AUTHOR=Lian Teng-Hong , Guo Peng , Zuo Li-Jun , Hu Yang , Yu Shu-Yang , Yu Qiu-Jin , Jin Zhao , Wang Rui-Dan , Li Li-Xia , Zhang Wei 

TITLE=Tremor-Dominant in Parkinson Disease: The Relevance to Iron Metabolism and Inflammation

JOURNAL=Frontiers in Neuroscience

VOLUME=Volume 13 - 2019

YEAR=2019

URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2019.00255

DOI=10.3389/fnins.2019.00255

ISSN=1662-453X

ABSTRACT=Background  Tremor is one of the most predominant symptoms of patients with Parkinson disease (PD), but the underlying mechanisms for tremor relating iron and its metabolism-related proteins and the inflammatory factors in cerebrospinal fluid (CSF) and serum have not been fully elucidated.
Methods  A total of 135 PD patients were divided into tremor-dominant (PD-TD) group (N=74) and gait difficulty-dominant (PD-PIGD) group (N=39) based on the ratio of mean tremor score to the mean bradykinesia/rigid score in Unified Parkinson's Disease Rating Scale (UPDRS) III. Age and sex-matched healthy controls were recruited (N=35). Demographic variables were evaluated; iron and its metabolism-related proteins and the inflammatory mediators in both CSF and serum were measured in these groups. The relevance of iron metabolism, inflammation and PD-TD were analyzed.
Results  1. PD-TD group had significantly decreased L-ferritin, increased iron levels in CSF and increased ferritin level in serum compared with PD-PIGD and control groups (P<0.05). PD-TD was prominently and positively correlated with iron level (r=0.345, P=0.011) and negatively correlated with L-ferritin level (r=-0.831, P=0.022). 2. PD-TD group had significantly enhanced IL-6 levels in both CSF and serum compared with PD-PIGD and control groups (P<0.05). IL-6 levels in both CSF and serum were positively and significantly correlated with PD-TD (r=0.313, P=0.048，r=0.276, P=0.028, respectively). 3. In CSF, IL-6 level was increased as iron level was elevated in PD-TD group (r=0.308, P=0.022). In serum, IL-6 level was increased as ferritin level was elevated in PD-TD group (r=0.410, P=0.004).
Conclusions The interplay between disturbed iron metabolism and relevant inflammation might modulate clinical phenotypes of PD.