A Reassessment of the Therapeutic Potential of a Dopamine Receptor 2 Agonist (D2-AG) in Endometriosis by Comparison against a Standardized Antiangiogenic Treatment

Potential Mechanisms of Guizhi Fuling Wan in Treating Endometriosis: An Analysis Based on TCMSP and DisGeNET Databases

ETHNOPHARMACOLOGICAL RELEVANCE

Guizhi Fuling Wan (GFW), is a traditional Chinese herbal formula that consists of Cinnamomi Ramulus (Guizhi), Poria Cocos(Schw.) Wolf. (Fuling), Persicae Semen (Taoren), Radix Paeoniae Rubra (Chishao), and Cortex Moutan (Mudanpi). This formula has been used in traditional Chinese medicine for more than 1800 years to treat disorders caused by stagnation of circulation and qi (air).

AIM OF THE STUDY

Based on pre-clinical and clinical studies, this review aimed to reveal the potential mechanisms of GFW in inhibiting endometriosis. The enhancement of therapeutic effects of western medications on endometriosis by GFW was also shown.

MATERIALS AND METHODS

A bibliographic assessment of publications on "Guizhi Fuling Wan" and "endometriosis" indexed in PubMed, Science Direct, and China National Knowledge Infrastructure (CNKI) was conducted. Five pre-clinical studies and 13 clinical studies were selected for this review. Moreover, the targeted molecules of each herb were first extracted from the Traditional Chinese Medicine Systems Pharmacology (TCMSP) Database and Analysis Platform followed by obtaining the endometriosis-related genes from DisGeNET. Subsequently, pathway and gene ontology analyses using David Bioinformatics Resources explored the potential mechanisms of therapeutic effects of GFW in treating endometriosis.

RESULTS

Pre-clinical and clinical studies showed that GFW might inhibit the growth of endometriotic lesion through the modulation of immunity, apoptosis-regulating molecules, and angiogenesis-associated factors, while enhancing the therapeutic effects of western medications in treating endometriosis. Furthermore, pathway and gene ontology analyses demonstrated that GFW might attenuate the disease primarily by affecting AGE-RAGE signaling pathway in diabetic complications (hsa04933) as well as pathways involved in Kaposi sarcoma-associated herpesvirus infection (hsa05167), human cytomegalovirus infection (has05163), and fluid shear stress and atherosclerosis (hsa05418). These pathways were all involved in the regulation of inflammation, angiogenesis, and apoptosis and commonly affected by all herbs.

CONCLUSIONS

The current review revealed that endometriosis is highly associated with aberrant inflammatory, angiogenic, and apoptotic activities. The therapeutic effects of GFW on endometriosis are likely to act through regulating these activities.

A Comprehensive Review of the Efficacy and Safety of Dopamine Agonists for Women with Endometriosis-associated Infertility from Inception to July 31, 2022

Background

Current medical management of endometriosis leads to suppression of ovulation and will not be helpful for women with endometriosis who are desirous of pregnancy. Thus, drugs that can both treat endometriosis and its associated infertility are highly warranted.

Objective

Anti-angiogenic agents are potential drugs for patients with endometriosis and infertility. Among these drugs, dopamine agonist (DA) is promising since it does not interfere with ovulation, is safe, and not teratogenic. The aim of the study is to determine the efficacy and safety of DA for improving reproductive outcomes in women with endometriosis and infertility.

Methods

A qualitative narrative review was done from inception to July 31, 2022 using the appropriate MeSH terms in PubMed, Cochrane Database of Systematic Reviews, the Cochrane Central Register of Controlled Trials, ClinicalTrial.gov, and World Health Organization International Clinical Trials Registry Platform. Date analysis was through qualitative analysis and synthesis of researches and their outcome measures.

Results

No studies used the core outcomes for trials evaluating treatments for infertility associated with endometriosis. All the included articles in the review supported the possible anti-angiogenic effects of DA on the vascular endothelial growth factor [VEGF] /VEGF receptor system. The use of DA does not have an effect on ovulation and menstrual cyclicity. Studies on safety profile of DA were consistent with existing data.

Conclusion

Most of studies reviewed demonstrated that DA were effective in reducing endometriotic lesions. However, further research is required to establish whether this anti-angiogenic effect can improve reproductive outcomes in women with endometriosis-associated infertility.

Research progress in rodent models of endometriosis

Endometriosis is a common and frequent disease in gynecology; its etiology and pathogenesis are partially understood and still not clear. The construction of suitable animal models is beneficial for basic research related to the disease. Currently, rodents have the advantages of low cost, fast reproduction, easy rearing, and a similar endometrial structure to humans. Depending on the purpose of the experiment, different molding methods have their advantages. In this paper, we describe the traditional methods of constructing endometriosis rodent models, compare their advantages and disadvantages, and introduce newly developed rodent models, such as cell line injection models, pain models, genetically engineered mouse models, fluorescent tracer models, iron overload models, chemical induction models, and methods of constructing rodent models of different subtypes of endometriosis. Fertility and treatment of endometriosis rodent models are also described. This study provides a reference for researchers in the selection of animal models for pathogenesis and drug treatment studies.

Antiangiogenic Effect of Dopamine and Dopaminergic Agonists as an Adjuvant Therapeutic Option in the Treatment of Cancer, Endometriosis, and Osteoarthritis

Dopamine (DA) and dopamine agonists (DA-Ag) have shown antiangiogenic potential through the vascular endothelial growth factor (VEGF) pathway. They inhibit VEGF and VEGF receptor 2 (VEGFR 2) functions through the dopamine receptor D2 (D2R), preventing important angiogenesis-related processes such as proliferation, migration, and vascular permeability. However, few studies have demonstrated the antiangiogenic mechanism and efficacy of DA and DA-Ag in diseases such as cancer, endometriosis, and osteoarthritis (OA). Therefore, the objective of this review was to describe the mechanisms of the antiangiogenic action of the DA-D2R/VEGF-VEGFR 2 system and to compile related findings from experimental studies and clinical trials on cancer, endometriosis, and OA. Advanced searches were performed in PubMed, Web of Science, SciFinder, ProQuest, EBSCO, Scopus, Science Direct, Google Scholar, PubChem, NCBI Bookshelf, DrugBank, livertox, and Clinical Trials. Articles explaining the antiangiogenic effect of DA and DA-Ag in research articles, meta-analyses, books, reviews, databases, and clinical trials were considered. DA and DA-Ag have an antiangiogenic effect that could reinforce the treatment of diseases that do not yet have a fully curative treatment, such as cancer, endometriosis, and OA. In addition, DA and DA-Ag could present advantages over other angiogenic inhibitors, such as monoclonal antibodies.

The latest advances in the pharmacological management of endometriosis

INTRODUCTION

Endometriosis is a benign disease, characterized by a wide range of symptoms and different degrees of severity, which is why therapy should be individually adapted to the patient's needs. Over the years, a lot of research has gone into finding new therapeutic approaches for this enigmatic disease.

AREAS COVERED

This review presents the latest advances in pharmacological management of endometriosis and is solely focused on studies published from 2010 to 2021.

EXPERT OPINION

Clinicians and researchers are constantly searching for new therapeutic strategies for endometriosis patients. As there are well-established treatments, however, any new medication should fulfill at least one of the three criteria: increased efficacy, comparable efficacy but a better safety profile, or treatments that have a lack of accompanying contraceptive effects that are seen in most endometriosis treatments. While some new substances show promising results, further studies are needed to demonstrate the fulfillment of one of the above-mentioned criteria.

Emerging Drug Targets for Endometriosis

Endometriosis is a chronic inflammatory disease causing distressing symptoms and requiring a life-long management strategy. The objective of this review is to evaluate endometriosis-related pathways and identify novel therapies to treat it. We focused on the crucial role of inflammation and inflammatory molecules in order to define new perspectives for non-hormonal treatment of the disease by targeting inflammation, nuclear factor kappa B and cytokines, or reactive oxygen species, apoptotic and autophagic pathways, regulators of epithelial-mesenchymal transition, and angiogenesis and neuroangiogenesis. Novel non-steroidal therapies targeting these pathways for endometriosis were explored, but multiple challenges remain. While numerous agents have been investigated in preclinical trials, few have reached the clinical testing stage because of use of inappropriate animal models, with no proper study design or reporting of preclinical strategies. Targeting estrogens is still the best way to control endometriosis progression and inflammation.

VEGF-A controls the expression of its regulator of angiogenic functions, dopamine D2 receptor, on endothelial cells

We have previously demonstrated significant upregulation of dopamine D2 (DAD2) receptor (DRD2) expression on tumor endothelial cells. The dopamine D2 receptors, upon activation, inhibit the proangiogenic actions of vascular endothelial growth factor-A (VEGF-A, also known as vascular permeability factor). Interestingly, unlike tumor endothelial cells, normal endothelial cells exhibit very low to no expression of dopamine D2 receptors. Here, for the first time, we demonstrate that through paracrine signaling, VEGF-A can control the expression of dopamine D2 receptors on endothelial cells via Krüppel-like factor 11 (KLF11)-extracellular signal-regulated kinase (ERK) 1/2 pathway. These results thus reveal a novel bidirectional communication between VEGF-A and DAD2 receptors.

Identification of Altered Evoked and Non-Evoked Responses in a Heterologous Mouse Model of Endometriosis-Associated Pain

The aim of this study was to develop and refine a heterologous mouse model of endometriosis-associated pain in which non-evoked responses, more relevant to the patient experience, were evaluated. Immunodeficient female mice (N = 24) were each implanted with four endometriotic human lesions (N = 12) or control tissue fat (N = 12) on the abdominal wall using tissue glue. Evoked pain responses were measured biweekly using von Frey filaments. Non-evoked responses were recorded weekly for 8 weeks using a home cage analysis (HCA). Endpoints were distance traveled, social proximity, time spent in the center vs. outer areas of the cage, drinking, and climbing. Significant differences between groups for von Frey response, climbing, and drinking were detected on days 14, 21, and 35 post implanting surgery, respectively, and sustained for the duration of the experiment. In conclusion, a heterologous mouse model of endometriosis-associated evoked a non-evoked pain was developed to improve the relevance of preclinical models to patient experience as a platform for drug testing.

Quinagolide Treatment Reduces Invasive and Angiogenic Properties of Endometrial Mesenchymal Stromal Cells

Endometrial mesenchymal stromal cells (E-MSCs) extensively contribute to the establishment and progression of endometrial ectopic lesions through formation of the stromal vascular tissue, and support to its growth and vascularization. As E-MSCs lack oestrogen receptors, endometriosis eradication cannot be achieved by hormone-based pharmacological approaches. Quinagolide is a non-ergot-derived dopamine receptor 2 agonist reported to display therapeutic effects in in vivo models of endometriosis. In the present study, we isolated E-MSCs from eutopic endometrial tissue and from ovarian and peritoneal endometriotic lesions, and we tested the effect of quinagolide on their proliferation and matrix invasion ability. Moreover, the effect of quinagolide on E-MSC endothelial differentiation was assessed in an endothelial co-culture model of angiogenesis. E-MSC lines expressed dopamine receptor 2, with higher expression in ectopic than eutopic ones. Quinagolide inhibited the invasive properties of E-MSCs, but not their proliferation, and limited their endothelial differentiation. The abrogation of the observed effects by spiperone, a dopamine receptor antagonist, confirmed specific dopamine receptor activation. At variance, no involvement of VEGFR2 inhibition was observed. Moreover, dopamine receptor 2 activation led to downregulation of AKT and its phosphorylation. Of interest, several effects were more prominent on ectopic E-MSCs with respect to eutopic lines. Together with the reported effects on endometrial and endothelial cells, the observed inhibition of E-MSCs may increase the rationale for quinagolide in endometriosis treatment.

Endometriosis in the Mouse: Challenges and Progress Toward a ‘Best Fit’ Murine Model

Endometriosis is a prevalent gynecologic condition associated with pelvic pain and infertility characterized by the implantation and growth of endometrial tissue displaced into the pelvis via retrograde menstruation. The mouse is a molecularly well-annotated and cost-efficient species for modeling human disease in the therapeutic discovery pipeline. However, as a non-menstrual species with a closed tubo-ovarian junction, the mouse poses inherent challenges as a preclinical model for endometriosis research. Over the past three decades, numerous murine models of endometriosis have been described with varying degrees of fidelity in recapitulating the essential pathophysiologic features of the human disease. We conducted a search of the peer-reviewed literature to identify publications describing preclinical research using a murine model of endometriosis. Each model was reviewed according to a panel of ideal model parameters founded on the current understanding of endometriosis pathophysiology. Evaluated parameters included method of transplantation, cycle phase and type of tissue transplanted, recipient immune/ovarian status, iterative schedule of transplantation, and option for longitudinal lesion assessment. Though challenges remain, more recent models have incorporated innovative technical approaches such as in vivo fluorescence imaging and novel hormonal preparations to overcome the unique challenges posed by murine anatomy and physiology. These models offer significant advantages in lesion development and readout toward a high-fidelity mouse model for translational research in endometriosis.