Tianjin Key Laboratory of Retinal Functions and Diseases, Tianjin Branch of National Clinical Research Center for Ocular Disease, Eye Institute and School of Optometry, Tianjin Medical University Eye Hospital, Tianjin, China.
Department of Medicine/Hematology, Keck School of Medicine of the University of Southern California, Los Angeles, CA, United States.
Front Immunol. 2022 Jul 6;13:888949. doi: 10.3389/fimmu.2022.888949. eCollection 2022.
Mesenchymal stem cell-derived small extracellular vesicles (MSC-sEVs) have been increasingly proved as promising immunomodulators against some autoimmune disorders. However, the possible effect and the underlying mechanism of MSC-sEVs in autoimmune dry eye have been rarely studied.
Small extracellular vesicles from human umbilical cord mesenchymal stem cells (hUC-MSC-sEVs) were subconjunctivally injected to rabbit dry eye model, and their preventive or therapeutical effects were assessed by recording the clinical and histological scores. Quantitative real-time PCR (Q-PCR), western blot and flow cytometry were performed to evaluate the immunomodulatory effects of hUC-MSC-sEVs on macrophages and T regulatory cells (Tregs) both and , and the T cell proliferation was detected by Bromodeoxyuridine (BrdU) assay. In addition, high expression of miR-100-5p in hUC-MSC-sEVs was identified by Q-PCR, and the functional role of sEVs-miR-100-5p on macrophages was explored by a series of co-culture experiments using sEVs derived from hUC-MSCs transfected with miR-100-5p inhibitor.
We firstly demonstrated that hUC-MSC-sEVs had the preventive and therapeutical effects on rabbit autoimmune dacryoadenitis, an animal model of Sjögren's syndrome (SS) dry eye. Further investigation revealed that hUC-MSC-sEVs administration effectively elicited macrophages into an anti-inflammatory M2 phenotype and elevated the proportion of Tregs both and , which contributed to reduced inflammation and improved tissue damage. Importantly, hUC-MSC-sEVs-educated macrophages with M2-like phenotype exhibited strong capacity to inhibit CD4+ T cell proliferation and promote Treg generation . Mechanistically, miR-100-5p was highly enriched in hUC-MSC-sEVs, and knockdown of miR-100-5p in hUC-MSC-sEVs partially blunted the promotion of hUC-MSC-sEVs on M2 macrophage polarization and even attenuated the effect of hUC-MSC-sEVs-educated macrophages on T cell suppression and Treg expansion.
Our data indicated that hUC-MSC-sEVs alleviated autoimmune dacryoadenitis by promoting M2 macrophage polarization and Treg generation possibly through shuttling miR-100-5p. This study sheds new light on the application of MSC-sEVs as a promising therapeutic method for SS dry eye.
间充质干细胞衍生的小细胞外囊泡（MSC-sEVs）已被越来越多地证明是对抗某些自身免疫性疾病的有前途的免疫调节剂。然而，MSC-sEVs 在自身免疫性干眼中的可能作用和潜在机制很少被研究。
通过结膜下注射人脐带间充质干细胞（hUC-MSC-sEVs）中的小细胞外囊泡，评估其对兔干眼模型的预防或治疗效果，并通过记录临床和组织学评分进行评估。通过实时定量 PCR（Q-PCR）、Western blot 和流式细胞术评估 hUC-MSC-sEVs 对巨噬细胞和调节性 T 细胞（Tregs）的免疫调节作用，并用溴脱氧尿苷（BrdU）测定法检测 T 细胞增殖。此外，通过 Q-PCR 鉴定 hUC-MSC-sEVs 中 miR-100-5p 的高表达，并通过一系列使用转染 miR-100-5p 抑制剂的 hUC-MSCs 衍生的 sEVs 的共培养实验探索 sEVs-miR-100-5p 对巨噬细胞的功能作用。
我们首先证明 hUC-MSC-sEVs 对兔自身免疫性泪腺炎（干燥综合征（SS）干眼的动物模型）具有预防和治疗作用。进一步的研究表明，hUC-MSC-sEVs 给药可有效诱导巨噬细胞向抗炎 M2 表型分化，并提高 和 中的 Tregs 比例，从而减少炎症和改善组织损伤。重要的是，具有 M2 样表型的 hUC-MSC-sEVs 诱导的巨噬细胞具有强烈抑制 CD4+T 细胞增殖和促进 Treg 生成的能力。机制上，miR-100-5p 在 hUC-MSC-sEVs 中高度富集，hUC-MSC-sEVs 中的 miR-100-5p 敲低部分减弱了 hUC-MSC-sEVs 对 M2 巨噬细胞极化的促进作用，甚至减弱了 hUC-MSC-sEVs 诱导的巨噬细胞对 T 细胞抑制和 Treg 扩增的作用。
我们的数据表明，hUC-MSC-sEVs 通过促进 M2 巨噬细胞极化和 Treg 生成来减轻自身免疫性泪腺炎，可能通过转导 miR-100-5p 实现。本研究为 MSC-sEVs 作为干燥综合征干眼病有前途的治疗方法提供了新的视角。
