Faculty Bibliography

Background: Immunomodulation has shown great promise as an Alzheimer's disease (AD) therapy but major limitations must be overcome, such as the need for effectively reducing cerebral amyloid angiopathy (CAA), without associated hemorrhages. CAA is a common feature in AD and cognitively normal elderly individuals. Our initial findings indicate that stimulation of innate immunity with CpG ODN appears to be an effective means of reducing vascular amyloid without inducing toxicity in AD mouse models. We are currently testing our approach in a well characterized nonhuman primate model of sporadic CAA, squirrel monkey (Saimiri Boliviensis), which share numerous biological similarities with humans. Methods: Varying doses of the class B CpG ODN preparation containing the primate specific immunostimulatory sequence were administered in young monkeys by a subcutaneous route (s.c.). The most effective and non-toxic dosage described in young animals was selected for our long term studies in the older animals (with expected CAA deposits). During the treatment, primates were closely monitored for signs of toxicity. The peripheral cytokine responses were determined in PBMC supernatants and plasma from control and treated monkeys at selected time points. In addition, the performances on cognitive tests are being compared between our aged and young squirrel monkeys. Results: We have shown that a TLR9 agonist prevented shortterm memory deficits in Tg-SwDI mice, a model with extensive CAA. CpG ODN treatment led to a reduction of CAA in the absence of microhemorrhages and increased inflammation. Transgenic models are ideal for initial screening of a potential therapy but prior to clinical trials it is imperative to perform studies in non-human primates, which are a more biologically proximate model to humans. Short duration safety and efficacy assessment studies were first performed in young monkeys. Characterization of immune responses and evaluation of cognitive function and working memory in our monkeys is curr!

Background: Atrophy of the hippocampus is a key pathological hallmark of Alzheimer's disease (AD). An interest of subfields of hippocampal imaging has emerged in recent years due to the advent of ultra-high field MR. This work was to evaluate the imaging parameters on human postmortem brain at 7T MR using 3D susceptibility-sensitivity imaging (SWI) with enhanced tissue susceptibility contrast to better identify these layers and hippocampal subfields that are not available on conventional MR in order to better understand the transition of the hippocampus in AD as disease progresses. Methods: Imaging was performed on a 7.0T Siemens MAGNETOM using a 24-element phased array head coil. Post-mortem brain specimens of the hippocampus were obtained from 3 patients (mean: 72.2+4.3 years) with clinically diagnosed AD and 4 age-matched healthy controls (71.4+5.2 years). Coronal brain slices were preserved and fixed in 2% agar for this study. High resolution 3D SWI was obtained with isotropic voxel size 150~320mum. For imaging optimization to better visualize amyloid plaques, we varied TR, TE, BWand flip angle from 30-100ms, 12-36ms, 60-140Hz/ pixel and 10-40degree; respectively. The SWI filtered phase images were used (multiplication factor of 4 ~ 8) to enhance susceptibility contrast in the SWI images. Results: With optimal SWI parameters TR/TE/FA of 80ms/ 20ms/30IS at 7T, Figure 1 exemplifies the excellent image contrast for visualization of hippocampal layers (Fig A) and subfields (Fig B) in an elderly post-mortem brain without AD, specifically for cell types/layers: (1) Alveus; (2) Stratum Oriens; (3) Stratum Pyramidale; (4) Stratum Radiatum; (5) Stratum Lacunosum; (6) Stratum Moleculare; and for Hippocampal Formation subfields: (1) Hippocampal Head; (2, 2') Dentate Gyrus, (3, 3') Cornu Ammonis (CA1), (4) CA2, (5) CA3, (6) Pre-Subiculum/ Subiculum, (7) Para-Subiculum, (8) Entorhinal Cortex. There was significant atrophy of the whole hippocampal formation and subfields inADsamples with lessening of the!

HIV-ITP patients have a unique antibody (Ab) against platelet GPIIIa49-66 which induces oxidative platelet fragmentation in the absence of complement (Cell 106: 551, 2001; JCI 113: 973, 2004). The search for a physiologic ligand that could induce this reaction was undertaken by panning the GPIIIa49-66 peptide with a phage surface display 7-mer peptide library. From 20 positive clones, 1 had 70% identity with a C-terminal region of ADAMTS-18 (a disintegrin and metalloproteinase with thrombospondin (TSR)-like motif 18), which is secreted by endothelial cell (EC). The recombinant C-terminal fragment of ADAMTS-18 can completely dissolve platelet aggregates formed in vitro. Moreover, this fragment lyses thrombi formed in the cerebral artery of mice and reduces infarction and neurologic impairment in murine ischemic stroke model (Blood 113: 6051, 2009). However, whether ADAMTS-18 represents the dominant physiologic mechanism controlling thrombus dissolution in vivo remains to be clarified. Here, we used ADAMTS-18-deficient (ADAMTS-18^-/-) mice to study the contributions of ADAMTS-18 to thrombus formation in vivo. To investigate possible functional differences between WT and ADAMTS-18^-/- platelets, we tested WT and ADAMTS-18^-/- platelets in a model of pulmonary thromboembolism induced by infusion of a mixture of platelet agonist collagen (25 mug per mouse) and epinephrine (1 mug per mouse). In lung tissue Hematoxylin and eosin-stained (HE) slides, the mean number of thrombi per lung was same in the ADAMTS-18^-/- group compared with WT group (163.7 +/-14.38 vs 174.9 +/-11.73, n=30/group, P=0.5480). In vitro, there is no difference between WT and ADAMTS-18^-/- platelet aggregation trace and activation initiated by various platelet agonists ADP (10 muM) or collagen (2 mug/mL). No difference was noted on WT and ADAMTS-18^-/- platelet adhesion on immobilized ligand (fibrinogen). These results indicated ADAMTS-18 had no effect on platelet functio!

BACKGROUND: Central to the pathogenesis of Alzheimer's disease (AD) and many other neurodegenerative diseases is the conformational change of a normal self-protein into toxic oligomeric species and amyloid deposits. None of these disorders have an effective therapy, but immunization approaches hold great promise. We have previously shown that active immunization with a novel peptide when polymerized into a stable oligomeric conformation, pBri, induced a humoral immune response to toxic Abeta species in an AD model, APP/PS1 transgenic (Tg) mice, reducing plaque deposits. pBri is a glutaraldehyde polymerized form of the carboxyl fragment of an amyloidogenic protein, which is deposited in the brains of patients with a rare autosomal dominant disease due to a missense mutation in a stop codon, resulting in the translation of an intronic sequence, with no known sequence homology to any mammalian protein. METHODS: In the current study we tested whether pBri-peptide-based immunomodulation is effective at reducing both vascular amyloid deposits and tau-related pathology using TgSwDI mice with extensive congophilic angiopathy and 3xTg mice with tau pathology. RESULTS: Our results indicate that this immunomodulation approach, which produces a humoral response to proteins in a pathological conformation, is effective at reducing both Abeta and tau-related pathologies. CONCLUSIONS: This immunomodulatory approach has the advantage of using a non-self-immunogen that is less likely to be associated with autoimmune toxicity. Furthermore we found that it is able to target all the cardinal features of AD concurrently.

Alzheimer's disease (AD) is the leading cause for dementia in the world. It is characterized by two biochemically distinct types of protein aggregates: amyloid beta (A beta ) peptide in the forms of parenchymal amyloid plaques and congophilic amyloid angiopathy (CAA) and aggregated tau protein in the form of intraneuronal neurofibrillary tangles (NFT). Several risk factors have been discovered that are associated with AD. The most well-known genetic risk factor for late-onset AD is apolipoprotein E4 (ApoE4) (Potter and Wisniewski (2012), and Verghese et al. (2011)). Recently, it has been reported by two groups independently that a rare functional variant (R47H) of TREM2 is associated with the late-onset risk of AD. TREM2 is expressed on myeloid cells including microglia, macrophages, and dendritic cells, as well as osteoclasts. Microglia are a major part of the innate immune system in the CNS and are also involved in stimulating adaptive immunity. Microglia express several Toll-like receptors (TLRs) and are the resident macrophages of the central nervous system (CNS). In this review, we will focus on the recent advances regarding the role of TREM2, as well as the effects of TLRs 4 and 9 on AD.

Soluble amyloid-beta oligomers (Abetao) trigger Alzheimer's disease (AD) pathophysiology and bind with high affinity to cellular prion protein (PrP(C)). At the postsynaptic density (PSD), extracellular Abetao bound to lipid-anchored PrP(C) activates intracellular Fyn kinase to disrupt synapses. Here, we screened transmembrane PSD proteins heterologously for the ability to couple Abetao-PrP(C) with Fyn. Only coexpression of the metabotropic glutamate receptor, mGluR5, allowed PrP(C)-bound Abetao to activate Fyn. PrP(C) and mGluR5 interact physically, and cytoplasmic Fyn forms a complex with mGluR5. Abetao-PrP(C) generates mGluR5-mediated increases of intracellular calcium in Xenopus oocytes and in neurons, and the latter is also driven by human AD brain extracts. In addition, signaling by Abetao-PrP(C)-mGluR5 complexes mediates eEF2 phosphorylation and dendritic spine loss. For mice expressing familial AD transgenes, mGluR5 antagonism reverses deficits in learning, memory, and synapse density. Thus, Abetao-PrP(C) complexes at the neuronal surface activate mGluR5 to disrupt neuronal function.

The relationship between the apolipoprotein E (ApoE) epsilon4 genotype and an increased risk of developing Alzheimer's disease (AD) has been well established in Caucasians but is less established among other ethnicities. ApoE epsilon4 has also been associated with several other neurological disorders. Whether ApoEpsilon4 epsilon4 is a risk factor for frontotemporal dementia (FTD) remains controversial. This study examined 432 patients with AD, 62 with FTD, and 381 sex- and age-matched controls. The ApoE epsilon4 allele frequency was significantly increased among patients in the AD and FTD groups compared with controls. The frequency of the ApoEpsilon epsilon4 allele was 24.86% in late-onset AD (p < 0.01), 18.02% in early-onset AD (p < 0.01), 16.13% in FTD (p < 0.01), and 7.34% in controls. ApoEpsilon epsilon4 prevalence was similar in the FTD and AD groups. The present study suggests that the ApoE epsilon4 allele is a risk factor for both disorders. (c) 2013 S. Karger AG, Basel.