Drew DeBay

In Vivo Detection of Human TRPV6-Rich Tumors with Anti-Cancer Peptides Derived from Soricidin

Soricidin is a 54-amino acid peptide found in the paralytic venom of the northern short-tailed shrew (Blarina brevicauda) and has been found to inhibit the transient receptor potential of vallinoid type 6 (TRPV6) calcium channels. We report that two shorter peptides, SOR-C13 and SOR-C27, derived from the C-terminus of soricidin, are high-affinity antagonists of human TRPV6 channels that are up-regulated in a number of cancers. Herein, we report molecular imaging methods that demonstrate the in vivo diagnostic potential of SOR-C13 and SOR-C27 to target tumor sites in mice bearing ovarian or prostate tumors. Our results suggest that these novel peptides may provide an avenue to deliver diagnostic and therapeutic reagents directly to TRPV6-rich tumors and, as such, have potential applications for a range of carcinomas including ovarian, breast, thyroid, prostate and colon, as well as certain leukemias and lymphomas.

Clearance of depot vaccine SPIO-labeled antigen and substrate visualized using MRI

Immunotherapies, including peptide-based vaccines, are a growing area of cancer research, and understanding their mechanism of action is crucial for their continued development and clinical application. Exploring the biodistribution of vaccine components may be key to understanding this action. This work used magnetic resonance imaging (MRI) to characterize the in vivo biodistribution of the antigen and oil substrate of the vaccine delivery system known as DepoVax(TM). DepoVax uses a novel adjuvanted lipid-in-oil based formulation to solubilise antigens and promote a depot effect. In this study, antigen or oil were tagged with superparamagnetic iron oxide (SPIO), making them visible on MR images. This enables tracking of individual vaccine components to determine changes in biodistribution. Mice were injected with SPIO-labeled antigen or SPIO-labeled oil, and imaged to examine clearance of labeled components from the vaccine site. The SPIO-antigen was steadily cleared, with nearly half cleared within two months post-vaccination. In contrast, the SPIO-oil remained relatively unchanged. The biodistribution of the SPIO-antigen component within the vaccine site was heterogeneous, indicating the presence of active clearance mechanisms, rather than passive diffusion or drainage. Mice injected with SPIO-antigen also showed MRI contrast for several weeks post-vaccination in the draining inguinal lymph node. These results indicate that MRI can visualize the in vivo longitudinal biodistribution of vaccine components. The sustained clearance is consistent with antigen up-take and trafficking by immune cells, leading to accumulation in the draining lymph node, which corresponds to the sustained immune responses and reduced tumor burden observed in vaccinated mice.

Spatial MEG Laterality maps for language: Clinical applications in epilepsy

Functional imaging is increasingly being used to provide a noninvasive alternative to intracarotid sodium amobarbitol testing (i.e., the Wada test). Although magnetoencephalography (MEG) has shown significant potential in this regard, the resultant output is often reduced to a simplified estimate of laterality. Such estimates belie the richness of functional imaging data and consequently limit the potential value. We present a novel approach that utilizes MEG data to compute “complex laterality vectors” and consequently “laterality maps” for a given function. Language function was examined in healthy controls and in people with epilepsy. When compared with traditional laterality index (LI) approaches, the resultant maps provided critical information about the magnitude and spatial characteristics of lateralized function. Specifically, it was possible to more clearly define low LI scores resulting from strong bilateral activation, high LI scores resulting from weak unilateral activation, and most importantly, the spatial distribution of lateralized activation. We argue that the laterality concept is better presented with the inherent spatial sensitivity of activation maps, rather than being collapsed into a one‐dimensional index. Hum Brain Mapp, 2013.

Using MRI to evaluate and predict therapeutic success from depot-based cancer vaccines.

In the preclinical development of immunotherapy candidates, understanding the mechanism of action and determining biomarkers that accurately characterize the induced host immune responses is critical to improving their clinical interpretation. Magnetic resonance imaging (MRI) was used to evaluate in vivo changes in lymph node size in response to a peptide-based cancer vaccine therapy, formulated using DepoVax (DPX). DPX is a novel adjuvant lipid-in-oil–based formulation that facilitates enhanced immune responses by retaining antigens at the injection site for extended latencies, promoting increased potentiation of immune cells. C57BL/6 mice were implanted with C3 (HPV) tumor cells and received either DPX or control treatments, 5 days post-implantation. Complete tumor eradication occurred in DPX-vaccinated animals and large volumetric increases were observed in the vaccine-draining right inguinal lymph node (VRILN) in DPX mice, likely corresponding to increased localized immune response to the vaccine. Upon evaluating the relative measure of vaccine-potentiated immune activation to tumor-induced immune response (VRILN/VLILN), receiver-operating characteristic (ROC) curves revealed an area under the curve (AUC) of 0.90 (±0.07), indicating high specificity and sensitivity as a predictive biomarker of vaccine efficacy. We have determined that for this tumor model, early MRI lymph node volumetric changes are predictive of depot immunotherapeutic success.

Quantification of Butyrylcholinesterase Activity as a Sensitive and Specific Biomarker of Alzheimer’s Disease

Amyloid-β (Aβ) plaques are a neuropathological hallmark of Alzheimer’s disease (AD); however, a significant number of cognitively normal older adults can also have Aβ plaques. Thus, distinguishing AD from cognitively normal individuals with Aβ plaques (NwAβ) based on Aβ plaque detection is challenging. It has been observed that butyrylcholinesterase (BChE) accumulates in plaques preferentially in AD. Thus, detecting BChE-associated plaques has the potential as an improved AD biomarker. We present Aβ, thioflavin-S, and BChE quantification of 26 postmortem brain tissues; AD (n = 8), NwAβ (n = 6), cognitively normal without plaques (n = 8), and other common dementias including corticobasal degeneration, frontotemporal dementia with tau, dementia with Lewy bodies, and vascular dementia. Pathology burden in the orbitofrontal cortex, entorhinal cortex, amygdala, and hippocampal formation was determined and compared. The predictive value of Aβ and BChE quantification was determined, via receiver-operating characteristic plots, to evaluate their AD diagnostic performance using sensitivity, specificity, and area under curve (AUC) metrics. In general, Aβ and BChE-associated pathology were greater in AD, particularly in the orbitofrontal cortex. In this region, the largest increase (9.3-fold) was in BChE-associated pathology, observed between NwAβ and AD, due to the virtual absence of BChE-associated plaques in NwAβ brains. Furthermore, BChE did not associate with pathology of the other dementias. In this sample, BChE-associated pathology provided better diagnostic performance (AUC = 1.0, sensitivity/specificity = 100% /100%) when compared to Aβ (AUC = 0.98, 100% /85.7%). These findings highlight the predictive value of BChE as a biomarker for AD that could facilitate timely disease diagnosis and management.

Using lymph node swelling as a potential biomarker for successful vaccination

There is currently a lack of biomarkers to help properly assess novel immunotherapies at both the preclinical and clinical stages of development. Recent work done by our group indicated significant volume changes in the vaccine draining right lymph node (RLN) volumes of mice that had been vaccinated with DepoVaxTM, a lipid-based vaccine platform that was developed to enhance the potency of peptide-based vaccines. These changes in lymph node (LN) volume were unique to vaccinated mice. To better assess the potential of volumetric LN markers for multiple vaccination platforms, we evaluated 100 tumor bearing mice and assessed their response to vaccination with either a DepoVax based vaccine (DPX) or a water–in-oil emulsion (w/o), and compared them to untreated controls. MRI was used to longitudinally monitor LN and tumor volumes weekly over 4 weeks. We then evaluated changes in LN volumes occurring in response to therapy as a potential predictive biomarker for treatment success. We found that for both vaccine types, DPX and w/o, the %RLN volumetric increase over baseline and the ratio of RLN/LLN were strong predictors of successful tumor suppression (LLN is left inguinal LN). The area under the curve (AUC) was greatest, between 0.75-0.85, two (%RLN) or three (RLN/LLN) weeks post-vaccination. For optimized critical thresholds we found these biomarkers consistently had sensitivity >90% and specificity >70% indicating strong prognostic potential. Vaccination with DepoVax had a more pronounced effect on draining lymph nodes than w/o emulsion vaccines, which correlated with a higher anti-tumor activity in DPX-treated mice.

Cerebral glucose metabolism, pathology and behaviour in the 5XFAD mouse model of Alzheimer's disease

IC-P-045 CEREBRAL GLUCOSE METABOLISM, PATHOLOGYAND BEHAVIOR IN THE 5XFAD MOUSE MODEL OFALZHEIMER’S DISEASE Ian Macdonald, Drew DeBay, Tim O’Leary, Andrew Reid, Meghan Cash, Courtney Jollymore, George Mawko, Steve Burrell, Chris Bowen, Earl Martin, Richard Brown, Sultan Darvesh, Dalhousie University, Halifax, Nova Scotia, Canada; National Research Council, Halifax, Nova Scotia, Canada; Mount Saint Vincent University, Halifax, Nova Scotia, Canada. Contact e-mail: Ian.Macdonald@dal.ca

BUTYRYLCHOLINESTERASE GENETIC POLYMORPHISM AND NEUROIMAGING BIOMARKERS IN ALZHEIMER’S DISEASE

Background: It has been already described that the gene coding the translocator protein (TSPO), expressed in microglial mitochondria, has a specific polymorphism which affects the proper binding of some radioligands used to index microglial activation in vivo. For this reason, population enrichment based on TSPO genotyping is extremely important in imaging studies of neuroinflammation, as it precludes misleading findings with false negative scans. It is also important to assure that the polymorphism has no pleiotropic effects with any phenotype related to the disease under investigation, which would also lead to incorrect findings. Our aim was to assess the allele frequency of the TSPO polymorphism rs6971 as well as to investigate its effects on dementia-related phenotypes in a Canadian cohort. Methods: The TSPO polymorphism rs6971 was genotyped in 673 participants from the Montreal (Canada) catchment area. Clinical and demographic information was collected for all participants. The diagnosis was clinically determined and the cognition was assessed by tests such as MOCA and MMSE. APOE genotype was available for a subsample of 649 participants. MRI scans were performed in 110 subjects, for which mean diffusivity (MD), fractional anisotropy (FA) and white matter hyperintensity (WMH) were calculated. Cerebrospinal fluid was obtained for 63 subjects and Ab, tau and phosphorylated-tau levels were measured. Subjects were classified as low-binders when rs6971 homozygous and high-binders when rs6971 homozygous. Chi-square and t-tests were used for demographic description whereas linear models adjusted for covariates were used to assess the effect of rs6971 on the available phenotypes. Results: The rs6971 minor-allele frequency in our study population is 0.30 (48,8% CC,41.7% CT,9.4% TT) (Figure 1), which is in accordancewith frequencies described for Caucasian populations in public databases. Differences in gender, diagnosis and APOE-e4 status were not observed across rs6971 genotypes. The rs6971 was not associated with any cognitive score as well as with none of the CSF or imaging biomarkers tested here. Conclusions:The study population under investigation is genetically representative of the Caucasian population –for the rs6971–and the SNP showed no effect in any dementia-related phenotypes analyzed here. Results confirm that the cohort is appropriate for neuroimaging studies linking dementia and neuroinflammation.

CEREBRAL PERFUSION IN THE 5XFAD MOUSE MODEL OF ALZHEIMER’S DISEASE

assessed in the Y-maze. In vivo signals were confirmed by autoradiography and immunohistochemistry in brain sections from scanned mice. Results:A progressive, age-dependent reduction in F-BCPP-EF uptake was observed in hippocampal and forebrain regions of tauTg mice, coinciding with the development of tau lesions detected by C-PBB3 PET. A strong association was observed betweenMC-I signals detected by PET, hippocampal volume assessed byMRI, and learning andmemory performance in the Y-maze task. In vivo findings were confirmed by F-BCPP-EF autoradiography and immunohistochemistry for AT-8 (tau phosphorylation), GFAP (astrocytes), IBA-1 (microglia), NeuN (neurons). Conclusions:MC-I PET may provide a useful non-invasive imaging biomarker for the real-time identification of early-stage mitochondrial abnormalities associated with tau-induced neurodegenerative cascades.

Impact of hepatocyte growth factor on skeletal myoblast transplantation late after myocardial infarction.

In clinical studies, skeletal myoblast (SKMB) transplantation late after myocardial infarction (MI) has minimal impact on left ventricular (LV) function. This may be related to our previous observation that the extent of SKMB engraftment is minimal in chronic MI when compared to acute MI, which correlates with decreased hepatocyte growth factor (HGF) expression, an important regulator of SKMB function. Here, we investigated delivery of exogenous HGF as a strategy for augmenting SKMB engraftment late after MI. Rats underwent SKMB transplantation 4 weeks after coronary ligation. HGF or vehicle control was delivered intravenously during the subsequent 2 weeks. LV function was assessed by MRI before and 2 weeks after SKMB transplantation. We evaluated HGF delivery, SKMB engraftment, and expression of genes associated with post-MI remodeling. Serum HGF was 6.2 ± 2.4 ng/mL after 2 weeks of HGF infusion (n = 7), but undetectable in controls (n = 7). LV end-diastolic volume and ejection fraction did not improve with HGF treatment (321 ± 27 mm3, 42% ± 2% vs. 285 ± 33 mm3, 43% ± 2%, HGF vs. control). MIs were larger in HGF-treated animals (50 ± 7 vs. 30 ± 6 mm3, P = 0.046), but the volume of engrafted SKMBs or percentage of MIs occupied by SKMBs did not increase with HGF (1.7 ± 0.3 mm3, 4.7% ± 1.9% vs. 1.4 ± 0.4 mm3, 5.3% ± 1.6%, HGF vs. control). Expression of genes associated with post-infarction remodeling was not altered by HGF. Delivery of exogenous HGF failed to augment SKMB engraftment and functional recovery in chronic MI. Expression of genes associated with LV remodeling was not altered by HGF. Alternative strategies to enhance engraftment of SKMB must be explored to optimize the clinical efficacy of SKMB transplantation.