Mast cell-derived histamine mediates cystitis pain

Area of Science:

• Immunology
• Neuroscience
• Urology

Background:

• Mast cells are implicated in inflammation and pain, but their direct role in pelvic pain, particularly in interstitial cystitis (IC), remains unclear.
• Interstitial cystitis (IC) is characterized by debilitating pelvic pain of unknown origin, often without overt inflammation, but with increased mast cells in the bladder.
• This study investigates the direct role of mast cells in mediating pelvic pain using a murine model of IC.

Purpose of the Study:

• To elucidate the mechanisms by which mast cells contribute to pelvic pain in a murine model of interstitial cystitis (IC).
• To determine the specific molecular pathways, including histamine and tumor necrosis factor alpha (TNF), involved in mast cell-mediated pain and bladder pathophysiology.
• To identify potential therapeutic targets for pain relief in IC and related chronic pain conditions.

Main Methods:

• Utilized a murine model of pseudorabies virus (PRV)-induced neurogenic cystitis to study pelvic pain and bladder pathophysiology.
• Employed mast cell-deficient mice and bone marrow reconstitution to assess the necessity of mast cells in pain development.
• Investigated the roles of tumor necrosis factor alpha (TNF), TNF receptors, histamine receptor H1R, and histamine receptor H2R in mediating pain and bladder dysfunction.

Main Results:

• PRV-induced pelvic pain and bladder pathophysiology were abolished in mast cell-deficient mice, with restoration upon wild-type bone marrow reconstitution.
• Pelvic pain occurred normally in TNF- and TNF receptor-deficient mice, indicating TNF is not essential for pain mediation.
• Disruption of histamine receptors H1R or H2R significantly attenuated pelvic pain, while bladder pathophysiology remained unaffected.

Conclusions:

• Mast cells directly promote cystitis-associated pain and bladder pathophysiology via distinct pathways involving histamine and TNF, respectively.
• Pelvic pain in this model is separable from inflammation and bladder pathology.
• Histamine receptors (H1R and H2R) are identified as direct therapeutic targets for managing pain in interstitial cystitis and other chronic pain conditions.