Department of Molecular, Cellular and Biomedical Sciences, City University of New York School of Medicine, New York, NY 10031, USA.
Department of Biology and Neuroscience, Graduate School, City University of New York, New York, NY 10016, USA.
Int J Mol Sci. 2023 Sep 11;24(18):13927. doi: 10.3390/ijms241813927.
Simufilam is a novel oral drug candidate in Phase 3 clinical trials for Alzheimer's disease (AD) dementia. This small molecule binds an altered form of filamin A (FLNA) that occurs in AD. This drug action disrupts FLNA's aberrant linkage to the α7 nicotinic acetylcholine receptor (α7nAChR), thereby blocking soluble amyloid beta (Aβ)'s signaling via α7nAChR that hyperphosphorylates tau. Here, we aimed to clarify simufilam's mechanism. We now show that simufilam reduced Aβ binding to α7nAChR with a 10-picomolar IC using time-resolved fluorescence resonance energy transfer (TR-FRET), a robust technology to detect highly sensitive molecular interactions. We also show that FLNA links to multiple inflammatory receptors in addition to Toll-like receptor 4 (TLR4) in postmortem human AD brains and in AD transgenic mice: TLR2, C-X-C chemokine receptor type 4 (CXCR4), C-C chemokine receptor type 5 (CCR5), and T-cell co-receptor cluster of differentiation 4 (CD4). These aberrant FLNA linkages, which can be induced in a healthy control brain by Aβ incubation, were disrupted by simufilam. Simufilam reduced inflammatory cytokine release from Aβ-stimulated human astrocytes. In the AD transgenic mice, CCR5-G protein coupling was elevated, indicating persistent activation. Oral simufilam reduced both the FLNA-CCR5 linkage and the CCR5-G protein coupling in these mice, while restoring CCR5's responsivity to C-C chemokine ligand 3 (CCL3). By disrupting aberrant FLNA-receptor interactions critical to AD pathogenic pathways, simufilam may promote brain health.
西美法仑是一种新型的用于治疗阿尔茨海默病（AD）痴呆的 3 期临床试验的口服药物候选物。这种小分子结合了在 AD 中发生的异常形式的细丝蛋白 A（FLNA）。该药物作用破坏了 FLNA 与α7 烟碱型乙酰胆碱受体（α7nAChR）的异常连接，从而阻断可溶性淀粉样β（Aβ）通过α7nAChR 对 tau 的过度磷酸化的信号传递。在这里，我们旨在阐明西美法仑的作用机制。我们现在表明，西美法仑使用时间分辨荧光共振能量转移（TR-FRET）降低了 Aβ 与α7nAChR 的结合，TR-FRET 是一种检测高度敏感分子相互作用的强大技术。我们还表明，FLNA 除了在死后 AD 大脑和 AD 转基因小鼠中与 Toll 样受体 4（TLR4）外，还与多种炎症受体连接：TLR2、C-X-C 趋化因子受体 4（CXCR4）、C-C 趋化因子受体 5（CCR5）和 T 细胞共受体分化群 4（CD4）。这些异常的 FLNA 连接，在 Aβ 孵育后可以在健康对照大脑中诱导，被西美法仑破坏。西美法仑减少了 Aβ 刺激的人星形胶质细胞中炎症细胞因子的释放。在 AD 转基因小鼠中，CCR5-G 蛋白偶联被上调，表明持续激活。口服西美法仑降低了这些小鼠中的 FLNA-CCR5 连接和 CCR5-G 蛋白偶联，同时恢复了 CCR5 对 C-C 趋化因子配体 3（CCL3）的反应性。通过破坏 AD 致病途径中至关重要的异常 FLNA-受体相互作用，西美法仑可能促进大脑健康。
