Polymorphonuclear granulocytes (PMNs) are indispensable for controlling life-threatening fungal infections. In addition to various effector mechanisms, PMNs also produce extracellular vesicles (EVs). Their contribution to antifungal defense has remained unexplored. We reveal that the clinically important human-pathogenic fungus Aspergillus fumigatus triggers PMNs to release a distinct set of antifungal EVs (afEVs). Proteome analyses indicated that afEVs are enriched in antimicrobial proteins. The cargo and the release kinetics of EVs are modulated by the fungal strain confronted. Tracking of afEVs indicated that they associated with fungal cells and even entered fungal hyphae, resulting in alterations in the morphology of the fungal cell wall and dose-dependent antifungal effects. To assess as a proof of concept whether the antimicrobial proteins found in afEVs might contribute to growth inhibition of hyphae when present in the fungal cytoplasm, two human proteins enriched in afEVs, cathepsin G and azurocidin, were heterologously expressed in fungal hyphae. This led to reduced fungal growth relative to that of a control strain producing the human retinol binding protein 7. In conclusion, extracellular vesicles produced by neutrophils in response to A. fumigatus infection are able to associate with the fungus, limit growth, and elicit cell damage by delivering antifungal cargo. This finding offers an intriguing, previously overlooked mechanism of antifungal defense against A. fumigatusIMPORTANCE Invasive fungal infections caused by the mold Aspergillus fumigatus are a growing concern in the clinic due to the increasing use of immunosuppressive therapies and increasing antifungal drug resistance. These infections result in high rates of mortality, as treatment and diagnostic options remain limited. In healthy individuals, neutrophilic granulocytes are critical for elimination of A. fumigatus from the host; however, the exact extracellular mechanism of neutrophil-mediated antifungal activity remains unresolved. Here, we present a mode of antifungal defense employed by human neutrophils against A. fumigatus not previously described. We found that extracellular vesicles produced by neutrophils in response to A. fumigatus infection are able to associate with the fungus, limit growth, and elicit cell damage by delivering antifungal cargo. In the end, antifungal extracellular vesicle biology provides a significant step forward in our understanding of A. fumigatus host pathogenesis and opens up novel diagnostic and therapeutic possibilities.

译文

多形核粒细胞 (pmn) 对于控制威胁生命的真菌感染是必不可少的。除了各种效应器机制外,pmn还产生细胞外囊泡 (EVs)。他们对抗真菌防御的贡献尚未得到探索。我们揭示了临床上重要的人类致病性真菌烟曲霉触发pmn释放出一组独特的抗真菌ev (afEVs)。蛋白质组分析表明,afEVs富含抗菌蛋白。EVs的货物和释放动力学受所面对的真菌菌株的调节。afEVs的跟踪表明它们与真菌细胞相关,甚至进入真菌菌丝,导致真菌细胞壁形态的改变和剂量依赖性的抗真菌作用。为了评估在真菌细胞质中存在的afEVs中发现的抗菌蛋白是否可能有助于抑制菌丝的生长,在真菌菌丝中异源表达了两种富含afEVs的人类蛋白,组织蛋白酶G和天青素。相对于产生人视黄醇结合蛋白7的对照菌株,这导致真菌生长减少。总之,嗜中性粒细胞对烟曲霉感染产生的细胞外囊泡能够与真菌结合,限制生长并通过传递抗真菌货物引起细胞损伤。这一发现提供了一个有趣的,以前被忽视的抗真菌防御A的机制。由于越来越多地使用免疫抑制疗法和抗真菌药物耐药性,由霉菌烟曲霉引起的烟曲霉侵袭性真菌感染在临床上日益受到关注。这些感染导致高死亡率,因为治疗和诊断选择仍然有限。在健康个体中,嗜中性粒细胞对于从宿主中消除烟曲霉至关重要; 然而,中性粒细胞介导的抗真菌活性的确切细胞外机制仍未解决。在这里,我们提出了一种人类嗜中性粒细胞针对烟曲霉的抗真菌防御模式,以前没有描述过。我们发现,嗜中性粒细胞对烟曲霉感染产生的细胞外囊泡能够与真菌结合,限制生长并通过传递抗真菌货物引起细胞损伤。最后,抗真菌细胞外囊泡生物学为我们对烟曲霉宿主发病机理的理解提供了重要的一步,并开辟了新的诊断和治疗可能性。

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