Pharmacological Inhibition of ceramide production in mitochondria as treatment for Alzheimer's disease

A metabolic shift favoring ceramide formation in the brain has been proposed to play an important role in amyloid-â (Aâ) formation and neuronal death in Alzheimer’s disease (AD). However, how neurotoxicity is mediated and whether pharmacological inhibition of ceramide generation represents a valid approach to modify AD pathology is still uncertain. The long-term goal of this research proposal is to dissect mitochondria dysfunction mediated by ceramide in AD and identify specific targets that protect mitochondria homeostasis. Recently, it was demonstrated that ceramide synthesis (CerS) in mitochondria is a key player in mitophagy and acid sphingomyelinase (A-SMase) mediates respiratory chain defects. Our central hypothesis is that ceramide mediates neurotoxicity by affecting mitochondrial function in neurons and that this process is prevented by inhibiting ceramide metabolism enzymes important for mitochondria homeostasis, such as CerS and A-SMase. The specific aims that test our hypothesis are: i) Identify ceramide species in mitochondria derived from AD mice models; ii) Examine whether extracellular trafficking of ceramide in micro-vesicles contributes to neurotoxic signaling propagation; iii) Determine whether CerS and/or A-SMase inhibition protects mitochondria from ceramide pore formation, lethal mitophagy, and respiratory chain defects; and iv) Delineate whether A-SMase and/or CerS inhibition corrects cognitive decline in an AD animal model. Transgenic mice models of familial AD (5xFAD) will be used to isolated mitochondria from brain tissue and to prepare neuronal and astrocyte primary culture to answer aim 1, 2 and 3. In aim 2 we will employ also neuroblastoma cells to study ceramide release in micro-vesicles. Primary outcomes of aim 1, 2 and 3 are ceramides species levels, measured by LC-MS/MS, and mitochondrial function, assayed through Seahorse approach. Next, the 5xFAD mice model will be challenged with daily administration of FTY720 to inhibit CerS and/or Imipramine to inhibit A-SMase for answering aim 4. Object recognition task will be administered during the last week of treatment to assess memory. At termination, brains will be collected for further biochemical analyses. We will measure Aâ pathology, global ceramide pathology in different brain regions, mitochondria function and neuronal loss. Upon conclusion, we will gain knowledge on the role of ceramide in AD pathophysiology and identify new therapeutic targets for the treatment of AD. The proposed research is innovative because it centers on the role of ceramide in AD pathophysiology, and findings may extend new therapeutics from AD to other neurodegenerative diseases where ceramide metabolism is known to play a role.