Current Protein and Peptide Science - Volume 18, Issue 2, 2017

Early studies often claimed that autonomic nerves were unimportant for uterine function, since denervation of the uterus had little effects on reproductive success. In 1979, Thorbert wrote, “It seems unlikely that Nature has equipped the uterus with a complex innervation merely as a structural ornament. Our ignorance in this area may be rather due to defects in methods of study”. Investigations carried out over the last four decades proved that Thorbert’s words were correct, because it is now clear that autonomic and sensory nerves regulate many critical uterine functions. However, the most remarkable aspect of uterine innervation is its capacity to change in response to physiological fluctuations in levels of sex hormones, as those accompanying pregnancy, the sex cycle and puberty. The present review provides an overview about how sex hormones influence uterine innervation. Data are presented about how this physiological plasticity is mimicked by exogenous administration of sex hormones, particularly estrogen. We will review recent developments illustrating the complex multifactorial mechanisms regulating uterine neural plasticity and the nature of molecular signals involved. Finally, we will go through recent findings pointing to the relevance of uterine innervation in gynecological diseases leading to pain and infertility.

Cervical remodeling (CR) is a complex process, which, in part, is believed to be induced by physiological inflammation. Even though the female reproductive tissues are richly innervated by nerves from the parasympathetic pelvic autonomic ganglia, sensory dorsal root and nodose ganglia, their roles (neuronal factors) in this process (CR) has been largely attributed to sex steroid hormones, until recently. Here, we discuss the interaction between neuropeptides derived from peripheral nerves associated with uterine cervix and estrogen, and their likely impact on cervical remodeling. It is likely that these neuronal factors, under the influence of estrogen, could induce physiological inflammation during cervical remodeling by promoting the expression of vascular endothelial growth factor, among other factors.

Wound healing is the process by which a complex cascade of biochemical events is responsible of the repair the damage. In vivo, studies in humans and mice suggest that healing and post-healing heterogeneous behavior of the surgically wounded myometrium is both phenotype and genotype dependent. Uterine wound healing process involves many cells: endothelial cells, neutrophils, monocytes/macrophages, lymphocytes, fibroblasts, myometrial cells as well a stem cell population found in the myometrium, myoSP (side population of myometrial cells). Transforming growth factor beta (TGF-β) isoforms, connective tissue growth factor (CTGF), basic fibroblast growth factor (bFGF), platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), and tumor necrosis factor alpha (TNF-α) are involved in the wound healing mechanisms. The increased TGF- β1/β3 ratio reduces scarring and fibrosis. The CTGF altered expression may be a factor involved in the abnormal scars formation of low uterine segment after cesarean section and of the formation of uterine dehiscence. The lack of bFGF is involved in the reduction of collagen deposition in the wound site and thicker scabs. The altered expression of TNF-α, VEGF, and PDGF in human myometrial smooth muscle cells in case of uterine dehiscence, it is implicated in the uterine healing process. The over-and under-expressions of growth factors genes involved in uterine scarring process could represent patient’s specific features, increasing the risk of cesarean scar complications.

Fibroids or myomas involve large proportion of women of reproductive age. The myoma formation starts from the transformation of the myometrium, causing the progressive formation of a pseudocapsule, which is made of compressed muscle fibers. Numerous studies investigated on myoma pseudocapsule anatomy, discovering many neurotransmitters and neuropeptides, as a neurovascular bundle, influencing myometrial physiology. These substances have a positive impact on wound healing and muscular restoring, also playing a role in sexual and reproductive function. Based on investigations, a distinct surgical technique evolved, called “intracapsular myomectomy”, meaning myoma removal from its pseudocapsule, which enables protection of the myoma pseudocapsule, containing neuropeptides and neurofibers involved in physiological myometrial healing. This technique, performed by a gentle myoma enucleating by stretching from myometrium and sparing pseudocapsule, reduces surgical trauma caused by iatrogenic myoma pseudocapsule damage. Intracapsular myomectomy meets the basic surgical anatomy principle: myoma is removed by a bloodless, precise and careful dissection sparing myometrium, as much as possible. The rationale of intracapsular myomectomy should be applied to all myoma removals; therefore, it has been used for both laparoscopic and laparotomic myomectomy, as well as for cesarean myomectomy. Scientific research is still seeks to clarify some reports of myomas with infertility, especially in the case of intramural myomas, but it is clear that in the case of performing myomectomy, it must do by the described intracapsular technique. This enables myometrial preservation, especially peripherally to myoma bed, promoting myometrial healing after myoma removal.

Human female reproductive system is closely dependent by hormonal stimulation. Anyway it is now commonly stated that autonomic innervation system regulates, along with hormonal stimulation, the uterine physiology. Cholinergic and adrenergic innervations have a critical role in mediating input to the uterus, but other neurotransmitters and neuropeptides exist that influence uterine physiology, as well. In the present investigation, we analyzed the uterine distribution of a large set of neurotransmitters, focusing on adrenergic, noradredenergic, acetylcholine (AChE) positive, dopaminergic, serotoninergic and peptidergic neurofibers; among these latter, we focused on those releasing prolattine, enkephalines (ENKs), Vasoactive Intestinal Polypeptide (VIP), substance P (SP) and oxytocine. Authors demonstrate the differential localization of these neurofibers in non pregnant uterine fundus, corpus and cervix, sampling myometrial assays of 31 patients submitted to hysterectomy. In fundus uteri, we observed a prevalence of prolactinergic (32.1 ± 1.4 Conventional Unit, C.U.) and adrenergic (36.4 ± 4.5 C.U.) neurofibers; in uterine body VIP positive neurofibers (32.6 ± 4.8 C.U.) and prolactinergic neurofibers (30.3 ± 1.2 C.U.) were the most represented. In uterine cervix, we detected the highest concentration of all the neurofibers analysed, with enkephalinergic neurofibers (94 ± 1.7 C.U.), oxitocinergic neurofibers (72.1 ± 5.1 C.U.), SP positive neurofibers (66.1 ± 4.4 C.U.), acetylcholine positive neurofibers (64.5± 3.6 C.U.), serotoninergic neurofibers (56.4 ± 3.9 C.U.) and VIP positive neurofibers (58.3 ± 5.2 C.U.) being the most expressed. This study demonstrates that uterine cervix harbors a higher concentration of almost all neurotransmitters, compared to the other two uterine anatomic sites. The uterine cervix is largely involved during pregnancy and labor, and the rich neurotransmitters density could contribute to confer to the cervix a proper potential plasticity, necessary for pregnancy and labour.

Collagen IV and Laminin are localized in cells and tissue of numerous human organs including the uterus, where these polypeptides control either age changes, or uterus growth in pregnancy, or ripening and dilatation in labor. Authors examined the polypeptides distribution of collagen IV and Laminin in the human pregnant uterus, in normal and dystocic labor, to clarify their physiologic role, by distribution and/or their changes in prolonged dystocic labor. We collected lower uterine segment (LUS) fragments during cesarean section (CS); these biopsies were treated with basic morphological staining for the observation of microscopic- anatomic details. Other samples were processed with immunohistochemical staining for collagen IV and for membrane bound Laminin. All morphological and immunochemical results were analyzed with quantitative analysis of images and statistical analysis of data. Both Collagen IV and Laminin show changes in the pregnant uterus before 4 hours of full cervical dilatation in patients after 4 hours. All the three types of the human uterine cells, mucosal, submucosal and smooth muscular cells, are more reduced in LUS after 4 hours of cervical dilatation in dystocic labor. The connective tissues (including fibroblast) show the most evident changes in the dystocic LUS, collagen IV and laminin changes during cervical dilatation in prolonged dystocic labor, with a decreased elasticity with increased roughness and dryness. The LUS anatomical modifications during labor can be the cause of pathological changes in protracted dystocic labor. In the dystocic labor that lasts more than 4 hours from the complete cervical ripening and dilatation, the laminin and collagen IV concentration reduces in the LUS tissue. In dystocic labor, delivery should be completed before the 3 hours of full dilation, to avoid a reduction of laminin and collagen IV and a worsening of LUS healing for the next pregnancy.

Utilizing both primary myometrial cells and a myometrial cell line, we show here that myometrial cells undergo transition to a myofibroblast-like phenotype after a biological insult of 72 hours serum starvation and serum add-back (SB: 1% to 10% FBS). We also found that thrombospondin-1 was increased and that the transforming growth factor-beta (TGFB)-SMAD3/4 pathway was activated. This pathway is a key mediator of fibrosis and extracellular matrix (ECM) deposition. Applying the same insult supplemented with TGFB3 (1-10ng/ml) and ascorbic acid (100μg/ml) in the serum add-back treatment, we further demonstrated that cells migrated into nodules containing collagen and fibronectin. The number of cellnodules was inversely related to the percentage serum add-back. Using transmission electron microscopy we demonstrated myofibroblast-like cells and fibril-like structures in the extracellular spaces of the nodules. This study is the first direct evidence of induction of myofibroblast transdifferentiation in cultured myometrial cells which is related to the increase of thrombospondin-1 (THBS1) and the activation of TGFBSMAD 3 / 4 pathways. Combined, these observations provide biochemical and direct morphological evidence that fibrotic responses can occur in cultured myometrial cells. The findings are the first to demonstrate uterine healing mechanisms at a molecular level. Our data support the concept that fibrosis may be an initial event in formation of fibroid which exhibits signaling pathways and molecular features of fibrosis and grow by both cellular proliferation and altered extracellular matrix accumulation. Our data assists in further understanding of myometrium tissue remodeling during gestation and postpartum.

Uterine leiomyoma is a benign smooth muscle tumor characterized by a high incidence in women of reproductive age. The aetiology of this tumor is still unknown but established risk factors include high levels of female hormones, family history, African ancestry, early age of menarche and obesity. Here, to identify proteomic features associated with this tumor type, we performed a liquid chromatography-mass spectrometry (LC-MS/MS) analysis of uterine myomas. The identified proteins were subjected to a gene ontology analysis to generate biological functions, molecular processes, and protein networks that were relevant to the uploaded dataset. Pathway-based analysis was an effective approach to investigate the molecular mechanisms underlying the disease and to create biological hypotheses about regulation of our proteins including the identification of upstream regulators and main protein nodes. Moreover, proteomic and in silico data were combined with immunohistochemistry and western blotting to identify a group of proteins representative of some selected pathways, with a dysregulated expression in myoma, pseudocapsule, and normal myometrium samples. Based on these results, we confirmed the over-expression of extracellular matrix components, and estrogen and progesterone receptors in uterine myomas, and proposed biological networks, canonical pathways and functions that may be relevant to the pathophysiology of this tumor.

Peptides and neuropeptides influence the uterine disorders of healing or cicatrization, chronic pelvic pain and disorder of pregnancy, labor and puerperium. They also promote changes in the lower uterine segment (LUS) during pregnancy, labor and delivery. We investigated the tissue quantity of neurotensin (NT), neuropeptide tyrosin (NPY) and Protein Gene Product 9.5 (PGP 9.5) in women submitted to elective cesarean section (CS) and urgent CS. During surgery, authors biopsied tissue samples of vesico-uterine space (VUS) to detect nerve fibers, and compared them. VUS samples from 106 patients have been evaluated with light microscopy, immunochemistry and Immunohistochemistry, and finally by Quantimet Leica analyzer software. Significantly higher amount of nerve fibers, containing NT, NPY and PGP 9.5 have been found in VUS tissue samples obtained during the first elective CS and during the first urgent CS were respectively 5±0.7, 7±0.6 and 5±0.9 CU and 2.5±0.5, 3.6±0.4 and 3.5±0.9 CU (p<0.05). This neurotransmitter reduction should indicate the inflammatory damage of cervical tissue for LUS over distension in dystocic-prolonged labor before CS. These results may be correlated with the decrease of NT, NPY and PGP 9.5, responsible for an optimal healing and LUS functions. In our opinion, the presence of neuropeptides reduction in uterine samples of women undergoing urgent CS may be due to a prolonged fetal head station in LUS, with a tissue denervation, in consequence of both overdistension and inflammatory process of the dystocic LUS.

With the rapid development of targeted therapy and our understanding of the underlying molecular mechanisms, drug repurposing is becoming trendy in drug development field. Drugs that display promising therapeutic effects towards multiple diseases tend to target important signaling proteins. Insulin resistance and obesity are strongly associated and both are reported to be correlated with cancer, suggesting they may be linked via some critical pathways. Signal transducer and activator of transcription 1 (STAT1) is an important transcription factor involved in the regulation of multiple cellular processes such as proliferation, survival, inflammation, and angiogenesis. The expression and activity of STAT1 is misregulated in both insulin resistance diseases and cancer. In this review, we summarize recent progress on the function and regulation of STAT1 in both cancer and insulin resistance diseases. Drugs and small molecules that can interfere with STAT1 activity or expression are also discussed.