Intranasal delivery of VGF-derived peptides in a preclinical model of Alzheimer's disease

Late onset Alzheimer’s disease (AD), the most common form of dementia, is characterized by memory loss and a progressive decline in cognitive function. The Accelerating Medicines Partnership-Alzheimer’s Disease (AMP- AD) program has supported systems biology analyses, with VGF (non-acronymic), a neurotrophin-inducible protein and neuropeptide precursor, being one of the top ranked AD drivers (regulators) identified by several groups. Notably, biomarker studies have consistently identified reduced VGF levels in the brains and CSF of patients with AD, and have further demonstrated that VGF is also a strong candidate biomarker of AD progression. Our recent published data demonstrate that VGF overexpression in hippocampus or chronic intracerebroventricular (icv) infusion of the VGF-derived neuropeptides TLQP-21 or TLQP-62 (named by the N- terminal 4 amino acids and length) reduces cortical and hippocampal amyloid deposition, microgliosis, and/or astrogliosis, in a regionally-specific manner, and reduces cognitive impairment in the 5xFAD mouse amyloidosis model. TLQP-21 activates the complement C3aR1 G-protein coupled receptor (GPCR), also implicated in AD pathogenesis and expressed in the CNS on neurons, microglia, and astrocytes, while the antidepressant and procognitive functions of TLQP-62 are dependent on BDNF/TrkB signaling. In this RO1 proposal, we request support for preclinical studies that will optimize intranasal (IN) nose-to-brain therapeutic delivery of the VGF- derived peptides TLQP-21 and TLQP-62 to mice, and will determine their efficacy in the 5xFAD mouse model of amyloidosis and then subsequently in the PS19 tauopathy model to reduce neuropathology and the progression of AD-like phenotypes. Our preliminary imaging data indicates that intranasal administration of Cy5-TLQP-21 and Cy5-TLQP-62 results in significant, rapid brain uptake. Aim 1 will determine regional uptake in the brain and any systemic spillover of IN Cy5-conjugated peptides, using small animal imaging and western analysis of brain and peripheral tissues. Aim 2 will verify retention of intact peptide in brain using Cy5- and biotin-conjugated peptide quantification by western analysis, and will determine ‘target engagement’ in hippocampus and cerebral cortex by IN peptide, including BDNF/TrkB/CREB and c-fos activation. Interim milestones include identification of the optimal dose and dosing interval for IN peptide delivery based on quantification of regional peptide levels in the brain, and the determination that signaling pathways known to be regulated by intra-hippocampal or icv delivery of these peptides are activated by IN peptide. Aim 3 will utilize the most efficacious IN delivery schedule identified to determine whether cognitive impairment and neuropathology in 5xFAD and PS19 can be reduced. Lastly, longevity of intranasal peptide treatment effects will be tested, systemic toxicity will be assessed, peptide modification(s) will be considered, and behavioral, biochemical, histological and large-scale genetics approaches will be employed to measure relative peptide efficacy in reducing disease progression. These preclinical studies will provide a firm foundation for future intervention using intranasal delivery of VGF peptide therapeutics in AD.