Spinal macrophage migration inhibitory factor and high mobility group box 1 mediate persistent bladder pain

Area of Science:

• Neuroscience
• Pain Research
• Urology

Background:

• Protease activated receptor 4 (PAR4) activation can induce persistent bladder pain.
• Spinal macrophage migration inhibitory factor (MIF) and high mobility group box 1 (HMGB1) are implicated in inflammatory and neuropathic pain.
• The role of spinal MIF and HMGB1 in PAR4-induced persistent bladder pain is not fully understood.

Purpose of the Study:

• To investigate spinal changes in MIF and HMGB1 during persistent bladder pain.
• To determine if spinal MIF and HMGB1 antagonists can modulate PAR4-induced bladder pain.

Main Methods:

• Persistent bladder pain was induced in mice via repeated intravesical PAR4 activation.
• Spinal cord tissue was analyzed for c-fos, MIF, and HMGB1 expression using immunofluorescence, western blotting, and real-time PCR.
• Mice received intrathecal injections of MIF monoclonal antibody or HMGB1 inhibitor (glycyrrhizin) to assess pain modulation.

Main Results:

• PAR4 activation led to increased spinal c-fos and MIF, and decreased HMGB1.
• Intrathecal MIF antibody or glycyrrhizin treatment significantly reduced abdominal hypersensitivity.
• The analgesic effects of spinal treatments were temporary, diminishing after 6 hours.

Conclusions:

• Persistent bladder pain induced by PAR4 activation is associated with altered spinal MIF and HMGB1 levels.
• Spinal MIF and HMGB1 play a role in maintaining this type of bladder pain.
• Targeting spinal MIF and HMGB1 represents a potential therapeutic strategy for chronic bladder pain conditions.