Department of Urologic Sciences, University of British Columbia, Vancouver, British Columbia, Canada.
Int Immunopharmacol. 2013 Aug;16(4):414-23. doi: 10.1016/j.intimp.2013.04.031. Epub 2013 May 16.
Inactivation of T cells is a widely used strategy for immunosuppression. Halofuginone (HF) is an antiprotozoal agent for treating parasites in veterinary medicine, and has been demonstrated to inhibit collagen type 1 synthesis, T helper 17 cell differentiation and cytokine production in activated T cells. The present study was designed to examine the biological effects of HF against T cell receptor and interleukin (IL)-2 stimulated T cell proliferation. T cell proliferation in cultured murine splenocytes was determined by methylthiazol tetrazolium assay. Cell apoptosis was mainly determined by fluorescence-activated cell sorting with Annexin-V and 7-aminoactinomycin D staining. Here, we showed that HF significantly suppressed T cell proliferation in naïve splenocyte cultures in response to alloantigen or anti-CD3 antibody (IC₅₀, 2-2.5 nM; P<0.0001), or in activated T cell cultures in response to IL-2 (IC₅₀, 16 nM; P<0.0001) in a dose-dependent manner. HF did neither attenuate IL-2 production in anti-CD3 antibody activated T cells nor disrupt STAT5 signaling in IL-2-stimulated T cells, but its anti-T cell proliferation was correlated with an increase in cell apoptosis and a decrease in proline uptake in culture medium. Further experiments showed that proline supplement in cell culture medium significantly prevented HF-mediated suppression of T cell proliferation and cell apoptosis. In conclusion, these data suggest that HF interferes with proline incorporation or uptake, resulting in apoptosis via amino acid starvation response in T cells in the response to antigen/mitogen or IL-2 stimulation.
T 细胞失活是一种广泛应用于免疫抑制的策略。卤夫酮（HF）是一种兽用抗寄生虫药物，已被证明可抑制胶原 1 型合成、辅助性 T 细胞 17 分化和细胞因子产生。本研究旨在研究 HF 对 T 细胞受体和白细胞介素（IL）-2 刺激的 T 细胞增殖的生物学影响。通过噻唑蓝比色法测定培养的鼠脾细胞中 T 细胞的增殖。通过 Annexin-V 和 7-氨基放线菌素 D 染色的荧光激活细胞分选主要测定细胞凋亡。在这里，我们表明 HF 可显著抑制同种抗原或抗 CD3 抗体刺激的幼稚脾细胞培养物中的 T 细胞增殖（IC₅₀，2-2.5 nM；P<0.0001），或 IL-2 刺激的激活 T 细胞培养物中的 T 细胞增殖（IC₅₀，16 nM；P<0.0001），呈剂量依赖性。HF 既不减弱抗 CD3 抗体激活的 T 细胞中 IL-2 的产生，也不破坏 IL-2 刺激的 T 细胞中的 STAT5 信号，但它的抗 T 细胞增殖与细胞凋亡增加和培养基中脯氨酸摄取减少有关。进一步的实验表明，细胞培养基中脯氨酸的补充可显著防止 HF 介导的 T 细胞增殖和细胞凋亡的抑制。总之，这些数据表明 HF 通过氨基酸饥饿反应干扰 T 细胞中抗原/有丝分裂原或 IL-2 刺激时的脯氨酸掺入或摄取，从而导致细胞凋亡。
