Lundie Rachel J, Webb Lauren M, Marley Angela K, Phythian-Adams Alexander T, Cook Peter C, Jackson-Jones Lucy H, Brown Sheila, Maizels Rick M, Boon Louis, O'Keeffe Meredith, MacDonald Andrew S
Institute of Immunology and Infection Research, Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh, UK.
Centre for Biomedical Research, Burnet Institute, Melbourne, VIC, Australia.
Immunol Cell Biol. 2016 Apr;94(4):400-10. doi: 10.1038/icb.2015.114. Epub 2015 Dec 11.
Dendritic cells (DCs) are the key initiators of T-helper (Th) 2 immune responses against the parasitic helminth Schistosoma mansoni. Although the liver is one of the main sites of antigen deposition during infection with this parasite, it is not yet clear how distinct DC subtypes in this tissue respond to S. mansoni antigens in vivo, or how the liver microenvironment might influence DC function during establishment of the Th2 response. In this study, we show that hepatic DC subsets undergo distinct activation processes in vivo following murine infection with S. mansoni. Conventional DCs (cDCs) from schistosome-infected mice upregulated expression of the costimulatory molecule CD40 and were capable of priming naive CD4(+) T cells, whereas plasmacytoid DCs (pDCs) upregulated expression of MHC class II, CD86 and CD40 but were unable to support the expansion of either naive or effector/memory CD4(+) T cells. Importantly, in vivo depletion of pDCs revealed that this subset was dispensable for either maintenance or regulation of the hepatic Th2 effector response during acute S. mansoni infection. Our data provides strong evidence that S. mansoni infection favors the establishment of an immunogenic, rather than tolerogenic, liver microenvironment that conditions cDCs to initiate and maintain Th2 immunity in the context of ongoing antigen exposure.
树突状细胞(DCs)是针对寄生性蠕虫曼氏血吸虫的辅助性T细胞(Th)2免疫反应的关键启动者。尽管肝脏是感染这种寄生虫期间抗原沉积的主要部位之一,但尚不清楚该组织中不同的DC亚群在体内如何对曼氏血吸虫抗原作出反应,或者在Th2反应建立过程中肝脏微环境如何影响DC功能。在本研究中,我们表明,小鼠感染曼氏血吸虫后,肝脏DC亚群在体内经历不同的激活过程。来自血吸虫感染小鼠的常规DC(cDC)上调共刺激分子CD40的表达,并能够启动初始CD4(+) T细胞,而浆细胞样DC(pDC)上调MHC II类、CD86和CD40的表达,但无法支持初始或效应/记忆CD4(+) T细胞的扩增。重要的是,体内pDC的耗竭表明,在急性曼氏血吸虫感染期间,该亚群对于肝脏Th2效应反应的维持或调节是可有可无的。我们的数据提供了强有力的证据,表明曼氏血吸虫感染有利于建立一种免疫原性而非耐受性的肝脏微环境,这种微环境使cDC在持续抗原暴露的情况下启动并维持Th2免疫。