Endogenous Reactive Oxygen Species Generation Research Articles

Mitigation of Oxidative Stress in Idiopathic Pulmonary Fibrosis Through Exosome-Mediated Therapies.

Idiopathic pulmonary fibrosis (IPF) poses a formidable clinical challenge, characterized by the thickening of alveolar septa and the onset of pulmonary fibrosis. The pronounced activation of oxidative stress emerges as a pivotal hallmark of inflammation. Traditional application of exogenous antioxidants proves inadequate in addressing oxidative stress, necessitating exploration into strategies to augment their antioxidant efficacy. Exosomes, nano-sized extracellular vesicles harboring a diverse array of bioactive factors, present as promising carriers with the potential to meet this challenge. Recent attention has been directed towards the clinical applications of exosomes in IPF, fueling the impetus for this comprehensive review. We have compiled fresh insights into the role of exosomes in modulating oxidative stress in IPF and delved into their potential as carriers for regulating endogenous reactive oxygen species generation. This review endeavors to bridge the divide between exosome research and IPF, traversing from bedside to bench. Through the synthesis of recent findings, we propose exosomes as a novel and promising strategy for improving the outcomes of IPF therapy.

Injectable Hydrogel Loaded with CDs and FTY720 Combined with Neural Stem Cells for the Treatment of Spinal Cord Injury.

Spinal cord injury (SCI) is an incurable and disabling event that is accompanied by complex inflammation-related pathological processes, such as the production of excessive reactive oxygen species (ROS) by infiltrating inflammatory immune cells and their release into the extracellular microenvironment, resulting in extensive apoptosis of endogenous neural stem cells. In this study, we noticed the neuroregeneration-promoting effect as well as the ability of the innovative treatment method of FTY720-CDs@GelMA paired with NSCs to increase motor function recovery in a rat spinal cord injury model. Carbon dots (CDs) and fingolimod (FTY720) were added to a hydrogel created by chemical cross-linking GelMA (FTY720-CDs@GelMA). The basic properties of FTY720-CDs@GelMA hydrogels were investigated using TEM, SEM, XPS, and FTIR. The swelling and degradation rates of FTY720-CDs@GelMA hydrogels were measured, and each group's ability to scavenge reactive oxygen species was investigated. The in vitro biocompatibility of FTY720-CDs@GelMA hydrogels was assessed using neural stem cells. The regeneration of the spinal cord and recovery of motor function in rats were studied following co-treatment of spinal cord injury using FTY720-CDs@GelMA hydrogel in combination with NSCs, utilising rats with spinal cord injuries as a model. Histological and immunofluorescence labelling were used to determine the regeneration of axons and neurons. The recovery of motor function in rats was assessed using the BBB score. The hydrogel boosted neurogenesis and axonal regeneration by eliminating excess ROS and restoring the regenerative environment. The hydrogel efficiently contained brain stem cells and demonstrated strong neuroprotective effects in vivo by lowering endogenous ROS generation and mitigating ROS-mediated oxidative stress. In a follow-up investigation, we discovered that FTY720-CDs@GelMA hydrogel could dramatically boost NSC proliferation while also promoting neuronal regeneration and synaptic formation, hence lowering cavity area. Our findings suggest that the innovative treatment of FTY720-CDs@GelMA paired with NSCs can effectively improve functional recovery in SCI patients, making it a promising therapeutic alternative for SCI.

Periodontal ligament stem cell-derived exosome-loaded Emodin mediated antimicrobial photodynamic therapy against cariogenic bacteria

BackgroundThis study was conducted to investigate the efficiency of periodontal ligament (PDL) stem cell-derived exosome-loaded Emodin (Emo@PDL-Exo) in antimicrobial photodynamic therapy (aPDT) on Streptococcus mutans and Lactobacillus acidophilus as the cariogenic bacteria.Materials and methodsAfter isolating and characterizing PDL-Exo, the study proceeded to prepare and verify the presence of Emo@PDL-Exo. The antimicrobial effect, anti-biofilm activity, and anti-metabolic potency of Emo, PDL-Exo, and Emo@PDL-Exo were then evaluated with and without irradiation of blue laser at a wavelength of 405 ± 10 nm with an output intensity of 150 mW/cm2 for a duration of 60 s. In addition, the study assessed the binding affinity of Emodin with GtfB and SlpA proteins using in silico molecular docking. Eventually, the study examined the generation of endogenous reactive oxygen species (ROS) and changes in the gene expression levels of gelE and sprE.ResultsThe study found that using Emo@PDL-Exo-mediated aPDT resulted in a significant decrease in L. acidophilus and S. mutans by 4.90 ± 0.36 and 5.07 log10 CFU/mL, respectively (P < 0.05). The study found that using Emo@PDL-Exo for aPDT significantly reduced L. acidophilus and S. mutans biofilms by 44.7% and 50.4%, respectively, compared to untreated biofilms in the control group (P < 0.05). Additionally, the metabolic activity of L. acidophilus and S. mutans decreased by 58.3% and 71.2%, respectively (P < 0.05). The molecular docking analysis showed strong binding affinities of Emodin with SlpA and GtfB proteins, with docking scores of -7.4 and -8.2 kcal/mol, respectively. The study also found that the aPDT using Emo@PDL-Exo group resulted in the most significant reduction in gene expression of slpA and gtfB, with a decrease of 4.2- and 5.6-folds, respectively, compared to the control group (P < 0.05), likely due to the increased generation of endogenous ROS.DiscussionThe study showed that aPDT using Emo@PDL-Exo can effectively reduce the cell viability, biofilm activity, and metabolic potency of S. mutans and L. acidophilus. aPDT also significantly reduced the expression levels of gtfB and slpA mRNA due to the increased endogenous ROS generation. The findings suggest that Emo@PDL-Exo-mediated aPDT could be a promising antimicrobial approach against cariogenic microorganisms.

Evaluation of anti-biofilm effect of antimicrobial sonodynamic therapy-based periodontal ligament stem cell-derived exosome-loaded kojic acid on Enterococcus faecalis biofilm.

Introduction. Antimicrobial sonodynamic therapy (aSDT) is an approach that uses ultrasound waves (UWs) and a sonosensitizer to generate reactive oxygen species (ROS) to damage microbial cells in biofilms. Using nano-carriers, such as exosomes (Exos), to deliver the sonosensitizer can potentially enhance the effectiveness of aSDT.Hypothesis/Gap Statement. aSDT can downregulate the expression of gelE and sprE genes, increasing the production of endogenous ROS and degradation of pre-formed Enterococcus faecalis biofilms.Aim. This study investigated the anti-biofilm effect of aSDT-based periodontal ligament stem cell-derived exosome-loaded kojic acid (KA@PDL-Exo) on pre-formed E. faecalis biofilms in root canals.Methodology. Following the isolation and characterization of PDL-Exo, KA@PDL-Exo was prepared and confirmed. The minimal biofilm inhibitory concentration (MBIC) of KA, PDL-Exo, KA@PDL-Exo and sodium hypochlorite (NaOCl) was determined, and their anti-biofilm effects were assessed with and without UWs. The binding affinity of KA with GelE and SprE proteins was evaluated using in silico molecular docking. Additionally, the study measured the generation of endogenous ROS and evaluated changes in the gene expression levels of gelE and sprE.Results. The results revealed a dose-dependent decrease in the viability of E. faecalis cells within biofilms. KA@PDL-Exo was the most effective, with an MBIC of 62.5 µg ml-1, while NaOCl, KA and PDL-Exo had MBIC values of 125, 250 and 500 µg ml-1, respectively. The use of KA@PDL-Exo-mediated aSDT resulted in a significant reduction of the E. faecalis biofilm (3.22±0.36 log10 c.f.u. ml-1; P<0.05). The molecular docking analysis revealed docking scores of -5.3 and -5.2 kcal mol-1 for GelE-KA an SprE-KA, respectively. The findings observed the most significant reduction in gene expression of gelE and sprE in the KA@PDL-Exo group, with a decrease of 7.9- and 9.3-fold, respectively, compared to the control group (P<0.05).Conclusion. The KA@PDL-Exo-mediated aSDT was able to significantly reduce the E. faecalis load in pre-formed biofilms, decrease the expression of gelE and srpE mRNA, and increase the generation of endogenous ROS. These findings imply that KA@PDL-Exo-mediated aSDT could be a promising anti-biofilm strategy that requires additional in vitro and in vivo investigations.

Enhancement of hypericin nanoparticle-mediated sonoinduced disruption of biofilm and persister cells of Streptococcus mutans by dermcidin-derived peptide DCD-1L.

Streptococcus mutans is considered a major significant contributor to dental caries and its effective removal is difficult due to the formation of biofilm. Therefore, the development of adjuvant therapeutic strategies with anti-biofilm properties is a promising approach. In the present study, we examined the effect of dermcidin-derived peptide DCD-1L on the antibacterial activity of hypericin nanoparticle (HypNP)-mediated antimicrobial sonodynamic therapy (aSDT) against persister cells growing- and biofilm cultures of S. mutans. Following synthesis and confirmation of HypNP, the fractional inhibitory concentration (FIC) index of HypNP and DCD-1L was determined by checkerboard assay. Cellular uptake of HypNP-DCD-1L and generation of endogenous reactive oxygen species (ROS) were assessed and followed by the determination of antimicrobial sonoactivity of HypNP-DCD-1L against persister cells growing- and biofilm cultures of S. mutans. The water-insoluble extracellular polysaccharide (EPS) and expression of the gtfD, comDE, and smuT genes were then evaluated in persister cells growing- and biofilm cultures of S. mutans. There was a synergistic activity in the combination of HypNP and DCD-1L against S. mutans with an FIC index value of 0.37. The HypNP-DCD-1L-mediated aSDT also displayed the highest cellular uptake and endogenous ROS generation by bacterial cells. When biofilm and persister cells of S. mutans were treated with HypNP-DCD-1L and subsequently exposed to ultrasound waves, 5.1 log and 3.8 log reductions, respectively, in bacterial numbers were observed (P<0.05). According to the data, EPS in both persister cells growing- and biofilm cultures of S. mutans were significantly decreased after exposure to the HypNP-DCD-1L-mediated aSDT (P<0.05). In addition, the quantitative real-time PCR data illustrated the high level of similarities in very low-expression profiles of the gtfD before and after all treated groups for persister cells. While, following HypNP-DCD-1L-mediated aSDT treatment, the expression levels of gtfD, comDE, and smuT were significantly lower in treated persister cells growing- and biofilm cultures of S. mutans in comparison with control groups (P<0.05). Combined, the results of this study indicate that ultrasound waves-activated HypNP-DCD-1L can sonoinactivate S. mutans biofilms and persister cells, as well as reduce effectively pathogenicity potency of S. mutans. Hence, HypNP-DCD-1L-mediated aSDT may be proposed as a promising adjunctive therapeutic approach for dental caries.

Peroxiredoxin 2 is required for the redox mediated adaptation to exercise

Exercise generates a site-specific increase in Reactive Oxygen Species (ROS) within muscle that promotes changes in gene transcription and mitochondrial biogenesis, required for the beneficial adaptive response. We demonstrate that Peroxiredoxin 2 (Prdx2), an abundant cytoplasmic 2-Cys peroxiredoxin, is required for the adaptive hormesis response to physiological levels of H2O2 in myoblasts and following exercise in C. elegans. A short bolus addition of H2O2 increases mitochondrial capacity and improves myogenesis of cultured myoblasts, this beneficial adaptive response was suppressed in myoblasts with decreased expression of cytoplasmic Prdxs. Moreover, a swimming exercise protocol in C. elegans increased mitochondrial content, fitness, survival and longevity in wild type (N2) worms. In contrast, prdx-2 mutant worms had decreased fitness, disrupted mitochondria, reduced survival and lifespan following exercise. Global proteomics following exercise identified distinct changes in the proteome of N2 and prdx-2 mutants. Furthermore, a redox proteomic approach to quantify reversible oxidation of specific Cysteine residues revealed a more reduced redox state in the non-exercised prdx-2 mutant strain that become oxidized following exercise. In contrast, specific Cys residues from regulatory proteins become more reduced in the N2 strain following exercise, establishing the key regulatory role of PRDX-2 in a redox signalling cascade following endogenous ROS generation. Our results demonstrate that conserved cytoplasmic 2-Cys Peroxiredoxins are required for the beneficial adaptive response to a physiological redox stress.

Melatonin facilitates the deposition of suberin polyphenolic and lignin at wounds of potato tubers by mediating nitric oxide and reactive oxygen species

Melatonin (MT), a phytohormone, can enhance plant resistance against biotic and abiotic stresses. However, no studies have been conducted on whether MT influences suberin polyphenolic (SPP) and lignin deposition by mediating nitric oxide (NO) and reactive oxygen species (ROS). Herein, wounded tubers were treated with 50 μmol/L MT, and 25 μmol/L Nω-nitro-L-arginine (L-NNA), a specific inhibitor of nitric oxide synthase. We found that MT upregulated StNR (nitrate reductase) and StNOS (nitric oxide synthase) expression levels, and increased endogenous NO content. Additionally, MT upregulated StNOX (NADPH oxidase) expression and facilitated O2.- and H2O2 production. Moreover, MT upregulated relative expression and enhanced the activities of the main enzyme and products of the phenylpropanoid pathway, and increased peroxidase (POD) activity. MT also elevated the accumulation amount of suberin polyphenolic (SPP) and lignin at the wound tissues, resulting in less weight loss and disease index in wounded potatoes (cv. Atlantic) during healing. In contrast, L-NNA treatment suppressed the influence of MT on the generation of endogenous NO and ROS, the activity of phenylpropanoid metabolism and POD, and SPP and lignin accumulation at wounds. Taken together, MT could promote SPP and lignin deposition at wounds of potato tubers by inducing NO and ROS production and activating phenylpropanoid metabolism. However, L-NNA could eliminate the positive effect of MT.

Yeast Mannan-Rich Fraction Modulates Endogenous Reactive Oxygen Species Generation and Antibiotic Sensitivity in Resistant E. coli.

Mannan-rich fraction (MRF) isolated from Saccharomyces cerevisiae has been studied for its beneficial impact on animal intestinal health. Herein, we examined how MRF affected the formation of reactive oxygen species (ROS), impacting antibiotic susceptibility in resistant Escherichia coli through the modulation of bacterial metabolism. The role of MRF in effecting proteomic change was examined using a proteomics-based approach. The results showed that MRF, when combined with bactericidal antibiotic treatment, increased ROS production in resistant E. coli by 59.29 ± 4.03% compared to the control (p ≤ 0.05). We further examined the effect of MRF alone and in combination with antibiotic treatment on E. coli growth and explored how MRF potentiates bacterial susceptibility to antibiotics via proteomic changes in key metabolic pathways. Herein we demonstrated that MRF supplementation in the growth media of ampicillin-resistant E. coli had a significant impact on the normal translational control of the central metabolic pathways, including those involved in the glycolysis-TCA cycle (p ≤ 0.05).

Water-Soluble Tomato Concentrate, a Potential Antioxidant Supplement, Can Attenuate Platelet Apoptosis and Oxidative Stress in Healthy Middle-Aged and Elderly Adults: A Randomized, Double-Blinded, Crossover Clinical Trial.

Increased oxidative stress and platelet apoptotic in middle-aged and elderly adults are important risk factors for atherosclerotic cardiovascular disease (ASCVD). Therefore, it is of great significance to control the oxidative stress and platelet apoptosis in middle-aged and elderly adults. Previous acute clinical trials have shown that water-soluble tomato concentrate (WSTC) from fresh tomatoes could exert antiplatelet benefits after 3 h or 7 h, but its effects on platelet apoptosis and oxidative stress are still unknown, especially in healthy middle-aged and elderly adults. This current study aimed to examine the efficacies of WSTC on platelet apoptosis and oxidative stress in healthy middle-aged and elderly adults via a randomized double-blinded placebo-controlled crossover clinical trial (10 weeks in total). A total of 52 healthy middle-aged and elderly adults completed this trial. The results showed that WSTC could increase the serum total antioxidant capacity levels (p < 0.05) and decrease the serum malondialdehyde levels (p < 0.05) after a 4-week WSTC supplementation in healthy middle-aged and elderly adults. Platelet endogenous reactive oxygen species generation (p < 0.05), mitochondrial membrane potential dissipation (p < 0.05) and phosphatidylserine exposure (p < 0.05) were attenuated. In addition, our present study also found that WSTC could inhibit platelet aggregation and activation induced by collagen or ADP after intervention (p < 0.05), while having no effects on adverse events (p > 0.05). The results suggest that WSTC can inhibit oxidative stress and its related platelet apoptosis, which may provide a basis for the primary prevention of WSTC in ASCVD.

Quantitative Analysis for ROS-Producing Activity and Regulation of Plant NADPH Oxidases in HEK293T Cells.

Reactive oxygen species (ROS) produced by plant NADPH oxidases, respiratory burst oxidase homologs (RBOHs), play key roles in biotic and abiotic stress responses and development in plants. While properly controlled amounts of ROS function as signaling molecules, excessive accumulation of ROS can cause undesirable side effects due to their ability to oxidize DNA, lipids, and proteins. To limit the damaging consequences of unrestricted ROS accumulation, RBOH activity is tightly controlled by post-translational modifications (PTMs) and protein-protein interactions. In order to analyze these elaborate regulatory mechanisms, it is crucial to quantitatively assess the ROS-producing activity of RBOHs. Given the high endogenous ROS generation in plants, however, it can be challenging in plant cells to measure ROS production derived from specific RBOHs and to analyze the contribution of regulatory events for their activation and inactivation. Here we describe human embryonic kidney 293T (HEK293T) cells as a heterologous expression system and a useful tool to quantitatively monitor ROS production by RBOHs. This system permits the reconstitution of regulatory events to dissect the effects of Ca2+, phosphorylation, and protein-protein interactions on RBOH-dependent ROS production.

A sequential multistage-targeted nanoparticles for MR imaging and efficient chemo/chemodynamic synergistic therapy of liver cancer

The reasonable combination of chemotherapy and chemodynamic therapy has great potential in the treatment of cancer. In this study, a novel multifunctional nanoparticle (CDTLG NPs) with tumor tissue-cell-mitochondria-targeted, tumor-specific drug release and endogenous reactive oxygen species generation are developed for magnetic resonance imaging-guided liver cancer synergistic chemo/chemodynamic therapy. The CDTLG NPs are constructed via self-assembled of glutathione/pH-responsive prodrug, organic chemodynamic therapy agents, and magnetic resonance imaging contrast agents. Through passive targeted, the nanosized CDTLG NPs can accumulate in tumor tissue. After accumulating in hepatoma cells by active targeting, the CDTLG NPs could be destroyed under acidic and reductive intracellular environment to quickly release chemotherapy drugs doxorubicin, camptothecin, and organic chemodynamic therapy agents. Subsequently, due to mitochondrial targeting, organic chemotherapeutic drugs accumulate in the mitochondria of hepatoma cells and generate a large number of reactive oxygen species. The burst of endogenous reactive oxygen species and chemotherapy drugs release achieved synergistic chemo/chemodynamic therapy, which led to more severe cell death than monotherapies. Furthermore, the CDTLG NPs present outstanding in vivo antitumor ability without causing obvious in vivo toxicity. Thus, the study provides an intriguing strategy to chemo/chemodynamic combination therapy-based nanoparticles for enhancing antitumor efficacy.

The Anticancer Activity of Curcumin: A Literature Review

Cancer is the world's second largest cause of mortality and one of the most serious public health issues. Despite significant advancements in cancer treatment, cancer incidence and mortality rates remain high. Current research is still focused on developing more effective and less hazardous cancer treatment options. Curcumin has gotten a lot of press in the last two decades as an anti-oxidant, anti-inflammatory and cancer-fighting agent Curcumin modulated intracellular signaling pathways that affect tumor growth, angiogenesis, metastasis, inflammation, invasion, and apoptosis, among other things. Curcumin suppresses tumor cell growth and enhances apoptosis via upregulating the expression and activity of p53. Curcumin also has a strong inhibitory impact on the NFB and COX2 activity, which are involved in the upregulation of antiapoptotic genes like Bcl2. It can also reduce the control of antiapoptosis PI3K signaling and enhance MAPK expression, resulting in endogenous reactive oxygen species generation. The goal of this research is to review curcumin's anticancer properties.

Treatment of Oxidative Stress with Exosomes in Myocardial Ischemia.

A thrombus in a coronary artery causes ischemia, which eventually leads to myocardial infarction (MI) if not removed. However, removal generates reactive oxygen species (ROS), which causes ischemia–reperfusion (I/R) injury that damages the tissue and exacerbates the resulting MI. The mechanism of I/R injury is currently extensively understood. However, supplementation of exogenous antioxidants is ineffective against oxidative stress (OS). Enhancing the ability of endogenous antioxidants may be a more effective way to treat OS, and exosomes may play a role as targeted carriers. Exosomes are nanosized vesicles wrapped in biofilms which contain various complex RNAs and proteins. They are important intermediate carriers of intercellular communication and material exchange. In recent years, diagnosis and treatment with exosomes in cardiovascular diseases have gained considerable attention. Herein, we review the new findings of exosomes in the regulation of OS in coronary heart disease, discuss the possibility of exosomes as carriers for the targeted regulation of endogenous ROS generation, and compare the advantages of exosome therapy with those of stem-cell therapy. Finally, we explore several miRNAs found in exosomes against OS.

Mitochondrial alterations triggered by repeated exposure to fine (PM2.5-0.18) and quasi-ultrafine (PM0.18) fractions of ambient particulate matter

Nowadays ambient particulate matter (PM) levels still regularly exceed the guideline values established by World Health Organization in most urban areas. Numerous experimental studies have already demonstrated the airway toxicity of the fine fraction of PM (FP), mainly triggered by oxidative stress-induced airway inflammation. However, only few studies have actually paid close attention to the ultrafine fraction of PM (UFP), which is likely to be more easily internalized in cells and more biologically reactive. Mitochondria are major endogenous sources of reactive oxygen species (ROS) through oxidative metabolism, and coordinate many critical cellular signaling processes. Mitochondria have been often studied in the context of PM toxicity and generally associated with apoptosis activation. However, little is known about the underlying adaptation mechanisms that could occur following exposure at sub-apoptotic doses of ambient PM. Here, normal human bronchial epithelial BEAS-2B cells were acutely or repeatedly exposed to relatively low doses (5 µg.cm−2) of FP (PM2.5-0.18) or quasi-UFP (Q-UFP; PM0.18) to better access the critical changes in mitochondrial morphology, functions, and dynamics. No significant cytotoxicity nor increase of apoptotic events were reported for any exposure. Mitochondrial membrane potential (ΔΨm) and intracellular ATP content were also not significantly impaired. After cell exposure to sub-apoptotic doses of FP and notably Q-UFP, oxidative phosphorylation was increased as well as mitochondrial mass, resulting in increased production of mitochondrial superoxide anion. Given this oxidative boost, the NRF2-ARE signaling pathway was significantly activated. However, mitochondrial dynamic alterations in favor of accentuated fission process were observed, in particular after Q-UFP vs FP, and repeated vs acute exposure. Taken together, these results supported mitochondrial quality control and metabolism dysfunction as an early lung underlying mechanism of toxicity, thereby leading to accumulation of defective mitochondria and enhanced endogenous ROS generation. Therefore, these features might play a key role in maintaining PM-induced oxidative stress and inflammation within lung cells, which could dramatically contribute to the exacerbation of inflammatory chronic lung diseases. The prospective findings of this work could also offer new insights into the physiopathology of lung toxicity, arguably initiate and/or exacerbate by acutely and rather repeated exposure to ambient FP and mostly Q-UFP.

Elevated Inorganic Carbon Concentrating Mechanism Confers Tolerance to High Light in an Arctic Chlorella sp. ArM0029B.

Microalgae and higher plants employ an inorganic carbon (Ci) concentrating mechanism (CCM) to increase CO2 availability to Rubisco. Operation of the CCM should enhance the activity of the Calvin cycle, which could act as an electron sink for electrons generated by photosynthesis, and lower the redox status of photosynthetic electron transport chains. In this study, a hypothesis that microalgal cells with fully operating CCM are less likely to be photodamaged was tested by comparing a Chlorella mutant with its wild type (WT). The mutant acquired by screening gamma-ray-induced mutant libraries of Chlorella sp. ArM0029B exhibited constitutively active CCM (CAC) even in the presence of additional Ci sources under mixotrophic growth conditions. In comparison to the WT alga, the mutant named to constitutively active CCM1 (CAC1) showed more transcript levels for genes coding proteins related to CCM such as Ci transporters and carbonic anhydrases (CA), and greater levels of intracellular Ci content and CA activity regardless of whether growth is limited by light or not. Under photoinhibitory conditions, CAC1 mutant showed faster growth than WT cells with more PSII reaction center core component D1 protein (encoded by psbA), higher photochemical efficiency as estimated by the chlorophyll fluorescence parameter (Fv/Fm), and fewer reactive oxygen species (ROS). Interestingly, high light (HL)-induced increase in ROS contents in WT cells was significantly inhibited by bicarbonate supplementation. It is concluded that constitutive operation of CCM endows Chlorella cells with resistance to HL partly by reducing the endogenous generation of ROS. These results will provide useful information on the interaction between CCM expression, ROS production, and photodamage in Chlorella and related microalgae.

Intraplatelet reactive oxygen species (ROS) correlate with the shedding of adhesive receptors, microvesiculation and platelet adhesion to collagen during storage: Does endogenous ROS generation downregulate platelet adhesive function?

Platelets storage lesion is mainly orchestrated by platelet activating signals during storage. Reactive oxygen species (ROS) are being considered as important signaling molecules modulating platelet function while their production has also been shown to be augmented by platelet activation. This study investigated to what extent endogenous ROS generation during platelet storage could be correlated with platelet receptor shedding, microvesiculation and adhesive function.10 PRP-platelet concentrates were subjected to flow cytometry analysis to examine the generation of intraplatelet ROS on days 1, 5 and 7 after storage. In 5 day-stored platelets considering 40% of ROS generation as a cutoff point, samples were divided into two groups of those with higher or lower levels of ROS. The expression of adhesion receptors (GPVI, GPIbα), the amount of microparticles and phosphatidylserine exposure in each group were then examined by flow cytometry. Platelet receptor shedding and adhesion to collagen matrix were respectively measured by western blotting and microscopic assays.Our data showed lowered expression of GPIbα (p < 0.05) and GPVI in samples with ROS > 40% than those with ROS ≤ 40%, whereas receptors shedding and microvesiculation were (p < 0.05) elevated in platelets with higher levels of ROS. Functionally, we observed significantly (p < 0.05) lower levels of platelet adhesion to collagen matrix in samples with ROS generation more than 40%.Taken together, we showed correlations between intraplatelet ROS generation and either platelet receptors or microparticle shedding as well as platelet adhesive capacity to collagen. These findings suggest that augmented ROS generation during storage might be relevant to down-regulation of platelet adhesive function.

Roles of Heat Shock Proteins in Apoptosis, Oxidative Stress, Human Inflammatory Diseases, and Cancer.

Heat shock proteins (HSPs) play cytoprotective activities under pathological conditions through the initiation of protein folding, repair, refolding of misfolded peptides, and possible degradation of irreparable proteins. Excessive apoptosis, resulting from increased reactive oxygen species (ROS) cellular levels and subsequent amplified inflammatory reactions, is well known in the pathogenesis and progression of several human inflammatory diseases (HIDs) and cancer. Under normal physiological conditions, ROS levels and inflammatory reactions are kept in check for the cellular benefits of fighting off infectious agents through antioxidant mechanisms; however, this balance can be disrupted under pathological conditions, thus leading to oxidative stress and massive cellular destruction. Therefore, it becomes apparent that the interplay between oxidant-apoptosis-inflammation is critical in the dysfunction of the antioxidant system and, most importantly, in the progression of HIDs. Hence, there is a need to maintain careful balance between the oxidant-antioxidant inflammatory status in the human body. HSPs are known to modulate the effects of inflammation cascades leading to the endogenous generation of ROS and intrinsic apoptosis through inhibition of pro-inflammatory factors, thereby playing crucial roles in the pathogenesis of HIDs and cancer. We propose that careful induction of HSPs in HIDs and cancer, especially prior to inflammation, will provide good therapeutics in the management and treatment of HIDs and cancer.

RTP801 Amplifies Nicotinamide Adenine Dinucleotide Phosphate Oxidase-4-Dependent Oxidative Stress Induced by Cigarette Smoke.

Tobacco smoke (TS) causes chronic obstructive pulmonary disease, including chronic bronchitis, emphysema, and asthma. Rtp801, an inhibitor of mechanistic target of rapamycin, is induced by oxidative stress triggered by TS. Its up-regulation drives lung susceptibility to TS injury by enhancing inflammation and alveolar destruction. We postulated that Rtp801 is not only increased by reactive oxygen species (ROS) in TS but also instrumental in creating a feedforward process leading to amplification of endogenous ROS generation. We used cigarette smoke extract (CSE) to model the effect of TS in wild-type (Wt) and knockout (KO-Rtp801) mouse lung fibroblasts (MLF). The production of superoxide anion in KO-Rtp801 MLF was lower than that in Rtp801 Wt cells after CSE treatment, and it was inhibited in Wt MLF by silencing nicotinamide adenine dinucleotide phosphate oxidase-4 (Nox4) expression with small interfering Nox4 RNA. We observed a cytoplasmic location of ROS formation by real-time redox changes using reduction-oxidation-sensitive green fluorescent protein profluorescent probes. Both the superoxide production and the increase in the cytoplasmic redox were inhibited by apocynin. Reduction in the activity of Sod and decreases in the expression of Sod2 and Gpx1 genes were associated with Rtp801 CSE induction. The ROS produced by Nox4 in conjunction with the decrease in cellular antioxidant enzymatic defenses may account for the observed cytoplasmic redox changes and cellular damage caused by TS.

Hormetic shifting of redox environment by pro-oxidative resveratrol protects cells against stress

Resveratrol has gained tremendous interest owing to multiple reported health-beneficial effects. However, the underlying key mechanism of action of this natural product remained largely controversial. Here, we demonstrate that under physiologically relevant conditions major biological effects of resveratrol can be attributed to its generation of oxidation products such as reactive oxygen species (ROS). At low nontoxic concentrations (in general <50µM), treatment with resveratrol increased viability in a set of representative cell models, whereas application of quenchers of ROS completely truncated these beneficial effects. Notably, resveratrol treatment led to mild, Nrf2-specific gene expression reprogramming. For example, in primary epidermal keratinocytes derived from human skin this coordinated process resulted in a 1.3-fold increase of endogenously generated glutathione (GSH) and subsequently in a quantitative reduction of the cellular redox environment by 2.61mVmmol GSH per g protein. After induction of oxidative stress by using 0.78% (v/v) ethanol, endogenous generation of ROS was consequently reduced by 24% in resveratrol pre-treated cells. In contrast to the common perception that resveratrol acts mainly as a chemical antioxidant or as a target protein-specific ligand, we propose that the cellular response to resveratrol treatment is essentially based on oxidative triggering. In physiological microenvironments this molecular training can lead to hormetic shifting of cellular defense towards a more reductive state to improve physiological resilience to oxidative stress.

Changes in serum biochemical parameters and oxidative stress biomarkers in grazing cattle

In most parts of West Africa, ruminants graze through long distances in search of forage and water, especially when rainfall is inadequate. Grazing is an energy-utilizing activity involving contraction and relaxation of muscles by the transient interactions of actin and myosin, during which higher ATP is generated and consumed. Increased ATP generation could result in elevated endogenous reactive oxygen species generation, which could overwhelm cellular antioxidant capacity, resulting in oxidative stress. Although grazing is common in West Africa, there is a dearth of information on its effects on serum markers of tissue damage in ruminants, thus necessitating this study. In this study, blood was collected from healthy cows kept in a pen (non-grazing) for 1 week after which they were subjected to grazing for another week, to determine the effect of grazing on serum biochemical parameters and oxidative stress biomarkers. Grazing significantly increased (p < 0.05) serum aspartate aminotransferase, creatinine kinase, lactate dehydrogenase, albumin, bilirubin, and malondialdehyde levels with a concomitant decrease in glutathione levels in the animals when grazing compared to when kept in the pen. The results suggest that grazing increased reactive oxygen species production, possibly resulting in oxidative stress in the study animals.