Adipose tissue-derived mesenchymal stem cells (ADSCs) have anti-inflammatory and immunomodulatory characteristics. Many studies have suggested that the immunomodulation of ADSCs is largely mediated by secreted paracrine factors. Various factors are secreted from ADSCs, among which extracellular vesicles are considered to play a major role in the communication between ADSCs and target cells. Several studies have reported the function of canine ADSC-derived extracellular vesicles (cADSC-EVs), but few studies have reported the immunomodulatory effects of cADSC-EVs on immune cells. The purpose of this study was to investigate the effects of cADSC-EVs on in vitro-stimulated CD4⁺ T cells isolated from peripheral blood mononuclear cells (PBMCs). cADSC-EVs were isolated from cADSCs under naive conditions or primed conditions by tumor necrosis factor-α (TNFα) and interferon-γ (IFNγ). The expression levels of several microRNAs in cADSC-EVs were altered by priming with TNFα and IFNγ. Culturing PBMCs stimulated with concanavalin A in the presence of naive or primed cADSC-EVs inhibited the differentiation of PBMCs and CD4⁺ T cells and promoted apoptosis of PBMCs. CD4⁺, CD8⁺, and CD4⁺CD8⁺ T cells were decreased, while CD3⁺CD4^-CD8^- T cells were increased. T helper (Th) 1, Th2, Th17, and regulatory T (Treg) cells were analyzed by flow cytometry. cADSC-EVs inhibited the proliferation of Th1 and Th17 cells and enhanced Th2 and Treg cell proliferation. However, CD4⁺ T cells that had incorporated labeled cADSC-EVs comprised only a few percent of all cells. Therefore, these responses of stimulated CD4⁺ T cells may be due to not only direct effects of cADSC-EVs but also to indirect effects through interactions between cADSC-EVs and other immune cells. In conclusion, cADSC-EVs exert immunosuppressive effects on stimulated CD4⁺ T cells in vitro. These findings may be useful for further studies of immune diseases.

中文翻译：

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犬脂肪组织间充质干细胞来源的细胞外囊泡对从外周血单个核细胞中分离的受激 CD4+ T 细胞的免疫调节作用

脂肪组织来源的间充质干细胞 (ADSCs) 具有抗炎和免疫调节特性。许多研究表明，ADSCs 的免疫调节主要由分泌的旁分泌因子介导。ADSCs分泌多种因子，其中细胞外囊泡被认为在ADSCs与靶细胞之间的通讯中起主要作用。几项研究报道了犬 ADSC 衍生的细胞外囊泡 (cADSC-EVs) 的功能，但很少有研究报道 cADSC-EVs 对免疫细胞的免疫调节作用。本研究的目的是研究 cADSC-EVs 对体外刺激的 CD4 ⁺从外周血单个核细胞 (PBMC) 中分离的 T 细胞。cADSC-EVs 是在幼稚条件下或通过肿瘤坏死因子-α (TNF α ) 和干扰素-γ (IFN γ ) 引发的条件下从 cADSCs 中分离出来的。cADSC-EVs 中几种 microRNA 的表达水平通过 TNF α和 IFN γ引发而改变。在幼稚或启动的 cADSC-EV 存在下培养用刀豆球蛋白 A 刺激的 PBMC 可抑制 PBMC 和 CD4 ⁺ T 细胞的分化并促进 PBMC 的凋亡。CD4 ⁺、CD8 ⁺和 CD4 ⁺ CD8 ⁺ T 细胞减少，而 CD3 ⁺CD4 ^- CD8 ^- T 细胞增加。通过流式细胞术分析 T 辅助 (Th) 1、Th2、Th17 和调节性 T (Treg) 细胞。cADSC-EVs 抑制 Th1 和 Th17 细胞的增殖并增强 Th2 和 Treg 细胞的增殖。然而，含有标记的 cADSC-EV 的CD4 ^{+ T 细胞仅占所有细胞的百分之几。}因此，受刺激的 CD4 ⁺ T 细胞的这些反应可能不仅是由于 cADSC-EV 的直接影响，还可能是由于 cADSC-EV 与其他免疫细胞之间相互作用的间接影响。总之，cADSC-EVs 在体外对受刺激的 CD4 ⁺ T 细胞发挥免疫抑制作用. 这些发现可能有助于进一步研究免疫疾病。