022 Cytokines as correlates of reported symptoms in disorders of hypersomnolence

Abstract

Introduction Cytokines are known for their role in inflammation, and more recently in sleepiness and fatigue. There is a paucity of data regarding cytokines in Idiopathic Hypersomnia (IH) and Narcolepsy Type 2 (NT2) as defined by the International Classifications of Sleep Disorders-Third Edition. Additionally the heterogenous cohort of patients with excessive daytime sleepiness (EDS), but do not meet criteria for a sleep disorder, has not been studied separately from IH patients. Methods The study cohort was a convenience sample evaluated at a single tertiary-care sleep center between 2016 and 2019. Diagnoses were IH, NT2, EDS, and controls (based on sleep laboratory testing). The following cytokines were measured using the Mesoscale U-PLEX biomarker assay: G-CSF, IFN-γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, MCP-1, and TNF-α. Demographic data and survey data pertaining to sleepiness, depression, and sleep inertia were available for all. Results The study cohort consisted of 22 controls, 26 patients with EDS, 51 patients with IH, and 12 patients with NT2. There were no significant differences between diagnosis and any cytokine. Pearson correlations showed significant negative correlations between G-CSF concentrations with depression (p=0.05) and sleep inertia (p<0.01) in patients but not controls. In controls, hours slept per week positively correlated with G-CSF (p=0.05), but this was not true in patients with EDS, IH, or NT2. IL-8 level was negatively correlated with reported sleep inertia in sleepy patients (p=0.05), but not controls. Conclusion Though differences in cytokines levels between diagnostic groups did not reach significance, several cytokines correlated with severity of reported symptoms in disorders of hypersomnolence. G-CSF and IL-8 may serve as a biomarker for symptoms of depression and sleep inertia in sleepiness disorders, and thus could be a targeted for therapies. Support (if any) Hypersomnia Foundation Grant