Reduced Reactive Oxygen Species Accumulation Research Articles

Oxidative Stress Regulates T Cell Pathogenicity in Gvhd

Allogeneic hematopoietic transplantation (allo-HCT) is a classic immunotherapy for hematologic malignances, but graft-versus-host disease (GVHD) remains a major cause of morbidity and mortality.Oxidative stress is considered as an unavoidable consequence of allo-HCT and could contribute to GVHD pathogenicity significantly. Owing to the contributions of pre-existing disease conditions and the requirement for conditioning regimens that increases cellular reactive oxygen species (ROS), oxidative stress is elevated in all BMT recipients. Thioredoxin (Trx) is ubiquitously expressed enzymes, counteracts oxidative stress by scavenging ROS and regulating other enzymes metabolizing H2O2. In addition, it has been shown that regulatory T cells (Tregs) express and secrete higher levels of Trx than conventional CD4 T cells. Trx-1 is critical for the resilience of Tregs to oxidative stress and sustained expression of surface thiols at a high density. We hypothesis that oxidative stress plays a critical role in the pathology of GVHD development, and thus the maintenance of a redox balance would be an effective strategy to control GVHD after allo-BMT.To test this hypothesis, we used a strain of mice that express transgenic (Tg) human Trx-1 ubiquitously, refer as Trx-Tg mice. We first verified that Trx-Tg T cells demonstrated significantly reduced ROS accumulation after activation in vitro and in vivo. We next sought to test whether Trx1 affects T cell activation and function. Upon alloantigen stimulation in vitro, Trx-Tg T cells have substantially reduced ability to produce IFN-γ compared with WT counterparts. These results prompted us to evaluate T cell responses in vivo . Upon transfer of T cells into irradiated allogeneic recipients, we observed that the Trx-Tg T cells significantly reduced proliferation and IFN-γ production compared with WT counterparts. Given that Trx-Tg T cells displayed a reduced allogeneic response in vitro and in vivo, we further hypothesized that Trx plays an essential role in regulating allogeneic T cells in GVHD. We performed a MHC-mismatched B6→BALB/c BMT model, and found that recipients of WT T cells developed severe and lethal GVHD, whereas the majority of the recipients of Trx-Tg T cells survived long term and had significantly less weight loss and lower clinical score. Development of GVHD requires donor T cell expansion in lymphoid organs and migration into target organs. Hence, we asked whether TRX-1 is required for T cell infiltration and expansion into target organs. Three weeks after BMT, we observed that recipients of Trx-Tg T cells had significantly fewer pathological injuries in all GVHD target organs, which was consistent with the GVHD outcome. While comparable numbers of Trx-Tg T and WT T cells were found in recipient spleens, a significantly lower number of Trx-Tg T cells were found in recipient livers as compared with that of WT T cells. In addition, T cells that migrated into the liver expressed significantly lower levels of intercellular IFN-γ in the Trx-Tg group. These data suggest that Trx-Tg T cells may reduce expansion and/or migration. For translational purpose, we evaluated therapeutic potential of recombinant human Trx-1 (rhTrx-1), and found that administration of recombinant human Trx-1 significantly reduced ability of T cells to produce IFN-γ compared with control treatment upon alloantigen stimulation in vivo . Furthermore, we performed a MHC-mismatched B6→BALB/c BMT model and found that administration of rhTrx-1had significantly reduced the mortality and mobility of BLAB/c recipients. Theraputic effect of rhTrx-1 in the prevention of GVHD was validated in a haploidentical BMT model (B6→BD2F1). More importantly, administration of rhTrx-1 did not impair the graft-versus-leukemia (GVL) against p815 tumor. Taken together, the current work provides a strong rationale and demonstrates the feasibility to target ROS pathway, which can be readily translated into clinic. DisclosuresNo relevant conflicts of interest to declare.

Yixin-Fumai granules improve sick sinus syndrome in aging mice through Nrf-2/HO-1 pathway: A new target for sick sinus syndrome

Ethnopharmacological relevanceYixin-Fumai granules (YXFMs)—composed of Ginseng quinquefolium (L.) Alph. Wood, Ophiopogon japonicus (Thunb.) Ker Gawl, Schisandra arisanensis Hayata, Astragalus aaronsohnianus Eig, Salvia cryptantha Montbret & Aucher ex Benth, and Ligusticum striatum DC—are compound granules used in traditional Chinese medicine to increase heart rate and thus treat bradyarrhythmia. It may be effective in treating sick sinus syndrome (SSS). AimTo observe the effect of YXFMs on aging-induced SSS in mice and explore whether this effect is related to the Nrf-2/HO-1 signaling pathway. Materials and methodsMice with a significant decrease in the heart rate due to natural aging were selected to construct an SSS model. After the mice were administered YXFMs, the damage to their sinoartrial node (SAN) was assessed through electrocardiography, Masson's trichrome staining, and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL). Dihydroethidium staining and immunofluorescence staining were used to assay reactive oxygen species (ROS) content and HCN4, respectively. Moreover, to observe the effects of YXFMs in vitro, the HL-1 cell line, derived from mouse atrial myocytes, was used to simulate SAN pacemaker cells, with H2O2 used as the cellular oxidative stress (OS) inducer. 2,7-Dichlorodihydrofluorescein diacetate staining was used to assay ROS content, whereas immunofluorescence staining and Western blotting were used to elucidate the related protein expression. Finally, mice were injected the Nrf-2 inhibitor ML385 to reversely verify the effects of YXFMs. ResultsIn our in vivo experiments, YXFMs significantly inhibited aging-induced SSS, shortened the R-R interval, increased heart rate, alleviated fibrosis, reduced apoptosis rate and ROS content, and promote HCN4 expression in the SAN. In our in vitro experiments, YXFMs significantly inhibited H2O2-induced cell peroxidation damage, promoted Nrf-2 activation and nuclear metastasis, increased HO-1 expression— thereby inhibiting ROS accumulation—and finally, upregulated HCN4 expression through the inhibition of histone deacetylase 4 (HDAC4) expression and its nuclear metastasis. Finally, injection of the Nrf-2 inhibitor ML385 after YXFMs administration inhibited their protective effect in the mice. ConclusionHere, we elaborated on the relationship between aging-induced SSS and the Nrf-2/HO-1 pathway for the first time and proposed that YXFMs improve SSS via the Nrf-2/HO-1 axis. Specifically, YXFMs promoted Nrf-2 activation and plasma–nuclear transfer to enhance HO-1 expression via the Nrf-2/HO-1 axis. This inhibited OS and reduced ROS accumulation in the SAN, and then, through the ROS/HDAC4 axis, reduced HDAC4 expression and plasma–nuclear transfer. Thereby, the OS-induced HCN4 loss in the SAN was inhibited—improving the function of If channel and thus producing SAN protection effect against SSS and improving the heart rate and R-R interval. In the future, we plan to use bioinformatics analysis technology to execute the next step of our research, namely to determine the effect of isolated, purified components of YXFMs in SSS, to increase its efficiency and reduce the toxicity of YXFMs.

Stress memory gene FaHSP17.8-CII controls thermotolerance via remodeling PSII and ROS signaling in tall fescue.

High temperature is the most limiting factor in the growth of cool-season turfgrass. To cope with high-temperature stress, grass often adopt a memory response by remembering one past recurring stress and preparing a quicker and more robust reaction to the next stress exposure. However, little is known about how stress memory genes regulate the thermomemory response in cool-season turfgrass. Here, we characterized a transcriptional memory gene, Fa-heat shock protein 17.8 Class II (FaHSP17.8-CII) in a cool-season turfgrass species, tall fescue (Festuca arundinacea Schreb.). The thermomemory of FaHSP17.8-CII continued for more than 4 d and was associated with a high H3K4me3 level in tall fescue under heat stress (HS). Furthermore, heat acclimation or priming (ACC)-induced reactive oxygen species (ROS) accumulation and photosystem II (PSII) electron transport were memorable, and this memory response was controlled by FaHSP17.8-CII. In the fahsp17.8-CII mutant generated using CRISPR/Cas9, ACC+HS did not substantially block the ROS accumulation, the degeneration of chloroplast ultra-structure, and the inhibition of PSII activity compared with HS alone. However, overexpression of FaHSP17.8-CII in tall fescue reduced ROS accumulation and chloroplast ultra-structure damage, and improved chlorophyll content and PSII activity under ACC+HS compared with that HS alone. These findings unveil a FaHSP17.8-CII-PSII-ROS module regulating transcriptional memory to enhance thermotolerance in cool-season turfgrass.

Nicotinamide Supplementation Improves Oocyte Quality and Offspring Development by Modulating Mitochondrial Function in an Aged Caenorhabditis elegans Model.

Aging is associated with a decline in the quality of biological functions. Among the aging processes, reproductive aging is a critical process because of its intergenerational effects. However, the mechanisms underlying reproductive aging remain largely unknown. Female reproductive aging is the primary reason for limited fertility in mammals. Therefore, we attempted to investigate a modulator that can control female reproductive aging using a Caenorhabditis elegans model. In the present study, we examined the role of nicotinamide (NAM) in oocyte quality and offspring development. The levels of reactive oxygen species (ROS) and oxidative stress responses in aged oocytes, embryonic lethality, and developmental growth of the offspring were examined with maternal NAM supplementation. Supplementation with NAM improved oocyte quality, decreased embryonic lethality, and promoted germ cell apoptosis. Furthermore, NAM supplementation in aged mothers reduced ROS accumulation and improved mitochondrial function in oocytes. Consequently, the developmental growth and motility of offspring were improved. These findings suggest that NAM supplementation improves the health of the offspring produced by aged mothers through improved mitochondrial function. Taken together, our results imply that NAM supplementation in the aged mother improves oocyte quality and protects offspring by modulating mitochondrial function.

CaDHN3, a Pepper (Capsicum annuum L.) Dehydrin Gene Enhances the Tolerance against Salt and Drought Stresses by Reducing ROS Accumulation

Dehydrins (DHNs) play an important role in abiotic stress tolerance in a large number of plants, but very little is known about the function of DHNs in pepper plants. Here, we isolated a Y1SK2-type DHN gene “CaDHN3” from pepper. To authenticate the function of CaDHN3 in salt and drought stresses, it was overexpressed in Arabidopsis and silenced in pepper through virus-induced gene silencing (VIGS). Sub-cellular localization showed that CaDHN3 was located in the nucleus and cell membrane. It was found that CaDHN3-overexpressed (OE) in Arabidopsis plants showed salt and drought tolerance phenotypic characteristics, i.e., increased the initial rooting length and germination rate, enhanced chlorophyll content, lowered the relative electrolyte leakage (REL) and malondialdehyde (MDA) content than the wild-type (WT) plants. Moreover, a substantial increase in the activities of antioxidant enzymes; including the superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), ascorbate peroxidase (APX), and lower hydrogen peroxide (H2O2) contents and higher O2•− contents in the transgenic Arabidopsis plants. Silencing of CaDHN3 in pepper decreased the salt- and drought-stress tolerance, through a higher REL and MDA content, and there was more accumulation of reactive oxygen species (ROS) in the CaDHN3-silenced pepper plants than the control plants. Based on the yeast two-hybrid (Y2H) screening and Bimolecular Fluorescence Complementation (BiFC) results, we found that CaDHN3 interacts with CaHIRD11 protein in the plasma membrane. Correspondingly, the expressions of four osmotic-related genes were significantly up-regulated in the CaDHN3-overexpressed lines. In brief, our results manifested that CaDHN3 may play an important role in regulating the relative osmotic stress responses in plants through the ROS signaling pathway. The results of this study will provide a basis for further analyses of the function of DHN genes in pepper.

Opa1 relies on cristae preservation and ATP synthase to curtail reactive oxygen species accumulation in mitochondria

Reactive oxygen species (ROS) are a common product of active mitochondrial respiration carried in mitochondrial cristae, but whether cristae shape influences ROS levels is unclear. Here we report that the mitochondrial fusion and cristae shape protein Opa1 requires mitochondrial ATP synthase oligomers to reduce ROS accumulation. In cells fueled with galactose to force ATP production by mitochondria, cristae are enlarged, ATP synthase oligomers destabilized, and ROS accumulate. Opa1 prevents both cristae remodeling and ROS generation, without impinging on levels of mitochondrial antioxidant defense enzymes that are unaffected by Opa1 overexpression. Genetic and pharmacologic experiments indicate that Opa1 requires ATP synthase oligomerization and activity to reduce ROS levels upon a blockage of the electron transport chain. Our results indicate that the converging effect of Opa1 and mitochondrial ATP synthase on mitochondrial ultrastructure regulate ROS abundance to sustain cell viability.

Transcription factor EB (TFEB)-mediated autophagy protects bovine mammary epithelial cells against H2O2-induced oxidative damage in vitro

BackgroundBovine mammary epithelial cells after calving undergo serious metabolic challenges and oxidative stress both of which could compromise autophagy. Transcription factor EB (TFEB)-mediated autophagy is an important cytoprotective mechanism against oxidative stress. However, effects of TFEB-mediated autophagy on the oxidative stress of bovine mammary epithelial cells remain unknown. Therefore, the main aim of the study was to investigate the role of TFEB-mediated autophagy in bovine mammary epithelial cells experiencing oxidative stress.ResultsH2O2 challenge of the bovine mammary epithelial cell MAC-T increased protein abundance of LC3-II, increased number of autophagosomes and autolysosomes while decreased protein abundance of p62. Inhibition of autophagy via bafilomycin A1 aggravated H2O2-induced reactive oxygen species (ROS) accumulation and apoptosis in MAC-T cells. Furthermore, H2O2 treatment triggered the translocation of TFEB into the nucleus. Knockdown of TFEB by siRNA reversed the effect of H2O2 on protein abundance of LC3-II and p62 as well as the number of autophagosomes and autolysosomes. Overexpression of TFEB activated autophagy and attenuated H2O2-induced ROS accumulation. Furthermore, TFEB overexpression attenuated H2O2-induced apoptosis by downregulating the caspase apoptotic pathway.ConclusionsOur results indicate that activation of TFEB mediated autophagy alleviates H2O2-induced oxidative damage by reducing ROS accumulation and inhibiting caspase-dependent apoptosis.

Aqueous extract of Whitmania pigra Whitman ameliorates ferric chloride-induced venous thrombosis in rats via antioxidation

Whitmania pigra Whitman (W. pigra) has been widely employed in decoction for the treatment of blood stasis syndrome for many years in China. The aim of the present study was to explore the anti-venous thrombosis (VT) mechanism of the aqueous extract of W. pigra (AEW) in rats. Rats were orally administered with AEW. A inferior vena cava (IVC) thrombosis model was established. Thrombosed IVC was weighed and histopathological analyses were performed. Blood coagulation, blood fibrinolysis, blood cell count, blood viscosity and platelet activity were evaluated. Reactive oxygen species (ROS) accumulation was analyzed. Malondialdehyde (MDA) content in thrombosed IVC and antioxidants in serum were detected. Protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase 1 (HO-1) in thrombosed IVC was determined. AEW significantly reduced thrombus weight. It did not affect blood coagulation, blood fibrinolysis, blood cell count, platelet activity, or whole blood viscosity. However, AEW remarkably alleviated vascular injury, reduced ROS accumulation and MDA content, enhanced the total antioxidant capacity and the activities of superoxide dismutase, glutathione peroxidase and glutathione reductase. It increased the glutathione/oxidized glutathione ratio and the protein expression levels of Nrf2 and HO-1. In summary, W. pigra may prevent VT via Nrf2-mediated antioxidation.

Hydrogen sulfide negatively regulates cd-induced cell death in cucumber (Cucumis sativus L) root tip cells

BackgroundHydrogen sulfide (H2S) is a gas signal molecule involved in regulating plants tolerance to heavy metals stress. In this study, we investigated the role of H2S in cadmium-(Cd-) induced cell death of root tips of cucumber seedlings.ResultsThe results showed that the application of 200 μM Cd caused cell death, increased the content of reactive oxygen species (ROS), chromatin condensation, the release of Cytochrome c (Cyt c) from mitochondria and activated caspase-3-like protease. Pretreatment of seedlings with 100 μM sodium hydrogen sulfide (NaHS, a H2S donor) effectively alleviated the growth inhibition and reduced cell death of root tips caused by Cd stress. Additionally, NaHS + Cd treatment could decrease the ROS level and enhanced antioxidant enzyme activity. Pretreatment with NaHS also inhibited the release of Cyt c from the mitochondria, the opening of the mitochondrial permeability transition pore (MPTP), and the activity of caspase-3-like protease in the root tips of cucumber seedling under Cd stress.ConclusionH2S inhibited Cd-induced cell death in cucumber root tips by reducing ROS accumulation, activating the antioxidant system, inhibiting mitochondrial Cyt c release and reducing the opening of the MPTP. The results suggest that H2S is a negative regulator of Cd-induced cell death in the root tips of cucumber seedling.

Volatile organic compounds produced by Aureobasidium pullulans induce electrolyte loss and oxidative stress in Botrytis cinerea and Alternaria alternata

Aureobasidium pullulans is a yeast-like fungus that produces volatile organic compounds (VOCs) with antifungal properties. VOCs have the potential to trigger the production of intracellular reactive oxygen species (ROS), lipid peroxidation and electrolyte loss in microorganisms. The relationship among A. pullulans VOCs, induced ROS accumulation and electrolyte leakage was investigated in Botrytis cinerea and Alternaria alternata in vitro. Exposure to a mixture of A. pullulans VOCs: ethanol, 2-methyl-1-propanol, 3-methyl-1-butanol and 2-phenylethanol, resulted in electrolyte leakage in both B. cinerea and A. alternata. Fluorescence microscopy using 2′,7′-dichlorofluorescein diacetate indicated triggered ROS accumulation in exposed fungal mycelia and the presence of the superoxide radical was evident by intense red fluorescence with dihydroethidium. Partial inhibition of enzymes of the mitochondrial respiratory chain complex I of B. cinerea and A. alternata by pre-treatment with rotenone reduced ROS accumulation in hypha exposed to A. pullulans VOCs and reversed the VOCs inhibition of fungal growth. Scanning electron micrographs revealed that B. cinerea and A. alternata hypha exposed to A. pullulans VOCs had altered cell wall structures. Our findings give insights into the potential mechanisms involved in the antifungal properties of A. pullulans in the suppression of B. cinerea and A. alternata growth in vitro.

Two Mn(II)-Organic Frameworks: Selective Detection of Fe3+ Ion and Treatment Activity on Alcohol-Induced Cerebellar Atrophy By Reducing ROS Accumulation in Brain

Under solvothermal reaction conditions, two new Mn(II)-containing meta-organic frameworks (MOFs) having the chemical formula of [Mn(bda) (L)·0.5H2O]n (1) and [Mn(Hdda)2(L)·4H2O)]n (2) were prepared via a mixed-ligand method using different aromatic dicarboxylic acids ligands (H2bda = benzopheno-4,4-dicarboxylic acid, H2dda = 1,2-diethyl ether-4,4′-dibenzoic acid) and the flexible 1,3-di(1 h-imidazol-1-yl)propane (L). Meanwhile, it is further demonstrated that complex 1 with excellent water stability can be used for a promising sensor for Fe3+ ions in aqueous solution, which has good selectivity and sensitivity. For the treatment of the alcohol-induced cerebellar atrophy, the accumulation of reactive oxygen species (ROS) in purkinje cells was evaluated by 2′,7′-dichlorofluorescin diacetate (DCFH-DA) assay. Besides, through real time reverse transcription-polymerase chain reaction (RT-PCR), the relative expression of ROS related gene in purkinje cells was detected.

Red light optimized physiological traits and enhanced the growth of ramie (Boehmeria nivea L.)

Light is an important variable affecting the plant growth. In present study, the effects of different color light-emitting diodes (mixed colors, red, blue, and orange light) on plant growth, gas exchange, and oxidative stress were investigated in Boehmeria nivea L., by means of measuring growth, photosynthesis, chlorophyll (Chl) content, reactive oxygen species (ROS), and activity of antioxidant enzymes under controlled conditions. Comparing to the mixed colors light, red light significantly increased shoot and leaf biomass, plant height, number of leaves per plant, and stem diameter by increasing the Chl content and therefore promoting the highest photosynthetic capacity. This might partially be explained by the decrease of malondialdehyde and proline contents as well as the activities of superoxide dismutase and peroxidase under red light, to keep a better internal environment of the cell. However, blue and orange light decreased plant growth, and increased the activities of antioxidant enzymes which suggest an environmental stress on plants. These results suggest that red light can enhance B. nivea growth by activating photosynthesis and reducing ROS accumulation.

Oxidative Stress and Vascular Dysfunction in the Retina: Therapeutic Strategies

Many retinal diseases, such as diabetic retinopathy, glaucoma, and age-related macular (AMD) degeneration, are associated with elevated reactive oxygen species (ROS) levels. ROS are important intracellular signaling molecules that regulate numerous physiological actions, including vascular reactivity and neuron function. However, excessive ROS formation has been linked to vascular endothelial dysfunction, neuron degeneration, and inflammation in the retina. ROS can directly modify cellular molecules and impair their function. Moreover, ROS can stimulate the production of inflammatory cytokines, such as tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) causing inflammation and cell death. However, there are various compounds with direct or indirect antioxidant activity that have been used to reduce ROS accumulation in animal models and humans. In this review, we report on the physiological and pathophysiological role of ROS in the retina with a special focus on the vascular system. Moreover, we present therapeutic approaches for individual retinal diseases targeting retinal signaling pathways involving ROS.

Curcumin-laden exosomes target ischemic brain tissue and alleviate cerebral ischemia-reperfusion injury by inhibiting ROS-mediated mitochondrial apoptosis.

The pathogenesis of ischemic cerebrovascular disease has revealed that ischemia-reperfusion (I/R) injury often leads to aggravation of metabolic oxidative stress and blood-brain barrier (BBB) destruction, eventually causing secondary brain tissue damage. Accumulated reactive oxygen species (ROS) in focal ischemia activate mitochondria-mediated apoptosis and damage the BBB by degrading tight junction proteins (TJPs). Herein, we report macrophage-derived exosomes (Ex) loaded with curcumin (cur) as a multifunctional biomimetic delivery vehicle (Ex-cur) for targeting ischemic brain tissue and alleviating cerebral I/R injury by inhibiting ROS-mediated mitochondrial apoptosis in a transient cerebral ischemia rat model. The design principle relies on unique features of macrophage-derived exosomes and the natural ingredient cur. Specifically, cur can be entrapped within exosomes when incubated with murine macrophage RAW264.7 cells, and its stability is subsequently significantly improved. The resultant Ex-cur can target ischemic regions by leveraging the targeting migration capability of Ex driven by inflammation. Accumulated Ex-cur in ischemic regions is experimentally proven to be highly effective at reducing ROS accumulation by virtue of the antioxidant properties of cur. Using Ex-cur to down-regulate ROS accumulation in lesions, we alleviate BBB damage and suppress mitochondria-mediated neuronal apoptosis, which is confirmed by a series of relevant protein analysis. These findings demonstrate good therapeutic efficacy of Ex-cur for treating I/R injury, providing experimental evidence for the potential clinical benefits of Ex-cur for other modes of neuroprotection.

Two Co(II) coordination polymers: treatment activity on myocardial injury during sepsis via reducing ROS accumulation in the cardiomyocytes

Two coordination polymers on the basis of distinct nitrogen-donor ligands and biphenyl-2,2′,5,5′-tetracarboxylic acid H4(o,m-bpta), {[Co2(o,m-bpta)(1,3-bimb)2]·DMF·2H2O}n (1) {1,3-bimb = [1,3-phenylenebis(methylene)]bis(1H-imidazole)} and {[Co2(o,m-bpta)(1,4-bimb)2]·H2O}n (2) {1,4-bimb = [1,4-phenylenebis(methylene)]bis(1H-imidazole)} were prepared under solvothermal conditions. These two complexes were then characterized through single-crystal X-ray diffraction, elemental analysis, IR spectroscopy and thermogravimetric (TG) analysis as well as the analysis of powder X-ray diffraction (PXRD). Compounds 1 and 2 were then studied to develop new candidates for the sepsis treatment and myocardial injury prevention. The reactive oxygen species (ROS) accumulation in the cardiomyocytes was detected with indicated kit and the enzyme linked immunosorbent assay (ELISA) test kit was conducted for the inflammatory cytokines evaluation.

Hydrogen Sulfide Alleviates Waterlogging-Induced Damage in Peach Seedlings via Enhancing Antioxidative System and Inhibiting Ethylene Synthesis.

Peach (Prunus persica L. Batsch) is a shallow root fruit tree with poor waterlogging tolerance. Hydrogen sulfide (H2S) is a signal molecule which regulates the adaptation of plants to adverse environments. Nevertheless, the effects of exogenous applications of H2S in fruit tree species especially in peach trees under waterlogging stress have been scarcely researched. Thus, the goal of this research was to investigate the alleviating effect of exogenous H2S on peach seedlings under waterlogging stress. In the present study, we found that the effect of exogenous H2S depended on the concentration and 0.2 mM sodium hydrosulfide (NaHS) showed the best remission effect on peach seedlings under waterlogging stress. Waterlogging significantly reduced the stomatal opening, net photosynthetic rate, and Fv/Fm of peach seedlings. The results of histochemical staining and physiological and biochemical tests showed that waterlogging stress increased the number of cell deaths and amounts of reactive oxygen species (ROS) accumulated in leaves, increased the number of root cell deaths, significantly increased the electrolyte permeability, O2.– production rate, H2O2 content and ethylene synthesis rate of roots, and significantly reduced root activity. With prolonged stress, antioxidative enzyme activity increased initially and then decreased. Under waterlogging stress, application of 0.2 mM NaHS increased the number of stomatal openings, improved the chlorophyll content, and photosynthetic capacity of peach seedlings. Exogenous H2S enhanced antioxidative system and significantly alleviate cell death of roots and leaves of peach seedlings caused by waterlogging stress through reducing ROS accumulation in roots and leaves. H2S can improve the activity and proline content of roots, reduce oxidative damage, alleviated lipid peroxidation, and inhibit ethylene synthesis. The H2S scavenger hypotaurine partially eliminated the effect of exogenous H2S on alleviating waterlogging stress of peach seedlings. Collectively, our results provide an insight into the protective role of H2S in waterlogging-stressed peach seedlings and suggest H2S as a potential candidate in reducing waterlogging-induced damage in peach seedlings.

A prodrug of epigallocatechin-3-gallate alleviates high glucose-induced pro-angiogenic factor production by inhibiting the ROS/TXNIP/NLRP3 inflammasome axis in retinal Müller cells

Diabetic retinopathy (DR) is a neurovascular complication of diabetes mellitus that leads to blindness in the working-age population. Retinal Müller cells proliferate and produce pro-angiogenic factors, including vascular endothelial growth factor (VEGF) and hepatocyte growth factor (HGF), via the reactive oxygen species (ROS)/thioredoxin interacting protein (TXNIP)/NACHT, LRR and PYD domain-containing protein 3 (NLRP3) inflammasome axis to promote proliferative DR. Epigallocatechin-3-gallate (EGCG) plays anti-oxidant, anti-inflammatory, anti-proliferative and anti-angiogenic roles in Müller cells. A prodrug of EGCG (pro-EGCG) enhances the bioavailability of EGCG. In an in vitro model of high glucose-stimulated Müller cells, pro-EGCG inhibited proliferation and pro-angiogenic factor production by down-regulating the activity of the ROS/TXNIP/NLRP3 inflammasome axis. In a mouse DR model, pro-EGCG reduced ROS accumulation, NLRP3 inflammasome activation, Müller cell proliferation, and production of the pro-angiogenic factors VEGF and HGF. In summary, pro-EGCG mitigated hyperglycaemia-challenged Müller cell proliferation and pro-angiogenic factor production by inhibiting ROS/TXNIP/NLRP3 inflammasome signalling, implying a potential therapeutic strategy for DR.

Transgenerational benefits of endophytes on resilience and antioxidant genes expressions in pea (Pisum sativum L.) under osmotic stress

Water shortage adversely affects many vital physiological processes in plants. In this study, we present the benefit of plant endophytic fungi and bacteria on endophyte-free second-generation Pisum sativum L. seeds arising from drought-stressed plants. Germination percentage, root and shoot length, reactive oxygen species (ROS) accumulation, antioxidant gene expression and protein content was examined in the F2 generation of pea (CDC Golden). The IOP-PDA and PEG media increased water stress, osmotic pressure and dehydration, respectively, to plants grown in vitro. The transgenerational endophyte-mediated benefits to pea can be appreciated by improved seed germination and reduced ROS accumulation levels in plant-roots. qPCR of antioxidants in leaves revealed downregulated proline, superoxide dismutase (SOD), and manganese superoxide dismutase (MnSOD) genes under water-deficient conditions. This finding implies that endophytes can improve pea’s resilience to abiotic stresses. The protein content increased in seeds produced from F1 plants colonized by endophytic Penicilium SMCD2206, Paraconiothyrium SMCD2210 and Streptomyces sp. SMCD2215 strains compared to endophyte-free plants. The results provide new insights into understanding leguminous plant–endophyte interactions under stress. The mechanisms by which transgenerational endophyte-mediated resilience in plants merit further studies under natural field conditions.

Delphinidin attenuates pathological cardiac hypertrophy via the AMPK/NOX/MAPK signaling pathway.

Reactive oxygen species (ROS) play a pivotal role in the development of pathological cardiac hypertrophy. Delphinidin, a natural flavonoid, was reported to exert marked antioxidative effects. Therefore, we investigated whether delphinidin ameliorates pathological cardiac hypertrophy via inhibiting oxidative stress. In this study, male C57BL/6 mice were treated with DMSO or delphinidin after surgery. Neonatal rat cardiomyocytes (NRCMs) were treated with angiotensin II (Ang II) and delphinidin in vitro. Eighteen-month-old mice were administered delphinidin to investigate the effect of delphinidin on aging-related cardiac hypertrophy. Through analyses of hypertrophic cardiomyocyte growth, fibrosis and cardiac function, delphinidin was demonstrated to confer resistance to aging- and transverse aortic constriction (TAC)-induced cardiac hypertrophy in vivo and attenuate Ang II-induced cardiomyocyte hypertrophy in vitro by significantly suppressing hypertrophic growth and the deposition of fibrosis. Mechanistically, delphinidin reduced ROS accumulation upon Ang II stimulation through the direct activation of AMP-activated protein kinase (AMPK) and subsequent inhibition of the activity of Rac1 and expression of p47phox. In addition, excessive levels of ERK1/2, P38 and JNK1/2 phosphorylation induced by oxidative stress were abrogated by delphinidin. Delphinidin was conclusively shown to repress pathological cardiac hypertrophy by modulating oxidative stress through the AMPK/NADPH oxidase (NOX)/mitogen-activated protein kinase (MAPK) signaling pathway.

Ketamine attenuates high-glucose-mediated endothelial inflammation in human umbilical vein endothelial cells.

Hyperglycemia mediates oxidative stress, thus inducing transcription factor nuclear factor kappa B (NF-κB) activation, increasing endothelial adhesion molecule expression and monocyte/endothelial interaction, and resulting in endothelial injury. Ketamine was reported to attenuate oxidative stress in many cases. In this research, we determined whether and how ketamine protects against high-glucose-mediated augmentation of monocyte/endothelial interaction and endothelial adhesion molecule expression in human umbilical vein endothelial cells. High glucose augmented monocyte/endothelial adhesion and endothelial adhesion molecule expression. High glucose induced reactive oxygen species (ROS) production and augmented phospho-protein kinase C (p-PKC) βII expression and PKC activity. Moreover, high glucose inhibited the inhibitory subunit of nuclear factor-κBα (IκBα) expression in the cytoplasm and induced NF-κB nuclear translocation. Importantly, the effects induced by high glucose were counteracted by ketamine treatment. Further, CGP53353, a PKC βII inhibitor, inhibited high-glucose-mediated NF-κB nuclear translocation, attenuated adhesion molecule expression, and reduced monocyte/endothelial interaction. Further, these effects of ketamine against high-glucose-induced endothelial injury were inhibited by phorbol 12-myristate 13-acetate, a PKC βII activator. In conclusion, ketamine, via reducing ROS accumulation, inhibited PKC βII Ser660 phosphorylation and PKC and NF-κB activation and reduced high-glucose-induced expression of endothelial adhesion molecules and monocyte/endothelial interaction.