Neurodegenerative diseases' treatments still represent one of the major unmet medical needs, and their related clinical trials are characterized by one of the highest failure rates. Despite the promising preclinical premises, pioglitazone lies among those drugs that failed clinical translation. It is an antidiabetic drug acting as a PPARγ agonist and later repurposed as a competitive and selective MAO-B inhibitor featuring polyhedral neuroprotective properties. In pursuing our efforts to broaden the therapeutic potential of pioglitazone toward the neurodegenerative context, we herein developed and preliminarily characterized a new series of glitazone derivatives. Particularly, by means of different connectors, a disulfide covalent warhead was attached to the 5-benzylthiazolidine-2,4-dione head to potentially engage cysteines located in MAO-B and PPARγ binding sites and turn pioglitazone into a prolonged-acting modulator. Interestingly, compound 5 emerged as a selective competitive MAO-B inhibitor and a PPARγ agonist with a very slow dissociation rate, revealing long-lasting target engagement, albeit exhibiting lower potencies with respect to pioglitazone. This peculiar biological profile resulted in promising antioxidant and anti-inflammatory properties, laying the ground for future development of covalent pioglitazone derivatives.

Cystic Fibrosis (CF), a multi-organ disease stemming from CFTR gene mutations, is characterized by progressive pulmonary disease, chronic inflammation, and a pro-oxidative environment. The intricate relationship between CFTR dysfunction, oxidative stress, and inflammation underscores the need to accurately characterize oxidative stress markers to identify therapeutic targets. This review compiles and analyzes methodologies employed in the CF field for this purpose, presenting selected applications and outcomes while highlighting potential inconsistencies due to experimental variations. The review encompasses a wide array of analytical techniques. These include methods for direct reactive oxygen species (ROS) detection (e.g., superoxide, hydrogen peroxide), characterization of oxidative damage to lipids (e.g., TBARS, F2-isoprostanes; lipidomics), proteins (e.g., carbonylation, S-nitrosylation, S-glutathionylation; proteomics), and DNA (e.g., 8-OHdG). Assays for major non-enzymatic antioxidants (glutathione, vitamins), enzymatic antioxidant systems (superoxide dismutase, catalase, glutathione peroxidase), and total antioxidant capacity (TAC) are detailed. Furthermore, methods to assess mitochondrial function for studying oxidative stress in CF are discussed. The critical choice of experimental models (in vitro, in vivo) and biological samples (e.g., blood, sputum, BALF, EBC, cells), along with their specific considerations, are also integral to the review. Application of these diverse methodologies frequently reveals heightened oxidative stress and perturbed antioxidant defenses across various CF-relevant compartments, although results can be influenced by the specific model or technique utilized. Ultimately, this comprehensive analysis underscores the complexity of assessing oxidative stress in CF and strongly advocates for the implementation of integrated, multiparametric strategies. Such synergistic approaches, combining complementary methodologies, are crucial for a holistic understanding of redox dysregulation, facilitating the identification of reliable biomarkers, and guiding the development of more effective, targeted antioxidant therapies to improve clinical outcomes in CF.

Cystic fibrosis (CF), is a genetic disorder caused by dysfunctional Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein, characterized by progressive pulmonary decline and elevated oxidative stress and inflammation. CFTR modulators, including potentiators such as ivacaftor, represent the cornerstone of current therapeutic strategies. We present compelling evidence that ivacaftor, in contrast to other CFTR modulators, exhibits a CFTR-independent ability to mitigate oxidative injury by inhibiting lipid peroxidation, a cascade of oxidative damage, and by blocking ferroptosis, a specific form of cell death driven by unrestrained lipid oxidation. This protective mechanism is attributed to ivacaftor's direct action as a scavenger of lipid radicals, effectively interrupting the initiation and propagation of lipid peroxidation as well as decreasing its toxic products. Moreover, we demonstrate that ivacaftor acts as a regulator of cellular innate antioxidant defense pathways, restoring physiological levels of Nrf2 and GPx4, and upregulating the expression of FSP1. These findings reveal a previously unexplored aspect of ivacaftor's pharmacological profile, suggesting potential therapeutic applications extending beyond the realm of CF, particularly in disease contexts characterized by elevated oxidative stress and ferroptotic cell death.

Cystic fibrosis (CF), a severe genetic disorder stemming from mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene, is characterized by a complex interplay of chronic inflammation and heightened oxidative stress, resulting in substantial patient morbidity. The diverse array of CFTR mutations, categorized into seven distinct classes based on their functional impact on the CFTR protein, presents a significant obstacle to effective therapeutic intervention. While CFTR modulator therapies offer clinical benefits, their applicability is restricted to specific mutation classes, leaving a considerable portion of the CF patient population with unmet therapeutic needs. This review provides a critical analysis of the intricate role of oxidative stress in CF, meticulously examining its origins, mechanistic pathways and downstream pathological consequences, with particular emphasis on lipid peroxidation (LPO). It elucidates the nuanced connection between LPO and inflammatory processes driven by cellular stressors such as endoplasmic reticulum dysfunction, mitochondrial impairment and persistent bacterial infections. Furthermore, it evaluates the current landscape of therapeutic proposals targeting oxidative stress, including antioxidant interventions, and explores the potential of microRNAs (miRNAs) as novel targets. This review aims to synthesize existing research to provide a comprehensive understanding of oxidative stress involvement in CF pathogenesis while critically appraising the advantages and limitations of current antioxidant therapeutic strategies.

Ferroptosis is a novel iron-sensitive subtype of regulated cell death (RCD), persisting under extreme lipid peroxidation and iron/redox imbalances. Unlike apoptosis, necroptosis, and pyroptosis, ferroptosis is a signaling-driven process mediated through iron metabolism imbalance, polyunsaturated fatty acid (PUFA) exceeding oxidation, and defects in its protective systems like Xc-/GSH/GPx4. Specifically, this review establishes that iron-driven ferroptosis is a central underlying pathomechanistic factor in a broad range of human diseases. Significantly, whether its modulation is therapeutic, it is entirely conditional on the specific disease context. Thus, its induction can provide a promising antidote for destructive cancer cells when conjoined with immuno-therapies to boost anticancer immunity. Conversely, iron-mediated ferroptosis suppression is a key factor in countering destructive changes in a whole range of degenerative and acute injuries. Current therapeutic approaches include iron chelators, lipid oxidation inhibitors, GPx4 activators, natural and active compounds, and novel drug delivery systems. However, against all odds and despite its intense therapeutic promise, its translation into a practical medicinal strategy faces many difficulties. Thus, a therapeutic agent specifically focused on its modulation is still lacking. The availability of selective biologic markers is a concern. The challenges in the direct pathologic identification of ferroptosis in a complex in vivo systemic scenario remain. Current avenues for its future development are pathogen infections, the discovery of novel regulating factors, and novel approaches to personalized medicine centered on its organ-level in vivo signatures.

The Ebola virus (EBOV) and the Rabies virus (RABV) are deadly infectious agents impacting human and animal health. Current prevention and control strategies mainly rely on vaccines and antibodies, highlighting the urgent need for effective, low-cost antivirals suitable for therapeutic options. Plant-derived bioactive compounds offer a promising natural source for such candidate antivirals. As a contribution to this antiviral approach, we have characterized the anti-EBOV and anti-RABV activity of a Cranberry extract (CE) endowed with a very high content of bioactive A2-type proanthocyanidin (PAC-A2). The CE inhibited the in vitro infection of both pseudoviruses expressing EBOV-GP or RABV-G glycoproteins and authentic EBOV and RABV. Attachment and entry assays revealed that the extract targets early phases of infection preventing attachment and entry. Noteworthy, synthetic PAC-A2 reproduced the antiviral activity observed with the whole CE. Mechanistic studies then revealed that the CE interacted directly with the ectodomain of EBOV-GP or the RABV-G, suggesting interference with their functions. In support to this hypothesis, fluorescence spectroscopy analysis showed a reduction in intrinsic fluorescence of both EBOV-GP and RABV-G after incubation with synthetic PAC-A2, thus confirming a direct interaction of the viral glycoproteins with PAC-A2. In silico docking simulations further sustained in vitro results by predicting the binding of PAC-A2 into the binding pocket of EBOV-GP and to the trimeric architecture of RABV-G. Together, these results suggest this cranberry extract and bioactive PAC-A2 as potential candidates to be further develop as novel antiviral agents for the prevention of EBOV and RABV infections.

The industry transfer of laboratory-use magnetic separation is still hampered by the lack of suitable nanoparticles, both in terms of their features and large-scale availability. Surface Active Maghemite Nanoparticles (SAMNs) characterized by a unique surface chemistry, low environmental impact, scalable synthesis and functionalization were used to develop a bio-inspired lactoferrin (LF) recognition system. Based on the LF affinity for DNA, a self-assembly process was optimized for obtaining a SAMN@DNA hybrid displaying chemical and colloidal stability and LF specificity. SAMN@DNA was successfully tested for the affinity purification of LF from crude bovine whey. Advantages, such as high selectivity and loading capacity, nanoparticle re-usability, outstanding purity (96 +/- 1%), preservation of protein conformation and short operational time, were highlighted. Finally, scalability was demonstrated by an automatic system performing continuous purification of LF from 100 liters day-1 of whey. This study responds to essential prerequisites, such as efficiency, re-usability and industrialization feasibility.

Human cytomegalovirus DNA polymerase processivity factor UL44 is transported into the nucleus by importin (IMP) α/β through a classical nuclear localization signal (NLS), and this region is susceptible to cdc2‐mediated phosphorylation at position T427. Whilst phosphorylation within and close to the UL44 NLS regulates nuclear transport, the details remain elusive, due to the paucity of structural information regarding the role of negatively charged cargo phosphate groups. We addressed this issue by studying the effect of UL44 T427 phosphorylation on interaction with several IMPα isoforms by biochemical and structural approaches. Phosphorylation decreased UL44/IMPα affinity 10‐fold, and a comparative structural analysis of UL44 NLS phosphorylated and non‐phosphorylated peptides complexed with mouse IMPα2 revealed the structural rearrangements responsible for phosphorylation‐dependent inhibition of UL44 nuclear import.

Oxidative stress and neuroinflammation play a pivotal role in triggering the neurodegenerative pathological cascades which characterize neurodegenerative disorders, such as Alzheimer’s and Parkinson’s diseases. In search for potential efficient treatments for these pathologies, that are still considered unmet medical needs, we started from the promising properties of the antidiabetic drug pioglitazone, which has been repositioned as an MAO-B inhibitor, characterized by promising neuroprotective properties. Herein, with the aim to broaden its neuroprotective profile, we tried to enrich pioglitazone with direct and indirect antioxidant properties by hanging polyphenolic and electrophilic features that are able to trigger Nrf2 pathway and the resulting cytoprotective genes’ transcription, as well as serve as radical scavengers. After a preliminary screening on MAO-B inhibitory properties, caffeic acid derivative 2 emerged as the best inhibitor for potency and selectivity over MAO-A, characterized by a reversible mechanism of inhibition. Furthermore, the same compound proved to activate Nrf2 pathway by potently increasing Nrf2 nuclear translocation and strongly reducing ROS content, both in physiological and stressed conditions. Although further biological investigations are required to fully clarify its neuroprotective properties, we were able to endow the pioglitazone scaffold with potent antioxidant properties, representing the starting point for potential future pioglitazone-based therapeutics for neurodegenerative disorders.

Monoamine oxidases (MAOs) are well-known pharmacological targets in neurological and neurodegenerative diseases. However, recent studies have revealed a new role for MAOs in certain types of cancer such as glioblastoma and prostate cancer, in which they have been found overexpressed. This finding is opening new frontiers for MAO inhibitors as potential antiproliferative agents. In light of our previous studies demonstrating how a polyamine scaffold can act as MAO inhibitor, our aim was to search for novel analogs with greater inhibitory potency for human MAOs and possibly with antiproliferative activity. A small in-house library of polyamine analogs (2–7) was selected to investigate the effect of constrained linkers between the inner amine functions of a polyamine backbone on the inhibitory potency. Compounds 4 and 5, characterized by a dianiline (4) or dianilide (5) moiety, emerged as the most potent, reversible, and mainly competitive MAO inhibitors (Ki < 1 μM). Additionally, they exhibited a high antiproliferative activity in the LN-229 human glioblastoma cell line (GI50 < 1 μM). The scaffold of compound 5 could represent a potential starting point for future development of anticancer agents endowed with MAO inhibitory activity.

Among multiple cytoprotective mechanisms, eukaryotic cells exhibit a complex transcriptional program relying on the Nrf2 transcription factor, which is generally recruited upon biological stressors including oxidative-stress-based cellular insults. The relevance of this master regulator has remarkably emerged in recent years in several research fields such as cancer, inflammatory disorders and age-related neurological diseases. Here, we document the generation and characterization of a novel Nrf2/ARE pathway biosensor fish which exhibits a dynamic spatiotemporal expression profile during the early developmental stages. The transgenic line is responsive to known Nrf2 pathway modulators but also to Edaravone, which direct activity on the Nrf2 pathway has never been documented in a live transgenic fish model. We also show that the reporter is faithfully activated during fin regeneration, and its degree of expression is slightly affected in a glucocerebrosidase (Gba1) morphant zebrafish model. Therefore, this novel transgenic fish may represent a valuable tool to be exploited for the characterization of zebrafish models of human diseases, as well as for primary high-throughput drug screening.

The aim of this study was to examine, in biochemical detail, the functional role of the Arg152 residue in the selenoprotein Glutathione Peroxidase 4 (GPX4), whose mutation to His is involved in Sedaghatian-type Spondylometaphyseal Dysplasia (SSMD). Wild-type and mutated recombinant enzymes with selenopcysteine (Sec) at the active site, were purified and structurally characterized to investigate the impact of the R152H mutation on enzymatic function. The mutation did not affect the peroxidase reaction's catalytic mechanism, and the kinetic parameters were qualitatively similar between the wild-type enzyme and the mutant when mixed micelles and monolamellar liposomes containing phosphatidylcholine and its hydroperoxide derivatives were used as substrate. However, in monolamellar liposomes also containing cardiolipin, which binds to a cationic area near the active site of GPX4, including residue R152, the wild-type enzyme showed a non-canonical dependency of the reaction rate on the concentration of both enzyme and membrane cardiolipin. To explain this oddity, a minimal model was developed encompassing the kinetics of both the enzyme interaction with the membrane and the catalytic peroxidase reaction. Computational fitting of experimental activity recordings showed that the wild-type enzyme was surface-sensing and prone to "positive feedback" in the presence of cardiolipin, indicating a positive cooperativity. This feature was minimal, if any, in the mutant. These findings suggest that GPX4 physiology in cardiolipin containing mitochondria is unique, and emerges as a likely target of the pathological dysfunction in SSMD.

The purification of a protein inhibiting lipid peroxidation led to the discovery of the selenoperoxidase GPx4 forty years ago. Thus, the evidence of the enzymatic activity was reached after identifying the biological effect and unambiguously defined the relationship between the biological function and the enzymatic activity. In the syllogism where GPx4 inhibits lipid peroxidation and its inhibition is lethal, cell death is operated by lipid peroxidation. Based on this rationale, this form of cell death emerged as regulated iron-enforced oxygen toxicity and was named ferroptosis in 2012. In the last decades, we learned that reduction of lipid hydroperoxides is indispensable and, in cooperation with prooxidant systems, controls the critical steady state of lipid peroxidation. This concept defined the GPx4 reaction as both the target for possible anti-cancer therapy and if insufficient, as cause of degenerative diseases. We know the reaction mechanism, but the details of the interaction at the membrane cytosol interface are still poorly defined. We know the gene structure, but the knowledge about expression control is still limited. The same holds true for post-transcriptional modifications. Reverse genetics indicate that GPx4 has a role in inflammation, immunity, and differentiation, but the observations emerging from these studies need a more specifically addressed biochemical evidence. Finally, the role of GPx4 in spermatogenesis disclosed an area unconnected to lipid peroxidation. In its mitochondrial and nuclear form, the peroxidase catalyzes the oxidation of protein thiols in two specific aspects of sperm maturation: stabilization of the mid-piece and chromatin compaction. Thus, although available evidence converges to the notion that GPx4 activity is vital due to the inhibition of lipid peroxidation, it is reasonable to foresee other unknown aspects of the GPx4 reaction to be disclosed.

EDITORIAL article Front. Mol. Biosci., 02 December 2022Sec. Molecular Diagnostics and Therapeutics Volume 9 - 2022 | https://doi.org/10.3389/fmolb.2022.1094922

Ferroptosis is a non-accidental, regulated form of cell death operated by lipid peroxidation under strict control of GPx4 activity. This is consistent with the notion that lipid peroxidation is initiated by radicals produced from decomposition of traces of pre-existing lipid hydroperoxides. The question, therefore, emerges about the formation of these traces of lipid hydroperoxides interacting with Fe2+. In the most realistic option, they are produced by oxygen activated species generated during aerobic metabolism. Screening for metabolic sources of superoxide supporting ferroptosis induced by GSH depletion, we failed to detect, in our cell model, a role of respiratory chain. We observed instead that the pyruvate dehydrogenase complex -as other α keto acid dehydrogenases already known as a major source of superoxide in mitochondria- supports ferroptosis. The opposite effect on ferroptosis by silencing either the E1 or the E3 subunit of the pyruvate dehydrogenase complex pointed out the autoxidation of dihydrolipoamide as the source of superoxide. We finally observed that GSH depletion activates superoxide production, seemingly through the inhibition of the specific kinase that inhibits pyruvate dehydrogenase. In summary, this set of data is compatible with a scenario where the more electrophilic status produced by GSH depletion not only activates ferroptosis by preventing GPx4 activity, but also favors the formation of lipid hydroperoxides. In an attractive perspective of tissue homeostasis, it is the activation of energetic metabolism associated to a decreased nucleophilic tone that, besides supporting energy demanding proliferation, also sensitizes cells to a regulated form of death.

Protein kinase CK2 is largely involved in cell proliferation and apoptosis and is generally recognized as an Achilles’ heel of cancer, being overexpressed in several malignancies. The beneficial effects of (−)-epigallocatechin-3-gallate (EGCG) in the prevention and treatment of several diseases, including cancer, have been widely reported. However, poor stability and limited bioavailability hinder the development of EGCG as an effective therapeutic agent. The combination of innovative nanomaterials and bioactive compounds into nanoparticle-based systems demonstrates the synergistic advantages of nanocomplexes as compared to the individual components. In the present study, we developed a self-assembled core-shell nanohybrid (SAMN@EGCG) combining EGCG and intrinsic dual-signal iron oxide nanoparticles (Surface Active Maghemite Nanoparticles). Interestingly, nano-immobilization on SAMNs protects EGCG from degradation, preventing its auto-oxidation. Most importantly, the nanohybrid was able to successfully deliver EGCG into cancer cells, displaying impressive protein kinase CK2 inhibition comparable to that obtained with the most specific CK2 inhibitor, CX-4945 (5.5 vs. 3 µM), thus promoting the phytochemical exploitation as a valuable alternative for cancer therapy. Finally, to assess the advantages offered by nano-immobilization, we tested SAMN@EGCG against Pseudomonas aeruginosa, a Gram-negative bacterium involved in severe lung infections. An improved antimicrobial effect with a drastic drop of MIC from 500 to 32.7 μM was shown.

Selenoproteins are translated via animal domain-specific elongation machineries that redefine dedicated UGA opal codons from termination of translation to selenocysteine (Sec) insertion, utilizing specific tRNA species and Sec-specific elongation factors. This has made recombinant production of mammalian selenoproteins in E. coli technically challenging but recently we developed a methodology that enables such production, using recoding of UAG for Sec in an RF1-deficient host strain. Here we used that approach for production of the human glutathione peroxidases 1, 2 and 4 (GPX1, GPX2 and GPX4), with all these three enzymes being important antioxidant selenoproteins. Among these, GPX4 is the sole embryonically essential enzyme, and is also known to be essential for spermatogenesis as well as protection from cell death through ferroptosis. Enzyme kinetics, ICP-MS and mass spectrometry analyses of the purified recombinant proteins were used to characterize selenoprotein characteristics and their Sec contents. This revealed a unique phenomenon of one-codon skipping, resulting in a lack of a single amino acid at the position corresponding to the selenocysteine (Sec) residue, in about 30% of the recombinant GPX isoenzyme products. We furthermore confirmed the previously described UAG suppression with Lys or Gln as well as a minor suppression with Tyr, together resulting in about 20% Sec contents in the full-length proteins. No additional frameshifts or translational errors were detected. We subsequently found that Sec-containing GPX4 could be further purified over a bromosulfophthalein-column, yielding purified recombinant GPX4 with close to complete Sec contents. This production method for homogenously purified GPX4 should help to further advance the studies of this important selenoprotein.

It has been previously demonstrated that synthetic antibody-derived peptides could exert a significant activity in vitro, ex vivo, and/or in vivo against microorganisms and viruses, as well as immunomodulatory effects through the activation of immune cells. Based on the sequence of previously described antibody-derived peptides with recognized antifungal activity, an in silico analysis was conducted to identify novel antifungal candidates. The present study analyzed the candidacidal and structural properties of in silico designed peptides (ISDPs) derived by amino acid substitutions of the parent peptide KKVTMTCSAS. ISDPs proved to be more active in vitro than the parent peptide and all proved to be therapeutic in Galleria mellonella candidal infection, without showing toxic effects on mammalian cells. ISDPs were studied by circular dichroism spectroscopy, demonstrating different structural organization. These results allowed to validate a consensus sequence for the parent peptide KKVTMTCSAS that may be useful in the development of novel antimicrobial molecules.