**2.4 Hormones**

Serum and PF hormones levels vary in patients affected with endometriosis. Luteinizing hormone (LH) levels are significantly higher in both serum and PF in patients with endometriosis than in normal controls (Illera et al., 2001). However, levels of prolactin, thyroid stimulating hormone (TSH) and follicle stimulating hormone (FSH) in the serum were no different between the different groups.

Recently it was reported that serum concentrations of leptin are increased in patients with endometriosis. This increase may play an anti-apoptotic role in activated endometrial stromal cells into the peritoneal cavity, stimulating endometrial cell implantation and cause infertility (Tanaka et al., 2003). Furthermore another study measured the serum concentration of leptin using a radioimmunoassay method, showing a significant association between leptin concentrations and stage of endometriosis (Viganò et al., 2002).

#### **2.5 Proteolytic enzymes and their inhibitors**

The physiological changes in endometriosis involve multiple steps of matrix remodelling. Endometriosis associated to abnormal matrix remodelling is affected by several molecular factors including proteolytic enzymes and their inhibitors, which mediate tissue turnover, and ovarian steroids, which normally regulate reconstruction of endometrium in the menstrual cycle.

The extracellular matrix (ECM) constitutes a well-organized network structure that surrounds the cells. The tissue remodelling involving ECM turnover is regulated by the pooled action of proteolytic enzymes, matrix metalloproteinases (MMP) and tissue inhibitors for MMP (TIMP). The inappropriate expression of MMP and TIMP is associated with tumorigenesis and metastasis, as well as with endometriosis.

Current Insights and Future Advances in Endometriosis Diagnostics 427

expressed in the cell-to-cell boundaries of the endometrium. It is reported that E-cadherin expression on the endometrium was higher in the secretory phase than in the proliferative phase, although there is one report that the expression was unchanged during the cycle. Furthermore, the level of E-cadherin in serum of endometriosis patients was significantly

The level of E-cadherin in the serum of both III stage and IV stage endometriosis patients was higher than that of I and II stage patients. However, the difference between them was not statistically significant. E-cadherin may play a role on the morbidity of endometriosis and the serum E-cadherin assay might be helpful as a serum marker for the diagnosis and

Environmental toxins, such as dioxins and polychlorinated biphenyls are some of the factors that have been suggested to play a significant role in the development of endometriosis. In fact, detection of environmental contaminant residues in serum and ovarian follicular fluid confirms this hypothesis. Dioxin-like chemicals, such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and polyhalogenated aromatic hydrocarbons (PHAHs), may exert effects on the pathophysiology of endometriosis through a number of pathways: (1) activation of procarcinogens; (2) altered synthesis and metabolism of estradiol; (3) altered production of proinflammatory growth factors or cytokines and (4) alterations in tissue remodelling

Exposure to HAHs and TCDD seems to be associated with a dose-dependent increase in the incidence and severity of endometriosis. TCDD may target peripheral blood and peritoneal and endometrial leukocyte populations inducing chronic expression of TNF-α and other inflammatory mediators resulting in increased adhesion, vascularization and proliferation of endometriotic cells. It has been suggested that an elevated concentration of TNF-a might participate in TCDD-mediated toxicity and contribute to the pathogenesis of endometriosis. Dioxins may affect the expression of TNF-α via the induction of an inflammatory cytokine network, since the region of DNA that recognize the ligand-activated AhR, the dioxinresponse element of DRE, is present in the genes of potent inducers of TNF-α including IL-

The adhesion of endometrial cells to the extracellular matrix (ECM) would be expected to play a central role in the pathogenesis of endometriosis. Various cell adhesion molecules (CAMs) have been investigated for their expression in endometriotic endometrium. Each cell type expresses a distinct pattern of integrins and other CAMs, including the cadherins, selectins and members of the immunoglobulin family that determines cell shape, maintains cell position and polarity and affects hormonal responsiveness. In addition, apoptosis might be mediated through loss of appropriate signals from the ECM through alternations in the integrin expression. Based on cell adhesion and the genes involving in adhesion and invasion aspects, cell adhesion molecules (CaMs) and proteolytic enzymes were investigated

for their mechanisms in association with the progression of endometriosis.

higher than that of control group.

**2.7 Environmental contaminant** 

1b, IL-6 and IFN-γ (Rier & Foster, 2003).

**3. Endometrial markers** 

processes.

management of endometriosis (Fu & Lang, 2002).

Several MMP have been implicated in the development of endometriosis (Sillem et al., 2001). The levels of MMP and TIMP in patients with endometriosis are different depending on the method of measurement and collection of samples of different tissues at different stages of endometriosis. The values of TIMP-1 is determined by radioimmunoassay measurement in serum of patients with PF in endometriosis are lower than in controls. In contrast, the concentration of TIMP-1 was restored after treatment with gonadotropin releasing hormone. Another study reported that there was no significant difference in levels of cathepsin D, a proteolytic enzyme thought to promote digestion of ECM proteins in endometriosis, in serum from women with and without endometriosis.

#### **2.6 Soluble adhesion molecules**

It is thought that the retrograde flow of the menstrual debris to the peritoneal cavity plays an important role in the origin of endometriosis but the mechanism of endometrial cells implantation remains unknown. Recently many studies have reported the importance of adhesion molecules in this process.

Several adhesion molecules (CAM) are expressed in the human endometrium: i.e. integrins, cadherins and immunoglobulin superfamilies. These adhesion molecules show cyclical changes during the menstrual cycle. The major cell surface receptors of the ECM are the *integrins* that contain large (α) and small (β) subunits.

β1-integrins are known to mediate the interaction between the cell-cell and cell-extracellular matrices and are represented by very late activation (VLA) antigen molecules. It is well known that endometriosis is frequently associated with immunological abnormalities. However, only a few studies have been conducted on the adhesion molecules, particularly on β 1-integrins, in endometriosis. It has reported that integrins are expressed in the endometrium in endometriosis. The ability of endometriotic tissues to express integrins may explain the high recurrence rates in patients with endometriosis, as these samples retain their adhesion potency after retrograde menstruation and are thus able to establish cell-cell and cell-matrix interactions with the surrounding peritoneum.

The soluble forms of the *intercellular-adhesion molecule-1 (sICAM-1)* are secreted from the endometrium and endometriotic implants. Moreover, endometrium from women with endometriosis secretes a higher amount of this molecule than tissue from women without the disease. Consequently, a strong correlation exists between levels of sICAM-1 and the number of endometriotic implants in the pelvis. Therefore, it has been hypothesized that sICAM-1 may be useful in the diagnosis of endometriosis (Leng et al., 2002). Many investigators have reported a significant increase in serum concentration of sICAM-1 in patients with endometriosis. The sICAM-1 concentrations were higher in patients with stage I−II endometriosis, suggesting that studies on these soluble adhesion molecules can help clarify the pathogenic mechanisms of endometriosis. Elevated ICAM-1 levels were found in patients with severe endometriosis, but its sensitivity is not high and the concomitant use of the CA125 marker increases the sensitivity and specificity of detection (Somigliana et al., 2002).

The **E-cadherin** mediates cell-cell interaction and cells adhere preferentially to cells that express the same cadherin. Cadherins are distributed widely among animals and play a potentially significant role in morphogenetic events during embryogenesis. Cadherin is also expressed in the cell-to-cell boundaries of the endometrium. It is reported that E-cadherin expression on the endometrium was higher in the secretory phase than in the proliferative phase, although there is one report that the expression was unchanged during the cycle. Furthermore, the level of E-cadherin in serum of endometriosis patients was significantly higher than that of control group.

The level of E-cadherin in the serum of both III stage and IV stage endometriosis patients was higher than that of I and II stage patients. However, the difference between them was not statistically significant. E-cadherin may play a role on the morbidity of endometriosis and the serum E-cadherin assay might be helpful as a serum marker for the diagnosis and management of endometriosis (Fu & Lang, 2002).
