Objective
To evaluate neurotrophin (NT) expression in the endometrium of women with and without endometriosis
Design
Prospective, cross-sectional, translational study
Setting
Academic hospital
Patient(s)
Thirty-three reproductive age women undergoing laparoscopy for infertility, pelvic pain, intramural fibroids, or tubal ligation
Intervention(s)
Endometrial biopsies, protein microarrays, RT-PCR, ELISAs and Western blotting
Main Outcome Measures
Neurotrophin proteins and mRNAs in eutopic endometrial biopsies
Results
Among seven neurotrophic proteins detected on the antibody microarrays, RT-PCR analysis confirmed nerve growth factor (NGF), NT-4/5, and brain-derived neurotrophic factor (BDNF) mRNAs in endometrial tissue. Quantitative ELISAs revealed that NT-4/5 (806 ± 701 vs. 256 ± 190 pg/100 mg protein, P=0.04) and BDNF (121 ± 97 vs. 14 ± 11 ng/100 mg protein, P<0.01) concentrations were significantly higher in women with endometriosis. NGF (100 ± 74 vs. 93 ± 83 pg/100 mg protein) levels did not differ between cases and controls (P=0.83).
Conclusions
Neurotrophins are synthesized in situ within the endometrium. NT-4/5 and BDNF proteins were more concentrated in biopsies from endometriosis cases than controls, whereas NGF levels were similar. We hypothesize that the local production of NTs induces sensory innervation of endometrium of women with endometriosis. These NTs represent novel targets for the diagnosis and treatment of endometriosis.
Endometriosis implants are comprised of glandular and stromal elements, macrophages, nerves, and blood vessels and are commonly accompanied by pelvic pain. We propose that activated macrophages are recruited to and infiltrate nascent lesions, where they secrete proinflammatory cytokines, promoting the production of chemokines, neurotrophins, and angiogenic growth factors that sustain an inflammatory microenvironment. Immunohistochemical evaluation of endometriosis lesions reveals in situ colocalization of concentrated macrophages, brain-derived neurotrophic factor (BDNF), and nerve fibers. These observations were coupled with biochemical analyses of primary eutopic endometriosis stromal cell (EESC) cultures, which allowed defining potential pathways leading to the neuroangiogenic phenotype of these lesions. Our findings indicate that IL-1β potently (EC = 7 ± 2 ng/mL) stimulates production of EESC BDNF at the mRNA and protein levels in an IL-1 receptor-dependent fashion. Selective kinase inhibitors demonstrate that this IL-1β effect is mediated by c-Jun N-terminal kinase (JNK), NF-κB, and mechanistic target of rapamycin signal transduction pathways. IL-1β regulation of regulated on activation normal T cell expressed and secreted (RANTES), a prominent EESC chemokine, also relies on JNK and NF-κB. An important clinical implication of the study is that interference with BDNF and RANTES production, by selectively targeting the JNK and NF-κB cascades, may offer a tractable therapeutic strategy to mitigate the pain and inflammation associated with endometriosis.
Type 2 cancers have nearly twice the TAM density of type 1 cancers. This difference may be due to M1 macrophage predominance in the stroma of type 2 cancers.
Our results indicate that soy extract has a trophic effect on rat uterine structures. Treatment of ovariectomized rats with a concentrated soy extract in combination with conjugated estrogens had no addictive effect on the uterine response.
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