NRF2 in COST Action 20121
Our quarterly newsletter attempts to provide our latest news and also aims at becoming a forum for analysis of relevant topics on the field of NRF2 and provide comments to some of the most relevant articles published during the quarter. Previous newsletters can be accessed at:
https://benbedphar.org/our-first-newsletter/
https://benbedphar.org/issue-2-abril-2022/
https://benbedphar.org/issue-3-july-2022/
https://benbedphar.org/issue-4-october-2022/
https://benbedphar.org/issue-5-january-2023/
https://benbedphar.org/issue-6-april-2023/
https://benbedphar.org/issue-7-october-2023/
https://benbedphar.org/issue-8-january-2024/
https://benbedphar.org/issue-9-april-2024/
https://benbedphar.org/issue-10-october-2024/
Antonio Cuadrado
Chair of COST Action 20121, BenBedPhar
Autonomous University of Madrid
Comments from the Working Groups
The potential of triterpenoids in NRF2 regulation, from natural compounds to synthetic terpenoid structures
Triterpenoids, as particular group of plant isolated terpenes, are obtained by six isoprene units through enzymatically catalyzed condensation reactions. Their biosynthesis includes reactions of oxidation, reduction, and additions of functional groups, leading to a wide variety of naturally occurring triterpene derivatives. Many authors have suggested that natural triterpenes can exert important pharmacological properties by modulation of NRF2 pathway [1,2,3].
NRF2 is one of the crucial regulators of the antioxidant response by controlling the expression of genes involved in detoxification, antioxidant defense, and cellular protection against oxidative stress. Disturbances in redox balance of the cell promote conformational changes in KEAP1-NRF2 ARE signaling axis. Although, this is the most identified pathway for activation of NRF2 by natural products, the GSK-3β/NRF2/β-TrCP signaling axis could be also involved in chemo sensibilization of cancer cells [4].
Natural triterpenoids as well as taraxasterol, astragaloside, ursolic acid, withaferin are electrophilic molecules behaving as NRF2 activators [1,2,3]. It is assumed that KEAP1 contains a series of cysteines (27 in humans), in which some specific cysteine residues are increasing the nucleophilicity of KEAP1. This nucleophilic potential attracts the electrophilic compounds which promotes structural rearrangement in KEAP 1, further conformational changes and activation of NRF2 [5].
Withaferin A, a steroidal triterpenoid lactone isolated from Withania somnifera L., has shown a potential for NRF2 activation. Withaferin A can ameliorate multidosage-sterptozocin induced diabetes mellitus type 1 via modulation of Nrf2/NFκB signaling[6]. This effect can be expected regarding its structure containing two rings (A and E) reacting as Michael acceptors and a B-ring epoxide, all of which have the potential to interact with KEAP1 and activate NRF2. Another pentacyclic-triterpene taraxasterol, isolated from Taraxacum sp., have shown hepatoprotective effects in which activation of Nrf2/HO-1 signaling pathways are involved [1].
On the other side, brusatol, triterpene lactones known as “quassinoids” have demonstrated that it is still known as one of the most potent NRF2 inhibitors from natural origin. The anti-tumor effects were emphasized with its potential for sensitizing many types of cancer cells. [7]. Therefore, this structure served for further development of other semi-synthetic (halofuginone) which promoted a decrease in the level of the NRF2 protein and selective cytotoxicity for NRF2 addicted cancer cell lines. Additionally, it has increased the efficacy of cisplatin in vivo, in an NRF2 dependent manner.
Oleanolic acid, a modest anti-inflammatory agent, doesn’t possess potential for NRF2 activation but has served as a basic structure for derivatization and obtaining of synthetic oleanane triterpenoids. Different modifications and addition of Michaelis acceptors in the rings of the steroid structure have been performed, until bardoxolone (CDDO), was revealed as a potent NRF2 activator. Their pre-clinical and clinical studies confirmed their ability to activate NRF2 pathway and act as anti-inflammatory, antineoplastic and reducing chemoresistance effects [8]. Another oleanone derivative, omaveloxolone, a recent therapeutic developed by Reata Pharmaceuticals have raised the interest for natural derived products based on triterpenoid structures after FDA approval, in 2023 for the treatment of Friedreich’s ataxia [9].
These data lead to a conclusion that natural triterpenoid compounds can serve as promising compounds for their derivatization and optimization of semi-synthetic and synthetic therapeutic agents as a promising targeting of NRF2 pathway.
is well known that the nuclear factor erythroid 2–related factor 2 (NRF2) function can be activated by various synthetic and natural substances for example sulforaphane, resveratrol, quercetin, bardoxolone methyl, and even registered drugs metformin and statins. One of the most powerful NRF2 activators is dimethyl fumarate (DMF), originally isolated from Fumaria officinalis. DMF is approved for the treatment of psoriasis and sclerosis multiplex. In addition, several studies suggested that DMF (or other fumarates) also possesses the potential to be repurposed for the treatment of cardiovascular diseases, for example as a therapeutic agent in patients with atherosclerotic cardiovascular disease. However, less is known about the long-term effects of activation of NRF2 function by DMF in chronic social stress conditions, to which patients are, more or less, exposed during the diseased state and its treatment. Moreover, borderline elevated blood pressure (prehypertension) is widespread even in young adults and children, so the effect of elevated blood pressure should also be considered in cardiovascular studies investigating the role of NRF2 itself or in the conditions of activated NRF2 function by various activators.
In our recently published study [1], we investigated the effects of chronic social stress, DMF and their interaction in rats genetically predisposed to high blood pressure, so-called borderline hypertensive rats (BHR). Our study showed that chronic social stress produced by crowding significantly elevated blood pressure and plasma corticosterone while inhibiting body weight gain, as expected in this stress model. Furthermore, upregulation of Nfe2l2 gene expression was present in the hearts of crowding-exposed rats associated with elevated Sod1 and Hmox1 gene expressions and reduced lipid peroxidation. DMF alone did not exert a significant effect on blood pressure and the endothelium-dependent and independent relaxations in the femoral artery. However, DMF, similarly to stress, led to an increase in plasma corticosterone levels, Nfe2l2, Sod1, Hmox1 gene expressions in the heart, reduced oxidative damage to lipids and this was, in contrast to stress, associated with the increase in relative left heart ventricular mass, suggesting the development of left heart ventricular hypertrophy. When DMF was administered to stress-exposed BHR, it prevented the development of stress-induced hypertension and corticosterone elevations. This was accompanied by a reduction in noradrenaline-induced contractions in the femoral artery which we consider the primary mechanism by which DMF prevented stress-induced hypertension in the crowding stress model. On the other hand, a concomitant upregulation of inflammatory mediator genes (Tnf, Nos2) in the heart was found in rats treated with DMF in stress conditions. Collectively, the findings suggest that DMF can prevent chronic stress-induced hypertension by reducing vascular contractility without alterations in vasorelaxation. Moreover, DMF itself might produce reductive stress in the heart and induce inflammation when combined with stress. The study provides insights into the potential benefits and risks of using DMF in chronic social stress conditions in presence of prehypertension. It also suggests a need for careful consideration of long-term DMF treatment taking into account its impact on
References:
- Xu L, Yu Y, Sang R, Li J, Ge B, Zhang X. Protective Effects of Taraxasterol against Ethanol-Induced Liver Injury by Regulating CYP2E1/Nrf2/HO-1 and NF-κB Signaling Pathways in Mice. Oxid Med Cell Longev. 2018 Sep 23;2018:8284107
- Xiao L, Dai Z, Tang W, Liu C, Tang B. Astragaloside IV Alleviates Cerebral Ischemia-Reperfusion Injury through NLRP3 Inflammasome-Mediated Pyroptosis Inhibition via Activating Nrf2. Oxid Med Cell Longev. 2021 Dec 30;2021:9925561.
- Yang Y, Yin R, Wu R, Ramirez CN, Sargsyan D, Li S, Wang L, Cheng D, Wang C, Hudlikar R, Kuo HC, Lu Y, Kong AN. DNA methylome and transcriptome alterations and cancer prevention by triterpenoid ursolic acid in UVB-induced skin tumor in mice. Mol Carcinog. 2019 Oct;58(10):1738-1753.
- Srivastava R, Fernández-Ginés R, Encinar JA, Cuadrado A, Wells G. The current status and future prospects for therapeutic targeting of KEAP1-NRF2 and β-TrCP-NRF2 interactions in cancer chemoresistance. Free Radic Biol Med. 2022 Nov 1;192:246-260.
- Zhang DD, Hannink M. Distinct cysteine residues in Keap1 are required for Keap1-dependent ubiquitination of Nrf2 and for stabilization of Nrf2 by chemopreventive agents and oxidative stress. Mol Cell Biol. 2003 Nov;23(22):8137-51.
- Tekula S, Khurana A, Anchi P, Godugu C. Withaferin-A attenuates multiple low doses of Streptozotocin (MLD-STZ) induced type 1 diabetes. Biomed Pharmacother. 2018 Oct;106:1428-1440.
- Yu XQ, Shang XY, Huang XX, Yao GD, Song SJ. Brusatol: A potential anti-tumor quassinoid from Brucea javanica. Chin Herb Med. 2020 Aug 19;12(4):359-366.
- Zhang DD, Chapman E. The role of natural products in revealing NRF2 function. Nat Prod Rep. 2020 Jun 1;37(6):797-826.
- Lee A. Omaveloxolone: First Approval. Drugs. 2023 Jun;83(8):725-729.
Viktorija Maksimova, PhD,
Faculty of Medical Sciences, Goce Delcev University, Stip
Republic of N. Macedonia
WG1 member, on behalf of authors
Covalent molecular glues for enhanced degradation of NRF2
The role of NRF2 in facilitating tumor growth has led to extensive efforts in search for NRF2 inhibitors. Numerous high-throughput screens have yielded several small molecules, most of which however are inhibitors of global protein translation (1). Using their unique mass spectrometry chemoproteomics screening-based drug discovery approach, which measures
changes in the covalent binding of cysteine residue to a biotinylated iodoacetamide probe following treatment with candidate covalent ligands (2), Vividion Therapeutics discovered VVD-065, a first-in-class small molecule NRF2 inhibitor with an allosteric molecular glue mechanism of action (3). VVD-065 is an electrophile, which similar to many other electrophilic NRF2 activators, specifically binds covalently to C151 in the BTB domain of KEAP1, the principal negative regulator of NRF2 (Figure 1). Unexpectedly however, instead of inhibiting KEAP1, VVD-065 promotes the formation of the KEAP1-CUL3 protein complex, resulting in accelerated degradation of NRF2.
These findings suggest that C151 in KEAP1 represents a tuneable regulator of the KEAP1-CUL3 protein complex. By covalently modifying C151 in KEAP1, most electrophiles such as bardoxolone and the FDA approved dimethyl fumarate (for multiple sclerosis) and omaveloxolone (for Friedreich’s ataxia), decrease the affinity of KEAP1 for binding to CUL3, resulting in NRF2 activation (4). By contrast, compounds such as VVD-065, increase the binding of KEAP1 to CUL3, leading to NRF2 inhibition.
In preclinical models, VVD-065 inhibits NRF2-dependent tumor growth and sensitizes tumors to chemo- and radiotherapy. Based on this discovery, an open Phase I clinical trial is currently underway in with a related compound (VVD-130037) in patients with metastatic or unresectable solid tumors, which have no mutations in KEAP1 (NCT05954312).
References:
- Harder et al. Brusatol overcomes chemoresistance through inhibition of protein translation. Mol Carcinog. 2017; 56: 1493-1500.
- Backus et al. Proteome-wide covalent ligand discovery in native biological systems. Nature 2016; 23; 534: 570-574.
- Roy et al. Suppression of NRF2-dependent cancer growth by a covalent allosteric molecular glue. bioRxiv preprint: https://doi.org/10.1101/2024.10.04.616592.
- Adamson et al. Structural and biochemical characterization establishes a detailed understanding of KEAP1-CUL3 complex assembly. Free Radic Biol Med. 2023; 204: 215-225.
Ana I Rojo
Autonomous University of Madrid, Spain
Albena T Dinkova-Kostova
University of Dundee, United Kingdom
WG2 Leaders, on behalf of authors
Protective Effects of Sulforaphane Preventing Inflammation and Oxidative Stress to Enhance Metabolic Health: A Narrative Review
The worldwide obesity epidemic has led to a drastic increase in diabetes and cardiovascular disease in younger generations. Further, maintaining metabolic health during aging is frequently a challenge due to poor diets and decreased mobility. In this setting, bioactive nutrients that are naturally occurring antioxidants, such as sulforaphane (SFN), are of high nutritional interest. SFN, a bioactive compound that is present in cruciferous vegetables, is a molecule that protects cells from cytotoxic damage and mitigates oxidative stress, protecting against disease. It exerts its action through the activation of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2). Many studies have been performed in animals and humans to evaluate its effects on cancer, brain health, and neurodegenerative disorders. However, fewer clinical studies have been performed to evaluate its effects on insulin resistance and the development of type 2 diabetes mellitus (T2DM) across the lifespan. Given that, in some parts of the world, particularly in Europe, the population is growing older at a significant rate, it is crucial to promote healthy habits (healthy foods, dietary pattern, precision nutrition, and physical activity) from an early stage in life and across the lifespan to avoid debilitating health conditions occurring during adulthood and aging. Thus, in this narrative review, we discuss the protective effects of SFN supplementation on inflammatory and oxidative stress pathways and relate them to metabolic disease.
Adapted from:
Alves, I.; Araújo, E.M.Q.; Dalgaard, L.T.; Singh, S.; Børsheim, E.; Carvalho, E. Protective Effects of Sulforaphane Preventing Inflammation and Oxidative Stress to Enhance Metabolic Health: A Narrative Review. Nutrients 2025, 17, 428.
Link to paper: https://doi.org/10.3390/nu17030428
Christina Morgenstern
Medical University of Vienna, Austria
WG3 Leader, on behalf of authors
Model organisms for investigating the functional involvement of NRF2 in non-communicable diseases
Non-communicable chronic diseases (NCDs) are most commonly characterized by age-related loss of homeostasis and/or by cumulative exposures to environmental factors, which lead to low-grade sustained generation of reactive oxygen species (ROS), chronic inflammation and metabolic imbalance. Nuclear factor erythroid 2-like 2 (NRF2) is a basic leucine-zipper transcription factor that regulates the cellular redox homeostasis. NRF2 controls the expression of more than 250 human genes that share in their regulatory regions a cis-acting enhancer termed the antioxidant response element (ARE). The products of these genes participate in numerous functions including biotransformation and redox homeostasis, lipid and iron metabolism, inflammation, proteostasis, as well as mitochondrial dynamics and energetics. Thus, it is possible that a single pharmacological NRF2 modulator might mitigate the effect of the main hallmarks of NCDs, including oxidative, proteostatic, inflammatory and/or metabolic stress. Research on model organisms has provided tremendous knowledge of the molecular mechanisms by which NRF2 affects NCDs pathogenesis. This review is a comprehensive summary of the most commonly used model organisms of NCDs in which NRF2 has been genetically or pharmacologically modulated, paving the way for drug development to combat NCDs. We discuss the validity and use of these models and identify future challenges.
Adapted from:
Rojo AI, Buttari B, Cadenas S, Carlos AR, Cuadrado A, Falcão AS, López MG, Georgiev MI, Grochot-Przeczek A, Gumeni S, Jimenez-Villegas J, Horbanczuk JO, Konu O, Lastres-Becker I, Levonen AL, Maksimova V, Michaeloudes C, Mihaylova LV, Mickael ME, Milisav I, Miova B, Rada P, Santos M, Seabra MC, Strac DS, Tenreiro S, Trougakos IP, Dinkova-Kostova AT. Model organisms for investigating the functional involvement of NRF2 in non-communicable diseases. Redox Biol. 2025 Feb;79:103464.
Link to paper: 10.1016/j.redox.2024.103464
Brigitta Buttari
Istituto Superiore di Sanità, IT
WG5 Leader, on behalf of authors
Hot from Pubmed
NRF2: A crucial regulator for mitochondrial metabolic shift and prostate cancer progression
Metabolic alterations are a common survival mechanism for prostate cancer progression and therapy resistance. This metabolic switching is dictated by oxidative stress in the cellular and tumor microenvironment. Therefore, regulation of oxidative stress in tumor cells and in the tumor-microenvironment may enhance the action of conventional anticancer therapies. However, the overall oxidative stress varies with prostate cancer clinical stage, metabolic state and therapy used for the cancer. This review by Buttari and colleagues summarized the levels of oxidative stress, metabolic preferences and NRF2 activity in the different stages of prostate cancer, providing a detailed understanding of the mechanism of action of NRF2. Moreover, a potential stage specific therapeutic method using NRF2 inducers or inhibitors to control aggressive prostate cancer growth was also discussed.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/36213236/
Role of Nrf2 in Epilepsy Treatment
Oxidative stress is a consequence of the disruption of the balance between the generation of reactive nitrogen and oxygen species and the biological system’s ability to neutralize those reactive products. Oxidative stress is involved in the generation of many disorders, including epilepsy, which is a prevalent chronic neurological disease that affects the lives of millions of people around the world. Epilepsy is characterized by unforeseeable and repeated seizures that can be very disturbing. Studies have reported that oxidative stress occurs before and after seizures. A transcription factor named Nuclear factor erythroid-derived 2-related factor 2 (Nrf2) controls genes related to the induction of oxidative stress and defends cells against oxidative stress. The Nrf2 protein has seven different domains, ranging from Neh1 to Neh7. Each domain is responsible for a distinctive function of this protein. Keap1 binds to Nrf2, but during oxidative stress, Nrf2 detaches from the Keap1 protein, moves to the nucleus, and binds to DNA. The result of this translocation and binding is the initiation of transcription of detoxifying genes to control the harmful effects of oxidative stress. There is some evidence of oxidative stress involvement in epilepsy. In this review, we have listed potential Nrf2-related therapeutic targets for treating and controlling epilepsy, such as Berberis alkaloids, pentoxifylline, lovastatin, progesterone, and chrysin nanoparticles. These activators were tested in animals (in vivo) and cells (in vitro), and most of these experiments showed promising results in different epilepsy models. Finally, the results have suggested that the activation of Nrf2 can be an option for controlling epilepsy.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39350402/
Specific targeting of the NRF2/β-TrCP axis promotes beneficial effects in NASH.
The effect of the novel compound PHAR, a protein-protein interaction inhibitor of NRF2/β-TrCP, which induces a mild NRF2 activation and selectively activates NRF2 in the liver, has been assessed in protection against Non-alcoholic steatohepatitis (NASH) and its progression to fibrosis. PHAR effectively activated NRF2 in hepatocytes, Kupffer cells, and stellate cells. The effect of PHAR has been analyzed in the STAM mouse model of NASH, based on partial damage of endocrine pancreas and insulin secretion impairment, followed by a high fat diet. Non-invasive analysis using MRI revealed that PHAR protects against liver fat accumulation. Moreover, PHAR attenuated key markers of NASH progression, including liver steatosis, hepatocellular ballooning, inflammation, and fibrosis. Notably, transcriptomic data indicate that PHAR led to upregulation of 3 anti-fibrotic genes (Plg, Serpina1a, and Bmp7) and downregulation of 6 pro-fibrotic (including Acta2 and Col3a1), 11 extracellular matrix remodeling, and 8 inflammatory genes. In conclusion, the study suggests that the mild activation of NRF2 via the protein-protein interaction inhibitor PHAR holds promise as a strategy for addressing NASH and its progression to liver fibrosis
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/38184999/
Curcumin enhances the anti-obesogenic activity of orlistat through SKN-1/NRF2-dependent regulation of nutrient metabolism in Caenorhabditis elegans
Background: Metabolic dysregulation, a defining feature of obesity, disrupts essential signalling pathways involved in nutrient sensing and mitochondria homeostasis. The nuclear factor erythroid 2-related factor 2 (NRF-2) serves as a pivotal regulator of the cellular stress response, and recent studies have implicated it in the pathogenesis of obesity, diabetes, and metabolic syndrome. Curcumin, a polyphenolic compound derived from turmeric, has been identified as a potent activator of NRF-2. Evidence suggests curcumin impacts obesity and metabolic disorders by modulating gut microbiota composition, increasing energy expenditure, and regulating lipid metabolism. Orlistat, an anti-obesity drug, inhibits fat absorption in the gastrointestinal tract, but its side effects limits its broader use.
Objectives: The present study aims to investigate the potential synergetic effect of a hybrid combination between orlistat and curcumin. Additionally, we provide a detailed understanding of the molecular mechanisms through which this combination mitigates glucose-induced lipid accumulation in Caenorhabditis elegans, with a focus on the role of the skinhead 1 (SKN-1) transcription factor, an orthologue of NRF2.
Methods: We assessed the lipid accumulation and the changes in skn-1 transcriptional activity in C. elegans using confocal GFP-based detection, alongside mRNA expression analysis of genes from lipid metabolism and oxidative stress response in wild-type, QV225 and LD1 strains. Furthermore, we evaluated locomotion, chemotaxis and mitochondrial dynamics to enhance our understanding of the proposed molecular-based model.
Results: Our findings reveal that the orlistat/curcumin combination exerts an anti-obesogenic effect through SKN-1/NRF2-dependent regulation of conserved genes involved in carbohydrate and lipid metabolism in C. elegans. Moreover, the combination stimulates mitochondrial potential, further contributing to the observed synergistic effects.
Conclusion: The hybrid combination of orlistat and curcumin demonstrates significant anti-obesity activity by regulating nutrient-sensing pathways through SKN-1/NRF-2 modulation. This approach may allow for the reduction of orlistat dosage, thereby minimizing its adverse effects while maintaining its therapeutic efficacy.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39856245/
An oral carbon monoxide-releasing molecule protects against acute hyperhemolysis in sickle cell disease
Acute hyperhemolysis is a severe life-threatening complication in patients with sickle cell disease (SCD) that may occur during delayed hemolytic transfusion reaction (DHTR), or vaso-occlusive crises associated with multiorgan failure. Here, we developed in vitro and in vivo animal models to mimic endothelial damage during the early phase of hyperhemolysis in SCD. We then used the carbon monoxide (CO)-releasing molecule CORM-401 and examined its effects against endothelial activation, damage, and inflammation inflicted by hemolysates containing red blood cell membrane-derived particles. The in vitro results revealed that CORM-401: (1) prevented the upregulation of relevant proinflammatory and proadhesion markers controlled by the NF-κB enhancer of activated B cells, and (2) abolished the expression of the nuclear factor erythroid-2-related factor 2 (Nrf2) that regulates the inducible antioxidant cell machinery. We also show in SCD mice that CORM-401 protects against hemolysate-induced acute damage of target organs such as the lung, liver, and kidney through modulation of NF-κB proinflammatory and Nrf2 antioxidant pathways. Our data demonstrate the efficacy of CORM-401 as a novel therapeutic agent to counteract hemolysate-induced organ damage during hyperhemolysis in SCD. This approach might be considered as possible preventive treatment in high-risk situations such as patients with SCD with history of DHTR.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/38518106/
AA147 Alleviates Symptoms in a Mouse Model of Multiple Sclerosis by Reducing Oligodendrocyte Loss
Inflammation-induced oligodendrocyte death and CNS demyelination are key features of multiple sclerosis (MS). Inflammation-triggered endoplasmic reticulum (ER) stress and oxidative stress promote tissue damage in MS and in its preclinical animal model, experimental autoimmune encephalitis (EAE). Compound AA147 is a potent activator of the ATF6 signaling arm of the unfolded protein response (UPR) that can also induce antioxidant signaling through activation of the NRF2 pathway in neuronal cells. Previous work showed that AA147 protects multiple tissues against ischemia/reperfusion damage through ATF6 and/or NRF2 activation; however, its therapeutic potential in neuroinflammatory disorders remains unexplored. Here, we demonstrate that AA147 ameliorated the clinical symptoms of EAE and reduced ER stress, oligodendrocyte loss, and demyelination. Additionally, AA147 suppressed T cells in the CNS without altering the peripheral immune response. Importantly, AA147 significantly increased the expressions of Grp78, an ATF6 target gene, in oligodendrocytes, while enhancing levels of Grp78 as well as Ho-1, an NRF2 target gene, in microglia. In cultured oligodendrocytes, AA147 promoted nuclear translocation of ATF6, but not NRF2. Intriguingly, AA147 altered the microglia activation profile, possibly by triggering the NRF2 pathway. AA147 was not therapeutically beneficial during the acute EAE stage in mice lacking ATF6 in oligodendrocytes, indicating that protection primarily involves ATF6 activation in these cells. Overall, our results suggest AA147 as a potential therapeutic opportunity for MS by promoting oligodendrocyte survival and regulating microglia status through distinct mechanisms.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39928347/
Novel insights into the central protective role of ACE2 in diabetic cardiomyopathy: from underlying signaling pathways to therapeutic perspectives
Diabetic cardiomyopathy (DCM) is a cardiac complication specific to individuals with diabetes. It is defined as abnormalities of myocardial structure and function in diabetic patients who do not exhibit any obvious coronary artery disease, hypertensive heart disease, valvular heart disease, or inherited cardiomyopathy. A significant cardiovascular protective factor identified recently is angiotensin-converting enzyme 2 (ACE2), which is a rising star in the renin angiotensin system (RAS) and is responsible for the onset and progression of DCM. Nonetheless, there is not a comprehensive review outlining ACE2’s effect on DCM. From the perspective of the pathogenesis of DCM, this review summarizes the myocardial protective role of ACE2 in the aspects of alleviating myocardial structure and dysfunction, correcting energy metabolism disorders, and restoring vascular function. Concurrently, we propose the connections between ACE2 and underlying signaling pathways, including ADAM17, Apelin/APJ, and Nrf2. Additionally, we highlight ACE2-related pharmaceutical treatment options and clinical application prospects for preventing and managing DCM. Further and underlying research is extensively required to completely comprehend the principal pathophysiological mechanism of DCM and the distinctive function of ACE2, switching experimental findings into clinical practice and identifying efficient therapeutic approaches.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39928210/
Skin sensitizers enhance superoxide formation by polycyclic aromatic hydrocarbons via the aldo-keto reductase pathway
Exposure to combustion-derived airborne polycyclic aromatic hydrocarbons (PAHs) may harm human skin, exacerbate cutaneous inflammatory diseases and accelerate skin aging. The toxicity of PAHs is unleashed upon their metabolic activation by cytochrome P450 (CYP) 1 monooxygenases, resulting in the formation of reactive intermediates that form mutagenic DNA adducts. Moreover, PAHs cause oxidative stress, which is primarily due to aldo-keto reductases (AKRs), such as AKR1C3, which convert CYP1-derived PAH-trans-diols to PAH-catechols. The catechols undergo autooxidation leading to the formation of reactive oxygen species (ROS) and PAH-quinones. The latter are highly reactive, mitotoxic and are reduced back to PAH-catechols, thus facilitating redox cycling. As AKR1C expression is inducible by other NRF2-stimulating chemicals, we tested the hypothesis that co-exposure of HaCaT keratinocytes to skin sensitizers and the PAH benzo[a]pyrene (BaP) enhances ROS formation. We observed a synergistic effect of the skin sensitizers on the BaP-induced expression of the NRF2 target genes heme oxygenase-1, sulfiredoxin-1 and AKR1C3. In fact, co-exposure to the skin sensitizers also enhanced the BaP-induced formation of superoxide anions. Intriguingly, the co-exposure-related ROS formation was abolished upon inhibition of either CYP1A1 or AKR1C3. Testing of additional skin-sensitizing compounds, differing in their mode of action, indicated that especially potent Michael acceptors enhance the toxicity of BaP by increasing AKR1C3 expression and, presumably, downstream BaP-quinone formation. Our study reveals potential health risks associated with the simultaneous exposure to common skin-sensitizing substances and ubiquitous PAHs, and implies a role for NRF2 in mediating PAH toxicity.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39922325/
Methylmercury Chronic Exposure and a High-Fat Diet Induce Gut Microbiome Alterations and Intestinal Barrier Disruption in Mice
Methylmercury (MeHg) is markedly toxic to humans. Our study explores whether MeHg and high-fat diet (HFD) can impair the intestinal barrier with microbiota dysbiosis in mice. Weanling mice were fed to HFD or standard diet for 40 days. In the last 20 days of diets, mice received either MeHg (20 mg/L) or drinking water. Proximal small intestine, cecum, and hair samples were collected. Villus length, crypt depth, villus/crypt length, mucin2 and lysozyme-positive cell counts, ZO-1 and occludin gene expression, and intestinal functional permeability were analyzed to assess the intestinal barrier. Blood samples were drawn to assess lipid parameters. Gut microbiome profiling was conducted with DNA from fecal/cecal samples. In addition, we analyzed ZO-1 immunofluorescence in the colon and small intestine. HFD increased MDA, Mucin2, and reduced villus height, crypt depth, villus/crypt length, lysozyme(+)-cell count, and increased intestinal permeability, regardless of MeHg intoxication. MeHg-HFD combination affected the intestinal barrier, decreasing ZO-1, occludin, and Nrf2 transcription, and increased permeability. HFD increased total plasma cholesterol and triglycerides. Only MeHg-HFD reduced microbiome alpha-diversity along with colonic ZO-1 immunolabeling loss compared to non-intoxicated mice fed a control diet. Regardless of diet, the genera Streptococcus, Psychrobacter, Facklamia, and Corynebacterium were severely depleted following MeHg intoxication. Other groups, such as Atopostipes and Jeotgalicoccus, were not altered by MeHg or HFD alone, but were significantly reduced by the combined HFD-MeHg. Synergistic effects of MeHg-HFD on the mucosa-associated microbiota are more pronounced than their individual effects. Our findings suggest that MeHg intoxication does not cause extensive dysbiosis but led to intestinal barrier disruption. C.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39921560/
KLF5 promotes esophageal squamous cell carcinoma radioresistance by targeting the Keap1-Nrf2 pathway
Objective: Esophageal squamous cell carcinoma (ESCC) has high morbidity and mortality in developing countries. The purpose of this article is to study the mechanism of KLF5’s effect on ESCC radiosensitivity.
Methods: WGCNA gene expression profiling identified core genes associated with ESCC radiosensitivity. KLF5 expression was detected by RT-qPCR. The effects of overexpression or downregulation of KLF5 on anti-irradiated cells’ proliferation, migration, invasion, and apoptotic activity were studied through colony formation assay, Transwell assay, and flow cytometry. Western blot can detect the activity of Nrf2 signaling pathway in cells and tissues. The enrichment of KLF5 at the Keap1 promoter was analyzed by ChIP-base, and the binding of KLF5 to Keap1 was analyzed by ChIP and dual-luciferase. They then injected ESCC cells into mice and used radiation to monitor tumor progression.
Results: KLF5 is a core gene in ESCC and is significantly associated with radiosensitivity. KLF5 expression is upregulated in drug-resistant ESCC cells. Overexpression of KLF5 significantly increased cell viability and attenuated cellular responses to radiation. KLF5 knockdown reduces radioresistance. After KLF5 overexpression, the Nrf2 signaling pathway was significantly up-regulated, and after KLF5 was up-regulated, the Keap1 signaling pathway was down-regulated. KLF5 inhibits the transcriptional activity of Keap1. Upregulation of Keap1 inhibits the effect of KLF5 overexpression on radioresistance of ESCC cells. KLF5/Keap1 regulates the effects of ESCC on in vivo radiotherapy.
Conclusion: KLF5 promotes ESCC radioresistance by inhibiting Keap1 transcription and activating the Nrf2 pathway.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39918680/
Modified citrus pectin ameliorates methotrexate-induced hepatic and pulmonary toxicity: role of Nrf2, galectin-3/TLR-4/NF-κB/TNF-α and TGF-β signaling pathways
Introduction: Methotrexate (MTX) is a frequently utilized anti-inflammatory and anticancer agent. Its potential liver and lung toxicity often limits its clinical effectiveness. We conducted this study to demonstrate the possible protective impacts of a natural galectin-3 (Gal-3) inhibitor, modified citrus pectin (MCP), against MTX-induced liver and lung toxicity and verify the potential signaling pathways of these suggested effects. In vitro, the cytotoxicity of MCP and its modulatory effect on MTX cytotoxic efficacy were assessed.
Methods: Four groups of rats were used: control, MTX (40 mg/kg, single intraperitoneal injection on day 9), MTX + MCP (200 mg/kg/day, orally, for 2 weeks), and MCP alone. MCF7, Nalm6, and JEG3 cell lines were used for the in vitro cytotoxicity assay.
Results: MCP counteracted liver and lung toxicity evidenced by ameliorating the markers of liver and lung functions. Moreover, MCP minimized oxidative stress elicited by MTX in lung and liver tissues, as indicated by reduced malondialdehyde levels, elevated levels of reduced glutathione, increased superoxide dismutase activity, and upregulated Nrf2 protein expression. In hepatic and pulmonary tissues, MCP downregulated the inflammatory signaling pathway, Gal-3/TLR-4/NF-κB/TNF-α. MCP pretreatment decreased TGF-β, collagen content, and cleaved caspase-3 levels. MCP enhanced the cytotoxicity of MTX in Nalm6 and JEG3 and did not interfere with its cytotoxicity in the MCF7 cell lines.
Discussion: MCP attenuated MTX-induced liver and lung toxicity through antioxidant, anti-fibrotic, anti-inflammatory, and anti-apoptotic influences, as demonstrated by the improved histopathological changes induced by MTX in pulmonary and hepatic tissues. Moreover, it increased MTX cytotoxicity in different human cell lines.
Access to the original article: https://pubmed.ncbi.nlm.nih.gov/39917614/
Joana Miranda
Faculty of Pharmacy, University of Lisbon
Portugal
