Overnight Changes in Cytokines and Cortisol in Rheumatoid Arthritis
Author Information
Author(s): Perry M G, Kirwan J R, Jessop D S, Hunt L P
Primary Institution: University of Bristol
Hypothesis
To investigate overnight variations in absolute values and patterns of cytokines including interleukin 6 (IL6) and tumour necrosis factor α (TNFα) in rheumatoid arthritis (RA), and to relate any changes to those occurring in blood cortisol.
Conclusion
The mean IL6 and cortisol concentrations showed a significant overnight variation, with IL6 rising approximately 3 hours before cortisol.
Supporting Evidence
- IL6 concentration rose significantly from 35 pg/ml at 22:00 to 64 pg/ml at 07:15.
- Cortisol concentration rose significantly overnight from 57 ng/ml at 01:00 to 229 ng/ml at 07:15.
- IL6 began to rise approximately 3 hours before cortisol in most participants.
Takeaway
People with rheumatoid arthritis have higher levels of a substance called IL6 in the morning, which happens before their cortisol levels rise.
Methodology
Blood samples were obtained at 13 time points overnight from 16 patients with active RA.
Potential Biases
Potential bias from the use of an intravenous cannula which may affect cytokine levels.
Limitations
The study had a relatively small sample size and was only conducted overnight, not over a full 24-hour period.
Participant Demographics
8 men and 8 women, mean age 59 years, mean disease duration 10 years.
Statistical Information
P-Value
p<0.001
Confidence Interval
95% CI for IL6: 34.5 pg/ml to 64.4 pg/ml; for cortisol: 56.9 ng/ml to 228.7 ng/ml.
Statistical Significance
p<0.001
Digital Object Identifier (DOI)
Want to read the original?
Access the complete publication on the publisher's website