Division of Clinical Immunology and Rheumatology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Diabetes. 2009 Nov;58(11):2498-505. doi: 10.2337/db09-0216. Epub 2009 Aug 12.
We sought to determine whether exosome-like vesicles (ELVs) released from adipose tissue play a role in activation of macrophages and subsequent development of insulin resistance in a mouse model.
ELVs released from adipose tissue were purified by sucrose gradient centrifugation and labeled with green fluorescent dye and then intravenously injected into B6 ob/ob mice (obese model) or B6 mice fed a high-fat diet. The effects of injected ELVs on the activation of macrophages were determined through analysis of activation markers by fluorescence-activated cell sorter and induction of inflammatory cytokines using an ELISA. Glucose tolerance and insulin tolerance were also evaluated. Similarly, B6 mice with different gene knockouts including TLR2, TLR4, MyD88, and Toll-interleukin-1 receptor (TIR) domain-containing adaptor protein inducing interferon-beta (TRIF) were also used for testing their responses to the injected ELVs.
ELVs are taken up by peripheral blood monocytes, which then differentiate into activated macrophages with increased secretion of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Injection of obELVs into wild-type C57BL/6 mice results in the development of insulin resistance. When the obELVs were intravenously injected into TLR4 knockout B6 mice, the levels of glucose intolerance and insulin resistance were much lower. RBP4 is enriched in the obELVs. Bone marrow-derived macrophages preincubated with recombinant RBP4 led to attenuation of obELV-mediated induction of IL-6 and TNF-alpha.
ELVs released by adipose tissue can act as a mode of communication between adipose tissues and macrophages. The obELV-mediated induction of TNF-alpha and IL-6 in macrophages and insulin resistance requires the TLR4/TRIF pathway.
我们旨在确定脂肪组织释放的类外泌体小泡（ELVs）是否在肥胖模型小鼠的巨噬细胞激活和随后发生胰岛素抵抗中发挥作用。
通过蔗糖密度梯度离心法纯化脂肪组织释放的 ELVs，并用绿色荧光染料进行标记，然后静脉内注射到 B6 ob/ob 小鼠（肥胖模型）或高脂饮食喂养的 B6 小鼠体内。通过荧光激活细胞分选分析激活标志物以及酶联免疫吸附试验（ELISA）检测炎性细胞因子的诱导，来确定注射的 ELVs 对巨噬细胞激活的影响。还评估了葡萄糖耐量和胰岛素耐量。同样，还使用具有不同基因敲除的 B6 小鼠，包括 TLR2、TLR4、MyD88 和 Toll-白细胞介素-1 受体（TIR）域包含衔接蛋白诱导干扰素-β（TRIF），以测试它们对注射的 ELVs 的反应。
ELVs 被外周血单核细胞摄取，然后分化为激活的巨噬细胞，其肿瘤坏死因子-α（TNF-α）和白细胞介素-6（IL-6）的分泌增加。将 obELVs 注射到野生型 C57BL/6 小鼠中会导致胰岛素抵抗的发展。当将 obELVs 静脉内注射到 TLR4 敲除 B6 小鼠中时，葡萄糖不耐受和胰岛素抵抗的水平要低得多。RBP4 在 obELVs 中富集。用重组 RBP4 预先孵育的骨髓来源的巨噬细胞导致 obELV 介导的 IL-6 和 TNF-α诱导减弱。
脂肪组织释放的 ELVs 可以作为脂肪组织与巨噬细胞之间通讯的一种方式。obELV 介导的巨噬细胞中 TNF-α和 IL-6 的诱导以及胰岛素抵抗需要 TLR4/TRIF 途径。
