title: A Local Inflammatory Renin-Angiotensin System Drives Sensory Axon Sprouting in Provoked Vestibulodynia.
abstract: Vestibulodynia is a form of provoked vulvodynia characterized by profound tenderness, hyperinnervation, and frequently inflammation within well-defined areas of the human vestibule. Previous experiments in animal models show that inflammatory hypersensitivity and hyperinnervation occur in concert with establishment of a local renin-angiotensin system (RAS). Moreover, mechanical hypersensitivity and sensory axon sprouting are prevented by blocking effects of angiotensin II on angiotensin II receptor type 2 (AT2) receptors. This case-control study assessed whether a RAS contributes to hyperinnervation observed in human vestibulodynia. Vestibular biopsies from asymptomatic controls or patients' nontender areas showed moderate innervation and small numbers of inflammatory cells. In women with vestibulodynia, tender areas contained increased numbers of mechanoreceptive nociceptor axons, T-cells, macrophages, and B-cells, whereas mast cells were unchanged. RAS proteins were increased because of greater numbers of T cells and B cells expressing angiotensinogen, and increased renin-expressing T cells and macrophages. Chymase, which converts angiotensin I to angiotensin II, was present in constant numbers of mast cells. To determine if tender vestibular tissue generates angiotensin II that promotes axon sprouting, we conditioned culture medium with vestibular tissue. Rat sensory neurons cultured in control-conditioned medium showed normal axon outgrowth, whereas those in tender tissue-conditioned medium showed enhanced sprouting that was prevented by adding an AT2 antagonist or angiotensin II neutralizing antibody. Hypersensitivity in provoked vestibulodynia is therefore characterized by abnormal mechanonociceptor axon proliferation, which is attributable to inflammatory cell-derived angiotensin II (or a closely related peptide) acting on neuronal AT2 receptors. Accordingly, reducing inflammation or blocking AT2 represent rational strategies to mitigate this common pain syndrome.
  
  
  
  This study provides evidence that local inflammation leads to angiotensin II formation, which acts on the AT2 to induce nociceptor axon sprouting in vulvodynia. Preventing inflammation and blocking AT2 therefore present potential pharmacological strategies for reducing vestibular pain.
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Liao
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Anuradha
authors.initials: A
authors.lastname: Chakrabarty
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Ying
authors.initials: Y
authors.lastname: Mu
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas.
authors.forename: Aritra
authors.initials: A
authors.lastname: Bhattacherjee
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon.
authors.forename: Martha
authors.initials: M
authors.lastname: Goestch
authors.affiliation: Department of Obstetrics and Gynecology, Oregon Health & Science University, Portland, Oregon.
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Leclair
authors.affiliation: Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, Kansas. Electronic address: psmith@kumc.edu.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Smith
mesh_terms: D000293:Adolescent; D000328:Adult; D057912:Angiotensin II Type 2 Receptor Blockers / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000473:pathology*; D001402:B-Lymphocytes / Q000473:pathology; D016022:Case-Control Studies; D002478:Cells, Cultured; D005260:Female; D005727:Ganglia, Spinal / Q000473:pathology; D006801:Humans; D006930:Hyperalgesia / Q000209:etiology; D007093:Imidazoles / Q000494:pharmacology; D007249:Inflammation / Q000209:etiology* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D012084:Renin-Angiotensin System / Q000502:physiology*; D011984:Sensory Receptor Cells / Q000187:drug effects / Q000473:pathology*; D013601:T-Lymphocytes / Q000473:pathology; D014722:Vestibule, Labyrinth / Q000378:metabolism / Q000473:pathology; D056650:Vulvodynia / Q000150:complications* / Q000503:physiopathology*; D055815:Young Adult
chemical_list: D057912:Angiotensin II Type 2 Receptor Blockers; D007093:Imidazoles; D009419:Nerve Tissue Proteins; D011725:Pyridines; C073402:PD 123319
keywords: Vulvodynia; angiotensin II; cell culture; inflammation; neural plasticity; peripheral nociceptors; quantitative histology