Institute of Liver Studies, King's College London School of Medicine at King's College Hospital, Denmark Hill, London, United Kingdom.
Hepatology. 2012 Aug;56(2):677-86. doi: 10.1002/hep.25682. Epub 2012 Jul 6.
In autoimmune hepatitis (AIH), liver-damaging CD4 T cell responses are associated with defective CD4(pos) CD25(pos) regulatory T cells (T-regs). Galectin-9 (Gal9), a β-galactosidase-binding protein expressed by T-regs, is key to their function, inhibiting T helper 1 immune responses by binding T cell immunoglobulin and mucin domain 3 (Tim-3) on CD4 effector cells. We investigated whether impaired immunoregulation in AIH results from reduced expression of Gal9 in T-regs and/or Tim-3 on CD4 effector cells. Circulating Gal9(pos) CD4(pos) CD25(pos) and Tim-3(pos) CD4(pos) CD25(neg) T cell phenotype was assessed by flow cytometry in 75 AIH patients. To evaluate whether Tim-3 expression renders CD4(pos) CD25(neg) T cells amenable to T-reg control, purified CD4(pos) CD25(neg) Tim-3(pos) (Tim-3(pos)) and CD4(pos) CD25(neg) Tim-3(neg) (Tim-3(neg)) cells were cocultured with T-regs. To determine whether Gal9 expression is essential to function, T-regs were treated with small interfering RNA (siRNA) to repress Gal-9 translation; T-reg suppressor function was assessed by proliferation. In AIH, Tim-3(pos) cells within CD4(pos) CD25(neg) cells and their T-bet(pos) and RORC(pos) subsets were fewer and contained higher numbers of interferon-γ (IFNγ)(pos) and interleukin (IL)-17(pos) cells than healthy subjects (HS). In AIH and HS, Tim-3(pos) cells proliferated less vigorously and were more susceptible to T-reg control than Tim-3(neg) cells. In AIH, Gal9(pos) T-regs were fewer and contained less FOXP3(pos), IL-10(pos), and transforming growth factor β(pos) and more IFNγ(pos) and IL-17(pos) cells than HS. siRNA treatment of Gal-9(pos) T-regs drastically reduced T-reg ability to suppress CD4(pos) CD25(neg) and Tim-3(pos) cell proliferation in AIH and HS. Tim-3(pos) cell percentage correlated inversely with aminotransferase and CD25(neg) T-bet(pos) cell values.
Reduced levels of Tim-3 on CD4(pos) CD25(neg) effector cells and of Gal9 in T-regs contribute to impaired immunoregulation in AIH by rendering effector cells less prone to T-reg control and T-regs less capable of suppressing.
在自身免疫性肝炎（AIH）中，损伤的 CD4 T 细胞应答与缺陷的 CD4(+)CD25(+)调节性 T 细胞（T-reg）有关。Galectin-9（Gal9），一种在 T-reg 中表达的β-半乳糖苷酶结合蛋白，是其功能的关键，通过结合 CD4 效应细胞上的 T 细胞免疫球蛋白和粘蛋白结构域 3（Tim-3）抑制辅助性 T 1 免疫应答。我们研究了 AIH 中免疫调节受损是否是由于 T-reg 中 Gal9 的表达减少和/或 CD4 效应细胞上 Tim-3 的表达减少所致。通过流式细胞术评估了 75 例 AIH 患者循环中 Gal9(+)CD4(+)CD25(+)和 Tim-3(+)CD4(+)CD25(neg)T 细胞表型。为了评估 Tim-3 表达是否使 CD4(+)CD25(neg)T 细胞易于受到 T-reg 控制，我们将纯化的 CD4(+)CD25(neg)Tim-3(+)（Tim-3(+)）和 CD4(+)CD25(neg)Tim-3(neg)（Tim-3(neg)）细胞与 T-reg 共培养。为了确定 Gal9 的表达是否对功能至关重要，我们用小干扰 RNA（siRNA）处理 T-reg 以抑制 Gal-9 翻译；通过增殖评估 T-reg 抑制功能。在 AIH 中，CD4(+)CD25(neg)细胞内的 Tim-3(+)细胞及其 T-bet(+)和 RORC(+)亚群比健康受试者（HS）更少，并且含有更多的干扰素-γ（IFNγ）（+）和白细胞介素（IL）-17（+）细胞。在 AIH 和 HS 中，Tim-3(+)细胞比 Tim-3(neg)细胞增殖更不活跃，更易受 T-reg 控制。在 AIH 中，Gal9(+)T-reg 比 HS 中的更少，且含有更少的 FOXP3(+)、IL-10(+)和转化生长因子β（TGFβ）（+），含有更多的 IFNγ（+）和 IL-17（+）细胞。Gal-9(+)T-reg 的 siRNA 处理大大降低了 AIH 和 HS 中 T-reg 抑制 CD4(+)CD25(neg)和 Tim-3(+)细胞增殖的能力。Tim-3(+)细胞百分比与氨基转移酶和 CD25(neg)T-bet(+)细胞值呈负相关。
CD4(+)CD25(neg)效应细胞上 Tim-3 的水平降低和 T-reg 中 Gal9 的水平降低导致 AIH 中的免疫调节受损，使效应细胞更不易受到 T-reg 控制，T-reg 更不能抑制。
