INTRODUCTION: Inflammatory bowel disease (IBD) might be accompanied by emotional disturbances. Circadian rhythm genes, such as brain and muscle ARNT‑Like 1 (BMAL1), circadian locomotor output cycles kaput (CLOCK), neuronal PAS domain protein 2 (NPAS2), or nuclear receptor subfamily 1 group D member 1 (NR1D1) are related to inflammation and psychiatric symptoms that might modulate their expression.
OBJECTIVES: The study aimed to compare the expression of the BMAL1, CLOCK, NPAS2, NR1D1 mRNA in IBD patients and healthy controls (HCs). We evaluated the association between the gene expression and the disease severity, antitumor necrosis factor (TNF) therapy, sleep quality, insomnia, and depression.
PATIENTS AND METHODS: A total of 81 IBD patients and 44 HCs were recruited and classified according to the disease activity and IBD type (ulcerative colitis [UC] or Crohn disease [CD]). The participants filled out questionnaires assessing their sleep quality, daytime sleepiness, insomnia, and depression. Venous blood samples were collected, and the IBD patients on the anti‑TNF therapy had their blood drawn before and after 14 weeks of the treatment.
RESULTS: In comparison with HCs, the IBD group had decreased expression of all studied genes apart from the BMAL1 gene. UC individuals with exacerbation had decreased expression of the CLOCK and the NPAS2 genes, as compared with the remission group. UC severity negatively correlated with the CLOCK, NPAS2, and NR1D1 mRNA levels. The IBD participants with depression symptoms had a decreased expression of the CLOCK and the NR1D1 genes, as compared with those without mood disturbances. Poor sleep quality was associated with a decreased expression of the NR1D1 gene. Biologic treatment decreased the expression of the BMAL1 gene.
CONCLUSIONS: Disruption of the clock gene expression might constitute a molecular background of sleep disorders and depression in IBD and might contribute to UC exacerbation.
