Langer Horvat Lea, Španić Popovački Ena, Babić Leko Mirjana, Zubčić Klara, Mustapić Maja, Hof Patrick R, Šimić Goran
Department of Neuroscience, Croatian Institute for Brain Research, University of Zagreb School of Medicine, Zagreb, 10000, Croatia.
Department of Medical Biology, University of Split Faculty of Science, Split, 21000, Croatia.
J Neural Transm (Vienna). 2025 Mar 17. doi: 10.1007/s00702-025-02909-z.
In this study, we further characterized a non-transgenic model of tauopathy by examining tau protein changes using ELISA and Western blot upon inoculation of human tau oligomers (TO) and human tau synthetic pre-formed fibrils (TF) into the medial entorhinal cortex of Wistar rats. Our analyses showed that inoculation with TO did not significantly alter the ratio of phosphorylated tau at AT8 epitopes (pSer202/pThr205) to total tau protein in the hippocampus and entorhinal cortex, but only resulted in a decrease of phosphorylation at AT100 epitopes (pThr212/pSer214). As we previously observed an increase in AT8 immunostaining in both regions, this suggests method-dependent conformational alterations. In contrast, eleven months after inoculation, TF caused significant AT8 and PHF-1 (pSer396/pSer404) epitope-specific changes in tau phosphorylation in the hippocampus, but not in the entorhinal cortex, reflecting a more advanced stage of Alzheimer's disease (AD)-like changes compared to TO. Importantly, amyloid plaques appeared as early as four months post-inoculation with TO, preceding significant phosphorylation changes of tau, thus indicating that amyloid probably facilitates early tau seeding and spreading. This was corroborated by the observed dynamic changes in Aβ levels in cerebrospinal fluid, with initial decreases followed by increases, similar to patterns seen in transgenic mouse models of AD and in AD patients. Altogether, these findings lead us to conclude that changes in tau protein induce amyloid changes and vice versa, which is actually what defines AD as a unique neurodegenerative disease.
在本研究中，我们通过将人tau寡聚体（TO）和人tau合成预形成纤维（TF）接种到Wistar大鼠的内侧内嗅皮质，利用酶联免疫吸附测定（ELISA）和蛋白质免疫印迹法检测tau蛋白变化，进一步对一种tau蛋白病的非转基因模型进行了特征描述。我们的分析表明，接种TO并未显著改变海马体和内嗅皮质中AT8表位（pSer202/pThr205）处磷酸化tau与总tau蛋白的比例，仅导致AT100表位（pThr212/pSer214）处磷酸化水平降低。正如我们之前观察到这两个区域的AT8免疫染色增加，这表明存在方法依赖性的构象改变。相比之下，接种后11个月，TF导致海马体中tau磷酸化出现显著的AT8和PHF-1（pSer396/pSer404）表位特异性变化，但在内嗅皮质中未出现，这反映出与TO相比，其阿尔茨海默病（AD）样变化处于更晚期阶段。重要的是，接种TO后早在4个月就出现了淀粉样斑块，早于tau的显著磷酸化变化，因此表明淀粉样蛋白可能促进了早期tau的播种和扩散。脑脊液中Aβ水平的动态变化也证实了这一点，最初下降随后上升，类似于AD转基因小鼠模型和AD患者中观察到的模式。总之，这些发现使我们得出结论，tau蛋白的变化会诱导淀粉样蛋白的变化，反之亦然，这实际上就是将AD定义为一种独特神经退行性疾病的原因。
