Short communicationIncreased levels of cell-free mitochondrial DNA in the cerebrospinal fluid of patients with multiple sclerosis

•Levels of cell-free mtDNA is increased in CSF of MS patients•The levels of mtDNA and disease duration are inversed correlated•mtDNA may provide a stage-specific marker for disease activity

Mitochondrial DNA (mtDNA) can act as damage-associated molecular pattern molecule (DAMP) and initiate an inflammatory response. We hypothesized that the concentration of mtDNA might reflect inflammatory activity in multiple sclerosis and investigated therefore levels of cell-free mitochondrial DNA in cerebrospinal fluid of patients with relapsing-remitting multiple sclerosis. Significantly higher levels of mtDNA were found in patients compared to controls and there was an inverse correlation between disease duration and mtDNA concentration. Our study suggests that mitochondria can be involved early in multiple sclerosis, but whether this is as an initiator of the inflammatory response or part of its maintenance is unclear. Further, our study suggests that changes in mtDNA may provide a novel marker for early disease activity.