Disruption of rhythms of molecular clocks in primary synovial fibroblasts of patients with osteoarthritis and rheumatoid arthritis, role of interleukin1 beta and tumor necrosis factor Full Text
Arthritis Research & Therapy, 05/25/2012

Haas S et al. – Rhythmicity is not present in primary OASF and RASF, which is unexpected because fibroblasts usually demonstrate perfect rhythms during several days. This might lead to uncoupling of important cellular pathways.

• Presence of BMAL–1, CLOCK, Period 1, and Period 2 proteins in synovial tissue was investigated by immunofluorescence.
• Presence of mRNA of molecular clocks was studied during 72hr by qPCR.
• Characteristics of rhythms were studied with time series analysis.

• BMAL–1, CLOCK, Period 1, and Period 2 proteins were abundantly present in synovial tissue of osteoarthritis (OA), rheumatoid arthritis (RA), and controls.
• Receiving synovial tissue at different operation time points during the day (8.00am–4.00pm) did not reveal a rhythm of BMAL–1 or Period 1 protein.
• In OASF and RASF, no typical rhythm curve of molecular clock mRNA was observed.
• Time series analysis identified a first peak between 2 and 18 hours after synchronization but a period was not detectable due to loss of rhythm.
• TNF inhibited mRNA of CLOCK, Period 1, and Period 2 in OASF, while IL–1beta and TNF increased these factors in RASF.
• This was supported by dose–dependently increased levels in MH7A RA fibroblasts.
• In RASF, IL 1beta and TNF shifted the first peak of BMAL–1 mRNA to later time points (8hr to 14hr).