P19-03IMMUNE ACTIVATION ENHANCES EPITHELIAL NERVE GROWTH IN LOCALIZED PROVOKED VULVODYNIA

19. Vulvar diseases and neoplasia
P. Tommola 1, L. Unkila-Kallio 1, A. Paetau 2, S. Meri 3, E. Kalso 4, J. Paavonen 1.
1Obstetrics and Gynecology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland (Finland), 2Pathology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland (Finland), 3Bacteriology and Immunology, Haartman Institute, University of Helsinki and Helsinki University Hospital, Helsinki, Finland (Finland), 4Pain Clinic, Anesthesiology, Intensive Care, and Pain Medicine, University of Helsinki and Helsinki University Hospital, Helsinki, Finland (Finland)

Background / Objectives

Localized provoked vulvodynia (LPV) manifests with allodynia in the vulvar mucosa. The exact mechanisms resulting in the altered pain sensation are unknown. Generation of the pain may be due to activation of the neuroinflammatory pathways.Thus, we wanted to study whether expression of intraepithelial nerve fibers (IENF) and expression of nerve growth factor (NGF) are related to immune activation in LPV.  


Methods

Vestibular mucosal specimens were obtained from 27 patients with severe LPV treated by vestibulectomy and from 15 controls. We employed antibodies against the protein gene product 9.5 (PGP9.5), the neuron specific neurofilament (NF2F11) and nerve growth factor (NGF) for immunohistochemistry to detect IENFs and expression of NGF positive immune cells in the vestibular mucosa. For PGP9.5 positive IENFs we determined the linear density (fiber counts per mm of the outer epithelial surface). NF2F11 positivity was defined as presence or absence of IENFs. NGF was evaluated by counting the staining positive immune cells. Antibodies against CD20 (B lymphocytes) and CD3 (T lymphocytes) were used to identify mucosal areas with increased density of B lymphocytes and the presence of germinal centers, i.e. signs of immune activation. B cell activation index (BAI) was used to describe the overall intensity of B cell infiltration. Mann-Whitney U-test or Wilcoxon signed ranks test and chi²-test or Fischer’s exact test were used for statistical analyses.


Results

We found more PGP9.5 positive IENFs in LPV than in controls, p=0.006. NF2F11 positive IENFs were found in 17 (63.0%) of 27 LPV cases and in none of the controls. The occurrence of IENFs was more common in samples with more pronounced immune activation. NGF positive immune cells were more numerous in the mucosal areas with high B cell infiltration and IENFs than in the areas without. Glandular epithelium was identified in 14 LPV samples. PGP9.5 positive nerve fibers were found at significantly higher densities in glands surrounded by B cell infiltrations than in glands without B cells, p=0.013.  Also, NF2F11 fiber positivity in the glandular epithelium was associated with immune activation. 


Conclusion

Excessive epithelial nerve growth in LPV is associated with increased B cell infiltration and NGF positivity. This supports the fundamental role of immune activation in LPV.


References