Investigation of the relationship between heavy metals (cadmium, arsenic, lead) and metallothionein in multiple sclerosis

Multiple sclerosis (MS) is one of the most common neurological disorders among the young adult population in the world and environmental factors are considered to be one of the factors contributing to MS risk and progression. Metals are important factors for maintenance and preservation of homeostasis and dysregulated metal homeostasis has been shown to cause various diseases including neurodegeneration. Heavy metals including arsenic (As), cadmium (Cd) and lead (Pb) are widely found in the environment and because of their toxic nature, they possess great danger for human health and are indicated in the etiology of various diseases. Metallothioneins (MTs) play important roles in metal homeostasis and detoxification of heavy metals. Up to date, there is no study investigated the relationships between MS, MTs and heavy metals in a single study, therefore, we investigated the possible relationship between these factors in MS patients. In this study, 50 subjects (20 healthy subjects and 30 MS patients) were included. Besides the demographic characteristics of the patients, plasma MT levels, blood Cd, As and Pb levels, as well as iron (Fe), cupper (Cu) and zinc (Zn) levels, were determined. Malondialdehyde (MDA) levels were investigated as a marker of oxidative stress. Statistical analysis was performed by using GraphPad Prism® 7.0 and a p value lower than 0.05 was considered as statistically significant. MT levels were slightly higher in MS group compared to control group (p > 0.05). As, Cd and Pb levels were significantly higher in the control subjects (p < 0.05). No differences in Fe, Cu and Zn levels between control and MS groups were present (p > 0.05). MDA levels were significantly higher in MS patients (p < 0.05). On the other hand, smoking was found to be a risk factor for MS (Relative risk = 1.294, 95% Confidence Intervals = 0.7961 - 1.999; p = 0.2727). In conclusion our results support relevance of MT and MDA levels in MS. Randomized, double-blinded, multi-centered, clinical studies with larger cohorts will be relevant to gain more insights about the relation between heavy metals, MT and MDA levels in MS. Key words: Arsenic, Cadmium, Heavy metals, Lead, Metallothionein, Multiple Sclerosis