Objective:

To investigate the effects of inflammatory arthritis on circadian rhythms and locomotor activity in a mouse model of rheumatoid arthritis.

Approach:

• Mouse Model: Utilized the K/BxN serum transfer arthritis (STA) mouse model to study the progression of rheumatoid arthritis.
• Locomotion Monitoring: Employed continuous actigraphy using passive infrared sensors to monitor locomotion throughout the disease course.
• DEX Treatment: Administered dexamethasone (DEX) to assess its impact on disease progression and circadian rhythms.
• Ankle Thickness Measurement: Measured ankle thickness to evaluate disease activity and progression.
• Bioluminescence Studies: Conducted bioluminescence studies on tissue-specific circadian clocks in response to inflammatory arthritis.

Key Findings:

• Total daily activity serves as a sensitive measure of disease state in inflammatory arthritis.
• Inflammatory arthritis disrupts local circadian clocks in affected joints while preserving central diurnal timing.
• Locomotion declines during arthritis, indicating reduced daily movement.

Interpretation:

The study indicates that while central circadian rhythms remain intact, local disruptions occur in the circadian clocks of arthritic joints.

Limitations:

• The study primarily uses a mouse model, which may not fully replicate human RA.
• Methodological approaches may limit the ability to capture the full diurnal nature of the disorder.

Conclusion:

Continuous monitoring of locomotor activity provides insights into the progression of inflammatory arthritis.