In Vitro Studies of Interferon-alpha Neurotoxicity (P01.248)

Abstract

Objective: To determine the mechanism of interferon-alpha (IFNa) toxicity in neurons. Background Elevated IFNa in the CNS is linked to cognitive dysfunction in patients with inflammatory CNS diseases such as HIV-associated dementia. Previous studies showed that IFNa treatment of neuronal cultures caused a dose dependent decrease in dendritic branching and length, mostly prevented after pre-treatment with IFNa neutralizing antibodies. Design/Methods: Primary neurons were extracted from rat fetal cortices and cultured for 14 days. Neurons were treated with 1000 U/ml of IFNα for multiple time points prior to protein extractions or immunofluorescence staining. Protein extracts were analyzed using Western blot. Neurons were analyzed for dendritic length and branching using ImagePro. Results: After 24hrs of IFNα treatment, average total length of branches per neuron was significantly reduced. By 48hrs the number of branches per neuron was significantly decreased. To begin to evaluate the mechanism of decreased dendritic arborization, microtubule associate protein 2 (MAP2), a cytoskeleton protein required for dendritic growth and stability in neurons, was examined. IFNα causes a decrease in total MAP2 protein levels as soon as 2 hrs after treatment that remain decreased compared to controls through 48 hrs. MAP2 association with microtubules, required for neuronal function and dendritic stability, is regulated by phosphorylation, specifically at the Ser126 site on MAP2. Preliminary data shows a decrease in phosphorylation at Ser136 on MAP2 after IFNα treatment. STAT1 phosphorylation was examined in order to begin to determine the signaling cascade after IFNα receptor engagement. Phosphorylated STAT1 peaks 2 hrs after IFNα administration. Conclusions: The neurotoxicity of IFNα is complex since it has direct and indirect effects on neuronal function. Our studies suggest that IFNα is in part acting through its receptor to reduce MAP2 expression in neurons. Determining the mechanism of IFNα neurotoxicity could lead to therapies for cognitive dysfunction during neuroinflammation. Supported by: VA Merit award 0007. Disclosure: Dr. Tyor has nothing to disclose. Dr. Fritz-French has nothing to disclose. Dr. Welshhans has nothing to disclose. Dr. Zhang has nothing to disclose. Dr. Sas has nothing to disclose. Dr. Bassell has nothing to disclose.