Levodopa-induced Dyskinesia in Parkinson's Disease: Plausible Inflammatory and Oxidative Stress Biomarkers.

Background: Pathophysiology of levodopa-induced dyskinesia (LID) remains obscure. Increased dopamine metabolism due to prolonged levodopa treatment can exacerbate oxidative damage and neuroinflammatory pathology in Parkinson's disease (PD). Association of novel peripheral markers with LID severity might provide insight into LID pathomechanisms.
Objective: We aimed to study specific peripheral blood inflammatory-oxidative markers in LID patients and investigate their association with clinical severity of LID.
Method: Motor, non-motor and cognitive changes in PD with and without LID compared to healthy-matched controls were identified. Within the same cohort, inflammatory marker (sLAG3, TOLLIP, NLRP3 and IL-1β) levels and antioxidant enzyme activities were determined by ELISA and spectrophotometric methods.
Results: LID patients showed distinctly upregulated TOLLIP, IL-1β levels with significant diminution of antioxidant activity compared to controls. Significant negative association of cognitive markers with oxidative changes was also observed.
Conclusion: To our understanding, this is the first study that indicates the involvement of toll-like receptor-mediated distinct and low-grade inflammatory activation in LID pathophysiology.