Blood-derived amyloid-ß protein induces Alzheimer's disease pathologies.

The amyloid-ß protein (Aß) protein plays a pivotal role in the pathogenesis of Alzheimer's disease (AD). It is believed that Aß deposited in the brain originates from the brain tissue itself. However, Aß is generated in both brain and peripheral tissues. Whether circulating Aß contributes to brain AD-type pathologies remains largely unknown. In this study, using a model of parabiosis between APPswe/PS1dE9 transgenic AD mice and their wild-type littermates, we observed that the human Aß originated from transgenic AD model mice entered the circulation and accumulated in the brains of wild-type mice, and formed cerebral amyloid angiopathy and Aß plaques after a 12-month period of parabiosis. AD-type pathologies related to the Aß accumulation including tau hyperphosphorylation, neurodegeneration, neuroinflammation and microhemorrhage were found in the brains of the parabiotic wild-type mice. More importantly, hippocampal CA1 long-term potentiation was markedly impaired in parabiotic wild-type mice. To the best of our knowledge, our study is the first to reveal that blood-derived Aß can enter the brain, form the Aß-related pathologies and induce functional deficits of neurons. Our study provides novel insight into AD pathogenesis and provides evidence that supports the development of therapies for AD by targeting Aß metabolism in both the brain and the periphery.

Downregulation of serum DKK-1 predicts poor prognosis in patients with papillary thyroid cancer.

The Wnt inhibitor dickkopf-1 (DKK-1) has been shown to be closely correlated with tumor initiation and progression in various types of cancers. However, the serum level of DKK-1 in patients with papillary thyroid cancer (PTC) and its potential clinical significance is poorly understood. Enzyme-linked immunosorbent assay (ELISA) was used to evaluate the level of serum DKK-1 in patients with PTC (N = 132) and healthy controls (N = 40). The association between serum DKK-1 level and clinicopathological parameters of PTC was examined and independent prognostic markers for PTC were identified. The mean serum DKK-1 level was significantly lower in patients with PTC than healthy controls (44.64 ± 15.13 and 85.51 ± 9.94 ng/mL, respectively; P < 0.01). Following treatment, the mean serum DKK-1 level in PTC patients significantly increased (67.03 ± 17.09 ng/mL; P < 0.01). Serum DKK-1 level was associated with various PTC clinical features including tumor size (P = 0.003), lymph node metastasis (P = 0.001), and tumor-node-metastasis stage (P = 0.004). Survival analysis revealed that PTC patients who had lower serum DKK-1 levels suffered both poorer overall survival (P = 0.036) and relapse-free survival (P = 0.015). Moreover, serum DKK-1 levels were an independent risk factor for predicting the prognosis of PTC (P = 0.031). In conclusion, low DKK-1 serum levels are associated with poor prognosis in PTC patients and DKK-1 could potentially be used as a biomarker leading to earlier diagnosis of PTC.

N-methyl-D-aspartate receptor-dependent long-term potentiation in CA1 region affects synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus.

Long term potentiation in hippocampus, evoked by high-frequency stimulation, is mediated by two major glutamate receptor subtypes, alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptors and N-methyl-D-aspartate receptors. Receptor subunit composition and its interaction with cytoplasmic proteins constitute different pathways regulating synaptic plasticity. Here, we provide further evidence that N-methyl-D-aspartate receptor-mediated long term potentiation evoked at hippocampal CA1 region of rats induced by high-frequency stimulation of the Schaffer collateral-commissural pathway in vivo is not dependent on N-methyl-D-aspartate receptor subunit NR2B. Applying semi-quantitative immunoblotting, we found that in the whole tetanized hippocampus, synaptic expression of the N-methyl-D-aspartate and alpha-amino-3-hydroxyl-5-methyl-4-isoxazole propionate receptor subunits (NR1, NR2A, glutamate receptor 1) and their associated partners, e.g. synaptic associated protein 97, postsynaptic density protein 95, alpha subunit of Ca2+/calmodulin-dependent protein kinase II, neuronal nitricoxide synthase, increased 180 min post-high-frequency stimulation. Moreover, phosphorylation of Ca2+/calmodulin-dependent protein kinase II at thr286 and glutamate receptor 1 at ser831 was increased 30 min post-high-frequency stimulation and blocked by N-methyl-D-aspartate receptor antagonists (AP-5 and MK-801). In sham group and controls, these changes were not observed. The expression of several other synaptic proteins (NR2B, glutamate receptors 2/3, N-ethylmaleimide sensitive factor) was not affected by long term potentiation induction. In hippocampal homogenates, the level of these proteins remained unchanged. These data indicate that N-methyl-D-aspartate receptor-dependent long term potentiation in CA1 region in vivo mainly affects the synaptic expression of glutamate receptor subunits and associated proteins in the whole hippocampus. The alteration of molecular aspects can play a role in regulating the long-lasting synaptic modification in hippocampal long term potentiation in vivo.