Inflammatory Biomarkers for Parkinson's Disease

Abstract

Parkinson disease (PD) is caused by degeneration of dopaminergic neurons.
Clinically it is characterized by bradykinesia, rigidity and resting tremors. The central hallmark of
the PD is accumulation of alpha synuclein (α-SN). Aetiology of the PD includes exposure to the
environmental toxins, low serum urate, genes and sporadic forms of the disease. Till date PD is a
clinical diagnosis with almost 80% of dopaminergic neurons disintegrated when motor signs
begin to appear. Therefore, there is urgent need for the definite biomarkers that indicate death of
the dopaminergic neurons and provide accuracy in diagnosis. The cerebrospinal fluid (CSF) and
imaging biomarkers are already available with varying and inconsistent results. Genetic
biomarkers have also significantly contributed in revealing the physiological and pathological
process underlying the PD. Most important of them is the leucine rich repeat kinase (LRRK2)
which has role in both sporadic and familial forms of the PD. Inflammation appears also to
be an important player in PD pathogenesis. The crosstalk between immune system of the
CNS and peripheral immune system results in generation of cytokines and chemokines
that are useful inflammatory biomarkers. Importantly LRRK2 expressed in different immune
cells of the innate immunity which further strengths the role of inflammation in the PD
pathogenesis. Hence inflammatory biomarkers could aid in early diagnosis of the PD, helps in
identification of new pathways and novel therapeutic targets. Key words Parkinson disease (PD),
leucine rich repeat kinase(LRRK2), MRI, innate immunity