Compound 48/80 increases bladder compliance by activating MMP-2 and inhibiting TIMP-2.

Area of Science:

• Urology
• Biochemistry
• Physiology

Background:

• Bladder dysfunction arises from disruptions in the bladder wall's extracellular matrix (ECM) and altered mechanical compliance.
• Compound 48/80 was previously shown to increase detrusor excitability and bladder wall mechanical compliance in a mast cell-independent manner.
• The mechanism by which compound 48/80 alters bladder mechanical compliance remained unclear.

Purpose of the Study:

• To investigate the hypothesis that compound 48/80 increases bladder wall mechanical compliance through the activation of matrix metalloproteinases (MMPs).

Main Methods:

• Ex vivo measurements of intravesical pressure, mechanical compliance, wall thickness, and permeability in mouse bladders using the Pentaplanar Reflected Image Macroscopy (PRIM) System and multiphoton microscopy.
• Assessment of MMP activity and tissue inhibitor of metalloproteinase (TIMP) activity using zymography.
• Inhibition studies using doxycycline (nonspecific MMP inhibitor) and ARP100 (MMP-2 inhibitor).

Main Results:

• Compound 48/80 increased bladder mechanical compliance and reduced wall thickness without affecting urothelial permeability.
• The observed increase in compliance was significantly inhibited by doxycycline and ARP100.
• Zymography revealed increased MMP-2 activity and decreased TIMP-2 activity in bladders treated with compound 48/80.

Conclusions:

• Compound 48/80 enhances bladder mechanical compliance via ECM breakdown, driven by the rapid activation of MMP-2 and concurrent inhibition of TIMP-2.
• These effects on compliance occur independently of changes in urothelial permeability, suggesting a novel receptor-mediated mechanism.
• The findings provide insight into the molecular mechanisms underlying compound 48/80-induced bladder changes and potential therapeutic targets for bladder dysfunction.