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

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.

Methods

  • 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.

Results

  • 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).

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