Salas Jessica R, Ryan K M, Trias Alyssa O, Chen Bao Ying, Guemes Miriam, Galic Zoran, Schultz Kenneth A, Clark Peter M
Department of Molecular and Medical Pharmacology, UCLA, Los Angeles, California, USA.
Crump Institute for Molecular Imaging, UCLA, Los Angeles, California, USA.
Immunology. 2025 Feb;174(2):247-263. doi: 10.1111/imm.13885. Epub 2024 Dec 22.
Autoreactive, aberrantly activated lymphocytes that target myelin antigens in the central nervous system (CNS) are primary drivers of the autoimmune disease multiple sclerosis (MS). Proliferating cells including activated lymphocytes require deoxyribonucleoside triphosphates (dNTPs) for DNA replication. dNTPs can be synthesised via the de novo pathway from precursors such as glucose and amino acids or the deoxyribonucleoside salvage pathway from extracellular deoxyribonucleosides. Deoxycytidine kinase (dCK) is the rate-limiting enzyme in the salvage pathway. In prior work, we showed that targeting dCK with the small molecule inhibitor TRE-515 limits clinical symptoms in two myelin oligodendrocyte glycoprotein (MOG)-induced experimental autoimmune encephalomyelitis (EAE) mouse models of MS and decreases the levels of activated CD4 T and B lymphocytes in vivo. However, whether targeting dCK limits disease in additional EAE models and how targeting dCK directly impacts activated and proliferating CD4 T and B cells has yet to be determined. Here, we show that dCK is activated in the lymph nodes and spleen in an EAE model induced by amino acids 139-151 of the proteolipid protein (PLP) that is driven by CD4 T and B cells and is characterised by acute disease followed by disease remission. Treating this model with TRE-515 limits clinical symptoms and decreases the levels of activated CD4 T and B cells. In culture, CD4 T and B cells induce deoxyribonucleoside salvage following activation, and TRE-515 directly blocks CD4 T and B cell activation-induced proliferation and activation marker expression. TRE-515 decreases deoxycytidine triphosphate (dCTP) and deoxythymidine triphosphate (dTTP) pools and increases the length of time cells spend in S phase of the cell cycle without inducing a replication stress response in B cells. Our results suggest that dCK activity is required to supply needed dNTPs and to enable rapid cell division following lymphocyte activation against autoantigens in EAE mouse models.
靶向中枢神经系统（CNS）中髓鞘抗原的自身反应性、异常活化的淋巴细胞是自身免疫性疾病多发性硬化症（MS）的主要驱动因素。包括活化淋巴细胞在内的增殖细胞进行DNA复制需要脱氧核糖核苷三磷酸（dNTPs）。dNTPs可通过从头合成途径由葡萄糖和氨基酸等前体合成，或通过细胞外脱氧核糖核苷的脱氧核糖核苷补救途径合成。脱氧胞苷激酶（dCK）是补救途径中的限速酶。在之前的研究中，我们发现用小分子抑制剂TRE-515靶向dCK可减轻两种髓鞘少突胶质细胞糖蛋白（MOG）诱导的MS实验性自身免疫性脑脊髓炎（EAE）小鼠模型的临床症状，并降低体内活化的CD4 T和B淋巴细胞水平。然而，靶向dCK是否能在其他EAE模型中限制疾病发展，以及靶向dCK如何直接影响活化和增殖的CD4 T和B细胞，尚待确定。在此，我们表明在由蛋白脂蛋白（PLP）的139-151位氨基酸诱导的EAE模型中，dCK在淋巴结和脾脏中被激活，该模型由CD4 T和B细胞驱动，其特征为急性疾病后疾病缓解。用TRE-515治疗该模型可减轻临床症状，并降低活化的CD4 T和B细胞水平。在培养中，CD4 T和B细胞活化后诱导脱氧核糖核苷补救，而TRE-515直接阻断CD4 T和B细胞活化诱导的增殖和活化标志物表达。TRE-515减少脱氧胞苷三磷酸（dCTP）和脱氧胸苷三磷酸（dTTP）池，并增加细胞在细胞周期S期停留的时间，而不会在B细胞中诱导复制应激反应。我们的结果表明，在EAE小鼠模型中，针对自身抗原的淋巴细胞活化后，dCK活性对于提供所需的dNTPs和实现快速细胞分裂是必需的。
