Intracellular delivery of biologically-active fungal metabolite gliotoxin using magnetic nanoparticles

Gliotoxin (GT), a secondary metabolite produced by Aspergillus molds, has been proposed as a potential anti-tumor agent. Here we have developed a nanoparticle approach to enhance delivery of GT in tumor cells and establish a basis for its potential use as therapeutical drug. GT bound to magnetic nanoparticles (MNPs) retained a high anti-tumor activity, correlating with efficient intracellular delivery, which was increased in the presence of glucose. Our results show that the attachment of GT to MNPs by covalent bonding enhances intracellular GT delivery without affecting its biological activity. This finding represents the first step to use this potent anti-tumor agent in the treatment of cancer

The mitochondrial protein Bak is pivotal for gliotoxin-induced apoptosis and a critical host factor of Aspergillus fumigatus virulence in mice

Aspergillus fumigatus infections cause high levels of morbidity and mortality in immunocompromised patients. Gliotoxin (GT), a secondary metabolite, is cytotoxic for mammalian cells, but the molecular basis and biological relevance of this toxicity remain speculative. We show that GT induces apoptotic cell death by activating the proapoptotic Bcl-2 family member Bak, but not Bax, to elicit the generation of reactive oxygen species, the mitochondrial release of apoptogenic factors, and caspase-3 activation. Activation of Bak by GT is direct, as GT triggers in vitro a dose-dependent release of cytochrome c from purified mitochondria isolated from wild-type and Bax- but not Bak-deficient cells. Resistance to A. fumigatus of mice lacking Bak compared to wild-type mice demonstrates the in vivo relevance of this GT-induced apoptotic pathway involving Bak and suggests a correlation between GT production and virulence. The elucidation of the molecular basis opens new strategies for the development of therapeutic regimens to combat A. fumigatus and related fungal infections

Role of laeA in the regulation of alb1, gliP , Conidial Morphology and Virulence in Aspergillus fumigatus

The alb1 (pksP) gene has been reported as a virulence factor controlling the pigmentation and morphology of conidia in Aspergillus fumigatus. A recent report suggested that laeA regulates alb1 expression and conidial morphology but not pigmentation in the A. fumigatus strain AF293. laeA has also been reported to regulate the synthesis of secondary metabolites, such as gliotoxin. We compared the role of laeA in the regulation of conidial morphology and the expression of alb1 and gliP in strains B-5233 and AF293, which differ in colony morphology and nutritional requirements. Deletion of laeA did not affect conidial morphology or pigmentation in these strains, suggesting that laeA is not involved in alb1 regulation during conidial morphogenesis. Deletion of laeA, however, caused down-regulation of alb1 during mycelial growth in a liquid medium. Transcription of gliP, involved in the synthesis of gliotoxin, was drastically reduced in B-5233laeAΔ, and the gliotoxin level found in the culture filtrates was 20% of wild-type concentrations. While up-regulation of gliP in AF293 was comparable to that in B-5233, the relative mRNA level in AF293laeAΔ was about fourfold lower than that in B-5233laeAΔ. Strain B-5233lae4Δ caused slower onset of fatal infection in mice relative to that with B-5233. Histopathology of sections from lungs of infected mice corroborated the survival data. Culture filtrates from B-5233laeAΔ caused reduced death in thymoma cells and were less inhibitory to a respiratory burst of neutrophils than culture filtrates from B-5233. Our results suggest that while laeA is not involved in the regulation of alb1 function in conidial morphology, it regulates the synthesis of gliotoxin and the virulence of A. fumigatus

All about (nk cell-mediated) death in two acts and an unexpected encore: initiation, execution and activation of adaptive immunity

NK cells are key mediators of immune cell-mediated cytotoxicity toward infected and transformed cells, being one of the main executors of cell death in the immune system. NK cells recognize target cells through an array of inhibitory and activating receptors for endogenous or exogenous pathogen-derived ligands, which together with adhesion molecules form a structure known as immunological synapse that regulates NK cell effector functions. The main and best characterized mechanisms involved in NK cell-mediated cytotoxicity are the granule exocytosis pathway (perforin/granzymes) and the expression of death ligands. These pathways are recognized as activators of different cell death programmes on the target cells leading to their destruction. However, most studies analyzing these pathways have used pure recombinant or native proteins instead of intact NK cells and, thus, extrapolation of the results to NK cell-mediated cell death might be difficult. Specially, since the activation of granule exocytosis and/or death ligands during NK cell-mediated elimination of target cells might be influenced by the stimulus received from target cells and other microenvironment components, which might affect the cell death pathways activated on target cells. Here we will review and discuss the available experimental evidence on how NK cells kill target cells, with a special focus on the different cell death modalities that have been found to be activated during NK cell-mediated cytotoxicity; including apoptosis and more inflammatory pathways like necroptosis and pyroptosis. In light of this new evidence, we will develop the new concept of cell death induced by NK cells as a new regulatory mechanism linking innate immune response with the activation of tumour adaptive T cell responses, which might be the initiating stimulus that trigger the cancer-immunity cycle. The use of the different cell death pathways and the modulation of the tumour cell molecular machinery regulating them might affect not only tumour cell elimination by NK cells but, in addition, the generation of T cell responses against the tumour that would contribute to efficient tumour elimination and generate cancer immune memory preventing potential recurrences

Fluorogenic Granzyme A Substrates Enable Real‐Time Imaging of Adaptive Immune Cell Activity

6 figures.Cytotoxic immune cells, including T lymphocytes (CTLs) and natural killer (NK) cells, are essential components of the host response against tumors. CTLs and NK cells secrete granzyme A (GzmA) upon recognition of cancer cells; however, there are very few tools that can detect physiological levels of active GzmA with high spatiotemporal resolution. Herein, we report the rational design of the near-infrared fluorogenic substrates for human GzmA and mouse GzmA. These activity-based probes display very high catalytic efficiency and selectivity over other granzymes, as shown in tissue lysates from wild-type and GzmA knock-out mice. Furthermore, we demonstrate that the probes can image how adaptive immune cells respond to antigen-driven recognition of cancer cells in real time.A. S. acknowledges a PhD fellowship from the Aragon Government. M. A. A. acknowledges funds from the Ministry of Economy and Competitiveness, Spain (IJC2019- 039192-I). This research was supported by CIBER (CB 2021), Instituto de Salud Carlos III, Ministerio de Ciencia e Innovación and Unión Europea-NextGenerationEU, FEDER (Group B29_20R), Ministry of Science, Innovation and Universities and Agencia Estatal de Investigación, Spain (SAF2017-83120-C2-1-R and PID2020-113963RB-I00). T. K. acknowledges funding from an MRC Career Development Award (MR/S006982/1) and an MRC Centre Grant (MR/N022556/1). E. W. R. acknowledges a Cancer Research UK grant (A_BICR_1920_Roberts). M. V. acknowledges funds from an ERC Consolidator Grant (DYNAFLUORS, 771443) and an ERC PoC Grant (IBDIMAGE, 957535). This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement (859908).Peer reviewe

National identity predicts public health support during a global pandemic

Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = −0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics.publishedVersio

Predicting attitudinal and behavioral responses to COVID-19 pandemic using machine learning

At the beginning of 2020, COVID-19 became a global problem. Despite all the efforts to emphasize the relevance of preventive measures, not everyone adhered to them. Thus, learning more about the characteristics determining attitudinal and behavioral responses to the pandemic is crucial to improving future interventions. In this study, we applied machine learning on the multinational data collected by the International Collaboration on the Social and Moral Psychology of COVID-19 (N = 51,404) to test the predictive efficacy of constructs from social, moral, cognitive, and personality psychology, as well as socio-demographic factors, in the attitudinal and behavioral responses to the pandemic. The results point to several valuable insights. Internalized moral identity provided the most consistent predictive contribution—individuals perceiving moral traits as central to their self-concept reported higher adherence to preventive measures. Similar results were found for morality as cooperation, symbolized moral identity, self-control, open-mindedness, and collective narcissism, while the inverse relationship was evident for the endorsement of conspiracy theories. However, we also found a non-neglible variability in the explained variance and predictive contributions with respect to macro-level factors such as the pandemic stage or cultural region. Overall, the results underscore the importance of morality-related and contextual factors in understanding adherence to public health recommendations during the pandemic.Peer reviewe

National identity predicts public health support during a global pandemic (vol 13, 517, 2022) : National identity predicts public health support during a global pandemic (Nature Communications, (2022), 13, 1, (517), 10.1038/s41467-021-27668-9)

Publisher Copyright: © The Author(s) 2022.In this article the author name ‘Agustin Ibanez’ was incorrectly written as ‘Augustin Ibanez’. The original article has been corrected.Peer reviewe

National identity predicts public health support during a global pandemic.

Changing collective behaviour and supporting non-pharmaceutical interventions is an important component in mitigating virus transmission during a pandemic. In a large international collaboration (Study 1, N = 49,968 across 67 countries), we investigated self-reported factors associated with public health behaviours (e.g., spatial distancing and stricter hygiene) and endorsed public policy interventions (e.g., closing bars and restaurants) during the early stage of the COVID-19 pandemic (April-May 2020). Respondents who reported identifying more strongly with their nation consistently reported greater engagement in public health behaviours and support for public health policies. Results were similar for representative and non-representative national samples. Study 2 (N = 42 countries) conceptually replicated the central finding using aggregate indices of national identity (obtained using the World Values Survey) and a measure of actual behaviour change during the pandemic (obtained from Google mobility reports). Higher levels of national identification prior to the pandemic predicted lower mobility during the early stage of the pandemic (r = -0.40). We discuss the potential implications of links between national identity, leadership, and public health for managing COVID-19 and future pandemics