Living organisms must adapt and communicate effectively in their environment to survive. Cells communicate through various mechanisms, including releasing growth factors, chemokines, small bioactive molecules, and cell–cell contact. In recent years, a new and sophisticated cell communication mechanism based on extracellular vesicles (EVs) has been described in all three domains of life: archaea, bacteria, and eukaryotes. EVs are small, bilayer proteolipid vesicles released by cells into the extracellular space. This review aims to analyze and compare the current literature on bacterial, archaeal, and eukaryotic EVs and their possible clinical applications. This framework will address three key points: (a) The role of EVs in bacteria, eukaryotes, and archaea. (b) What is the impact of EVs in archaea on disease? (c) How archaea use EVs to communicate with other domains (bacteria/eukaryotes).

The nasal microbiome represents a complex and dynamic microbial ecosystem that contributes to mucosal defense, epithelial homeostasis, immune regulation, and olfactory function. Increasing evidence indicates that this microbial community actively interacts with host physiology, while alterations in its composition are associated with chronic inflammation, oxidative stress, and olfactory impairment. Such changes have been reported in conditions including chronic rhinosinusitis, allergic rhinitis, and post-viral anosmia. Beyond local effects, chronic nasal inflammation has been hypothesized to influence neuroinflammatory processes and protein aggregation pathways involving α-synuclein and tau, potentially linking nasal microbial imbalance to neurodegenerative mechanisms. However, current evidence remains largely indirect and does not support a causal relationship. This narrative review summarizes current clinical and immunological evidence on the role of the nasal microbiome in olfactory function and dysfunction, highlighting limitations of existing studies and outlining future research directions.

Background: Lactic acid bacteria are increasingly being studied for their immunomodulatory activity and protective effects against pathogens. Limosilactobacillus fermentum DSM 34872, isolated from human breast milk, was evaluated for its prophylactic potential using Galleria mellonella as an alternative preclinical model. Results: The antimicrobial activity of L. fermentum against Salmonella enterica subsp. enterica serovar Typhimurium or Enterococcus faecalis was first assessed in vitro by the overlay assay. In vivo, G. mellonella larvae were orally administered with L. fermentum via gavage and exposed to pathogens. Survival rates, melanization score, and expression of immune-related genes ( dorsal, relish, gallerimycin, gloverin ) were evaluated in both the gut and hemolymph using RT-qPCR at 4 and 24 h after infection. Conclusion: L. fermentum showed antibacterial activity in vitro. In vivo, pre-treatment with L. fermentum significantly increased survival and delayed mortality. The melanization score supported the in vivo survival results. Gene expression analysis revealed modulation of key immune markers in both the gut and hemolymph, suggesting controlled immune activation rather than hyperinflammation in L. fermentum pretreated groups. Prophylactic oral administration of L. fermentum protected against lethal bacterial infections in G. mellonella , altering both local and systemic immune responses. These results highlight the potential of L. fermentum as a promising candidate for future in vivo analyses and confirm G. mellonella as an ethical, economical, and reliable preclinical model for preliminary screening, with the aim of subsequent evaluations in accredited clinical models.