Innate immune-induced neuronal cell apoptosis via a SARM1 mediated mechanism in the absence of viral replication. (INM9P.451)

Abstract

Abstract Neuronal cell death is a hallmark of multiple neurological diseases including viral infections. The innate immune response in the CNS can contribute to neuronal cell death indirectly through the production of cytokines and neurotoxins as well as via the recruitment of immune cells. However, the direct induction of neuronal cell death via innate immune mechanisms is less well characterized and often confused by confounding factors such as viral replication. We previously identified sterile alpha and HEAT/Armadillo motif containing 1 (SARM1) as a mediator of bunyavirus induced neuronal apoptosis. Currently, we have identified a new mechanism of SARM1-mediated neuronal cell death independent of viral infection of the cell. Treatment with TLR7 and TLR9 agonists induces significant levels of neuronal cell death in cortical neurons. Cell death was associated with induction of SARM1 and inhibition of SARM1 suppressed TLR7 and TLR9 mediated neuronal apoptosis. SARM1 localized to the mitochondria and induced oxidative damage leading to neuronal apoptosis. Mechanistic studies indicated that SARM1 co-localized with both PINK1 and UXT proteins indicating a putative mechanism of SARM1 mediated neuronal cell. Thus, activation of pattern-recognition receptors on neurons in the absence of active virus infection can lead to neuronal death and the mechanism of death is via production of SARM leading to mitochondrial damage.