Evaluation of circadian phenotypes utilizing fibroblasts from patients with circadian rhythm sleep disorders

A Hida,M Kobayashi,A Usui,H Kusanagi,S Kitamura,Y Ohsawa,Y Motomura,Y Kamei,N Ayabe,K Matsui,Y Inoue,K Mishima,K Nakazaki

doi:10.1038/tp.2017.75

Abstract

We evaluated the circadian phenotypes of patients with delayed sleep–wake phase disorder (DSWPD) and non-24-hour sleep–wake rhythm disorder (N24SWD), two different circadian rhythm sleep disorders (CRSDs) by measuring clock gene expression rhythms in fibroblast cells derived from individual patients. Bmal1-luciferase (Bmal1-luc) expression rhythms were measured in the primary fibroblast cells derived from skin biopsy samples of patients with DSWPD and N24SWD, as well as control subjects. The period length of the Bmal1-luc rhythm (in vitro period) was distributed normally and was 22.80±0.47 (mean±s.d.) h in control-derived fibroblasts. The in vitro periods in DSWPD-derived fibroblasts and N24SWD-derived fibroblasts were 22.67±0.67 h and 23.18±0.70 h, respectively. The N24SWD group showed a significantly longer in vitro period than did the control or DSWPD group. Furthermore, in vitro period was associated with response to chronotherapy in the N24SWD group. Longer in vitro periods were observed in the non-responders (mean±s.d.: 23.59±0.89 h) compared with the responders (mean±s.d.: 22.97±0.47 h) in the N24SWD group. Our results indicate that prolonged circadian periods contribute to the onset and poor treatment outcome of N24SWD. In vitro rhythm assays could be useful for predicting circadian phenotypes and clinical prognosis in patients with CRSDs.

Highlights

advanced sleep–wake phase disorder (ASWPD) is characterized by extremely early involuntary sleep timing, whereas delayed sleep–wake phase disorder (DSWPD) is characterized by significantly delayed sleep timing, and non-24-hour sleep–wake rhythm disorder (N24SWD) has sleep timing that occurs with a 30 min to 1 h delay each day
Patients with Circadian rhythm sleep disorders (CRSDs) are mostly treated with chronotherapy, in which intense light exposure or melatonin administration is performed during the phase-advance or phasedelay portion, respectively, of the sleep–wake cycle
The Bmal1-luc rhythms were measured in the fibroblast cells derived from patients with DSWPD, patients with N24SWD and control subjects

Summary

INTRODUCTION

Circadian rhythm sleep disorders (CRSDs) are defined by persistent or recurrent disturbed sleep–wake patterns and consist of several subtypes including advanced sleep–wake phase disorder (ASWPD), delayed sleep–wake phase disorder (DSWPD), and non-24-hour sleep–wake rhythm disorder (N24SWD).[1,2,3,4] ASWPD is characterized by extremely early involuntary sleep timing, whereas DSWPD is characterized by significantly delayed sleep timing, and N24SWD has sleep timing that occurs with a 30 min to 1 h delay each day. The forced desynchrony protocol is costly and laborious,[12,13] and different approaches that can provide more convenient and feasible methods of evaluating circadian phenotypes in a clinical setting are needed. Surrogate measurement techniques, such as using cultured cells derived from biopsy samples of an individual, have been developed and tested for assessing circadian phenotypes.[14,15,16,17,18,19]. 2 N24SWD by evaluating Bmal1-luciferase (Bmal1-luc) rhythms in skin fibroblast cells from individual patients

MATERIALS AND METHODS

RESULTS

DISCUSSION