ENDOMETRIOSIS
Endometriosis, which is defined as the ectopic presence of endometrial glandular and stromal cells outside of the uterine cavity is one of the common benign gynaecologic disorders [1]. Endometriosis is often associated with chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility. Endometriosis occurs in 10% of reproductive-age women, whereas the prevalence of endometriosis in women with chronic pelvic pain or infertility ranges from 20% to 90% [2]. Although the pathophysiology underlying endometriosis is not fully understood, the most accepted hypothesis is that endometrial cells pass through retrograde menstrual flow and implant in the abdominal cavity. On the basis of this hypothesis, it is thought that immunologic and biological factors influence the incidence of endometriosis. Retrograde menstrual flow is a common phenomenon in most women; however, there are several conditions that must be met to develop endometriosis. First, the endometrial cells in the abdominal cavity cannot be cleared or absorbed by immunological reactions. Second, the cells must evade apoptosis. Third, the cells must attach to the ectopic tissues of the peritoneal cavity, invade the interstitium, and be supplied by angiogenesis. Recently, the substances requisite for such conditions have been studied intensively, such as adhesion molecules, proteinases, growth factors, and angiogenic factors, and the expressions and activities of the substances have been compared [3-6]. To meet these conditions, peritoneal environment which is different from that in healthy women will be needed. Excessive cell proliferation and inadequate apoptosis have been considered two of the most abnormal features of endometriotic cells [7]. Increasing cell proliferation could result from inadequately activated ERK signaling in endometriotic tissues [8, 9]. Apoptosis, the process of programmed cell death, is precisely controlled for maintaining tissue homeostasis and removing senescent cells during the menstrual cycle from the human endometrium. It has been reported that changed apoptotic activity of endometriotic cells is related to the up-regulation of antiapoptotic factors. [10]. Some investigators suggested that endometriosis patients have a different peritoneum compared to healthy controls, which may help to attribute a pro-inflammatory environment, promoting the occurrence of endometriosis. In a study about molecular factors affecting endometriosis, various kinds of molecules such as IL-1ß, VEGF and IL-6 were related to the development and progression of endometriosis [11].
Mistletoe is a hemi-parasitic plant that grows attached to a wide range of host trees, and consists of mistletoe lectins, viscotoxins, vester protein, and Kuttan peptide. Mistletoe is known to stimulate and normalize the immune system so the growth of cancer cells is inhibited without killing normal cells [12-15]. Helixor®, the type of mistletoe used in the current study, is distinguished between A and M on the basis of trees upon which the mistletoe is parasitic. Helixor A®, which is hemi-parasitic on firs, is used clinically for treating skin allergies, breast cancer, and recto-sigmoid cancer. Moreover, Helixor A® has been reported to be effective in treating cancer, such as preventing the recurrence of cancer after surgery, inhibiting angiogenesis, stimulating bone marrow function, and curing endometriosis [16-20].
It has been reported that ectopic endometrial tissue transplantation is promoted by increased vascular endothelial growth factor (VEGF), uPA, and MMP-3 levels in the endometrium and abdominal cavity fluid of patients with endometriosis [21].
The current study evaluated the effect of mistletoe on cell viability of endometriosis, especially according to the early and advanced stage of endometriosis. To determine the anti-angiogenic effect of mistletoe, the expressions of VEGF was measured, and the change in expressions of VEGF following mistletoe treatment was recorded. Additionally, we determined if the anti-angiogenic effect of mistletoe could be used in the treatment of endometriosis, and if mistletoe could be used clinically.
DISCUSSION
Using peritoneal fluid from endometriosis patients and mistletoe, we found that both the eutopic and ectopic endometrial stromal cell viability increased after treatment with peritoneal fluid from early-stage (I and II) endometriosis. In addition, after mistletoe treatment, cell viability decreased in, both eutopic and ectopic endometrial stromal cell in all stages of endometriosis. These findings were verified consistently by the expression and concentration of VEGF, a marker of angiogenesis. Thus, it is assumed that there is some factor in the peritoneal fluid of endometriosis patients that causes an increase in cell viability, which is suppressed by mistletoe. VEGF is a possible factor related to endometriosis, and VEGF expression is controlled by mistletoe. This is consistent with the results of an earlier study [23].
Furthermore, VEGF expression increased in group 1 and decreased more when treated with mistletoe compared to group 2. These results imply that an early stage of endometriosis is more active pathophysiologically, and it may yield better results. Moreover, the clinical symptoms do not correspond with the stage. Another study also reported that VEGF expression is higher in patients with stage I and II endometriosis than stage III and IV endometriosis [24].
Endometriosis is a benign disease, but the characteristics of the cells with endometriotic lesion resemble malignant tumour cells including cell proliferation, invasion, angiogenesis, and reduced apoptosis [25]. Peritoneal endometriosis is the most common type of endometriosis [26]. Peritoneal endometriosis may progress to the advanced stage with inflammatory cytokines and angiogenic factors [25].
There are several etiologic hypotheses to account for endometriosis, such as ectopic transplantation of endometrial cells, metaplasia of coelomic epithelium, and induction. Because no single theory can fully explain all locations of endometriotic lesions, the etiology of endometriosis is unclear. Even though endometrial cells pass through retrograde menstrual flow in most women, ectopic transplantation of endometrial cells does not always occur; the basis for this observation has not been proven. It has been reported that immunologic factors are abnormally high in endometriosis patients, and facilitate survival in the abdominal cavity, attachment to the peritoneum, proliferation, angiogenesis, and generation of inflammatory reactions. For example, endometrial cells from endometriosis patients shows resistance to apoptosis, the normal process of changing endometrial cells, which is regulated through the menstrual period. Moreover, the bcl-2/bax and Fas-ligand system is known to be involved in this resistance [27, 28]. It is assumed that due to the resistance to apoptosis, the viability of endometrial cells is increased in the abdominal cavity, and the retrograde menstrual flow shows resistance to the immunologic reactions of macrophages. Therefore, the cells survive and may cause endometriosis. Recurrent and recalcitrant endometriosis may be regarded as an immunologic disease, and studies of immune control treatment are necessary.
Because the incidence of endometriosis has shown a rapid increase in recent decades, the diagnosis tends to be delayed, and endometriosis may even relapse occur postoperatively, so long-term treatment methods that prevents relapse are needed. Clinically, mistletoe is used in some regions as an immune modulator because recurrent and recalcitrant endometriosis is regarded as an immunologic disease. However, studies focusing on the basic science of mistletoe are rare; thus, the present study was performed to establish a theoretical background for clinical application. In early stage endometriosis, such as pelvic endometriosis, endometriotic lesions are metabolically active and endometriosis is a disease with progressive and recurrent disease.
In conclusion, we found that peritoneal fluid in the early stage of endometriosis had specific factors increasing cell viability and VEGF expression, and this effect decreased after mistletoe treatment. Thus, mistletoe could be considered as an immune modulator for treatment of early or recurrent diseases.
Comments
Post a Comment