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BMC Physiol. 2017 May 25;17(1):6. doi: 10.1186/s12899-017-0032-9.

Disulfide high mobility group box-1 causes bladder pain through bladder Toll-like receptor 4.

Author information

1
Research and Development, Lexington Veterans Affairs Medical Center, 1101 Veterans Drive, Room C-327, Lexington, Kentucky, 40502, USA.
2
Department of Physiology, University of Kentucky, Lexington, Kentucky, USA.
3
Saha Cardiovascular Research Center, University of Kentucky, Lexington, Kentucky, USA.
4
Present Address: Department of Molecular Pharmacology and Therapeutics, Loyola University Chicago, Maywood, Illinois, USA.
5
Department of Natural Sciences, St. Petersburg College, St. Petersburg, Florida, USA.
6
Research and Development, Lexington Veterans Affairs Medical Center, 1101 Veterans Drive, Room C-327, Lexington, Kentucky, 40502, USA. pedro.vera@va.gov.
7
Department of Physiology, University of Kentucky, Lexington, Kentucky, USA. pedro.vera@va.gov.
8
Department of Surgery, University of Kentucky, Lexington, Kentucky, USA. pedro.vera@va.gov.

Abstract

BACKGROUND:

Bladder pain is a prominent symptom in several urological conditions (e.g. infection, painful bladder syndrome/interstitial cystitis, cancer). Understanding the mechanism of bladder pain is important, particularly when the pain is not accompanied by bladder pathology. Stimulation of protease activated receptor 4 (PAR4) in the urothelium results in bladder pain through release of urothelial high mobility group box-1 (HMGB1). HGMB1 has two functionally active redox states (disulfide and all-thiol) and it is not known which form elicits bladder pain. Therefore, we investigated whether intravesical administration of specific HMGB1 redox forms caused abdominal mechanical hypersensitivity, micturition changes, and bladder inflammation in female C57BL/6 mice 24 hours post-administration. Moreover, we determined which of the specific HMGB1 receptors, Toll-like receptor 4 (TLR4) or receptor for advanced glycation end products (RAGE), mediate HMGB1-induced changes.

RESULTS:

Disulfide HMGB1 elicited abdominal mechanical hypersensitivity 24 hours after intravesical (5, 10, 20 μg/150 μl) instillation. In contrast, all-thiol HMGB1 did not produce abdominal mechanical hypersensitivity in any of the doses tested (1, 2, 5, 10, 20 μg/150 μl). Both HMGB1 redox forms caused micturition changes only at the highest dose tested (20 μg/150 μl) while eliciting mild bladder edema and reactive changes at all doses. We subsequently tested whether the effects of intravesical disulfide HMGB1 (10 μg/150 μl; a dose that did not produce inflammation) were prevented by systemic (i.p.) or local (intravesical) administration of either a TLR4 antagonist (TAK-242) or a RAGE antagonist (FPS-ZM1). Systemic administration of either TAK-242 (3 mg/kg) or FPS-ZM1 (10 mg/kg) prevented HMGB1 induced abdominal mechanical hypersensitivity while only intravesical TLR4 antagonist pretreatment (1.5 mg/ml; not RAGE) had this effect.

CONCLUSIONS:

The disulfide form of HMGB1 mediates bladder pain directly (not secondary to inflammation or injury) through activation of TLR4 receptors in the bladder. Thus, TLR4 receptors are a specific local target for bladder pain.

KEYWORDS:

HMGB1; RAGE; TLR4; abdominal mechanical hypersensitivity; bladder pain; urothelium

PMID:
28545586
PMCID:
PMC5445386
DOI:
10.1186/s12899-017-0032-9
[Indexed for MEDLINE]
Free PMC Article

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