Circulating levels of cytokines are increased in restless legs syndrome

Sleep Breath. 2021 Sep;25(3):1581-1585. doi: 10.1007/s11325-020-02218-7. Epub 2020 Oct 21.

Abstract

Background: Restless legs syndrome [RLS] is known as a disease of iron and dopaminergic dysregulation but inflammatory processes might also have a role in the pathogenesis. In this study, we compared the circulating levels of hsCRP, IL-1β, IL-6, and TNF-α in patients with primary restless legs syndrome [RLS] and healthy control subjects.

Methods: We prospectively included 29 patients with primary RLS and 65 healthy controls [HC], all age-sex matched. The diagnosis of RLS was established using international guidelines. IRLSSG Severity Scale was used to evaluate the severity of RLS. Plasma levels of hsCRP, IL-1β, IL-6, and TNF-α were measured in all participants.

Results: The mean age of patients was 37.8 ± 11.3 and 52% of RLS group were women. Serum IL-1β, IL-6, and TNF-α levels of the patient group were statistically significantly higher compared to HC [p < 0.001 for all variables]. Plasma levels of hsCRP did not differ between groups. There were 8 patients with mild RLS [28%], 13 patients with moderate RLS [45%], and 8 patients with severe RLS [28%]. Only IL-6 values were significantly different between the groups. In the severe group, the value of IL-6 was significantly higher than in the other groups [p: 0.03].

Conclusion: These results showing higher circulating levels of inflammatory cytokines in patients with RLS support the notion that inflammation may be involved in the pathogenesis of primary RLS. However, it is necessary to perform further studies to determine if this finding is a cause or an effect.

Keywords: Interleukin-1β; Interleukin-6; Restless legs syndrome; TNF-α.