Batiuk T D, Kung L, Halloran P F
Department of Medicine, Division of Nephrology and Immunology, University of Alberta, Edmonton, Alberta AB T6G 2R8, Canada.
J Clin Invest. 1997 Oct 1;100(7):1894-901. doi: 10.1172/JCI119719.
Cyclosporine (CsA) is both a clinical immunosuppressive drug and a probe to dissect intracellular signaling pathways. In vitro, CsA inhibits lymphocyte gene activation by inhibiting the phosphatase activity of calcineurin (CN). In clinical use, CsA treatment inhibits 50-75% of CN activity in circulating leukocytes. We modeled this degree of CN inhibition in primary human leukocytes in vitro in order to study the effect of partial CN inhibition on the downstream signaling events that lead to gene activation. In CsA-treated leukocytes stimulated by calcium ionophore, the degree of reduction in CN activity was accompanied by a similar degree of inhibition of each event tested: dephosphorylation of nuclear factor of activated T cell proteins, nuclear DNA binding, activation of a transfected reporter gene construct, IFN-gamma and IL-2 mRNA accumulation, and IFN-gamma production. Furthermore, the degree of CN inhibition was reflected by a similar degree of reduction in lymphocyte proliferation and IFN-gamma production in the allogeneic mixed lymphocyte cultures. These data support the conclusion that CN activity is rate-limiting for the activation of primary human T lymphocytes. Thus, the reduction of CN activity observed in CsA-treated patients is accompanied by a similar degree of reduction in lymphocyte gene activation, and accounts for the immunosuppression observed.
环孢素（CsA）既是一种临床免疫抑制药物，也是一种用于剖析细胞内信号通路的探针。在体外，CsA通过抑制钙调神经磷酸酶（CN）的磷酸酶活性来抑制淋巴细胞基因激活。在临床应用中，CsA治疗可抑制循环白细胞中50%-75%的CN活性。我们在体外对原代人白细胞中这种程度的CN抑制进行建模，以研究部分CN抑制对导致基因激活的下游信号事件的影响。在用钙离子载体刺激的经CsA处理的白细胞中，CN活性的降低程度伴随着对所测试的每个事件的类似程度的抑制：活化T细胞核因子蛋白的去磷酸化、核DNA结合、转染报告基因构建体的激活、IFN-γ和IL-2 mRNA积累以及IFN-γ产生。此外，在同种异体混合淋巴细胞培养中，CN抑制程度由淋巴细胞增殖和IFN-γ产生的类似程度降低所反映。这些数据支持CN活性是原代人T淋巴细胞激活的限速因素这一结论。因此，在经CsA治疗的患者中观察到的CN活性降低伴随着淋巴细胞基因激活的类似程度降低，并解释了所观察到的免疫抑制现象。
