Reduced serum interleukin-2 associates with higher motor severity and along with CD4 T cell alterations may be an early event in isolated REM Sleep Behaviour Disorder.

BACKGROUND

Emerging evidence indicates that peripheral immune changes occur in patients with isolated REM sleep behaviour disorder (iRBD) and may contribute to the conversion of this dream enactment disorder to a neurodegenerative synucleinopathy such as Parkinson's disease, dementia with Lewy bodies or multiple system atrophy. However, with only a limited number of studies conducted, the extent to which immune changes occur across diverse iRBD cohorts remains to be determined.

OBJECTIVES

We therefore aimed to assess peripheral immune changes in an Australian cohort of iRBD patients (n = 65) compared to controls (n = 35).

METHODS

A 9-plex cytokine assay was used to measure serum levels of IFNγ, IL-10, IL-12, IL-17A, IL-1β, IL-2, IL-4, IL-6 and TFNα. Flow cytometry was used to assess T cell populations in the same participants.

RESULTS

Exploratory analyses revealed lower levels of the T cell regulating cytokine interleukin 2 (IL-2) in participants with iRBD, along with lower frequencies of CD4 T cells positive for IL-2, IL-4 and IL-10.

CONCLUSIONS

These results add to evidence of immune alterations in iRBD and suggest that dysregulation of cytokines with anti-inflammatory properties may be an early event that could associate with subsequent development of a neurodegenerative synucleinopathy.