Aspergillus fumigatus Extracellular Vesicles Display Increased Galleria mellonella Survival but Partial Pro-Inflammatory Response by Macrophages

MiR-146/TNF-α/IL-6/osteocalcin crosstalk in anti-rheumatic potential of Galleria mellonella hemolymph from computational molecular modeling to in-vivo validation

Rheumatoid arthritis (RA) is an inflammatory autoimmune illness that persistently and recurrently affects joints. In RA, miR-146a functions as a key regulator, modulating inflammation by targeting and downregulating cytokines that promote inflammation, such as TNF-α and IL-6, whereas osteocalcin, a bone metabolism marker, plays a role in bone remodeling and joint health. The interplay between these molecules significantly influences RA progression and severity by balancing inflammation and bone integrity. Conventional antirheumatic drugs often cause varying levels of side effects. As sustainable development initiatives grow, insects are gaining interest as sustainable food sources and potential medicinal agents. Notably, the increasing Galleria mellonella (G. mellonella) population has raised concerns about the spread of honeybee viruses, affects bee products and food security, and drives economic losses in the therapeutic market. Accordingly, hemolymph has crucial defensive and immunological effects in insects and has recently been investigated as an immunomodulatory agent in parasitic in-vitro and in-vivo rat models. This work was designed to elucidate the potential immunomodulatory impact of G. mellonella hemolymph on the crosstalk between miR-146a, IL-6, TNF-α, and osteocalcin in the context of RA, utilizing both computational molecular modeling and in-vivo validation. Computer-aided molecular simulation for immune and RA mediators is applied through specific cell annotation, targeted pathways, and in-silico protein‒protein and gene‒gene interactions with a gene relative-tissue expression heatmap, which is based on gas chromatographic‒mass spectrometric analysis of hemolymph. Our study is the first to adapt a preliminary test to optimize hemolymph dosing and toxicity. The rats were subsequently divided into four groups: healthy control, Freund's adjuvant-induced arthritis (utilized as a model that mimics human RA), methotrexate-treated arthritis, and hemolymph-treated arthritis groups. Our findings indicate that hemolymph contains valuable active compounds that have anti-inflammatory and antioxidant potential, increasing the impact of recovery on diseased joints in comparison with the arthritic and methotrexate groups. This is the first report investigating the maximum inhibition rate of G. mellonella hemolymph as an immunomodulatory and anti-inflammatory agent in an arthritic model.

Characterizing extracellular vesicles of human fungal pathogens

Since their discovery in 2007, there has been growing awareness of the importance of fungal extracellular vesicles (EVs) for fungal physiology, host-pathogen interactions and virulence. Fungal EVs are nanostructures comprising bilayered membranes and molecules of various types that participate in several pathophysiological processes in fungal biology, including secretion, cellular communication, immunopathogenesis and drug resistance. However, many questions remain regarding the classification of EVs, their cellular origin, passage across the cell wall, experimental models for functional and compositional analyses, production in vitro and in vivo and biomarkers for EVs. Here, we discuss gaps in the literature of fungal EVs and identify key questions for the field. We present the history of fungal EV discovery, discuss five major unanswered questions in fungal EV biology and provide future perspectives for fungal EV research. We primarily focus our discussion on human fungal pathogens, but also extend it to include knowledge of other fungi, such as plant pathogens. With this Perspective we hope to stimulate new approaches and expand studies to understand the biology of fungal EVs.

Extracellular vesicles from diverse fungal pathogens induce species-specific and endocytosis-dependent immunomodulation

Microbial pathogens generate extracellular vesicles (EVs) for intercellular communication and quorum sensing. Microbial EVs also induce inflammatory pathways within host innate immune cells. We previously demonstrated that EVs secreted by Candida albicans trigger type I interferon signaling in host cells specifically via the cGAS-STING innate immune signaling pathway. Here, we show that despite sharing similar properties of morphology and internal DNA content, the interactions between EVs and the innate immune system differ according to the parental fungal species. EVs secreted by C. albicans, Saccharomyces cerevisiae, Cryptococcus neoformans, and Aspergillus fumigatus are endocytosed at different rates by murine macrophages triggering varied cytokine responses, innate immune signaling, and subsequent immune cell recruitment. Notably, cell wall constituents that decorate C. neoformans and A. fumigatus EVs inhibit efficient internalization by macrophages and dampen innate immune activation. Our data uncover the transcriptional and functional consequences of the internalization of diverse fungal EVs by immune cells and reveal novel insights into the early innate immune response to distinct clinically significant fungal pathogens.

Hidden allies: how extracellular vesicles drive biofilm formation, stress adaptation, and host-immune interactions in human fungal pathogens

Pathogenic fungi pose a significant threat to human health, especially given the rising incidence of invasive fungal infections and the emergence of drug-resistant strains. This requires the development of vaccines and the advancement of antifungal strategies. Recent studies have focused on the roles of fungal extracellular vesicles (EVs) in intercellular communication and host-pathogen interactions. EVs are nanosized, lipid membrane-bound particles that facilitate the transfer of proteins, lipids, and nucleic acids. Here, we review the multifaceted functions of EVs produced by different human fungal pathogens, highlighting their importance in the response of fungal cells to different environmental cues and their interactions with host immune cells. We summarize the current state of research on EVs and how leveraging this knowledge can lead to innovative approaches in vaccine development and antifungal treatment.

Host innate immune systems gather intel on invading microbes via pathogen-derived extracellular vesicles

Extracellular vesicles (EVs) are membrane-bound vesicles released into the extracellular milieu from various cell types including host cells and pathogens that infect them. As carriers of nucleic acids, proteins, lipids, metabolites, and virulence factors, EVs act as delivery vehicles for intercellular communication and quorum sensing. Innate immune cells have the capacity to intercept, internalize, and interpret 'messages' contained within these EVs. This review categorizes the ability of EVs secreted by bacterial, parasitic, and fungal pathogens to trigger both pro- and anti-inflammatory innate immune responses in the host. Understanding molecular pathways and inflammatory responses activated in innate immune cells upon pathogen-derived EV stimulation is critical to gain insight into potential therapeutics and combat these infectious diseases.

Fungi and tumors: The role of fungi in tumorigenesis (Review)

Fungi inhabit different anatomic sites in the human body. Advances in omics analyses of host‑microbiome interactions have tremendously improved our understanding of the effects of fungi on human health and diseases such as tumors. Due to the significant enrichment of specific fungi in patients with malignant tumors, the associations between fungi and human cancer have attracted an increasing attention in recent years. Indeed, cancer type‑specific fungal profiles have been found in different tumor tissues. Importantly, fungi also influence tumorigenesis through multiple factors, such as host immunity and bioactive metabolites. Microbiome interactions, host factors and fungal genetic and epigenetic factors could be involved in fungal enrichment in tumor tissues and/or in the conversion from a commensal fungus to a pathogenic fungus. Exploration of the interactions of fungi with the bacterial microbiome and the host may enable them to be a target for cancer diagnosis and treatment. In the present review, the associations between fungi and human cancer, cancer type‑specific fungal profiles and the mechanisms by which fungi cause tumorigenesis were discussed. In addition, possible factors that can lead to the enrichment of fungi in tumor tissues and/or the conversion of commensal fungi to pathogenic fungi, as well as potential therapeutic and preventive strategies for tumors based on intratumoral fungi were summarized.

The multiple frontiers in the study of extracellular vesicles produced by fungi

The production of extracellular vesicles (EVs) by fungi has been recognized for about a decade. Here we discuss the roles played by fungal EVs in biofilm formation, antifungal resistance, and release of immunogens with vaccine potential. We also explore their significance in promoting international collaboration and understanding of fungal biology.

RNA-containing extracellular vesicles in infection

Extracellular vesicles (EVs) are membrane-bound particles released by cells that play vital roles in intercellular communication by transporting diverse biologically active molecules, including RNA molecules, including mRNA, miRNA, lncRNA, and other regulatory RNAs. These RNA types are protected within the lipid bilayer of EVs, ensuring their stability and enabling long-distance cellular interactions. Notably, EVs play roles in infection, where pathogens and host cells use EV-mediated RNA transfer to influence immune responses and disease outcomes. For example, bacterial EVs play a crucial role in infection by modulating host immune responses and facilitating pathogen invasion. This review explores the complex interactions between EV-associated RNA and host-pathogen dynamics in bacteria, parasites, and fungi, aiming to uncover molecular mechanisms in infectious diseases and potential therapeutic targets.

Fungal extracellular vesicle-mediated regulation: from virulence factor to clinical application

Invasive fungal disease (IFD) poses a significant threat to immunocompromised patients and remains a global challenge due to limited treatment options, high mortality and morbidity rates, and the emergence of drug-resistant strains. Despite advancements in antifungal agents and diagnostic techniques, the lack of effective vaccines, standardized diagnostic tools, and efficient antifungal drugs contributes to the ongoing impact of invasive fungal infections (IFI). Recent studies have highlighted the presence of extracellular vesicles (EVs) released by fungi carrying various components such as enzymes, lipids, nucleic acids, and virulence proteins, which play roles in both physiological and pathological processes. These fungal EVs have been shown to interact with the host immune system during the development of fungal infections whereas their functional role and potential application in patients are not yet fully understood. This review summarizes the current understanding of the biologically relevant findings regarding EV in host-pathogen interaction, and aim to describe our knowledge of the roles of EV as diagnostic tools and vaccine vehicles, offering promising prospects for the treatment of IFI patients.