The liver, and more specifically, the liver sinusoidal endothelial cells, constitute the beginning of one of the most important responses for the elimination of hematogenously disseminated Candida albicans. Therefore, we aimed to study the mechanisms involved in the interaction between these cells and C. albicans. Transcriptomics-based analysis showed an increase in the expression of genes related to the immune response (including receptors, cytokines, and adhesion molecules), as well as to aerobic glycolysis. Further in vitro analyses showed that IL-6 production in response to C. albicans is controlled by MyD88- and SYK-pathways, suggesting an involvement of Toll-like and C-type lectin receptors and the subsequent activation of the MAP-kinases and c-Fos/AP-1 transcription factor. In addition, liver sinusoidal endothelial cells undergo metabolic reprogramming towards aerobic glycolysis induced by C. albicans, as confirmed by the increased Extracellular Acidification Rate and the overexpression of enolase (Eno2), hexonikase (Hk2) and glucose transporter 1 (Slc2a1). In conclusion, these results indicate that the hepatic endothelium responds to C. albicans by increasing aerobic glycolysis and promoting an inflammatory environment. (c) 2024 The Authors. Published by Elsevier Masson SAS on behalf of Institut Pasteur. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Recent studies have increasingly focused on the role of fungi, including Candida albicans , in carcinogenesis. Since C. albicans is a component of the human microbiota, particularly on the skin, we investigated its effect on the phenotype and signalling pathways of melanoma cells. Assays for migration, adhesion, angiogenesis, and hepatic metastasis showed that C. albicans promotes a more malignant phenotype in melanoma cells. At the transcriptomic level, C. albicans increased the expression of VEGF ( Vegfa ), and genes associated with MAPK and HIF-1 signalling pathways, and with aerobic glycolysis. Further in vitro analysis revealed that TLRs and EphA2 receptors are involved in the recognition of live C. albicans , stimulating VEGF secretion and expression of the AP-1 transcription factor component c-Fos through p38-MAPK and HIF-1α. These pathways also regulate the expression of other AP-1 constituents such as Atf3 , Jun , and Jund . Moreover, p38-MAPK regulates glycolytic genes like Hk2 , Slc2a1 , and Eno2 . In conclusion, C. albicans activates the p38-MAPK/c-Fos/AP-1 and HIF-1/HIF-1α/c-Fos/AP-1 pathways in melanoma cells, promoting a pro-angiogenic environment and metabolic reprogramming. Therefore, this study clarifies the impact of C. albicans on melanoma cells, which can lead to the use of antifungal therapies as complementary to traditional treatments for melanoma.

The difficulty of accurately identifying Candida auris and the high resistance rates presented have increased the concern in the healthcare setting. Due to this, the aim of this study was to analyse the fungal response to oxidative stress. To achieve this goal, gene and protein expression were examined using qPCR and two-dimensional electrophoresis, respectively, peroxiredoxin Tsa1b being discovered to be overexpressed under oxidative stress. Besides, its antigenicity was also confirmed by western blotting. Subsequently, the significance of Tsa1b was next investigated by creating and characterizing the C. auris ΔTSA1B and C. auris ΔTSA1B::TSA1B strains using CRISPR-Cas9. The findings demonstrated that the ΔTSA1B strain was more susceptible to oxidative and cell wall stressors than the wild-type strain, which was consistent with an increase in the cell wall β-glucan amounts when grown in the presence of oxidative stress. Furthermore, the ΔTSA1B strain was also more vulnerable to the presence of dendritic cells and bone marrow-derived macrophages. Finally, in vivo infections performed in Galleria mellonella and mice showed a slower progression of the disease in those animals infected with the mutant strain. In conclusion, the peroxiredoxin Tsa1b has been identified as an important protein for the C. auris response to oxidative stress and as a virulence factor, allowing for a more thorough knowledge of the pathobiology of this yeast. This study points out the potential that this protein may have for the development of new diagnostic and therapeutic approaches. HIGHLIGHTS: Several metabolic proteins are implicated in C. auris response to oxidative stress C. auris response to oxidative stress is influenced by the Tsa1b peroxiredoxin Lack of Tsa1b generates more susceptibility to stresses and an altered cell wall C. auris Tsa1b is involved in the fungal interaction with host immune cells The Tsa1b of C. auris contributes to the progression of the infection in vivo

Candidozyma auris (Candida auris) is an emerging pathogenic yeast of global concern due to its persistence on abiotic and biotic surfaces and the difficulty of treating the severe infections it causes, which are frequently associated with high mortality rates because of its extensive antifungal resistance. Thus, new therapeutic strategies are urgently needed to complement or replace current antifungal drugs. In this study, we evaluated the efficacy of Ca37, a monoclonal antibody (mAb) targeting the alcohol dehydrogenase (Adh) protein of Candida albicans, against C. auris both in vitro and in vivo. Protein electrophoresis and Western Blot analyses demonstrated immunoreactivity of Ca37 mAb with C. auris total protein and cell wall-associated protein extracts, among which Adh was identified. In vitro, incubation with Ca37 mAb significantly reduced the growth of several C. auris strains and enhanced the phagocytic activity of RAW 264.7 murine macrophages. In vivo, Ca37 mAb treatment increased the survival of Galleria mellonella larvae. In a murine model of systemic infection, treated mice displayed improved clinical condition, along with a greater number and larger area of immune-associated foci in the kidneys, suggesting enhanced fungal recognition. These findings support the potential of Ca37 mAb as an antifungal immunotherapy, although further studies in murine models are necessary to establish optimal dosing, efficacy, and mechanisms of action.

The rise of antimicrobial resistance is reducing the effectiveness of current therapies and highlights the need for new antimicrobial agents. Marine environments, rich in microorganisms adapted to extreme conditions, represent a promising reservoir of bioactive compounds. The marine bacterium Marinomonas mediterranea secretes, among others, lysine oxidase (LodA) and glycine oxidase (GoxA), enzymes that generate hydrogen peroxide and exhibit antibacterial activity. Based on this mechanism, we hypothesized that modifying specific experimental con-ditions could enhance the antimicrobial potential of the secreted enzymes and additional com-pounds, broadening their activity spectrum. In this study, culture conditions were optimized to promote the production of inhibitory molecules, and the antimicrobial activity of the M. medi-terranea secretome was assessed against clinically relevant microorganisms. The concentrated secretome obtained from growth in Marine Broth exhibited antimicrobial activity against the Gram-negative and Gram-positive bacteria analyzed and several pathogenic fungi, an effect at-tributable to some proteins present in it. Among them, LodA and GoxA, previously associated with bacterial growth inhibition, also appear to contribute to antifungal activity. Moreover, valyl-tRNA synthetase emerged as a potential new antimicrobial factor. These findings high-light the biotechnological potential of marine microorganisms and support further exploration of their secretomes for the development of new antimicrobial agents.