van Vliet Sandra J, den Dunnen Jeroen, Gringhuis Sonja I, Geijtenbeek Teunis Bh, van Kooyk Yvette
Department of Molecular Cell Biology and Immunology, VU University Medical Center, van der Boechorststraat 7, 1081BT Amsterdam, The Netherlands.
Curr Opin Immunol. 2007 Aug;19(4):435-40. doi: 10.1016/j.coi.2007.05.006. Epub 2007 Jul 12.
Dendritic cells are crucial in pathogen recognition and induction of specific immune responses to eliminate pathogens from the infected host. Host recognition of invading microorganisms relies on evolutionarily conserved, germline-encoded pattern-recognition receptors (PRRs) that are expressed by DCs. The best-characterized PRR family comprises the Toll-like receptors (TLRs) that recognize bacteria or viruses. In addition to TLRs, intracellular Nod-like receptors and the membrane-associated C-type lectins (CLRs) function as PRRs. Many of these innate receptors also have an important function in natural host homeostatic responses, such as the maintenance of gut homeostasis. Clearly, more indications are hinting at a fine-tuning of immune responses by a concerted action of these PRRs on the recognition of pathogen components and the consequent signalling events that are created. It is becoming increasingly clear that these PRRs can initiate specific signalling events that modulate the production of inflammatory cytokines, phagocytosis, intracellular routing of antigen, release of oxidative species and DC maturation and the subsequent development of adaptive immunity. Notably, members within one family of PRRs can trigger opposite signalling features, indicating that the ultimate outcome of pathogen-induced immune responses depends on the pathogen signature and the collective PRRs involved.
树突状细胞在病原体识别以及诱导特异性免疫反应以清除感染宿主中的病原体方面至关重要。宿主对入侵微生物的识别依赖于由树突状细胞表达的进化上保守的、种系编码的模式识别受体（PRR）。特征最明确的PRR家族包括识别细菌或病毒的Toll样受体（TLR）。除了TLR之外，细胞内Nod样受体和膜相关C型凝集素（CLR）也作为PRR发挥作用。许多这些固有受体在天然宿主稳态反应中也具有重要功能，例如维持肠道稳态。显然，越来越多的迹象表明这些PRR通过协同作用对病原体成分的识别以及由此产生的信号事件来微调免疫反应。越来越清楚的是，这些PRR可以启动特定的信号事件，从而调节炎性细胞因子的产生、吞噬作用、抗原的细胞内转运、活性氧的释放以及树突状细胞成熟和随后适应性免疫的发展。值得注意的是，一个PRR家族中的成员可以触发相反的信号特征，这表明病原体诱导的免疫反应的最终结果取决于病原体特征和所涉及的集体PRR。
