Jo Juandy, Tan Anthony T, Ussher James E, Sandalova Elena, Tang Xin-Zi, Tan-Garcia Alfonso, To Natalie, Hong Michelle, Chia Adeline, Gill Upkar S, Kennedy Patrick T, Tan Kai Chah, Lee Kang Hoe, De Libero Gennaro, Gehring Adam J, Willberg Christian B, Klenerman Paul, Bertoletti Antonio
Viral Hepatitis Laboratory, Singapore Institute for Clinical Sciences, Agency of Science Technology and Research (A*STAR), Singapore.
Program Emerging Infectious Diseases, Duke-NUS Graduate Medical School, Singapore.
PLoS Pathog. 2014 Jun 26;10(6):e1004210. doi: 10.1371/journal.ppat.1004210. eCollection 2014 Jun.
The ability of innate immune cells to sense and respond to impending danger varies by anatomical location. The liver is considered tolerogenic but is still capable of mounting a successful immune response to clear various infections. To understand whether hepatic immune cells tune their response to different infectious challenges, we probed mononuclear cells purified from human healthy and diseased livers with distinct pathogen-associated molecules. We discovered that only the TLR8 agonist ssRNA40 selectively activated liver-resident innate immune cells to produce substantial quantities of IFN-γ. We identified CD161(Bright) mucosal-associated invariant T (MAIT) and CD56(Bright) NK cells as the responding liver-resident innate immune cells. Their activation was not directly induced by the TLR8 agonist but was dependent on IL-12 and IL-18 production by ssRNA40-activated intrahepatic monocytes. Importantly, the ssRNA40-induced cytokine-dependent activation of MAIT cells mirrored responses induced by bacteria, i.e., generating a selective production of high levels of IFN-γ, without the concomitant production of TNF-α or IL-17A. The intrahepatic IFN-γ production could be detected not only in healthy livers, but also in HBV- or HCV-infected livers. In conclusion, the human liver harbors a network of immune cells able to modulate their immunological responses to different pathogen-associated molecules. Their ability to generate a strong production of IFN-γ upon stimulation with TLR8 agonist opens new therapeutic opportunities for the treatment of diverse liver pathologies.
先天性免疫细胞感知并应对即将到来的危险的能力因解剖位置而异。肝脏被认为具有免疫耐受性,但仍能够发起成功的免疫反应以清除各种感染。为了解肝脏免疫细胞是否会调整其对不同感染挑战的反应,我们用不同的病原体相关分子探测了从人类健康和患病肝脏中纯化出的单核细胞。我们发现,只有TLR8激动剂ssRNA40能选择性地激活肝脏驻留的先天性免疫细胞,使其产生大量的IFN-γ。我们确定CD161(Bright)黏膜相关恒定T细胞(MAIT)和CD56(Bright)自然杀伤细胞为做出反应的肝脏驻留先天性免疫细胞。它们的激活不是由TLR8激动剂直接诱导的,而是依赖于ssRNA40激活的肝内单核细胞产生的IL-12和IL-18。重要的是,ssRNA40诱导的MAIT细胞的细胞因子依赖性激活反映了细菌诱导的反应,即产生高水平IFN-γ的选择性分泌,而不伴随TNF-α或IL-17A的分泌。肝内IFN-γ的产生不仅在健康肝脏中可以检测到,在乙肝或丙肝感染的肝脏中也能检测到。总之,人类肝脏拥有一个免疫细胞网络,能够调节其对不同病原体相关分子的免疫反应。它们在用TLR8激动剂刺激后产生大量IFN-γ的能力为治疗各种肝脏疾病开辟了新的治疗机会。