Inflammasome-Derived Exosomes Activate NF-κB Signaling in Macrophages

Exosomes are secreted small vesicles
that mediate various biological
processes, such as tumorigenesis and immune response. However, whether
the inflammasome signaling leads to the change of constituent of exosomes
and its roles in immune response remains to be determined. We isolated
the exosomes from macrophages with treatment of mock, endotoxin, or
endotoxin/nigericin. A label-free quantification method by MS/MS was
used to identify the components of exosomes. In total, 2331 proteins
were identified and 513 proteins were exclusively detected in exosomes
with endotoxin and nigericin treatment. The differentially expressed
proteins were classified by Gene Ontology and KEGG pathways. The immune
response-related proteins and signaling pathways were specifically
enriched in inflammasome-derived exosomes. Moreover, we treated macrophages
with the exosomes from different stimulation. We found that inflammasome-derived
exosomes directly activate NF-κB signaling pathway, while the
control or endotoxin-derived exosomes have no effect. The inflammatory
signaling was amplified in neighbor cells in an exosome-dependent
way. The inflammasome-derived exosomes might be used to augment the
immune response in disease treatment, and preventing the transfer
of these exosomes might ameliorate autoimmune diseases.

外泌体（exosomes）是一类分泌型小囊泡，可介导多种生物学过程，例如肿瘤发生与免疫应答。然而，炎性体信号通路是否会引发外泌体组分改变，以及该改变在免疫应答中发挥的功能，仍有待阐明。本研究从经模拟处理、脂多糖（endotoxin）或脂多糖/尼日利亚菌素（nigericin）处理的巨噬细胞中分离出外泌体，采用基于质谱联用（MS/MS）的无标记定量技术对外泌体组分进行鉴定。共计鉴定得到2331种蛋白质，其中513种蛋白质仅在经脂多糖/尼日利亚菌素处理的巨噬细胞来源的外泌体中被检出。本研究通过基因本体论（Gene Ontology）与京都基因与基因组百科全书（KEGG）通路分析，对差异表达蛋白质进行功能分类，发现与免疫应答相关的蛋白质及信号通路在炎性体来源的外泌体中显著富集。此外，我们采用不同刺激条件下产生的外泌体处理巨噬细胞，结果显示炎性体来源的外泌体可直接激活核因子κB（NF-κB）信号通路，而对照组或脂多糖处理组来源的外泌体则无此效应。炎性信号可通过外泌体依赖的方式在邻近细胞中被放大。综上，炎性体来源的外泌体或可用于增强疾病治疗中的免疫应答，而阻断此类外泌体的传递则有望缓解自身免疫性疾病。