Faculty Bibliography

The present invention relates to synthetic immunogenic but non-amyloidogenic peptides homologous to amyloid beta which can be used alone or conjugated to an immunostimulatory molecule in an immunizing composition for inducing an immune response to amyloid beta peptides and amyloid deposits

The prion protein (PrP) binds copper and under some conditions copper can facilitate its folding into a more protease resistant form. Hence, copper levels may influence the infectivity of the scrapie form of prion protein (PrPSc). To determine the feasibility of copper-targeted therapy for prion disease, we treated mice with a copper chelator, D-(-)-penicillamine (D-PEN), starting immediately following intraperitoneal scrapie inoculation. D-PEN delayed the onset of prion disease in the mice by about 11 days (p = 0.002), and reduced copper levels in brain by 29% (p < 0.01) and in blood by 22% (p = 0.03) compared with control animals. Levels of other metals were not significantly altered in the blood or brain. Modest correlation was observed between incubation period and levels of copper in brain (p = 0.08) or blood (p = 0.04), indicating that copper levels are only one of many factors that influence the rate of progression of prion disease. In vitro, copper dose-dependently enhanced the proteinase K resistance of the prion protein, and this effect was counteracted in a dose-dependent manner by co-incubation with D-PEN. Overall, these findings indicate that copper levels can influence the conformational state of PrP, thereby enhancing its infectivity, and this effect can be attenuated by chelator-based therapy

The presence of amyloid-beta (Abeta) plaques in the brain is a hallmark pathological feature of Alzheimer's disease (AD). Transgenic mice overexpressing mutant amyloid precursor protein (APP), or both mutant APP and presenilin-1 (APP/PS1), develop Abeta plaques similar to those in AD patients, and have been proposed as animal models in which to test experimental therapeutic approaches for the clearance of Abeta. However, at present there is no in vivo whole-brain imaging method to detect Abeta plaques in mice or men. A novel method is presented to detect Abeta plaques in the brains of transgenic mice by magnetic resonance microimaging (muMRI). This method uses Abeta1-40 peptide, known for its high binding affinity to Abeta, magnetically labeled with either gadolinium (Gd) or monocrystalline iron oxide nanoparticles (MION). Intraarterial injection of magnetically labeled Abeta1-40, with mannitol to transiently open the blood-brain barrier (BBB), enabled the detection of many Abeta plaques. Furthermore, the numerical density of Abeta plaques detected by muMRI and by immunohistochemistry showed excellent correlation. This approach provides an in vivo method to detect Abeta in AD transgenic mice, and suggests that diagnostic MRI methods to detect Abeta in AD patients may ultimately be feasible

Signal abnormalities on magnetic resonance imaging (MRI) T2-weighted images (T2WI) have been described in patients with Creutzfeldt-Jakob disease; however, the pathology underlying these findings remains to be fully described. We investigated the time-course of signal alterations in a murine model of prion disease using in vivo 9.4 Tesla micro magnetic resonance imaging (muMRI). The topography of muMRI signal changes was correlated with the accumulation of proteinase resistant PrP(Sc) in corresponding brain sections. Increased signal intensity on T2WI was observed in the septum and in the hippocampus of presymptomatic mice 120 days post infection (dpi). Mildly symptomatic animals (150 dpi) and animals with apparent neurological deficit (180 dpi) had a greater increase of signal intensity on T2WI in the septum and the hippocampus; in addition, abnormalities in the cortex and in the thalamus were found. Neuropathological evaluation demonstrated accumulation of PrP(Sc) and astrogliosis but only minimal or no spongiform changes in structures where abnormal signal was detected. These observations suggest that early pathological changes related to the accumulation of PrP(Sc) may be detectable in presymptomatic subjects using MRI systems with higher magnetic field strength

When recombinant and cellular prion protein (PrP(C)) binds copper, it acquires properties resembling the scrapie isoform (PrP(Sc)), namely protease resistance, detergent insolubility and increased beta sheet content. However, whether the conformations of PrP(C) induced by copper and PrP(Sc) are similar has not been studied in great detail. Here, we use a panel of seven monoclonal antibodies to decipher the epitopes on full-length mouse PrP(C) that are affected by exogenous copper, and to compare the antigenicity of the copper-treated full-length PrP(C) with the full-length PrP(Sc) present in scrapie-infected mouse brains. In the presence of copper, we found that epitopes along residues 115-130 and 153-165 become more accessible on PrP(C). These regions correspond to the two beta sheet strands in recombinant PrP and they were proposed to be important for prion conversion. However, when we compared the antibody-binding patterns between full-length PrP(C) with full-length PrP(Sc) and between copper-treated full-length PrP(C) with full-length PrP(Sc), antibody binding to residues 143-155 and 175-185 was consistently increased on PrP(Sc). Collectively, our results suggest that copper-treated full-length PrP(C) does not resemble full-length PrP(Sc), despite acquiring PrP(Sc)-like properties. In addition, since each full-length protein reacts distinctively to some of the antibodies, this binding pattern could discriminate between PrP(C) and PrP(Sc).

Prion disease is characterized by a conformational change of the normal form of the prion protein (PrP(C)) to the scrapie-associated form (PrP(Sc)). Since the emergence of new variant Creutzfeldt-Jakob disease a potentially large human population is at risk for developing prion disease. Currently, no effective treatment or form of post-exposure prophylaxis is available for prion disease. We recently showed that active immunization with recombinant PrP prolongs the incubation period of scrapie. Here we show that anti-PrP antibodies following prion exposure are effective at increasing the incubation period of the infection. Stimulation of the immune system is an important therapeutic target for the prion diseases, as well as for other neurodegenerative illnesses characterized by abnormal protein conformation

Dendritic spines are postsynaptic sites of excitatory input in the mammalian nervous system. Apolipoprotein (apo) E participates in the transport of plasma lipids and in the redistribution of lipids among cells. A role for apoE is implicated in regeneration of synaptic circuitry after neural injury. The apoE4 allele is a major risk factor for late-onset familial and sporadic Alzheimer's disease (AD) and is associated with a poor outcome after brain injury. ApoE isoforms are suggested to have differential effects on neuronal repair mechanisms. In vitro studies have demonstrated the neurotrophic properties of apoE3 on neurite outgrowth. We have investigated the influence of apoE genotype on neuronal cell dendritic spine density in mice and in human postmortem tissue. In order to compare the morphology of neurons developing under different apoE conditions, gene gun labeling studies of dendritic spines of dentate gyrus (DG) granule cells of the hippocampus were carried out in wild-type (WT), human apoE3, human apoE4 expressing transgenic mice and apoE knockout (KO) mice; the same dendritic spine parameters were also assessed in human postmortem DG from individuals with and without the apoE4 gene. Quantitative analysis of dendritic spine length, morphology, and number was carried out on these mice at 3 weeks, 1 and 2 years of age. Human apoE3 and WT mice had a higher density of dendritic spines than human E4 and apoE KO mice in the 1 and 2 year age groups (P<0.0001), while at 3 weeks there were no differences between the groups. These age dependent differences in the effects of apoE isoforms on neuronal integrity may relate to the increased risk of dementia in aged individuals with the apoE4 allele. Significantly in human brain, apoE4 dose correlated inversely with dendritic spine density of DG neurons cell in the hippocampus of both AD (P=0.0008) and aged normal controls (P=0.0015). Our findings provide one potential explanation for the increased cognitive decline seen in aged and AD patients expressing apoE4