ROS-induced Lipid Peroxidation Research Articles

Oxidative Stress and ROS Link Diabetes and Cancer

Type 2 diabetes mellitus (T2DM) accounts for one-sixth of deaths globally, whereas cancer is the second leading cause of death in the U.S. T2DM is a known risk factor for many cancers. Reactive oxygen species (ROS)-altered metabolic and signaling pathways link T2DM to cancer. These reprogrammed metabolic and signaling pathways contribute to diabetic complications, impact the redox balance (oxidative stress), and have differential roles in the early and late stages of cancer. A respiratory chain that is highly reduced (as under hyperglycemic conditions) or if reduced cofactors accumulate, ROS are greatly elevated. ROS may cause mutations in mitochondrial DNA (mtDNA) that result in further ROS elevations. The amplification of ROS results in the activation of PKC, an overarching signaling pathway that activates MAPK with a subsequent regulation in several factors that result in pathophysiological manifestations of T2DM and cancer. An upregulation in PKC leads to a deregulation in NF-kß, which regulates the PKB/P13/Akt pathway and orchestrates the cell survival, growth, proliferation, and glucose metabolism manifested in cancer. It also affects Insulin Receptor Substrate (IRS-1), decreasing insulin-stimulated glucose transport and glucose uptake, disrupting subsequent cell signaling pathways contributing to the development of T2DM. Dyslipidemia is a hallmark of T2DM and cancer. ROS-induced lipid peroxidation leads to systemic inflammation, producing inflammatory prostaglandins, cytokines, and chemokines that result in tumor proliferation, rapid tumor growth, and modulation of immunity. The dual role of ROS in the early and late stages of cancer makes antioxidant therapy precarious and may be responsible for controversial results. A system that delivers an antioxidant directly to mitochondria may be useful in inhibiting the formation of ROS early during the pre-diabetic stage, whereas antioxidant therapy must be halted in later stages to retard metastasis.

MACC1 knockdown enhances RSL3-induced ferroptosis in human colorectal cancer cells by inhibiting GPX4 expression

To investigate the effect of MACC1 on RSL3-induced ferroptosis in colorectal cancer cells and explore its molecular mechanism. MACC1 expression was detected in SW620, HCT116, LOVO and RKO cells using Western blotting. The effects of different concentrations of RSL3 (an inducer of ferroptosis) or Fer-1 (an inhibitor of ferroptosis) alone, or 10 μmol/L RLS3 combined with 10 μmol/L Fer-1, on viability of SW620 cells were examined using MTT assay. The survival of SW620 cells with mRNA interference of MACC1 was analyzed following treatment with RSL3, and RT-qPCR and Western blotting were performed to detect the changes in MACC1 expressions after RSL3 treatment at different concentrations and the changes in GPX4 expression after MACC1 knockdown. Flow cytometry and laser confocal microscopy were used to analyze the changes in ROS-induced lipid peroxidation in SW620 cells after MACC1 knockdown. SW620 cells had the highest MACC1 expression among the 4 colorectal cancer cell lines. Treatment with RSL3 significantly inhibited the viability of SW620 cells in a dose-dependent manner, while Fer-1 did not significantly affect the survival of SW620 cells. RSL3 alone reduced SW620 cell survival by 50% (P < 0.01), and the combined treatment with RSL3 and Fer-1 caused no significant changes in cell survival (P > 0.05). Treatment with RSL3 concentration-dependently suppressed MACC1 expressions at both the mRNA and protein levels in SW620 cells (P < 0.01). MACC1 knockdown obviously enhanced the cytotoxic effect of RSL3, inhibited the expression of GPX4, and increased ROS-induced lipid peroxidation in SW620 cells (P < 0.05). MACC1 knockdown enhances RSL3-induced ferroptosis in cultured colorectal cancer cells by inhibiting the expression of GPX4.

AKAP1 in Renal Patients with AHF to Reduce Ferroptosis of Cardiomyocyte.

This study mainly investigated the mechanism and effects of AKAP1 in renal patients with acute heart failure (AHF). Patients with renal patients with AHF and normal volunteers were collected. The left anterior descending arteries (LAD) of mice were ligated to induce myocardial infarction. AKAP1 messenger RNA (mRNA) expression was found to be down-regulated in renal patients with AHF. The serum levels of AKAP1 mRNA expression were negatively correlated with collagen I/III in patients. AKAP1 mRNA and protein expression in the heart tissue of mice with AHF were also found to be down-regulated in a time-dependent manner. Short hairpin (Sh)-AKAP1 promotes AHF in a mouse model. AKAP1 up-regulation reduces reactive oxygen species (ROS)-induced oxidative stress in an In Vitro model. AKAP1 up-regulation also reduces ROS-induced lipid peroxidation ferroptosis in an In Vitro model. AKAP1 induces NDUFS1 expression to increase GPX4 activity levels. AKAP1 protein interlinked with the NDUFS1 protein. Up-regulation of the AKAP1 gene reduced NDUFS1 ubiquitination, while down-regulation of the AKAP1 gene increased NDUFS1 ubiquitination in a model. In vivo imaging showed that the sh-AKAP1 virus reduced NDUFS1 expression in the heart of a mouse model. AKAP1 reduced ROS-induced lipid peroxidation ferroptosis through the inhibition of ubiquitination of NDUFS by mitochondrial damage in model of renal patients with AHF, suggest a novel target for AHF treatment.

Clinical evaluation of a novel gallotannin-enriched Galla Rhois extract (GRE) on vital cognitive functions in healthy volunteers: A randomized, double-blind, placebo-controlled study

Background: Oxidative damage has emerged as one of the significant factors in the onset of neurodegenerative disorders, primarily owing to a) higher usage of oxygen by brain cells and b) higher amounts of lipids in the neuronal membranes. Together, these have resulted in higher susceptibility of brain cells to ROS-induced lipid peroxidation, damage to other cellular macromolecules, including nucleic acids and proteins, and death of neurons by apoptosis, ferroptosis, and necrosis. The design of therapeutics to prevent oxidative damage-induced brain stroke or other irreversible injuries has remained a challenge owing to the continuous production of free radicals at the site of damage. In this respect, plant-derived tannins and tannic acid derivatives have exhibited promising results in scavenging free radicals and inhibiting lipid peroxidation.Objective: This investigation reports the effect of Ghala Rois extract (GRE), a methyl gallate enriched gall formed on the nutgall sumac tree, Rhus javanica L. (Anacardiaceae), on enhancing the cognitive function and overall well-being through a double-blind, placebo-controlled, randomized, parallel-group design study on 80 healthy adult volunteers over a period of six consecutive weeks.Results: Administration of GRE in the dosage of 750 mg/day p.o. (with an equal amount of corn starch as a placebo) after breakfast resulted in significant improvement in cognitive functions as assessed by HappyNeuroPro, a digital therapy tool, and the cognitive tools under Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MOCA) and Adult ADHD Self-Reported Scale (ASRSv1.1). Concomitantly, the GRE-treated subjects also scored significantly higher (p = 0.033) in the roles of Physical and Emotional Problems, Energy/Fatigue, Emotional well-being, and pain as evaluated by linearly independent pairwise comparisons among the estimated marginal means and computed using alpha = 0.05. In the Global Evaluation Questionnaire, over 77% of the treated subjects believed that the product increased their attention span, and helped their memory by 70%, and they also indicated their willingness to buy the commercially available GRE. Evaluation of the complete metabolic profile in the GRE-treated subjects significantly lowered the blood urea nitrogen (BUN) (11.98 mg/dL) as compared to placebo (13.27 mg/dL) (p = 0.011) as well as SGPT/ALT from 28.09 U/L (placebo) to 18.17 U/L (GRE-treated) (p&lt;0.001). However, the vital parameters, including heart rate and systolic/diastolic pressure, were not affected by the consumption of GRE extract.Conclusion: The study demonstrated that GRE could be used as an effective new phytotherapeutic for reversing oxidative damage-induced neuronal degeneration and improving cognitive health in these study individuals.Keywords: Galla Rhois extract (GRE); Rhus javanica L. (family Anacardiaceae); Cognitive functions; ADHD; Executive function; Verbal memory; Safety, Reactive Oxygen Species (ROS)

Evaluating β-cryptoxanthin antioxidant properties against ROS-induced macromolecular damages and determining its photo-stability and in-vitro SPF.

Natural antioxidants have become vital to minimize macromolecular damage caused by Reactive Oxygen Species (ROS). This study investigated the antioxidant property of β-cryptoxanthin (β-CRX) extracted fromKocuria marinaDAGII and its protective effect against macromolecular damages by generating ROS via two models: UV radiation and the Fenton reaction. β-cryptoxanthin exhibited the highest scavenging activity towards hydrogen peroxide radicals with an IC50 value of 38.30 ± 1.13μg/ml, favoring the hydrogen atom transfer mechanism. The total antioxidant capacity value of 872.0101 ± 1.84μg BHT/mg β-CRX indicated the cumulative ROS scavenging ability of β-cryptoxanthin. β-cryptoxanthin could protect against ROS-induced lipid peroxidation, protein oxidation, and DNA damage. The highest lipid peroxidation and protein oxidation inhibition values of β-cryptoxanthin against ROS were 99.371 ± 0.51% and 78.19 ± 0.15%, respectively. β-cryptoxanthin also showed a protective effect in maintaining DNA intactness against ROS-mediated DNA damage.Allium cepatest showed the non-genotoxic nature of β-cryptoxanthin and its protective effect against ROS genotoxic effects. A photo-stability study of β-cryptoxanthin toward UVA and UVB radiation showed a rapid bleaching result of UVB obeying pseudo-zero order kinetics with an average R2 value of 0.9897 and a higher k value (-6.3 × 10-11 ± 0.2M/s) than UVA (k value -3.1 × 10-11 ± 0.17M/s), signifying that UVB is more potent toward photo-degradation. The good SPF value of 23.1737 ± 0.15 showed the UV protection capability of β-cryptoxanthin. Thus, the present study suggests that β-cryptoxanthin could be a valuable antioxidant to protect against ROS-induced various macromolecular damages and act as a good UV protectant.

Chemotherapy impairs ovarian function through excessive ROS-induced ferroptosis

Chemotherapy was conventionally applied to kill cancer cells, but regrettably, they also induce damage to normal cells with high-proliferative capacity resulting in cardiotoxicity, nephrotoxicity, peripheral nerve toxicity, and ovarian toxicity. Of these, chemotherapy-induced ovarian damages mainly include but are not limited to decreased ovarian reserve, infertility, and ovarian atrophy. Therefore, exploring the underlying mechanism of chemotherapeutic drug-induced ovarian damage will pave the way to develop fertility-protective adjuvants for female patients during conventional cancer treatment. Herein, we firstly confirmed the abnormal gonadal hormone levels in patients who received chemotherapy and further found that conventional chemotherapeutic drugs (cyclophosphamide, CTX; paclitaxel, Tax; doxorubicin, Dox and cisplatin, Cis) treatment significantly decreased both the ovarian volume of mice and the number of primordial and antral follicles and accompanied with the ovarian fibrosis and reduced ovarian reserve in animal models. Subsequently, Tax, Dox, and Cis treatment can induce the apoptosis of ovarian granulosa cells (GCs), likely resulting from excessive reactive oxygen species (ROS) production-induced oxidative damage and impaired cellular anti-oxidative capacity. Thirdly, the following experiments demonstrated that Cis treatment could induce mitochondrial dysfunction through overproducing superoxide in GCs and trigger lipid peroxidation leading to ferroptosis, first reported in chemotherapy-induced ovarian damage. In addition, N-acetylcysteine (NAC) treatment could alleviate the Cis-induced toxicity in GCs by downregulating cellular ROS levels and enhancing the anti-oxidative capacity (promoting the expression of glutathione peroxidase, GPX4; nuclear factor erythroid 2-related factor 2, Nrf2 and heme oxygenase-1, HO-1). Our study confirmed the chemotherapy-induced chaotic hormonal state and ovarian damage in preclinical and clinical examination and indicated that chemotherapeutic drugs initiated ferroptosis in ovarian cells through excessive ROS-induced lipid peroxidation and mitochondrial dysfunction, leading to ovarian cell death. Consequently, developing fertility protectants from the chemotherapy-induced oxidative stress and ferroptosis perspective will ameliorate ovarian damage and further improve the life quality of cancer patients.

ROS-induced lipid peroxidation modulates cell death outcome: mechanisms behind apoptosis, autophagy, and ferroptosis.

Reactive oxygen species (ROS) mediate lipid peroxidation and produce 4-hydroxynonenal and other related products, which play an important role in the process of cell death, including apoptosis, autophagy, and ferroptosis. Lipid peroxidation of phospholipid bilayers can promote mitochondrial apoptosis, endoplasmic reticulum stress, and other complex molecular signaling pathways to regulate apoptosis. Lipid peroxidation and its products also act at different stages of autophagy, affecting the formation of autophagosomes and the recruitment of downstream proteins. In addition, we discuss the important role of ROS and lipid peroxides in ferroptosis and the regulatory role of nuclear factor erythroid 2-related factor 2 in ferroptosis under a background of oxidation. Finally, from the perspectives of promotion, inhibition, transformation, and common upstream molecules, we summarized the crosstalk among apoptosis, autophagy, and ferroptosis in the context of ROS. Our review discusses the role of ROS and lipid peroxidation in apoptosis, autophagy, and ferroptosis and their possible crosstalk mechanisms, so as to provide new insights and directions for the study of diseases related to pathological cell death. This review also has referential significance for studying the exact mechanism of ferroptosis mediated by lipid peroxidation.

Suppressing Mesenchymal Stromal Cell Ferroptosis Via Targeting a Metabolism‐Epigenetics Axis Corrects their Poor Retention and Insufficient Healing Benefits in the Injured Liver Milieu (Adv. Sci. 13/2023)

Mesenchymal Stromal Cell (MSC) Ferroptosis As reported in article number 2206439 by Ling Tao, Fuyang Zhang, and co-workers, MSCs are seriously damaged by the reactive oxygen species (ROS) after injection into the injured liver milieu and rapidly deplete due to ferroptosis driven by ROS-induced lipid peroxidation, like the devouring fire in the forest threatening the entered firefighters. Strategies reducing ferroptosis, such as incorporating ferroptosis inhibitors or overexpressing BCAT1, protect the implanted MSCs from ROS-irritated ferroptosis, hence improving MSC retention and therapeutic effectiveness, similar to the firefighters are shielded by the firefighting clothing and equipment.

Idebenone attenuates ferroptosis by inhibiting excessive autophagy via the ROS-AMPK-mTOR pathway to preserve cardiac function after myocardial infarction

Cardiovascular diseases (CVDs) are the leading causes of mortality worldwide. As a type of CVDs, myocardial infarction (MI) induces ischemia hypoxia, which leads to excessive reactive oxygen species (ROS), resulting in multiple cell deaths and contributing to the subsequent development of heart failure or premature death. Recent evidence indicates that ROS-induced lipid peroxidation promotes autophagy and ferroptosis, leading to the loss of healthy myocardium and resulting in the dysfunction of cardiac tissue. Theoretically, cardiac function would be preserved after MI by inhibiting autophagy and ferroptosis. As an analog of coenzyme Q10 (CoQ10) and a clinically approved drug, idebenone would be used to inhibit ferroptosis and preserve cardiac function due to its capacity to improve mitochondrial physiology with antioxidant and anti-inflammatory properties. Here, we confirmed that the addition of idebenone inhibited H2O2-induced and RSL3-induced ferroptosis. Furthermore, the ROS-AMPK-mTOR pathway axis was identified as the signaling pathway that idebenone stimulated to prevent excessive autophagy and consequent ferroptosis. In the MI animal model, idebenone demonstrated a cardioprotective role by regulating ROS-dependent autophagy and inhibiting ferroptosis, which paves the way for the future clinical translation of idebenone in MI management.

The effect and mechanistic study of encequidar on reversing the resistance of SW620/AD300 cells to doxorubicin

Encequidar, a gut-specific P-glycoprotein (P-gp) inhibitor, makes oral paclitaxel possible, and has been used in clinical treatment of metastatic breast cancer, however, its pharmacological effect and mechanism of reversal of drug resistance in drug-resistant colon cancer cells SW620/AD300 are still unknown. Herein, we first synthesized encequidar and demonstrated that it could inhibit the transport activity of P-gp, reduced doxorubicin (DOX) efflux, enhanced DOX cytotoxicity and promoted tumor-apoptosis in SW620/AD300 cells. Metabolomic analysis of cell samples was performedusing liquid chromatography Q-Exactive mass spectrometer, the results of metabolite enrichment analysis and pathway analysis showed that the combination of encequidar and DOX could: i) significantly affect the citric acid cycle (TCA cycle) and reduce the energy supply required for P-gp to exert its transport activity; ii) affect the metabolism of glutathione, which is the main component of the anti-oxidative stress system, and reduce the ability of cells to resist oxidative stress; iii) increase the intracellular reactive oxygen species (ROS) production and enhance ROS-induced cell damage and lipid peroxidation, which in turn restore the sensitivity of drug-resistant cells to DOX. In conclusion, these results provide sufficient data support for the therapeutical application of the P-gp inhibitor encequidar to reverse MDR, and are of great significance to further understand the therapeutic advantages of encequidar in anti-tumor therapy and guide clinical rational drug use.

Determination of ROS-Induced Lipid Peroxidation by HPLC-Based Quantification of Hydroxy Polyunsaturated Fatty Acids.

Because they are highly unsaturated, plant lipids are sensitive to oxidation and constitute a primary target of reactive oxygen species. Therefore, quantification of lipid peroxidation provides a pertinent approach to evaluating oxidative stress in plants. Here, we describe a simple method to measure upstream products of the peroxidation of the major polyunsaturated fatty acids in plants, namely, linolenic acid (C18:3) and linoleic acid (C18:2). The method uses conventional HPLC with UV detection to measure hydroxy C18:3 and C18:2 after reduction of their respective hydroperoxides. The described experimental approach requires low amounts of plant material (a few hundred milligrams), monitors oxidation of both membrane and free fatty acids, and can discriminate between enzymatic and non-enzymatic lipid peroxidation.

Syzygium aqueum (Burm.f.) Alston Prevents Streptozotocin-Induced Pancreatic Beta Cells Damage via the TLR-4 Signaling Pathway.

Although several treatments are available for the treatment of type 2 diabetes mellitus, adverse effects and cost burden impose the search for safe, efficient, and cost-effective alternative herbal remedies. Syzygium aqueum (Burm.f.) Alston, a natural anti-inflammatory, antioxidant herb, may suppress diabetes-associated inflammation and pancreatic beta-cell death. Here, we tested the ability of the bioactive leaf extract (SA) to prevent streptozotocin (STZ)-induced oxidative stress and inflammation in pancreatic beta cells in rats and the involvement of the TLR-4 signaling pathway. Non-fasted rats pretreated with 100 or 200 mg kg−1 SA 2 days prior to the STZ challenge and for 14 days later had up to 52 and 39% reduction in the glucose levels, respectively, while glibenclamide, the reference standard drug (0.5 mg kg−1), results in 70% reduction. Treatment with SA extract was accompanied by increased insulin secretion, restoration of Langerhans islets morphology, and decreased collagen deposition as demonstrated from ELISA measurement, H and E, and Mallory staining. Both glibenclamide and SA extract significantly decreased levels of TLR-4, MYD88, pro-inflammatory cytokines TNF-α, and TRAF-6 in pancreatic tissue homogenates, which correlated well with minimal pancreatic inflammatory cell infiltration. Pre-treatment with SA or glibenclamide decreased malondialdehyde, a sensitive biomarker of ROS-induced lipid peroxidation, and restored depleted reduced glutathione in the pancreas. Altogether, these data indicate that S. aqueum is effective in improving STZ-induced pancreatic damage, which could be beneficial in treating type 2 diabetes mellitus.

Naringenin Regulates Doxorubicin-Induced Liver Dysfunction: Impact on Oxidative Stress and Inflammation.

Doxorubicin (Dox) is an operational and largely used anticancer drug, used to treat an array of malignancies. Nonetheless, its beneficial use is constrained due to its renal and hepatotoxicity dose dependently. Numerous research findings favor the use of antioxidants may impact Dox-induced liver injury/damage. In the current study, Wistar rats were given naringenin (50 and 100 mg/kg b.wt.) orally for 20 days as prophylactic dose, against the hepatotoxicity induced by single intraperitoneal injection of Dox (20 mg/kg b.wt.). Potency of naringenin against the liver damage caused by Dox was assessed by measuring malonyl aldehyde (MDA) as a by-product of lipid peroxidation, biochemical estimation of antioxidant enzyme system, reactive oxygen species (ROS) level, and inflammatory mediators. Naringenin-attenuated ROS production, ROS-induced lipid peroxidation, and replenished reduced antioxidant armory, namely, catalase (CAT), glutathione reductase (GR), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione (GSH). Naringenin similarly diminished expression of Cox-2 and levels of NF-κB and other inflammatory molecules induced by the Dox treatment. Histology added further evidence to the defensive effects of naringenin on Dox-induced liver damage. The outcomes of the current study reveal that oxidative stress and inflammation are meticulously linked with Dox-triggered damage, and naringenin illustrates the potential effect on Dox-induced hepatotoxicity probably through diminishing the oxidative stress and inflammation.

Reactive Oxygen Species-Induced Lipid Peroxidation in Apoptosis, Autophagy, and Ferroptosis.

Reactive oxygen species- (ROS-) induced lipid peroxidation plays a critical role in cell death including apoptosis, autophagy, and ferroptosis. This fundamental and conserved mechanism is based on an excess of ROS which attacks biomembranes, propagates lipid peroxidation chain reactions, and subsequently induces different types of cell death. A highly evolved sophisticated antioxidant system exists that acts to protect the cells from oxidative damage. In this review, we discussed how ROS propagate lipid peroxidation chain reactions and how the products of lipid peroxidation initiate apoptosis and autophagy in current models. We also discussed the mechanism of lipid peroxidation during ferroptosis, and we summarized lipid peroxidation in pathological conditions of critical illness. We aim to bring a more global and integrative sight to know how different ROS-induced lipid peroxidation occurs among apoptosis, autophagy, and ferroptosis.

Renal temperature reduction progressively favors mitochondrial ROS production over respiration in hypothermic kidney preservation

BackgroundHypothermia, leading to mitochondrial inhibition, is widely used to reduce ischemic injury during kidney preservation. However, the exact effect of hypothermic kidney preservation on mitochondrial function remains unclear.MethodsWe evaluated mitochondrial function [i.e. oxygen consumption and production of reactive oxygen species (ROS)] in different models (porcine kidney perfusion, isolated kidney mitochondria, and HEK293 cells) at temperatures ranging 7–37 °C.ResultsLowering temperature in perfused kidneys and isolated mitochondria resulted in a rapid decrease in oxygen consumption (65% at 27 °C versus 20% at 7 °C compared to normothermic). Decreased oxygen consumption at lower temperatures was accompanied by a reduction in mitochondrial ROS production, albeit markedly less pronounced and amounting only 50% of normothermic values at 7 °C. Consequently, malondialdehyde (a marker of ROS-induced lipid peroxidation) accumulated in cold stored kidneys. Similarly, low temperature incubation of kidney cells increased lipid peroxidation, which is due to a loss of ROS scavenging in the cold.ConclusionsLowering of temperature highly affects mitochondrial function, resulting in a progressive discrepancy between the lowering of mitochondrial respiration and their production of ROS, explaining the deleterious effects of hypothermia in transplantation procedures. These results highlight the necessity to develop novel strategies to decrease the formation of ROS during hypothermic organ preservation.

Macrophage-Driven Biomaterial Degradation Depends on Scaffold Microarchitecture.

In situ tissue engineering is a technology in which non-cellular biomaterial scaffolds are implanted in order to induce local regeneration of replaced or damaged tissues. Degradable synthetic electrospun scaffolds are a versatile and promising class of biomaterials for various in situ tissue engineering applications, such as cardiovascular replacements. Functional in situ tissue regeneration depends on the balance between endogenous neo-tissue formation and scaffold degradation. Both these processes are driven by macrophages. Upon invasion into a scaffold, macrophages secrete reactive oxygen species (ROS) and hydrolytic enzymes, contributing to oxidative and enzymatic biomaterial degradation, respectively. This study aims to elucidate the effect of scaffold microarchitecture, i.e., μm-range fiber diameter and fiber alignment, on early macrophage-driven scaffold degradation. Electrospun poly-ε-caprolactone-bisurea (PCL-BU) scaffolds with either 2 or 6 μm (Ø) isotropic or anisotropic fibers were seeded with THP-1 derived human macrophages and cultured in vitro for 4 or 8 days. Our results revealed that macroph age-induced oxidative degradation in particular was dependent on scaffold microarchitecture, with the highest level of ROS-induced lipid peroxidation, NADPH oxidase gene expression and degradation in the 6 μm Ø anisotropic group. Whereas, biochemically polarized macrophages demonstrated a phenotype-specific degradative potential, the observed differences in macrophage degradative potential instigated by the scaffold microarchitecture could not be attributed to either distinct M1 or M2 polarization. This suggests that the scaffold microarchitecture uniquely affects macrophage-driven degradation. These findings emphasize the importance of considering the scaffold microarchitecture in the design of scaffolds for in situ tissue engineering applications and the tailoring of degradation kinetics thereof.

‘Candidatus Liberibacter asiaticus’ peroxiredoxin (LasBCP) suppresses oxylipin-mediated defense signaling in citrus

The Lasbcp (CLIBASIA_RS00445) 1-Cys peroxiredoxin gene is conserved among all 13 sequenced strains of Candidatus Liberibacter asiaticus, the causal agent of Huanglongbing or "citrus greening" disease. LasBCP was previously characterized as a secreted peroxiredoxin with substrate specificity for organic peroxides, and as a potential pathogenicity effector. Agrobacterium-mediated transient expression of LasBCP in citrus leaves provided significant protection against peroxidation of free and membrane-bound lipids, thereby preserving the molecular integrity of the chlorophyll apparatus and reducing accumulation of lipid peroxidation products (oxylipins) following exposure to tert-butyl hydroperoxide (tBOOH, an organic peroxide). Oxylipins extracted from GUS-expressing citrus leaves reduced viability of L. crescens, the only Liberibacter species cultured to date. However, similar extracts obtained from LasBCP-expressing leaves were less inhibitory to L. crescens growth and viability in culture. Quantitative RT-PCR analyses showed coordinated transcriptional downregulation of oxylipin biosynthetic (CitFAD, CitLOX, CitAOS and CitAOC), and jasmonic acid (JA) (CitJAR1, CitCOI1 and CitJIN1) and salicylic acid (SA) (CitPAL, CitICS and CitPR1) signaling pathway genes in citrus leaves expressing LasBCP and treated with tBOOH. The negative response regulator of jasmonic acid CitJAZ1 was upregulated in LasBCP-expressing citrus leaves under similar conditions. These data clearly demonstrated a protective role of secreted LasBCP in favor of Las survival and colonization by alleviating ROS-induced lipid peroxidation in citrus host, preventing accumulation of antimicrobial oxylipins, and suppressing both localized and systemic immune responses in planta.

Sustained SREBP-1-dependent lipogenesis as a key mediator of resistance to BRAF-targeted therapy

Whereas significant anti-tumor responses are observed in most BRAFV600E-mutant melanoma patients exposed to MAPK-targeting agents, resistance almost invariably develops. Here, we show that in therapy-responsive cells BRAF inhibition induces downregulation of the processing of Sterol Regulator Element Binding (SREBP-1) and thereby lipogenesis. Irrespective of the escape mechanism, therapy-resistant cells invariably restore this process to promote lipid saturation and protect melanoma from ROS-induced damage and lipid peroxidation. Importantly, pharmacological SREBP-1 inhibition sensitizes BRAFV600E-mutant therapy-resistant melanoma to BRAFV600E inhibitors both in vitro and in a pre-clinical PDX in vivo model. Together, these data indicate that targeting SREBP-1-induced lipogenesis may offer a new avenue to overcome acquisition of resistance to BRAF-targeted therapy. This work also provides evidence that targeting vulnerabilities downstream of oncogenic signaling offers new possibilities in overcoming resistance to targeted therapies.

Coral bleaching from a single cell perspective

Ocean warming is resulting in increased occurrence of mass coral bleaching; a response in which the intracellular algal endosymbionts (Symbiodinium sp.) are expelled from the coral host due to physiological stress. This detrimental process is often attributed to overproduction of reactive oxygen species (ROS) that leak out of the endosymbionts and causes damage to the host cell, though direct evidence validating this link is limited. Here, for the first time, we used confocal microscopy and fluorescent dyes to investigate if endosymbiont ROS production significantly and predictably affects physiological parameters in its host cell. Heat treatment resulted in a 60% reduction in coral symbiont density, a ~70% increase in median endosymbiont ROS and a small reduction in photosystem efficiency (FV/FM, 11%), indicating absence of severe light stress. Notably, no other physiological parameters were affected in either endosymbionts or host cells, including reduced glutathione and ROS-induced lipid peroxidation. Taken together, the increase in endosymbiont ROS could not be linked to physiological damage in either partner, suggesting that oxidative stress is unlikely to have been the driver for symbiont expulsion in this study.

Induction of Mitochondrial Reactive Oxygen Species Production by Itraconazole, Terbinafine, and Amphotericin B as a Mode of Action against Aspergillus fumigatus.

Drug resistance in fungal pathogens is of incredible importance to global health, yet the mechanisms of drug action remain only loosely defined. Antifungal compounds have been shown to trigger the intracellular accumulation of reactive oxygen species (ROS) in human-pathogenic yeasts, but the source of those ROS remained unknown. In the present study, we examined the role of endogenous ROS for the antifungal activity of the three different antifungal substances itraconazole, terbinafine, and amphotericin B, which all target the fungal cell membrane. All three antifungals had an impact on fungal redox homeostasis by causing increased intracellular ROS production. Interestingly, the elevated ROS levels induced by antifungals were abolished by inhibition of the mitochondrial respiratory complex I with rotenone. Further, evaluation of lipid peroxidation using the thiobarbituric acid assay revealed that rotenone pretreatment decreased ROS-induced lipid peroxidation during incubation of Aspergillus fumigatus with itraconazole and terbinafine. By applying the mitochondrion-specific lipid peroxidation probe MitoPerOx, we also confirmed that ROS are induced in mitochondria and subsequently cause significant oxidation of mitochondrial membrane in the presence of terbinafine and amphotericin B. To summarize, our study suggests that the induction of ROS production contributes to the ability of antifungal compounds to inhibit fungal growth. Moreover, mitochondrial complex I is the main source of deleterious ROS production in A. fumigatus challenged with antifungal compounds.