AbstractIncreasing evidence supports a role for abnormal immune activation and inflammatory responses in Huntington disease (HD). In this study, we evaluated the therapeutic potential of laquinimod (1 and 10 mg/kg), a novel immunomodulatory agent shown to be protective in a number of neuroinflammatory conditions, in the YAC128 mouse model of HD. Treatment with laquinimod for 6 months rescued atrophy in the striatum, in certain cortical regions, and in the corpus callosum of YAC128 HD mice. Diffusion tensor imaging showed that white matter microstructural abnormalities in the posterior corpus callosum were improved following treatment with low dose (1 mg/kg) laquinimod, and were paralleled by reduced levels of interleukin-6 in the periphery of YAC128 HD mice. Functionally, treatment with laquinimod (1 and 10 mg/kg) led to modest improvements in motor function and in depressive-like behaviour. Taken together, these results suggest that laquinimod may improve some features of pathology in HD, and provides support for the role of immune activation in the pathogenesis of HD.