Institute of Viral Hepatitis, Key Laboratory of Molecular Biology for Infectious Diseases, Ministry of Education, Chongqing Medical University, Second Affiliated Hospital, Chongqing, China.
J Viral Hepat. 2013 Apr;20 Suppl 1:27-39. doi: 10.1111/jvh.12061.
α-Galactosylceramide (α-GalCer)-activated natural killer T (NKT) cells have antiviral properties against hepatitis B virus (HBV). However, α-GalCer activation of NKT cells can induce anergy. We hypothesized that this effect may be overcome by a treatment strategy that includes manipulation of CD28/CD80 costimulatory and PD-1/PDL1 coinhibitory signals of NKT cells, thereby enhancing the anti-HBV effect of α-GalCer. We established a transgenic mouse model of chronic HBV infection and investigated hepatic NKT cell frequencies, functions and expression of immunomodulatory factors. Our results showed that compared with uninfected control mice, hepatic NKT cells from HBV transgenic mice displayed lower frequencies (7.91% vs 16.74%, P < 0.05), impaired capabilities to produce interferon (IFN)-γ (5.6% vs 1.4%, P < 0.05) and interleukin (IL)-4 (6.8% vs 0.3%, P < 0.05), higher expression of PD-1 (9.64% vs 6.36%, P < 0.05) and lower expression of CD28 (5.05% vs 28.88%, P < 0.05). However, when hepatic mononuclear cells (MNCs) were isolated from HBV transgenic mice, α-GalCer exposure in culture remarkably upregulated both PD-1(+) NKT cells (P < 0.05) and CD28(+) NKT cells (P < 0.05). Furthermore, when HBV transgenic mice were treated with combination therapies consisting of α-GalCer and anti-PDL1 monoclonal antibody (mAb) and/or anti-CD80/anti-CD28 mAbs, IFN-γ(+) NKT cell frequency was selectively increased (P < 0.05) and HBV replication was suppressed; these effects were accompanied by varying degrees and types of liver damage. Surprisingly, activating CD28/CD80 signal in HBV transgenic mice was more effective but caused less liver injury than blocking PD-1/PDL1 signal in modulating αGalCer-activated NKT cell function to inhibit HBV infection. Our findings also show that combined therapy with blocking PD-1/PDL1 and activating CD28/CD80 signal in the presence of aGalCer cannot superimpose the effect of antivirus. α-GalCer combination therapy that modulates the CD28/CD80 pathways of NKT cells may represent a promising approach to inhibit HBV replication in chronically infected patients.
α-半乳糖神经酰胺（α-GalCer）激活的自然杀伤 T（NKT）细胞具有抗乙型肝炎病毒（HBV）的抗病毒特性。然而，α-GalCer 激活的 NKT 细胞可诱导失能。我们假设，通过操纵 NKT 细胞的 CD28/CD80 共刺激和 PD-1/PDL1 共抑制信号的治疗策略可以克服这种作用，从而增强 α-GalCer 的抗 HBV 作用。我们建立了慢性 HBV 感染的转基因小鼠模型，并研究了肝 NKT 细胞的频率、功能和免疫调节因子的表达。我们的结果表明，与未感染对照小鼠相比，HBV 转基因小鼠的肝 NKT 细胞频率较低（7.91%比 16.74%，P<0.05），产生干扰素（IFN）-γ（5.6%比 1.4%，P<0.05）和白细胞介素（IL）-4（6.8%比 0.3%，P<0.05）的能力受损，PD-1 的表达较高（9.64%比 6.36%，P<0.05），CD28 的表达较低（5.05%比 28.88%，P<0.05）。然而，当从 HBV 转基因小鼠分离肝单核细胞（MNC）时，α-GalCer 在培养中暴露可显著上调 PD-1（+）NKT 细胞（P<0.05）和 CD28（+）NKT 细胞（P<0.05）。此外，当用包含 α-GalCer 和抗 PDL1 单克隆抗体（mAb）和/或抗 CD80/抗 CD28 mAb 的联合疗法治疗 HBV 转基因小鼠时，IFN-γ（+）NKT 细胞频率选择性增加（P<0.05），HBV 复制受到抑制；这些作用伴有不同程度和类型的肝损伤。令人惊讶的是，在调节 αGalCer 激活的 NKT 细胞功能以抑制 HBV 感染时，激活 HBV 转基因小鼠的 CD28/CD80 信号比阻断 PD-1/PDL1 信号更有效但引起的肝损伤更小。我们的研究结果还表明，在 α-GalCer 存在的情况下，阻断 PD-1/PDL1 和激活 CD28/CD80 信号的联合治疗不能叠加抗病毒作用。调节 NKT 细胞的 CD28/CD80 途径的 α-GalCer 联合治疗可能代表抑制慢性感染患者 HBV 复制的一种有前途的方法。
