Examining the effect of cadmium metal exposure on Alzheimer's disease genetic alleles using herpes viral infected cerebral organoids - PROJECT SUMMARY/ABSTRACT Several genetic variants within immune system genes like APOE, TREM2, BIN1, CR1, etc have been associated with Alzheimer’s disease (AD). There is also evidence showing heavy metals such as cadmium (Cd) toxicity being associated with AD. Studies have shown that circulatory levels of Cd are significantly increased in AD patients and Cd levels in urine are associated with AD associated mortality. Next, neuroinflammatory dysregulation due to viral infection has also been implicated in AD. Evidence for this includes, discoveries linking a higher load of herpes-viral signatures of post-mortem brain tissues of AD patients and accelerated beta-amyloid deposition in in-vitro and in-vivo models infected with herpes viruses. Since then, our team has been studying the role of herpes simplex virus 1 (HSV-1) in AD using human in-vitro cerebral organoid (cOrgs) models differentiated from induced pluripotent stem cells (iPSCs). Our work led to the discovery of an AD-specific transcriptomic perturbations signature by HSV-1. We also discovered that HSV-1 infection of cOrgs upregulated AD markers such as Aβ and phosphorylated Tau. As such, we propose to use these phenotypes to test the if we can similarly measure such AD-specific phenotypes when cOrgs are exposed to Cd alone or exposed to Cd in conjunction with HSV-1 infection and test if genetic variation affect these phenotypes. We plan to select donor lymphoblastoid cell lines (LCLs) carrying various immune related AD associated genetic variants from the 1000 genomes project as well as the Personal Genome Project for reprogramming into iPSCs and differentiating into cOrgs. We plan to test similar conditions for all our aims. We will perform the tests on a single-donor differentiated cOrgs as well as on multiple cOrgs carrying different AD- genetic variants. We will test and compare between Cd exposed cOrg and unexposed cOrgs. We will test HSV-1 infected, Cd exposed cOrgs and compare that with just unexposed HSV-1 infected cOrgs. For aim 1, we plan to perform RNA-sequencing of the cOrgs and test for the AD-specific transcriptomic perturbation signature upon Cd exposure, with or without HSV-1 infection, and the effect of the genetic variants. For aim 2, we plan to perform intracellular staining of Aβ, phosphorylated Tau and several cell type specific markers using flow cytometry and determine if Cd exposure or HSV-1 infection causes significant changes and whether cOrgs carrying various variants will show differential effects. For aim 3, we plan to interrogate the media for pro-inflammatory cytokines using multiplex enzyme-linked immunosorbent assays (ELISAs). By doing so, we can test if any are released upon Cd exposure or HSV-1 infection and if their effects are different for the various AD-associated genetic variants. These aims are independent measurements for determining the relationship between Cd exposure, HSV-1 infection, genetic variation, and AD pathology. Knowing these things will allow us to understand better the pathology of AD and reveal insights into its genetic and environmental effects which can lead to novel ways of treating this debilitating neurodegenerative disease.
