Mechanical loading reduces inflammation-induced human osteocyte-to-osteoclast communication

Area of Science:

• Bone Biology
• Rheumatology
• Mechanobiology

Background:

• Rheumatoid arthritis (RA) causes bone loss through inflammation and immobilization.
• Mechanical loading typically prevents bone loss, but its effect in RA is unclear.

Purpose of the Study:

• To investigate if mechanical stimuli can reverse the effects of RA serum on osteocyte-osteoclast communication.
• To determine if mechanical loading impacts RA-induced changes in bone signaling.

Main Methods:

• Human osteocytes were treated with RA serum or control serum, followed by mechanical loading (pulsating fluid flow).
• Gene expression (RANKL, OPG, IL-6, etc.) and nitric oxide (NO) production were measured.
• Osteoclast formation was assessed using conditioned media from treated osteocytes.

Main Results:

• RA serum increased the RANKL/OPG ratio, promoting osteoclastogenesis, but mechanical loading nullified this effect.
• Mechanical loading increased nitric oxide production similarly in both RA and control serum groups.
• Conditioned media from RA serum-treated osteocytes enhanced osteoclast formation, an effect abolished by mechanical loading.

Conclusions:

• RA serum upregulates osteocyte-to-osteoclast communication, contributing to bone loss.
• Mechanical loading effectively counteracts this RA-induced upregulation.
• Mechanical stimuli hold potential for preventing osteoporosis in inflammatory diseases like RA.