Beta-amyloid(Aβ)-induced inflammation plays a critical role in the pathogenesis of Alzheimer’s disease (AD). Nod-like receptor nucleotide-binding domain leucine rich repeat containing protein 3 (NLRP3) inflammasome is involved in the Aβ-induced inflammation. However, the mechanisms by which extracellular Aβ activates cytoplasmic NLRP3 inflammasome are poorly understood. Toll-like receptor 4(TLR4) acts as a sensor of Aβ and performs a key role in neuroinflammation. TLR4 is involved in activating the NLRP3 inflammasome in several diseases. In this study, the interaction between TLR4 and NLRP3 inflammasome in Aβ₁₋₄₂-induced neuroinflammation was investigated. BV-2 microglia and primary microglia were primed with lipopolysaccharide (LPS) and then pretreated with TLR4 inhibitor CLI-095, followed by stimulation with Aβ_1–42. The protein expression of NLRP3, the adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC), and caspase-1 p 10 was detected by western blotting and immunostaining. The mRNA expression of inflammatory factors was measured by real-time PCR. The protein level of pro IL-1β and IL-1β was examined by ELISA. Activated microglia were examined by immunofluorescence staining for ionized calcium-binding adapter molecule-1 (Iba-1). Conditioned medium of BV-2 cells was collected to challenge HT-22 neurons. Cell viability was assessed with MTT assay. Assessment of HT-22 cell apoptosis was performed by Annexin V/PI staining and western blotting to detect the protein level of cleaved caspase 3. The results showed that Aβ₁₋₄₂ activated and up-regulated the expression of NLRP3 inflammasome in BV-2 microglia, as indicated by increased activation of caspase-1 and secretion of IL-1β. Pharmacological inhibition of TLR4 by CLI-095 abolished Aβ₁₋₄₂-induced NLRP3 inflammasome activation, which curbed the development of inflammation and exerted protective effect on HT-22 neurons. Furthermore, the inhibitory effects of CLI-095 on Aβ₁₋₄₂-induced inflammation were reversed by NLRP3 activator ATP. Overall, our findings suggested TLR4 mediated Aβ₁₋₄₂-induced NLRP3 inflammasome activation in mouse microglia. TLR4/NLRP3 pathway plays a critical role in Aβ₁₋₄₂-induced neuroinflammation.

β淀粉样蛋白（Aβ）诱导的炎症在阿尔茨海默氏病（AD）的发病机理中起着关键作用。含有蛋白3（NLRP3）的炎性小体的Nod样受体核苷酸结合结构域富含亮氨酸重复序列与Aβ诱导的炎症有关。然而，人们对细胞外Aβ激活细胞质NLRP3炎性小体的机制了解甚少。Toll样受体4（TLR4）充当Aβ的传感器，并在神经炎症中起关键作用。TLR4与几种疾病中的NLRP3γ体活化有关。在这项研究中，TLR4和NLRP3炎性小体在_Aβ1-42之间的相互作用对诱发的神经炎症进行了研究。BV-2小胶质细胞和原发性小胶质细胞用脂多糖（LPS）灌注，然后用TLR4抑制剂CLI-095预处理，然后用_Aβ1–42刺激。通过western印迹和免疫染色检测到NLRP3的蛋白表达，与CARD衔接蛋白凋亡相关的斑点样蛋白（ASC）和caspase-1 p 10的表达。通过实时PCR测量炎性因子的mRNA表达。通过ELISA检测前IL-1β和IL-1β的蛋白水平。激活的小胶质细胞通过免疫荧光染色检查了离子钙结合衔接子分子1（Iba-1）。收集BV-2细胞的条件培养基以攻击HT-22神经元。用MTT测定法评估细胞活力。通过膜联蛋白V / PI染色和Western印迹法评估HT-22细胞凋亡，以检测裂解的胱天蛋白酶3的蛋白水平。结果显示，_Aβ1–42激活并上调BV-2小胶质细胞中NLRP3炎性小体的表达，这可通过caspase-1激活的增强和IL-1β的分泌来表明。CLI-095对TLR4的药理抑制作用取消了_Aβ1–42诱导的NLRP3炎性小体活化，从而抑制了炎症的发展并对HT-22神经元产生了保护作用。此外，NLRP3激活剂ATP逆转了CLI-095对_Aβ1–42诱导的炎症的抑制作用。总体而言，我们的发现表明，TLR4介导了小鼠小胶质细胞中_Aβ1–42诱导的NLRP3炎性小体激活。TLR4 / NLRP3途径在_Aβ1–42诱导的神经炎症中起关键作用。