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)-1ß 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.

Immunohistochemical characterization of endometriosis-associated smooth muscle cells in human peritoneal endometriotic lesions.

BACKGROUND: Smooth muscle cells (SMC) are common components of endometriotic lesions. SMC have been characterized previously in peritoneal, ovarian and deep infiltrating endometriotic lesions and adenomyosis. The aim of this retrospective study was to investigate the extent of differentiation in endometriosis-associated SMC (EMaSMC) in peritoneal endometriotic lesions. METHODS: We obtained biopsies from peritoneal endometriotic lesions (n = 60) and peritoneal sites distant from the endometriotic lesion (n = 60), as well as healthy peritoneum from patients without endometriosis (control tissue, n = 10). These controls were hysterectomy specimens from patients without endometriosis or adenomyosis. Histopathological examination of peritoneal specimens using antibodies against oxytocin receptor (OTR), vasopressin receptor (VPR), smooth muscle myosin heavy chain (SM-MHC), estrogen receptor (ER) or progesterone receptor (PR) was performed. To identify SMC and their level of differentiation, antibodies for smooth muscle actin desmin and caldesmon were used. RESULTS: SMC were detected in all endometriotic lesions. SMC were more abundant in unaffected peritoneum of women with endometriosis (38%) compared with women without endometriosis (6%; P < 0.0001). Depending on the level of differentiation, SMC stained for SM-MHC, OTR, VPR, ER and PR. OTR was only detected in fully differentiated SMC. CONCLUSIONS: Identification of OTR, VPR, ER and PR leads to the hypothesis that the EMaSMC might be functionally active and possibly involved in the generation of pain associated with endometriosis.

Remodeling of estrogen-dependent sympathetic nerve fibers seems to be disturbed in adenomyosis.

OBJECTIVE: To investigate neuronal remodeling processes in the uterine innervation, particularly a remodeling of sympathetic nerve fibers, as well as the role of estrogen in this modulation in adenomyosis. DESIGN: Retrospective case-control study. SETTING: University hospital endometriosis center. PATIENT(S): Forty-two patients with histologically proven adenomyosis and 19 patients without adenomyosis. INTERVENTION(S): Endometrial and myometrial tissue were immunohistochemically analyzed to further characterize the uterine innervation. MAIN OUTCOME MEASURE(S): Immunohistochemical analysis was used to identify PGP 9.5-, substance P-, and tyrosine hydroxylase-positive nerve fibers. The expression of the aromatase cytochrome P450 was evaluated in uterine tissue, and the expression of the estrogen receptor (ER) -α and ERß in uterine nerve fibers was analyzed. RESULT(S): Adenomyotic lesions are not innervated. The density of sympathetic nerve fibers in the myometrium of women with adenomyosis is reduced when compared with the nonadenomyosis group. The aromatase expression in the myometrium of women with adenomyosis was increased when compared with the control group. The ERα/ERß ratio is in trend shifted to the ERα side in the myometrial tyrosine hydroxylase-positive nerve fibers in adenomyosis compared to the controls. CONCLUSION(S): The disruption of the modulation of the uterine sympathetic innervation seems to be an important aspect in the pathogenesis of adenomyosis. Estrogen and its receptors seem to play a crucial role in the depletion of myometrial sympathetic nerve fibers.

High lymph vessel density and expression of lymphatic growth factors in peritoneal endometriosis.

To investigate the occurrence of lymph vessels and lymphangiogenic growth factors in peritoneal lesions, we performed immunohistochemical staining of peritoneal lesions of 37 patients with antibodies against podoplanin (D2-40), lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1), prospero homeobox protein 1 (Prox-1), vascular epithelial growth factor (VEGF)-C/VEGF-D. Overall, 10 lesions were double stained against D2-40 and von Willebrand factor. The lymph vessel density in peritoneal lesion was significantly higher in comparison with healthy peritoneum. All lymph vessel makers could be detected, whereby the lymph vessel density of LYVE-1- and Prox-1-positive lymph vessels was significantly higher than the lymph vessel density of D2-40-positive lymph vessels. Endometriotic epithelial cells and stromal cells (SCs) showed a moderate-to-strong VEGF-C/VEGF-D expression. The VEGF-C-/VEGF-D-positive macrophages in endometriotic SCs could be observed. The lymphatic vasculature seems to form a further component of peritoneal lesions and could be involved in the inflammatory process. These data demonstrated a further step in the clarification of the pathogenesis of endometriosis.

Influence of nerve growth factor in endometriosis-associated symptoms.

To investigate the role of the nerve growth factor (NGF) in the development of dysmenorrhea/pelvic pain in patients with endometriosis, we performed a prospective, clinical, blind study. Peritoneal fluids (PFs) were obtained from patients with histologically proven endometriosis. Patients with endometriosis were divided into 7 different groups depending on their preoperative pain score and symptomatology: patients with no pain, patients with minimal pain (dysmenorrhea, pelvic pain, or both), and patients with severe pain (dysmenorrhea, pelvic pain, or both) and were used for the neuronal growth assay with cultured chicken dorsal root ganglia (DRG) and for Western blot analyses. Dorsal root ganglia were stained with anti-calcitonin gene-related peptide (CGRP) and anti-growth-associated protein 43 (GAP 43). Peritoneal fluids from patients with endometriosis induce neurite outgrowth. There was no significant difference in the outgrowth between the 7 pain groups. Western blot analyses showed a moderate NGF expression in the PFs from patients with endometriosis, without significant differences in the 7 pain groups. The present study suggests that the neurotrophic properties of endometriotic tissues are endometriosis- and not pain-associated.