ALDH2 deficiency exacerbates acrolein-mediated neuropathology in multiple sclerosis

The pro-inflammatory aldehyde acrolein has long been implicated as a critical factor in the pathology of multiple sclerosis. Given that acrolein can be scavenged via the endogenous enzyme aldehyde dehydrogenase 2 (ALDH2), we sought to investigate whether individuals with an ALDH2 deficiency, ALDH2*2, may be more susceptible to worsened symptoms of multiple sclerosis. In this study, we model this clinically relevant genotype in mice with an animal model of multiple sclerosis, experimental autoimmune encephalomyelitis. Our results indicate that ALDH2*2 mice induced with experimental autoimmune encephalomyelitis not only display heightened behavioral deficits and neuropathic pain, but also enhanced expression of acrolein, various inflammatory markers, glutamate transporter dysfunction, demyelination, and a trend of neuronal loss, demonstrating a neuroprotective role of ALDH2 on various key aspects of multiple sclerosis pathology. Notably, these differences were absent between control ALDH2*2 and wild-type mice, indicating that the ALDH2*2 genotype alone does not appear to produce behavioral or physiological deficits. However, our results support emerging studies suggesting that individuals with ALDH2*2 may suffer from worsened symptoms in an acrolein-mediated disease such as multiple sclerosis compared with individuals with functioning ALDH2. This study additionally serves to reinforce the pivotal role of acrolein and ALDH2 in experimental autoimmune encephalomyelitis pathogenesis, expanding the possible therapeutic targets to achieve neuroprotection in multiple sclerosis.