Immunobiology of endometriosis

OBJECTIVE: To provide a review of the humoral and cellular immunology of endometriosis and to discuss the rationale for future approaches to diagnosis and treatment. DESIGN: Literature survey. RESULT(S): Defective immunosurveillance in women who are destined to develop endometriosis may allow for the survival of ectopic endometrial tissue. The evidence includes endometrial cell resistance to apoptosis, perhaps through the secretion of proteins that interfere with implant recognition and/or FasL expression by stromal cells, inducing apoptosis of Fas-bearing immune cells. Although the immune response may be defective, aspects of it clearly are enhanced in endometriosis, as is seen by the generalized polyclonal B-cell autoimmune activation and secretion of immune proteins. Several cytokines, chemokines, and growth factors (including vascular growth factors) are increased in women with endometriosis. CONCLUSION(S): A complex network of locally produced cytokines modulate the growth and inflammatory behavior of ectopic endometrial implants. Proinflammatory proteins from endometriotic lesions and associated immune cells contribute to the enhanced inflammatory reaction associated with endometriosis that subserves the survival of these lesions instead of leading to their demise.     

Gonadotropin-releasing hormone analog repairs reduced endometrial cell apoptosis in endometriosis in vitro

OBJECTIVE: Impaired sensitivity of endometrial tissue to spontaneous apoptosis in women with endometriosis contributes to the abnormal implantation and growth of endometrium at ectopic sites. Our purpose was to examine the effect of gonadotropin-releasing hormone analog, widely used in the treatment of endometriosis, on the reduced rate of endometrial apoptosis in endometriosis.Study Design: Paired ectopic and eutopic endometrial tissue specimens were obtained from 13 patients with endometriosis, and control samples were taken from 8 patients with uterine myoma. Apoptotic cell death was assessed biochemically and morphologically with an enzyme-linked immunoassay and Hoechst No. 33342 staining of deoxyribonucleic acid fragment, respectively. RESULTS: Spontaneous apoptosis was significantly lower in ectopic and eutopic endometrial tissue from patients with endometriosis (0.22 +/- 0.082 in absorbance) than in endometrial tissue from control subjects (0.52 +/- 0.483)(P < 0.001). Incubation with a gonadotropin-releasing hormone analog (1 micromol/L) increased the apoptotic rate of endometrial cells from patients with endometriosis to 0.56 +/- 0.501 (P <.001). The effect of this gonadotropin-releasing hormone revealed a dose dependency; a half-maximal effect occurred with 10 nmol/L; however, the control endometrium was not affected. CONCLUSION: Exposure to gonadotropin-releasing hormone results in changes of the sensitivity of endometriotic endometrium to spontaneous apoptosis; these changes in sensitivity may, in turn, release endometrial cells from resistance to apoptosis and result in reduced survival and growth. This phenomenon could, at least in part, account for the therapeutic action of gonadotropin-releasing hormone analog on endometriosis.     

Immunology of endometriosis

The pathophysiology of endometriosis is not completely understood, but an aberrant immune response in the peritoneal environment seems to be crucial for the proliferation of ectopic endometrial cells – as those cells escape apoptosis and peritoneal cavity immunosurveillance. The growth of endometrial implants leads to the recruitment of a large number and diversity of immune cells and intense inflammation with increased pro-inflammatory cytokines, growth factors, and angiogenesis. There is substantial evidence of aberrant function of almost all types of immune cells in women with endometriosis: decreased T cell reactivity and NK cytotoxicity, polyclonal activation of B cells and increased antibody production, increased number and activation of peritoneal macrophages, and changes in inflammatory mediators. New clinical treatments for endometriosis are an urgent need, especially nonhormonal drugs. The study of immunology may clarify its role in the pathogenesis of endometriosis and contribute to the development of new therapeutic strategies.     

c-myc protooncogene polypeptide expression in endometriosis.

The c-myc protooncogene and its polypeptide product are important regulators of cell proliferation and differentiation, and ovarian steroids are believed to stimulate growth of various uterine cell types through altered expression of the c-myc gene. To determine whether c-myc expression may also be involved in the growth and development of endometriosis, we assessed c-myc expression in eutopic and ectopic endometrial tissue obtained from women undergoing surgery for endometriosis. Immunocytochemistry using a monoclonal antibody to the c-myc protein demonstrated positive staining of glandular and stromal cell nuclei, and cytoplasmic staining of glandular but not stromal cells in both eutopic and ectopic endometrium. These findings suggest that c-myc expression may be an important regulator of cell proliferation in endometriotic tissue.     

Fibrinogen alpha chain is up-regulated and affects the pathogenesis of endometriosis

Research questionIn the group's previous study, fibrinogen alpha chain (FGA) was identified as an up-regulated differential protein that was highly expressed in women with endometriosis. The current study investigated the expression and effects of FGA in endometriosis. It also evaluated the effects of FGA on human endometrial stromal cells and studied the possible mechanism.DesignThis was a cross-sectional analysis of FGA expression in plasma and endometrial tissue of matched eutopic and ectopic samples from women with endometriosis undergoing laparoscopic surgery and samples from women without endometriosis. Forty-four patients with endometriosis and 32 healthy control subjects who donated plasma for FGA analysis, including 26 matched cases of eutopic and ectopic endometria from endometriosis patients and 22 endometria from healthy control subjects, were analysed. The effects of FGA were studied in a human endometrial stromal cell line after transfection with FGA short interfering RNA (siRNA).ResultsFGA concentrations in serum and expression in eutopic and ectopic endometrial tissue were significantly higher in women with endometriosis than controls (P < 0.05 and P < 0.01 respectively), whereas FGA expression was not significantly different in eutopic compared with ectopic endometrial tissues from the same patients. High FGA concentrations in serum were related to disease stage and ovarian involvement, but were not affected by age and menstrual cycle. The knockdown of FGA expression by FGA siRNA inhibited hEM15A cellular adhesion, migration and invasion, and attenuated matrix metalloproteinase-2 (MMP-2) expression.ConclusionsHigh FGA expression in endometriosis was closely related to disease severity and affected cell adhesion, migration and invasion, which might play an important role in the pathogenesis of endometriosis.     

GnRHa对子宫内膜异位症内膜间质细胞生长增殖及血管形成的影响

目的:研究GnRHa对子宫内膜异位症异位及在位内膜间质细胞增殖、凋亡及血管形成的影响。方法:体外原代培养人内异症异位及在位子宫内膜间质细胞,用不同浓度的GnRHa分别干预,四甲基偶氮噻唑蓝(MTT)法测定内膜间质细胞的生长增殖活力;Annexin V-FITC和PI双染、流式细胞仪(FCM)检测异位及在位内膜间质细胞凋亡及周期变化;免疫细胞化学检测血管内皮生长因子(VEGF)表达的改变。结果:GnRHa可抑制内异症异位及在位内膜间质细胞增殖且呈剂量依赖关系;GnRHa能明显增加异位及在位内膜细胞的凋亡率(P<0.05),且异位内膜细胞凋亡率明显高于在位内膜(P<0.05);不同浓度的GnRHa作用后,内膜间质细胞均发生细胞周期阻滞,G1期细胞增加,S期细胞减少,此作用随浓度增加而增强(P<0.05);免疫细胞化学测定表明,GnRHa可降低异位及在位内膜间质细胞VEGF的表达(P<0.05),且随GnRHa浓度增加而增强(P<0.05)。结论:GnRHa可明显抑制人内异症异位及在位子宫内膜间质细胞的生长并促进其凋亡,降低异位及在位内膜间质细胞VEGF的表达。     

Immunology of endometriosis

Endometriosis is classically described as the presence of both endometrial glandular and stromal cells outside the uterine cavity, mainly in the pelvis. The pathogenesis of this enigmatic disorder still remains controversial despite extensive research. Although multiple theories have been put forth to explain the pathophysiology and pathogenesis of endometriosis, the retrograde menstruation theory of Sampson is the most widely accepted. However, since retrograde menstruation occurs in most of the reproductive age women, it is clear that there must be other factors which may contribute to the implantation of endometrial cells and their subsequent development into endometriotic disease. There is substantial evidence to support that the alterations in both cell-mediated and humoral immunity contribute to the pathogenesis of endometriosis. Increased number and activation of peritoneal macrophages, decreased T cell and natural killer (NK) cell cytotoxicities are the alterations in cellular immunity and result in inadequate removal of ectopic endometrial cells from the peritoneal cavity. Moreover, increased levels of several cytokines and growth factors which are secreted by either immune and endometrial cells seem to promote implantation and growth of ectopic endometrium by inducing proliferation and angiogenesis. In addition to the impaired capacity of the immune cells to mediate endometrial cell removal, inherent resistance of the ectopic endometrial cells against immune cells is another interesting concept in the pathogenesis of endometriosis. Endometriosis has also been considered to be an autoimmune disease, since it is often associated with the presence of autoantibodies, other autoimmune diseases, and possibly with recurrent immune-mediated abortion.     

Expression of oct-4 and c-kit antigens in endometriosis

The objective of this study was to test the expression of the oct-4 and c-kit, both markers of stem cells, in the ectopic endometrial tissue of endometriotic lesions of women with severe endometriosis. Our findings show that ectopic epithelial cells express oct-4 and c-kit and this suggests that the ectopic endometrium in endometriosis has a stem cell origin and could explain the possible progression to ovarian cancer.     

子宫内膜异位症患者辅助性T细胞亚群免疫状态的研究

目的　探讨辅助性T细胞 (Th)亚群在子宫内膜异位症 (内异症 )发病中的作用。方法　采用酶联免疫吸附法检测 30例内异症患者 (内异症组 )及 2 0例非内异症患者 (对照 1组 )血清及腹腔液中白细胞介素 (IL) 2、6的水平 ;用免疫组化技术分别检测IL 2、IL 6在内异症组患者异位内膜组织和 10例子宫肌瘤患者 (对照 2组 )的正常子宫内膜组织中的表达。结果　内异症组患者血清及腹腔液中位数IL 6水平分别为 5 3、2 1ng/L ,对照 1组患者血清及腹腔液中位数IL 6水平分别为 2 5、0 9ng/L ,两组妇女血清和腹腔液中IL 6水平分别比较 ,差异均有统计学意义 (P <0 0 5 ) ;内异症组Ⅲ～Ⅳ期患者血清及腹腔液中位数IL 6水平分别为 13 6、4 1ng/L ,Ⅰ～Ⅱ期患者血清及腹腔液中位数IL 6水平分别为 3 7、1 6ng/L ,Ⅲ～Ⅳ期患者与Ⅰ～Ⅱ期患者血清及腹腔液中位数IL 6水平比较 ,差异均有统计学意义 (P <0 0 5 ) ;内异症组IL 2 /IL 6比值在血清及腹腔液中分别为 0 7、1 1,均分别低于对照组的 0 8、6 2 ,差异也有统计学意义 (P <0 0 5 )。内异症组患者腹腔液与血清IL 6水平呈正相关 (r =0 74 5 ,P <0 0 1) ,血清及腹腔液中IL 6水平与IL 2 /IL 6比值均呈负相关 (r =- 0 4 0 6 ,P <0 0 5 ;r =- 0 4 80 ,P <0 0 5 )     

Deregulation of LOXL1 and HTRA1 gene expression in endometriosis

Endometriosis is a gynecologic disease characterized by the presence of endometrial tissue outside the uterine cavity. Although 15% of the female population in reproductive age is affected by endometriosis, its pathogenesis remains unclear. According to the most accepted pathogenesis hypothesis, endometrial fragments from the menstrual phase are transported through the uterine tubes to the peritoneal cavity, where they undergo implantation and growth, invading adjacent tissues. However, the establishment of the disease requires that endometrial cells present molecular characteristics favoring the onset and progression of ectopic implantation. In this investigation, we analyzed the differential gene expression profiles of peritoneal and ovarian endometriotic lesions compared to the endometrial tissue of nonaffected women using rapid subtraction hybridization (RaSH). In our study, this method was applied to samples of endometriotic lesions from affected women and to biopsies of endometrium of healthy women without endometriosis, where we could identify 126 deregulated genes. To evaluate the expression of genes found by RaSH method, we measured LOXL1, HTRA1, and SPARC genes by real-time polymerase chain reaction. Significant different expression was obtained for HTRA1 and LOXL1, upregulated in the ectopic endometrium, suggesting that these genes are involved in the physiopathology of endometriosis and may favor the viability of endometrial cells at ectopic sites.     

Histocompatibility leukocyte antigen-G is not expressed by endometriosis or endometrial tissue

OBJECTIVE: The immunological mechanisms that support persistence and proliferation of ectopic endometrial implants within the peritoneal cavity of women with endometriosis are unknown. Inhibition of natural killer (NK) and cytotoxic T-cell function has been proposed as a mechanism. We tested the hypothesis that expression of a nonclassical major histocompatibility antigen, HLA-G, might explain the local immunosuppression associated with ectopic endometrium. DESIGN: Nested case-control study of women with and without laparoscopic evidence of endometriosis. SETTING: Reproductive endocrinology clinic at a university hospital. PATIENT(S): Peritoneal fluid specimens from 10 women with revised AFS stage I-IV endometriosis and from 10 age-matched normal controls without laparoscopic evidence of endometriosis were tested for the presence of HLA-G protein. Endometriosis and normal endometrial biopsies from four patients were used to prepare stromal cell cultures directly evaluated for HLA-G protein. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): The expression of HLA-G in peritoneal fluid, tissue, and cell cultures was determined by immunoblotting with a specific monoclonal antibody. RESULT(S): HLA-G protein was not detectable in peritoneal fluid specimens of endometriosis patients or controls. Moreover, ectopic and normal endometrial tissues and stromal cells did not express HLA-G. CONCLUSION(S): Immune cell inhibition in endometriosis must be mediated by factors other than HLA-G.     

Abnormal interleukin 1 receptor types I and II gene expression in eutopic and ectopic endometrial tissues of women with endometriosis

Interleukin-1 (IL1) is believed to play a central role in the immuno-inflammatory process associated with endometriosis. IL1 triggers cell activation via its receptor type I (IL1R1), but its receptor type II (IL1R2) is known instead as a scavenger that buffers the cytokine's effects. Our previous studies have shown increased expression of IL1R1 in active endometriotic implants compared to normal and endometriosis women-derived endometrial tissues, and a simultaneous decrease in IL1R2 expression at the protein level. In the present study, in situ hybridization demonstrated a noticeable decrease in IL1R2 mRNA hybridization score in eutopic and matched ectopic endometrial tissues of women with endometriosis compared to normal women in the stroma (P<0.001 and P<0.001, respectively) and the epithelium (P<0.01 and P<0.05, respectively), whereas IL1R1 mRNA hybridization score was higher only in the ectopic implants, with a statistically significant difference in the stroma (P<0.05). This was corroborated by RT-PCR analysis of IL1R1 and IL1R2 mRNAs in ectopic (P<0.05 and P<0.05, respectively) and matched eutopic (P=0.22 and P<0.05, respectively) endometrial tissues from women with endometriosis compared to endometrial tissues from normal women. The decrease in IL1R2 mRNA levels in eutopic endometrial tissue of endometriosis women, and the concomitant increase in IL1R1 mRNA levels in ectopic implants, reveal a profound defect in IL1R 1 and IL1R2 gene expression which may accentuate the capability of this tissue to respond to IL1 and favor its ectopic growth.     

Xanthine oxidase in eutopic and ectopic endometrium in endometriosis and adenomyosis

OBJECTIVE: To investigate the expression of xanthine oxidase in eutopic and ectopic endometrium in endometriosis and adenomyosis. DESIGN: Immunohistochemical identification of xanthine oxidase in endometrial tissues by using polyclonal antibody. SETTING: University hospital. PATIENT(S): Thirty-four women with endometriosis, 34 women with adenomyosis, and 44 fertile control women. INTERVENTION(S): Biopsy samples were obtained from the endometrium throughout the menstrual cycle. MAIN OUTCOME MEASURE(S): Semiquantitative immunostaining (evaluation nomogram) score of endometrial cells. RESULT(S): The level of xanthine oxidase expression in the glandular epithelium of control varied according to menstrual phase, but no such variation in expression was seen in endometriosis. Variation in xanthine oxidase expression was observed during the menstrual cycle in patients with adenomyosis; this variation differed completely from that in controls. Xanthine oxidase expression was found in ectopic endometrial tissue in all cases. The mean evaluation nomogram levels in the glandular epithelium in adenomyosis tissue were as high as those in the early secretory phase in the eutopic endometrium. CONCLUSION(S): Aberrant expression of xanthine oxidase in eutopic and ectopic endometrium appears to play a pathologic role in endometriosis and adenomyosis.     

Peritoneal fluid-mediated enhancement of eutopic and ectopic endometrial cell proliferation is dependent on tumor necrosis factor-alpha in women with endometriosis

OBJECTIVE: To determine the effect of autologous peritoneal fluid and tumor necrosis factor-alpha (TNF-alpha) on proliferation of endometrial cells from women with endometriosis. DESIGN: Endometrial cells from eutopic and ectopic endometrium were cultured in vitro with peritoneal fluids or recombinant TNF-alpha for 72 hours before DNa synthesis determination by 3H-thymidine labeling and liquid scintillation counting. SETTING: An institute for the study and treatment of endometriosis and university-based research laboratories. PATIENT(S): Thirty-five women with endometriosis and 17 controls without endometriosis. MAIN OUTCOME MEASURE(S): In vitro incorporation of 3H-thymidine in endometrial cells was examined. RESULT(S): Peritoneal fluid from women with endometriosis enhanced proliferation of autologous and heterologous endometrial cell cultures from women with endometriosis. The soluble TNF-receptor etanercept blocked the ability of peritoneal fluid from women with endometriosis to enhance proliferation of eutopic or ectopic endometrial cells. Recombinant TNF-alpha also enhanced proliferation of eutopic and ectopic endometrial cells from women with endometriosis. In contrast, autologous peritoneal fluid, heterologous peritoneal fluid from women with endometriosis, and recombinant TNF-alpha failed to enhance, and often inhibited, the proliferation of eutopic endometrial cells from controls without endometriosis. CONCLUSION(S): Endometrial cells from women with endometriosis can utilize factors in peritoneal fluids, such as TNF-alpha, to facilitate proliferation in ectopic environments. Endometrial cells from women without endometriosis do not share this ability, suggesting that this abnormality is etiologically related to development of the disease. Therapy with agents that block the effects of TNF-alpha may be warranted.     

Reduced progesterone action during endometrial maturation: a potential risk factor for the development of endometriosis

OBJECTIVE: To discuss the role that reduced endometrial responsiveness to progesterone (P) might play in the pathophysiology of endometriosis. DESIGN: A review of experimental evidence regarding the failure of P to regulate the expression of matrix metalloproteinases (MMPs) in the endometrium of patients with endometriosis. CONCLUSION(S): Progesterone and locally produced differentiation factors act cooperatively to reduce MMP expression by maternal endometrial cells within the pro-inflammatory micro-environment of early pregnancy. Our in vitro studies with normal human endometrium demonstrate that prior P exposure not only down-regulates MMP expression, but also limits the ability of locally produced proinflammatory cytokines to stimulate expression of these enzymes. In contrast, endometrial tissues from women with endometriosis demonstrate an altered response to P, allowing a continuous expression of MMPs throughout the secretory phase. Although the factors that influence the loss of P sensitivity in the endometrium of patients with endometriosis have not yet been defined, alterations in cell-cell communication seem to contribute to dysregulated MMP expression. Specifically, proinflammatory cytokines produced by epithelial cells oppose stromal cell responses to P, inhibiting production of key differentiation factors necessary for cell-specific MMP regulation. The resulting loss in normal MMP regulation enhances the invasive capacity of endometrial tissue, promoting ectopic establishment in an experimental model.     

Polo-样激酶1在子宫内膜异位症患者在位和异位子宫内膜中的表达

目的探讨Polo－样激酶1（PLK1）在子宫内膜异位症发生发展中的作用。方法采用逆转录（RT—PCR）、蛋白免疫印迹法（Western blotting）及免疫组织化学的方法检测子宫内膜异位症患者的异位子宫内膜组织29例和在位子宫内膜组织20例及正常子宫内膜组织30例中PLK1的表达。结果PLK1蛋白在内异症组增殖期异位（2．19±0．63）和在位子宫内膜组织（1．78±0．59）上的表达量明显高于对照组子宫内膜组织（1．21±0．30）上的表达量（P〈0．05）。PLK1蛋白在内异症组分泌期异位（1．15±0．332）和在位子宫内膜组织（1．00±0．33）上的表达量明显高于对照组子宫内膜组织（0．82±0．24）上的表达量（P〈0．05）。内异症组增殖期和分泌期异位和在位子宫内膜组织上PLK1的表达量比较,差异均无统计学意义（P〉0．05）。结论PLK1蛋白的高表达可能与子宫内膜异位症的发生发展有关。     

TWEAK在子宫内膜异位症在位和异位内膜上的表达

目的:探讨肿瘤坏死因子样凋亡的微弱诱导剂(TWEAK)在子宫内膜异位症(EMs)发病的关系。方法:采用实时定量逆转录-聚合酶链反应(Real-time RT-PCR)和免疫组化、Western Blot方法检测EMs患者在位内膜、异位病灶中TWEAK mRNA和蛋白的表达,并与正常对照子宫内膜比较。结果:TWEAK蛋白表达于子宫内膜的腺上皮细胞和间质细胞的胞浆内。与正常对照组内膜和在位组内膜相比,TWEAK mRNA和蛋白在异位内膜上表达量下调(P<0.05),且无论是EMs在位内膜还是对照组内膜,其增生期TWEAK mRNA表达明显低于分泌期(P<0.05)。结论:TWEAK在子宫内膜中表达,表达量在分泌期明显升高。EMs患者异位子宫内膜TWEAK表达降低,可能导致子宫内膜细胞的凋亡水平下降,参与EMs的发生发展过程。     

Apoptosis and expression of Bcl-2 and Bax in eutopic endometrium from women with endometriosis

OBJECTIVE: To evaluate and compare spontaneous apoptosis and Bcl-2 and Bax expression in eutopic endometrium from women with and without endometriosis. DESIGN: Apoptosis and Bcl-2 and Bax expression were examined in eutopic endometrium from women with and without endometriosis. SETTING: Instituto de Biología y Medicina Experimental-CONICET, Department of Gynecology and Department of Gynecological Pathology, Clínicas University Hospital, Buenos Aires, Argentina. PATIENT(S): Women with untreated endometriosis (n = 14) and controls (n = 16). INTERVENTION(S): Collection of endometrial samples during diagnostic or therapeutic laparoscopy. MAIN OUTCOME MEASURE(S): Apoptotic cells were detected with use of the dUTP nick-end labeling (TUNEL) assay; Bcl-2 and Bax expressions were assessed with use of immunohistochemical techniques. RESULT(S): Spontaneous apoptosis was significantly lower in eutopic endometrium from patients with endometriosis, compared with healthy controls (2.26 +/- 0.53 and 9.37 +/- 1.69 apoptotic cells/field, respectively) and was independent of cycle phase. An increased expression of Bcl-2 protein was found in proliferative eutopic endometrium from patients with endometriosis. Bax expression was absent in proliferative endometrium, whereas there was an increase in its expression in secretory endometrium from both patients and controls. CONCLUSION(S): Women with endometriosis show decreased number of apoptotic cells in eutopic endometrium. The abnormal survival of endometrial cells may result in their continuing growth into ectopic locations.     

The role of endometrium in endometriosis

Endometriosis is defined as the presence of endometrial glands and stroma outside the uterus. Several theories have been proposed to explain the pathogenesis of this disease. According to Sampson's retrograde menstruation theory, endometrial cells are refluxed through the fallopian tubes during the menstruation and implant onto peritoneum or pelvic organs. Since retrograde menstruation is a very common phenomenon among women of reproductive age, there must be other factors that may contribute to the pathophysiology and/or pathogenesis of endometriosis. Genetic predisposition, environmental factors, and alterations in immune and endocrine functions are believed to play significant roles in the establishment and maintenance of endometriosis. Although the eutopic endometriums of women with and without endometriosis are histologically similar, studies revealed that there are many fundamental differences between these two tissues. Invasive properties, decreased apoptosis, alterations in expression of specific gene and proteins, and increased steroid and cytokine production have been identified in eutopic endometrium of women with endometriosis. Furthermore, significant biochemical differences exist even between ectopic and autologous eutopic endometrium. These differences can be explained by the direct effects of an inflammatory peritoneal environment.