Kaplan David E
UNIVERSITY OF PENNSYLVANIA; CORPORAL MICHAEL J. CRESCENZ VA MEDICAL CENTER.
Blood. 2017 Jul 6;130(1):4. doi: 10.1182/blood-2017-05-786368.
In this issue of Del Padre et al evaluated the impact of eliminating chronic antigen exposure on B-cell exhaustion in the human therapeutic setting of direct-acting antiviral therapy for chronic hepatitis C virus infection (HCV) complicated by mixed cryoglobulinemia (MC). The phenotype of hepatitis C–related MC B cells has been previously demonstrated by this group and others to include low-level CD21 expression (CD21) and hypoproliferation in response to stimulation either through the B-cell receptor or Toll-like receptor 9, imperfectly termed “exhausted” or “anergic.” At baseline, CD21 B cells from HCV-infected patients expressed markers of chronic activation, with elevated and near-maximal basal levels of phosphorylated extracellular signal–regulated kinase, and were also predisposed to apoptosis. During oral direct-acting antiviral therapy, the authors observed that by 4 weeks (at which point, most patients have no circulating HCV RNA), these basal abnormalities at least partially normalized. During longitudinal follow-up after patients were documented as cured, the overall frequency of CD21 cells progressively declined from 50% to 30% of circulating B cells. However, the frequency of V1-69 B cells specific for HCV-related MC generally remained stable, although some regained CD21 expression. Despite partial resolution of the exhaustion phenotype, surviving V1-69 B cells remained hypoproliferative upon Toll-like receptor 9 ligation, suggesting that the B-cell exhaustion phenotype is durably programmed into antigen-specific B cells during long-term extracellular antigen exposure.
在本期杂志中,德尔·帕德雷等人评估了在慢性丙型肝炎病毒感染(HCV)合并混合性冷球蛋白血症(MC)的人类治疗环境中,消除慢性抗原暴露对B细胞耗竭的影响。该研究团队及其他团队先前已证明,丙型肝炎相关MC B细胞的表型包括低水平的CD21表达(CD21)以及对通过B细胞受体或Toll样受体9刺激的增殖低下,这种情况被不确切地称为“耗竭”或“无反应性”。基线时,HCV感染患者的CD21 B细胞表达慢性激活标志物,磷酸化细胞外信号调节激酶水平升高且接近最大基础水平,并且还易于发生凋亡。在口服直接抗病毒治疗期间,作者观察到,到4周时(此时大多数患者已无循环HCV RNA),这些基础异常至少部分恢复正常。在患者被记录为治愈后的纵向随访期间,CD21细胞的总体频率从循环B细胞的50%逐渐下降至30%。然而,与HCV相关MC特异性的V1-69 B细胞频率总体上保持稳定,尽管一些细胞恢复了CD21表达。尽管耗竭表型部分得到缓解,但存活的V1-69 B细胞在Toll样受体9连接后仍增殖低下,这表明在长期细胞外抗原暴露期间,B细胞耗竭表型被持久地编程到抗原特异性B细胞中。