Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, New York, USA.
Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA.
Sci Rep. 2018 May 23;8(1):8065. doi: 10.1038/s41598-018-25665-5.
Diverse pathogenic fungi secrete extracellular vesicles (EV) that contain macromolecules, including virulence factors that can modulate the host immune response. We recently demonstrated that the binding of monoclonal antibodies (mAb) modulates how Histoplasma capsulatum load and releases its extracellular vesicles (EV). In the present paper, we addressed a concentration-dependent impact on the fungus' EV loading and release with different mAb, as well as the pathophysiological role of these EV during the host-pathogen interaction. We found that the mAbs differentially regulate EV content in concentration-dependent and independent manners. Enzymatic assays demonstrated that laccase activity in EV from H. capsulatum opsonized with 6B7 was reduced, but urease activity was not altered. The uptake of H. capsulatum by macrophages pre-treated with EV, presented an antibody concentration-dependent phenotype. The intracellular killing of yeast cells was potently inhibited in macrophages pre-treated with EV from 7B6 (non-protective) mAb-opsonized H. capsulatum and this inhibition was associated with a decrease in the reactive-oxygen species generated by these macrophages. In summary, our findings show that opsonization quantitatively and qualitatively modifies H. capsulatum EV load and secretion leading to distinct effects on the host's immune effector mechanisms, supporting the hypothesis that EV sorting and secretion are dynamic mechanisms for a fine-tuned response by fungal cells.
多种致病性真菌分泌包含大分子的细胞外囊泡 (EV)，包括可调节宿主免疫反应的毒力因子。我们最近证明，单克隆抗体 (mAb) 的结合可调节荚膜组织胞浆菌的负荷及其细胞外囊泡 (EV) 的释放。在本论文中，我们研究了不同 mAb 对真菌 EV 负载和释放的浓度依赖性影响，以及这些 EV 在宿主-病原体相互作用过程中的病理生理作用。我们发现，mAb 以浓度依赖和非依赖的方式差异调节 EV 含量。酶促测定表明，与 6B7 包被的荚膜组织胞浆菌的 EV 中的漆酶活性降低，但脲酶活性没有改变。用 EV 预处理的巨噬细胞摄取荚膜组织胞浆菌呈现出抗体浓度依赖性表型。用非保护性 7B6 (mAb) 包被的荚膜组织胞浆菌的 EV 预处理的巨噬细胞中，酵母细胞的胞内杀伤被强烈抑制，这种抑制与这些巨噬细胞产生的活性氧减少有关。总之，我们的研究结果表明，调理作用定量和定性地改变了荚膜组织胞浆菌 EV 的负载和分泌，导致对宿主免疫效应机制的不同影响，支持了 EV 分拣和分泌是真菌细胞精细调节反应的动态机制的假说。
