability in effectiveness and to explore long-term sustainability, especially as pathogens evolve and environmental conditions change. Induced resistance, when integrated with a comprehensive disease management approach, offers a significant step forward in reducing post-harvest losses and improving food security globally.

Assessment of quality and antioxidant capacity of peach in response to different UV-C dose irradiation.

The effects of different doses of UV-C irradiation (0, 0.5, 1.0, 2.0, and 4.0kJ m-2) on the quality and antioxidant capacity of peach fruit were examined. Results showed that irradiation at 2.0kJ m-2 led to higher firmness and total soluble solids, as well as lower weight loss and decay index. Additionally, peach fruits irradiated with 2.0kJ m-2 UV-C exhibited increased production of reactive oxygen species, which in turn stimulated the synthesis of total phenolics and total flavonoids and enhanced the activities of superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase. Overall, the best abiotic stress effect was observed with 2.0kJ m-2 UV-C irradiation, resulting in improved shelf quality and increased antioxidant capacity of peach fruits during storage. PRACTICAL APPLICATION: This study provides a theoretical basis for the application of UV-C irradiation in peach fruit preservation.

Inhibitory effect of Bacillus velezensis 1273 strain cell-free supernatant against developing and preformed biofilms of Staphylococcus aureus and MRSA

Microbial biofilms constitute a significant virulence factor and a substantial challenge in clinical environments due to their role in promoting antimicrobial resistance and their resilience to eradication efforts. Methicillin-resistant Staphylococcus aureus (MRSA) infections substantially increase healthcare costs, extend hospitalizations, and elevate morbidity and mortality rates. Therefore, developing innovative strategies to target and eliminate these bacteria and their biofilms effectively is imperative for robust epidemiological control. In this study, we evaluated the antibacterial and antibiofilm activities of cell-free supernatant (CFS) obtained from the Bacillus velezensis 1273 strain culture. Our data showed that CFS inhibited the growth of S. aureus ATCC 29213 and MRSA (clinical strain), with greater efficacy observed against S. aureus (1:16 dilution). Furthermore, CFS showed substantial potential in reducing biofilm formation in both strains (∼30 %) at subinhibitory concentrations. Additionally, the antibacterial activity against biofilm-formed cells showed that pure CFS treatment decreased the viability of S. aureus (60 %) and MRSA (45 %) sessile cells. We further demonstrated that CFS treatment induces the production of reactive oxygen species (ROS) and damages the membranes and cell walls of the pathogen cells. Genome analysis revealed the presence of genes encoding bacteriocins and secondary metabolites with antibacterial activity in the B. velezensis 1273 genome. These findings highlight the potential of probiotic bacterial metabolites as antibiofilm and anti-multidrug-resistant pathogens.

Neuroprotective Effects of Morin Against Cadmium- and Arsenic-Induced Cell Damage in PC12 Neurons.

Arsenic and cadmium, both toxic metals and widespread environmental pollutants, can trigger apoptosis and oxidative stress in various tissues and cells. Morin, a natural flavonoid with diverse biological properties, has been found to protect neurons from oxidative stress and apoptosis-induced damage. This research aimed to examine the protective properties of morin against neurotoxicity caused by arsenic and cadmium, utilizing PC12 cells as a model for nerve cells. The cells were pre-treated with different concentrations of morin and then exposed to arsenic and cadmium, after which cell viability and reactive oxygen species (ROS) production were assessed. Additionally, western blotting was performed to evaluate the protein levels of the Bax/Bcl-2 ratio and cleaved-caspase-3. Following exposure to arsenic and cadmium, there were significant increases in ROS, Bax/Bcl-2 ratio, and cleaved-caspase-3. However, the results of the study demonstrated the beneficial effects of morin at various concentrations, as it increased cell viability and decreased ROS production. Furthermore, morin at a concentration of 10 µM was found to reduce the elevated levels of cleaved-caspase-3 induced by arsenic and diminish the increased Bax/Bcl-2 ratio after exposure to arsenic and cadmium. The findings of this study suggest that morin can effectively protect cells from arsenic and cadmium-induced neurotoxicity through its antioxidant and anti-apoptotic effects. Thus, morin should be considered a promising agent for treating arsenic and cadmium toxicity.

Paeoniflorin alleviates toxicity and accumulation of 6-PPD quinone by activating ACS-22 in Caenorhabditis elegans

6-PPD quinone (6-PPDQ) is extensively existed in various environments. In Caenorhabditis elegans, exposure to 6-PPDQ could cause multiple toxic effects. In the current study, we further used C. elegans to investigate the effect of paeoniflorin (PF) treatment on 6-PPDQ toxicity and accumulation and the underlying mechanism. Treatment with PF (25–100 mg/L) inhibited 6-PPDQ toxicity on reproduction capacity and locomotion behavior and in inducing reactive oxygen species (ROS) production. Additionally, PF (25–100 mg/L) alleviated the dysregulation in expression of genes governing oxidative stress caused by 6-PPDQ exposure. Moreover, PF (25–100 mg/L) inhibited the enhancement in intestinal permeability caused by 6-PPDQ exposure and the accumulation of 6-PPDQ in the body of nematodes. In 6-PPDQ exposed nematodes, PF (25–100 mg/L) increased expression of acs-22 encoding a fatty acid transporter. RNAi of acs-22 could inhibit the beneficial effect of PF against 6-PPDQ toxicity in decreasing reproductive capacity and locomotion behavior, in inducing intestinal ROS production, and in enhancing intestinal permeability. RNAi of acs-22 could also suppress the PF beneficial effect against 6-PPDQ accumulation in the body of nematodes. Therefore, our results demonstrate the function of PF treatment against 6-PPDQ toxicity and accumulation in nematodes by activating the ACS-22.

Evidence for endogenous hydrogen peroxide production by E. coli fatty acyl-CoA dehydrogenase.

Aerobic organisms continuously generate internal superoxide and hydrogen peroxide, which can damage enzymes and impair growth. To avoid this problem cells maintain high levels of superoxide dismutases, catalases, and peroxidases. Surprisingly, we do not know the primary sources of these reactive oxygen species (ROS) in living cells. However, in vitro studies have shown that flavoenzymes can inadvertently transfer electrons to oxygen. Therefore, it seems plausible that substantial ROS may be generated when large metabolic fluxes flow through flavoproteins. Such a situation may arise during the catabolism of fatty acids. Acyl-CoA dehydrogenase (FadE) is a flavoprotein involved in each turn of the beta-oxidation cycle. In the present study the catabolism of dodecanoic acid specifically impaired the growth of strains that lack enzymes to scavenge hydrogen peroxide. The defect was absent from fadE mutants. Direct measurements confirmed that the beta-oxidation pathway amplified the rate of intracellular hydrogen peroxide formation. Scavenging-proficient cells did not display the FadE-dependent growth defect. Those cells also did not induce the peroxide stress response during dodecanoate catabolism, indicating that the basal defenses are sufficient to cope with moderately elevated peroxide formation. In vitro work still is needed to test whether the ROS evolve specifically from the FadE flavin site and to determine whether superoxide as well as peroxide is released. At present such experiments are challenging because the natural redox partner of FadE has not been identified. This study supports the hypothesis that the degree of internal ROS production can depend upon the type of active metabolism inside cells.

The impact of trauma relevant concentrations of prostaglandin E2 on the anti-microbial activity of the innate immune system.

The mechanisms underlying the state of systemic immune suppression that develops following major trauma are poorly understood. A post-injury increase in circulating levels of prostaglandin E2 (PGE2) has been proposed as a contributory factor, yet few studies have addressed how trauma influences PGE2 biology. Blood samples from 95 traumatically-injured patients (injury severity score ≥8) were collected across the pre-hospital (≤2 hours), acute (4-12 hours) and subacute (48-72 hours) post-injury settings. Alongside ex vivo assessments of lipopolysaccharide (LPS)-induced cytokine production by monocytes, neutrophil reactive oxygen species production and phagocytosis, serum concentrations of PGE2 and its scavenger albumin were measured, and the expression of enzymes and receptors involved in PGE2 synthesis and signalling analysed. Leukocytes from trauma patients were treated with cyclooxygenase (COX) inhibitors (indomethacin or NS-398), or the protein kinase A inhibitor H89, to determine whether injury-induced immune suppression could be reversed by targeting the PGE2 pathway. The effect that trauma relevant concentrations of PGE2 had on the anti-microbial functions of neutrophils, monocytes and monocyte-derived macrophages (MDMs) from healthy controls (HC) was examined, as was the effect of PGE2 on efferocytosis. To identify factors that may trigger PGE2 production post-trauma, leukocytes from HC were treated with mitochondrial-derived damage associated molecular patterns (mtDAMPs) and COX-2 expression and PGE2 generation measured. PGE2 concentrations peaked in blood samples acquired ≤2 hours post-injury and coincided with significantly reduced levels of albumin and impaired LPS-induced cytokine production by monocytes. Significantly higher COX-2 and phospholipase A2 expression was detected in neutrophils and/or peripheral blood mononuclear cells isolated from trauma patients. Treatment of patient leukocytes with indomethacin, NS-398 or H89 enhanced LPS-induced cytokine production and neutrophil extracellular trap generation. Exposure to physiological concentrations of PGE2 suppressed the anti-microbial activity of monocytes, neutrophils and MDMs of HC, but did not influence efferocytosis. In a formyl-peptide receptor-1 dependent manner, mtDAMP treatment significantly increased COX-2 protein expression in neutrophils and monocytes, which resulted in increased PGE2 production. Physiological concentrations of PGE2 suppress the anti-microbial activities of neutrophils, monocytes and MDMs. Targeting the PGE2 pathway could be a therapeutic approach by which to enhance innate immune function post-injury.

Mechanism of β-MnO2 particle for the peroxymonosulfate activation under electric field: the promoting effect of carbamazepine on Mn(III) and reactive oxygen species production

In this study, β-MnO2 was introduced into electro-peroxymonosulfate process as particle electrodes (E/PMS/β-MnO2) to reveal the pathway of reactive manganese species (RMnS) and its promoting effect on reactive oxygen species (ROS) production. A significant synergistic was observed in the E/PMS/β-MnO2 process, the reaction constant was 3 times higher than that in the E/PMS process. The mechanism experiments revealed the generation pathway of Mn(III)aq during the E/PMS/β-MnO2 process. The pyrophosphate complex experiments and electrochemical analysis demonstrated that Mn(III)aq was dominantly generated through the electron transfer between carbamazepine (CBZ) and Mn(IV) under electric field conditions, rather than the reduction process in the cathode area. Furthermore, quenching experiments and competition kinetics method demonstrated the production of Mn(III)aq has the potential to enhance the formation of reactive oxygen species (ROS), especially •OH and SO4•−. In addition, Mn(V)aq and Mn(VI)aq was proved unable to be produced during the E/PMS/β-MnO2 process. Different from other similar electrochemical studies, 1O2 was mainly generated by the reaction betweenO2•− and •OH in this research. It was observed that the inclusion of Cl— facilitated the removal of CBZ, whereas the addition of humic acid (HA) had negligible impact on CBZ removal during the E/PMS/β-MnO2 process. At last, the results of various water matrices effects and toxicology analysis showed that the E/PMS/β-MnO2 process has satisfactory performance in practical application. This study could provide new insights for electro-persulfate treatment processes.

The leucine-rich repeat receptor kinase QSK1 regulates PRR-RBOHD complexes targeted by the bacterial effector HopF2Pto.

Plants detect pathogens using cell-surface pattern recognition receptors (PRRs) such as ELONGATION Factor-TU (EF-TU) RECEPTOR (EFR) and FLAGELLIN SENSING 2 (FLS2), which recognize bacterial EF-Tu and flagellin, respectively. These PRRs belong to the leucine-rich repeat receptor kinase (LRR-RK) family and activate the production of reactive oxygen species via the NADPH oxidase RESPIRATORY BURST OXIDASE HOMOLOG D (RBOHD). The PRR-RBOHD complex is tightly regulated to prevent unwarranted or exaggerated immune responses. However, certain pathogen effectors can subvert these regulatory mechanisms, thereby suppressing plant immunity. To elucidate the intricate dynamics of the PRR-RBOHD complex, we conducted a comparative coimmunoprecipitation analysis using EFR, FLS2, and RBOHD in Arabidopsis thaliana. We identified QIAN SHOU KINASE 1 (QSK1), an LRR-RK, as a PRR-RBOHD complex-associated protein. QSK1 downregulated FLS2 and EFR abundance, functioning as a negative regulator of PRR-triggered immunity (PTI). QSK1 was targeted by the bacterial effector HopF2Pto, a mono-ADP ribosyltransferase, reducing FLS2 and EFR levels through both transcriptional and transcription-independent pathways, thereby inhibiting PTI. Furthermore, HopF2Pto transcriptionally downregulated PROSCOOP genes encoding important stress-regulated phytocytokines and their receptor MALE DISCOVERER 1-INTERACTING RECEPTOR-LIKE KINASE 2. Importantly, HopF2Pto requires QSK1 for its accumulation and virulence functions within plants. In summary, our results provide insights into the mechanism by which HopF2Pto employs QSK1 to desensitize plants to pathogen attack.