Neuroprotective effect of Nrf2/ARE activators, CDDO ethylamide and CDDO trifluoroethylamide, in a mouse model of amyotrophic lateral sclerosis.

Oxidative damage, neuroinflammation, and mitochondrial dysfunction contribute to the pathogenesis of ALS, and these pathologic processes are tightly regulated by the Nrf2/ARE (NF-E2 related factor 2/antioxidant response element) signaling program. Therefore, modulation of the Nrf2/ARE pathway is an attractive therapeutic target for neurodegenerative diseases such as ALS. We examined two triterpenoids, CDDO (2-cyano-3, 12-dioxooleana-1,9-dien-28-oic acid) ethylamide (CDDO-EA) and CDDO-trifluoroethylamide (CDDO-TFEA), that potently activate Nrf2/ARE in a cell culture model of ALS and in the G93A SOD1 mouse model of ALS. Treatment of NSC-34 cells stably expressing mutant G93A SOD1 with CDDO-TFEA upregulated Nrf2 expression, and resulted in translocation of Nrf2 into the nucleus. Western blot analysis showed an increase in the expression of Nrf2/ARE-regulated proteins. When treatment started at a “presymptomatic age”, of 30 days both of these compounds significantly attenuated weight loss, enhanced motor performance and extended the survival of G93A SOD1 mice. Treatment started at a “symptomatic age”, as assessed by impaired motor performance was neuroprotective and slowed disease progression. These findings provide further evidence that compounds which activate the Nrf2/ARE signaling pathway may be useful in the treatment of ALS.