Beesu Mallesh, Salyer Alex C D, Brush Michael J H, Trautman Kathryn L, Hill Justin K, David Sunil A
Department of Medicinal Chemistry, University of Minnesota , Sixth Street SE, Minneapolis, Minnesota 55455, United States.
J Med Chem. 2017 Mar 9;60(5):2084-2098. doi: 10.1021/acs.jmedchem.6b01860. Epub 2017 Feb 15.
The induction of toll-like receptor 7 (TLR7)-dependent type I interferons (IFN-α/β) from plasmacytoid dendritic cells as well as the production of TLR8-dependent type II interferon (IFN-γ), TNF-α, and IL-12 in myeloid dendritic cells are of importance in generating T helper-1 biased adaptive immune responses. In an effort to identify novel dual TLR7/TLR8-active compounds, we undertook structure-activity relationship studies in pyrimidine 2,4-diamines, focusing on substituents at C5. Several analogues substituted with aminopropyl appendages at C5 displayed dominant TLR8-agonistic activity. N-Butyl-6-methyl-5-(3-morpholinopropyl)pyrimidine-2,4-diamine was found to be a very potent dual TLR7/TLR8 agonist. Employing novel cytokine reporter cell assays, we verified that potency at TLR7 correlates with IFN-α/β production in human blood, whereas IFN-γ and TNF-α induction is largely TLR8-dependent. Dual TLR7/TLR8 agonists markedly upregulate CD80 expression in multiple dendritic cell subsets, providing insight into the immunological basis for the superior adjuvantic properties of such innate immune stimuli.
浆细胞样树突状细胞诱导依赖Toll样受体7（TLR7）的I型干扰素（IFN-α/β）以及髓样树突状细胞中产生依赖TLR8的II型干扰素（IFN-γ）、肿瘤坏死因子-α（TNF-α）和白细胞介素-12（IL-12）对于产生偏向于辅助性T细胞1的适应性免疫反应至关重要。为了鉴定新型的双TLR7/TLR8活性化合物，我们对嘧啶2,4-二胺进行了构效关系研究，重点关注C5位的取代基。几种在C5位被氨丙基取代的类似物表现出主要的TLR8激动活性。发现N-丁基-6-甲基-5-(3-吗啉丙基)嘧啶-2,4-二胺是一种非常有效的双TLR7/TLR8激动剂。采用新型细胞因子报告细胞检测法，我们证实了在TLR7上的活性与人体血液中IFN-α/β的产生相关，而IFN-γ和TNF-α的诱导在很大程度上依赖TLR8。双TLR7/TLR8激动剂显著上调多个树突状细胞亚群中CD80的表达，为这种先天免疫刺激剂卓越的佐剂特性的免疫学基础提供了深入了解。
