Work

Human neutrophils release extracellular RNA that modulates Aspergillus fumigatus gene expression across kingdoms

Year: 2026

Type: preprint

Abstract: ABSTRACT Extracellular RNAs (exRNAs) are emerging as potent bidirectional interkingdom effectors of host-pathogen interactions, particularly in plant and insect systems. Here, using small RNA-sequencing and genetic manipulation, we provide evidence consistent with a function of the human neutrophil exRNA-ome in modulating gene expression across kingdoms in the fungal pathogen Aspergillus fumigatus . The neutrophil extracellular space contains a diverse repertoire of RNA, which was corroborated using a droplet-digital stem-loop RT-PCR protocol to measure differential abundance of several tRNA-derived RNAs between two extracellular fractions. A closer inspection of the extracellular miRNA pool revealed enrichment of antimicrobial Let-7 family sRNAs and immunomodulatory miR-223, among others. Secretion of these sRNAs was largely impervious to infection status, suggesting that neutrophils produce and maintain an antimicrobial exRNA environment against A. fumigatus that requires further targeting. Cross-kingdom miRNA target prediction and exRNA delivery experiments revealed that putative fungal targets are modulated independently of the fungal argonaute proteins and in a donor-dependent manner. Although heterogeneous, for donors that exhibited a silencing effect, mutated target sequences in the fungus did reverse silencing. We hypothesize that the exRNA landscape produced by neutrophils contributes to their multifaceted role in antifungal defense. SIGNIFICANCE The human lung is regularly confronted with microbes, including several hundred asexual spores (conidia) of the mold Aspergillus fumigatus per day. These conidia are rapidly cleared in the healthy lung by phagocytes and other innate defenses; however, in immunosuppressed individuals, particularly those lacking neutrophils, A. fumigatus can germinate and establish invasive life-threatening infections. Here, we uncover a previously unappreciated mechanism contributing to neutrophil antifungal immunity, the transfer of Let-7 family microRNAs from human host to fungal pathogen to control pathogen gene expression. This first example of cross-kingdom RNA interference between human and mold bolsters the emerging concept that hosts and pathogens alike exchange RNA molecules as interkingdom effectors during the course of infection.

Source: bioRxiv (Cold Spring Harbor Laboratory)

DOI: 10.64898/2026.10.19.758605