Department of Neurology, Affiliated Hospital of Xuzhou Medical University, China; Institute of Neurological Diseases, Xuzhou Medical University, China.
Department of Histology and Embryology, Shenyang Medical College, China.
Brain Behav Immun. 2021 Jan;91:257-266. doi: 10.1016/j.bbi.2020.10.004. Epub 2020 Oct 16.
Toll-like receptor-2 (TLR2), a member of TLR family, plays an important role in the induction and regulation of immune/inflammation. TLR2 gene knockout (TLR2KO) mice have been widely used for animal models of neurological diseases. Since there is close relationship between immune system and neurobehavioral functions, it is important to clarify the exact role of TLR2 defect itself in neurobehavioral functions. The present study aimed to investigate the effect of TLR2KO on neurobehavioral functions in mice and the mechanisms underlying the observed changes.
Male TLR2KO and wild type (WT) mice aged 3, 7, and 12 months were used for neurobehavioral testing and detection of protein expression by Western blot. Brain magnetic resonance imaging (MRI), electrophysiological recording, and Evans blue (EB) assay were applied to evaluate regional cerebral blood flow (rCBF), synaptic function, and blood-brain barrier (BBB) integrity in 12-month-old TLR2KO and age-matched WT mice.
Compared to WT mice, TLR2KO mice showed decreased cognitive function and locomotor activity, as well as increased anxiety, which developed from middle age (before 7-month-old) to old age. In addition, significantly reduced regional cerebral blood flow (rCBF), inhibited long-term potentiation (LTP), and increased blood-brain barrier (BBB) permeability were observed in 12-month-old TLR2KO mice. Furthermore, compared with age-matched WT mice, significant reduction in protein levels of tight junction proteins (ZO-1, Occludin, and Claudin-5) and increased neurofilament protein (SMI32) were observed in 7 and 12-month-old TLR2KO mice, and that myelin basic protein (MBP) decreased in 12-month-old TLR2KO mice.
Our data demonstrated that TLR2 defect resulted in significantly observable neurobehavioral dysfunctions in mice starting from middle age, as well as multiple abnormalities in brain structure, function, and molecular metabolism.
Toll 样受体-2（TLR2）是 TLR 家族的成员，在免疫/炎症的诱导和调节中发挥重要作用。TLR2 基因敲除（TLR2KO）小鼠已广泛用于神经疾病的动物模型。由于免疫系统与神经行为功能密切相关，因此阐明 TLR2 缺陷本身对神经行为功能的确切作用非常重要。本研究旨在探讨 TLR2KO 对小鼠神经行为功能的影响及其观察到的变化的机制。
使用 3、7 和 12 个月龄的 TLR2KO 和野生型（WT）雄性小鼠进行神经行为测试和 Western blot 检测蛋白表达。脑磁共振成像（MRI）、电生理记录和 Evans 蓝（EB）测定用于评估 12 月龄 TLR2KO 和年龄匹配的 WT 小鼠的局部脑血流（rCBF）、突触功能和血脑屏障（BBB）完整性。
与 WT 小鼠相比，TLR2KO 小鼠表现出认知功能和运动活性降低，以及焦虑增加，从中年（7 个月龄前）到老年逐渐发展。此外，在 12 月龄的 TLR2KO 小鼠中观察到明显减少的局部脑血流（rCBF）、抑制长时程增强（LTP）和增加血脑屏障（BBB）通透性。此外，与年龄匹配的 WT 小鼠相比，在 7 和 12 月龄的 TLR2KO 小鼠中观察到紧密连接蛋白（ZO-1、Occludin 和 Claudin-5）的蛋白水平明显降低，神经丝蛋白（SMI32）增加，并且在 12 月龄的 TLR2KO 小鼠中髓鞘碱性蛋白（MBP）减少。
我们的数据表明，TLR2 缺陷导致小鼠从中年开始出现明显可观察到的神经行为功能障碍，以及大脑结构、功能和分子代谢的多种异常。
