Cytokine activity in Parkinson's disease

Abstract

The contribution of the immune system to the pathophysiology of neurodegenerative Parkinson's disease (PD) is increasingly being recognised, with alterations in the innate and adaptive arms of the immune system underlying central and peripheral inflammation in PD. As chief modulators of the immune response, cytokines have been intensely studied in the field of PD both in terms of trying to understand their contribution to disease pathogenesis, and if they may comprise much needed therapeutic targets for a disease with no current modifying therapy. This review summarises current knowledge on key cytokines implicated in PD (TNFα, IL-6, IL-1β, IL-10, IL-4 and IL-1RA) that can modulate both pro-inflammatory and anti-inflammatory effects. Cytokine activity in PD is clearly a complicated process mediated by substantial cross-talk of signalling pathways and the need to balance pro- and anti-inflammatory effects. However, understanding cytokine activity may hold promise for unlocking new insight into PD and how it may be halted.

Keywords: Parkinsons disease; cytokines; inflammation; interleukins; tumour necrosis factors.

Figure 1. Cytokine imbalance in PD

PD is associated with an imbalance in the levels of peripheral and central cytokines that mediate pro- and anti- inflammatory responses, resulting in a chronic low-grade pro-inflammatory phenotype. Pro-inflammatory cytokines can contribute to the degeneration of movement controlling dopamine neurons via the activation of microglia or by acting directly on neurons themselves. In turn, this contributes to the clinical symptoms of PD. Figure created with Biorender.com