Platelets are a rich source of many cytokines and chemokines including transforming growth factor β 1 (TGF-β1). TGF-β1 is required to convert conventional CD4⁺ T (Tconv) cells into induced regulatory T (iTreg) cells that express the transcription factor Foxp3. Whether platelet contents will affect Treg cell properties has not been explored. In this study, we show that unfractionated platelet lysates (pltLys) containing TGF-β1 efficiently induced Foxp3 expression in Tconv cells. The common Treg cell surface phenotype and in vitro suppressive activity of unfractionated pltLys-iTreg cells were similar to those of iTreg cells generated using purified TGF-β1 (purTGFβ-iTreg) cells. However, there were substantial differences in gene expression between pltLys-iTreg and purTGFβ-iTreg cells, especially in granzyme B, interferon γ, and interleukin-2 (a 30.99-, 29.18-, and 17.94-fold difference, respectively) as determined by gene microarray analysis. In line with these gene signatures, we found that pltLys-iTreg cells improved cell recovery after transfer and immune suppressive function compared with purTGFβ-iTreg cells in factor VIII (FVIII)–deficient (F8^null, hemophilia A model) mice after recombinant human FVIII (rhF8) infusion. Acute antibody-mediated platelet destruction in F8^null mice followed by rhF8 infusion increased the number of Treg cells and suppressed the antibody response to rhF8. Consistent with these data, ex vivo proliferation of F8-specific Treg cells from platelet-depleted animals increased when restimulated with rhF8. Together, our data suggest that pltLys-iTreg cells may have advantages in emerging clinical applications and that platelet contents impact the properties of iTreg cells induced by TGF-β1.

摘要

血小板是許多細胞因子和趨化因子的豐富來源，包括轉化生長因子 β 1 （TGF-β1）。TGF-β1 是將常規(guī) CD4+ T （Tconv）細胞轉化為表達轉錄因子 Foxp3 的誘導調節(jié)性 T （iTreg）細胞所必需的。血小板內容物是否會影響Treg細胞特性尚未得到探索。在這項研究中，我們發(fā)現(xiàn)含有 TGF-β1 的普通血小板裂解物（pltLys）有效地誘導了 Tconv 細胞中 Foxp3 的表達。普通 pltLys-iTreg 細胞的常見 Treg 細胞表面表型和體外抑制活性與純化 TGF-β1 （purTGFβ-iTreg）細胞生成的 iTreg 細胞相似。然而，通過基因微陣列分析確定，pltLys-iTreg 和 purTGFβ-iTreg 細胞之間的基因表達存在顯著差異，尤其是在顆粒酶 B、干擾素 γ 和白細胞介素-2 中（分別相差 30.99 倍、29.18 倍和 17.94 倍）。根據這些基因特征，我們發(fā)現(xiàn)在重組人FVIII（rhF8）輸注后，與凝血因子VIII（FVIII）缺陷（F8null，血友病A模型）小鼠中的purTGFβ-iTreg細胞相比，pltLys-iTreg細胞改善了轉移后的細胞恢復和免疫抑制功能。在F8null小鼠中，急性抗體介導的血小板破壞，然后輸注rhF8，增加了Treg細胞的數(shù)量，并抑制了對rhF8的抗體反應。與這些數(shù)據一致，當用rhF8重新刺激時，來自血小板耗盡動物的F8特異性Treg細胞的離體增殖增加?？傊覀兊臄?shù)據表明，pltLys-iTreg細胞可能在新興的臨床應用中具有優(yōu)勢，并且血小板含量會影響TGF-β1誘導的iTreg細胞的性質。