Determining Efficacy of DMF Treatment for PPT1 and TPP1-deficient Neuronal Ceroid Lipofuscinosis Cell Cultures

CLN1 and CLN2 are lysosomal storage disorders arising from respective mutations to PPT1 and TPP1 genes; PPT1 and TPP1 code for key lysosomal proteins that break down fats and proteins. Inability to break down waste material causes these diseases to accumulate large amounts of lipofuscin, most readily identified in tissue in the neural system. Infants and juveniles who present with this disease are marked with seizures, vision loss, and cognitive decline. Accumulation of waste products leads to neuroinflammation and increased oxidative stress in CLN1 and CLN2, decreasing rates of dendritic branching and preventing key brain connections from developing in the young mind. While NCL gene therapy and pharmaceutical methods are in development, few studies have examined ways to directly lower oxidative stress in NCLs. Dimethyl Fumarate (DMF) has been shown to significantly decrease relapse rates of patients with multiple sclerosis (MS), another neuroinflammatory disease. DMF activates the Nrf2 pathway, signaling a number of cell-protecting agents; notably, the antioxidant response element (ARE) is transcribed with increased Nrf2, leading to downstream production of reducing agents to help relieve oxidative stress. Due to its high efficacy in MS treatment, our lab decided to test DMF as a potential treatment for CLN1 and CLN2 cells. Cell cultures of CLN1 and CLN2 cells treated with DMF were not found to have significant induction of the Nrf2 pathway. Similarly, downstream effects of DMF induction such as the number of vacuoles per cell or amount of lysosomes present as visualized through LAMP1 did not vary significantly with DMF treatment; one notable exception is the CLN2-486 cell lines treated with 30µM DMF which were found to significantly increase in LAMP1 intensity and lysosomal function. Our findings suggest that DMF is an ineffective treatment for CLN1 and CLN2, although future studies should be conducted to verify these results