Induction of Ab Amyloidogenesis In Vivo by Blood Transfusion
Rodrigo Morales,1,† Claudia Duran-Aniotz,1, 2 Akihiko Urayama,1 Lisbell Estrada,3 Diego Morales-Scheihing1, 2 and Claudio Soto1
1University of Texas Health Science Center at Houston; Houston, TX USA; 2Universidad de Los Andes; Santiago, Chile; 3Universidad Catolica de Chile; Santiago, Chile†Presenting author; Email: Rodrigo.MoralesLoyola@uth.tmc.edu
Alzheimer disease (AD) is the most common type of senile dementia. Disease manifestation is characterized by progressive impairment of memory and cognition which is triggered by synaptic dysfunction and neuronal loss. Compelling evidence suggests that misfolding and aggregation of Ab is a hallmark event in the disease pathogenesis. An important unanswered question related to AD involves its etiology since over 90% of the AD cases arise sporadically. Interestingly, misfolding and aggregation of proteins is the main feature of other diseases -termed Protein Misfolding Disorders (PMDs)] which include Transmissible Spongiform Encephalopathies (TSEs), among others. Convincing experimental evidences have shown that the only component of the infectious agent in TSEs is the misfolded form of the prion protein. Strikingly, the molecular mechanisms responsible for prion replication are very similar to the process of amyloid formation in all PMDs, suggesting that all these diseases have the inherent capability of being transmissible. Recent reports have shown that intra-cerebral and intra-peritoneal administration of brain homogenates containing Ab aggregates can accelerate the generation of senile plaques in mice models of AD. However, it remains to be demonstrated if this phenomenon can occur by more relevant routes of administration. The aim of this study was to assess whether AD pathogenesis can be induced intravenously, mimicking the know transmission of prion diseases through blood transfusion. For this purpose we used young tg2576 mice which were injected with blood obtained from 12 months old tg2576 mice (AD-blood) that contains a substantial quantity of cerebral Ab deposits. Mice were sacrificed at 250 days old, a time in which these animals scarcely develop Ab deposits. Interestingly, we observed that infusion of AD-blood induces substantial Ab accumulation in animals that without treatment or injected with wild type blood would barely have any detectable Ab lesion. Plaque deposition was mainly present in cortex and hippocampus, being more abundant in the former. In addition, we observed a decrease in memory in mice challenged with AD-blood. Other features such as brain inflammation and synaptic integrity were also measured. Importantly, similar results were obtained in a second and independent experiment performed in a double transgenic mouse model that develops AD plaques as early as 4 months old. Our results indicate that an AD-like pathogenesis can be induced by intravenous administration of AD-blood, presumably through induction of protein misfolding in a similar way as prion diseases. These findings may open a new avenue to understand the origin of sporadic AD and may provide new strategies for disease intervention and prevention.
Wednesday, June 29, 2011
TSEAC Meeting August 1, 2011 donor deferral