Expression of circadian clock genes in leukocytes of patients with Meniere's disease

Objectives The underlying etiology of Meniere's disease (MD) is not completely clear, but the precipitated triggers may alter the circadian clock in patients with MD. This study aims to survey the expression of circadian clock genes in peripheral blood (PB) leukocytes of MD patients. Methods We investigated the expression of nine circadian clock genes in the PB leukocytes of patients with MD and normal controls using real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Results We observed significantly lower expression of PER1 gene and higher expression of CLOCK gene in MD patients than those in normal controls (p < 0.05). PER1 did not associate with the degree of dizziness handicap in the patients with MD, but a lower expression of PER1 was significantly correlated with higher pure tone average (PTA) and speech reception threshold of the affected ear (p < 0.05). Patients with PTA > 30 dB had significantly lower PER1 expression than those with PTA <= 30 dB in the affected ear (p < 0.05). Our qRT-PCR result was validated by fewer positively stained leukocytes for PER1 protein in the MD patients using the immunocytochemical study. Conclusion Our study implies the alteration of the circadian clock in patients with MD. In particular, the downregulation of PER1 correlated with the degree of hearing loss in the affected ear. PER1 in PB leukocytes may be a potential marker for the progression of hearing loss in MD.