Lipid-derived electrophiles inhibit the function of membrane channels during ferroptosis.

The therapeutic targeting of ferroptosis requires full understanding of the molecular mechanism of this regulated cell death pathway. While lipid-derived electrophiles (LDEs), including 4-hydroxy-2-nonenal (4-HNE), are important biomarkers of ferroptosis, a functional role for these highly reactive species in ferroptotic cell death execution has not been established. Here, through mechanistic characterization of LDE-detoxification impairment, we demonstrate that LDEs mediate altered protein function during ferroptosis. Applying live cell fluorescence imaging, we first identified that export of glutathione-LDE-adducts through multidrug resistance-associated protein (MRP) channels is inhibited following exposure to a panel of ferroptosis inducers (FINs) with different modes of action (type I-IV FINs erastin, RSL3, FIN56, and FINO2). This channel inhibition was recreated by both initiation of lipid peroxidation and treatment with 4-HNE. Importantly, treatment with radical-trapping antioxidants prevented impaired LDE-adduct export when working with both FINs and lipid peroxidation initiators but not 4-HNE, pinpointing LDEs as the cause of this inhibited MRP activity observed during ferroptosis. Our findings, when combined with reports of widespread LDE alkylation of key proteins following ferroptosis induction, including MRP1, set a precedent for LDEs as critical mediators of ferroptotic cell damage. Lipid hydroperoxide breakdown to form truncated phospholipids and LDEs may fully explain membrane permeabilization and modified protein function downstream of lipid peroxidation, offering a unified explanation of the molecular cell death mechanism of ferroptosis.

Anti-Biofilm Activity of Oleacein and Oleocanthal from Extra-Virgin Olive Oil toward Pseudomonas aeruginosa.

New antimicrobial molecules effective against Pseudomonas aeruginosa, known as an antibiotic-resistant "high-priority pathogen", are urgently required because of its ability to develop biofilms related to healthcare-acquired infections. In this study, for the first time, the anti-biofilm and anti-virulence activities of a polyphenolic extract of extra-virgin olive oil as well as purified oleocanthal and oleacein, toward P. aeruginosa clinical isolates were investigated. The main result of our study was the anti-virulence activity of the mixture of oleacein and oleocanthal toward multidrug-resistant and intermediately resistant strains of P. aeruginosa isolated from patients with ventilator-associated pneumonia or surgical site infection. Specifically, the mixture of oleacein (2.5 mM)/oleocanthal (2.5 mM) significantly inhibited biofilm formation, alginate and pyocyanin production, and motility in both P. aeruginosa strains (p < 0.05); scanning electron microscopy analysis further evidenced its ability to inhibit bacterial cell adhesion as well as the production of the extracellular matrix. In conclusion, our results suggest the potential application of the oleacein/oleocanthal mixture in the management of healthcare-associated P. aeruginosa infections, particularly in the era of increasing antimicrobial resistance.

Anti-Cancer, Anti-Angiogenic, and Anti-Atherogenic Potential of Key Phenolic Compounds from Virgin Olive Oil.

The Mediterranean diet, renowned for its health benefits, especially in reducing cardiovascular risks and protecting against diseases like diabetes and cancer, emphasizes virgin olive oil as a key contributor to these advantages. Despite being a minor fraction, the phenolic compounds in olive oil significantly contribute to its bioactive effects. This review examines the bioactive properties of hydroxytyrosol and related molecules, including naturally occurring compounds (-)-oleocanthal and (-)-oleacein, as well as semisynthetic derivatives like hydroxytyrosyl esters and alkyl ethers. (-)-Oleocanthal and (-)-oleacein show promising anti-tumor and anti-inflammatory properties, which are particularly underexplored in the case of (-)-oleacein. Additionally, hydroxytyrosyl esters exhibit similar effectiveness to hydroxytyrosol, while certain alkyl ethers surpass their precursor's properties. Remarkably, the emerging research field of the effects of phenolic molecules related to virgin olive oil on cell autophagy presents significant opportunities for underscoring the anti-cancer and neuroprotective properties of these molecules. Furthermore, promising clinical data from studies on hydroxytyrosol, (-)-oleacein, and (-)-oleocanthal urge further investigation and support the initiation of clinical trials with semisynthetic hydroxytyrosol derivatives. This review provides valuable insights into the potential applications of olive oil-derived phenolics in preventing and managing diseases associated with cancer, angiogenesis, and atherosclerosis.

Comparative Analysis of Olive-Derived Phenolic Compounds' Pro-Melanogenesis Effects on B16F10 Cells and Epidermal Human Melanocytes.

Olive leaf contains plenty of phenolic compounds, among which oleuropein (OP) is the main component and belongs to the group of secoiridoids. Additionally, phenolic compounds such as oleocanthal (OL) and oleacein (OC), which share a structural similarity with OP and two aldehyde groups, are also present in olive leaves. These compounds have been studied for several health benefits, such as anti-cancer and antioxidant effects. However, their impact on the skin remains unknown. Therefore, this study aims to compare the effects of these three compounds on melanogenesis using B16F10 cells and human epidermal cells. Thousands of gene expressions were measured by global gene expression profiling with B16F10 cells. We found that glutaraldehyde compounds derived from olive leaves have a potential effect on the activation of the melanogenesis pathway and inducing differentiation in B16F10 cells. Accordingly, the pro-melanogenesis effect was investigated by means of melanin quantification, mRNA, and protein expression using human epidermal melanocytes (HEM). This study suggests that secoiridoid and its derivates have an impact on skin protection by promoting melanin production in both human and mouse cell lines.

Epithelial-mesenchymal interaction protects normal colonocytes from 4-HNE-induced phenotypic transformation.

INTRODUCTION: Recent studies have shown that epithelial-stromal interactions could play a role in the development of colorectal cancer. Here, we investigated the role of fibroblasts in the transformation of normal colonocytes induced by 4-HNE. METHODS: Normal Co colonocytes and nF fibroblasts from the same mouse colon were exposed, in monoculture (m) or coculture (c), to 4-HNE (5 µM) twice weekly for 3 weeks. Gene expression was then analysed and the ability of Co colonocytes to grow in anchorage-independent conditions was tested in soft agar. Fibroblasts previously treated or not with 4-HNE were also seeded in culture inserts positioned above the agar layers to allow paracrine exchanges with colonocytes. RESULTS: First, 60% of the genes studied were modulated by coculture in Co colonocytes, with notably increased expression of BMP receptors. Furthermore, while 4-HNE increased the ability of monoculture-treated Co colonocytes to form colonies, this effect was not observed in coculture-treated Co colonocytes. Adding a selective BMPR1 inhibitor during the treatment phase abolished the protective effect of coculture. Conversely, addition of a BMP4 agonist to the medium of monoculture-treated Co colonocytes prevented phenotypic transformation by 4-HNE. Second, the presence of nF(m)-HNE fibroblasts during the soft agar assay increased the number and size of Co(m) colonocyte colonies, regardless of whether these cells had been previously treated with 4-HNE in monoculture. For soft agar assays performed with nF(c) and Co(c) cells initially treated in coculture, only the reassociation between Co(c)-HNE and nF(c)-HNE resulted in a small increase in the number of colonies. CONCLUSIONS: During the exposure phase, the epithelial-mesenchymal interaction protected colonocytes from 4-HNE-induced phenotypic transformation via activation of the BMP pathway. This intercellular dialogue also limited the ability of fibroblasts to subsequently promote colonocyte-anchorage-independent growth. In contrast, fibroblasts pre-exposed to 4-HNE in monoculture strongly increased the ability of Co(m) colonocytes to form colonies.

Nanofabrication of citronellal with chitosan biopolymer to boost its efficacy against aflatoxin B1 and Aspergillus flavus mediated biodeterioration of active ingredient of Piper longum.

The study reports the efficacy of nanofabricated citronellal inside the chitosan biopolymer (NeCn) against Aspergillus flavus growth, aflatoxin B1 (AFB1) production, and active ingredient biodeterioration (Piperine) in Piper longum L. The prepared NeCn was characterized by Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and Fourier Transform Infrared Spectroscopy (FTIR). The results revealed that the NeCn exhibited distantly improved antifungal (1.25 µL/mL) and AFB1 inhibition (1.0 µL/mL) compared to free Cn. The perturbances in membrane function, mitochondrial membrane potential, antioxidant defense system, and regulatory genes (Ver-1 and Nor-1) of AFB1 biosynthesis were reported as probable modes of action of NeCn. The NeCn (1.25 µL/mL) effectively protects the P. longum from A. flavus (78.8%), AFB1 contamination (100%), and deterioration of Piperine (62.39%), thus demonstrating its potential as a promising novel antifungal agent for food preservation.

Receptors underlying an odorant's valence across concentrations in Drosophila larvae.

Odorants interact with receptors expressed in specialized olfactory neurons, and neurons of the same class send their axons to distinct glomeruli in the brain. The stereotypic spatial glomerular activity map generates recognition and the behavioral response for the odorant. The valence of an odorant changes with concentration, typically becoming aversive at higher concentrations. Interestingly, in Drosophila larvae, the odorant (E)-2-hexenal is aversive at low concentrations and attractive at higher concentrations. We investigated the molecular and neural basis of this phenomenon, focusing on how activities of different olfactory neurons conveying opposing effects dictate behaviors. We identified the repellant neuron in the larvae as one expressing the olfactory receptor Or7a, whose activation alone at low concentrations of (E)-2-hexenal elicits an avoidance response in an Or7a-dependent manner. We demonstrate that avoidance can be overcome at higher concentrations by activation of additional neurons that are known to be attractive, most notably odorants that are known activators of Or42a and Or85c. These findings suggest that in the larval stage, the attraction-conveying neurons can overcome the aversion-conveying channels for (E)-2-hexenal.

In Situ Reaction-Generated Aldehyde-Scavenging Polypeptides-Curcumin Conjugate Nanoassemblies for Combined Treatment of Spinal Cord Injury.

The microenvironment after traumatic spinal cord injury (SCI) involves complex pathological processes, including elevated oxidative stress, accumulated reactive aldehydes from lipid peroxidation, excessive immune cell infiltration, etc. Unfortunately, most of current neuroprotection therapies cannot cope with the intricate pathophysiology of SCI, leading to scant treatment efficacies. Here, we developed a facile in situ reaction-induced self-assembly method to prepare aldehyde-scavenging polypeptides (PAH)-curcumin conjugate nanoassemblies (named as PFCN) for combined neuroprotection in SCI. The prepared PFCN could release PAH and curcumin in response to oxidative and acidic SCI microenvironment. Subsequently, PFCN exhibited an effectively neuroprotective effect through scavenging toxic aldehydes as well as reactive nitrogen and oxygen species in neurons, modulating microglial M1/M2 polarization, and down-regulating the expression of inflammation-related cytokines to inhibit neuroinflammation. The intravenous administration of PFCN could significantly ameliorate the malignant microenvironment of injured spinal cord, protect the neurons, and promote the motor function recovery in the contusive SCI rat model.

2-iodohexadecanal induces autophagy during goiter involution.

BACKGROUND: Iodine plays an important role in thyroid physiology and biochemistry. The thyroid is capable of producing different iodolipids such as 2-iodohexadecanal (2-IHDA). Data from different laboratories have shown that 2-IHDA inhibits several thyroid parameters and it has been postulated as intermediary on the action of iodide function. OBJECTIVE: To explore different mechanisms involved during the involution of the hyperplastic thyroid gland of Wistar rats towards normality induced by 2-IHDA. METHODS: Goiter was induced by the administration of MMI for 10 days, then the treatment was discontinued and Wistar rats were injected with 2-IHDA or KI. RESULTS: During involution, 2-IHDA treatment reduced PCNA expression compared to spontaneous involution. KI treatment caused an increase of Caspase-3 activity and TUNEL-positive cells. In contrast, 2-IHDA failed to alter this value but induced an increase of LC3B expression. KI but not 2-IHDA led to an increase in peroxides levels, catalase and glutathione peroxidase activity. CONCLUSIONS: We demonstrated that 2-IHDA, in contrast to iodide, did not lead to an increase in oxidative stress or apoptosis induction, indicating that the involution triggered by 2-IHDA in Wistar rats, is primarily due to the inhibition of cell proliferation and the induction of autophagy.

Computational and physicochemical insight into 4-hydroxy-2-nonenal induced structural and functional perturbations in human low-density lipoprotein.

Lipid peroxidation (LPO) is a biological process that frequently occurs under physiological conditions. Undue oxidative stress increases the level of LPO; which may further contribute to the development of cancer. 4-Hydroxy-2-nonenal (HNE), one of the principal by-products of LPO, is present in high concentrations in oxidatively stressed cells. HNE rapidly reacts with various biological components, including DNA and proteins; however, the extent of protein degradation by lipid electrophiles is not well understood. The influence of HNE on protein structures will likely have a considerable therapeutic value. This research elucidates the potential of HNE, one of the most researched phospholipid peroxidation products, in modifying low-density lipoprotein (LDL). In this study, we tracked the structural alterations in LDL by HNE using various physicochemical techniques. To comprehend the stability, binding mechanism and conformational dynamics of the HNE-LDL complex, computational investigations were carried out. LDL was altered in vitro by HNE, and the secondary and tertiary structural alterations were examined using spectroscopic methods, such as UV-visible, fluorescence, circular dichroism and fourier transform infrared spectroscopy. Carbonyl content, thiobarbituric acid-reactive-substance (TBARS) and nitroblue tetrazolium (NBT) reduction assays were used to examine changes in the oxidation status of LDL. Thioflavin T (ThT), 1-anilinonaphthalene-8-sulfonic (ANS) binding assay and electron microscopy were used to investigate aggregates formation. According to our research, LDL modified by HNE results in changes in structural dynamics, oxidative stress and the formation of LDL aggregates. The current investigation must characterize HNE's interactions with LDL and comprehend how it can change their physiological or pathological functions.Communicated by Ramaswamy H. Sarma.

2-Methoxybenzaldehyde effectively repels ants.

Ants can particularly make for harmful pests, infesting human homes and reducing crop yields. The damage caused by ants and the efforts to mitigate the damage are hugely costly. Broad-spectrum insecticides are used most commonly; however, due to their negative side effects, there is increasing interest in nontoxic alternatives. One promising commercially available alternative is 2-hydroxybenzaldehyde, which is naturally produced by various arthropods as a means of chemical defense and effectively repels ants. Here we conduct a structure-activity relationship investigation, testing how different chemical modifications alter the repellence of 2-hydroxybenzaldehyde. We find that 2-methoxybenzaldehyde is considerably more effective than 2-hydroxybenzaldehyde at repelling the common black garden ant, Lasius niger. We next compare the most effective repellent chemicals against 4 particularly harmful ant species to confirm that the results obtained with L. niger are general to ants and that our results are relevant to mitigate the costs of ant damage.

Neuroprotective effect of isovaleraldehyde accompanied with upregulation of BDNF and CREB phosphorylation via the PKA pathway.

Recently, the number of patients diagnosed with dementia has increased. The World Health Organization (WHO) estimates that 50 million patients suffer from dementia. Although several therapeutic strategies have been proposed, currently, there is no curative approach for treating dementia. Neurodegeneration is an irreversible process. As this disease gradually progresses over 15-20 years, a low-cost and sustainable method for preventing these diseases is desired. Cacao nib is consumed in many countries, and a recent clinical study indicated that cocoa intake upregulates brain-derived neurotrophic factor (BDNF), which plays a significant role in memory formation and neuronal cell survival. In the present study, neural cells were treated with cacao nib extract or the 17 characteristic components of cacao nib. Treatment with Cacao nib extract upregulates BDNF mRNA expression. In addition, cacao nib extract elicits the phosphorylation of cAMP-response-element-binding protein (CREB), which regulates the transcription of BDNF. Among the 17 species screened, isovaleraldehyde (IVA), also known as an aroma component of cacao nibs extract, improved BDNF mRNA expression without SH-SY5Y cell toxicity. IVA also promoted CREB phosphorylation through a cAMP-dependent protein kinase (PKA)-dependent mechanism. In conclusion, IVA could be responsible for the BDNF upregulation effect of cacao nib, and IVA upregulated BDNF expression via the PKA-CREB axis.

Crosslinking kiwifruit-derived DNA with natural aromatic aldehydes generates membranolytic antibacterial nanogels.

Improper use of antibiotics has led to the global rise of drug-resistant biofilm bacteria. Thus, researchers have been increasingly interested in green materials that are highly biocompatible and have low toxicity. Here, nanogels (NGs) with imine bonds were synthesized by crosslinking kiwifruit-derived DNA's primary amine and aromatic aldehydes (cuminaldehyde, p-anisaldehyde, or vanillin) under water-in-hexane emulsion processes. Transmission electron microscope showed that the NGs had spherical geometry with an average particle size ranging from 40 to 140 nm and that the zeta potential indicated a negative charge. Additionally, the DNA-aromatic aldehyde NGs showed low cytotoxicity toward normal cell organoids and human RBCs in cell viability tests. These NGs were also tested against four pathogenic bacteria for various assays. DNA-vanillin (DNA-VA) NGs exhibited significant antibacterial effects against bacteria with very low inhibitory concentrations as seen in a minimum inhibitory concentration assay. Scanning electron microscope observation revealed that the bacteria were deformed, and immunoblotting detected intracellular groEL protein expression. In agreement with these results, DNA-aromatic aldehyde NGs successfully protected C. elegans from P. aeruginosa-induced lethality. These DNA NGs provided a multivalent 3D space for antibacterial aromatic aldehydes to tether, enhancing their interaction with the bacterial wall. These results offer a new direction for the development of novel antibiotics in the future.

Computational study on Schiff base derived salicylaldehyde and furfuraldehyde derivatives as potent anti-tubercular agents: prospect to dihydropteroate synthase inhibitors.

Nowadays, bacterial multidrug resistance has become a commonplace problem in clinics due to several intrinsic factors mediated through resistance to antibacterials obtained via bacterial consortia and extrinsic factors, such as non-uniform antibacterial policy and migration of resistant bacteria through human and other routes. The development of newer, effective anti-mycobacterial candidate(s) is coveted by clinics. Hybrid molecules would be comparatively more emulating against invasive bacterial strains; nevertheless, newer antibiotics are continually added. Herein, designing and developments of two series of Schiff-based salicylaldehyde S1-S7 and furfuraldehyde F1-F7 molecules individually bearing sulfonamide group are described; and those were synthesized and their structures by spectral characterization were confirmed. Concomitantly, molecule dynamic simulations of all atoms had been performed to fathom the mechanism of the action with these leading complexes. These data imply that the synthesized Schiff-based salicylaldehyde hybrids would be promising anti-tubercular compounds, which further need potent pharmacological evaluations.Communicated by Ramaswamy H. Sarma.

ß-escin activates ALDH and prevents cigarette smoke-induced cell death.

BACKGROUND: The tobacco use is one of the biggest public health threats worldwide. Cigarette smoke contains over 7000 chemicals among other aldehydes, regarded as priority toxicants. ß-escin (a mixture of triterpenoid saponins extracted from the Aesculus hippocastanum. L) is a potent activator of aldehyde dehydrogenase (ALDH) - an enzyme catalyzing oxidation of aldehydes to non-toxic carboxylic acids. PURPOSE: The aim of this study was to evaluate the effect of ß-escin on ALDH activity, ALDH isoforms mRNA expression and cytotoxicity in nasal epithelial cells exposed to cigarette smoke extract (CSE). METHODS: Nasal epithelial cells from healthy non-smokers were treated with ß-escin (1 µM) and exposed to 5% CSE. After 6- or 24-hours of stimulation cell viability, DNA damage, ALDH activity and mRNA expression of ALDH isoforms were examined. RESULTS: 24 h ß-escin stimulation revised CSE induced cytotoxicity and DNA damage. Cells cultured with ß-escin or exposed to CSE responded with strong increase in ALDH activity. This effect was more pronounced in cultures treated with combination of ß-escin and CSE. The strongest stimulatory effect on ALDH isoform mRNA expression was observed in cells cultured simultaneously with ß-escin and CSE: at 6 h for ALDH1A1 and ALDH3A1, and at 24 h for ALDH1A3, ALDH3A2, ALDH3B1, and ALDH18A1. Combined ß-escin and CSE treatment prevented the CSE-induced inhibition of ALDH2 expression at 24 h. CONCLUSIONS: ß-escin is an effective ALDH stimulatory and cytoprotective agent and might be useful in the prevention or supportive treatment of tobacco smoke-related diseases.

Performance of TMRM and Mitotrackers in mitochondrial morphofunctional analysis of primary human skin fibroblasts.

Mitochondrial membrane potential (Δψ) and morphology are considered key readouts of mitochondrial functional state. This morphofunction can be studied using fluorescent dyes ("probes") like tetramethylrhodamine methyl ester (TMRM) and Mitotrackers (MTs). Although these dyes are broadly used, information comparing their performance in mitochondrial morphology quantification and Δψ-sensitivity in the same cell model is still scarce. Here we applied epifluorescence microscopy of primary human skin fibroblasts to evaluate TMRM, Mitotracker Red CMXros (CMXros), Mitotracker Red CMH2Xros (CMH2Xros), Mitotracker Green FM (MG) and Mitotracker Deep Red FM (MDR). All probes were suited for automated quantification of mitochondrial morphology parameters when Δψ was normal, although they did not deliver quantitatively identical results. The mitochondrial localization of TMRM and MTs was differentially sensitive to carbonyl cyanide-4-phenylhydrazone (FCCP)-induced Δψ depolarization, decreasing in the order: TMRM ≫ CHM2Xros = CMXros = MDR > MG. To study the effect of reversible Δψ changes, the impact of photo-induced Δψ "flickering" was studied in cells co-stained with TMRM and MG. During a flickering event, individual mitochondria displayed subsequent TMRM release and uptake, whereas this phenomenon was not observed for MG. Spatiotemporal and computational analysis of the flickering event provided evidence that TMRM redistributes between adjacent mitochondria by a mechanism dependent on Δψ and TMRM concentration. In summary, this study demonstrates that: (1) TMRM and MTs are suited for automated mitochondrial morphology quantification, (2) numerical data obtained with different probes is not identical, and (3) all probes are sensitive to FCCP-induced Δψ depolarization, with TMRM and MG displaying the highest and lowest sensitivity, respectively. We conclude that TMRM is better suited for integrated analysis of Δψ and mitochondrial morphology than the tested MTs under conditions that Δψ is not substantially depolarized.

N-phenyl and N-benzyl substituted succinimides: Preclinical evaluation for their antihypertensive effect and underlying mechanism.

The study was designed to investigate the antihypertensive potential of 2-(2, 5-dioxo-1-phenylpyrrolidin-3-yl)-3-(4-isopropylphenyl)-2-methylpropanal (Comp-1) and 2-(1-benzyl-2,5-dioxopyrrolidin-3-yl)-3-(4-isopropylphenyl)-2-methylpropanal (Succ-5) in rats. The study results showed that, just like nifedipine (the standard reference drug), the test compounds, Comp-1 (at doses of 15 and 20 mg/kg) and Succ-5 (at a dose of 20 mg/kg) had significant antihypertensive effect against deoxycorticosterone acetate-salted rats. The test compounds maintained the level of cardiac markers troponin I and creatinine kinase myocardial bands (CK-MB) in serum, and modulate the oxidative stress markers Glutathione s-transferase (GST) activity, reduced glutathione (GSH), catalase levels, and lipid peroxidation (LPO). These compounds also reduced the expression of inflammatory markers, including cyclooxygenase-2 (COX-2) and tumor necrosis factor alpha (TNF-α) in heart tissues. Furthermore, in the ex-vivo study, the test substances relaxed the contractions induced by phenylephrine (PE) and potassium (K+). Vasodilation was endothelium-independent because the test substances showed nearly the same effect in aortic rings with intact endothelium, denuded endothelium, and with L-NAME pretreatment. The test compounds shifted the calcium curve to the right, i.e., contraction was inhibited and decreased the maximal response. This study demonstrated the antihypertensive, anti-inflammatory, antioxidant, and vasodilate effects of the test compounds. In addition, the results supported the phenomenon of calcium channel blockades responsible for vasodilation.

Aldehyde dehydrogenase 2-mediated aldehyde metabolism promotes tumor immune evasion by regulating the NOD/VISTA axis.

BACKGROUND: Aldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme involved in endogenous aldehyde detoxification and has been implicated in tumor progression. However, its role in tumor immune evasion remains unclear. METHODS: Here, we analyzed the relationship between ALDH2 expression and antitumor immune features in multiple cancers. ALDH2 knockout tumor cells were then established using CRISPR/Cas9 system. In immunocompetent breast cancer EMT6 and melanoma B16-F10 mouse models, we investigated the impact of ALDH2 blockade on cytotoxic T lymphocyte function and tumor immune microenvironment by flow cytometry, mass cytometry, Luminex liquid suspension chip detection, and immunohistochemistry. Furthermore, RNA sequencing, flow cytometry, western blot, chromatin immunoprecipitation assay, and luciferase reporter assays were employed to explore the detailed mechanism of ALDH2 involved in tumor immune evasion. Lastly, the synergistic therapeutic efficacy of blocking ALDH2 by genetic depletion or its inhibitor disulfiram in combination with immune checkpoint blockade (ICB) was investigated in mouse models. RESULTS: In our study, we uncovered a positive correlation between the expression level of ALDH2 and T-cell dysfunction in multiple cancers. Furthermore, blocking ALDH2 significantly suppressed tumor growth by enhancing cytotoxic activity of CD8+ T cells and reshaping the immune landscape and cytokine milieu of tumors in vivo. Mechanistically, inhibiting ALDH2-mediated metabolism of aldehyde downregulated the expression of V-domain Ig suppressor of T-cell activation (VISTA) via inactivating the nucleotide oligomerization domain (NOD)/nuclear factor kappa-B (NF-κB) signaling pathway. As a result, the cytotoxic function of CD8+ T cells was revitalized. Importantly, ALDH2 blockade markedly reinforced the efficacy of ICB treatment. CONCLUSIONS: Our data delineate that ALDH2-mediated aldehyde metabolism drives tumor immune evasion by activating the NOD/NF-κB/VISTA axis. Targeting ALDH2 provides an effective combinatorial therapeutic strategy for immunotherapy.

A patent review on aldehyde dehydrogenase inhibitors: an overview of small molecule inhibitors from the last decade.

INTRODUCTION: Physiological and pathophysiological effects arising from detoxification of aldehydes in humans implicate the enzyme aldehyde dehydrogenase (ALDH) gene family comprising of 19 isoforms. The main function of this enzyme family is to metabolize reactive aldehydes to carboxylic acids. Dysregulation of ALDH activity has been associated with various diseases. Extensive research has since gone into studying ALHD isozymes, their structural biology and developing small-molecule inhibitors. Novel chemical strategies to enhance the selectivity of ALDH inhibitors have now appeared. AREAS COVERED: A comprehensive review of patent literature related to aldehyde dehydrogenase inhibitors in the last decade and half (2007-2022) is provided. EXPERT OPINION: Aldehyde dehydrogenase (ALDH) is an important enzyme that metabolizes reactive exogenous and endogenous aldehydes in the body through NAD(P)±dependent oxidation. Hence this family of enzymes possess important physiological as well as toxicological roles in human body. Significant efforts in the field have led to potent inhibitors with approved clinical agents for alcohol use disorder therapy. Further clinical translation of novel compounds targeting ALDH inhibition will validate the promised therapeutic potential in treating many human diseases.The scientific/patent literature has been searched on SciFinder-n, Reaxys, PubMed, Espacenet and Google Patents. The search terms used were 'ALDH inhibitors', 'Aldehyde Dehydrogenase Inhibitors'.

4-Hydroxynonenal impairs miRNA maturation in heart failure via Dicer post-translational modification.

BACKGROUND AND AIMS: Developing novel therapies to battle the global public health burden of heart failure remains challenging. This study investigates the underlying mechanisms and potential treatment for 4-hydroxynonenal (4-HNE) deleterious effects in heart failure. METHODS: Biochemical, functional, and histochemical measurements were applied to identify 4-HNE adducts in rat and human failing hearts. In vitro studies were performed to validate 4-HNE targets. RESULTS: 4-HNE, a reactive aldehyde by-product of mitochondrial dysfunction in heart failure, covalently inhibits Dicer, an RNase III endonuclease essential for microRNA (miRNA) biogenesis. 4-HNE inhibition of Dicer impairs miRNA processing. Mechanistically, 4-HNE binds to recombinant human Dicer through an intermolecular interaction that disrupts both activity and stability of Dicer in a concentration- and time-dependent manner. Dithiothreitol neutralization of 4-HNE or replacing 4-HNE-targeted residues in Dicer prevents 4-HNE inhibition of Dicer in vitro. Interestingly, end-stage human failing hearts from three different heart failure aetiologies display defective 4-HNE clearance, decreased Dicer activity, and miRNA biogenesis impairment. Notably, boosting 4-HNE clearance through pharmacological re-activation of mitochondrial aldehyde dehydrogenase 2 (ALDH2) using Alda-1 or its improved orally bioavailable derivative AD-9308 restores Dicer activity. ALDH2 is a major enzyme responsible for 4-HNE removal. Importantly, this response is accompanied by improved miRNA maturation and cardiac function/remodelling in a pre-clinical model of heart failure. CONCLUSIONS: 4-HNE inhibition of Dicer directly impairs miRNA biogenesis in heart failure. Strikingly, decreasing cardiac 4-HNE levels through pharmacological ALDH2 activation is sufficient to re-establish Dicer activity and miRNA biogenesis; thereby representing potential treatment for patients with heart failure.