Julia Arnold

Imbalance between sympathetic and sensory innervation in peritoneal endometriosis

To investigate possible mechanisms of pain pathophysiology in patients with peritoneal endometriosis, a clinical study on sensory and sympathetic nerve fibre sprouting in endometriosis was performed. Peritoneal lesions (n=40) and healthy peritoneum (n=12) were immunostained and analysed with anti-protein gene product 9.5 (PGP 9.5), anti-substance P (SP) and anti-tyrosine hydroxylase (TH), specific markers for intact nerve fibres, sensory nerve fibres and sympathetic nerve fibres, respectively, to identify the ratio of sympathetic and sensory nerve fibres. In addition, immune cell infiltrates in peritoneal endometriotic lesions were analysed and the nerve growth factor (NGF) and interleukin (IL)-1β expression was correlate with the nerve fibre density. Peritoneal fluids from patients with endometriosis (n=40) and without endometriosis (n=20) were used for the in vitro neuronal growth assay. Cultured chicken dorsal root ganglia (DRG) and sympathetic ganglia were stained with anti-growth associated protein 43 (anti-GAP 43), anti-SP and anti-TH. We could detect an increased sensory and decreased sympathetic nerve fibres density in peritoneal lesions compared to healthy peritoneum. Peritoneal fluids of patients with endometriosis compared to patients without endometriosis induced an increased sprouting of sensory neurites from DRG and decreased neurite outgrowth from sympathetic ganglia. In conclusion, this study demonstrates an imbalance between sympathetic and sensory nerve fibres in peritoneal endometriosis, as well as an altered modulation of peritoneal fluids from patients with endometriosis on sympathetic and sensory innervation which might directly be involved in the maintenance of inflammation and pain.

Evidence of neurotrophic events due to peritoneal endometriotic lesions

To investigate the neurotrophic properties of endometriosis, as well as the involvement of neurotrophic factors in the development of chronic pelvic pain in patients with endometriosis, we performed a prospective clinical study. The presence of neurotrophins was investigated in the peritoneal fluid (PF) of patients with peritoneal endometriotic lesions or adenomyosis, as well as from women with non-endometriotic adhesions and from women without endometriosis/adenomyosis/adhesions. The PF from patients with peritoneal endometriotic lesions was divided in three groups: asymptomatic endometriosis, minimal pain and severe pain. PF from patients with adenomyosis or with non-endometriotic adhesions and the control group were divided in patients without pain and with pain. Neurotrophin expression in PF was analyzed using Elisa and the neuronal growth assay with cultured chicken sensory ganglia (dorsal-root-ganglia, DRG) and sympathetic ganglia. PF from women with peritoneal endometriotic lesions overexpress nerve growth factor (NGF) and neurotrophin-3 (NT-3), but not brain derived neurotrophic factor (BDNF), whereas the PF of women with adenomyosis or adhesions seems to express normal amounts of these factors. Neurotrophin expression did not differ among the pain groups. Furthermore, the PF from patients with peritoneal endometriotic lesions induced a strong sensory and a marginal sympathetic neurite outgrowth, while the PF from women with adenomyosis and non-endometriotic adhesions induced an outgrowth similar to the control group. The induced neurite outgrowth could only be inhibited in DRG incubated with peritoneal endometriotic lesions. Interestingly, the outgrowth of sympathetic ganglia was inhibited in all studied groups. The present study suggests that only peritoneal endometriotic lesions lead to an increased release of NGF and NT-3 into the PF and that NGF modulates the nerve fiber growth in endometriosis.

Eutopic endometrium from women with endometriosis does not exhibit neurotrophic properties

The role of neurotrophins in eutopic endometrium from endometriosis-patients was investigated in a prospective study using immunofluorescence-staining, Western blot and a neuronal growth assay. The nerve growth factor is expressed in primary endometrial cell culture from women with and without endometriosis. Western blot analysis of endometrial biopsies or uterine fluid from patients with and without endometriosis shows no difference in the neurotrophin expression. We could not find a difference between patients with and without endometriosis with regards to the neurite outgrowth of sensory ganglia when treated with conditioned cultured medium or uterine fluid. This result refutes the assumed neurotrophic properties of eutopic endometrium of patients with endometriosis.

Neurotrophin Expression Is Not Affected in Uteri of Women with Adenomyosis

To investigate the involvement of neurotrophins and nerve fibres in the pathogenesis of adenomyosis, we performed a retrospective, clinical study. Hysterectomy specimens from 40 patients with histologically proven adenomyosis and from 20 patients without adenomyosis or endometriosis were used for immunohistochemical analysis. In order to investigate neurotrophic properties in adenomyosis, the antibodies against nerve growth factor (NGF), neurotrophin 3 (NT-3), the high-affinity NGF receptor (TrkA), the low-affinity neurotrophin receptor (p75NTR), the neuronal marker S100 (for myelinated nerve fibres) and protein gene product 9.5 (PGP9.5; for intact nerve fibres) were used. There was no significant difference in the NGF, NT-3 and p75NTR expression in the myometrium or endometrium between the adenomyosis and the control group. The nerve fibre density (S100, PGP9.5 and p75NTR) did not significantly differ between the adenomyosis and control group, the nerve fibre density of the adenomyosis group was tendentially decreased when compared with the nonporous control group. The present study suggests that endometrial and uterine neurotrophin expression and endometrial innervation are not altered in adenomyosis; however, women with adenomyosis or with adenomyosis/endometriosis tendentially had less myometrial nerve fibres than the control group.

Calcium-binding protein expression in peritoneal endometriosis-associated nerve fibres

Recent studies demonstrated the potential involvement of nerve fibres in the chronic inflammatory process of endometriosis. We aimed to characterize nerve fibres in the proximal and distal areas of the peritoneal endometriotic lesions in order to understand the chronic inflammatory process in endometriosis.