Cerebrospinal fluid IL-1β correlates with cortical pathology load in multiple sclerosis at clinical onset

•Cortical demyelinating lesions and atrophy are peculiar features of MS pathology.•The progressive cortical damage in MS determines physical and cognitive decline.•CSF levels of IL-1β correlate with cortical pathology in very early MS.•IL-1β, expressed by activated microglia, may contribute to neurodegeneration in MS.•This cytokine may play a role in linking inflammation and neurodegeneration in MS.

The cerebrospinal fluid levels of interleukin-1 beta and structural magnetic resonance parameters of cortical damage, i.e., cortical lesion number and volume, and global cortical thickness, were analysed in multiple sclerosis patients at clinical onset. Cerebrospinal fluid interleukin-1 beta levels strongly correlated with cortical lesion load and cortical thickness, while correlation with white matter lesion load was modest. Interleukin-1 beta, intrathecally produced by infiltrating lymphocytes and activated microglia, may constitute a possible link between inflammation and neurodegeneration in multiple sclerosis.