Scavenging Reactive Lipids to Prevent Oxidative Injury

Oxidative Stress Causes Mitochondrial and Electrophysiologic Dysfunction to Promote Atrial Fibrillation in Pitx2+/- Mice

BACKGROUND

The strongest genetic risk factors for atrial fibrillation (AF) are DNA variants on chromosome 4q25 near the transcription factor gene PITX2 (Pitx2:Paired-like homeodomain transcription factor 2). Mice deficient in Pitx2 (Pitx2+/-) have increased AF susceptibility, although the molecular mechanism(s) remains controversial. Pitx2 encodes a transcription factor that activates an antioxidant response to promote cardiac repair. Increased reactive oxygen species causing oxidation of polyunsaturated fatty acids generates reactive lipid dicarbonyl moieties that adduct to proteins and other macromolecules to promote cellular injury. We tested the hypothesis that oxidative stress, and specifically isolevuglandins, the most reactive lipid dicarbonyls identified, are increased in the setting of Pitx2 deficiency to promote proarrhythmic remodeling and AF.

METHODS

Pitx2+/- and Pitx2+/+ wild-type littermate control mice were treated orally with vehicle, the lipid dicarbonyl scavenger 2-hydroxybenzylamine, or an inactive control compound at weaning, until study at age 16 to 18 weeks.

RESULTS

Pitx2+/- mice demonstrated increased P wave duration indicative of slowed atrial conduction, as well as increased inducible AF burden and sustained AF, compared with wild type, and these abnormalities were prevented by 2-hydroxybenzylamine. Both reactive oxygen species and isolevuglandin protein adducts were elevated in Pitx2+/- atria with reduced expression of reactive oxygen species-protective genes. High-resolution respirometry demonstrated impaired mitochondrial function in Pitx2+/- atria, with disruption of mitochondrial integrity and cell-cell junctions with connexin lateralization, as well as decreased mitochondrial biogenesis gene expression. Proarrhythmic ionic current remodeling in Pitx2+/- atrial myocytes included elevated resting membrane potential, abbreviated action potential duration, and reduced maximum phase 0 upstroke velocity compared with wild type. Most of these abnormalities were ameliorated or prevented by 2-hydroxybenzylamine.

CONCLUSIONS

These results demonstrate a critical role for lipid dicarbonyl mediators of oxidative stress in the proarrhythmic remodeling and AF susceptibility that occurs with Pitx2 deficiency, implying the possibility of genotype-specific therapy to prevent AF.

Oxidative Stress and Reprogramming of Lipid Metabolism in Cancers

Oxidative stress is a common event involved in cancer pathophysiology, frequently accompanied by unique lipid metabolic reprogramming phenomena. Oxidative stress is caused mainly by an imbalance between the production of reactive oxygen species (ROS) and the antioxidant system in cancer cells. Emerging evidence has reported that oxidative stress regulates the expression and activity of lipid metabolism-related enzymes, leading to the alteration of cellular lipid metabolism; this involves a significant increase in fatty acid synthesis and a shift in the way in which lipids are taken up and utilized. The dysregulation of lipid metabolism provides abundant intermediates to synthesize biological macromolecules for the rapid proliferation of cancer cells; moreover, it contributes to the maintenance of intracellular redox homeostasis by producing a variety of reducing agents. Moreover, lipid derivatives and metabolites play critical roles in signal transduction within cancer cells and in the tumor microenvironment that evades immune destruction and facilitates tumor invasion and metastasis. These findings suggest a close relationship between oxidative stress and lipid metabolism during the malignant progression of cancers. This review focuses on the crosstalk between the redox system and lipid metabolic reprogramming, which provides an in-depth insight into the modulation of ROS on lipid metabolic reprogramming in cancers and discusses potential strategies for targeting lipid metabolism for cancer therapy.

Exploring Strategies to Prevent and Treat Ovarian Cancer in Terms of Oxidative Stress and Antioxidants

Oxidative stress is a state of imbalance between the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS) and the antioxidant defence system in the body. Oxidative stress may be associated with a variety of diseases, such as ovarian cancer, diabetes mellitus, and neurodegeneration. The generation of oxidative stress in ovarian cancer, one of the common and refractory malignancies among gynaecological tumours, may be associated with several factors. On the one hand, the increased metabolism of ovarian cancer cells can lead to the increased production of ROS, and on the other hand, the impaired antioxidant defence system of ovarian cancer cells is not able to effectively scavenge the excessive ROS. In addition, chemotherapy and radiotherapy may elevate the oxidative stress in ovarian cancer cells. Oxidative stress can cause oxidative damage, promote the development of ovarian cancer, and even result in drug resistance. Therefore, studying oxidative stress in ovarian cancer is important for the prevention and treatment of ovarian cancer. Antioxidants, important markers of oxidative stress, might serve as one of the strategies for preventing and treating ovarian cancer. In this review, we will discuss the complex relationship between oxidative stress and ovarian cancer, as well as the role and therapeutic potential of antioxidants in ovarian cancer, thus guiding future research and clinical interventions.

Pathophysiology of Group 3 Pulmonary Hypertension Associated with Lung Diseases and/or Hypoxia

Pulmonary hypertension associated with lung diseases and/or hypoxia is classified as group 3 in the clinical classification of pulmonary hypertension. The efficacy of existing selective pulmonary vasodilators for group 3 pulmonary hypertension is still unknown, and it is currently associated with a poor prognosis. The mechanisms by which pulmonary hypertension occurs include hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, a decrease in pulmonary vascular beds, endothelial dysfunction, endothelial-to-mesenchymal transition, mitochondrial dysfunction, oxidative stress, hypoxia-inducible factors (HIFs), inflammation, microRNA, and genetic predisposition. Among these, hypoxic pulmonary vasoconstriction and subsequent pulmonary vascular remodeling are characteristic factors involving the pulmonary vasculature and are the focus of this review. Several factors have been reported to mediate vascular remodeling induced by hypoxic pulmonary vasoconstriction, such as HIF-1α and mechanosensors, including TRP channels. New therapies that target novel molecules, such as mechanoreceptors, to inhibit vascular remodeling are awaited.

Understanding coenzyme Q

Coenzyme Q (CoQ), also known as ubiquinone, comprises a benzoquinone head group and a long isoprenoid side chain. It is thus extremely hydrophobic and resides in membranes. It is best known for its complex function as an electron transporter in the mitochondrial electron transport chain (ETC) but is also required for several other crucial cellular processes. In fact, CoQ appears to be central to the entire redox balance of the cell. Remarkably, its structure and therefore its properties have not changed from bacteria to vertebrates. In metazoans, it is synthesized in all cells and is found in most, and maybe all, biological membranes. CoQ is also known as a nutritional supplement, mostly because of its involvement with antioxidant defenses. However, whether there is any health benefit from oral consumption of CoQ is not well established. Here we review the function of CoQ as a redox-active molecule in the ETC and other enzymatic systems, its role as a prooxidant in reactive oxygen species generation, and its separate involvement in antioxidant mechanisms. We also review CoQ biosynthesis, which is particularly complex because of its extreme hydrophobicity, as well as the biological consequences of primary and secondary CoQ deficiency, including in human patients. Primary CoQ deficiency is a rare inborn condition due to mutation in CoQ biosynthetic genes. Secondary CoQ deficiency is much more common, as it accompanies a variety of pathological conditions, including mitochondrial disorders as well as aging. In this context, we discuss the importance, but also the great difficulty, of alleviating CoQ deficiency by CoQ supplementation.

Clerodendranthus Spicatus: A review of its active compounds, mechanisms of action, and clinical studies in urinary diseases

Clerodendranthus spicatus (Thunb.) C.Y.Wu (CS) is a widely studied plant that shows potential in treating urinary diseases. Previous studies have focused on its chemical composition, pharmacological effects, and clinical applications. This review aims to provide a comprehensive summary and evaluation of the existing literature on CS. It also suggests future research directions to increase our understanding of its medicinal value. 129 pieces of literature were selected from several databases, including PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), Wan-fang Database, and Google Scholar, and were analyzed. Forty-five active compounds of CS have pharmacological effects such as lowering uric acid, anti-inflammation, anti-oxidation, and kidney protection. The potential mechanisms of these effects may be related to inhibiting transforming growth factor β1 (TGF-β1) activation, reducing inflammatory factors such as IL-8, IL-1β, TNF-α, PGE2, IFN-γ, and IL-6 levels, suppressing the activation of NF-κB, JAK/STAT pathway, enhancing the clearance of ROS, MDA DPPH·, and O2 ̇ -, and regulating the expression of apoptosis-related pathways and proteins. This paper also discusses the quality control of CS and its efficacy and safety in treating urinary diseases. The study concludes that CS has a high potential for treating urinary diseases. Future studies should focus on observing the metabolic changes of CS active compounds in vivo and investigating the effects of CS on key signaling pathways. Additionally, more standardized and reasonable clinical studies and safety evaluation experiments should be conducted to obtain more clinical data.

Atrial cardiomyopathy revisited-evolution of a concept: a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS)

AIMS

The concept of "atrial cardiomyopathy" (AtCM) had been percolating through the literature since its first mention in 1972. Since then, publications using the term were sporadic until the decision was made to convene an expert working group with representation from four multinational arrhythmia organizations to prepare a consensus document on atrial cardiomyopathy in 2016 (EHRA/HRS/APHRS/SOLAECE expert consensus on atrial cardiomyopathies: definition, characterization, and clinical implication). Subsequently, publications on AtCM have increased progressively.

METHODS AND RESULTS

The present consensus document elaborates the 2016 AtCM document further to implement a simple AtCM staging system (AtCM stages 1-3) by integrating biomarkers, atrial geometry, and electrophysiological changes. However, the proposed AtCM staging needs clinical validation. Importantly, it is clearly stated that the presence of AtCM might serve as a substrate for the development of atrial fibrillation (AF) and AF may accelerates AtCM substantially, but AtCM per se needs to be viewed as a separate entity.

CONCLUSION

Thus, the present document serves as a clinical consensus statement of the European Heart Rhythm Association (EHRA) of the ESC, the Heart Rhythm Society (HRS), the Asian Pacific Heart Rhythm Society (APHRS), and the Latin American Heart Rhythm Society (LAHRS) to contribute to the evolution of the AtCM concept.

LNK/SH2B3 loss of function increases susceptibility to murine and human atrial fibrillation

AIMS

The lymphocyte adaptor protein (LNK) is a negative regulator of cytokine and growth factor signalling. The rs3184504 variant in SH2B3 reduces LNK function and is linked to cardiovascular, inflammatory, and haematologic disorders, including stroke. In mice, deletion of Lnk causes inflammation and oxidative stress. We hypothesized that Lnk-/- mice are susceptible to atrial fibrillation (AF) and that rs3184504 is associated with AF and AF-related stroke in humans. During inflammation, reactive lipid dicarbonyls are the major components of oxidative injury, and we further hypothesized that these mediators are critical drivers of the AF substrate in Lnk-/- mice.

METHODS AND RESULTS

Lnk-/- or wild-type (WT) mice were treated with vehicle or 2-hydroxybenzylamine (2-HOBA), a dicarbonyl scavenger, for 3 months. Compared with WT, Lnk-/- mice displayed increased AF duration that was prevented by 2-HOBA. In the Lnk-/- atria, action potentials were prolonged with reduced transient outward K+ current, increased late Na+ current, and reduced peak Na+ current, pro-arrhythmic effects that were inhibited by 2-HOBA. Mitochondrial dysfunction, especially for Complex I, was evident in Lnk-/- atria, while scavenging lipid dicarbonyls prevented this abnormality. Tumour necrosis factor-α (TNF-α) and interleukin-1 beta (IL-1β) were elevated in Lnk-/- plasma and atrial tissue, respectively, both of which caused electrical and bioenergetic remodelling in vitro. Inhibition of soluble TNF-α prevented electrical remodelling and AF susceptibility, while IL-1β inhibition improved mitochondrial respiration but had no effect on AF susceptibility. In a large database of genotyped patients, rs3184504 was associated with AF, as well as AF-related stroke.

CONCLUSION

These findings identify a novel role for LNK in the pathophysiology of AF in both experimental mice and humans. Moreover, reactive lipid dicarbonyls are critical to the inflammatory AF substrate in Lnk-/- mice and mediate the pro-arrhythmic effects of pro-inflammatory cytokines, primarily through electrical remodelling.

Role of reactive carbonyls and superoxide radicals in protein damage by cigarette smoke extracts: Comparison of Heat-not-Burn e-cigarettes to conventional cigarettes

Oxidative protein damage involving carbonylation of respiratory tract proteins typically accompanies exposure to tobacco smoke. Such damage can arise via multiple mechanisms, including direct amino acid oxidation by reactive oxygen species or protein adduction by electrophilic aldehydes. This study investigated the relative importance of these pathways during exposure of a model protein to fresh cigarette emission extracts. Briefly, protein carbonyl adducts were estimated in bovine serum albumin following incubation in buffered solutions with whole cigarette emissions extracts prepared from either a single 1R6F research cigarette or a single "Heat-not-Burn" e-cigarette. Although both extracts caused concentration-dependent protein carbonylation, conventional cigarette extracts produced higher adduct yields than e-cigarette extracts. Superoxide radical generation by conventional and e-cigarette emissions was assessed by monitoring nitro blue tetrazolium reduction and was considerably lower in extracts made from "Heat-Not-Burn" e-cigarettes. The superoxide dismutase/catalase mimic EUK-134 strongly suppressed radical production by whole smoke extracts from conventional cigarettes, however, it did not diminish protein carbonyl adduction when incubating smoke extracts with the model protein. In contrast, edaravone, a neuroprotective drug with strong carbonyl-trapping properties, strongly suppressed protein damage without inhibiting superoxide formation. Although these findings require extension to appropriate cell-based and in vivo systems, they suggest reactive aldehydes in tobacco smoke make greater contributions to oxidative protein damage than smoke phase radicals.

Isolevuglandins Promote Mitochondrial Dysfunction and Electrophysiologic Abnormalities in Atrial Cardiomyocytes

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, yet the cellular and molecular mechanisms underlying the AF substrate remain unclear. Isolevuglandins (IsoLGs) are highly reactive lipid dicarbonyl products that mediate oxidative stress-related injury. In murine hypertension, the lipid dicarbonyl scavenger 2-hydroxybenzylamine (2-HOBA) reduced IsoLGs and AF susceptibility. We hypothesized that IsoLGs mediate detrimental pathophysiologic effects in atrial cardiomyocytes that promote the AF substrate. Using Seahorse XFp extracellular flux analysis and a luminescence assay, IsoLG exposure suppressed intracellular ATP production in atrial HL-1 cardiomyocytes. IsoLGs caused mitochondrial dysfunction, with reduced mitochondrial membrane potential, increased mitochondrial reactive oxygen species (ROS) with protein carbonylation, and mitochondrial DNA damage. Moreover, they generated cytosolic preamyloid oligomers previously shown to cause similar detrimental effects in atrial cells. In mouse atrial and HL-1 cells, patch clamp experiments demonstrated that IsoLGs rapidly altered action potentials (AP), implying a direct effect independent of oligomer formation by reducing the maximum Phase 0 upstroke slope and shortening AP duration due to ionic current modifications. IsoLG-mediated mitochondrial and electrophysiologic abnormalities were blunted or totally prevented by 2-HOBA. These findings identify IsoLGs as novel mediators of oxidative stress-dependent atrial pathophysiology and support the investigation of dicarbonyl scavengers as a novel therapeutic approach to prevent AF.

GSH/APE1 Cascade-Activated Nanoplatform for Imaging Therapy Resistance Dynamics and Enzyme-Mediated Adaptive Ferroptosis

Ferroptosis, as a type of programmed cell death process, enables effective damage to various cancer cells. However, we discovered that persistent oxidative stress during ferroptosis can upregulate the apurinic/apyrimidinic endonuclease 1 (APE1) protein that induces therapeutic resistance ("ferroptosis resistance"), resulting in an unsatisfactory treatment outcome. To address APE1-induced therapeutic resistance, we developed a GSH/APE1 cascade activated therapeutic nanoplatform (GAN). Specifically, the GAN is self-assembled by DNA-functionalized ultrasmall iron oxide nanoparticles and further loaded with drug molecules (drug-GAN). GSH-triggered GAN disassembly can "turn on" the catalysis of GAN to induce efficient lipid peroxidation (LPO) for ferroptosis toward the tumor, which could upregulate APE1 expression. Subsequently, upregulated APE1 can further trigger accurate drug release for overcoming ferroptosis resistance and inducing the recovery of near-infrared fluorescence for imaging the dynamics of APE1. Importantly, adaptive drug release can overcome the adverse effects of APE1 upregulation by boosting intracellular ROS yield and increasing DNA damage, to offset APE1's functions of antioxidant and DNA repair, thus leading to adaptive ferroptosis. Moreover, with overexpressed GSH and upregulated APE1 in the tumor as stimuli, the therapeutic specificity of ferroptosis toward the tumor is greatly improved, which minimized nonspecific activation of catalysis and excessive drug release in normal tissues. Furthermore, a switchable MRI contrast from negative to positive is in sync with ferroptosis activation, which is beneficial for monitoring the ferroptosis process. Therefore, this adapted imaging and therapeutic nanoplatform can not only deliver GSH/APE1-activated lipid peroxide mediated adaptive synergistic therapy but also provided a switchable MRI/dual-channel fluorescence signal for monitoring ferroptosis activation, drug release, and therapy resistance dynamics in vivo, leading to high-specificity and high-efficiency adaptive ferroptosis therapy.

Protein adduction causes non-mutational inhibition of p53 tumor suppressor

p53 is a key tumor suppressor that is frequently mutated in human tumors. In this study, we investigated how p53 is regulated in precancerous lesions prior to mutations in the p53 gene. Analyzing esophageal cells in conditions of genotoxic stress that promotes development of esophageal adenocarcinoma, we find that p53 protein is adducted with reactive isolevuglandins (isoLGs), products of lipid peroxidation. Modification of p53 protein with isoLGs diminishes its acetylation and binding to the promoters of p53 target genes causing modulation of p53-dependent transcription. It also leads to accumulation of adducted p53 protein in intracellular amyloid-like aggregates that can be inhibited by isoLG scavenger 2-HOBA in vitro and in vivo. Taken together, our studies reveal a posttranslational modification of p53 protein that causes molecular aggregation of p53 protein and its non-mutational inactivation in conditions of DNA damage that may play an important role in human tumorigenesis.

A promising antifibrotic drug, pyridoxamine attenuates thioacetamide-induced liver fibrosis by combating oxidative stress, advanced glycation end products, and balancing matrix metalloproteinases

Liver fibrosis is a common chronic hepatic disease. This study was done to examine the effect of pyridoxamine against thioacetamide-induced hepatic fibrosis. Animals were divided into four groups (1) control group; (2) Thioacetamide group (200 mg/kg, i.p.) twice a week for eight weeks; (3) Pyridoxamine-treated group treated with pyridoxamine (100 mg/kg/day, i.p.) for eight weeks; (4) Thioacetamide and pyridoxamine group, in which pyridoxamine was given (100 mg/kg/day, i.p.) during thioacetamide injections. Thioacetamide treatment resulted in hepatic dysfunction manifested by increased serum levels of bilirubin, gamma-glutamyl transferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST). Oxidative stress was noted by increased hepatic lipid peroxidation and decreased glutathione (GSH). Increased concentrations of total nitrite/nitrate, advanced glycation end products (AGEs), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), transforming growth factor-β (TGF-β), matrix metalloproteinases (MMP-2&9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) were noticed in hepatic tissues. Immunostaining sections also revealed overexpression of MMP-2, MMP-9 and collagen IV. Liver fibrosis was confirmed by severe histopathological changes. Pyridoxamine improved the assessed parameters. Moreover, histopathological and immunohistological studies supported the ability of pyridoxamine to reduce liver fibrosis. The findings of the present study provide evidence that pyridoxamine is a novel target for the treatment of liver fibrosis.

Understanding Myeloperoxidase-Induced Damage to HDL Structure and Function in the Vessel Wall: Implications for HDL-Based Therapies

Atherosclerosis is a disease of increased oxidative stress characterized by protein and lipid modifications in the vessel wall. One important oxidative pathway involves reactive intermediates generated by myeloperoxidase (MPO), an enzyme present mainly in neutrophils and monocytes. Tandem MS analysis identified MPO as a component of lesion derived high-density lipoprotein (HDL), showing that the two interact in the arterial wall. MPO modifies apolipoprotein A1 (apoA-I), paraoxonase 1 and certain HDL-associated phospholipids in human atheroma. HDL isolated from atherosclerotic plaques depicts extensive MPO mediated posttranslational modifications, including oxidation of tryptophan, tyrosine and methionine residues, and carbamylation of lysine residues. In addition, HDL associated plasmalogens are targeted by MPO, generating 2-chlorohexadecanal, a pro-inflammatory and endothelial barrier disrupting lipid that suppresses endothelial nitric oxide formation. Lesion derived HDL is predominantly lipid-depleted and cross-linked and exhibits a nearly 90% reduction in lecithin-cholesterol acyltransferase activity and cholesterol efflux capacity. Here we provide a current update of the pathophysiological consequences of MPO-induced changes in the structure and function of HDL and discuss possible therapeutic implications and options. Preclinical studies with a fully functional apoA-I variant with pronounced resistance to oxidative inactivation by MPO-generated oxidants are currently ongoing. Understanding the relationships between pathophysiological processes that affect the molecular composition and function of HDL and associated diseases is central to the future use of HDL in diagnostics, therapy, and ultimately disease management.

Isolevuglandins Scavenger Ameliorates Myocardial Ischemic Injury by Suppressing Oxidative Stress, Apoptosis, and Inflammation

Augmented levels of reactive isolevuglandins (IsoLGs) are responsible for cardiovascular diseases. The role of IsoLGs in myocardial infarction (MI) remains elusive. Here we explored the effect of IsoLGs scavenger 2-hydroxybenzylamine (2-HOBA) in post-infarction cardiac repair. We observed that infarcted cardiac tissues expressed high IsoLGs in mice. Following MI injury, 2-HOBA treated mice displayed decreased infarction area and improved heart function compared with the saline-treated group. Moreover, 2-HOBA effectively attenuated MI-induced cardiac remodeling, oxidative stress, apoptosis, and inflammation. 4-hydroxybenzylamine (4-HOBA), a less reactive isomer of 2-HOBA, barely antagonized the MI-induced injury. These findings suggest that IsoLGs elimination may be helpful in MI therapy.

Salt Sensitivity of Blood Pressure in Blacks and Women: A Role of Inflammation, Oxidative Stress, and Epithelial Na+ Channel

Significance: Salt sensitivity of blood pressure (SSBP) is an independent risk factor for mortality and morbidity due to cardiovascular disease, and disproportionately affects blacks and women. Several mechanisms have been proposed, including exaggerated activation of sodium transporters in the kidney leading to salt retention and water. Recent Advances: Recent studies have found that in addition to the renal epithelium, myeloid immune cells can sense sodium via the epithelial Na+ channel (ENaC), which leads to activation of the nicotinamide adenine dinucleotide phosphate oxidase enzyme complex, increased fatty acid oxidation, and production of isolevuglandins (IsoLGs). IsoLGs are immunogenic and contribute to salt-induced hypertension. In addition, aldosterone-mediated activation of ENaC has been attributed to the increased SSBP in women. The goal of this review is to highlight mechanisms contributing to SSBP in blacks and women, including, but not limited to increased activation of ENaC, fatty acid oxidation, and inflammation. Critical Issues: A critical barrier to progress in management of SSBP is that its diagnosis is not feasible in the clinic and is limited to expensive and laborious research protocols, which makes it difficult to investigate. Yet without understanding the underlying mechanisms, this important risk factor remains without treatment. Future Directions: Further studies are needed to understand the mechanisms that contribute to differential blood pressure responses to dietary salt and find feasible diagnostic tools. This is extremely important and may go a long way in mitigating the racial and sex disparities in cardiovascular outcomes. Antioxid. Redox Signal. 35, 1477-1493.

Introduction to the Theme "Old and New Toxicology: Interfaces with Pharmacology"

The theme of Volume 61 is "Old and New Toxicology: Interfaces with Pharmacology." Old toxicology is exemplified by the authors of the autobiographical articles: B.M. Olivera's work on toxins and venoms from cone snails and P. Taylor's studies of acetylcholinesterase and the nicotinic cholinergic receptor, which serve as sites of action for numerous pesticides and venoms. Other articles in this volume focus on new understanding and new types of toxicology, including (a) arsenic toxicity, which is an ancient poison that, through evolution, has caused most multicellular organisms to express an active arsenic methyltransferase to methylate arsenite, which accelerates the excretion of arsenic from the body; (b) small molecules that react with lipid dicarbonyls, which are now considered the most toxic oxidative stress end products; (c) immune checkpoint inhibitors (ICIs), which have revolutionized cancer therapy but have numerous immune-related adverse events, including cardiovascular complications; (d) autoimmunity caused by the environment; (e) idiosyncratic drug-induced liver disease, which together with the toxicity of ICIs represents new toxicology interfacing with pharmacology; and (f) sex differences in the development of cardiovascular disease, with men more susceptible than women to vascular inflammation that initiates and perpetuates disease. These articles and others in Volume 61 reflect the interface and close integration of pharmacology and toxicology that began long ago but continues today.

Exosomal delivery of therapeutic modulators through the blood-brain barrier; promise and pitfalls

Nowadays, a large population around the world, especially the elderly, suffers from neurological inflammatory and degenerative disorders/diseases. Current drug delivery strategies are facing different challenges because of the presence of the BBB, which limits the transport of various substances and cells to brain parenchyma. Additionally, the low rate of successful cell transplantation to the brain injury sites leads to efforts to find alternative therapies. Stem cell byproducts such as exosomes are touted as natural nano-drug carriers with 50-100 nm in diameter. These nano-sized particles could harbor and transfer a plethora of therapeutic agents and biological cargos to the brain. These nanoparticles would offer a solution to maintain paracrine cell-to-cell communications under healthy and inflammatory conditions. The main question is that the existence of the intact BBB could limit exosomal trafficking. Does BBB possess some molecular mechanisms that facilitate the exosomal delivery compared to the circulating cell? Although preliminary studies have shown that exosomes could cross the BBB, the exact molecular mechanism(s) beyond this phenomenon remains unclear. In this review, we tried to compile some facts about exosome delivery through the BBB and propose some mechanisms that regulate exosomal cross in pathological and physiological conditions.

CART mitigates oxidative stress and DNA damage in memory deficits of APP/PS1 mice via upregulating β‑amyloid metabolism‑associated enzymes

Alzheimer's disease (AD) is the most common form of dementia that is primarily characterized by progressive cognitive deficits. The toxicity of amyloid β-protein (Aβ) serves an important role in the progression of AD, resulting in neuronal loss via a number of possible mechanisms, including oxidative stress, mitochondrial dysfunction, energy depletion, apoptosis and neuroinflammation. Previous studies have reported that cocaine amphetamine regulated transcript (CART) treatment improves memory and synaptic structure in APP/PS1 mice. Therefore, the present study aimed to investigate whether CART served a protective role against memory deficits in AD. APP/PS1 mice were treated with CART or PBS. Spatial memory was assessed using the Morris water maze. Oxidative stress and DNA damage were compared among wild-type, APP/PS1 and CART-treated APP/PS1 mice. The mRNA and protein expression levels of Aβ metabolism-associated enzymes, including neprilysin (NEP), insulin-degrading enzyme (IDE), receptor for advanced glycation end products (RAGE) and low-density lipoprotein receptor-related protein 1 (LRP-1), in the hippocampus were measured via reverse transcription-quantitative PCR and western blotting, respectively. CART improved the memory impairment of APP/PS1 mice by reducing oxidative stress, inhibiting DNA damage and protecting against mitochondrial dysfunction in the cerebral cortex and hippocampus. CART also reduced cell senescence and oxidative stress in Aβ1-42-exposed primary cortical neurons in APP/PS1 mice. Moreover, CART promoted Aβ degradation via modulating Aβ metabolism-associated enzymes, including IDE, NEP, LRP-1 and RAGE. Collectively, the present study indicated that CART improved the learning and memory capacity of APP/PS mice, thus may have potential to serve as a novel therapeutic agent for AD.