Vascular endothelial growth factor gene polymorphisms are associated with the risk of developing adenomyosis

Uterine disorders and iron deficiency anemia

Abnormal uterine bleeding (AUB) is a clinical entity which can lead to iron deficiency anemia. Classification according to the acronym PALM-COEIN (polyp, adenomyosis, leiomyoma, malignancy, and hyperplasia; coagulopathy, ovulatory dysfunction, endometrial, iatrogenic, and not otherwise classified) provides a structured approach to establish the cause of AUB. The goal of this review is to discuss the different mechanisms and the relationship between uterine disorders and AUB. Heavy menstrual bleeding, a subgroup of AUB, is more closely related to the presence of uterine fibroids. The relationship between heavy menstrual bleeding and uterine fibroids remains poorly characterized, particularly the understanding of endometrial function in women with structural myometrial features such as leiomyomas. A number of theories have been proposed in the literature and are discussed in this review. Uterine adenomyosis is also a frequent cause of AUB, and its pathogenesis is still far from being fully elucidated. The mechanisms contributing to its development are multifactorial. Many theories lean toward invasion of the myometrium by endometrial cells. Both clinical and basic studies favor the theory of direct invasion, although de novo development of adenomyosis from Müllerian rests or stem cells has not been ruled out. Development of adenomyotic lesions involves repeated tissue injury and repair. In addition, this review describes the other causes of AUB such as endometrial polyps, cesarean scar defects, and uterine vascular abnormalities. Endometrial polyps are often asymptomatic, but approximately 68% of women have concomitant AUB. Histologic alterations in the lower uterine segment in patients who had undergone cesarean sections were identified and may explain the cause of AUB.

[Adenomyosis pathophysiology: An unresolved enigma]

Adenomyosis is a chronic benign uterine disease characterized by the presence of endometrial glands and stroma within the myometrium. It is a heterogeneous disease, presenting various clinical forms, depending on the location of the ectopic lesions within the myometrium. Adenomyosis can be responsible for several symptoms such as dysmenorrhea, abnormal uterine bleeding and/or infertility. Its pathophysiology is a real conundrum and several theories have been proposed: development of adenomyosis lesion could initiate de novo from Mullerian rests or from stem cells. Moreover, multiple factors could be involved in initiating lesions, including specific hormonal, immune and/or genetic changes. The objective of this review is to provide an update on adenomyosis pathophysiology, in particular on the various theories proposed concerning the invasion of the myometrium by endometrial cells and the inducing mechanisms, and to study the link between the physiopathology, the symptoms and the medical treatments.

Adenomyosis: Mechanisms and Pathogenesis

Adenomyosis is a common disorder of the uterus, and is associated with an enlarged uterus, heavy menstrual bleeding (HMB), pelvic pain, and infertility. It is characterized by endometrial epithelial cells and stromal fibroblasts abnormally found in the myometrium where they elicit hyperplasia and hypertrophy of surrounding smooth muscle cells. While both the mechanistic processes and the pathogenesis of adenomyosis are uncertain, several theories have been put forward addressing how this disease develops. These include intrinsic or induced (1) microtrauma of the endometrial-myometrial interface; (2) enhanced invasion of endometrium into myometrium; (3) metaplasia of stem cells in myometrium; (4) infiltration of endometrial cells in retrograde menstrual effluent into the uterine wall from the serosal side; (5) induction of adenomyotic lesions by aberrant local steroid and pituitary hormones; and (6) abnormal uterine development in response to genetic and epigenetic modifications. Dysmenorrhea, HMB, and infertility are likely results of inflammation, neurogenesis, angiogenesis, and contractile abnormalities in the endometrial and myometrial components. Elucidating mechanisms underlying the pathogenesis of adenomyosis raise possibilities to develop targeted therapies to ameliorate symptoms beyond the current agents that are largely ineffective. Herein, we address these possible etiologies and data that support underlying mechanisms.

Altered VEGF, Bcl-2 and IDH1 expression in patients with adenomyosis

PURPOSE

Adenomyosis is a benign uterine disease resulting from the myometrial invasion of the endometrial gland and stroma. In the current study, angiogenesis, apoptosis and energy metabolism were investigated in adenomyosis.

METHODS

A retrospective study was performed using paraffin archival tissues. Three groups were included in the study: Group I and Group II; ectopic and eutopic endometrial tissues of patients with adenomyosis, respectively, and Control Group; endometrial tissue of individuals without adenomyosis. Vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), intercellular adhesion molecule 1 (ICAM-1) and hypoxia-inducible factor 1 alpha (HIF-1A) levels were evaluated as angiogenic markers. Bcl-2, caspase-9 and caspase-3 levels were investigated as apoptotic indicators, and isocitrate dehydrogenase 1 (IDH1), succinate dehydrogenase complex subunit C (SDHC) and fumarate hydratase (FH) levels were also examined as energy metabolism markers. Gene expression levels of all parameters were determined by RT-PCR.

RESULT

VEGF expression levels were found to be increased in Group I according to the control group and Group II. Bcl-2 expression levels were found to be increased in the Group I compared to the Group II. It was determined that expression levels of IDH1 were decreased in the Group I and Group II compared to the Control Group. There was no significant difference in the other examined parameters. Although we did not find a significant difference in HIF-1A levels between the groups, we found a positive correlation between VEGF and HIF-1A in the Group I.

CONCLUSION

These results point out that VEGF, HIF-1A, Bcl-2 and IDH1 may be associated with the etiology of adenomyosis.

The impact of vascular endothelial growth factor single nucleotide polymorphisms in the development and severity of endometriosis: A systematic review of the literature

OBJECTIVE

To review the impact of single nucleotide polymorphisms (SNPs) of the vascular endothelial growth factor (VEGF) gene in the development and severity of endometriosis.

SEARCH STRATEGY

We searched Medline, Scopus, Clinicaltrials.gov, EMBASE, Cochrane Central Register of Controlled Trials CENTRAL and Google Scholar databases for published studies in the field.

SELECTION CRITERIA

We included prospective and retrospective observational studies.

DATA COLLECTION AND ANALYSIS

Data extraction was performed using a modified data form that was based in Cochrane`s data collection form for intervention reviews.

MAIN RESULTS

Twenty studies were included that investigated the frequency of the various alleles of the -460C/T, +405G/C, +936C/T, -2578A/C and -1154G/A SNPs. The Hardy-Weinberg equilibrium revealed that the different genotypes were comparable among patients with endometriosis and control women, as well as among patients with mild and severe forms of the disease. No differences were observed in the expression of the various alleles in the majority of cases. Ethnical variations were observed; however, the results should be regarded as inconclusive due to the small amount of available data.

CONCLUSIONS

The results of our meta-analysis suggest that the investigated single nucleotide polymorphisms are unlikely to significantly contribute to the development and severity of endometriosis.

Role of angiogenesis in adenomyosis-associated abnormal uterine bleeding and subfertility: a systematic review

BACKGROUND

Adenomyosis commonly occurs with abnormal uterine bleeding (AUB) and is associated with subfertility and a higher miscarriage rate. Recent evidence showed abnormal vascularization in the endometrium in patients with adenomyosis, suggesting a role of angiogenesis in the pathophysiology of AUB and subfertility in adenomyosis and providing a possible treatment target.

OBJECTIVE AND RATIONALE

We hypothesized that the level of abnormal vascularization and expression of angiogenic markers is increased in the ectopic and eutopic endometrium of adenomyosis patients in comparison with the endometrium of control patients. This was investigated through a search of the literature.

SEARCH METHODS

A systematic search was performed in PubMed and Embase until February 2019. Combinations of terms for angiogenesis and adenomyosis were applied as well as AUB, subfertility or anti-angiogenic therapy. The main search was limited to clinical studies carried out on premenopausal women. Original research articles focusing on markers of angiogenesis in the endometrium of patients with adenomyosis were included. Studies in which no comparison was made to control patients or which were not published in a peer-reviewed journal were excluded. A second search was performed to explore the therapeutic potential of targeting angiogenesis in adenomyosis. This search also included preclinical studies.

OUTCOMES

A total of 20 articles out of 1669 hits met our selection criteria. The mean vascular density (MVD) was studied by quantification of CD31, CD34, von Willebrand Factor (vWF) or factor-VIII-antibody-stained microvessels in seven studies. All these studies reported a significantly increased MVD in ectopic endometrium, and out of the six articles that took it into account, four studies reported a significantly increased MVD in eutopic endometrium compared with control endometrium. Five articles showed a significantly higher vascular endothelial growth factor expression in ectopic endometrium and three articles in eutopic endometrium compared with control endometrium. The vascular and pro-angiogenic markers α-smooth muscle actin, endoglin, S100A13, vimentin, matrix metalloproteinases (MMPs), nuclear factor (NF)-kB, tissue factor (TF), DJ-1, phosphorylated mammalian target of rapamycin, activin A, folli- and myostatin, CD41, SLIT, roundabout 1 (ROBO1), cyclooxygenase-2, lysophosphatidic acid (LPA) 1,4-5, phospho signal transducer and activator of transcription 3 (pSTAT3), interleukin (IL)-6, IL-22 and transforming growth factor-β1 were increased in ectopic endometrium, and the markers S100A13, MMP-2 and -9, TF, follistatin, myostatin, ROBO1, LPA1 and 4-5, pSTAT3, IL-6 and IL-22 were increased in eutopic endometrium, compared with control endometrium. The anti-angiogenic markers E-cadherin, eukaryotic translation initiation factor 3 subunit and gene associated with retinoic-interferon-induced mortality 19 were decreased in ectopic endometrium and IL-10 in eutopic endometrium, compared with control endometrium. The staining level of vWF and two pro-angiogenic markers (NF-κB nuclear p65 and TF) correlated with AUB in patients with adenomyosis. We found no studies that investigated the possible relationship between markers of angiogenesis and subfertility in adenomyosis patients. Nine articles reported on direct or indirect targeting of angiogenesis in adenomyosis-either by testing hormonal therapy or herbal compounds in clinical studies or by testing angiogenesis inhibitors in preclinical studies. However, there are no clinical studies on the effectiveness of such therapy for adenomyosis-related AUB or subfertility.

WIDER IMPLICATIONS

The results are in agreement with our hypothesis that increased angiogenesis is present in the endometrium of patients with adenomyosis compared with the endometrium of control patients. It is likely that increased angiogenesis leads to fragile and more permeable vessels resulting in adenomyosis-related AUB and possibly subfertility. While this association has not sufficiently been studied yet, our results encourage future studies to investigate the exact role of angiogenesis in the etiology of adenomyosis and related AUB or subfertility in women with adenomyosis in order to design curative or preventive therapeutic strategies.

Effect of ovarian steroids on vascular endothelial growth factor a expression in bovine uterine endothelial cells during adenomyosis

Background

Adenomyosis is a uterine dysfunction defined as the presence of endometrial glands within the myometrium. There is evidence that proangiogenic factors may play a role during the development of adenomyosis; however, exact mechanism remains unknown. The aim of the study was to determine the action of vascular endothelial growth factor A (VEGFA) in uterine tissue and uterine vascular endothelial cells during adenomyosis.

Results

Uterine tissues were collected and examined for the presence and extent of adenomyosis. Gene and protein expression of VEGFA and its two receptors (VEGFR1 and VEGFR2) was evaluated with quantitative polymerase chain reaction and Western blotting, respectively, in endometrium and myometrium during adenomyosis. Immunolocalization of VEGFA and its receptors within uterine tissues during adenomyosis was also determined. In an in vitro experiment, endothelial cells from non-adenomyotic bovine uteri were treated with media conditioned by non-adenomyotic or adenomyotic uterine slices treated with 17-beta-oestradiol (E2) or progesterone (P4). Both gene and protein expression of VEGFR2 were elevated in endometrium in stages 3–4 of adenomyosis. Protein expression of VEGFA and VEGFR2 as well as VEGFA secretion were increased in endothelial cells treated with media conditioned by adenomyotic uterine slices after E2 treatment.

Conclusions

Results suggest that VEGFA signalling is an important component, next to E2, that enhances VEGFA action and participates in adenomyosis development in cows.

Impact of a Chinese Medicinal Formula, Xiao Liu Fang, on the "3A" Ability of Endometrial Stromal Cells in Patients with Endometriosis

The pathogenesis of endometriosis (EMS) is complicated, and treatment results are unsatisfactory. It has become the focus of gynecological research. Analysis targeting the pathogenesis of EMS is the key to providing more effective treatments. In recent years, the superiority of traditional Chinese medicine in treating EMS has been highlighted, so we investigated the impact of a Chinese medicinal formula (Xiao Liu Fang) on the “3A” ability, in situ, of ectopic endometrial stromal cells in patients with EMS. Primary endometrial stromal cells were isolated using a modified net filtration method, cultured, and identified in different groups. Endometrial cell attachment was measured using the methyl thiazolyl tetrazolium (MTT) colorimetric assay, cell aggression was detected by the transwell cell-invasion assay, and angiogenesis was defined by evaluating the mRNA concentrations of intercellular cell adhesion molecule 1 (ICAM-1), cyclooxygenase 2 (COX-2), matrix metallo peptidase 9 (MMP-9), and vascular endothelial growth factor (VEGF). Attachment, aggression, and angiogenesis (AAA) plays an important role in EMS, and a high dose of the Xiao Liu Fang extract can be used for the treatment of EMS owing to its inhibition of the AAA of endometrial stromal cells. Therefore, in-depth studies targeting the effective mechanisms and targets of traditional Chinese medicine (TCM) are of great significance for the prevention and treatment of EMS.

Basic mechanisms of vascularization in endometriosis and their clinical implications

BACKGROUND

Vascularization is a major hallmark in the pathogenesis of endometriosis. An increasing number of studies suggests that multiple mechanisms contribute to the vascularization of endometriotic lesions, including angiogenesis, vasculogenesis and inosculation.

OBJECTIVE AND RATIONALE

In this review, we provide an overview of the basic mechanisms of vascularization in endometriosis and give special emphasis on their future clinical implications in the diagnosis and therapy of the disease.

SEARCH METHODS

Literature searches were performed in PubMed for English articles with the key words 'endometriosis', 'endometriotic lesions', 'angiogenesis', 'vascularization', 'vasculogenesis', 'endothelial progenitor cells' and 'inosculation'. The searches included both animal and human studies. No restriction was set for the publication date.

OUTCOMES

The engraftment of endometriotic lesions is typically associated with angiogenesis, i.e. the formation of new blood vessels from pre-existing ones. This angiogenic process underlies the complex regulation by angiogenic growth factors and hormones, which activate intracellular pathways and associated signaling molecules. In addition, circulating endothelial progenitor cells (EPCs) are mobilized from the bone marrow and recruited into endometriotic lesions, where they are incorporated into the endothelium of newly developing microvessels, referred to as vasculogenesis. Finally, preformed microvessels in shed endometrial fragments inosculate with the surrounding host microvasculature, resulting in a rapid blood supply to the ectopic tissue. These vascularization modes offer different possibilities for the establishment of novel diagnostic and therapeutic approaches. Angiogenic growth factors and EPCs may serve as biomarkers for the diagnosis and classification of endometriosis. Blood vessel formation and mature microvessels in endometriotic lesions may be targeted by means of anti-angiogenic compounds and vascular-disrupting agents.

WIDER IMPLICATIONS

The establishment of vascularization-based approaches in the management of endometriosis still represents a major challenge. For diagnostic purposes, reliable angiogenic and vasculogenic biomarker panels exhibiting a high sensitivity and specificity must be identified. For therapeutic purposes, novel compounds selectively targeting the vascularization of endometriotic lesions without inducing severe side effects are required. Recent progress in the field of endometriosis research indicates that these goals may be achieved in the near future.

Berberine inhibits the LPS-induced proliferation and inflammatory response of stromal cells of adenomyosis tissues mediated by the LPS/TLR4 signaling pathway

A previous study by our group has demonstrated that lipopolysaccharide (LPS) induces adenomyosis through stimulating inflammatory cell proliferation and invasive growth of stromal cells via Toll-like receptor 4 (TLR4) signaling. The present study aimed to investigate the effects of berberine (BBR) on LPS-induced ectopic endometrial stromal cells (EESCs) isolated from patients with adenomyosis. The viability of EESCs treated with LPS or LPS plus BBR was detected by a cell counting kit-8 assay, and the cell cycle distribution and apoptosis were evaluated by flow cytometry. The effect of BBR on the expression of key molecules of inflammatory proliferation and invasive growth of LPS-induced EESCs was also evaluated. BBR significantly inhibited the LPS-induced proliferation of EESCs in a dose- and time-dependent manner. BBR induced cell cycle arrest in G0/G1 phase and enhanced apoptosis of LPS-induced EESCs. Furthermore, BBR inhibited the expression of interleukin (IL)-6, IL-8, transforming growth factor-β, epithelial growth factor, vascular endothelial growth factor and matrix metalloproteinase 2 in LPS-induced EESCs. To the best of our knowledge, the present study was the first to demonstrate that BBR has a protective effect on ameliorating the LPS-induced progression of adenomyosis. This result may provide a novel therapeutic strategy for the clinical treatment of the disease.

Molecular Characteristics of the Endometrium in Uterine Adenomyosis and Its Biochemical Microenvironment

Adenomyosis, which manifests with focally or diffusely scattered endometrial tissue within the uterine myometrium, is an endometriosis-like disease with controversial pathogenesis and compromised reproductive outcomes. This review, including the in vitro and in vivo studies performed on human or mouse models, is aimed to summarize the specific molecular characteristics of endometrium in the biochemical microenvironments of uterine adenomyosis. Many studies attributed the endometrium as the main cause of pathogenesis, with evidence of differential genetic expression and/or epigenetic modulation as well as estrogen-induced epithelial-mesenchymal transition. However, some studies indicated that the myometrium could play a role in the development of disease, based on findings of smooth muscle metaplasia and/or fibroblast-to-myofibroblast transdifferentiation by the influence of local biochemical factors. To date, it remains unclear whether adenomyosis is a genetically determined or a microenvironmentally induced disorder or whether the dysregulation of local factors may elicit the alteration of genetic expression in the endometrium. Similarly, it is uncertain whether the endometrial characteristics would remain consistent or could change along with a woman's reproductive life. Further longitudinal studies of the epigenetic controls or system biology are needed to elucidate the pathogenesis. Discovery of effective conservative treatments to improve the reproductive outcomes of patients with adenomyosis is still warranted.

Involvement of NADPH oxidase and NF-κB activation in CXCL1 induction by vascular endothelial growth factor in human endometrial epithelial cells of patients with adenomyosis

Chemokines were known to participate in inflammation and angiogenesis but have been recently recognized to be involved in embryonic implantation and endometrium-related pathologies. Among these chemokines, the CXC chemokines, such as CXCL1, have potential roles to work as biomarkers to identify patients with uterine adenomyosis. In this study, human endometrial epithelial cells (HEECs) were derived from patients' endometrium with adenomyosis. The inductive effects of CXCL1 production by various mediators/growth factors were investigated in the HEECs. Of the tested mediators, VEGF was found to be the most effective. The immunohistochemistry and RT-PCR analysis revealed a positive staining for VEGF and CXCL1 at the epithelium and the presence of CXCL1 in the human endometrium specimens, respectively. The CXCL1 induction by VEGF could be reduced by the antagonist for VEGF receptor (VEGFR), and by the inhibitors for NADPH oxidase and NF-κB signaling pathway. However, it was not affected by sex hormones and the inhibitors for MAPKs, PI-3K, protein kinase A and C. In parallel, VEGF induced p47 phox NADPH oxidase activation, IκBα phosphorylation, NF-κB translocation and NF-κB-DNA complex formation in the HEECs. Moreover, the CXCL1 released by the HEECs with VEGF stimulation attracted vascular endothelial cell migration. Taken together, we show that VEGF and CXCL1 are expressed in epithelium of the endometrium with adenomyosis and demonstrate here for the first time that VEGF is capable of inducing CXCL1 expression in HEECs through VEGFR, p47 phox NADPH oxidase and NF-κB signaling pathway, which is functionally required for attracting vascular endothelial cell migration.

Association between nm23 gene polymorphisms and the risk of endometriosis

The first tumor metastasis-suppressor gene, nm23, may have an important role in the pathogenesis of endometriosis (EM). The present study aimed to evaluate whether nm23 gene polymorphisms are correlated with the risk of the development of EM in North Chinese women, as a preliminary study. The case-control study was conducted with 379 EM patients and 384 unrelated healthy controls. Genotyping of two polymorphisms within the nm23 gene promoter region (rs16949649 T/C and rs2302254 C/T) were performed using polymerase chain reaction-restriction fragment length polymorphism. The data showed that the rs16949649 and rs2302254 polymorphisms within the nm23 gene were not associated with the risk of developing EM. There were no statistical differences in the distribution of nm23 genotypes between patients with EM and the control group (P=0.490 and P=0.440, respectively). For the rs16949649 T/C, compared with the C/T + T/T genotype, the C/C genotype did not increase the risk of EM [odds ratio (OR)=0.81; 95% confidence interval (CI), 0.57-1.17]. For the rs2302254 C/T, compared with the C/T + C/C genotype, the T/T genotype did not increase the risk of EM (OR=1.46; 95% CI, 0.81-2.64). In conclusion, the findings in the present pilot study suggest that nm23 polymorphisms do not contribute to EM susceptibility. However, more studies in larger populations are required to confirm these results.

Role of vascular endothelial growth factor polymorphisms (-2578C>A, -460 T>C, -1154G>A, +405G>C and +936C>T) in endometriosis: a case-control study with Brazilians

Background

Endometriosis is regarded as a complex and heterogeneous disease in which genetic and environmental factors contribute to the phenotype. The Vascular Endothelial Growth Factor (VEGF) plays important roles in the pathogenesis of endometriosis. The present study was aimed at investigating the contribution of VEGF polymorphisms as risk factors for the development of endometriosis. This is the first study to evaluate the combined influence of the five most common VEGF polymorphisms.

Methods

This study was conducted at two hospitals from the Brazilian public health system, and comprised 294 women submitted to laparoscopic or laparotomy surgery: 182 patients had a histologically confirmed diagnosis of endometriosis (cases), whereas 112 had no evidence of the disease (controls). The VEGF polymorphisms were determined by TaqMan real-time polymerase chain reaction. The odds ratio (OR) with their 95% confidence intervals (CI) were calculated using an unconditional logistic regression model.

Results

Endometriosis patients and controls did not differ regarding age distribution, whereas the body mass index was significantly lower in endometriosis patients, when compared with controls (23.1 ± 3.9 versus 27.3 ± 5.9, P < 0.001). The evaluation of gynecological symptoms, including dysmenorrhea, non-cyclic chronic pelvic pain, dyspareunia and infertility, indicates significantly higher prevalences among endometriosis cases. The variant allele -1154A was significantly associated with endometriosis, either considering all cases (OR: 1.90, 95% CI: 1.23–2.97), deep infiltrating endometriosis (DIE) (OR: 1.83, 95% CI: 1.16-2.90) or moderate and severe endometriosis (stages III-IV) (OR: 1.97, 95% CI: 1.21-3.19). No significant differences were found in allele or genotype distributions of the –2578C > A, -460 T > C, +405G > C and +936C > T polymorphisms between endometriosis cases and controls. A total of six haplotypes were inferred derived from four polymorphisms (-2578C > A, -460 T > C, -1154G > A and +405G > C). There was a protective association between CCGG haplotype and endometriosis, either considering all cases (OR: 0.36, 95% CI: 0.15–0.86), DIE (OR: 0.37 95% CI: 0.15 – 0.90) or stages III-IV (OR: 0.35 95% CI: 0.13 – 0.95).

Conclusions

The present results indicate a positive association between VEGF -1154G > A and the risk of developing endometriosis, whereas the CCGG haplotype may be protective against the development of disease.

Oestrogen-induced angiogenesis promotes adenomyosis by activating the Slug-VEGF axis in endometrial epithelial cells

Adenomyosis is an oestrogen-dependent disease characterized by the invasion of endometrial epithelial cells into the myometrium of uterus, and angiogenesis is thought to be required for the implantation of endometrial glandular tissues during the adenomyotic pathogenesis. In this study, we demonstrate that compared with eutopic endometria, adenomyotic lesions exhibited increased vascularity as detected by sonography. Microscopically, the lesions also exhibited an oestrogen-associated elevation of microvascular density and VEGF expression in endometrial epithelial cells. We previously reported that oestrogen-induced Slug expression was critical for endometrial epithelial–mesenchymal transition and development of adenomyosis. Our present studies demonstrated that estradiol (E2) elicited a Slug-VEGF axis in endometrial epithelial cells, and also induced pro-angiogenic activity in vascular endothelial cells. The antagonizing agents against E2 or VEGF suppressed endothelial cells migration and tubal formation. Animal experiments furthermore confirmed that blockage of E2 or VEGF was efficient to attenuate the implantation of adenomyotic lesions. These results highlight the importance of oestrogen-induced angiogenesis in adenomyosis development and provide a potential strategy for treating adenomyosis through intercepting the E2-Slug-VEGF pathway.

Association between genetic variants of the VEGFR-2 gene and the risk of developing endometriosis in Northern Chinese Women

AIM

To investigate the association of tag single nucleotide polymorphisms (SNPs) in the vascular endothelial growth factor receptor 2 (VEGFR-2) gene with susceptibility to endometriosis.

METHODS

This study comprised 571 patients with endometriosis and 580 women in the control group. Five tag SNPs in the VEGFR-2 gene were selected using a Haploview program, and those SNPs were genotyped by a method of polymerase chain reaction and ligase detection reaction.

RESULTS

Statistical results show that there was a significant difference in the genotype and allele distribution of the 1192C/T polymorphism between the disease group and the control group (p = 0.041 and 0.017). The women carrying the T allele (C/T+T/T genotype) had a lower risk of developing endometriosis compared with the women with the C/C genotype (OR 0.75, 95% CI 0.57-0.99). There was no significant difference in the allele and genotype distribution of four other tag SNPs (1719T/A, +31C/T, IVS25-92A/G and IVS6+​54C/T) between the disease group and the control group (all p > 0.05).

CONCLUSIONS

Our results suggested that the 1192C/T polymorphisms on the VEGFR-2 gene might affect the risk of developing endometriosis in Northern Chinese women of Han ethnicity.

Vascular endothelial growth factor gene polymorphisms contribute to the risk of endometriosis: an updated systematic review and meta-analysis of 14 case-control studies

Endometriosis is a chronic gynecological disease defined as the presence of the endometrium outside the uterine cavity. Endometriosis is a multifactorial and polygenic disease in which angiogenesis may be implicated. Angiogenesis is under the control of numerous inducers, including vascular endothelial growth factor (VEGF). Many studies have reported that VEGF plays a role in the progression of the disease, but individually published studies showed inconclusive results. We investigated the association between VEGF polymorphisms and the susceptibility to endometriosis. The MEDLINE, EMBASE, Web of Science, and CBM databases were searched for all articles published up to June 25, 2012, which addressed VEGF polymorphisms and endometriosis risk. We investigated the potential association between VEGF polymorphisms and the risk of endometriosis. Fourteen studies were included with a total of 3313 endometriosis cases and 3393 healthy controls. Meta-analysis results showed that the rs699947 (A>C) and rs1570360 (G>A) polymorphisms in the VEGF gene were associated with a decreased risk of endometriosis, while rs3025039 (C>T) might increase the risk of endometriosis. However, the rs833061 (T>C) and rs2010963 (G>C) polymorphisms of the VEGF gene did not appear to have an influence on endometriosis susceptibility. Results from the meta-analysis suggest that the rs3025039 (C>T) polymorphism of the VEGF gene increases the risk of endometriosis, but the rs699947 (A>C) and rs1570360 (G>A) polymorphisms might be protective factors for endometriosis.

The pathophysiology of uterine adenomyosis: an update

The diagnosis of adenomyosis using noninvasive techniques such as vaginal ultrasounds and magnetic resonance has clear clinical applications and has renewed the interest in the pathogenesis of uterine adenomyosis. However, the research remains hampered by the lack of consensus on the classification of lesions. Magnetic resonance imaging and transvaginal ultrasound have comparable diagnostic accuracy. Minimal interventional biopsy techniques have recently been introduced. This article reviews human and animal studies and provides an update on the pathophysiology of adenomyosis. Recent views on the pathogenesis and links with endometriosis are discussed.

The Endometrium in Adenomyosis

Eutopic and ectopic endometria of women with adenomyosis show a series of metabolic and molecular abnormalities that increase angiogenesis and proliferation, decrease apoptosis, allow local production of estrogens, create progesterone resistance, and impair cytokine expression. These changes enhance the ability of the endometrium to infiltrate the junctional zone myometrium and the growth of ectopic tissue. In addition, in these subjects several immunological abnormalities have been observed, together with an increased production of ‘free radicals’ leading to excessive growth of endometrial stromal cells that may facilitate the establishment of adenomyosis. A limiting factor is that these studies have been performed on hysterectomy specimens representing final stages of the disease. This increased knowledge has created new therapeutic options, including the block of local aromatase production through the use of selective estrogen receptor modulators, estrogen-progestin combinations and gonadotropin-releasing hormone super agonists. Also promising are investigations into the mechanism of dysmenorrhea and abnormal uterine bleeding.

Adenomyosis and infertility

Today an accurate diagnosis of adenomyosis can be made thanks to progress in imaging techniques: sonography and magnetic resonance imaging (MRI). This has made it possible to clinically correlate the presence of adenomyosis to infertility. At the same time, a series of pathogenetic hypotheses have been presented to explain this correlation. First, the identification of the myometrial junctional zone (JZ) and of its disruption and thickening has been linked to poor reproductive performance mainly through perturbed uterine peristalsis, a phenomenon that originates exclusively from the JZ in the nonpregnant uterus. In addition, a number of biochemical and functional alterations in both eutopic and heterotopic endometrium in women with adenomyosis have now been found to lead to lower receptivity, indicated by the presence of 'implantation marker' defects. In these patients there is also an altered decidualization and abnormal concentrations of intrauterine free radicals. All these abnormalities in the endometrial environment seem to contribute to subfertility. Several attempts have been made to restore fertility in adenomyosis patients, the oldest being gonadotrophin-releasing hormone agonists coupled to conservative surgery. Also, uterine artery embolization and MRI-assisted high-intensity focused ultrasound ablation have been tried with some degree of success.

Polymorphisms of human vascular endothelial growth factor gene are associated with acute cerebral infarction in the Chinese population

BACKGROUND AND PURPOSE

Vascular endothelial growth factor (VEGF) plays a key role in the development of cerebral infarction as a major mediator of angiogenesis. The aim of this study was to investigate whether the VEGF gene polymorphisms were associated with the risks of acute cerebral infarction.

METHODS

We examined the distribution of three single nucleotide polymorphisms (SNPs), -1154G/A, 936C/T and -2578C/A, in the promoter and coding region of the VEGF gene in DNA samples from 147 Chinese patients with acute cerebral infarction and 131 control subjects.

RESULTS

There was no significant difference in allele and genotype distributions of -1154G/A, 936C/T and -2578C/A with the risk of acute cerebral infarction when compared with controls. However, haplotype analysis from the above-mentioned three polymorphisms showed that haplotype ACC was significantly lower in patients with acute cerebral infarction (0.020) than in controls (0.054) (p = 0.034).

CONCLUSIONS

These data suggested that the -1154/, 936/ and -2578/ ACC haplotype was associated with the risk of acute cerebral infarction with an OR of 0.361, and it may reduce the risk of acute cerebral infarction through the regulation of VEGF expression.

Differences in mitochondrial proteins in the eutopic endometrium of patients with adenomyosis and endometriosis identified using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry

Adenomyosis and endometriosis have a similar pathogenesis; indeed, adenomyosis has been considered by some as a variant of endometriosis ('internal endometriosis'). This study aimed to detect differences in mitochondrial proteins in eutopic endometrial samples from women with adenomyosis (n = 13) and endometriosis (n = 24), and from control patients (n = 29) using surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF-MS) protein chip technology. A total of 82 and 78 mitochondrial protein peaks were found in adenomyosis and endometriosis individuals, respectively. Of these, 14 were common to women with adenomyosis and women with endometriosis, although only one of these (mass-to-charge [m/z] ratio 3499) was significantly different between the adenomyosis and endometriosis groups. It is concluded that, compared with control patients, there are differences in the mitochondrial proteins isolated from the eutopic endometrium of patients with adenomyosis and those with endometriosis. Although the changes in mitochondrial proteins in eutopic endometrium from patients with adenomyosis and endometriosis were largely similar, significant differences were also detected. Further identification of these proteins and elucidation of the differences will help towards the differential diagnosis of adenomyosis and endometriosis and new therapeutic approaches.